A Test Study of an Energy and Mass Balance Model Application to a Site on Urumqi Glacier No. 1, Chinese Tian Shan

Min Yang,Xiaoying Yue,Shuang Jin,Huilin Li,Zhongqin Li,Christoph Schneider,Hongliang Li,Puyu Wang,Alexandra Hamm,Chunhai Xu

doi:10.3390/w12102865

Abstract

In this study, energy and mass balance is quantified using an energy balance model to represent the glacier melt of Urumqi Glacier No. 1, Chinese Tian Shan. Based on data from an Automatic Weather Station (4025 m a.s.l) and the mass balance field survey data nearby on the East Branch of the glacier, the “COupled Snowpack and Ice surface energy and Mass balance model” (COSIMA) was used to derive energy and mass balance simulations during the ablation season of 2018. Results show that the modeled cumulative mass balance (−0.67 ± 0.03 m w.e.) agrees well with the in-situ measurements (−0.64 ± 0.16 m w.e.) (r2 = 0.96) with the relative difference within 5% during the study period. The correlation coefficient between modeled and observed surface temperatures is 0.88 for daily means. The main source of melt energy at the glacier surface is net shortwave radiation (84%) and sensible heat flux (16%). The energy expenditures are from net longwave radiation (55%), heat flux for snow/ice melting (32%), latent heat flux of sublimation and evaporation (7%), and subsurface heat flux (6%). The sensitivity testing of mass balance shows that mass balance is more sensitive to temperature increase and precipitation decrease than temperature decrease and precipitation increase.

Highlights

There are 7934 glaciers comprising an area of 7179.77 km2 in the Chinese Tian Shan, accounting for 16% and 14% in number and area of glaciers in China, respectively [1]
Despite the fact that one single ablation season is only a short study period, we are convinced that the findings provide novel insight on the relevant physical processes governing the surface mass balance
The coupled snow and ice surface energy and mass balance model COSIMA was used to simulate the glacier surface energy and mass balance at site AWS1 on Urumqi Glacier No 1 (UG1) during the summer season 2018 using air temperature, air pressure, relative humidity, precipitation, cloud cover, wind speed and downward shortwave as forcing variables

Summary

Introduction

There are 7934 glaciers comprising an area of 7179.77 km in the Chinese Tian Shan, accounting for 16% and 14% in number and area of glaciers in China, respectively [1]. Earlier studies in the Chinese Tian Shan deploy various empirical models, such as linear regression models and Degree-Day models, which can describe the relationship between mass balance and meteorological components [14,15,16,17]. They show shortcomings for glaciers with accumulation mainly in summer, and for large areas with complex terrain where radiative processes and non-linear feedback between air temperature, precipitation and albedo play a significant role. Physical models have been developed to investigate energy and mass balance of glaciers all around the world [18,19,20,21,22,23,24,25,26]. [22] presented the steady-state physically based “COupled Snowpack and

Results

Discussion

Conclusion