Chyhareva A. Clouds and precipitation in the Antarctic Peninsula region: microphysics, mesoscale processes and climate projections to the end of the 21st century.

The study is devoted to determining the cloud and precipitation formation features on the microphysical, mesoscale and climatic scales for the region of the Antarctic Peninsula with the main focus on the intense precipitation events with a precipitation phase change and on the multi-year climate indices and atmospheric parameters associated with a change in the cloud and precipitation formation in the region from the end of the 20th to the end of the 21st century according to the modern climate projections. Polar atmospheric processes are an essential component of global circulation, significantly sensitive to climate change, and directly affect the formation of the weather regime in lower latitudes. However, the properties of clouds and precipitation in polar regions remain to be understudied due to the lack of field, aerological and satellite measurement data. It is also why the parameterization of clouds and precipitation in climate and forecast models remains a source of errors, making it impossible to obtain reliable information about the state of the polar atmosphere in particular. Therefore, a thorough study of cloud and precipitation formation processes by the high spatial and temporal resolution regional simulations and their verification with the measurement data, as well as assessing their climate projections, can improve the understanding of atmospheric processes in the polar regions and the quality of numerical modelling, including climate modelling, in the future. The study aims to determine the mesoscale and microphysical features of cloud and precipitation processes during intense precipitation events in the Antarctic Peninsula region and to analyze climate projections of the respective parameters until the end of the 21st century. The object of the study is clouds and precipitation over the Antarctic Peninsula region. The subjects of the study are the mesoscale and microphysical processes of cloud and precipitation formation during intense precipitation events with a phase transition over the Antarctic Peninsula region. Modern tools used in the study include global climate models, ERA5 reanalysis, and mesoscale numerical models Polar WRF. A comparative analysis of model configurations was conducted. We can assume that the selected configuration of Polar WRF with Thomson microphysical parameterization better represents the characteristics of clouds and precipitation in the northwestern Antarctic Peninsula. This chosen Polar WRF model configuration was applied and tested for the intense snowfall event in March 2013 over Europe, Ukraine and the central and western Ukraine. It was shown that the chosen microphysical configuration of the WRF numerical model produced similar amount of measured precipitation and therefore could be used to study the intense snowfall processes over Ukraine. Atmospheric circulation processes, mesoscale conditions, and microphysical characteristics of cloud and precipitation formation during the intense precipitation events with a phase transition over the Antarctic Peninsula were analyzed. Based on the analysis of droplet and crystal distributions’ 3D visualization, the presence of rain cells along the west coast of the Antarctic Peninsula, even during the winter cyclonic event, was determined, as well as the relative location of snow, ice crystals and droplets of different sizes in the Antarctic Peninsula region during moments of intense precipitation on the west coast of the peninsula Several indices and parameters proposed by WMO to unify assessment of meteorological processes were analyzed, but we selected mostly indices that represent climate changes near melting point. Namely, they are numbers of ice and frost days associated with the presence or absence of ice melting processes, continuous periods with/without significant precipitation associated with accumulation/ablation of glacier mass, liquid fraction and extreme precipitation. Spatial analysis of the selected indices provides an opportunity to determine the regional features of the Antarctic Peninsula climate, as they represent not only the change of the essential climate parameters but more generally the regime of temperature, precipitation and cloud cover.