GEM does not calculate or advect aerosols. However, the radiation scheme 'cccmarad' uses a predefined ...
‘cccmarad’ considers the following 5 types of background Aerosol Optical Depth/Thickness (AOD/AOT). ‘cccmarad’ consideres the following 5 types of background aerosols:
- Organic carbon
- Sea salt
- Mineral dust (from deserts)
- Black carbon
- Sulphate
The their AOD can be different for all model levels.
In GEM:
By default, GEM uses hardcoded background Aerosol Optical Depth/Thickness (AOD/AOT).
- Organic carbon only exists over land where it’s AOD goes linearly from 0.25 at the equator to 0.05 at the poles – see image red line in image below
- Sea salt only exists over the ocean where it’s AOD goes linearly from 0.13 at the equator to 0.03 at the poles – see blue line in image below
- Mineral dust, black carbon and sulphate are set to zero everywhere
The background AOD is distributed evenly (in term of meters) over all model levels of the planetary boundary layer.
In CRCM6-GEM5:
In CRCM6-GEM5 we now have one has the possibility of using reading prescribed 2-D background AODs for all 5 types of aerosols, which will then get used by 'cccmarad2'. The fields can vary from one month to the nextin time, but so far only 2-D fields can get used. Although, it should not be that complicated to introduce 3-D fields.
At the moment we only have a pre-industrial monthly AOD climatology from EC-Earth. But if you find others (for example for current and/or future) we can use those as well. For as long as they are AODs for the 5 types of aerosols cccmarad consideres.
See 2-D AOD plots on next slideread. As when using the default AOD, they will be distributed evenly (in term of meters) over all model levels of the planetary boundary layer.