Glacier stagnant in central Karakorum derived from DEOS Mass Transport Model GRACE data and one monthly degree-day model

Abstract

Glacier change in central Karakorum is known as ‘anomony’ in the late 1990s, where many glaciers expanded and numbers of glacier surged while most of glaciers in the Greater Himalaya rapidly retreated. However, the understanding of glacier change in this region is still poor. Glacier changes for the Hunza river basin (HRB) in central Karakorum during 2003 to 2008 were investigated from different data sources. The mass variation in HRB were estimated from the DEOS Mass Transport Model (DMT-1) GRACE data and the Variable Infiltration Capacity (VIC) model, and compared with the simulated glacier mass balance by one monthly degree-day model. The surface elevation difference of glaciers between ASTER DEM and SRTM were calculated. The mass variations from GRACE data suggest that the glacier mass balance in HRB during 2003-2007 has no clear trend. The cumulative mass balance is positive during 2003-2008. The average glacier surface elevation difference between SRTM DEM and ASTER DEM is 11.8±3.2 m. The average differences of glacier surface elevation of Batura glaciers in accumulation zones is increased with 0.88m.a-1, These results indicate that there is no significant glacier retreat during 1999 to 2008. The seasonal amplitude of simulated mass variation of the monthly degree-day model agreed well with that estimated from DMT-1 GRACE data, but the simulated glacier accumulation is less than that calculated from GRACE data. The main reason probably lies in that the precipitation of glaciers and ungalciated areas were underestimated, especially in alpine areas.