Reconstruction of Satellite-Retrieved Land-Surface Reflectance Based on Temporally-Continuous Vegetation IndicesReport as inadecuate




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1

State Key Laboratory of Remote Sensing Science, School of Geography, Beijing Normal University, Beijing 100875, China

2

College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China

3

Department of Geographical Sciences, University of Maryland, College Park, MD 20742, USA





*

Author to whom correspondence should be addressed.



Academic Editors: Richard Müller and Prasad S. Thenkabail

Abstract Land-surface reflectance, estimated from satellite observations through atmospheric corrections, is an essential parameter for further retrieval of various high level land-surface parameters, such as leaf area index LAI, fraction of absorbed photosynthetically active radiation FAPAR, and surface albedo. Although great efforts have been made, land-surface reflectance products still contain considerable noise caused by, e.g., cloud or mixed-cloud pixels, which results in temporal and spatial inconsistencies in subsequent downstream products. In this study, a new method is developed to remove the residual clouds in the Moderate Resolution Imaging Spectroradiometer MODIS land-surface reflectance product and reconstruct time series of surface reflectance for the red, near infrared NIR, and shortwave infrared SWIR bands. A smoothing method is introduced to calculate upper envelopes of vegetation indices VIs from the surface reflectance data and the cloud contaminated reflectance data are identified using the time series VIs and the upper envelopes of the time series VIs. Surface reflectance was then reconstructed according to cloud-free surface reflectance by incorporating the upper envelopes of the time series VIs as constraint conditions. The method was applied to reconstruct time series of surface reflectance from MODIS-TERRA surface reflectance product MOD09A1. Temporal consistency analysis indicates that the new method can reconstruct temporally-continuous time series of land-surface reflectance. Comparisons with cloud-free MODIS-AQUA surface reflectance product MYD09A1 over the BELMANIP Benchmark Land Multisite Analysis and Intercomparison of Products sites in 2003 demonstrate that the new method provides better performance for the red band R2 = 0.8606 and RMSE = 0.0366 and NIR band R2 = 0.6934 and RMSE = 0.0519, than the time series cloud detection TSCD algorithm R2 = 0.5811 and RMSE = 0.0649; and R2 = 0.5005 and RMSE = 0.0675, respectively. View Full-Text

Keywords: surface reflectance; MODIS; vegetation index; reconstruction; cloud detection surface reflectance; MODIS; vegetation index; reconstruction; cloud detection





Author: Zhiqiang Xiao 1,* , Shunlin Liang 1,3, Tongtong Wang 1 and Qiang Liu 2

Source: http://mdpi.com/



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