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Dataset NCEP Reanalysis Tutorial
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  • NCEP Reanalysis 1
  • NCEP Reanlysis 2

The NCEP/NCAR Reanalysis 1 project is using a state-of-the-art analysis/forecast system to perform data assimilation using past data from 1948 to the present. A large subset of this data is available from PSD in its original 4 times daily format and as daily averages. However, the data from 1948-1957 is a little different, in the regular (non-Gaussian) gridded data. That data was done at 8 times daily in the model, because the inputs available in that era were available at 3Z, 9Z, 15Z, and 21Z, whereas the 4x daily data has been available at 0Z, 6Z, 12Z, and 18Z. These latter times were forecasted and the combined result for this early era is 8x daily. The local ingestion process took only the 0Z, 6Z, 12Z, and 18Z forecasted values, and thus only those were used to make the daily time series and monthly means here.

Acknowledgement
  • For dataset source, please cite: Kalnay et al.,The NCEP/NCAR 40-year reanalysis project, Bull. Amer. Meteor. Soc., 77, 437-470, 1996.
  • Please note: If you acquire NCEP Reanalysis data products from PSD, we ask that you acknowledge us in your use of the data. This may be done by including text such asNCEP Reanalysis data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at https://www.esrl.noaa.gov/psd/ in any documents or publications using these data. We would also appreciate receiving a copy of the relevant publications. This will help PSD to justify keeping the NCEP Reanalysis data set freely available online in the future.
Data Contributors
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Data details
Pressure level data
Spatial resolution 0.25 X 0.25 (degree)
Temporal resolution Daily, Monthly
Levels 17 Pressure levels(1000, 925, 850, 700, 600, 500, 400, 300, 250, 200, 150, 100, 70, 50, 30, 20, 10) (mb)
Some variables have less: omega (to 100mb) and Humidities (to 300mb)
Parameters
  • Air temperature(air)
  • Geopotential height(hgt)
  • Relative humidity(rhum)
  • Specific humidity(shum)
  • Omega(omega)
  • U-wind(uwnd)
  • V-Wind (vwnd)
Surface data
Spatial resolution 0.25 X 0.25 (degree)
Temporal resolution Daily, Monthly
Levels Surface, Sea
Parameters
  • Sea level pressure(slp)
  • Pressure(pres.sfc)
  • Land-sea mask(land)
Surface flux data
Spatial resolution T62 Gaussian grid with 192x94 points(88.542N-88.542S, 0E-358.125E)
Temporal resolution Daily, Monthly
Levels Surface, 2m, 10m
Parameters
  • Air Temperature 2m (air.2m)
  • Maximum temperature at 2m(tmax.2m)
  • Minimum temperature at 2m (tmin.2m)
  • Specific humidity at 2 meter(shum.2m)
  • U-wind at 10 m(uwnd.10m)
  • V-wind at 10 m(vwnd.10m)
  • Downward longwave radiation flux(dlwrf.sfc)
  • Downward solar radiation flux(dswrf.sfc)
  • Latent heat net flux(lhtfl.sfc)
  • Precipitation rate(prate.sfc)
  • Sensible heat net flux(shtfl.sfc)
  • Upward longwave radiation flux(ulwrf.sfc)
  • Upward solar radiation flux(uswrf.sfc)
  • Ground Heat Flux(gflux.sfc) (monthly only)
  • Net Longwave Radiation Flux(nlwrs.sfc) (monthly only)
  • Net Shortwave Radiation Flux(nswrs.sfc) (monthly only)
  • Sea level pressure(slp)
Other flux data
Spatial resolution T62 Gaussian grid with 192x94 points(88.542N-88.542S, 0E-358.125E)
Temporal resolution Daily, Monthly
Levels Nominal top of atmosphere
Parameters
  • Downward solar radiation flux(dswrf.ntat)
  • Upward longwave radiation flux(ulwrf.ntat)
  • Upward solar radiation flux(uswrf.ntat)
Reference
  1. Kalnay et al.,The NCEP/NCAR 40-year reanalysis project, Bull. Amer. Meteor. Soc., 77, 437-470, 1996
  2. NCEP/NCAR Reanalysis 1: Summary (https://www.esrl.noaa.gov/psd/data/gridded/data.ncep.reanalysis.html)