formation of 26 8 26 9 σθ water in the kuril basin of the sea of okhotsk as a possible origin of north pacific intermediate water by using all japanese hydrographic data obtained south of 55 n in latitude in the sea of okhotsk we compile a data set for this study our investigations with these data show that a large quantity of relatively cold fresh oxygen rich homogeneous intermediate water with a density range of 26 8 to 26 9 exists in the kuril basin we name this intermediate water the kuril basin intermediate water kbiw results of isosteric analyses show that a possible origin of kbiw is located in a region off the hokkaido coast in the southwestern sea of okhotsk we suggest that kbiw is produced by the isopycnal mixing of relatively dense soya warm water which appears only in early spring with the colder fresher water which originates from the northwestern okhotsk finally we demonstrate that kbiw may be a source water of the north pacific intermediate water npiw because it has the same density range and water properties

martian surface simulations computer generated surfaces have been created to aid in imaging landing and rover studies for mars and the moon they are also being applied to the study of cratering histories the surfaces are generated in steps which attempt to mimic geologic episodes surface roughness is realized fractally while craters and other specific features have shapes and distributions dictated by observation surface materials are assigned appropriate albedos making the images more realistic with the inclusion of correlations between crater and rock distributions the simulations are beginning to acquire a predictive capability

variation of the lunar highland surface roughness at baseline 0 15 100 km and the relationship to relative age we report the surface roughness analysis of the lunar highlands for the baseline range 0 15 100 km we use the median differential slope m to investigate the scale dependency of the roughness and derive the global m distribution from selene laser altimeter and terrain camera data while m l versus baseline l km plots vary among different highland types all highlands commonly show a peak at 3 30 km the pre nectarian surface shows a relatively large m 20 30 km our analysis is supported by the simulation of synthetic surface cratering models and crater statistics in our simulation a peak of m 30 km is successfully reproduced the actual crater density shows good correlation with an empirical roughness indicator however a large part of the nectarian surface shows a peak at 6 9 km baseline this peak may be caused by secondary craters and ejecta deposit textures from the nectarian system basins

under ice ambient noise in eastern beaufort sea canadian arctic and its relation to environmental forcing this paper analyzes an 8 month time series november 2005 to june 2006 of underwater noise recorded at the mouth of the amundsen gulf in the marginal ice zone of the western canadian arctic when the area was 90 ice covered the time series of the ambient noise component was computed using an algorithm that filtered out transient acoustic events from 7 min hourly recordings of total ocean noise over a 0 4 1 khz frequency band under ice ambient noise did not respond to thermal changes but showed consistent correlations with large scale regional ice drift wind speed and measured currents in upper water column the correlation of ambient noise with ice drift peaked for locations at ranges of 300 km off the mouth of the amundsen gulf these locations are within the multi year ice plume that extends westerly along the coast in the eastern beaufort sea due to the large beaufort gyre circulation these results reveal that ambient noise in eastern beaufort sea in winter is mainly controlled by the same meteorological and oceanographic forcing processes that drive the ice drift and the large scale circulation in this part of the arctic ocean

lunar topographic roughness maps from lunar orbiter laser altimeter lola data scale dependence and correlation with geologic features and units we present maps of the topographic roughness of the moon at hectometer and kilometer scales the maps are derived from range profiles obtained by the lunar orbiter laser altimeter lola instrument onboard the lunar reconnaissance orbiter lro spacecraft as roughness measures we used the interquartile range of profile curvature at several baselines from 115 m to 1 8 km and plotted these in a global map format the maps provide a synoptic overview of variations of typical topographic textures and utilize the exceptional ranging precision of the lola instrument we found that hectometer scale roughness poorly correlates with kilometer scale roughness because they reflect different sets of processes and time scales hectometer scale roughness is controlled by regolith accumulation and modification processes and affected by the most recent events primarily geologically recent 1 2 ga meteoritic impacts kilometer scale roughness reflects major geological impact volcanic and tectonic events in earlier geological history young large impact craters are rough and their roughness decreases with age the global roughness maps revealed a few unusually dense clusters of hectometer and decameter size impact craters that differ in their morphology and settings from typical secondary crater clusters and chains the origin of these features is enigmatic the maps can assist in the geological mapping of the lunar maria by revealing contacts between volcanic plain units the global roughness maps also clearly reveal cryptomaria old volcanic plains superposed by younger materials primarily crater and basin ejecta

comparing landslides to fluidized crater ejecta on mars 1 we use the mars global surveyor and viking data sets to compare and contrast the geomorphology of four large martian landslides located in valles marineris to fluidized ejecta of seven fresh martian craters located in lunae planum both mass movements have flowed over the martian surface and possess characteristics seen in terrestrial mass movements we combine these comparisons with simple flow models to determine how the planar geometry of landslides and the cylindrical geometry of ejecta can generate different topographic expressions for the same input constraints our purpose is to better understand the emplacement processes of both types of mass movements our geomorphic analyses are consistent with previous views that the large martian landslides resemble large terrestrial long run out flows the planar flow model supports this inference martian landslides probably flowed as a basal glide where motion is limited to a narrow interface at the base of the mass movement geomorphic investigations of fresh multilayered ejecta indicate that their inner portions with their subtle rampart probably flowed like their landslide counterparts as a basal glide distal pronounced contiguous ramparts however resemble features akin to terrestrial debris flows the cylindrical flow model shows that differences in geometry can mask the dynamics of flow emplacement this model suggests as expected a basal glide origin for the inner portions of the ejecta surprisingly basal glide also best explains the topography of the distal ejecta ramparts

morphometry of impact craters on mercury from messenger altimetry and imaging abstract data acquired by the mercury laser altimeter and the mercury dual imaging system on the messenger spacecraft in orbit about mercury provide a means to measure the geometry of many of the impact craters in mercury s northern hemisphere in detail for the first time the combination of topographic and imaging data permit a systematic evaluation of impact crater morphometry on mercury a new calculation of the diameter d t at which craters transition with increasing diameter from simple to complex forms and an exploration of the role of target properties and impact velocity on final crater size and shape measurements of impact crater depth on mercury confirm results from previous studies with the exception that the depths of large complex craters are typically shallower at a given diameter than reported from mariner 10 data secondary craters on mercury are generally shallower than primary craters of the same diameter no significant differences are observed between the depths of craters within heavily cratered terrain and those of craters within smooth plains the morphological attributes of craters that reflect the transition from simple to complex craters do not appear at the same diameter instead flat floors first appear with increasing diameter in craters at the smallest diameters followed with increasing diameter by reduced crater depth and rim height and then collapse and terracing of crater walls differences reported by others in d t between mercury and mars despite the similar surface gravitational acceleration on the two bodies are confirmed in this study the variations in d t between mercury and mars cannot be adequately attributed to differences in either surface properties or mean projectile velocity

sea ice noise generating processes an ambient noise model is presented for sound generated in compact ice by ridging microcracking and mixed layer shearing the model describes sound intensity as the sum of these different processes and the sum of intensities propagated from all source locations the source intensity changes as a function of time for each frequency and can depend on material parameters that affect behavior such as ice thickness the processes are identified by their driving forces the large scale stress state is related to the local stress in each ice floe which when small can cause local cracking but does not contribute to large scale deformations if the stress level is large enough to cause ridging rafting and leading then large scale deformations occur independently of these large scale deformations the ice can move as a rigid body which shears the mixed layer each of these processes is assumed to have its own spectral signature and each is driven by a different environmental variable local cracking is

the distribution and origin of smooth plains on mercury 1 orbital images from the messenger spacecraft show that 27 of mercury s surface is covered by smooth plains the majority 65 of which are interpreted to be volcanic in origin most smooth plains share the spectral characteristics of mercury s northern smooth plains suggesting they also share their magnesian alkali basalt like composition a smaller fraction of smooth plains interpreted to be volcanic in nature have a lower reflectance and shallower spectral slope suggesting more ultramafic compositions an inference that implies high temperatures and high degrees of partial melting in magma source regions persisted through most of the duration of smooth plains formation the knobby and hummocky plains surrounding the caloris basin known as odin type plains occupy an additional 2 of mercury s surface the morphology of these plains and their color and stratigraphic relationships suggest that they formed as caloris ejecta although such an origin is in conflict with a straightforward interpretation of crater size frequency distributions if some fraction is volcanic this added area would substantially increase the abundance of relatively young effusive deposits inferred to have more mafic compositions smooth plains are widespread on mercury but they are more heavily concentrated in the north and in the hemisphere surrounding caloris no simple relationship between plains distribution and crustal thickness or radioactive element distribution is observed a likely volcanic origin for some older terrain on mercury suggests that the uneven distribution of smooth plains may indicate differences in the emplacement age of large scale volcanic deposits rather than differences in crustal formational process

extent age and resurfacing history of the northern smooth plains on mercury from messenger observations abstract messenger orbital images show that the north polar region of mercury contains smooth plains that occupy 7 of the planetary surface area within the northern smooth plains nsp we identify two crater populations those superposed on the nsp post plains and those partially or entirely embayed buried the existence of the second of these populations is clear evidence for volcanic resurfacing the post plains crater population reveals that the nsp do not exhibit statistically distinguishable subunits on the basis of crater size frequency distributions nor do measures of the areal density of impact craters reveal volcanically resurfaced regions within the nsp these results suggest that the most recent outpouring of volcanic material resurfaced the majority of the region and that this volcanic flooding emplaced the nsp over a relatively short interval of geologic time perhaps 100 my or less stratigraphic embayment relationships within the buried crater population including partial crater flooding and the presence of smaller embayed craters within the filled interiors of larger craters and basins indicate that a minimum of two episodes of volcanic resurfacing occurred from the inferred rim heights of embayed craters we estimate the nsp to be regionally 0 7 1 8 km thick with a minimum volume of volcanic material of 4 10 6 to 10 7 km 3 because of the uncertainty in the impact flux at mercury the absolute model age of the post plains volcanism could be either 3 7 or 2 5 ga depending on the chronology applied

identification and quantification of soundscape components in the marginal ice zone acoustic experiments using an integrated ice station were carried out during august 2012 and september 2013 in the marginal ice zone miz of fram strait the two experiments lasted four days each and collected under ice acoustic recordings together with wave in ice and meteorological data synthetic aperture radar satellite data provided information on regional ice conditions four major components of the under ice soundscape were identified ship cavitation noise seismic airgun noise marine mammal vocalizations and natural background noise ship cavitation noise was connected to heavy icebreaking it dominated the soundscape at times with noise levels nls 100 km from the icebreaker increased by 10 28 db seismic airgun noise that originated from seismic surveys more than 800 km away was present during 117 out of 188 observation hours it increased nls at 20 120 hz by 2 6 db marine mammal vocalizations were a minor influence on measured nls but their prevalence shows the biological importance of the miz the 10th percentile of the noise distributions was used to identify the ambient background noise background nls above 100 hz differed by 12 db between the two experiments presumably due to variations in natural noise sources

self affine behavior of martian topography at kilometer scale from mars orbiter laser altimeter data 1 we used mars orbiter laser altimeter mola data from the current mars global surveyor mission to characterize the topographic roughness of the martian surface and to provide a mean to evaluate clutter at long 10 300 m wavelengths such wavelengths are relevant for the marsis and sharad subsurface radars which will be flown in future missions to mars the method of analysis is based on the assumption that topography can be described as a self affine fractal 30 km long segments of mola altimetry profiles have thus been reduced to the topographic parameters rms height rms slope and hurst exponent this last related to the fractal dimension which can be used as inputs to a near nadir radar scattering model the values of the hurst exponent are greater than 0 5 for most of the surface meaning a scaling behavior which is almost self similar maps of rms height and hurst exponent show that these two parameters have very different spatial distributions whereas the rms height is patterned after the north south dichotomy the hurst exponent follows a latitudinal trend we make use of a multivariate method called g mode to classify profiles in the three dimensional parameter space we find several roughness units some of which have a strong correlation with certain geologic units while others are bound by latitude however at scales between 300 m and 3 km large stretches of the surface of mars share common statistical properties of topography independent from the north south dichotomy

the roughness of natural terrain a planetary and remote sensing perspective we examine the various methods and parameters in common use for quantifying and reporting surface topographic roughness it is shown that scale dependent roughness parameters are almost always required though not widely used we suggest a method of standardizing the parameters that are computed and reported so that topographic data gathered by different workers using different field techniques can be directly and easily intercompared we illustrate the proposed method by analyzing topographic data from 60 different surfaces gathered by five different groups and examine the information for common features we briefly discuss the implications of our analysis for studies of planetary surface roughness lander safety and radar remote sensing modeling and analysis

topographic power spectra of cratered terrains theory and application to the moon impact cratering produces characteristic variations in the topographic power spectral density psd of cratered terrains which are controlled by the size frequency distribution of craters and the spectral content shape of individual features these variations are investigated here in two parallel approaches first a cratered terrain model based on monte carlo emplacement of craters and benchmarked by an analytical formulation of the one dimensional psd is employed to generate topographic surfaces at a range of size frequency power law exponents and shape dependencies for self similar craters the slope of the psd varies inversely with that of the production function leveling off to 0 at high surface topography dominated by the smallest craters and maintaining a roughly constant value 2 at low surface topography dominated by the largest craters the effects of size dependent shape parameters and various crater emplacement rules are also considered second we compare the model derived predictions for the behavior of the psd with values of calculated along transects from the lunar orbiter laser altimeter lola at small scales 115 m to 1 km model predictions agree well with the psd slope over the observed range of lunar size frequency distributions differences between global psd slopes at subkilometer and kilometer scales reflect a scale separation in roughness consistent with prior observations using a variety of surface roughness parameters understanding the statistical markers left by the impact cratering process on the lunar surface is useful for distinguishing between competing geological processes on planetary surfaces throughout the solar system

the self secondary crater population of the hokusai crater on mercury whether or not self secondaries dominate small crater populations on continuous ejecta deposits and floors of fresh impact craters has long been a controversy this issue potentially affects the age determination technique using crater statistics here the self secondary crater population on the continuous ejecta deposits of the hokusai crater on mercury is unambiguously recognized superposition relationships show that this population was emplaced after both the ballistic sedimentation of excavation flows and the subsequent veneering of impact melt but it predated the settlement and solidification of melt pools on the crater floor fragments that formed self secondaries were launched via impact spallation with large angles complex craters on the moon mercury and mars probably all have formed self secondaries populations dating young craters using crater statistics on their continuous ejecta deposits can be misleading impact melt pools are less affected by self secondaries overprint by subsequent crater populations with time reduces the predominance of self secondaries

kilometer scale topographic roughness of mercury correlation with geologic features and units we present maps of the topographic roughness of the northern circumpolar area of 30 mercury at kilometer scales the maps are derived from range profiles obtained by the 31 mercury laser altimeter mla instrument onboard the mercury surface space 32 environment geochemistry and ranging messenger mission as measures of 33 roughness we used the interquartile range of profile curvature at three baselines 0 7 km 34 2 8 km and 11 km the maps provide a synoptic overview of variations of typical 35 topographic textures they show a dichotomy between the smooth northern plains and 36 rougher more heavily cratered terrains analysis of the scale dependence of roughness 37 indicates that the regolith on mercury is thicker than on the moon by approximately a 38 factor of three roughness contrasts within northern volcanic plains of mercury indicate a 39 younger unit inside goethe basin and inside another unnamed stealth basin these new 40 data permit interplanetary comparisons of topographic roughness

comparisons of fresh complex impact craters on mercury and the moon implications for controlling factors in impact excavation processes the impact cratering process is usually divided into the coupling excavation and modification stages where each stage is controlled by a combination of different factors although recognized as the main factors governing impact processes on airless bodies the relative importance of gravity target and projectile properties and impact velocity in each stage is not well understood we focus on the excavation stage to place better constraints on its controlling factors by comparing the morphology and scale of crater exterior structures for similar sized fresh complex craters on the moon and mercury we find that the ratios of continuous ejecta deposits continuous secondaries facies and the largest secondary craters on the continuous secondaries facies between same sized mercurian and lunar craters are consistent with predictions from gravity regime crater scaling laws our observations support that gravity is a major controlling factor on the excavation stage of the formation of complex impact craters on the moon and mercury on the other hand similar sized craters with identical background terrains on mercury have different spatial densities of secondaries on the continuous secondaries facies suggesting that impactor velocity may also be important during the excavation stage as larger impactor velocity may also cause greater ejection velocities moreover some craters on mercury have more circular and less clustered secondaries on the continuous secondaries facies than other craters on mercury or the moon this morphological difference appears not to have been caused by the larger surface gravity or the larger median impact velocity on mercury a possible interpretation is that at some places on mercury the target material might have unique properties causing larger ejection angles during the impact excavation stage we conclude that gravity is the major controlling factor on the impact excavation stage of complex craters while impact velocity and target properties also affect the excavation stage but to a lesser extent than gravity

initial observations from the lunar orbiter laser altimeter lola as of june 19 2010 the lunar orbiter laser altimeter an instrument on the lunar reconnaissance orbiter has collected over 2 0 10 9 measurements of elevation that collectively represent the highest resolution global model of lunar topography yet produced these altimetric observations have been used to improve the lunar geodetic grid to 10 m radial and 100 m spatial accuracy with respect to the moon s center of mass lola has also provided the highest resolution global maps yet produced of slopes roughness and the 1064 nm reflectance of the lunar surface regional topography of the lunar polar regions allows precise characterization of present and past illumination conditions lola s initial global data sets as well as the first high resolution digital elevation models dems of polar topography are described herein

topography of the northern hemisphere of mercury from messenger laser altimetry laser altimetry by the messenger spacecraft has yielded a topographic model of the northern hemisphere of mercury the dynamic range of elevations is considerably smaller than those of mars or the moon the most prominent feature is an extensive lowland at high northern latitudes that hosts the volcanic northern plains within this lowland is a broad topographic rise that experienced uplift after plains emplacement the interior of the 1500 km diameter caloris impact basin has been modified so that part of the basin floor now stands higher than the rim the elevated portion of the floor of caloris appears to be part of a quasi linear rise that extends for approximately half the planetary circumference at mid latitudes collectively these features imply that long wavelength changes to mercury s topography occurred after the earliest phases of the planet s geological history

kilometer scale roughness of mars results from mola data analysis the mars orbiter laser altimeter mola data are used to characterize the kilometer scale surface roughness of mars the median absolute value of the differential slope at a given baseline is proposed as a data derived measure of the surface roughness at this scale study of the scale dependence of roughness for the smoothest terrains gives an independent estimate of 20 cm for mola ranging accuracy the baseline lengths from 0 6 to 20 km are used and kilometer scale roughness is mapped for the entire surface the maps show that different geological units have distinctive roughness characteristics scale dependence of roughness for a number of geological units is presented and discussed the southern polar cap is rougher than the northern at kilometer and subkilometer scale which suggests differences in the sublimation condensation balance the vastitas borealis formation has a distinctive 3 km scale background surface topography which suggests a nonvolcanic origin for its upper layer young volcanic plains in amazonis planitia and the eastern part of elysium planitia are very similar to each other in their roughness characteristics and differ from other volcanic plains on mars which suggests a distinctive eruption style there are systematic latitudinal variations of roughness in both the southern highlands and the northern lowlands terrains at high latitude are smoother at short baselines the characteristic vertical scale related to this difference is several meters processes that could be responsible for formation of this trend include creep of ice rich near surface material at high latitudes treatment of the surface with repetitive deposition and sublimation of seasonal frost climate controlled deposition and or cementation of dust at high latitudes and repetitive sublimation and accumulation of subsurface ice at low latitudes with climate variations all mechanisms of origin could operate more effectively under different climate conditions relevant morphological observations favor mechanisms involving deposition of smooth blankets at high latitudes

a comparison of rayed craters on the moon and mercury 1 observations of rayed craters at optical and radar wavelengths provide insight into the processes that lead to ray formation and degradation on terrestrial planets we have compared optical and s band radar data for several large 20 km diameter young craters on the moon and mercury and find evidence that secondary cratering plays a significant role in the formation of crater rays regions where rays appear bright to optical and radar sensors correspond to dense concentrations of secondary craters and the observed radar enhancement appears to be a result of the deposition of blocky immature ejecta from the secondary craters and or the rocky immature interior walls of the secondary craters we define a new optical maturity index for mercury and find that rays in radar and optical images correspond closely indicating that the rays are rich in centimeter to decimeter sized clasts rays on the moon are less prominent at radar wavelengths suggesting that they are currently composed of smaller clasts centimeter sized or less this difference suggests that secondary craters are larger on mercury and capable of excavating more decimeter sized clasts furthermore observations of rayed craters provide an opportunity to assign relative ages to the youngest craters on the moon and mercury although rayed craters on mercury appear most similar to the youngest craters on the moon the apparent ages are more likely influenced by inherent differences in impact velocity surface gravitational acceleration and target properties that result in the formation of larger secondary craters on mercury

intercrater plains on mercury insights into unit definition characterization and origin from messenger datasets abstract orbital observations by the mercury surface space environment geochemistry and ranging messenger spacecraft are used to re evaluate the nature and origin of the oldest mapped plains deposits on mercury the intercrater and intermediate plains units defined by mariner 10 investigators despite the large areal extent of these plains which comprise approximately one third of the planetary surface area viewed by mariner 10 their formation mechanism was not well constrained by mariner 10 imaging one hypothesis attributed plains formation to ponding of fluidized impact ejecta to create relatively smooth surfaces another hypothesis was that these plains are of volcanic origin to assess the origin of these older plains and the contribution of early volcanism to resurfacing on mercury we have used messenger data to analyze the morphology spectral properties impact crater statistics and topography of mariner 10 type areas of intercrater and intermediate plains on the basis of new criteria for the identification of intercrater and intermediate plains derived from these observations we have remapped 18 of the surface of mercury we find that the intercrater plains are a highly textured unit with an abundance of secondary craters whereas the intermediate plains are composed of both intercrater and smooth plains we suggest that the term intermediate plains not be used to map the surface of mercury henceforth but rather this unit should be subdivided into its constituent intercrater and smooth plains units we argue that a substantial percentage of the intercrater plains are composed of volcanic materials on the basis of 1 examples of areas where ejecta from a small number of superposed craters have transformed smooth plains deposits of volcanic origin into a unit indistinguishable from intercrater plains 2 the range in ages of intercrater plains deposits as interpreted from crater size frequency distributions and 3 the near global distribution of intercrater plains compared with the uneven distribution of impact basins and their associated ejecta deposits

global surface slopes and roughness of the moon from the lunar orbiter laser altimeter 1 the acquisition of new global elevation data from the lunar orbiter laser altimeter carried on the lunar reconnaissance orbiter permits quantification of the surface roughness properties of the moon at unprecedented scales and resolution we map lunar surface roughness using a range of parameters median absolute slope both directional along track and bidirectional in two dimensions median differential slope and hurst exponent over baselines ranging from 17 m to 2 7 km we find that the lunar highlands and the mare plains show vastly different roughness properties with subtler variations within mare and highlands most of the surface exhibits fractal like behavior with a single or two different hurst exponents over the given baseline range when a transition exists it typically occurs near the 1 km baseline indicating a significant characteristic spatial scale for competing surface processes the hurst exponent is high within the lunar highlands with a median value of 0 95 and lower in the maria with a median value of 0 76 the median differential slope is a powerful tool for discriminating between roughness units and is useful in characterizing among other things the ejecta surrounding large basins particularly orientale as well as the ray systems surrounding young copernican age craters in addition it allows a quantitative exploration on mare surfaces of the evolution of surface roughness with age