Low longwave absorption in NorESM by desert dust

[Ovewh]

Figure 1: (a) surface albedo, (b) Dust Forcing efficiency (DirectRadiative forcing/od550dust) calculated as difference between 2x-dust and control. From AerChemMIP

Figure 2: as the figure 1 above just for LW forcing effciency

Note: I have selected a box transect from North Atlantic over North Africa. All the plots I am showing is for the same region.

The CMIP6 version of NorESM2-LM has the dry deposition bug which caused even more rapid settling of the large particles.

When running the dust radiative forcing experiments (DURF), i did histSST simulations using the FORCES NorESM2 version with this bug corrected. The bug did not make a substantial difference in the LW forcing efficiency, see my figure below.

Figure 3: Forcing efficiency for LW, SW and net for NorESM2 only, with dry deposition bug fix

I would like to tackle this issue in my upcomming PPE, so I was wondering which parameter in the models that would be best to adjust?

• Size parameters?
• Radiation, optical properties