Numerical assimilation Study of Storm Surge and Research on Fitting Method of Altimetry Data
Based on the simulation of storm surges resulting from Typhoons 7203 and 8509 in the Bohai Sea, Yellow Sea and East Cluna Sea, water level data at tide stations areassimilated into a two-dimensional storm surge model, to study the spatially varyingdrag coefficient (DC) by employing the adjoint method. In this study, the DC at somegrid points is uniformly selected as the independent DC, while the DCs at other gridpoints is obtained through linear interpolation of the independent DC. The DC atindependent points is optimized by employing the adjoint assimilation method, andglobal optimization is achieved by optimizing the independent DC. To demonstratethe method's performance, three comparative experiments are carried out. In the firstexperiment, the DC is treated as a constant. In the second and third experiments, theDC is derived using an empirical formula. Comparing the experimental results, it isfound that the simulation accuracy for both Typhoons 7203 and 8509 increases greatlywhen optimizing the independent DC. However, the number of independent pointsmakes no great difference to the precision of simulation. Moreover, the DC invertedfrom Typhoons 7203 and 8509 differs in some sea areas because of the differenttyphoon tracks. However, the spatial distribution of the inverted DC, for bothTyphoons 7203 and 8509, demonstrates a clear effect of the DC on the storm surge modeling near the coastal areas where the DC is highest or lowest. Besides, a series ofrandom noises are applied to the windfield of the typhoon to study theeffectsofuncertaintiesin thewindfield on the DC. By checking the change of simulated surge elevations and the inverted DC, we conclude that the inverted DC is affected by uncerlainties in the wind field, but the effect is very small. The inverted DC is statistically analyzed and the results show that the DC is closely related to the local water depth and wind speed.
数值同化;风暴潮;卫星测高数据;拟合方法
中国海洋大学
硕士
Physical Oceanography
Xianqing Lv professor
2011
P731.23
63
2011-11-02（万方平台首次上网日期，不代表论文的发表时间）