Multimoment ice bulk microphysics scheme with consideration for particle shape and apparent density. Part I: Methodology and idealized simulation
Journal
Journal of the Atmospheric Sciences
Journal Volume
77
Journal Issue
5
Pages
1821-1850
Date Issued
2020
Author(s)
Tsai, T.-C.
Abstract
To improve the parameterization of ice-phase microphysics in regional meteorological models, this study developed a triple-moment bulk scheme, which also tracks the variations in the shape and density of several hydrometeors. Solid-phase hydrometeors are classified into pristine ice, snow aggregates, rimed ice, and hailstones based on their physical mechanisms. The new scheme has been incorporated into the Weather Research and Forecasting Model and tested with an idealized two-dimensional simulation of a squall-line system. The simulation successfully revealed the smooth transition from the convective core to the stratiform anvil as well as the alternating pattern in the hydrometeor vertical distributions, as was similarly demonstrated in other similar studies.Afew sensitivity tests were performed to reveal the importance of including shape and density variations, which strongly affect the mean particle size by up to 50% and fall speed by as much as 100% for individual hydrometeor categories. Furthermore, the inclusion of a third moment could enhance the diffusional growth rate of small crystals and reduce the ventilation effect of large particles compared with the conventional double-moment approach. These factors have a significant influence on cloud structure and precipitation amounts. © 2020 American Meteorological Society.
SDGs
Other Subjects
Clouds; Growth rate; Particle size; Precipitation (meteorology); Sensitivity analysis; Storms; Weather forecasting; Diffusional growth rates; Mean particle size; Meteorological models; Physical mechanism; Two-dimensional simulations; Ventilation effects; Vertical distributions; Weather research and forecasting models; Ice; climate modeling; cloud microphysics; computer simulation; hydrometeorology; ice cover; methodology; particle size; squall line; weather forecasting
Type
journal article