Preprints
https://doi.org/10.5194/cp-2020-151
https://doi.org/10.5194/cp-2020-151

  10 Dec 2020

10 Dec 2020

Review status: this discussion paper is a preprint. It has been under review for the journal Climate of the Past (CP). The manuscript was not accepted for further review after discussion.

Mineral Dust Influence on the Glacial Nitrate Record from the RICE Ice Core, West Antarctica and Environmental Implications

Abhijith U. Venugopal1, Nancy A. N. Bertler1,2, Rebecca L. Pyne2, Helle A. Kjær3, V. Holly L. Winton1, Paul A. Mayewski4, and Giuseppe Cortese2 Abhijith U. Venugopal et al.
  • 1Antartic Research Centre, Victoria University of Wellington, Wellington, New Zealand
  • 2GNS Science, Lower Hutt, Wellington, New Zealand
  • 3Centre for Ice and Climate, Physics of Ice, Climate and Environment, Niels Bohr Institute, University of Copenhagen, Denmark
  • 4Climate Change Institute, University of Maine, Orono, ME, USA

Abstract. Nitrate (NO3), an abundant aerosol in polar snow, is a complex environmental proxy to interpret owing to the variety of its sources and its susceptibility to post-depositional processes. During the last glacial period, when the dust level in the Antarctic atmosphere was higher than today by a factor up to ~25, mineral dust appears to have a stabilizing effect on the NO3 concentration. However, the exact mechanism remains unclear. Here, we present new and highly resolved records of NO3 and non-sea salt calcium (nssCa2+, a proxy for mineral dust) from the Roosevelt Island Climate Evolution (RICE) ice core for the period 26–40 kilo years Before Present (ka BP). This interval includes seven millennial-scale Antarctic Isotope Maxima (AIM) events, against the background of a glacial climate state. We observe a significant correlation between NO3 and nssCa2+ over this period and especially during AIM events. We put our observation into a spatial context by comparing the records to existing data from east Antarctic cores of EPICA Dome C (EDC), Vostok and central Dome Fuji. The data suggest that nssCa2+ is contributing to the effective scavenging of NO3 from the atmosphere through the formation of Ca(NO3)2. The geographic pattern implies that the process of Ca(NO3)2 formation occurs during the long-distance transport of mineral dust from the mid-latitude source regions by Southern Hemisphere Westerly Winds (SHWW) and most likely over the Southern Ocean. Since NO3 is dust-bound and the level of dust mobilized through AIM events is mainly regulated by the latitudinal position of SHWW, we suggest that NO3 may also have the potential to provide insights into paleo-westerly wind pattern during the events.

Abhijith U. Venugopal et al.

 
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Abhijith U. Venugopal et al.

Abhijith U. Venugopal et al.

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Short summary
We present a new and highly resolved glacial record of nitrate and calcium from a deep ice core obtained from Roosevelt Island, West Antarctica. Our data show a dependent association among nitrate and non-sea salt calcium (mineral dust) as observed previously in East Antarctica. The spatial pattern indicates that mineral dust is scavenging nitrate from the atmosphere and the westerlies are dispersing the dust-bound nitrate across Antarctica, making nitrate a potential paleo-westerly wind proxy.