Effects of turbulence on mixed‐phase deep convective clouds under different basic‐state winds and aerosol concentrations

Abstract

The effects of turbulence-induced collision enhancement (TICE) on mixed-phase deep convective clouds are numerically investigated using a 2-D cloud model with bin microphysics for uniform and sheared basic-state wind profiles and different aerosol concentrations. Graupel particles account for the most of the cloud mass in all simulation cases. In the uniform basic-state wind cases, graupel particles with moderate sizes account for some of the total graupel mass in the cases with TICE, whereas graupel particles with large sizes account for almost all the total graupel mass in the cases without TICE. This is because the growth of ice crystals into small graupel particles is enhanced due to TICE. The changes in the size distributions of graupel particles due to TICE result in a decrease in the mass-averaged mean terminal velocity of graupel particles. Therefore, the downward flux of graupel mass, and thus the melting of graupel particles, is reduced due to TICE, leading to a decrease in the amount of surface precipitation. Moreover, under the low aerosol concentration, TICE increases the sublimation of ice particles, consequently playing a partial role in reducing the amount of surface precipitation. The effects of TICE are less pronounced in the sheared basic-state wind cases than in the uniform basic-state wind cases because the number of ice crystals is much smaller in the sheared basic-state wind cases than in the uniform basic-state wind cases. Thus, the size distributions of graupel particles in the cases with and without TICE show little difference.

Cloud — Aerosol interaction during lightning activity over land and ocean: Precipitation pattern assessment

“…To analyze precipitation efficiency, cloud microphysical property need to be explored properly. There are several factors like turbulence (Benmoshe and Khain, 2014;Lee et al, 2014), collision rate, terminal velocity etc. need to be considered.…”

Effects of turbulence‐induced collision enhancement on heavy precipitation: The 21 September 2010 case over the Korean Peninsula

“…The time series of the maximum turbulence dissipation rate show that strong turbulence appears intermittently, particularly in the cloud developing stage (07–13 LST). The maximum turbulence dissipation rate during this period reaches approximately 2000 cm 2 s −3 in the case with TICE, which is in the simulated ranges in Benmoshe and Khain [] and Lee et al [] that numerically investigated an isolated deep convective cloud using a two‐dimensional model with finer grid resolutions. The vertical distributions of the maximum turbulence dissipation rate show that strong turbulence dissipation rates mainly appear at high altitudes ( z > 7 km), which is also in good agreement with the result of Benmoshe and Khain [].…”

“…Instead, TICE increases the snow number concentration in almost the entire range of snow size. This aspect of change in the snow size distribution is partially due to the very effective riming process across the entire range of snow size, and it is similar to the changes in graupel size distribution due to TICE [ Lee et al , ]. It is seen in Figure that the intercept parameter of snow size distribution function varies significantly.…”

“…Benmoshe and Khain [2014] andLee et al [2014] and also similar to the methods used inSeifert et al [2010],Wyszogrodzki et al [2013],and Franklin [2014].…”

How Mountain Geometry Affects Aerosol-Cloud-Precipitation Interactions: Part I. Shallow Convective Clouds

“…The WRF-bin model considers 43 mass-doubling bins. Following Khain et al (2000) and Lee et al (2014), the initial aerosol size distribution N (r a ) is specified as…”