辽东半岛顶端海域上升流长期变化特征及影响因素

LONG-TERM VARIATION OF UPWELLING AT THE TIP OF LIAODONG PENINSULA: FEATURES AND FACTORS

利用回归分析、相关性分析等分析方法,对全球气候变暖背景下辽东半岛顶端海域上升流的变化特征及影响因素进行了研究。结果表明:夏季,辽东半岛顶端邻近海域上升流以38°52′N、120°55′E为中心,呈纺锤状分布于复州湾-辽东半岛顶端-北砣矶水道沿线海域,其位置较为固定。1988-2018年,海表温度上升流指数呈显著增加的变化趋势,其变化速率为0.27℃/10a,研究海域上升流显著增强,其中1998-2018年上升流增强尤为显著。在全球气候变暖背景下,渤海及北黄海部分海域净辐射通量的增加和夏季风场的减弱是研究海域上升流增强的两个影响因素。净辐射通量的增加和夏季风场的减弱分别有利于非上升流与上升流区的温差增大和底层冷水的上涌,进而使上升流现象增强。在长时间尺度上,ENSO(El Niño-Southern Oscillation)不会影响研究海域上升流强度的变化趋势,但在强厄尔尼诺发展阶段(1997年和2014年),ENSO可使研究海域纬向风(西风)增强,从而减弱研究海域上升流。

The variation features and influencing factors of upwelling in the top sea area of Liaodong Peninsula under the background of global warming were studied by means of regression analysis and correlation analysis.The results show that in summer,the upwelling in the adjacent sea area of the tip of Liaodong Peninsula is centered at 38°52′N and 120°55′E,and is distributed in a spindle-like shape in the sea area along the Fuzhou Bay,the tip of Liaodong Peninsula and the Beidangji Channel,with its position relatively fixed.From 1988 to 2018,the upwelling index of sea surface temperature showed a significant increase trend,and its variation rate was 0.27°C/10a,and the upwelling in the study area was significantly enhanced.During the research period,the upwelling from 1998 to 2018 was more significant.Under the background of global warming,the increase of net radiation flux and the decrease of summer monsoon in the Bohai Sea and the North Yellow Sea are the influencing factors for the enhancement of upwelling in the research area.The increase of net radiation flux and the decrease of summer monsoon are beneficial to the increase of temperature difference between the non-upwelling and upwelling regions,and to the upwelling of the bottom cold water,thus enhance the upwelling phenomenon.In a long time scale,ENSO does not affect the variation trend of upwelling intensity in the research area,but in the development stage of strong El-Niño(1997 and 2014),it can increase the zonal westerly wind of the research area and weaken the upwelling of the study seas.