upper ocean response to typhoon choi wan as measured by the kuroshio extension observatory mooring 1 the kuroshio extension observatory keo is a highly instrumented moored reference station located at 32 3 n 144 5 e in the recirculation gyre south of the kuroshio extension on 19 september 2009 the eye of typhoon choi wan international designation 0914 passed 40 km to the southeast of the keo surface mooring hourly meteorological and physical oceanographic measurements together with 3 hourly air sea carbon dioxide observations telemetered from keo in near real time show the evolution of the upper ocean and its associated air sea fluxes during the passage of this storm and its aftermath during the approach of the storm the mixed layer freshened because of intense rainfall this was followed by a large outgassing of co2 rapid cooling and an increase in salinity although these changes in mixed layer properties imply substantial entrainment they were accompanied by upwelling and ultimately a temporary 20 m shoaling of the mixed layer this upwelling which was observed at all depths including the deepest sensor near 500 m was coincident with the onset of near inertial oscillations in the mixed layer currents after the typhoon passed inertial pumping caused 15 20 m amplitude vertical displacements throughout the top 500 m that continued for at least 6 days a large oceanic response was observed in this case even though the eye of choi wan passed to the right of keo resulting in winds rotating cyclonically with time in opposition to the anticyclonic rotating near inertial currents

numerical simulations of tropical cyclone ocean interaction with a high resolution coupled model the tropical cyclone ocean interaction was investigated using a high resolution tropical cyclone ocean coupled model the model design consisted of the noaa geophysical fluid dynamics laboratory tropical cyclone prediction model which was coupled with a multilayer primitive equation ocean model coupling between the hurricane and the ocean models was carried out by passing into the ocean model the wind stress heat and moisture fluxes computed in the hurricane model the new sea surface temperature sst calculated by the ocean model was then used in the tropical cyclone model a set of idealized numerical experiments were performed in which a tropical cyclone vortex was embedded in both easterly and westerly basic flows of 2 5 5 and 7 5 m s 1 with a fourth experiment run with no basic flow specified initially the profile of the tangential wind for hurricane gloria at 1200 utc 22 september 1985 was used as the initial condition of the tropical cyclone for each of the experiments the model ocean was initially horizontally homogenous and quiescent to clarify the impact of the ocean response to the hurricane s behavior analogous experiments were also carried out with the sst kept constant control cases the experiments indicated that the cooling of the sea surface induced by the tropical cyclone resulted in a significant impact on the ultimate storm intensity due to the reduction of total heat flux directed into the tropical cyclone above the regions of decreased sst the sea surface cooling produced by the tropical cyclones was found to be larger when the storms moved slower in the experiments run without an initial basic flow the maximum sst anomaly was about 5 6 c with a resulting difference in the minimum sea level pressure and maximum surface winds of 16 4 hpa and 7 m s 1 respectively in contrast in the experiments run with the 7 5 m s 1 basic flow the maximum sst anomalies ranged from about 2 6 to 3 0 c with a difference in the minimum sea level pressure and maximum surface winds of about 7 3 hpa and 2 7 m s 1 the tropical cyclone ocean coupling significantly influenced the storm track only for the case with no basic flow and the 2 5 m s 1 easterly flow in these cases the storm with the ocean interaction turned more to the north and east no basic flow or the north 2 5 m s 1 easterly flow of the experiments with constant sst in the first case the storm by 72 hours was located over 70 km to the east southeast of the control case a possible explanation for this track deviation is related to a systematic weakening of the mean tangential flow at all radii of the storm due to the interaction with the ocean and resulting alteration of the beta drift

rheological properties of water ice applications to satellites of the outer planets 1 abstract the icy moons of the outer solar system have not been quiescent bodies in part because many have a substantial water component and have experienced significant internal heating we can begin to understand the thermal evolution of the moons and the rate of viscous relaxation of surface topography because we now have good constraints on how ice in several of its polymorphic forms flows under deviatoric stress at planetary conditions details of laboratory derived flow laws for pure polycrystalline ice are reviewed in detail one of the more important questions at hand is the role of ice grain size grain size may be a dynamic quantity within the icy moons and it may or may not significantly affect rheology one recent beneficiary of revelations about grain size sensitive flow is the calculation of the rheological structure of europa s outer ice shell which may be no thicker than 20 km

impact of the configuration of stretching and ocean atmosphere coupling on tropical cyclone activity in the variable resolution gcm arpege this study starts by investigating the impact of the configuration of the variable resolution atmospheric grid on tropical cyclone tc activity the french atmospheric general circulation model arpege the grid of which is rotated and stretched over the north atlantic basin was used with prescribed sea surface temperatures the study clearly shows that changing the position of the stretching pole strongly modifies the representation of tc activity over the north atlantic basin a pole in the centre of the north atlantic basin provides the best representation of the tc activity for this region in a second part the variable resolution climate model arpege is coupled with the european oceanic global climate model nemo in order to study the impact of ocean atmosphere coupling on tc activity over the north atlantic basin two pre industrial runs a coupled simulation and a simulation forced by the sea surface temperatures from the coupled one are compared the results show that the coupled simulation is more active in the caribbean sea and the gulf of mexico while the forced simulation is more active over eastern florida and the eastern atlantic the difference in the distribution of tc activity is certainly linked with the location of tc genesis in the forced simulation tropical cyclogenesis is closer to the west african coast than in the coupled simulation moreover the difference in tc activity over the eastern atlantic seems to be related to two different mechanisms the difference in african easterly wave activity over the west of africa and the cooling produced in the coupled simulation by african easterly waves over the eastern atlantic finally the last part studies the impact of changing the frequency of ocean atmosphere coupling on atlantic tc activity increasing the frequency of coupling decreases the density of tc activity over the north atlantic basin however it does not modify the spatial distribution of the tc activity tc rainfalls are decreased by 8 in the high frequency coupled run

seismicity on tidally active solid surface worlds tidal interactions between planets or stars and the bodies that orbit them dissipate energy in their interiors the dissipated energy heats the interior and a fraction of that energy will be released as seismic energy here we formalize a model to describe the tidally driven seismic activity on planetary bodies based on tidal dissipation to constrain the parameters of our model we use the seismic activity of the moon driven by tidal dissipation from the earth moon interactions we then apply this model to predict the amount of seismic energy release and largest seismic events on other moons in our solar system and exoplanetary bodies we find that many moons in the solar system should be more seismically active than the earth s moon and many exoplanets should exhibit more seismic activity than the earth finally we examine how temporal spatial variations in tidal dissipation manifest as variations in the locations and timing of seismic events on these bodies

upper ocean and subsurface variability in the bay of bengal during cyclone roanu a synergistic view using in situ and satellite observations in this study the upper ocean and subsurface variability during the different phases of the cyclonic storm roanu along the western bay of bengal bob in may 2016 are investigated by using the moored buoys argos hf radar and satellite datasets in the proximity of the cyclone track the moored buoy observations recorded a decrease of sea surface temperature sst by 1 c all over the track whereas increase in salinity by 1 5 psu was detected along with the highest wind speed of 16 m s 1 pressure drop of 14 hpa and air temperature drop of 4 c the cooling at the cyclone centers from the satellite data indicated higher lower sst drops when translation speed of the cyclone was low high and took more less time to recover to its pre cyclone state in southern northern bob mostly higher sst drop was observed along the right side of the cyclone track interestingly the opposite phenomenon occurred before landfall where sst drop was higher on the left due to upwelling in the head bay as observed both from wave rider buoy wrb at digha and satellite sst the wrb near vizag showed the maximum increase in significant wave heights by 2 4 m during the passage of cyclone argos also captured cyclone induced drop in temperature due to upwelling and entrainment reasonably well in the southwestern bay significant upwelling was observed from the argos with drop in temperature and increase in salinity in the upper layers however a strong stratification was observed from argos in the northwestern bob due to lesser salinity and higher precipitation the currents from in situ as well as hf radar datasets measured the increase in current magnitude during the passage of roanu rotary spectral analysis showed strong inertial currents with frequency 2 1 days at bd11 location with higher amplitudes of the clockwise component during the cyclone period

liquid water and active resurfacing on europa voyager images of the jovian moon europa show a bright icy surface transected by a complex pattern of long linear fracture like markings with a slightly lower albedo1 very few impact craters are observed with sizes generally hi the range 10 20 km indicators of surface composition and texture include deep ir h2o absorption features2 uv absorption features characteristic of sulphur in a water matrix on the trailing hemisphere3 and a photometric function indicating much more homogeneous scattering than areas of equal albedo on ganymede and callisto4 europe s mean density is 3 03 g cm 3 indicating a primarily silicate composition however if the density of the silicates is the same as for io the h2o mass fraction would be 6 enough to form an outer layer of h2o 100 km thick if completely differentiated several models have been suggested for the evolution and present state of europa5 8 we present here arguments for recent resurfacing by h2o from a liquid layer based on new interpretations of recent spacecraft and earth based observations and revised theoretical calculations

light at deep sea hydrothermal vents ambient light spectral data were acquired at two deep sea hydrothermal vents with a temperature of 350 c the hole to hell site on the east pacific rise at 9 n and the snake pit site on the mid atlantic ridge measurements were made with a simple multi channel photometer which simultaneously detected light in four 100 nm wide bands over the wavelength range of 650 1050 nm most of the light detected is near infrared 750 1050 nm but there is a 19x greater photon flux than expected from thermal radiation alone at shorter wavelengths 650 750 nm at the hole to hell vent at snake pit more light in the 750 850 nm band was observed 10 cm above the orifice where the temperature was 50 100 c than at the 351 c vent opening these data suggest the presence of non thermal light sources in the vent environment some possible non thermal mechanisms are identified but further data will be required to resolve them

fracture penetration in planetary ice shells abstract the proposed past eruption of liquid water on europa and ongoing eruption of water vapor and ice on enceladus have led to discussion about the feasibility of cracking a planetary ice shell we use a boundary element method to model crack penetration in an ice shell subjected to tension and hydrostatic compression we consider the presence of a region at the base of the ice shell in which the far field extensional stresses vanish due to viscoelastic relaxation impeding the penetration of fractures towards a subsurface ocean the maximum extent of fracture penetration can be limited by hydrostatic pressure or by the presence of the unstressed basal layer depending on its thickness our results indicate that europa s ice shell is likely to be cracked under 1 3 mpa tension only if it is 2 5 km thick enceladus ice shell may be completely cracked if it is capable of supporting 1 3 mpa tension and is less than 25 km thick

a numerical study of the effect of island terrain on tropical cyclones abstract a triply nested movable mesh model was used to study the behavior of tropical cyclones encountering island mountain ranges the integration domain consisted of a 37 wide and 45 long channel with an innermost mesh resolution of 1 6 the storms used for this study were embedded in easterly flows of 5 and 10 m s 1 initially realistic distributions of island topography at 1 6 resolution were inserted into the model domain for the region of the caribbean including the islands of cuba hispaniola and puerto rico the island of taiwan and the region of luzon in the northern philippines it was found that the islands affected the basic flow as well as the wind field directly associated with the storm system the combination of these effects caused changes in the track and translational speed of the storm in particular in the case of the 5 m s 1 easterly flow the storm accelerated and veered to the north well before reaching taiwan for the other island distributions the northward deflecti

hurricane generated currents on the outer continental shelf 1 model formulation and verification a numerical model is developed to simulate currents generated by hurricanes on the outer continental shelf and slope emphasis is on the mixed layer response within a few hours of storm passage however some attention is given to the lower layer and shelf wave responses the model is based on a layered explicit finite difference formulation using the nonlinear primitive equations including conservation of heat the problem of topography intersecting the model layer is resolved by introducing artificial steps of the order of 100 m where the layer intersects the slope model comparisons are presented for three gulf of mexico hurricanes using a 0 2 grid for two of the storms the model reproduces better than 80 of the observed velocity variance with correlation coefficients of greater than 0 8 for the mixed layer discrepancies in the comparisons are traced to unresolved local topography and nonstorm forcing such as warm core rings further model simulations reveal that 1 substantial shelf waves were generated with phase speeds of 4 to 10 m s 1 2 the response is primarily baroclinic even in water as shallow as 200 m 3 an entrainment law which scales with the velocity difference between the mixed layer and upper thermocline yields markedly better comparisons than one which scales with the wind stress and 4 deviations from a straight line storm path can significantly alter the response

is there evidence for polar wander on europa abstract the orientations of the albedo lineaments bands and lineations on europa s surface have been compared in previous studies with the global stress fields set up by orbital eccentricity orbital recession and nonsynchronous rotation of these orbital and rotational effects nonsynchronous rotation combined with an offsetting of the tidal bulge comes closest to providing agreement between the stress field generated and the lineation orientations if the lineations trace tension or extension fractures mcewen 1986 nature321 49 51 however inferred minimum principal stress directions for a broad region of wedge shaped bands near the anti jove point cannot satisfactorily be accounted for by any of the stress fields above but are consistent with the stresses resulting from a rotation of europa s ice shell about an axis through the sub and anti jove points clockwise as seen from the anti jove hemisphere p m schenk and w b mckinnon 1989 icarus79 75 100 calculations by ojakangas and stevenson 1989 icarus81 220 241 of the thermal state of europa s ice shell indicate that spatial variations in the thickness of the shell may cause it to undergo such a reorientation we have investigated whether any reorientation of the shell about an axis through the sub and anti jove points produces a stress field consistent with the full global set of prominent lineations on europa s surface we find that no such reorientation provides a good fit between the lineations and plausible fracture orientations derived from the principal stress trajectories topographic ridges identified in a limited zone south of the anti jove point are roughly consistent with compression due to clockwise polar wander but the orientations of these ridges may be strongly biased by illumination direction within the limitations of the presently available imagery nonsynchronous rotation is still the most likely cause of the prominant fractures on europa s surface and the best specific albeit regionally limited tectonic evidence consistent with recent polar wander remains the wedge shaped bands

influence of large scale initial oceanic mixed layer depth on tropical cyclones abstract the influence of spatial variations of the oceanic mixed layer depth omld on tropical cyclones tcs is investigated using a coupled atmosphere ocean model the model consists of a version of the naval research laboratory limited area weather prediction model coupled to a simple 2 layer ocean model interactions between the tc and the ocean are represented by wind induced turbulent mixing in the upper ocean and latent and sensible heat fluxes across the air sea interface four numerical experiments are conducted with different spatial variations of the unperturbed omld representing idealizations of broad scale patterns observed in the north atlantic and north pacific oceans during the tropical cyclone season in each the coupled model is integrated for 96 h with an atmospheric vortex initially of tropical storm intensity embedded in an easterly mean flow of 5 m s 1 and located over an oceanic mixed layer that is locally 40 m deep the numerical solutions reveal that the rate of intensificatio

satellite measurements of sea surface cooling during hurricane gloria hurricanes and other strong storms can cause important decreases in sea surface temperature by means of vertical mixing within the upper ocean and by air sea heat exchange here we use satellite derived infrared images of the western north atlantic to study sea surface cooling caused by hurricane gloria 1985 significant regional variations in sea surface cooling are well correlated with hydrographic conditions the greatest cooling up to 5 c occurred in slope waters north of the gulf stream where the seasonal thermocline is shallowest and most compressed moderate cooling up to 3 c occurred in the open sargasso sea where the thermocline is deeper and more diffused little or no cooling occurred in shallow coastal waters bottom depth less than 20 m which were isothermal before the passage of hurricane gloria there is a pronounced right side asymmetry of sea surface cooling with stronger by a factor of 4 and more extensive by a factor of 3 cooling found on the right side of the hurricane track these qualitative results are consistent with the notion that vertical mixing within the upper ocean is the dominant sea surface cooling mechanism of hurricanes

expected seismicity and the seismic noise environment of europa seismic data will be a vital geophysical constraint on internal structure of europa if we land instruments on the surface quantifying expected seismic activity on europa both in terms of large recognizable signals and ambient background noise is important for understanding dynamics of the moon as well as interpretation of potential future data seismic energy sources will likely include cracking in the ice shell and turbulent motion in the oceans we define a range of models of seismic activity in europa s ice shell by assuming each model follows a gutenberg richter relationship with varying parameters a range of cumulative seismic moment release between 10 16 and 10 18 nm yr is defined by scaling tidal dissipation energy to tectonic events on the earth s moon random catalogs are generated and used to create synthetic continuous noise records through numerical wave propagation in thermodynamically self consistent models of the interior structure of europa spectral characteristics of the noise are calculated by determining probabilistic power spectral densities of the synthetic records while the range of seismicity models predicts noise levels that vary by 80 db we show that most noise estimates are below the self noise floor of high frequency geophones but may be recorded by more sensitive instruments the largest expected signals exceed background noise by 50 db noise records may allow for constraints on interior structure through autocorrelation models of seismic noise generated by pressure variations at the base of the ice shell due to turbulent motions in the subsurface ocean may also generate observable seismic noise

thickness constraints on the icy shells of the galilean satellites from a comparison of crater shapes a thin outer ice shell on jupiter s large moon europa would imply easy exchange between the surface and any organic or biotic material in its putative subsurface ocean1 2 3 4 the thickness of the outer ice shell is poorly constrained however with model dependent estimates ranging from a few kilometres5 6 to ten or more kilometres7 here i present measurements of depths of impact craters on europa ganymede and callisto that reveal two anomalous transitions in crater shape with diameter the first transition is probably related to temperature dependent ductility of the crust at shallow depths 7 8 km on europa the second transition is attributed to the influence of subsurface oceans on all three satellites3 8 9 which constrains europa s icy shell to be at least 19 km thick the icy lithospheres of ganymede and callisto are equally ice rich but europa s icy shell has a thermal structure about 0 25 0 5 times the thicknesses of ganymede s or callisto s shells depending on epoch the appearances of the craters on europa are inconsistent with thin ice shell models1 and indicate that exchange of oceanic and surface material could be difficult

the effect of relative flow on the asymmetric structure in the interior of hurricanes abstract asymmetric structure of tropical cyclones simulated by the geophysical fluid dynamics laboratory high resolution triply nested movable mesh hurricane model was analyzed emphasis was placed on the quasi steady component of the asymmetric structure in the region of the eyewall it was found that the asymmetry was primarily caused by the relative wind that is the flow entering and leaving the storm region relative to the moving storm a set of idealized numerical experiments was first performed both with a constant and a variable coriolis parameter f and the addition of basic flows that were either constant or sheared with height analysis was then made for one case of hurricane gilbert 1988 to demonstrate that the quasi steady asymmetric structure analyzed in the idealized studies could be identified in this real data case vorticity analysis in the variable f experiment indicated that quasi steady asymmetries resulted in the eyewall region through the effect of vorticity advection due to

ocean response to a hurricane part i observations abstract the response of the ocean to hurricanes was investigated using aircraft deployable expendable current profilers axcp the goals were to observe and separate the surface wave and surface mixed layer sml velocities under the storms and to map the across track and along track velocity and temperature response in the mixed layer and thermocline custom instrumentation was prepared including slower failing axcps and the axcp equipment was installed on noaa wp 3d aircraft research flights were made into two 1984 hurricanes norbert in the eastern pacific off baja california 19 n 109 w and josephine off the east coast of the united states 29 n 72 w thirty one probes were deployed in each hurricane and about half the axcps provided temperature and velocity profiles most velocity profiles exhibited strong surface wave contributions slablike velocities in the sml strong shears beneath the sml and only weak flows in the upper thermocline separation of the surface gravity wave velociti

ocean effects on tropical cyclone intensification and inner core asymmetries abstract the interaction between a tropical cyclone and the ocean is investigated using a minimal three dimensional tropical cyclone model coupled with a two layer ocean model two representations for entrainment into the ocean mixed layer are compared one based on the assumption that the velocity scale for entrainment is the surface friction velocity the other on the assumption that this scale is the magnitude of the mean velocity difference across the base of the mixed layer it is shown that the magnitude and distribution of the ocean cooling depends strongly on the method for representing entrainment velocity the method based on the surface friction velocity is more effective in reducing the heat flux from the ocean to the storm in the inner core region and leads to a greater reduction of the tropical cyclone intensity with ocean coupling the surface heat flux is reduced in the inner core mainly in the rear right quadrant relative to the track which is toward the northwest as a result the pot

comment on superplastic deformation of ice experimental observations by d l goldsby and d l kohlstedt knowledge of the rheological properties of ice at devia toric stresses lower than 0 1 mpa is of great interest whenmodeling the flow of glaciers and ice sheets in spite of thedifficulty of obtaining convincing results in the laboratory thereis now agreement on a flow law with a stress exponent lowerthan 2 mellor and testa 1969 duval 1973 alley 1992 duval and castelnau 1995 this result is also supported byborehole deformation measurements dahl jensen and gun destrup 1987 and bubbly ice densification modeling lipenkovet al 1997

implementation of a mesh movement scheme in a multiply nested ocean model and its application to air sea interaction studies a mesh movement scheme is implemented in a multiply nested primitive equation ocean model mesh movement can be specified or determined in the course of the model run so as to follow an evolving oceanic feature such as a wave front or propagating eddy or atmospheric forcing such as a tropical cyclone mass heat and momentum are conserved during the movement the mesh movement scheme is tested in idealized and realistic configurations of the model the idealized tests include simulations in which the moving meshes follow a propagating equatorial kelvin wave a dipole or move across an existing mesoscale eddy the tests demonstrate that the solutions in the fine mesh region of the nested meshes reproduce well the equivalent solutions from uniform fine mesh models the model is applied for simulations of the ocean response to tropical cyclones in which the moving meshes maintain high resolution near the cyclone center the solution in the inner meshes reproduces very well the uniform fine mesh simulation in particular the sea surface temperature it demonstrates that the moving meshes do not degrade the solution even with the application of strong winds and the generation of energetic surface currents and near inertial gravity waves the mesh movement scheme is also successfully applied for a real case simulation of the ocean response to typhoon roy 1988 in the western north pacific for this experiment the model is initialized using the fields from a general circulation model gcm multiyear spinup integration of the large scale circulation in the tropical pacific ocean the nested mesh solution shows no difficulty simulating the interaction of the storm induced currents with the existing background circulation

numerical simulation of tropical cyclone mora using a regional coupled ocean atmospheric model tropical storms ts are highly sensitive to the behavior of nearby oceans and the only way to improve their predictability is to include all the possible factors contributing to their genesis and motion the present study evaluates the response of air sea coupling on ts mora which occurred during the pre monsoon season of 2017 mora is simulated using a non hydrostatic regional atmospheric modeling system coupled to a regional ocean modeling system model the observations show a low level rossby wave in the atmosphere during the storm genesis there was also evidence of increased sea surface height simultaneously in the form of a downwelling kelvin wave at the west coast of the bay of bengal the present study emphasizes the relationship between near surface oceanic and atmospheric circulation patterns we have tried to elucidate the process with the help of dynamical equations and model solutions we also analyze the pivotal role of the atmospheric rossby wave in the formation of the coastal kelvin wave the kelvin wave seems to produce a warm pool required to form a low pressure system which further gave rise to the tropical storm mora the changes in the temperature and salinity profile within the ocean subsurface layers during storm passage are further used for inferences regarding the vertical structure of the upper ocean due to wind generated mixing the model analysis reveals that the ocean and atmospheric counterparts responsible for storm genesis are well recorded in the coupled model when compared to the observations it was found that air sea coupling in the model made it possible to realistically capture ocean and atmospheric responses

aquifer chemistry of thermal waters of the godavari valley india abstract the results of a chemical study of thermal waters from three hot springs two water discharges in a mine at 180 m depth and four wells drilled for exploration of coal and water resources in the godavari valley indicate 1 a deep flow path within the lower gondwanas upper carboniferous lower triassic for agnigundala thermal water which has been found to be in equilibrium with quartz montmorillonite and kaolinite at 150 c 2 medium depth circulation also through lower gondwana sedimentary rocks and equilibrium with quartz at 100 c for waters of buga manguru and bhuttayagudem and 3 circulation within sedimentary formations for the thermal waters of the pagdaru and bhimdole areas waters of the last areas show disequilibrium but are within the stability field of kaolinite the aquifer temperature is most likely to be about 156 c for the agnigundala around 100 c for the buga and not more than 100 c for the other systems

rate controlling processes in the creep of polar ice influence of grain boundary migration associated with recrystallization abstract information on the deformation modes and recrystallization processes in polar ice sheets was obtained thanks to the analysis of the ice structure along two deep ice cores from greenland and antarctica it is shown that the deformation of polar ice at low stresses is produced by intracrystalline slip accommodated by grain boundary migration gbm a deformation model based on an equilibrium between work hardening and recovery processes has been developed the decrease in dislocation density is due to both gbm associated with grain growth and the formation of boundaries by recrystallization the value of the dislocation density along the byrd and grip ice cores obtained thanks to the model is about 1 10 11 m 2 this value is in agreement with data from synchrotron x ray diffraction on samples taken along the core this deformation model can account for the deformation of polar ice at low stresses it is shown that the flow law with a stress exponent lower than 2 can be related to the efficiency of gbm as a recovery process

a coupled atmosphere wave ocean modeling system simulation of the intensity of an idealized tropical cyclone abstract a coupled atmosphere wave ocean modeling system cawoms based on the integration of atmosphere wave atmosphere ocean and wave current interaction processes is developed the component models consist of the weather research and forecasting wrf model the simulating waves nearshore swan model and the princeton ocean model pom the coupling between the model components is implemented by using the model coupling toolkit the cawoms takes into account various wave related effects including wave state and sea spray affected sea surface roughness sea spray heat fluxes and dissipative heating in atmosphere wave coupling it also considers oceanic effects such as the feedback of sea surface temperature sst cooling and the impact of sea surface current on wind stress in atmosphere ocean coupling in addition wave current interactions including radiation stress and wave induced bottom stress are also taken into account the cawoms is applied to the simulation of an idealized tropical cyclo

tropical cyclones in rotating radiative convective equilibrium with coupled sst abstracttropical cyclones are studied under the idealized framework of rotating radiative convective equilibrium achieved in a large doubly periodic f plane by coupling the column physics of a global atmospheric model to rotating hydrostatic dynamics unlike previous studies that prescribe uniform sea surface temperature sst over the domain ssts are now predicted by coupling the atmosphere to a simple slab ocean model with coupling ssts under the eyewall region of tropical cyclones tcs become cooler than the environment however the domain still fills up with multiple long lived tcs in all cases examined including at the limit of the very small depth of the slab the cooling of ssts under the eyewall increases as the depth of the slab ocean layer decreases but levels off at roughly 6 5 k as the depth approaches zero at the eyewall the storm interior is decoupled from the cooler surface and moist entropy is no longer well mixed along the angular momentum surface in the boundary layer tc intens

reply to comment by p duval and m montagnat on superplastic deformation of ice experimental observations 1 in a recent paper we reported the results of a detailed experimental investigation of the rheological properties of ice goldsby and kohlstedt 2001 one of the innovative aspects of our investigation was the use of fine grained samples that enabled us to explore deformation not only by grain size insensitive mechanisms involving grain matrix dislocation processes but also by grain size sensitive flow mechanisms involving grain boundary sliding gbs an exciting discovery in our research was an extensive creep regime in which gbs contributes substantially to the flow of ice most importantly this deformation regime in which basal slip is accommodated by gbs referred to in our paper as the superplastic flow regime governs the flow of ice over a wide range of temperature grain size and stress conditions found in glaciers ice sheets and icy planetary interiors 2 in their comment on our paper duval and montagnat 2002 repeat the objection that they had raised previously montagnat and duval 2000 concerning our conclusion that superplastic deformation controls the flow of glaciers and ice sheets they assert that gbs as a significant creep mechanism is not compatible with observations on the development of fabrics and microstructures in ice sheets special emphasis is placed instead on the role of grain boundary migration as a recovery process in glacier ice they then continue by arguing that basal slip accommodated by grain boundary migration gbm rather than by gbs is the dominant deformation mechanism in ice 3 in this reply we extend the results presented in detail by goldsby and kohlstedt 1997 and goldsby and kohlstedt 2001 to further demonstrate that gbs is a very important deformation process in natural ice bodies our reasoning is based on three points 1 the microstructures reported for samples from large natural ice bodies are remarkably similar to those observed in samples deformed in the laboratory in the superplastic flow regime 2 our constitutive equation for ice is in excellent agreement with the flow behavior determined from field measurements on glaciers and ice sheets 3 contrary to the assertion of montagnat and duval 2000 and duval and montagnat 2001 fabric development is fully compatible with deformation in the superplastic regime described in our paper in addition we note that while gbm associated with dynamic recrystallization is an important recovery mechanism in ice it is not a deformation mechanism and hence cannot accommodate basal slip

causes characteristics and consequences of convective diapirism on europa 1 we investigate the hypothesis that the 10 km diameter dome shaped features seen on europa s surface are caused by strongly temperature dependent convection in which upwellings form isolated diapirs or thermals we use the observed lower limit on dome diameter of 4 km to deduce that the conductive stagnant lid thickness must be 5 km such a lid thickness implies a minimum surface heat flux of 90 mwm 2 compatible with recent estimates of tidal heating we also use the mean observed dome diameter to infer a lower thermal boundary layer thickness of 1 km we find that the ice is probably deforming in the diffusion creep regime with a grain size in the range 0 02 0 06 mm the fraction of internal heating is 0 5 the ice viscosity 10 12 10 13 pa s and the crustal solidification rate 5km ma index terms 6218 planetology solar system objects jovian satellites 5430 planetology solid surface planets interiors 8147 5418 planetology solid surface planets heat flow 5455 planetology solid surface planets origin and evolution citation nimmo f and m manga causes characteristics and consequences of convective diapirism on europa geophys res lett 29 23 2109 doi 10 1029 2002gl015754 2002

fracturing and flow investigations on the formation of shallow water sills on europa abstract double ridge tectonic features appear prominently and ubiquitously across the surface of jupiter s icy moon europa previous studies have interpreted flanking fractures observed along some of the ridges as indicators of stress resulting from the ridge loading and flexing of the ice shell above a shallow water body here we investigate a shallow water sill emplacement process at a time when the shell is cooling and thickening and explore the conditions that would make such a system feasible on timescales of ridge formation results show that fracture initiation and transport of ocean water to shallow depths can realistically occur although horizontal fracturing and sill lifetimes prove challenging finite element models demonstrate that mechanical layering or a fractured shell do not provide enough stress change to promote horizontal fracturing but tidal forcing does result in a small amount of turn assuming it is possible for a shallow sill to form a sill would convect internally and conduct heat out quickly resulting in a short lifetime in comparison to an estimated flexure timeframe of 100 kyr suggested required for double ridge formation consideration of heat transfer and residence in the overlying ice however extends the flexure timeframe and multiple sill intrusions or replenishment with warm ocean water could prolong the effective sill lifetime though challenges still remain for sill formation at europa these analyses constrain the potential mechanisms for emplacement and indicate sills can act as viable options for supplying the heat needed for surface flexure further analyses and future missions to europa will help to increase our understanding of these enigmatic processes

evidence for separation across a gray band on europa abstract thynia linea a gray band on europa is found to be a 25 km wide and 900 km long region of lithospheric separation which has been infilled by relatively dark material roughly a dozen older features and the cuspate segments that form its outline appear to have been displaced across its width displacement azimuths indicate a best fit pole of opening near 79 s 200 w however displacement magnitude decreases toward either end of the gray band indicating that it is more akin to a tear in a nonrigid europan lithosphere opening was in response to nw se directed tensile stress in accord with the stress predictions of nonsynchronous rotation observations of thynia linea are consistent with a laterally mobile brittle lithosphere decoupled from ductile or liquid material below as previously suggested to account for opening of wedge shaped bands in europa s antijovian region lithospheric separation and contemporaneous emplacement of new material offers a possible volcano tectonic scenario for resurfacing europa if this process is ongoing resurfacing can be accomplished on a time scale consistent with the satellite s surface age if one gray band or zone of wedge shaped bands forms every 10 3 10 4 yr and becomes unrecognizable with age this would imply that features on europa brighten with age as through continuous deposition of frost onto the surface

geologic mapping of europa galileo data enable the major geological units structures and surface features to be identified on europa these include five primary units plains chaos band ridge and crater materials and their subunits along with various tectonic structures such as faults plains units are the most widespread ridged plains material spans a wide range of geological ages including the oldest recognizable features on europa and appears to represent a style of tectonic resurfacing rather than cryovolcanism smooth plains material typically embays other terrains and units possibly as a type of fluid emplacement and is among the youngest material units observed at global scales plains are typically mapped as undifferentiated plains material although in some areas differences can be discerned in the near infrared which might be related to differences in ice grain size chaos material is composed of plains and other preexisting materials that have been severely disrupted by inferred internal activity chaos is characterized by blocks of icy material set in a hummocky matrix band material is arrayed in linear curvilinear wedge shaped or cuspate zones with contrasting albedo and surface textures with respect to the surrounding terrain bilateral symmetry observed in some bands and the relationships with the surrounding units suggest that band material forms by the lithosphere fracturing spreading apart and infilling with material derived from the subsurface ridge material is mapped as a unit on local and some regional maps but shown with symbols at global scales ridge material includes single ridges doublet ridges and ridge complexes ridge materials are considered to represent tectonic processes possibly accompanied by the extrusion or intrusion of subsurface materials such as diapirs the tectonic processes might be related to tidal flexing of the icy lithosphere on diurnal or longer timescales crater materials include various interior smooth central rough inner and annular massif and exterior continuous ejecta subunits structural features and landforms are shown with conventional symbols type localities for the units are identified along with suggestions for portraying the features on geological maps including colors and letter abbreviations for material units implementing these suggestions by the planetary mapping community would facilitate comparisons of maps for different parts of europa and contribute to an eventual global synthesis of its complex geology on the basis of initial mapping results a stratigraphic sequence is suggested in which ridged plains form the oldest unit on europa followed by development of band material and individual ridges band materials tend to be somewhat older than ridges but in many areas the two units formed simultaneously similarly the formation of most chaos follows the development of ridged plains although chaos is among the youngest materials on europa some chaos units might have formed contemporaneously with ridged plains smooth plains generally embay all other units and are late stage in the evolution of the surface c 1 craters are superposed on ridged plains but are crosscut by other materials including bands and ridges most c2 craters postdate all other units but a few c2 craters are cut by ridge material c3 craters constitute the youngest recognizable material on europa

europa s small impactor flux and seismic detection predictions abstract europa is an attractive target for future lander missions due to its dynamic surface and potentially habitable sub surface environment seismology has the potential to provide powerful new constraints on the internal structure using natural sources such as faults or meteorite impacts here we predict how many meteorite impacts are likely to be detected using a single seismic station on europa to inform future mission planning efforts to this end we derive 1 the current small impactor flux on europa from jupiter impact rate observations and models 2 a crater diameter versus impactor energy scaling relation for icy moons by merging previous experiments and simulations and 3 scaling relations for seismic signal amplitudes as a function of distance from the impact site for a given crater size based on analogue explosive data obtained on earth s ice sheets finally seismic amplitudes are compared to predicted noise levels and seismometer performance to determine detection rates we predict detection of 0 002 20 small local impacts per year based on p waves travelling directly through the ice crust larger regional and global scale impact events detected through mantle refracted waves are predicted to be extremely rare 10 8 1 detections per year so are unlikely to be detected by a short duration mission estimated ranges include uncertainties from internal seismic attenuation impactor flux and seismic amplitude scaling internal attenuation is the most significant unknown and produces extreme uncertainties in the mantle refracted p wave amplitudes our nominal best guess attenuation model predicts 0 002 5 local direct p detections and 6 10 6 0 2 mantle refracted detections per year given that a plausible europa landed mission will only last around 30 days we conclude that impacts should not be relied upon for a seismic exploration of europa for future seismic exploration faulting due to stresses in the rigid outer ice shell is likely to be a much more viable mechanism for probing europa s interior

aquifer chemistry of the puga and chumatang high temperature geothermal systems in india abstract results of a chemical study of the fluids from drill holes and hot springs of puga and chumatang areas in the northwestern part of the himalaya are presented and discussed in this paper the thermal waters of puga and chumatang are of na hco 3 cl and na hco 3 types respectively a comparison between these waters their chemical classification and activity studies suggest a flow path within a quartzitic schistose basement containing quartz k feldspar and illite and in clayey terrains containing montmorillonite and illite the chemistry of thermal waters also indicate their association with magmatic activity the chemical geothermometers indicate the possible existence of a geothermal reservoir at puga with temperature 250 c the chumatang area has a comparatively cooler reservoir with a temperature of 150 180 c

evaluation of reservoir temperatures and local utilization of geothermal waters of the konkan coast india abstract geochemical studies on fifteen geothermal manifestations 38 70 c from the konkan coast geothermal province of india have been used to evaluate the reservoir temperatures activity studies of the minerals and the waters present in the reservoirs suggest that the thermal waters are in equilibrium with montmorillonite kaolinite and quartz at about 100 c reservoir temperatures of these geothermal systems as estimated by geochemical thermometers are 88 to 128 c and thus too low for economic electricity production

satellite derived ocean thermal structure for the north atlantic hurricane season abstractthis paper describes a new model method called satellite derived north atlantic profiles snap that seeks to provide a high resolution near real time ocean thermal field to aid tropical cyclone tc forecasting using about 139 000 observed temperature profiles a spatially dependent regression model is developed for the north atlantic ocean during hurricane season a new step introduced in this work is that the daily mixed layer depth is derived from the output of a one dimensional price weller pinkel ocean mixed layer model with time dependent surface forcing the accuracy of snap is assessed by comparison to 19 076 independent argo profiles from the hurricane seasons of 2011 and 2013 the rms differences of the snap estimated isotherm depths are found to be 10 25 m for upper thermocline isotherms 29 19 c 35 55 m for middle isotherms 18 7 c and 60 100 m for lower isotherms 6 4 c the primary error sources include uncertainty of sea surface height anomaly ssha high frequency fluc

seismic detectability of a subsurface ocean on europa abstract a seismometer placed on jupiter s moon europa can use passive monitoring to determine the presence or absence of a possible liquid water ocean beneath europa s surface ice and estimates of the thickness of the ice shell itself using probable seismic velocities for europa s ice it is demonstrated that surface waves propagating in the frequency band of 0 1 to 0 5 hz wave periods of 2 to 10 s can discriminate ice shells varying from 5 to 20 km in thickness miniature light weight seismometers with appropriate sensitivities are available

diagnosing forecast errors in tropical cyclone motion abstractthis paper reports on the development of a diagnostic approach that can be used to examine the sources of numerical model forecast error that contribute to degraded tropical cyclone tc motion forecasts tropical cyclone motion forecasts depend upon skillful prediction of the environment wind field and by extension the synoptic scale weather systems nearby the tc while previous research suggests that the deep layer mean dlm steering flow typically approximates the actual tc motion it is shown that the motion of even mature tcs can depart from the dlm steering flow an optimal environmental steering flow is defined which varies the vertical extent of the steering layer and the radius over which tc vorticity and divergence are removed errors in predicted tc motion are quantified using a diagnostic equation that accounts for not only differences in the synoptic scale flow but also differences in the depth and radius used to define the steering flow differences in the latter two parameters a

a numerical study of the effects of land proximity and changes in sea surface temperature on hurricane tracks a three layer shallow water model with a convection parametrization is used to study the track deflections of slow moving hurricanes on a plane as they approach straight coastlines of different orientations with respect to north or as they cross to a cooler or warmer body of water in the landfall experiments the land surface is level and is characterized by an abrupt increase of the drag coefficient and zero evaporation the tracks of a 72 h integration on a plane are compared with an ocean control experiment it is found that the divergent flow in the boundary layer in regions of offshore winds is responsible for the observed track deflections in this region middle layer air descends into the boundary layer and increases the positive potential vorticity anomaly in the middle layer in the case of land conditions to the west of the vortex the maximum potential vorticity anomaly extends less to the north of the vortex centre and results in a more southerly track than in the ocean control case if land conditions are specified in the north the positive potential vorticityasymmetry maximum extends more to the north west and results in a northward deflection of the track on the other hand land conditions to the north west of the initial vortex centre do not significantly change the location of the asymmetry and therefore the track deflection is small the magnitude of the track deflections as well as the drift speed increases when the roughness of the land is increased it is significant that track deflections commence about 20 h before landfall reaching a value of about 150 km at the time of landfall compared with landfalling hurricanes track deflections of model hurricanes which drift into a region of different sea surface temperature sst are smaller and are a result of intensity changes of the vortex circulation the maximum wind speed at the time of landfall increases if a region of higher sst is located adjacent to the coastline

prediction experiments of hurricane gloria 1985 using a multiply nested movable mesh model abstract the prediction capability of the gfdl triply nested movable mesh model with finest grid resolution of degree was investigated using several case studies of hurricane gloria 1985 during the period that the storm approached and moved up the east coast of the united states the initial conditions for these experiments were interpolated from an nmc t80 global analysis at 0000 utc 25 september and 1200 utc 22 september the integrations starting from 0000 utc 25 september were run 72 h while those starting on 1200 utc 22 september were run 132 h the lateral boundary conditions were obtained from either an integration of the nmc t80 forecast model or the t80 global analysis or were fixed to the initial value the model s predicted track of gloria for each integration was compared against the best track determined by the national hurricane center nhc for the case starting from 0000 utc 25 september using a forecasted boundary condition the model successfully forecasted significant acceler

europa tidal heating of upwelling thermal plumes and the origin of lenticulae and chaos melting europa we show that tidal energy can be preferentially focused in rising plumes for viscosities in agreement with laboratory experiments when the plume cores reach the base of the outer cold brittle layer they spread laterally causing shallow melting disruption and formation of terrain similar to lenticulae and chaos we show that this mechanism can readily explain the major characteristics of chaos and lenticulae even if the average outer solid ice layer thickness is larger than 20 km

current and density observations across the wake of hurricane gay abstract ctd and acoustic doppler current profiler data are analyzed for the response of the upper ocean to rapidly moving hurricane gay currents were observed within about two days of the hurricane passage and were dominated by a blue shifted inertial oscillation confined largely to the mixed layer the amplitude of the current was strongly asymmetric about the track with the largest amplitude 1 m s 1 about 80 km to the right of the track there was also an asymmetry of the mixed layer depth and temperature with deeper and cooler values to the right of the track the gradient richardson number was found to have low values in some places less than 1 4 in a layer from 10 to 30 m thick below the base of the surface mixed layer this suggests that shear flow instability played an important role in the vertical mixing that occurred within the mixed layer and upper thermocline

influence of coast line on upper ocean s response to the tropical cyclone 1 a 3 dimensional princeton ocean model has been configured for the east coast of india which is applied to study the transformation of the upper ocean s response in the near coastal waters to the 1999 orissa super cyclone in the bay of bengal at the time of landfall it is well known that the sea surface temperature sst cooling is more towards the right of the storm track because of the dominant wind stress forcing there consequently the model simulated ssts showed more cooling to the right of the storm track however it is found to be true only in the open ocean the coastal dynamics transformed the scenario as the cyclone translated over the coastal waters owing to the impedance of the coast line to the circulation and shifted the region of maximum surface cooling to the left of the cyclone track the satellite imageries during the period also endorsed the model simulations

estimate of ocean mixed layer deepening after a typhoon passage over the south china sea by using satellite data abstractthe ocean responses to typhoon cimaron which influenced the south china sea scs from 1 to 8 november 2006 are analyzed based on satellite observed sea surface temperature sst and climatological temperature profiles in the scs mixed layer deepening an important parameter characterizing turbulent mixing and upwelling driven by strong typhoon winds is derived corresponding to the sst drop of 4 4 c on 3 november 2006 the mixed layer deepened by 104 5 m relative to the undisturbed depth of 43 2 m which is consistent with a simulation result from a mixed layer model furthermore baroclinic geostrophic velocity and vorticity are calculated from the surface temperature gradient caused by the typhoon the negative vorticity associated with the typhoon cooling indicated an anticyclonic baroclinic circulation strongest at the base of the mixed layer and at the depth of 50 m the geostrophic speed reached as high as 0 2 m s 1 typhoon cimaron proceeded slowly 1 7 m s 1 when it was making a s

geochemical and isotope hydrological characterisation of geothermal resources at godavari valley india thermal waters at the godavari valley geothermal field are located in the khammam district of the telangana state india the study area consists of several thermal water manifestations having temperature in the range 36 76 c scattered over an area of 35 km2 the thermal waters are na hco3 type with moderate silica and tds concentrations in the present study detailed geochemical major and trace elements and isotope hydrological investigations are carried out to understand the hydrogeochemical evolution of these thermal waters correlation analysis and principal component analysis pca are performed to classify the thermal waters and to identify the different geochemical processes controlling the thermal water geochemistry from correlation matrix it is seen that tds and ec of the thermal springs are mainly controlled by hco3 and na ions in pca thermal waters are grouped into two distinct clusters one cluster represents thermal waters from deeper aquifer and other one from shallow aquifer lithium and boron concentrations are found to be similar followed by rubidium and caesium concentrations different ternary plots reveal rock water interaction to be the dominant mechanism for controlling trace element concentrations stable isotopes 18o 2h data indicate the meteoric origin of the thermal waters with no appreciable oxygen 18 shift the low tritium values of the samples originating from deeper aquifer reveal the long residence time 50 years of the recharging waters xrd results of the drill core samples show that quartz constitutes the major mineral phase whereas kaolinite dolomite microcline calcite mica etc are present as minor constituents quartz geothermometer suggests a reservoir temperature of 100 20 c which is in good agreement with the values obtained from k mg and mg corrected k mg ca geothermometers

influence of the size of supertyphoon megi 2010 on sst cooling abstractsupertyphoon megi 2010 left behind two very contrasting sst cold wake cooling patterns between the philippine sea 1 5 c and the south china sea 7 c based on various radii of radial winds we found that the size of megi doubles over the south china sea when it curving northwards on average the radius of maximum wind rmw increased from 18 8 km over the philippine sea to 43 1 km over the south china sea the radius of 64 kt typhoon force wind r64 increased from 52 6 km to 119 7 km the radius of 50 kt damaging force wind r50 increased from 91 8 km to 210 km and the radius of 34 kt gale force wind r34 increased from 162 3 km to 358 5 km to investigate the typhoon size effect we conduct a series of numerical experiments on megi induced sst cooling by keeping other factors unchanged i e typhoon translation speed and ocean subsurface thermal structure the results show that if it were not for megi s size increase over the south china sea the during megi sst cooling magnitude woul

thickness of a europan ice shell from impact crater simulations several impact craters on jupiter s satellite europa exhibit central peaks on the terrestrial planets central peaks consist of fractured but competent rock uplifted during cratering therefore the observation of central peaks on europa indicates that an ice layer must be sufficiently thick that the impact events did not completely penetrate it we conducted numerical simulations of vapor and melt production during cratering of water ice layers overlying liquid water to estimate the thickness of europa s icy crust because impacts disrupt material well beyond the zone of partial melting our simulations put a lower limit on ice thickness at the locations and times of impact we conclude that the ice must be more than 3 to 4 kilometers thick

bottom up versus top down solidification of the cores of small solar system bodies constraints on paradoxical cores abstract the slopes of the adiabatic gradient of liquid iron and iron alloys are calculated at high pressure conditions and compared to liquidi slopes the controversial thermal expansion of liquid iron results in uncertainties in the pressure conditions and compositional range over which adiabats are steeper than the liquidi and hence over the conditions at which planetary cores would be expected to begin crystallization from the top down as opposed to the bottom up if the liquid iron thermal expansion is relatively high 13 2 10 5 k as indicated by a large number of studies the cores of almost all objects smaller than callisto pressures 8 gpa for 10 wt s compositions hence top down crystallization and compositional stratification may be an endemic feature in the cores of small to mid size solar system bodies and the evolution of crystallization induced compositional stratification may provide a natural explanation for possible early shut offs of dynamos of small bodies in the solar system

the tidal response of europa the tidal response of europa to a time varying potential is determined by solving the quasi static equilibrium equations for a body composed of several uniform maxwell viscoelastic layers models in which europa s surface ice extends all the way to the silicate mantle have weak tidal responses 1 m vertical deflection while models in which a liquid ocean underlies the ice have about 30 m peak vertical deflection the phase lag of the tidal response is very small 2 in the case of an ocean but may be large if there is no ocean and the ice has a viscosity around 1013 pa s for models with an ocean the product of the thickness and strength of the ice determines the tidal response making it difficult to determine the thickness of the ice by observing the tidal deflection of europa

probing europa s interior with natural sound sources europa s interior structure may be determined by relatively simple and robust seismo acoustic echo sounding techniques the strategy is to use ice cracking events or impacts that are hypothesized to occur regularly on europa s surface as sources of opportunity a single passive geophone on europa s surface may then be used to estimate the thickness of its ice shell and the depth of its ocean by measuring the travel time of seismo acoustic reflections from the corresponding internal strata quantitative analysis is presented with full field seismo acoustic modeling of the europan environment this includes models for europan ambient noise and conditions on signal to noise ratio necessary for the proposed technique to be feasible the possibility of determining europa s ice layer thickness by surface wave and modal analysis with a single geophone is also investigated

a simulation study of the landfall of tropical cyclones abstract by use of a triply nested movable mesh model several ideal simulations of tropical cyclone landfall were performed for a strong zonal flow of 10 m s 1 the integration domain was a 37 45 channel with the innermost mesh having a 22 22 point resolution of 1 6 general characteristics similar to observed landfalling tropical cyclones are obtained in the primary simulation experiment including an abrupt change in the low level 68 m winds at the coastline and a decay of the tropical cyclone at it moves inland additional interesting features subject to model and experimental limitations include little noticeable track change of the model storm when compared to a control experiment with an ocean surface only a possible temporary displacement or the center of the surface wind circulation from the surface pressure center at landfall and a distinct decrease in kinetic energy generation and precipitation a few hours after landfall the sensitivity to the specified land surface conditions was

long period seismology on europa 1 physically consistent interior models 1 in order to examine the potential of seismology to determine the interior structure and properties of europa it is essential to calculate seismic velocities and attenuation for the range of plausible interiors we calculate a range of models for the physical structure of europa as constrained by the satellite s composition mass and moment of inertia we assume a water ice shell a pyrolitic or a chondritic mantle and a core composed of pure iron or iron plus 20 weight percent of sulfur we consider two extreme mantle thermal states hot and cold given a temperature and composition we determine density seismic velocities and attenuation using thermodynamical models while anelastic effects will be negligible in a cold mantle and the brittle part of the ice shell strong dispersion and dissipation are expected in a hot convective mantle and the bulk of the ice shell there is a strong relationship between different thermal structures and compositions the hot mantle may maintain temperatures consistent with a liquid core made of iron plus light elements for the cold scenarios the possibility of a solid iron core cannot be excluded and it may even be favored the depths of the ocean and core mantle boundary are determined with high precision 10 km and 40 km respectively once we assume a composition and thermal structure furthermore the depth of the ocean is relatively insensitive 4 km to the core composition used

europa stratigraphy and geological history of the anti jovian region from galileo e14 solid state imaging data a tidal bulge and associated deformation are predicted to occur in europa s anti jovian region voyager data showed polygonal low albedo bands in this region it was demonstrated that when the low albedo material comprising these bands was removed the margins could be reconstructed suggesting that fracturing and lateral separation has occurred higher resolution galileo images of a 300 000 km2 portion of the anti jovian region permit recognition and mapping of a variety of features and documentation of the geological history we identify background ridged plains several distinctive types of bands and ridges lenticulae and regions of chaotic terrain these images are at relatively low incidence angles thus albedo variations predominate over topography this presents a challenge to morphologically based mapping but does not preclude development of a regional stratigraphy stratigraphic relationships show that dark bands crosscut the bright ridged plains and are themselves disrupted by lenticulae and chaos suggesting a geological history beginning with background ridged plains followed by a period dominated by band formation with the most recent history predominantly characterized by formation of lenticulae and chaos the paucity of impact craters in this region indicates that the entire sequence of units is geologically recent

satellite observations of sea surface cooling by hurricanes sea surface cooling associated with 13 hurricanes in the western north atlantic between september 1981 and december 1984 is examined using satellite derived sea surface temperature fields some surface cooling is observed in all cases however because of cloud cover and the fairly weak signal in some cases we see pronounced cooling along an extensive and continuous portion of the storm path for only three strong hurricanes the persistence of cooling following the passage of a hurricane varies from a few days to at least 16 days the amplitude of cooling is moderately well correlated with hurricane strength and is as large as 3 5 c when the hurricanes move rapidly the maximum cooling occurs well to the right of the track approximately 70 km whereas for slowly moving hurricanes the maximum cooling occurs near or on the track because western north atlantic hurricanes are often found in close proximity to high pressure systems daytime satellite images must be made with some care because of diurnal warming

long period seismology on europa 2 predicted seismic response 1 previous studies have documented the potential for using relatively short period body waves and intermediate period surface waves to explore the structure and tectonics of europa we show that long period measurements 0 001 to 0 1 hz may have large amplitudes of displacement millimeters to centimeters and are potentially measurable from orbit without requiring a lander to accurately model the long period response of europa we use normal modes calculated from physically self consistent models of europa s structure developed in part 1 cammarano et al 2007 on the basis of the geometry of observed faults we estimate that faulting events of magnitude 5 or larger may occur regularly synthetic seismograms show that long period displacement measurements with millimeter accuracy could detect current tectonic activity and determine the thickness of europa s ice shell and confirm the presence of a subsurface ocean determination of deeper structure with seismic measurements however is more challenging in the presence of a global liquid ocean which acts to decouple deeper seismic energy from the surface

geophysical controls of chemical disequilibria in europa the ocean in jupiter s moon europa may have redox balance similar to earth s on earth low temperature hydration of crustal olivine produces substantial hydrogen comparable to any potential flux from volcanic activity here we compare hydrogen and oxygen production rates of the earth system with fluxes to europa s ocean even without volcanic hydrothermal activity water rock alteration in europa causes hydrogen fluxes 10 times smaller than earth s europa s ocean may have become reducing for a brief epoch for example after a thermal orbital resonance 2 gyr after accretion estimated oxidant flux to europa s ocean is comparable to estimated hydrogen fluxes europa s ice delivers oxidants to its ocean at the upper end of these estimates if its ice is geologically active as evidence of geologic activity and subduction implies

exogenic and endogenic albedo and color patterns on europa new global and high resolution multispectral mosaics of europa have been produced from the voyager imaging data photometric normalizations are based on multiple image techniques that explicitly account for intrinsic albedo variations through pixel by pixel solutions the exogenic color and albedo pattern on europa is described by a second order function of the cosine of the angular distance from the apex of orbital motion on the basis of this second order function and of color trends that are different on the leading and trailing hemispheres the exogenic pattern is interpreted as being due to equilibrium between two dominant processes 1 impact gardening and 2 magnetospheric interactions including sulfur ion implantation and sputtering redistribution removal of the model exogenic pattern in the mosaics reveals the endogenic variations consisting of only two major units darker redder and bright materials therefore europa s visual spectral reflectivity is simple having one continuous exogenic pattern and two discrete endogenic units

spatial and temporal characterization of sea surface temperature response to tropical cyclones abstractthe spatial structure and temporal evolution of the sea surface temperature sst anomaly ssta associated with the passage of tropical cyclones tcs as well as their sensitivity to tc characteristics including tc intensity and translation speed and oceanic climatological conditions represented here by latitude are thoroughly examined by means of composite analysis using satellite derived sst data the magnitude of the tc generated ssta is larger for more intense slower moving and higher latitude tcs and it occurs earlier in time for faster moving and higher latitude storms the location of maximum ssta is farther off the tc track for faster moving storms and it moves toward the track with time after the tc passage the spatial extension of the cold wake is greater for more intense and for slower moving storms but its shape is quite independent of tc characteristics consistent with previous studies the calculations show that the mean ssta over a tc centered box nearly linearly corre

some aspects of vortex structure related to tropical cyclone motion abstract some effect of tropical cyclone structure on the vortex motion are examined in a nondivergent barotropic numerical model with no basic current as suggested earlier by demaria the initial maximum wind speed has little effect on the track vortex translation associated with the beta effect depends sensitively on the strength of the flow between 300 and 1000 km from the center if the flow in this annulus is made more cyclonic the track will turn cyclonically and move more toward the west in the northern hemisphere the dynamics of this beta drift is studied via a decomposition into symmetric and asymmetric circulations the symmetric flow experiences a slight weakening of the maximum wind speed and an anticyclonic circulation is induced beyond 600 km the asymmetric circulation is dominated by an azimuthal wavenumber one circulation with an anticyclonic gyre east of the center a cyclonic gyre to the west and a nearly uniform broad scale ventilation flow between the gyres the vortex translati

geophysical investigations of habitability in ice covered ocean worlds geophysical measurements can reveal the structures and thermal states of icy ocean worlds the interior density temperature sound speed and electrical conductivity thus characterize their habitability we explore the variability and correlation of these parameters using 1 d internal structure models we invoke thermodynamic consistency using available thermodynamics of aqueous mgso 4 nacl as seawater and nh 3 pure water ice phases i ii iii v and vi silicates and any metallic core that may be present model results suggest for europa that combinations of geophysical parameters might be used to distinguish an oxidized ocean dominated by mgso 4 from a more reduced ocean dominated by nacl in contrast with jupiter s icy ocean moons titan and enceladus have low density rocky interiors with minimal or no metallic core the low density rocky core of enceladus may comprise hydrated minerals or anhydrous minerals with high porosity cassini gravity data for titan indicate a high tidal potential love number k 2 0 6 which requires a dense internal ocean ocean 1 200 kg m 3 and icy lithosphere thinner than 100 km in that case titan may have little or no high pressure ice or a surprisingly deep water rock interface more than 500 km below the surface covered only by ice vi ganymede s water rock interface is the deepest among known ocean worlds at around 800 km its ocean may contain multiple phases of high pressure ice which will become buoyant if the ocean is sufficiently salty callisto s interior structure may be intermediate to those of titan and europa with a water rock interface 250 km below the surface covered by ice v but not ice vi

thermal orbital evolution of io and europa coupled thermal orbital evolution models of europa and io are presented it is assumed that io europa and ganymede evolve in the laplace resonance and that tidal dissipation of orbital energy is an internal heat source for both io and europa while dissipation in io occurs in the mantle as in the mantle dissipation model of segatz et al 1988 icarus 75 187 two models for europa are considered in the first model dissipation occurs in the silicate mantle while in the second model dissipation occurs in the ice shell in the latter model ice shell melting and variations of the shell thickness above an ocean are explicitly included the rheology of both the ice and the rock is cast in terms of a viscoelastic maxwell rheology with viscosity and shear modulus depending on the average temperature of the dissipating layer heat transfer by convection is calculated using a parameterization for strongly temperature dependent viscosity convection both models are consistent with the present orbital elements of io europa and ganymede it is shown that there may be phases of quasi steady evolution with large or small dissipation rates in comparison with radiogenic heating phases with runaway heating or cooling and oscillatory phases during which the eccentricity and the tidal heating rate will oscillate europa s ice thickness varies between roughly 3 and 70 km dissipation in the silicate layer or 10 and 60 km dissipation in the ice layer suggesting that europa s ocean existed for geological timescales the variation in ice thickness including both convective and purely conductive phases may be reflected in the formation of different geological surface features on europa both models suggest that at present europa s ice thickness is several tens of km thick and is increasing while the eccentricity decreases implying that the satellites evolve out of resonance including lithospheric growth in the models makes it impossible to match the high heat flux constraint for io other heat transfer processes than conduction through the lithosphere must be important for the present io

a numerical study of the effect of a mountain range on a landfalling tropical cyclone abstract a triply nested movable mesh model was used to study the effects of a mountain range on a landfalling tropical cyclone embedded in an easterly flow of 10 m s 1 the integration domain consisted of a 37 wide and 45 long channel with an innermost mesh resolution of 1 6 an idealized mountain range with maximum height of 958 meters was placed parallel to the shoreline the mountain range which spanned 19 in the north south direction and 5 in the east west direction was centered in the middle of the channel results obtained were compared with a previous landfall simulation performed without the effect of the mountain range included in particular comparison was made of the total storm rainfall maximum wind distribution and storm decay rate it was found that the storm filled much more rapidly in the simulation run with the mountain included the mountain range affected the decay rate through reduction in the supply of latent and kinetic energy into the storm circulation during as well

typhoon kai tak an ocean s perfect storm an unusually intense sea surface temperature drop dsst of about 10 88c induced by the typhoon kaitak is observed in the northern south china sea scs in july 2000 observational and high resolution scs model analyses were carried out to study the favorable conditions and relevant physical processes that cause the intense surface cooling by kai tak upwelling and entrainment induced by kai tak account for 62 and 31 of the dsst respectively so that upwelling dominates vertical entrainment in producing the surface cooling for a subcritical storm such as kai tak however wind intensity and propagation speed alone cannot account for the large dsst prior to kai tak the sea surface was anomalously warm and the main thermocline was anomalously shallow the cause was a delayed transition of winter to summer monsoon in the northern scs in may 2000 this produced an anomalously strong wind stress curl and a cold eddy capped by a thin layer of very warm surface water west of luzon kai tak was the ocean s perfect storm in passing over the eddy at the right time producing the record sst drop and high chlorophyll a concentration

pressurized oceans and the eruption of liquid water on europa and enceladus 1 it is difficult for liquid water to erupt onto the surface of icy satellites such as europa and enceladus because liquid water is more dense than ice if the ice shell thickens the volume expansion of ice upon freezing increases pressure in the subsurface ocean the excess pressure is determined by a balance between compression of ocean water and elastic expansion of the ice shell we show that on europa the freezing of 1 10 km of ice generates tangential stresses that exceed the tensile strength of ice excess pressure however is insufficient for liquid water to erupt to the surface within smaller icy satellites such as enceladus ocean pressure can become large enough to cause an eruption of large amounts of liquid water

tidally heated convection constraints on europa s ice shell thickness 1 the thickness of europa s ice shell is constrained with numerical experiments of thermal convection including heterogeneous tidal heating thermal convection occurs in the stagnant lid regime with most of the tidal heating located in the bottom half of the layer the addition of tidal heating mainly results in the increase of the temperature of the well mixed interior and in the decrease of the heat flux at the base of the ice layer in many simulations the ice in hot plumes is heated up to its melting point this induces episodic upwellings 0 5 ma of partially molten ice up to the base of the conductive lid with possible implications for the formation of lenticulae and chaos regions the thickness of the convective ice shell in equilibrium with the heat flow from the silicate core is estimated to be about 20 25 km tidal dissipation and surface temperature variations create lateral variations of the ice shell thickness of about 5 km with maxima near the equator at the jovian and anti jovian points and minima at midlatitudes surface heat flux is about 35 40 mw m 2 it is almost constant all over europa s surface even though the tidal dissipation rate is four times larger at the poles than at the equator

numerical high resolution air sea coupling over the gulf of lions during two tramontane mistral events 1 the near sea surface meteorological conditions associated with strong wind events over the mediterranean sea constitute a strong forcing on the ocean mixed layer the present study addresses the question of the sea surface scheme used in high resolution and short range atmospheric numerical modeling to represent the ocean mixed layer response under these severe mistral wind events in the gulf of lions area several slab ocean models have been used coupled with the weather research and forecasting wrf model and applied on two mistral cases 1 a slab model based on the transport divergence equation where the mixed layer evolution is only driven by the wind stress 2 a slab model where the temperature is the only prognostic variable and evolves according to the net surface heat flux and 3 a complete slab scheme from price 1981 the coupled simulations are also compared to two basic simulations one using a constant sea surface temperature sst field during all of the model integration and another using a 6 hourly update sea surface temperature reanalysis in this study we mainly focus on the slab model performances we identify the processes involved in the ocean mixed layer response under strong wind situations i e local and fast cooling and deepening the feedbacks of an interactive ocean mixed layer on the atmospheric simulation are also investigated

brine volcanism and the interior structures of asteroids and icy satellites abstract cryovolcanism is among the foremost processes responsible for modifying the surfaces of icy satellites volcanic brine petrogenesis in ammonia deficient satellites should mainly involve eutectic melting in relevant salt water systems carbonaceous chondrites provide useful insights into the compositions of salts and aqueously altered rock in icy satellites and asteroids c1 chondrites contain about one fifth by mass of salts in various states of hydration many aspects of the petrogenesis and physical volcanology of icy satellite brines should be well described in the system h2o mgso4 na2so4 minor components include sulfates of k ni mn and ca chondrites also contain abundant carbonates but these are probably not very important in brine magmatism due to their low solubilities under expected conditions chlorides are also unimportant under most circumstances because of the low cosmic abundance ratio of cl s soluble salts may have profound effects on the geology and structure of icy satellites and asteroids in some models late episodes of water volcanism are facilitated by high buoyant forces due to the relatively high densities of sulfate rich mantle and crustal layers in other models early hypersaline brine volcanism quickly yields to plutonic magmatism due to low crustal densities europa probably has a layered crust composed of anhydrous mg na sulfates near the base and a frozen or partially molten eutectic mixture of ice and hydrated mg and na sulfates near the surface ganymede may have a crust about 300 km thick composed of a 10 1 ratio of ice mirabilite and a mantle 500 km thick composed of 50 ice phases plus 50 hydrated mg and na sulfates

galileo magnetometer measurements a stronger case for a subsurface ocean at europa on 3 january 2000 the galileo spacecraft passed close to europa when it was located far south of jupiter s magnetic equator in a region where the radial component of the magnetospheric magnetic field points inward toward jupiter this pass with a previously unexamined orientation of the external forcing field distinguished between an induced and a permanent magnetic dipole moment model of europa s internal field the galileo magnetometer measured changes in the magnetic field predicted if a current carrying outer shell such as a planet scale liquid ocean is present beneath the icy surface the evidence that europa s field varies temporally strengthens the argument that a liquid ocean exists beneath the present day surface

does europa have a subsurface ocean evaluation of the geological evidence it has been proposed that jupiter s satellite europa currently possesses a global subsurface ocean of liquid water galileo gravity data verify that the satellite is differentiated into an outer h2o layer about 100 km thick but cannot determine the current physical state of this layer liquid or solid here we summarize the geological evidence regarding an extant subsurface ocean concentrating on galileo imaging data we describe and assess nine pertinent lines of geological evidence impact morphologies lenticulae cryovolcanic features pull apart bands chaos ridges surface frosts topography and global tectonics an internal ocean would be a simple and comprehensive explanation for a broad range of observations however we cannot rule out the possibility that all of the surface morphologies could be due to processes in warm soft ice with only localized or partial melting two different models of impact flux imply very different surface ages for europa the model favored here indicates an average age of 50 myr searches for evidence of current geological activity on europa such as plumes or surface changes have yielded negative results to date the current existence of a global subsurface ocean while attractive in explaining the observations remains inconclusive future geophysical measurements are essential to determine conclusively whether or not there is a liquid water ocean within europa today

europa s differentiated internal structure inferences from four galileo encounters radio doppler data from four encounters of the galileo spacecraft with the jovian moon europa have been used to refine models of europa s interior europa is most likely differentiated into a metallic core surrounded by a rock mantle and a water ice liquid outer shell but the data cannot eliminate the possibility of a uniform mixture of dense silicate and metal beneath the water ice liquid shell the size of a metallic core is uncertain because of its unknown composition but it could be as large as about 50 percent of europa s radius the thickness of europa s outer shell of water ice liquid must lie in the range of about 80 to 170 kilometers

grain size sensitive seismic wave attenuation in polycrystalline olivine 1 in order to investigate the processes responsible for the attenuation of seismic shear waves in the earth s upper mantle four olivine polycrystals ranging in mean grain size d from 3 to 23 m have been fabricated characterized and mechanically tested in torsion at high temperatures and seismic frequencies both the shear modulus which governs the shear wave speed vs and the dissipation of shear strain energy q 1 have been measured as functions of oscillation period to temperature t and for the first time grain size at sufficiently high t all four specimens display similar absorption band viscoelastic behavior adequately represented for 1000 t 1200 or 1300 c and 1 to 100 s by the expression q 1 a tod 1 exp e rt with a 7 5 102 s m 0 26 and e 424 kj mol 1 this mildly grain size sensitive viscoelastic behavior of melt free polycrystalline olivine is attributed to a combination of elastically and diffusionally accommodated grain boundary sliding the latter becoming progressively more important with increasing t and or to extrapolation to the larger mm cm grain sizes expected in the earth s upper mantle yields levels of dissipation comparable with those observed seismologically implying that the same grain size sensitive processes might be responsible for much of the observed seismic wave attenuation the temperature sensitivity of vs is increased substantially by the viscoelastic relaxation allowing the lateral variability of wave speeds to be associated with relatively small temperature perturbations

interaction of binary tropical cyclones in a coupled tropical cyclone ocean model the motion and evolution of binary tropical cyclones was investigated using a coupled tropical cyclone ocean movable nested grid model the model consists of eight layer atmospheric and seven layer ocean primitive equation models several regimes of binary storm interaction have been identified depending on the initial separation distance d and differences in storm strengths at d less than a few hundred kilometers interacting storms experienced complete merger cm or partial merger pm at larger d between about 600 km and 1000 km three regimes of storm interaction have been found pm straining out so characterized by complete disintegration of the weaker storm and mutual straining out mso characterized by weakening and dissipation of both storms so occurred when the interacting storms had substantially different intensities and strengths mso was observed when the interacting storms were comparable in size and intensity in the latter case the storms were unable to approach each other at distances smaller than a certain minimum distance of about 450 500 km without being mutually stretched out moreover initial attraction of the storms in this regime was replaced by repulsion as frequently observed in the western pacific at d exceeding about 1000 km elastic interaction ei was found when the storms interact without any significant changes in their intensity and structure in additional experiments with a conditional instability of the second kind cisk type parameterization of convective heating the storm interaction was very different the storms were nearly axisymmetric and very compact and they continued approaching each other until they merged thus more realistic simulations of binary storm interaction can be achieved by using a physically more reasonable convective parameterization

scaling laws for time dependent stagnant lid convection in a spherical shell abstract systematic numerical simulations of time dependent stagnant lid convection in an internally heated spherical shell are performed in order to obtain scaling relationships for various convective parameters convection beneath the lid is time dependent and characterized by passive upwellings and cold sheet like downwellings the heat flux scaling relationship agrees with results from experiment two dimensional numerical simulations and boundary layer stability analysis without a mobile lithosphere low heat transport efficiency and extensive melting during evolution of the terrestrial planets which are predicted by two dimensional studies also apply in fully three dimensional spherical shell geometry the scaling relationships for convection induced stresses in the lid are also very similar to those obtained in two dimensions this supports the idea that initiation of subduction in the stagnant lid convection regime requires a very weak lithosphere

asymmetric oceanic response to a hurricane deep water observations during hurricane isaac the eye of hurricane isaac passed through the center of an array of six deep water water column current meter moorings deployed in the northern gulf of mexico the trajectory of the hurricane provided for a unique opportunity to quantify differences in the full water column oceanic response to a hurricane to the left and right of the hurricane trajectory prior to the storm passage relative vorticity on the right side of the hurricane was strongly negative while on the left relative vorticity was positive this resulted in an asymmetry in the near inertial frequencies oceanic response at depth and horizontally a shift in the response to a slightly larger inertial frequencies 1 11f was observed and verified by theory additionally the storm passage coincided with an asymmetric change in relative vorticity in the upper 1000 m which persisted for 15 inertial periods vertical propagation of inertial energy was estimated at 29 m d while horizontal propagation at this frequency was approximately 5 7 km d wavelet analysis showed two distinct subinertial responses one with a period of 2 5 days and another with a period of 5 12 days analysis of the subinertial bands reveals that the spatial and temporal scales are shorter and less persistent than the near inertial variance as the array is geographically located near the site of the deep water horizon oil spill the spatial and temporal scales of response have significant implications for the fate transport and distribution of hydrocarbons following a deep water spill event

temperatures on europa from galileo photopolarimeter radiometer nighttime thermal anomalies galileo observations of europa s thermal emission show low latitude diurnal brightness temperatures in the range of 86 to 132 kelvin nighttime temperatures form an unexpected pattern with high temperatures on the bright ejecta blanket of the crater pwyll and an equatorial minimum in temperatures after sunset uncorrelated with surface albedo or geology the nighttime anomalies may be due to regional thermal inertia variations of an unknown origin which are equivalent to a two to threefold variation in thermal conductivity or to endogenic heat fluxes locally reaching 1 watt per square meter endogenic heat flow at this high level although consistent with some geological evidence is theoretically unlikely