View Instrument

Instrument Type: imager (scanning monochromator) and sounder (a cloud cover radiometer), Operational Mode: Discrete mode, sweep mode or diffuser plate mode., Collection Type: nonspatial scanning, Other Information: The SBUV/2 is a nadir pointing nonspatial scanning instrument sensitive to radiation in the 160 nm to 400 nm ultraviolet spectrum. The SBUV/2 instruments on the TIROS-N satellites are designed to measure the total ozone in a vertical column beneath the satellite and its distribution with height in the atmosphere. The SBUV/2 contains a scanning double monochromator and a cloud cover radiometer (CCR) designed to measure ultraviolet (UV) spectral intensities. In its primary mode of operation, the monochromator measures solar radiation backscatter by the atmosphere in 12 discrete wavelength bands in the near-UV, ranging from 252.0 to 339.8 nm, each with a bandpass of 1.1 nm. The total-ozone algorithm uses the four longest wavelength bands (312.5, 317.5, 331.1, and 339.8 nm), whereas the profiling algorithm uses the shorter wavelengths. The cloud cover radiometer operates at 379 nm (i.e. outside the ozone absorption band) with a 3.0-nm bandpass and was designed to measure the reflectivity of the surface in the instantaneous field of view (IFOV). The SBUV/2 also makes periodic measurements of the solar flux by deploying a diffuser plate into the field of view (FOV) to reflect sunlight into the instrument. The monochromator and the cloud cover radiometer are mounted so that they look in the nadir direction with coincident nominal FOV's of 11.3 by 11.3 degrees. As the satellite moves in a Sun-synchronous orbit, the FOV traces 160-km wide paths on the ground. The earth rotates approximately 26 degrees during each orbit. The satellite footprint moves at a speed of about 6 km/sec. In discrete mode a set of 12 measurements, 1 for each discrete wavelength band, is taken every 32 seconds. The order of measurements is 252.0 to 339.8 and the integration time is 1.25 seconds per measurement. For each monochromator measurement there is a cloud cover radiometer measurement.