A subset of reanalysis from ECMWF ERA40 is available for the IPSL scientific community on ClimServ. Products have been extracted at ECWMF on regular latitude/longitude grid and converted from GRIB (meteorological format) to Netcdf (self-describing format, widely used in modelers community). Note that the ERA40 archive over the full period (1958-2002), with other products is also avalaible at IDRIS.
You must be a member of the IPSL to access to these data. In other cases, write a letter to:
Météo-France
Département Europe et Espace
1, quai Branly
75340 PARIS CEDEX 07
France
Introduce yourself and request the permission to use the netCDF formatted ECMWF Dataset available at IPSL. Upon receipt of the agreement from Météo-France, fax it to:
Sophie Cloché
Laboratoire de Meteorologie Dynamique
Ecole Polytechnique
F-91128 PALAISEAU CEDEX
France
Fax : +33 1 69 33 30 49
Spatial coverage
Global area: 0E to 358.875E , 90N to 90S
regular longitude-latitude mesh: 1.125x1.125deg
Temporal resolution
- 4 times daily (4xdaily) products:
Analysis
Times : 0 6 12 18 h
step : 0 h
Forecasting
Times : 0, 6, 12, 18 h
Steps :6 h
Temporal coverage
Data type
|
4 times daily
|
Monthly mean
|
Surface
|
1979/01-2002/08
|
1970/01-2002/08 |
Pressure Level
|
1967/01-2002/08 |
1970/01-2002/08 |
Model Level
|
1983/01-1997/12 |
- |
Levels
Model levels
The ECMWF model uses a hybrid vertical coordinate that reduces smoothly from a terrain-following sigma coordinate in the lower troposphere to a pressure coordinate in the stratosphere.
To represent the vertical variation of the dependent variables , , and , the atmosphere is divided into layers. These layers are defined by the pressures at the interfaces between them (the `half-levels'), and these pressures are given by
|
(1)
|
for . The and are constants whose values effectively define the vertical coordinate and is the surface pressure field.
The values of the and for all are given here to allow the reconstruction of the `full-level' pressure associated with each model level (middle of layer) from ( )by using equation (1) and the surface pressure field.
Pressure levels
- 23 levels (in hPa) : 1, 2, 3, 5, 7, 10, 20, 30, 50, 70, 100, 150, 200, 250, 300, 400, 500, 600, 700, 775, 850, 925, 1000
The fields have been interpolated to standard pressure levels from the original model levels.
Available products
Surface
Long name |
Grib id |
Netcdf name
|
Units |
Dataset* |
Level type* |
Sea ice fraction |
31
|
ci
|
(0-1)
|
AN
|
SF
|
Mean sea level pressure |
151 |
msl |
Pascal |
AN |
SF |
Temperature at 2 meters |
167 |
t2 |
degK |
AN |
SF |
Dew point at 2 meters |
168 |
d2 |
degK |
AN |
SF |
Soil temperature level1
|
139 |
stl1 |
degK |
AN |
SF |
Soil temperature level2 |
170
|
stl2
|
degK |
AN |
SF |
Soil temperature level3 |
183
|
stl3
|
degK |
AN |
SF |
Soil temperature level4 |
236
|
stl4
|
degK |
AN |
SF |
Volumetric soil water level 1
|
39
|
swvl1
|
m**3 s**-3 |
AN |
SF |
Volumetric soil water level 2
|
40
|
swvl2 |
m**3 s**-3 |
AN |
SF |
Volumetric soil water level 3
|
42
|
swvl3 |
m**3 s**-3 |
AN |
SF |
Volumetric soil water level 4
|
42
|
swvl4 |
m**3 s**-3 |
AN |
SF |
Geopotentiel
|
129
|
geopt
|
m**2 s**-2 |
AN |
SF |
10m U wind component |
165 |
u10 |
m/s |
AN |
SF |
10m V wind component |
166 |
v10 |
m/s |
AN |
SF |
Albedo |
174 |
al |
-
|
AN |
SF |
Surface roughness
|
173 |
sr |
m |
AN |
SF |
Land/sea mask |
172
|
lsm
|
(0,1)
|
AN
|
SF
|
Sea surface temperature
|
24
|
sstk
|
degK
|
AN
|
SF
|
Skin temperature
|
235
|
skt
|
degK
|
AN
|
SF
|
Total column water
|
136 |
tcw |
kg/m^2 |
AN |
SF |
Total column water vapor |
137 |
tcwv |
kg/m^2 |
AN
|
SF
|
Snow depth |
141
|
sd
|
m of water equivalent |
AN
|
SF
|
Low cloud cover
|
186 |
lcc |
(0-1) |
AN |
SF
|
Medium cloud cover
|
187 |
mcc |
(0-1) |
AN
|
SF
|
High cloud dover
|
188 |
hcc |
(0-1)
|
AN
|
SF |
Total cloud cover
|
164 |
tcc |
(0-1) |
AN
|
SF |
Total column ozone
|
206 |
tco3 |
kg/m^2
|
AN
|
SF |
Evaporation |
182 |
e |
m of water |
FC |
SF |
Large scale precipitation |
142 |
lsp |
m |
FC |
SF |
Convective precipitation |
143 |
cp |
m |
FC |
SF |
Surface solar radiation |
176 |
ssr |
(W/m^2)s |
FC |
SF |
Surface thermal radiation |
177 |
str |
(W/m^2)s |
FC |
SF |
Top thermal radiation |
179 |
ttr |
(W/m^2)s |
FC |
SF |
Surface latent heat flux |
147 |
slhfl |
(W/m^2)s |
FC |
SF |
Surface sensible heat flux |
146 |
sshfl |
(W/m^2)s |
FC |
SF |
East /West surface stress |
180 |
ewss |
(N/m^2)s |
FC |
SF |
North/South surface stress |
181 |
nsss |
(N/m^2)s |
FC |
SF |
Downward surface solar radiation |
169
|
ssrd
|
W/m^2 s |
FC
|
SF
|
Downward surface thermal radiation |
175
|
strd
|
W/m^2 s |
FC
|
SF
|
Boundary layer height |
159
|
blh
|
m
|
FC
|
SF
|
Snowfall |
144
|
sf
|
m of water equivalent |
FC
|
SF
|
Maximum temperature during period
|
201 |
mx2t |
degK |
FC |
SF |
Manimum temperature during period
|
202 |
mn2t |
degK |
FC |
SF |
Surface solar radiation clear sky
|
210 |
ssrc |
W:m^2 s
|
FC |
SF |
Large scale snowfall
|
240 |
lsf |
m of water equivalent
|
FC |
SF |
Convective snowfall
|
239 |
csf |
m of water equivalent |
FC |
SF |
Runoff
|
205 |
ro |
m |
FC |
SF |
Pressure level
Long name |
Grib id |
Netcdf name
|
Units |
Dataset* |
Level type* |
Geopotentiel |
129 |
geopt |
m^2/s^2 |
AN |
PL
|
Temperature |
130 |
ta |
degK |
AN |
PL |
U-velocity |
131 |
u |
m/s |
AN |
PL |
V-velocity |
132 |
v |
m/s |
AN |
PL |
Vertical velocity |
135 |
w
|
Pascal/s |
AN |
PL |
Vorticity (relative) |
138 |
vo |
s^-1 |
AN |
PL |
Divergence |
155 |
d |
s^-1 |
AN |
PL |
Relative humidity |
157 |
r |
% |
AN |
PL |
Specific humidity
|
133 |
q |
Kg/Kg |
AN
|
PL |
Ozone mass mixing ratio
|
203
|
o3
|
Kg/Kg |
AN
|
PL
|
Potential vorticity
|
60 |
pv |
m^2s^-1K Kg^-1 |
AN |
PL
|
Model level
Long name |
Grib id |
Netcdf name |
Units |
Dataset*
|
Level type* |
Log surface pressure |
152 |
lnsp |
- |
AN |
ML(1st level)
|
Temperature
|
130 |
t |
degK |
AN |
ML |
Specific humidity
|
133 |
q |
kg/kg |
AN |
ML |
*AN: Analysis
*FC: Forecats
*SF: surface
*PL: pressure level
*ML: model level
Access
The access to this dataset is restricted to the members of IPSL.
You can access data by several ways :
- from your login on climserv server, camelot: cd /bdd/ERA40/.
To have an access on our server, please mail to
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- by ftp : ftp://ftp.climserv.ipsl.polytechnique.fr/era40/
- by
your login at IDRIS: data are available in the
/u/rech/psl/rpsl376/ERA40/NETCDF/ directory. You must be a member of the
subipsl subgroup; if it is not the case, please contact Sophie Cloché
(
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)
- by OpenDaP at IDRIS (in dowload mode): http://dods.idris.fr:81/rpsl376/ERA40/NETCDF/
- by OpenDaP at IDRIS (in opendap mode):http://dods.idris.fr:81/cgi-bin/nph-dods/rpsl376/rpsl376/ERA40/NETCDF/
Format
The data files are in the netCDF format and are compatible with the CF convention. It defines the meaning of attributes, the naming of variables, the units, the coordinate variables.
The files are organized by variable, by month for analysis and for forecast, for 4xdaily fields. For monthly means, there is one file per variable and per year. The geophysical values of variables (called unpacked values) are coded on 2 bytes (packed values).
The vast majority of the data that we distribute in netCDF files have been packed into short integers to save space. You must unpack that data to get the correct floating point representation of the data. Each netCDF variable (except some of them) that has been packed has an add_offset and scale_factor attribute associated with it. The scale_factor and add_offset can vary with each netCDF file even for the same variable from the same data set, though this doesn't happen often.
The formula to unpack the data is:
unpacked value = add_offset + ( (packed value) * scale_factor )
Related file Naming and Structure information The ECMWF data are stored on the directory: /bdd/ERA40/
- The subdirectories are the following:
/FFF/XXX/AA_LL/YYYY/name_file
FFF: format (NETCDF)
XXX: is the temporal resolution (4xdaily)
AA_LL: AA is the type of data (AN for Analysis or FC for Forecast)
LL is the level type (SF, PL, ML)
SF: surface
PL: Pressure level
ML:Model level
YYYY: year
NAME.YYYY[MM].ABC.EXT
NAME: is the netcdf parameter name (see table)
YYYY: year
MM: month
A: type(a: analysis, f:forecast)
B: level type (s:surface,v: surface pv, t: isentropic level, p: pressure level, m: model level)
C: temporal resolution (h: 4 x daily, d: daily mean, m: monthly mean)
EXT: format (.nc forNetcdf)
Original source
European Centre for Medium-Range Weather Forecasts.
Usage restrictions
The ECMWF data are restricted to non-commercial use. For additional information or permission to use ECMWF data, contact the European Centre for Medium-Range Weather Forecasts
Contact
Sophie Cloché-IPSL
Ecole Polytechnique
91128 Palaiseau cedex
FRANCE
Tel: 33 (1) 69 33 51 31
mailto:
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