Publications by Jane Hurley

Analysis of Rosetta/VIRTIS spectra of earth using observations from ENVISAT/AATSR, TERRA/MODIS and ENVISAT/SCIAMACHY, and radiative-transfer simulations

Planetary and Space Science 90 (2014) 37-59

J Hurley, PGJ Irwin, A Adriani, M Moriconi, F Oliva, F Capaccioni, A Smith, G Filacchione, F Tosi, G Thomas

Rosetta, the Solar System cornerstone mission of ESA's Horizon 2000 programme, consists of an orbiter and a lander, and is due to arrive at the comet 67P/Churyumov-Gerasimenko in May 2014. Following its 2004 launch, Rosetta carried out a series of planetary fly-bys and gravitational assists. On these close fly-bys of the Earth, measurements were taken by the Visible Infrared Thermal Imaging Spectrometer (VIRTIS). Analysis of these spectra and comparison with spectra acquired by Earth-observing satellites can support the verification of the inflight calibration of Rosetta/VIRTIS. In this paper, measurements taken by VIRTIS in November 2009 are compared with suitable coincident data from Earth-observing instruments (ESA-ENVISAT/AATSR and SCIAMACHY, and EOS-TERRA/MODIS). Radiative transfer simulations using NEMESIS (Irwin et al.; 2008) are fit to the fly-by data taken by VIRTIS, using representative atmospheric and surface parameters. VIRTIS measurements correlate 90% with AATSR's, 85-94% with MODIS, and 82-88% with SCIAMACHYs. The VIRTIS spectra are reproducible in the 1-5 μm region, except in the 1.4 μm deep water vapour spectral absorption band in the near-infrared in cases in which the radiance is very low (cloud-free topographies), where VIRTIS consistently registers more radiance than do MODIS and SCIAMACHY. Over these cloud-free regions, VIRTIS registers radiances a factor of 3-10 larger than SCIAMACHY and of 3-8 greater than MODIS. It is speculated that this discrepancy could be due to a spectral light leak originating from reflections from the order-sorting filters above the detector around 1.4 μm. © 2013 Elsevier Ltd.

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