Precipitation events and atmospheric waves on Greenland's west coast

The supply of atmospheric moisture in the Arctic is increasing with the warming global climate, owing both to higher volumes of moisture advection into the region and to enhanced local evaporation. Correspondingly, overall precipitation amounts and the frequency of large individual precipitation events are increasing as well. Due to the relative sparsity of observations in the region, however, the local microphysical and dynamical processes which translate the moisture content into precipitation remain poorly studied and classified. We build on a comprehensive observational dataset from a research site in Qeqertarsuaq, Greenland to characterise the local boundary layer structure during precipitation events. The observations include, besides standard surface climate parameters, atmospheric profiles of temperature and humidity from a microwave radiometer and cloud observations from an optical camera. Dynamical processes are studied by combining observations and the CARRA reanalysis, with a focus on internal gravity waves which trigger precipitation events when they interact with local topography and atmospheric moisture. Both our observations and CARRA are also used to validate and bias-correct simulations of regional atmospheric models (in particular, HIRHAM) performed as part of the PROTECT project, which allow an assessment of how the precipitation-generating processes will change in the future.