A235-07
Influence of föhn winds on surface melting in Northeast Greenland and their relationships with atmospheric rivers
Wednesday, 16 December 2020: 07:19
Virtual
Jenny Turton, University Erlangen-Nürnberg, Erlangen, Germany, Kyle Stephen Mattingly, University of Georgia, Athens, GA, United States, Xavier Fettweis, University of Liège, Liège, Belgium, Jonathan Wille, University Grenoble Alpes, IGE, Saint Martin d'Hères, France and Brice Noel, Institute for Marine and Atmospheric Research Utrecht, Utrecht, Netherlands
Abstract:
Atmospheric Rivers (ARs), narrow filaments of concentrated moisture transport, have direct impacts on the Surface Mass Balance (SMB) of western Greenland through increased melting in the ablation area and increased snowfall in higher altitudes. Here, we show that an indirect or secondary effect of ARs on the SMB comes from the development of föhn winds, whereby the air is adiabatically warmed as it descends. As ARs pass over the ice sheet and deposit precipitation on the west coast, the air flows down the east slope and the warm, dry conditions contribute to increased melting along the northeast coast, and more specifically for Nioghalvfjerdsfjorden (or 79N Glacier).
We identify föhn events using an automated detection algorithm applied to MAR and RACMO2 regional climate model output. These data are paired with an AR detection algorithm and self-organizing map (SOM) classification applied to MERRA-2 and ERA5 reanalyses, in order to investigate connections between ARs, regional circulation patterns, föhn winds, and ice sheet surface melt. We find that approximately 70% of the ARs which make landfall in the northwest sector of Greenland lead to the development of föhn winds on the northeast coast. The föhn winds contribute to increased mass loss through a combination of excess shortwave radiation and sensible heat flux. The frequency of AR-induced föhn conditions has increased in the last 40 years, in line with an increase in the strongest ARs.
