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A Novel Approach to Validate Satellite Soil Moisture Retrievals.....


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Work carried out by Karthikeyan Lanka along with Prof D. Nagesh Kumar has been published in Journal of Geophysical Research: Atmospheres.

Article: A Novel Approach to Validate Satellite Soil Moisture Retrievals using Precipitation Data

DOI: 10.1002/2016JD024829

A novel approach is proposed that attempts to validate passive microwave soil moisture retrievals using precipitation data (applied over India). It is based on the concept that the expectation of precipitation conditioned on soil moisture follows a sigmoidal convex-concave shaped curve, the characteristic of which was recently shown to be represented by mutual information estimated between soil moisture and precipitation. On this basis, with an emphasis over distribution free – non-parametric computations, a new measure called Copula–Kernel Density Estimator based Mutual Information (CKDEMI) is introduced. The validation approach is generic in nature and utilizes CKDEMI in tandem with a couple of proposed bootstrap strategies, to check accuracy of any two soil moisture products (here AMSR-E sensor's VUA-NASA and U. Montana products) using precipitation (IMD) data. The proposed technique yields a ‘best-choice soil moisture product’ map which contains locations where any one of the two/none of the two/both the products have produced accurate retrievals. The results indicated that, in general, VUA-NASA product has performed well over U. Montana's product for India. The best-choice soil moisture map is then integrated with land use land cover and elevation information using a novel PDF based procedure to gain insight on conditions under which each of the products has performed well. Finally, impact of using a different precipitation (APHRODITE) dataset over the best-choice soil moisture product map is also analyzed. The proposed methodology assists researchers and practitioners in selecting appropriate soil moisture product for various assimilation strategies at both basin and continental scales.

Karthikeyan L. and D. Nagesh Kumar (2016). A Novel Approach to Validate Satellite Soil Moisture Retrievals using Precipitation Data. Journal of Geophysical Research: Atmospheres, DOI: 10.1002/2016JD024829.

Prof. Nagesh Kumar can be reached at

Thanks & Regards

Sonali Pattanayak
Research Associate
Divecha Center for Climate Change