ENSO循环海表温度演变多样性的客观分类  

Objective Classification of Sea Surface Temperature Evolution diversity of ENSO Cycle

作　　者：刘嘉锡 朱志伟[1] 卢睿 李娟[1] LIU Jiaxi;ZHU Zhiwei;LU Rui;LI Juan(Key Laboratory of Meteorological Disasters,Ministry of Education/International Joint Laboratory on Climate and Environmental Change/Collaborative Innovation Center for Meteorological Disaster Forecast and Assessment,Nanjing University of Information Science and Technology,Nanjing 210044,Jiangsu,China)

机构地区：[1]南京信息工程大学气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心,江苏南京210044

出　　处：《高原气象》2024年第6期1433-1447,共15页Plateau Meteorology

基　　金：国家自然科学基金基础科学中心项目(42088101)。

摘　　要：厄尔尼诺-南方涛动(El Nino-Southern Oscillation,ENSO)是热带太平洋最显著的年际气候变率模态,其海温异常(Sea Surface Temperature Anomalies,SSTA)的演变过程呈周期性和锁相性特征。本文从ENSO循环角度出发,使用K均值聚类法(K-Means Clustering Analysis,KMA)对1961-2021年ENSO的SSTA演变进行分类,得到ENSO循环的SSTA演变3类和5类两种客观分类结果。当分3类时,ENSO循环的SSTA基本演变特征分别为暖发展、暖衰减和冷持续过程;而分5类时,超强和普通暖事件发展、衰减过程在强度和纬向分布上的差异能够被进一步反映出来。为解释该差异,本文又引入结合主成分分析(Empirical Orthogonal Function,EOF)的KMA方法。通过将EOF主模态分为两大类,分别代表ENSO循环的纬向一致发展模态和纬向非对称发展模态,分离了ENSO循环中赤道太平洋SSTA纬向一致和纬向非对称发展过程。在此基础上,结合KMA聚类分析结果对不同类别的ENSO循环特征进行分析,发现纬向非对称发展模态叠加在纬向一致发展模态上,可最终导致ENSO的SSTA年循环纬向发展速度的不对称。对ENSO纬向一致和非对称演变模态进行回归重构,发现风、温跃层厚度异常可能是造成SSTA纬向非对称演变的关键。本文客观定义ENSO演变的不同类型,为ENSO多样性的气候动力学及其气候影响研究提供了一定参考。El Niño-Southern Oscillation(ENSO)is the most prominent interannual climate mode over the tropical Pacific,which is characterized by a periodic and phase-locked evolution of sea surface temperature anomalies(SSTA).From the perspective of ENSO cycle,this study objectively classified the SSTA evolution of ENSO from 1961 to 2021 into two results using K-means clustering method(KMA):3 or 5 types of ENSO cycle.When it is classified into 3 types,the basic characteristics of ENSO cycle are warm-developing,warm-decaying,and cold-persistence.When it is classified into 5 types,the discrepancies of intensity and zonal distribution of the development and decay processes between super-strong and normal events are highlighted.To further explain these discrepancies,this study employed a KMA considering the Principal Component Analysis(Empirical Orthogonal Function).Based on the two EOF leading modes which reflects the zonal symmetric and asymmetric development modes,the zonally symmetric and asymmetric development processes of the ENSO cycle are divided.Combined with the KMA clustering analysis,it is further found that zonally asymmetric development mode together with the zonally consistent development mode jointly lead to the zonal asymmetric development speed of ENSO cycle.Reconstruction of the zonally homogeneous and asymmetric evolution modes of ENSO reveals that wind and thermocline thickness anomalies may be key factors controlling the zonal asymmetric evolution of SSTA.This study objectively classified different types of ENSO evolution,providing reference for climate dynamics and impacts of ENSO diversity.

关 键 词：ENSO循环 K均值聚类 主成分分析 太平洋海温 

分 类 号：P47[天文地球—大气科学及气象学]