Software Design And Numerical Experiments For Simulating Airborne Radar Detection And Data Processing

Clouds are of considerable importance in the atmosphere. Millimeter cloud radar plays an important role in getting both the macro and micro structures of cloud. To make research on the effect of various factors such as macro and micro structures of hydrometeors in cloud on airborne radar sounding and data processing, this paper design an algorithm for developing a software platform to quantitatively simulate airborne radar detection and data processing, abbreviated as SimRAD hereafter, based on the theories of cloud and precipitation observations and attenuation correction in millimeter wavelength, and then make numerical simulation experiments on radar sounding and attenuation correction from different cloud parameters by SimRAD.SimRAD source codes are written in Fortran90 with Compaq Visual Fortran 6.6.C, and available on Windows system. By importing the radar frequency and the atmospheric state parameters such as height, pressure, temperature, relative humidity, and the phase, content and droplet size distribution of hydrometeors, the SimRAD can compute the radar-observed reflectivity vertical profiles and the attenuation caused by hydrometeors and gaseous molecules in the atmosphere, and make attenuation correction with different correction algorithm.To airborne W band cloud radar (94GHz,3.2 mm), the research based on the SimRAD not only make numerical simulations of radar echo of six typical non-precipitating clouds and make attenuation correction with five correction algorithms by the relationship between the attenuation coefficient k and the radar echo Z, but also make study on the correction results when the six typical clouds'parameters (water content and cloud droplet number density) are changed.The results show that:firstly, all five correction algorithms are suitable for the six typical clouds and even if the cloud thickness increase to 2 times of the typical clouds, the relative errors are still less than 5%; secondly, the attenuation correction results are apt to unstable to the non-typical clouds with the Hitschfeld-Bordan algorithm; thirdly, the attenuation correction results are acceptable to the non-typical clouds with the Meneghini's iteration, which are relatively little changed to the typical cloud, and if the cloud thickness is not more than the typical thickness, the relative errors are less than 10%; the last is the attenuation correction results are close to each other between the two approximated bin-by-bin algorithms and the bin-by-bin algorithm to the non-typical cloud, which water content don't change, and even if the cloud thickness increase to 2 times of the typical clouds, the relative errors are still less than 10%.