Much of my scholarship examines the role of atmospheric circulation on extremes in rainfall, snowfall, and ice ablation. For more than two decades, I have studied the climate of the polar regions, particularly the role of atmospheric blocking and atmospheric rivers on the surface mass balance of the Greenland ice sheet. More recent work has taken me to the Caribbean, where I study the impact of climate, land cover change, and atmospheric aerosols on precipitation and drought. Ongoing projects are supported by grants from the U.S. Navy and NSF.