珠穆朗玛峰北坡地区气温和湿度变化特征

Characteristics of the air temperature and humidity on the north slope of Mt Qomolangma.

中文关键词:  气温，湿度，特征，珠穆朗玛峰，冰川

英文关键词:Air temperature, Humidity, Characteristics, Mt Qomolangma, Glacier

中文摘要:

      珠穆朗玛峰地区由于其独特的自然地理条件、举世无双的高度、脆弱而敏感的环境使其成为气候变化和环境变迁的敏感区。根据2007年5月至2008年8月在珠穆朗玛峰北坡地区7个不同海拔高度观测的逐时气温和空气湿度资料分析了该地区气温和湿度的时空变化特征。结果表明，在海拔5207、5792和5955 m 高度处的年平均气温分别为0.2、-4.4和-5.4℃，最高气温分别为14.6、9.1和18.6℃, 最低气温分别为-24.2、-28.8和-29.3℃；除在冰川表面以外，空气相对湿度随海拔高度的升高没有明显变化。气温和相对湿度的年变化幅度随海拔高度的升高而减小。由于冰面近地层逆温层顶部暖空气与冷空气的混合作用造成其最高气温出现时间晚于其他下垫面。年平均温度递减率为（0.72±0.01）℃/100 m，并且呈现出明显的季节变化特征。同时结合定日气象站1959—2007年的气温和降水资料，探讨了对珠穆朗玛峰北坡绒布冰川变化的影响。

英文摘要:

      Weather and climatic conditions over the Himalaya regions are of great interest to the scientific community at large. The objective of this study is to present spatial and temporal variations of air temperatures and the relative humidity on the north slope of Mt Qomolangma. Both the hourly air temperature and relative humidity were measured at the seven automatic weather stations (AWS) from 5207 to 7028 m a.s.l. from May 2007 through September 2008. The preliminary results show that the elevational variation of the mean annual air temperature is non-linear, which decreases from 0.2℃ at elevations of 5207 m to -4.4℃ at 5792 m, and -5.4℃ at 5955 m. The maxima are 14.6℃, 9.1℃, and 18.6℃, and the minima are -24.2℃, -28.8℃, and -29.3℃ at the three elevations, respectively. The relative humidity does not change significantly with increasing elevation except over the glacier ice, but the mixing ratio decreases due to the decrease in air temperature. The mean diurnal ranges of air temperature and relative humidity decrease with increasing elevation. The daily maximum air temperature occurs significantly later at the high elevation site than that at the low elevation site because the air temperature at the high elevation site is affected to a large extent by the downward mixing of warm air near the ablation zone of the glacier during daytime. The air moisture content reflects the pronounced alternation of the wet and dry seasons, and the highest water vapor content is associated with the southwesterly Indian monsoon. The mean annual lapse rate of surface air temperature is 0.72±0.01℃/100 m, and also shows a pronounced seasonal signature. Moreover, the reason of the Rongbuk Glacier retreat is also discussed based on the long-term (1959-2007) air temperature and precipitation data from Dingri meteorological station.