Comparison of snow accumulation from global data products using a new seasonal mountain snow classification
Abstract
Mountain snow accumulation has a fundamental role in regional water balances, with disproportionately more snow water storage (SWS) in mountains than lowland areas. However, there is little consensus for defining snow-covered mountains on a global scale. Here we use GTOPO30 digital elevation model and remotely sensed MODIS imagery to create a new dataset for classifying global seasonal mountain snow (SMS) accumulation at a spatial resolution of 30 arc-seconds ( 1 km). In our definition, SMS remains on the ground for a minimum duration of 56 days (corresponding to 7 consecutive 8-day MODIS periods, allowing for cloud cover). Of the nearly 30 million km2 of mountain area, SMS covers 12 million km2, or 40% of global mountains. Using our new SMS classification, we show there is little agreement of mountain SWS from four global data products (ERA-Interim, GLDAS, MERRA, and VIC), with peak snowy mountain SWS ranging from 907 km3 to 1360 km3. Though snowy mountains are only 9% of the global land area, they hold 22-31% of the global snow accumulation, as estimated by each global dataset. When compared to a higher-resolution regional climate model estimate of North American mountain SWS, the global data products underestimate by 40-66%, a negative bias up to 651 km3. Assuming the global data products have a similar bias for other continents, current modeled representation of mountain SWS may not only be too low by 1500 km3, but snowy mountains may hold an even larger percentage of global SWS. Through application of our new SMS classification, we suggest that insufficient mountain representation in global models may be biasing our understanding of the not only the global water budget, but also the global energy balance.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.H22B..02W
- Keywords:
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- 0736 Snow;
- CRYOSPHEREDE: 0740 Snowmelt;
- CRYOSPHEREDE: 1860 Streamflow;
- HYDROLOGYDE: 1863 Snow and ice;
- HYDROLOGY