RADAR PROBING OF THE TROPOSPHERE UNDER CLEAR SKY CONDITIONS
Abstract
The author discusses the nature and the origins of radar echoes in clear air in the absence of hydrometeors. Four different types are defined: (1) discrete-coherent echo, (2) reflections from inversion layers, (3) reflections from layers containing aerosols, (4) reflections from regions of turbulence. The first type of radar return can be explained either by inhomogeneities in the refractive index of the air or by the presence of insects or birds. The author comes to the conclusion that models based on variations in the refractive index are inconsistent with some important aspects of this phenomenon. On the other hand, eliminating birds as the source of such echoes because the magnitudes of signals due to reflections from birds are several orders of magnitude higher than those under consideration, the hypothesis that insects are the source of the discrete-coherent echoes fully satisfies the meteorological and physical properties of such signals. Reflections from the inversion layers are due to abrupt changes in the refractive index of air caused by the local temperature differences as well as to the presence of aerosols. The latter source is extensively discussed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 09, 1969
- Accession Number
- AD0696235
Entities
People
- G. B. Brylev