Solar-Blind Ultraviolet Upwelling Radiance Diurnal Variation Led by Observation Geometry Factors on Geostationary Attitude Sensor Limb Viewing

  • Features of SBUV earth image are assessed based on all-time simulation
  • A optimal spectral range is confirmed for recognizing available earth limb image
  • Point having high radiance and contrast simultaneously is nonexistent on earth limb

In this satellite autonomous navigation feasibility study on geostationary orbit using the ultraviolet (UV) attitude sensor, the solar-blind UV (SBUV) upwelling radiance spatial distributions from the Earth surface points or the limb viewing path are simulated every two hours in all seasons based on the MODTRAN4 model. The target points are arranged from where the sensor can receive the Earth’s radiance, including eight limb viewing points in the 0 - 90 km altitude range with an interval of 5 km and nine surface points. A hypothetical UV attitude sensor with 9.6° field of view is set at a geostationary orbit, 3.6 × 107 m away from Equator sea level. The nadir point of which is considered to be located at 102°E and the Equator. The results show that SBUV (200 - 280 nm) upwelling radiance from the limb viewing points can increase to a maximum and then decrease with the increase in limb points altitude. The average SBUV radiance on the observation plane presents a regular bright crescent or ring, which has the maximum at about 0.433 W m-2 sr-1 μm-1 at 50 - 60 km altitude. The maximum upwelling radiance in the 242 - 267 nm spectra has the optimal characteristic considering the contrast and maximum altitude radiance continuity at the limb points.

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Published by The Chinese Geoscience Union