| Millimeter/submillimeter waves are affected by different atmospheric conditions during atmospheric transmission,such as the absorption and scattering of rain,clouds,haze and snow all produce attenuation,and the effects of different frequency bands are also different.Based on the attenuation characteristics of atmospheric transmission,a radiometer is used to detect the near-ground atmospheric brightness temperature,so as to start the monitoring and analysis of the near-ground atmospheric concentration.Millimeter waves have achieved relatively mature results and applications in atmospheric transmission,and research on the attenuation characteristics of millimeter/submillimeter waves and the near-ground atmospheric concentration temperature models have been launched.Based on the millimeter/submillimeter waves blackbody radiation law,under different weather conditions,as well as the influence of water vapor and related pollutant gases in the atmosphere on radiant energy,this paper conducts research on the near-ground atmospheric radiation characteristics.According to the atmospheric data from three different regions in Nanjing,Nantong and Shanghai,mathematical models of near-ground atmospheric gas concentration,haze,water vapor and temperature are established through simulation.Based on this,the millimeter-wave radiometer is used to detect the radiation energy of selected weather conditions,which verifies the correctness of the model.The research work of this paper is as follows:(1)According to the millimeter/submillimeter waves blackbody radiation law,a model of radiometer power and temperature is derived.Detailed analysis of the absorption mechanism of millimeter/submillimeter waves water molecules and the selection method of atmospheric window.Based on the full-power radiometer,the system principle and technical index design method of millimeter wave radiometer are described.(2)According to the characteristics of millimeter/submillimeter wave atmospheric transmission,the three factors that cause atmospheric transmission attenuation,namely absorption,scattering and refraction,are studied.In the case of different rainfall rates,use M-P distribution and J-D distribution models to simulate and analyze the rainfall attenuation model.In the case of cloud particles with different water content,the Rayleigh approximate model is used to simulate and analyze the millimeter wave atmospheric attenuation,and the attenuation coefficient curves of the three empirical formulas are compared under different rain temperatures.The Mie scattering theory is used to scatter the haze double layer Simulation of characteristics.At last,the extinction cross section and backscattering cross section of dry snow particles in the snow are compared and analyzed in different frequency ranges.(3)According to the pollutants in the near-ground atmosphere,the study focuses on the relationship between the SO2,NO2,PM2.5 and PM10 in the atmosphere and the relationship between the brightness temperature of the gas detected by the millimeter wave radiometer and the atmospheric pollution.Based on the air pollution concentration data at different locations in Nanjing,Nantong and Shanghai,simulation and analysis have shown that there is a negative correlation between atmospheric concentration and near-ground temperature.Based on the blackbody radiometer power model,the radiometer is used to monitor and analyze the concentration of atmospheric pollution.(4)In addition to considering the influence of atmospheric concentration in different regions on the radiometer's detection results,the influence of water vapor and particulate matter attenuation on the brightness temperature cannot be ignored.Therefore,the rainy,cloudy and haze days in Nanjing from October to December are selected to simulate and analyze the concentration and temperature of atmospheric pollutants.Based on the model of power and temperature,a radiometer can be used to monitor and analyze the atmospheric concentration in the case of atmospheric attenuation. |
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