利用HJ-1B遥感数据反演西北地区近地表气温

    Estimation of near-surface air temperature from HJ-1B satellite data in Northwest China

    • 摘要: 近地表气温是一个重要的气候参数,为了给农业研究提供空间上连续的气温信息,以西北地区为研究区,利用HJ-1B数据运用温度-植被指数方法(temperature-vegetation index, TVX)反演近地表气温。首先采用修正普适性单通道算法反演地表温度,并利用同一地区的MODIS温度产品进行了对比验证,然后利用2010年7月20日、2010年8月28日、2011年8月8日3景影像结合研究区气象站点观测的气温资料推算饱和NDVI值,最后将推算结果应用到2011年8月28日影像,利用气象站点观测资料对TVX方法反演的气温进行了精度验证。结果表明,反演地表温度与MODIS温度产品空间分布趋势基本一致,符合研究区的地表覆盖状况;反演气温与反演地表温度空间分布格局具有较好的一致性,可以提供比气象站点观测数据更理想的空间异质性信息;反演气温值比观测值偏高,二者平均绝对误差MAE为2.16 K,均方根误差RMSE为2.72 K。为快速有效获取大范围的气温时空信息提供了一种新思路,对科学指导农业生产、合理利用农业资源具有一定的可参考性。

       

      Abstract: Abstract: Near-surface air temperature is an important meteorological parameter, and is closely related to agriculture production. In this paper, the temperature-vegetation index method (TVX method, also called contextual method) for the area-wide mapping of instantaneous air temperature was adopted for use with HJ-1B data in Northwest China. The approach was complemented with an iterative filtering routine for eliminating outliers, and an interpolation algorithm for filling in data gaps. The air temperature at the time of satellite passing through was estimated from the maximum and minimum air temperature measured in a meteorological station with a simple sine curve model, and we still labeled it as "measured" air temperature. The improved generalized single-channel algorithm was adopted for retrieved surface temperature, and the results were validated by comparison with MODIS land surface temperature products (MOD11_L2). In addition, the meteorological measured air temperatures and three scenes HJ-1B data on July 20,2010, August 28, 2010, and August 8, 2011 were adopted for parameterization of NDVImax. Then the NDVImax was applied to HJ-1B data on August 28, 2011, and the retrieved air temperatures were validated by the meteorological measured air temperatures. The results showed that the land surface temperature retrieved with the improved algorithm were consistent with those provided by the MODIS product, and that the satellite-derived air temperature also had a consistent distribution with land surface temperature, the satellite-derived air temperatures were in good agreement with the meteorological observed values with MAE=2.16 K, RMSE=2.72 K, and the accuracy was in line with previously reported results for the TVX method. There are difficulties in relating the satellite-derived air temperature to a fixed shelter height, therefore the results of this study showed that the remote sensing approach tends to overestimate the in situ air temperatures. It is concluded that near-surface air temperature can be retrieved effectively from HJ-1B satellite data through the use of the TVX method.

       

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