近30年西藏地区雷暴日数的气候分布特征

利用西藏地区1980~2009年逐月雷暴日数观测数据,分析了近30a来西藏地区雷暴的时空分布特征以及影响雷暴天气的气象因子。结果表明:(1)雷暴天气主要发生在西藏那曲地区,并由该区域向西南、东南部逐渐递减,且雷暴天气发生的中心位置随着季节有所差别。夏季雷暴日数最多,其次是秋季和春季,冬季雷暴日数最少。(2)近30年来年或各季节的雷暴日数基本呈现减少的趋势,尤其以2000年之后最为显著。雷暴日数以2003年为突变点,开始急剧减少。(3)雷暴日数和平均气温呈负相关,与风速、相对湿度、降水量呈正相关,气温升高可能是导致雷暴日数减少的主要气候影响因子。 

Climatic Distribution of Thundering Days in Tibet during 1980~2009

With the monthly observation of thundering days in Tibet Autonomous Region (TAR) during 1980~2009, this paper investigated the temporal and the spatial distribution of thundering days and its influencing factors in last 30 years.Results show that thunderstorm generally occurs in the Nagqu region of TAR, and it decreases from the above region to the southwest and southeast parts of Tibet, and the thundering center is different during the different seasons. Summer has the maximum thundering days, followed by that in autumn and spring while winter has the least thundering days. Generally annual and seasonal thundering days have the decreasing variation trend, especially after 2000. Year 2003 is the brake point and the number of thundering day decreases quite obviously since then. The number of thundering days is negatively related with air temperature while it positively related to wind speed, relative humidity and precipitation. The increasing temperature is might be the major climatic factor which results in the decreasing thundering days.