A novel approach for characterizing the variability in mass–dimension relationships: results from MC3E
<p>Mass–dimension (<span class="inline-formula"><i>m</i></span>–<span class="inline-formula"><i>D</i></span>) relationships determining bulk microphysical properties such as total water content (TWC) and radar reflectivity fac...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-03-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/19/3621/2019/acp-19-3621-2019.pdf |
| Summary: | <p>Mass–dimension (<span class="inline-formula"><i>m</i></span>–<span class="inline-formula"><i>D</i></span>) relationships determining bulk
microphysical properties such as total water content (TWC) and radar
reflectivity factor (<span class="inline-formula"><i>Z</i></span>) from particle size distributions are used in both
numerical models and remote sensing retrievals. The <span class="inline-formula"><i>a</i></span> and <span class="inline-formula"><i>b</i></span> coefficients
representing <span class="inline-formula"><i>m</i>=<i>a</i><i>D</i><sup><i>b</i></sup></span> relationships, however, can vary significantly
depending on meteorological conditions, particle habits, the definition of
particle maximum dimension, the probes used to obtain the data, techniques
used to process the cloud probe data, and other unknown reasons. Thus,
considering a range of <span class="inline-formula"><i>a</i>,<i>b</i></span> coefficients may be more applicable for use in
numerical models and remote sensing retrievals. Microphysical data collected
by two-dimensional optical array probes (OAPs) installed on the University of
North Dakota (UND) Citation aircraft during the Mid-latitude Continental Convective
Clouds Experiment (MC3E) were used in conjunction with TWC data from a
Nevzorov probe and ground-based <span class="inline-formula"><i>S</i></span>-band radar data to determine <span class="inline-formula"><i>a</i></span> and <span class="inline-formula"><i>b</i></span>
using a technique that minimizes the chi-square difference between the TWC and
<span class="inline-formula"><i>Z</i></span> derived from the OAPs and those directly measured by a TWC probe and
radar. All <span class="inline-formula"><i>a</i></span> and <span class="inline-formula"><i>b</i></span> values within a specified tolerance were regarded as equally
plausible solutions. Of the 16 near-constant-temperature flight legs analyzed
during the 25 April, 20 May, and 23 May 2011 events, the derived surfaces of
solutions on the first 2 days where the aircraft-sampled stratiform cloud
had a larger range in <span class="inline-formula"><i>a</i></span> and <span class="inline-formula"><i>b</i></span> for lower temperature environments that
correspond to less variability in <span class="inline-formula"><i>N</i>(<i>D</i>)</span>, TWC, and <span class="inline-formula"><i>Z</i></span> for a flight leg.
Because different regions of the storm were sampled on 23 May, differences in
the variability in <span class="inline-formula"><i>N</i>(<i>D</i>)</span>, TWC, and <span class="inline-formula"><i>Z</i></span> influenced the distribution of
chi-square values in the (<span class="inline-formula"><i>a</i>,<i>b</i></span>) phase space and the specified tolerance in a
way that yielded 2.8 times fewer plausible solutions compared to the flight
legs on the other dates. These findings show the importance of representing
the variability in <span class="inline-formula"><i>a</i>,<i>b</i></span> coefficients for numerical modeling and remote
sensing studies, rather than assuming fixed values, as well as the need to
further explore how these surfaces depend on environmental conditions in
clouds containing ice hydrometeors.</p> |
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| ISSN: | 1680-7316 1680-7324 |