Radar Measurement of Small Scale Turbulence and Thermal Stability in the Lower Atmosphere

Preliminary research results indicate that microwave, pulsed radar can be used to monitor the strength of temperature inversions and the magnitude of small scale turbulent eddies in the atmosphere at low altitudes. This is accomplished by the use of special video analysis equipment which monitors the amplitude and fluctuations of reflected signals from stable, stationary objects in the vicinity of the radar. Long and short period fluctuations are observed on the order of 10³ to 10^-1 minutes. The long period fluctuations appear to be manifestations of slow changes in the temperature lapse rate; and the short period ones of small scale turbulence in the lower atmosphere. The average strength of reflected signals increases as the lapse rate of temperature decreases in the lower atmosphere. Although atmospheric moisture content enters into the radio refractive index, apparently the highest average signal strengths are associated with ground-based or low altitude temperature inversions. Suitable radars presently exist in or near most metropolitan areas. The present state of the art electronics which would be added to each would be small in size, gather propagation-stability data from several path-areas, and yield important meteorological information useful for air pollution and other applications without affecting the present mission of the radars.