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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union

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Atmos. Meas. Tech., 10, 881-903, 2017
https://doi.org/10.5194/amt-10-881-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
09 Mar 2017
In-operation field-of-view retrieval (IFR) for satellite and ground-based DOAS-type instruments applying coincident high-resolution imager data
Holger Sihler1,2, Peter Lübcke2, Rüdiger Lang3, Steffen Beirle1, Martin de Graaf4,5, Christoph Hörmann1, Johannes Lampel1, Marloes Penning de Vries1, Julia Remmers1, Ed Trollope3,6, Yang Wang1, and Thomas Wagner1 1Max Planck Institute for Chemistry (MPIC), Hahn-Meitner-Weg 1, 55128 Mainz, Germany
2Institute of Environmental Physics (IUP), University of Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany
3European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), Eumetsat Allee 1, 64295 Darmstadt, Germany
4Royal Netherlands Meteorological Institute (KNMI), Utrechtseweg 297, 3731 GA De Bilt, the Netherlands
5Delft University of Technology (TU-Delft), Stevinweg 1, 2628 CN Delft, the Netherlands
6Telespazio VEGA Deutschland GmbH, Europaplatz 5, 64293 Darmstadt, Germany
Abstract. Knowledge of the field of view (FOV) of a remote sensing instrument is particularly important when interpreting their data and merging them with other spatially referenced data. Especially for instruments in space, information on the actual FOV, which may change during operation, may be difficult to obtain. Also, the FOV of ground-based devices may change during transportation to the field site, where appropriate equipment for the FOV determination may be unavailable.

This paper presents an independent, simple and robust method to retrieve the FOV of an instrument during operation, i.e. the two-dimensional sensitivity distribution, sampled on a discrete grid. The method relies on correlated measurements featuring a significantly higher spatial resolution, e.g. by an imaging instrument accompanying a spectrometer. The method was applied to two satellite instruments, GOME-2 and OMI, and a ground-based differential optical absorption spectroscopy (DOAS) instrument integrated in an SO2 camera. For GOME-2, quadrangular FOVs could be retrieved, which almost perfectly match the provided FOV edges after applying a correction for spatial aliasing inherent to GOME-type instruments. More complex sensitivity distributions were found at certain scanner angles, which are probably caused by degradation of the moving parts within the instrument. For OMI, which does not feature any moving parts, retrieved sensitivity distributions were much smoother compared to GOME-2. A 2-D super-Gaussian with six parameters was found to be an appropriate model to describe the retrieved OMI FOV. The comparison with operationally provided FOV dimensions revealed small differences, which could be mostly explained by the limitations of our IFR implementation. For the ground-based DOAS instrument, the FOV retrieved using SO2-camera data was slightly smaller than the flat-disc distribution, which is assumed by the state-of-the-art correlation technique. Differences between both methods may be attributed to spatial inhomogeneities.

In general, our results confirm the already deduced FOV distributions of OMI, GOME-2, and the ground-based DOAS. It is certainly applicable for degradation monitoring and verification exercises. For satellite instruments, the gained information is expected to increase the accuracy of combined products, where measurements of different instruments are integrated, e.g. mapping of high-resolution cloud information, incorporation of surface climatologies. For the SO2-camera community, the method presents a new and efficient tool to monitor the DOAS FOV in the field.


Citation: Sihler, H., Lübcke, P., Lang, R., Beirle, S., de Graaf, M., Hörmann, C., Lampel, J., Penning de Vries, M., Remmers, J., Trollope, E., Wang, Y., and Wagner, T.: In-operation field-of-view retrieval (IFR) for satellite and ground-based DOAS-type instruments applying coincident high-resolution imager data, Atmos. Meas. Tech., 10, 881-903, https://doi.org/10.5194/amt-10-881-2017, 2017.
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This paper presents the independent and simple IFR method to retrieve the FOV of an instrument, i.e. the two-dimensional sensitivity distribution. IFR relies on correlated measurements featuring a higher spatial resolution and was applied to two satellite instruments, GOME-2 and OMI, and a DOAS instrument integrated in an SO2 camera. Our results confirm the commonly applied FOV distributions. IFR is applicable for verification exercises as well as degradation monitoring in the field.
This paper presents the independent and simple IFR method to retrieve the FOV of an instrument,...
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