摘要
在气候变化背景下,许多地区蒸发皿蒸发量出现持续减少现象。淮河流域是中国南北方气候分界线,研究蒸发问题对认识淮河流域水分循环和水资源状况有重要作用。利用淮河流域实测蒸发皿蒸发量、气温、降水等7种气象要素、英国CRU月平均云量资料和NCEP/NCAR的再分析资料,分析了淮河流域近50年来蒸发皿蒸发量的变化及其原因。结果表明,淮河流域蒸发皿蒸发量存在显著的下降趋势。在一年的四季中,春夏季节蒸发量最大,下降趋势最强;淮河流域北部和西部蒸发量最大,下降趋势最强。究其原因,蒸发皿蒸发量下降与下垫面风速和日照时数减少、相对湿度和降水量增多有关;大气对流层相对湿度和比湿的增加致使地面相对湿度增大,天空云量和降水量增多,从而减弱了太阳辐射的强度,缩短了日照时间,结果使蒸发皿蒸发量下降。
Long-term observational records from the Huaihe River basin show that the evaporation rate from open pans of water has been steadily decreasing over the past 50 years. Traditionally, the Huaihe River valley is seen as the transition zone dividing the arid north from the tropical south in China. Due to its geographic location, studying of pan evaporation changes in the basin would be important to understanding the basin's water cycle and water resources conditions, especially in a changing climate. In this study, the pan evaporation change in the past 50 years is investigated using the observed pan evaporation, temperature, surface wind speed, sunshine duration, relative humidity, air pressure and rainfall from the China Meteorological Information Centre, as well as the monthly mean cloud amount da- ta of UK Climatic Research Unit (CRU) and the NCEP/NCAR renalysis data. The result confirms the pan evaporation in the basin has undergone a significant downward trend change over the past 50 years. The most pan evaporation occurs in springs and summers, and thus showing a strongest downward trend. Regionally, the greatest pan evaporation and the related downward trend change are found to be in the basin east and south. The study on the cause of decreased pan evaporation reveals that the downward trend change might be the result of the decreasing in surface wind speeds and sunshine duration, as well as the increasing in relative humidity and precipitation. The increase of both relative and specific humidity in the troposphere can result in an increase of surface relative humidity, cloud amount and precipitation, and thus weakening the intensity of solar radiation and shortening the sunshine duration. Such a process will eventually cause the reduction in pan evaporation.
出处
《水科学进展》
EI
CAS
CSCD
北大核心
2011年第1期15-22,共8页
Advances in Water Science
基金
国家自然科学基金资助项目(40771039
40830639
50879017)~~
关键词
蒸发皿蒸发量
线性趋势
气象要素
大气湿度
淮河流域
pan evaporation
linear time trend
meteorological elements
atmospheric humidity
Huaihe River basin