Abstract:

SMOS and SMAP are both dedicated to acquire global soil moisture information with L band radiometer. The parallel comparison between them is the key foundation for the integration of a consistent global soil moisture dataset. Though the nominal passing time of SMAP and SMOS are designed fixed, the precise time they move overhead locally may not be the same because of the variation in spatial and temporal, practically it is unable to match SMAP, SMOS and field observations in temporal rigidly, therefore the evaluation on their soil moisture retrievals is hard to carry. Research on this mismatch problem is made in the continental United States; firstly, the overlapping period of the two satellites is determined on the basis of a statistic on the time stamp of 2016~2017 SMOS and SMAP soil moisture data; then, the natural variation characteristics of surface soil moisture within this period is studied using in-situ data which having high density in temporal and large scale in spatial. Results showed that, by grouping the samples in the three conditions of entire, no precipitation and with precipitation, where the sample ratio of 98.14%, 99.51% and 88.49% in each group, respectively, meaning in most cases, the surface soil moisture presents a variation of 0.007 m3/m3, 0.007 m3/m3 and 0.012 m3/m3accordingly, which is far less than the nominal accuracy of SMOS and SMAP (0.04 m3/m3). It can be demonstrated preliminarily, 鈶� the direct comparison of SMOS and SMAP soil moisture retrievals (L2 data) is acceptable, 鈶� validation error induced by the difference of passing time can be neglected.

Key words: SMOS, SMAP, Microwave remote sensing, Surface soil moisture, Soil moisture stability

鎽樿锛�

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鍏抽敭璇�: SMOS, SMAP, 寰尝閬ユ劅, 琛ㄥ眰鍦熷￥姘村垎, 鍦熷￥姘村垎绋冲畾鎬�