Relationships between Sea Surface Wind Speed and the Diurnal Variation of Sea Surface Temperature over the Tropical Ocean

Based on sea surface temperature (SST) and sea surface wind speed (SSW) data retrieval from the tropical rainfall measuring mission (TRMM) microwave imager (TMI) from 1998 to 2007, the authors investigated the features of diurnal variation of SST under the influence of SSW in the tropics under non-precipitation conditions. The retrieved SST and SSW data were matched at TMI resolution within the TMI orbit swath. The results suggest a notable diurnal variation of SST over the topical ocean. The minimum value of the diurnal cycle of SST appears during 0300 LST to 0600 LST and the maximum occurred during 1700 LST to 1900 LST. The diurnal absolute amplitude of SST is about 1.9-3.4℃, and the relative amplitude is about 5%-7%. The effect of SSW on the diurnal SST amplitude is significant and shows the regional characteristics, just as it influences the time of the minimum/maximum value. The diurnal SST amplitude decreases with an increase of the SSW, but it changes only slightly with increasing SSW when the SSW is greater than 9 m/s. Statistical analysis shows a significant sinusoidal correlation between the diurnal SST amplitude and SSW. In particular, reduced SSW leads to a decrease of 0.16℃ in the diurnal SST amplitude in the western equatorial Pacific, whereas enhanced SSW leads to an increase of 0.17℃ in the diurnal SST amplitude over the coastal area of Peru. The above results provide a basis for further research on diurnal variations of latent and sensible heat fluxes.