天山冰川消融参数化能量平衡模型

A PARAMETERIZED ENERGY BALANCE MODEL OF GLACIER MELTING ON THE TIANSHAN MOUNTAIN

本文运用在天山乌鲁木齐河源的冰川能量平衡观测和常规气象站观测要素，建立了冰川消融参数化能量平衡模型。以日照、日平均气温、低云量、水汽压和风速为模型基本输入因子，模拟计算和讨论了消融期冰川表面辐射平衡和能量平衡。

Based on the measurement of energy balance on a glacier at the source area of the Urumqi River on the Tianshan Mountain druing the ablation seasons from June to August of 1986 and 1987, a parameterized energy balance model of glacier melting is developed with standard meteorological elements. Taking daily sunshine duration hours. daily mean air temperature. low cloud cover, wind velocity and vapour pressure at a standard meteorological station as the inputs to the model, the daily global radiation albedo, long-wave incoming and outgoing radiation, sensible and latent heat fluxes are simulated on the glacier, then the daily rediation balance. energy balance and melting heat of the glacier are obtained.In the parameterized heat flux expressions of the model, the extraatmospheric solar radiation is calculated by taking the slope influence into account. The ratio of daily global radiation to extraatmospheric solar radiation has a significant linear correlation to the ratio of daily sunshine duration hours to potential sunshine duration hours. The albedo of snow and ice decreases with the increase of air temperature, but the ratio of decrease of snow albedo is much larger than that of ice. The snow albedo is correlated to the power function of air temperature. while the ice albedo is linearly correlated to air temperature. Atmospheric emissivity is calculated with low cloud cover, while the surface emissivity of melting ice and snow is considered constant. According to the flux-gradient relationship, sensible and latent heat fluxes are approximated by the one level measurement of wind velocity, air temperature and vapour pressure.The simulated results indicate that during the summer months from June to August, most of net radiation is received by the glacier surface because of the relatively small albedo. In addition to the more sensible heat flux, the melting heat is then mostly distributed in the two months. Therefore, the intense melting period of glaciers on the Tianshan mountain is during July and August. At the height of 3910m a. s. 1. on Glacier No. 1 at the source of the Urumqi River, during June to August from 1986 to 1990, the incoming radiation is 224W/m￣2 which is global radiaton. While the outgoing radiaton consists mainly of reflected radiation (54%) and the surface effective radiation.(13%), and the remaining 33% belongs to net radiation. The incoming part in the energy balance consists mainly of net radiation, and sensible heat flux 13W/m￣2 which accounts for 15%. The incoming energy is consumed mostly by melting heat, accounting for 94%, and by evaporation latent heat.