Atmospheric and Oceanic Sciences Departmental Seminar Series
Precipitation and atmospheric rivers over Southern Ocean and Antarctica
a talk by
Assistant Researcher, Centre for Environmental and Marine Studies
University of Aveiro, Portugal
Intensification of the global hydrological cycle has been linked with increased precipitation in mid latitudes and polar regions. Increased precipitation over Antarctica affects the ice sheet mass balance and its contribution to global sea level rise. At the same time, more precipitation over the Southern Ocean causes its freshening with important consequences for ecosystems and ocean dynamics. During individual events, the partitioning of precipitation between the ocean and the ice sheet depends strongly upon several atmospheric and air-sea interaction processes. These include the underlying large- and meso-scale atmospheric dynamics, evaporation rates from the surrounding ocean surface, and the intensity of the moisture flux during individual events, particularly the phenomena known as atmospheric rivers. Atmospheric models used for simulating weather and climate show significant differences in cloud and precipitation properties. The problem lies not only in the need to improve model parametrisations but also in the lack of cloud and precipitation measurements in these regions, leading to large uncertainties in model estimates of variability and trends in Southern Ocean and Antarctic precipitation. Since 2009 first precipitation radar was installed in the escarpment zone of East Antarctica at the Belgian Antarctic station Princess Elisabeth allowing long-term measurements of precipitation reaching the ground and also virga.
Several other countries have followed with long-term measurements of precipitation using precipitation radar. Unique precipitation measurements using a multi-sensor approach were performed during the Swiss Polar Institute's Antarctic Circumnavigation Expedition (December 2016-March 2017) along with radiosonde profiling. During the last years intensive collaboration among different teams working in several countries, including Belgium, Switzerland, France, Italy, Portugal, UK, as well as other comprehensive measurement campaigns (by US, Australia, New Zealand), have marked the unprecedented collaborative efforts in characterizing precipitation over Antarctica and Southern Ocean. In this presentation I will discuss the most recent results concerning precipitation measurements and modeling, and particularly intense precipitation events associated with atmospheric rivers, in Antarctica and Southern Ocean.