Radar remote sensing of the clear atmosphere—Review and applications

This is a review of clear-air radar with special emphasis on applications. The history of radio scattering from turbulence-induced refractive-index fluctuations is discussed along with current research programs using clear-air radars. Applications involving wind measurement are presently being implemented and the first operational use of clear-air radar will be to improve weather prediction. Eventually, the same clear-air radar system used to observe the weather will be used for optimum routing of aircraft for fuel economy and to estimate transport of pollutants in acid rain studies. Clear-air radar also can potentially be used as an airport hazard monitor for wind shear and wingtip vortices. A new application for clear-air radar is monitoring the presence and height of refractive layers aloft to predict anomalous propagation and estimate unusual radar coverage. Because insects are often detected by clear-air radars, we have included insects as clear-air targets and discuss the use of radar to study insects and birds.