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Aerosol Robotic Network (AERONET)
AEROSOL OPTICAL DEPTH AEROSOL INVERSIONS SOLAR FLUX OCEAN COLOR Maritime Aerosol Network
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TROUBLESHOOTING - Asymmetric Almucantars
 
 

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Almucantar Scenerio

The alumucantar scenerio is the procedure where an direct sun observation is taken initially, then while maintaining the same solar zenith angle, a range of azimuth positions are measured as the sensor rotates on its axis. The latest software version allows the Cimel to divide this procedure into 2 steps--scanning 180 degrees on one side, then 180 degrees on the other, rather than performing a full rotation. Binding may still result when the rotating robot is inhibited by its cables rubbing on or catching on an obstruction (typically binding on the robot body itself). These measurements are taken at a range of airmasses, with greater frequency at the beginning an end of the day.

  • Observe a pair of azimuth scans and verify that the cables are not impeding the motion

A second possibility is that there is an obstruction of some kind in one of the collimators, e.g., a spider web.

  • Remove the collimator and look through it toward the sun to verify that it is free of contamination

To Initiate an Almucantar

In MANUAL mode:

  • Enter the scenario (SCN) mode
  • Scroll until PARK is displayed, then press GO
  • Scroll to GOSUN, then press GO
  • Scroll to TRACK, then press GO
  • Once the sensor is aligned on the sun, scroll to ALMUC, then press GO

    The Cimel should begin the automated almucantar procedure. Observe that the full rotation of the sensor head is not being inhibited by its cables contacting the robot body. Sometimes, the gray enclosure box needs to be moved closer to the robot to allow sufficient cable length for free movement.

  • After a few complete scans, scroll to OFF, then press GO.
    NOTE: The MANUAL almucantar procedure will continue indefinitely until terminated.
  • Scroll to PARK, then press GO.
  • Return the instrument to AUTO mode

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Last Updated: December 04, 2007