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GEFSv12 North Atlantic Oscillation Indices (NCEI Accession 0259492)

Published by NOAA National Centers for Environmental Information | National Oceanic and Atmospheric Administration, Department of Commerce | Metadata Last Checked: January 29, 2026 | Last Modified: 2022-11-09T00:00:00.000+00:00
The North Atlantic Oscillation (NAO) index characterizes the primary mode of atmospheric circulation variability over the North Atlantic region. This dataset provides NAO indices computed from the Global Ensemble Forecast System version 12 (GEFSv12) reanalysis and subseasonal reforecast datasets. These indices are defined from Empirical Orthogonal Function analysis of 500 millibar geopotential height fields in the region of 20-90N latitude, and 90W-40E longitude. For the GEFSv12 reanalysis, these indices are provided once daily for all dates from 2000-2019. For the GEFSv12 reforecasts, these indices are provided only for the subseasonal 35-day reforecasts, which are initialized once per week in the 2000-2019 period, starting from 2000-01-05.

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