North Pacific (NP) Index by Trenberth and Hurrell; monthly and winter

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North Pacific (NP) Index  by Trenberth and Hurrell; monthly and winter
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The North Pacific Index (NP index or NPI) is the area-weighted sea level pressure over the region 30°N-65°N, 160°E-140°W. The NP index is defined to measure interannual to decadal variations in the atmospheric circulation. The dominant atmosphere-ocean relation in the North Pacific is one where atmospheric changes lead changes in sea surface temperatures by one to two months. However, strong ties exist with events in the tropical Pacific, with changes in tropical Pacific SSTs leading SSTs in the north Pacific by three months.

Key Strengths

Key Strengths

Long timeseries running from 1899 to present.

Depicts changes in the intensity of the Aleutian low, and is highly correlated with the 500hPa PNA index from Wallace and Gutzler (1981).

Official North Pacific Index cited in Trenberth & Hurrell (1994).

Please cite data sources, following the data providers' instructions
Suggested Data Citation
None
Dataset DOIs
None
Hosted Climate Index Files
  1. Details
    Missing Value: -999.00 Units: hPa Start Date: Updated through:
    Citation

    NP Index Data provided by the Climate Analysis Section, NCAR, Boulder, USA, Trenberth and Hurrell (1994). Updated Regularly. Accessed DD Month YYYY [list date you accessed the data].

    Notes
  2. Details
    Missing Value: -999.00 Units: hPa Start Date: Updated through:
    Citation

    NP Index Data provided by the Climate Analysis Section, NCAR, Boulder, USA, Trenberth and Hurrell (1994). Updated Regularly. Accessed DD Month YYYY [list date you accessed the data].

    Notes
  3. Details
    Missing Value: -999.00 Units: hPa Start Date: Updated through:
    Citation

    NP Index Data provided by the Climate Analysis Section, NCAR, Boulder, USA, Trenberth and Hurrell (1994). Updated Regularly. Accessed DD Month YYYY [list date you accessed the data].

    Notes
Data Access
None
Usage Restrictions
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Key Figures

NDJFM North Pacific Index.

NDJFM North Pacific Index (anomalies) standardized in bar chart form. The smooth black line is a weighted (1-3-5-6-5-3-1) running average. (Climate Data Guide; A. Phillips)

Other Information

Earth system components and main variables

Years of record
to
Data time period extended
Yes, data set is extended
Timestep
Monthly, Seasonal
Formats:
Input Data

SLP from NCAR (Trenberth/Palino) SLP

Vertical Levels:
None
Missing Data Flag
None
Ocean or Land
None
Spatial Resolution
None
Model Resolution (reanalysis)
None
Data Assimilation Method
None
Model Vintage (reanalysis)
None