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NCEP/NCAR Reanalysis Monthly Means and Other Derived Variables: Pressure Lelve

One-Line Description:

  • NCEP/NCAR Reanalysis Monthly Means and Other Derived Variables.

Temporal Coverage:

  • Daily and Monthly Values for 1948/01 - present.
  • Long term monthly means, derived from data for years 1968 - 1996.

Spatial Coverage:

  • 2.5 degree latitude x 2.5 degree longitude global grid (144x73).
  • 90N - 90S, 0E - 357.5E

Levels:

  • 17 pressure levels (hPa): 1000, 925, 850, 700, 600, 500, 400, 300, 250, 200, 150, 100, 70, 50, 30, 20, 10
  • some variables not defined at all levels

Update Schedule:

  • Monthly

Download/Plot Data:

Variable Statistic Level Download File Create Plot/Subset
Air Temperature Monthly Mean Surface air.mon.mean.nc plot
Air Temperature Monthly Long Term Mean Surface air.mon.ltm.nc plot
Air temperature air degC mon mean,ltm,daily ltm,
      diurnal cycle (4 different months)
      1st 2 eofs NH, calculated
      separately for each level
Geopotential height hgt m mon mean,ltm,daily ltm
      diurnal cycle (4 different months)
      1st 2 eofs NH, calculated
      separately for each level
Relative humidity rhum % mon mean,ltm
Specific humidity shum g/kg mon mean,ltm,daily ltm
Omega (vertical velocity) omega Pascal/s mon mean,ltm
U-wind uwnd m/s mon mean,ltm,daily ltm,
      1st 2 eofs NH, calculated
      separately for each level
V-wind vwnd m/s mon mean,ltm
Land-sea mask (time invariant) * lsmask (0 or 1) none
Derived variables include: File Units Statistics Available
Potential Temperature pottmp K mon mean,ltm * recalculated using new corrected NCEP data from 1997.
Static Stability stat   mon mean,ltm,inter,intra
Zonal Heat Flux ut K*(m/s) transient mon ltm
UU uu (m/s)**2 transient mon ltm
Momentum Flux uv (m/s)**2 transient mon ltm
Meridional Heat Flux vt K*(m/s) transient mon ltm
VV vv (m/s)**2 transient mon ltm
Vertical Heat flux wt K*mb/sec transient mon ltm

Note:

These variables are averages of instantaneous values at the 4 reference times; 0,6,12 and 18z over the averaging period (month, day).

Availability and usage restrictions:

Note:

These variables are instantaneous values at the reference time. These variables are averages of instantaneous values at the 4 reference times; 0,6,12 and 18z over the averaging period (month, day)

Usage Restrictions:

  • None

Detailed Description:

  • 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.

Caveats:

  • None

Related File Naming & Structure Information:

File Names:

  • Archive parameters: File names are composed of variable abbreviations, averaging period and statistic. Averaging periods include "day" and "mon". Statistics include "mean", "ltm"(long-term mean), "inter.std" (interannual standard deviation), "intra.std" (intra-annual standard deviation), "3_10"(3-10 day filtered std).

    (variable).(averaging period).(statistic).nc (e.g. hgt.mon.mean.nc)

  • Data set format and size:
  • All data are stored in netCDF files
  • There are 64 files currently
  • Sizes range from 43 Kbytes to 443 Mbytes
  • Current total of 3.8 Gbytes
  • var.time.stat.nc   (In directory: /Datasets/ncep.reanalysis.derived/)
  • Files are available by anonymous FTP from ftp.cdc.noaa.gov in /Datasets/ncep.reanalysis.derived/surface.
  • Archive parameters: File names are generally composed of variable abbreviations, averaging period and statistic. Averaging periods include "day" and "mon". Statistics include "mean", "ltm"(long-term mean), "inter.std" (interannual standard deviation), "3_10"(3-10 day filtered std). (variable).(averaging period).(statistic).nc

Dataset Format and Size:

  • PSD standard NetCDF xx (packed).
  • All data are stored in netCDF files
  • The data are divided by variable and year into separate files
  • There are 48 files currently
  • Files range in size from 167 Kbytes to 26 Mbytes
  • Current total of 377 Mbytes

Missing Data:

  • Missing data is flagged with a value of 32767s.

Citation:

  • 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 Derived data products from PSD, we ask that you acknowledge us in your use of the data. This may be done by including text such as NCEP Reanalysis Derived data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.cdc.noaa.gov/ 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 Derived data set freely available online in the future. Thank you!

References:

  • March, 1996 BAMS

Original Source:

  • NOAA National Center for Environmental Prediction

Contact:

  • Physical Sciences Division: Data Management
    NOAA/ESRL/PSD
    325 Broadway
    Boulder, CO 80305-3328
    esrl.psd.data@noaa.gov