Performance Simulation Research Of Small Satellite Atmospheric Microwave Sounder

The technology of small satellite atmospheric microwave sounder is currently a research hotspot of microwave remote sensing technology.It has the advantages of small in size,low in power consumption,easy to use,and highly versatile.Through satellite networking and organically combining a variety of observation methods,the small satellite atmospheric microwave sounder can achieve rapid revisit observations in the globe or in special regions.This is of great significance for numerical weather prediction,disaster monitoring and environmental protection,and global climate research.This thesis takes the application of the small Satellite Atmospheric Microwave Sounder(SAMS)independently developed by the National Space Science Center as the research object,through the establishment of the atmospheric radiation transmission model and inversion algorithm,combined with sensitivity test data simulation analysis the on-orbit performance of SAMS.SAMS consists of 18 channels with 89,118,166 and 183 GHz as the center frequency.It is an atmospheric temperature and humidity sounder suitable for the miniaturization design of small satellite platform based on the FY-3C,3D,and 3E series of Microwave Humidity Sounder.Based on the current system sensitivity test results,simulation analysis of all 18 channels for the retrieval capabilities of atmospheric temperature and humidity profiles shows that the temperature retrieval error(RMSE)is about 2-3K below 30 mb altitude.The average value is around 2.2 K,of which 100 mb and 850 mb are slightly larger,about 3 K.The SAMS humidity retrieval RMS error average is about 13%,the overall range is 10-15%,and the maximum is about 20% around 600 mb.The ability to profile the atmospheric humidity near-surface atmosphere has been improved due to the addition of channels near the ground.This thesis also extended the analysis of the SAMS data in terms of the sea surface pressure,atmospheric water vapor content,and the wet path delay.It can be found that the sea surface pressure can be retrieved up to 2 mb,and the atmospheric wet path delay is expected to reach 1.4 cm.These results have great significance for a large range monitoring of severe sea surface convective weather and the correction of sea surface height path delay.At the same time,it is found through analysis that SAMS has certain sea surface parameter retrieval capabilities,such as sea surface temperature and wind speed.Although the accuracy is not high,it can be used as the input of the initial value of the profile retrieval to reduce the influence of surface error on atmospheric profile retrieval.Spectrum receiving technology of microwave radiometer is currently a research hotspot.In order to further improve the detection range and detection accuracy of SAMS,this thesis discusses the feasibility of using spectrometer technology near the absorption peak of oxygen and water vapor to enhance atmospheric profile detection capabilities.The design scheme of the channel index is completed,and the relevant verification and analysis are carried out.For the 118 GHz frequency band,the sensitivity of different positions of the spectral lines to different detection heights is analyzed,and a suitable position(117.85～118.85 GHz)for setting the spectrometer is selected.Then the detection capability of 1 GHz bandwidth and 0.3 GHz bandwidth spectrometers is compared through simulation,and the results show that 1 GHz bandwidth spectrometers have more advantages.Finally,the detection performance of5,10,20,and 30 MHz spectral resolution under different sensitivity conditions is analyzed.The results show that,in the atmosphere less than 1 h Pa,the spectral resolution is required better than 20 MHz at least,and when the noise temperature is lower than 600 K,the improvement of spectral resolution is helpful to improve the measurement performance.At altitudes below this,a spectrometer with a bandwidth of1 GHz and a resolution of 30 MHz can meet the requirement of a temperature detection accuracy better than 2 K.In addition,through the calculation of the inversion Jacobian matrix and the amount of information,it is proved that the ability of using the spectrum analyzer technology near 118 GHz to detect temperature is significantly improved.For the 183 GHz frequency band,the weighting function calculation shows that a spectrometer set near 183.31 GHz has a certain detection weight for water vapor above100 h Pa,but it is far less than the troposphere.According to the simulation results,although there is a certain weight,the retrieval accuracy is poor because the water vapor content above the troposphere is too small to be distinguished from the background radiation.Therefore,it is difficult to improve the water vapor detection ability above the troposphere by using spectrometer.