Spanning the Gap From Bulk to Bin: A Novel Spectral Microphysics Method

Abstract

A new microphysics method using collocation of basis functions is presented.• The method improves spectral accuracy and precipitation predictions over bulk and bin methods.• The method applies to a flexible range of computational complexity, providing a way to unify microphysics models.

Reduced‐Order Modeling for Linearized Representations of Microphysical Process Rates

“…How informative are latent variable and moment based representations of the DSD? Unlike the basis function approach discussed in De Jong et al (2022) or the machine learning approaches described in Rodríguez Genó and Alfonso (2022) and Gettelman et al (2021), our approach does not require a priori assumptions about the functional form of drop size distributions, but rather assumes optimal representations can be directly learned from the observations. We use recent reduced-order modeling developed in the context of data-driven discovery of governing equations for discrete dynamical systems.…”

“…This large number of variables limits the use of bin microphysics schemes for many modeling applications. Several recent papers have focused on finding accurate and efficient basis sets to represent the DSD, in order to create models with less computational expense than bin models and more accurate predictions than bulk models (De Jong et al., 2022; Rodríguez Genó & Alfonso, 2022). The quadrature method of moments has also recently been used to develop sparse representations of aerosol populations (which present similar modeling challenges to cloud particle populations) (Fierce & McGraw, 2017; McGraw, 1997).…”

“…Unlike the basis function approach discussed in De Jong et al. (2022) or the machine learning approaches described in Rodríguez Genó and Alfonso (2022) and Gettelman et al. (2021), our approach does not require a priori assumptions about the functional form of drop size distributions, but rather assumes optimal representations can be directly learned from the observations.…”