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United States Department of Agriculture

Agricultural Research Service

Research Project: AIRBORNE MEASUREMENT OF LAND-SURFACE ENERGY, WATER AND CARBON FLUXES OVER HETEROGENEOUS
2012 Annual Report


1a.Objectives (from AD-416):
To determine spatially averaged evapotranspiration, as well as carbon and heat fluxes, between the plot and the regional scale (~20km) using a dedicated flux aircraft over irrigated agricultural region in the Texas High Plains (THS), to process and analyze the flux data using different aggregation techniques to enhance the utility of the data set for ALEXI/disALEXI model validation, scaling, and verification studies, and to provide additional flight activities and data collection to enhance the multi-disciplinary research occurrring during the intensive observation periods (i.e., providing boundary layer development data).


1b.Approach (from AD-416):
Work with UA_AERO scientist to coordinate and execute a series of airborne flux measurement campaigns. Use the resulting large-scale flux datasets to contrain/validate ALEXI model estimates and improve embedding algorithms.


3.Progress Report:

The goal of this project is to work with University of Alabama (UA) scientists to coordinate and execute a series of airborne flux measurement campaigns. The resulting large-scale flux datasets will be used to constrain/validate flux estimates from the Atmosphere-Land Exchange Inverse (ALEXI) model and to improve embedded algorithms. The Bushland Evapotranspiration and Agricultural Remote Sensing Experiment, 2008 (BEAREX08) intensive field experiment was conducted during the summer months of 2008 in Bushland, Texas. An intensive aircraft campaign was developed to coordinate airborne flux measurements by UA with airborne imaging acquisitions conducted by collaborators from Utah State. Ground-based measurements of evapotranspiration (ET) were collected with eddy covariance and Bowen ratio systems and large weighing lysimeters.

The collaborating scientists at UA collected airborne flux data on multiple days during BEAREX08 over the experiment site and on transects into adjacent areas to help in upscaling point ET measurements to field and watershed scales. The aircraft data are being processed to estimate both fluxes and contributing footprints on the land-surface in one-second fragments. These fragments (and associated footprints) have been collated into different contiguous and noncontiguous (land classification based) flux transects along the flight lines. Spatially averaged fluxes along the flight transects are being compared to gridded fluxes estimates generated using remote sensing models and to calibrating data from flux towers within the flight domain. Direct comparison between the gridded model fluxes and flux tower data were conducted and show good agreement at the point locations of the flux towers. The flux transect data collected by the aircraft measurements provide a means for evaluating spatial variations in modeled fluxes at specific points in time.


Last Modified: 12/19/2014
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