Towards a novel high-spatial-resolution satellite rainfall product from C-band SAR Sentinel-1 over Central South Korea based on a bottom-up approach

Generation of High-Resolution Gridded Runoff Product for the Republic of Korea Sub-Basins from Seasonal Merging of Global Reanalysis Datasets

“…This is due to the fact that higher weights were assigned to the most superior product in these regions, the ERA5L runoff product. Especially for the central Republic of Korea, the better performance of the ERA5L runoff also links to the superior performance of the ERA5L rainfall product in this region, which is consistent with the previous finding [31,49]. Moreover, according to the vegetation cover map in Figure 1b, it can be seen that superior performances of the merged product over the Geum River, Seomjin River, and Yeongsan River (in terms of lowest ubRMSE and MBE values) watersheds overlap a vast majority of low vegetation regions.…”

“…Another problem is that the TC merging method was preferred at the global scale rather than at the sub-basin level, while the runoff can strongly vary even at a small scale across adjacent sub-basins due to the high spatial heterogeneity of the landscape. In the context of the Republic of Korea where diverse vegetation conditions, complex terrains, and strong seasonal rainfall differences between rainy (wet) and non-rainy (dry) seasons under the summer monsoon's (Changma) effects [31] may lead to high uncertainties in runoff behavior, focusing on improving seasonal runoff estimates at the sub-basin level with more detailed spatial information derived from global products is necessary [32][33][34][35][36].…”

“…Seasonal Separation: This study employed the seasonal merging of runoff products, so separating the seasonal runoff variation periods is required. Despite the four clear seasons in the Republic of Korea, the runoff behavior can vary following the seasonal rainfall variation under the East-Asia monsoon effects rather than these four seasons, where intensified rainfall occurring in the rainy season (mostly summer and fall) [31] can lead to a rapid increase in total runoff. Therefore, we decided to separate the runoff data period in the Republic of Korea into two seasons based on the rainfall seasons.…”