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ERA-15 MARS Access

1. Introduction

We have defined the following MARS types for monthly data:

 
an analysis fc forecast

We have defined the following MARS streams for monthly data:

 mo monthly means mv monthly variance or standard deviation data 
moda monthly means of daily means

Upper air data on pressure levels have to be extrapolated below the ground if the level pressure is higher than the surface pressure at the gridpoint. This postprocessing necessarily involves assumptions, and for e.g. atmospheric volume integrals it will lead to erroneous estimates. The user should be aware of this when using pressure level data. (in "Diagnostic Equations in Isobaric Coordinates" M.Wea.Rev. Vol. 110 Dec. 1982 pp 1801-1820) G. Boer suggests a method to avoid the problem.)

This document describes the monthly data stored in the ECMWF archiving and retrieval system 'MARS'.

Users should note that the monthly data are comprised of approximately two million GRIB fields, generated from an archive of over 60 million fields from the daily archive. Currently there are believed to be a small number (probably less than 100) corrupt fields within the daily archive. This is bound to have caused some errors in some of the monthly fields. The task of detecting and correcting such errors is enormous. However, this task will continue. The feedback of users who suspect errors will be much appreciated, and will be followed up rigorously.

2. GRIB archive.

ECMWF forecast and analysis products are stored using WMO FM 92 GRIB. However, it has been found convenient to use the option allowed in GRIB to number parameters according to local standards. To this end various local version of GRIB table 2 have been developed to cater for the varied needs of ECMWF applications. The most commonly used version is numbered 128, and is used for most ECMWF operational Archives. An additional version, numbered 160, had to be developed to cater for additional ERA-15 products, primarily variances and covariances in MARS stream 'MV'.

The ERA-15 data are archived in the original geometrical resolution, i.e. as T106 spherical harmonic coefficients for most upper air data and as gridpoint values in the corresponding Gaussian grid for surface data and upper air model level humidity and clouds. The retrieval system, MARS, can however provide the data interpolated to other geometries (e.g. 2.5 * 2.5 degrees) and/or subareas on user's request.

In addition to the monthly variance and standard deviation data (stream 'mv') monthly fields of the covariance between selected upper air pressure level fields have been produced. These fields (code figures 206 - 236) are not available in MARS. Please contact era@ecmwf.int for further details.

3. Parameter Tables and Units

The table lists the parameters, units, code figures, and MARS abbreviations.

Table 2 - Parameters, units, and Code Figures for GRIB table 2, ECMWF local version numbers 128 and 160
Parameter Mars abbreviation Code (128) Units (128) Code (160) Units (160)

atmospheric tide AT 127 127

geopotential (at the surface=orography) Z 129 m2s-2 129 m2s-2

temperature T 130 °K 130 °K

U-velociity U 131 ms-1 131 ms-1

V-velocity V 132 ms-1 132 ms-1

specific humidity Q 133 kgkg-1 133 kgkg-1

surface pressure SP 134 Pa 134 Pa

vertical velocity W 135 Pas-1 135 Pas-1

total column water TCW 136 Kgm-2 136 Kgm-2

total column water vapour TCWV 137 Kgm-2 137 Kgm-2

vorticity (relative) VO 138 Pas-1 138 Pas-1

soil temperature level 1 STL1 139 °K 139 °K

soil temperature level 2 STL2 170 °K 170 °K

soil temperature level 3 STL3 183 °K 183 °K

soil temperature level 4 STL4 236 °K 236 °K

soil wetness level 1 SWL1 140 m of water 140 m of water

soil wetness level 2 SWL2 171 m of water 171 m of water

soil wetness level 3 SWL3 184 m of water 184 m of water

soil wetness level 4 SWL4 237 m of water 237 m of water

snow depth SD 141 m of water equivalent 141 m of water equivalent

large scale precipitation LSP 142 m of water 142 kgm-2s-1

convective precipitation CP 143 m of water 143 kgm-2s-1

snow fall SF 144 m of water equivalent 144 kgm-2s-1

boundary layer dissipation BLD 145 Wm-2s 145 Wm-2

surface sensible heat flux SSHF 146 Wm-2s 146 Wm-2

surface latent heat flux SLHF 147 Wm-2s 147 Wm-2

mean sea level pressure MSL 151 Pa 151 Pa

ln surface pressure LNSP 152 152

divergence D 155 s-1 155 s-1

relative humidity R 157 157

total cloud cover TCC 164 (0-1) 164 (0-1)

10 metre u-wind 10U 165 ms-1 165 ms-1

10 metre v-wind 10V 166 ms-1 166 ms-1

2 metre temperature 2T 167 °K 167 °K

2 metre dewpoint 2D 168 °K 168 °K

surface solar radiation downward SSRD 169 Wm-2s 169 Wm-2

land/sea mask LSM 172 (0 - 1) 172 (0 - 1)

surface roughness SR 173 m 173 m

albedo AL 174 - 174 -

surface thermal radiation downwards STRD 175 Wm-2s 175 Wm-2

surface solar radiation SSR 176 Wm-2s 176 Wm-2

surface thermal radiation STR 177 Wm-2s 177 Wm-2

top solar radiation TSR 178 Wm-2s 178 Wm-2

top thermal radiation TTR 179 Wm-2s 179 Wm-2

u-component of stress EWSS 180 Nm-2s 180 Nm-2

v-component of stress NSSS 181 Nm-2s 181 Nm-2

evaporation E 182 m of water 182 kgm-2s-1

low cloud cover LCC 186 (0 - 1) 186 (0 - 1)

medium cloud cover MCC 187 (0 - 1) 187 (0 - 1)

high cloud cover HCC 188 (0 - 1) 188 (0 - 1)

latitudinal component of gravity wave stress LGWS 195 Nm-2s 195 Nm-2

meridional component of gravity wave stress MGWS 196 Nm-2s 196 Nm-2

gravity wave dissipation GWD 197 Wm-2s 197 Wm-2

skin reservoir content SRC 198 m of water 198 m of water

percentage of vegetation VEG 199 % 199 %

runoff RO 205 m of water 205 kgm-2s-1

SD of geopotential ZZ 206 m2s-2

cov. temperature and geopotential TZ 207 Km2s-2

SD of temperature TT 208 K

cov. sp. humidity and geopotential QZ 209 m2s-2

cov. sp. humidity and temperature QT 210 K

SD of specific humidity QQ 211 (0 - 1)

cov. U-wind and geopotential UZ 212 m3s-3

cov. U-wind and temperature UT 213 Kms-1

cov. U-wind and sp. humidity UQ 214 ms-1

SD of U-wind UU 215 ms-1

cov. V-wind and geopotential VZ 216 m3s-3

cov. V-wind and temperature VT 217 Kms-1

cov. V-wind and sp. humidity VQ 218 ms-1

cov. V-wind and U-wind VU 219 ms-1

SD of V-wind VV 220 ms-1

cov. vertical velocity and geopotential WZ 221 Pam2s-3

cov. vertical velocity and temperature WT 222 KPas-1

cov. vertical velocity and sp. humidity WQ 223 Pas-1

cov. vertical velocity and U-wind WU 224 Pams-2

cov. vertical velocity and V-wind WV 225 Pams-2

SD of vertical velocity WW 226 Pas-1

skin temperature SKT 235 °K 235 °K

convective snow fall CSF 239 m of water equivalent 239 kgm-2s-1

large scale snow fall LSF 240 m of water equivalent 240 kgm-2s-1

cloud liquid water content CLWC 246 kgkg-1

10m wind speed (irrespective of direction) 10SP 246 ms-1

cloud ice water content CIWC 247 kgkg-1

momentum flux (irrespective of direction) MOFL 247 Nm-2

cloud cover CC 248 (0 - 1)

gravity wave dissipation flux GWDF 249 Nm-2

heaviside ("beta") finction HSD 254 (0 - 1)

4. Data Content

All pressure level data are available on these 17 pressure leves:

 10, 30, 50, 70, 100, 150, 200, 250, 300, 400, 500, 
600, 700, 775, 850, 925 and 1000 hPa.

4.1 Single level analysis data

In the following GRIB table 2 version 128 is used, with the exception of parameter 246, which is taken from GRIB table 2 version 160.

N80 reduced Gaussian grid monthly means:

 type=an, stream=mo, repres=gg, levtype=sfc, time=00/06/12/18, 
param=139/140/141/151/165/166/167/168/170/171/172/ 173/174/183/184/198/199/235/236/237/246,

N80 reduced Gaussian grid monthly standard deviations:

 type=an, 
stream=mv, repres=gg, levtype=sfc, time=00/06/12/18, param=139/140/141/151/165/166/167/168/170/171/172/ 
173/174/183/184/198/199/235/236/237/246,

In the following GRIB table 2 version 160 is used throughout.

N80 reduced Gaussian grid monthly means of daily means:

 type=an, stream=moda, repres=gg, levtype=sfc, param=139/140/141/151/165/166/167/168/170/171/172/ 
173/174/183/184/198/199/235/236/237/246,

4.2 Model level analysis data

In the following GRIB table 2 version 128 is used throughout.

T106 spherical harmonics monthly means:

 type=an, stream=mo, repres=sh, levtype=ml, time=00/06/12/18, 
step=0, param=130/131/132/135/138/155,

T106 spherical harmonics monthly means of daily means:

 type=an, stream=moda, repres=sh, levtype=ml, step=0, 
param=130/131/132/135/138/155,

N80 reduced Gaussian grid monthly means:

 type=an, stream=mo, repres=gg, levtype=ml, time=00/06/12/18, step=0, 
param=133,

N80 reduced Gaussian grid monthly means of daily means:

 
type=an, stream=moda, repres=gg, levtype=ml, step=0, param=133,

4.3 Pressure level analysis data

In the following GRIB table 2 version 128 is used.

T106 spherical harmonics monthly means:

 type=an, stream=mo, 
repres=sh, levtype=pl, time=00/06/12/18, step=0, param=129/130/131/132/135/138/155/157,

T106 spherical harmonics monthly means of daily means:

 type=an, 
stream=moda, repres=sh, levtype=pl, step=0, param=129/130/131/132/135/138/155/157,

4.4 Single level forecast data - step 0

In the following GRIB code table 2 version 128 is used.

N80 reduced Gaussian grid monthly means:

 type=fc, stream=mo, repres=gg, levtype=sfc, time=00/06/12/18, step=0, 
param=136/137/139/140/141/151/164/165/166/167/168/170/171/172/ 173/174/183/184/186/187/188/198/199/235/236/237/246,

N80 reduced Gaussian grid monthly standard deviations:

 type=fc, 
stream=mv, repres=gg, levtype=sfc, time=00/06/12/18, step=0, param=136/137/139/140/141/151/164/165/166/167/168/170/171/172/ 
173/174/183/184/186/187/188/198/199/235/236/237/246,

In the following GRIB code table 2 version 160 is used.

N80 reduced Gaussian grid monthly means of daily means:

 type=fc, stream=moda, repres=gg, levtype=sfc, step=0, 
param=136/137/139/140/141/151/164/165/166/167/168/170/171/172/ 173/174/183/184/186/187/188/198/199/235/236/237/246,

4.5 Single level forecast data - steps 06, 12, 18, and 24

In the following GRIB code table 2 version 128 is used.

N80 reduced Gaussian grid monthly means:

 type=fc, stream=mo, repres=gg, levtype=sfc, time=00/06/12/18, 
step=06, param=136/137/139/140/141/142/143/144/145/146/147/151/164/ 165/166/167/168/169/170/171/175/176/177/178/179/180/ 
181/182/183/184/186/187/188/195/196/197/198/205/235/ 236/237/239/240/246/247/249,

N80 reduced Gaussian grid monthly standard deviations:

 type=fc, 
stream=mv, repres=gg, levtype=sfc, time=00/06/12/18, step=06, param=136/137/139/140/141/142/143/144/145/146/147/151/164/ 
165/166/167/168/169/170/171/175/176/177/178/179/180/ 181/182/183/184/186/187/188/195/196/197/198/205/235/ 
236/237/239/240/246/247/249,

4.6 Single level forecast data - steps 06, 12, and 24

In the following GRIB code table 2 version 160 is used.

N80 reduced Gaussian grid monthly means of daily means:

 type=fc, 
stream=moda, repres=gg, levtype=sfc, step=nn, param=136/137/139/140/141/151/164/165/166/167/168/170/171/ 
183/184/186/187/188/198/235/236/237/246,

4.7 Model level forecast data - steps 0, 6, 12, 18, and 24

Note that steps 12, 18, and 24 are available only for time=00 and time=12. GRIB code table 2 version 160 is used.

T106 spherical harmonics monthly means:

 type=fc, stream=mo, repres=sh, levtype=ml, 
time=00/06/12/18, step=nn, param=130/131/132/135/138/155,

T106 spherical harmonics monthly means of daily means:

 type=fc, stream=moda, repres=sh, 
levtype=ml, step=nn, param=130/131/132/135/138/155,

N80 reduced Gaussian grid monthly means:

 type=fc, stream=mo, repres=gg, levtype=, time=00/06/12/18, 
step=nn, param=133/246/247/248,

N80 reduced Gaussian grid monthly means of daily means:

 type=fc, stream=moda, repres=gg, levtype=ml, step=nn, 
param=133/246/247/248,

4.8 Pressure level forecast data

Note that the T106 pressure level data are available for steps 0 and 6 from 00, 06, 12, and 18 UTC, and for steps 12, 18, and 24 from 00 UTC and 12 UTC only.

T106 spherical harmonics monthly means:

 type=an, stream=mo, repres=sh, 
levtype=pl, time=00/06/12/18, step=nn, param=129/130/131/132/135/138/155/157,

T106 spherical harmonics monthly means of daily means:

 type=fc, 
stream=mo, repres=sh, levtype=pl, step=0, param=129/130/131/132/135/138/155/157,

07.02.2002