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Yanbian University (延边大学) 2020

Water Surface Albedo Estimation of Typical Arid-semiarid Lakes in Northeast China Based on Sentinel-2A Images


Titre : Water Surface Albedo Estimation of Typical Arid-semiarid Lakes in Northeast China Based on Sentinel-2A Images

Auteur : 周昊昊

Grade : Master’s Theses 2020

Université : Yanbian University (延边大学)

Résumé partiel
Lake albedo is an important parameter to describe the energy balance of the water-air interface.It can describe the reflection capacity of the lake surface to the solar short-wave radiation,regulate the distribution process of the radiation energy between the lake and the atmosphere,and has an important impact on the local climate and ecological environment.However,previous studies have mostly focused on surface albedo,rarely involving lake albedo,and inadequate consideration of factors affecting water albedo.Most of the existing remote sensing inversion models of albedo have good applicability to land and will produce large errors when applied to lakes.Therefore,this paper intends to analyze lake albedo,focusing on the effects of astronomical factors(solar elevation angle),meteorological factors(wind speed)and water quality factors(chlorophyll-a concentration,turbid suspended matter)on lake albedo.Moreover,the sentinel-2 MSI sensor remote sensing method for lake albedo estimation was established for the first time by using sentinel-2 images and taking the energy transfer equation as the entry point.The specific work of this paper includes :(1)Detailed analysis of the effects of astronomical,meteorological and water quality factors on lake albedo.The solar elevation angle is the primary controlling factor of the change of lake albedo.The lake albedo decreases with the increase of the sun elevation angle.The parametric models of albedo and solar elevation angle developed in the ocean show different degree of underestimation in the inversion of inland lakes.Due to the strong backscattering of TSM in different solar elevation angle,the lake albedo increases with the increase of TSM,and the relationship is more obvious at high solar elevation angle,with the determination coefficient reaching 0.76.There was no significant correlation between lake albedo and chlorophyll-a concentration at low solar elevation angle,and the determination coefficient was 0.11.At high solar elevation angle,the albedo showed a positive correlation with the increase of chlorophyll-a concentration,with a determination coefficient of 0.47.However,compared with the TSM to the size of lake albedo,the concentration of chlorophyll a was much smaller.Wind waves indirectly affect lake albedo by affecting the TSM in shallow lakes.Therefore,the lake albedo is positively correlated with wind speed in the high solar elevation angle and the low solar elevation angle,with the determination coefficients of 0.62 and 0.50 respectively.CDOM and particle absorption have strong absorption effects at shorter wavelengths,affecting the distribution of incident solar radiation and its spectral distribution.However,there is not enough evidence to show that CDOM and particulate matter absorption will reduce the albedo of lakes.The change of lake albedo in this study area mainly depends on the backscattering characteristics of inorganic particulate matter.Atmospheric transmittance is closely related to water albedo

Mots clés : Lake Albedo ;Remote Sensing ;Sentinel-2 MSI ;Chlorophyll-a ;Total Suspended Matters ;

Présentation (CNKI)

Page publiée le 29 mars 2022