Monthly Climate Timeseries:

This mode describes low frequency variability of the Northern Hemisphere extratropics. A positive PNA is associated with in ceased heights over the inter-mountain region of the US and low heights in the SE and off the Aleutian islands. A positive PNA is often associated with an El Ni˜o and a negative one with a La Ni˜a.
Correlation of JFM 500mb height with the PNA index. Sign is such that a positive PNA is associated with
Time-series Plot:
Select this link to get a plot. Plot is taken from the Times-series Plotting and Analysis web-page.
Calculation Method:
CPC uses rotated principal components.
Time Interval: Monthly
Time Coverage: 1950 to present
Update Status: monthly

Get Data:
PNA index: Standard PSL Format (What is standard format?)
Data is from the NOAA CPC
  1. Please cite CPC