Effect of radar measurement error on the detection of transient inland water bodies

This paper studies the identification of inland transient water bodies using an L-band radar, especially the dependence of the identification accuracy on the radar measurement noise (noise-equivalent radar backscatter, σ νε). The different levels for the radar measurement noise are simulated using the images taken by the Uninhabited Aerial Vehicle Syn thetic Aperture Radar (UAVSAR). With the original UAVSAR σ⁰_NE of -45 dB the detection error is 2%. When σ⁰_NE is raised to -28.5 dB and -25.5 dB, the error increases to 7% and 15% respectively. The analyses of the UAVSAR images over two different locations report the consistent results. 15% error in the water detection error translates into approximately 2 kelvin error in brightness temperature, when 10% of a 36-km radiometer pixel of the Soil Moisture Active Passive (SMAP)1 mission is covered by water surfac es. Based on these considerations, it is recommended that σ⁰_NE for the SMAP mission should be kept as low as the spacecraft and the instrument may support.