Print Email Facebook Twitter Spatial and Time Warping for Gauge Adjustment of Rainfall Estimates Title Spatial and Time Warping for Gauge Adjustment of Rainfall Estimates Author le Coz, C.M.L. (TU Delft Water Resources; TU Delft Mathematical Physics) Heemink, A.W. (TU Delft Mathematical Physics) Verlaan, M. (TU Delft Mathematical Physics; Deltares) van de Giesen, N.C. (TU Delft Water Resources) Date 2021 Abstract Many satellite-based estimates use gauge information for bias correction. In general, bias-correction methods are focused on the intensity error and do not explicitly correct possible position or timing errors. However, position and timing errors in rainfall estimates can also lead to errors in the rainfall occurrence or the intensity. This is especially true for localized rainfall events such as the convective rainstorms occurring during the rainy season in sub-Saharan Africa. We investigated the use of warping to correct such errors. The goal was to gauge-adjust satellite-based estimates with respect to the position and the timing of the rain event, instead of its intensity. Warping is a field-deformation method that transforms an image into another one. We compared two methods, spatial warping focusing on the position errors and time warping for the timing errors. They were evaluated on two case studies: a synthetic rainfall event represented by an ellipse and a rain event in southern Ghana during the monsoon season. In both cases, the two warping methods reduced significantly the respective targeted (position or timing) errors. In the southern Ghana case, the average position error was decreased by about 45 km by the spatial warping and the average timing error was decreased from more than 1 h to 0.2 h by the time warping. Both warping methods also improved the continuous statistics on the intensity: the correlation went from 0.18 to at least 0.62 after warping in the southern Ghana case. The spatial warping seems more interesting because of its positive impact on both position and timing errors. Subject precipitation estimationfield displacementwarpingTAHMOIMERGgauge datasatellite-based precipitation To reference this document use: http://resolver.tudelft.nl/uuid:fc40e85f-b17c-44d3-a0aa-5ebbc89ba9b1 DOI https://doi.org/10.3390/atmos12111510 ISSN 2073-4433 Source Atmosphere, 12 (11) Part of collection Institutional Repository Document type journal article Rights © 2021 C.M.L. le Coz, A.W. Heemink, M. Verlaan, N.C. van de Giesen Files PDF atmosphere_12_01510_v2.pdf 10.62 MB Close viewer /islandora/object/uuid:fc40e85f-b17c-44d3-a0aa-5ebbc89ba9b1/datastream/OBJ/view