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Estimating Evaporative Fraction From Readily Obtainable Variables in Mangrove Forests of the Everglades, U.S.A.A remote-sensing-based model to estimate evaporative fraction (EF) the ratio of latent heat (LE; energy equivalent of evapotranspiration -ET-) to total available energy from easily obtainable remotely-sensed and meteorological parameters is presented. This research specifically addresses the shortcomings of existing ET retrieval methods such as calibration requirements of extensive accurate in situ micro-meteorological and flux tower observations, or of a large set of coarse-resolution or model-derived input datasets. The trapezoid model is capable of generating spatially varying EF maps from standard products such as land surface temperature [T(sub s)] normalized difference vegetation index (NDVI)and daily maximum air temperature [T(sub a)]. The 2009 model results were validated at an eddy-covariance tower (Fluxnet ID: US-Skr) in the Everglades using T(sub s) and NDVI products from Landsat as well as the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors. Results indicate that the model accuracy is within the range of instrument uncertainty, and is dependent on the spatial resolution and selection of end-members (i.e. wet/dry edge). The most accurate results were achieved with the T(sub s) from Landsat relative to the T(sub s) from the MODIS flown on the Terra and Aqua platforms due to the fine spatial resolution of Landsat (30 m). The bias, mean absolute percentage error and root mean square percentage error were as low as 2.9% (3.0%), 9.8% (13.3%), and 12.1% (16.1%) for Landsat-based (MODIS-based) EF estimates, respectively. Overall, this methodology shows promise for bridging the gap between temporally limited ET estimates at Landsat scales and more complex and difficult to constrain global ET remote-sensing models.
Document ID
20170007804
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Yagci, Ali Levent
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Santanello, Joseph A.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Jones, John
(Geological Survey Reston, VA, United States)
Barr, Jordan
(National Park Service Homestead, FL, United States)
Date Acquired
August 17, 2017
Publication Date
April 4, 2017
Publication Information
Publication: International Journal of Remote Sensing
Publisher: Taylor and Francis
Volume: 38
Issue: 14
ISSN: 0143-1161
e-ISSN: 1366-5901
Subject Category
Meteorology And Climatology
Statistics And Probability
Earth Resources And Remote Sensing
Report/Patent Number
GSFC-E-DAA-TN45789
Funding Number(s)
CONTRACT_GRANT: NNH15C048B
Distribution Limits
Public
Copyright
Other
Keywords
trapezoid
mangrove
everglades

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