Performance of a coupled atmosphere-streamflow prediction system at the Pyungchang River IHP basin

Abstract

A coupled atmosphere-streamflow model has been developed for the Pyungchang River basin in Korea to improve operational rainfall and streamflow forecasts. Here, the authors examine how the modeling system performs for different domain sizes and spatial resolutions from a set of 72-h simulations over the 10-day-period from 00 UTC 24 June to 12 UTC 4 July, 1998. The larger and smaller domains cover East Asia and the Korean Peninsula at spatial resolutions of 60 and 12 km, respectively. For both domains, the simulated rainfall and streamflow show reasonable agreement with observations during the first 48-h-periods. A correlation of 0.89 is obtained between the simulated and observed streamflow for the first 12-h-period. Agreements between the simulated and observed rainfall appear to be highest during the period of 12–24 h from initialization for the smaller domain, and 24–36 h for the larger domain. The results suggest that a larger domain with a coarser resolution requires longer spin-up period than a smaller domain with a fine resolution. The transfer trends from the simulated rainfall to streamflow show a 12-h lag for the Pyungchang River basin, which implies that the streamflow model takes additional spin-up time to respond to the rainfall forcing. The fine resolution simulations generally outperform the coarse resolution ones, perhaps due to better representation of orographic effects in local precipitation and shorter spin-up period.