About longwave effect of dust aerosols in CAM3

[yuexuiap@sohu_com]

Dear All,

CAM3 considers the shortwave effect of dust. However, the longwave effect of dust has been neglected. And I want to know whether I could include such effect by modifying the codes of CAM3. I know that CAM3 consider the longwave effect of volcanic aerosols. Can I use the similar parameterization method to add the longwave effect of dust by modifying the absorption coefficients abs_cff_mss_aer(bnd_nbr_LW)?

Thanks very much!

 

[zender]

Hi Yue,

Yes. The procedure that was used for volcanic aerosols works for dust.
The main difference for dust is the need to loop from [1..dst_nbr].
You'll want to weight the absorption coefficients within each band by
a representative Planck function, since some LW bands are quite broad.

Good luck,
Charlie

 

[yuexuiap@sohu_com]

Dear professor Zender,

Thanks for your suggestions.
The calculation of the absorption coefficient for aerosols in the infrared intervals seems different from that in shortwave bands. I divide each longwave bands into several subbands. Then I calculate the weighted coefficients by
Ai = sum(A*d(lam))/sum(d(lam))
where A is the absorption coefficient within the subbands derived from the Mie theory.

However, the results seems to be much smaller than that of the absorption coefficients of volcanic aerosol's (in the same unit of m2/kg). As a result the magnitude of dust longwave effect is smaller than reality.

Are there any problems?

Thanks very much!