Abstract
The glacier ELA is one of the important parameters reflecting climate change. Based on observations of the equilibrium line altitude (ELA) of Urumqi Glacier No.1 in the Tianshan Mountains, we established a statistical model between ELA and its major influencing factors, warm season air temperature (air temperature averages for May, June, July and August) and annual precipitation. Result showed that, warm season air temperature was the leading climatic factor influencing ELA variations. The glacier ELA ascends (descends) 61.7 m when warm season air temperature increases (decreases) by 1°C, and ascends (descends) 13.1 m when cold season precipitation decreases (increases) by 10%. In the period 1959–2008, the glacier ELA showed a general increasing trend, ascending108 m and reaching its highest altitude in 2008 at 4168 m a.s.l., close to the glacier summit. If future climate is similar to that in the past 50 years, the ELA of Urumqi Glacier No.1 will still ascend with a speed of 2.16 m/a. However, If future climate is similar to that in the period 2000–2008, the ELA will still ascend with a speed of 6.5 m/a before it is stable. As a result of ELA variation, the accumulation area ratio (AAR) of the glacier showed a decreasing trend during the past 50 years.
Highlights
The glacier equilibrium line altitude (ELA) is one of the important parameters reflecting climate change
ELA is the boundary of accumulation zone and ablation zone on the glacier, which is closely correlated with climatic factors and the glacier surface geomorphology
As precipitation increase could cause the decline of ELA, the ascending trend of the glacier ELA was caused by air temperature rising
Summary
Statistical models correlating ELA and air temperature and precipitation [28,29] using data from nearby meteorological stations are effective for reconstructing past correlation between ELA and climate factors and investigating ELA sensitivity to climate change [3]. We will use these models here to investigate the state of the ELA of Urumqi Glacier No.. Meteorological datasets, air temperature and precipitation, with a time period of 1959–2008, are obtained from Daxigou Meteorological Station, which is located at 3600 m a.s.l. in the glacial region, only 4 km away from Urumqi Glacier No.. The data is well coincident with that of three hydro- meteorological stations at the Urumqi River source, which could reflect the climate change of the Urumqi River source very well [29–32]
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