Articles | Volume 20, issue 5
https://doi.org/10.5194/cp-20-1125-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/cp-20-1125-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Technical note: An improved methodology for calculating the Southern Annular Mode index to aid consistency between climate studies
Laura Velasquez-Jimenez
CORRESPONDING AUTHOR
Research School of Earth Sciences, Australian National University, Canberra ACT 2601, Australia
Australian Centre for Excellence in Antarctic Science, Australian National University, Canberra ACT 2601, Australia
Nerilie J. Abram
Research School of Earth Sciences, Australian National University, Canberra ACT 2601, Australia
Australian Centre for Excellence in Antarctic Science, Australian National University, Canberra ACT 2601, Australia
ARC Centre of Excellence for Climate Extremes, Australian National University, Canberra ACT 2601, Australia
ARC Centre of Excellence for Weather of the 21st Century, Australian National University, Canberra ACT 2601, Australia
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Tessa R. Vance, Nerilie J. Abram, Alison S. Criscitiello, Camilla K. Crockart, Aylin DeCampo, Vincent Favier, Vasileios Gkinis, Margaret Harlan, Sarah L. Jackson, Helle A. Kjær, Chelsea A. Long, Meredith K. Nation, Christopher T. Plummer, Delia Segato, Andrea Spolaor, and Paul T. Vallelonga
Clim. Past, 20, 969–990, https://doi.org/10.5194/cp-20-969-2024, https://doi.org/10.5194/cp-20-969-2024, 2024
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This study presents the chronologies from the new Mount Brown South ice cores from East Antarctica, which were developed by counting annual layers in the ice core data and aligning these to volcanic sulfate signatures. The uncertainty in the dating is quantified, and we discuss initial results from seasonal cycle analysis and mean annual concentrations. The chronologies will underpin the development of new proxy records for East Antarctica spanning the past millennium.
Georgina M. Falster, Nicky M. Wright, Nerilie J. Abram, Anna M. Ukkola, and Benjamin J. Henley
Hydrol. Earth Syst. Sci., 28, 1383–1401, https://doi.org/10.5194/hess-28-1383-2024, https://doi.org/10.5194/hess-28-1383-2024, 2024
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Multi-year droughts have severe environmental and economic impacts, but the instrumental record is too short to characterise multi-year drought variability. We assessed the nature of Australian multi-year droughts using simulations of the past millennium from 11 climate models. We show that multi-decadal
megadroughtsare a natural feature of the Australian hydroclimate. Human-caused climate change is also driving a tendency towards longer droughts in eastern and southwestern Australia.
Lingwei Zhang, Tessa R. Vance, Alexander D. Fraser, Lenneke M. Jong, Sarah S. Thompson, Alison S. Criscitiello, and Nerilie J. Abram
The Cryosphere, 17, 5155–5173, https://doi.org/10.5194/tc-17-5155-2023, https://doi.org/10.5194/tc-17-5155-2023, 2023
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Physical features in ice cores provide unique records of past variability. We identified 1–2 mm ice layers without bubbles in surface ice cores from Law Dome, East Antarctica, occurring on average five times per year. The origin of these bubble-free layers is unknown. In this study, we investigate whether they have the potential to record past atmospheric processes and circulation. We find that the bubble-free layers are linked to accumulation hiatus events and meridional moisture transport.
Sarah L. Jackson, Tessa R. Vance, Camilla Crockart, Andrew Moy, Christopher Plummer, and Nerilie J. Abram
Clim. Past, 19, 1653–1675, https://doi.org/10.5194/cp-19-1653-2023, https://doi.org/10.5194/cp-19-1653-2023, 2023
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Ice core records are useful tools for reconstructing past climate. However, ice cores favour recording climate conditions at times when snowfall occurs. Large snowfall events in Antarctica are often associated with warmer-than-usual temperatures. We show that this results in a tendency for the Mount Brown South ice core record to preserve a temperature record biased to the climate conditions that exist during extreme events, rather than a temperature record that reflects the mean annual climate.
Rachel M. Walter, Hussein R. Sayani, Thomas Felis, Kim M. Cobb, Nerilie J. Abram, Ariella K. Arzey, Alyssa R. Atwood, Logan D. Brenner, Émilie P. Dassié, Kristine L. DeLong, Bethany Ellis, Julien Emile-Geay, Matthew J. Fischer, Nathalie F. Goodkin, Jessica A. Hargreaves, K. Halimeda Kilbourne, Hedwig Krawczyk, Nicholas P. McKay, Andrea L. Moore, Sujata A. Murty, Maria Rosabelle Ong, Riovie D. Ramos, Emma V. Reed, Dhrubajyoti Samanta, Sara C. Sanchez, Jens Zinke, and the PAGES CoralHydro2k Project Members
Earth Syst. Sci. Data, 15, 2081–2116, https://doi.org/10.5194/essd-15-2081-2023, https://doi.org/10.5194/essd-15-2081-2023, 2023
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Accurately quantifying how the global hydrological cycle will change in the future remains challenging due to the limited availability of historical climate data from the tropics. Here we present the CoralHydro2k database – a new compilation of peer-reviewed coral-based climate records from the last 2000 years. This paper details the records included in the database and where the database can be accessed and demonstrates how the database can investigate past tropical climate variability.
Nicky M. Wright, Claire E. Krause, Steven J. Phipps, Ghyslaine Boschat, and Nerilie J. Abram
Clim. Past, 18, 1509–1528, https://doi.org/10.5194/cp-18-1509-2022, https://doi.org/10.5194/cp-18-1509-2022, 2022
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The Southern Annular Mode (SAM) is a major mode of climate variability. Proxy-based SAM reconstructions show changes that last millennium climate simulations do not reproduce. We test the SAM's sensitivity to solar forcing using simulations with a range of solar values and transient last millennium simulations with large-amplitude solar variations. We find that solar forcing can alter the SAM and that strong solar forcing transient simulations better match proxy-based reconstructions.
Tobias Erhardt, Matthias Bigler, Urs Federer, Gideon Gfeller, Daiana Leuenberger, Olivia Stowasser, Regine Röthlisberger, Simon Schüpbach, Urs Ruth, Birthe Twarloh, Anna Wegner, Kumiko Goto-Azuma, Takayuki Kuramoto, Helle A. Kjær, Paul T. Vallelonga, Marie-Louise Siggaard-Andersen, Margareta E. Hansson, Ailsa K. Benton, Louise G. Fleet, Rob Mulvaney, Elizabeth R. Thomas, Nerilie Abram, Thomas F. Stocker, and Hubertus Fischer
Earth Syst. Sci. Data, 14, 1215–1231, https://doi.org/10.5194/essd-14-1215-2022, https://doi.org/10.5194/essd-14-1215-2022, 2022
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The datasets presented alongside this manuscript contain high-resolution concentration measurements of chemical impurities in deep ice cores, NGRIP and NEEM, from the Greenland ice sheet. The impurities originate from the deposition of aerosols to the surface of the ice sheet and are influenced by source, transport and deposition processes. Together, these records contain detailed, multi-parameter records of past climate variability over the last glacial period.
Camilla K. Crockart, Tessa R. Vance, Alexander D. Fraser, Nerilie J. Abram, Alison S. Criscitiello, Mark A. J. Curran, Vincent Favier, Ailie J. E. Gallant, Christoph Kittel, Helle A. Kjær, Andrew R. Klekociuk, Lenneke M. Jong, Andrew D. Moy, Christopher T. Plummer, Paul T. Vallelonga, Jonathan Wille, and Lingwei Zhang
Clim. Past, 17, 1795–1818, https://doi.org/10.5194/cp-17-1795-2021, https://doi.org/10.5194/cp-17-1795-2021, 2021
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We present preliminary analyses of the annual sea salt concentrations and snowfall accumulation in a new East Antarctic ice core, Mount Brown South. We compare this record with an updated Law Dome (Dome Summit South site) ice core record over the period 1975–2016. The Mount Brown South record preserves a stronger and inverse signal for the El Niño–Southern Oscillation (in austral winter and spring) compared to the Law Dome record (in summer).
Bronwen L. Konecky, Nicholas P. McKay, Olga V. Churakova (Sidorova), Laia Comas-Bru, Emilie P. Dassié, Kristine L. DeLong, Georgina M. Falster, Matt J. Fischer, Matthew D. Jones, Lukas Jonkers, Darrell S. Kaufman, Guillaume Leduc, Shreyas R. Managave, Belen Martrat, Thomas Opel, Anais J. Orsi, Judson W. Partin, Hussein R. Sayani, Elizabeth K. Thomas, Diane M. Thompson, Jonathan J. Tyler, Nerilie J. Abram, Alyssa R. Atwood, Olivier Cartapanis, Jessica L. Conroy, Mark A. Curran, Sylvia G. Dee, Michael Deininger, Dmitry V. Divine, Zoltán Kern, Trevor J. Porter, Samantha L. Stevenson, Lucien von Gunten, and Iso2k Project Members
Earth Syst. Sci. Data, 12, 2261–2288, https://doi.org/10.5194/essd-12-2261-2020, https://doi.org/10.5194/essd-12-2261-2020, 2020
François Klein, Nerilie J. Abram, Mark A. J. Curran, Hugues Goosse, Sentia Goursaud, Valérie Masson-Delmotte, Andrew Moy, Raphael Neukom, Anaïs Orsi, Jesper Sjolte, Nathan Steiger, Barbara Stenni, and Martin Werner
Clim. Past, 15, 661–684, https://doi.org/10.5194/cp-15-661-2019, https://doi.org/10.5194/cp-15-661-2019, 2019
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Antarctic temperature changes over the past millennia have been reconstructed from isotope records in ice cores in several studies. However, the link between both variables is complex. Here, we investigate the extent to which this affects the robustness of temperature reconstructions using pseudoproxy and data assimilation experiments. We show that the reconstruction skill is limited, especially at the regional scale, due to a weak and nonstationary covariance between δ18O and temperature.
Chris S. M. Turney, Helen V. McGregor, Pierre Francus, Nerilie Abram, Michael N. Evans, Hugues Goosse, Lucien von Gunten, Darrell Kaufman, Hans Linderholm, Marie-France Loutre, and Raphael Neukom
Clim. Past, 15, 611–615, https://doi.org/10.5194/cp-15-611-2019, https://doi.org/10.5194/cp-15-611-2019, 2019
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This PAGES (Past Global Changes) 2k (climate of the past 2000 years working group) special issue of Climate of the Past brings together the latest understanding of regional change and impacts from PAGES 2k groups across a range of proxies and regions. The special issue has emerged from a need to determine the magnitude and rate of change of regional and global climate beyond the timescales accessible within the observational record.
Michael Sigl, Nerilie J. Abram, Jacopo Gabrieli, Theo M. Jenk, Dimitri Osmont, and Margit Schwikowski
The Cryosphere, 12, 3311–3331, https://doi.org/10.5194/tc-12-3311-2018, https://doi.org/10.5194/tc-12-3311-2018, 2018
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The fast retreat of Alpine glaciers since the mid-19th century documented in photographs is used as a symbol for the human impact on global climate, yet the key driving forces remain elusive. Here we argue that not industrial soot but volcanic eruptions were responsible for an apparently accelerated deglaciation starting in the 1850s. Our findings support a negligible role of human activity in forcing glacier recession at the end of the Little Ice Age, highlighting the role of natural drivers.
Barbara Stenni, Mark A. J. Curran, Nerilie J. Abram, Anais Orsi, Sentia Goursaud, Valerie Masson-Delmotte, Raphael Neukom, Hugues Goosse, Dmitry Divine, Tas van Ommen, Eric J. Steig, Daniel A. Dixon, Elizabeth R. Thomas, Nancy A. N. Bertler, Elisabeth Isaksson, Alexey Ekaykin, Martin Werner, and Massimo Frezzotti
Clim. Past, 13, 1609–1634, https://doi.org/10.5194/cp-13-1609-2017, https://doi.org/10.5194/cp-13-1609-2017, 2017
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Within PAGES Antarctica2k, we build an enlarged database of ice core water stable isotope records. We produce isotopic composites and temperature reconstructions since 0 CE for seven distinct Antarctic regions. We find a significant cooling trend from 0 to 1900 CE across all regions. Since 1900 CE, significant warming trends are identified for three regions. Only for the Antarctic Peninsula is this most recent century-scale trend unusual in the context of last-2000-year natural variability.
Tessa R. Vance, Jason L. Roberts, Andrew D. Moy, Mark A. J. Curran, Carly R. Tozer, Ailie J. E. Gallant, Nerilie J. Abram, Tas D. van Ommen, Duncan A. Young, Cyril Grima, Don D. Blankenship, and Martin J. Siegert
Clim. Past, 12, 595–610, https://doi.org/10.5194/cp-12-595-2016, https://doi.org/10.5194/cp-12-595-2016, 2016
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This study details a systematic approach to finding a new high-resolution East Antarctic ice core site. The study initially outlines seven criteria that a new site must fulfil, encompassing specific accumulation, ice dynamics and atmospheric circulation aspects. We then use numerous techniques including Antarctic surface mass balance syntheses, ground-truthing of satellite data by airborne radar surveys and reanalysis products to pinpoint promising regions.
Related subject area
Subject: Atmospheric Dynamics | Archive: Historical Records | Timescale: Centennial-Decadal
Could old tide gauges help estimate past atmospheric variability?
Reassessing long-standing meteorological records: an example using the national hottest day in Ireland
Extreme historical droughts and floods in the Hanjiang River Basin, China, since 1426
Influence of warming and atmospheric circulation changes on multidecadal European flood variability
Assimilating monthly precipitation data in a paleoclimate data assimilation framework
Historical droughts in the Qing dynasty (1644–1911) of China
Impact of different estimations of the background-error covariance matrix on climate reconstructions based on data assimilation
Causes of increased flood frequency in central Europe in the 19th century
A 305-year continuous monthly rainfall series for the island of Ireland (1711–2016)
Changes in the strength and width of the Hadley Circulation since 1871
Ecosystem effects of CO2 concentration: evidence from past climates
Paul Platzer, Pierre Tandeo, Pierre Ailliot, and Bertrand Chapron
EGUsphere, https://doi.org/10.5194/egusphere-2023-2997, https://doi.org/10.5194/egusphere-2023-2997, 2024
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Old observations are necessary to understand the atmosphere. When direct observations are not available, one can use indirect observations such as tide gauges, which measure the sea-level in portal cities. The sea level rises when local air pressure decreases, and when wind pushes water towards the coast. Several centuries-long tide gauge records are available. We show that these can be complementary to direct pressure observations for studying storms and anticyclones in the 19th century.
Katherine Dooley, Ciaran Kelly, Natascha Seifert, Therese Myslinski, Sophie O'Kelly, Rushna Siraj, Ciara Crosby, Jack Kevin Dunne, Kate McCauley, James Donoghue, Eoin Gaddren, Daniel Conway, Jordan Cooney, Niamh McCarthy, Eoin Cullen, Simon Noone, Conor Murphy, and Peter Thorne
Clim. Past, 19, 1–22, https://doi.org/10.5194/cp-19-1-2023, https://doi.org/10.5194/cp-19-1-2023, 2023
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The highest currently recognised air temperature (33.3 °C) ever recorded in the Republic of Ireland was logged at Kilkenny Castle in 1887. This paper reassesses the plausibility of the record using various methods such as inter-station reassessment and 20CRv3 reanalysis. As a result, Boora 1976 at 32.5 °C is presented as a more reliable high-temperature record for the Republic of Ireland. The final decision however rests with the national meteorological service, Met Éireann.
Xiaodan Zhang, Guoyu Ren, Yuda Yang, He Bing, Zhixin Hao, and Panfeng Zhang
Clim. Past, 18, 1775–1796, https://doi.org/10.5194/cp-18-1775-2022, https://doi.org/10.5194/cp-18-1775-2022, 2022
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Applying yearly drought and flood records from historical documents and precipitation data in the period of instrumental measurements, this study constructs a time series of extreme droughts and floods in the Hanjiang River Basin from 1426–2017 and analyzes the temporal and spatial characteristics of the extreme drought and flood event variations.
Stefan Brönnimann, Peter Stucki, Jörg Franke, Veronika Valler, Yuri Brugnara, Ralf Hand, Laura C. Slivinski, Gilbert P. Compo, Prashant D. Sardeshmukh, Michel Lang, and Bettina Schaefli
Clim. Past, 18, 919–933, https://doi.org/10.5194/cp-18-919-2022, https://doi.org/10.5194/cp-18-919-2022, 2022
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Floods in Europe vary on time scales of several decades. Flood-rich and flood-poor periods alternate. Recently floods have again become more frequent. Long time series of peak stream flow, precipitation, and atmospheric variables reveal that until around 1980, these changes were mostly due to changes in atmospheric circulation. However, in recent decades the role of increasing atmospheric moisture due to climate warming has become more important and is now the main driver of flood changes.
Veronika Valler, Yuri Brugnara, Jörg Franke, and Stefan Brönnimann
Clim. Past, 16, 1309–1323, https://doi.org/10.5194/cp-16-1309-2020, https://doi.org/10.5194/cp-16-1309-2020, 2020
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Data assimilation is becoming more and more important for past climate reconstructions. The assimilation of monthly resolved precipitation information has not been explored much so far. In this study we analyze the impact of assimilating monthly precipitation amounts and the number of wet days within an existing paleoclimate data assimilation framework. We find increased skill in the reconstruction, suggesting that monthly precipitation can constitute valuable input for future reconstructions.
Kuan-Hui Elaine Lin, Pao K. Wang, Pi-Ling Pai, Yu-Shiuan Lin, and Chih-Wei Wang
Clim. Past, 16, 911–931, https://doi.org/10.5194/cp-16-911-2020, https://doi.org/10.5194/cp-16-911-2020, 2020
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This study reconstructs drought chronologies of the Qing dynasty (1644–1911) based on Chinese documentary records from the REACHES database. In addition to drought records, ecological and societal records are also retrieved. Tests are performed to cross-check data and time series. Six severe drought periods are identified, and spatial patterns are revealed through multivariable analysis. Drought consequence networks are built highlighting human intervention affecting famine and social turmoil.
Veronika Valler, Jörg Franke, and Stefan Brönnimann
Clim. Past, 15, 1427–1441, https://doi.org/10.5194/cp-15-1427-2019, https://doi.org/10.5194/cp-15-1427-2019, 2019
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In recent years, the data assimilation approach was adapted to the field of paleoclimatology to reconstruct past climate fields by combining model simulations and observations.
To improve the performance of our paleodata assimilation system, we tested various techniques that are well established in weather forecasting and evaluated their impact on assimilating instrumental data and proxy records (tree rings).
Stefan Brönnimann, Luca Frigerio, Mikhaël Schwander, Marco Rohrer, Peter Stucki, and Jörg Franke
Clim. Past, 15, 1395–1409, https://doi.org/10.5194/cp-15-1395-2019, https://doi.org/10.5194/cp-15-1395-2019, 2019
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During the 19th century flood frequency was high in central Europe, but it was low in the mid-20th century. This paper tracks these decadal changes in flood frequency for the case of Switzerland from peak discharge data back to precipitation data and daily weather reconstructions. We find an increased frequency in flood-prone weather types during large parts of the 19th century and decreased frequency in the mid-20th century. Sea-surface temperature anomalies can only explain a small part of it.
Conor Murphy, Ciaran Broderick, Timothy P. Burt, Mary Curley, Catriona Duffy, Julia Hall, Shaun Harrigan, Tom K. R. Matthews, Neil Macdonald, Gerard McCarthy, Mark P. McCarthy, Donal Mullan, Simon Noone, Timothy J. Osborn, Ciara Ryan, John Sweeney, Peter W. Thorne, Seamus Walsh, and Robert L. Wilby
Clim. Past, 14, 413–440, https://doi.org/10.5194/cp-14-413-2018, https://doi.org/10.5194/cp-14-413-2018, 2018
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This work reconstructs a continuous 305-year rainfall record for Ireland. The series reveals remarkable variability in decadal rainfall – far in excess of the typical period of digitised data. Notably, the series sheds light on exceptionally wet winters in the 1730s and wet summers in the 1750s. The derived record, one of the longest continuous series in Europe, offers a firm basis for benchmarking other long-term records and reconstructions of past climate both locally and across Europe.
J. Liu, M. Song, Y. Hu, and X. Ren
Clim. Past, 8, 1169–1175, https://doi.org/10.5194/cp-8-1169-2012, https://doi.org/10.5194/cp-8-1169-2012, 2012
I. C. Prentice and S. P. Harrison
Clim. Past, 5, 297–307, https://doi.org/10.5194/cp-5-297-2009, https://doi.org/10.5194/cp-5-297-2009, 2009
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Short summary
The Southern Annular Mode (SAM) influences climate in the Southern Hemisphere. We investigate the effects of calculation method and data used to calculate the SAM index and how it influences the relationship between the SAM and climate. We propose a method to calculate a natural SAM index that facilitates consistency between studies, including when using different data resolutions, avoiding distortion of SAM impacts and allowing for more reliable results of past and future SAM trends.
The Southern Annular Mode (SAM) influences climate in the Southern Hemisphere. We investigate...