塔克拉玛干沙漠周边地区潜在蒸散时空演变特征及其主要影响因素

潜在蒸散是区域干湿状况评价、作物需水量估算和水资源合理规划的关键因子。基于FAO推荐的Penman-Monteith公式和16个台站1961-2009年逐日气象观测资料,估算塔克拉玛干沙漠周边地区的潜在蒸散量ET0,在对ET0的时空演变特征进行分析的基础上,探讨了影响该地区ET0变化的主要因素。结果表明,塔克拉玛干沙漠周边地区独特的自然地理条件导致多年平均潜在蒸散的分布和变化具有明显的空间差异。49 a来塔克拉玛干沙漠周边地区年和四季ET0变化整体上均为下降趋势,时间演变过程中在20世纪90年代初期均由下降趋势转为缓慢上升趋势。空间上,ET0变化在北部地区多为显著下降趋势,而南部地区多不显著;春、夏、秋3季ET0变化趋势的空间分布与年情况比较一致,但冬季ET0呈上升趋势的站点明显增多。影响塔克拉玛干沙漠周边地区多数站点ET0变化的主导因子是风速;第二影响因子春季和夏季主要是日照时数,而影响秋季和冬季ET0变化的主要是平均气温。

Spatio-temporal Variations of Potential Evapotranspiration around Taklimakan Desert and the Main Influencing Factors

Potential evapotranspiration (ET0) is a key factor for analyzing regional moisture condition, estimating crop water requirement and managing water resources. In the study, based on the daily meteorological data during 1961-2009 from 16 meteorological stations around the Taklimakan Desert, we computed ET0 with the Penman-Monteith equation recommended by FAO and analyzed its spatio-temporal variations and the influencing factors through the partial correlation analysis. Results showed that there are obviously regional differences in the average yearly ET0 variation and the main determining factor was the diverse topography and climate around the Taklimakan Desert. The annual and seasonal ET0 variations showed a general declining trend in 1961-2009, appearing a secondary increasing trend from the lowest value point since 1990s. In spatial pattern, ET0 decreased more significantly in the north part than in the south part around the Taklimakan Desert; the spatial distributions of seasonal ET0 in spring, summer and autumn had roughly similar pattern compared with that of annual ET0, while the spatial distribution in winter showed more increasing trends at these stations. The absolute values of partial correlation coefficients between ET0 and the climate variables indicated that wind speed played the most important role in the change of ET0 around the Taklimakan Desert; the secondly significant factor was sunshine duration in spring and summer, and it was air temperature in autumn and winter.