Calibration of a Monostatic SoDAR for Quantitative Measurement of CN**2

The SoDAR was one of the first ground based remote sensing instruments used for research and by the commercial community. The SoDAR was introduced to the U.S by the Wave Propagation laboratory in the mid-1960s. A seminal paper on the principles of SoDAR technology and comparing it to other remote sensing instruments spurred the development of the subsequent WPL atmospheric remote sensing effort as well as igniting research efforts at universities and commercial entities. These remote sensing instruments differ from the weather radar in that they are designed intentionally to measure horizontal wind and turbulence profiles directly above the instrument. In particular the SoDAR was projected to be a device to provide measurements within the lowest part of the atmosphere (1 km and below) directly above the instrument. An commercial example was the highly successful acoustic radar that was manufactured by AeroVironment, Inc. iin the early 1970s. Over the years the monostatic non-coherent SoDAR has been successfully produced qualitative and qualitative measurements of atmospheric phenomena such as local mixing depths which are often related to inversion heights or elevated shear layers, the local atmospheric stability and the atmospheric structure constant for temperature. This presentation will focus on the application of the SoDAR equation. It describes the relationship between the SoDAR sound pulse and the atmospheric temperature structure constant. Building on this relationship, a calibration procedure will be presented This procedure is to be used to calibrate the SoDAR for quantitative measurements of the structure constant. These measurement will be applied to the measurement of profiles of the structure constant as well as monitoring the time height history of the structure constant. This paper will present the methodology for calibration and the methodology to verify this calibration over several months of operation. These types of measurements are useful for applications such as atmospheric “seeing” applications associated with high power telescopes, microwave and laser propagation.