Browsing by Author "Baker, Ian T., author"
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Item Open Access Investigation of enhanced-reflectivity features embedded within a wintertime orographic cloud on 28-29 November 1984(Colorado State University. Libraries, 1994) Baker, Ian T., author; Grant, Lewis O., advisor; Mielke, Paul W., committee member; Cotton, William R., committee memberA combination of aircraft, sounding, surface, vertically-pointing ku-Band radar and dual-channel radiometer data was used to investigate the microphysical characteristics of enhanced-reflectivity areas embedded within an orographic cloud in northwestern Colorado on 28-29 November 1984. The orographic cloud was associated with the passage of an open wave and upper-level front over the region, and embedded within the cloud were regularly-spaced areas of increased reflectivity as seen by the vertically-pointing radar. The radiometer observed a cyclical component on both the liquid and vapor channels when oriented in the vertical. Aircraft data reveal that there was supercooled liquid water in the cloud at levels as high as 41 kPa and as far as 55 km upwind of the barrier. 2D-C and 2D-P probe data indicated two crystal regimes, one where concentrations in individual size bins were larger and spectra were broader, indicating crystal growth. In the other, concentrations were smaller and size spectra were narrower. Radar data indicate that the enhanced-reflectivity regions were between 10-20 km apart, with a length dimension on the order of 5 km wide. It is believed that the presence of the enhanced-reflectivity areas is closely linked to the presence of a decoupled layer on the windward side of the barrier, and preliminary evidence points to a gravity-wave mechanism as a physical cause.