El Nino Southern Oscillation signal in a new East Antarctic ice core, Mount Brown South

• Published in: Climate of the Past
• Main Authors: Crockart, CK, Vance, TR, Fraser, AD, Abram, NJ, Criscitiello, AS, Curran, MAJ, Favier, V, Gallant, AJE, Kjaer, HA, Klekociuk, AR, Jong, LM, Moy, AD, Plummer, CT, Vallelonga, PT, Wille, J, Zhang, L
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus GmbH 2021
• Subjects: Earth Sciences; Climate change science; Climate change processes; Antarctic; East Antarctica; Austral; Pacific; Indian; Law Dome; South Ice; Mount Brown; Antarc*; Antarctica; ice core
• Online Access: https://doi.org/10.5194/cp-17-1795-2021; http://ecite.utas.edu.au/143518

Abstract. Paleoclimate archives, such as high-resolution ice core records, provide a means to investigate long-term (multi-centennial) climate variability. Until recently, the Law Dome (Dome Summit South) ice core record remained one of few long-term high-resolution records in East Antarctica. A new ice core drilled in 2017/2018 at Mount Brown South, approximately 1000 km west of Law Dome, provides an additional high-resolution record that will likely span the last millennium in the Indian Ocean sector of East Antarctica. Here, we compare snowfall accumulation rates and sea salt concentrations in the upper portion (~21 m) of the Mount Brown South record, and an updated Law Dome record over the period 19752016. Annual sea salt concentrations from the Mount Brown South record preserves a stronger signal for the El Nio-Southern Oscillation (ENSO; in austral winter and spring, r = 0.521, p < 0.000, Nio 3.4) compared to the Law Dome record (NovemberFebruary, r = −0.387, p = 0.018, Nio 3.4). The Mount Brown South and Law Dome ice cores record inverse signals for the ENSO, suggesting the occurrence of distinct moisture and aerosol intrusions. We suggest that ENSO-related sea surface temperature anomalies in the equatorial Pacific drive atmospheric teleconnections in the southern mid-latitudes. These anomalies are associated with a weakening (strengthening) of regional westerly winds to the north of Mount Brown South that corresponds to years of low (high) sea salt deposition at Mount Brown South during La Nia (El Nio) events. The Mount Brown South annual sea salt record when complete will offer a new proxy record for reconstructions of the ENSO over the recent millennium, along with improved understanding of regional atmospheric variability in the southern Indian Ocean in addition to that derived from Law Dome.