The Observation And Numerical Simulation Of The Response Of The Upper Ocean To The Typhoon Nanmadol In The Luzon Strait

In this thesis, the water vapor and re-intensification mechanisms of super typhoon,such as typhoon Nanmadol occurred in August2011, are investigated. This paperaims to conclude the relationship between Luzon strait terrain with generating andvanishing process of typhoon. The response features of Luzon strait to typhoonNanmadol are analyzed with the newest data in CFSV2, and further discussion aboutthe response of the Luzon strait to the typhoon, such as current field, SSS, SST andvertical velocity characteristic, is made based on the numerical simulation of athree-dimensional ocean model POM.Firstly inter-annual variations and inter-monthly variations of frequency arecounted in the Pacific Northwest for nearly51years (1961-2011) of tropical cyclonewith Best Track Dataset for Tropical Cyclones over the Western North Pacific in thispaper, the study found that the frequency of tropical cyclones tend to be reduced, andtropical cyclones occurs mainly in July, August and September in a year.Secondly，this paper analyzes the background circulation situation and typhoonwind field structure. The study found that the right side of the wind speed of typhooncyclonic wind field is larger than the left. At the same time, this paper analyzes thewater vapor budget for typhoon development, the results show that sufficient watervapor makes typhoon rapidly strengthen and develop, while reduced supply ofmoisture after the typhoon landed is the main reason for the attenuation o f typhoon.Meanwhile, the paper analyzes the characteristics of the marine field using CFSV2forecast field, as the comparison with the simulation results of POM model.Finally，the response of the upper ocean of the Luzon Strait to Typhoon Nanmadolwas simulated using POM model. The simulation experiment was based on twoaspects, one is the response of the upper ocean of the Luzon Strait to fixed size andposition typhoon wind field, the other is the response of the upper ocean of the LuzonStrait to the motion of Typhoon Nanmadol. The Typhoon Nanmadol wind field andresponse of ocean surface flow field、SST and SSS to Nanmadol was analyzed. Theresults prove that:(1) Luzon Strait in the upper ocean response to asymmetry of typhoon wind field structure, shows the velocity on the right side of the upper ocean isgreater than the left side, as well as the current and typhoon. Sea surface temperature(SST) dropped2-7℃, falling space is hundreds of kilometers in diameter, shows theright strong left weak asymmetry.(2) In the process of the upper ocean response to thefixed typhoon, ocean flow field and SST after reaching extreme value of energy, itwill trigger an anticyclonic flow field which will control the Luzon strait, SST returnsto the initial state after about ten days.(3) Upper ocean response to typhoonmovement shows the one with the typhoon moving ocean flow field, current intensityand SST decline amplitude is smaller, current cyclone structure has certain stretchingalong the path, and in the pate behind a wake. In contrast to the role of typhoonprecipitation, strong evaporation and pumping action play a major role in making SSSdecline of0.3g/kg.