Casebook 22 September 2003


CSU-CHILL Casebook: 22 September, 2003

RHI scan showing boundary layer

PPI volume scans conducted on 22 September 2003 detected widespread boundary layer echo with a "dumbell" pattern characterized by maximum positive values of nearly +9 dB that are separated by ~180 degrees in azimuth. (See the first VCHILL example image below.) This pattern is observed when insects are flying in a preferred direction. The positive peaks occur when the radar is observing a side view of the insects, giving the largest horizontal / vertical axis length ratio. When the radar is illuminating an end-view of the insects, values are minimized. The broadside view of the insects also gives a larger backscattering cross section, so reflectivity maxima coincide with the peaks. The second VCHILL example is an RHI scan that passes through the layered insect echo.

example in VCHILL

example in VCHILL

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