Bill Neff

After efforts over several decades focused on Antarctica and its unique meteorological and chemical environment, my recent research has turned to the Greenland ice sheet.  Of particular interest has been boundary layer behavior at Summit Station as part of the decade-long ICECAPS field program (Integrated Characterization of Energy, Clouds, Atmospheric state, and Precipitation at Summit).   Initially, I focused on the role of atmospheric rivers (ARs) in transporting warm, high-moisture air to Summit Station associated with the dramatic melt episode that occurred in 2012 and compared it to the previous episode in 1889 using the Twentieth Century Reanalysis (Neff et al., JGR, 2014).   More recently, two more episodes occurred in June and late July 2019 related to heat waves over Europe and northwest Africa.  These melt cases also raised the question of the role of multiple melt events preconditioning the subsurface ice layers (e.g. Walden et al. A235-09, AGU 2020 Fall Meeting). In addition, I have discovered past cases where hurricanes, as they migrated north through the Atlantic, became extratropical and decayed near Greenland bringing additional warm air and moisture to the ice sheet. Hurricane Irene in 2011 provided one example associated with a major mass loss event in late August.  These initial results were presented as an Invited Talk at the Fall 2020 Meeting of the AGU (Neff et al, A235-01). More generally the ICECAPS data set will provide an opportunity for more extensive analysis of the role of clouds, aerosols, and atmospheric dynamics on surface exchange processes over the ice sheet.