Microwave and Optical-Infrared Satellite Remote Sensing of Global Vegetation Phenology
Matthew
O.
Jones, The University of Montana Flathead Lake Biological Station, matt.jones@ntsg.umt.edu
(Presenting)
John
S.
Kimball, The University of Montana Flathead Lake Biological Station, johnk@flbs.umt.edu
Lucas
A.
Jones, The University of Montana Flathead Lake Biological Station, lucas@ntsg.umt.edu
Kyle
C.
McDonald, Jet Propulsion Laboratory, kyle.mcdonald@jpl.nasa.gov
Global Land Surface Phenology (LSP) monitoring has largely involved satellite optical-infrared remote sensing of vegetation indices (VIs) including EVI, NDVI and LAI. The VI accuracy is constrained by clouds, solar illumination, smoke and aerosols, degrading the ability to monitor phenological events in key ecosystems including tropical and boreal forests. Satellite microwave observations are insensitive to clouds at lower frequencies (≤ 10 GHz) and independent of solar illumination. We developed an algorithm for global retrieval of vegetation optical depth (VOD) from AMSR-E, which responds to phenological changes in canopy biomass and water content. We examined global relations among AMSR-E VOD, MODIS VIs, and a bioclimatic phenology model from 2003-2008 and compared these observations with in situ tower measurements of ecosystem CO2 exchange. Our results show good VI-VOD correspondence across a majority of global biomes and reduced correspondence over cloudy regions due to VI related signal degradation and phase-shifts or lags between the VI and VOD phenology signals. The microwave VOD signal provided nearly double the number of high quality (QC) retrievals and relatively complete phenology time series over some tropical regions. Although the VOD and VI signals co-vary they do not detect identical changes in seasonal dynamics and are sensitive to independent yet complimentary surface characteristics. These multi-sensor data provide synergistic phenology information, including dynamic changes in both vegetation greenness and canopy biomass that are sensitive to seasonal changes in surface meteorology and land-atmosphere carbon exchange. This work was conducted at the University of Montana and Jet Propulsion Laboratory under contract to NASA.
Presentation Type: Poster
Poster Session: Ecosystems Science
NASA TE Funded Awards Represented:
McDonald, Kyle
Vegetation Phenology Assessment Using Satellite Radar Remote Sensing: Global Monitoring of Daily and Seasonal Changes in Canopy Structure and Water Status