Investigating The Relationship Between Atmospheric Moisture Flux And The Surface Mass Balance On The Greenland Ice Sheet

Abstract:

One of the most striking changes occurring in the Arctic over the past decade is the increased mass loss and freshwater discharge from the Greenland ice sheet (GrIS). Improving our understanding and prediction of the mass balance and freshwater discharge of the GrIS requires improved knowledge of the different atmospheric drivers and weather events that impact the surface mass balance (SMB). In this study, we assess the relationship between both local and large-scale forcing of ocean heat and moisture advection (aka. moisture flux) on the GrIS SMB. To this aim, we employ a variety of tools and datasets such as the outputs of a regional climate model (Modèle Atmosphérique Régional, MAR) and reanalysis data. In particular, we test the hypothesis that useful information on the mass loss and freshwater discharge of the GrIS can be obtained from the computation of the atmospheric moisture flux in a Eulerian framework and focus on understanding the physical processes involved. Using the high-resolution outputs of a 35-year (1979–2014) simulation from the MAR model, we examine the spatiotemporal co-variability of mass loss and gain (divided regions based on latitude) during the strongest moisture flux events, as estimated from MAR and reanalysis datasets. We then classify the different weather events associated with the moisture flux that occur during strong mass loss events. Using conditional subsetting, rather than correlation analysis, our work identifies the spectrum of responses of the GrIS mass balance to strong atmospheric moisture fluxes into the region. Then, in a separate analysis, we characterize the variety of moisture fluxes that occur prior to large melt events.