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Monthly Multivariate ENSO Index (MEI)
Entry ID: NOAA_NWS_CPC_MEI

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Summary

Abstract: [Text Source: Klaus Wolter, http://www.esrl.noaa.gov/psd//people/klaus.wolter/MEI/
Refer to: Wolter and Timlin, 1993, 1998, http://www.esrl.noaa.gov/psd//people/klaus.wolter/MEI/#ref_wt1 ]

El Niño/Southern Oscillation (ENSO) is the most important coupled ocean-atmosphere phenomenon to cause global climate variability on interannual time scales. Here we attempt to monitor ENSO by basing the Multivariate ENSO Index (MEI) on the six main observed variables over the tropical Pacific. These six variables are: sea-level pressure (P), zonal (U) and meridional (V) components of the surface wind, sea surface temperature (S), surface air temperature (A), and total cloudiness fraction of the sky (C). These observations have been collected and published in COADS for many years. The MEI is computed separately for each of twelve sliding bi-monthly seasons (Dec/Jan, Jan/Feb,..., Nov/Dec). After spatially filtering the individual fields into clusters (Wolter, 1987), the MEI is calculated as the first unrotated Principal Component (PC) of all six observed fields combined. This is accomplished by normalizing the total variance of each field first, and then performing the extraction of the first PC on the co-variance matrix of the combined fields (Wolter and Timlin, 1993). In order to keep the MEI comparable, all seasonal values are standardized with respect to each season and to the 1950-93 reference period. The MEI is extended during the first week of the following month based on near-real time marine ship and buoy observations (courtesy of Diane Stokes at NCEP) summarized into COADS-compatible 2-degree monthly statistics at NOAA-ESRL PSD. Caution should be exercised when interpreting the MEI on a month-to-month basis, since the input data for updates are not as reliable as COADS, and the MEI has been developed mainly for research purposes. Negative values of the MEI represent the cold ENSO phase, a.k.a.La Niña, while positive MEI values represent the warm ENSO phase (El Niño).

See: http://www.esrl.noaa.gov/psd//people/klaus.wolter/MEI/

Related URL

Link: GET DATA
Description: Access to monthly MEI index data since 1950

Link: GET DATA
Description: Current MEI time series

Link: VIEW RELATED INFORMATION
Description: Access to additional MEI data, plots and documentation.

Geographic Coverage

N: 5.0 S: -5.0 E: -120.0 W: -170.0

Data Set Citation

Dataset Originator/Creator: NOAA/OAR/ESRL/PSD
Dataset Title: Multivariate ENSO Index (MEI)
Dataset Series Name: NOAA Indices and Forecasts
Dataset Release Date: ongoing
Dataset Release Place: Boulder, CO, USA
Dataset Publisher: NOAA/OAR/ESRL/PSD
Online Resource: http://www.esrl.noaa.gov/psd//people/klaus.wolter/MEI/

Temporal Coverage

Start Date: 1950-01-01

Location Keywords

OCEAN > PACIFIC OCEAN

Data Resolution
Temporal Resolution: monthly

Science Keywords

OCEANS >OCEAN TEMPERATURE >SEA SURFACE TEMPERATURE >SST [Definition]

CLIMATE INDICATORS >ATMOSPHERIC/OCEAN INDICATORS >TELECONNECTIONS >EL NINO SOUTHERN OSCILLATION (ENSO) >MULTIVARIATE ENSO INDEX [Definition]

ISO Topic Category

CLIMATOLOGY/METEOROLOGY/ATMOSPHERE

Keywords

MEI

Multivariate ENSO Index

climate index

climate indices

SST

ENSO

climate change

Data Set Progress

IN WORK

Originating Center

NOAA/NWS/CPC

Data Center

Physical Sciences Division, Earth System Research Laboratory, OAR, NOAA, U.S. Department of Commerce [Information]
Data Center URL: http://www.esrl.noaa.gov/psd/
Dataset ID: MEI Index

Data Center Personnel

Name: ESRL/PSD DATA INQUIRIES
Email: esrl.psd.data at noaa.gov

Distribution

Distribution_Media: online www
Distribution_Format: ascii
Fees: none

Personnel

KLAUS WOLTER
Role: TECHNICAL CONTACT
Email: Klaus.Wolter at noaa.gov

SCOTT A. RITZ
Role: DIF AUTHOR
Phone: 301-614-5126
Fax: 301-614-5268
Email: Scott.A.Ritz at nasa.gov
Contact Address:
NASA Goddard Space Flight Center
Global Change Master Directory
City: Greenbelt
Province or State: Maryland
Postal Code: 20771
Country: USA

Publications/References

http://www.amt-uk.org/publications.aspx

Creation and Review Dates

DIF Creation Date: 2013-02-17

Last DIF Revision Date: 2013-05-03

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