We are using the CAMS near real time data for a wildfire application. In the old interface we always had the option to select a finer grid size of the data (0.125°x0.125° was used). In the new interface there is no such option and the user is tied to a more coarse resolution (I think per defualt 0.4°x0.4°).

Can users still access the higher reoluted data? If nor, is it planned to re-add the grid size option to the new ADS web interface?

Is it possible to access the full resolution of the data (0,125°x0,125°) through the python api?

Thank you very much in advance!

4 Comments

  1. Kevin Marsh

    Hi Mohamad,

    The CAMS Global atmospheric composition forecasts data available from the ADS has been pre-interpolated to a regular 0.4°x 0.4° latitude/longitude grid. The keyword 'grid' is not supported in CDS API requests on the ADS.

    See CAMS: Global atmospheric composition forecast data documentation for full details of this dataset,

    Thanks,

    Kevin

  2. Marine Benchmark

    Hello. I have a follow-up question regarding the re-gridding.

    What is the best way of re-gridding the ADS provided 0.4 x 0.4 into 0.25 x 0.25 grid we use?

    It's really hard to find any good answers for re-gridding. We're not a computer-savvy enough output to figure out the arcane commands for CDO and their brothers.


  3. Kevin Marsh

    HI Marine,

    I'd say that CDO is a good option for this regridding - do you have the details of the grid you want? do you have CDO installed?

    (Note that regridding to a higher resolution does not add any 'extra' information to the data)  

    Thanks

    Kevin

  4. Marine Benchmark

    Hi, and thanks for the answer!

    I've found this so far:

    cdo -v remapnn,r1440x720 ECMWF_CAMS_dust_aerosol_optical_depth_550nm2022011212.grib ECMWF_CAMS_dust_aerosol_optical_depth_550nm2022011212_remapped.grib

    This "seems" to work, but creates a grid from (-89.875, -180) to (89,875, 179,75), with 0.25-steps. I guess it means that value is in the "middle" of a 0.25x0.25 point?

    We would like to match the output of (-90, -180) to (90, 179.75) that ERA5 weather files generates, where the value is the lower left point.

    But perhaps it's as simple as substracting -0.125 from the latitude?

    Another question, is if "nn" - nearest neighbour is the correct algorithm to use for the various CAMS values?

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