Data: AO index

Annular Modes |

Indices of the Annular Modes (i.e., the AO and AAO)

  • The following indices are generated by projecting various anomaly fields onto the structure of the "AO", defined here as the leading EOF of SLP poleward of 20N based on all months Jan1958 to April1997. All units are arbitrary.

    AO_TREN_NCEP_Jan1899Current.ascii
    MONTHLY INDEX Jan1899 to current (June 2002). Found by projecting the AO pattern onto SLP anomalies back to Jan 1899. Index starts Jan 1899, ends June 2002. Index values 1899-Dec1957 are based on data described in Trenberth and Paolino (1980). Index values Jan1958 to current are from the NCEP/NCAR Reanalysis. (Reference: Thompson and Wallace 2000)

    AO_SATindex_JFM_Jan1851March1997.ascii MONTHLY INDEX BASED ON SAT DATA. January-March monthly-mean values from Jan1851 to March1997. The first column is the time axis in years (and fractions of years: i.e. 1958+0/3 would be Jan 1958, 1958+2/3 is March 1958, etc). The second column is the index values. In this case the index values are the expansion coefficient time series of the pattern of SAT anomalies associated with the AO. SAT data provided by P. D. Jones (Jones 1994) from the CRU. (Reference: Thompson and Wallace 2000)

  • The following indices are available via the NOAA CPC website:

    Indices of the annular modes (i.e., the Arctic Oscillation and its Southern Hemisphere counterpart) from the NOAA CPC.
    Includes historical indices/real time indices/forecasts of the annular modes/indices in daily and monthly formats/etc

    Source: Hyun-Kyung Kim Hyun-kyung.Kim@noaa.gov

    David W. J. Thompson davet@atmos.colostate.edu