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Antarctic Oscillation (AO) Time Series Data since 1948 from JISAO

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Abstract: The Antarctic Oscillation (AAO) is the dominant pattern of non-seasonal tropospheric circulation variations south of 30S, and it is characterized by pressure anomalies of one sign centered in the Antarctic and anomalies of the opposite sign centered about 40-50S. The AAO is also referred to as the Southern Annular Mode (SAM).

The AAO is defined as the leading principal component (PC) of 850 hPa geopotential height anomalies south of 30S (Thompson and Wallace 2000). For more information on the construction and analyses of this data, see:
Related URL
Description: Access to AAO documentation, graphs, and data.

Geographic Coverage
Spatial coordinates   
  N: -30.0   S: -90.0   E: 180.0   W: -180.0
Min Altitude: 0 MB Max Altitude: 850 MB

Data Set Citation
Dataset Originator/Creator: T. Mitchell
Dataset Title: Antarctic Oscillation (AO) Time Series
Dataset Release Date: 2002
Dataset Release Place: Seattle, WA
Dataset Publisher: JISAO, University of Washington
Online Resource:
Temporal Coverage
Start Date: 1948-01-01
Data Resolution
Temporal Resolution: monthly mean
Temporal Resolution Range: Monthly - < Annual
Data Set Progress
Originating Center
Distribution Media: online www
Distribution Format: ascii
Fees: none
Email: mitchell at
Thompson, D. W. J., and J. M. Wallace, 2000: Annular modes in the extratropical circulation. Part I: Month-to-month variability. J. Climate, 13, 1000-1016.

Thompson, D. W. J., and S. Solomon, 2002: Interpretation of Recent Southern Hemisphere Climate Change. Science, 296, 895-899.
Extended Metadata Properties
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Creation and Review Dates
DIF Creation Date: 2003-02-10
Last DIF Revision Date: 2017-08-23