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

The nadir-viewing Global Ozone Monitoring Experiment spectrometer aboard the second European Remote Sensing satellite measures spectra in the range of 240-790 nm. For the near-real-time delivery of ozone columns and profiles at the Royal Netherlands Meteorological Institute, a wavelength-calibration method was developed that allows for variation in both location and width of the spectral bins along the detector. The resultant wavelength grid of earthshine spectra varies along an orbit. This variation shows a correlation with instrument temperatures for a window near 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.