Research Of Atmosphere Radiative Transmission Characteristics For The Typical Weather

When electromagnetic waves transmit in atmosphere, the characteristics of atmospheric radiation transmission refer to two aspects based on the effects of absorption and scattering between the particles in the atmosphere and electromagnetic wave:on one hand, the energy of target radiations and solar radiations reflected in front of the camera imaging system is attenuated through atmospheric transmission. On the other hand, the energy in front of the camera imaging system is enhanced because of the energy of solar radiations of single scattering and multiple scattering, the target thermal radiation of multiple scattering and the particles thermal radiation in the atmosphere. Atmospheric transmittance is usually expressed energy attenuation of the radiation in the atmosphere. Atmospheric path radiation is usually expressed energy enhanced. Based on engineering applications in practice and to calculate infrared atmospheric transmission and path radiance real-time without atmospheric interference, the following contents are the major research works of this thesis:1. The relationship between the calculation factors and atmospheric molecular extinction optical depth is analyzed, the calculation factors including atmospheric parameters, absorption cross sections, scattering cross sections, radiative transmission distance, frequency etc. Absorption optical depths of continuous spectral of water vapor and nitrogen and absorption optical depths of band spectral of carbon dioxide, methane, ozone, carbon monoxide and an oxide of nitrogen are calculated according to the composition of gases in the atmosphere. Finally scattering optical depth of atmospheric molecular is calculated.2. The database for complex refractive index of aerosol particle under the conditions of typical weather (haze, fog, dust and rain, etc.) was set up. The model of aerosol size distribution was improved according to the experimental data of aerosol size distribution, and atmospheric parameterswere considered such as atmospheric visibility.the optical depths of aerosol extinction in the typical weather are calculated by Mie scattering theory.According to the relationship between optical depth and atmospheric transmittance, the calculation model of the atmospheric transmittance is improved from3 to 5 micron spectral wavelength. The simulation verifies the model correct by simulation calculation of atmospheric transmittance in typical weather.3. The small spot adjustable system for Gaussian beam in space is presented based on atmospheric transmittance measurement principle and long-distance. The radius of beam can be adjustable within a certain size at a certain distance by changing the position of primary and secondary mirror of the offset Cassegrain antenna. The feasibility verifies through experimental simulation, which can solve the measurements problem of long-distance atmospheric transmittance. The parameters of primary and secondary mirror for Cassegrain antenna of He-Ne laser are designed to achieve the radius of beam adjustable between40 mm and 60mm within 10 km.4. Considering the calculation method of optical depths, the slant path and solar parameters, the calculation model of atmospheric path radiation for the typical weather is proposed based on 3 to 5 micron spectral wavelength of the background and the theory of atmospheric radiation. The model of atmospheric path radiation includes the model of single scattering and multiple scattering of solar radiation, the model of multiple scattering of surface thermal radiation the particles thermal radiation in the atmosphere. The simulation verifies the model correct by simulation calculation of atmospheric path radiation in typical weather.5. The models of atmospheric radiation transmission for the typical weather in this paper are verified by simulation. The simulation results are analyzed under the premise for keeping the inputting parameters the same for the model of this paper and PcModWin software. The errors are calculated compared to the standard value which is calculated by PcModWin software. Based on error simulation calculations of different wave number and different weather,the maximum relative error of the atmospheric transmittance is 3.846%, and The maximum relative error of the atmospheric path radiation is 5.011% for the typical weather.that proves the validity of the model.