Multi‐year assessment of atmospheric circulation and impacts on air temperature variation on James Ross Island, Antarctic Peninsula

Abstract

The influence of synoptic‐scale circulation on air temperature variation in the ice‐free and glaciated areas on the eastern side of the Antarctic Peninsula (AP) has been analysed. For this purpose, a new classification of atmospheric circulation with 15 synoptic patterns in the AP region was developed using the self‐organizing maps technique. The synoptic patterns were compared with air temperature observations from coastal and glacial sites on James Ross Island, northeastern AP, in the period 2005–2015. The most frequent synoptic pattern with a frequency of 13.7% was dominated by a low‐pressure centre in the northwestern Bellingshausen Sea, which extended over the AP to the Weddell Sea. On the other hand, the largest inter‐annual variability was observed for a synoptic pattern with a low‐pressure centre in the southern Bellingshausen Sea. This synoptic pattern also had the highest air temperature anomalies at both investigated sites year‐round. Air temperature anomalies at the lower lying site (Mendel station) were the lowest during a high‐pressure ridge dominating the AP region due to a combination of local and synoptic‐scale processes. At Davies Dome, the glacial site, southerly barrier winds advecting cold air from the ice‐covered Weddell Sea during a strong low‐pressure system in the Weddell Sea ensured the coldest air temperature anomalies.

Interannual variability of air temperature inversions in ice-free area of northern James Ross Island, Antarctica

“…10f) reveals that during the years with the anomaly, the geopotential height just to the west of the AP was by more than 50 m higher than without the anomaly. That could indicate that the warm westerly airflow towards JRI was likely less intensive with a less deep or frequent cyclone in the Bellingshausen Sea, yielding the space to high-pressure ridges, which frequently occur in the AP Region in winter (Ambrožová et al 2020).…”

“…Continuous snow cover on the Ulu Peninsula usually occurs from the second half of March until the second half of September (Hrbacek et al 2016), but the distribution of snow cover is greatly affected by the prevailing south to south-westerly winds (Kavan et al 2020). Mean sea ice fraction around JRI was 0.12 in austral summer and 0.33 in austral winter (Ambrozova et al 2019) with a usual sea ice break-up around 17 December (Ambrožová et al 2020).…”

High-Resolution Numerical Modelling of Near-Surface Atmospheric Fields in the Complex Terrain of James Ross Island, Antarctic Peninsula

“…These inversions contribute to relatively low mean annual near-ground lapse rates of 0.40-0.43 • C•100 m −1 [47]. The dominant southwestern wind direction on the Ulu Peninsula is the result of the regular barrier winds blowing along the eastern AP coast [48].…”

Persistent mass loss of Triangular Glacier, James Ross Island, north-eastern Antarctic Peninsula

“…Climate conditions in the study area are affected by the predominantly western circulation across the Antarctic Peninsula, the southerly barrier winds from the Antarctic interior and the sea-ice extent variations in the north-western sector of the Weddell Sea (King, 1994; Turner and others, 2016; Ambrožová and others, 2020). The mean annual air temperature decreases from −7.0 °C at sea level to <−8.0 °C at high-elevation areas (Ambrožová and others, 2019).…”