中国西北地表能量分配影响因子及特征空间法适用性北大核心CSCD

利用2009年地面实测资料,分析中国西北地区不同气候区潜热、感热及其与净辐射之比随土壤体积含水量、土壤温度及入射辐射的变化特征,并结合2000—2018年中分辨率成像光谱仪(MODIS)产品讨论特征空间法在中国西北地区的适用性。结果表明:在以玛曲站为代表的高寒湿润区,入射能量始终是潜热的主导因素,用于潜热估算的斜率φ可直接取1.26,潜热估算精度依赖于净辐射的反演结果。在以兰州大学半干旱气候与环境监测站(SACOL,榆中站)和长武站为代表的半干旱、半湿润区,当入射能量充足时,土壤水分成为潜热的主导因子,这时候使用特征空间法估算的斜率φ值与实测值相关性显著,φ的估算精度将直接影响潜热估算结果。所以,特征空间法适用于以水分为潜热主导因子的地区和时段,且要满足植被指数与地表温度呈负相关。另外需要注意的是在选择特征空间法研究区时必须保证植被指数与地表温度的散点呈规则的“三角形”。

Influencing factors of surface energy conversion in Northwest China and applicability of characteristic space method

Based on the measured ground data in 2009， the variation characteristics of latent heat （LE）， sensible heat （H_s） and the ratios of LE and Hs to net radiation （R_n） in different climatic regions with soil volume water content， soil temperature and incident radiation （R_s） are analyzed. Combined with the products of Moderate-resolution Imaging Spectroradiometer （MODIS） from 2000 to 2018， the applicability of characteristic space method in Northwest China is discussed. The results show that in the alpine humid area represented by Maqu station， the incident energy is always the dominant factor of LE. The slope ? used for LE estimation can be directly taken as 1.26. The estimated accuracy of LE depends on the retrieval result of R_n. In the semi-arid and semi-humid areas represented by SACOL station and Changwu station， when the incident energy is sufficient， the soil moisture becomes the dominant factor of LE， the slope ? estimated by the characteristic space method is significantly correlated with the measured value， and the estimated accuracy of ? will directly affect the estimated results of LE. Therefore， the characteristic space method is suitable for areas and periods with soil water content as the dominant factor of LE， and it should meet the negative correlation between vegetation index and land surface temperature. In addition， it should be noted that when selecting the study area of characteristic space method， it must ensure that the scatters of vegetation index and land surface temperature are in a regular "triangle".