Parameterization of cloud droplet size distributions: comparison with parcel models and observations
Author
Hsieh, W.C.
Nenes, A.
Flagan, R.C.
Seinfeld, J.H.
Buzorius, G.
Jonsson, H.
Date
2009Metadata
Show full item recordAbstract
This work examines the efficacy of various physically based approaches derived
from one-dimensional adiabatic parcel model frameworks (a numerical model and a
simplified parameterization) to parameterize the cloud droplet distribution characteristics
for computing cloud effective radius and autoconversion rate in regional/global
atmospheric models. Evaluations are carried out for integrations with single (average) and
distributions of updraft velocity, assuming that (1) conditions at smax are reflective of
the cloud column or (2) cloud properties vary vertically, in agreement with
one-dimensional parcel theory. The predicted droplet distributions are then compared
against in situ cloud droplet observations obtained during the CRYSTAL-FACE and
CSTRIPE missions. Good agreement of droplet relative dispersion between parcel model
frameworks indicates that the parameterized parcel model essentially captures
one-dimensional dynamics; the predicted distributions are overly narrow, with relative
dispersion being a factor of 2 lower than observations. However, if conditions at cloud
maximum supersaturation are used to predict relative dispersion and applied throughout
the cloud column, better agreement is seen with observations, especially if integrations
are carried out over the distribution of updraft velocity. When considering the efficiency of
the method, calculating cloud droplet spectral dispersion at smax is preferred for linking
aerosol with droplet distributions in large-scale models.
Description
Journal of Geophysical Research, Vol. 114, D11205
The article of record as published may be located at http://dx.doi.org/10.1029/2008JD011387
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.Collections
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