Last modified 2017/11/12.

Last modified 2017/12/05.

Figure in PDF Last modified 2017/12/05.
In the United States

Data source: NCEP/NCAR Reanalysis Monthly Means

Citation: Kalnay et al.,The NCEP/NCAR 40-year reanalysis project, Bull. Amer. Meteor. Soc., 77, 437-470, 1996.

Acknowledgement: NCEP Reanalysis Derived data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at