Hydrographic and Biological Changes in the Taiwan Strait During the 1997–1998 El Niño Winter

During the 1997–1998 El Niño event, the average sea surface temperature (SST) in the Taiwan Strait (TWS) in the winter was ∼1.4°C higher than that of the winter climatological mean. The areal ratio of the warm water (≥2°C above the regional mean) to the cold water (≥2°C below the regional mean) in the TWS increased by 25% while the area of the eutrophic water (chlorophyll a >1 mg m ⁻³ ) was halved. Field observations also indicate that the mixed layer in the TWS became more nutrient-poor during this winter. These observations are consistent with a diminished advection of the cold and eutrophic Zhe-Min Coastal Water, and, concomitantly, an expansive intrusion of the warm and oligotrophic South China Sea Warm Current/Kuroshio Branch Water to the TWS as the northeast monsoon was weakened. Thus, El Niño events potentially can have significant ecological impacts on the TWS.