Acronyms
Introduction
The CAMS Radiation Service is designed to meet the requirements that have been specified for the Copernicus Atmosphere Monitoring Service (CAMS). The precursor projects MACC and MACC-II/-III prepared the CAMS Radiation Service in terms of implementation, sustained operation and availability. It was ensured that the service lines have been designed to best meet both the requirements of downstream service providers and end users at the European, national and local levels, and the requirements of the global scientific user community. This page provides a high level overview of the solar radiation service; more details can be found in the Section Detailed documentation.
Solar radiation service
The CAMS solar radiation services provide historical values (2004 to present) of global (GHI), direct (BHI) and diffuse (DHI) solar irradiation, as well as direct normal irradiation (BNI). The aim is to fulfil the needs of European and national policy development and the requirements of both commercial and public downstream services, e.g. for planning, monitoring, efficiency improvements and the integration of solar energy systems into energy supply grids.
For clear-sky conditions, an irradiation time series is provided for any location in the world using information on aerosol, ozone and water vapour from the CAMS global forecasting system. Other properties, such as ground albedo and ground elevation, are also taken into account. Similar time series are available for cloudy conditions but, since the high-resolution cloud information is directly inferred from satellite observations, these are currently only available inside the field-of-view of the Meteosat Second Generation (MSG) satellite, which is roughly Europe, Africa, the Atlantic Ocean and the Middle East.
Input quality control, regular quarterly benchmarking against ground stations, and regular monitoring the consistency and detecting possible trends is performed.
Detailed documentation
A detailed User Guide is available here: User Guide to the CAMS Radiation Service (CRS)
Evaluation and Quality Assurance reports
Quarterly reports are made routinely available on the CAMS web page.
Data products
Data is offered via the Copernicus Atmosphere Data Store (ADS) in both ASCII and NetCDF format.
Additionally, an ASCII "expert mode" format can be selected which contains in addition to the irradiation, all the input data used in their calculation (aerosol optical properties, water vapour concentration, etc). This additional information is only meaningful in the time frame at which the calculation is performed and so is only available at 1-minute time steps in universal time (UT).
Table 1: Overview of key characteristics
| Clear-Sky (McClear) | All-Sky (Heliosat-4) |
| ADS name | Cloud-free conditions only | Both cloud-free and actual weather conditions |
Type of product | Point data, time-series | |
Parameters | GHI, DHI, BHI, BNI | |
Geographical area | global | Europe / Africa / Middle East / Atlantic Ocean |
Horizontal resolution | Interpolated to point of interest from various spatial input data resolutions | |
Time coverage | from 2004-01-01 to | from 2004-02-01 to |
Temporal resolution | 1 min, 15 min, 1 h, 1 day, 1 month | |
Data format | ASCII (CSV), NetCDF | |
Data file size | File size depends on the temporal resolution. Largest files are in 1 min temporal resolution and the CSV data format | |
Data access | ||
Processing | on request; data normally available within a few minutes | |
Update of the databases | 2 days delayed mode | |
The CAMS Radiation Service CSV formatted products are presented as a metadata header section, followed by lines of values (columns). The metadata header section helps the user to understand the data, and describing the various features of the products. These metadata are written as text in the delivered file, and conform to the ISO standard where available. Currently these metadata are:
- title: title of the time-series, e.g., “CAMS Radiation Service v3.2 all-sky irradiation (derived from satellite data)”,
- content: a short description of the content of the product, e.g., “A time-series of solar radiation received on horizontal plane and plane always normal to the sun rays at ground level.”,
- provider: name of the provider, e.g., “MINES ParisTech (France)”,
- date begin, date end: dates of the beginning and end of the period. The date follows the ISO 8601 standard, e.g. 2004-01-01T01:00:00.000.
- site latitude and longitude: geographical coordinates of the site, positive North and positive Earth. The ISO 19115 standard is used,
- elevation: elevation above sea level in m,
- time reference: time system used: Universal Time (UT), or True Solar Time (TST). This metadata is present only when the period of integration is less than 1 day,
- summarization: period during which the energy is summed up to obtain a power average, e.g., 15 min,
- sampling rate: period with which the resulting irradiation is sampled. Usually, the sampling rate is set equal to summarization,
- noValue: the code denoting the absence of value, e.g. NaN (not a number).The content of each column is described as a free text.
Each line corresponds to an instance of output observation data for a given period. The typical content of a line is:
- instance of output observation data for a given period,
- irradiation at the top of the atmosphere,
- clear-sky irradiation value at ground level, e.g. Clear Sky GHI
- all-sky irradiation value at ground level, e.g., GHI,
- reliability code, ranging from 0 to 1. The exact content of a line depends on the type of product and the description is provided in the metadata. This is why metadata are included in the file header as plain text.
Standard output variables
| Main Variable Names | NetCDF Units | Description |
|---|---|---|
| BHI | Wh m-2 | Direct horizontal all sky irradiation, i.e., the direct part of the surface solar downward irradiation integrated over the whole spectrum available at ground level, on a horizontal surface |
| BNI | Wh m-2 | Direct normal all sky irradiation. Part of the radiation that is received from the direction of the sun by a plane facing the sun. |
| DHI | Wh m-2 | Diffuse horizontal all sky irradiation, i.e., the diffuse part of the surface solar downward irradiation integrated over the whole spectrum available at ground level, on a horizontal surface. |
| GHI | Wh m-2 | Global horizontal all sky irradiation, i.e., the surface solar downward irradiation integrated over the whole spectrum available at ground level, on a horizontal surface. |
| BHIc | Wh m-2 | Direct horizontal clear sky irradiation |
| BNIc | Wh m-2 | Direct normal clear sky irradiation. |
| DHIc | Wh m-2 | Diffuse horizontal clear sky irradiation |
| GHIc | Wh m-2 | Global horizontal clear sky irradiation |
Expert mode variables
For expert users, all input and output variables are provided in the ‘detailed info expert output mode’. It can only be retrieved when requesting 1 min resolved time series from the Atmosphere Data Store. Besides the standard outputs, it provides:
- Irradiation on a horizontal plane at the top of atmosphere
- Clear sky irradiation values:
- Clear sky GHI. Clear sky global irradiation on a horizontal plane at ground level
- Clear sky BHI. Clear sky direct (beam) irradiation on a horizontal plane at ground level
- Clear sky DHI. Clear sky diffuse irradiation on a horizontal plane at ground level
- Clear sky BNI. Clear sky direct (beam) irradiation on a mobile plane at normal incidence following the sun
- All sky irradiation values:
- All sky GHI. Clear sky global irradiation on horizontal plane at ground level
- All sky BHI. Clear sky direct (beam) irradiation on horizontal plane at ground level
- All sky DHI. Clear sky diffuse irradiation on horizontal plane at ground level
- All sky BNI. Clear sky direct (beam) irradiation on mobile plane at normal incidence following the sun
- Solar zenith angle for the middle of the summarization (deg)
- Atmospheric profile code: afglus=U.S. standard, afglt=tropical, afglms=midlatitude summer, afglmw=midlatitude winter, afglss=subarctic summer, afglsw=subarctic winter
- Total column content of ozone (Dobson unit)
- Total column content of water vapour (kg/m2)
- AOD BC. Partial aerosol optical depth at 550 nm for black carbon
- AOD DU. Partial aerosol optical depth at 550 nm for dust
- AOD SS. Partial aerosol optical depth at 550 nm for sea salt
- AOD OR. Partial aerosol optical depth at 550 nm for organic matter
- AOD SU. Partial aerosol optical depth at 550 nm for sulphate
- AOD NI. Partial aerosol optical depth at 550 nm for nitrate. This quantity was introduced in July 2019 and will have zero values before – indicating unavailability.
- AOD AM. Partial aerosol optical depth at 550 nm for ammonium. This quantity was introduced in July 2019 and will have zero values before – indicating unavailability.
- Deprecated and replaced by AOD NI: AOD 550. Aerosol optical depth at 550 nm
- Deprecated and replaced by AOD AM: AOD 1240. Aerosol optical depth at 1240 nm
- Deprecated, but kept for format consistency: alpha Ångström coefficient for aerosol. It is set to zero values.
- Deprecated, but kept for format consistency: Aerosol type. Type of aerosol: -1=no value, 5=urban, 7=continental clean, 8=continental polluted, 9=continental average 10=maritime clean, 11= maritime polluted, 12=maritime tropical, 13=antarctic, 14=desert
- MODIS-like BRDF (bidirectional reflectance distribution function) parameter fiso
- MODIS-like BRDF (bidirectional reflectance distribution function) parameter fvol
- MODIS-like BRDF(bidirectional reflectance distribution function) parameter fgeo
- Ground albedo
- Cloud optical depth (value of the nearest acquisition time of the pixel, not interpolated over time)
- Cloud coverage of the pixel (percentage from 0 to 100, value of the nearest acquisition time of the pixel, not interpolated over time)
- Cloud type (value of the nearest acquisition time of the pixel, not interpolated over time) -1=no value, 0=no clouds, 5=low-level cloud, 6=medium-level cloud, 7=high-level cloud, 8=thin cloud
- non-bias corrected all-sky radiation values
- non-corrected all sky GHI. Clear sky global irradiation on horizontal plane at ground level
- non-corrected all sky BHI. Clear sky direct (beam) irradiation on horizontal plane at ground level
- non-corrected all sky DHI. Clear sky diffuse irradiation on horizontal plane at ground level
- non-corrected all sky BNI. Clear sky direct (beam) irradiation on mobile plane at normal incidence, following the sun
Users may:
- make use of this information to establish an extended bias correction based on their own localised ground observations;
- use this transparency about all input parameters to run their own solar radiation retrieval schemes;
- contribute easily to evaluation and method development of Heliosat‑4 by having access to all input variables;
- develop downstream services by making use of the knowledge of all input parameters e.g. in artificial intelligence methods
Note should be taken that the content of the detailed info mode may change depending on the version of Heliosat‑4 or McClear. Each product contains a detailed description of its content and the user should refer to it.
Known issues and version updates
| Date | Version | Description |
2022-09 | v4.5 (current) | New version of the all-sky model. Version 4.5 uses a new clear sky model (McClear 3.5) and no bias correction anymore. The clear-sky model McClear 3.5 uses now the CAMS Reanalysis for 2004-2020. |
2021-06 | v4.0 | Since 2013, CAMS Radiation service used the cloud retrieval scheme APOLLO. The version 4.0 of CAMS Radiation Service includes a new version APOLLO Next Generation (APOLLO_NG) that improves cloud detection using fuzzy logic. Fix in the MSG satellite projection handling for all data before 12/2017. A new global bias correction was implemented. |
2018-06 | v3.2 | Fix of a mathematical bug in the (latitude, longitude) position of the pixels of the Meteosat satellite images. |
2018-03 | v3.1 | CAMS McClear benefits from the successive enhancements of the Aerosol Optical Depth versions. McClear version, and consequently CAMS radiation service version as well, have been incremented from 3.0 to 3.1. Results are slightly modified in October 2012 and September-November 2015. |
2017-10 | v3 | McClear clear sky model v3 |
2015-10 | v2.7 | McClear v2.7 |
2015-07 | v2.6 | Bug fixed in verbose expert mode |
2015-02 | v2.6 | Bug fixed in the filling of MACC AOD databases |
2015-01 | v2.6 | Bug fixed bug for cloud coverage > 100% |
2014-11 | v2.5 | APOLLO data coverage extension: 2004-02-01 to D-2 |
2014-11 | v2.4 | Call to McClear v2.4 |
2014-08 | v2.3 | Call to McClear v2.3 Bug fixed in APOLLO data interpolation |
v2.2 | does not exist (synchronization with McClear versions) | |
2014-07 | v2.1 | Bug fixed for the shift of one pixel in APOLLO files import |
2013-07 | v2.0 | Edition format file version 1 |
How to acknowledge and cite the data
The use of the CAMS Radiation Service data should be acknowledged as indicated below:
All users of data uploaded from the Atmosphere Data Store (ADS) must:
(1) provide clear and visible attribution to the Copernicus programme by citing the web catalogue page:
CAMS solar radiation time-series. Copernicus Atmosphere Monitoring Service (CAMS) Atmosphere Data Store (ADS). (Accessed on DD-MMM-YYY), https://ads.atmosphere.copernicus.eu/cdsapp#!/dataset/cams-solar-radiation-timeseries?tab=overview
(2) acknowledge according to the data licence (i.e. licence to use Copernicus products (Clause 5 in particular)
(3) Cite the relevant peer-review publication for the the CAMS-Radiation Service:
Qu, Z., Oumbe, A., Blanc, P., Espinar, B., Gesell, G., Gschwind, B., Klüser, L., Lefèvre, M., Saboret, L., Schroedter-Homscheidt, M., and Wald L.: Fast radiative transfer parameterisation for assessing the surface solar irradiance: The Heliosat-4 method, Meteorol. Z., 26, 33-57, doi: 10.1127/metz/2016/0781,2017. Available for download at https://www.schweizerbart.de/papers/metz/detail/26/87036/Fast_radiative_transfer_parameterisation_for_asses?af=crossref.
Schroedter-Homscheidt, M., Azam, F., Betcke, J., Hanrieder, N., Lefèvre, M., Saboret, L., Saint-Drenan, Y.-M.: Surface solar irradiation retrieval from MSG/SEVIRI based on APOLLO Next Generation and HELIOSAT-4 methods, Contrib. Atm. Sci./Meteorol. Z.,2022, doi:10.1127/metz/2022/1132.
and for the CAMS clear-sky time series:
Gschwind, B., Wald L., Blanc, P., Lefèvre, M., Schroedter-Homscheidt, M., Arola, A., 2019. Improving the McClear model estimating the downwelling solar radiation at ground level in cloud free conditions – McClear-V3., Meteorol. Z./Contrib. Atm. Sci., 28, 2, 147-163, doi:10.1127/metz/2019/0946. Available for download at https://www.schweizerbart.de/papers/metz/detail/28/90593/Improving_the_McClear_model_estimating_the_downwelling_solar_radiation_at_ground_level_in_cloud_free_conditions_McClear_v3
Lefèvre, M., Oumbe, A., Blanc, P., Espinar, B., Gschwind, B., Qu, Z., Wald, L., Schroedter-Homscheidt, M., Hoyer-Klick, C., Arola, A., Benedetti, A., Kaiser, J., W., and Morcrette, J.-J.: McClear: a new model estimating downwelling solar radiation at ground level in clear-sky conditions, Atmos. Meas. Tech., 6, 2403–2418, doi: 10.5194/amt-6-2403-2013, 2013. Available for download at http://www.atmos-meas-tech.net/6/2403/2013/amt-6-2403-2013.pdf
References
Gschwind, B., Wald L., Blanc, P., Lefèvre, M., Schroedter-Homscheidt, M., Arola, A., 2019. Improving the McClear model estimating the downwelling solar radiation at ground level in cloud free conditions – McClear-V3., Meteorol. Z./Contrib. Atm. Sci., 28, 2, 147-163, doi:10.1127/metz/2019/0946. Available for download at https://www.schweizerbart.de/papers/metz/detail/28/90593/Improving_the_McClear_model_estimating_the_downwelling_solar_radiation_at_ground_level_in_cloud_free_conditions_McClear_v3
Lefèvre, M., Oumbe, A., Blanc, P., Espinar, B., Gschwind, B., Qu, Z., Wald, L., Schroedter-Homscheidt, M., Hoyer-Klick, C., Arola, A., Benedetti, A., Kaiser, J., W., and Morcrette, J.-J.: McClear: a new model estimating downwelling solar radiation at ground level in clear-sky conditions, Atmos. Meas. Tech., 6, 2403–2418, doi: 10.5194/amt-6-2403-2013, 2013. Available for download at http://www.atmos-meas-tech.net/6/2403/2013/amt-6-2403-2013.pdf
Qu, Z., Oumbe, A., Blanc, P., Espinar, B., Gesell, G., Gschwind, B., Klüser, L., Lefèvre, M., Saboret, L., Schroedter-Homscheidt, M., and Wald L.: Fast radiative transfer parameterisation for assessing the surface solar irradiance: The Heliosat-4 method, Meteorol. Z., 26, 33-57, doi: 10.1127/metz/2016/0781,2017. Available for download at https://www.schweizerbart.de/papers/metz/detail/26/87036/Fast_radiative_transfer_parameterisation_for_asses?af=crossref.
Schroedter-Homscheidt, M., Azam, F., Betcke, J., Hanrieder, N., Lefèvre, M., Saboret, L., Saint-Drenan, Y.-M.: Surface solar irradiation retrieval from MSG/SEVIRI based on APOLLO Next Generation and HELIOSAT-4 methods, Contrib. Atm. Sci./Meteorol. Z.,2022, doi:10.1127/metz/2022/1132.
