反照率对冬克玛底冰川径流及物质平衡模拟影响研究

Albedo has been considered an important factor affecting the process of glacier runoff and mass balance, but still lack of quantitative studies. In this study, albedo and incoming shortwave radiation are taken into account in the glacier hydrological model FLEX^G, and tested in the Dongkemadi River Basin, in the source region of the Yangtze River. To account for spatial heterogeneity, the basin was classified into 19 elevation bands at 50 m intervals, and was divided into 3 different aspects（north facing, south facing and west/east facing）for both glacier and non-glacier regions. Observed hydrology and meteorology data from 2005 to 2009, MODIS （MOD10A1）daily albedo product and daily incoming shortwave radiation product during ablation seasons （May-September）were used to force the models, and calibrate the parameters. The hydro-meteorological data and glacier mass balance data from 2010 to 2014 were used to validate model performance. Monte Carlo sampling was used to generate 2×10⁴ sets of parameters within the prior range. Kling-Gupta efficiency（KGE）was used as an objective function to evaluate model performance in calibration. Then the best one percent of parameter sets was regarded as behavioral ones for further analysis and generate uncertainty ranges of the simulated runoff. The results showed that consideration of the albedo and incoming shortwave radiation could increase the model realism, including daily runoff, glacier mass balance, and the glacial runoff proportion. More specifically, the runoff simulation was improved from KGE=0. 49 to KGE=0. 51, the glacier mass balance simulation was improved from R²=0. 67 to R²=0. 83；and the glacier runoff proportion was increased from 63% to 66%, which is closer to the previous result obtained by isotopic hydrograph separation. This study illustrates that considering the albedo and incoming shortwave radiation can improve the performance and model realism of the degree-day factor model.