Accession Number : ADA320980

Title :   Radar Studies of Aviation Hazards: Part 2 Lightning Precursors.

Descriptive Note : Scientific rept. no. 3,

Corporate Author : HUGHES STX CORP LEXINGTON MA

Personal Author(s) : Harris, F. I. ; Smalley, David J. ; Tung, Shu-Lin ; Bohne, Alan R.

PDF Url : ADA320980

Report Date : 15 JUL 1996

Pagination or Media Count : 32

Abstract : For convective storms developing in a weakly sheared environment, considerable evidence has been amassed that relates radar reflectivity structure and lightning activity. Marshall and Radhakant (1978) suggest that the electrical activity of thunderstorms is related to radar reflectivity observed at the 6-7 km level. This idea was further tested by Lhermitte and Krehbiel (1979). They horizontally integrated the radar reflectivity of a storm at several heights and found that lightning began when the storm top reached 8 km (-20c C). Also, they found that the peak flash rate (about 1 flash/s) occurred when the reflectivity exceeded 50 dBZ at the 100 C level. Buechier and Goodman (1991) observed that cloud-to-ground strikes began when the reflectivity values of 30-40 dBZ extended above 7 km. While all the above observations were made in Florida, similar altitude or temperature thresholds were found in New Mexico (Krehbiel, 1986) and the tropics (Williams, 1991). Other studies have looked at various methods of comparing reflectivity data and lightning activity. A recent study by Harris-Hobbs et al (1992) attempted to correlate lightning activity with storm volumes exceeding various thresholds. They found good correlations between the magnitudes of the volumes exceeding 20 dBZ and flash activity. However, for some of their data, study by Harris-Hobbs et al (1992) attempted to correlate lightning activity with storm volumes exceeding various thresholds. They found good correlations between the magnitudes of the volumes exceeding 20 dBZ and flash activity. However, for some of their data, regions with higher reflectivity thresholds attain peak volumes before that for the 20 dBZ threshold and before the time of maximum lightning activity.

Descriptors :   *HAZARDS, *DOPPLER RADAR, *AVIATION SAFETY, *THUNDERSTORMS, PEAK VALUES, PREDICTIONS, MASS, RATES, ELECTRICAL PROPERTIES, AERONAUTICS, LIGHTNING, RADAR REFLECTIONS, STORMS, NEW MEXICO, TROPICAL REGIONS, REFLECTIVITY, FLORIDA, CONVECTION(ATMOSPHERIC), FLASHES.

Subject Categories : Meteorology
      Safety Engineering
      Active & Passive Radar Detection & Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE