Publications

Othman, Y; Steele, C; St Hilaire, R (2018). Surface Reflectance Climate Data Records (CDRs) is a Reliable Landsat ETM plus Source to Study Chlorophyll Content in Pecan Orchards. JOURNAL OF THE INDIAN SOCIETY OF REMOTE SENSING, 46(2), 211-218.

Abstract
We evaluated the relationships among three Landsat Enhanced Thematic Mapper (ETM+) datasets, top-of-atmosphere (TOA) reflectance, surface reflectance climate data records (surface reflectance-(CDR)) and atmospherically corrected images using Fast Line-of-Sight atmospheric analysis of Spectral Hypercubes model (surface reflectance-(FLAASH)) and their linkto pecan foliar chlorophyll content(chl-cont). Foliar chlorophyll content as determined with a SPAD meter, and remotely-sensed data were collected from two mature pecan orchards (one grown in a sandy loam and the other in clay loam soil) during the experimental period. Enhanced vegetation index derived from remotely sensed data was correlated to chl-cont. At both orchards, TOA reflectance was significantly lower than surface reflectance within the 550-2400 nm wavelength range. Reflectance from atmospherically corrected images (surface reflectance-(CDR) and surface reflectance-(FLAASH)) was similar in the shortwave infrared (SWIR: 1550-1750 and 2080-2350 nm) and statistically different in the visible (350-700 nm). Enhanced vegetation index derived from surface reflectance-(CDR) and surface reflectance-(FLAASH) had higher correlation with chl-cont than TOA. Accordingly, surface reflectance is an essential prerequisite for using Landsat ETM+ data and TOA reflectance could lead to miss-/or underestimate chl-cont in pecan orchards. Interestingly, the correlation comparisons (Williams t test) between surface reflectance-(CDR) and chl-cont was statistically similar to the correlation between chl-cont and commercial atmospheric correction model. Overall, surface reflectance-(CDR), which is freely available from the earth explorer portal, is a reliable atmospherically corrected Landsat ETM+ image source to study foliar chlorophyll content in pecan orchards.

DOI:
10.1007/s12524-017-0690-x

ISSN:
0255-660X