Comparative study on observed mass balance between East and West Branch of Urumqi Glacier No. 1, Eastern Tianshan, China

摘要

This paper is based on observed mass balance between East and West Branch of Urumqi Glacier No. 1, meteorological data during 1988-2010, comparative studies the mass balance variations, and analyses the mass balance sensitivity to climate change. Results show that average mass balance of East and West Branch was 532 mm/a and 435 mm/a, cumulative mass balance was 12,227 mm (ice thinned by 13.6 m) and 10,001 mm (ice thinned by 11.1 m), respectively, and mass loss of East Branch was 97 mm/a larger than West Branch. The East and West Branch ELA (equilibrium line altitude) ascended about 176 m and 154 m, analysis shows the steady-state ELA0 was 3,942 m a.s.l. and 4,011 m a.s.l., and when East and West Branch mass balance decreased by 100 mm, ELA ascended 20 m and 23 m, respectively. The AAR (accumulation area ratio) of East and West Branch presented an obviously decreasing trend of 34.5% and 23%, equilibrium-state AAR0 was 65% and 66%, when East and West Branch mass balance increased by 100 mm, AAR ascended 4.6% and 4.2%, respectively. Glacier mass balance was sensitive to change of net ablation, net ablation of East and West Branch increased 10×104 m3 , and mass balance decreased 110 mm and 214 mm, respectively. By analyzing mass balance sensitivity to climate change, results suggest that East and West Branch mass balance decreased (increased) 463 mm and 388 mm when ablation period temperature increased (decreased) by 1°C, East and West Branch mass balance increased (decreased) 140 mm and 158 mm when annual precipitation increased (decreased) by 100 mm, and sensitivity of East Branch mass balance to climate change was more intense than that of West Branch.