琼东上升流的年际变化及长期变化趋势

THE INTERANNUAL VARIATION AND LONG-TERM TREND OF QIONGDONG UPWELLING

全球变暖背景下沿岸上升流的年际变化是近年来的研究热点。本文基于1982—2012年的海表面温度和风场资料,分析了琼东上升流的强度和中心位置的年际变化规律以及沿岸风应力及其旋度的作用。结果显示,近30年来,琼东上升流强度总体减弱,相比于沿岸风应力,其变化与减弱的局地风应力旋度相关性更高;琼东上升流强中心位置最大概率发生在19.2°—19.3°N,与最大风应力旋度位置接近,且存在北移趋势。琼东上升流强度和位置的年际变化还存在周期约3年、5年和10年的本征模态,以3年周期变化为主。局地风应力旋度在琼东上升流的年际变化中发挥了重要作用。

The interannual variation of coastal upwelling in the global warming has become a focus of study in recent studies. Using sea surface temperature and wind velocity data of 1982--2012, we investigated the intensity and the core location of the Qiongdong Upwelling （QU）, and the roles of alongshore wind stress and local wind curl. Results show that the intensity of QU trends to decrease in recent 30 years. Compared with the alongshore wind stress, QU is more closely correlated to the variation of local wind curl that shows a decreasing trend too. The QU core location would occur most probably in 19.2°--19.3°N zone, which is close to the area where maximum wind curl often occurs, and tends to move northward. Three intrinsic modes in period of 3, 5, and 10 years are found in upwelling intensity and core location variation, of which the 3-year one dominates the variation. In addition, local wind curl plays an important role in the QU interannual variation.