Observational Study on Characteristics of Meteorological Elements in Mountain Qomolangma Region

The Qomolangma Olympic torch relay meteorological guarantee team of the Central Meteorological Office has obtained precious first hand observational data, including in situ data of automatic station and 79 sounding data in the Qomolangma's base camp from 12 April to 8 May in 2007. Observational characteristics of meteorological elements in Mountain Qomolangma are revealed in terms of these data and the results are as follows. Due to the effect of glacier wind in Rongbuk Valley, the prevalent wind is a downslope wind (south wind) in the Qomolangma's base camp. The diurnal changes of wind speed and temperature show single peak type distribution, with the minimum appearing at 08:00 and the maximum at 15:00. Relative humidity peaks appear at 07:00 and 23:00, the minimum at noon. There is a constant south wind below 6200 meter elevation, and the strongest downslope wind happens during 22:00-00:00. West wind is dominant for 7200-9000 meters, and its speed increases significantly with the elevation. At the height of 5200-8000 meters, the temperature always reaches minimum at 08:00 and maximum at 16:00, but the temperature diurnal change shows more fluctuations above 8200 meters. The high value centers of relative humidity can maintain at an elevation of 6700-9700 meters, and the highest value areas locate mainly in 6500-8800 meters. From late April to early May, the high level frontal zone in the Everest area is at the elevation of 12000-15000 meters, and troposphere top height is around 18200 meters. Rising temperature, pressure and decreasing wind speed offer ideal time window for climbing the mountain.