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Title: Predicting Ice Shape Evolution in a Bulk Microphysics Model

Abstract

A novel bulk microphysics scheme that predicts the evolution of ice properties, including aspect ratio (shape), mass, number, size, and density is described, tested, and demonstrated here. The scheme is named the Ice-Spheroids Habit Model with Aspect-Ratio Evolution (ISHMAEL). Ice is modeled as spheroids and is nucleated as one of two species depending on nucleation temperature. Microphysical process rates determine how shape and other ice properties evolve. A third aggregate species is also employed, diversifying ice properties in the model. Tests of ice shape evolution during vapor growth and riming are verified against wind tunnel data, revealing that the model captures habit-dependent riming and its effect on fall speed. Lagrangian parcel studies demonstrate that the bulk model captures ice property evolution during riming and melting compared with a bin model. Lastly, the capabilities of ISHMAEL are shown in a 2D kinematic framework with a simple updraft. A direct result of predicting ice shape evolution is that various states of ice from unrimed to lightly rimed to densely rimed can be modeled without converting ice mass between predefined ice categories (e.g., snow and graupel). This leads to a different spatial precipitation distribution compared with the traditional method of separating snow andmore » graupel and converting between the two categories, because ice in ISHMAEL sorts in physical space based on the amount of rime, which controls the thickness and therefore fall speed. Predicting these various states of rimed ice leads to a reduction in vapor growth rate and an increase in riming rate in a simple updraft compared with the traditional method.« less

Authors:
 [1];  [2];  [1];  [3]
  1. National Center for Atmospheric Research, Boulder, Colorado
  2. The Pennsylvania State University, University Park, Pennsylvania
  3. Meteorological Research Division, Environment and Climate Change Canada, Montreal, Quebec, Canada
Publication Date:
Research Org.:
Pennsylvania State Univ., University Park, PA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER); National Science Foundation (NSF)
OSTI Identifier:
1361944
Alternate Identifier(s):
OSTI ID: 1536994
Grant/Contract Number:  
FG02-05ER64058; SC0012827
Resource Type:
Published Article
Journal Name:
Journal of the Atmospheric Sciences
Additional Journal Information:
Journal Name: Journal of the Atmospheric Sciences Journal Volume: 74 Journal Issue: 6; Journal ID: ISSN 0022-4928
Publisher:
American Meteorological Society
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Cloud microphysics; Ice crystals; Ice loss/growth; Ice particles; Cloud parameterizations; Clouds

Citation Formats

Jensen, Anders A., Harrington, Jerry Y., Morrison, Hugh, and Milbrandt, Jason A. Predicting Ice Shape Evolution in a Bulk Microphysics Model. United States: N. p., 2017. Web. doi:10.1175/JAS-D-16-0350.1.
Jensen, Anders A., Harrington, Jerry Y., Morrison, Hugh, & Milbrandt, Jason A. Predicting Ice Shape Evolution in a Bulk Microphysics Model. United States. doi:10.1175/JAS-D-16-0350.1.
Jensen, Anders A., Harrington, Jerry Y., Morrison, Hugh, and Milbrandt, Jason A. Tue . "Predicting Ice Shape Evolution in a Bulk Microphysics Model". United States. doi:10.1175/JAS-D-16-0350.1.
@article{osti_1361944,
title = {Predicting Ice Shape Evolution in a Bulk Microphysics Model},
author = {Jensen, Anders A. and Harrington, Jerry Y. and Morrison, Hugh and Milbrandt, Jason A.},
abstractNote = {A novel bulk microphysics scheme that predicts the evolution of ice properties, including aspect ratio (shape), mass, number, size, and density is described, tested, and demonstrated here. The scheme is named the Ice-Spheroids Habit Model with Aspect-Ratio Evolution (ISHMAEL). Ice is modeled as spheroids and is nucleated as one of two species depending on nucleation temperature. Microphysical process rates determine how shape and other ice properties evolve. A third aggregate species is also employed, diversifying ice properties in the model. Tests of ice shape evolution during vapor growth and riming are verified against wind tunnel data, revealing that the model captures habit-dependent riming and its effect on fall speed. Lagrangian parcel studies demonstrate that the bulk model captures ice property evolution during riming and melting compared with a bin model. Lastly, the capabilities of ISHMAEL are shown in a 2D kinematic framework with a simple updraft. A direct result of predicting ice shape evolution is that various states of ice from unrimed to lightly rimed to densely rimed can be modeled without converting ice mass between predefined ice categories (e.g., snow and graupel). This leads to a different spatial precipitation distribution compared with the traditional method of separating snow and graupel and converting between the two categories, because ice in ISHMAEL sorts in physical space based on the amount of rime, which controls the thickness and therefore fall speed. Predicting these various states of rimed ice leads to a reduction in vapor growth rate and an increase in riming rate in a simple updraft compared with the traditional method.},
doi = {10.1175/JAS-D-16-0350.1},
journal = {Journal of the Atmospheric Sciences},
number = 6,
volume = 74,
place = {United States},
year = {2017},
month = {4}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1175/JAS-D-16-0350.1

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