Mesoscale Wind Fields for a Severe Storm Situation Determined from SMS Cloud Observations

The Effect of the Arbitrary Level Assignment of Satellite Cloud Motion Wind Vectors on Wind Analyses in the Pre-thunderstorm Environment

“…A variation of this technique (Suomi, 1975) used by Wilson and Houghton (1979) and Pesien (1980) calculates optical thickness from the visible brightness of a target cloud to determine the infrared emittance of the cloud and thus account for fractional cloud cover on a sub-pixel scale.…”

“…This review highlights the various approaches to assigning the CMV to a particular level. It may be argued, however, that all of the finer aspects of each technique may ha;e ra meaningful impact on diagnostic computations if the next step in the analysis procedure is to "arbitrarily"' assign all the CMV to pressure surfaces which are representative of "low," "middle," or "high" portions of the troposphere as has been done in numerous diagnostic or model studies (Wilson and Houghton, 1979;Peslen, 1980;Negri and Vonder Haar, 1980;Lee and Houghton, 1984a, b). The purpose of the analyses which follow is to determine the impact of the arbitrary assignment of CMV to a "low" pressure surface in a pre-convective storm envirogment.…”

“…Moreover, no comparisons have ever been made between CMV and mesoscale rawinsonde observations obtained in baroclinic, continental situations. Despite this lack of adequate verification, a number of investigators have obtained physically meaningful mesoscale wind fields from satellite cloud motions in continental severe storm situations (Wilson and Houghton, 1979;Peslen, 1980;Negri and Vonder Haar, 1980). Furthermore, the mesoscale information of CMV has been reported by Maddox and Vonder Haar (1979) in terms of statistical structure functions.…”

“…The height determination issue is concerned with errors arising from the various methods of cloud height measurement. Together these two sources of error can contribute to a very large percentage of the total random error variance [for example, 93% in the case reported by Wilson and Houghton (1979), amounting to 4.5 m sec -1 standard deviation in the resulting CMV wind estimates].…”

Review Lecture: Local weather forecasting

“…An important task in areas prone to severe thunderstorms is to obtain descriptions of mesoscale wind fields which are accurate enough to reveal the associated regions of low-level convergence. Initial investigations suggest that rapid-scan cloud imagery can be used to detect the areas of strongest convergence (Wilson & Houghton 1979). An extension of this technique (Vonder Haar 1977) would then be to combine the measurements of such areas of convergence with measurements of boundary layer moisture content, since the mesoscale field of moisture convergence is considered to be one of the best indicators of imminent outbreaks of severe storms.…”