Updates to radiation, cloud, and land processes for improved surface temperature and radiative flux biases

[rhaesung]

Description

Changes from @RuiyuSun and @HelinWei-NOAA.

This PR addresses several key issues identified in the HRv4 and UFS/Noah-MP models, focusing on radiative flux biases, soil thermal conductivity, and evapotranspiration improvements. The goal of these updates is to enhance model performance and better align simulations with observed data.

1. Cloud/Radiation adjustments:

• To reduce the high bias in downward shortwave (DSW) radiative flux over land, the cloud number concentration over land has been increased from 100/cm³ to 150/cm³.
• The convective cloud ice radius in radiation has been reduced from 50 µm to 25 µm.
• The 2020 summer test results (HRv4Ntc100) show a reduction in the high DSW bias over land and a corresponding reduction in the low bias of upward shortwave (SW) radiative flux at the top of the atmosphere (TOA).

2. Soil thermal conductivity enhancement:

• A persistent nighttime and early morning warm surface temperature bias remains in both the GFS/Noah and UFS/Noah-MP models. This is partly due to overlooking the influence of soil organic matter (SOM) on soil thermal conductivity.
• By incorporating a lookup table developed from the PNNL soil carbon dataset and VIIRS surface type data, the effects of SOM on soil thermal properties have been accounted for.
• Tests show that including SOM results in better simulation of ground heat flux, reducing heat storage in the soil during the day, and mitigating the nighttime warm bias, particularly over the Great Plains.

3. Evapotranspiration adjustment:

• The aquifer hydraulic conductivity has been updated to use the algorithm average rather than the harmonic average. This increases the amount of water uptake by the soil layer, improving evapotranspiration modeling.

4. Bug Fixes:

• Snow aging at night: Fixed an issue to allow snow aging to occur at night, ensuring more realistic snow dynamics.
• Unit correction for potential evaporation: Corrected the unit for potential evaporation from W/m² to mm/s to ensure proper unit consistency and accuracy in the model.

Issue(s) addressed

None

Testing

See ufs-community/ufs-weather-model#2548 for testing using UFS WM RTs on Hera.

Dependencies

• waiting on Updates to radiation, cloud, and land processes for improved surface temperature and radiative flux biases ufs-community/ccpp-physics#244

Requirements before merging

• All new code in this PR is tested by at least one unit test
• All new code in this PR includes Doxygen documentation
• All new code in this PR does not add new compilation warnings (check CI output)