In-flight radiometric and polarimetric calibration of the Directional Polarimetric Camera onboard the GaoFen-5 satellite over the ocean

doi:10.1364/AO.422980

	In-flight radiometric and polarimetric calibration of the Directional Polarimetric Camera onboard the GaoFen-5 satellite over the ocean
	Qie, Lili 2; Li, Zhengqiang 2; Zhu, Sifeng 2; Xu, Hua 2; Xie, Yisong 2; Qiao, Rui 2; Hong, Jin 1; Tu, Bihai 1
刊名	APPLIED OPTICS
	2021-08-20
卷号	60
ISSN号	1559-128X
DOI	10.1364/AO.422980
通讯作者	Li, Zhengqiang(lizq@radi.ac.cn)
英文摘要	The Directional Polarimetric Camera (DPC) is the first Chinese multi-angle polarized Earth observation satellite sensor, which was successfully launched on 9 May 2018, onboard the GaoFen-5 satellite in the Chinese High-Resolution Earth Observation Program. The DPC's observation is one of the most important space-borne multi-spectral, multi-angular polarimetric measurements of the global Earth-atmosphere system at the present stage. Although rigorous radiometric calibration had been performed for the DPC before launch, its in-flight performance may change because of the process of launch, harsh environment of space, and aging of the sensor. Due to the absence of the onboard calibration system, vicarious calibration methods are necessary for the DPC's in-flight performance monitoring and calibration. In this paper, we adapted the Rayleigh absolute calibration method, the sun glint inter-band calibration method, and the sun glint polarization calibration method to the DPC sensor. First, the calibration errors of these three methods caused by ancillary data uncertainties (e.g., aerosol, chlorophyll concentration, absorption gases amount, and wind speed) were analyzed in detail. The error budgets show that the aerosol parameters (optical thickness and aerosol model) are some of the critical factors affecting both the radiometric and polarimetric calibration accuracies for the Rayleigh and sun glint methods. The DPC radiometric and polarimetric in-flight calibration during its commissioning phase was then implemented. The absolute coefficients of short spectral bands (443, 490, 565, and 670 nm) were calibrated by the well-characterized Rayleigh scattering signal over the ocean. Using the 565 nm band as a reference band, the Rayleigh absolute calibration was then transferred to other bands (443, 490, 670, and 865 nm) through inter-band calibration using the specular reflection of the sun over the ocean. The polarization measurements of the DPC at polarized bands (490, 670, and 865 nm) were calibrated with the polarized reflection of the sun glint over ocean. The preliminary results show that the radiometric sensitivity of the DPC changed very little after launch at the four visible bands. The absolute calibration coefficient differences from pre-flight calibration are smaller than 0.5% at the 443 and 670 nm bands, while they are within +/- 2% at the 490 and 565 nm bands. However, a large deviation at 865 nm band of about 9% from pre-flight calibration was indicated by the sun glint inter-band calibration. The degree of linear polarization measurement of the DPC is validated with high accuracy of about 0.02 at the 865 nm band, while the deviation at 490 and 670 nm bands are relatively larger, reaching 0.04. The DPC/GaoFen-5 shows a good in-flight performance of radiometric measurement and generally reliable polarimetric measurement after launch. (C) 2021 Optical Society of America
资助项目	National Natural Science Foundation of China[41925019] ; National Natural Science Foundation of China[41771396] ; National Natural Science Foundation of China[41671364] ; National Natural Science Foundation of China[41601385] ; Hainan Provincial Natural Science Foundation of China[418QN302]
WOS关键词	POLARIZATION ; AEROSOL ; IMPROVEMENT ; LAND ; 6S
WOS研究方向	Optics
语种	英语
出版者	OPTICAL SOC AMER
WOS记录号	WOS:000687563200019
资助机构	National Natural Science Foundation of China ; Hainan Provincial Natural Science Foundation of China
内容类型	期刊论文
源URL	[http://ir.hfcas.ac.cn:8080/handle/334002/125077]
专题	中国科学院合肥物质科学研究院
通讯作者	Li, Zhengqiang
作者单位	1.Chinese Acad Sci, Anhui Inst Opt & Fine Mech, Key Lab Opt Calibrat & Characterizat, Hefei 230031, Peoples R China 2.Chinese Acad Sci, Aerosp Informat Res Inst, State Environm Protect Key Lab Satellite Remote S, Beijing 100101, Peoples R China
推荐引用方式 GB/T 7714	Qie, Lili,Li, Zhengqiang,Zhu, Sifeng,et al. In-flight radiometric and polarimetric calibration of the Directional Polarimetric Camera onboard the GaoFen-5 satellite over the ocean[J]. APPLIED OPTICS,2021,60.
APA	Qie, Lili.,Li, Zhengqiang.,Zhu, Sifeng.,Xu, Hua.,Xie, Yisong.,...&Tu, Bihai.(2021).In-flight radiometric and polarimetric calibration of the Directional Polarimetric Camera onboard the GaoFen-5 satellite over the ocean.APPLIED OPTICS,60.
MLA	Qie, Lili,et al."In-flight radiometric and polarimetric calibration of the Directional Polarimetric Camera onboard the GaoFen-5 satellite over the ocean".APPLIED OPTICS 60(2021).