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  • Author or Editor: DAVID B. SPIEGLER x
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David B. Spiegler


An objective layer of maximum-wind (LRMW) analysis technique which is described and evaluated, has two main features: 1) a categorization procedure that sorts wind profiles into nine jet-stream categories, for the derivation of regression equations to generate initial-guess fields of six LRMW parameters; and 2) an analysis technique that locates jet cores between grid points and generates “observations” along these cores from horizontal-jet profile models.

Initial-guess fields are generated for thickness of the LRMW, wind speed maximum, mean height and wind direction of the LRMW, and vector shears below and above the LRMW, providing a three-dimensional picture of the wind field.

The initial-guess LRMW equations are stable in tests with independent data and are capable of specifying very well the general characteristics of the LRMW profile. They also provide realistic values for the LRMW parameters over no-data areas that are consistent with the entire analysis area.

Over data areas, where objective and subjective analyses could be compared, the objective LRMW analyses compare favorably with subjective analyses.

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George H. Milly
John T. Ball
, and
David B. Spiegler


An examination is made of the hypothesis that the inconclusive or marginal effects of many cloud seeding operations are due, at least in part, to an inhomogeneous distribution of freezing nuclei resulting in great ranges of concentration and extensive areas of overseeding and underseeding over the target region. Distributions of silver iodide nucleus concentrations arising from ground based generators were computed using a Gaussian plume diffusion model. Meteorological conditions and the number, locations, and yield of ground based generators were varied in a series of numerical experiments which bracketed conditions typical of many cloud seeding operations. The results indicated that effective seeding concentrations of nuclei can be achieved over a significant portion of the target area only by carefully considering initial atmospheric conditions as they affect nucleus diffusion and activity, and by accordingly designing and deploying the system of silver iodide generators.

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