major pathways of atlantic water in the northern north atlantic and nordic seas toward arctic 1 the major pathways of near surface atlantic water in the northern north atlantic and nordic seas are identified as current speeds above 30 cm s using 1014 lagrangian drifters combined with previously published hydrography the inflow over the scotland greenland ridge and establishment of the two branch norwegian atlantic current nwac are described in light of the circulation in the northern north atlantic the western branch of the nwac appears as a jet in the polar front topographically guided from the iceland faroe front through the nordic seas toward fram strait the eastern branch starts as a shelf edge current above the irish scottish continental shelf and after passing through the faroe shetland channel it continues northward along the norwegian shelf edge toward the arctic with a branch bifurcating into the barents sea the nwac appears to maintain its two branch structure throughout the nordic seas with the atlantic water confined to a 200 600 km wide wedge

influences of multiple layers of air temperature differences on tidal forces and tectonic stress before during and after the jiujiang earthquake abstract using the air temperature data of the national center for environmental prediction ncep we compared multiple layers of air temperature differences before during and after the jiujiang earthquake and explored its relationship with the additive tectonic stress caused by celestial tide generating force atsctf the earthquake occurred at the 1 of 4 high phases of atsctf while the temperature rise came from land surface to high sky it indicated that the tide force could trigger an earthquake when the tectonic stress was in critical status and the air temperature rise reflected the terra stress change modulated under the tidal force during the shock period of atsctf the distribution of air temperature changes both near land surfaces and upper multi layers along the active fault zones showed a tectonic disturbance pattern of calm before earthquake rise during earthquake calm after earthquake as well as a heat distribution pattern of the surface air warmed by land uplifted by heat flux cooled and dissipated in the sky the pattern of changes obeyed the rule of thermal rise of rocks broken under stress loading and the principle of atmospheric thermal dynamic diffusion in vertical we argued that an earthquake may also be a reason for air temperature differences rather than a simple weather process at the same time the rise of air temperature was synchronized with the atsctf fluctuant which showed that tidal force had a particular indicative significance for the identification of temperature anomaly on seismic faults because of the mechanical characteristics of the study of earthquake thermal anomalies it could help to identify the earthquake thermal anomalies and the climatic thermal anomalies and provided a clear time indication for the choice of the background temperature in the seismic thermal anomaly recognition

residual flows in cook strait a large tidally dominated strait abstractflows at subtidal frequencies are resolved from 20 months of current observations at multiple sites across the narrows of cook strait new zealand the substantial tidal flows spring tides 3 m s 1 are challenging to measure with moored adcps along strait residual flows are on the order of 0 05 0 1 m s 1 but there were differences across the strait and also through the annual cycle the calculated net residual transport is 0 25 sverdrups sv 1 sv 106 m3 s 1 i e negative sign implies to the south from tasman sea to pacific ocean this is smaller by a factor of 2 3 than that estimated from previous sparse current measurements crucially however these new data also suggest that over the austral summer autumn period there is persistent residual flow northward on the western side of the strait so that the summer autumn net 0 15 sv flow can be separated into 0 065 sv westside and 0 22 sv eastside flow this western northward flow had a seasonal bias appearing only in the summer

north atlantic nordic seas exchanges abstract the northeastern part of the north atlantic is unique in the sense that it is much warmer in the surface than other ocean areas at similar latitudes the main reason for this is the large northward transport of heat that extends to high latitudes and crosses the greenland scotland ridge to enter the nordic seas and the arctic there the warm atlantic water is converted to colder water masses that return southwards over the ridge partly as surface outflows and partly as overflows through the deep passages across the ridge in this paper the state of knowledge on the exchanges especially across the eastern part of the greenland scotland ridge is reviewed based on results from the ices nansen north atlantic norwegian sea exchanges project from the nordic woce project and from other sources the accumulated evidence allows us to describe the exchanges in fair detail the origins of the waters the patterns of their flow towards and over the ridge and their ultimate fate there is also increasing information on temporal variations of the exchanges although dynamical changes are still not well understood quantitative estimates for the volume transport of most of the overflow branches seem reasonably well established and transport measurements of the atlantic inflows to the nordic seas are approaching acceptable levels of confidence which allows preliminary budgets to be presented the deep overflows are driven by pressure gradients set up by the formation of deep and intermediate water the dominance of deep overflows over surface outflows in the water budget argues that this thermohaline forcing also dominates over direct wind stress and estuarine forcing in driving the atlantic water inflow across the greenland scotland ridge while wind stress seems to influence the characteristics and distribution of the atlantic water north of the ridge

exhaustion and steady state models for predicting landslide hazards in the canadian rocky mountains abstract the temporal distribution of landslides can be evaluated by steady state and exhaustion models the probability of landsliding remains constant through time in the steady state model but the probability decreases in the exhaustion model as more slopes fail rock sliding down bedding surfaces on overdip slopes exhausts hazardous sites to leave stable dipslope landforms in kananaskis country in the canadian rocky mountains the distribution of rock slides in this area can be better explained by the exhaustion model than by the steady state model

directly measured mid depth circulation in the northeastern north atlantic ocean the circulation of water masses in the northeastern north atlantic ocean has a strong influence on global climate owing to the northward transport of warm subtropical water to high latitudes but the ocean circulation at depths below the reach of satellite observations is difficult to measure and only recently have comprehensive direct observations of whole ocean basins been possible here we present quantitative maps of the absolute velocities at two levels in the northeastern north atlantic as obtained from acoustically tracked floats we find that most of the mean flow transported northward by the gulf stream system at the thermocline level about 600 m depth remains within the subpolar region and only relatively little enters the rockall trough or the nordic seas contrary to previous work our data indicate that warm saline water from the mediterranean sea reaches the high latitudes through a combination of narrow slope currents and mixing processes at both depths under investigation currents cross the mid atlantic ridge preferentially over deep gaps in the ridge demonstrating that sea floor topography can constrain even upper ocean circulation patterns

assessing the potential of thermal infrared satellite surveys for monitoring seismically active areas the case of kocaeli izmit earthquake august 17 1999 abstract space time anomalies of earth s emitted radiation in the thermal infrared spectral range tir measured from satellite months to weeks before the occurrence of earthquakes have been interpreted by several authors as pre seismic signals the claimed connection of tir emission with seismic activity has been considered up to now with some caution by the scientific community mainly for the insufficiency of the validation data sets and the scarce importance attached by those authors to other causes e g meteorological that rather than seismic activity could be responsible for the observed tir signal fluctuations in this paper a robust satellite data analysis technique is described which permits us to identify anomalous space time tir signal transients even in very variable observational satellite view angle land topography and coverage etc and natural e g meteorological conditions a statistically well founded definition of tir anomaly is given and proposed as a suitable tool for satellite tir surveys in seismically active regions eight years of meteosat tir observations have been analyzed in order to characterize the tir signal behavior at each specific observation time and location space time tir signal transients have then been analyzed both in the presence validation and in the absence of confutation seismic events looking for possible space time relationships the devastating earthquake which occurred in turkey izmit august 17 m s 7 8 in 1999 has been considered as a test case for validation relatively unperturbed periods no earthquakes with m 5 were taken for confutation purposes quite intense s n 3 5 and rare spatially extensive and time persistent tir signal transients were identified appearing eight days before the izmit main shock in greece moving to turkey on august 13 and disappearing moving back to greece some days after possible implications of such results together with present limitations of the proposed technique will also be discussed in the light of the improved performances expected by its extension to other existing or future satellite packages

interannual thermohaline changes in the northern north atlantic 1991 1996 abstract in the period 1991 1996 the woce hydrographic section a1e ar7e between greenland and ireland was repeated five times the observed thermohaline changes altered the baroclinic structure along the eastern margin of the subpolar gyre significantly between june 1995 and august 1996 an overall increase of the temperature and thickness and a decrease of the density of the subpolar mode water spmw layer were observed accompanied by an increase of its salinity east of the reykjanes ridge and a decrease of its salinity in the irminger sea the changes were most pronounced in the iceland basin where the subarctic front retreated westwards coinciding with a strong weakening of the westerlies as determined by the north atlantic oscillation they are related to a local reduction of the ekman upwelling and the ocean to atmosphere heat flux on the one hand and to the advection of anomalies from the subtropics on the other hand the eastward spreading of the different labrador sea water lsw vintages led to a corresponding cooling of the lsw in the irminger sea and in the iceland basin in the period 1991 1996 the renewal of the lsw in the rockall trough occurred more sporadically indicating that the north atlantic current nac impedes the southward spreading of lsw in the eastern atlantic the changes in 1996 seem to have also counteracted this spreading

near surface circulation in the northern north atlantic as inferred from lagrangian drifters variability from the mesoscale to interannual 1 the near surface circulation of the nordic seas is basically cyclonic and consists of jets and recirculation cells which are tightly linked to the bottom topography variable forcing by the large scale rotation of the wind leads to a modulation in the strength of the gyres and their interconnecting jets this is seen in drifter and altimeter data currents are stronger during winter and during phases of high north atlantic oscillation index the exchanges between the north atlantic and the nordic seas do not seem to be directly affected by this variable forcing the narrow boundary currents and the intergyre jets are subject to instability causing mesoscale current fluctuations which contribute to the stirring and mixing of polar and atlantic water masses

uncertainty of north atlantic current observations from altimetry floats moorings and xbt abstract large scale geostrophic flow across an oceanographic section can be computed from in situ density profiles and satellite borne sea level anomaly measurements at the section endpoints here uncertainties are estimated and compared for observations that span the north atlantic current out of multi year mooring records from two sites porcupine abyssal plain and central irminger sea 16 months from the 2002 2005 period are available that have sufficient data coverage to observe this current transport and uncertainty estimates from these moorings are compared to results from argo floats and expendable bathythermographs the latter have longer data sets and provide decadal time series with semiannual resolution in time typical uncertainties which take sensor errors and sub sampling the eddy field into account are below 2 sv of volume transport for the mooring and float based estimates and just below 3 sv for the expendable bathythermographs peak to peak variability occurs on decadal time scales and is about 11 sv well above the observational uncertainty we can therefore have confidence that the observed signal reflects true changes in the ocean the time series is further extended to 25 years duration using solely the altimetry data by proxy the aim of this study is to add value to such time series by understanding and quantifying the uncertainties and consistency between methods the methodology is applicable at other locations as well

lunar solar periodicities of large earthquakes in southern california large earthquakes in southern california with epicentres between 33 and 36 n have statistically significant 12 hourly lunar fortnightly and 18 6 yr periodicities smaller earthquakes in the same region do not display these periodicities a search for tidal effects associated with these periodicities shows that large earthquakes have significant correlations with the times and orientations of daily semi daily tidal stresses while the lunar fornightly term is associated with the ocean tides along the southern californian coast

the north atlantic current based on trajectories of satellite tracked buoys and hydrographic sections both dietrich s and worthington s schemes of the north atlantic current are reconsidered ninety satellite tracked buoys have been analyzed in order to distinguish between these schemes neither could be confirmed the north atlantic current appears as a superposition of a broad west wind drift and a frontal jet in the western part of the north atlantic north of 40 n which becomes independent from the subtropical gyre neither a permanent branching suggested by dietrich nor a confinement of the subpolar gyre to the east of newfoundland per worthington can be found the north atlantic current extends over the entire north atlantic carrying more than 20 sverdrups sv toward the north this northward transport is mainly due to the northward flow around flemish cap and a sudden turn of the north atlantic current east of the mid atlantic ridge the buoy tracks have been used to determine speed and direction in the upper layers 100 m we combine these results with hydrographic data in order to obtain an estimate of the mass transport transport across the mid atlantic ridge is based on recent sections fahrbach et al 1985 while transport in the northeastern north atlantic has been derived from the erika dan sections at 53 5 n and 59 5 n according to these two sections the return flow occurs mainly below 1000 m after water mass conversion in the northern areas the results imply that about 7 sv of atlantic water are transformed into deep water in the area between 53 5 n and 60 n

near surface circulation of the nordic seas as measured by lagrangian drifters in the period june 1991 to august 1993 107 argos tracked drifters drogued to 15 m depth were released in the nordic seas or greenland iceland and norwegian seas the drifter movements revealed the strong and spatially confined current systems along the surface salinity fronts of the iceland faroe frontal zone and of the norwegian coast and along the continental margins and their extensions to the barents sea and spitsbergen the norwegian atlantic current is composed of three distinct streams two continental margin and one coastal branches which join into one single swift mean current west of the lofoten and vesteralen islands where the strongest measured currents are in excess of 110 cm s 1 in addition to the general cyclonic gyre circulation in the nordic seas the drifters indicate smaller cyclonic circulation patterns in all the major subbasins i e the iceland plateau the norwegian the lofoten and the greenland basins no surface signature of the east icelandic current is disclosed by the drifters interpolated and low pass filtered position data were used to construct maps of 15 m depth ensemble mean velocity velocity variability and residence time vigorous eddy fields are dominant in the strong currents and in the lofoten basin eulerian correlations indicate that they tend to propagate to the west in contrast the iceland plateau appears quiescent both in the mean and eddy velocities single particle diffusivities are computed and are found to be in the range 1 7 107 cm2 s 1 the corresponding lagrangian timescale and space scale are 1 3 days and 10 40 km respectively these lagrangian drifter measurements compose the first basin scale accurate near surface velocity data set of the nordic seas

the physical oceanographic conditions along the mid atlantic ridge north of the azores in june july 2004 abstract during the mar eco expedition in june and july 2004 39 deep ctd stations were occupied with uneven spacing along the mid atlantic ridge mar between 41 n and 61 n the ctd stations coincided with the biological sampling stations and thus gave a detailed vertical description of the water properties at these locations many different water masses were identified however using the predominant water mass in the upper 500 m four different hydrographic regions were identified stations in the vicinity of the reykjanes ridge north of 57 n were dominated by modified north atlantic water mnaw stations south of 56 30 n and north of the sub polar front spf were dominated by sub arctic intermediate water saiw ctd data combined with along track continuous surface temperature and salinity measurements satellite sea level anomaly data and sea surface temperature sst and along track current data adcp data showed that the position of the spf was at about 52 n at the southern edge of the charlie gibbs fracture zone cgfz south of the spf a frontal region with both north atlantic central water nacw and saiw present was observed and south of about 50 n the predominant water mass in the upper 500 m was nacw a ship mounted rdi 75 khz adcp was operated during the cruise and yielded high quality data during the first leg the currents showed large variations over short distances and were strongly affected by topography the adcp data was be used to describe the mesoscale eddy field along the mar and to detect three jets in the north atlantic current nac data from a current meter mooring left for 10 months after the cruise at a seamount just to the south of cgfz showed the dominance of the tidal currents in the area typical spring tidal currents were about 0 15 m s 1 and the mean flow an order of magnitude smaller about 0 03 m s 1 a short term mooring on a seamount farther south showed tidal currents of 0 3 m s 1 binned 8 day 4 km sst satellite imagery were collected and processed for 2004 the sst data were analysed and showed characteristic frontal structures in the mar eco region

north atlantic surface circulation during the 1990 s observed with satellite tracked drifters a new compilation of lagrangian velocity observations describes the state of the north atlantic surface circulation during the 1990s gridded fields of velocity and eddy kinetic energy eke are constructed from trajectories of more than 1500 15 m drogued satellite tracked surface drifters in service between january 1990 and december 1999 this time period overlaps a coordinated field study of circulation and variability in the north atlantic completed between 1996 2000 as part of the world ocean circulation experiment we describe the construction of a self consistent drifter climatology present decadal mean quasi eulerian velocity and eke fields computed on a 1 grid and compare these results with contemporary satellite measurements detailed discussion of the inferred surface circulation is focused on three regions 1 the gulf stream and north atlantic current 2 the labrador sea and subpolar gyre and 3 the caribbean sea the swiftest drifter motions were found in the equatorial region and along the tropical subtropical and subpolar western boundaries the maximum instantaneous speed determined from a single quality controlled and filtered drifter observation was 273 cm s 1 in the gulf stream southeast of cape cod the highest eke value in the north atlantic 2790 cm2 s 2 was found in the gulf stream just downstream of the new england seamounts over most of the atlantic basin drifter derived eke values were found to be o 100 cm2 s 2 higher than corresponding values derived from satellite altimetry in the labrador sea a region of sharply elevated eke appears to be geographically related to the localized ejection of drifters and by extension mass and kinetic energy from the energetic west greenland current between 60 and 62 n when compared to drifter measurements made in the late 1970s our results suggest but do not statistically confirm an enhancement and slight northward shift of the zonal gulf stream extension such a shift is consistent in sign with expectations based on observed interdecadal variations in wind stress and subtropical gyre potential energy associated with the north atlantic oscillation

north atlantic ocean surface currents 1 close to 1800 surface drifters are used to investigate the 15 m circulation of the north atlantic ocean the data are used to describe structures of the average eulerian circulation and of the associated eddy variability the data resolve scales on the order of 50 km which have hitherto not been systematically described in particular near shelf breaks and near the most intense currents the gulf stream the north atlantic current nac and the frontal currents of the subpolar gyre this reveals a complex series of quasi permanent eddies meanders and recirculation patterns gulf stream intensity is portrayed as changing abruptly near 54 w east of which it is identified as two current branches centered near 39 and 41 5 n the northern one connecting more directly with the nac and the southern one with the recirculation gyre and the azores current ac many features of the currents are controlled by topography in particular currents are often intensified near shelf breaks or parallel to ridges in the subpolar gyre however the largest northward branch of the nac in the icelandic basin is located near the deepest bathymetry not near steep bathymetry other currents in particular in the subtropical gyre are less clearly related to topography for instance the ac is featured as a zonal eastward current extending far west of the mid atlantic ridge mar to at least 55 w and possibly 63 w in the interior and away from topographic features the eddy kinetic energy eke is the largest where the mean currents are the largest in the subpolar gyre there are striking differences in eke between southward flowing currents the labrador and east greenland current and the northward flowing currents west greenland current and branches of the nac which have higher eke the areas of weakest variability are located in the southwest part of the subpolar gyre northeast of iceland and in the eastern atlantic south of 45 n the ac eddies and the mesoscales south of the canary islands transect this eastern eddy desert drifter trajectories are used as realizations of lagrangian particles in the vicinity of current cores these illustrate the variety of paths or connections between different current systems and demonstrate cross stream dispersions

exploring land surface temperature earthquake precursors a focus on the gujarat india earthquake of 2001 1 there are many reports of land surface temperature lst anomalies appearing prior to large earthquakes a number of methods have been applied in hindcast mode to identify these anomalies using infrared datasets collected from earth orbiting remote sensing satellites here we examine three such methods and apply them to six years 2001 2006 of modis lst data collected over the region of the 2001 gujarat india earthquake which previous studies have identified as a site exhibiting possible pre seismic and post seismic thermal anomalies methods 1 and 2 use an lst differencing technique while method 3 the robust satellite technique rst has been developed specifically for the identification of thermal anomalies within spatio temporal datasets in relation to the gujarat earthquake results from methods 1 and 2 lst differencing indicate that changes previously reported to be potential precursory thermal anomalies appear instead to occur within the range of normal thermal variability results obtained with method 3 rst do appear to show significant anomalies around the time of the earthquake but we find these to be related to positive biases caused by the presence of modis lst data gaps attributable to cloud cover and mosaicing of neighboring orbits of data currently therefore we find no convincing evidence of lst precursors to the 2001 gujarat earthquake and urge care in the use of approaches aimed at identifying such seismic thermal anomalies

currents and mixing in the irminger sea and in the iceland basin on the basis of a hydrographic section from the faeroe islands toward greenland along 62m 0n and the deployment of about 20 satellite tracked buoys it is shown that the irminger current branches at the reykjanes ridge its total transport amounts to 17 18 sv the eastern branch of the irminger current 8 sv turns east and enters the norwegian sea both through the faeroe shetland channel 3 sv and by passing northeast of the faeroe islands maximum speeds of 70 cm s 1 are reached at the outer edge of the east and west greenland current very intensive mixing is observed between the four water masses that flow into the irminger basin stirring by eddies plays a dominant role for strong interleaving subsequent salt fingering and double diffusive layering conditions for these processes are optimal nearly everywhere in the irminger sea

northern north atlantic sea surface height and ocean heat content variability 1 the evolution of nearly 20 years of altimetric sea surface height ssh is investigated to understand its association with decadal to multidecadal variability of the north atlantic heat content altimetric ssh is dominated by an increase of about 14 cm in the labrador and irminger seas from 1993 to 2011 while the opposite has occurred over the gulf stream region over the same time period during the altimeter period the observed 0 700 m ocean heat content ohc in the subpolar gyre mirrors the increased ssh by its dominantly positive trend over a longer period 1955 2011 fluctuations in the subpolar ohc reflect atlantic multidecadal variability amv and can be attributed to advection driven by the wind stress gyre mode bringing more subtropical waters into the subpolar gyre the extended subpolar warming evident in ssh and ohc during the altimeter period represents transition of the amv from cold to warm phase in addition to the dominant trend the first empirical orthogonal function ssh time series shows an abrupt change 2009 2010 reaching a new minimum in 2010 the change coincides with the change in the meridional overturning circulation at 26 5 n as observed by the rapid rapid climate change project and with extreme behavior of the wind stress gyre mode and of atmospheric blocking while the general relationship between northern warming and atlantic meridional overturning circulation amoc volume transport remains undetermined the meridional heat and salt transport carried by amoc s arteries are rich with decade to century timescale variability

direct measurements of the mean flow and eddy kinetic energy structure of the upper ocean circulation in the ne atlantic 1 the upper ocean circulation in the sub polar northeast atlantic has been a challenge to quantify due to strong and variable wind forcing and strong and variable deep currents that lead to large uncertainties in the use of the standard dynamical method since 1999 we have been operating an acoustical doppler current profiler on a container vessel that operates between denmark and greenland to repeatedly sample upper ocean currents across the northeast atlantic individual transects exhibit a highly energetic mesoscale variability but ensemble averaging of the sections reveals a striking organization of the mean field along the reykjanes ridge a distinct southward flow along its eastern slope and two clearly defined peaks with seasonal modulation flowing to the north along its western slope higher values of eddy kinetic energy about 150 600 cm2 s 2 are observed along the transect o 1 5 greater than surface drifter estimates

precursors for rock fracturing and failure part i irr image abnormalities abstract there are many precursors including the abnormality of infrared radiation irr for rock fracturing and failure as the comprehensive effect of rock thermoelasticity and rock friction the study of the irr abnormality of loaded rock as one of the important issues of remote sensing rock mechanics rsrm is facilitated by the fast development of ir remote sensing imaging technology in view of energy input and consumption by the loading system comprised of loader rock and air the mechanism of surface irr from loaded rock is studied the concepts that surface irr is the comprehensive effect of a series of physical mechanical processes inside loaded rock and that the thermoelastic effect and the frictional thermal effect are two of the main mechanisms are presented here based on retrospective investigation of the fundamental experiments on rsrm during the past decade it is concluded that there are two kinds of irr abnormality as precursors of rock fracturing and failure irr image abnormality and irr temperature curve abnormality the spatial temporal evolution of abnormal surface irr images of loaded rock in a condition of uniaxial stress compressive shear biaxial stress frictional slide and impact is systematically analyzed the fact that large irr can occur in the fracturing center of compressively loaded and shearing fractured strong and brittle rock is also revealed finally the relation between rock stress and irr temperature are studied based on thermomechanical coupling theory for solid materials it is concluded that irr image abnormalities are important precursors for rock fracturing and meaningful for the forecast of rockbursts and tectonic earthquakes

labrador sea boundary currents and the fate of the irminger sea water abstract the general circulation of the labrador sea is studied with a dataset of 53 surface drifters drogued at 15 m and several hydrographic sections done in may 1997 surface drifters indicate three distinct speed regimes fast boundary currents a slower crossover from greenland to labrador and a slow eddy dominated flow in the basin interior mean eulerian velocity maps show several recirculation cells located offshore of the main currents in addition to the cyclonic circulation of the labrador sea above the northern slope of the basin the surface drifters have two preferential paths one between the 1000 m and 2000 m isobaths and the other close to the 3000 m isobath the vertical shear estimated from ctd data supports the presence of two distinct currents around the basin one current more baroclinic flows between the 1000 m and 2000 m isobaths the other one more barotropic flows above the lower continental slope the irminger sea water carried by the boundary currents is altered as it tr

on the spatial structure and temporal variability of poleward transport between scotland and greenland 1 the flow north of warm subtropical water though the northeastern atlantic is known to have many pathways that vary over time here we use a combination of upper ocean current measurements betwe