Application of a Degree-Day Model for Determination of Mass Balance of Urumqi Glacier No. 1, Eastern Tianshan, China

In order to verify the feasibility and stability of a degree-day model on simulating the long time series of glacier mass balance, we apply a degree-day model to simulate the mass balance of Urumqi Glacier No. 1 for the period 1987/1988–2007/2008 based on temperature and precipitation data from a nearby climate station. The model is calibrated by simulating point measurements of mass balance, mass balance profiles, and mean specific mass balance during 1987/1988–1996/1997. The optimized parameters are obtained by using a least square method to make the model fit the measured mass balance through the model calibration. The model validation (1997/1998–2007/2008) indicates that the modeled results are in good agreement with the observations. The static mass balance sensitivity of Urumqi Glacier No. 1 is analyzed by computing the mass balance of the glacier for a temperature increase of 1 ℃, with and without a 5% precipitation increase, and the values for the east branch are −0.80 and −0.87 m w.e. a⁻¹·℃⁻¹, respectively, and for the west branch, the values are −0.68 and −0.74 m w.e. a⁻¹·℃⁻¹, respectively. Moreover, the analysis of the parameter stability indicates that the parameters in the model determined from the current climate condition can be applied in the prediction of the future mass balance changes for the glacier and provide a reference for extending the model to other small glaciers in western China.