Weather Prediction in SHiELD: Effect from GFDL Cloud Microphysics Scheme Upgrade

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.

Machine‐Learned Climate Model Corrections From a Global Storm‐Resolving Model: Performance Across the Annual Cycle

“…The first three months are excluded as spin‐up, resulting in a year‐long reference data set spanning the remaining time from 19 January 2020 through 17 January 2021. The following are notable configuration differences in the reference fine‐grid model used here with respect to the configuration in B22: There is no meteorological nudging of atmospheric fields to analysis. It uses the newer, inline version of the GFDL microphysics (Zhou et al., 2022). It uses a mixed‐layer ocean between 45°S and 45°N, nudged with a 15‐day timescale to ECMWF SSTs from analysis.…”

Impact of warmer sea surface temperature on the global pattern of intense convection: insights from a global storm resolving model

“…X-SHiELD uses 79 vertical levels where the resolution is the finest (~20 m) at the bottom and gradually expands upward, with a model top at 3 hPa. The physical parameterizations used in X-SHiELD include the in-line GFDL microphysics scheme (Harris et al, 2020;Zhou et al 2022), the turbulent kinetic energy (TKE)-based moist eddy-diffusivity mass-flux (EDMF) PBL scheme (Han and Bretherton, 2019), the scale-aware simplified Arakawa-Schubert scheme (Han et al, 2017) for shallow convection only, and the Noah-MP land surface model (Niu et al, 2011). A mixed-layer ocean model (Pollard et al, 1973) is used and nudged towards real-time ECMWF SST analyses.…”