A Study On Quality Evaluation And Correction Of Ground-based Microwave Radiometer Brightness Temperature Data And Its Inversion Applications

This paper addresses the quality control of ground-based microwave radiometer bright temperature data,carries out radiometer bright temperature simulation and analysis based on radiation transmission theory and radiometer performance,refines the screening of clear sky and cloudy sky samples,and establishes a systematic bias revision of bright temperature data based on clear sky samples;quantitatively analyzes the radiative contribution of clouds,and uses the observed bright temperature of microwave radiometer based on the analysis of the response of each radiometer channel to clouds.The inversion of cloud parameters is based on the analysis of the response of the radiometer channels to clouds,and the inversion accuracy of the atmospheric temperature and humidity profiles is further improved by proposing a "cloud influence revision" scheme that removes the "cloud radiative contribution".The main findings include.(1)The study emphasizes the influence of the radome and the ambient temperature on the side flaps,and proposes an environmental interference correction scheme based on radiation theory analysis and statistics.Analysis of the computational results shows that the temperature around the antenna must be taken into account,especially in the K-band,to prevent the effects of contaminated radomes and side flap spillover.The correction eliminates the "jumps" in the bright temperature observations,improves the temporal continuity of the bright temperature observations themselves,and improves the systematic consistency with the orthorectified data based on NCEP-fnl data.The proposed correction scheme can be used for real-time data quality control,and also for data rescue in case of contaminated environment or improper calibration when a large amount of data is acquired using microwave radiometers.(2)In this paper,we use the "three-channel weighting method" to estimate the cloud thickness and cloud water concentration,and identify the "clear sky" and "cloudy sky" samples,using three of the 22 observation channels of the ground-based microwave radiometer that are sensitive to cloud parameters.The "cloudy sky" and "cloudy sky" samples are also identified.On this basis,the "cloud radiation contribution" of the remaining channels is revised for the temperature and humidity inversion calculation.This paper emphasizes that,in addition to the quality control of the bright temperature data to ensure the stability of the system hardware,further "cloud influence correction" should be performed to remove the influence of clouds from the bright temperature data,and then the data should be used for the inversion of the vertical profiles of atmospheric temperature and humidity and liquid water content.The analysis of the Beijing data for two years shows that a "cloud radiative contribution" correction is necessary for the bright temperature observations,where the larger the cloud impact factor CI is,the more difficult and necessary the correction is.The significant improvement in the inversion of the temperature and humidity profiles implies that the method is feasible.(3)After the systematic revision of the bright temperature data before the strong convective precipitation and the revision of the cloud impact,the temperature and humidity vertical profiles are inverted,and the corresponding convective effective potential energy CAPE and convective inhibition energy CIN are calculated and applied to the analysis of convective instability before the strong convective precipitation,which can effectively capture the local convective effective potential energy accumulation process completed in a short period of time,and has some significance for the forecast of approaching precipitation.