Satellite passive microwave remote sensing for monitoring global land surface phenology

Matthew O. Jones, Lucas A. Jones, John S. Kimball, Kyle C. McDonald

Research output: Contribution to journalArticlepeer-review

216 Scopus citations

Abstract

Vegetation phenology characterizes seasonal life-cycle events that influence the carbon cycle and land- atmosphere water and energy exchange. We analyzed global phenology cycles over a six year record (2003-2008) using satellite passive microwave remote sensing based Vegetation Optical Depth (VOD) retrievals derived from daily time series brightness temperature (Tb) measurements from the Advanced Microwave Scanning Radiometer on EOS (AMSR-E) and other ancillary data inputs. The VOD parameter derives vegetation canopy attenuation at a given microwave frequency (18.7 GHz) and varies with canopy height, density, structure and water content. An error sensitivity analysis indicates that the retrieval algorithm can resolve the VOD seasonal cycle over a majority of global vegetated land areas. The VOD results corresponded favorably (p<0.01) with vegetation indices (VIs) and leaf area index (LAI) information from satellite optical-infrared (MODIS) remote sensing, and phenology cycles determined from a simple bioclimatic growing season index (GSI) for over 82% of the global domain. Lower biomass land cover classes (e.g. savannas) show the highest correlations (R=0.66), with reduced correspondence at higher biomass levels (0.03<R<0.51) and higher correlations for homogeneous land cover areas (0.41<R<0.83). The VOD results display a unique end-of-season signal relative to VI and LAI series, and may reflect microwave sensitivity to the timing of vegetation biomass depletion (e.g. leaf abscission) and associated changes in canopy water content (e.g. dormancy preparation). The VOD parameter is independent of and synergistic with optical-infrared remote sensing based vegetation metrics, and contributes to a more comprehensive view of land surface phenology.

Original languageEnglish
Pages (from-to)1102-1114
Number of pages13
JournalRemote Sensing of Environment
Volume115
Issue number4
DOIs
StatePublished - Apr 15 2011

Funding

This study was carried out with funding from the NASA Terrestrial Ecology program . The AMSR-E T b data and MODIS land cover in EASE grid format were provided by the National Snow and Ice Data Center (NSIDC). Other MODIS data were provided by the EOS data gateway, and NNR meteorological data were provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA ( http://www.cdc.noaa.gov ). The independent emissivity database was provided by Jean-Luc Moncet and Pan Liang of Atmospheric and Environmental Research, Inc., ( http://www.aer.com/scienceResearch/mwrs/emis.html ). The AMSR-E global VOD database and associated biophysical retrievals from this study are available through the UMT online data archives ( ftp://ftp.ntsg.umt.edu/pub/data ) and the NSIDC ( http://nsidc.org/data/nsidc-0451.html ). This work was performed at the University of Montana (UMT) and at the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration.

FundersFunder number
National Aeronautics and Space Administration

    Keywords

    • AMSR-E
    • EVI
    • Growing season
    • LAI
    • MODIS
    • NDVI
    • Optical depth
    • Phenology
    • Vegetation index

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