Gust Front Recognition Using a Single-Doppler Radar.
Abstract
A dual-Doppler analysis of a squall-line on 3 May 1977 yielded a three-dimensional wind field within what was considered a typical squall line. This wind field was highly divergent near the surface in the area of the downdraft. Directly above this divergent flow, at a height of 3 to 6 km, the flow became highly convergent, with dry air entrainment observed along the backside of the storm. The wind field above 6 km showed only small areas of weak convergence. This lead to the conclusion that the mid-level (3 to 6 km) air was the main source of the downdraft air responsible for the strong surface outflow. Based on the idea that the mid-level convergence is an indication of a strong downdraft, the dual-Doppler wind field was converted to radial wind fields as would be viewed from various angles by a single-Doppler radar. To be able to use this idea in real-time operations, convergence values along each radial were computed relative to the azimuth of the radar and direction of storm motion. To further illustrate the possible use of this convergence signature, single-Doppler data of three thunderstorms known to have produced strong surface winds were examined. In all three cases, a strong convergent boundary was present in the mid-levels of the storm. This research indicated mid-level convergence may be a characteristic of thunderstorms which produce a strong downdraft and subsequently strong outflow. By identifying such a feature in the mid-levels of the storm, the problems of warning on storms located at a distance in excess of 100 km or storms with a gust front out ahead of the precipitation would be eliminated.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1979
- Accession Number
- ADA108013
Entities
People
- Michael William Mader
Organizations
- Air Force Institute of Technology