Revise z_bot and p_bot calculation to avoid negative z_bot

[XiaqiongZhou-NOAA]

Description
The calculation of z_bot and p_bot is revised to avoid negative z_bot.
The calculation of the lowest layer-mean hydrostatic pressure p_lot is revised by only using pe (interface values) only instead of delp and peln in order to avoid the inconsistency between them. z_bot is now exactly the height depth from the surface to the lowest model level. This modification can fix the model crash issue for UFS coupled applications.

How Has This Been Tested?

This was tested on Hera and Orion for the coupled regression tests.
The z_bot fields are more reasonable with the modification.

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]

looks fine

[HenryJuang-NOAA]

looks file, where to click approval?

…

On Mon, May 10, 2021 at 11:53 AM bensonr ***@***.***> wrote: @bensonr <https://github.com/bensonr> requested your review on: #102 <#102> Revise z_bot and p_bot calculation to avoid negative z_bot . — You are receiving this because your review was requested. Reply to this email directly, view it on GitHub <#102 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ALRWWEMLM5OSDRX524V5ZXDTM76OTANCNFSM44RPITYQ> .

[bensonr]

@HenryJuang-NOAA - after you click on green "add your review" button near the top of this page, there green button on the right hand side of the screen near the top that says "review changes". It is there you can click approve and submit your review.

[HenryJuang-NOAA]

Is bot for T_bot and P_bot to indicate T and P at the bottom first model layer location, then z_bot must mean height at the bottom model layer location. Based on the formula, it is okay to say the depth in height above the model ground or ocean surface.

[bensonr]

I agree with @HenryJuang-NOAA regarding the specifications of where the data originates, but won't hold up the approval. The inline documentation should match up to the quantities provided.