Aerosol extinction in MAM7

[adrianabossolasco]

I am using the CAM5-MAM7 model for my studies (FSTRATMAM7 compset) and now I have a doubt regarding the Extinction coefficient that the model gives from the output file, according to the master list this is the Aerosol extinction coefficient but I realized that in MAM7 the AP (aerosol particles) are treated together with the aerosol in convective clouds. So I am wondering if this Extinction coefficient is just due to aerosols or it's also due to clouds? because at the altitude of around 200 hPa I have very large values. so what exactly include the extinction?

For the other hand in the paper by Liu et al. 2012, where the MAM7 model is described, says that in MAM7 the AP (aerosol particles) in the interstitial state are lumped with the aerosol in convective clouds. What is the mean of this? Is like always the aerosol concentration is mix of dry aerosols + aerosols in clouds? What is the exactly meaning of AP in the interstitial state?

I really appreciate any help

Thanks

Adriana

 

[nusbaume]

Hi Adriana,

In MAM7, the “cloud-borne” aerosols only includes aerosols that are within stratiform clouds, while the “interstitial” aerosols includes both clear-sky aerosols and aerosols contained within convective clouds. So if you are looking in a region with significant convection (like the tropics) then these convective cloud particles could be the cause of your high extinction coefficient values.

Also, since I am in no way an expert on this topic, I am moving this question to the CAM-Chem forum, in case someone more knowledgeable than myself would like to provide additional info or clarification.

Hope that helps, and have a great day!

Jesse

 

[adrianabossolasco]

Hi Jesse
Thank you very much for you answer and clarification. This help me a lot, now I understand why my high values.
It would be great if someone else provide additional info

Thanks again and good day for you too

Adriana