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www.hydrol-earth-syst-sci-discuss.net/7/6699/2010/
doi:10.5194/hessd-7-6699-2010
© Author(s) 2010. This work is distributed
under the Creative Commons Attribution 3.0 License.
Developing an improved soil moisture dataset by blending passive and active microwave satellite-based retrievals
1School of Civil and Environmental Engineering, University of New South Wales, Sydney, Australia
2Department of Hydrology and Geo-Environmental Sciences, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
3Institute for Photogrammetry and Remote Sensing, Vienna University of Technology, Vienna, Austria
4CSIRO Land and Water, Black Mountain Laboratories, Canberra, Australia
5Climate Change Research Centre, University of New South Wales, Sydney, Australia
Abstract. Combining information derived from satellite-based passive and active microwave sensors has the potential to offer improved retrievals of surface soil moisture variations at global scales. Here we propose a technique to take advantage of retrieval characteristics of passive (AMSR-E) and active (ASCAT) microwave satellite estimates over sparse-to-moderately vegetated areas to obtain an improved soil moisture product. To do this, absolute soil moisture values from AMSR-E and relative soil moisture derived from ASCAT are rescaled against a reference land surface model date set using a cumulative distribution function (CDF) matching approach. While this technique imposes the bias of the reference to the rescaled satellite products, it adjusts both satellite products to the same range and almost preserves the correlation between satellite products and in situ measurements. Comparisons with in situ data demonstrated that over the regions where the correlation coefficient between rescaled AMSR-E and ASCAT is above 0.65 (hereafter referred to as transitional regions), merging the different satellite products together increases the number of observations while minimally changing the accuracy of soil moisture retrievals. These transitional regions also delineate the boundary between sparsely and moderately vegetated regions where rescaled AMSR-E and ASCAT are respectively used in the merged product. Thus the merged product carries the advantages of better spatial coverage overall and increased number of observations particularly for the transitional regions. The combination approach developed in this study has the potential to be applied to existing microwave satellites as well as to new microwave missions. Accordingly, a long-term global soil moisture dataset can be developed and extended, enhancing basic understanding of the role of soil moisture in the water, energy and carbon cycles.
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Notice on Discussion StatusCitation: Liu, Y. Y., Parinussa, R. M., Dorigo, W. A., de Jeu, R. A. M., Wagner, W., van Dijk, A. I. J. M., McCabe, M. F., and Evans, J. P.: Developing an improved soil moisture dataset by blending passive and active microwave satellite-based retrievals, Hydrol. Earth Syst. Sci. Discuss., 7, 6699-6724, doi:10.5194/hessd-7-6699-2010, 2010. Bibtex EndNote Reference Manager XML
