Differences between SO2 and tcSO2

Datasets and Usage CAMS - Datasets and Usage
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1

Hello, 
I am quite new to atmospheric data andI am working with CAMS reanalysis data to do my diploma thesis. I noticed there are two different parameters for SO2 (but the same for CO, NO2, O3..)
I would like to know what is the difference between Sulphur dioxide (kg kg^-1) and Total column Sulphur dioxide kg m^-2. 
The first mentioned can be found in CAMS Model levels, second one is from CAMS surface level. 

Is there any good documentation of the parameters from CAMS reanalysis (except of https://apps.ecmwf.int/codes/grib/param-db) 

Thank you very much for your help!
K

2

Hi,

Total column (in kg m-2) is available at the surface (model level 60 for MARS users). Total column refers to the total amount of the selected variable in a column of air extending from the surface of the Earth to the top of the atmosphere (model level 1 for MARS users). Total column can also be referred to as total <selected variable>, or vertically integrated <selected variable>.

Thanks

Michela

3

Hello,

I have he same question and I am puzzled by the answer. From Michela’s answer the two variables aermssso2 (Vertically integrated mass of sulphur dioxide) and tcso2 (Total column Sulphur dioxide) should be the same. However, they aren’t. I downloaded both variables from ECA4. Here is the difference plot for July 2025.

image
image1374×611 179 KB

Obviously, both variables are not the same. So what is their difference?

With kind regards,

Andreas Sterl

4

Dear Andreas,
thanks for your comment. Could you please share how you downloaded aermssso2? I can only see vertically integrated mass of sulphate aerosol (aermsssu) on the EAC4 form

image
image871×638 21.5 KB

Thanks

5

Dear Michela,

The API request I used is

dataset = "cams-global-reanalysis-eac4-monthly"
request = {
    "variable": [
        "2m_temperature",
        "total_aerosol_optical_depth_550nm",
        "total_column_sulphur_dioxide",
        "vertically_integrated_mass_of_sulphur_dioxide"
    ],
    "year": ["2025"],
    "month": [
        "01", "02", "03",
        "04", "05", "06",
        "07", "08", "09",
        "10", "11", "12"
    ],
    "product_type": ["monthly_mean"],
    "data_format": "netcdf",
    "download_format": "unarchived"

}

Regards,
Andreas
6

Additional info:

I used CAMS global reanalysis (EAC4) monthly averaged fields to generate the API