Spatial Patterns of the Tropical Meridional Circulation: Drivers and Teleconnections
Spatial Patterns of the Tropical Meridional Circulation: Drivers and Teleconnections
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DOI：
10.1029/2021jd035531
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发表时间：
2022-01-27
影响因子：
4.4
通讯作者：
Tziperman, Eli
中科院分区：
文献类型：
--
作者：
Galanti, Eli;Raiter, Dana;Tziperman, Eli
大尺度Hadley环流是全球热湿输送的关键要素。它传统上被定义为热带地区纬向平均的纬向环流，但被证明有很强的纵向依赖性，如在三维大气流分解成空间依赖的纬向和纬向环流。最近的研究提供了一个有用的分析区域加强/减弱的分解环流，但不是它的模式。在这里，我们研究的年际变化的纵向依赖纬向环流（LMC），重点是其空间格局。我们使用层次聚类来客观地确定LMC年际变率的四个主要模态，并应用拉格朗日气团跟踪方法来揭示全环流模式。虽然厄尔尼诺和拉尼娜现象被发现，在以前的研究中，发挥作用，在设置这些模式，我们发现的模式是不是唯一的特点是标准的厄尔尼诺南方涛动（ENSO）指数（Nino3.4或南方涛动指数）。相反，ENSO风味（即，东太平洋和中太平洋）对LMC的影响不同。最突出的年际变化的LMC是一个东西移动。还确定了纬度和经度的垂直变化以及收缩/扩张。多元线性回归分析表明，虽然很大一部分的LMC方差解释海表温度，马登-朱利安振荡作出了不可忽视的独立贡献。聚类模式也被用来研究远程降水和地面气温的遥相关。
The large-scale Hadley circulation is a key element in the global heat and moisture transport. It is traditionally defined as the zonally averaged meridional circulation in the tropics, but was shown to have a strong longitudinal dependence, as seen in a decomposition of the three-dimensional atmospheric flow into spatially dependent meridional and zonal circulations. Recent studies provided a useful analysis of the regional strengthening/weakening of the decomposed circulation but not its patterns. Here, we study the interannual variability of the longitudinally dependent meridional circulation (LMC), with a focus on its spatial patterns. We use hierarchical clustering to objectively determine the four main modes of the LMC interannual variability, and apply a Lagrangian air parcel tracking method to reveal the full circulation patterns. While El Nino and La Nina are found, as in previous studies, to play a role in setting these patterns, we find the patterns are not uniquely characterized by standard El Nino-Southern Oscillation (ENSO) indices (Nino3.4 or Southern Oscillation Index). Instead, ENSO flavors (i.e., East Pacific vs. Central Pacific) have different effects on the LMC. The most prominent interannual variability of the LMC is an east-west shift. Latitudinal shifts, as well as contraction/expansion in both latitude and longitude are also identified. Multiple linear regression analysis shows that while a large fraction of the LMC variance is explained by Sea Surface Temperature, the Madden-Julian Oscillation makes a nonnegligible independent contribution. The clustering patterns are also used to study the remote precipitation and surface air temperature teleconnections.