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Radiometric calibration of the gome-2 instrument

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Author: Otter, G.C.J. · Dijkhuizen, N. · Vosteen, L.L.A. · Brinkers, S. · Gür, B. · Kenter, P.
Type:article
Date:2017
Publisher: Springer
Source:Urbach, H.P.Zhang, G., 3rd International Symposium of Space Optical Instruments and Applications, 26-29 June 2016, 192, 493-504
series:
Springer Proceedings in Physics
Identifier: 753497
ISBN: 9783319491837
Keywords: Electronics · Calibration · GOME-2 · METOP · Radiometry · Spectrometer · UV · VIS · NIR · Stray-light · High Tech Systems & Materials · Industrial Innovation · 2015 Nano Technology · OPT - Optics SSE - Space Systems Engineering · TS - Technical Sciences

Abstract

The Global Ozone Monitoring Experiment-2(GOME-2) represents one of the European instruments carried on board the MetOp satellite within the ESA’s “Living Planet Program”. Consisting of three flight models (FM’s) it is intended to provide long-term monitoring of atmospheric ozone and other trace gases over a time frame of 15–20 years, thus contributing valuable input towards climate and atmospheric research and providing near real-time data for use in air quality forecasting. The ambition to achieve highly accurate scientific results requires a thorough calibration and characterization of the instrument prior to launch with highly specialised sources. These calibration campaigns were performed by TNO in Delft in the Netherlands, in the “Thermal Vacuum Calibration Facility” of the institute. Due to refurbishment and/or storage of the instruments over a period of a few years, several re-calibration campaigns were necessary. These re-calibrations provided the unique opportunity to study the effects of long term storage and build up statistics on the instrument as well as the calibration methods used. During the re-calibration of the second flight model a difference was found in the radiometric calibration output, which was not understood initially. In order to understand the anomalies on the radiometry, a deep investigation was performed using numerous variations of the setup and different sources. The major contributor was identified to be a systematic error in the alignment, for which a correction was applied. Apart from this, it was found that the geometry of the sources influenced the results. Based on the calibration results combined with a theoretical geometrical hypothesis inferred that the on-ground calibration should mimic as close as possible the in-orbit geometry.