| Summary: | 碩士 === 國立中山大學 === 海洋資源學系 === 88 === Brightness temperature data measured by the special sensor microwave imager (SSM/I) onboard the F11 and F14 satellites were used in this study to estimate the wind speed, air temperature and specific humidity over the South China Sea (SCS). The results were compared with the in-situ measurements during IOP (from April to June, 1998) of the South China Sea Monsoon Experiment (SCSMEX) with a collocation window of 1 hr and 25 km. After evaluation of various methods the following algorithms or data sources were selected in this study.(1) Surface winds: Goodberlet et al. (1989),(2)Surface specific humidity: Schulz et al.(1993),(3)Weekly sea surface temperature: National Centers for Environmental Prediction (NCEP),(4)Surface air temperature: Kubota and Shikauchi(1995). Good correlations were found between SSM/I results and ground truth.
Daily retrievals of wind speeds, specific humidity, air temperature together with NCEP SSTs are then spatially averaged to each 1°×1°grid box over the SCS for the period of April, May and June 1998. The monthly values of air-sea fluxes were then estimated by the bulk method. These results are compared with the 10-year average results (1998~1997) derived from the Comprehensive Ocean-Atmosphere Data Set (COADS). It is found that regions of higher values of SST often correspond to higher humidity difference and lower winds. Overall speaking, latent and sensible heat fluxes are largely controlled by the wind speed, but the spatial distributions of the air-sea fluxes are also influenced by the temperature and humidity differences. The latent heat fluxes over the SCS show seasonal variations. In the period of winter monsoon, higher values of latent heat flux occur at the northeastern part of SCS. Contrarily, higher values of latent heat flux occur at the southwestern part of SCS during the summer monsoon.
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