Climate Data

NCEP-NCAR (R1): An Overview

NCEP-NCAR (R1) is the original reanalysis effort. It uses a frozen global state-of-the-art global data assimilation system (as of 11 January 1995). The original database was enhanced (additional, quality checked datasets) by NCAR's Data Support Section. Originally planned to span 1957-96 ("40-Year Reanalysis Project"), it was extended back to 1948 and continues to this day.

Key Strengths:

  • Global Data Set
  • Longest running reanalysis that uses rawindsonde data
  • Used in many publications so it can be used as a baseline reference for many computations

Key Limitations:

  • Antiquated (1994) data assimilation/model
  • Low spatial and temporal moisture variability over oceans (mainly model 'first guess' fields)
  • relatively poor Southern Hemisphere

Technical Notes

Kalnay et al (1996) provide a four class partitioning of the R1 output analyzed variables. Specifically:

  • Class A: Variables that are "strongly influenced" by observations. 
  • Class B: Variables where both observations and the model influence the output (e.g., humidity and surface temperature).
  • Class C: Variables created by the model and data assimilation schemes (e.g., clouds and precipitation).
  • Class D: Fixed climatological values.

Years of Record

1948/01 to 2013/01



Sub-daily | Daily | Monthly

Data Time Period Extended?

yes, data set is extended


Spatial Resolution

2.5°x2.5°; 3 hPA top

Ocean or Land


Missing Data Flag

spatially complete

Data Assimilation Method

Model Resolution used to create reanlaysis

T62 - 28 levels

Model Vintage (reanalysis)


Input Data

Rawindsondes; ICOADS, station data, aircraft, satellite retrievals

Earth system components and main variables

Data Access: Please Cite data sources, following the data providers' instructions.

NCAR Research Data Archive
NCAR Cas Data Catalog derived mass, moisture, energy budgets

Usage Restrictions

varies by download site
  1. Kalnay et al.,The NCEP/NCAR 40-year reanalysis project, <i>Bull. Amer. Meteor. Soc.,</i> 77, 437-470, 1996.
  2. Kistler, R., et al, 2001: The NCEP-NCAR 50-Year Reanalysis: Monthly Means CD-ROM and Documentation. Bull. Amer. Meteor. Soc., 82, 247-267

Key Figures

Click the thumbnails to view larger sizes



Climate Data Guide Image: Taylor Diagram NCEP NCAR Reanalysis Taylor Diagram NCEP NCAR Reanalysis

Cite this page

National Center for Atmospheric Research Staff (Eds). Last modified 20 Aug 2013. "The Climate Data Guide: NCEP-NCAR (R1): An Overview." Retrieved from

Acknowledgement of any material taken from this page is appreciated. On behalf of experts who have contributed data, advice, and/or figures, please cite their work as well.