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These are shown in the following figures:
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| Figure 1: Web interface | Figure 2: Request options on the web interface |
2) The CDS API is a service providing programmatic access in Python to ADS data. Users need to have a CDS account to use it with their related CDS API credentials. For a full description and some useful examples, please see How to use the CDS API.
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Please note that cached data (if present) is used to fulfill an ADS request only if the ADS request is exactly identical to a previous one. This means that data will be extracted from the cache, rather than being re-retrieved from the dataset itself.
The ADS data availability information is now available through REST API:
https://ads.atmosphere.copernicus.eu/api/catalogue/v1/docs
Here is a sample data availability request:
| Code Block |
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curl -X 'GET' \
'https://ads.atmosphere.copernicus.eu/api/catalogue/v1/collections/cams-europe-air-quality-forecasts/constraints.json' \
-H 'accept: application/json' |
Request states
After sending a request, the user can track its state on the 'Your Requests' page of the ADS web interface. There are five different states of a request:
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Table 1: Summary of the number of fields limits, as well as the major features of all ADS datasets (last reviewed on )
| Dataset | Number of fields limit | Volume size limit | Adaptor (indicates where the data are stored; see "Efficiency Tips" below) | Notes |
| 10000 | 175 GB for GRIB files, 30 GB for netCDF files | MARS Internal/external | Those variables listed as fast-access are readily available from ADS disks. Those variables listed as slow-access and data older than 30 days are stored in ECMWF MARS tape archive. | |
| 100000 | 175 GB for GRIB files, 30 GB for netCDF files | MARS Internal/external | Those variables listed as fast-access are readily available from ADS disks. Those variables listed as slow-access are stored in ECMWF MARS tape archive. | |
| 100000 | 175 GB for GRIB files, 30 GB for netCDF files | MARS Internal | N/A | |
CAMS global inversion-optimised greenhouse gas fluxes and concentrations | 500 | N/A | adaptor.url | Stored locally on ADS disks |
| 100000 | 175 GB for GRIB files, 30 GB for netCDF files | MARS external | Data are stored in ECMWF MARS tape archive | |
CAMS global greenhouse gas reanalysis (EGG4) monthly averaged fields | 100000 | 175 GB for GRIB files, 30 GB for netCDF files | MARS external | Data are stored in ECMWF MARS tape archive |
| 10000 | N/A | adaptor.cams_solar_rad2.retrieve | This data is calculated on demand by a service jointly provided by DLR, Armines, and Transvalor. The ADS forwards requests to this service and returns the data from it. | |
| 10000 | N/A | adaptor.cams_solar_rad2.retrieve | This data is calculated on demand by a service jointly provided by DLR, Armines, and Transvalor. The ADS forwards requests to this service and returns the data from it. | |
| 5000 | N/A | adaptor.cams_regional_fc.retrieve | There are three classes of speed at which these requests will be processed:
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| 1000 | N/A | adaptor.url | Check the documentation for data availability | |
CAMS European air quality forecasts optimised at observation sites | 1000 | N/A | adaptor.url | |
| 1000 | N/A | adaptor.url2.retrieve | N/A | |
CAMS global biomass burning emissions based on fire radiative power (GFAS) | N/A | N/A | N/A | |
| 1000 | N/A | adaptor.url | ||
| 1000 | N/A | adaptor.url |
Efficiency tips
- Where the data are actually stored can make a significant difference in the speed at which a request is processed. ADS data hosted in 'MARS internal' is stored on ADS disks, and so is faster to retrieve. The 'MARS external' datasets are stored in the ECMWF MARS (tape) archive, and in this case it is important to request as much data as possible from the same tape file in your ADS request.
- It is better to submit small requests rather than very large requests. This will ensure your requests are not given a lower priority in the ADS request queue.
- When using the CDS API, it is strongly recommended that users take as a starting point the example API request script shown at the bottom of the ADS web 'Download data' page for the dataset of interest, and use this as the basis for your request.
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