科研之友
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摘要
To retrieve soil moisture from L-band microwave radiometry, it is necessary to account for the effects of temperature within both vegetation and soil media. To compute the effective soil temperature T-G, several simple formulations accounting for soil temperatures at the surface and at depth and surface soil moisture have been developed. However, the effects of the soil physical properties in terms of texture, density, or structure, which all may be important variables in the modeling of T-G, have never been investigated. In this paper, several simple formulations of T-G at L-band, accounting for or ignoring the effects of soil texture and density, were developed and compared based on a very large simulated data set. The best configurations and parameterizations of these simple formulations were computed and could be directly used for operational applications in future soil moisture retrieval studies. For instance, we showed that the use of the surface temperature in the estimation of T-G can be significantly improved by using additional information on the soil temperature at depth (the average error in the estimation of T-G decreased from similar to 4 to similar to 1.8 K). On the contrary, almost no improvement was obtained if air temperature was used instead of surface temperature. Also, it is shown that the use of additional information on the soil properties, mainly the soil clay content and density, led to improved results by about 0.2 K in the estimation of T-G. The improvement was found to be larger for sandy and dry soils: simplified formulations accounting for soil properties are able to represent the fact that T-G is closer to the soil temperature at depth for these soil conditions.
- 出版日期2008-3
- 单位国家气象中心
