Abstract: Due to the stability of the lunar reflectance and the fact that it is an exo-atmospheric target with flux levels close to levels observed by Earth Remote Sensing instruments, many sensors routinely measure the lunar spectral irradiance. While many sources of uncertainly that arise when vicariously calibrating sensors using land targets are eliminated, lunar measurements are complicated - though predictable - because of the lunar irradiance is a function of the relative positions of the Sun, Moon, and Observer among other variables. The United States Geological Survey has developed a model, called the Robotic Lunar Observatory (ROLO) Model of lunar reflectance/irradiance that accounts for changes in lunar irradiance as a function of these variables; utilizing the ROLO Model, NASA has demonstrated the ability to track sensor responsivity changes at the 0.1 % level. The current uncertainties in the ROLO Model are estimated to be between 3 % and 6 % in the VNIR spectral region and are not traceable to the International System of Units (the SI). The objective of the airborne Lunar Spectral Irradiance (air-LUSI) project is to make highly accurate (sub-0.5 % uncertainty), SI-traceable measurements of the lunar spectral irradiance in the VNIR region using a laboratory instrument on an airplane at 70,000 feet. The measurements, corrected for residual atmospheric attenuation, will be compared with the ROLO model-predicted exo-atmospheric lunar irradiance and may be used to establish limits on the uncertainty in the ROLO Model as well as to possibly serve as tie-points to the Model over this spectral range. The first step was to integrate the air-LUSI instrument onto a NASA ER-2 research aircraft and have Engineering Flights to demonstrate that the instrument concept was valid and that the instrument could function properly at-altitude. Two Engineering Flights took place in August 2018 in Palmdale, CA at NASA’s Armstrong Flight Research Center. The talk will focus on what happened during the deployment both from a technical and personal point of view; results of the radiometric measurements and the performance of the instrument lend insight into a path forward to lower uncertainty measurements during the next Flight Campaign and will be presented.
About the Speaker: Mr. Thomas Larason is an Electronics Engineer in the Sensor Science Division at the National Institute of Standards and Technology (NIST). His career at NIST began in 1989 where his research has focused on the development, characterization and calibration of detectors that measure ultraviolet, visible, and near infrared light. Additional research areas include the measurement of photocurrent, aperture area, and the development of new transfer standards. He has collaborated with both university and industry researchers on various projects, for example, investigating UV light sensors used for the inactivation of pathogens for drinking water. He has twice received the Department of Commerce Bronze Medal Award.
{Thomas C. Larason of NIST}
When
Thu Nov 29, 2018 5pm – 6pm Coordinated Universal Time
Where
Conference Room # 2552-2553 , NOAA Center for Weather and Climate Prediction, 5830 University Research Court, College Park, MD (map)
