Here we document the CAMS reanalysis dataset, which, eventually, will cover the period January 2003 to near real time (NRT), though currently only data for the period 2003-2018 have been released. The CAMS reanalysis is the latest global reanalysis data set of atmospheric composition (AC) produced by the Copernicus Atmosphere Monitoring Service, consisting of 3-dimensional time-consistent AC fields, including aerosols, chemical species and greenhouse gases, though GHG fields will only be released in 2019. The data set builds on the experience gained during the production of the earlier MACC reanalysis and CAMS interim reanalysis.
The CAMS reanalysis was produced using 4DVar data assimilation in CY42R1 of ECMWF’s Integrated Forecast System (IFS), with 60 hybrid sigma/pressure (model) levels in the vertical, with the top level at 0.1 hPa. Atmospheric data are available on these levels and they are also interpolated to 25 pressure, 10 potential temperature and 1 potential vorticity level(s). "Surface or single level" data are also available.
Generally, the data are available at a sub-daily and monthly frequency and consist of analyses and 48h forecasts, initialised daily from analyses at 00 UTC.
The data are archived in the ECMWF data archive (MARS) and can be retrieved using the ECMWF Public Dataset service via the WebAPI (ECMWF Member State users can access the data using MARS directly, in the usual manner).
The 4DVar data assimilation uses 12 hour assimilation windows from 09 UTC to 21 UTC and 21 UTC to 09 UTC.
The IFS model documentation for various model cycles can be found on https://www.ecmwf.int/en/forecasts/documentation-and-support/changes-ecmwf-model/ifs-documentation. The model used in the CAMS reanalysis includes several updates to the aerosol and chemistry modules on top of the standard CY42R1 release, which are listed below. Please note that 42r1 documentation is not available on the page, but the code for the earlier and later cycles is available for reference.
The chemical mechanism of the IFS is an extended version of the Carbon Bond 2005 (CB05) chemical mechanism as implemented in CTM Transport Model 5 (TM5). In the CAMS reanalysis the model as documented in Flemming et al. (2015) and Flemming et al. (2017) is used with the following updates:
The model configuration for greenhouse gases is based on the specification of the following components documented in the listed papers below:
The emissions datasets used to produce the CAMS reanalysis are listed in Table 1. They include the MACCity anthropogenic emission, GFAS fire emissions, MEGAN biogenic emissions and several GHG emission datasets.
Table 1: Emission datasets used in the CAMS reanalysis
|MACCity anthropognic emissions||MACCity (trend: ACCMIP + RCP8.5) & CO emission upgrade Stein et al. (2014)|
|Dry deposition||Sumo dry deposition|
|VOC emissions||Monthly mean VOC emissions calculated by the MEGAN model using MERRA reanalysed meteorology (Sindelarova et al., 2014)|
|CO2 ocean fluxes||Takahashi et al. (2009) climatology|
|CO2 emissions from aviation||Based on ACCMIP NO emissions from aviation scaled to annual total CO2 from EDGAR aviation emissions.|
CO2 ecosystem fluxes
bias corrected with BFAS
|Based on CHTESSEL (modelled online in C-IFS)|
|CO2 anthropogenic emissions||EDGARv4.2FT2010 (2003-2010)|
|CH4 wetland emissions||LPJ-HYMN climatology (Spanhi et al., 2011)|
|CH4 total emissions||based on EDGARv4.2FT2010 , LPJ-HYMN wetland climatology and other natural sources/sinks (2003-2010)|
|CH4 chemical sink||based on Bergamaschi et al. (2009) dataset|
|CH4 anthropogenic emissions||EDGARv4.2FT2010 (2003-2010)|
Users with access to MARS can also browse the data on the MARS catalogue under class=mc and expver=eac4.
The CAMS reanalysis data have a resolution of approximately 80 km. The data are available either as spectral coefficients with a triangular truncation of T255 or on a reduced Gaussian grid with a resolution of N128. These grids are so called "linear grids", sometimes referred to as TL255.
For sub-daily data for the CAMS reanalysis (stream=oper) the analyses (type=an) are available 3-hourly. The daily forecast, run from 00 UTC, has 3-hourly steps from 0 to 48 hours for the 3D model level and pressure level fields, and hourly steps from 0 to 48 hours for the surface fields.
Several parameters are also available as synoptic monthly means, for each particular time and forecast step (stream=mnth) and as monthly means of daily means, for the month as a whole (stream=moda).
Monthly means for analyses and instantaneous forecasts are created from data with a valid time in the month, between 00 and 23 UTC, which excludes the time 00 UTC on the first day of the following month. Monthly means for accumulations and mean rates are created from data with a forecast period falling within the month. For example, monthly means of daily means for accumulations and mean rates are created from contiguous data with forecast periods spanning from 00 UTC on the first day of the month to 00 UTC on the first day of the following month.
Model level fields are in GRIB2 format. All other fields are in GRIB1, unless otherwise indicated.
Pressure levels: 1000/950/925/900/850/800/700/600/500/400/300/250/200/150/100/70/50/30/20/10/7/5/3/2/1
Potential temperature levels: 300/315/320/330/350/370/395/475/600/850
Potential vorticity level: 2000
Model levels: 1/to/60, which are described at https://www.ecmwf.int/en/forecasts/documentation-and-support/60-model-levels.
The archive of available parameters can be browsed here.
The atmospheric composition satellite retrievals used as input into the CAMS reanalysis are listed below. The following abbreviations are used in Table 1. TC: Total column, TRC: Tropospheric column, PROF: profiles, PC: Partial columns, ColAv: Column average mixing ratio, QR= quality flag given by data providers, SOE: Solar elevation, MODORO: Model orography, PRESS_RL= pressure at bottom of layer, LAT: Latitude.
Validation Reports for the CAMS reanalysis can be found on the CAMS Quality Assurance website.
The following advice is intended to help users understand particular features of the CAMS reanalysis data:
At the time of writing (2017-11) we are aware of these issues with the CAMS reanalysis:
The use of the NOx variable from the CAMS reanalysis (as well as from the CAMS interim re-analysis and the CAMS operational system) is not recommended. The user is advised to download NO and NO2 separately and to add them up. Please note that a conversion of the mass mixing ratios [kg/kg] to volume mixing rations / molar fractions [mol/mol] is needed to do this in a meaningful way.
This list will be updated as we become aware of further issues in the CAMS reanalysis.
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An ECMWF newsletter article 'The new CAMS global reanalysis of atmospheric composition' is available from: https://www.ecmwf.int/node/18821
To be kept informed of the latest news associated to the CAMS Reanalysis products, you may subscribe to the CAMS Global Reanalysis mailing list.