El Niño–Southern Oscillation signal in a new East Antarctic ice core, Mount Brown South
<p>Paleoclimate archives, such as high-resolution ice core records, provide a means to investigate past climate variability. Until recently, the Law Dome (Dome Summit South site) ice core record remained one of few millennial-length high-resolution coastal records in East Antarctica. A new ice...
| Main Authors: | , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-09-01
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| Series: | Climate of the Past |
| Online Access: | https://cp.copernicus.org/articles/17/1795/2021/cp-17-1795-2021.pdf |
| Summary: | <p>Paleoclimate archives, such as high-resolution ice core records, provide a
means to investigate past climate variability. Until recently, the Law Dome
(Dome Summit South site) ice core record remained one of few
millennial-length high-resolution coastal 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 snow accumulation rates and sea salt
concentrations in the upper portion (<span class="inline-formula">∼</span> 20 m) of three Mount
Brown South ice cores and an updated Law Dome record over the period
1975–2016. Annual sea salt concentrations from the Mount Brown South site
record preserve a stronger signal for the El Niño–Southern Oscillation
(ENSO; austral winter and spring, <span class="inline-formula"><i>r</i></span> <span class="inline-formula">=</span> 0.533, <span class="inline-formula"><i>p</i></span> <span class="inline-formula"><</span> 0.001, Multivariate El Niño Index) compared to a previously defined Law Dome record of summer sea salt concentrations (November–February, <span class="inline-formula"><i>r</i></span> <span class="inline-formula">=</span> 0.398, <span class="inline-formula"><i>p</i></span> <span class="inline-formula">=</span> 0.010, Southern
Oscillation Index). The Mount Brown South site record and Law Dome record
preserve inverse signals for the ENSO, possibly due to longitudinal
variability in meridional transport in the southern Indian Ocean, although
further analysis is needed to confirm this. 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 correspond to years of low (high) sea
salt deposition at Mount Brown South during La Niña (El Niño)
events. The extended Mount Brown South annual sea salt record (when
complete) may 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.</p> |
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| ISSN: | 1814-9324 1814-9332 |