The Surface Energy Budget in the Accumulation Zone of the Laohugou Glacier No. 12 in the Western Qilian Mountains, China, in Summer 2009

The energy balance of a glacial surface can describe physical melting processes. To expand the understanding of how glaciers in arid regions respond to climate change, the energy budget in the accumulation zone of the Laohugou Glacier No. 12 was measured. Input variables were meteorological data (1 June-30 September 2009) from an automatic weather station located on the accumulation zone at 5040 m above sea level (a.s.l.). Radiative fluxes directly measured, and turbulent fluxes calculated using the bulk aerodynamic approach, were involved in the surface energy budget. Net radiation flux was the primary source of the surface energy balance (72%) and was chiefly responsible for glacial melting, followed by sensible heat flux (28%). Melting energy was the main output of surface energy (48%), and was almost as large as the sum of latent heat flux (32%) and subsurface heat flux (20%). The modeled mass balance was -75 mm water equivalent, which compared well with sonic ranging sensor readings. Albedo varied between 0.52 and 0.88 on the glacial surface, and melting was prevented by high albedo. Under the assumption of neutral atmospheric conditions, turbulent fluxes were overestimated, especially the sensible heat flux by 54%; therefore, a stability correction was necessary.