# Ms-global-atmospheric-composition-forecasts incomplete download

**URL:** <https://forum.ecmwf.int/t/ms-global-atmospheric-composition-forecasts-incomplete-download/11148>\
**Category:** CAMS - Datasets and Usage\
**Tags:** cams\_global\_forecast\
**Created:** [3 February 2025 09:11 UTC](https://forum.ecmwf.int/t/ms-global-atmospheric-composition-forecasts-incomplete-download/11148 "2025-02-03T09:11:33Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![Ronald\_Van\_Assche](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/r/bb73d2/32.png) [@Ronald\_Van\_Assche](https://forum.ecmwf.int/u/Ronald_Van_Assche)\
**Post date:** [3 February 2025 09:11 UTC](https://forum.ecmwf.int/t/ms-global-atmospheric-composition-forecasts-incomplete-download/11148/1 "2025-02-03T09:11:33Z")

</div>

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.

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<div class="post-metadata">

**Author:** ![Luke\_Jones](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/l/e0b2c6/32.png) [@Luke\_Jones](https://forum.ecmwf.int/u/Luke_Jones)\
**Post date:** [7 February 2025 17:11 UTC](https://forum.ecmwf.int/t/ms-global-atmospheric-composition-forecasts-incomplete-download/11148/2 "2025-02-07T17:11:11Z")

</div>

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.

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<div class="post-metadata">

**Author:** ![Ronald\_Van\_Assche](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/r/bb73d2/32.png) [@Ronald\_Van\_Assche](https://forum.ecmwf.int/u/Ronald_Van_Assche)\
**Post date:** [7 February 2025 17:32 UTC](https://forum.ecmwf.int/t/ms-global-atmospheric-composition-forecasts-incomplete-download/11148/3 "2025-02-07T17:32:34Z")

</div>

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 ?

---

<div class="post-metadata">

**Author:** ![Luke\_Jones](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/l/e0b2c6/32.png) [@Luke\_Jones](https://forum.ecmwf.int/u/Luke_Jones)\
**Post date:** [7 February 2025 17:50 UTC](https://forum.ecmwf.int/t/ms-global-atmospheric-composition-forecasts-incomplete-download/11148/4 "2025-02-07T17:50:44Z")

</div>

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.

---

<div class="post-metadata">

**Author:** ![Ronald\_Van\_Assche](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/r/bb73d2/32.png) [@Ronald\_Van\_Assche](https://forum.ecmwf.int/u/Ronald_Van_Assche)\
**Post date:** [7 February 2025 19:18 UTC](https://forum.ecmwf.int/t/ms-global-atmospheric-composition-forecasts-incomplete-download/11148/5 "2025-02-07T19:18:41Z")

</div>

that did not work.

`Preformatted text

```auto

`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 ;
```