the vertical profile of winds on titan the huygens probe landed on titan on 14 january this year and seven papers published in this issue record the encounter they describe a world that resembles a primitive earth complete with weather systems and geological activity the huygens on titan section opens with an overview of the descent and landing and a news and views piece tomasko et al describe the dry riverbed and drainage channels seen during huygens descent evidence that liquid methane falls as rain or erupts from cryovolcanoes periodically flooding the surface this paper includes the images used on the cover to the huygens section niemann et al measured the abundances of isotopes of argon nitrogen and carbon in the atmosphere and conclude that there is no evidence that titan s methane comes from biological activity fulchignoni et al obtained precise measurements of temperature and pressure from the upper atmosphere right down to the surface on the way down huygens recorded evidence for lightning zarnecki et al report that the probe landed on a relatively smooth surface of icy grains with the consistency of wet clay or sand isral et al report that the aerosols in titan s clouds have solid cores made from complex organic molecules containing carbon and nitrogen and bird et al found that on average titan s winds blow in the same direction as the moon rotates and that close to the surface these winds are very weak travelling at around walking speed one of titan s most intriguing attributes is its copious but featureless atmosphere the voyager 1 fly by and occultation in 1980 provided the first radial survey of titan s atmospheric pressure and temperature1 2 and evidence for the presence of strong zonal winds3 it was realized that the motion of an atmospheric probe could be used to study the winds which led to the inclusion of the doppler wind experiment4 on the huygens probe5 here we report a high resolution vertical profile of titan s winds with an estimated accuracy of better than 1 m s 1 the zonal winds were prograde during most of the atmospheric descent providing in situ confirmation of superrotation on titan a layer with surprisingly slow wind where the velocity decreased to near zero was detected at altitudes between 60 and 100 km generally weak winds 1 m s 1 were seen in the lowest 5 km of descent

the atmosphere of titan an analysis of the voyager 1 radio occultation measurements abstract two coherently related radio signals transmitted from voyager 1 at wavelengths of 13 cm s band and 3 6 cm x band were used to probe the equatorial atmosphere of titan the measurements were conducted during the occultation of the spacecraft by the satellite on november 12 1980 an analysis of the differential dispersive frequency measurements did not reveal any ionization layers in the upper atmosphere of titan the resolution was approximately 3 10 3 and 5 10 3 electrons cm 3 near the evening and morning terminators respectively abrupt signal changes observed at ingress and egress indicated a surface radius of 2575 0 0 5 km leading to a mean density of 1 881 0 002 g cm 3 for the satellite the nondispersive data were used to derive profiles in height of the gas refractivity and microwave absorption in titan s troposphere and stratosphere no absorption was detected the resolution was about 0 01 db km at the 13 cm wavelength the gas refractivity data which extend from the surface to about 200 km altitude were interpreted in two different ways in the first it is assumed that n 2 makes up essentially all of the atmosphere but with very small amounts of ch 4 and other hydrocarbons also present this approach yielded a temperature and pressure at the surface of 94 0 0 7 k and 1496 20 mbar respectively the tropopause which was detected near 42 km altitude had a temperature of 71 4 0 5 k and a pressure of about 130 mbar above the tropopause the temperature increased with height reaching 170 15 k near the 200 km level the maximum temperature lapse rate observed near the surface 1 38 0 10 k km corresponds to the adiabatic value expected for a dry n 2 atmosphere indicating that methane saturation did not occur in tbis region above the 3 5 km altitude level the lapse rate dropped abruptly to 0 9 0 1 k km and then decreased slowly with increasing altitude crossing zero at the tropopause for the n 2 atmospheric model the lapse rate transition at the 3 5 km level appears to mark the boundary between a convective region near the surface having the dry adiabatic lapse rate and a higher stable region in radiative equilibrium in the second interpretation of the refractivity data it is assumed instead that the 3 5 km altitude level corresponds to the bottom of a ch 4 cloud layer and that n 2 and ch 4 are perfectly mixed below this level these assumptions lead to an atmospheric model which below the clouds contains about 10 ch 4 by number density the temperature near the surface is about 95 k arguments concerning the temperature lapse rates computed from the radio measurements appear to favor models in which methane forms at most a limited haze layer high in the troposphere

titan s planetary boundary layer structure at the huygens landing site 1 huygens atmospheric structure instrument hasi for the first time performed an in situ measurement of the thermal structure in titan s atmosphere with a vertical resolution sufficient to analyze the planetary boundary layer pbl the vertical potential temperature profile reveals the presence of a weakly convective pbl with a surface layer thickness of 10 m and an outer layer with a depth of 300 m with a mean eddy diffusivity of only 7 4 10 3 m2 s 1 the turbulence in the pbl is weak the turbulent heat flux in the surface layer was upward but tiny 0 02 w m 2 indicating that the ground surface was marginally warmer than the air the surface heat flux is too small to cause a diurnal variation of the pbl except in the lowest few meters so the observed profile may be a nearly steady state feature within this season at the landing site in the surface layer the mean wind speed is likely to be less than 0 1 m s 1 given the tiny surface heat flux the buoyant production of turbulence is very weak the pbl structure reveals that the weather condition at the time and place of the huygens landing resembles a calm overcast day on earth but is clearly different from the pbl typical for the polar night

loess and life out of earth abstract loess is a homogeneous typically nonstratified porous friable slightly coherent often calcareous fine grained silty pale yellow wind blown aeolian and often by water reworked sediment that is distributed on continents world wide recent studies have highlighted the importance of biological loess crusts in trapping and transforming aeolian material into loess and also in prevention from wind and water erosion of deposited material some planets and satellites in our solar system are characterized by conditions comparable to those related to loess formation in terrestrial environments given the requirements for loess deposition on earth this study aims to ask the following questions 1 if loess like sediment formation is possible outside earth what are the mechanisms of sediment deposition and preservation 2 could the possible loess like sediments be stabilized through the activity of extraterrestrial equivalents of biological loess crusts found on earth as loess formation on earth is related to biological activity we propose a new direction in the search for extraterrestrial life evidence about extraterrestrial loess might indicate extraterrestrial life connected to loess formation on the basis of comparative analysis of some astrophysical conditions of seven celestial bodies we propose mars and titan and possibly venus and io to be assessed for evidence of loess deposition and the possible presence of related life forms and their biomarkers following recent advances in our understanding of terrestrial loess deposition we propose new indicators of extraterrestrial life research biomarkers in loess cyanobacterial and other microbial

simulations of titan s paleoclimate abstract we investigate the effects of varying saturn s orbit on the atmospheric circulation and surface methane distribution of titan using a new general circulation model of titan s atmosphere we simulate its climate under four characteristic configurations of orbital parameters that correspond to snapshots over the past 42 kyr capturing the amplitude range of long period cyclic variations in eccentricity and longitude of perihelion the model which covers pressures from the surface to 0 5 mbar reproduces the present day temperature profile and tropospheric superrotation in all four simulations the atmosphere efficiently transports methane poleward drying out the low and mid latitudes indicating that these regions have been desert like for at least tens of thousands of years though circulation patterns are not significantly different the amount of surface methane that builds up over either pole strongly depends on the insolation distribution in the present day methane builds up preferentially in the north in agreement with observations where summer is milder but longer the same is true to a lesser extent for the configuration 14 kyr ago while the south pole gains more methane in the case for 28 kyr ago and the system is almost symmetric 42 kyr ago this confirms the hypothesis that orbital forcing influences the distribution of surface liquids and that the current observed asymmetry could have been partially or fully reversed in the past the evolution of the orbital forcing implies that the surface reservoir is transported on timescales of 30 kyr in which case the asymmetry reverses with a period of 125 kyr otherwise the orbital forcing does not produce a net asymmetry over longer timescales and is not a likely mechanism for generating the observed dichotomy

provenance of turbidites in the ulleung tsushima back arc basin east sea sea of japan in the inactive ulleung back arc basin accumulation of turbidites was predominant over hemipelagic deposition since about pliocene time most of the late pleistocene turbidite layers deposited in the time interval between major volcanic eruptions at about 9 300 21 000 and 50 000 yrs b p contain heavy minerals that were derived mainly from the stable craton of the east korean peninsula during major eruptions however turbidites composed dominantly of unstable minerals originated mainly from the volcanic arc of northwestern honshu a few turbidite layers contain mineral assemblages common to both margins turbidites in the ulleung interplain gap were derived from the adjacent islands and banks modified journal abstract

the dynamics of titan s troposphere while the voyager mission could essentially not reveal the dynamics of titan s troposphere useful information was obtained by the cassini spacecraft and particularly by the huygens probe that landed on titan s surface this information can be interpreted by means of numerical models of atmospheric circulation the meridional circulation is likely to consist of a large hadley circulation asymmetric about the equator but is susceptible to disruption by turbulence in clouds the zonal wind in the troposphere is comparable to or even weaker than that in the terrestrial troposphere and contains zones of easterlies much in contrast to the super rotating stratosphere unique to titan is the transition from a geostrophic to cyclostrophic wind balance in the upper troposphere while earth like storm systems associated with baroclinic instability are absent saturn s gravitational tide introduces a planetary wave of wavenumber 2 and a periodical variation in the wind direction in the troposphere unlike on earth the wind over the equatorial surface is westerly the seasonal reversal in the hadley circulation sense and zonal wind direction is predicted to have a substantial influence on the formation of dunes as well as variation of titan s rotation rate and length of day

slope stability change from late pleistocene to holocene in the ulleung basin east sea japan sea abstract a wide variety of mass movement deposits prevail along the entire margin of ulleung basin overlain by a hemipelagic mud unit 1 2 m thick the boundary between the lower turbidite sequence and the upper hemipelagic mud on the basin plain is distinct and approximately coincides with the well known basin wide ash layer ulleung ash of early holocene age in the absence of significant terrigenous sediment input the lithologic change from the turbidite to hemipelagic mud may reflect physical effects of glacio marine eustatic sea level change sea level lowering during the glacial period may have generated excess pore pressure within the sediments caused by reducing hydrostatic confining pressure and facilitated triggering of the deep water slope failure by earthquakes storm waves may also have affected the uppermost slope area to induce small scale slope instabilities during the lowered sea level stand these glacial factors destabilizing the slope appear to have enhanced large scale slope failures during the late pleistocene in contrast the topmost hemipelagic mud attests to a stable slope phase associated with raised sea level in the holocene consistent with the infinite slope stability analyses calculations of the sedimentation rates based on c 14 dates of several ash layers indicate that the pre holocene turbidites on the basin plain had accumulated at an average rate of 40 cm 1000 years with a minimum recurrence interval of 50 years during the late pleistocene mass flux estimations between the slumps and turbidites suggest a predominance of the nondisintegrative mode of slope failures in the ulleung basin in each event of slope failure most of the failed mass rested on the slope as slide slump blocks and only its meager portions were deposited on the basin plain as turbidite layers

smoothness of titan s ontario lacus constraints from cassini radar specular reflection data 1 cassini radar altimetry data collected on the 49th flyby of titan 2008 december 21 over ontario lacus in titan s south polar region provides strong evidence for an extremely smooth surface with less than 3 mm rms surface height variation over the 100m wide fresnel zone histograms of the raw radar echoes imply a mirror like specular reflection of the transmitted signal such an echo is possible only if the surface is extremely flat relative to our 2 2 cm wavelength the 3 mm upper bound follows from analyzing the strength of the specular return which declines exponentially with increasing surface height variance in this experiment the strength of the echo was larger than expected severely saturating the receiver we developed a method to partially correct the echoes for the distortion incurred while the implied mm scale smoothness is not proof that the surface is liquid it is unlikely that a solid surface is so smooth

a tidal explanation for the titan haze layers abstract though titan is in synchronous rotation around saturn it experiences gravitational tides as a consequence of its eccentric orbit it is proposed that the vertical transport of aerosols by these tides produces the haze layers in titan s upper atmosphere analysis shows that the zonal winds in titan s superrotating atmosphere have a profound influence on which tidal components are effective in establishing the multiple detached haze layers if the huygens doppler winds are representative of the equatorial global superrotation then the westward propagating s 2 mode is the responsible tidal component even though its forcing is significantly weaker than that of the s 0 and eastward s 2 components the eastward s 2 tidal mode is eliminated by critical levels while the s 0 mode is viscously damped in the strong high altitude winds at polar latitudes however the gravest s 0 mode is the one most likely to produce layering it is also suggested that the atmospheric gravitational tides could be responsible for decelerating the superrotating atmosphere as seen in the huygens doppler wind velocity profile at about 80 km altitude

variations in titan s dune orientations as a result of orbital forcing abstract wind blown dunes are a record of the climatic history in titan s equatorial region through modeling of the climatic conditions associated with titan s historical orbital configurations arising from apsidal precessions of saturn s orbit we present evidence that the orientations of the dunes are influenced by orbital forcing analysis of 3 titan general circulation models gcms in conjunction with a sediment transport model provides the first direct intercomparison of results from different titan gcms we report variability in the dune orientations predicted for different orbital epochs of up to 70 although the response of the gcms to orbital forcing varies the orbital influence on the dune orientations is found to be significant across all models furthermore there is near agreement among the two models run with surface topography with 3 out of the 5 dune fields matching observation for the most recent orbital cycle through comparison with observations by cassini we find situations in which the observed dune orientations are in best agreement with those modeled for previous orbital configurations or combinations thereof representing a larger portion of the cycle we conclude that orbital forcing could be an important factor in governing the present day dune orientations observed on titan and should be considered when modeling dune evolution

diagnostics of titan s stratospheric dynamics using cassini cirs data and the 2 dimensional ipsl circulation model abstract the dynamics of titan s stratosphere is discussed in this study based on a comparison between observations by the cirs instrument on board the cassini spacecraft and results of the 2 dimensional circulation model developed at the institute pierre simon laplace available at http www lmd jussieu fr titandbase rannou p lebonnois s hourdin f luz d 2005 adv space res 36 2194 2198 the comparison aims at both evaluating the model s capabilities and interpreting the observations concerning 1 dynamical and thermal structure using temperature retrievals from cassini cirs and the vertical profile of zonal wind at the huygens landing site obtained by huygens dwe and 2 vertical and latitudinal profiles of stratospheric gases deduced from cassini cirs data the modeled thermal structure is similar to that inferred from observations cassini cirs and earth based observations however the upper stratosphere above 0 05 mbar is systematically too hot in the 2d cm and therefore the stratopause region is not well represented this bias may be related to the haze structure and to misrepresented radiative effects in this region such as the cooling effect of hydrogen cyanide hcn the 2d cm produces a strong atmospheric superrotation with zonal winds reaching 200 m s 1 at high winter latitudes between 200 and 300 km altitude 0 1 1 mbar the modeled zonal winds are in good agreement with retrieved wind fields from occultation observations cassini cirs and huygens dwe changes to the thermal structure are coupled to changes in the meridional circulation and polar vortex extension and therefore affect chemical distributions especially in winter polar regions when a higher altitude haze production source is used the resulting modeled meridional circulation is weaker and the vertical and horizontal mixing due to the polar vortex is less extended in latitude there is an overall good agreement between modeled chemical distributions and observations in equatorial regions the difference in observed vertical gradients of c 2 h 2 and hcn may be an indicator of the relative strength of circulation and chemical loss of hcn the negative vertical gradient of ethylene in the low stratosphere at 15 s cannot be modeled with simple 1 dimensional models where a strong photochemical sink in the middle stratosphere would be necessary it is explained here by dynamical advection from the winter pole towards the equator in the low stratosphere and by the fact that ethylene does not condense near the winter pole 80 n some compounds c 4 h 2 c 3 h 4 exhibit an interior minimum in the observed abundance vertical profiles whereas 2d cm profiles are well mixed all along the atmospheric column this minimum can be a diagnostic of the strength of the meridional circulation and of the spatial extension of the winter polar vortex where strong descending motions are present in the summer hemisphere observed stratospheric abundances are uniform in latitude whereas the model maintains a residual enrichment over the summer pole from the spring cell due to a secondary meridional overturning between 1 and 50 mbar at latitudes south of 40 50 s the strength as well as spatial and temporal extensions of this structure are a difficulty that may be linked to possible misrepresentation of horizontally mixing processes due to the restricted 2 dimensional nature of the model this restriction should also be kept in mind as a possible source of other discrepancies

titan s rotation reveals an internal ocean and changing zonal winds cassini radar observations of saturn9s moon titan over several years show that its rotational period is changing and is different from its orbital period the present day rotation period difference from synchronous spin leads to a shift of 0 36 per year in apparent longitude and is consistent with seasonal exchange of angular momentum between the surface and titan9s dense superrotating atmosphere but only if titan9s crust is decoupled from the core by an internal water ocean like that on europa

stratospheric global winds on titan at the time of huygens descent 1 measurements of stratospheric zonal winds on titan were made in preparation for and during the time of the descent of the huygens probe into titan s atmosphere on 14 january 2005 fully resolved emission lines from ethane near 11 7 m were measured on the east center and west positions on titan using the nasa gsfc heterodyne instrument for planetary wind and composition hipwac mounted on the national astronomical observatory of japan 8 2 m subaru telescope on mauna kea hawaii analysis of the doppler shifts of the emission line shapes yielded mean prograde gas velocity 60 65 m s at altitudes below 120 km 5 mbar this result is consistent with retrievals from the huygens doppler wind experiment and from other observations near this altitude range current spectral line shapes however differed significantly from those obtained in similar measurements on subaru in 2004 and on the nasa irtf in 1993 1996 which retrieved prograde zonal winds 190 90 m s at 230 km 0 4 mbar the cores of the emission lines which probe the high altitude region could not be fitted as before to retrieve wind directly using the accepted atmospheric model for titan they imply an approximately tenfold increase in ethane mole fraction 1 2 10 4 with strong wind shear above the stratopause providing a potential probe of the lower mesosphere and possible evidence of temporal and spatial variability results contribute to coordinated measurements of winds by various techniques providing information on the altitude distribution of wind velocity in titan s atmosphere from near the surface to the lower mesosphere

physical properties of titan s surface at the huygens landing site from the surface science package acoustic properties sensor api s abstract we present the results from the first sonar to be deployed outside of earth and the first active acoustic instrument on titan onboard the huygens probe and the implications of its data for the geomorphology and characteristics of the huygens landing site signals were recorded from 90 m downwards until impact with a maximum sensor footprint diameter at the ground of 39 2 m probe impact speed was measured to be 4 67 m s 1 derivation of terrain topography in a transect beneath the probe may indicate a ridge trough terrain with an amplitude of about 1 m and a wavelength of about 10 m although a flat surface is also consistent with the results modelling of the returned signal indicates that the surface acoustic properties at the landing site must be specular in nature which may have two possible not incompatible causes the surface may consist of sorted interlocking grains smooth on the centimetre scale which would imply either fluvial sorting or the infill of small particles interstitial to the larger particles similar to a terrestrial playa alternatively specularity may indicate the presence of methane as an interstitial liquid or as very small pools due to mission constraints tens of metres around the landing site were not well imaged by huygens cameras except for the narrow azimuth observed after impact the camera did not look straight down and was not in imaging mode during the last few hundred metres of descent thus the data presented are among the few direct observations of the landing site surroundings

the structure and dynamics of titan s middle atmosphere titan s middle atmosphere is characterized by cyclostrophic winds and strong seasonal modulation cassini cirs observations obtained in northern winter indicate that the stratosphere near 1mbar i

dunes on titan observed by cassini radar thousands of longitudinal dunes have recently been discovered by the titan radar mapper on the surface of titan these are found mainly within 30 of the equator in optically near infrared and radar dark regions indicating a strong proportion of organics and cover well over 5 of titan s surface their longitudinal duneform interactions with topography and correlation with other aeolian forms indicate a single dominant wind direction aligned with the dune axis plus lesser off axis or seasonally alternating winds global compilations of dune orientations reveal the mean wind direction is dominantly eastwards with regional and local variations where winds are diverted around topographically high features such as mountain blocks or broad landforms global winds may carry sediments from high latitude regions to equatorial regions where relatively drier conditions prevail and the particles are reworked into dunes perhaps on timescales of thousands to tens of thousands of years on titan adequate sediment supply sufficient wind and the absence of sediment carriage and trapping by fluids are the dominant factors in the presence of dunes

post depositional redistribution processes and their effects on middle rare earth element precipitation and the cerium anomaly in sediments in the south korea plateau east sea abstract we sampled two box core sediments from the slope of the eastern south korea plateau skp in the east sea sea of japan at water depths of 1400 and 1700 m two chemical fractions of extractable hydroxylamine acetic acid and residual rare earth elements rees together with al ca fe mg mn p s as mo and u were analyzed to assess the post depositional redistribution of rees extractable fe and mn are noticeably abundant in the oxic topmost sediment layer

observations of a stationary mid latitude cloud system on titan abstract we report the observation of a cloud system on titan that remained localized near 40 s latitude and 60 w longitude for at least 34 h ground based observations obtained with the sinfoni imaging spectrograph at the very large telescope over four consecutive nights recorded the lifetime and altitude of the unresolved cloud system concomitant measurements made by cassini vims over 3 h resolved changes in the altitude and opacity of individual regions within the system during this time clouds are measured from 13 to 37 km altitude with optical depths per pixel ranging from 0 13 to 7 short timescale rise times are consistent with previous measurements of the evolution of mid latitude clouds however the long timescale localization of the cloud structure is unexplained we speculate about the role of mesoscale circulation in relation to cloud formation

temporal variations of titan s middle atmospheric temperatures from 2004 to 2009 observed by cassini cirs we use five and one half years of limb and nadir viewing temperature mapping observations by the composite infrared radiometer spectrometer cirs on the cassini saturn orbiter taken between july 2004 and december 2009 ls from 293 to 4 northern mid winter to just after northern spring equinox to monitor temperature changes in the upper stratosphere and lower mesosphere of titan the largest changes are in the northern winter polar stratopause which has declined in temperature by over 20 k between 2005 and 2009 throughout the rest of the mid to upper stratosphere and lower mesosphere temperature changes are less than 5 k in the southern hemisphere temperatures in the middle stratosphere near 1 mbar increased by 1 2 k from 2004 through early 2007 then declined by 2 4 k throughout 2008 and 2009 with the changes being larger at more polar latitudes middle stratospheric temperatures at mid northern latitudes show a small 1 2 k increase from 2005 through 2009 at north polar latitudes within the polar vortex temperatures in the middle stratosphere show a 4 k increase during 2007 followed by a comparable decrease in temperatures in 2008 and into early 2009 the observed temperature changes in the north polar region are consistent with a weakening of the subsidence within the descending branch of the middle atmosphere meridional circulation

vertical atmospheric flow on titan as measured by the hasi instrument on board the huygens probe 1 on january 14 2005 the huygens probe descended on the surface of titan the largest moon of saturn and the only moon in the solar system with a substantial atmosphere after the deployment of the main parachute and the release of the heat shield at an altitude of about 150 km the local pressure and temperature were measured by hasi huygens atmospheric structure instrument all the way down to the surface these measurements have now been used to determine the vertical component of the atmospheric flow along the trajectory of the probe the average flow direction is rising below about 40 km and sinking above that with features that loosely match the strong shears in the horizontal wind profile obtained by radio telemetry the prevalence of sinking motion in the stratosphere is an unexpected result for the given latitude suggesting a layered atmosphere with a large thermally indirect cell wiggles superposed on the main upward flow are evidence of inertial instability characteristic of equatorial regions pointing to a latitudinal shear of zonal wind throughout the lower atmosphere

are tropical cyclones possible over titan s polar seas abstract while extratropical cyclones cannot be expected in titan s barotropic troposphere tropical cyclones which gain their energy from the latent heat of sea evaporation cannot be entirely dismissed over titan s polar hydrocarbon seas the most essential condition for the genesis of tropical cyclones on titan is a methane rich composition of the polar seas the most likely season for titan s hypothetical tropical cyclones is around the northern summer solstice when the sea surface gets warmer and the relative vorticity of the near surface air increases by seasonal convergence and equatorial wave activity a tropical cyclone would manifest itself as an anti clockwise swirling vortex right over one of the northern seas kraken mare ligeia mare punga mare and increase the surface wind over the seas by an order of magnitude on the other hand tropical cyclones are unlikely to emerge over titan s few tropical lakes for dynamic reasons such as negligible coriolis parameter and large vertical wind shear

titan s meridional wind profile and huygens orientation and swing inferred from the geometry of disr imaging abstract the altitude and zonal motion of the huygens probe descending through titan s atmosphere was determined early under the assumption of no meridional motion bird et al 2005 nature 438 800 802 by comparing images taken during the descent karkoschka et al karkoschka et al 2007 planet space sci 55 1895 1935 determined the meridional motion of huygens which was generally much smaller than its zonal motion here we present a comprehensive geometrical analysis of all images taken during the descent that is four times more accurate than the previous study the result is a meridional wind profile across titan s troposphere with northward winds by up to 0 4 m s with an average of 0 1 m s above 1 km altitude and southward winds below peaking at 0 9 m s near 0 4 km altitude the imaging data extend down to 0 22 km altitude although additional information came from the horizontal impact speed near 0 8 m s southward schroder et al 2012 planet space sci 73 327 340 there is a region between 5 and 8 km altitude with no significant meridional wind in the stratosphere the average meridional wind was 1 2 1 5 m s northward and zero meridional motion is possible down to 15 km altitude we present the difference between the zonal speeds of huygens and the wind that was ignored in previous publications and amounts to up to 7 m s we determined the three rotational angles of huygens for the times of each exposure that showed surface features during 26 exposures the swing speed of huygens was fast enough to smear images inferred swing speeds were up to 20 s during the calm phase of the descent consistent with up to 40 s swings reported before during the rough phase the improved geometric calibration of images allowed identification of many features also seen in cassini radar images this comparison yields the location of the huygens landingsite as 192 34 02 west and 10 47 0 02 south

cenozoic recent tectonics and uplift in the greater caucasus a perspective from azerbaijan the greater caucasus is europe s highest mountain belt and results from the inversion of the greater caucasus back arc type basin due to the collision of arabia and eurasia the orogenic processes that led to the present mountain chain started in the early cenozoic accelerated during the plio pleistocene and are still active as shown from present gps studies and earthquake distribution the greater caucasus is a doubly verging fold and thrust belt with a pro and a retro wedge actively propagating into the foreland sedimentary basin of the kura to the south and the terek to the north respectively based on tectonic geomorphology active and abandoned thrust fronts the mountain range can be subdivided into several zones with different uplift amounts and rates with very heterogeneous strain partitioning the central part of the mountain range defined by the main caucasus thrust to the south and backthrusts to the north forms a triangular shape zone showing the highest uplift and fastest rates and is due to thrusting over a steep tectonic ramp system at depth the meridional orogenic in front of the greater caucasus in azerbaijan lies at the foothills of the lesser caucasus to the south of the kura foreland basin

high resolution 2 7 khz acoustic and geometric characters of submarine creep deposits in the south korea plateau east sea a synthesis of high resolution chirp 2 7 khz seismic profiles in the south korea plateau reveals that large masses of wavy stratified sediment 60 90 m thick cover broad gently sloping 0 5 ridges in water depths of 1000 2000 m the wavy stratified sediment wss is characterized by wavy 0 2 5 km in wavelength and 15 m in relief continuous reflective layers with a basal deformed zone that overlies undeformed strong reflectors the wss exhibits systematic variation in wave dimensions and thickness of internal reflective layers with changes in slope gradient the troughs of the waves are commonly associated with internal growth faults and wave amplitude generally increases with subbottom depth on steep slopes around the ridges the wss masses are bounded downslope by slide and slump deposits including slightly translated or rotated wss blocks the acoustic and geometric characters and association with downslope slides and slumps on the steeper slopes suggest that the wss masses were most probably formed by slow creep movement before slope failure in the absence of significant sediment input to the south korea plateau the deep 1000 2000 m in water depth mass movements were probably triggered by earthquakes that have occurred frequently in this region some slightly displaced intact wss blocks in the associated slides and slumps downslope reflect a progressive evolution from submarine creep into slide and slump

titan s middle atmospheric temperatures and dynamics observed by the cassini composite infrared spectrometer the composite infrared radiometer spectrometer cirs instrument on the nasa cassini saturn orbiter has been acquiring thermal emission spectra from the atmosphere of titan since orbit insertion in 2004 observation sequences for measuring stratospheric temperatures have been obtained using both a nadir mapping mode and a limb viewing mode the limb observations give better vertical resolution and give information from higher altitudes while the nadir observations provide more complete longitude coverage because the scale height of titan s atmosphere is large enough so that emission from a grazing ray is influenced by horizontal temperature variations in the atmosphere we have developed a twodimensional temperature retrieval algorithm for reducing the limb spectra which solves simultaneously for meridional and vertical temperature variations the analyzed nadir mapping data have sampled nearly all longitudes at latitudes from about 90 st o 60 n providing temperatures between pressure levels of about 5 to 0 2 mbar the limb data covers latitudes between about 75 s and 85 n and yields temperatures between about 1 and 0 005 mbar at a small number of longitudes the retrieved temperatures are consistent with early results from nadir observations flasar f m and 44 colleagues 2005 science 308 975 978 between 0 5 and 5 mbar where both results are valid with the warmest temperatures at the equator and much stronger meridional temperature gradients in the northern winter hemisphere than in the southern at higher altitudes not probed by nadir viewing the limb data reveal that the stratopause is nearly 20 k warmer in the northern polar regions than at the equator and southern hemisphere and that the altitude of the stratopause shifts from 0 1 mbar 300 km near the equator to 0 01 mbar 400 km poleward of about 40 n when the gradient wind equation is used to construct a zonal mean wind the reversal in sign of the temperature leads to capping of the winter westerly flow the core of the resulting jet is about 190 m s 1 in magnitude spans between 30 n and 60 n and peaks near 0 1 mbar estimates of the radiative heating associated with the radiative disequilibrium lead to a meridional overturning timescale of about three earth years

sediment failure on the korea plateau slope east sea sea of japan abstract high resolution 3 5 khz seismic profiles from the slope of the korea plateau east sea sea of japan show an extensive area of slide deposits with prominent slump scars the sediment displaced from the steep slope 5 7 is less expansive than massive failure deposits on gradual slopes 1 2 seaward of a large trough thick wavy stratified sediments cover the gentle slope cyclic loading by earthquakes is the most probable triggering mechanism for the slope instability in this area the topmost 2 3 m sediment is chiefly composed of hemipelagic mud with interbeds of turbidites and volcanogenic material these sediments are highly plastic and shear resistant over 4 kpa at the surface in both stable and failed areas grain size decreases seaward from sandy mud on the shelf to silty clay on the lower slope total organic matter and water contents are closely associated with sediment texture both increasing with clay amounts from 5 10 and from 50 up to 200 respectively

the sand seas of titan cassini radar observations of longitudinal dunes the most recent cassini radar images of titan show widespread regions up to 1500 kilometers by 200 kilometers of near parallel radar dark linear features that appear to be seas of longitudinal dunes similar to those seen in the namib desert on earth the ku band 2 17 centimeter wavelength images show 100 meter ridges consistent with duneforms and reveal flow interactions with underlying hills the distribution and orientation of the dunes support a model of fluctuating surface winds of 0 5 meter per second resulting from the combination of an eastward flow with a variable tidal wind the existence of dunes also requires geological processes that create sand sized 100 to 300 micrometer particulates and a lack of persistent equatorial surface liquids to act as sand traps

winds on titan from ground based tracking of the huygens probe 1 large radio telescopes on earth tracked the radio signal transmitted by the huygens probe during its mission at titan frequency measurements were conducted as a part of the huygens doppler wind experiment dwe in order to derive the velocity of the probe in the direction to earth the dwe instrumentation on board huygens consisted of an ultrastable oscillator which maintained the high doppler stability required for a determination of probe horizontal motion during the atmospheric descent a vertical profile of the zonal wind velocity in titan s atmosphere was constructed from the doppler data under the plausible assumption of generally small meridional wind as validated by tracked images from the huygens descent imager spectral radiometer disr we report here on improved results based on data with higher temporal resolution than that presented in the preliminary analysis by bird et al 2005 corroborating the first in situ measurement of titan s atmospheric superrotation and a region of strong vertical shear reversal within the lower stratosphere we also present the first high resolution display and interpretation of the winds near the surface and planetary boundary layer

characterization of zonal winds in the stratosphere of titan with uves 2 observations coordinated with the huygens probe entry 1 the huygens probe has successfully entered titan s atmosphere and landed on its surface on 14 january 2005 with the aim of characterizing the zonal wind flow in titan s stratosphere close to the time of entry coordinated observations were carried out at the very large telescope on the nights of 7 12 14 and 15 january as in our previous investigation luz et al 2005 we used the uves instrument mounted on the kueyen ut2 telescope simultaneously achieving high spectral resolving power and high spatial resolution the field has been derotated in order to align the 0 3 arcsec aperture perpendicularly to titan s rotation axis in this configuration spatial information in the east west direction is preserved in a set of spectra in the direction perpendicular to dispersion we present measurements of zonal winds obtained with the technique of absolute accelerometry the observations were made in the wavelength range 4200 6200 a probing between 115 and 280 km with peak contributions at 200 and 170 km for the lower and upper parts of the domain we detect prograde zonal winds with lower limits 46 and 53 ms 1 at these altitudes these values are close to our previous measurements

mapping and interpretation of sinlap crater on titan using cassini vims and radar data 1 only a few impact craters have been unambiguously detected on titan by the cassini huygens mission among these sinlap is the only one that has been observed both by the radar and vims instruments this paper describes observations at centimeter and infrared wavelengths which provide complementary information about the composition topography and surface roughness several units appear in vims false color composites of band ratios in the sinlap area suggesting compositional heterogeneities a bright pixel possibly related to a central peak does not show significant spectral variations indicating either that the impact site was vertically homogeneous or that this area has been recovered by homogeneous deposits both vims ratio images and dielectric constant measurements suggest the presence of an area enriched in water ice around the main ejecta blanket since the ku band sar may see subsurface structures at the meter scale the difference between infrared and sar observations can be explained by the presence of a thin layer transparent to the radar an analogy with terrestrial craters in libya supports this interpretation finally a tentative model describes the geological history of this area prior during and after the impact it involves mainly the creation of ballistic ejecta and an expanding plume of vapor triggered by the impact followed by the redeposition of icy spherules recondensed from this vapor plume blown downwind subsequent evolution is then driven by erosional processes and aeolian deposition

wave constraints for titan s jingpo lacus and kraken mare from vims specular reflection lightcurves abstract stephan et al stephan k et al 2010 geophys res lett 37 7104 first saw the glint of sunlight specularly reflected off of titan s lakes we develop a quantitative model for analyzing the photometric lightcurve generated during a flyby in which the specularly reflected light flux depends on the fraction of the solar specular footprint that is covered by liquid we allow for surface waves that spread out the geographic specular intensity distribution applying the model to the vims t58 observations shows that the waves on jingpo lacus must have slopes of no greater than 0 15 two orders of magnitude flatter than waves on earth s oceans combining the model with theoretical estimates of the intensity of the specular reflection allows a tighter constraint on the waves 0 05 residual specular signal while the specular point lies on land implies that either the land is wetted the wave slope distribution is non gaussian or that 5 of the land off the southwest edge of jingpo lacus is covered in puddles another specular sequence off of kraken mare acquired during cassini s t59 flyby shows rapid flux changes that the static model cannot reproduce points just 1 min apart vary in flux by more than a factor of two the present dataset does not uniquely determine the mechanism causing these rapid changes we suggest that changing wind conditions kilometer wavelength waves or moving clouds could account for the variability future specular observations should be designed with a fast cadence at least 6 points per minute in order to differentiate between these hypotheses such new data will further constrain the nature of titan s lakes and their interactions with titan s atmosphere

zoned facies of mass flow deposits in the ulleung tsushima basin east sea sea of japan abstract high resolution 3 5 khz reflection profiles in the ulleung tsushima basin made it possible to classify the uppermost ca 50 m thick sedimentary deposits into rock fall slide slump debris flow deposit debrite and turbidite in terms of their acoustic properties these deposits generally occur in a distinctive zonal facies slides and slumps on the slope debrites on the base of slope and turbidites on the basin floor the rock fall deposits occur along the bases of the korea plateau and ulleung and dok islands the zonal distribution of mass flow deposits suggests that they most likely are derived from a line source at the shelfbreak shelf sediments prograde toward the shelfbreak on the slope sediment masses move downslope mainly accompanied by progressive slumping upslope individual slides and slumps on the slope probably develop into debris flows on the base of slope and successively into turbidity currents on the basin floor mass flow processes on the ulleung basin slope played an important role in transporting a large volume of terrigenous sediments into the deep basin

mountain torque and its influence on the atmospheric angular momentum on titan abstract the impact of titan s large scale topography and surface roughness on the atmospheric angular momentum budget is investigated by the cologne titan general circulation model that is run with and without topography constrained by cassini on seasonal timescales the angular momentum exchange is dominated by the friction torque which oscillates semi annually topography gives rise to a large diurnal and small seasonal mountain torque the diurnal mountain torque is caused by surface pressure variations associated with saturn s tide but has no net effect on the atmospheric angular momentum the seasonal mountain torque is mainly contributed by low latitude mountains that are hit by easterly surface winds the seasonal mountain torque causes a net transfer of angular momentum from the surface to the atmosphere which is counterbalanced by an opposite angular momentum transfer by the friction torque the atmospheric angular momentum is larger if topography is included

mapping the zonal structure of titan s northern polar vortex abstract saturn exhibits an obliquity of 26 7 such that the largest moon titan experiences seasonal variations including the formation of a polar vortex in the winter hemisphere titan s polar vortex is characterised by cold stratospheric temperatures due to the lack of insolation over the winter pole and an increase in trace gas abundance as a result of complex organic chemistry in the upper atmosphere combined with polar subsidence meridional variations in temperature and gas abundance across the vortex have previously been investigated but there has not yet been any in depth study of the zonal variations in the temperature or composition of the northern vortex here we present the first comprehensive two dimensional seasonal mapping of titan s northern winter vortex using 18 nadir mapping sequences observed by the composite infrared spectrometer cirs instrument on board cassini we investigate the evolution of the vortex over almost half a titan year from late winter through to mid summer ls 326 86 2007 2017 we find the stratospheric symmetry axis to be tilted from the solid body rotation axis by around 3 5 although our results for the azimuthal orientation of the tilt are inconclusive we find that the northern vortex appears to remain zonally uniform in both temperature and composition at all times a comparison with vortices observed on earth mars and venus shows that large scale wave mechanisms that are important on other terrestrial planets are not as significant in titan s atmosphere this allows the northern vortex to be more symmetrical and persist longer throughout the annual cycle compared to other terrestrial planets

slope stability and geotechnical properties of sediment of the southern margin of ulleung basin east sea sea of japan abstract ulleung basin a deep back arc basin in the sea of japan is tectonically active in relation to the subduction zone fronting the japanese islands cores and high resolution 3 5 khz seismic profiles were obtained from the southern margin of the basin based on the results of geotechnical tests pseudo static infinite slope stability analyses were carried out for the surficial slope sediments the shelf sediments are mostly massive medium to fine sand whereas the slope sediments are strongly bioturbated waterrich 170 200 water content and highly plastic 125 135 liquid limit 70 80 plasticity index silty clays these hemipelagic muds are slightly overconsolidated and highly compressible most geotechnical properties show distinctive downslope variations the amount of clay fraction water content and atterberg limits gradually increase downslope whereas calcium carbonate content decreases from 5 on the upper slope to nearly nil on the lower slope 1500 m total organic matter is somewhat consistent 8 14 throughout the slope shear strength displays no systematic variations downslope but gradually increases downcore in most places seismic data indicate that the slope surface is heavily moulded by mass movements a complex system of gullies and slump scars begins at the upper slope extending to the lower slope as slide slump and debris flow deposits the surficial sediments on the entire slope are quite stable statically under both undrained and drained conditions at present they appear to be least susceptible to slope failure by any probable earthquake loading associated with the regionally active tectonic regime