Water vapor and aerosol are two key atmospheric factors effecting the remote sensing image quality. As water vapor is responsible for most of the solar radiation absorption occurring in the cloudless atmosphere, accurate measurement of water content is important to not only atmospheric correction of remote sensing images, but also many other applications such as the study of energy balance and global climate change, land surface temperature retrieval in thermal remote sensing. A multi-spectral, single-angular, polarized radiometer called Polarized Scanning Atmospheric Corrector (PSAC) were developed in China, which are designed to mount on the same satellite platform with the principle payload and provide essential parameters for principle payload image atmospheric correction. PSAC detect water vapor content via measuring atmosphere reflectance at water vapor absorbing channels (i.e. 0.91 μm) and nearby atmospheric window channel (i.e. 0.865μm). A near-IR channel ratio method was implemented to retrieve column water vapor (CWV) amount from PSAC measurements. Field experiments were performed at Yantai, in Shandong province of China, PSAC aircraft observations were acquired. The comparison between PSAC retrievals and ground-based Sun-sky radiometer measurements of CWV during the experimental flights illustrates that this method retrieves CWV with relative deviations ranging from 4% ~ 13%. This method retrieve CWV more accurate over land than over ocean, as the water reflectance is low.
The infrared radiation characteristics of space object and its change regulation are the important information for object properties and on-orbit status estimate, which is of most significance for the application of space remote sensing detection. Ground-based infrared imaging detection system, equipped with the atmospheric synchronous correction system, can effectively obtain infrared radiation characteristics of space objects. However, due to its long distance away from the ground sensor, space object presents point source features for the imaging system, thus it produces diffusion on the focal plane, which results in serious distortion of radiance information characterized by each pixel and optical signals aliasing between the target and the background. Therefore, significant error is introduced in the retrieval result. According to ground-based infrared imaging detection system, a retrieval method of infrared radiance of space point source target is proposed. By analyzing the radiative transfer from target to image plane and the imaging process, a calculation method of space point source target radiation is derived, which takes energy diffusion, pixel signals aliasing, FPA duty cycle and other factors into consideration. By the ground-based experiment of measuring the infrared standard stars, the inversion results of standard stars irradiance are compared to their nominal values, and the accuracy is better than 20%. The results show that this method can provide an effective way for acquisition of infrared radiation characteristics of space point source target.
The image quality of optical remote sensing satellite is affected by the atmosphere, thus the image needs to be corrected. Due to the spatial and temporal variability of atmospheric conditions, correction by using synchronous atmospheric parameters can effectively improve the remote sensing image quality. For this reason, a small light spaceborne instrument, the atmospheric synchronous correction device (airborne prototype), is developed by AIOFM of CAS(Anhui Institute of Optics and Fine Mechanics of Chinese Academy of Sciences). With this instrument, of which the detection mode is timing synchronization and spatial coverage, the atmospheric parameters consistent with the images to be corrected in time and space can be obtained, and then the correction is achieved by radiative transfer model. To verify the technical process and treatment effect of spaceborne atmospheric correction system, the first airborne experiment is designed and completed. The experiment is implemented by the "satellite-airborne-ground" synchronous measuring method. A high resolution(0.4 m) camera and the atmospheric correction device are equipped on the aircraft, which photograph the ground with the satellite observation over the top simultaneously. And aerosol optical depth (AOD) and columnar water vapor (CWV) in the imagery area are also acquired, which are used for the atmospheric correction for satellite and aerial images. Experimental results show that using the AOD and CWV of imagery area retrieved by the data obtained by the device to correct aviation and satellite images, can improve image definition and contrast by more than 30%, and increase MTF by more than 1 time, which means atmospheric correction for satellite images by using the data of spaceborne atmospheric synchronous correction device is accurate and effective.