Where can I find analyses for input to REGRID?
Users with NCAR computing accounts have ready access to a variety of gridded
meteorological analyses and forecast products. Some of the more commonly-used
analyses archived at NCAR include:
Users who do not have NCAR computing accounts must find their own ways
to get gridded analyses or forecasts. Various real-time analyses
and forecasts may be available via anonymous ftp, for example.
Real-time analyses and forecasts that have been found useful include:
NCEP GDAS
The NCEP GDAS (Global Data Assimilation System) analysis as
archived at NCAR is the traditional option for analyses. Analyses
are available every 12 hours. Data are archived on a 2.5 degree x
2.5 degree lat/lon grid. Data are available from the mid 1970's to
recent months (updated periodically). Through March 1997, data are
in ON84 format. Beginnning in April 1997, data are in GRIB format.
For more information see www.scd.ucar.edu/dss/datasets/ds082.0.html
(for the ON84-formatted data through March 1997) or www.scd.ucar.edu/dss/datasets/ds083.0
(for the GRIB-formatted data beginning April 1997).
-
Peculiarities/Caveats:
-
Northern and southern hemispheres of a given global field are archived
as separate fields.
-
Snow-cover data are archived sporadically in the ON84 dataset.
-
SST are archived once per day in the ON84 dataset.
-
The Vtables are set up automatically for the ON84 GDAS data set, but if
you really want to see what they look like, see: Sample
Vtable for NCEP GDAS (ON84).
-
The Vtables are set up automatically for the GRIB GDAS data set, but if
you really want to see what they look like, see: Sample
Vtable for NCEP GDAS (GRIB).
NCEP/NCAR Reanalysis
The NCEP/NCAR Reanalysis has become a popular data source.
This data set is a global analysis beginning in 1948 using a single analysis
system for the entire dataset. Analyses are available every six hours.
Data are archived on a 2.5 x 2.5 degree lat/lon grid and a gaussian grid
(~1.9 degrees lat, 2.5 degrees lon). The data REGRID accesses are
in GRIB format. For more information, see www.scd.ucar.edu/dss/pub/reanalysis/index.html.
-
Peculiarities/Caveats:
-
Much of the surface data are actually six-hour forecasts.
-
Sea-surface temperature is not archived. Skin temperature may be
used with some caution. Be aware that ground temperatures and sea-surface
temperatures at coastlines may be unrealistic.
-
Sample Vtable for using the NCEP/NCAR Reanalysis
in REGRID.
NCEP Eta
The NCEP Eta is a regional analysis and forecast for North America
based on the Eta model.
-
Peculiarities/Caveats:
-
Sea-surface temperature is not archived. Skin temperature may be
used with some caution. Be aware that ground temperatures and sea-surface
temperatures at coastlines may be unrealistic.
-
The archived specific humidity is converted to relative humidity by pregrid.
For further information about the Eta archives at NCAR, see www.scd.ucar.edu/dss/pub/gcip.
Information about NCEP model products, including where to find the
real-time products, may be found at
http://www.emc.ncep.noaa.gov/index.html,
in pages such as
http://www.emc.ncep.noaa.gov/mmb/research/meso.products.html
and
http://www.emc.ncep.noaa.gov/modelinfo/index.html
ECMWF TOGA Global analysis
The archives at NCAR begin January 1985. Data are archived
at 2.5 x 2.5 degree lat/lon grid. Times are 00 UTC and 12 UTC.
-
Peculiarities/Caveats:
-
Sea-surface temperature is not archived. Skin temperature may be
used with some caution. Be aware that ground temperatures and sea-surface
temperatures at coastlines may be unrealistic.
-
Geopotential must be converted to geopotential height by REGRID.
Thus, both geopotential and geopotential height must be specified in the
Vtable. See the sample Vtable linked below.
-
ECMWF uses different parameter tables (i.e., GRIB code numbers) than NCEP
for many variables.
-
Usage of this dataset is restricted: [NCAR/DSS] may distribute this data
to US scientists, scientists visiting US organizations, and Canadian scientists
affiliated with UCAR member organizations only. This data must not be used
for commercial purposes. ECMWF must be given credit in any publications
in which this data is used. A permission
form must be signed and returned to DSS for use of this data.
For further information about the ECMWF TOGA analysis archives at
NCAR, see www.scd.ucar.edu/dss/datasets/ds111.2.html.
ECMWF Reanalysis
The ECMWF Reanalysis is a global analysis of 15 years' worth of
data. Archives are from Jan 1979 through Dec 1993. Data are
archived on a 2.5 x 2.5 degree lat/lon grid, in GRIB format.
-
Peculiarities/Caveats:
-
Sea-surface temperature is not archived. Skin temperature may be
used with some caution. Be aware that ground temperatures and sea-surface
temperatures at coastlines may be unrealistic.
-
Geopotential must be converted to geopotential height by REGRID.
Thus, both geopotential and geopotential height must be specified in the
Vtable. See the sample Vtable linked below.
-
ECMWF uses different parameter tables (i.e., GRIB code numbers) than NCEP
for many variables.
-
Usage of this dataset is restricted: [NCAR] may distribute this data to
US scientists, scientists visiting US organizations, and Canadian scientists
affiliated with UCAR member organizations only. This data must not be used
for commercial purposes. ECMWF must be given credit in any publications
in which this data is used. A permission
form must be signed and returned to DSS for use of this data.
For further information about the ECMWF Reanalysis archives at NCAR,
see www.scd.ucar.edu/dss/pub/ec-reanalysis.html.
Documentation HOME
Last modified: Tue May 16 17:24:36 MDT 2000