Producing the Hindcast of Wind and Waves Using a High-Resolution Atmospheric Reanalysis around Korea

Abstract

The Weather Research and Forecasting Model (WRF) and its variational data assimilation system (WRFDA) are applied to all of the surrounding seas of the Korean Peninsula for a high-resolution regional atmospheric reanalysis study. Observational data are assimilated every 6 h, and the results are verified against unassimilated observations. In this study, three-dimensional variational data assimilation (3DVAR) has been adopted to improve the model's initial conditions and to generate the final high-resolution analysis. For the hindcast of the meteorological data, the real-time analysis field obtained from the global final analysis (FNL) operated by the National Centers for Environmental Prediction (NCEP) is taken as the initial and 6 h forecast files and as initial and lateral boundary conditions. For the wave hindcast, we used the third-generation spectral wave model, WAVEWATCH III (WW3). Both nested wave models consist of a coarse 9 kin model covering the East Asian marginal seas and a nested 2 km resolution model covering all of the surrounding seas of Korean Peninsula forced with 20 km and 4 km resolution hindcasts of winds, respectively. A comparison against in-situ observations of wind and sea states reveals significant improvement in the mean values and upper percentiles of wind vectors and significant wave height. Improvement is also found in the mean wave period. The reanalysis data of wind with the data assimilation technique and waves in this study is also useful for computing the design wave.