摘要
本文分析了2003～2005年半干旱区退化草地和农田下垫面近地层湍流通量日、季、年的变化特征,探讨了不同年份的气候背景和下垫面土地覆被对地气交换过程的影响。结果表明:半干旱区退化草地和农田近地层湍流通量具有明显的日变化、季变化周期;地气间通量交换年际间的差异主要受当年的气候背景影响,尤其是降水的影响;同时还受到下垫面覆被的影响。潜热通量和感热通量的能量分配比率呈反位相变化,且农田和退化草地的变化趋势相似,在夏季潜热通量所占比例均超过感热通量;两种下垫面的波恩比月均值变化趋势十分相似,量级接近,夏季低,春、秋季高;夏季退化草地和农田下垫面波恩比均小于或等于1。
The seasonal and diurnal variations of the surface turbulent fluxes over the degraded grassland and the cropland are investigated, based on the turbulent flux data measured with Eddy Covariance （EC） method and radia- tion and meteorological data collected from 2003 to 2005 in the semi-arid area. The influence of different meteoro- logical backgrounds on the turbulent fluxes between land and atmosphere over different land surfaces is also dis- cussed. It is shown that there are clear seasonal and diurnal variations for the components of surface energy balance over the degraded grassland and the cropland in the semi-arid area. The interannual variability of the components of surface energy balance is mainly influenced by meteorological backgrounds in the same year, especially by precipita- tion. The ratios of net radiation to latent heat flux and to sensible heat flux show an opposite phase change over both degraded grassland and cropland, and the ratio for the latent heat flux is higher than that for the sensible heat flux in summer. The trends of mean monthly Bowen ratios over two types of underlying surfaces are almost the same, and the magnitudes of the Bowen ratios are near. The Bowen ratio in summer is not larger than 1.0 over both degraded grassland and cropland.
出处
《大气科学》
CSCD
北大核心
2009年第4期719-725,共7页
Chinese Journal of Atmospheric Sciences
基金
国家重点基础研究发展规划项目2006CB400501
国家自然科学基金资助项目40775050
关键词
近地层湍流通量交换
下垫面
半干旱区
surface turbulent flux, sensible heat flux, semi-arid area
