In this paper, the observational data from Marine and Meteorological Observation Platform （MMOP） at Bohe, Maoming and buoys located in Shanwei and Maoming are used to study the characteristics of air-sea temperature and specific humidity difference and the relationship between wind and wave with the tropical cyclones over the South China Sea （SCS）. The heat and momentum fluxes from eddy covariance measurement （EC） are compared with these fluxes calculated by the COARE 3.0 algorithm for Typhoon Koppu. The results show that at the developing and weakening stages of Koppu, both these differences between the sea surface and the near-surface atmosphere from the MMOP are negative, and data from the buoys also indicate that the differences are negative between the sea surface and near-surface atmosphere on the right rear portion of tropical cyclones （TCs） Molave and Chanthu. However, the differences are positive on the left fi＇ont portion of Molave and Chanthu. These positive differences suggest that the heat flux is transferred from the ocean to the atmosphere, thus intensifying and maintaining the two TCs. The negative differences indicate that the ocean removes heat fluxes from the atmosphere, thus weakening the TCs. The wind-wave curves of TCs Molave and Chanthu show that significant wave height increases linearly with 2-min wind speed at 10-m height when the wind speed is less than 25 m/s, but when the wind speed is greater than 25 m/s, the significant wave height increases slightly with the wind speed. By comparing the observed sensible heat, latent heat, and friction velocity from EC with these variables from COARE 3.0 algorithm, a great bias between the observed and calculated sensible heat and latent heat fluxes is revealed, and the observed friction velocity is found to be almost the same as the calculated friction velocity.
The intensity, landing time, track trend and intensity variation of tropical cyclones (TCs) afterlandfall are analyzed using the TCs data (of best track from the China Meteorological Administration)between 1949 and 2006 for the western North Pacific and South China Sea. The trend differences of trackand intensity between the TCs that directly land in East China and those making the second landfall in EastChina after landing in Taiwan Island are categorically discussed. The results show that the first kind oflanding TCs are more likely to go northward or turn while the second kind of TCs have a larger tendency tokeep going northwest. The intensity of the first kind of TCs is more persistent than the second one. There isa higher percentage for the intensity to be weakened significantly if the TCs keep going west to northwest orsouthwest after landing.
