<title>NPOESS VIIRS sensor design overview</title>

Abstract

A new era in remote sensing will begin with the launch of the National Polar-orbiting Operational Environment Satellite Systems (NPOESS) Preparatory Project (NPP) spacecraft in 2005, and the multiple operational NPOESS launches in sun-synchronous orbital planes (nominally 13:30, 17:30, or 21:30 local equatorial crossing times) starting in 2008. Users of polar-orbiting environmental satellite data will see a profound improvement in the radiometric quality, spectral coverage, and spatial resolution of routinely available visible and infrared data relative to current operational civilian and military polar-orbiting systems. The improved data will be provided by the NPOESS Visible Infrared Imaging Radiometer Suite (VIIRS). VIIRS will provide Environmental Data Records (EDRs) to meet civilian and national defense operational requirements, including day and night cloud imagery, sea surface temperatures (SST), and ocean color. EDRs will be produced by ground processing of raw data records (RDRS) from the VIIRS sensor. VIIRS will replace three currently operating sensors: the Defense Meteorological Satellite Program (DMSP) Operational Line- scanning System (OLS), the NOAA Polar-orbiting Operational Environmental Satellite (POES) Advanced Very High Resolution Radiometer (AVHRR), and the NASA Earth Observing System (EOS Terra and Aqua) MODerate-resolution Imaging Spectroradiometer (MODIS). This paper describes the VIIRS all-reflective 22-band single-sensor design. VIIRS provides low noise (driven by ocean color for the reflective visible and near-IR spectral bands and by SST for the emissive mid and long-wave IR spectral), excellent calibration and stability (driven by aerosol, cloud, and SST), broad spectral coverage, and fine spatial resolution driven by the imagery EDR. In addition to improved radiometric, spectral, and spatial performance, VIIRS features DMSP OLS-like near- constant resolution, global twice-daily coverage in each orbit plane, and direct heritage to proven design innovations from the successful Sea-viewing Wide Field-of- view Sensor (SeaWiFS) and Earth Observing System (Terra) MODIS.