Seasonal evaluation of surface mass balance and firn model outputs from satellite and airborne lidar mapping
Abstract
We present estimates of seasonal surface elevation change of the Greenland Ice Sheet (GrIS) from a novel combination of satellite and airborne laser altimetry measurements. Our method combines measurements from the Airborne Topographic Mapper (ATM), the Land, Vegetation and Ice Sensor (LVIS), and the second Ice, Cloud and land Elevation Satellite (ICESat-2) to generate elevation change rates at high spatial resolution. We use the altimetry-derived elevation changes to evaluate the uncertainty in surface mass balance (SMB) and firn elevation change derived from both regional and global climate models. Here, we are evaluating estimates from the Regional Atmospheric Climate Model (RACMO2.3p2), the Modèle Atmosphérique Régional (MARv3.9), and the second iteration of the NASA Modern-Era Retrospective analysis for Research and Applications (MERRA-2). We are using seasonal elevation differences from 2013, 2015, 2016, 2017 and 2018, which vary in terms of the regional magnitude and driving processes. We investigate locations with low ice sheet surface velocities that are within the estimated ablation zones of each climate model. We evaluate over regions of Southwest Greenland that have land-terminating glaciers because temporal variability in runoff is typically the dominant process driving seasonal surface elevation change. We are also evaluating over regions of North Greenland due to the regional sensitivity to Arctic oceanic conditions and sea ice presence, as well as the increase in the number of melt days over our observation period. Despite the increase in the number of melt days, the rate of elevation change determined from the flight-line in North Greenland was much lower in 2017 than in 2015. For our regions in Southwest and North Greenland, we find that the model error typically increases during cold periods but varies significantly spatially over the available summer seasons.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.C41A..03S
- Keywords:
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- 3360 Remote sensing;
- ATMOSPHERIC PROCESSES;
- 0726 Ice sheets;
- CRYOSPHERE;
- 0750 Sea ice;
- CRYOSPHERE;
- 4556 Sea level: variations and mean;
- OCEANOGRAPHY: PHYSICAL