MODIS leaf area index products: From validation to algorithm improvement

Research output: Contribution to journalArticle

Researchers

  • Wenze Yang
  • Bin Tan
  • Dong Huang
  • Miina Rautiainen

  • Nikolay V. Shabanov
  • Y. Wang
  • Jeffrey L. Privette
  • Karl Fred Huemmrich
  • Rasmus Fensholt
  • Inge Sandholt
  • M. Weiss
  • Douglas E. Ahl
  • Stith T. Gower
  • Ramakrishna R. Nemani
  • Yuri Knyazikhin
  • Ranga B. Myneni

Research units

  • Boston University
  • University of Helsinki
  • Goddard Earth Sciences and Technology Center
  • University of Maryland, Baltimore County
  • NASA Goddard Space Flight Center
  • University of Copenhagen
  • Institut national de la recherche agronomique
  • University of Wisconsin-Madison
  • NASA Ames Research Center

Abstract

Global products of vegetation green Leaf Area Index (LAI) and Fraction of Photosynthetically Active Radiation absorbed by vegetation (FPAR) are being operationally produced from Terra and Aqua Moderate Resolution Imaging Spectroradiometers (MODIS) at 1-km resolution and eight-day frequency. This paper summarizes the experience of several collaborating investigators on validation of MODIS LAI products and demonstrates the close connection between product validation and algorithm refinement activities. The validation of moderate resolution LAI products includes three steps: 1) field sampling representative of LAI spatial distribution and dynamic range within each major land cover type at the validation site; 2) development of a transfer function between field LAI measurements and high resolution satellite data to generate a reference LAI map over an extended area; and 3) comparison of MODIS LAI with aggregated reference LAI map at patch (multipixel) scale in view of geo-location and pixel shift uncertainties. The MODIS LAI validation experiences, summarized here, suggest three key factors that influence the accuracy of LAI retrievals: 1) uncertainties in input land cover data, 2) uncertainties in input surface reflectances, and 3) uncertainties from the model used to build the look-up tables accompanying the algorithm. This strategy of validation efforts guiding algorithm refinements has led to progressively more accurate LAI products from the MODLS sensors aboard NASA's Terra and Aqua platforms.

Details

Original languageEnglish
Article number1645288
Pages (from-to)1885-1896
Number of pages12
JournalIEEE Transactions on Geoscience and Remote Sensing
Volume44
Issue number7
Publication statusPublished - Jul 2006
MoE publication typeA1 Journal article-refereed

    Research areas

  • Fraction of Photosynthetically Active Radiation (FPAR) absorbed by vegetation, Leaf Area Index (LAI), Moderate Resolution Imaging Spectroradiometer (MODIS), Validation

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