Dumbbell Shaped ZDR Patterns: 19 August 2002
On 19 August 2002, the CSU-CHILL radar observed some distinct "dumbbell-shaped" signal patterns while making PPI scans through an elevated echo layer. The dumbbells were characterized by relative maxima and minima that alternated at 90 degree azimuth intervals around constant range circles within the echo layer. The manifestation of this pattern in the reflectivity field is shown below:
A high amplitude dumbbell pattern was also quite evident in the differential reflectivity (ZDR) field:
As shown by the radial velocity configuration, the maxima in both of these dumbbells were located roughly along the mean wind direction in the height layer that was sampled in the 40 to 60 km range ring interval. (The PPI scan elevation angle was 2.8 degrees):
An analysis of these dumbbell-shaped patterns has been done by Dr. Tim Lang (research scientist in the CSU atmospheric science department radar meteorology group), Prof. Steve Rutledge (CSU-CHILL radar facility scientific director), and Dr. Jeff Stith (NCAR RAF facility manager). Their results are summarized in this paper presented at the 31st American Meteorological Society Conference on Radar Meteorology (Seattle, Washington; 6-12 August 2003):
