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| Titel |
Constraining mass–diameter relations from hydrometeor images and cloud radar reflectivities in tropical continental and oceanic convective anvils |
| VerfasserIn |
E. Fontaine, A. Schwarzenboeck, J. Delanoë, W. Wobrock, D. Leroy, R. Dupuy, C. Gourbeyre, A. Protat |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 20 ; Nr. 14, no. 20 (2014-10-29), S.11367-11392 |
| Datensatznummer |
250119126
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| Publikation (Nr.) |
 copernicus.org/acp-14-11367-2014.pdf |
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| Zusammenfassung |
In this study the density of ice hydrometeors in tropical clouds is derived
from a combined analysis of particle images from 2-D-array probes and
associated reflectivities measured with a Doppler cloud radar on the same
research aircraft. Usually, the mass–diameter m(D) relationship is
formulated as a power law with two unknown coefficients (pre-factor,
exponent) that need to be constrained from complementary information on
hydrometeors, where absolute ice density measurement methods do not apply.
Here, at first an extended theoretical study of numerous hydrometeor shapes
simulated in 3-D and arbitrarily projected on a 2-D plan allowed to constrain
the exponent βof the m(D) relationship from the exponent σ of
the surface–diameterS(D)relationship, which is likewise written as a power
law. Since S(D) always can be determined for real data from 2-D optical array
probes or other particle imagers, the evolution of the m(D) exponent can be
calculated. After that, the pre-factor α of m(D) is constrained from
theoretical simulations of the radar reflectivities matching the measured
reflectivities along the aircraft trajectory.
The study was performed as part of the Megha-Tropiques satellite
project, where two types of mesoscale convective systems (MCS) were
investigated: (i) above the African continent and (ii) above the Indian
Ocean. For the two data sets, two parameterizations are derived to calculate
the vertical variability of m(D) coefficients α and β as a
function of the temperature. Originally calculated (with T-matrix) and also
subsequently parameterized m(D) relationships from this study are compared to
other methods (from literature) of calculating m(D) in tropical convection.
The significant benefit of using variable m(D) relations instead of a single
m(D) relationship is demonstrated from the impact of all these m(D)
relations on Z-CWC (Condensed Water Content) and Z-CWC-T-fitted parameterizations. |
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