青藏高原东北部MODIS地表温度重建及其与气温对比分析

Reconstruction of MODIS Land Surface Temperature in Northeast Qinghai-Xizang Plateau and Its Comparison with Air Temperature

通过遥感获取地表温度(地温,LST)可以弥补气象站LST数据局地性的不足。但受某些因素影响,遥感LST影像存在噪音像元,影响了LST数据的应用。本文提出了一种基于高程-温度回归关系的空间重建算法,对2008年青藏高原MODIS LST影像异常低值像元进行了重建,得到空间完整的LST时间序列。分别将原始LST和重建LST与研究区62个气象站最高气温进行对比分析,结果表明,重建前后LST与最高气温一致性很好,相关系数分别为0.88和0.91,各气象站平均相关系数达到0.898,LST一般高于气温,平均偏差为6.98℃。地气温差与海拔、土地覆盖、季节和噪音水平有关。海拔越高,地气温差越大;植被覆盖越好,地气温差越小;温度越高,温差越大。研究还发现,重建后的数据在森林覆盖区仍然残留噪音,这需要结合LST的质量控制信息做进一步研究。

Land surface temperature（LST） derived from remote sensing data is a good alternative because the traditional LST from meteorological station has a local problem.Yet remote sensing LST may suffer from noises from various sources,which greatly degrade the LST quality and hamper its efficient application.This paper presents a novel algorithm which can reconstruct the complete LST based on relationship of DEM and LST.TERRA MODIS-LSTs in northeast Qinghai-Xizang Plateau in 2008 are reconstructed using this method.Comparison of origin LST and reconstructed LST data with maximum air temperature（T） observations at 62 meteorological stations in the study region indicates that LST is significantly correlated with T,with correlation coefficient of 0.88 and 0.91,respectively,and average correlation coefficient is 0.898 at each station.By the average,LST has a 6.98 ℃ bias over T.The land-atmosphere temperature difference is related with the sea level elevation,vegetation cover,season and noise.The heighter sea level elevation is,the larger land-atmosphere temperature difference is;the denser vegetation coverage is,the smaller earth-atmosphere temperature difference is;the higher temperature is,the larger temperature difference is.It is also found that there are still some residual noises in well-vegetated areas after reconstruction.Therefore,the further study is required to identify the sources of noises,for instance,using the quality control information and 1 day LST.