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MODIS Terrestrial Primary Production, Evapotranspiration and Disturbance Index Data Sets

Maosheng Zhao, NTSG, U of MT, zhao@ntsg.umt.edu (Presenting)
Qiaozhen Mu, NTSG, U of MT, qiaozhen@ntsg.umt.edu
David Mildrexler, NTSG, U of MT, drexler@ntsg.umt.edu
Faith Ann Heinsch, NTSG, U of MT, faithann@ntsg.umt.edu
Steven W. Running, NTSG, U of MT, swr@ntsg.umt.edu

Timely and accurate monitoring of carbon and water cycles and major disturbances in terrestrial ecosystems is scientifically and societally significant. With remote sensing data from MODIS sensor onboard of NASA’s satellites, Numerical Terradynamic Simulation Group (NTSG) at university of Montana developed algorithms to map global terrestrial gross and net primary production (GPP and NPP), evapotranspiration (ET), and disturbance index (DI) at a spatial resolution of MODIS. Here we present the algorithms, validation and multiyear results for our MODIS GPP/NPP, ET and DI. The GPP/NPP algorithm is based on the logic of light use efficacy originally proposed by Monteith, while also incorporates major environmental stresses for plant growth induced by low temperature and water stress. The ET algorithm is based on the Penman-Monteith equation, with MODIS albedo for net radiation calculation, and MODIS LAI combined with major environmental stresses to estimate canopy conductance. Total daily ET is the summation of transpiration from plants and evaporation from soil. The DI is based on the opposite changes between surface greenness (MODIS EVI) and sensible heat energy (MODIS LST) in response to disturbances such as wildfires, clear cut, and land use change. Validation of GPP and ET at eddy flux towers shows that these data sets are reasonable across a diverse range of biomes and climate regimes. The consistency between our MODIS DI and fire perimeters obtained from field work also reveals that our DI is a robust method to map major disturbances. From 2000 to 2006, MODIS NPP negative anomalies at large scales are generally caused by widespread droughts, while ET has showed different spatial responses from NPP, suggesting that NPP and ET are controlled by different biophysical processes. Global total NPP anomalies are significantly inverted related to anomalies of atmospheric CO2 interannual growth rates. Together, our MODIS GPP/NPP, ET and DI provide key quantitative information on mass (carbon and water) and energy exchange between terrestrial ecosystems and atmosphere at continental and global scale.


NASA Carbon Cycle & Ecosystems Active Awards Represented by this Poster:

  • Award: NNX08AG87A
    Start Date: 2008-01-28
     
  • Award: NNG05GG13G
    Start Date: 2005-02-15
     

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