Fixes and updates related to Noah-MP

[kaiyuan-cheng]

Description

A number of fixes, updates, and code clean-up related to Noah-MP:

1. fix issue with iems = 2, together with updated surface emissivity initialization. Originally, the surface emissivity was 0.95 everywhere anytime over land and sea-ice. The fix gives realistic spatial and temporal distribution of surface emissivity.
   

2. fix wrong type of precipitation passed to Noah-MP. Specifically, this PR fixes that falling cloud ice was passed into Noah-MP as falling hail.

3. fix the representation of mixing ratio. Correct conversion from modified specific humidity (vapor_mass/[dry_mass + vapor_mass]; used in the GFS physics) to mixing ratio.

4. fix potential temperature calculation

5. fix water table recharge, based on version 4.5 of the official Noah-MP repository

6. update snow initialization, based on version 4.5 of the official Noah-MP repository

7. fix the output of wilting point

cc: @spencerkclark and @lharris4

How Has This Been Tested?

Tested on Gaea with a C96 case. Restart run and layout change do not change the answer.

Checklist:

Please check all whether they apply or not

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

[lharris4]

I think this looks ok. Since it will change answers, could we have a couple of plots with this PR to summarize what is changed (such as your plots of emissivity you sent by Email)?

[kaiyuan-cheng]

I think this looks ok. Since it will change answers, could we have a couple of plots with this PR to summarize what is changed (such as your plots of emissivity you sent by Email)?

I have added more details to the proposed fixes.

[lharris4]

Thank you for this additional documentation. I think this is good now.