remote sensing Article Data Assimilation for Rainfall-Runoff Prediction Based on Coupled Atmospheric-Hydrologic Systems with Variable Complexity Wei Wang 1,2, Jia Liu 1,*, Chuanzhe Li 1, Yuchen Liu 1 and Fuliang Yu 1 1 State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China;
[email protected] (W.W.);
[email protected] (C.L.);
[email protected] (Y.L.); yufl@iwhr.com (F.Y.) 2 College of Hydrology and Water Resources, Hohai University, Nanjing 210098, China * Correspondence:
[email protected]; Tel.: +86-150-1044-3860 Abstract: The data assimilation technique is an effective method for reducing initial condition errors in numerical weather prediction (NWP) models. This paper evaluated the potential of the weather research and forecasting (WRF) model and its three-dimensional data assimilation (3DVar) module in improving the accuracy of rainfall-runoff prediction through coupled atmospheric-hydrologic systems. The WRF model with the assimilation of radar reflectivity and conventional surface and upper-air observations provided the improved initial and boundary conditions for the hydrological process; subsequently, three atmospheric-hydrological systems with variable complexity were estab- lished by coupling WRF with a lumped, a grid-based Hebei model, and the WRF-Hydro modeling system. Four storm events with different spatial and temporal rainfall distribution from mountainous catchments of northern China were chosen as the study objects. The assimilation results showed a general improvement in the accuracy of rainfall accumulation, with low root mean square error and Citation: Wang, W.; Liu, J.; Li, C.; high correlation coefficients compared to the results without assimilation.