Faculty

CURRENT STUDENTS Robert Zellem (PTYS) FORMER STUDENTS Paulo Penteado, 2009 (PTYS)

Caitlin Griffith Professor Planetary atmospheres Ph.D., 1991, State University of New York, Stony Brook Kuiper   #424 626-3806 Years with LPL:  2002 to present RESEARCH INTERESTS Dr. Griffith investigates the chemical, dynamical and thermal structures of planetary atmospheres, using ground-based and spacecraft observations. The data are interpreted with radiative transfer calculations to measure the temperature, composition and dynamical signatures of planetary atmospheres. These results are analyzed with simple chemical, radiative and dynamical models to address questions on atmospheric structure and evolution. Currently Dr. Griffith is up to her elbows in the analysis of data from the Cassini spacecraft. She is particularly intrigued by Titan, Saturn’s largest moon, which she regards as a deranged version of Earth. On Titan methane acts like water and can exist as a gas in the atmosphere, or as liquid and ice, in rain, snow and lakes. Cassini images of Titan show features near the equator indicative of methane rivers and ancient shorelines reminiscent of Earth, thus suggesting wetter times underneath a cloudless sky. Titan’s methane clouds are found only near the south pole, and, in a narrow band lined up at -40 latitude, like a string of beads. This weather forecast contrasts Earth’s, where with the exception of a few deserts an umbrella may come in handy at any time and season. It is not entirely clear how Titan’s weather works and what created the dry shore lines and extensive rivers that the Cassini Huygens mission witnesses under Titan’s largely clear skies. Dr. Griffith’s present work aims to characterize the clouds, circulation, surface humidity and the stability of the atmosphere to understand the moon’s exotic weather. Additional efforts aim to quantify the mass and location of organic material that precipitates to the surface from the stratosphere. Surface sediments are produced from byproducts of the photolysis of methane, which depletes the methane inventory fast enough to obliterate the atmospheric supply in 10 million years. The sediments are thus vestiges of the past presence of methane in Titan’s atmosphere. The present lack of oceans or apparent surface liquids suggests that methane is supplied by recent cryo-volcanism. But it is still not clear how long Titan has had methane in its atmosphere. Surface sediments are observed in the form of extensive dunes. Yet, instead of dune-forming particulates, we expected the 80% of the surface sediments to be liquid ethane, the main product of methane photolysis. Recent work by Dr. Griffith suggests that ethane precipitates only in Titan's polar regions. Thus perhaps lack of lakes in Titan's well-imaged tropics occurs because ethane instead accumulates at the poles as lakes or ice caps depending on the polar surface temperatures. Dr. Griffith has also investigated the atmospheres of Jupiter, Saturn and their cousins, brown dwarfs. More about Dr. Griffith CURRENT SPACECRAFT INVOLVEMENT Cassini ADS PUBLICATIONS SEARCH NASA ADS Author search: Caitlin A. Griffith SELECTED PUBLICATIONS Tinetti, G., et al. EChO. Exoplanet characterisation observatory 2012ExA....34..311T Soderblom, J. M., et al. Modeling specular reflections from hydrocarbon lakes on Titan 2012Icar..220..744S Griffith, C. A., et al. Possible tropical lakes on Titan from observations of dark terrain 2012Natur.486..237G Griffith, C. A., et al. Radiative transfer analyses of Titan's tropical atmosphere 2012Icar..218..975G Le Mouélic, S., et al. Dissipation of Titan's north polar cloud at northern spring equinox 2012P&SS...60...86L Waldmann, I. P., et al. Ground-based Near-infrared Emission Spectroscopy of HD 189733b 2012ApJ...744...35W Rodriguez, S., et al. Titan's cloud seasonal activity from winter to spring with Cassini/VIMS 2011Icar..216...89R Lavvas, P., Griffith, C. A., Yelle, R. V.Condensation in Titan's atmosphere at the Huygens landing site 2011Icar..215..732L Moses, J. I., et al. Disequilibrium Carbon, Oxygen, and Nitrogen Chemistry in the Atmospheres of HD 189733b and HD 209458b 2011ApJ...737...15M Beaulieu, J.-P., et al. Methane in the Atmosphere of the Transiting Hot Neptune GJ436B? 2011ApJ...731...16B Mousis, O., et al. On the Volatile Enrichments and Heavy Element Content in HD189733b 2011ApJ...727...77M Beaulieu, J. P., et al. Water in the atmosphere of HD 209458b from 3.6-8 μm IRAC photometric observations in primary transit 2010MNRAS.409..963B Lavvas, P., Yelle, R. V., Griffith, C. A. Titan’s vertical aerosol structure at the Huygens landing site: Constraints on particle size, density, charge, and refractive index 2010Icar..210..832L Stephan, K., et al. Specular reflection on Titan: Liquids in Kraken Mare 2010GeoRL..3707104S Tinetti, G., et al. Probing the Terminator Region Atmosphere of the Hot-Jupiter XO-1b with Transmission Spectroscopy 2010ApJ...712L.139T Penteado, P. F., et al. Latitudinal variations in Titan’s methane and haze from Cassini VIMS observations 2010Icar..206..352P Penteado, P. F., Griffith, C. A. Ground-based measurements of the methane distribution on Titan 2010Icar..206..345P Swain, M. R., et al. A ground-based near-infrared emission spectrum of the exoplanet HD189733b 2010Natur.463..637S Tinetti, G., et al. Exploring extrasolar worlds: from gas giants to terrestrial habitable planets 2010FaDi..147..369T McKay, C. P., et al. Comparing methane and temperature profiles on Titan in 1980 and 2005 2009P&SS...57.1996M Barnes, J. W., et al. VIMS spectral mapping observations of Titan during the Cassini prime mission 2009P&SS...57.1950B Mousis, O., et al. Elemental abundances and minimum mass of heavy elements in the envelope of HD 189733b 2009A&A...507.1671M Swain, M. R., et al. Water, Methane, and Carbon Dioxide Present in the Dayside Spectrum of the Exoplanet HD 209458b 2009ApJ...704.1616S Griffith, C. A., et al. Characterization of Clouds in Titan's Tropical Atmosphere 2009ApJ...702L.105G Boudon, V., et al. Methane in Titan's atmosphere: from fundamental spectroscopy to planetology 2009ENews..40...17B Rodriguez, S., et al. Global circulation as the main source of cloud activity on Titan 2009Natur.459..678R Coustenis, A., et al. TandEM: Titan and Enceladus mission 2009ExA....23..893C Griffith, C. A. Storms, polar deposits and the methane cycle in Titan's atmosphere 2009RSPTA.367..713G Griffith, C. A., McKay, C. P., Ferri, F. Titan's Tropical Storms in an Evolving Atmosphere 2008ApJ...687L..41G Jaumann, R., et al. Fluvial erosion and post-erosional processes on Titan 2008Icar..197..526J Graves, S. D. B., et al. Rain and hail can reach the surface of Titan 2008P&SS...56..346G Ádámkovics, M., et al. Correction to ``Titan's bright spots: Multiband spectroscopic measurement of surface diversity and hazes'' 2008JGRE..11302S90A Jaumann, R., et al. Distribution of icy particles across Enceladus' surface as derived from Cassini-VIMS measurements 2008Icar..193..407J Coradini, A., et al. Identification of spectral units on Phoebe 2008Icar..193..233C The Cassini Vims Team, et al. Composition of Titan's surface from Cassini VIMS 2006P&SS...54.1524T McCord, T. B., et al. Composition of Titan's surface from Cassini VIMS 2006P&SS...54.1524M Jaumann, R., et al. High-resolution CASSINI-VIMS mosaics of Titan and the icy Saturnian satellites 2006P&SS...54.1146J Griffith, C. A., et al. Evidence for a Polar Ethane Cloud on Titan2006Sci...313.1620G Griffith, C. A. Planetary science: Titan's exotic weather 2006Natur.442..362G Ádámkovics, M., et al. Titan's bright spots: Multiband spectroscopic measurement of surface diversity and hazes 2006JGRE..11107S06A Brown, R. H., et al. Observations in the Saturn system during approach and orbital insertion, with Cassini's visual and infrared mapping spectrometer (VIMS) 2006A&A...446..707B Griffith, C. A., et al. The Evolution of Titan's Mid-Latitude Clouds 2005Sci...310..474G Barnes, J. W., et al. A 5-Micron-Bright Spot on Titan: Evidence for Surface Diversity 2005Sci...310...92B Greathouse, T. K., et al. Meridional variations of temperature, C2H2 and C2H6 abundances in Saturn's stratosphere at southern summer solstice 2005Icar..177...18G Griffith, C. A., et al. Observations of Titan's Mesosphere 2005ApJ...629L..57G Penteado, P. F., et al. Measurements of CH3D and CH4 in Titan from Infrared Spectroscopy 2005ApJ...629L..53P Baines, K. H., et al. The Atmospheres of Saturn and Titan in the Near-Infrared First Results of Cassini/vims 2005EM&P...96..119B Lorenz, R. D., et al. Convective plumes and the scarcity of Titan's clouds 2005GeoRL..3201201L Ádámkovics, M., et al. Spatially-resolved spectroscopy at 1.6 μm of Titan's atmosphere and surface 2004GeoRL..3117S05A Griffith, C. A., et al. Meridional transport of HCN from SL9 impacts on Jupiter 2004Icar..170...58G Yelle, R. V., Griffith, C. A. HCN fluorescence on Titan 2003Icar..166..107Y Bétrémieux, Y., Yelle, R. V., Griffith, C. A. HST observation of the atmospheric composition of Jupiter's equatorial region: evidence for tropospheric C2H2* 2003Icar..163..414B Griffith, C. A., et al. Evidence for the Exposure of Water Ice on Titan's Surface 2003Sci...300..628G Geballe, T. R., et al. High-Resolution 3 Micron Spectroscopy of Molecules in the Mesosphere and Troposphere of Titan 2003ApJ...583L..39G Brown, M. E., Bouchez, A. H., Griffith, C. A. Direct detection of variable tropospheric clouds near Titan's south pole 2002Natur.420..795B Yelle, R. V., Griffith, C. A., Young, L. A. Structure of the Jovian Stratosphere at the Galileo Probe Entry Site 2001Icar..152..331Y Griffith, C. A., Hall, J. L., Geballe, T. R. Detection of Daily Clouds on Titan 2000Sci...290..509G Griffith, C. A., Yelle, R. V. Equilibrium Chemistry in a Brown Dwarf's Atmosphere: Cesium in Gliese 229B 2000ApJ...532L..59G Griffith, C. A., Yelle, R. V. Disequilibrium Chemistry in a Brown Dwarf's Atmosphere: Carbon Monoxide in Gliese 229B 1999ApJ...519L..85G Griffith, C. A., Yelle, R. V., Marley, M. S. The Dusty Atmosphere of the Brown Dwarf Gliese 229B 1998Sci...282.2063G Griffith, C. A., Transient clouds in Titan's lower atmosphere 1998Natur.395..575G Lara, L.-M., et al. High-Resolution 10-micronmeter Spectroscopy of Ammonia and Phosphine Lines on Jupiter 1998Icar..131..317L McKay, C. P., Martin, S. C., Griffith, C. A., Keller, R. M. Temperature Lapse Rate and Methane in Titan's Troposphere 1997Icar..129..498M Griffith, C. A., et al. Thermal Infrared Imaging Spectroscopy of Shoemaker-Levy 9 Impact Sites: Spatial and Vertical Distributions of NH_3, C_2H_4, and 10-μm Dust Emission 1997Icar..128..275G Noll, K. S., et al. Carbon Monoxide in Jupiter after Comet Shoemaker-Levy 9 1997Icar..126..324N Bezard, B., Griffith, C. A., Kelly, D. M. Search for NH_3 in Jupiter's Stratosphere Ten Months after SL9's Collision 1997Icar..125..331B Bezard, B., Griffith, C. A., Kelly, D. M., Lacy, J. H., Greathouse, T., Orton, G. Icarus, Thermal Infrared Imaging Spectroscopy of Shoemaker-Levy 9 Impact Sites: Temperature and HCN Retrievals 1997Icar..125...94B Lissauer, J. J., et al. The epsilon Aurigae Secondary: A Hydrostatically Supported Disk 1996ApJ...465..371L Orton, G., et al. Collision of Comet Shoemaker-Levy 9 with Jupiter Observed by the NASA Infrared Telescope Facility 1995Sci...267.1277O Griffith, C. A., Zahnle, K. Influx of cometary volatiles to planetary moons: The atmospheres of 1000 possible Titans 1995JGR...10016907G Griffith, C. A. Evidence for surface heterogeneity on Titan 1993Natur.364..511G Griffith, C. A., et al. The tropospheric abundances of NH3 and PH3 in Jupiter's Great Red Spot, from Voyager IRIS observations 1992Icar...98...82G Toon, O. B., et al. A physical model of Titan's aerosols 1992Icar...95...24T Griffith, C. A., Owen, T., Wagener, R. Titan's surface and troposphere, investigated with ground-based, near-infrared observations 1991Icar...93..362G Griffith, C. A. Investigations of Titan's troposphere and surface and Jupiter's great red SPOT with infrared observations 1991PhDT.........9G Lissauer, J. J., Griffith, C. A. Erosion of circumstellar particle disks by interstellar dust 1989ApJ...340..468L