jurassic radiolarites in a tethyan continental margin subbetic southern spain palaeobathymetric and biostratigraphic considerations abstract a region of the pelagic subbetic basin within the southern iberian continental margin is studied in lithostratigraphical and biostratigraphical detail jurassic radiolarites jarropa radiolarite formation bathonian oxfordian interbedded with shallow water marine limestones have been recognized underlying the radiolarites camarena formation bajocian are oolitic limestones showing shallowing upward cycles with karstic surfaces on the top corresponding to deposition on an isolated carbonate platform on volcanic edifices the milanos formation upper kimmeridgian tithonian overlying the radiolarites contains calciclastic strata with hummocky cross stratification which indicate outer carbonate ramp deposition in the jarropa radiolarite formation some calcisiltite strata with hummocky cross stratification have been found the bathymetry of the subbetic jurassic pelagic sediments including the radiolarites is considered as moderate or shallow in depth we suggest that the pelagic character of the jurassic sediments in this margin and their equivalents in other alpine domains is a consequence of distance from the continent beyond the pericontinental platform but not necessarily of depositional depth

meteoric water participation in the genesis of jurassic cherts in the subbetic of southern spain a significant indicator of penecontemporaneous emergence abstract in the eastern sector of the betic cordillera outcrops of the internal subbetic display chert lenses in the upper parts of oolitic limestones camarena formation mid jurassic the stratigraphy indicates a sedimentary record related to synsedimentary tectonics tilting the sediments were deposited in different tectonic blocks at varying depths the camarena formation is mainly made up of shallow platform oolitic limestones and was deposited on a pelagic swell a shallow isolated platform that developed far from continental areas the chert lenses appear in those stratigraphic units deposited in the lowermost sunken fault blocks which display biosiliceous facies overlying the camarena formation the chert mainly consists of megaquartz formed by replacement of the oolitic host rocks without an opaline precursor the part of the host that has been most affected by the silicification is the carbonate cement the petrological features indicate a slow replacement from solutions which were poor in silica and cations comparing the textures and fabric of the cherts and their host rocks it is deduced that the silicification took place after compaction cementation fracturing and local dissolution of the oolitic limestones the stable isotopic data 18o 13c obtained from the chert oolitic host rock and overlain biosiliceous rocks display significant differences the host rocks camarena formation and overlying biosiliceous rocks have isotopic signatures that are typical of marine environments or shallow marine diagenesis however the chert isotopic values are interpreted to suggest meteoric water participation in the silicification process the timing of the chertification is suggested to have been between the bathonian beginning of the deposition of the biosiliceous source facies and the aptian first appearance of this chert as clasts in breccia beds in palaeogeographic terms the optimum timing would have been during emergence i e between the bathonian and tithonian the exposed areas could have acted as recharge areas of meteoric water into the regional aquifer system the involvement of meteoric water in the silicification processes gives new support to the hypothesis that pelagic swells were subjected to episodic exposure

sea level changes an integrated approach sea level changes an integrated approach in october 1985 sepm sponsored a four day conference entitled sea level changes an integrated approach the purpose of the conference was to provide a forum for an interdisciplinary exchange of ideas on sea level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues the conference was successful in bringing together scientists from industry academia and government representing all of the major geosciences disciplines presentations of many new papers plus significant releases of data that were previously held proprietary provided fertile ground for discussion this much cited volume represents the best of the material presented at the conference includes the early vail chart

winter currents and hydrographic conditions on the northern central bering sea shelf current observations obtained from the northern bering shelf region in winter 1984 1985 indicate that midwinter circulation patterns differed from those during the rest of the year annual mean circulation in this region is dominated by vigorous northward currents from 10 cm s in shpanberg strait to more than 50 cm s in bering strait these northward currents are accompanied by a weak northwestward coastal flow south of st lawrence island in february april 1985 however flow was weakly 0 5 cm s southward through shpanberg strait and southeastward south of st lawrence island while remaining northward through anadyr and bering straits comparison with current data obtained from previous years suggests that midwinter reversal of flow in shpanberg strait is a recurrent winter feature it generally occurs at about the same time that the winter ice cover undergoes its major advance and it is associated with strong northerly winds northward flow through anadyr strait persists conversely through the winter and is the northward extension of a western intensified northward flow over the bering shelf its source is bering sea water farther south rather than water from the northern central shelf the resultant trapping of shelf water on the northern central shelf coupled with intensive regional ice formation during the same period as the flow reversal led in 1985 to significant about 1 5 brine enrichment this salinity increase agrees qualitatively with historical data which suggest that the northern central bering shelf is the site both of sluggish winter circulation and of elevated salinities due to brine enrichment from ice formation

multi event analysis of the westerly greenland tip jet based upon 45 winters in era 40 the westerly greenland tip jet is an intense narrow and intermittent wind phenomenon located southeast of cape farewell that occurs frequently during the winter season using the era 40 reanalysis dataset a catalogue of 586 objectively detected westerly tip jet events is compiled for the winters 1957 2002 and an analysis is undertaken of the character of the jet and its accompanying atmospheric features it is shown that the tip jet frequency exhibits a significant positive correlation with both the nao index and the latitude of the icelandic low the peak wind speed and accompanying heat fluxes of the jet have values up to 30 m s 1 and 600 w m 2 respectively and are sustained for less than one day the air parcels constituting the tip jet are shown based upon a trajectory model and the era 40 dataset to have a continental origin and to exhibit a characteristic deflection and acceleration around southern greenland the events are almost invariably accompanied both by a notable coherence of the lower level tip jet with an overlying upper level jet stream and by a surface cyclone located to the lee of greenland it is also shown that the cyclone originates upstream of and is advected to the lee of greenland and thereby it both precedes in time and contributes dynamically to the formation of the tip jet on this basis it is suggested that the tip jet arises from the interplay of the synoptic scale flow evolution and the perturbing effects of greenland s topography upon the flow copyright 2009 royal meteorological society

seasonal variations of sea ice and ocean circulation in the bering sea a model data fusion study 1 a 9 km coupled ice ocean model ciom was implemented in the entire bering sea to investigate seasonal cycles of sea ice and ocean circulation under atmospheric forcing sea ice cover with a maximum of 0 6 106 km2 in february to late march was reasonably reproduced by the bering ciom and validated by special sensor microwave imager ssm i measurements the model also captures some important spatial variability and downscaling processes such as polynyas and ridging which the ssm i measurements cannot reproduce because of their coarse 25 km resolution there are two distinct surface ocean circulation patterns in winter and summer on the bering shelves because of the dominant winds which are northeasterly in winter and southwesterly in summer summer low temperature high salinity water mass 3 c on the bering shelf is formed locally during winter because of strong vertical convection caused by salt injection when ice forms wind and wind wave mixing on the shelf the northward volume transport across the 62 5 n line with an annual mean of 0 8 0 33 sv 1 sv 106 m3 s 1 that is consistent with the measurements in the bering strait has barotropic structure which transports heat flux with an annual mean of 7 74 tw 1 tw 1012 w northward the anadyr current advects warmer saltier water northward during summer nevertheless it reverses its direction to southward during winter because of predominant northeasterly and northerly wind forcing therefore the anadyr current advects cold salty water southward the volume transport on the broad midshelf is northward year round advecting heat 3 3 2 4 tw and freshwater 8 10 104 practical salinity unit psu m3 s 1 northward one important finding is that the anadyr current and the midshelf current are out of phase in volume and heat transports the alaskan coastal current also transports heat and freshwater northward on an annual basis the bering ciom also captures the winter dense water formation along the siberian coast which is promoted by the downwelling favorable northeasterly wind and the summer upwelling due to the basin scale upwelling favorable southwesterly wind which brings up the cold salty and nutrient rich water from the subsurface to the surface within a narrow strip along the west coast this upwelling found in the model was also confirmed by satellite measurements in this study

deep convection in the irminger sea forced by the greenland tip jet open ocean deep convection one of the processes by which deep waters of the world s oceans are formed is restricted to a small number of locations for example the mediterranean and labrador seas recently the southwest irminger sea has been suggested as an additional location for open ocean deep convection the deep water formed in the irminger sea has the characteristic temperature and salinity of the water mass that fills the mid depth north atlantic ocean which had been believed to be formed entirely in the labrador basin here we show that the most likely cause of the convection in the irminger sea is a low level atmospheric jet known as the greenland tip jet which forms periodically in the lee of cape farewell greenland and is associated with elevated heat flux and strong wind stress curl using a history of tip jet events derived from meteorological land station data and a regional oceanic numerical model we demonstrate that deep convection can occur in this region when the north atlantic oscillation index is high which is consistent with observations this mechanism of convection in the irminger sea differs significantly from those known to operate in the labrador and mediterranean seas

accommodation and supply a dual control on stratigraphic sequences abstract it is widely accepted that both eustatic and tectonically controlled regional changes of sea level have contributed to the record of stratigraphic sequences i suggest that environmental change be added as a third autonomous control sedimentologic principles clearly indicate that sequences and their systems tracts are controlled by the interplay of two rates the rate of change in accommodation space available for sedimentation and the rate of sediment supply sea level has direct control on accommodation but its influence on sediment supply is remote and easily overshadowed by environmental factors for instance the record of the most recent sea level rise is a transgressive systems tract where supply is low it is a prograding highstand systems tract in deltas where the supply is high examples of sequence boundaries generated by changes in sediment supply include tectonically driven shifts in sediment input into basins changes in ocean currents pulsating supply from failure of submarine slopes and drowning of carbonate platforms by environmental stress furthermore the stratigraphic sequences in fluviatile continental basins are physically removed from sea level induced changes in accommodation and must have formed by changes in the rate and pattern of supply subaerial exposure of marine sediments at the sequence boundary is a most important criterion for recognizing sea level cycles as opposed to supply cycles other criteria include downstepping of shelf breaks and characteristic patterns in the spacing of time lines within sequences some third order cycles ca 0 5 3 ma duration meet these criteria others do not cycle stacking patterns and the shifting facies belts on cratons indicate that many second and third order cycles lack pronounced exposure unconformities and represent gradual changes superimposed on more rapid shorter oscillations seismic data yield poor images of these gradational changes because they lack resolution seismic models of outcrops show that near the limits of resolution the seismic tool tends to portray rapid changes in facies and bed thickness i e lateral variations in supply as unconformities seismic unconformities do not necessarily correspond to unconformities in outcrop the succession of stratigraphic sequences is best considered a composite record of sea level and environmental change separating the various controls requires carefully planned experiments work on the oxygen isotope curve another proxy for sea level has set an example in this respect

upwelling on the continental slope of the alaskan beaufort sea storms ice and oceanographic response 1 the characteristics of pacific born storms that cause upwelling along the beaufort sea continental slope the oceanographic response and the modulation of the response due to sea ice are investigated in fall 2002 a mooring array located near 152w measured 11 significant upwelling events that brought warm and salty atlantic water to shallow depths when comparing the storms that caused these events to other aleutian lows that did not induce upwelling interesting trends emerged upwelling occurred most frequently when storms were located in a region near the eastern end of the aleutian island arc and alaskan peninsula not only were these storms deep but they generally had northward tending trajectories while the steering flow aloft aided this northward progression the occurrence of lee cyclogenesis due to the orography of alaska seems to play a role as well in expanding the meridional influence of the storms in late fall and early winter both the intensity and frequency of the upwelling diminished significantly at the array site it is argued that the reduction in amplitude was due to the onset of heavy pack ice while the decreased frequency was due to two different upper level atmospheric blocking patterns inhibiting the far field influence of the storms

currents and transport on the eastern bering sea shelf an integration of over 20 years of data abstract more than 20 years of data from moorings satellite tracked drifters and hydrographic surveys are integrated to provide a comprehensive view of currents and transport on the eastern bering sea shelf the major sources of water onto the eastern bering sea shelf are north pacific water flowing through unimak pass and bering slope water flowing onto the shelf usually via the canyons that intersect the shelf break absolute geostrophic transport through unimak pass varies from an average of 0 25 106 m3 s 1 sv in the warm months to 0 43 sv in the cold months flow along the 50 m isobath is weak with a transport of 13 months and from amukta pass to bering strait via the bering slope current is 8 months consequently the source of most of the heat transported into the arctic through bering strait is a result of air sea interactions local to the northern bering sea analysis of the currents and water properties on the southern shelf indicates that 50 of the shelf water is exchanged with slope water during october january each year this exchange elevates the october mid shelf average nitrate level from 6 m to 14 16 m by the end of january

mesoscale structure of cape farewell tip jets abstractcape farewell greenland s southernmost point is characterized by a number of low level jets that are the result of topographic flow distortion associated with passing extratropical cyclones the heavy seas associated with these wind events are a hazard to maritime traffic in the region in addition the air sea heat flux associated with these weather systems plays an important role in the climate system by contributing to the forcing of the lower limb of the atlantic meridional overturning circulation in this paper the north american regional reanalysis will be used to generate a higher resolution climatology of these mesoscale jets as compared to previous studies through the use of a diagnostic that partitions the occurrence frequency of high speed wind events by wind direction the author shows that there are four different types of cape farewell tips jets that are characterized as having either northwesterly southwesterly northeasterly or southeasterly wind direction all four types hav

the contribution of alaskan siberian and canadian coastal polynyas to the cold halocline layer of the arctic ocean numerous arctic ocean circulation and geochemical studies suggest that ice growth in polynyas over the alaskan siberian and canadian continental shelves is a source of cold saline water which contributes to the maintenance of the arctic ocean halocline the purpose of this study is to estimate for the 1978 1987 winters the contributions of arctic coastal polynyas to the cold halocline layer of the arctic ocean the study uses a combination of satellite oceanographic and weather data to calculate the brine fluxes from the polynyas then an oceanic box model is used to calculate their contributions to the cold halocline layer of the arctic ocean this study complements and corrects a previous study of dense water production by coastal polynyas in the barents kara and laptev seas recurrent polynyas form on the canadian and alaskan coasts from banks island to the bering strait and on the siberian coast from the bering strait to the new siberian islands in the bering sea polynyas form in norton sound south and west of st lawrence island and in the gulf of anadyr two regions that account for almost 50 of the total dense water production are the siberian coastal polynyas in the adjacent regions of the gulf of anadyr and anadyr strait and the alaskan coastal polynyas which occur along the coast from cape lisburne to point barrow for all of the western arctic coastal regions examined the mean annual total brine flux is 0 5 0 2 sv combination of this flux with the contribution from the barents kara and laptev seas which is recalculated from data in the earlier study shows that over the entire arctic coastal polynyas generate about 0 7 1 2 sv of dense water this compares well with the theoretical estimates of 1 1 5 sv because an unknown fraction of the barents kara and laptev brine flux must go to the eurasian basin deep water the coastal polynyas alone cannot renew the halocline layer other potential brine generation mechanisms include overall freezing on the shelves and the response of the ice to infrequent violent storms for example during february 1982 an intense storm generated a large region of low ice concentration in the eastern chukchi sea over barrow canyon the refreezing of the region was followed by the flow of a dense plume down barrow canyon although the ocean dynamical response to this refreezing needs to be established the possible response of a barrow canyon flow to this refreezing event suggests that the overall refreezing in response to infrequent violent storms may be a potential source of the additional brine needed to maintain the arctic ocean halocline

tip jets and barrier winds a quikscat climatology of high wind speed events around greenland the high topography of greenland results in a number of orographically induced high wind speed flows along its coast that are of interest from both a severe weather and climate perspective here the surface wind field dataset from the nasa jpl seawinds scatterometer on board the quick scatterometer quikscat satellite is used to develop a wintertime climatology of these flows the high spatial resolution and the twice daily sampling of the seawinds instrument allows for a much more detailed view of the surface winds around greenland than has been previously possible three phenomena stand out as the most distinctive features of the surface wind field during the winter months the previously identified tip jets and reverse tip jets as well as the hitherto unrecognized barrier flows along its southeast coast in the vicinity of the denmark strait peak surface wind speeds associated with these phenomena can be as large as 50 m s 1 with winds over 25 m s 1 occurring approximately 10 15 of the time at each location a compositing technique is used to show that each type of flow is the result of an interaction between a synoptic scale parent cyclone and the high topography of greenland in keeping with previous work it is argued that tip jets are caused by a combination of conservation of the bernoulli function during orographic descent and acceleration due to flow splitting as stable air passes around cape farewell while barrier winds are a geostrophic response to stable air being forced against high topography it is proposed that reverse tip jets occur when barrier winds reach the end of the topographic barrier and move from a geostrophic to a gradient wind balance becoming supergeostrophic as a result of their anticyclonic curvature

tectonic control in the boundaries of the genetic units an example in the dogger of the external zones of the betic cordillera province of murcia and almeria spain abstract i have studied the evolution of a genetic unit of the dogger to the north of velez rubio external zones of the betic cordilleras southeast spain this unit at its lower and upper boundaries is limited by sedimentary breaks of the uppermost toarcian and intra upper bathonian respectively starting from the analysis and distribution of facies rich in ostracods oncolites oolites crinoids peloids pelagic pelecypods or deposited particles on diverse drawn columns the lateral and vertical evolution in this section of the basin for this period of time can be deduced this permits the differentiation between systems tracts lowstand systems tract lst transgressive systems tract tst and highstand systems tract hst with a slightly homogeneous distribution which can be related to an uneven morphology of the substratum different factors that controlled the evolution of the basin during this period of time have been analysed from this we can deduce that the role of tectonics could be dominant as contrasted with that of eustasy an anomalous evolution toward the top of the highstand systems tract is indicated in this unusually thick succession some evidence of retrogradation can be deduced this could not be explained eustatically but it could certainly be explained tectonically

mesoscale climatology and variation of surface winds over the chukchi beaufort coastal areas abstractthe detailed mesoscale climatology of surface winds in the chukchi beaufort seas and adjacent arctic slope region is analyzed using the recently developed chukchi beaufort high resolution atmospheric reanalysis cbhar within the study area surface winds are mainly driven by the prevailing synoptic weather patterns of the beaufort high and aleutian low and are further modulated by local geographic features through thermodynamic and dynamic processes sea breezes up or downslope winds and the mountain barrier jets are all clearly captured by cbhar sea breezes emerge in june september and last most of the day with a maximum spatial extent 100 km inland and 50 km offshore and maximum speed around 1 3 m s 1 in the late afternoon 1500 alaska standard time akst thermodynamic impacts of mountains on the surface winds vary from time to time drainage flows begin to build at the mountaintop in september and reach the strongest during november february occupying the entire slope upslope winds

an overview of barrier winds off southeastern greenland during the greenland flow distortion experiment during the greenland flow distortion experiment barrier flow was observed by an instrumented aircraft on 1 2 5 and 6 march 2007 off southeastern greenland during this time period the barrier flow increased from a narrow jet 15 m s 1 to a jet filling almost the whole of the denmark strait with maximum wind speed exceeding 40 m s 1 dropsonde observations show that the barrier flow was capped by a sharp temperature inversion below mountain height below the inversion was a cold and dry jet with a larger northerly wind component than that of the flow above which was also warmer and more moist thus the observations indicate two air masses below mountain height a cold and dry barrier jet of northern origin and above this a warmer and moister air mass that was of cyclonic origin numerical simulations emphasize the non stationarity of the greenland barrier flow and its dependence on the synoptic situation in the greenland iceland region they show that the barrier jet originated north of the denmark strait and was drawn southward by a synoptic scale cyclone with the strength and location of the maximum winds highly dependent on the location of the cyclone relative to the orography of greenland experiments without greenland s orography suggest a 20 m s 1 enhancement of the low level peak wind speeds due to the presence of the barrier thus the greenland barrier flows are not classic geostrophically balanced barrier flows but have a significant ageostrophic component and are precisely controlled by synoptic scale systems copyright c 2009 royal meteorological society

buoy observations from the windiest location in the world ocean cape farewell greenland 1 cape farewell greenland s southernmost point is a region of significant interest in the meteorological and oceanographic communities in that atmospheric flow distortion associated with the high topography of the region leads to a number of high wind speed jets the resulting large air sea fluxes of momentum and buoyancy have a dramatic impact on the region s weather and ocean circulation here the first in situ observations of the surface meteorology in the region collected from an instrumented buoy are presented the buoy wind speeds are compared to 10 m wind speeds from the quikscat satellite and the north american regional reanalysis narr we show that the quikscat retrievals have a high wind speed bias that is absent from the narr winds the spatial characteristics of the high wind speed events are also presented

lithosphere dynamics and tectono stratigraphic evolution of the mesozoic betic rifted margin southeastern spain abstract quantitative subsidence analysis demonstrates that mesozoic sediments in the eastern betic cordilleras have been deposited on a thermally subsiding rifted margin the dynamics of rifting are related to regional trans tension in the atlantic realm modelling of this phase of rifting at the southern iberian margin shows that the associated stretching of the lithosphere significantly altered its geometrical and mechanical structure and exerted a major control on subsequent convergence tectonics the mesozoic stretching led to the formation of a ramp at the margin due to strong lateral variations in the effective elastic thickness eet of the lithosphere and the thickness of the crust in a direction perpendicular to the margin the existence of a ramp structure in the late mesozoic at the iberian margin which is also supported by stratigraphic and structural data is important for the style of subsequent deformation of the lithosphere in late cretaceous tertiary times the lateral variations in eet inferred from forward modelling of rifted margin stratigraphy could explain the observed multiple collapse of the betic margin and the partitioning of deformation between the converging units involved in the betic orogeny modelling of depth dependent palaeo rheological profiles of the margin shows that the mechanical properties of the lithosphere after stretching differed distinctly from those before stretching lithospheric deformation in the betic cordilleras during the tertiary orogeny seems therefore to be largely controlled by the previous rifting phase a comparison of the palaeo and present day rheologies in terms of estimates for eet during late cretaceous and present times indicates that the mechanical properties of the lithosphere underlying the betic orogen were also affected by rifting during late oligocene aquitanian times this phase of rifting is coeval with extension in the valencia trough the gulf of lions and the west european rift system which supports a causal relation with regional lithospheric processes the lateral and spatial variations in thermo mechanical properties of the lithosphere underlying the betics therefore reflect the dynamics of lithospheric extension on a larger scale

northern bering sea tip jets 1 low level regions of high wind speed known as tip jets have been identified near cape farewell greenland s southernmost point these wind systems contribute to this area being the windiest location on the ocean s surface and play an important role in the regional weather and climate here we present the first analysis of the wind systems that make the siberian coast of the northern bering sea the windiest location in the north pacific ocean during the boreal winter in particular we show that tips jets characterized by enhanced northeasterly winds occur in the vicinity of the two prominent headlands along the coast cape navarin and cape olyutorsky the advance of sea ice in the region is shown to impact the frequency and location of the high speed winds in the vicinity of these two capes furthermore we show that these jets are associated with the interaction of extra tropical cyclones with the high topography of the koryak mountain range situated just inland of the capes the windstress imparted to the ocean via the tip jets is argued to help drive the formation of dense water in winter in the northern bering sea thus playing an important role in the regional oceanic circulation

an easterly tip jet off cape farewell greenland ii simulations and dynamics an easterly tip jet that occurred on 21 february 2007 off cape farewell greenland is examined in part i of this article aircraft observations were described now in part ii numerical simulations and an analysis of the dynamical forcing mechanisms are presented the simulations make use of a limited area 12 km resolution configuration of the met office s unified model sea surface temperatures and sea ice concentrations have been replaced using the operational sea surface temperature and sea ice analysis ostia product addressing a boundary layer temperature bias while roughness lengths over sea ice have been updated addressing a wind speed bias these modifications ensured a reasonably accurate simulation generally within 1 2 k and 2 3 m s 1 when compared with dropsonde observations a momentum budget analysis along a curved locus through the core of the jet has been derived off southeast greenland the easterly tip jet was in cross jet geostrophic balance but was being accelerated downstream by an along jet pressure gradient over the curved part of the locus as the jet rounded cape farewell a cross jet residual suggests that the jet was unbalanced at the height of the jet core this residual decreases with height so that an approximate gradient wind balance applies in the upper part of the jet the anticyclonic curvature characteristic of easterly tip jets was caused by a dramatic decrease in the cross jet pressure gradient force at the end of the barrier after which the jet aligned with the synoptic scale isobars and returned to approximate geostrophic balance the momentum budget is shown to be robust and applicable to other cases copyright 2009 royal meteorological society

effects of a shelf polynya on flow and water properties in the northern bering sea we present long term 230 day measurements from three moorings in the vicinity of saint lawrence island on the northern bering sea shelf one mooring was deployed near the polynya which often exists south of the island these data confirm the existence of strong 0 15 m s 1 flow toward bering strait northwest of the island in anadyr strait and suggest that regional circulation results in a moderate 0 03 5 m s 1 mean flow eastward along the southern coast of saint lawrence island coherent variations in the regional circulation and variations in the geostrophic wind account for much of the low frequency current fluctuation south of saint lawrence island however there were 11 events when offshore northerly winds coincided with the temperature following the freezing point increasing salinity and reversal of the current this suggests that ice formation and the ensuing brine rejection affect flow in the vicinity of the polynya scaling of a simplified momentum equation indicates that the cross shelf density gradient was a possible mechanism for some of the reversals salinity data show a seasonal cycle as well as individual events of brine rejection during an average event time of 65 hours the salinity increased by 8 10 3 g kg 1 h 1 the heat flux can be estimated as 535 wm 2 these fluxes correspond to an ice production of 5 m during winter 1981 extrapolation of our results and comparison with the freshwater cycle suggest that brine rejection is an important component of the regional salt budget

an easterly tip jet off cape farewell greenland i aircraft observations an easterly tip jet event off cape farewell greenland is described and analysed in considerable detail in part i of this study this paper comprehensive aircraft based observations are described while in part ii of this study numerical simulations and a dynamical analysis are presented the easterly tip jet of 21 february 2007 took place during the greenland flow distortion experiment it resulted through the interaction of a barotropic synoptic scale low pressure system in the central north atlantic and the high topography of southern greenland in situ observations reveal a jet core at the coast with peak winds of almost 50 m s 1 about 600 800 m above the sea surface and of 30 m s 1 at 10 m the depth of the jet increased with wind speed from 1500 m to 2500 m as the peak winds increased from 30 to 50 m s 1 the jet accelerated and curved anticyclonically as it reached cape farewell and the end of the barrier the easterly tip jet was associated with a tongue of cold and dry air along the coast of southeast greenland general cloud cover to the east and cloud streets to the south of cape farewell precipitation was observed during the low level components of the flight the very high wind speeds generated a highly turbulent atmospheric boundary layer and resulted in some of the highest surface wind stresses ever observed over the ocean copyright c 2009 royal meteorological society

gale force winds over the irminger sea to the east of cape farewell greenland 1 high wind events that occur over the irminger sea to the east of cape farewell greenland are of interest as a result of the significant hazard they represent to maritime activity as well as their potential role in forcing deep ocean convection in the region in this paper the ncep reanalysis is used to develop a climatology of gale force wind events over the irminger sea in addition to the previously identified tip jet events that are characterized by strong westerly flow we show that there also exist reverse tip jet events that are characterized by strong easterly flow both types of events are associated with deep extra tropical cyclones that are undergoing an interaction with the high topography of southern greenland we also show that the frequency of both types of events is highest in the winter months and is modulated by the phase of the north atlantic oscillation nao

the novaya zemlya bora and its impact on barents sea air sea interaction 1 novaya zemlya is a mountainous archipelago in the eastern arctic weather station data indicates that southeasterly high speed winds are frequent especially during the winter although it has been proposed that a bora is responsible for these winds there has been no quantitative analysis of the flow in the region here we present the first high resolution climatology of the three dimensional wind field near novaya zemlya the high speed wind events are shown to share many characteristics with bora as well as models of downslope windstorms the highest wind speeds occur where barents sea dense water is observed to form and we show that there is a doubling in the turbulent heat transfer from the ocean to the atmosphere during bora it is argued that the bora plays an important role in the transformation of the atlantic water that passes by the archipelago en route to the central arctic ocean

ekofisk first of the giant oil fields in western europe discovery of the giant ekofisk field in block 2 4 in the norwegian part of the north sea in 1969 was a major turning point in the exploration for petroleum in western europe since that time the north sea has proven to be one of the best areas for exploration anywhere in the world current production is 1 5 million barrels of oil per day and north sea proven reserves total 18 billion barrels with estimates of ultimate reserves as high as 40 billion barrels ekofisk is located in the central graben in the southern part of the norwegian sector of the north sea although several periods of tectonism have affected this area it has remained an intercratonic basin since devonian time the main elements of the tectonic fabric were established during the caledonian and hercynian orogenies and later remained as controlling features for facies and sediment distribution a stratigraphic history reveals petrography of the main chalk group environment of deposition and diagenetic history of the area a section outlines the preservation of porosity which has allowed the ekofisk and tor formations to retain an average porosity of 30 to 40 percent which would not have been possible under normal circumstances it is appropriate to state that the anomalously high porosity in ekofisk field is probably due to a combination of 1 overpressuring of the reservoir 2 magnesium rich pore fluids and 3 early introduction of hydrocarbons the six greater ekofisk fields now being developed were all located during the 1960s by reconnaissance seismic work the history of the geophysical exploration is outlined and a study has been made on source rock analysis and geopressures also outlined is the three phase greater ekofisk development program