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DOI	10.1117/12.2572293
	Validation of atmospheric correction approaches for Sentinel-2 under partly-cloudy conditions in an African agricultural landscape
	Kganyago, Mahlatse; Ovakoglou, Georgios; Mhangara, Paidamwoyo; Alexandridis, Thomas; Odindi, John; Adjorlolo, Clement; Mashiyi, Nosiseko
通讯作者	Kganyago, M (corresponding author), South African Natl Space Agcy, Earth Observat Directorate, Enterprise Bldg,Mark Shuttleworth St, ZA-0001 Pretoria, South Africa. ; Kganyago, M (corresponding author), Univ Witwatersrand, Sch Geog Archaeol & Environm Studies, ZA-2050 Johannesburg, South Africa.
会议名称	Conference on Remote Sensing of Clouds and the Atmosphere XXV held at SPIE Remote Sensing Conference
会议日期	SEP 21-25, 2020
会议地点	ELECTR NETWORK
英文摘要	Globally, remotely sensed agricultural monitoring is impeded by cloudy conditions which render the acquired images useless. In semi-arid landscapes, rainfed croplands dominate agricultural production; thus, the majority of planting occurs in the rainy season, characterized by erratic cloud cover. The clear-sky pixels in partly-cloudy images can be used to increase the number of useful observations for quantitative analysis. This is achieved by cloud screening and atmospheric correction (AC) processes. However, the effectiveness of various AC approaches under partly-cloudy conditions is still unknown. Many studies validate surface reflectance (SR) under clear-sky conditions, with only a few focusing on the validation of SR under partly-cloudy conditions. This study sought to validate Sentinel-2 SR products derived from various AC approaches, i.e., MAJA, Sen2Cor, iCor, and FORCE, using in-situ spectral measurements. A partly-cloudy image with >60% cloud cover, acquired over a semi-arid agricultural landscape and +/- 3 days of the field measurements, was used as a test case. The results showed R-2 of <0.2 with in-situ SR in the VIS and SWIR, and R-2 of similar to 0.6 in the Red-edge and NIR regions, attributable to low aerosol scattering effect in the NIR. However, RMSE, MAE, and BIAS error metrics showed consistently higher errors across all AC approaches and crop types, with varying magnitude per spectral band. This finding can be attributed to the high presence of clouds in the image, which enhanced the apparent path radiance, causing an overestimation of the aerosol optical thickness, hence an underestimation of SR. The need for further validation of SR under various cloud conditions emanates from this study, to ascertain the utility of AC approaches under such conditions. Overall, the results have implications for the utility of remotely sensed images for agricultural crop monitoring in partly-cloudy conditions.
英文关键词	Sentinel-2 Surface Reflectance Atmospheric correction Analysis-Ready-Data MAJA Sen2Cor iCor FORCE
来源出版物	REMOTE SENSING OF CLOUDS AND THE ATMOSPHERE XXV
ISSN	0277-786X
EISSN	1996-756X
出版年	2020
卷号	11531
ISBN	978-1-5106-3876-1; 978-1-5106-3875-4
出版者	SPIE-INT SOC OPTICAL ENGINEERING
类型	Proceedings Paper
语种	英语
开放获取类型	Green Published
收录类别	CPCI-S
WOS记录号	WOS:000632593600005
WOS类目	Meteorology & Atmospheric Sciences ; Remote Sensing ; Optics
WOS研究方向	Meteorology & Atmospheric Sciences ; Remote Sensing ; Optics
资源类型	会议论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/353175
作者单位	[Kganyago, Mahlatse; Mashiyi, Nosiseko] South African Natl Space Agcy, Earth Observat Directorate, Enterprise Bldg,Mark Shuttleworth St, ZA-0001 Pretoria, South Africa; [Ovakoglou, Georgios; Alexandridis, Thomas] Aristotle Univ Thessaloniki, Sch Agr, Lab Remote Sensing Spect & GIS, Thessaloniki 54124, Greece; [Kganyago, Mahlatse; Mhangara, Paidamwoyo; Adjorlolo, Clement] Univ Witwatersrand, Sch Geog Archaeol & Environm Studies, ZA-2050 Johannesburg, South Africa; [Odindi, John] Univ KwaZulu Natal, Sch Agr Earth & Environm Sci, P Bag X01, ZA-3209 Pietermaritzburg, South Africa; [Adjorlolo, Clement] African Union Dev Agcy AUDA NEPAD, 230 15th Rd, ZA-1685 Johannesburg, South Africa
推荐引用方式 GB/T 7714	Kganyago, Mahlatse,Ovakoglou, Georgios,Mhangara, Paidamwoyo,et al. Validation of atmospheric correction approaches for Sentinel-2 under partly-cloudy conditions in an African agricultural landscape[C]:SPIE-INT SOC OPTICAL ENGINEERING,2020.