Sea surface winds and coastal winds, which have a significant influence on the ocean environment, are very difficult to predict. Although most planetary boundary layer (PBL) parameterizations have demonstrated the capability to represent many meteorological phenomena, little attention has been paid to the precise prediction of winds at the lowest PBL level. In this study, the ability to simulate sea winds of two widely used mesoscale models, fifth-generation mesoscale model (MM5) and weather research and forecasting model (WRF), were compared. In addition, PBL sensitivity experiments were performed using Medium-Range Forecasts (MRF), Eta, Blackadar, Yonsei University (YSU), and Mellor-Yamada-Janjic (MYJ) during Typhoon Ewiniar in 2006 to investigate the optimal PBL parameterizations for predicting sea winds accurately. The horizontal distributions of winds were analyzed to discover the spatial features. The time-series analysis of wind speed from five sensitivity experimental cases was compared by correlation analysis with surface observations. For the verification of sea surface winds, QuikSCAT satellite 10-m daily mean wind data were used in root-mean-square error (RMSE) and bias error (BE) analysis. The MRF PBL using MM5 produced relatively smaller wind speeds, whereas YSU and MYJ using WRF produced relatively greater wind speeds. The hourly surface observations revealed increasingly strong winds after 0300 UTC, July 10, with most of the experiments reproducing observations reliably. YSU and MYJ using WRF showed the best agreements with observations. However, MRF using MM5 demonstrated underestimated winds. The conclusions from the correlation analysis and the RMSE and BE analysis were compatible with the above-mentioned results. However, some shortcomings were identified in the improvements of wind prediction. The data assimilation of topographical data and asynoptic observations along coast lines and satellite data in sparsely observed ocean areas should make it possible to improve the accuracy of sea surface wind predictions.

[1] The seasonal variation of eddy kinetic energy (EKE) of the North Pacific Subtropical Countercurrent (STCC) was investigated by analyzing the data from an eddy-resolving OGCM with the horizontal resolution 1/12°in comparison with satellite altimetry data. Although the annual cycle of simulated EKE of the whole STCC domain showed agreement with satellite data, with a maximum in spring and a minimum in fall, it revealed latitudinal dependence; that is, near 19°N the EKE level is higher in summer than in winter, but it is higher in winter than in summer north of 20°N. The OGCM also reproduced two branches of the STCC, which affect the EKE variation. The variation of EKE level was shown to be closely related to the growth rate of baroclinic eddies. The simulated zonal velocity is much larger than climatological value, thus allowing much faster growth of baroclinic eddies. Citation: Noh, Y., B. Y.

On 31 March 2007, the abnormal wave occurred along western coast of Korean including Yeonggwang. In this paper, this event is studied using available field measurement data for the event analysis and numerical model for reproducing the unknown waves. We found several 1-min interval tidal elevation and mean sea level pressure (MSLP) data along the western coast of Korea and analyzed it using wavelet technique. We computed the arrival time and the propagation direction of abnormal wave using wavelet results and performed the numerical simulation using 2 dimensional shallow water wave model. The sea level under the forcing of air pressure jump was obviously amplified by the Proudman resonant effect. The computed sea levels compared with observations are underestimated, but the order of arrival time at the tidal station showed good agreement.

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The vertical structure of meridional eddy heat transport (EHT) of the North Pacific was investigated by analyzing the results from an eddy-resolving ocean general circulation model (OGCM) with a horizontal resolution of , while comparing with previous simulation results and observation data. In particular, the spatial and temporal variation of the effective depth of EHT He was investigated, which is defined by the depth integrated EHT (D-EHT) divided by EHT at the surface. It was found that the annual mean value of He is proportional to the eddy kinetic energy (EKE) level at the surface in general. However, its seasonal variation is controlled by the mixed layer depth (MLD) in the extratropical ocean (>20°N). Examination of the simulated eddy structures reveals that the temperature associated with mesoscale eddies is radically modified by the surface forcing in the mixed layer, while the velocity field is not, and the consequent enhanced misalignment of temperature and velocity anomalies leads to the radical change of EHT across the seasonal thermocline.