Opened 12 years ago

Closed 11 years ago

#75 closed task (fixed)

Acquire 2008 radiometric calibration

Reported by: mggr Owned by: mggr
Priority: immediate Milestone: 2008 data processing completion
Component: ARSF Keywords:
Cc: Other processors:

Description

We need copies of the ATM, CASI, Eagle and Hawk calibration files as soon as possible in the year.

The expectation is that Chris MacLellan of FSF is going to calibrate the CASI (and Specim?) early Dec 2007.

Attachments (2)

atmcomparisons.png (344.5 KB) - added by mark1 11 years ago.
screenshots of 2007/2008 ATM against averaged Eagle bands
calib_stuff.ods (55.6 KB) - added by mark1 11 years ago.
Spreadsheet containing comparisons of averaged eagle spectra, 2007 and 2008 ATM

Download all attachments as: .zip

Change History (10)

comment:1 Changed 11 years ago by mggr

  • Priority changed from medium to immediate
  • Summary changed from Acquire radiometric calibration to Acquire 2008 radiometric calibration

Updates:

  • CASI is not being flown in the 2008 season
  • calibration was attempted in Dec 2007 but the calibrated bulb in FSF's integrating sphere blew
    • a smaller sphere and other lights allowed partial validation of the Specim Feb 2007 factory calibration, but no full calibration
  • ATM's 2007 post season and 2008 pre-season calibrations showed a marked difference to the 2007 pre-season calibration
    • ATM subsequently suffered a serious failure in the Ethiopia campaign (Jan/Feb 2008)
    • the 2007 pre-season was found to be the best match for all 2007 data (see #39 for details)
    • ATM has recovered (~April) and is being used again - the 2008 pre-season calibration will need comparing again 2008 data, and a recalibration should be made if there is any discrepancy.

comment:2 Changed 11 years ago by mggr

Many repeated attempts to reschedule a calibration:

  • Feb during engine replacements (failed due to lack of availability of bulbs?)
  • No luck in March
  • April attempted again (FSF unavailable?)
    • Chris apparently lost another bulb and now believes it may be the power regulator (getting checked)
    • Phil asked about using the Met Office integrating sphere at Exeter, but apparently this isn't likely to work out
  • May, tried for end of May during plane downtime, FSF unavailable
    • slim possibility of ~10 June (after steering committee), but might be tough to get FSF and in peak flying season (Kidlington suggests end of July may be better..)

comment:3 Changed 11 years ago by mggr

Very initial comparison of ATM vs Eagle data (mark1's) indicates the 2007 pre-season may still be better - probably need to redo ATM calibration.

comment:4 Changed 11 years ago by mggr

Discussed Specim radiometric calibration situation during Gary's visit (also showed him PML's facilities in addition to re-discussing access to the Met Office integrating sphere). Conclusions:

  • push for a calibration in July/Aug or Aug/Sept (to align with LIDAR testing, to avoid taking a week of the flying season and to allow FSF time to schedule)
  • raise at steering committee
  • deliver data with 2007 calibration (stability of instruments unknown :/), with a promise to notify and redeliver if there's a problem when 2008 calibration becomes available

comment:5 Changed 11 years ago by mggr

Raised at steering committee. FSF trying to go for late July for another attempt.

comment:6 Changed 11 years ago by mark1

Comparisons between 2007 and 2008 ATM calibrations and Eagle have been done for 4 flight lines from 2 separate projects. Results can be seen in spreadsheet and images at ~arsf/calibration/2008/atm2007_2008_comparisons Also see attached spreadsheet and screenshot for overview.

Changed 11 years ago by mark1

screenshots of 2007/2008 ATM against averaged Eagle bands

Changed 11 years ago by mark1

Spreadsheet containing comparisons of averaged eagle spectra, 2007 and 2008 ATM

comment:7 Changed 11 years ago by mggr

Calibration data gathered at FSF Edinburgh 21-23 July! Starting to process it.

comment:8 Changed 11 years ago by mggr

  • Resolution set to fixed
  • Status changed from new to closed

Detailed report on the attempt at Reports. Short version - good enough for verifying the calibration, but too much non-uniformity in the sphere for a real calibration.

Closing this ticket as all future work will be on 2009 calibration..

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