Difference between revisions of "What is in MARS? - Data types and format"
(Created page with "Back to ECMWF overview[http://muspelheim.nilu.no/w/index.php/ECMWF] '''Data types''' '''REANALYSIS:''' '''ERA-15''' - reanalyses from 12/1978 to 02/1994 - spectral T106 r...") |
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− | Back to | + | Back to [[ECMWF]] overview |
+ | '''Data types''' | ||
+ | |||
+ | |||
+ | == FORECAST DATA == | ||
+ | |||
+ | Operational forecast data. | ||
+ | |||
+ | We receive data for up to 2 days ago (i.e. not forecast forward in time). | ||
+ | |||
+ | == ANALYSIS DATA == | ||
− | |||
+ | The 4D-Var analysis uses the model dynamics and physics to create, over a time window, (currently 12 hours), a sequence of model states that fits as closely as possible with the available observations and background. | ||
+ | |||
+ | The 4D-Var system handles all observational data similarly, including radiances from satellites. It compares the actual observations with what would be expected, given the model fields. For satellite radiances the variational scheme modifies the model fields of temperature, wind, moisture and ozone in such a way that the simulated observations are brought closer to the observed values. | ||
+ | == RE-ANALYSIS DATA == | ||
− | |||
'''ERA-15''' | '''ERA-15''' | ||
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- useful for long term analyses | - useful for long term analyses | ||
+ | |||
+ | |||
+ | '''ERA-CLIM''' | ||
+ | |||
+ | is the new set of reanalysis that will span the entire 20th century (from 1899). Possibly released end of 2013. | ||
+ | |||
+ | See http://www.era-clim.eu/ | ||
+ | |||
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The public ERA-40 data are not the high-resolution data, and the public ERA-Interim data are not including all fields. | The public ERA-40 data are not the high-resolution data, and the public ERA-Interim data are not including all fields. | ||
+ | == OBSERVATIONS == | ||
− | + | The MARS archive also includes observation data. | |
− | |||
− | |||
+ | == DATA FORMAT == | ||
− | + | The forecast/analysis/re-analysis data are in GRidded BInary (GRIB) format. Two different versions are used: | |
− | - GRIB1 | + | ''' - GRIB1''' |
− | - GRIB2 was implemented on 18 May 2011. | + | ''' - GRIB2 was implemented on 18 May 2011.''' |
Information on the GRIB2 migration can be found here http://www.ecmwf.int/products/changes/grib2_migration/index.html | Information on the GRIB2 migration can be found here http://www.ecmwf.int/products/changes/grib2_migration/index.html | ||
+ | |||
+ | |||
+ | The observations are in BUFR format. | ||
+ | |||
+ | |||
+ | == FIELDS IN GRIB == | ||
+ | |||
+ | The fields in the GRIB files are | ||
+ | - Spherical Harmonics for Upper-Air fields | ||
+ | - Gaussian Grid for Surface Fields | ||
+ | - Latitude/Longitude for wave and ocean products. | ||
+ | |||
+ | When retrieving fields, one can interpolate from spherical harmonics to a lat/long, Regular Gaussian or Reduced Gaussian grid. |
Latest revision as of 11:23, 4 April 2014
Back to ECMWF overview
Data types
Contents
FORECAST DATA
Operational forecast data.
We receive data for up to 2 days ago (i.e. not forecast forward in time).
ANALYSIS DATA
The 4D-Var analysis uses the model dynamics and physics to create, over a time window, (currently 12 hours), a sequence of model states that fits as closely as possible with the available observations and background.
The 4D-Var system handles all observational data similarly, including radiances from satellites. It compares the actual observations with what would be expected, given the model fields. For satellite radiances the variational scheme modifies the model fields of temperature, wind, moisture and ozone in such a way that the simulated observations are brought closer to the observed values.
RE-ANALYSIS DATA
ERA-15
- reanalyses from 12/1978 to 02/1994
- spectral T106 resolution with 31 vertical hybrid levels
ERA-40
- reanalyses from mid-1957 to 2001
- T159 spectral resolution with 60 vertical levels
ERA-interim
- reanalyses from 01/1979 up to 3 months ago
- T255 spectral resolution with 60 vertical levels
- corrected for different models so should be consistent
- useful for long term analyses
ERA-CLIM
is the new set of reanalysis that will span the entire 20th century (from 1899). Possibly released end of 2013.
The Re-analysis data are publicly available via http://data-portal.ecmwf.int
One does not need to be an authorized user but only register.
The public ERA-40 data are not the high-resolution data, and the public ERA-Interim data are not including all fields.
OBSERVATIONS
The MARS archive also includes observation data.
DATA FORMAT
The forecast/analysis/re-analysis data are in GRidded BInary (GRIB) format. Two different versions are used:
- GRIB1
- GRIB2 was implemented on 18 May 2011.
Information on the GRIB2 migration can be found here http://www.ecmwf.int/products/changes/grib2_migration/index.html
The observations are in BUFR format.
FIELDS IN GRIB
The fields in the GRIB files are
- Spherical Harmonics for Upper-Air fields - Gaussian Grid for Surface Fields - Latitude/Longitude for wave and ocean products.
When retrieving fields, one can interpolate from spherical harmonics to a lat/long, Regular Gaussian or Reduced Gaussian grid.