Dynamical Downscaling Of The Sea Surface Winds Over The East China Sea

The dynamic downscaling method is used widely for the simulation of the temperature and precipitation, but it is used rarely for the simulation of sea winds. Research on dynamic downscaling sea winds in China is rare, and there are no studies on dynamic downscaling of the East China Sea. In order to test the downscaling ability of WRF(Weather Research and Forecast) model runs in the East China Sea and review the applicability of dynamical downscaling methods in the East China Sea, regional climate simulation tests were made, driven by the NCEP reanalysis data FNL. Firstly, three tests vary with different re-initialization schemes to evaluate the simulation of the sea winds in 2009. Then, spectral nudging scheme was added into the three tests before to evaluate the improvement of simulations and find the best way to improve the simulation. Finally, sensitivity tests varied with different combinations of cumulus parameterization schemes and boundary layer schemes focusing on the simulation of typhoons which plays an important role in sea winds over the East China Sea in summer. The main conclusions are as follows:1) By the simulations of different re-initialization schemes, the ability of the simulation of monthly mean sea winds has been proved, and the performance of the simulations in winter is better than its in summer. According to the simulations of 1448 times of wind speed and wind direction, the best test is 5 DAY test, which means re-initialization in 5 days is the best ways to simulate sea winds over the East China Sea than others.2) Spectral nudging scheme was added into the three tests before. It changed very little in the simulation of monthly mean sea winds. According to the simulations of 1448 times of wind speed and wind direction,5 DAYS and 10 DAYS test improved obviously, and 10 DAYS test improved more obviously than 5 DAYS test. But the best performance of simulations is 5 DAYS test.10 DAYS test took second place. The performance of YEARS test was worse than YEAR test, which means adding spectral nudging scheme into continuous long-term integration simulation could not improve the simulation.3) Sensitivity tests varied with different combinations of cumulus parameterization schemes and boundary layer schemes focusing on the simulation of typhoons which plays an important role in sea winds over the East China Sea in summer.The results show that even the best combination of parameterization scheme was different for each typhoon on the simulation of the typhoons’track, the combination of cumulus parameterization scheme KF and boundary layer scheme MYJ produced the best simulation on the track overall, and the combination of cumulus parameterization scheme KF and boundary layer scheme YSU produced the best simulation on the intensity of the typhoons overall.4) By analyzing the typical typhoons, the results show that the combination of cumulus parameterization scheme KF and boundary layer scheme MYJ produced the best simulation on the track due to its best simulation on the large scale circulation, and when the typhoon’s intensity rapidly strengthened, sensitivity of the combination of cumulus parameterization scheme KF and boundary layer scheme YSU is better than the combination of cumulus parameterization scheme KF and boundary layer scheme MYJ, and when the typhoon’s intensity rapid strengthened, sensitivity of the combination of cumulus parameterization scheme KF and boundary layer scheme MYJ is better than the combination of cumulus parameterization scheme KF and boundary layer scheme YSU.