Accession Number : ADA265898


Title :   Investigation of Outflow Strength Variability in Florida Downburst Producing Storms


Descriptive Note : Final rept.


Corporate Author : FEDERAL AVIATION ADMINISTRATION WASHINGTON DC SURVEILLANCE OFFICE


Personal Author(s) : Johnson, J T ; Eilts, Michael ; Droegemeier, Kevin


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a265898.pdf


Report Date : Feb 1993


Pagination or Media Count : 114


Abstract : With the Federal Aviation Administration introducing Doppler weather radar to high-traffic airports in the form of the Terminal Doppler Weather Radar (TDWR), improved identification of dangerous windshears from downbursts and other weather phenomena will be possible. Using detection and prediction algorithms, the TDWR system will give controllers and pilots more information about the weather situation in the terminal area than is available heretofore. During the summer of 1990, a prototype TDWR system was tested and evaluated in Orlando, Florida with more than 500 downbursts detected. Many storms possessing apparently 'similar' characteristics were found to produce a wide variety of outflow speeds on days with nearly the same environmental structure. In this study, we use single-Doppler radar observations, surface mesonet data and a 3-D numerical cloud model in an attempt to determine causes for the observed variability. In particular, we examine 8 downbursts from August 18, 21 and 22 as well as 5 simulated downbursts. Our results show that the observed variability is explained neither by Doppler radar signatures known to precede downbursts (e. g., convergence and rotation aloft) nor by minor but detectable variations in the environment among the three days examined. Suspecting somewhat more subtle mechanisms, we examined detailed microphysical processes within numerically simulated storms


Descriptors :   *DOPPLER RADAR , *WEATHER FORECASTING , *WIND SHEAR , *STORMS , MATHEMATICAL MODELS , AIRPORTS , THUNDERSTORMS , FLORIDA , REFLECTIVITY , FREEZING , ATMOSPHERIC PRECIPITATION , CLOUDS


Subject Categories : Terminal Flight Facilities
      Meteorology
      Active & Passive Radar Detection & Equipment


Distribution Statement : APPROVED FOR PUBLIC RELEASE