AERONET Instrument Troubleshooting Interface - Solutions for INGAAS VS SI DETECTORS Flag

Description
Extended-range Cimel instruments and the Model T contain both a Silicon (Si) and an InGaAs detector, each housed in a separate collimator tube. Both tubes view the same target, so their 1020 nm AOD retrievals should agree closely. A persistent difference between them indicates that one collimator has an obstruction or contamination affecting its optical throughput. This is among the most direct indicators of a dirty or obstructed collimator.

Condition(s)
Instruments with InGaAs and Silicon Detectors: Check Level 1.5 AOT data from 1020nm for the entire day. Flag if average AOT difference is more than 0.03 for any measurements.

How To Check/Test
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Solution Level 1 (< 5 minutes)
Check Collimator Cleaning.pdf

Model 4 and Standard Model 5: n/a

Extended Model 5 and Model T:
1. Remove collimator and check inside for webs or other obstructions.
2. Ensure collimator is installed in the correct orientation.

Solution Level 2 (more involved)
Model 4 and Standard Model 5: n/a

Extended Model 5 and Model T:
1. Inspect the lenses for significant contamination or residue. If found, do not clean. Take a picture and send to AERONET.

Solution Level 3 (last resort)
Model 4 and Standard Model 5: n/a

Extended Model 5 and Model T:
1. Confirm that the gains have not been changed (ask AERONET).
2. Return instrument for maintenance.