青藏高原腹地1985年雪灾成因分析

THE ANALYSIS OF CAUSING THE SNOW DISASTER ON 1985 OVER CENTRAL QINGHAI-XIZANG PLATEAU

分析了 1 985年 1 0月青藏高原腹地一次特大雪灾的地面气象要素场及卫星辐射场特征 ,并对造成重雪灾的原因进行了初步探讨。结果表明 :此次雪灾的范围与过程 ,降水量≥8mm与积雪深度≥ 5cm的范围基本一致 ,雪盖的后延冷却效应较强 ,持续时间近 5个月 ;卫星辐射资料的分析计算结果表明 ,地气系统净辐射收支中行星反照率起主导作用。 1 1月积雪中心区域各因子均达极值—行星反照率距平高达 1 6 % ,OLR距平值减小 - 1 4 .6W/m2 ,地气系统净辐射距平值达 - 2 5 .4W/m2 。初步发现 :如果下半年西天山—帕米尔间 (73°～ 75°E)有 7级以上地震或青藏腹地 (32°～ 35°N ,85°～ 1 0 0°E)有 5 .9级以上地震发生 ,就会引发当年冬季或 /和次年春季的重雪灾。

The surface variables and the characteristics of satellite radiation budget field about a serious snow disaster were analyzed in October 1985 over Central Qinghai Xizang Plateau, and the causing snow disaster were preliminary researched. The results show that the range of precipitation(≥8 mm) and snow depth (≥5 cm) is almost equal. The lag-cooling effect of the snow cover is stronger, continuing time is about five months. The calculated results with satellite radiation data show that the albedo is important in the radiation budget field of earth atmospheric system. In November, every variable in the central area of snow cover is getting to the largest: or so, albedo anomaly is high as 16%, OLR is low as 185.6 W/m 2 and the net radiation is -25.4 W/m 2. The preliminary result were discovered, which there will be serious snow disaster in the winter or/and the next spring over Plateau, if the earth quake (Ms≥7) is appeared between the western Tianshan and Pamier (73°～75°E) or in the Central Plateau(32°～35°N, 85°～100°E) when Ms≥5.9 in last half a year.