We have transitioned the data files from netCDF3 to netCDF4-classic format. As a result, the files are compressed instead of being packed with a scale and offset. As with any netCDF4 file, the user interface will perform the uncompression. We expect the files to be read faster, depending on the application you are using. Please let us know if you run into any issues.

20th Century Reanalysis

Plot shows the NAO pattern with the anomalous 850mb zonal wind dipole over the eastern NH Atlantic ocean.

Options to produce plot are using the Monthly/seasonal 20th Century Plotting page: Google Earth

  • variable=zonal wind
  • level=850mb
  • January
  • use timeseries
  • NAO
  • standardized values greater than 1 sigma