Quantifying Greenland Ice Sheet snowmelt that results from atmospheric blocking events
Abstract
Because extensive Greenland Ice Sheet (GrIS) melt could lead to considerable sea level rise, processes that affect GrIS melt are of interest to the scientific community. Summer snowmelt of the GrIS margins is common, but some atmospheric processes can also lead to snowmelt in high elevation accumulation zones. One of these processes is atmospheric blocking, which occurs when a large anticyclone remains over a region for an extended period of time and diverts incident upper-level airflow. Anticyclones ("blocks") located near Greenland can transport warm subtropical air over the ice sheet and lead to enhanced snowmelt. In July 2012, atmospheric blocking was at least partly responsible for snowmelt that was recorded over 98% of the GrIS (Nghiem et al., 2012). Although other atmospheric blocks have formed and dissipated over the Greenland region, the areal extent of July 2012 snowmelt was the largest on record during the satellite era. In this study, we apply MERRA-2 reanalysis data to drive the Community Land Model (CLM) and simulate the impacts of atmospheric blocking on GrIS snowmelt in the summer (June, July, and August, or JJA) from 1980 to 2016. We identify atmospheric blocks in JJA using the Greenland Blocking Index (Hanna et al., 2014). In order for an event to be considered a Greenland block, its spatially-averaged 500mb geopotential height must be larger than the seasonal average 500mb geopotential height for at least five consecutive days. For each blocking event we calculate the anomalous snowmelt that occurs relative to non-blocking conditions during the same time of year. We then apply this analysis to determine the relationship between GrIS snowmelt and 500mb geopotential height anomalies.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.A43D2476W
- Keywords:
-
- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSES;
- 3339 Ocean/atmosphere interactions;
- ATMOSPHERIC PROCESSES;
- 3364 Synoptic-scale meteorology;
- ATMOSPHERIC PROCESSES;
- 1621 Cryospheric change;
- GLOBAL CHANGE