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Principles for helicopters as platforms for optical wavelength remote sensing and the NASA GSFC/WFF helicopter remote sensing system

An airborne system developed by NASA Goddard Space Flight Center (GSFC) and Wallops Flight Facility (WFF) utilizing a helicopter as the platform has proven to be a versatile means of acquiring calibrated remote sensing data emphasizing spatial, spectral, temporal, bidirectional and polarization information domains. As the system evolved, it has been used for the acquisition of data in support of field measurement campaigns, such as: a study of the effects of atmospheric deposition on forest health, the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE), the Forest Ecosystems Dynamics (FED) Project, and the Boreal Ecosystem and Atmosphere Study (BOREAS). The data collected with the helicopter system during these projects have been used to develop fundamental relationships between vegetation parameters and remotely sensed measurements, validate atmosphere and vegetation models, address scaling issues, and provide low altitude data for use with instrument calibration studies. Off‐the‐shelf and experimental instrumentation have been flown as part of the system. Most recently, gyro‐stabilized, pointable mounts and an automatic sun‐tracking sun photometer for use with helicopters were specifically designed and fabricated for the system. The development stages of the helicopter system over a twelve‐year period are described and provide suggestions for various system configurations, while illustrating the advantages and limitations afforded to investigators using helicopter‐based systems.