Browsing by Author "Thorp, K. R."

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    Assimilating remote sensing observations of leaf area index and soil moisture for wheat yield estimates: An observing system simulation experiment
    (American Geophysical Union, 2012-05-17) Nearing, G. S.; Crow, W. T.; Thorp, K. R.; Moran, M. S.; Reichle, R. H.; Gupta, H. V.; University of Arizona; United States Department of Agriculture (USDA); National Aeronautics & Space Administration (NASA); NASA Goddard Space Flight Center; University of Alabama Tuscaloosa
    Observing system simulation experiments were used to investigate ensemble Bayesian state-updating data assimilation of observations of leaf area index (LAI) and soil moisture (theta) for the purpose of improving single-season wheat yield estimates with the Decision Support System for Agrotechnology Transfer (DSSAT) CropSim-Ceres model. Assimilation was conducted in an energy-limited environment and a water-limited environment. Modeling uncertainty was prescribed to weather inputs, soil parameters and initial conditions, and cultivar parameters and through perturbations to model state transition equations. The ensemble Kalman filter and the sequential importance resampling filter were tested for the ability to attenuate effects of these types of uncertainty on yield estimates. LAI and theta observations were synthesized according to characteristics of existing remote sensing data, and effects of observation error were tested. Results indicate that the potential for assimilation to improve end-of-season yield estimates is low. Limitations are due to a lack of root zone soil moisture information, error in LAI observations, and a lack of correlation between leaf and grain growth.