近46年青藏高原干湿气候区动态变化研究

利用青藏高原62个气象站1961～2006年逐日气象资料, 用世界粮农组织 (FAO) 在1998年推荐的、并唯一承认的Penman-Menteith模式计算潜在蒸散量; 比较了降水量、积温降水比、气温降水比、蒸散降水比和降水蒸散比5种湿润度指标在青藏高原的适用性, 用常规统计方法和墨西哥帽小波变换分析青藏高原各气候区干湿状况及其界线的动态变化。结果表明: 5种指标中, 用降水蒸散比得到的青藏高原湿润、半湿润、半干旱、干旱和极端干旱气候区的分区结果比较合理; 近46年来青藏高原大部分地区湿润度和每个气候区的平均湿润度均呈增加趋势, 半干旱和半湿润气候区的界线呈向西北推进趋势, 气候在向暖湿方向发展。

A Study of Dynamic Change of Dry and Wet Climate Regions in the Tibetan Plateau over the Last 46 Years

Using daily meteorological data at 62 stations from 1961 to 2006 in the Tibetan Plateau,the potential evapotranspiration is estimated with the Penman-Monteith(recommended by FAO in 1998) model,and the five moisture indexes,which are precipitation,the ratio of accumulated temperature to precipitation,the ratio of air temperature to precipitation,the ratio of evapotranspiration to precipitation and the ratio of precipitation to evapotranspiration,are compared.The dry and wet conditions in each climate region and dynamic change of the boundaries between different climate regions in the Tibetan Plateau over the last 46 years are analyzed based on general statistic methods and Mexican Hat wavelet.The mainly results show that the distribution of humid,semi-humid,semi-arid,arid and extreme arid climate regions in the Tibetan Plateau given by using the ratio of precipitation to evapotranspiration is the most reasonable in the distributions given by using the five indexes.Over the last 46 years,the moisture index values in the most places of the Tibetan Plateau and the average moisture index values in each climate region increase and the boundary between the humid region and the semi-humid region moves northwestward.The climate in the Tibetan Plateau changes toward warm-wet climate.