How Are Mixed‐Phase Clouds Mixed?

Abstract

Mixed‐phase clouds are recognized as significant contributors to the modulation of precipitation and radiation transfer on both regional and global scales. This study is focused on the analysis of spatial inhomogeneity of mixed‐phase clouds based on an extended data set obtained from airborne in situ observations. The lengths of continuous segments of ice, liquid, and mixed‐phase clouds present a cascade of scales varying from 102 km down to a minimum scale of 100 m determined by the spatial resolution of measurements. It was found that the phase composition of mixed‐phase clouds is highly intermittent, and the frequency of occurrence of ice, liquid, and mixed‐phase regions increases with the decrease of their spatial scales. The distributions of spatial scales have well‐distinguished power‐law dependencies. The results obtained yield insight into the morphology of mixed‐phase clouds and have important implications for improvement in representing subgrid inhomogeneity of mixed‐phase clouds in weather and climate models.

On the Scale of Particle Clustering Induced by Inhomogeneous Entrainment‐Mixing in Mixed‐Phase Cumulus Clouds

“…This method is limited by the sample frequency, thus, r c indicates the dominant cluster scale within a sample distance of 100 m. It is expected that there will be smaller clusters of droplets and ice, but a higher sampling frequency is required. Clusters larger than 100 m are probably affected by other processes such as isolated updrafts/downdrafts and mesoscale dynamics (A. Korolev & Milbrandt, 2022) rather than turbulence and entrainment, and will not be discussed in this study.…”

CLASS Observations of Atmospheric Cloud Polarization at millimeter Wavelengths

“…At temperatures above −40 °C, liquid water may coexist with ice crystals in its supercooled state (Korolev & Milbrandt 2022). The dielectric permittivity of liquid water within the microwave range has a strong frequency dependency; therefore, the Rayleigh scattering spectrum of liquid water has an additional term |(ò ν − 1)/(ò ν + 2)| 2 (Equation ( 5)).…”

Characterization of the Spatial Distribution of the Thermodynamic Phase Within Mixed‐Phase Clouds Using Satellite Observations

“…The WBF process is thus more efficient when hydrometeors are uniformly mixed than when organized in discrete pockets of ice crystals and liquid droplets. Independent aircraft in situ as well as ground‐based and satellite remote sensing observations support the latter arrangement of cloud thermodynamic phase, that is, hydrometeors tend to be organized in pockets or clusters of ice crystals and liquid droplets (Chylek & Borel, 2004; D’Alessandro et al., 2019; Korolev & Milbrandt, 2022; Korolev et al., 2003; Lewis et al., 2020; Shupe, 2007; Thompson et al., 2018). Nonetheless, GCMs assume that cloud droplets and ice crystals within mixed‐phase clouds are uniformly mixed (e.g., Gettelman et al., 2010).…”

“…Nevertheless, it should be noted that active measurements from space‐based instruments have more uncertainties compared to in situ and ground‐based observations (Tansey et al., 2022) (e.g., inability to observe small particles, low‐level clouds near the ground, and all multilayer clouds, the coarse spatial resolution, algorithm errors due to incorrect simplifying assumptions) and the data set might not be able to accurately quantify cloud base due to signal attenuation. Recent studies have quantified the heterogeneity of mixed‐phase clouds over the mid‐latitude and Arctic regions (D’Alessandro et al., 2019; Korolev & Milbrandt, 2022). However, studies investigating the control of the global spatial distribution of the thermodynamic and local meteorological parameters on phase heterogeneity are scarce.…”