ANALYSIS OF COLD PATCH ON THE SEA OFF NORTHEASTERN TAIWAN

摘要

Mechanisms of the occurrence frequency of cold patch on the sea off northeastern Taiwan are analyzed using multi-sensor data from different satellites. In this study, Sea surface temperature (SST) data derived from infrared sensors, sea surface height anomaly (SSHA) data derived from satellite altimeters, as well as sea surface wind data derived from microwave scatterometers are analyzed by Empirical Orthogonal Function (EOF) and Fast Fourier Transform (FFT) methods to investigate the temporal variability of the cold patch. According to the analyses of SSHA data from 1993 to 2009 and SST data from 1985 to 2008, the variations of cold patch have an interannual oscillation around 5 years, annual cycle, and an intra-seasonal fluctuation with main peak centered at 62 days. The variations of annual and intra-seasonal periods of the cold patch may be affected by the migration of Kuroshio suggested by previous studies. Sea surface wind stress data are also analyzed. After applying a 13-month running mean filter, the primarily period of the wind stress data is an inter-annual period of around 5 years which is the same as that of SSHA and SST. It implies that generating vertical motion in the sea off northeastern Taiwan is significantly impacted by the sea surface wind filed fluctuation. This suggests that not only Kuroshio but also sea surface wind stress play roles in modifying the occurrence frequency of the cold patch on the sea off northeastern Taiwan.