Validation of NEON airborne remote sensing data

Background/Question/Methods

The National Ecological Observatory Network (NEON) is a continental-scale research platform that will collect information on ecosystems across the United States to advance our understanding and ability to forecast environmental change at the continental-scale. The Airborne Observation Platform (AOP) will fly an instrument suite consisting of a visible-to-shortwave infrared imaging spectrometer, a full waveform LiDAR, and a high-resolution digital camera. NEON AOP will focus on several of the terrestrial Essential Climate Variables (ECV) including bioclimate, biodiversity, biogeochemistry, and land use products. These variables are collected throughout a network of 60 sites across the Continental United States, Alaska, Hawaii and Puerto Rico via ground-based and airborne measurements.

A series of AOP test flights were conducted during the first year of NEON construction with the goal to test out instrument functionality and performance, exercise our remote sensing collection protocols, and provide data for algorithm and product validation. These test flights will attempt to address the following questions: What is the optimal remote sensing data collection protocol to meet NEON science requirements? How do aircraft altitude, spatial sampling, spatial resolution, and LiDAR instrument configuration affect data retrievals? What are appropriate algorithms to derive ECVs from AOP data? What methodology should be followed to validate AOP remote sensing products and how should ground truth data be collected? Early test flights were focused on radiometric and geometric calibration as well as processing from raw data to Level-1 products. Next, flights were conducted with a focus on vegetation chemistry and structure measurements. Vegetation field sampling measurements were performed in coordination with the test flights.

Results/Conclusions

The AOP test flights conducted during 2012 proved to be extremely valuable to verify instrument functionality and performance, exercise remote sensing collection protocols, and provide data for algorithm and product validation. Preliminary results for NEON AOP Level-0 to Level-1 processing are presented including the radiometric and geometric calibration of the AOP instruments. Efforts are currently underway to develop algorithms for Level-4 NEON science data products and the ground truth data collected coincidently with the flights are being used to validate those products. The 2012 flight campaigns are just the first of several test flights that will take place over the next few years as part of the NEON observatory construction. Lessons learned from these early campaigns will inform both airborne and ground data collection methodologies for future campaigns as well as guide the AOP sampling strategy before NEON enters full science operations.