Dependence of Mass–Dimensional Relationships on Median Mass Diameter

Retrievals of ice cloud properties require accurate estimates of ice particle mass. Empirical mass–dimensional (<i>m</i>–<i>D</i>) relationships in the form <inline-formula> <math display="inline"> <semantics> <mrow> <mi>m</mi> &l...

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Main Authors: Saisai Ding, Greg M. McFarquhar, Stephen W. Nesbitt, Randy J. Chase, Michael R. Poellot, Hongqing Wang
Format: Article
Language:English
Published: MDPI AG 2020-07-01
Series:Atmosphere
Subjects:
Online Access:https://www.mdpi.com/2073-4433/11/7/756
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author Saisai Ding
Greg M. McFarquhar
Stephen W. Nesbitt
Randy J. Chase
Michael R. Poellot
Hongqing Wang
author_facet Saisai Ding
Greg M. McFarquhar
Stephen W. Nesbitt
Randy J. Chase
Michael R. Poellot
Hongqing Wang
author_sort Saisai Ding
collection DOAJ
description Retrievals of ice cloud properties require accurate estimates of ice particle mass. Empirical mass–dimensional (<i>m</i>–<i>D</i>) relationships in the form <inline-formula> <math display="inline"> <semantics> <mrow> <mi>m</mi> <mo>=</mo> <mi>a</mi> <msup> <mi>D</mi> <mi>b</mi> </msup> </mrow> </semantics> </math> </inline-formula> are widely used and usually universally applied across the complete range of particle sizes. For the first time, the dependence of <i>a</i> and <i>b</i> coefficients in <i>m–D</i> relationships on median mass diameter (<i>D<sub>mm</sub></i>) is studied. Using combined cloud microphysical data collected during the Olympic Mountains Experiment and coincident observations from Airborne Precipitation Radar Third Generation, <i>D<sub>mm</sub></i>-dependent (<i>a</i>, <i>b</i>) coefficients are derived and represented as surfaces of equally plausible solutions determined by some tolerance in the chi-squared difference <inline-formula> <math display="inline"> <semantics> <mrow> <msup> <mi>χ</mi> <mn>2</mn> </msup> </mrow> </semantics> </math> </inline-formula> that minimizes the difference between observed and retrieved radar reflectivity. Robust dependences of <i>a</i> and <i>b</i> on <i>D<sub>mm</sub></i> are shown with both parameters significantly decreasing with <i>D<sub>mm</sub></i>, leading to smaller effective densities for larger <i>D<sub>mm</sub></i> ranges. A universally applied constant <i>m–D</i> relationship overestimates the mass of large aggregates when <i>D<sub>mm</sub></i> is between 3–6 mm and temperatures are between −15–0 °C. Multiple <i>m–D</i> relations should be applied for different <i>D<sub>mm</sub></i> ranges in retrievals and simulations to account for the variability of particle sizes that are responsible for the mass and thus for the variability of particle shapes and densities.
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spelling doaj.art-63ff77ed79004fab8fcd44f828ae4ef82023-11-20T07:09:12ZengMDPI AGAtmosphere2073-44332020-07-0111775610.3390/atmos11070756Dependence of Mass–Dimensional Relationships on Median Mass DiameterSaisai Ding0Greg M. McFarquhar1Stephen W. Nesbitt2Randy J. Chase3Michael R. Poellot4Hongqing Wang5Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, ChinaCooperative Institute of Mesoscale Meteorological Studies, Norman, OK 73072, USADepartment of Atmospheric Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USADepartment of Atmospheric Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USADepartment Atmospheric Sciences, University of North Dakota, Grand Forks, ND 58202, USADepartment of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, ChinaRetrievals of ice cloud properties require accurate estimates of ice particle mass. Empirical mass–dimensional (<i>m</i>–<i>D</i>) relationships in the form <inline-formula> <math display="inline"> <semantics> <mrow> <mi>m</mi> <mo>=</mo> <mi>a</mi> <msup> <mi>D</mi> <mi>b</mi> </msup> </mrow> </semantics> </math> </inline-formula> are widely used and usually universally applied across the complete range of particle sizes. For the first time, the dependence of <i>a</i> and <i>b</i> coefficients in <i>m–D</i> relationships on median mass diameter (<i>D<sub>mm</sub></i>) is studied. Using combined cloud microphysical data collected during the Olympic Mountains Experiment and coincident observations from Airborne Precipitation Radar Third Generation, <i>D<sub>mm</sub></i>-dependent (<i>a</i>, <i>b</i>) coefficients are derived and represented as surfaces of equally plausible solutions determined by some tolerance in the chi-squared difference <inline-formula> <math display="inline"> <semantics> <mrow> <msup> <mi>χ</mi> <mn>2</mn> </msup> </mrow> </semantics> </math> </inline-formula> that minimizes the difference between observed and retrieved radar reflectivity. Robust dependences of <i>a</i> and <i>b</i> on <i>D<sub>mm</sub></i> are shown with both parameters significantly decreasing with <i>D<sub>mm</sub></i>, leading to smaller effective densities for larger <i>D<sub>mm</sub></i> ranges. A universally applied constant <i>m–D</i> relationship overestimates the mass of large aggregates when <i>D<sub>mm</sub></i> is between 3–6 mm and temperatures are between −15–0 °C. Multiple <i>m–D</i> relations should be applied for different <i>D<sub>mm</sub></i> ranges in retrievals and simulations to account for the variability of particle sizes that are responsible for the mass and thus for the variability of particle shapes and densities.https://www.mdpi.com/2073-4433/11/7/756mass–dimensional relationshipmedian mass diameterradar reflectivityequally plausible surface
spellingShingle Saisai Ding
Greg M. McFarquhar
Stephen W. Nesbitt
Randy J. Chase
Michael R. Poellot
Hongqing Wang
Dependence of Mass–Dimensional Relationships on Median Mass Diameter
Atmosphere
mass–dimensional relationship
median mass diameter
radar reflectivity
equally plausible surface
title Dependence of Mass–Dimensional Relationships on Median Mass Diameter
title_full Dependence of Mass–Dimensional Relationships on Median Mass Diameter
title_fullStr Dependence of Mass–Dimensional Relationships on Median Mass Diameter
title_full_unstemmed Dependence of Mass–Dimensional Relationships on Median Mass Diameter
title_short Dependence of Mass–Dimensional Relationships on Median Mass Diameter
title_sort dependence of mass dimensional relationships on median mass diameter
topic mass–dimensional relationship
median mass diameter
radar reflectivity
equally plausible surface
url https://www.mdpi.com/2073-4433/11/7/756
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