Aerosol Optical Depth - Clear Sky and All Sky - CAM-Chem

[nuvolet]

What version of the code are you using?
CESM2.2.0 in Derecho

Have you made any changes to files in the source tree?
Some changes in the nudging module

Describe every step you took leading up to the problem:
I have run a multiyear case (2010-2012) using MERRA2 and assimilating AOD from MODIS to look at how the model nudges those aerosols.
In the output files I requested the AODVISdn and the AODstrt. I am assuming that the AODs are computed for all sky conditions

Describe your problem or question:

I am wondering if there is any option while running same case as explained before to get the AOD but for clear-sky conditions.

 

[rrbuchholz]

Hi Toni,

We had a chat within ACOM and have come up with an answer (thanks to Danny, Ilaria, Louisa and Simone).

The way AOD is calculated in CESM is by using aerosol-specific mass extinction coefficient (m2/kg) and columnal dry air mass (kg/m2). This means AOD fields in CESM are never contaminated by CESM-simulated clouds (all-sky conditions), which means they are always clear-sky AOD fields.

If you want to look at the AOD from the model that are in grid-cells without any clouds, you can save out cloud fraction (i.e. CLOUD) and use it to filter your model output for AODVIS.

Best,
Rebecca

 

[nuvolet]

Hi Rebecca,

This is really helpful.
Thanks for your response.

Cheers.

Toni