The Southern Hemisphere westerly winds are among the most
important drivers of recently observed environmental changes in West
Antarctica. However, the lack of long-term wind records in this region
hinders our ability to assess the long-term context of these variations. Ice
core proxy records yield valuable information about past environmental
changes, although current proxies present limitations when aiming to
reconstruct past winds. Here we present the first regional wind study based
on the novel use of diatoms preserved in Antarctic ice cores. We assess the
temporal variability in diatom abundance and its relation to regional
environmental parameters spanning a 20-year period across three sites in the
southern Antarctic Peninsula and Ellsworth Land, Antarctica. Correlation
analyses reveal that the temporal variability of diatom abundance from high-elevation ice core sites is driven by changes in wind strength over the core
of the Southern Hemisphere westerly wind belt, validating the use of diatoms
preserved in ice cores from high-elevation inland sites in the southern
Antarctic Peninsula and Ellsworth Land as a proxy for reconstructing past
variations in wind strength over the Pacific sector of the Southern
Hemisphere westerly wind belt.
Introduction
Winds over the Southern Ocean (circumpolar westerlies) play a key role in
driving the exchange of heat and carbon dioxide between the ocean and
atmosphere (Russell et al., 2006; Quéré et al., 2007; Hodgson and
Sime, 2010; Landschutzer et al., 2015). In recent decades, the circumpolar
wind belt has increased in strength and has shifted towards the Antarctic
continent, constituting one of the strongest climatic trends in the Southern
Hemisphere (Thompson and Solomon, 2002; Gille et al., 2008; Young et al., 2011). These atmospheric changes have been linked as drivers of the
widespread warming observed in the Antarctic Peninsula (AP) (Orr et al., 2004; Van Den Broeke and Van Lipzig, 2004; Marshall et al., 2006; Thomas et al., 2009; Thomas and Tetzner, 2018; Turner et al., 2020) and West
Antarctica (WA) (Thomas et al., 2013) and as the mechanism behind the
enhanced upwelling of deep and relatively warm, CO2-rich oceanic water
(Nakayama et al., 2018). The upwelling of circumpolar deep water has been
shown to promote accelerated melting and thinning at the base of the ice
shelves (Thoma et al., 2008; Jacobs et al., 2011; Pritchard et al., 2012;
Steig et al., 2012; Wåhlin et al., 2013; Dutrieux et al., 2014; Favier
et al., 2014; Gille et al., 2014; Joughin et al., 2014; Paolo et al., 2015;
Holland et al., 2019), thus threatening the stability of floating ice
shelves along the coastline of the Amundsen–Bellingshausen seas and
ultimately contributing to global sea level rise (Pritchard et al., 2012).
Changes in the circumpolar westerlies have also been linked to an observed
pattern of increased snow accumulation in Antarctica over the 20th century, which has mitigated global mean sea level rise (Medley and Thomas, 2019). To assess the context of these recent wind changes, an extended record of wind strength is needed.
Direct meteorological observations in the AP region are sparse, relatively
short-term and mostly constrained to coastal regions (Lazzara et al., 2012;
Oliva et al., 2017; Thomas and Tetzner, 2018; Turner et al., 2020). The
scarcity of continuous long-term data can be partly addressed by using
climate reanalyses datasets. These datasets comprise model outputs from
simulations that are used to interpolate measured climate variables,
providing accurate meteorological data in this region for the satellite era
(1979–present) (Tetzner et al., 2019; Dong et al., 2020; Zhu et al., 2021),
but are not viable for studying pre-satellite regional climate variability.
Climate models can be used to extend the record back in time; however, model
simulations from the Fifth Coupled Model Intercomparison Project (CMIP5)
exhibit strong biases over the Southern Ocean compared with observations
(Bracegirdle et al., 2013). Overall, the lack of long-term wind records in
the region hinders the possibility to assess the long-term context of the
recently observed changes.
Ice cores provide valuable climatic information over a range of timescales
(Legrand and Mayewski, 1997). Insoluble mineral dust concentrations in
Antarctic ice cores have been widely used to infer past variability in
regional-to-hemispheric atmospheric circulation (Röthlisberger et al., 2002; Lambert et al., 2008; Koffman et al., 2014; Delmonte et al., 2020;
Laluraj et al., 2020). Geochemical tracers of mineral dust, such as the
non-sea-salt component of soluble calcium (nssCa2+) or potassium
(nssK+), have been used to track changes in the strength and position
of the Southern Hemisphere westerly wind (SHWW) belt (Dixon et al., 2012;
Mayewski et al., 2013). However, these traditional proxies typically
originate from South America, Australia and New Zealand, and local Antarctic
ice-free areas and are therefore potentially influenced by environmental
changes in these distal source regions (McConnell et al., 2007; Lambert et
al., 2008; Li et al., 2010; Wolff et al., 2010; Bullard et al., 2016;
Delmonte et al., 2017). Sea salt sodium (ssNa+) has been previously
interpreted as a proxy for increased meridional transport from the Southern
Ocean to ice core sites in Antarctica (Kreutz et al., 2000; Goodwin et al., 2004; Kaspari et al., 2005; Mayewski et al., 2013; Vance et al., 2013).
However, the ssNa+ signal is potentially influenced by inputs from
blowing snow above sea ice (Frey et al., 2020) and by the production of
ssNa+ in “frost flowers”, as well as by inputs from the open ocean
(Huang and Jaeglé, 2017). As frost flowers are precipitated from the
surface of freshly formed sea ice (Wagenbach et al., 1998; Rankin et al., 2000) and all these sources are affected by sea ice extent, some studies
have reflected on the potential of the ssNa+ ice core record from
Antarctic coastal sites as a proxy for seasonal sea ice extension (Rankin et
al., 2002; Wolff et al., 2003, 2006). These conflicting
sources of ssNa+ suggest that the variability of the ssNa+ record
is not entirely driven by changes in winds or atmospheric circulation. The
current limitations identified in conventional ice core wind and atmospheric
circulation proxies highlight the need to explore new species to reconstruct
wind strength.
Diatoms entrained in Antarctic snow and ice have recently been proposed as
an alternative source of information about winds (Allen et al., 2020).
Diatoms are unicellular algae with siliceous cell walls that inhabit marine,
brackish and freshwater environments throughout the world (Smol and
Stoermer, 2010). Despite their aquatic habitats, several studies support
the idea that they can be airborne (Chalmers et al., 1996; Gayley et al., 1989;
Lichti-Federovich, 1984; McKay et al., 2008; Wang et al., 2008; Harper and
Mackay, 2010; Spaulding et al., 2010; Hausmann et al., 2011; Budgeon et al., 2012; Papina et al., 2013; Fritz et al., 2015). Airborne diatoms can be
sourced from both exposed diatom-bearing sediments and modern water bodies
(e.g. oceans, streams, lakes) (Harper and McKay, 2010). Marine diatoms can
be effectively lifted from the sea surface microlayer into the atmosphere by
wind-induced bubble-bursting and wave-breaking processes (Cipriano and
Blanchard, 1981; Farmer et al., 1993). Once in the atmosphere, they can be
transported by winds over long distances (Chalmers et al., 1996; Elster et al., 2007; Harper and McKay, 2010; Budgeon et al., 2012; Marks et al., 2019;
Allen et al., 2020). Diatom records have been evaluated at multiple ice core
sites in the AP and Ellsworth Land (EL) regions (Tetzner et al., 2022a) to
reveal consistent spatial variations and increases in the diatom
concentration during the past 3 decades. Despite the potential the
diatom record has shown to reconstruct past wind strength, this proxy
requires evaluation against more established ice core wind and atmospheric
circulation proxies.
In this study, we evaluate the potential for diatoms to reconstruct regional
wind strength using an array of three shallow-depth ice cores drilled in the
AP and EL regions. We investigate the relationship between diatom abundance
and changes in environmental parameters to assess the regional consistency
of the diatom-based wind proxy. We expand these analyses by comparing the
diatom record to traditional ice core wind and atmospheric circulation
proxies based on major ions and dust.
MethodsIce core records and age scales
Three ice cores and firn cores from the southern AP and EL were included in
this study (Fig. 1, Table 1). The Jurassic ice core (JUR, 140 m) was
drilled in the vicinity of Jurassic Nunatak using the BAS electromechanical
drill during the austral summer 2012–2013. The Sky-Blu firn core (SKBL, 21.8 m) from the vicinity of Sky-Blu Field Station, southern AP, and the Sherman Island firn core (SHIC, 21.3 m) from Eights Coast were drilled using a
Kovacs hand auger during the austral summer 2019–2020; hereafter, for
practical reasons, firn cores will be referred to as ice cores. For JUR,
SKBL and SHIC, an ice core chronology was established (Tetzner et al., 2022a) based on their hydrogen peroxide (H2O2) annual cycle that
is assumed to peak during the austral summer solstice and to exhibit its
minimum during the austral winter (Frey et al., 2006; Thomas et al., 2008).
Ice core chronologies were corroborated using the annual cycle of the
non-sea-salt component of major ions, such as non-sea-salt sulfate
(nssSO42-) (Piel et al., 2006), that is assumed to peak between
November and January in this region (Pasteris et al., 2014; Thoen et al., 2018). Ice core chronologies were corroborated with the presence of volcanic tephra in the 2001 CE ice core layer (Tetzner et al., 2021b). The top 15 m of SKBL included in this work and the full SHIC core were dated back to 1999 CE, and the top 36.90 m of JUR included in this work dated back to 1992 CE. The estimated dating error is ±3 months for each year with no accumulated error.
Map showing the location of the ice core sites and main oceanographic features considered in this study. The red circles show the locations of the three ice core sites. The pale green line shows the median September sea ice extension between 1980 and 2010 CE, and the pale green area represents the seasonal sea ice zone (SSIZ). The red line shows the median February sea ice extension between 1980 and 2010 CE, and the pale red area represents the perennial sea ice zone (PSIZ). SAF: Sub-Antarctic Front.
APF: Antarctic Polar Front. CP: coastal polynya. EI-C: Eights Coast. BC: Bryan Coast. ASE: Amundsen Sea Embayment. PAL: Palmer ice core site. FER: Ferrigno ice core site. AP: Antarctic Peninsula.
Summary of each ice core geographical location and main features
analysed in this study. SIE: sea ice edge (*) – the distance from SIE reported corresponds to the median for years covering the data interval.
September SIE values used for calculations were obtained as the distance between
the ice core site and the closest point in the northern limit of 15 % sea
ice cover. February SIE values used for calculations were obtained as the
distance between the ice core site and the closest sea-ice-free region.
CoreLongLatElevationAnnual record Total depthDistance from name(m a.s.l.)used (m)SIE (km)*Years (CE)No. samplesSeptemberFebruaryJUR-73.06-74.3311391992–20122036.91045140SKBL-71.59-74.8514191999–20192015.01148200SHIC99.63-72.674741999–20192021.3753130Sample preparation and analyses
All ice cores included in this study were cut using a bandsaw with a steel
blade. Discrete ice core samples were cut at 5 cm resolution for ion
chromatographic analyses using reagent-free Dionex ICS-2500 anion and IC 2000 cation systems in a class-100 clean room. Major ion concentrations were
used to calculate the ionic contributions from marine and continental
sources. The marine sea salt fraction of sodium (ssNa+) and the non-sea-salt fraction of calcium (nssCa2+) were calculated using Eqs. (1)
and (2):
1[ssNa+]=[Na+]-[nssCa2+]/Rcrust,2[nssCa2+]=[Ca2+]-[ssNa+]×RseawaterCa/Na,
where Rcrust and RseawaterCa/Na are the mean ratios (weight
by weight – w/w) of Ca/Na in the Earth's crust (RcrustCa/Na=1.78) and in bulk seawater (RseawaterCa/Na=0.038), respectively (Bowen, 1979). The non-sea-salt fraction of potassium (nssK+) was calculated using Eq. (3):
[nssK+]=[K+]-[ssNa+]×RseawaterK/Na,
where RseawaterK/Na is the mean ratio (weight by weight – w/w) of K/Na in bulk seawater (RseawaterK/Na=0.036) (Piel et al., 2006).
Microparticle concentration (MPC) was measured on each ice core using a
flow-through Klotz Abakus laser particle counter connected to a continuous
ice core melter system at the British Antarctic Survey (Grieman et al., 2021).
Diatom samples from each ice core site were previously analysed and reported
by Tetzner et al. (2022a). All diatom samples were extracted by filtration.
Ice core meltwater was filtered through polycarbonate membrane filters (pore
diameter 1.0 µm) and subsequently scanned in a scanning electron
microscope (SEM) following the method presented in Tetzner et al. (2021a).
Observations of diatom preservation were based on the visual identification
of characteristic frustule dissolution features and degradation described in
Warnock and Scherer (2015). Diatom frustules and fragments less than 5 µm were excluded from counting and identification. Diatom counts per sample (n) included all diatom valves, partially obscured diatom valves and
diatom fragments identified in each sample. After processing, diatom counts
per sample (n) were represented as their temporal equivalent, diatom
abundance (n per year). The diatom abundance parameter includes all diatoms
and diatom remains identified on each sample, regardless of their potential
source. As reported by Tetzner et al. (2022a), the diatom assemblages at all
ice core sites presented in this study are primarily comprised of
Fragilariopsis cylindrus, Fragilariopsis pseudonana, Pseudonitzschia spp., Shionodiscus gracilis and Cyclotella group., with the exclusive presence of other diatom species at each site (Appendix A – Table A1).
All correlations are based on linearly detrended data and calculated using
the Pearson's linear correlation (R). Time series linear correlations were
calculated over a 20-year period (1992–2012 CE for JUR and 1999–2019 CE for SHIC and SKBL). Seasons are reported as austral summer (December to
February, DJF), autumn (March to May, MAM), winter (June to August, JJA) and
spring (September to November, SON).
Climate reanalyses and sea ice extension data
Monthly reanalysis fields from the fifth generation of the European Centre
for Medium-Range Weather Forecasts (ECMWF), ERA5 (Hersbach and Dee, 2016),
were used to obtain spatial correlations between ice core records and
environmental parameters. Three fields were used to perform spatial
correlation analyses: wind speed (10 m wind speed), precipitation and sea
ice cover. ERA5 datasets provide hourly data available at 0.25∘
resolution (∼31 km) since 1979 CE.
Sea ice extension data were obtained from the Sea Ice Index version 3
dataset (Fetterer et al., 2017) from the National Snow and Ice Data Centre
(NSIDC), providing monthly sea ice concentrations at 25 km resolution from
1979 to 2021 CE. September sea ice limits (defined as the median northerly
extent of 15 % sea ice cover) were considered the annual sea ice maximum
and February sea ice limits (defined as the median northerly extent of
15 % sea ice cover) were considered the annual sea ice minimum (Thomas et
al., 2019).
Statistical analyses
For each ice core site, the diatom abundance was compared to conventional
ice core wind and atmospheric circulation proxies (ssNa+, nssCa2+,
nssK+ and MPC) and to records of methane sulfonic acid (MSA), a
traditional sea ice proxy. All correlations were based on annual averages
(winter-to-winter). The correlation of chemical, MPC and diatom abundance
records across all ice core sites was carried out using the flux parameter
(except for diatom abundance). Annual fluxes were calculated after
multiplying the annual mean concentration by the estimated annual snow
accumulation (mm of water equivalent). Spatial correlations were calculated
using chemical and MPC mean annual concentrations and diatom abundance.
Spatial correlations were generated using the field correlation tool from
the Royal Netherlands Meteorological Institute (KNMI) Climate Explorer
(https://climexp.knmi.nl/start.cgi, last access: 1 July 2021). Spatial correlations were based on linearly detrended data and calculated using the Pearson's linear
correlation (R) over the South Pacific sector from 180 to
60∘ W and 40 to 90∘ S, which was selected based on
air mass pathways reaching the ice core sites (Thomas and Bracegirdle,
2015). Based on the records of September sea ice cover between 1992 and 2020 CE (Fetterer et al., 2017), spatial correlations for sea ice cover were
calculated over a reduced region (between 180 to 60∘ W and 55 to 90∘ S). All linear correlations were calculated over a 20-year period (1992–2012 CE for JUR and 1999–2019 CE for SHIC and SKBL). The MPC record from JUR covers the interval 1992–2011 CE; therefore, correlations calculated using this parameter at JUR are calculated over a 19-year period. Since diatom concentrations at SHIC peak during the austral summer (Tetzner et al., 2022a), spatial correlations for the SHIC diatom record were also calculated over a 6-month period covering the austral spring and summer season (September–February).
ResultsJurassic ice core (JUR)Chemistry, MPC and diatom abundance annual records
The JUR chemical fluxes, MPC flux and diatom abundance records are
characterized by positive trends during the 1992-2012 CE period, with the
exception of the MSA flux, which exhibits a negative trend (Fig. 2, Table S1 in the Supplement). Of them, only the nssCa2+ flux and nssK+ fluxes were statistically significant (p<0.05) (Table S1). The nssCa2+ flux shows a steady increase, reaching a maximum between 2010 and 2011 CE. The nssK+ flux shows a similar pattern with values increasing steadily after 2002 CE. The ssNa+ flux is moderately variable from 1992 to 2012 CE, with an overall increase between 2000 and 2002 CE. The MSA flux displays an overall decrease between 1992 and 2003 CE, followed by a general increase during 2003 and 2012 CE. Similarly, the MPC exhibits an increase during 1992–2012 CE with its lowest values during 1998 CE. The diatom abundance is moderately variable between 1992 and 2004 CE, followed by a marked increase after 2004 CE, reaching its highest value during 2009–2010 CE (Fig. 2). Similar features were present in the JUR chemical and MPC concentration records (Table S2 and Fig. S1 in the Supplement).
Time series of chemical species fluxes, MPC flux and diatom abundance for each ice core site. Data points represent the annual austral winter-to-winter average and were plotted over the correspondent austral summer. Colour-coded dashed lines show statistically significant linear trends (p<0.05). The MPC flux record from JUR covers the interval 1992–2011 CE. Data presented in panel (a) were previously presented by Tetzner et al. (2022a).
Environmental correlations
All records (excluding MSA) presented strong and significant correlations
with wind strength (R≤-0.6 and R≥0.6, p<0.05; Appendix B – Fig. B1). Diatom abundance is positively correlated with wind
strength (0.45≤R≤0.67, p<0.05) over a latitudinal band at
the northern limit of the Amundsen Sea (∼60∘ S) and negatively correlated with the sea ice cover north of the SHIC ice core
drilling site (-0.45≥R≥-0.69, p<0.05) (Fig. 3). The MPC
is positively correlated with wind strength over the east coast of Argentina
(0.6≤R≤0.73, p<0.05). The nssCa2+ exhibits a positive correlation with wind strength (0.6≤R≤0.62, p<0.05) and with precipitation (0.6≤R≤0.77, p<0.05) off the western coast of southern South America. The nssK+ shows a positive correlation with wind strength (0.6≤R≤0.66, p<0.05) over the Amundsen Sea. The ssNa+ is positively correlated with wind strength over the Drake Passage (0.6≤R≤0.7, p<0.05) and over Ellsworth Land (0.6≤R≤0.63, p<0.05). No significant correlations were identified with wind strength or precipitation at or near the JUR ice core drilling site. No strong correlations (R≥0.6 or R≤-0.6) between the MSA record and sea ice cover were identified in the region.
Regional maps showing spatial correlations between environmental
parameters and diatom abundance. Colour-coded polygons in the maps indicate
highly correlated regions (R≥0.45 or R≤-0.45). All polygons
plotted are statistically significant (p<0.05). The pale grey latitudinal band indicates the core of the Southern Hemisphere westerly wind (SHWW) belt. Pale blue polygons indicate the region covered by seasonal sea ice. Pale orange polygons indicate the region covered by perennial sea ice. Black squares represent a 1∘×1∘ quadrant around the point of highest correlation (QHC) between wind strength and diatom abundance. Regional maps only present areas of spatial correlation larger than 1∘×1∘. Degrees of freedom (DF) for each spatial
correlation can be obtained using the following expression dependent on the
sample size (n): DF =n-2.
Sky-Blu ice core (SKBL)Chemistry, MPC and diatom abundance annual records
The SKBL chemical fluxes, MPC flux and diatom abundance records are
characterized by negative trends during the 1999–2019 CE period (Fig. 2)
(Table S1). Among these trends, only MPC, nssCa2+ and nssK+ fluxes exhibited linear trends that were statistically significant (p<0.05). The diatom abundance is characterized by moderate interannual variability and single major increases during 1999–2000, 2002–2003 and 2009–2010 CE, with the latter presenting the absolute highest value (77 n yr-1). A major increase in MSA flux was also registered during 2003 CE (Fig. 2). Similar features were present in the SKBL chemical concentration and MPC records (Table S2, Fig. S1).
Environmental correlations
The diatom abundance, chemical and MPC records from SKBL were compared to
environmental parameters over the 1999–2019 CE period (Appendix B – Fig. B1). Two records are highly correlated with wind strength: the diatom
abundance and ssNa+. Diatom abundance exhibits a positive correlation
with wind strength (0.45≤R≤0.78, p<0.05) over a latitudinal band (∼60∘ S) extending from the Ross Sea to the Amundsen Sea and a negative correlation with the sea ice cover (-0.6≥R≥-0.71, p<0.05) over the Amundsen Sea Embayment (Fig. 3). The ssNa+ is positively correlated with wind strength (0.6≤R≤0.75, p<0.05) off the west coast of South America at ∼45∘ S. No correlations were identified between the ice core records and wind strength or precipitation over the SKBL ice core drilling site. No strong correlations (R≥0.6 or R≤-0.6) between the MSA record and sea ice cover were identified in the region.
Sherman Island ice core (SHIC)Chemistry, MPC and diatom abundance annual records
The SHIC chemical fluxes, MPC flux and diatom abundance records present
contrasting features over the 1999–2019 CE period (Fig. 2, Table S1). Negative linear trends are observed in nssCa2+ flux, nssK+ flux and MSA flux. The ssNa+ flux exhibits a positive trend with values reaching an absolute maximum during 2015 CE. The MSA flux was relatively constant over the 1999–2014 CE period. After 2014 CE, MSA flux decreases, reaching its absolute minimum between 2018 and 2019 CE. The MPC flux shows a steady increase after 2008–2009 CE, reaching its highest value in 2018–2019 CE. The diatom abundance exhibits a positive trend (2.16 n yr-1, p>0.05) with a strong interannual variability which describes a semi-periodic 3-year pattern (Fig. 2). Similar features were present in the SHIC chemical concentration and MPC records (Table S2, Fig. S1).
Environmental correlations
The diatom abundance, chemical and MPC records from SHIC were compared to
environmental parameters over the 1999–2019 CE period (Appendix B – Fig. B1). Diatom abundance, MPC and ssNa+ are highly correlated with wind strength over the 1999–2019 CE period. Annual diatom abundance is positively correlated with wind strength (0.45≤R≤0.61, p<0.05) over the Bryan Coast sector (Fig. 3). The spring–summer diatom abundance is
positively correlated with wind strength over a latitudinal band at the
northern limit of the Bellingshausen Sea (∼60∘ S) (0.45≤R≤0.64, p<0.05), over the Bryan Coast (0.45≤R≤0.64, p<0.05) and over the Amundsen Sea Embayment (0.45≤R≤0.71, p<0.05) (Fig. 3). In parallel, the spring–summer diatom abundance is positively correlated with the sea ice cover over the Amundsen Sea (0.45≤R≤0.81, p<0.05) (Fig. 3). MPC is positively correlated with precipitation (0.6≤R≤0.66, p<0.05) over the SHIC drilling site. Conversely, MPC is negatively correlated with precipitation off the southern coast of South America (-0.6≥R≥-0.65, p<0.05). The ssNa+ is positively correlated with sea ice (0.6≤R≤0.7, p<0.05) to the west and north-west of the SHIC drilling site. No clear correlations were identified with the nssCa2+ and nssK+ records. No strong correlations (R≥0.6 or R≤-0.6) between the MSA record and sea ice cover were identified for the SHIC site.
Correlation of ice core records
Linear correlations were calculated between the annual chemical and MPC
fluxes, as well as diatom abundance records across all ice core sites
(Table S3). Strong positive and statistically significant (p<0.05) correlations were identified between nssCa2+ flux and nssK+ flux in SHIC, JUR and SKBL (R=0.48, R=0.45 and R=0.82, respectively) and between ssNa+ flux and MSA flux in SHIC, JUR and SKBL (R=0.7, R=0.63 and R=0.52, respectively). Diatom abundance and ssNa+ flux exhibited strong and significant correlations (p<0.05) across all the ice core sites (R=0.6, R=-0.47 and R=0.46, for SHIC, JUR and SKBL, respectively). The only statistically significant correlation in the same proxy across the sites was between diatom abundance in the JUR and SKBL cores (R=0.84, p<0.05). No clear or consistent pattern was identified when comparing chemical proxies from different ice core sites.
DiscussionTemporal variability of the diatom record
The diatom abundance preserved in ice cores reveals a strong interannual
variability across the AP and EL regions from 1992 to 2019 CE. The relationships between diatom abundance and environmental parameters at the ice core drilling sites are weak and not statistically significant, indicating that conditions at the ice core site are not drivers of the diatom temporal
variability, in agreement with previous studies concluding that ice core
diatom records are not dependent on annual snow accumulation or local wind
conditions (Allen et al., 2020; Tetzner et al., 2022a).
Spatial correlations of annual wind strength and the annual diatom abundance
preserved in ice cores reveal regions of significant positive correlations
(0.45≤R≤0.78, p<0.05) (Fig. 3). These regions match the oceanographic zones indicated by the ecology of the dominant marine diatom taxa well (Tetzner et al., 2022a). Furthermore, the neighbouring ice core sites of JUR and SKBL share similar regions of spatial correlation
(0.45≤R≤0.78, p<0.05) (Fig. 3). Numerous studies have highlighted the relationship between wind strength and sea spray production (Blanchard, 1963; Schlichting, 1974; Monahan et al., 1983; Callaghan et al., 2008; Löndahl, 2014; Tesson et al., 2016; Wiśniewska et al., 2019;
Marks et al., 2019). Stronger winds have been shown to enhance the
production of sea spray aerosols, including microalgae, which implies an
increased transfer of diatoms from the sea surface microlayer into the
atmosphere (Marks et al., 2019). Studies on regional atmospheric circulation
confirm that air masses from these regions are effectively transported to
ice core sites (Thomas and Bracegirdle, 2009; Abram et al., 2010; Thomas and
Bracegirdle, 2015; Allen et al., 2020), therefore establishing an efficient
transport pathway from the identified source regions to the ice core sites.
Two oceanographic zones were highlighted in the spatial correlation analyses
for their strong link between changes in wind strength and changes in diatom
abundance: the seasonal sea ice zone (SSIZ) and permanently open ocean zone
(POOZ). The JUR and SKBL diatom records were correlated exclusively with
winds in the POOZ (northern Amundsen Sea), and the SHIC spring–summer diatom
record was correlated with regions from both the SSIZ (Bryan Coast sector
and Amundsen Sea Embayment) and POOZ (northern Bellingshausen Sea) (Fig. 3). It is important to note that these regions of spatial correlation agree
with the oceanographic affiliations of the diatom assemblages for the
respective ice cores (coastal vs. inland sites) reported by Tetzner et al. (2022a). Despite the correlation between the SHIC spring–summer diatom
record and winds in the POOZ, the diatom assemblages for SHIC support a
stronger link with the SSIZ (Tetzner et al., 2022a). Therefore, discussion
for the SHIC diatom record will be focused on environmental changes within
the SSIZ. The correlation between the SHIC summer–spring diatom record and
winds in the POOZ (Fig. 3) is likely explained by the close association
between regional atmospheric circulation (SHWW), sea ice dynamics and
primary productivity in the Amundsen–Bellingshausen seas (Arrigo et al., 2008; Soppa et al., 2016).
SSIZ controls on diatom variability at a coastal site (SHIC)
The SSIZ is identified as the dominant source region by both the spatial
correlation analyses and the ecological associations of the SHIC diatom
record (Tetzner et al., 2022a). Wind strength and sea ice dynamics play an
important role in driving the primary productivity in diatom source regions
within the SSIZ (Arrigo et al., 2008, 2012). In the Bryan Coast and Amundsen Sea Embayment, winds drive sea ice northward, producing large ice-free areas (polynyas) near the coast (Arrigo et al., 2012; Holland
and Kwok, 2012). These coastal polynyas have been identified as among the
most productive regions in the Southern Ocean (Arrigo et al., 2008; Soppa et
al., 2016). The stronger link to wind strength during the austral spring and
summer (Fig. 3) and strong seasonality identified in the sub-annual diatom record reflect the enhanced austral spring–summer primary productivity in these regions (Arrigo et al., 2008; Soppa et al., 2016; Tetzner et al., 2022a). This suggests that the interannual diatom
variability at this site is not exclusively driven by wind strength, but is
also dependent on sea ice dynamics and/or primary productivity. Previous
studies have identified recent reductions in the ice-covered days (sea ice
concentration) during the austral summer (Stammerjohn et al., 2012) and the
development of coastal polynyas (Eltanin Polynya, Pine Island Polynya and
Amundsen Sea Polynya) within the coastal regions identified as the SHIC
diatom sources (Arrigo and van Dijken, 2003; Arrigo et al., 2012). Both lead
to prolonged and increased biogenic primary productivity near the ice core
site. Greater sea ice breakup and more open water in summer often result in
larger phytoplankton blooms (Soppa et al., 2016). A prolonged ice-free
diatom source and/or recently enhanced primary productivity will increase
the availability of diatoms on the ocean surface, favouring potentially
larger entrainments of diatoms by strong winds. This is consistent with the
recent large decadal increases seen in the SHIC diatom concentration
(Tetzner et al., 2022a).
The clear link identified between the seasonality of the diatom record and
sea ice primary productivity is complemented by the strong relationship
between the austral spring–summer diatom abundance and sea ice cover over
the Amundsen Sea. However, no direct relationship was observed between the
diatom abundance and the sea ice cover directly in the vicinities of SHIC
(Fig. 3). This is consistent with the lack of correlation between MSA and
sea ice at this site, despite previous studies observing a positive
relationship between MSA and sea ice extent in this region (Abram et al., 2010; Thomas and Abram, 2016). These findings suggest that diatom (and MSA) variability at SHIC is not exclusively driven by either marine primary
productivity or changes in sea ice cover. This can be explained by the
effect of a bidirectional pattern of winds at SHIC, drawing air masses from
both the east coast (Bryan Coast) and the west coast (Amundsen Sea
Embayment) (Tetzner et al., 2019), resulting in two distinct sources of
aerosols to the ice core site. Additionally, the onset of the sea ice
breakup and duration of ice-free conditions at the Bryan Coast, Eights Coast
and the Amundsen Sea Embayment do not follow a clear pattern. Some years
present these coastal regions as completely ice-free, while others present
either one or more of these regions as ice-covered (Arrigo et al., 2008). The
development of coastal polynyas near SHIC (see Fig. 1) will contribute to
the increased availability of diatoms in some years (Arrigo and van Dijken,
2003; Arrigo et al., 2015). The potential input of diatoms from coastal
sources from opposite directions, along with the variability in the
distribution and duration of the sea ice cover and the occasional
development of coastal polynyas, adds an additional and non-negligible source
of variability to the diatom record at SHIC.
POOZ controls on diatom variability at inland sites (JUR and SKBL)
The diatom source region identified by the spatial correlation analyses and
diatom ecological affiliations for JUR and SKBL is in the northern Amundsen
Sea within the POOZ (Figs. 1 and 3). This oceanographic zone is characterized by the lowest seasonal and interannual variability in primary productivity for the whole SO (Arrigo et al., 2008; Soppa et al., 2016). The
absence of sea ice in the POOZ reduces the seasonal extremes in primary
productivity evident within the SSIZ (Tetzner et al., 2022a). The diatom
availability in the northern Amundsen Sea POOZ presents a low variability
year-round (Arrigo et al., 2008; Soppa et al., 2016), limiting the impact of
interannual changes in primary productivity on the diatom record and
upholding the idea that temporal variability in the JUR and SKBL diatom records is
derived mainly from changes in wind strength at the source. This POOZ source
is also supported by back-trajectory analyses showing that air masses reaching
high-elevation sites on the Antarctic Peninsula are a
considerable distance over the ocean at sea level and are higher in the atmosphere when
they traverse the peninsula coast (Thomas and Bracegirdle, 2015; Allen et
al., 2020). The marine source region supplying diatoms to JUR and SKBL is in
the core of the SHWW belt. The significant positive correlation between wind
strength and annual diatom abundance (0.45≤R≤0.78, p<0.05) demonstrates that the diatom records from these sites can be used as a proxy
for interannual changes in the strength of the SHWWs. However, changes in
ocean primary productivity may contribute to diatom variability over longer
timescales.
Results presented here are consistent with the relationship identified
between SHWW strength and diatoms in an EL ice core (Allen et al., 2020).
Specifically, our results show close agreement with the location
(50–60∘ S, 140∘ W) and magnitude of the strongest
correlation (R=0.61, p<0.05) between annual SHWW anomalies and
calibrated diatom flux at the Ferrigno ice core site (Fig. 1) (Allen et
al., 2020). Unlike JUR and SKBL, the Ferrigno diatom assemblage was
characterized by the absence of sea ice diatoms. This can be explained by
the more north-westerly location of the Ferrigno diatom source (compared to
the JUR and SKBL source region) that is less likely to receive inputs from
the SSIZ. Additionally, the absence of sea ice diatoms at Ferrigno supports
the conclusion that inland sites have limited influence from low-elevation
air masses in contact with the SSIZ (Tetzner et al., 2022a).
Recent regional environmental changes and the diatom record
Ice core diatom records have the potential to capture regional environmental
changes. The correlation between the annual diatom abundance variability at
JUR and SKBL and changes in the wind strength in the SHWW belt (Figs. 3, 4a and b) strongly suggests that the recent increase in diatoms at
these ice core sites (Tetzner et al., 2022a) is driven by a strengthening of
the SHWW belt during the satellite era (Mayewski et al., 2013; Young and
Ribal, 2019; Goyal et al., 2021). This link is further supported by
sea spray production experiments showing that a ∼10 % increase in wind strength (U10>5 m s-1) has the potential to double the production of spume drops and sea spray aerosol, including microalgae (Monahan et al., 1986; Wu, 1993; Anguelova et al., 1999). Increasing the entrainment of aerosols into the atmosphere would likely increase the supply of diatoms to the ice core sites and therefore the number of diatoms contained in the ice. Despite SHIC exhibiting a similar increase in annual diatom abundance, the intrinsic relationship between the SHIC diatom record, the sea ice cover in SSIZ and winds over the SSIZ prevents establishing a direct link between the increases in annual diatom abundance at SHIC and the strengthening of the SHWW belt (Fig. 4c).
Time series of diatom abundance and mean wind speed inside the quadrants of highest correlation (QHC) for each ice core site highlighted in Fig. 3. Data points represent the annual austral winter-to-winter average and were plotted over the correspondent austral summer. Colour-coded symbols for the SHIC ice core represent the time series of wind speed on each QHC identified for that site. QHC-BS: quadrant of high correlation over the
Bellingshausen Sea. QHC-ASE: quadrant of high correlation over the
Amundsen Sea Embayment. QHC-BC: quadrant of high correlation over the
Bryan Coast.
The diatom wind proxy and the traditional ice core wind and atmospheric circulation proxies
We have demonstrated that the annual diatom abundance shows promise as a
wind proxy for SHWW at multiple sites. To assess the full scope and validity
of this novel proxy, we compared the new diatom records with established ice
core wind and atmospheric circulation proxies.
MPC, nssCa2+, ssNa+ and nssK+ have been used to infer past
variability in regional-to-hemispheric atmospheric circulation from annual
to millennial timescales. Our results reveal the limitations in these
traditional proxies, which fail to reproduce the interannual variability of
wind strength upwind from the ice core sites. Even though many of these
records show a strong link with wind strength, their region of correlation
did not fit their expected sources and was not consistent between
sites. This refutes a direct link between wind strength and in situ
aerosol production. For example, there are strong correlations between
continental ions and wind strength over regions in the middle of the ocean,
where it is not feasible to entrain continental ions (JUR nssK+
record). Similarly, some records are strongly linked to other environmental
parameters such as precipitation, suggesting that source (JUR nssCa2+
record) or site conditions (MPC record at SHIC), rather than wind strength,
dominate the variability of these species. Some proxies (MPC at JUR and
ssNa+ at SKBL) were strongly linked to wind strength over regions north
(∼ 40–45∘ S) of the core of the SHWW belt (Appendix B – Fig. B1). These results suggest that those records could indicate changes in wind strength over continental or marine regions far from the
core of the SHWW belt. Previous studies have demonstrated that MPC and chemical
species are valuable records to infer past changes in
regional-to-hemispheric wind regimes and atmospheric circulation. However,
it must be acknowledged that the variability of these tracers represents the
cumulative effect of several factors (McConnell et al., 2007; Lambert et
al., 2008; Li et al., 2010; Wolff et al., 2010; Bullard et al., 2016;
Delmonte et al., 2017). These include (1) wind strength at the source(s),
(2) air mass transport pathways, (3) primary production of the tracer at the
source(s), (4) the humidity and precipitation while transported in the atmosphere, and (5) snow accumulation rate in Antarctica. The numerous factors influencing the variability of these records hinder their capacity to accurately represent changes in winds strength. Despite our results
confirming that these tracers are not the ideal records to infer past wind strength
variability, they do not invalidate their use to reconstruct wind and
atmospheric circulation changes in a broad sense. Additionally, our results
highlight the need for a thorough site and proxy evaluation before using
these chemical and MPC species to reconstruct wind changes through time.
The ssNa+ flux was the only record with a regionally consistent
relationship with the diatom abundance (yellow cells in Table S3). Despite the strong correlations at each ice core site,
they presented opposite signs (R<0 for JUR and R>0 for
SHIC and SKBL), suggesting that the interannual variability of diatom
abundance and ssNa+ flux is not driven exclusively by the same
environmental parameters across the AP and EL region.
Correlation analyses of ice core proxies between sites confirm that diatom
abundance is the only record with a consistent, statistically significant
and strong correlation (JUR vs. SKBL, R=0.84, p<0.05) (grey cell
in Table S3), supporting the regional validity of the diatom-based wind proxy at the high-elevation sites.
Previous studies have proposed MPC as a proxy for winds and atmospheric
circulation in the AP and EL region (Mosley-Thompson et al., 1990, 1991; Thompson et al., 1994), suggesting that the MPC record is indicative of long-term regional environmental changes. However, low background concentrations reported in those studies suggest that the
MPC annual record from the AP and EL region could be biased by the
occurrence of sporadic major dust events reaching the high southern
latitudes (Li et al., 2010). Our results are in close agreement, showing
that the regional MPC record preserved in ice cores from the AP and EL is
not a robust indicator of interannual wind strength variability, possibly
due to the numerous factors driving MPC variability. In contrast, the WAIS
Divide ice core in neighbouring Marie Byrd Land revealed a link between the
coarse particle percentage (analogous to MPC) and interannual zonal wind
strength variability at both 700 and 850 hPa over the satellite era
(R= 0.3–0.5, p<0.01) (Koffman et al., 2014). This contrasting
behaviour can be partly explained by the diametrically opposed continental
regions supplying mineral dust to Antarctica (Sudarchikova et al., 2015;
Neff and Bertler, 2015) and the higher dependence of Antarctic Peninsula
sites on extreme precipitation events (Turner et al., 2019). Similarly,
differences in transport pathways and the role of local meteorology have
also been used to explain the different behaviour observed in sea ice
proxies (MSA) around Antarctica (Abram et al., 2013; Thomas et al., 2019).
Our findings provide further evidence that ice core proxies perform
differently depending on the geographical region and the temporal resolution
over which they are assessed.
The temporal variability of chemical tracers (nssCa2+, nssK+,
ssNa+) in a network of ice cores across Marie Byrd Land (ITASE) has
been proposed as a tracer of long-term (multi-year) changes in atmospheric
circulation (Dixon et al., 2012; Mayewski et al., 2013). However, only
nssCa+2 proved reliable in capturing interannual variability in
atmospheric circulation patterns over the satellite era (0.37≤R≤0.59, p<0.01), although not directly related to wind strength but
to northerly air mass incursions (Dixon et al., 2012). Thus, there is
clearly a need for a reliable proxy for past wind strength in this important
region of Antarctica. Based on our results, we propose that diatoms show the
most promise as a tool to reconstruct the interannual variability of SHWW
strength.
Recommendations
Our findings demonstrate that diatoms show the most promise as a proxy for
past wind strength in AP and EL ice cores when compared with a range of
traditional chemical and MPC records. At inland sites, diatom abundance is
most strongly dependent on annual changes in the strength of the SHWWs and
has excellent potential as a proxy to reconstruct past changes in the
strength of the SHWWs over the northern Amundsen Sea.
Based on our results, we propose three candidate ice core sites across the
AP and EL region where multi-decadal to centennial-scale reconstructions of
winds could be achieved: the Jurassic, Ferrigno and Palmer ice cores (Thomas
and Bracegirdle, 2015) (see Fig. 1). Evaluations have already confirmed
the suitability of the JUR site (this study) and the Ferrigno site (Allen et
al., 2020) in reproducing recent changes in the SHWW strength. Previous
studies on the Ferrigno ice core have confirmed that this ice core covers
the last 3 centuries (Thomas et al., 2015; Thomas and Abram, 2016),
making it a good candidate for extending an SHWW reconstruction back to the
core of the Little Ice Age (∼1700 CE), while the JUR site has
the potential to capture changes over the last 140 years (Emanuelsson et
al., 2022). The diatom record from the Palmer ice core has not yet been
explored; however, this high-elevation, low-snow-accumulation site (Thomas
and Bracegirdle, 2015) has the potential to hold a 390-year record
(Emanuelsson et al., 2022), one of the longest records in the region. An
annually resolved wind strength reconstruction from any of these three ice
cores will establish if the recent intensification of the SHWW belt is
unprecedented over the last few centuries and will clearly identify the
timing of onset (Abram et al., 2013; Koffman et al., 2014; Turney et al., 2016; Perren et al., 2020).
Despite the consistency of the observations presented in this work, it must
be acknowledged that they are from a particular region in Antarctica.
Antarctica is a vast continent with contrasting environmental conditions in
different sectors (Jones et al., 2016; Stenni et al., 2017; Thomas et al., 2017, 2019). Thus, we recommend conducting a detailed assessment of the diatom proxy outside the AP–EL regions.
Conclusions
Ice cores capture changes in past wind strength and atmospheric variability,
with several chemical and microparticles suggested as potential proxies. In
this study, we propose an exciting new wind proxy based on diatoms that
performs better than traditional ice core wind proxies in ice cores from the
southern Antarctic Peninsula and Ellsworth Land. A set of ice cores from
this region have been analysed to demonstrate that the temporal variability
of the diatom record preserved in inland ice cores is exclusively driven by
changes in the wind strength within the core of the Southern Hemisphere
westerly wind belt, while the temporal variability of the diatoms preserved
in coastal ice cores is driven by a combination of wind strength and sea ice
dynamics within the seasonal sea ice zone.
The lack of coherence between ice core chemical and dust proxies at sites
from the same region suggests that these proxies should be used with caution.
For these proxies, both the production at the source and the deposition at
the ice core sites drive the variability, making it hard to resolve the
signal of wind strength. These findings demonstrate the importance of a
thorough site evaluation before extending environmental interpretations back
in time, with no single proxy suitable for reconstructions across all of
Antarctica.
We propose that the diatom record preserved in ice cores from the Antarctic
Peninsula and Ellsworth Land regions is the optimal proxy for reconstructing
the interannual wind strength variability in the Pacific sector of the
Southern Hemisphere westerly wind belt. Further research should be focused
on expanding the study of the diatom record and its potential as a wind
proxy in other regions of Antarctica and over longer timescales.
Relative abundance (%) and frequency (no. of samples) of main
diatom taxa in annual diatom records for each ice core. (*) Specimens of
Cyclotella sensu lato (including Lindavia, Discostella, Tertiarius and Pantocsekiella). (s): sea-ice-affiliated diatom. (o-SSIE): open ocean – diatom affiliated with the seasonal sea ice edge. (o-POOZ): open ocean – diatom species or group affiliated with the permanently open ocean zone. Table modified from Tetzner et al. (2022a).
Regional maps showing spatial correlations between environmental parameters and chemical species, MPC and diatom abundance. Colour-coded polygons in the maps indicate highly correlated regions (R≥0.6 or R≤-0.6). All polygons plotted are statistically significant (p<0.05). Pale grey latitudinal band indicates the core of the Southern Hemisphere westerly wind (SHWW) belt. Pale blue polygons indicate the region covered by seasonal sea ice. Pale orange polygons indicate the region covered by perennial sea ice. Black squares represent a 1∘×1∘ quadrant around the point of highest correlation (QHC) between wind strength and diatom abundance. Spatial correlations between MSA and environmental parameters were excluded because they were below the threshold (R<0.6, R>-0.6 or p>0.05). Regional maps only present areas of spatial correlation larger than 1∘×1∘. Degrees of freedom (DF) for each spatial correlation can be obtained using the following expression dependent on the sample size (n); DF =n-2.
Data availability
Datasets original to this work will be available at the UK Polar Data Centre (10.5285/9ce1fd9f-cfaf-44fa-aa5d-45c24c0a76cc, Tetzner et al., 2022b).
The supplement related to this article is available online at: https://doi.org/10.5194/cp-18-1709-2022-supplement.
Author contributions
DRT did the initial conceptualization. DRT and MMG were in charge of data curation. DRT, ERT and CSA conducted the formal analysis. DRT was in charge of the investigation. DRT, ERT and CSA designed the methodology. DRT prepared the original paper. ERT, CSA and MMG contributed to the reviewing and editing of the original paper.
Competing interests
At least one of the (co-)authors is a member of the editorial board of Climate of the Past. The peer-review process was guided by an independent editor, and the authors also have no other competing interests to declare.
Disclaimer
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Acknowledgements
We would like to thank Sarah Crowsley, Tom King, Isobel Rowell and Dr. Robert
Mulvaney for their help while drilling the SHIC and SKBL ice cores included
in this work. We would like to thank Shaun Miller, Jack Humby, Diana
Vladimirova and Daniel Emanuelsson from the Ice Core Lab, British
Antarctic Survey, for their help while cutting the ice and conducting the
continuous flow analysis (CFA). We would like to thank Eric Wolff
from the Earth Sciences Department, University of Cambridge, for his
valuable comments during the final review and editing of this paper.
SEM work was partly supported by a Royal Society Research Professorships
Enhancement Award (RP/EA/180006). We would like to thank Iris Buisman and Giulio Lampronti from the Microscopy Lab, Earth Sciences Department, University of Cambridge, for their technical support in the use of the SEM. Fieldwork conducted for this research was supported by the Collaborative Antarctic Science Scheme (CASS-168). This research was funded by CONICYT–Becas Chile and Cambridge Trust funding programme for PhD studies under grant number 72180432. Finally, the authors thank two anonymous reviewers and the editor for their constructive comments that led to an improved paper.
Financial support
This research has been supported by the Comisión Nacional de Investigación Científica y Tecnológica (grant no. 72180432).
Review statement
This paper was edited by Barbara Stenni and reviewed by two anonymous referees.
ReferencesAbram, N. J., Thomas, E. R., McConnell, J. R., Mulvaney, R., Bracegirdle, T.
J., Sime, L. C., and Aristarain, A. J.: Ice core evidence for a 20th century
decline of sea ice in the Bellingshausen Sea, Antarctica, J. Geophys. Res., 115, D23101, 10.1029/2010JD014644, 2010.Abram, N. J., Wolff, E. W., and Curran, M. A. J.: A review of sea ice proxy
information from polar ice cores, Quaternary Sci. Rev., 79, 168–183,
10.1016/j.quascirev.2013.01.011, 2013.Allen, C. S., Thomas, E. R., Blagbrough, H., Tetzner, D. R., Warren, R. A.,
Ludlow, E. C., and Bracegirdle, T. J.: Preliminary Evidence for the Role
Played by South Westerly Wind Strength on the Marine Diatom Content of an
Antarctic Peninsula Ice Core (1980–2010), Geosciences, 10, 87, 10.3390/geosciences10030087, 2020.Anguelova, M., Barber, R. P., and Wu, J.: Spume Drops Produced by the Wind
Tearing of Wave Crests, J. Phys. Oceanogr., 29, 1156–1165,
10.1175/1520-0485(1999)029<1156:SDPBTW>2.0.CO;2, 1999.Arrigo, K. R. and van Dijken, G. L.: Phytoplankton dynamics within 37
Antarctic coastal polynya systems, J. Geophys. Res., 108, 3271, 10.1029/2002JC001739, 2003.Arrigo, K. R., van Dijken, G. L., and Bushinsky, S.: Primary production in
the Southern Ocean, 1997–2006, J. Geophys. Res., 113, C08004, 10.1029/2007JC004551, 2008.Arrigo, K. R., Lowry, K. E., and van Dijken, G. L.: Annual changes in sea
ice and phytoplankton in polynyas of the Amundsen Sea, Antarctica, Deep-Sea
Res. Pt. II, 71–76, 5–15, 10.1016/j.dsr2.2012.03.006, 2012.Arrigo, K. R., van Dijken, G. L., and Strong, A. L.: Environmental controls
of marine productivity hot spots around Antarctica, J. Geophys.
Res.-Oceans, 120, 5545–5565, 10.1002/2015JC010888, 2015.Blanchard, D. C.: The electrification of the atmosphere by particles from
bubbles in the sea, Prog. Oceanogr., 1, 73–202, 10.1016/0079-6611(63)90004-1, 1963.
Bowen, H. J. M.: Environmental chemistry of the elements, Academic Press,
London, ISBN: 0121204502 9780121204501, 1979.Bracegirdle, T. J., Shuckburgh, E., Sallee, J.-B., Wang, Z., Meijers, A. J.
S., Bruneau, N., Phillips, T., and Wilcox, L. J.: Assessment of surface
winds over the Atlantic, Indian, and Pacific Ocean sectors of the Southern
Ocean in CMIP5 models: historical bias, forcing response, and state
dependence, J. Geophys. Res.-Atmos., 118, 547–562,
10.1002/jgrd.50153, 2013.Budgeon, A. L., Roberts, D., Gasparon, M., and Adams, N.: Direct evidence of
aeolian deposition of marine diatoms to an ice sheet, Antarct. Sci., 24,
527–535, 10.1017/S0954102012000235, 2012.Bullard, J. E., Baddock, M., Bradwell, T., Crusius, J., Darlington, E.,
Gaiero, D., Gassó, S., Gisladottir, G., Hodgkins, R., McCulloch, R.,
McKenna-Neuman, C., Mockford, T., Stewart, H., and Thorsteinsson, T.:
High-latitude dust in the Earth system, Rev. Geophys., 54, 447–485,
10.1002/2016RG000518, 2016.Callaghan, A., de Leeuw, G., Cohen, L., and O'Dowd, C. D.: Relationship of
oceanic whitecap coverage to wind speed and wind history, Geophys. Res. Lett., 35, L23609, 10.1029/2008GL036165, 2008.Chalmers, M. O., Harper, M. A., and Marshall, W. A.: An illustrated
catalogue of airborne microbiota from the maritime Antarctic, British
Antarctic Survey, Cambridge, 175 pp., https://nora.nerc.ac.uk/id/eprint/514943/ (last access: 1 July 2021), 1996.Cipriano, R. J. and Blanchard, D. C.: Bubble and aerosol spectra produced by
a laboratory 'breaking wave', J. Geophys. Res., 86, 8085–8092, 10.1029/JC086iC09p08085, 1981.Delmonte, B., Paleari, C. I., Andò, S., Garzanti, E., Andersson, P. S.,
Petit, J. R., Crosta, X., Narcisi, B., Baroni, C., Salvatore, M. C.,
Baccolo, G., and Maggi, V.: Causes of dust size variability in central East
Antarctica (Dome B): Atmospheric transport from expanded South American
sources during Marine Isotope Stage 2, Quaternary Sci. Rev., 168,
55–68, 10.1016/j.quascirev.2017.05.009, 2017.Delmonte, B., Winton, H., Baroni, M., Baccolo, G., Hansson, M., Andersson,
P., Baroni, C., Salvatore, M. C., Lanci, L., and Maggi, V.: Holocene dust in
East Antarctica: Provenance and variability in time and space, The Holocene,
30, 546–558, 10.1177/0959683619875188, 2020.Dixon, D. A., Mayewski, P. A., Goodwin, I. D., Marshall, G. J., Freeman, R.,
Maasch, K. A., and Sneed, S. B.: An ice-core proxy for northerly air mass
incursions into West Antarctica, Int. J. Climatol., 32,
1455–1465, 10.1002/joc.2371, 2012.
Dong, X., Wang, Y., Hou, S., Ding, M., Yin, B., and Zhang, Y.: Robustness
of the recent global atmospheric reanalyses for Antarctic near-surface wind
speed climatology, J. Climate, 33, 4027–4043, 2020.Dutrieux, P., Rydt, J. D., Jenkins, A., Holland, P. R., Ha, H. K., Lee, S.
H., Steig, E. J., Ding, Q., Abrahamsen, E. P., and Schröder, M.: Strong
Sensitivity of Pine Island Ice-Shelf Melting to Climatic Variability,
Science, 343, 174–178, 10.1126/science.1244341, 2014.Elster, J., Delmas, R. J., Petit, J.-R., and Řeháková, K.: Composition of microbial communities in aerosol, snow and ice samples from remote glaciated areas (Antarctica, Alps, Andes), Biogeosciences Discuss., 4, 1779–1813, 10.5194/bgd-4-1779-2007, 2007.Emanuelsson, B. D., Thomas, E. R., Tetzner, D. R., Humby, J. D., and Vladimirova, D. O.: Ice Core Chronologies from the Antarctic Peninsula: The Palmer, Jurassic, and Rendezvous Age-Scales, Geosciences, 12, 87, 10.3390/geosciences12020087, 2022.Farmer, D. M., McNeil, C. L., and Johnson, B. D.: Evidence for the importance of bubbles in increasing air–sea gas flux, Nature, 361, 620–623, 10.1038/361620a0, 1993.Favier, L., Durand, G., Cornford, S. L., Gudmundsson, G. H., Gagliardini,
O., Gillet-Chaulet, F., Zwinger, T., Payne, A. J., and Le Brocq, A. M.:
Retreat of Pine Island Glacier controlled by marine ice-sheet instability,
Nat. Clim. Change, 4, 117–121, 10.1038/nclimate2094, 2014.Fetterer, F., Knowles, K., Meier, W. N., Savoie, M., and Windnagel, A. K.: Sea Ice Index, Version 3, Sea Ice Extent dataset, NSIDC:
National Snow and Ice Data Center [data set], Boulder, Colorado USA, 10.7265/N5K072F8, 2017.Frey, M. M., Bales, R. C., and McConnell, J. R.: Climate sensitivity of the
century-scale hydrogen peroxide (H2O2) record preserved in 23 ice cores from West Antarctica, J. Geophys. Res., 111, D21301,
10.1029/2005JD006816, 2006.Frey, M. M., Norris, S. J., Brooks, I. M., Anderson, P. S., Nishimura, K., Yang, X., Jones, A. E., Nerentorp Mastromonaco, M. G., Jones, D. H., and Wolff, E. W.: First direct observation of sea salt aerosol production from blowing snow above sea ice, Atmos. Chem. Phys., 20, 2549–2578, 10.5194/acp-20-2549-2020, 2020.Fritz, S. C., Brinson, B. E., Billups, W. E., and Thompson, L. G.: Diatoms
at >5000 Meters in the Quelccaya Summit Dome Glacier, Peru,
Arct. Antarct. Alp. Res., 47, 369–374, 10.1657/AAAR0014-075, 2015.Gayley, R. I., Ram, M., and Stoermer, E. F.: Seasonal variations in diatom
abundance and provenance in Greenland ice, J. Glaciol., 35, 290–292, 10.3189/S0022143000004664, 1989.Gille, S.: How ice shelves melt, Science, 346, 1180–1181, 10.1126/science.aaa0886, 2014.Gille, S. T.: Decadal-Scale Temperature Trends in the Southern Hemisphere
Ocean, J. Climate, 21, 4749–4765, 10.1175/2008JCLI2131.1, 2008.Goodwin, I. D., van Ommen, T. D., Curran, M. A. J., and Mayewski, P. A.: Mid
latitude winter climate variability in the South Indian and southwest
Pacific regions since 1300 AD, Clim. Dynam., 22, 783–794, 10.1007/s00382-004-0403-3, 2004.Goyal, R., Gupta, A. S., Jucker, M., and England, M. H.: Historical and
Projected Changes in the Southern Hemisphere Surface Westerlies, Geophys. Res. Lett., 48, e2020GL090849, 10.1029/2020GL090849, 2021.Grieman, M. M., Hoffmann, H. M., Humby, J. D., Mulvaney, R., Nehrbass-Ahles,
C., Rix, J., Thomas, E. R., Tuckwell, R., and Wolff, E. W.: Continuous flow
analysis methods for sodium, magnesium and calcium detection in the Skytrain
ice core, J. Glaciol., 68, 90–100, 10.1017/jog.2021.75, 2021.Harper, M. A. and McKay, R. M.: Diatoms as markers of atmospheric transport,
in: The Diatoms: Applications for the Environmental and Earth Sciences,
edited by: Stoermer, E. F. and Smol, J. P., Cambridge University Press,
Cambridge, 552–559, 10.1017/CBO9780511763175.032, 2010.Hausmann, S., Larocque-Tobler, I., Richard, P. J. H., Pienitz, R., St-Onge,
G., and Fye, F.: Diatom-inferred wind activity at Lac du Sommet, southern
Québec, Canada: A multiproxy paleoclimate reconstruction based on
diatoms, chironomids and pollen for the past 9500 years, The Holocene, 21,
925–938, 10.1177/0959683611400199, 2011.
Hersbach, H. and Dee, D. J. E. N.: ERA5 reanalysis is in production, ECMWF
newsletter, 147, 5–6, 2016.Hodgson, D. A. and Sime, L. C.: Southern westerlies and CO2, Nat. Geosci.,
3, 666–667, 10.1038/ngeo970, 2010.Holland, P. R. and Kwok, R.: Wind-driven trends in Antarctic sea-ice drift,
Nat. Geosci., 5, 872–875, 10.1038/ngeo1627, 2012.Holland, P. R., Bracegirdle, T. J., Dutrieux, P., Jenkins, A., and Steig, E.
J.: West Antarctic ice loss influenced by internal climate variability and
anthropogenic forcing, Nat. Geosci., 12, 718–724, 10.1038/s41561-019-0420-9, 2019.Huang, J. and Jaeglé, L.: Wintertime enhancements of sea salt aerosol in polar regions consistent with a sea ice source from blowing snow, Atmos. Chem. Phys., 17, 3699–3712, 10.5194/acp-17-3699-2017, 2017.Jacobs, S. S., Jenkins, A., Giulivi, C. F., and Dutrieux, P.: Stronger ocean
circulation and increased melting under Pine Island Glacier ice shelf,
Nat. Geosci., 4, 519–523, 10.1038/ngeo1188, 2011.Jones, J. M., Gille, S. T., Goosse, H., Abram, N. J., Canziani, P. O.,
Charman, D. J., Clem, K. R., Crosta, X., de Lavergne, C., Eisenman, I.,
England, M. H., Fogt, R. L., Frankcombe, L. M., Marshall, G. J.,
Masson-Delmotte, V., Morrison, A. K., Orsi, A. J., Raphael, M. N., Renwick,
J. A., Schneider, D. P., Simpkins, G. R., Steig, E. J., Stenni, B.,
Swingedouw, D., and Vance, T. R.: Assessing recent trends in high-latitude
Southern Hemisphere surface climate, Nat. Clim. Change, 6, 917–926,
10.1038/nclimate3103, 2016.Joughin, I., Smith, B. E., and Medley, B.: Marine Ice Sheet Collapse
Potentially Under Way for the Thwaites Glacier Basin, West Antarctica,
Science, 344, 735–738, 10.1126/science.1249055, 2014.Kaspari, S., Dixon, D. A., Sneed, S. B., and Handley, M. J.: Sources and
transport pathways of marine aerosol species into West Antarctica, Ann.
Glaciol., 41, 1–9, 10.3189/172756405781813221, 2005.Koffman, B. G., Kreutz, K. J., Breton, D. J., Kane, E. J., Winski, D. A., Birkel, S. D., Kurbatov, A. V., and Handley, M. J.: Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia, Clim. Past, 10, 1125–1144, 10.5194/cp-10-1125-2014, 2014.Kreutz, K. J., Mayewski, P. A., Pittalwala, I. I., Meeker, L. D., Twickler,
M. S., and Whitlow, S. I.: Sea level pressure variability in the Amundsen
Sea region inferred from a West Antarctic glaciochemical record, J. Geophys. Res., 105, 4047–4059, 10.1029/1999JD901069, 2000.Laluraj, C. M., Rahaman, W., Thamban, M., and Srivastava, R.: Enhanced Dust
Influx to South Atlantic Sector of Antarctica During the Late-20th Century:
Causes and Contribution to Radiative Forcing, J. Geophys. Res.-Atmos., 125, e2019JD030675, 10.1029/2019JD030675, 2020.Lambert, F., Delmonte, B., Petit, J. R., Bigler, M., Kaufmann, P. R.,
Hutterli, M. A., Stocker, T. F., Ruth, U., Steffensen, J. P., and Maggi, V.:
Dust-climate couplings over the past 800,000 years from the EPICA Dome C ice
core, Nature, 452, 616–619, 10.1038/nature06763, 2008.Landschützer, P., Gruber, N., Haumann, F. A., Rödenbeck, C., Bakker,
D. C. E., Heuven, S. van, Hoppema, M., Metzl, N., Sweeney, C., Takahashi,
T., Tilbrook, B., and Wanninkhof, R.: The reinvigoration of the Southern
Ocean carbon sink, Science, 349, 1221–1224, 10.1126/science.aab2620, 2015.
Lazzara, M. A., Weidner, G. A., Keller, L. M., Thom, J. E., and Cassano, J.
J.: Antarctic automatic weather station program: 30 years of polar
observation, B. Am. Meteorol. Soc., 93, 1519–1537, 2012.Legrand, M. and Mayewski, P.: Glaciochemistry of polar ice cores: A review,
Rev. Geophys., 35, 219–243, 10.1029/96RG03527, 1997.Li, F., Ginoux, P., and Ramaswamy, V.: Transport of Patagonian dust to
Antarctica J. Geophys. Res., 115, D18217, 10.1029/2009JD012356, 2010.Lichti-Federovich, S.: Investigation of diatoms found in surface snow from
the Sydkap ice cap, Ellesmere Island, Northwest Territories, Current
Research, Geological Survey of Canada, Paper no. 84-01A, 287–301, 10.4095/119677, 1984.Löndahl, J.: Physical and biological properties of bioaerosols, Bioaerosol detection technologies, in: Bioaerosol Detection Technologies, Springer, 33–48, 10.1007/978-1-4419-5582-1_3, 2014.Marks, R., Górecka, E., McCartney, K., and Borkowski, W.: Rising bubbles
as mechanism for scavenging and aerosolization of diatoms, J. Aerosol Sci., 128, 79–88, 10.1016/j.jaerosci.2018.12.003, 2019.
Marshall, G. J., Orr, A., Van Lipzig, N. P., and King, J. C.: The impact of
a changing Southern Hemisphere Annular Mode on Antarctic Peninsula summer
temperatures, J. Climate, 19, 5388–5404, 2006.Mayewski, P. A., Maasch, K. A., Dixon, D., Sneed, S. B., Oglesby, R.,
Korotkikh, E., Potocki, M., Grigholm, B., Kreutz, K., Kurbatov, A. V.,
Spaulding, N., Stager, J. C., Taylor, K. C., Steig, E. J., White, J.,
Bertler, N. A. N., Goodwin, I., Simões, J. C., Jaña, R., Kraus, S.,
and Fastook, J.: West Antarctica's sensitivity to natural and human-forced
climate change over the Holocene, J. Quaternary Sci., 28, 40–48,
10.1002/jqs.2593, 2013.McConnell, J. R., Aristarain, A. J., Banta, J. R., Edwards, P. R., and
Simões, J. C.: 20th-Century doubling in dust archived in an Antarctic
Peninsula ice core parallels climate change and desertification in South
America, P. Natl. Acad. Sci. USA, 104, 5743–5748, 10.1073/pnas.0607657104, 2007.McKay, R. M., Barrett, P. J., Harper, M. A., and Hannah, M. J.: Atmospheric
transport and concentration of diatoms in surficial and glacial sediments of
the Allan Hills, Transantarctic Mountains, Palaeogeogr. Palaeocl., 260, 168–183, 10.1016/j.palaeo.2007.08.014, 2008.Medley, B. and Thomas, E. R.: Increased snowfall over the Antarctic Ice
Sheet mitigated twentieth-century sea-level rise, Nat. Clim. Change, 9,
34–39, 10.1038/s41558-018-0356-x, 2019.Monahan, E. C., Fairall, C. W., Davidson, K. L., and Boyle, P. J.: Observed
inter-relations between 10m winds, ocean whitecaps and marine aerosols,
Q. J. Roy. Meteor. Soc., 109, 379–392, 10.1002/qj.49710946010, 1983.Monahan, E. C., Spiel, D. E., and Davidson, K. L.: A Model of Marine Aerosol
Generation Via Whitecaps and Wave Disruption, in: Oceanic Whitecaps: And
Their Role in Air-Sea Exchange Processes, edited by: Monahan, E. C. and
Niocaill, G. M., Springer Netherlands, Dordrecht, 167–174, 10.1007/978-94-009-4668-2_16, 1986.Mosley-Thompson, E., Thompson, L. G., Grootes, P. M., and Gundestrup, N.:
Little Ice Age (Neoglacial) Paleoenvironmental Conditions At Siple Station,
Antarctica, Ann. Glaciol., 14, 199–204, 10.3189/S0260305500008570, 1990.Mosley-Thompson, E., Dai, J., Thompson, L. G., Grootes, P. M., Arbogast, J.
K., and Paskievitch, J. F.: Glaciological studies at Siple Station
(Antarctica): potential ice-core paleoclimatic record, J. Glaciol., 37, 11–22, 10.3189/S002214300004274X, 1991.Nakayama, Y., Menemenlis, D., Zhang, H., Schodlok, M., and Rignot, E.:
Origin of Circumpolar Deep Water intruding onto the Amundsen and
Bellingshausen Sea continental shelves, Nat. Commun., 9, 3403, 10.1038/s41467-018-05813-1, 2018.Neff, P. D. and Bertler, N. A. N.: Trajectory modeling of modern dust
transport to the Southern Ocean and Antarctica, J. Geophys.
Res.-Atmos., 120, 9303–9322, 10.1002/2015JD023304, 2015.Oliva, M., Navarro, F., Hrbáček, F., Hernández, A., Nývlt, D., Pereira, P., Ruiz-Fernández, J., and Trigo, R.: Recent regional climate cooling on the Antarctic Peninsula and associated impacts on the cryosphere, Sci. Total Environ., 580, 210–223, 10.1016/j.scitotenv.2016.12.030, 2017.Orr, A., Cresswell, D., Marshall, G. J., Hunt, J. C., Sommeria, J., Wang, C.
G., and Light, M.: A 'low-level' explanation for the recent large warming
trend over the western Antarctic Peninsula involving blocked winds and
changes in zonal circulation, Geophys. Res. Lett., 31, L06204, 10.1029/2003GL019160, 2004.Paolo, F. S., Fricker, H. A., and Padman, L.: Volume loss from Antarctic ice
shelves is accelerating, Science, 348, 327–331, 10.1126/science.aaa0940, 2015.Papina, T., Blyakharchuk, T., Eichler, A., Malygina, N., Mitrofanova, E., and Schwikowski, M.: Biological proxies recorded in a Belukha ice core, Russian Altai, Clim. Past, 9, 2399–2411, 10.5194/cp-9-2399-2013, 2013.Pasteris, D. R., McConnell, J. R., Das, S. B., Criscitiello, A. S., Evans,
M. J., Maselli, O. J., Sigl, M., and Layman, L.: Seasonally resolved ice
core records from West Antarctica indicate a sea ice source of sea-salt
aerosol and a biomass burning source of ammonium, J. Geophys.
Res.-Atmos., 119, 9168–9182, 10.1002/2013JD020720, 2014.Perren, B. B., Hodgson, D. A., Roberts, S. J., Sime, L., Van Nieuwenhuyze,
W., Verleyen, E., and Vyverman, W.: Southward migration of the Southern
Hemisphere westerly winds corresponds with warming climate over centennial
timescales, Communications Earth & Environment, 1, 1–8, 10.1038/s43247-020-00059-6, 2020.Piel, C., Weller, R., Huke, M., and Wagenbach, D.: Atmospheric methane
sulfonate and non-sea-salt sulfate records at the European Project for Ice
Coring in Antarctica (EPICA) deep-drilling site in Dronning Maud Land,
Antarctica, J. Geophys. Res., 111, D03304, 10.1029/2005JD006213, 2006.Pritchard, H. D., Ligtenberg, S. R. M., Fricker, H. A., Vaughan, D. G., van
den Broeke, M. R., and Padman, L.: Antarctic ice-sheet loss driven by basal
melting of ice shelves, Nature, 484, 502–505, 10.1038/nature10968, 2012.Quéré, C. L., Rödenbeck, C., Buitenhuis, E. T., Conway, T. J.,
Langenfelds, R., Gomez, A., Labuschagne, C., Ramonet, M., Nakazawa, T.,
Metzl, N., Gillett, N., and Heimann, M.: Saturation of the Southern Ocean
CO2 Sink Due to Recent Climate Change, Science, 316, 1735–1738, 10.1126/science.1136188, 2007.Rankin, A. M., Auld, V., and Wolff, E. W.: Frost flowers as a source of
fractionated sea salt aerosol in the polar regions, Geophys. Res. Lett., 27, 3469–3472, 10.1029/2000GL011771, 2000.Rankin, A. M., Wolff, E. W., and Martin, S.: Frost flowers: Implications for
tropospheric chemistry and ice core interpretation, J. Geophys.
Res., 107, AAC 4-1–AAC 4-15, 10.1029/2002JD002492, 2002.Röthlisberger, R., Mulvaney, R., Wolff, E. W., Hutterli, M. A., Bigler,
M., Sommer, S., and Jouzel, J.: Dust and sea salt variability in central
East Antarctica (Dome C) over the last 45 kyrs and its implications for
southern high-latitude climate, Geophys. Res. Lett., 29,
24-1–24-4, 10.1029/2002GL015186, 2002.Russell, J. L., Dixon, K. W., Gnanadesikan, A., Stouffer, R. J., and
Toggweiler, J. R.: The Southern Hemisphere Westerlies in a Warming World:
Propping Open the Door to the Deep Ocean, J. Climate, 19, 6382–6390, 10.1175/JCLI3984.1, 2006.Schlichting, H. E.: Ejection of microalgae into the air via bursting
bubbles, J. Allergy Clin. Immun., 53, 185–188, 10.1016/0091-6749(74)90006-2, 1974.Smol, J. P. and Stoermer, E. F. (Eds.): The Diatoms: Applications for the
Environmental and Earth Sciences, 2nd edn., Cambridge University Press,
Cambridge, 10.1017/CBO9780511763175, 2010.Soppa, M. A., Völker, C., and Bracher, A.: Diatom Phenology in the
Southern Ocean: Mean Patterns, Trends and the Role of Climate Oscillations,
Remote Sensing, 8, 420, 10.3390/rs8050420, 2016.Spaulding, S. A., Van de Vijver, B., Hodgson, D. A., McKnight, D. M.,
Verleyen, E., and Stanish, L.: Diatoms as indicators of environmental change
in Antarctic and subantarctic freshwaters, in: The Diatoms: Applications for
the Environmental and Earth Sciences, edited by: Stoermer, E. F. and Smol,
J. P., Cambridge University Press, Cambridge, 267–284, 10.1017/CBO9780511763175.015, 2010.Stammerjohn, S., Massom, R., Rind, D., and Martinson, D.: Regions of rapid
sea ice change: An inter-hemispheric seasonal comparison, Geophys. Res. Lett., 39, L06501, 10.1029/2012GL050874, 2012.Steig, E. J., Ding, Q., Battisti, D. S., and Jenkins, A.: Tropical forcing
of Circumpolar Deep Water Inflow and outlet glacier thinning in the Amundsen
Sea Embayment, West Antarctica, Ann. Glaciol., 53, 19–28, 10.3189/2012AoG60A110, 2012.Stenni, B., Curran, M. A. J., Abram, N. J., Orsi, A., Goursaud, S., Masson-Delmotte, V., Neukom, R., Goosse, H., Divine, D., van Ommen, T., Steig, E. J., Dixon, D. A., Thomas, E. R., Bertler, N. A. N., Isaksson, E., Ekaykin, A., Werner, M., and Frezzotti, M.: Antarctic climate variability on regional and continental scales over the last 2000 years, Clim. Past, 13, 1609–1634, 10.5194/cp-13-1609-2017, 2017.Sudarchikova, N., Mikolajewicz, U., Timmreck, C., O'Donnell, D., Schurgers, G., Sein, D., and Zhang, K.: Modelling of mineral dust for interglacial and glacial climate conditions with a focus on Antarctica, Clim. Past, 11, 765–779, 10.5194/cp-11-765-2015, 2015.Tesson, S. V. M., Skjøth, C. A., Šantl-Temkiv, T., and Löndahl,
J.: Airborne Microalgae: Insights, Opportunities, and Challenges, Appl. Environ. Microb., 82, 1978–1991, 10.1128/AEM.03333-15, 2016.Tetzner, D., Thomas, E., and Allen, C.: A Validation of ERA5 Reanalysis Data
in the Southern Antarctic Peninsula–Ellsworth Land Region, and Its
Implications for Ice Core Studies, Geosciences, 9, 289, 10.3390/geosciences9070289, 2019.Tetzner, D., Thomas, E. R., Allen, C. S., and Wolff, E. W.: A Refined Method
to Analyze Insoluble Particulate Matter in Ice Cores, and Its Application to
Diatom Sampling in the Antarctic Peninsula, Front. Earth Sci., 9, 617043, 10.3389/feart.2021.617043, 2021a.Tetzner, D. R., Thomas, E. R., Allen, C. S., and Piermattei, A.: Evidence of recent active volcanism in the Balleny Islands (Antarctica) from ice core records, J. Geophys. Res.-Atmos., 126, e2021JD035095, 10.1029/2021JD035095, 2021.Tetzner, D. R., Allen, C. S., and Thomas, E. R.: Regional variability of diatoms in ice cores from the Antarctic Peninsula and Ellsworth Land, Antarctica, The Cryosphere, 16, 779–798, 10.5194/tc-16-779-2022, 2022a.Tetzner, D., Thomas, E., and Allen, C.: Annual microparticle and ion fluxes in the Jurassic, Sherman Island and Sky-Blu ice cores (1992-2019 CE), NERC EDS UK Polar Data Centre [data set], 10.5285/9ce1fd9f-cfaf-44fa-aa5d-45c24c0a76cc, 2022b.Thoen, I. U., Simões, J. C., Lindau, F. G. L., and Sneed, S. B.: Ionic
content in an ice core from the West Antarctic Ice Sheet: 1882-2008 A.D.,
Braz. J. Geol., 48, 853–865, 10.1590/2317-4889201820180037, 2018.Thoma, M., Jenkins, A., Holland, D., and Jacobs, S.: Modelling Circumpolar
Deep Water intrusions on the Amundsen Sea continental shelf, Antarctica,
Geophys. Res. Lett., 35, L18602, 10.1029/2008GL034939, 2008.Thomas, E. R. and Abram, N. J.: Ice core reconstruction of sea ice change in
the Amundsen-Ross Seas since 1702 A.D., Geophys. Res. Lett., 43,
5309–5317, 10.1002/2016GL068130, 2016.Thomas, E. R. and Bracegirdle, T. J.: Improving ice core interpretation
using in situ and reanalysis data, J. Geophys. Res., 114, D20116, 10.1029/2009JD012263, 2009.Thomas, E. R. and Bracegirdle, T. J.: Precipitation pathways for five new
ice core sites in Ellsworth Land, West Antarctica, Clim. Dynam., 44, 2067–2078, 10.1007/s00382-014-2213-6, 2015.Thomas, E. R. and Tetzner, D. R.: The Climate of the Antarctic Peninsula
during the Twentieth Century: Evidence from Ice Cores, IntechOpen,
10.5772/intechopen.81507, 2018.Thomas, E. R., Marshall, G. J., and McConnell, J. R.: A doubling in snow
accumulation in the western Antarctic Peninsula since 1850, Geophys. Res. Lett., 35, L01706, 10.1029/2007GL032529, 2008.Thomas, E. R., Dennis, P. F., Bracegirdle, T. J., and Franzke, C.: Ice core
evidence for significant 100-year regional warming on the Antarctic
Peninsula, Geophys. Res. Lett., 36, L20704, 10.1029/2009GL040104, 2009.Thomas, E. R., Bracegirdle, T. J., Turner, J., and Wolff, E. W.: A 308 year
record of climate variability in West Antarctica, Geophys. Res. Lett., 40, 5492–5496, 10.1002/2013GL057782, 2013.Thomas, E. R., Hosking, J. S., Tuckwell, R. R., Warren, R. A., and Ludlow,
E. C.: Twentieth century increase in snowfall in coastal West Antarctica,
Geophys. Res. Lett., 42, 9387–9393, 10.1002/2015GL065750, 2015.Thomas, E. R., van Wessem, J. M., Roberts, J., Isaksson, E., Schlosser, E., Fudge, T. J., Vallelonga, P., Medley, B., Lenaerts, J., Bertler, N., van den Broeke, M. R., Dixon, D. A., Frezzotti, M., Stenni, B., Curran, M., and Ekaykin, A. A.: Regional Antarctic snow accumulation over the past 1000 years, Clim. Past, 13, 1491–1513, 10.5194/cp-13-1491-2017, 2017.Thomas, E. R., Allen, C. S., Etourneau, J., King, A. C. F., Severi, M.,
Winton, V. H. L., Mueller, J., Crosta, X., and Peck, V. L.: Antarctic Sea
Ice Proxies from Marine and Ice Core Archives Suitable for Reconstructing
Sea Ice over the Past 2000 Years, Geosciences, 9, 506, 10.3390/geosciences9120506, 2019.Thompson, D. W. J. and Solomon, S.: Interpretation of Recent Southern
Hemisphere Climate Change, Science, 296, 895–899, 10.1126/science.1069270, 2002.Thompson, L. G., Peel, D. A., Mosley-thompson, E., Mulvaney, R., Dal, J.,
Lin, P. N., Davis, M. E., and Raymond, C. F.: Climate since AD 1510 on Dyer
Plateau, Antarctic Peninsula: evidence for recent climate change, Ann. Glaciol., 20, 420–426, 10.3189/1994AoG20-1-420-426, 1994.
Turner, J., Phillips, T., Thamban, M., Rahaman, W., Marshall, G. J., Wille,
J. D., Favier, V., Winton, V. H. L., Thomas, E., Wang, Z., van den Broeke, M., Hosking, J. S., and Lachlan-Cope, T.: The dominant role of extreme precipitation events in Antarctic snowfall variability, Geophys. Res. Lett., 46, 3502–3511, 2019.Turner, J., Marshall, G. J., Clem, K., Colwell, S., Phillips, T., and Lu,
H.: Antarctic temperature variability and change from station data,
Int. J. Climatol., 40, 2986–3007, 10.1002/joc.6378, 2020.Turney, C. S. M., Jones, R. T., Fogwill, C., Hatton, J., Williams, A. N., Hogg, A., Thomas, Z. A., Palmer, J., Mooney, S., and Reimer, R. W.: A 250-year periodicity in Southern Hemisphere westerly winds over the last 2600 years, Clim. Past, 12, 189–200, 10.5194/cp-12-189-2016, 2016.
Van Den Broeke, M. R. and Van Lipzig, N. P.: Changes in Antarctic temperature, wind and precipitation in response to the Antarctic Oscillation, Ann. Glaciol., 39, 119–126, 2004.Vance, T. R., Ommen, T. D. van, Curran, M. A. J., Plummer, C. T., and Moy,
A. D.: A Millennial Proxy Record of ENSO and Eastern Australian Rainfall
from the Law Dome Ice Core, East Antarctica, J. Climate, 26, 710–725, 10.1175/JCLI-D-12-00003.1, 2013.Wagenbach, D., Ducroz, F., Mulvaney, R., Keck, L., Minikin, A., Legrand, M.,
Hall, J. S., and Wolff, E. W.: Sea-salt aerosol in coastal Antarctic
regions, J. Geophys. Res., 103, 10961-–10974, 10.1029/97JD01804, 1998.Wåhlin, A. K., Kalén, O., Arneborg, L., Björk, G., Carvajal, G.
K., Ha, H. K., Kim, T. W., Lee, S. H., Lee, J. H., and Stranne, C.:
Variability of Warm Deep Water Inflow in a Submarine Trough on the Amundsen
Sea Shelf, J. Phys. Oceanogr., 43, 2054–2070, 10.1175/JPO-D-12-0157.1, 2013.Wang, L., Lu, H., Liu, J., Gu, Z., Mingram, J., Chu, G., Li, J., Rioual, P.,
Negendank, J. F. W., Han, J., and Liu, T.: Diatom-based inference of
variations in the strength of Asian winter monsoon winds between 17,500 and
6000 calendar years B.P., J. Geophys. Res., 113, D21101,
10.1029/2008JD010145, 2008.Warnock, J. P. and Scherer, R. P.: Diatom species abundance and
morphologically-based dissolution proxies in coastal Southern Ocean
assemblages, Cont. Shelf Res., 102, 1–8, 10.1016/j.csr.2015.04.012, 2015.Wiśniewska, K., Lewandowska, A. U., and Śliwińska-Wilczewska,
S.: The importance of cyanobacteria and microalgae present in aerosols to
human health and the environment – Review study, Environ. Int., 131, 104964, 10.1016/j.envint.2019.104964, 2019.Wolff, E. W., Rankin, A. M., and Röthlisberger, R.: An ice core
indicator of Antarctic sea ice production?, Geophys. Res. Lett., 30, 2158, 10.1029/2003GL018454, 2003.Wolff, E. W., Fischer, H., Fundel, F., Ruth, U., Twarloh, B., Littot, G. C.,
Mulvaney, R., Röthlisberger, R., de Angelis, M., Boutron, C. F.,
Hansson, M., Jonsell, U., Hutterli, M. A., Lambert, F., Kaufmann, P.,
Stauffer, B., Stocker, T. F., Steffensen, J. P., Bigler, M.,
Siggaard-Andersen, M. L., Udisti, R., Becagli, S., Castellano, E., Severi,
M., Wagenbach, D., Barbante, C., Gabrielli, P., and Gaspari, V.: Southern
Ocean sea-ice extent, productivity and iron flux over the past eight glacial
cycles, Nature, 440, 491–496, 10.1038/nature04614, 2006.
Wolff, E. W., Barbante, C., Becagli, S., Bigler, M., Boutron, C. F.,
Castellano, E., de Angelis, M., Federer, U., Fischer, H., Fundel, F.,
Hansson, M., Hutterli, M., Jonsell, U., Karlin, T., Kaufmann, P., Lambert,
F., Littot, G. C., Mulvaney, R., Röthlisberger, R., Ruth, U., Severi,
M., Siggaard-Andersen, M. L., Sime, L. C., Steffensen, J. P., Stocker, T.
F., Traversi, R., Twarloh, B., Udisti, R., Wagenbach, D., and Wegner, A.:
Changes in environment over the last 800,000 years from chemical analysis of
the EPICA Dome C ice core, Quaternary Sci. Rev., 29, 285–295,
10.1016/j.quascirev.2009.06.013, 2010.Wu, J.: Production of spume drops by the wind tearing of wave crests: The
search for quantification, J. Geophys. Res., 98, 18221–18227, 10.1029/93JC01834, 1993.Young, I. R. and Ribal, A.: Multiplatform evaluation of global trends in
wind speed and wave height, Science, 364, 548–552, 10.1126/science.aav9527, 2019.Young, I. R., Zieger, S., and Babanin, A. V.: Global Trends in Wind Speed
and Wave Height, Science, 332, 451–455, 10.1126/science.1197219, 2011.Zhu, J., Xie, A., Qin, X., Wang, Y., Xu, B., and Wang, Y.: An assessment of
ERA5 reanalysis for antarctic near-surface air temperature, Atmosphere, 12, 217, 10.3390/atmos12020217, 2021.