Publications by Fred Taylor

First observations of H2O and CO2 vapor in comet 67P/Churyumov-Gerasimenko made by VIRTIS onboard Rosetta


D Bockelee-Morvan, V Debout, S Erard, C Leyrat, F Capaccioni, G Filacchione, N Fougere, P Drossart, G Arnold, M Combi, B Schmitt, J Crovisier, M-C de Sanctis, T Encrenaz, E Kuehrt, E Palomba, FW Taylor, F Tosi, G Piccioni, U Fink, G Tozzi, A Barucci, N Biver, M-T Capria, M Combes, W Ip, M Blecka, F Henry, S Jacquinod, J-M Reess, A Semery, D Tiphene

Models of the global cloud structure on Venus derived from Venus Express observations

Icarus (2011)

JK Barstow, CCC Tsang, CF Wilson, PGJ Irwin, FW Taylor, K McGouldrick, P Drossart, G Piccioni, S Tellmann

Models of the global cloud structure on Venus derived from Venus Express observations

Icarus 217 (2012) 542-560

JK Barstow, CCC Tsang, CF Wilson, PGJ Irwin, FW Taylor, K McGouldrick, P Drossart, G Piccioni, S Tellmann

Spatially-resolved near-infrared spectra from the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on Venus Express have been used to derive improved models of the vertical structure and global distribution of cloud properties in the southern hemisphere of Venus. VIRTIS achieved the first systematic, global mapping of Venus at wavelengths within transparency windows in the 1.6-2.6. μm range, which are sensitive on the nightside to absorption by the lower and middle cloud layers of thermally-emitted radiation from the hot lower atmosphere (Taylor, F.W., Crisp, D., Bézard, B. [1997]. Venus II: Geology, Geophysics, Atmosphere, and Solar Wind Environment, pp. 325-351). The cloud model used to interpret the spectra is based on previous work by Pollack et al. (Pollack, J., Dalton, J., Grinspoon, D., Wattson, R., Freedman, R., Crisp, D., Allen, D., Bézard, B., de Bergh, C., Giver, L. [1993]. Icarus 103, 1-42), Grinspoon et al. (Grinspoon, D.H., Pollack, J.B., Sitton, B.R., Carlson, R.W., Kamp, L.W., Baines, K.H., Encrenaz, T., Taylor, F.W. [1993]. Planet. Space Sci. 41, 515-542) and Crisp (Crisp, D. [1986]. Icarus 67, 484-514), and assumes a composition for the cloud particles of sulfuric acid and water, with acid concentration as a free parameter to be determined. Other retrieved parameters are the average size of the particles and the altitude of the cloud base in the model. Latitudinal variation in the atmospheric temperature structure was incorporated using data from the Venus Radio Science experiment (VeRa). Values are estimated initially using wavelength pairs selected for their unique sensitivity to each parameter, and then validated by comparing measured to calculated spectra over the entire wavelength range, the latter generated using the NEMESIS radiative transfer and retrieval code (Irwin, P.G.J., Teanby, N.A., de Kok, R., Fletcher, L.N., Howett, C.J.A., Tsang, C.C.C., Wilson, C.F., Calcutt, S.B., Nixon, C.A., Parrish, P.D. [2008]. J. Quant. Spectrosc. Radiat. Trans. 109, 1136-1150). The sulfuric acid concentration in the cloud particles is found to be higher in regions of optically thick cloud. The cloud base altitude shows a dependence on latitude, reaching a maximum height near -50°. The increased average particle size near the pole found by Wilson et al. (Wilson, C.F., Guerlet, S., Irwin, P.G.J., Tsang, C.C.C., Taylor, F.W., Carlson, R.W., Drossart, P., Piccioni, G. [2008]. J. Geophys. Res. (Planets) 113, E12) and the finding of spatially variable water vapor abundance at35-40. km altitude first reported by Tsang et al. (Tsang, C.C.C., Wilson, C.F., Barstow, J.K., Irwin, P.G.J., Taylor, F.W., McGouldrick, K., Piccioni, G., Drossart, P., Svedhem, H. [2010]. Geophys. Res. Lett. 37, L02202) are both confirmed. The implications of these improved descriptions of cloud structure and variability for the chemistry, meteorology, and radiative energy balance on Venus are briefly discussed. © 2011 Elsevier Inc.

Forty years of satellite meteorology at Oxford


FW Taylor

Comparative planetology, climatology and biology of Venus, Earth and Mars


FW Taylor

Infrared limb sounding of Titan with the cassini composite infrared spectrometer: Effects of the mid-IR detector spatial responses: Errata

Applied Optics 49 (2010) 5575-5576

CA Nixon, NA Teanby, SB Calcutt, S Aslam, DE Jennings, VG Kunde, FM Flasar, PGJ Irwin, FW Taylor, DA Glenar, MD Smith

We provide a revised Table 5 for the paper by Nixon et al. [Appl. Opt. 48, 1912 (2009)], in which the abundances of13CO2and C18O were incorrect . © 2010 Optical Society of America.

Correlations between cloud thickness and sub-cloud water abundance on Venus


CCC Tsang, CF Wilson, JK Barstow, PGJ Irwin, FW Taylor, K McGouldrick, G Piccioni, P Drossart, H Svedhem

Martian atmosphere as observed by VIRTIS-M on Rosetta spacecraft


A Coradini, D Grassi, F Capaccioni, G Filacchione, F Tosi, E Ammannito, MC De Sanctis, V Formisano, P Wolkenberg, G Rinaldi, G Arnold, MA Barucci, G Bellucci, J Benkhoff, JP Bibring, A Blanco, D Bockelee-Morvan, MT Capria, R Carlson, U Carsenty, P Cerroni, L Colangeli, M Combes, M Combi, J Crovisier, P Drossart, T Encrenaz, S Erard, C Federico, U Fink, S Fonti, W-H Ip, PGJ Irwin, R Jaumann, E Kuehrt, Y Langevin, G Magni, T McCord, V Mennella, S Mottola, G Neukum, V Orofino, P Palumbo, G Piccioni, H Rauer, B Schmitt, D Tiphene, FW Taylor, GP Tozzi

Mars' south polar hood as observed by the Mars Climate Sounder


JL Benson, DM Kass, A Kleinboehl, DJ McCleese, JT Schofield, FW Taylor

Diviner lunar radiometer observations of cold traps in the moon's south polar region

Science 330 (2010) 479-482

DA Paige, MA Siegler, JA Zhang, PO Hayne, EJ Foote, KA Bennett, AR Vasavada, BT Greenhagen, JT Schofield, DJ McCleese, MC Foote, E DeJong, BG Bills, W Hartford, BC Murray, CC Allen, K Snook, LA Soderblom, S Calcutt, FW Taylor, NE Bowles, JL Bandfield, R Elphic, R Ghent, TD Glotch, MB Wyatt, PG Lucey

Diviner Lunar Radiometer Experiment surface-temperature maps reveal the existence of widespread surface and near-surface cryogenic regions that extend beyond the boundaries of persistent shadow. The Lunar Crater Observation and Sensing Satellite (LCROSS) struck one of the coldest of these regions, where subsurface temperatures are estimated to be 38 kelvin. Large areas of the lunar polar regions are currently cold enough to cold-trap water ice as well as a range of both more volatile and less volatile species. The diverse mixture of water and high-volatility compounds detected in the LCROSS ejecta plume is strong evidence for the impact delivery and cold-trapping of volatiles derived from primitive outer solar system bodies.

Structure and dynamics of the Martian lower and middle atmosphere as observed by the Mars Climate Sounder: Seasonal variations in zonal mean temperature, dust, and water ice aerosols


DJ McCleese, NG Heavens, JT Schofield, WA Abdou, JL Bandfield, SB Calcutt, PGJ Irwin, DM Kass, A Kleinbohl, SR Lewis, DA Paige, PL Read, MI Richardson, JH Shirley, FW Taylor, N Teanby, RW Zurek

The Lunar Reconnaissance Orbiter Diviner Lunar Radiometer Experiment

SPACE SCIENCE REVIEWS 150 (2010) 125-160

DA Paige, MC Foote, BT Greenhagen, JT Schofield, S Calcutt, AR Vasavada, DJ Preston, FW Taylor, CC Allen, KJ Snook, BM Jakosky, BC Murray, LA Soderblom, B Jau, S Loring, J Bulharowski, NE Bowles, IR Thomas, MT Sullivan, C Avis, EM De Jong, W Hartford, DJ McCleese

Venus: Not evil, just a bit unfortunate

ASTRONOMY & GEOPHYSICS 51 (2010) 26-31

FW Taylor

Venus Cloud Properties from Venus Express VIRTIS Observations

AAS/Division for Planetary Sciences Meeting Abstracts #42 42 (2010) 994-994

J Barstow, FW Taylor, CCC Tsang, CF Wilson, PGJ Irwin, P Drossart, G Piccioni

The Scientific Exploration of Mars

Cambridge University Press, 2010

FW Taylor

What do we know about Mars? What remains to be understood? Is there evidence of life there? Will humans ever travel there? The dream of exploring Mars has ...

Planetary atmospheres


FW Taylor

Variability of CO concentrations in the Venus troposphere from Venus Express/VIRTIS using a Band Ratio Technique

Icarus 201 (2009) 432-443

CCC Tsang, FW Taylor, CF Wilson, SJ Liddell, PGJ Irwin, G Piccioni, P Drossart, SB Calcutt

A fast method is presented for deriving the tropospheric CO concentrations in the Venus atmosphere from near-infrared spectra using the night side 2.3 μm window. This is validated using the spectral fitting techniques of Tsang et al. [Tsang, C.C.C., Irwin, P.G.J., Taylor, F.W., Wilson, C.F., Drossart, P., Piccioni, G., de Kok, R., Lee, C., Calcutt, S.B., and the Venus Express/VIRTIS Team, 2008a. Tropospheric carbon monoxide concentrations and variability on Venus with Venus Express/VIRTIS-M observations. J. Geophys. Res. 113, doi: 10.1029/2008JE003089. E00B08] to show that monitoring CO in the deep atmosphere can be done quickly using large numbers of observations, with minimal effect from cloud and temperature variations. The new method is applied to produce some 1450 zonal mean CO profiles using data from the first eighteen months of operation from the Visible and Infrared Thermal Imaging Spectrometer infrared mapping subsystem (VIRTIS-M-IR) on Venus Express. These results show many significant long- and short-term variations from the mean equator-to-pole increasing trend previously found from earlier Earth- and space-based observations, including a possible North-South dichotomy, with interesting implications for the dynamics and chemistry of the lower atmosphere of Venus. © 2009 Elsevier Inc. All rights reserved.

Spatial variability of carbon monoxide in venus' mesosphere from venus express/visible and infrared thermal imaging spectrometer measurements

Journal of Geophysical Research E: Planets 114 (2009)

PGJ Irwin, R De Kok, A Negrão, CCC Tsang, CF Wilson, P Drossart, G Piccioni, D Grassi, FW Taylor

[1] Observations of Venus' mesosphere by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS)-M instrument of Venus Express have been used to investigate the spatial distribution of CO above Venus' nightside cloud tops by fitting the CO absorption in the (1-0) CO band around 4.7 μm. We find little spatial variation in the abundance of CO at midlatitudes, with a retrieved abundance of approximately 40 ± 10 ppm just above the cloud tops between 65 and 70 km altitude. Unfortunately, we find it very difficult to constrain the abundance of CO in the cold polar collar, centered at about 70°S, as the retrieved temperature structure in the CO line-forming region masks the absorption lines. However, there is a possibility that CO increases toward the poles, as we detect a significant signature of high levels of CO over Venus' south polar dipole feature in all the observations analyzed so far. To constrain the abundance of CO more closely will require the analysis of higher-resolution VIRTIS-H observations. In addition, limb observations would greatly help to resolve any possible temperature/cloud ambiguities and allow us to assess vertical variations in the abundance of CO. Copyright 2008 by the American Geophysical Union.

Tropospheric carbon monoxide concentrations and variability on Venus from Venus Express/VIRTIS-M observations

Journal of Geophysical Research E: Planets 114 (2009)

CCC Tsang, PGJ Irwin, CF Wilson, FW Taylor, C Lee, R De Kok, P Drossart, G Piccioni, B Bezard, S Calcutt

[1] We present nightside observations of tropospheric carbon monoxide in the southern hemisphere near the 35 km height level, the first from Venus Express/Visible and Infrared Thermal Imaging Spectrometer (VIRTIS)-M-IR. VIRTIS-M data from 2.18 to 2.50 μm, with a spectral resolution of 10 nm, were used in the analysis. Spectra were binned, with widths ranging from 5 to 30 spatial pixels, to increase the signal-to-noise ratio, while at the same time reducing the total number of retrievals required for complete spatial coverage. We calculate the mean abundance for carbon monoxide at the equator to be 23 ± 2 ppm. The CO concentration increases toward the poles, peaking at a latitude of approximately 60°S, with a mean value of 32 ± 2 ppm. This 40% equator-to-pole increase is consistent with the values found by Collard et al. (1993) from Galileo/NIMS observations. Observations suggest an overturning in this CO gradient past 60°S, declining to abundances seen in the midlatitudes. Zonal variability in this peak value has also been measured, varying on the order of 10% (∼3 ppm) at different longitudes on a latitude circle. The zonal variability of the CO abundance has possible implications for the lifetime of CO and its dynamics in the troposphere. This work has definitively established a distribution of tropospheric CO, which is consistent with a Hadley cell circulation, and placed limits on the latitudinal extent of the cell. Copyright 2008 by the American Geophysical Union.

Infrared limb sounding of Titan with the Cassini Composite InfraRed Spectrometer: effects of the mid-IR detector spatial responses.

Appl Opt 48 (2009) 1912-1925

CA Nixon, NA Teanby, SB Calcutt, S Aslam, DE Jennings, VG Kunde, FM Flasar, PG Irwin, FW Taylor, DA Glenar, MD Smith

The composite infrared spectrometer (CIRS) instrument on board the Cassini Saturn orbiter employs two 1x10 HgCdTe detector arrays for mid-infrared remote sensing of Titan's and Saturn's atmospheres. In this paper we show that the real detector spatial response functions, as measured in ground testing before launch, differ significantly from idealized "boxcar" responses. We further show that neglecting this true spatial response function when modeling CIRS spectra can have a significant effect on interpretation of the data, especially in limb-sounding mode, which is frequently used for Titan science. This result has implications not just for CIRS data analysis but for other similar instrumental applications.