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

Full description

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.

See also the related metadata record.

Lineage

Progress Code: completed

Statement: The dates provided in temporal coverage are approximate only. See the links for the source data for further information about the quality of the original datasets.