The Study Of The Detection Potential On Fog And Its Visibility By Doppler Radar

Since Doppler Weather Radar is applied in operation, it has become an effective instrument of surveying the meso-scale and micro-scale weather systems. At the present time, the meteorological workers and scholars have make much research on the intensity and Doppler velocity information which relate to weather and bring forward many means of how to inspect and identify all kinds of weather systems from Doppler Radar data, while there are few research on the detection of fog by radar. This paper estimates the fog echo intensity range by use of the radar fog echo data before and after the fog, studies infection of the radar performance parameters on fog detection and analyses the relationship between the reflectivity Z and visibility of the fog, excepting it will provide some new information for fog detection by radar.In the preface, the development of weather radar at home and abroad, the currently way of fog detection and the purposes of this research are given.In chapter two, the physical cause of formation and evanishment of fog, the types of fog and the infection on traffic, and the fogdrop distributing experiential modal are introduced, then the space-time distributing characteristics of dense fog are expound on the example Shanghai-Nanjing Highway.Then in chapter three, the main configuration and the detection theory of Doppler Radar are introduced first, with that the probability of fog detection by radar is discussed, and then based on the radar echo data of fog, the basic characteristics of fog echo are analyzed.Subsequently, the theoretic estimation of fog echo intensity is investigated in chapter four. The infection on radar detection by radar performance parameter, the congest coefficient of wave beam, the attenuation, the fluctuation of atmospheric refractive index and the fogdrop distributing model is analyzed. Then the reason of why fogdrop distributing model evolves is discussed, and the radar fog echo intensity range is estimated under different fogdrop distributing models.In chapter five, the visibility and reflectivity of fog has been analyzed, thus the technique of using Doppler Weather Radar to detect the visibility in fog has been explored. Then taking the dense fog of Zhenjiang stage in spring of 2006 and Maqun stage in winter of 2007 for example, based on the analyse of visibility detected by visibility meter and the relevant radar reflectivity, we find they have obvious reciprocal connection, which elementarily checked up the detection potential on fog and its visibility by Doppler Radar.Finally, in chapter six the conclusions in this paper are showed and the refinement is suggested.