A Study of the Atmospheric Turbulence Structure and Flux Transfer at the Sea Surface during the Onset of SCS Monsoon

The observation experiment of air-sea interface flux is crucial to understand the physical and thermodynamic exchange processes for the onset, maintenance and variability of SCS monsoon. Air-sea flux observation tower (18m)was installed in Xisha offshore, the middle of SCS. Turbulent fluxes have been measured on the marine surface layer during SCSMEX(South China Sea Monsoon Experiment) in May14-June 22,1998 and May7-June17, 2000. The preliminary results of fluctuation and gradient measurements of wind velocity, air temperature and moisture at the air-sea flux tower are presented. Intensities of turbulence are estimated to the values of ¦Òu/=0.096, /=0.066 and /=0.045 respectively at about 10m high during the measured period. The drag coefficient CD of momentum transfer is 1.12 and approximated by the expression . The wind spectrum and some parameters include vertical fluxes of momentum, latent and sensible heat obtained from the eddy correlation or profile method are shown with various statistical quantities of turbulence structure such as friction velocity u* and aerodynamic roughness height . Furthermore , these analyzed results are compared with the results on the TOGA-COARE and seen the special characteristics of turbulence structure and flux transfer at the sea surface during the onset of SCS Monsoon .