Annual Snow Accumulation in the Antarctic Peninsula and the West Antarctica Ice Sheet from 1979 to 2008

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Abstract We investigated the annual net snow accumulation rate differences between the Antarctic Peninsula (AP) and the West Antarctic Ice Sheet (WAIS) over 29 years (1979–2008 CE). We compared the results from two ice cores, one from the AP, Detroit Plateau (DP) (64°05′S, 59°38′W), and another from the WAIS, Mount Johns (79°55′S, 94°23′W), with results from previous studies: two from the AP, Bruce Plateau (66°03′S, 64º07′W), and Gomez (73°59′S, 70°36′W), and one from the WAIS, Ferrigno (74°34′S, 86°54′W). We used ERA5 reanalysis to investigate the behavior of atmospheric circulation in the South Pacific Ocean and its influence on snow precipitation variability. The correlation between annual net snow accumulation rate and meridional wind V at 850 hPa, as recorded in ERA5 in the AP, showed a marked increase from 1979–92 to 1993–2008. Between the two periods, there was an increase in the annual net snow accumulation rate by up to 33% (DP) at AP sites, with a decrease toward the south; no differences were observed between the two WAIS sites. A positive Southern Annular Mode (SAM) trend since 1993 deepened the Amundsen Sea low (ASL) and increased cyclonic activity and precipitation, especially in the AP, as evidenced by the increase in both zonal and meridional flows. However, the WAIS cores did not show a statistically significant trend. There was a sharp transition in the variability of accumulation between the southern AP and the eastern part of the WAIS. Significance Statement The southern oceanic sector west of the Antarctic Peninsula (AP) is sensitive to climate change. Many cold air masses that advance over South America are associated with frontal systems originating in the Amundsen and Bellingshausen Seas. We investigated the net snow accumulation rate (NSAR) variability from 1979 to 2008 using five ice cores from the AP and the West Antarctic Ice Sheet (WAIS). There was a marked increase in the accumulation rate on the AP, associated with migration further east and the strengthening of the Amundsen Sea low, which was predominantly associated with a positive Southern Annular Mode (SAM) in recent decades. Similar increases were not observed in the WAIS, which is subject to interannual teleconnections. The results of this study are relevant for understanding the development and intensification of extratropical cyclones that originate in the Southern Ocean and move to the South Atlantic and help to interpret the differences found in ice cores collected in the two geographic regions of the study.

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