河西走廊荒漠-绿洲蒸散对夏季高温天气响应的初步研究

高温事件对水文过程的影响以及生态系统对高温事件的响应成为全球变化关注的重要问题之一。以2010年7月20-30日河西走廊临泽地区出现的持续高温天气为案例，初步探讨了高温期间该地区水面蒸发、参考作物蒸散量和植物蒸腾的变化规律，分析了蒸散产生变化的主要原因，并分析了气温与蒸散之间的关系。结果表明：高温期间水面蒸发量比多年同期平均值增加42%，参考作物蒸散比多年同期平均值增加19%。平均气温和最高气温增加是其变化的主要原因。回归分析表明，在2005-2009年7月20-30日平均气温距平值每升高1 ℃时，水面蒸发距平值增加0.58 mm；最高气温距平值每升高1 ℃时，水面蒸发距平值增加0.39 mm。而对于参考作物蒸散而言，在2005-2009年7月20-30日平均气温距平值每升高1 ℃，参考作物蒸散量距平值增加0.11 mm；最高气温距平值每升高1 ℃，参考作物蒸散量距平值增加0.06 mm。荒漠灌木沙拐枣蒸腾速率在2010年高温期比2008-2009年同期平均值增加373%，在2008-2009年7月20-30日，相对湿度距平值每增加1%，蒸腾速率减少0.39 g?cm-²?d-¹。

Study on Response of Evapotranspiration to Scorching Weather in a Desert-Oasis Region in the Hexi Corridor

In this paper, a high-temperature event occurred in Linze County, Gansu Province in 2010 was regarded as a case to estimate the response of evapotranspiration to scorching weather. The water-surface evaporation, transpiration rate of Calligonum mongolicunl and referred crop evapotranspiration during the period with extremely high temperature in 2010 were compared with the average values during the same period of 2005-2009. The results showed that, compared with the long term values, the water surface evaporation and the referred crop evapotranspiration under the scorching weather in 2010 were increased by 42% and 19% respectively, and the increases of both average and maximum air temperatures were the main causes resulting in such changes. Regression analysis results showed that, during the study period, the water-surface evaporation was increased by 0.58 mm whenever the average air temperature anomaly was increased by 1 ℃; the water surface evaporation was increased by 0.39 mm whenever the average maximum air temperature anomaly was increased by 1 ℃. The referred crop evapotranspiration was increased by 0.11 mm whenever the average air temperature was increased by 1 ℃; the referred crop evapotranspiration anomaly was increased by 0.06 mm whenever the maximum air temperature anomaly was increased by 1 ℃. The transpiration rate of C. mongolicunl under high temperature in 2010 was increased by 373% compared with the average during 2008-2009, and the transpiration rate of C. mongolicunl was decreased by 0.39 g?cm-²?d-¹ whenever the relative humidity was increased by 1%.