论文部分内容阅读
利用1980～2010年月平均Hadley中心海表温度、美国全球海洋资料同化系统(GODAS)海洋温度和NCEP/NCAR大气环流再分析资料,通过对2个海洋要素(海表温度SST、上层热含量HC)和5个大气要素(海平面气压SLP、850hPa风场、200hPa速度势和对外长波辐射OLR)的多变量经验正交函数展开(multivariateEOF,简称MV-EOF)探讨了热带太平洋的主要海气耦合特征。结果表明,MV-EOF分析的前两个耦合模态分别很好地对应了传统型ElNio和ElNio Modoki的海气耦合特征:传统型ElNio期间,伴随着赤道中东太平洋SST的异常增温,HC、SLP、200hPa速度势等要素总体呈东西反相的“跷跷板”变化,低层850hPa赤道中太平洋出现较强西风距平,西北太平洋上空为反气旋性异常环流;ElNio Modoki期间,SST持续增温和HC正异常中心均显著西移至中太平洋,低层SLP和高空200hPa速度势均呈现纬向三极型异常分布,低层异常强西风向西移至暖池东部,西北太平洋上空呈现气旋性异常环流。两类ElNio的海气耦合特征存在显著差异,较优的ElNio指数应不仅可以客观描述和区分ElNio现象本身,更要紧密联系两类事件所产生的大气响应。以往定量表征ElNio年际变化的指标大多立足于SST或SLP,本文选取HC作为研究指标,定义了一组新的ElNio指数HCEI和HCEMI。较以往基于SST的ElNio指数,HCEI和HCEMI不仅能更清楚地表征和区分两类ElNio(如1993年的传统型ElNio和2006年的ElNio Modoki),而且能更好地反映和区分两类ElNio与大气间的海气耦合特征,为ElNio的监测和短期气候预测工作提供了一个新工具。
Based on the monthly mean sea surface temperature of Hadley Center from 1980 to 2010, the ocean temperature of the United States Global Oceanographic Data Assimilation System (GODAS) and the NCEP / NCAR atmospheric circulation reanalysis data, two ocean elements (SST, HC ) And multivariate empirical orthogonal function expansion (multivariateEOF, referred to as MV-EOF) of five atmospheric elements (sea level pressure SLP, 850hPa wind field, 200hPa velocity potential and external longwave radiation) were used to discuss the main ocean-atmosphere coupling feature. The results show that the first two coupled modes of the MV-EOF analysis correspond well to the ocean-atmosphere coupling characteristics of the traditional El Niño and El Ni o Modoki, respectively. During the traditional El Niño period, with the equatorial central-eastern Pacific SST Abnormal warming, HC, SLP, 200hPa velocity potential and other elements of the overall reversal of “seesaw” changes, the lower 850hPa Equatorial Pacific strong westerly anomalies, the Pacific Northwest Pacific anti-cyclonic anomalous circulation; ElNi During the Modoki period, both SST and HC positive anomalies migrated westward to the mid-Pacific Ocean. The velocities of low-level SLP and high-altitude 200 hPa showed anomalous zonal trending tripole anomalies. The anomalously strong westerly anomalies in the lower reaches shifted to the east of the warm pool, Cyclone anomalous circulation over the western North Pacific. The two types of El Ni o have significant differences in the characteristics of sea-air coupling, and the better El Ni o index should not only objectively describe and distinguish the El Ni o phenomenon itself, but also relate closely to the atmospheric responses generated by both types of events. In the past, most of the indicators that characterize the interannual variation of El Niño were based on SST or SLP. In this paper, HC was chosen as the research index and a new set of El Ni o indices HCEI and HCEMI were defined. Compared with the El Niño index based on SST, HCEI and HCEMI can not only characterize and distinguish two types of El Ni o more clearly (such as the traditional El Ni o in 1993 and El Ni o Modoki in 2006), but also better Reflects and distinguishes the coupling characteristics between two types of El Niño and the atmosphere, providing a new tool for the monitoring of El Ni o and short-term climate prediction.