MAPS: Measurements and modeling of the atmospheric and oceanic boundary layers at the northern Antarctic Peninsula during the Year of Polar Prediction Special observing periods
The Antarctic Peninsula (AP) has shown a much stronger warming trend compared to the rest of the ice sheet and other land areas in the Southern Hemisphere (SH) during the last several decades leading to the extensive surface melt, destabilizing the ice shelves around the AP and accelerating ice loss. At the same time, the AP has also experienced increase in precipitation, and one of the key questions regarding the present and future climate change – will there be a shift from snowfall to rainfall at the AP similar to the Arctic. Atmospheric rivers (ARs) – long corridors of intense moisture transport from subtropical and mid-latitude regions poleward - are known for their prominent role in the poleward heat and moisture transport. Their impacts in the Antarctic region range from intense snowfall over the ice sheet, to strong rainfall over the Southern Ocean and near-surface air temperature records with major surface melt events at the AP and West Antarctica.
Both the surface warming and type/amount of precipitation are tightly linked with the cloud supercooled liquid water content. The ARs are also associated with high wind speeds increasing wave heights near the AP, which might lead to the increased white capping. Sea surface whitecaps play a significant role in momentum exchange between atmosphere and ocean, and also influence gas and aerosol exchange. In turn, the primary (sea salt) and secondary (organics) aerosols act as cloud condensation and ice nuclei and determine cloud microphysical properties. In this exploratory project, we will investigate the potential connection between the increased white capping and cloud supercooled liquid water content, together with the analysis of biological and chemical composition of precipitation.
Given the short duration of the project, we will focus on specific AR events affecting the AP. MAPS will be using the data generated during the Year of Polar Prediction in the SH (YOPP-SH), which is a flagship activity of the Polar Prediction Project, a 10-year (2013-2022) initiative of the World Meteorological Organization’s World Weather Research Programme. YOPP-SH goal is to enable significantly improved weather, climate and environmental prediction services for the polar regions, on time scales from hours to seasonal. Within the MAPS project we will apply and analyze in detail measurements from the YOPP-SH summer and winter special observing periods during austral summer 2018/2019 and winter months (April-July) in 2022 as well as related special campaigns conducted in the northern AP, and will conduct new measurements in order to explore new ideas in process understanding concerning the impact of the extra-tropical cyclones and ARs in the atmospheric and oceanic boundary layers in Antarctica and precipitation composition.
The MAPS project methodology is based on the YOPP-SH approach of enhanced measurements and modeling during targeted observing periods with a specific focus on the changes in the atmospheric and oceanic boundary layers during the ARs. This will include near-surface wind speeds, significant wave heights and wave breaking generated in response (which leads to increased production and supply of the aerosols), precipitation composition analysis (for the presence of sea salt and organics that play an important role as cloud condensation and ice nuclei), and cloud and precipitation microphysical properties. Atmospheric boundary layer and tropospheric profile during specific events will be measured using radiosondes (providing temperature, humidity, pressure and wind speed and direction along the profiles) together with the cloud sensors measuring supercooled liquid water content. Ground-based remote sensing instruments (already installed at the Escudero base on King George Island) will be used to derive precipitation and cloud properties. For wind-wave and whitecap modeling, we will apply the spectral wave model WAVEWATCH-III, where parameterization of whitecap properties has been recently implemented. Simultaneous characterization of the increase in the near-surface wind speeds and evaluating the ability of both atmospheric reanalyses and wave models to represent such events, their effects on the whitecap production along with atmospheric state and cloud microphysical properties during the AR, has not been attempted so far and is the goal of this exploratory project. Targeting both atmospheric and oceanic impacts that we propose in the MAPS project is novel and will bring new insights into the key processes controlling cloud and precipitation properties and their links with the Antarctic Peninsula warming and oceanic state. The MAPS project brings together an interdisciplinary team of experts, includes training of young scientists, dissemination of the scientific results and outreach to the general public.