mesoscale oceanographic processes beneath the ice of fram strait a major component of the fram strait marginal ice zone experiment was the investigation of air sea ice interactions processes and circulation patterns found behind the local ice edge and on scales greater than 10 kilometers mesoscale and large scale neutrally buoyant floats ice tethered cyclesondes and helicopter based measurements were used to obtain uniquely integrated and consistent views of the mesoscale ocean features beneath the ice cover of fram strait within the vicinity of the yermak plateau three distinct regions of mesoscale motion were observed that coincided with the shallow topography of the plateau the northward flowing atlantic water over the western flank of the plateau and the strong current shear zone of the east greenland polar front a subice meander of the front was also observed which was probably occluded subsequently

variations of mesoscale and large scale sea ice morphology in the 1984 marginal ice zone experiment as observed by microwave remote sensing during the summer 1984 marginal ice zone experiment in the fram strait and greenland sea mizex 84 passive and active microwave sensors on five aircraft and the nimbus 7 scanning multichannel microwave radiometer smmr acquired synoptic sequential observations which when combined give a comprehensive sequential description of the mesoscale and large scale ice morphology variations during the period june 9 through july 16 1984 the high resolution ice concentration distributions in these images agree well with the low resolution smmr distributions for diffuse ice edges the 30 smmr ice concentration isopleth corresponds to the ice edge while for compact conditions the ice edge falls within the 40 to 50 smmr isopleths throughout the experiment ice edge meanders and eddies repeatedly formed moved and disappeared but the ice edge remained within a 100 km wide zone the ice pack behind this alternately diffuse and compact edge underwent rapid and pronounced variations in ice concentration over a 200 km wide zone the aircraft microwave images show the complex structures and ephemeral nature of the mesoscale sea ice morphology the difference in oceanographic forcing between the eastern and western sectors of the experiment area generated pronounced ice morphology differences on the yermak plateau from 3 e to 10 e the weak ocean circulation allowed the wind to be the dominant force in determining the ice morphology to the southwest of this region over the molloy deep and the greenland continental shelf break from 3 e to 8 w the ice morphology was dominated by the energetic east greenland current with its associated eddies and meanders

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

holocene survival of late pleistocene megafauna in china a critical review of the evidence late quaternary megafaunal extinction chronologies are poorly understood across eastern and southeast asia previous radiometric studies suggested that surprisingly many extinct late pleistocene large mammal species survived into the holocene in northern china bos primigenius coelodonta antiquitatis mammuthus primigenius and southern china ailuropoda baconi crocuta crocuta ultima megatapirus augustus stegodon orientalis sus cf xiaozhu indicating that chinese megafaunal extinctions may have been staggered across the late quaternary we critically re examined all radiometric evidence suggesting holocene survival of chinese late quaternary megafauna and conducted new dating of mammal material from reportedly holocene sites containing characteristically late pleistocene faunas evidence for holocene survival of any chinese late pleistocene megafaunal species is weak or untenable no previous radiometric dates used to support holocene megafaunal survival represent direct bone dates for species of interest and stratigraphic association between material yielding holocene dates and megafaunal remains is dubious at most sites concerns over accurate identification of faunal material further confuse claims for holocene survival of many species robust radiometric last occurrence dates for extinct chinese megafauna are all restricted to the late pleistocene similar to the timing of many other late quaternary megafaunal species extinctions elsewhere in eurasia and the americas c 2013 elsevier ltd all rights reserved

climate people and faunal succession on java indonesia evidence from song gupuh song gupuh a partially collapsed cave in the gunung sewu limestones of east java indonesia contains over 16 m of deposits with a faunal sequence spanning some 70 ka major changes in the range of animals represented show the impact of climate change and humans the terminal pleistocene and early holocene was a period of maximum biodiversity human use of song gupuh and other cave sites in the region also intensified significantly from ca 12 ka together with a new focus on exploitation of small bodied species macaque monkeys and molluscs the first evidence for import of resources from the coast and use of bone and shell tools human activity especially after the onset of the neolithic around 2 6 ka subsequently contributed to a progressive loss of many species from the area including tapir elephant malayan bear rhino and tiger and this extinction process is continuing we conclude by discussing the biogeographical significance of song gupuh in the context of other sites in java e g punung wajak and further afield e g liang bua

boundary layer upper ocean and ice observations in the greenland sea marginal ice zone during the 1984 marginal ice zone experiment a coordinated ocean boundary layer and mixed layer experiment was carried out in concert with a complete heat and mass balance study in the summer marginal ice zone miz of the greenland sea the measurements were made at two drifting ice stations and included observations of ocean boundary layer turbulence profiles of water temperature salinity and velocity ice ablation ice concentration solar radiation and spectral albedos ocean conditions were found to be extremely variable the ice and water velocities were heavily influenced by tidal and inertial motions with amplitudes from 6 to 12 cm s 1 in the course of the drift a 30 km eddy was crossed wherein ice and water velocities exceeded 15 cm s 1 the northern extension of the east greenland polar front was encountered and a northward flow of atlantic water into the arctic basin was observed below the eastern edge of the front but the drift station never moved quite far enough west to be caught in the southward transport of arctic surface water heat from the ocean was a major factor in ice melt and when the ice was over atlantic water it was the dominant factor the events that had the greatest impact on the ice were two outbreaks during which off ice winds blew the ice across warm ice edge ocean fronts once south of these fronts and over surface water as warm as 1 c the ice bottom melted at rates up to 100 kg m 2 d 1 the rapid changes in stratification associated with the outbreaks had a dramatic impact on the drag and heat transfer coefficients the drag coefficient relative to the square of the relative water velocity at 30 m ranged from 0 002 to 0 02 and averaged 0 006 the heat transfer coefficient relative to the friction velocity u and the mixed layer temperature elevation above freezing ranged from 0 0025 to 0 009 and averaged 0 0038 in agreement with the idea that stratification inhibits turbulent exchange the heat transfer coefficient decreased when stratification increased in fact the observed melt rates can be simulated well if molecular heat and salt transfer through a thin near surface laminar boundary layer are accounted for as well as transfer through the turbulent outer boundary layer also in agreement with turbulent boundary layer theory the drag coefficient decreased when stratification increased slightly above neutral however for the large increases in surface stratification the drag coefficient increased this was due to the generation of internal gravity waves by ice bottom roughness because the surface exchange coefficients are so sensitive to surface stratification which is in turn highly variable in the miz accurate simulations of ice motion and ice melt will require realistic estimates of stratification and a good understanding of the relation between the ice ocean interactions and upper ocean conditions

the effect of observed ice conditions on the drag coefficient in the summer east greenland sea marginal ice zone the summer east greenland sea marginal ice zone is a region characterized by extreme horizontal variations of surface roughness characteristics the surface drag coefficient is found to be correlated with these roughness characteristics in particular ice concentration and ice floe roughness and size the estimates of wind stress and wind speed yield neutral drag coefficients cdn with standard deviations of 2 3 0 8 10 3 for areas with less than 40 ice concentration and 4 0 1 1 10 3 for ice concentrations greater than 70 much of the variation in cdn for a given ice concentration is explained by differences in ice floe size and roughness very small concentrated rough floes that have been affected by wave action produce twice as much wind stress cdn 4 2 0 7 10 3 as relatively large flat floes cdn 2 1 0 6 10 3 and 4 times as much as typical open ocean for a given wind speed and stability the drag coefficients in this region are higher than other marginal ice zones probably a result of the presence of large amounts of multiyear ice floes that extend higher above the ocean surface and create more drag than first year floes

liquid release tests in unsaturated fractured welded tuffs ii numerical modeling abstract we have carried out a numerical modeling study in conjunction with the in situ liquid release experiment described in salve et al j hydrol 257 2001 the experiment site is a highly fractured welded tuff accessed from the exploratory studies facility an underground laboratory in the unsaturated zone at yucca mountain nevada the experiment examines the effect of the rock matrix on liquid flow and transport that occurs primarily through the fracture network the purpose of the modeling is to aid in experimental design predict experimental results and study the physical processes accompanying liquid flow through unsaturated fractured welded tuff the model uses cubic elements arranged in a regular three dimensional grid to represent a 24 m3 block of fractured tuff high permeability fracture elements located deterministically preserve the connectivity of the fracture network which is crucial to its ability to conduct fluid because element thickness is much greater than fracture aperture fracture elements are assigned properties of a fracture continuum rather than of an individual fracture the fracture network is constructed using fracture geometry data taken from a fracture map of the walls and ceiling of the alcove adjacent to the field test site the network is then refined using the results of air permeability tests model results suggest that it may not be sufficient to conceptualize the fractured tuff as consisting of high permeability fractures embedded in a low permeability matrix the need to include a secondary fracture network with distinct characteristics from the network of larger mapped fractures is demonstrated by comparison to the liquid flow observed in the field

ice edge eddies in the fram strait marginal ice zone five prominent ice edge eddies in fram strait on the scale of 30 to 40 kilometers were observed over deep water within 77 n to 79 n and 5 w to 3 e the use of remote sensing a satellite tracked buoy and in situ oceanographic measurements showed the presence of eddies with orbital speeds of 30 to 40 centimeters per second and lifetimes of at least 20 days ice ablation measurements made within one of these ice ocean eddies indicated that melting which proceeded at rates of 20 to 40 centimeters per day is an important process in determining the ice edge position these studies give new insight on the formation propagation and dissipation of ice edge eddies

on some possible interactions between internal waves and sea ice in the marginal ice zone the ice edges of the world ocean are generally the site at times when winds are blowing off the ice of regularly spaced surface bands of ice floes these bands have size scales of the order of 1 10 km and their long axes are oriented approximately normal to the wind direction available oceanic temperature and salinity data from the bering and greenland sea ice edge regions suggest that these ice bands are commonly underlain by a two layered density structure which is maintained by net melting along the ice edges linear internal wave theory is applied to these data to compute first mode interfacial wave phase speeds a simple analytical model is developed that demonstrates the feasibility of generation of such interfacial internal waves by the stress discontinuity due to off ice winds blowing over either a stationary or a moving ice edge it is qualitatively shown that the computed internal wave phase speeds and wavelengths are under many conditions compatible with the speeds and spacings of the surface ice bands this compatibility suggests in turn that coupling between internal waves and ice bands may commonly occur some possible implications of the generation and presence of these internal waves upon other ice edge processes such as air sea heat and momentum transfer are qualitatively discussed

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

avian remains from the early middle pleistocene of the so a basin central flores indonesia and their palaeoenvironmental significance the so a basin in central flores contains the earliest known evidence for hominins on this remote indonesian island with stone tools from this region dating back at least 1 0 ma at least 16 late early to early middle pleistocene terrestrial fossil localities record evidence for highly insular endemic faunas and proxy evidence for hominins the hominin presence in the so a basin raises many questions as to how when and from where hominins arrived on the island and key issues regarding their adaptation to this insular environment remain poorly understood here we provide palaeoenvironmental data based on avian remains recovered during recent systematic excavations of late early to early middle pleistocene deposits at mata menge and bo a leza in the so a basin at least six species of birds in five avian orders were recovered forming the oldest bird remains recovered from wallacea two species a swan cygnus sp and an eagle owl bubo sp no longer occur on flores the avian assemblage from mata menge and bo a leza described here is indicative of an open environment with a strong open freshwater component and nearby grasslands and with forests at a distance in that it differs from the late pleistocene limestone cave site of liang bua the find locality of homo floresiensis and is more similar to the early pleistocene homo erectus sites of the sangiran dome on java although little is known regarding the identity of the so a basin toolmakers the presence of an open savannah type environment in the late early to early middle pleistocene of flores may have facilitated their dispersal from the asian shelf into wallacea

archaeological implications of the geology and chronology of the soa basin flores indonesia the timing of arrival of early hominids in southeast asia has major implications for models of hominid evolution the majority of evidence for the earliest appearance of hominids in the region has previously come from java in western indonesia much of this evidence remains controversial owing to a poor understanding of the stratigraphic and chronologic relationships of the depositional units from which the material was derived before artifacts may be placed into their proper archaeological context the geologic history of archaeological sites must be thoroughly understood and deposits containing artifacts must be properly dated an extensive investigation has been undertaken on the island of flores in eastern indonesia to determine the depositional and chronological history of stratigraphic units within the soa basin many of the units are associated with stone artifacts attributed to homo erectus zircon fission track dates of tuffaceous deposits within this lacustrine basin now provide the most reliable data concerning the true time of arrival of homo erectus into southeast asia and indicate that these early hominids must have successfully begun colonizing eastern indonesia by ca 840 ka

new magnetochronology of late miocene mammal fauna ne tibetan plateau china mammal migration and paleoenvironments abstract lanzhou basin lies on the northeastern margin of the tibetan plateau in western china and is a rich source of oligocene miocene mammalian fossils obtaining precise age determinations for these fossils is important to address key questions concerning mammalian and environmental evolution in asia associated with stepwise tibetan plateau uplift here we report a new magnetostratigraphic record for the xingjiawan fluvio lacustrine section from the northwestern margin of lanzhou basin that can be correlated to the geomagnetic polarity timescale with two options the late miocene xingjiawan fauna is located either at the boundary between reversed polarity chron c4r 1r and normal polarity chron c4n 2n or at the boundary between subchrons c5r 1r and c5n 2n with an estimated age of at least 8 ma or perhaps as early as 11 ma both age estimations imply that the fossil stegodon in the lanzhou basin is the oldest known record of stegodon worldwide it predates the formerly oldest stegodon find from africa by at least one million years and perhaps by as many as four million years this provides new evidence for an asian origin of stegodon together with other faunal components a mixed woodland grassland setting existed in the lanzhou basin during the late miocene in contrast to its modern arid environment

ice ocean acoustic energy transfer ambient noise in the ice edge region abstract the ambient noise produced by large areas of ice floes such as the odden and the marginal ice zone was recorded and analysed a model based on the collision compression and shearing of floes driven by ocean swell was constructed this model allows the level and variance of the ambient noise to be predicted provided the conditions of the ice and the sea state are known the frequency spectrum of the ambient noise in the range 100 hz to 100 khz is explained in terms of acoustic propagation and absorption by sea water the probability distribution of ambient noise intensity obtained from a statistical analysis of collision frequencies is a form of k distribution and agrees with observations

geoarchaeological finds below liang bua flores indonesia a split level cave system for homo floresiensis we report on new geoarchaeological finds in a recently discovered cave chamber liang bawah cave under neath positioned below liang bua on the island of flores indonesia where the type specimen for homo floresiensis was recovered from late pleistocene sediment at the rear of liang bua a 23 m long shaft inclined at 60 leads to a lower chamber measuring 23 m x 24 m x 5 m high about half the size of liang bua stone artefacts and bones were found shallowly buried in rubble at the base of the shaft and around a 5 m high mud mound that fills the northwest sector of liang bawah we recovered 17 stone artefacts made from chert and volcanics and more than 220 well preserved bone elements belonging to endemic giant rats pigs primates small murid rodents bats and introduced species multi collector inductively coupled plasma mass spectrometer mc icpms analysis of uranium and thorium in carbonate coatings on four bones yielded ages of similar to 240 180 ka endemic giant rat femur similar to 110 60 ka unidentified phalanx similar to 33 23 ka pig skull fragment and similar to 7 3 ka giant rat femur which overlap with the similar to 95 to 17 ka occupation of liang bua by h floresiensis the similar to 33 23 ka age of the pig skull fragment indicates that sus sp may have dispersed into island southeast asia earlier than previously recognised the passageway at the rear of liang bawah and a currently buried front entrance represent two possible transport paths for cultural and faunal material to the cave chamber analysis of the geomorphic evolution of liang bawah shows that it may have been a late pleistocene depocentre for material transported from the occupation chamber of liang bua and a repository for human subsistence refuse or pit fall trap via the rear passage these physical attributes and the antiquity of the faunal remains found thus far indicate that liang bawah could contain an archive of the late pleistocene and potentially remains of h floresiensis c 2015 elsevier b v all rights reserved

high frequency ice floe collisions in the greenland sea during the 1984 marginal ice zone experiment during the 1984 marginal ice zone greenland sea experiment we carried out a field study on the relation between ice floe collisions and ocean swell the experiment consisted of the deployment on separate ice floes of three buoys each of which contained a compass and a set of triaxial accelerometers the floes had characteristic diameters of 100 m and thicknesses of 1 5 m from two major deployments of these buoys we gathered 16 days of data from the vertical accelerometer data we calculated the variation in the long period ocean swell with time from the horizontal accelerometers we determined the individual and mean collision properties examination of the individual collisions showed that two types of collisions occurred a short period spike that recurred with the period of the ocean swell and a longer period acceleration event that was uncorrelated with the swell we observed several hundred of the first type of collision in our data set but only eight of the second type the number of periodic collisions in a 9 min sample and the energy of these collisions were generally correlated with the ocean swell energy the ocean swell measured at the floes had root mean square rms amplitudes of 1 30 mm and periods between 10 and 18 s after removal of the ocean swell signal the collisions had characteristic horizontal displacements of 5 35 mm with rms velocities of the order of 1 mm s 1

acoustic properties of ice edge noise in the greenland sea a towed array experiment was performed by nrl in 1982 in the vicinity of the ice edge in the greenland sea the array was towed normal and parallel to and at ranges between 4 50 km from the ice edge the received data were beamformed to study the horizontal directionality of the noise the results indicated that a few localized hot spots with dimensions 5 km in the vicinity of the ice edge were the dominant noise sources these sources persisted for nearly 1 day the nominal separation between the hot spots was about 50 km the ice edge noise spectrum measured at these ranges decreased 11 12 db per octave with frequency between 100 500 hz as compared with the 6 db per octave spectrum of ambient sea noise possible sources are hypothesized in the context of known eddy wind and wave effects in the vicinity of the ice edge

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

the late quaternary palaeogeography of mammal evolution in the indonesian archipelago abstract the quaternary faunal evolution for the indonesian archipelago reflects the unique relationship of each island with se asian mainland the recent sub faunas of sundaland kalimantan sumatra java and bali preserved broad connections with the se asian mainland during the latest glacial they are all balanced and show many mainland components alternatively wallacea sulawesi and the lesser sunda islands has always been geographically isolated from the mainland wallacea faunas thus remain unbalanced they lack large carnivores and endemic a significant turnover arrives throughout the region with pronounced global sea level recessions around 0 8 ma during the transition from early pleistocene ep to the middle pleistocene mp by way of comparison the palaeontological records of japan and taiwan also preserve this turnover with ep mp recessions bringing east asian mainland immigrants on java the earliest late pliocene to early pleistocene satir fauna indicates island conditions java became connected to the se asian mainland towards the end of the early pleistocene global cooling brought open woodlands on java an environment evidently preferred by homo erectus in the ci saat fauna and trinil h k fauna as ep mp sea level recessions created a wide corridor across the sunda shelf siwaliks and the se asian mainland terrestrial mammals invaded as is seen in the kedung brubus fauna the succeeding ngandong fauna maintains an open woodland character but shows some endemism homo erectus and stegodon trigonocephalus among others can be distinguished on a subspecies level the late pleistocene marks the earliest known tropical rainforest and the corresponding punung fauna is of chinese affinity with pongo hylobates and elephas maximus homo sapiens probably arrives at this point as well the youngest fossil faunas known from java are the still poorly known cipeundeuy fauna ca 30 ka and the holocene faunas from wajak and sampung while sulawesi and flores remained isolated throughout the quaternary only a limited number of terrestrial vertebrates arrived by crossing sea barriers endemic island faunas with pygmy elephantoids and giant tortoises were present during the early pleistocene ep mp sea level recessions allowed large to medium sized elephantoids to replace the dwarf species around the same time homo erectus appears on the island of flores modern faunas eventually replaced the middle pleistocene island faunas but the time frame has yet to be pinpointed sulawesi presents a unique case its current fauna holds no walanae representatives apart from the phalangers which must have come from the east the ancestors of all other large sulawesi land vertebrates fossil and extant reached the island by crossing the sunda sea as the south sulawesi fauna was stable until the middle pleistocene this area must have constituted a separate palaeo island some localized developments can be observed e g shortening of the metapodials in celebochoerus increasing hypsodonty in stegodon

eastern arctic ambient noise on a drifting vertical array ambient noise in the eastern arctic was studied from april to september 2013 using a 22 element vertical hydrophone array as it drifted from near the north pole 89 23 n 62 35 w to north of fram strait 83 45 n 4 28 w the hydrophones recorded for 108 min day on six days per week with a sampling rate of 1953 125 hz after removal of data corrupted by non acoustic transients 19 days throughout the transit period were analyzed noise contributors identified include broadband and tonal ice noises bowhead whale calling seismic airgun surveys and earthquake t phases the bowhead whale or whales detected are believed to belong to the endangered spitsbergen population and were recorded when the array was as far north as 86 24 n median power spectral estimates and empirical probability density functions along the array transit show a change in the ambient noise levels corresponding to seismic survey airgun occurrence and received level at low frequencies and transient ice noises at high frequencies

the youngest stegodon remains in southeast asia from the late pleistocene archaeological site liang bua flores indonesia stegodon remains originating from late pleistocene layers of the archaeological cave site liang bua on the indonesian island of flores are described as a new endemic dwarf subspecies stegodon florensis insularis subsp nov some fossil stegodon fragments were found in association with the recently described remains of homo floresiensis but many occur in levels with high artefact concentrations the direct ancestor is the larger sized s florensis florensis known from early pleistocene and early middle pleistocene sites on flores the assemblage from liang bua comprises mostly dental and skeletal elements of juvenile individuals s f insularis is characterized by an advanced molar ridge formula and diminutive size on average the molars are 30 per cent smaller in linear dimensions as compared to the ancestral species hominin activities are likely to have played a role in the stegodon bone accumulation at liang bua

the role of shortwave radiation in the summer decay of a sea ice cover heat balance models of ice leads and the underlying water column were used to investigate the role of shortwave radiation in the summer decay of a sea ice cover because of the potential importance of positive feedback between decreasing ice concentration and increasing solar input to the ocean particular emphasis was given to the treatment of heat transfer and lateral melting in leads the rate of heat loss to floe edges was calculated from lead temperatures using an empirical boundary layer parameterization coefficients for this parameterization were obtained from field measurements in the dynamically active ice cover of the greenland sea during the 1984 marginal ice zone experiment and in the static ice of mould bay northwest territories field coefficients were found to be considerably larger than those previously obtained in the laboratory suggesting that heat transfer rates near floe edges were controlled more by winds and currents than by local density differences model studies of individual leads indicate that heat losses to the atmosphere cause lateral melt rates to asymptotically approach a constant value as lead size increases thus although very wide leads transmit considerable energy to the underlying ocean they have relatively little effect on lateral melting other results provide information on the relative importance of horizontal heat transfer rates ice thickness floe perimeter atmospheric forcing and oceanic heat flux in general the calculations indicate that much of the shortwave radiation entering the ocean is absorbed below the ice where it contributes to bottom ablation rather than lateral melting this suggests that previous work has seriously overestimated the magnitude of the feedback between ice concentration and incident shortwave radiation

floe pair interaction event rates in the marginal ice zone data from an accelerometer package are used to estimate the rates at which interaction events occur between adjacent ice floes in the marginal ice zone observations suggest that the events are principally the result of a modified collision process where brash ice partially filling the gap between two floes acts as an intermediary in the transfer of momentum from one to the other a model is presented from which the rate at which these interactions occur can be predicted comparison of the rates estimated from the data with those predicted by the model shows there to be some agreement although there is considerable room for improvement the predicted event rate depends strongly on the ratio of the root mean square wave height to the amount of open water between pairs of floes the form of this dependence offers an explanation for grouping of events a feature that may be readily observed in many extracts of data

underwater ambient noise on the chukchi sea continental slope from 2006 2009 from september 2006 to june 2009 an autonomous acoustic recorder measured ambient noise north of barrow alaska on the continental slope at 235 m depth between the chukchi and beaufort seas mean monthly spectrum levels selected to exclude impulsive events show that months with open water had the highest noise levels 80 83 db re 1 pa2 hz at 20 50 hz months with ice coverage had lower spectral levels 70 db at 50 hz and months with both ice cover and low wind speeds had the lowest noise levels 65 db at 50 hz during ice covered periods in winter spring there was significant transient energy between 10 and 100 hz from ice fracture events during ice covered periods in late spring there were significantly fewer transient events ambient noise increased with wind speed by 1 db m s for relatively open water 0 25 ice cover and by 0 5 db m s for nearly complete ice cover 75 in september and early october for all years mean noise levels were elevated by 2 8 db due to the presence of seismic surveys in the chukchi and beaufort seas

laboratory measurement of capillary pressure saturation relationships in a rock fracture a laboratory technique has been developed to measure the hysteretic relationship between capillary pressure and fluid saturation for a rough walled rock fracture under different states of normal stress the technique incorporates a loading system and a uniquely designed capillary barrier to the nonwetting phase which allows for fracture closure and provides excellent hydraulic connection of the wetting phase in the fracture with external pressure control the method is applied to a single rough walled fracture in limestone using oil and water as the nonwetting and wetting phase respectively the measured capillary pressure curves were found to be well represented by a brooks corey porous media capillary pressure function a distinct entry pressure giving rise to initial nonwetting phase invasion was observed in each test it was found that the inferred aperture distributions became less skewed with increased normal load these aperture distributions were inferred using one of three conceptual models presented for nonwetting phase invasion of a rough walled fracture under conditions of main drainage

environmental correlates of arctic ice edge noise temporal variations of low frequency broadband ambient noise measured in early summer under drifting ice floes of the marginal ice zone miz are cross correlated with local environmental forces and ice field descriptors surface gravity wave forcing is the primary correlate of the noise its interaction with ice floes generates sound most likely via flexural floe failure and unloading motion within a few kilometers of the ice edge ice concentration is also well correlated with the noise most likely parametrically that is as ice concentration increases so does the density of potential sound sources in the ice field ice stress ice moment and wind stress magnitude while highly correlated with low frequency noise in the fully ice covered arctic are poor correlates in the miz lateral melt rate as a surrogate for thermally induced ice stress is also poorly correlated with low frequency miz noise when surface wave forcing is weak about 1 2 the time in this experiment episodes of high noise a

on thermohydrologic conditions near high level nuclear wastes emplaced in partially saturated fractured tuff 2 effective continuum approximation this paper presents an effective continuum approximation for modeling of fluid and heat flow in fractured porous media the approximation is based on the thermohydrologic behavior observed in detailed simulations with explicit consideration of fracture effects see the companion paper part 1 the crucial concept in the development of an effective continuum approximation is the notion of local thermodynamic equilibrium between rock matrix and fractures where applicable it provides a substantial simplification of the description of fluid and heat flow in fractured porous media we derive formulas for effective continuum characteristic curves relative permeabilities and capillary pressures in terms of the properties of fracture and matrix continua respectively numerical simulations demonstrate that under favorable conditions the effective continuum approximation closely matches predictions obtained from an explicit modeling of fracture effects it is also demonstrated that the approximation breaks down under unfavorable conditions very tight rock matrix a simple criterion for the applicability of an effective continuum approximation is derived from consideration of diffusive processes a quantitative evaluation shows the criterion to be consistent with results of our numerical simulations

on thermohydrologic conditions near high level nuclear wastes emplaced in partially saturated fractured tuff 1 simulation studies with explicit consideration of fracture effects we have performed modeling studies on the simultaneous transport of heat liquid water vapor and air in partially saturated fractured porous rock formation parameters were chosen as representative of the potential nuclear waste repository site in the topopah spring unit of the yucca mountain tuffs the presence of fractures makes the transport problem very complex both in terms of flow geometry and physics the numerical simulator used for our flow calculations takes into account most of the physical effects believed to be important in multiphase fluid and heat flow it has provisions for handling the extreme nonlinearities that arise in phase transitions component disappearances and capillary discontinuities at fracture faces we model a region around an infinite linear string of nuclear waste canisters taking into account both the discrete fractures and the porous matrix thermohydrologic conditions in the vicinity of the waste packages are found to depend strongly on relative permeability and capillary pressure characteristics of the fractures which are unknown at the present time if liquid held on the rough walls of drained fractures is assumed to be mobile strong heat pipe effects are predicted under these conditions the host rock will remain in two phase conditions right up to the emplacement hole and formation temperatures will peak near 100 c if it is assumed that liquid cannot move along drained fractures the region surrounding the waste packages is predicted to dry up and formation temperatures will rise beyond 200 c a substantial fraction of waste heat can be removed if emplacement holes are left open and ventilated as opposed to backfilled and sealed emplacement conditions comparing our model predictions with observations from in situ heater experiments reported by zimmerman and coworkers some intriguing similarities are noted however for a quantitative evaluation additional carefully controlled laboratory and field experiments will be needed