Application Research On Numerical Forecast Modeling Of Storm Surge In Tianjin Port

Storm surge disasters along Tianjin Port occurr frequently and often cause enormous economic losses and casualties.Accurate prediction of storm surge is urgently needed for services in preventing and reducing storm surge disasters.In this paper, the storm surge data of Tianjin Port, the conventional meteorological observation data and sounding data, Tianjin automatic weather station data and the NCEP reanalysis data sets are used; the paper bases on BoHai Storm Surge Model using numerical simulation method to carry out Tianjin Port storm surge numerical model application research. The research topics include:1) This paper compiles statistics from 1950-2010 storm surge data of Tianjin Port, and analyzes the characteristics of Tianjin Port's storm surge. The results show that the storm surges throughout the full year have occurred in Tianjin Port, which is concentrated in June to November. August is the most concentrated month. Historically,37.8% of storm surges happened in August. Maximum storm surge tide was in September, August and November followed by; Tianjin Port's storm surges occured frequently, the tide level above 470cm, there will be 2.43 times per year average and higher than 500cm tide level occurs every 2.5 years.2) This paper analyzes the special topography of the Bohai sea effects storm surge of Tianjin Port. The results show that not only strong wind over the Bohai Sea continued will cause storm surges,when no wind or offshore wind blowing, if there is a strong weather system (such as cyclones)produced strong easterly winds in the North Huanghai Sea. Because the topography of the Bohai Sea in particular,if a large number of water of the North Huanghai Sea into Bohai Sea, Tianjin Port's tide will be abnormally higher, or even caused storm surges.3) BHSSM is used to simulate 10 cases of storm surge in Tianjin Port; capability of the model simulating different types storm surge is analyzed; The results show that the model's simulation results of typhoon storm surges have large error; The model's simulation results of Strong cyclone storm surges, low pressure and cold front storm surges and cold front storm surges are smaller than the actual tide, and the small magnitude of the three is different.4) The wind stress plays a decisive role on the formation of Bohai sea storm surge. By increasing the drag coefficient of wind stress appropriately,the simulation results of the mode have improved;Experiment shows that the simulation error on the storm surge of strong isolated cyclones type, low pressure of cold front type and cold front type are reduced and the simulation result is closer to the real condition,when the wind stress drag coefficient correction parameter A is adjusted to [0.096,0.16].5) One case of storm surge in 2011 in Tianjin Port is used to test the practicability of adjustment programs on wind stress drag coefficient. The results show that after the adjustment of wind stress drag coefficient, the error between simulated water level and actual water level is effectively decreased, which improves the simulation accuracy of numerical model on Bohai Sea storm surge.