NCEP/NCAR Reanalysis Monthly Means and Other Derived Variables

We have transitioned the data files from netCDF3 to netCDF4-classic format on Monday Oct 20th, 2014.

Brief 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 1981 - 2010.

Spatial Coverage:

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

Levels:

• Surface or near the surface (.995 sigma level)
• The variables on sigma level 0.995 are: air, rhum, uwnd, vwnd and wspd.
• Also, precipitable water is included here, because it is a 3-D file on a 2.5 degree grid, but it is not a surface value, but rather for the entire atmospheric column

Update Schedule:

• Monthly

Download/Plot Data: (FTP Access)

Variable	Statistic	Level	Download File	Create Plot/Subset	File Metadata
Air Temperature	Monthly Means	Surface	air.mon.mean.nc		File Metadata
Air Temperature	Monthly Long Term Means	Surface	air.mon.ltm.nc		File Metadata
Air Temperature	Monthly Means	Surface	air.sig995.mon.mean.nc		File Metadata
Air Temperature	Monthly Long Term Means	Surface	air.sig995.mon.ltm.nc		File Metadata
Air Temperature	Daily Long Term Means	Surface	air.sig995.day.1981-2010.ltm.nc		File Metadata
Air Temperature	4X Daily Long Term Means	Surface	air.sig995.4Xday.1981-2010.ltm.nc		File Metadata
Surface Lifted Index	Monthly Means	Surface	lftx.sfc.mon.mean.nc		File Metadata
Best (4-layer) Lifted Index	Monthly Means	Surface	lftx4.sfc.mon.mean.nc		File Metadata
Omega (dp/dt)	Monthly Means	Surface	omega.sig995.mon.mean.nc		File Metadata
Omega (dp/dt)	Monthly Long Term Means	Surface	omega.sig995.mon.ltm.nc		File Metadata
Omega (dp/dt)	Daily Long Term Means	Surface	omega.sig995.day.1981-2010.ltm.nc		File Metadata
Omega (dp/dt)	4X Daily Long Term Means	Surface	omega.sig995.4Xday.1981-2010.ltm.nc		File Metadata
Potential Temperature	Monthly Means	Surface	pottmp.sig995.mon.mean.nc		File Metadata
Potential Temperature	Monthly Long Term Means	Surface	pottmp.sig995.mon.ltm.nc		File Metadata
Potential Temperature	Daily Long Term Means	Surface	pottmp.sig995.day.1981-2010.ltm.nc		File Metadata
Potential Temperature	4X Daily Long Term Means	Surface	pottmp.sig995.4Xday.1981-2010.ltm.nc		File Metadata
Precipitable Water Content	Monthly Means	Surface	pr_wtr.eatm.mon.mean.nc		File Metadata
Precipitable Water Content	Monthly Long Term Means	Surface	pr_wtr.eatm.mon.ltm.nc		File Metadata
Precipitable Water Content	Daily Long Term Means	Surface	pr_wtr.eatm.day.1981-2010.ltm.nc		File Metadata
Precipitable Water Content	4X Daily Long Term Means	Surface	pr_wtr.eatm.4Xday.1981-2010.ltm.nc		File Metadata
Precipitable Water Content	Monthly Means	Surface	pr_wtr.mon.mean.nc		File Metadata
Precipitable Water Content	Monthly Long Term Means	Surface	pr_wtr.mon.ltm.nc		File Metadata
Surface Pressure	Monthly Means	Surface	pres.mon.mean.nc		File Metadata
Surface Pressure	Monthly Long Term Means	Surface	pres.mon.ltm.nc		File Metadata
Surface Pressure	Daily Long Term Means	Surface	pres.day.1981-2010.ltm.nc		File Metadata
Surface Pressure	4X Daily Long Term Means	Surface	pres.4Xday.1981-2010.ltm.nc		File Metadata
Surface Pressure	Monthly Means	Surface	pres.sfc.mon.mean.nc		File Metadata
Relative Humidity	Monthly Means	Surface	rhum.mon.mean.nc		File Metadata
Relative Humidity	Monthly Long Term Means	Surface	rhum.mon.ltm.nc		File Metadata
Relative Humidity	Monthly Means	Surface	rhum.sig995.mon.mean.nc		File Metadata
Relative Humidity	Monthly Long Term Means	Surface	rhum.sig995.mon.ltm.nc		File Metadata
Relative Humidity	Daily Long Term Means	Surface	rhum.sig995.day.1981-2010.ltm.nc		File Metadata
Relative Humidity	4X Daily Long Term Means	Surface	rhum.sig995.4Xday.1981-2010.ltm.nc		File Metadata
Sea Level Pressure	Monthly Means	Sea Level	slp.mon.mean.nc		File Metadata
Sea Level Pressure	Monthly Long Term Means	Sea Level	slp.mon.ltm.nc		File Metadata
Sea Level Pressure	Daily Long Term Means	Sea Level	slp.day.1981-2010.ltm.nc		File Metadata
Sea Level Pressure	4X Daily Long Term Means	Sea Level	slp.4Xday.1981-2010.ltm.nc		File Metadata
u-wind	Monthly Means	Surface	uwnd.mon.mean.nc		File Metadata
u-wind	Monthly Long Term Means	Surface	uwnd.mon.ltm.nc		File Metadata
u-wind	Monthly Means	Surface	uwnd.sig995.mon.mean.nc		File Metadata
u-wind	Monthly Long Term Means	Surface	uwnd.sig995.mon.ltm.nc		File Metadata
u-wind	Daily Long Term Means	Surface	uwnd.sig995.day.1981-2010.ltm.nc		File Metadata
u-wind	4X Daily Long Term Means	Surface	uwnd.sig995.4Xday.1981-2010.ltm.nc		File Metadata
v-wind	Monthly Means	Surface	vwnd.mon.mean.nc		File Metadata
v-wind	Monthly Long Term Means	Surface	vwnd.mon.ltm.nc		File Metadata
v-wind	Monthly Means	Surface	vwnd.sig995.mon.mean.nc		File Metadata
v-wind	Monthly Long Term Means	Surface	vwnd.sig995.mon.ltm.nc		File Metadata
v-wind	Daily Long Term Means	Surface	vwnd.sig995.day.1981-2010.ltm.nc		File Metadata
v-wind	4X Daily Long Term Means	Surface	vwnd.sig995.4Xday.1981-2010.ltm.nc		File Metadata
Wind Speed	Monthly Means	Surface	wspd.mon.mean.nc		File Metadata
Wind Speed	Monthly Long Term Means	Surface	wspd.mon.ltm.nc		File Metadata
Wind Speed	Monthly Means	Surface	wspd.sig995.mon.mean.nc		File Metadata
Wind Speed	Monthly Long Term Means	Surface	wspd.sig995.mon.ltm.nc		File Metadata

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 PSL 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:

• 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). (variable).(averaging period).(statistic).nc

OpenDap File Names:

• /thredds/dodsC/Datasets/ncep.reanalysis.derived/surface/var.time.stat.nc   

Dataset Format and Size:

• PSL 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 -9.96921e+36f.

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 PSL, 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 PSL, Boulder, Colorado, USA, from their Web site at / in any documents or publications using these data. We would also appreciate receiving a copy of the relevant publications. This will help PSL 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 Laboratory: Data Management
  NOAA/ESRL/PSL
  325 Broadway
  Boulder, CO 80305-3328
  psl.data@noaa.gov