Jim Hurrell, Senior Scientist
NAO/NAM Climate Indices
Introduction to NAO Indices
Reference Information
To learn more about how the spatial structure and time series of the NAO are defined, please see Hurrell et al. (2003)
| Index | Description | Updated Thru | Next Update | Format |
| NAO Station Based (DJFM) | Winter (December through March) index of the NAO based on the difference of normalized
sea level pressure (SLP) between Lisbon, Portugal and Stykkisholmur/Reykjavik, Iceland since 1864. Detailed Description, Timeseries Plot | DJFM 2008 | June 2009 | HTML Table / ascii / Microsoft Excel File (.xls) |
| NAO Station Based (Monthly) | Monthly index of the NAO based on the difference of normalized sea level pressures (SLP) between Ponta Delgada, Azores and Stykkisholmur/Reykjavik, Iceland since 1865. | March 2003 | Unknown* | HTML Table |
| NAO Station Based (3 month seasons) | Seasonal (DJF,MAM,JJA,SON) indices of the NAO are based on the difference of normalized sea level pressure (SLP) between Ponta Delgada, Azores and Stykkisholmur/Reykjavik, Iceland since 1865. Detailed Description | May 2004 | Unknown* | HTML Table |
| NAO Station Based (Annual) | The annual index of the NAO is based on the difference of normalized sea level pressure (SLP) between Ponta Delgada, Azores and Stykkisholmur/Reykjavik, Iceland since 1865. Detailed Description | May 2004 | Unknown* | HTML Table |
| CPC NAO Projection Based (Daily) | The daily NAO index is constructed by projecting the daily (00Z) 500mb height anomalies over the Northern Hemsiphere onto the loading pattern of the NAO since 1950. Detailed Description | Today | Tomorrow | ascii (Last 120 days) / ascii (1950-Current) / Teleconnections Data Archive |
| CRU NAO Station Data (Monthly) | Sea level pressure (SLP) data from the Azores (1865-2002), Gibraltar (1821-2007), and Reykjavik, Iceland (1821-2007). | Dec. 2007 | Unknown | CRU NAO Data Updated CRU NAO Data |
| NAO PC Based (DJFM) | The principal component (PC) time series of the leading EOF of seasonal
(December through March) SLP anomalies over the Atlantic sector (20-80N, 90W-40E), available since 1899. Detailed Description, Timeseries Plot | DJFM 2008 | May 2009 | HTML Table |
| NAO PC Based (DJF) | The principal component (PC) time series of the leading EOF of DJF
(December through February) SLP anomalies over the Atlantic sector (20-80N, 90W-40E), available since 1899. Plot of Spatial Pattern, Timeseries | DJF 2008 | May 2009 | HTML Table |
| NAO PC Based (MAM) | The principal component (PC) time series of the leading EOF of MAM
(March through May) SLP anomalies over the Atlantic sector (20-80N, 90W-40E), available since 1899. Plot of Spatial Pattern, Timeseries | MAM 2007 | May 2009 | HTML Table |
| NAO PC Based (JJA) | The principal component (PC) time series of the leading EOF of JJA
(June through August) SLP anomalies over the Atlantic sector (20-80N, 90W-40E), available since 1899. Plot of Spatial Pattern, Timeseries | JJA 2007 | May 2009 | HTML Table |
| NAO PC Based (SON) | The principal component (PC) time series of the leading EOF of SON
(September through November) SLP anomalies over the Atlantic sector (20-80N, 90W-40E), available since 1899. Plot of Spatial Pattern, Timeseries | SON 2007 | May 2009 | HTML Table |
| NAO PC Based (Annual) | The principal component (PC) time series of the leading EOF of annual
SLP anomalies over the Atlantic sector (20-80N, 90W-40E), available since 1899. Plot of Spatial Pattern, Timeseries | 2007 | May 2009 | HTML Table |
| Northern Annular Mode (DJFM) |
The NAM (or Arctic Oscillation) is defined as the first EOF of NH (20-90N) winter SLP data. The normalized PC values are available since
1899.
Detailed Description, Plots | DJFM 2008 | May 2009 | HTML Table |
Reference Information
Correct reference for all NAO/NAM timeseries taken directly from this webpage:NAO Index Data provided by the Climate Analysis Section, NCAR, Boulder, USA, Hurrell (1995).
