Atmospheric Description for Idaho Falls B-757 Run #9 on September 25, 1990

The Volpe National Transportation Systems Center (Volpe Center) has been developing data processing software for the meteorological tower and tethersonde data observed during the special wake vortex experiments conducted at Idaho Falls in 1990. In addition, the data have been analyzed by Volpe Center meteorological support personnel for the purpose of preparing "canonical cases" for study by wake vortex modelers. The material in this report is the first such case developed for a particularly strong and persistent up wind vortex from a B-757 flyby at 0818LST on Sept. 25, 1990. Data are provided in three forms: raw data, data smoothed in time and height, and best fit polynomials. Except at the turbulent scale, the bulk characteristics of a local air mass change slowly relative to the life cycle of a vortex pair from a single aircraft. Therefore, the dataset from this case, taken over the space of a few minutes by the instrumented tower and a tethersonde less than a mile away, should be reasonably representative of flyby #9 on Sept. 25, 1990. In future experiments, this hypothesis must be further tested and proved. However, in the present case, it seems like a reasonable working assumption without evidence to the contrary. The authors manually smoothed the tethersonde data primarily in order to remove some of the effects of what appears to be significant observational noise associated with the sounding technique employed. The tethersonde balloon only developed for ten (10) seconds at each observation level in order to minimize the time of balloon flight and provide safe aircraft flybys. The smoothed data were then fit to fourth order polynomials which provided an analytical description of the profiles of wind, temperature, and derived parameters. This also removed more of the irregularities while preserving the larger scale vertical structure. Thus users of this dataset can choose from several optional forms of data. It should be noted that the authors have presented the wind data in terms of the orthogonal components; u, which is positive west to east, and v, which is positive south to north, rather than in terms of direction and speed.

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    System Resources Corporation

    128 Wheeler Road
    Burlington, MA  United States  01803

    Volpe National Transportation Systems Center

    55 Broadway
    Cambridge, MA  United States  02142
  • Publication Date: 1994-1


  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; Tables;
  • Pagination: 30p

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Filing Info

  • Accession Number: 01675056
  • Record Type: Publication
  • Created Date: Jul 11 2018 9:58AM