Wavelength calibration of spectra measured by
the Global Ozone Monitoring Experiment:
variations along orbits and in time

J.H.G.M. van Geffen
Applied Optics  43, 695-706 (2004).

Abstract

The nadir-viewing Global Ozone Monitoring Experiment (GOME) spectrometer aboard the second European Remote Sensing satellite (ERS-2) measures spectra in the range 240-790 nm. For the near-real time delivery of ozone columns and profiles at KNMI, a tailor-made wavelength calibration method was developed. This method allows for a variation in both the location and the width of the spectral bins along the detector. The wavelength grid resulting from the calibration of GOME earthshine spectra varies along an orbit. This variation shows a significant correlation with instrument temperatures for a window around 306 nm; for other wavelength windows there is no significant correlation. The wavelength calibration in windows at short wavelengths, below about 300 nm, is hampered in the region known as the South Atlantic Anomaly, due to an increase of the impacts of charged particles on the detector in combination with the low signal-to-noise ratio for these wavelengths. The wavelength grid of calibrated solar spectra, measured once a day by GOME, shows over a period of six years fluctuations without an apparent pattern and no correlation with the degradation of the instrument.

 
Note:
The above abstract is the abstract as it was submitted. Applied Optics says it too long: it should be no more than 100 words. For that reason the abstract has been shorted, though that makes the abstract sadly rather incomplete and not so well readable as the original abstract. The shortened abstract reads as follows.

The nadir-viewing Global Ozone Monitoring Experiment (GOME) spectrometer aboard the second European Remote Sensing satellite (ERS-2) measures spectra in the range 240-790 nm. For the near-real time delivery of ozone columns and profiles at KNMI, a wavelength calibration method was developed which allows for a variation in both location and width of the spectral bins along the detector. The resulting wavelength grid of earthshine spectra varies along an orbit. This variation shows a correlation with instrument temperatures for a window around 306 nm; for other wavelength windows there is no correlation. The wavelength grid of calibrated solar spectra shows fluctuations without an apparent pattern and no correlation with instrument degradation.

contents

   Abstract
   1. Introduction
   2. The wavelength calibration method
      2.1 The wavelength grid
      2.2 The accuracy of the method
      2.3 Recalibration of GDP level-1 spectra
   3. Data used in the analysis of earthshine spectra
   4. Instrument temperatures
   5. Calibration results of earthshine spectra
      5.1 Wavelength window 4
      5.2 Wavelength windows 5-9
      5.3 Wavelength windows 1-3
   6. Variations in time of the calibration of solar spectra
   7. Concluding remarks
   Acknowledgements
   References
   Appendix
Note: Subsection 2.3 introduces the GomeCal package; see the GomeCal home page

===> PDF file of the paper in own typesetting (22 pages; 322 kB)

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created: 16 August 2002
last modified: 19 August 2020