Abstract. Paleoclimate archives, such as high-resolution ice core records, provide ameans to investigate past climate variability. Until recently, the Law Dome(Dome Summit South site) ice core record remained one of fewmillennial-length high-resolution coastal records in East Antarctica. A newice core drilled in 2017/2018 at Mount Brown South, approximately 1000 kmwest of Law Dome, provides an additional high-resolution record that willlikely span the last millennium in the Indian Ocean sector of EastAntarctica. Here, we compare snow accumulation rates and sea saltconcentrations in the upper portion (∼ 20 m) of three MountBrown South ice cores and an updated Law Dome record over the period1975–2016. Annual sea salt concentrations from the Mount Brown South siterecord preserve a stronger signal for the El Niño–Southern Oscillation(ENSO; austral winter and spring, r = 0.533, p < 0.001, Multivariate El Niño Index) compared to a previously defined Law Dome record of summer sea salt concentrations (November–February, r = 0.398, p = 0.010, SouthernOscillation Index). The Mount Brown South site record and Law Dome recordpreserve inverse signals for the ENSO, possibly due to longitudinalvariability in meridional transport in the southern Indian Ocean, althoughfurther analysis is needed to confirm this. We suggest that ENSO-related seasurface temperature anomalies in the equatorial Pacific drive atmosphericteleconnections in the southern mid-latitudes. These anomalies areassociated with a weakening (strengthening) of regional westerly winds tothe north of Mount Brown South that correspond to years of low (high) seasalt deposition at Mount Brown South during La Niña (El Niño)events. The extended Mount Brown South annual sea salt record (whencomplete) may offer a new proxy record for reconstructions of the ENSO overthe recent millennium, along with improved understanding of regionalatmospheric variability in the southern Indian Ocean, in addition to thatderived from Law Dome.
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Seasonally Resolved Holocene Sea Ice Variability Inferred From South Pole Ice Core Chemistry
Variability in sea ice is a critical climate feedback, yet the seasonal behavior of Southern Hemisphere sea ice and climate across multiple timescales remains unclear. Here, we develop a seasonally resolved Holocene sea salt record using major ion measurements of the South Pole Ice Core (SPC14). We combine the SPC14 data with the GEOS‐Chem chemical transport model to demonstrate that the primary sea salt source switches seasonally from open water (summer) to sea ice (winter), with wintertime variations disproportionately responsible for the centennial to millennial scale structure in the record. We interpret increasing SPC14 and circum‐Antarctic Holocene sea salt concentrations, particularly between 8 and 10 ka, as reflecting a period of winter sea ice expansion. Between 5 and 6 ka, an anomalous drop in South Atlantic sector sea salt indicates a temporary sea ice reduction that may be coupled with Northern Hemisphere cooling and associated ocean circulation changes.
more » « less- Award ID(s):
- 1702266
- NSF-PAR ID:
- 10373277
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 48
- Issue:
- 8
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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