Snow, runoff, and mass balance modeling for the entire Mittivakkat Glacier (1998-2006), Ammassalik Island, SE Greenland

摘要

SnowModel, a physically-based snow evolution modeling system that includes four submodels - MicroMet, EnBal, SnowPack, and SnowTranSD - was used to simulate eight full-year (1998/99 through 2005/06) evolutions of snow accumulation, blowing snow sublimation, evaporation, snow and ice surface melt, runoff, and mass changes on the entire Mittivakkat Glacier (31 km~2) in southeast Greenland. Meteorological observations from two meteorological stations inside the glacier catchment were used as model input, and glaciological mass balance observations were used for model calibration (1998/99 through 2001/02) and validation (2002/03 through 2005/06) of winter snow simulations. As confirmed by observations, the spatially modeled end-of-winter snow water equivalent (SWE) accumulation increased with elevation up to 700-800 m a.s.l. in response to elevation, topography, and dominating wind direction, and maximum snow deposition occurred on the lee side of the ridge east and south of the glacier. Simulated end-of-summer cumulative runoff decreased with elevation and minimum runoff occurred on the shadowed side of the ridge east and south of the glacier. The modeled test period averaged annual mass balance was 65 mm w.eq. y~(-1) or ~8% more than the observed. For the simulation period, the glacier net mass balance varies from -199 to -1,834 mm w.eq. y~(-1), averaging -900(±470) mm w.eq. y~(-1). The glacier averaged annual modeled precipitation ranged from 1,299 to 1,613 mm w.eq. y~(-1), evaporation and sublimation from 206 to 289 mm w.eq. y~(-1), and runoff from 1,531 to 2,869 mm w.eq. y~(-1). The model simulated Mittivakkat Glacier net loss of 900 mm w.eq. y~(-1) contributes approximately 42% to the average simulated runoff of 2,140 mm w.eq. y'', indicating a mean specific runoff of 67.8 ls~(-1) km~(-2).