Optimizing the Radar Detection of Clear Air Turbulence 660186
An analysis is made of the spectrum of refractivity fluctuations in regions of CAT and of its radar reflectivity as a function of wavelength. The results are compared to the minimum detectable reflectivity of airborne radars having optimum state of the art characteristics at each wavelength. It is shown that the best radars now feasible can barely detect the most reflective CAT at 10 na. mi. (i.e. 1 minute warning). A 20 db improvement in sensitivity is required for detection of most CAT, which appears to be just attainable by pre-detection integration. The optimum wavelength to implement is 5 - 6 cm. The best radar at this wavelength will also detect cirrus clouds reliably. Whether detecting clouds, chaff, or direct CAT echoes, a measure of the echo fluctuation (or Doppler) spectrum is required to identify the intensity of CAT. It is also demonstrated that a ground-based forward-scatter link holds great promise for reliable CAT detection.