利用MODIS数据估算晴空半干旱地表潜热通量

为研究我国半干旱区域地表潜热通量分布特征, 建立了一套不需要将地面气象观测数据作为输入而仅用卫星数据来估算晴空条件下半干旱地表潜热能量的方案。该方案设计了针对半干旱地表的净辐射通量参数化方法和土壤热通量估算模型, 利用S-SEBI模型计算蒸发比率, 根据能量平衡原理得到潜热通量。基于MODIS陆地和大气产品, 利用该方案进行潜热通量估算研究，并采用2003, 2004和2005年6?11月间退化草地和农田晴空数据进行验证。与地面站点观测数据对比结果表明该方案能有效计算地表潜热通量: 在退化草地和农田两个站点上, 该方案计算的地表潜热通量的均方根误差分别为60.4和64.6 W/m², 平均偏差分别为18.6和32.4 W/m²。

Estimation of Latent Heat Flux over Semiarid Areas for Clear Sky Days Using MODIS Data

In order to study the distribution of latent heat flux in Northern China, a scheme, eliminating the need of ground meteorology data as input and only using remotely sensed information, is proposed to estimate latent heat flux over semiarid areas for clear sky days. In this scheme, latent heat flux is calculated based on surface energy balance: net radiation is estimated using an improved parameterization; soil heat flux is calculated through a regression equation; evaporative ratio is obtained by S-SEBI model. Based on land and atmospheric data products available from moderate resolution imaging spectroradiometer (MODIS), this scheme is validated by clear sky datasets at the degraded grassland site and the farmland site during June to November in 2003, 2004 and 2005. The results indicate that the proposed scheme can effectively calculate the latent heat flux. The root mean square error (RMSE) for the estimated latent heat flux in grassland and farmland are 60.4 and 64.6 W/m² respectively, and the mean error (ME) are 18.6 and 32.4 W/m² respectively.