000032424 001__ 32424
000032424 041__ $$aEnglish
000032424 100__ $$aRagettli, S.
000032424 245__ $$aHeterogeneous Glacier Thinning Patterns over the Last 40 Years in Langtang Himal, Nepal
000032424 260__ $$c2016
000032424 300__ $$a2075-2097
000032424 520__ $$aThis study presents volume and mass changes of seven (five partially debris-covered, two debris-free) glaciers in the upper Langtang catchment in Nepal. We use a digital elevation model (DEM) from 1974 stereo Hexagon satellite data and seven DEMs derived from 2006–2015 stereo or tri-stereo satellite imagery (e.g., SPOT6/7). The availability of multiple independent DEM differences allows the identification of a robust signal and narrowing down of the uncertainty about recent volume changes. The volume changes calculated over several multiyear periods between 2006 and 2015 consistently indicate that glacier thinning has accelerated with respect to the period 1974–2006. We calculate an ensemble-mean elevation change rate of –0.45 ± 0.18 m a−1 for 2006–2015, while for the period 1974–2006 we compute a rate of −0.24 ± 0.08 m a−1. However, the behavior of glaciers in the study area is heterogeneous, and the presence or absence of debris does not seem to be a good predictor for mass balance trends. Debris-covered tongues have nonlinear thinning profiles, and we show that recent accelerations in thinning correlate with the presence of supraglacial cliffs and lakes. At stagnating glacier areas near the glacier front, however, thinning rates decreased with time or remained constant. The April 2015 Nepal earthquake triggered large avalanches in the study catchment. Analysis of two post-earthquake DEMs revealed that the avalanche deposit volumes remaining 6 months after the earthquake are negligible in comparison to 2006–2015 elevation changes. However, the deposits compensate about 40 % the mass loss of debris-covered tongues of 1 average year.
000032424 700__ $$aBolch, T.
000032424 700__ $$aPellicciotti, F.
000032424 773__ $$pThe Cryosphere
000032424 773__ $$v10 (5)
000032424 773__ $$a10.5194/tc-10-2075-2016
000032424 8564_ $$uhttp://www.the-cryosphere.net/10/2075/2016/$$yExternal link (open access)
000032424 980__ $$aARTICLE