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A new technique, named Vertical Profile Indicator (VPI), which uses the vertical structure of the reflectivity profile to delineate regions most likely to have supercooled liquid water content (SCLWC) within the precipitation field, was developed. When the aircraft flew in the "active regions" (as defined by the VPI technique) it was found that 90% of the time significant amounts of SCLWC were observed. / Using Doppler and "Quasi-Doppler" radar data, high convergence cores (> 3.0 x 10('-3) s('-1)) and updraft activity were observed to occur preferentially in the "active regions". During the 1981 winter-spring period of the Precipitation Enhancement Project in the Duero Basin of Spain percentages of "active regions" in relation to the whole precipitation field, and in relation to the total radar observation area, did not exceed 47% and 18% respectively. / The VPI technique provides information which may be used to direct research aircraft to cloud regions containing SCLWC to allow measurements of the time evolution of their microphysical state. These measurements would permit a better estimation of the residence time of the SCLWC and its removal rates. This is a key parameter for better understanding the microphysical properties of clouds and consequently the possibility of artificial modification of precipitation.

The indirect effect of aerosols expresses how changes in aerosols would influence clouds and cause impacts on Earth's climate and hydrological cycle. The current assessment of the interactions between aerosols and clouds is uncertain and parameterizations used to represent cloud processes are not well constrained. This thesis first evaluates a cloud activation parameterization by investigating cloud droplet number concentration closure for stratocumulus clouds sampled during the 2005 MArine Stratus Experiment (MASE). Further analysis of the droplet size distribution characteristics using the extended parameterization is performed by comparing the predicted droplet spectra with the observed ones. The effect of dynamical variability on the droplet size distribution evolution is also investigated by considering a probability density function for updraft velocity. The cumulus and stratocumulus cloud datasets from in-situ field measurements of NASA's Cirrus Regional Study of Tropical Anvils and Cirrus Layers - Florida Area Cirrus Experiment (CRYSTAL-FACE) and Coastal STRatocumulus Imposed Perturbation Experiment (CSTRIPE) campaigns are used for this task. Using the same datasets, the autoconversion rate is calculated based on direct integration of kinematic collection equation (KCE). Six autoconversion parameterizations are evaluated and the effect of turbulence on magnifying collection process is also considered. Finally, a general circulation model (GCM) is used for studying the effect of different autoconversion parameterizations on indirect forcing estimates. The autoconversion rate given by direct KCE integration is also included by implementing a look-up table for collection kernels. Although these studies add more variability to the current estimate of aerosol indirect forcing, they also provide direction towards a more accurate assessment for climate prediction.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 47-49). Also available on the World Wide Web.

Thesis (M.S.)--Florida State University, 2005. / Advisor: Dr. Carol Anne Clayson, Florida State University, College of Arts and Sciences, Dept. of Meteorology. Title and description from dissertation home page (viewed June 28, 2005). Document formatted into pages; contains x, 62 pages. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 96-99).