Backscattering coefficients for the L-, C-, and X-bands, vegetation indices (RVI, NDVI, and LAI), and crop growth data (VWC) were observed over rice and soybean growth cycles.
RVI for all frequency bands gradually increased in accordance with crop growth and decreased with a reduction of VWC.
RVI for L-, C-, and X-bands was compared to VWC, LAI, and NDVI. It was found that L-band RVI was well correlated with VWC, LAI, and NDVI. Retrieval equations were developed for estimating VWC using the RVI in both crops.
The most accurate VWC retrievals were achieved using the L-band RVI, and these were better than the C- and X-band RVIs. Combining both crops using L-band RVI resulted in a robust VWC relationship. This investigation focused on a 40◦ single incidence angle observing system, as will be employed with SMAP. It is expected that the effects of the incidence and the azimuth angle could affect the results. These results demonstrate the potential of using L-band radar observations from upcoming satellite missions that include Aquarius (2011) and SMAP (2014) to retrieve VWC information and contribute to crop growth monitoring.
Backscattering coefficients for the L-, C-, and X-bands, vegetation indices (RVI, NDVI, and LAI), and crop growth data (VWC) were observed over rice and soybean growth cycles.RVI for all frequency bands gradually increased in accordance with crop growth and decreased with a reduction of VWC.RVI for L-, C-, and X-bands was compared to VWC, LAI, and NDVI. It was found that L-band RVI was well correlated with VWC, LAI, and NDVI. Retrieval equations were developed for estimating VWC using the RVI in both crops.The most accurate VWC retrievals were achieved using the L-band RVI, and these were better than the C- and X-band RVIs. Combining both crops using L-band RVI resulted in a robust VWC relationship. This investigation focused on a 40◦ single incidence angle observing system, as will be employed with SMAP. It is expected that the effects of the incidence and the azimuth angle could affect the results. These results demonstrate the potential of using L-band radar observations from upcoming satellite missions that include Aquarius (2011) and SMAP (2014) to retrieve VWC information and contribute to crop growth monitoring.
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