SST variations of the Kuroshio from AVHRR observation

1 INTRODUCTION The Kuroshio Current (KC), being the western boundary current in the North Pacific subtropical gyre, is the second strongest current in the world af- ter the Gulf Stream and is famous as a strong and fast flow. KC plays an important role in…

SST variations of the Kuroshio from AVHRR observation

Using monthly gridded ocean pathfinder Sea Surface Temperature (SST) data with a spatial resolution of 4km from AVHRR, variations of SST over the Kuroshio region northeast of Taiwan Is. during the past two decades (1985–2003) are studied. Some interesting findings are as follows. (1) The climatological SST field shows an expected pattern with southwest-northeast orientated isotherms, and this pattern is mainly dominated by solar irradiance and regional circulation. However, the interannual variation of this pattern is very notable, in particular along Kuroshio path. The most dynamic region is located in the east coast of Taiwan, where cold upwelling is very energetic. (2) Seasonal variation of SST over this region is mainly controlled by see-saw variation of solar irradiance between two hemispheres, but the strong interannual fluctuation of SST is found to be locked to boreal winter (January, February, and last December), and the energetic region is identified along Kuroshio path. This phenomenon seems to closely connect with El Niño’s phase locking characteristics. (3) SST anomalies over Kuroshio region have a positive correlation with El Niño-Southern Oscillation (ENSO), which is dramatic due to the weak (strong) North Equatorial Current (NEC) during El Niño (La Niña) events, and the weak (strong) NEC is supposed to induce a same polarity of SST variation along the Kuroshio path. How the interannual variation and seasonal variation interact each other and what is the mechanism between ENSO and the thermal and thermodynamic processes over this region deserve our further analyses.