摘要
风灾是日喀则地区主要的灾害性天气之一,尤其是西部和南部边缘地区,大风天气一年四季均有发生,是西藏区域大风天气频繁多发地带.大风不仅对房屋建筑物、电力通讯设施等方面构成严重威胁,而且还给草原植被、农牧业生产带来严重的影响.文章选取1981～2010年间日喀则地区7个观测站大风气象资料,分析日喀则地区西部和南部边缘大风天气的时空分布规律,并探讨大风天气的形成原因.结果表明:大风主要出现在冬春两个季节,秋季次之,夏季最少.近30年中,西部地区在上世纪80年代大风天气最多,00年代次之,90年代最少,30年中两个高值年和四个低值年,峰值出现在1984年,年大风日数在80年代波动较大,之后基本稳定在平均值附近,整体变化趋势不明显；南部边缘地区则是在上世纪90年代大风天气最多,00年代次之,80年代最少,30年中有4个高值年和3个低值年,年大风日数整体呈逐渐增多的趋势,2004年达到最高值.结合日喀则地区气象特征得出如下结论:该地区大风天气主要由高空急流、高空冷热平流活动、低空升温降压以及地形地理环境等因素造成.
Shigatse is the prone zone of frequently happening regional windy weather in Tibet and the windstorm disaster is one of the major disastrous weathers in Shigatse.Especially,in the western and southern border areas,the windy weather have occurred throughout the year.Gale brings about serious damage not only for buildings,electrical communication facilities,but also to grassland vegetation and agricultural production.In the present paper,the temporal and spatial distribution pattern of windy weather in the western and southern remote areas in Shigatse based on 30 years(from 1981 to 2010) gale weather data from seven stations and explored the reasons for the formation of windy weather in the area.The results showed that the gale weather has being mainly occurred in the winter and autumn and very seldom in summer.The maximum of windy weather in the western region occurred in 1980s followed by 00's and the least in 90's during the 30 years.There were two years of high value and four years of low value in 30 years.The annual number of gale days fluctuated in the 80s and the peak value occurred in the year of 1984 and then it was basically stable around the average.There was no significant change in the overall trend in the West of the region.The maximum of windy weather in southern region occurred in 1990s,followed by 00s,and the least in 1980s during the 30 years.There were four years of high value and three years of low value in 30 years and the overall annual number of gale days was gradually growing and the highest value reached in 2004.The gale weather in Shigatse have been caused by impact of high-altitude jet stream,high-altitude cold advection activity,low temperature and antihypertensive effect,and the geographical and environmental conditions in conjunction with local meteorological characteristics.
关键词
西藏日喀则
天气变化特征
大风天气
Shigatse prefecture in Tibet
characteristics of weather change
windy weather
