VIIRS constant spatial-resolution advantages

The Suomi National Polar-orbiting Partnership (NPP) Visible Infrared Imager Radiometer Suite (VIIRS) was launched on 28 October 2011, nearly 20 years after the conceptual definition began at the Hughes Aircraft Company's Santa Barbara Research Center. Constrained off-nadir pixel growth, producing constant or near-constant VIIRS spatial resolution over the entire scan swath, is a patented design feature that dramatically improves imaging radiometry compared to VIIRS predecessors. VIIRS ground-projected east–west (across the orbit track) and north–south (along the orbit track) pixel dimensions are constrained to within a factor of two from nadir to ±1500 km off-nadir (edge of scan) in all 22 VIIRS spectral bands. The capability is a valuable improvement to previous systems' six-fold across-track pixel growth over narrower swaths, while improving signal-to-noise ratio (SNR) without larger optics. The technique allows the VIIRS day/night band (DNB) to offer nearly 9- to over 50-fold finer and truly constant area spatial resolution with enhanced sensitivity and dynamic range compared with the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS). This article reviews constant resolution from concept to VIIRS implementation and compares several VIIRS applications to similar applications of systems VIIRS replaces to demonstrate advantages of the new capability.