Arctic Oscillation (AO) Index Data
Entry ID: JISAO_ARCTIC_AO

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Summary
Abstract: The University of Washington Joint Institute for the Study of the
Atmosphere and Ocean (JISAO) offers an Arctic Oscillation (AO) Index
dataset. The Arctic Oscillation (AO) is defined as the leading EOF of
Northern Hemisphere sea-level pressure anomalies poleward of 20N,
weighted by area (Thompson and Wallace, 1998).

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 January 1958 to April
1997. All units are arbitrary.

&http://ao.atmos.colostate.edu//Data/AO_TREN_NCEP_Jan1899Current.ascii&
AO_TREN_NCEP_Jan1899Current.ascii MONTHLY INDEX
January 1899 to present. Found by projecting the AO pattern onto SLP
anomalies back to Jan 1899. Index starts Jan 1899, ends June
2002. Index values 1899-December 1957 are based on data described in
Trenberth and Paolino (1980). Index values January 1958 to current are
from the NCEP/NCAR Reanalysis. (Reference: Thompson and Wallace 2000)

&http://ao.atmos.colostate.edu//Data/AO_SATindex_JFM_Jan1851March1997.ascii&
AO_SATindex_JFM_Jan1851March1997.ascii MONTHLY INDEX BASED ON SAT
DATA.
January-March monthly-mean values from January 1851 to March 1997. 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)

Additional AO Index data are available from:
&http://www.atmos.colostate.edu/ao/Data/ao_index.html&

and

&http://jisao.washington.edu/data/aots/&

Related URL
Link: GET DATA
Description: Access to AO Index documentation, graphs and data from 1899. Data
includes monthly means and seasonal (JFM) means.


Link: GET DATA
Description: Monthly AO Indices from January 1899 to present based on data
described in Trenberth and Paolino (1980).


Link: GET DATA
Description: Monthly AO Indices from January 1851 based on SAT data provided by
P. D. Jones (Jones 1994) from the CRU.


Geographic Coverage
 N: 90.0 S: 75.0  E: 180.0  W: -180.0

Data Set Citation
Dataset Originator/Creator: David W. J. Thompson, John. M. Wallace,
Dataset Title: Arctic Oscillation (AO) Index Data
Dataset Release Place: Seattle, Washington, USA
Dataset Publisher: University of Washington Department of Atmospheric Sciences


Temporal Coverage
Start Date: 1851-01-01


Location Keywords
GEOGRAPHIC REGION > ARCTIC
GEOGRAPHIC REGION > NORTHERN HEMISPHERE
GEOGRAPHIC REGION > POLAR


Science Keywords
ATMOSPHERE >ATMOSPHERIC PRESSURE >OSCILLATIONS    [Definition]
ATMOSPHERE >ATMOSPHERIC PRESSURE >PRESSURE ANOMALIES    [Definition]
ATMOSPHERE >ATMOSPHERIC PRESSURE >SEA LEVEL PRESSURE    [Definition]
CLIMATE INDICATORS >ATMOSPHERIC/OCEAN INDICATORS >TELECONNECTIONS >ARCTIC OSCILLATION >AO    [Definition]


ISO Topic Category
CLIMATOLOGY/METEOROLOGY/ATMOSPHERE


Use Constraints
Please cite the dataset originator if you use this data.


Keywords
Arctic Oscillation
AO
Northern Hemisphere Annular Mode
climate index
climate indices
climate change


Data Set Progress
IN WORK


Data Center
Joint Institute for the Study of the Atmosphere and Ocean, Department of Atmospheric Sciences, University of Washington    [Information]
Data Center URL: http://www.jisao.washington.edu/

Data Center Personnel
Name: TODD MITCHELL
Email: mitchell at atmos.washington.edu



Distribution
Distribution_Media: Online (FTP)
Distribution_Format: ASCII
Fees: None


Personnel
DAVID W.J. THOMPSON
Role: INVESTIGATOR
Email: davet at atmos.colostate.edu
Contact Address:
Department of Atmospheric Sciences
Colorado State University
City: Fort Collins
Province or State: CO
Postal Code: 80523
Country: USA


Publications/References
References:
David W. J. Thompson and John. M. Wallace, 1998: The Arctic
Oscillation signature in the wintertime geopotential height and
temperature fields. Geophys. Res. Lett., 25, No. 9, 1297-1300.

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., J. M. Wallace, and G. C. Hegerl, 2000: Annular
modes in the extratropical circulation. Part II: Trends. J. Climate,
13, 1018-1036.

For additional publications and links to abstracts and the above
papers, see:
http://www.atmos.colostate.edu/ao/ResPapers/index.html

Creation and Review Dates
DIF Creation Date: 1999-07-27
Last DIF Revision Date: 2009-04-13

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