Abstract
This paper documents the third version of the GFDL cloud microphysics
scheme (GFDL MP v3) used in the System for High-resolution prediction on
Earth-to-Local Domains (SHiELD) model. Compared to the GFDL MP v2, the
GFDL MP v3 is entirely reorganized, optimized, and modularized by
functions. In addition, the particle size distribution (PSD) of all
cloud categories is redefined to mimic the latest observations, and the
cloud condensation nuclei (CCNs) are calculated from the MERRA2 aerosol
data. The GFDL MP has been redesigned so all processes use the redefined
PSD to ensure overall consistency and easily permit introductions of new
PSDs and microphysical processes. Analyses gathered from simulations by
SHiELD with selected configurations are examined. Compared to the GFDL
MP v2, the GFDL MP v3 significantly improves the predictions of
geopotential height, air temperature, and specific humidity in the
Troposphere, as well as the high, middle and total cloud fractions and
the liquid water path. With the more realistic PSD implemented in GFDL
MP v3, the predictions of geopotential height in the Troposphere, low
and total cloud fractions are further improved. Furthermore, using
climatological aerosol data to calculate CCNs leads to even better
predictions of geopotential height, air temperature, and specific
humidity in the Troposphere, high and middle cloud fractions, as well as
the liquid and ice water paths. However, the upgrade of the GFDL MP
shows little impact on the precipitation prediction. Degradation due to
the scheme upgrade is also addressed and discussed to guide the future
GFDL MP development.