Parameters available in the ECMWF ERA-15 Re-analysis data held at the BADC (January 1979 - February 1994)

Introduction

The BADC archives a range of parameters produced by the ECMWF ERA-15 Re-analyses project.

The tables on this web page display all the parameters that are available for each grid type and resolution. The tables also include the time period and the type and number of levels for which each parameter is available.

Explanation of Initialised and Uninitialised Data

Regular 2.5° x 2.5° gridded data (initialised only)
- Surface/single level analysis fields (lisfYYMMDDHH)
- Upper air analysis fields on pressure levels (liprYYMMDDHH)
N80 Reduced Gaussian Gridded data (initialised and uninitialised)
- Surface/single level analysis fields (gisfYYMMDDHH/gpsfYYMMDDHH)
- Upper air Gaussian gridded analysis fields on model levels (giuaYYMMDDHH/gpuaYYMMDDHH)
Spectral T106 data (initialised and uninitialised)
- Upper air analysis fields on model levels (siuaYYMMDDHH/spuaYYMMDDHH)
- Upper air analysis fields on pressure levels (siprYYMMDDHH/spprYYMMDDHH)
Orography

Details of the available parameters are also listed for the Operational data sets on separate a page.

Explanation of Initialised and Uninitialised Data

The ERA-15 data was produced using both initialised and an uninitialised model runs.

Initialisation was used to suppress gravity waves in model runs in the model used to produce the ERA-15 data set. Though the wind and mass fields were balanced within the analysis “boxes”, on the larger scale and away from the equator, minor imbalances still appeared between the “boxes”. These imbalances set up fictitious, undesired gravity waves. In the normal mode initialisation process the model suppressed these gravity waves. During the process, the mass and wind fields became adjusted in such a way that no further undesired gravity waves would appear.

A primary reason for initialisation was to improve the data assimilation. Unless initial, spurious waves in the first guess forecast, especially in the surface pressure, were eliminated, they could lead to the rejection of good, and the acceptance of bad observations, and to a degraded estimation of the necessary increments to be generated by the selected observations.

The problem of initialisation was overcome when the 3D-Variational (3D-Var) data assimilation scheme was introduced on 30th January 1996. The Operational analyses from the 3D-var system are practically equivalent to the initialised analyses from the previous Optimum-Interpolation assimilation system used for ERA-15.

The full-resolution Spectral T106 upper air and N80 Reduced Gaussian gridded surface (and one upper air parameter) data are available as both initialised and uninitialised data sets. The regular latitude-longitude 2.5° gridded data is only available as initialised data. The initialised data sets can be found in the directory:

/badc/ecmwf-era/data/init/

They can also be accessed via the webserver (by registered BADC users) at:
http://badc.nerc.ac.uk/cgi-bin/data_browser/data_browser/badc/ecmwf-era/data/init/

The uninitialised data sets can be found in the directory:

/badc/ecmwf-era/data/uninit/

They can also be accessed via the webserver (by registered BADC users) at:
http://badc.nerc.ac.uk/cgi-bin/data_browser/data_browser/badc/ecmwf-era/data/uninit/

Please note that the initialised and uninitialised data sets contain the same parameters and levels for the same time periods. However, the filenames differ in the manner described below.

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Regular 2.5° x 2.5° gridded data (initialised only)

Tables 1 and 2 show the parameters available for ERA-15 analysis data on a 2.5° x 2.5° regular grid (initialised only). These files are located in the directory:

/badc/ecmwf-era/data/gridded/ or /badc/ecmwf-era/data/gridded_2.5/

They can also be accessed via the webserver (by registered BADC users) at:
http://badc.nerc.ac.uk/cgi-bin/data_browser/data_browser/badc/ecmwf-era/data/gridded/ or
http://badc.nerc.ac.uk/cgi-bin/data_browser/data_browser/badc/ecmwf-era/data/gridded_2.5/

Surface/single level analysis fields (lisfYYMMDDHH)

The regular 2.5° x 2.5° gridded surface/single level fields are stored following the file-naming convention:

lisfYYMMDDHH

Where li means lat/long regular grid (the "i" stands for initialised),
sf means surface or single levels (i.e. only one atmospheric level),
and YYMMDDHH stand for the Year, Month, Day (of the month), and Hour (either 00, 06, 12 or 18).
The format of the files is GRIB.

The complete file and directory structure of the regular 2.5° x 2.5° gridded surface/single level fields takes the form of:

/badc/ecmwf-era/data/gridded/YYYY/lisfYYMM/lisfYYMMDDHH

Table 1. Parameters, dates and levels available for the ECMWF ERA-15 Re-analysis regular 2.5° x 2.5° gridded surface/single level fields.

Dates Parameters Levels

Start End Parameters (Name) ECMWF code (numeric) ECMWF code Units Levels
Total Levels

01/01/1979 28/02/1994 Soil temperature level 1 139 STL1 K Surface/single 1

" " Soil wetness level 1 140 SWL1 m (of water) " "

" " Snow depth 141 SD m (of water equivalent) " "

" " Mean sea level pressure 151 MSL Pa " "

" " 10 metre u wind component 165 10U m s^-1 " "

" " 10 metre v wind component 166 10V m s^-1 " "

" " 2 metre temperature 167 2T K " "

" " 2 metre dewpoint temperature 168 2D K " "

" " Soil temperature level 2 170 STL2 K " "

" " Soil wetness level 2 171 SWL2 m (of water) " "

" " Surface roughness 173 SR m " "

" " Albedo 174 AL - " "

" " Soil temperature level 3 183 STL3 K " "

" " Soil wetness level 3 184 SWL3 m (of water) " "

" " Skin reservoir content 198 SRC m (of water) " "

" " Percentage of vegetation 199 VEG % " "

" " Apparent surface humidity 233 ASQ kg/kg " "

" " Log of surface roughness length for heat 234 LSRH - " "

" " Skin temperature 235 SKT K " "

" " Soil temperature level 4 236 STL4 K " "

" " Soil wetness level 4 237 SWL4 m (of water) " "

Upper air analysis fields on pressure levels (liprYYMMDDHH)

The regular 2.5° x 2.5° gridded pressure level fields are stored following the file-naming convention:

liprYYMMDDHH

Where li means lat/long regular grid (the "i" means initialised),
pr means the data is stored on pressure levels,
and YYMMDDHH stand for the Year, Month, Day (of the month), and Hour (either 00, 06, 12 or 18).
The format of the files is GRIB.

The complete file and directory structure of the regular 2.5° x 2.5° gridded pressure level fields takes the form of:

/badc/ecmwf-era/data/gridded/YYYY/liprYYMM/liprYYMMDDHH

Table 2. Parameters, dates and levels available for the ECMWF ERA-15 Re-analysis regular 2.5° x 2.5° gridded upper air fields on pressure levels.

Dates Parameters Levels

Start End Parameters (Name) ECMWF code (numeric) ECMWF code Units Levels
Total Levels

01/01/1979 28/02/1994 Geopotential (at the surface = orography) 129 Z m² s^-2 10, 30, 50, 70, 100, 150, 200, 250, 300, 400, 500, 600, 700, 775, 850, 925, 1000 hPa 17
" " Temperature 130 T K " "
" " U-velocity 131 U m s^-1 " "
" " V-velocity 132 V m s^-1 " "
" " Vertical velocity 135 W Pa s^-1 " "
" " Relative humidity 157 R % " "

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N80 Reduced Gaussian Gridded data (initialised and uninitialised)

Tables 3 and 4 show the parameters available for ECMWF ERA-15 Re-analysis data on an N80 Reduced Gaussian grid. Both initialised and uninitialised data sets are available on the N80 Reduced Gaussian grid.

The initialised files are located in the directory:

/badc/ecmwf-era/data/init/N80/ or via the webserver (by registered BADC users) at:
http://badc.nerc.ac.uk/cgi-bin/data_browser/data_browser/badc/ecmwf-era/data/init/N80/

The uninitialised files are located in the directory:

/badc/ecmwf-era/data/uninit/N80/ or via the webserver (by registered BADC users) at:
http://badc.nerc.ac.uk/cgi-bin/data_browser/data_browser/badc/ecmwf-era/data/uninit/N80/

Surface/single level analysis fields (gisfYYMMDDHH/gpsfYYMMDDHH)

The N80 Reduced Gaussian gridded surface/single level analysis fields are stored following the file-naming convention:

gisfYYMMDDHH (initialised) and:

gpsfYYMMDDHH (uninitialised)

Where gi/gp stands for a Gaussian grid (the "i" means initialised and the "p" denotes uninitialised data),
sf means surface or single levels (i.e. only one atmospheric level),
and YYMMDDHH stand for the Year, Month, Day (of the month), and Hour (either 00, 06, 12 or 18).
The format of the files is GRIB.

The complete file and directory structure of the N80 Reduced Gaussian gridded surface/single level analysis fields takes the form of:

/badc/ecmwf-era/data/init/N80/YYYY/gisfYYMM/gisfYYMMDDHH (initialised) and:

/badc/ecmwf-era/data/uninit/N80/YYYY/gpsfYYMM/gpsfYYMMDDHH (uninitialised)

Table 3. Parameters, dates and levels available for the ECMWF ERA-15 Re-analysis N80 Reduced Gaussian gridded surface/single level fields.

Dates Parameters Levels

Start End Parameters (Name) ECMWF code (numeric) ECMWF code Units Levels
Total Levels

01/01/1979 28/02/1994 Soil temperature level 1 139 STL1 K Surface/single 1

" " Soil wetness level 1 140 SWL1 m (of water) " "

" " Snow depth 141 SD m (of water equivalent) " "

" " Mean sea level pressure 151 MSL Pa " "

" " 10 metre u wind component 165 10U m s^-1 " "

" " 10 metre v wind component 166 10V m s^-1 " "

" " 2 metre temperature 167 2T K " "

" " 2 metre dewpoint temperature 168 2D K " "

" " Soil temperature level 2 170 STL2 K " "

" " Soil wetness level 2 171 SWL2 m (of water) " "

" " Surface roughness 173 SR m " "

" " Albedo 174 AL - " "

" " Soil temperature level 3 183 STL3 K " "

" " Soil wetness level 3 184 SWL3 m (of water) " "

" " Skin reservoir content 198 SRC m (of water) " "

" " Percentage of vegetation 199 VEG % " "

" " Apparent surface humidity 233 ASQ kg/kg " "

" " Log of surface roughness length for heat 234 LSRH - " "

" " Skin temperature 235 SKT K " "

" " Soil temperature level 4 236 STL4 K " "

" " Soil wetness level 4 237 SWL4 m (of water) " "

Upper air Gaussian gridded analysis fields on model levels (giuaYYMMDDHH/gpuaYYMMDDHH)

Specific Humidity is the only N80 Reduced Gaussian gridded model level analysis field. It is stored following the file-naming convention:

giuaYYMMDDHH (initialised) and:

gpuaYYMMDDHH (uninitialised)

Where gi/gp stands for a Gaussian grid (the "i" means initialised and the "p" denotes uninitialised data),
ua means upper air model levels,
and YYMMDDHH stand for the Year, Month, Day (of the month), and Hour (either 00, 06, 12 or 18).
The format of the files is GRIB.

The complete file and directory structure of the N80 Reduced Gaussian gridded upper air model level analysis fields takes the form of:

/badc/ecmwf-era/data/init/N80/YYYY/giuaYYMM/giuaYYMMDDHH (initialised) and:

/badc/ecmwf-era/data/uninit/N80/YYYY/gpuaYYMM/gpuaYYMMDDHH (uninitialised)

Table 4. Dates and levels available for the ECMWF ERA-15 Re-analysis N80 Reduced Gaussian gridded Specific Humidity data on model levels.

Dates Parameters Levels

Start End Parameters (Name) ECMWF code (numeric) ECMWF code Units Levels
Total Levels

01/01/1979 28/02/1994 Specific humidity 133 SP kg/kg 1-31 31

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Spectral T106 data (initialised and uninitialised)

Tables 5 and 6 show the parameters available for ECMWF ERA-15 Re-analysis data in T106 Spectral resolution. Both initialised and uninitialised data sets are available in Spectral resolution.

The initialised files are located in the directory:

/badc/ecmwf-era/data/init/T106/ or via the webserver (by registered BADC users) at:
http://badc.nerc.ac.uk/cgi-bin/data_browser/data_browser/badc/ecmwf-era/data/init/T106/

The uninitialised files are located in the directory:

/badc/ecmwf-era/data/uninit/T106/ or via the webserver (by registered BADC users) at:
http://badc.nerc.ac.uk/cgi-bin/data_browser/data_browser/badc/ecmwf-era/data/uninit/T106/

Upper air analysis fields on model levels (siuaYYMMDDHH/spuaYYMMDDHH)

The T106 Spectral resolution model level analysis fields are stored following the file-naming convention:

siuaYYMMDDHH (initialised) and:

spuaYYMMDDHH (uninitialised)

Where si/sp means Spectral resolution (the "i" means initialised and the "p" denotes uninitialised data),
ua means upper air model levels,
and YYMMDDHH stand for the Year, Month, Day (of the month), and Hour (either 00, 06, 12 or 18).
The format of the files is GRIB.

The complete file and directory structure of the T106 Spectral model level analysis fields take the form of:

/badc/ecmwf-era/data/init/T106/YYYY/siuaYYMM/siuaYYMMDDHH (initialised) and:

/badc/ecmwf-era/data/uninit/T106/YYYY/spuaYYMM/spuaYYMMDDHH (uninitialised)

Table 5. Parameters, dates and levels available for the ECMWF ERA-15 Re-analysis T106 Spectral upper air fields on model levels.

Dates Parameters Levels

Start End Parameters (Name) ECMWF code (numeric) ECMWF code Units Levels Total Levels

01/01/1979 28/02/1994 Temperature 130 T K 1-31 31

" " Vertical velocity 135 W Pa s^-1 " "

" " Vorticity (relative) 138 VO s^-1 " "

" " Log surface pressure 152 LNSP - " "

" " Divergence 155 D s^-1 " "

Upper air analysis fields on pressure levels (siprYYMMDDHH/spprYYMMDDHH)

The T106 Spectral resolution pressure level analysis fields are stored following the file-naming convention:

siprYYMMDDHH (initialised) and:

spprYYMMDDHH (uninitialised)

Where si/sp means Spectral resolution (the "i" means initialised and the "p" denotes uninitialised data),
pr means upper air pressure levels,
and YYMMDDHH stand for the Year, Month, Day (of the month), and Hour (either 00, 06, 12 or 18).
The format of the files is GRIB.

The complete file and directory structure of the T106 Spectral model level analysis fields take the form of:

/badc/ecmwf-era/data/init/T106/YYYY/siprYYMM/siprYYMMDDHH (initialised) and:

/badc/ecmwf-era/data/uninit/T106/YYYY/spprYYMM/spprYYMMDDHH (uninitialised)

Table 6. Parameters, dates and levels available for the ECMWF ERA-15 Re-analysis T106 Spectral upper air fields on pressure levels.

Dates Parameters Levels

Start End Parameters (Name) ECMWF code (numeric) ECMWF code Units Levels Total Levels

01/01/1979 28/02/1994 Geopotential 129 Z m² s^-2 10, 30, 50, 70, 100, 150, 200, 250, 300, 400, 500, 600, 700, 775, 850, 925, 1000 hPa 17

" " Temperature 130 T K " "

" " Vertical velocity 135 W Pa s^-1 " "

" " Vorticity (relative) 138 VO s^-1 " "

" " Divergence 155 D s^-1 " "

" " Relative humidity 157 R % " "

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Orography files

Separate files are used to store the orography data for each grid type of ERA-15 Re-analysis data. Note that the surface geopotential (where available) is equal to the orography.

The orography files for ERA-15 Re-analysis data sets are held in the directory:

/badc/ecmwf-era/data/orography or via the webserver (by registered BADC users) at:
http://badc.nerc.ac.uk/cgi-bin/data_browser/data_browser/badc/ecmwf-era/data/orography/

There are three orography files for the ERA-15 Re-analysis data:

Gridded 2.5° x 2.5° - llor80010100
N80 (reduced) Gaussian grid - gpor79010100
Spectral (T106) - spor90010100

Depending on the grid type, the files will contain some of the constant fields listed in Table 7. The spectral orography file spor90010100 only contains the surface geopotential.

Table 7. Orography parameters and their ECMWF codes.

Parameter name ECMWF code (numeric) ECMWF code

Geopotential (at the surface, orography) 129 Z

Standard deviation of orography 160 SDOR

Anisotropy of subgrid scale orography 161 ISOR

Angle of subgrid scale orography 162 ANOR

Slope of subgrid scale orography 163 SLOR

Land/Sea mask 172 LSM

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Dates		Parameters				Levels
Start	End	Parameters (Name)	ECMWF code (numeric)	ECMWF code	Units	Levels	Total Levels
01/01/1979	28/02/1994	Soil temperature level 1	139	STL1	K	Surface/single	1
"	"	Soil wetness level 1	140	SWL1	m (of water)	"	"
"	"	Snow depth	141	SD	m (of water equivalent)	"	"
"	"	Mean sea level pressure	151	MSL	Pa	"	"
"	"	10 metre u wind component	165	10U	m s^-1	"	"
"	"	10 metre v wind component	166	10V	m s^-1	"	"
"	"	2 metre temperature	167	2T	K	"	"
"	"	2 metre dewpoint temperature	168	2D	K	"	"
"	"	Soil temperature level 2	170	STL2	K	"	"
"	"	Soil wetness level 2	171	SWL2	m (of water)	"	"
"	"	Surface roughness	173	SR	m	"	"
"	"	Albedo	174	AL	-	"	"
"	"	Soil temperature level 3	183	STL3	K	"	"
"	"	Soil wetness level 3	184	SWL3	m (of water)	"	"
"	"	Skin reservoir content	198	SRC	m (of water)	"	"
"	"	Percentage of vegetation	199	VEG	%	"	"
"	"	Apparent surface humidity	233	ASQ	kg/kg	"	"
"	"	Log of surface roughness length for heat	234	LSRH	-	"	"
"	"	Skin temperature	235	SKT	K	"	"
"	"	Soil temperature level 4	236	STL4	K	"	"
"	"	Soil wetness level 4	237	SWL4	m (of water)	"	"

Parameter name	ECMWF code (numeric)	ECMWF code
Geopotential (at the surface, orography)	129	Z
Standard deviation of orography	160	SDOR
Anisotropy of subgrid scale orography	161	ISOR
Angle of subgrid scale orography	162	ANOR
Slope of subgrid scale orography	163	SLOR
Land/Sea mask	172	LSM