Recent Ice sheet surface warming events over coastal Dronning Maud Land, East Antarctica: Causes and Implications

Gayathri, Eledath M.; Laluraj, Chavarukonam M.; Satheesan, Karathazhiyath; Matsuoka, Kenichi; Thamban, Meloth

Sudden short-term warming events over the ice sheet surface (hereafter Ice Sheet Surface Warming (ISSW) events) can affect mass balance by sublimation and on rare occasions melting when the temperature rises above 0 °C. On the one hand, the knowledge of the frequency and duration of these warming events is essential, while on the other hand, a process-level understanding of them is crucial for incorporating in climate models and tracing their behaviour in future climate scenarios. Here, we examined the ISSW events over coastal Dronning Maud Land (cDML) in East Antarctica using the borehole temperature record of an ice core covering a period of 2014–18 CE. The borehole surface thermistor record provided accurate estimation of year-round ISST and subsurface heat flux in the region. In total, 71 warming events (> 2 ºC for > 3 days) with a maximum warming of 11 °C were recorded during the period. They mostly occurred during spring (24) and winter (23), followed by autumn (15) and least in summer (9). The general meteorological setting during these events was the occurrence of strong winds. It was found that 84 % of ISSW events occurred during strong easterly winds with high snow accumulation, while 16 % occurred during strong southeasterly winds (katabatic) without any precipitation. The study suggests that for the first case, intense downward longwave radiation associated with warm air advection (with moisture from the surrounding ocean) heated the ice sheet’s surface and led to snowfall. For the second case, turbulent mixing due to strong and dry winds from the interior of the continent (katabatic) led to ISSW. Furthermore, the synoptic conditions during ISSW events differed by changes in the relative positions of low pressure and high pressure over the southern ocean. Considering the drastic drop in accumulation in cDML since 1906 CE, a simultaneous increase in ISSW events (via their sublimation and melting rates), appears to have greater implications on the mass balance and stability of coastal Antarctic ice sheets in the long term.

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Gayathri, Eledath M. / Laluraj, Chavarukonam M. / Satheesan, Karathazhiyath / et al: Recent Ice sheet surface warming events over coastal Dronning Maud Land, East Antarctica: Causes and Implications. 2023. Copernicus Publications.

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