The effect of Typhoon on coastal upwelling in the Northern Japanese coastal using a three-dimensional primitive equation numerical modelA three-dimensional primitive equation model (the Princeton ocean Model, often called POM) has been implemented for simulating Typhoon Oliwa to examined the coastal upwelling . A sudden temperature decrease(Senjyu and Watanabe, 1999) along the sanin coast was observed after the passage of Typhoon oliwa. The model reproduces well the prominent features obtained in the observation such as wind and atmospheric pressure especially SST decrease (-6 to -7), and reasonably explains it to be induced by coastal upwelling in a classical theory. What is more, typhoon simulation was implemented under several different condition: track, moving speed, minimal central pressure and grid interval. Model results suggest that The SST cooling is a lively function of track, moving speed and central pressure, a weak function of grid size. 1. IntroductionDuring the last two centuries, tropical cyclones(typhoon) have been responsible for the deaths of about 1.9million people worldwide. It is estimated that 10,000people per year perish due to tropical cyclones.Many tropical cyclones frequently occur in the Pacific Ocean and move northward in the summer, affecting the oceanic conditions in the northwestern Pacific Ocean(Figure 1), as well as causing casualties and terrible damage to property in the nearshore countries. A primary response to tropical cyclones (hereafter typhoons) is to cool sea surface water. Many authors have reported this sea surface cooling (SSC) associated with physical and biogeochemical response, especially in the open ocean of the western North Pacific.Most recently,numerical model has been implemented to examine the behaviors of typhoons.Senju and Watanabe 1999 observed a sudden temperature decrease along the Sanin coast when the typhoon was approaching and the sudden temperature decrease was attributed to an upwelling . Wada 2003 implemented numerical simulations to elucidate the 3C SST cooling by Typhoon Rex , and Hoon and Yoon2003 simulated Typhoon Holly using a three-dimensional numerical model However, it seems that there have been got a couple of reports the SSC, especially in the coastal regions of the North Pacific, despite the fact that many typhoons very often land on the continents in this region. If the SSC with typhoon passage is found in the coastal region, it should be induced by coastal upwelling in a classical Ekman dynamics (Yoshida, 1955). Senjyu and Watanabe (1999; hereafter SW) firstly observed a rapid SST decrease along the northern Japanese coast in the East/Japan Sea (here after the East Sea) with the passage of Typhoon Oliwa (1997) (Figure 1). During the typhoon passage, the five stations (Figure 1b) including Island Mishima recorded all the SST decrease ranging from -6 to -8C (Figure 1c). A measurement in Island Mishima (dotted lines) was performed by by a ferry boat before and after Oliwa. In fact, coastal upwelling can occur whenever the wind blows in parallel with a coast. During the Typhoon Oliwa, the wind at Hamada (Figure 1d) was basically north-easterly along the northern Japanese coast, thus most preferable here to coastal upwelling as pointed out by SW. The goal of this paper is to find out what role do the condition (track, moving speed,central pressure and grid interval) play in the SST. 2. Numerical Model2.1 Governing EquationThe Princeton ocean model (POM) is a community general numerical model for ocean circulation that can be used to simulate and predict oceanic currents, temperatures, salinities and other water properties. The model incorporates the MellorYamada turbulence scheme developed in the early 1970s by George Mellor and Ted Yamada; this turbulence sub-model is widely used by oceanic and atmospheric models. At the time, early computer ocean models such as the BryanCox model (developed in the late 1960s at the Geophysical Fluid Dynamics Laboratory, GFDL, and later became the modular ocean model, MOM), were aimed mostly at coarse-resolution simulations of the large-scale ocean circulation, so there was a need for a numerical model that can handle high-resolution coastal ocean processes. The BlumbergMellor 1987 model (which later became POM) thus included new features such as free surface to handle tides, sigma vertical coordinates (i.e., terrain-following) to handle complex topographies and shallow regions, a curvilinear grid to better handle coastlines, and a turbulence scheme to handle vertical mixing.The model formulated by a Cartesian coordinate solves the following traditional hydrodynamics equations for conservation of mass, momentum, temperature, and salinity coupled with the equation of state, (1) (2) (3) (4) (5)