Parameterization of cloud droplet size distributions: comparison with parcel models and observations
MetadataShow full item record
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.
Journal of Geophysical Research, Vol. 114, D11205The article of record as published may be located at http://dx.doi.org/10.1029/2008JD011387
Showing items related by title, author, creator and subject.
Analysis of shiptrack persistence with insitu cloud measurements and satellite retrieved reflectance Tessmer, Scott A. (Monterey, California. Naval Postgraduate School, 1996-03);Shiptracks detected on Advanced Very High Resolution Radiometer (AVHRR) satellite images posses longer detection lives and down-track brightness than expected. A simple model of physical processes is developed to correlate ...
Morales, R.; Nenes, A.; Jonsson, H.; Flagan, R.C.; Seinfeld, J.H. (2011);This study investigates the ability of a droplet activation parameterization (which considers the effects of entrainment and mixing) to reproduce observed cloud droplet number concentration (CDNC) in ambient clouds. ...
Rissman, T.A.; Varutbangkul, V.; Jonsson, H.H.; Nenes, A.; Jimenez, J.L.; Delia, A.E.; Bahreini, R.; Roberts, G.C.; Seinfled, J.H.; Conant, W. C.; Van Reken, T.M. (2004);Our understanding of the activation of aerosol particles into cloud drops during the formation of warm cumulus clouds presently has a limited observational foundation. Detailed observations of aerosol size and composition, ...