两类开始型厄尔尼诺事件与次表层海温异常的联系
夏 飞1,黎 鑫1,2*,杨明浩1,陈 雄1,罗海波3

(1.国防科技大学气象海洋学院,江苏 南京 211101; 2.中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室,北京 100029; 3.中国人民解放军96833部队,湖南 怀化 418099)

厄尔尼诺; 东太平洋开始型; 中太平洋开始型; 赤道太平洋; 次表层海温异常循环; 动力因素

Linkage between two onset types of El Niño events and subsurface ocean temperature anomalies
XIA Fei1,LI Xin1,2*,YANG Minghao1,CHEN Xiong1,LUO Haibo3

(1.Institute of Meteorology & Oceanography,National University of Defense Technology,Nanjing211101,China; 2.State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics,Chinese Aca

DOI: 10.6043/j.issn.0438-0479.201911031

备注

通过资料分析,探究了东太平洋开始型(EP-onset)和中太平洋开始型(CP-onset)厄尔尼诺发生发展过程中赤道太平洋次表层海温异常(SOTA)的变化情况及其对风场的响应,并将两者进行对比,结果发现:EP-onset型的赤道西太平洋暖池SOTA与赤道中东太平洋的海表温度异常(SSTA)有很好的负相关性,而CP-onset型在爆发前的暖池SOTA与赤道中东太平洋SSTA没有显著相关性.EP-onset型在爆发前,赤道西太平洋暖池区域有较显著的暖水积聚,且其积聚时间较长,强度较强,位置偏西,其发生发展伴随着非常显著的SOTA冷暖循环; 而CP-onset型的发生发展没有显著的循环特征,看上去更多是独立事件.分析还表明:EP-onset型和CP-onset型厄尔尼诺在SSTA模态、风应力分布及温跃层结构等方面存在差异.EP-onset型在爆发前,赤道中西太平洋会出现大范围的东风异常,这种东风异常通过密度流、温跃层反馈及海气耦合等机制对其爆发起到关键作用; 而CP-onset型在爆发前,赤道地区风异常较小,赤道外尤其是热带中太平洋的西南风异常却较强劲,通过Ekman输送及海气耦合作用等机制对其爆发起到关键作用.

Through data analysis,we investigate variation of the equatorial Pacific subsurface ocean temperature anomaly(SOTA)and its response to the wind field during outbreak and development of the Eastern-Pacific onset(EP-onset)and the Central-Pacific onset(CP-onset)El Niño,and then compare the two parameters.The results show that:during the EP-onset El Niño,the equatorial western Pacific warm pool SOTA has a significantly negative relationship with the equatorial Pacific sea surface temperature anomaly(SSTA)in the central eastern Pacific,while before the outbreak of the CP-onset El Niño,the equatorial western Pacific warm pool SOTA is not significantly associated with the equatorial central eastern Pacific SSTA.Before the outbreak of the EP-onset El Niño,warm water accumulates in the equatorial western Pacific warm pool area,and the accumulation lasts for a longer time with a stronger intensity and a relatively western location.The outbreak and development of the EP-onset El Niño are accompanied by a very significant SOTA cold-warm cycle.However,the outbreak and development of the CP-onset El Niño have no significantly cyclic characteristics and seem to be more independent.The analysis also shows that there are differences between the EP-onset and the CP-onset El Niño in SSTA modes,wind stress distribution and thermocline structure.Before the outbreak of the EP-onset El Niño,a large range of eastern wind anomaly occurs in the central and western equatorial Pacific, and plays a key role in the outbreak of the EP-onset El Niño through the mechanisms of density flow,thermocline feedback and air-sea coupling.Before the outbreak of the CP-onset El Niño burst,there is smaller wind anomaly in the equatorial region,but the southwestern wind anomaly outside the tropical central Pacific is stronger,and plays a key role in the outbreak of the CP-onset El Niño through Ekman transport and air-sea coupling.