Use of airborne incident and reflected solar radiation to characterize spatial variability of land use and Earth skin temperature around research tower sites

To better understand how point measurements of reflected radiation made from research tower sites are influenced by the spatial variability of land around those tower sites, an investigation using multiple visible and near-IR radiation sensors carried aboard an aircraft will be conducted. A partnership between NOAA's Atmospheric Turbulence and Diffusion Division (ATDD) in Oak Ridge, Tennessee and the University of Tennessee Space Institute (UTSI), in Tullahoma, Tennessee was formed to measure incident and reflected solar radiation around various research tower sites, including those in NOAA's Climate Reference Network (CRN). The primary purpose will be to characterize the spatial variability of land-use and reflected solar radiation in the visible and near-infrared (IR) bands (e.g. Earth skin temperature) and to provide an intermediate linkage between the point measurements of reflected solar radiation provided by the research towers and those measured over much greater areas by NOAA satellites making measurements at similar wavelengths.

Instruments to be used for this investigation will be a downward-looking Heitronics KT19.85-II IR Pyrometer (9.6-11.5 µm), a downward-looking high-resolution visible video camera system, one upward-looking and one downward-looking Ocean Optics USB2000+Vis+NIR spectrometers (200-1100 nm), one upward-looking Kipp & Zonen SP Lite solar radiation sensor (400-1100 nm), and one upward and one downward-looking Kipp & Zonen PAR Lite sensors (400-700 nm). Measurements of time, aircraft position, velocity, attitude, and absolute altitude will be made using a combination of Global Positioning Satellites (GPS), inertial attitude heading reference system (AHRS), and a Reigl high-range laser distance meter. The AHRS, laser altitude, and GPS position will be used to precisely locate the footprint of the various downward-looking instruments on the Earth's surface. The absolute altitude of the aircraft will also be used to provide a scale reference to measure the size of objects in the video camera's field of view. Operating altitudes will be approximately 1000 feet above ground level (AGL).

Initial flights will be made using UTSI Airborne Science research aircraft flying over the CRN tower site in Crossville, Tennessee, as well as the ATDD's research tower at Walker Branch Watershed in Oak Ridge, Tennessee. Data will be presented to show preliminary spatial variability around these sites in both the visible and near-IR bands.