The solar UV radiation and its influence factors (cloud, ozone, etc.) in Lhasa, Tibet, China were observed during the period of January 2015～December 2016 by using the NILU-UV Irradiance Meters. The results show that the daily mean UV dose during the period was 1.24 MJ·m-2·d-1, in which maximum value in summer (from June to August) was 1.57 MJ·m-2·d-1, minimum value in winter (from December to Feburary) was 0.87 MJ·m-2·d-1. The average local noon-hour (05:25～06:25 UTC) UV index (UVI) was 8.34 during the period, in which the average value in summer was 11.53, and 5.02 for the winter. UVI maximum value (20.78) and daily UV dose maximum value (2.58 MJ·m-2) both arose in August, 2016. There was a phenomenon that the UV radiation was strengthened in summer as the cloud exchanged richly. The total ozone column(TOC) almost had no change during measurement, and the average local noon-hour TOC value was 264.2 DU.

Aerosol optical properties are investigated using the data observed by sun-photometer CE318 from 2011 to 2014 at Beijing station. It shows that the aerosol optical depth in Beijing, China is high for the whole year, the annual means of aerosol optical depth (AOD) at 440 nm for the four years are about 0.67±0.70, 0.69±0.71, 0.73±0.66 and 0.75±0.66, respectively. The average monthly AOD shows similar seasonal variation with a maximum in spring and a minimum in autumn. According to aerosol classification, high aerosol level in Beijing is mainly caused by fine particles and there are also coarse dust particles in spring. Fine particles growth is found in four seasons, which is mainly a hygroscopic growth in summer and autumn and a coagulation growth in other seasons. Comparison of aerosol properties between dust and haze condition shows AOD in haze condition is generally higher than that in dust condition. The back trajectory analysis indicates that airmasses on the dust day are northwest wind across Mongolia grassland and Gobi deserts. The wind speed on the haze day is weak and dominated by southeast and northwest wind, and high aerosol load condition is caused by local accumulation and transportation from other places.

According to the problems in the detection of weak chlorophyll fluorescence, a chlorophyll fluorescence detection system based on m sequence modulation technology was proposed. On the basis of noise analysis of fluorescence detection circuit, I/V conversion circuit and secondary amplifier circuit that based on T-type resistance feedback network were designed. According to the principle of m sequence demodulation, a bipolar conversion circuit, a phase-shift circuit and a fluorescence signal demodulation circuit based on AD630 were designed. The system was applied to measure the chlorophyll fluorescence of chlorella pyrenoidosa. For a sample with a chlorophyll concentration of 10 μg/L, the relative standard deviation of measurement values was 2.61%. The linear correlation coefficient between the output DC voltage and chlorophyll concentration was 0.998 in a chlorophyll concentration range of 0～100 μg/L.

Based on the principle of laser induced fluorescence, a laser induced fluorescence aerosol detection device is developed. The device uses the Nd:YAG pulsed laser in 355 nm wavelength, and the laser is guided to sample cell, then the fluorescence is collected into the high resolution grating spectrograph, finally the fluorescence spectrum is displayed. Two typical biological fluorescent substances reduced coenzyme I (NADH) and riboflavin are chosen as samples to test the performance of the device. Under the excitation of the laser in 355 nm wavelength, the reduced coenzyme I and riboflavin fluorescence spectrum are obtained. The influence of concentration on the fluorescence intensity of riboflavin is studied experimentally, and results show that fluorescence intensity has a linear relation with the riboflavin concentration during the low concentration range. The influence of the laser intensity is also studied, the results show that fluorescence intensity changes linearly with laser power within the limits, but the fluorescence intensity saturation will happen when the laser power reaches a certain value. The biological fluorescent materials database given by the laser induced fluorescence method is helpful to understand and grasp the biological fluorescence characteristics and is of significance to remote sensing of biological aerosols.

Satellite remote sensing is a useful and important tool to monitor the aerosol temporal and spatial changes. GF-4 satellite is a new generation geostationary satellite which has more spectral bands in visible to near infrared spectrum and high spatio-temporal resolution. GF-4 grabs images in focusing and scanning observation modes. So GF-4 characteristics create a good condition for aerosol monitoring. Utilizing the ultra-high spatio-temporal resolution satellite data acquired by GF-4, an operational software system was designed to retrieve aerosol optical depth. The characteristics of GF-4 observation modes and the sensibility of sensor bands to aerosol retrieval were investigated. The retrieval algorithm of aerosol optical depth was developed for ultra-high spatio-temporal resolution satellite data of GF-4, with a core idea of time-varying difference of reflectance between surface and atmosphere. Then, an operational software system was developed. The software system has the capabilities of multithreading calculation and automatic operation, which meet the demands of satellite data operational processing. A series of GF-4 satellite data were processed and validated by the ground-based experimental data, which can be got from the ground-based aerosol observation network. Preliminary results were obtained and indicate that the system has good reliability and stability. This remote sensing software system can be useful to monitor spatio-temporal changes of atmospheric particulates.

With the increase of the number and variety of remote sensors and the accuracy requirements for the calibration of remote sensors, the task of calibration is aggravated. High-frequency calibration can reduce the error of calibration and improve the level of quantification. But on-orbit calibration mode based on a small number of calibration sites has been unable to meet the timeliness and functional requirements of business applications. For the high-frequency, high-efficiency, multi-time and multi-site calibration requirements, an intelligentized calibration task planning system was developed. Relying on the domestic core site and foreign digital site, a global calibration sited information database was established to solve the matching problem of the site characteristics, satellite and load characteristics, space and time. Through the digitization of site and satellite attributes, the complicated factors that need to be considered in the calibration planning are transformed into the rules of matching calculation and the computer-readable logic. So it is possible to achieve multi-site calibration task planning on a global scale so as to improve the efficiency of calibration and achieve the goal of high-frequency calibration.

Greenhouse gases monitoring instrument (GMI) uses spatial heterodyne interference technology which can effectively detect atmospheric high-resolution absorption spectra during 759～2058 nm. And the calibration is the base of GMI spectral image data quantitative application. Based on the principle of GMI imaging and spectral calibration, the methods of on-orbit spectral calibration are discussed, and spectral calibration scheme of the external light source characteristic spectral is presented. Through the calculation of the simulation data, the uncertainty of calibration is further analyzed, and the uncertainty of on-orbit the spectral calibration is 0.030 nm. The calibration results show that the calibration uncertainty is mainly affected by the light source calibration uncertainty and regression uncertainty. The method meets the calibration requirements of the instrument and provides the basis for quantitative inversion of atmospheric main greenhouse gases.

Relative radiation correction is one of the key technologies to realize high precision and full field radiometric calibration for the directional polarized camera. A high-precision and automatic method of relative radiation correction is proposed. 15×15 points vision field scanning measurements are used. The panoramic imaging measurements of radiation response are fulfilled through the integration of the high-precision and large two-dimension rotating platforms and large-diameter integrating sphere reference light source. On-orbit working mode is simulated, data collecting process is regulated, data acquisition software is written, and the acquisition of radiation response image data is fulfilled. Astitching algorithm for data image and a processing method for relative data are designed. The data processing and precision analyzing of relative radiation correction are completed. Results of data comparison analysis and accuracy analysis show that the precision of relative radiation calibration is within 0.5%～0.8%.

Data acquisition equipment of lidar echo signal is the critical part of lidar system. In order to improve signal-to-noise ratio(SNR), data acquisition equipment should have the function of filtering and high-speed data accumulation. In order to meet the requirement of lidars with different repetition frequency, the parameters such as sampling depth and accumulating time should be reconfigurable. A universal data acquisition card of lidar echo signal (DAQ card) with a sampling rate of 20 MHz and reconfigurable parameters, which has the function of filtering and hardware accumulation, is realized by using FPGA as main control element. The test results show that the DAQ card achieves the basic parameter configuration function and accumulation function under the different repetition rate of the trigger signal, and the SNR is 71.9 dB. Compared with a foreign echo signal acquisition equipment, the DAQ card has longer detection range and higher SNR in high repetition frequency lidar.