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CCPP SciDoc v7.0.0
v7.0.0
Common Community Physics Package Developed at DTC
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CCPP SciDoc v7.0.0
v7.0.0
Common Community Physics Package Developed at DTC
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The Grell-Freitas (GF) scheme, as described in Grell and Freitas (2014) [72], Freitas et al. (2018) [61], Freitas et al. (2021) [62], and Lin et al. (2022) [121] follows the mass flux approach published by Grell (1993) [73]. Further developments by Grell and \(D\acute{e}v\acute{e}nyi\) (2002) [71] included implementing stochastics through allowing parameter perturbations. The GF scheme includes mixed phase physics impact, momentum transport, a diurnal cycle closure (Bechtold et al. (2014) [13] ), and a trimodal spectral size to simulate the interaction and transition from shallow, congestus and deep convection regimes. The vertical mass flux distribution of shallow, congestus and deep convection regimes is characterized by Probability Density Functions (PDFs). The three PDFs are meant to represent the average statistical mass flux characteristic of deep, congestus, and shallow (respectively) plumes in the grid area. Each PDF therefore represents a spectrum of plumes within the grid box. Forcing is different for each characteristic type. Entrainment and detrainment are derived from the PDFs. The GF scheme takes into account aerosol dependence (considered experimental and not supported in this release), which is implemented through rain generation (following Berry (1968) [23] and evaporation formulations depending on the cloud concentration nuclei at cloud base (Jiang et al. (2010) [101]), and Lee and Feingold (2010) [115]). Wet scavenging is considered to add a memory impact. GF is able to transport tracers. Recently, GPU capabilities and cap suppressing (do_cap_suppress) based on radar data assimilation have been added, and they are used only for the RAP suite.
The impacts of GF scheme in operational RAP/HRRR include: (a)uses mass-flux schemes, which are more physically realistic than (sounding) adjustment schemes; (b)takes parameterization uncertainty into account by allowing parameters from multiple convective schemes which can be perturbed internally or with temporal and spatial correlation patterns; (c)for higher resolutions (less than 10 km), in addition to scale awareness as in Arakawa et al. (2011) [8] GF can transition as grid spacing decreases into a shallow convection scheme; (d)Coupled to the grid-scale precipitation and radiation schemes through passing of diagnosed cloud liquid and ice from simulated precipitating convective cloud and shallow convective clouds.
The Implementation of GF in RRFS prototypes
The implementation of GF in HAFS is ongoing.
The GF scheme passes cloud hydrometeors to the grid-scale microphysics scheme (Thompson Aerosol-Aware Cloud Microphysics Scheme ) through detrainment from each convective cloud layer containing convective cloud. The detrained condensate interacts with short- and longwave radiation by contributing to the "opaqueness" to radiation of each grid layer. Additionally, detrained condensate is added to any existing condensate, to be treated by the complex grid-scale microphysics scheme. This allows for a crude emulation of stratiform precipitation regions in the RAP.
Additionally, the shallow convection and PBL schemes pass cloud information to the radiation scheme, which improved cloud/radiation interaction and retention of the inversion typically found above mixed layers.
1.12.0