Title

Hurrell North Atlantic Ocscillation (NAO) index (PC-based)

Date (Revision)

2021-09-28

Date (Publication)

2003-01-01

Citation identifier

b2fd35f3-2347-4957-af80-961519d6c593

Abstract

The principal component (PC)-based indices of the North Atlantic Oscillation (NAO) are the time series of the leading Empirical Orthogonal Function (EOF) of SLP anomalies over the Atlantic sector, 20°-80°N, 90°W-40°E. These indices are used to measure the NAO throughout the year, tracking the seasonal movements of the Icelandic low and Azores high. These movements are illustrated in the Figures on this page. Positive values of the NAO index are typically associated with stronger-than-average westerlies over the middle latitudes, more intense weather systems over the North Atlantic and wetter/milder weather over western Europe.

Credit

National Center for Atmospheric Research (USA)

Point of contact

Organisation name	Individual name	Electronic mail address	Role
National Center for Atmospheric Research (NCAR)			Author
National Center for Atmospheric Research (NCAR)			Publisher

Thèmes Sextant

• /Physical Environment/Hydrodynamics/Water Column

GEMET - INSPIRE themes, version 1.0

• Oceanographic geographical features

Mission Atlantic - Resources

• Data

Mission Atlantic - Case Studies

• Norwegian Sea

• Celtic Seas

Mission Atlantic - BODC Parameters

• /Physical oceanography/Water column temperature and salinity

Mission Atlantic - Data type (DMP)

• Modelling data

Mission Atlantic - Work Package

• WP5 Assessing state, drivers and tipping points

Use limitation

CC-BY (Creative Commons - Attribution)

Spatial representation type

Grid

Language

English

Character set

UTF8

Topic category

• Oceans

Distribution format

Name	Version
XYZ Ascii

OnLine resource

Protocol	Linkage	Name
WWW:LINK	https://climatedataguide.ucar.edu/climate-data/hurrell-north-atlantic-oscillation-nao-index-pc-based

Hierarchy level

Dataset

Statement

The PC-based NAO indices produced by NCAR's Climate Analysis Section are based on Hurrell (2003), cited below. They are currently offered as ascii text files for winter, monthly, seasonal, and annual values. As is the nature of PC-based indices, every time additional data is used to compute the EOF the individual PC values will likely change. It is thus recommended that one downloads an entire climate index each time they wish to update their holdings.

The NCAR Sea Level Pressure dataset is used for the calculation of the various NAO PC-based indices.

Metadata

File identifier

b2fd35f3-2347-4957-af80-961519d6c593

Metadata language

English

Character set

UTF8

Hierarchy level

Dataset

Date stamp

2023-10-01T16:43:37.552Z

Metadata standard name

ISO 19115:2003/19139 - SEXTANT

Metadata standard version

1.0

Metadata author

Organisation name	Individual name	Electronic mail address	Role
Ifremer	Sextant	sextant@ifremer.fr	Local service desk