active shoreline of ontario lacus titan a morphological study of the lake and its surroundings of more than 400 filled lakes now identified on titan the first and largest reported in the southern latitudes is ontario lacus which is dark in both infrared and microwave here we describe recent observations including synthetic aperture radar sar images by cassini s radar instrument 2 cm and show morphological evidence for active material transport and erosion ontario lacus lies in a shallow depression with greater relief on the southwestern shore and a gently sloping possibly wave generated beach to the northeast the lake has a closed internal drainage system fed by earth like rivers deltas and alluvial fans evidence for active shoreline processes including the wave modified lakefront and deltaic deposition indicates that ontario is a dynamic feature undergoing typical terrestrial forms of littoral modification

alpine crustal shear zones and pre alpine basement terranes in the romanian carpathians and apuseni mountains the carpathian orocline formed by complex suturing of small continental fragments to the east european and moesian plate remnants of continental fragments belong to three pre alpine lithotectonic assemblages a greenstone granite association and two gneissic assem blages during alpine collision pieces of crust were repeatedly fragmented and welded to accommodate heterogeneous strain along the irregular east european plate boundary shallow structural levels of alpine tectonic discontinuities in which the locus of most intense strain migrated over time are now exposed as wide retrograde greenschist grade belts repeated mainly transpressive deformation resulted in early ductile fabrics being overprinted by local brittle shear strain igneous intrusion accompanied different phases of tectonic activity the age of shearing initiation is probably late paleozoic and the configuration of the zones and their alpine internal structures are consistent with the geometry of the carpathian arc

radar evidence for liquid surfaces on titan arecibo radar observations of titan at 13 centimeter wavelength indicate that most of the echo power is in a diffusely scattered component but that a small specular component is present for about 75 of the subearth locations observed these specular echoes have properties consistent with those expected for areas of liquid hydrocarbons knowledge of the areal extent and depth of any deposits of liquid hydrocarbons could strongly constrain the history of titan s atmosphere and surface

quantitative geomorphic modeling of martian bedrock shorelines 1 multiple researchers have identified shoreline features such as scarps on mars these features occur in both paleocrater lake basins and the northern hemispheric basin here we use a simple numerical model to investigate the viability of forming martian bedrock scarps via wind wave action we use the pierson moskowitz equation modified for martian gravity to generate wave fields under a variety of wind speeds and use those wave fields to drive a terrestrial bedrock shore erosion model modified for martian conditions our results indicate that even with conservative assumptions for the key parameters of wind speed slope and substrate it is difficult to form shoreline features of sufficient magnitude to be captured by spacecraft imaging under many combinations of reasonable initial conditions no shoreline features are formed in cases where shoreline features do develop the largest equilibrium scarp height is 5 m and the shorelines require nearly 2000 model years to form in light of these results and the difficulty of maintaining warm wet climates on mars it seems unlikely that the putative shoreline features identified in images are a result of water wave erosion and alternative hypotheses such as ice cover should be entertained

the growth of wind waves in titan s hydrocarbon seas abstract ocean wave growth on titan is considered the classic sverdrup munk theory for terrestrial wave growth is applied to titan and is compared with a simple energy balance model that exposes the effect of titan s environmental parameters air density gravity and fluid density these approaches are compared with the only previously published semi empirical model ghafoor n a l zarnecki j c challenor p srokosz m a 2000 j geophys res 105 12 077 12 091 hereafter g2k and allow the impact of various parameters such as atmospheric density to be transparently explored our model like g2k suggests fully developed significant wave heights on titan h s 0 2 u 2 where u is the windspeed si units in dimensionless terms this is rather close to h s 0 2 u 2 g a rule of thumb previously noted for terrestrial waves we find various datasets where the prefactor varies by 2 it is noted that liquid and air densities affect the growth rate of waves but not their fully developed height for 1 m s winds wave amplitude reaches 0 15 m 75 of fully developed with a fetch of only 1 km rather faster than predicted by g2k liquid viscosity has no major effect on gravity wave growth but does influence the threshold windspeed at which gravity capillary waves form in the first place the model is used to develop predicted ranges for wave height to guide the design of the titan mare explorer time a proposed discovery class mission to float a capsule on ligeia mare in 2023 for the expected maximum 1 m s winds a significant wave height of 0 2 m and wavelength of 4 m can be expected assuming that wave heights follow rayleigh statistics as they do on earth then given the wave period of 4 s individual waves of 0 6 m might be encountered over a 3 month period for predicted titan winds at kraken mare significant wave heights may reach 0 6 m in the peak of summer but do not exceed the tidal amplitude at its northern end consistent with the area around mayda insula being a tidal flat while elsewhere on kraken and ligeia and at ontario lacus shorelines may be wave or tidally dominated depending on the specific location

wind driven surface waves on titan the surface of titan represents the largest surface area in the solar system essentially unexplored although recent observations from hubble space telescope and ground based telescopes using adaptive optics have given perhaps the first low resolution indications of its nature whilst early models citing global oceans have been all but abandoned substantial bodies of liquid up to several hundred kilometers in extent are not precluded if such reservoirs do exist then in the presence of any surface winds it is expected that wind driven surface waves will be generated as on earth gravity remains the dominant controlling factor for such waves with surface tension and viscous effects only becoming significant below wavelengths of several centimeters empirical models used for terrestrial wind driven sea waves are adapted to investigate the properties of such waves on titan using predicted parameters for titan s liquids significant wave height peak period wavelength phase speed and wave steepness are predicted as a function of wind speed and liquid body extent it is found that waves will grow to a limiting height limiting wavelength and limiting period which are all inversely proportional to gravity the limiting significant wave height under the action of a 1 m s 1 titan wind over 50 km for example is predicted to be 0 2 m compared to 0 02 m on earth under similar circumstances more interesting however is the wave growth prior to this limiting value a useful visualization is that surface waves on a titan sea arising from surface wind speeds of 0 3 and 1 m s 1 will resemble in scale waves on earth generated by terrestrial winds of 1 and 3 m s 1 respectively these particular titan waves will have nearly 3 times the period and travel almost 3 times slower than the terrestrial waves however the wave parameters predicted in this work have potential surface mission implications for the european space agency s huygens probe which will land on titan in 2004 conversely their measurement by instruments on board huygens and nasa s cassini spacecraft could yield important planetological information

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

eddy variability and energetics from direct current measurements in the antarctic circumpolar current south of australia two year time series measurements of current velocity and temperature in the subantarctic front saf south of australia from 1993 to 1995 provide estimates of eddy fluxes of heat and momentum across the antarctic circumpolar current acc and further insight into the variability of the acc the saf was found to be an energetic meandering jet with vertically coherent fluctuations varying on a timescale of 20 days with typical amplitude 30 cm s21 at 1150 dbar a daily varying coordinate frame that follows the direction of flow allowed mesoscale variability of the saf to be isolated from variability due to meandering of the front and proved very successful for examining eddy fluxes vertically averaged cross stream eddy heat flux was 11 3 kw m 22 poleward and significantly different from zero at 95 for fluctuations in the 2 90 day band zonally integrated this eddy heat flux 50 9 pw is more than large enough to balance heat lost south of the polar front and is as large as cross saf fluxes found in drake passage cross stream eddy momentum fluxes were small not significantly different from zero and of indeterminate sign but tending to decelerate the mean flow a relationship between vertical motion and meander phase identified in the gulf stream was found to hold for the acc eddy kinetic energy levels were similar to those in drake passage and southeast of new zealand eddy potential energy was up to an order of magnitude larger than at other acc sites most likely because meandering of the front is more common here baroclinic conversion was found to be the dominant mechanism by which eddies grow south of australia typical eddy growth time is estimated to be 30 days approximately twice as fast as in drake passage consistent with eddy energy growing rapidly downstream

spatially resolved images of titan by means of adaptive optics abstract images of titan were acquired with the adonis adaptive optics system installed at the eso 3 6 m telescope in la silla chile the near infrared range from 1 2 5 m was covered in 1994 and 1995 in the methane atmospheric windows at 1 3 1 6 and 2 0 m with narrow band filters and cvf diffraction limited images were obtained 0 14 arcsec at 2 m thus allowing us to resolve the titan disk we have corrected the images for systematic effects removed center to limb variation and applied deconvolution processes to our data the contrast on the images is on the order of 30 both the leading and trailing hemispheres were observed the 2 m images presented in this paper show a broad bright feature on the surface of titan s leading hemisphere near 114 lcm which is in agreement with the hst images and with spectroscopy performed at these longitudes from the ground that show a higher geometric albedo on titan s leading side high quality flat fielding of our data has highlighted the presence of at least two main bright spots within the equatorial region the trailing hemisphere of titan s surface is not completely dark but shows brightness near the poles with some north to south asymmetry the northern latitudes are uniformly brighter than the lower equatorial and southern latitudes factor of about 2 our results bring new constraints on the models of the satellite s surface

energetics of the kuroshio extension at 35 n 152 e abstract a simplistic interpretation of eddy heat fluxes from a two year current meter mooring deployment in the kuroshio extension leads to the conclusion that the eddy field is denying at 152 e contradicting observations from the surface to 300 m that indicate the region to be one of steady or growing eddy energy thus a simplified version of the method used by hall to construct the velocity field of the current from the moored data has been used to examine the baroclinic and barotropic energy conversions in the cyclonic and anticyclonic portions of the current for both geographic and stream coordinates although the error bars are large in stream coordinates significant conversions of mean to eddy potential energy occur on the anticyclonic side of the current at both 350 and 625 dbar with smaller average conversions of eddy to mean energy over the cold portion barotropic conversions in this coordinate system are small but qualitatively the calculated reynolds stresses agree with previous obser

wind driven circulation in titan s seas circulation in titan s seas forced by wind is simulated by an ocean circulation model using surface wind data predicted by a global circulation model wind driven circulation is insignificant throughout much of the annual cycle but becomes significant from late spring to late summer when the wind stress becomes strong the large scale circulation in summer is predominantly southward near the sea surface and northward near the sea bottom the sea surface current can get as fast as 5 cms 1 in some areas titan s rotation affects the vertical structure of sea currents in the form of an ekman spiral if the wind is strong the maximum wind setup at the shores is of the same order of magnitude as the tidal range wind stirring may reduce thermal stratification in summer but may be unable to destroy stratification of methane rich liquids on top of ethane rich liquids that can result from imbalances between evaporation and precipitation

the tide in the seas of titan the surface temperature of titan1 is about 95 k between the melting point 90 6 k and the boiling point 118 k of methane at the total surface pressure of 1 6 bar voyager 1 ir observations1 2 suggest a methane abundance in the lower atmosphere 0 19 of saturation comparison with the mean h2o abundance in the earth s atmosphere suggests1 a ch4 saturation level 0 5 thus the volume mixing ratio of methane is probably about 6 and methane begins to condense out some 40 km above the surface it is therefore a natural speculation that methane exists in the liquid state on the surface of titan the atmospheric ch4 corresponds to a liquid layer 10 m deep but it is unlikely that the buffer for atmospheric methane would have a capacity equal only to that of the atmosphere itself on earth the quantity of water in the oceans is on average several times 104 the quantity of water vapour in the atmosphere thus if titan has oceans of liquid ch4 they are probably 100 m deep we argue here that if this ocean exists the present high eccentricity of titan requires its depth to be 400 m and that such an ocean can be detected by radar techniques

variability of the kuroshio extension jet recirculation gyre and mesoscale eddies on decadal time scales abstract twelve years of sea surface height ssh data from multiple satellite altimeters are used to investigate the low frequency changes and the interconnections of the kuroshio extension ke jet its southern recirculation gyre and their mesoscale eddy field the dominant signal is characterized by the steady weakening of the ke jet recirculation gyre from 1993 to 1996 followed by a gradual strengthening after 1997 during the weakening period of 1993 96 the ke path migrated southward in general and this path migration reversed in direction during the strengthening period of the ke jet and recirculation gyre after 1997 by hindcasting the ssh signals using linear vorticity dynamics it was found that weakening strengthening in the ke jet and recirculation gyre is consistent with westward propagation of negative positive ssh anomalies generating in the eastern north pacific and strengthening during their westward propagation when the ke jet and recirculation gyre were in a weak mode during 19

penetrometry of granular and moist planetary surface materials application to the huygens landing site on titan the huygens probe landed on the then unknown surface of titan in january 2005 a small protruding penetrometer part of the surface science package ssp was pushed into the surface material measuring the mechanical resistance of the ground as the probe impacted the landing site we present laboratory penetrometry into room temperature surface analogue materials using a replica penetrometer to investigate further the nature of titan s surface and examine the sensor s capabilities the results are then compared to the flight instrument s signature and suggest the titan surface substrate material consists of sand sized particles with a mean grain size 2 mm a possible thin 7 mm coating with mechanical properties similar to terrestrial snow may overlie this substrate although due to the limited data we are unable to detect any further layering or grading within the near surface material the unusual weakening with depth of the signature returned from titan has to date only been reproduced using a damp sand target that becomes progressively wetter with depth and supports the suggestion that the surface may consist of a damp and cohesive material with interstitial liquid contained between its grains comparison with terrestrial analogues highlights the unusual nature of the landing site material

surface roughness of titan s hydrocarbon seas abstract we derive fields of solutions for the surface properties roughness and permittivity of the liquid hydrocarbon bodies ligeia kraken and punga mare on titan by applying the radar statistical reconnaissance rsr technique to the cassini radar observations in altimeter mode during the northern early summer at the time of observation kraken and ligeia were confined within root mean square heights of 1 5 2 5 mm similar to wave heights of 6 10 mm correlation lengths of 45 115 mm and corresponding to effective slopes of 1 1 2 4 the latter extends up to 3 6 4 9 if the rougher punga is included the lower bound of those ranges has to be considered if the composition of the seas is methane dominant these are the first measurements to simultaneously constrain both the vertical and horizontal roughness parameters of titan s seas from the same observations our results are representative for the global properties of the sea scaled portion of the studied tracks and suggest that quiet surfaces are a dominant trend over the seas during the northern early summer fields of rougher textures if existent might develop mainly over local patches and or might not be sustained over significant periods of time

eddy mean flow interaction in the decadally modulating kuroshio extension system abstract satellite altimeter sea surface height ssh data of the past 16 years are used to investigate the decadal changes of the kuroshio extension ke system that oscillated between a stable and an unstable dynamic state during the stable state of 10 1992 06 1995 and 01 2002 12 2004 the ke jet was intense and had a northerly zonal mean path and a well defined southern recirculation gyre during the unstable state of 07 1995 12 2001 and 01 2005 present the ke jet had a reduced eastward transport and a more southerly flow path transitions between the two dynamic states are caused by the basin scale wind stress curl forcing in the eastern north pacific related to the pacific decadal oscillations pdos or the north pacific gyre oscillations npgos during the positive pdo or negative npgo phase the intensified aleutian low generates negative ssh anomalies in the eastern north pacific through ekman divergence as these wind induced negative ssh anomalies propagate to the west as baroclinic rossby waves they weaken the zonal ke jet and shift its path southward as its path is pushed southward 32 n the deep reaching ke jet has to ride over the shallow shatsky rise generating localized disturbances that lead to their subsequent development along the ke jet west of the shatsky rise the sequence opposite to that listed above occurs when the pdo npgo changes to its negative positive phase after the ke system transitions from a stable to unstable state the enhanced eddy interaction is found to strengthen both the southern recirculation gyre and quasi stationary meanders along the ke s upstream path this nonlinear eddy interaction is important in determining the amplitude of the observed decadal ke variability

surface of ligeia mare titan from cassini altimeter and radiometer analysis cassini radar observations of the surface of ligeia mare collected during the 23 may 2013 t91 cassini fly by show that it is extremely smooth likely to be mostly methane in composition and exhibits no surface wave activity the radar parameters were tuned for nadir looking geometry of liquid surfaces using experience from cassini s only comparable observation of ontario lacus on 21 december 2008 t49 and also include coincident radiometric observations radar echoes from both passes show very strong specular radar reflections and limit surface height variations to 1 mm rms the surface physical temperature at 80 n is 92 0 5 k if the sea is liquid hydrocarbon and the land is solid hydrocarbon essentially the same as cassini cirs measurements furthermore radiometry measurements over the surrounding terrain suggest dielectric constants from 2 2 2 4 arguing against significant surface water ice unless it is extremely porous

titan s surface revealed by hst imaging we present for the first time relative albedo maps of titan s surface the maps were made from images taken by the hubble space telescope s planetary camera 295 km per pixel through atmospheric windows at 940 and 1080 nm coverage at all longitudes and between 45 s and 60 n was obtained with 14 orbits from 4 18 october 1994 each image is characterized by haze with both limb effects brightening and a large north south contrast subtracting an averaged image from each frame removes haze effects and reveals surface features of 10 maximum contrast many features are clearly visible in multiple images and in both filters but the surface map is dominated by a large bright roughly rectangular feature centered at 110 w 10 s and elongated in an east west direction 4000 2500 km2 this feature and others indicate the diversity of titan s surface we consider the origin of the bright feature in an otherwise dark landscape and suggest that highland washing by methane rainfall is a likely mechanism

threshold of wave generation on titan s lakes and seas effect of viscosity and implications for cassini observations motivated by radar and near infrared data indicating that titan s polar lakes are extremely smooth we consider the conditions under which a lake surface will be ruffled by wind to form capillary waves we evaluate laboratory data on wind generation and derive without scaling for surface tension effects a threshold for pure methane ethane of 0 5 1 m s however we compute the physical properties of predicted titan lake compositions using the national institute for standards technology nist code and note that dissolved amounts of c3 and c4 compounds are likely to make titan lakes much more viscous than pure ethane or methane even without allowing for suspended particulates which would increase the viscosity further wind tunnel experiments show a strong dependence of capillary wave growth on liquid viscosity and this effect may explain the apparent absence so far of waves contrary to prior expectations that generation of gravity waves by wind should be easy on titan on the other hand we note that winds over titan lakes predicted with the titanwrf global circulation model indicate radar observations so far have in any case been when winds have been low 0 5 0 7 m s possibly below the wave generation threshold while peak winds during summer may reach 1 2 m s thus observations of titan s northern lakes during the coming years by the cassini solstice mission offer the highest probability of observing wind roughening of lake surfaces while observations of ontario lacus in the south will likely continue to show it to be flat and smooth

a comparison of surface eddy kinetic energy and reynolds stresses in the gulf stream and the kuroshio current systems from merged topex poseidon and ers 1 2 altimetric data analyses of surface eddy kinetic energy eke inferred from 5 years of merged topex poseidon and ers 1 2 altimetric data are presented in the gulf stream gs and the kuroshio ks current systems focusing on anisotropy and eke seasonal interannual and long term variations as well as reynolds stresses for both gs and ks a descriptive analysis of the eke field shows that it is anisotropic along the path of the currents and assesses the close relationship between the spatial distribution of eke high levels and bottom topography a striking ocean feature is found in the gs shaped as a zonal double blade structure in the eke field centered at 37 n 71 5 w that likely corresponds to a regular and permanent lateral displacement of the mean path of the current at this geographical location maps of eke seasonal means for years 1993 1996 and 1997 provide a detailed description of the surface variability meanders pinched off eddies etc and show strong interannual variations in the ks eke monthly mean changes in the ks reveal a well marked seasonal cycle during the first 3 years 1993 1995 with eke peaking in july august this is followed by a constant increase of its level from the beginning of year 1996 till the beginning of 1997 during this increase the zonal velocity variance u 2 is up to 30 higher than its meridional counterpart suggesting a zonal acceleration of the eastward flow eke seasonal changes are also found in the ks current 30 35 n 130 140 e and also show a regular annual cycle during the first 3 years which precedes by 2 months the eke seasonal cycle in the ks extension maximum in may june the maximum in eke in both regions precedes by 2 months the maximum surface transport found by qiu et al 1991 and zlotnicki 1991 occurring in july and late september respectively no such annual cycle is found in the gs region during the first 3 years year 1996 is anomalous in both current systems with mean eke level that increases by more than 20 compared to the other years also eke monthly mean changes in the ks reveal a well marked positive tendency in the eastern part of the current of more than 300 cm2 s 2 yr 1 and a negative tendency both in its eastern part and in the ks current this feature is absent from the gs at last eddy mean flow interaction is presented both the spatial averaging of turbulent quantities and the relative contribution of the different terms of the horizontal momentum fluxes are discussed a tentative explanation is given for the anomalously large u 2 at the end of 1996 in the ks extension

electromagnetic models and inversion techniques for titan s ontario lacus depth estimation from cassini radar data abstract since 2004 cassini radar operating at 13 8 ghz as a radiometer scatterometer altimeter and synthetic aperture radar sar provides a vast amount of data suggesting new scenarios for titan s morphology and evolution an important result was the detection of lakes constituted by liquid hydrocarbons thus supporting the hypothesis of a methane and ethane cycle similar to water cycle on earth in 2007 ontario lacus a 200 km 70 km lake was detected near the south pole to date ontario is the only large liquid area sensed by cassini radar in the southern hemisphere of titan in this work we analyze the sar data using two different electromagnetic modeling approaches to retrieve the optical thickness parameter of the liquid hydrocarbon layer a physically based model iem combined with a gravity capillary wave spectra and integrated into a bayesian statistical inversion is compared with a semi empirical model also based on a double layer description we consider the impact of the dielectric constant of the surface constituents as well as wind speed and wave motion scenarios on the retrieved optical thickness and by extension the lake depth and volume estimation wind speed can be constrained below 0 7 m s in good agreement with the forecasts of global circulation models on titan lake depths estimates depend on the hypotheses on wind speed and loss tangent of the liquid the average depth lake estimates obtained with the physically based approach range from 2 7 and 8 3 m with the 95 of the lake area not exceeding 30 m depth the semiempirical model results confirm this interval also considering the hypothesis of a low reflectivity lake bed this would imply lower depth with a significant part of the lake area not liquid filled at the present

tidal effects of disconnected hydrocarbon seas on titan thermodynamic and photochemical arguments1 4 suggest that titan the largest satellite of saturn has a deep ocean of liquid hydrocarbons at visible wavelengths titan s surface is obscured by a thick stratospheric haze but radar observations5 7 have revealed large regions of high surface reflectivity that are inconsistent with a global hydrocarbon ocean titan s surface has also been imaged at infrared wavelengths8 10 and the highest resolution data obtained by the hubble space telescope show clear variations in surface albedo and or topography10 the natural interpretation of these observations is that titan like the earth has continents and oceans but titan s high orbital eccentricity poses a problem for this interpretation as the effects of oceanic tidal friction would have circularized titan s orbit for most configurations of oceans and continents1 11 here we argue that a more realistic topography in which liquid hydrocarbons are confined to a number of disconnected seas or crater lakes may satisfy both the dynamical and observational constraints

annual and interannual variability in the kuroshio current system abstract individual seasonal 300 m temperature maps were constructed over the kuroshio current system from 130 e to 170 w for a 4 year period from summer 1976 through spring 1980 using transpac xbt data and jodc temperature depth data quasi stationary meanders in the kuroshic current system occurred at 137 c i e kuroshio meander at 144 e and 150 e i e lee wave meanders and near 160 e i e meander over the shatsky rise a composite of the paths of the kuroshio i e the 12 c isotherm from the individual seasonal maps and the total variance map finds nodes i e minima and anti nodes i e maxima of variability to have existed along the mean kuroshio path the anti nodes coincided with the location of the quasi stationary meanders the nodes in between zonal propagation of temperature anomalies accounted for 20 30 of the total interannual variance these temperature anomalies propagated eastward at 0 5 1 5 cm s 1 in the region 140 155 e and westward at 1 to 2 cm s 1 in the re

gulf stream path and thermocline structure near 74 w and 68 w the synoptic ocean prediction synop experiment had the goal of providing a physical understanding of energetic mesoscale eddy processes in the gulf stream in the synop inlet array off cape hatteras and in the central array near 68 w modred observations were collected from october 1987 through august 1990 the inlet array measured the surface path and bottom currents where the gulf stream leaves the continental margin to enter the deep water regime small amplitude propagating and growing meanders characterized the variability there the central array measured velocity and temperature as a proxy for density at four levels in the water column as well as the upper and deep level streamfunctions all with mesoscale resolution near 70 w the path envelope exhibited a relative node confined within a 40 km band 55 of the time near 68 w the path envelope was over 3 times as wide due to several elongated steep meander troughs and relatively steep meander crests the crests typically propagated downstream without much growth the troughs often stalled near 68 w steepened and persisted for one to several months two cases evolved into s shaped paths and subsequently formed rings even the time averaged fields showed a small trough in the mean path and thermocline structure whereas meanders of 20 to 60 day periods had similar spectral levels throughout 70 67 w meanders with long periods 85 day accounted for the local minimum in variance at 70 w bottom pressure and velocity observations revealed repeated periods of intense swirl speeds 0 30 m s 1 abyssal eddies the time averaged deep currents exhibited a mean cyclone centered 30 km offshore and downstream of the upper layer mean trough the cross stream slope of the thermocline steepened linearly with path curvature consistent with gradient wind balance structures are illustrated in the mapped fields consistent with baroclinic instability wherein troughs steepen and rings form

divergent eddy heat fluxes in the kuroshio extension at 144 148 e part ii spatiotemporal variability the kuroshio extension system study kess provided 16 months of observations to quantify divergent eddy heat flux dehf from a mesoscale resolving array of current and pressure equipped inverted echo sounders kess observations captured a regime shift from a stable to unstable state there is a distinct difference in the spatial structure of dehfs between the two regimes the stable regime had weak downgradient dehfs the unstable regime exhibited asymmetry along the mean path with strong downgradient dehfs upstream of a mean trough at 1478e the spatial structure of dehfs resulted from episodic mesoscale processes the first 6 months were during the stable regime in which fluxes were associated with eastward propagating 10 15 day upper meanders after 6 months the kuroshio extension underwent a regime shift from a stable to unstable state this regime shift corresponded with a red shift in mesoscale phenomena with the prevalence of 40 day deep externally generated eddies dehf amplitudes more than quadrupled during the unstable regime cold core ring ccr formation ccr jet interaction and coupling between 40 day deep eddies were responsible for asymmetry in downgradient fluxes in the mean maps not observed during the stable regime the kuroshio extension has prominent deep energy associated with externally generated eddies that interact with the jet to drive some of the biggest dehf events these eddies play an important role in the variability of the jet through eddy mean flow interactions the dehfs that result from vertical coupling act in accordance with baroclinic instability the interaction is not growth from an infinitesimal perturbation but from the start is a finite amplitude interaction

geological evolution of the tyras vallis paleolacustrine system mars 1 using the new high resolution stereo camera hrsc data and other martian data sets we reconstructed the hydrological history of an unnamed complex crater in the xanthe terra region the crater hosted a lacustrine basin fed by a dense and centripetal drainage system developed along its inner rim and by the tyras vallis channel where the tyras vallis opens into the crater a prominent delta like feature is visible characterized by a central terrace and two small longitudinal scarps this deposit has been used as sedimentary recorder of the crater lake history and allowed assessment of the overall hydrological evolution two major stands of the water level have been inferred at 700 and 550 m above the crater floor based on the correlation between the morphology and topography of the fan and the crater floor deposits our reconstruction reveals a complex sedimentary evolution of the fan which underwent deltaic and alluvial sedimentation as a result of the different lake water levels and tyras vallis supplies a dominant erosional evolution of the fan delta was determined by the interaction between the fluvial characteristics and basin wave regime wave height analysis and morphological comparison with terrestrial analogues support this hypothesis the lacustrine activity could be chronologically placed between the late noachian and the hesperian the climatic conditions could have allowed the recharge of the regional groundwater system by precipitation and episodic fluvial activity however also heating effects of cratering could have affected the system rejuvenating or accelerating the recharge of the local aquifer