Potential mechanisms governing the variation in rain/snow frequency over the northern Antarctic Peninsula during austral summer

Precipitation with different phases can exert different influences on the Antarctic mass balance. Using the observational rain and snow days from the Great Wall Station, ERA-interim reanalysis, and other data, this study investigates the mechanisms governing the year-to-year variability of precipitation phase (i.e., rainfall and snowfall) over the northern Antarctic Peninsula (AP) during austral summer (December, January, and February; abbreviated as DJF) for the period 1985-2016. The results reveal that the rainfall and snowfall anomalies are controlled mainly by the change in the proportion of precipitation occurring as rain and snow, and the latter is strongly influenced by the change in air temperature. Through regulating the air temperature, different atmospheric circulation anomalies affect the variability of the rainfall and snowfall over the northern AP during summer. Specifically, a circulation pattern with an anomalous anticyclone over the Malvinas Islands and an anomalous cyclone over the Amundsen-Bellingshausen Seas (ABS) can increase summer rainfall, whereas an anomalous cyclone over the Weddell Sea facilitates more snowfall. The summertime atmospheric circulation anomalies, which modulate the variability of rainfall over the northern AP, are primarily caused by an atmospheric teleconnection pattern persisting from austral spring (September-November, SON) to summer. Such a persistent teleconnection pattern can be attributed to the long-time maintenance of sea surface temperature anomalies due to air-sea interaction processes.