Hi all,
I would like to know the relationship between AAOD changes and Black carbon. I want to separate the effects of BC, Dust, EC to AAOD. As a result , i want to know the Parameterized scheme of AAOD in RRTM. I have read Atmospheric and Environmental Research R&C. But i didn’t find it.
I would like to know which factor effects AAOD in WRF-CMAQ, how can they effect AAOD and which file controls the input of species information from the CMAQ model to the WRF model.
Xu
Hi Xu,
WRF-CMAQ coupled model with direct aerosol radiative effect is based on the core-shell model. Primarily the optics calculation utilizes BHCOAT method. If EC presents, it will switch to the BHMIE method, which is based on Mie theory. I am not a Mie theory expert, but my understanding is that Mie’s calculation includes scattering and absorption. I believe you can perform a simple experiment: with the current coupled model as the base case, run the model with setting EC = 0 (modify the source code) as case 1, and run the model with switching all calculations using the BHCOAT method as case 2 (again modify the source code). With these three cases, you can see the weight of absorption.
WRF-CMAQ coupled model transfers five categorical aerosol information (water soluble, water insoluble, EC, H2O, and Sea Salt, each of which consists of three different modes, i, j, and k) from CMAQ to WRF to impact the radiation calculation. EC here refers to AEC species in CMAQ. The definition of these categories can be found in the feedback_setup subroutine in twoway_feedback.F90. In much older versions of the coupled model, everything is hard coded based on a specific chemical mechanism and aerosol model. In recent versions, water soluble and insoluble species are determined automatically. In addition, CMAQ species associated with “dust” are included in the water insoluble category. Hence if you want to figure out the contribution of EC, BC, and Dust to AAOD, it is impossible with the current form of the coupled model. You need to modify the code considerably in order to achieve your goal.
If you have additional questions, please let me know (feel free to contact me directly, wong.david-c@epa.gov).
Cheers,
David
Hi David,
Your reply is very helpful to me. After your reminder, I found the files module_ra_rrtmg_aero_optical_util_cmaq.F and module_ra_rrtmg_aero_optical_util_cmaq.f90. Surprisingly, thet were written by you. This makes me even more honored to receive your reply.
I recently discovered that black carbon emissions have been significantly underestimated in my research area, and this issue takes precedence over the relationship between black carbon and AAOD. Nevertheless, thank you very much for your reply.
Cheers,
Xu