Numerical assimilation Study of Storm Surge and Research on Fitting Method of Altimetry Data.pdf

1、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

2、 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 throu

3、gh 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

4、 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 t

5、he 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

6、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 7

7、203 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 s

8、tudy 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