The variability of the Southern Annular Mode and associations with high latitude weather and climate

Metadata record for data from ASAC Project 2540
See the link below for public details on this project.

The hemispheric and regional atmospheric circulation influences the Southern Ocean in many and profound ways, including intense air-sea fluxes of momentum, energy, fresh water and dissolved gases. The Southern Ocean ventilates a large fraction of the world ocean and hence these influences are spread globally. We use the NCEP-2 reanalysis dataset to diagnose aspects of the large-scale atmospheric structure and variability and explore how these impact on the Southern Ocean. We discuss how the 'Southern Annular Mode' and the 'Pacific-South American' pattern influence the Southern Ocean, particularly in the Eastern Pacific. We review the importance of atmospheric eddies in Southern Ocean climate, and the role they play in transport of mechanical energy into the ocean. The fluxes of fresh water across the air-sea boundary influence strongly the processes of water mass formation. It is shown that climatological precipitation exceeds evaporation over most of the Southern Ocean. When averaged over the ocean from 50S to the Antarctic coast the annual mean excess is 0.8 mm per day. The magnitude of the flux displays only a small measure of seasonality, and it's largest value of 0.92 mm per day occurs in summer.

In this project, the NCEP reanalysis datasets were sourced from: NOAA/National Weather Service, National Centers for Environmental Prediction (5200 Auth Road, Camp Springs, Maryland, 20746 USA).

Two NCEP reanalysis data sets were used in this study. The first was NCEP/NCAR, with 6-hourly data available from 1958 (see the URL provided below for further information). The second was the NCEP/DOE set, with 6-hourly data available from 1979 (see the URL provided below for further information).

The ERA-40 is a 're-analysis' of meteorological observations from September 1957 to August 2002 produced by the European Centre for Medium-Range Weather Forecasts (ECMWF) in collaboration with many institutions.

The HadISST1.1 data set was the first version of the global sea-ice and sea surface temperature dataset produced by the Hadley Centre at the United Kingdom Meteorological Office.

In this project the following model/analysis was applied:

Application of The University of Melbourne cyclone tracking scheme (Simmonds et al., 2003, Monthly Weather Review, 131, 272-288) and a broad range of statistical tests. Brief details are provided in the Summary. See the link for the pdf document for more detailed information.

These complex statistical analyses were run over the entire length of the project (2004/05 - 2006/07). They were run on Dell PCs in the School of Earth Sciences, The University of Melbourne.

ASAC项目2540数据集元数据记录
点击下方链接查看该项目的公开详情。

半球与区域大气环流以多重深刻途径影响南大洋，涵盖动量、能量、淡水与溶解气体的强海气通量。南大洋为全球多数海洋提供通风作用，因此此类影响可传播至全球范围。我们采用NCEP-2再分析数据集（NCEP-2 reanalysis dataset）对大尺度大气结构与变异性的多个维度进行诊断，并探究其对南大洋的影响。我们探讨了南环状模态（Southern Annular Mode）与太平洋-南美型（Pacific-South American pattern）对南大洋的影响机制，尤其聚焦东太平洋海域。我们综述了大气涡旋在南大洋气候系统中的重要性，及其在将机械能输送至海洋过程中所扮演的角色。海气界面的淡水通量对水团形成过程具有显著调控作用。研究表明，南大洋绝大多数海域的气候态降水量大于蒸发量。若对南纬50度至南极海岸的海域进行区域平均，年平均淡水盈余为0.8毫米/日。该通量的强度仅表现出微弱的季节性变化，其峰值达0.92毫米/日，出现在夏季。

本项目所用的NCEP再分析数据集源自：美国国家海洋和大气管理局（NOAA）/国家气象局、美国国家环境预报中心（地址：美国马里兰州坎普斯普林斯市Auth路5200号，邮编20746）。

本研究共使用两套NCEP再分析数据集：第一套为NCEP/NCAR再分析数据集，其6小时分辨率数据起始于1958年（详细信息请点击下方链接查阅）；第二套为NCEP/DOE再分析数据集，其6小时分辨率数据起始于1979年（详细信息请点击下方链接查阅）。

ERA-40是欧洲中期天气预报中心（ECMWF）联合多家科研机构，针对1957年9月至2002年8月的气象观测数据开展的再分析项目。

HadISST1.1数据集是英国气象局哈德利中心推出的首套全球海冰与海表温度数据集。

本项目采用了以下模型与分析方法：
采用墨尔本大学气旋追踪方案（Simmonds等，2003年，《每月天气评论》，第131卷，第272-288页）以及多组统计检验方法。简要说明已收录于项目摘要，详细信息请点击链接查阅对应PDF文档。

本项目全周期（2004/05年度至2006/07年度）均运行了上述复杂统计分析程序，计算设备为墨尔本大学地球科学学院的戴尔（Dell）个人计算机。