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Title: Towards an improved LAI collection protocol via simulated field-based PAR sensing

In support of NASA’s next-generation spectrometer—the Hyperspectral Infrared Imager (HyspIRI)—we are working towards assessing sub-pixel vegetation structure from imaging spectroscopy data. Of particular interest is Leaf Area Index (LAI), which is an informative, yet notoriously challenging parameter to efficiently measure in situ. While photosynthetically-active radiation (PAR) sensors have been validated for measuring crop LAI, there is limited literature on the efficacy of PAR-based LAI measurement in the forest environment. This study (i) validates PAR-based LAI measurement in forest environments, and (ii) proposes a suitable collection protocol, which balances efficiency with measurement variation, e.g., due to sun flecks and various-sized canopy gaps. A synthetic PAR sensor model was developed in the Digital Imaging and Remote Sensing Image Generation (DIRSIG) model and used to validate LAI measurement based on first-principles and explicitly-known leaf geometry. Simulated collection parameters were adjusted to empirically identify optimal collection protocols. Furthermore, these collection protocols were then validated in the field by correlating PAR-based LAI measurement to the normalized difference vegetation index (NDVI) extracted from the “classic” Airborne Visible Infrared Imaging Spectrometer (AVIRIS-C) data (R2 was 0.61). The results indicate that our proposed collecting protocol is suitable for measuring the LAI of sparse forest (LAI < 3–5 (more » m2/m2)).« less
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [1]
  1. Rochester Institute of Technology, Rochester, NY (United States)
  2. Rochester Institute of Technology, Rochester, NY (United States); Univ. College London, London (United Kingdom)
Publication Date:
OSTI Identifier:
1263884
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Sensors
Additional Journal Information:
Journal Volume: 16; Journal Issue: 7; Journal ID: ISSN 1424-8220
Publisher:
MDPI AG
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
ORNL Program Development; USDOE
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION HyspIRI; AVIRIS; DIRSIG; leaf area index; photosynthetically active radiation