Radar Studies of Aviation Hazards: Part 2 Lightning Precursors

• Main Authors: Harris, F. I, Smalley, David J, Tung, Shu-Lin, Bohne, Alan R
• Format: Report
• Language: English
• Subjects: Active & Passive Radar Detection & Equipment; AERONAUTICS; AUTOMATED TECHNIQUES; AVIATION SAFETY; CONVECTION(ATMOSPHERIC); DOPPLER RADAR; DOPPLER WEATHER RADAR; ELECTRICAL PROPERTIES; FLASHES; FLORIDA; HAZARDS; LIGHTNING; LIGHTNING PRECURSORS; MASS; Meteorology; NEW MEXICO; PE63707F; PEAK VALUES; PREDICTIONS; RADAR REFLECTIONS; RATES; REFLECTIVITY; Safety Engineering; STORM MASS; STORM STRUCTURE; STORM VOLUME; STORMS; THUNDERSTORMS; TROPICAL REGIONS; WUPL2781GTMA

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. ADA320981 ADA320982 ADA320983