Links between Large-Scale Modes of Climate Variability and Synoptic Weather Patterns in the Southern Indian Ocean
Links between Large-Scale Modes of Climate Variability and Synoptic Weather Patterns in the Southern Indian Ocean
复制标题
南印度洋气候变率大尺度模式与天气模式之间的联系
DOI：
10.1175/jcli-d-20-0297.1
复制
发表时间：
2020
影响因子：
4.9
通讯作者：
M. Curran
中科院分区：
文献类型：
--
作者：
Danielle G. Udy;T. Vance;A. Kiem;N. Holbrook;M. Curran
南印度洋（SIO）的天气系统驱动南极洲东部和澳大利亚南部的天气尺度降水变化。加深对这些动态联系的理解有助于从气候代用记录中诊断长期气候变化，并为区域天气和气候预报提供信息。利用自组织图（SOM）将1979年1月至2018年10月SIO（30°-75 ° S，40°-180 ° E）逐日500 hPa高度场（z500; ERA-Interim）异常分为9种区域天气类型。所代表的图形异常包括四个纬向异常、三个纬向-纬向混合异常、一个纬向异常和一个过渡节点异常。南环波节的频率与南环波模的位相关系有限，尤其是在9 - 11月。纬向和混合模式，但强烈和显着相关SAM，虽然区域的天气表示SAM+条件是不纬向对称，并表示由三个独立的节点。我们建议考虑如何不同的天气条件变化的大气代表SAM+在任何给定的季节在SIO。这些不同类型的SAM+意味着半球指数无法捕捉主要由天气变化而不是SAM的绝对极性驱动的地面天气条件的区域变化。
Weather systems in the southern Indian Ocean (SIO) drive synoptic-scale precipitation variability in East Antarctica and southern Australia. Improved understanding of these dynamical linkages is beneficial to diagnose long-term climate changes from climate proxy records as well as informing regional weather and climate forecasts. Self-organizing maps (SOMs) are used to group daily 500-hPa geopotential height (z500; ERA-Interim) anomalies into nine regional synoptic types based on their dominant patterns over the SIO (30°–75°S, 40°–180°E) from January 1979 to October 2018. The pattern anomalies represented include four meridional, three mixed meridional–zonal, one zonal, and one transitional node. The frequency of the meridional nodes shows limited association with the phase of the southern annular mode (SAM), especially during September–November. The zonal and mixed patterns were nevertheless strongly and significantly correlated with SAM, although the regional synoptic representation of SAM+ conditions was not zonally symmetric and was represented by three separate nodes. We recommend consideration of how different synoptic conditions vary the atmospheric representation of SAM+ in any given season in the SIO. These different types of SAM+ mean a hemispheric index fails to capture the regional variability in surface weather conditions that is primarily driven by the synoptic variability rather than the absolute polarity of the SAM.