The Soil Moisture-Atmosphere Coupling Experiment (SMACEX) was conducted over a four week period in the Walnut Creek Watershed near Ames, Iowa, from June 15-July 13, 2002. This multiple-tiered experiment has the objective of studying exchanges of water, carbon and energy between the soil, vegetation and atmosphere. The data collection involved ground-based and airborne measurements of energy fluxes, airborne and satellite remote sensing in the visible, near infrared and thermal infrared, vegetation density and cover measurements, ground-based Lidar observations of water vapor densities and soil moisture measurements.

The high-resolution remotely sensed imagery was acquired with the USU airborne multispectral system at three spatial resolutions. The entire watershed and study area was covered at 1.5 meter pixel resolution imagery in the short wave bands and 5 meter pixel resolution in the thermal infrared, four times over the course of the experiment, coinciding with Landsat 5, 7 and Aster overpasses. One-meter resolution imagery was acquired over the multiple fields containing the tower flux stations and along the Canadian Twin Otter flux aircraft transects. All imagery will be calibrated to a reflectance standard, using concurrent measurements of incoming irradiance over a calibrated standard reflectance panel with known bi-directional properties.

This paper will describe the airborne remote sensing measurements conducted during the experiment and present preliminary results comparing estimates of spatially distributed surface energy balance fluxes in the different corn and soybean fields with the measured fluxes at the ground stations.