Calibration of the National Ecological Observatory Network\u27s Airborne Observation Platforms

The National Ecological Observatory Network (NEON) is a continental-scale ecological observation facility funded by the National Science Foundation (NSF). NEON\u27s mission is to enable understanding and forecasting of the impacts of land-use change and invasive species by providing the infrastructure and consistent methodologies for the collection of continental-scale ecological data. The Airborne Observation Platform (AOP) will play a unique role by collecting regional scale remote sensing data surrounding the NEON sites. This is expected to enable scaling of individual in-situ measurements collected by NEON or others to those collected by external satellite-based remote sensing systems. The airborne payload consists of the NEON Imaging Spectrometer (NIS), a full waveform and discrete LIDAR, and a high-resolution digital camera integrated into a Twin Otter aircraft. Three payloads on separate aircraft will provide coverage of 80 plus sites located in the 20 NEON Domains as well as targets of opportunity and PI-driven science. A key component of the NEON design is the consistent calibration of the airborne instruments to provide reliable and accurate scientific data over the full lifetime of the NEON observatory. The NEON Sensor Test Facility provides the facilities for the laboratory calibration of the AOP instrumentation. This work examines the spectral and radiometric calibration of the NIS in the NEON Sensor Test Facility. Recent work has focused on the traceability and uncertainty of the radiometric and spectral calibration and stability of the calibration from lab to operations. To verify the operational stability during acquisitions, a quality check algorithm has been developed to assess the raw NIS data prior to ingestion into the NEON processing framework. In addition, routine vicarious calibration flights are scheduled to independently verify the lab-based calibration. The work presented here also examines implemented improvements in characterizing the level of stray light in the NIS data. These corrections have significantly improved the fidelity of the spectroscopic data as well as improving the overall radiometric and spectral accuracy across the typical heterogeneous scenes included in the NEON collections