Ms-global-atmospheric-composition-forecasts incomplete download

Datasets and Usage CAMS - Datasets and Usage
1

i downloaded a dataset from “ms-global-atmospheric-composition-forecasts”, here is what the API server indicated to me as a python script following an online request to obtain the classic air pollution data.

dataset = “cams-global-atmospheric-composition-forecasts”
request = {
“variable”: [
“particulate_matter_2.5um”,
“particulate_matter_10um”,
“nitrogen_dioxide”,
“ozone”
],

You see I ask for 4 variables. But in the end I get after downloading a Netcdf file with two variables(pm25 & pm10) and not 4.
Another question: are these variables at ground level?

Thank you.

2

Hi Ronald,

NO2 and O3 are multi-level variables, so they’ll only appear in the output file if you select some model or pressure levels to retrieve them on. Use model_level 137 to get the surface values.

Luke.

3

Thank you

So :
request = {
“variable”: [
“particulate_matter_2.5um”,
“particulate_matter_10um”,
“nitrogen_dioxide”,
“ozone”
],
“model_level”: [“137”],

Will download these 4 variables for surface values ?

4

Yes, that should give you all four. Particulate matter is only available at the surface, so that doesn’t need a level, but NO2 and O3 do.

5

that did not work.

`Preformatted text


`dataset = "cams-global-atmospheric-composition-forecasts"
    request = {
        "variable": [
            "particulate_matter_2.5um",
            "particulate_matter_10um",
            "ozone",
            "nitrogen_dioxide"
        ],
        "model_level": ['137'],
        "date": [t],
        "time": ["00:00"],`

gave me only pm2.5 and pm10 variables.
 EDIT: my error, I cet a zip file, with 2 NC , the 2nd has NO2 and O3. 
But its forecast period :  forecast_period = 0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42,
    45, 48, 51, 54, 57, 60, 63, 66, 69, 72, 75, 78, 81, 84, 87, 90, 93, 96,
    99, 102, 105, 108, 111, 114, 117, 120 ;