cam6_4_020: dz fix in convproc

[fvitt]

This fixes an error in the calculation of dz in the aerosol convective removal code.

Closes #1118
Closes #1030
Closes #1125
Closes #1126

[fvitt]

@tilmes is testing the fix

[cacraigucar]

It all looks good. If you want to combine with #1118, feel free to do so

[fvitt]

@tilmes has provided some initial test results here:

https://acomstaff.acom.ucar.edu/tilmes/amwg/cam7/f.cam6_3_160.FMTHIST_ne30.moving_mtn.output.conv7_1996_2004_vs_f.cam6_3_160.FMTHIST_ne30.moving_mtn.output.conv6_1996_2004/website/html_table/mean_tables.html

I believe @tilmes is testing another configuration.

[adamrher]

I really don't expect this bug fix to change answers that much, but @tilmes these diagnostics are too limited -- they don't have any radiative fluxes except global restom. Can we get them somehow?

[tilmes]

I am doing a low-top model run with all the output, so we can run more comprehensive diagnostics and will post it asap. The earlier diagnostics show zonal mean aerosol comparisons and it indeed shows a very small impact. More to come soon.

[tilmes]

Here are the new diagnostics with the low-top model:
https://acomstaff.acom.ucar.edu/tilmes/amwg/cam7/f.e23_beta02.FLTHIST_ne30.conv_dz_bug_1995_2004_vs_f.e23_beta02.FLTHIST_ne30.001_1995_2004/website/index.html

Very little change, a little bit in dust AOD, Simone

[fvitt]

@cacraigucar
If there are no objections, this is ready to merge into cam_development.

[cacraigucar]

@PeterHjortLauritzen - As the AMWG rep, do you or @adamrher who has commented on this PR need to approve this change, or is @tilmes approval all that is required?

[PeterHjortLauritzen]

Not seeing anything of concern ... so unless @adamrher has any concerns I'd say "approve"

[adamrher]

I approve!