hydrographic structure of the convection regime in the gulf of lions winter 1987 abstract deep winter convection in the northwestern mediterranean gulf of lions and the subsequent formation of mediterranean deep water were observed using advanced oceanographic instrumentation during a six week long experiment in 1987 the severe 1987 european winter forced an intense outbreak of the mistral a cold dry wind blowing down the rhone valley in mid january surface cooling and evaporation were of sufficient intensity to cause an initial episode of deep convection shortly before the experiment described here began however several more mistral events took place during the experiment during several cruises into the area ctd and absolute horizontal velocity profiles were measured in the mixed area over the rhone fan as well as across the southern front of this region in addition continuous records of shipboard meteorological and oceanographic parameters air temperature surface salinity etc were made an early february mistral apparently did not produce enough surface cooling to

estimation of deep and intermediate water mass formation rates in the mediterranean sea abstract using a simple diagnostic model and climatological surface temperature salinity and air sea fluxes the deep and intermediate water formation sites of the mediterranean sea are determined as well as the annual formation rates for each of them with the same model the t and s characteristics of the water masses are estimated four distinct formation sites are formed one in the western gulf of lions and three in the eastern adriatic northern ionian rhodes gyre area southern aegean basin respectively with well defined water types being produced at each formation site the computed annual production rates compare quite well with other independent estimations found in literature

formation and spreading of red sea outflow water in the red sea hydrographic data chlorofluorocarbon 12 cfc 12 and sulfur hexafluoride sf6 measurements collected in march 2010 and september october 2011 in the red sea as well as an idealized numerical experiment are used to study the formation and spreading of red sea outflow water rsow in the red sea analysis of inert tracers potential vorticity distributions and model results confirm that rsow is formed through mixed layer deepening caused by sea surface buoyancy loss in winter in the northern red sea and reveal more details on rsow spreading rates pathways and vertical structure the southward spreading of rsow after its formation is identified as a layer with minimum potential vorticity and maximum cfc 12 and sf6 ventilation ages of seawater within the rsow layer calculated from the partial pressure of sf6 psf6 range from 2 years in the northern red sea to 15 years at 17 n the distribution of the tracer ages is in agreement with the model circulation field which shows a rapid transport of rsow from its formation region to the southern red sea where there are longer circulation pathways and hence longer residence time due to basin wide eddies the mean residence time of rsow within the red sea estimated from the psf6 age is 4 7 years this time scale is very close to the mean transit time 4 8 years for particles from the rsow formation region to reach the exit at the strait of bab el mandeb in the numerical experiment

the land sea breeze of the red sea observations simulations and relationships to regional moisture transport unique in situ observations of atmospheric conditions over the red sea and the coastal arabian peninsula are examined to study the dynamics and regional impacts of the local land sea breeze cycle lsbc during a 26 month data record spanning 2008 2011 observed lsbc events occurred year round frequently exhibiting cross shore wind velocities in excess of 8 m s observed onshore and offshore features of both the land and sea breeze phases of the cycle are presented and their seasonal modulation is considered weather research and forecasting climate downscaling simulations and satellite measurements are used to extend the analysis in the model the amplitude of the lsbc is significantly larger in the vicinity of the steeper terrain elements encircling the basin suggesting an enhancement by the associated slope winds observed and simulated conditions also reflected distinct gravity current characteristics of the intrinsic moist marine air mass during both phases of the lsbc specifically the advance and retreat of marine air mass was directly tied to the development of internal boundary layers onshore and offshore throughout the period of study convergence in the lateral moisture flux resulting from this air mass ascending the coastal topography sea breeze phase as well as colliding with air masses from the opposing coastline land breeze phase further resulted in cumulous cloud formation and precipitation

salinity driven thermocline transients in a wind and thermohaline forced isopycnic coordinate model of the north atlantic abstract an isopycnic coordinate oceanic circulation model formulated with the aim of simulating thermodynamically and mechanically driven flow in realistic basins is presented special emphasis is placed on the handling of diabatic surface processes and on thermocline ventilation the model performance is illustrated by a 30 year spinup run with coarse horizontal resolution 2 mesh in a domain with north atlantic topography extending from 10 to 60 n latitude the vertical structure encompasses 10 isopycnic layers in steps of 0 2 units capped by a thermodynamically active mixed layer from an initially isohaline state with isopycnals prescribed by zonally averaged climatology the model is forced by seasonally varying wind stress radiative and freshwater fluxes and by a thermal relaxation process at the surface after a mechanical spinup time of about 15 years a quasi stationary pattern of mean circulation and annual variability ensues characterized by pronounced subtropical mode water formation

sensitivity studies of the red sea eddies using adjoint method the topography data is derived from general bathymetric chart of the oceans gebco https www gebco net the open boundary conditions are extracted from the estimating the circulation and climate of the ocean ecco product https ecco jpl nasa gov products the data supporting the analysis presented here can be found at figshare https figshare com articles data for 2018jc014531r 7243184 the research reported in this manuscript is supported by king abdullah university of science and technology kaust and made use of the resources of the supercomputing laboratory and computer clusters at kaust

an oceanographic nowcast forecast system for the red sea we describe the application of a nowcast forecast system for three dimensional currents temperature and salinity to the red sea the modeling system is constructed around a high resolution 6 7 km primitive equation numerical circulation model with complete thermodynamics and an imbedded turbulence closure submodel it is coupled to near real time databases containing meteorological forecasts and remotely sensed and in situ temperature and salinity data the temperature and salinity data are ingested into the model daily using a nudged objective analysis technique because the red sea is a relatively narrow basin bounded by typically high and complex orography a single layer atmospheric boundary layer submodel has been used to increase the effective resolution of the original 40 km resolution meteorological fields by taking into account orographic steering of the low level winds in order to validate the modeling system two very complete hydrographic surveys of the red sea were undertaken and their results are described both the surveys and the modeling system nowcasts demonstrate that the circulation pattern of the red sea is variable and often composed of a series of eddies or subgyres mainly anticyclones immediately before one survey the winds tended to be along axis while just before the second they tended to be cross axis the red sea circulation was much more eddy like when the winds were cross axis by forcing the modeling system with and without orographically steered winds we were able to establish that the complex eddy structure is a response to a wind field which can be highly structured and vorticity rich because of interaction with the high and variable adjacent orography when the winds are more along axis there is less interaction with the adjacent orography and consequently there are fewer eddies in the red sea

holocene and last interglacial cloudiness in eastern baffin island arctic canadathis article is one of a series of papers published in this special issue on the theme polar climate stability network geotop publication 2008 0027 this study presents last interglacial and holocene vegetation and climate changes at fog lake 67 11 n 63 15 w on eastern baffin island arctic canada the vegetation cover is reported as vegetat

direct observations of seasonal exchange through the bab el mandab strait the exchange flow between the red sea and the gulf of aden indian ocean through the bab el mandab strait was measured continuously for 10 months june 1995 march 1996 adcp and temperature salinity chain moorings allow an unprecedented look at the magnitude and seasonal evolution of the inflow layer from the gulf of aden and the high salinity outflow layer from the red sea the timing structure and evolution of the summer season mid depth intrusion of cold low salinity water into the red sea from the gulf of aden is measured for the complete intrusion cycle of 1995 we unexpectedly find the deep outflow still strong in june 1995 with speeds of 0 6 m sec and transport of 0 4 sv 1 sv 106 m sec from july to mid september the deep outflow persists but is attenuated to speeds of 0 2 m sec and transport of 0 05 sv the dominant summer feature the cold low salinity intermediate layer intrusion persists for 3 months occupies 70 of the water column in the strait and carries approximately 1 7 1012 m of cold nutrient rich water into the red sea the winter regime begins in mid september is fully developed by early november and continues to the end of our first observation interval in march 1996 speeds in the lower layer are 0 8 1 0 m sec and 0 4 0 6 m sec in the upper layer at maximum exchange in mid february outflow transport reaches 0 7 sv ubiquitous oscillations in current and salinity at synoptic and intraseasonal periods appear closely related to fluctuations in the along channel wind forcing and perhaps to coastally trapped waves

exchange through the bab el mandab during the last 10 years there have been a number of important developments in the understanding of the exchange flow in the bab el mandab new and improved estimates of the fluxes of mass heat and salt through the strait have been made directly from oceanographic measurements and indirectly from air sea flux data hydraulic theory has been applied to explain the seasonal variations in the exchange flow and in particular the three layer summer circulation the effects of wind stress friction and seasonal sea level variability on hydraulic control are addressed in this paper analyses of oceanographic data have failed to provide direct evidence of hydraulic control but they have highlighted the importance of tidal scale variability and differences between real continuously stratified fluids and idealised layer flows often used in hydraulic theory other studies have investigated the coupling between the flow in the strait and the circulation within the red sea

the summer circulation in the gulf of suez and its influence in the red sea thermohaline circulation abstractthe gulf of suez is accepted as an important location for red sea deep water formation but the circulation and exchange with the red sea around the year remains elusive a summer cruise in the area gives the opportunity to investigate features of the summertime hydrological structure and exchange with the red sea an inverse estuarine circulation and exchange with the red sea is evident the topographic patterns of the gulf play an important role in the circulation two sills one in midbasin and a second at the mouth of the gulf inhibit the bottom flow topographically trapping waters that were formed in the cold season although the water mass characteristics of the outflowing waters during the other seasons are not directly related to the deep waters they can influence the water column structure of the northern red sea a simple box model shows that their contribution can have a significant influence in the formation of the intermediate layer a hypersaline 40 6 psu but relatively warm 23

species valve size and pretreatment effects on δ18o and δ13c values of ostracod valves from lake qinghai qinghai tibet plateau abstract stable carbon and oxygen isotope ratios of lacustrine ostracod valves are widely used to deduce paleoenvironmental information we tested the effects of sample pretreatment methods methanol deionised water and methanol and hydrogen peroxide on ostracod shell oxygen and carbon isotope compositions in addition we examined the stable isotope differences among ostracod valves of different sizes and between the two species eucypris inflata and limnocythere inopinata present in lake qinghai we found that different treatment methods have no significant effect on the measured c or o stable isotope ratios of ostracod valves and therefore propose that pretreatment is not needed before isotope analysis oxygen isotope ratios of e inflata were positively correlated with l inopinata this correlation suggests that the 18 o values of the two species respond similarly to environmental change the 13 c values of e inflata showed no correlation with l inopinata and e inflata had consistently higher 13 c values than l inopinata valve length had no effect on measured 18 o values for e inflata but 13 c values increased with the decreasing shell length for length classes 18 o history in contrast much more attention must be paid to the selection of species and size when using the carbon isotope composition of ostracods for palaeoenvironmental reconstruction

palaeo water depth estimation for a 600 year record from nam co tibet using an ostracod based transfer function a modern training set of ostracods from the large slightly saline lake nam co on the southeastern tibetan plateau is presented in total 44 samples covering the largest part of the lake and water depth from 2 to 93 m were taken there are eight ostracod species in surface sediments of nam co leucocytherella sinensis leucocythere dorsotuberosa fabaeformiscandona gyirongensis candona xizangensis candona candida ilyocypris cf mongolica eucypris gyirongensis and limnocythere inopinata in order of mean dominance a morphological variant of l dorsotuberosa the forma postilirata is an indicator form of deep water below the thermocline the 36 samples comprise a sufficient number of ostracods for analysis covering water depths between 3 7 and 89 3 m two transfer function models based on weighted average binomial regression wa br and weighted average partial least square regression wa pls using the programs excel and c2 were established to estimate past water depths of nam co transfer functions were applied to ostracod data from two short cores from nam co covering approximately the past 600 years model results show a lake level minimum occurring during the little ice age lia between about 1490 and 1760 ad this minimum corresponds to results from previous stable isotope analysis and indicates a lake level which was about 5 m below the present day level the more exact transfer function model wa pls was set up using c2 and revealed a higher correlation index r o f 0 91 and a lower standard error of 6 7 m however the more selective because of using indicator taxa only wa br model using excel r 0 88 standard error 10 6 m seems to represent palaeo water depths better at least for the studied short cores

ostracod distribution and habitat relationships in the kunlun mountains northern tibetan plateau abstract surface sediment samples were collected from the lakes heihai kusai haiding nuur and yan hu and from streams and ponds in the kunlun mountains at the northern margin of the tibetan plateau to investigate the sub fossil ostracod micro crustacean fauna of the region among 65 collected samples 46 ostracod shell rich samples were used to study the relationship between the ostracod distribution and specific conductivity sc of the water which ranged from 0 6 to 53 0 ms cm 1 a total of eleven ostracod species was identified from this region with about half of the species restricted to the tibetan plateau and its adjacent mountain areas and the other half representing holarctic taxa tonnacypris cf estonica and tonnacypris tonnensis are reported from the tibetan plateau for the first time leucocythere sp is the dominant species and ilyocypris cf bradyi is also relatively abundant the other seven species were recorded with limited abundances apparently due to lower sc tolerances leucocythere sp was recorded over the full sc range from 0 6 to 53 ms cm 1 eucypris mareotica is a typical brackish and saline water species which was found at sample sites with high sc 2 8 53 0 ms cm 1 in contrast leucocythere dorsotuberosa candona candida and eucypris afghanistanensis prefer freshwater to slightly oligohaline waters with sc 1 the sc optimum and tolerance range for each species were determined and compared to earlier reported data from other regions of central asia the results indicate that species assemblage data from fossil ostracod shells have a large potential to provide information on past sc levels and more general climate determined moisture conditions

renewal of deep water in the red sea during 1982 1987 between october 1982 and may 1983 the deep water in the northern red sea was ventilated through slope convection the deep water became cooler fresher and more oxygenated dense bottom water formed in the gulf of suez during winter cooling sank down the continental slope thereby entraining near surface and intermediate depth waters from the application of a one dimensional plume model a vertical transport of 0 58 106 m3 s 1 over a period of 7 months was estimated long term time series of atmospheric heat fluxes show that such a major convection event can occur every 4 7 years the corresponding renewal time of the red sea deep water is thus of the order of 40 90 years in agreement with previous estimates

a mixed layer study of the formation of levantine intermediate water a mixed layer model is used to investigate the formation of levantine intermediate water liw over the eastern mediterranean the one dimensional model is initialized with climatological hydrography and integrated over the levantine basin with forcing by climatological surface fluxes realistic and repeated seasonal mixed layer cycles are obtained if the annual surface heat input and water loss are offset by a parameterized horizontal advection the model integrations show that liw is formed during winter in the mixed layer of the northwestern levantine the preferred formation region for liw is found through idealized experiments to be controlled by the preconditioning of the hydrography especially that of the cold cyclonic rhodes gyre rather than by the pattern of the climatological fluxes the annual mean formation rate of liw is estimated to be 1 0 sv using the climatological surface fluxes the magnitude of the annual surface fluxes alters the formation rate and modifies the formation region an additional annual heat flux reduces the formation rate of liw whereas an extra cooling enhances it as well as forming waters denser than liw in the center of the rhodes gyre

process modeling studies of physical mechanisms of the formation of an anticyclonic eddy in the central red sea surface drifters released in the central red sea during april 2010 detected a well defined anticyclonic eddy around 23 n this eddy was 45 60 km in radius with a swirl speed up to 0 5 m s the eddy feature was also evident in monthly averaged sea surface height fields and in current profiles measured on a cross isobath shipboard ctd adcp survey around that region the unstructured grid finite volume community ocean model fvcom was configured for the red sea and process studies were conducted to establish the conditions necessary for the eddy to form and to establish its robustness the model was capable of reproducing the observed anticyclonic eddy with the same location and size diagnosis of model results suggests that the eddy can be formed in a red sea that is subject to seasonally varying buoyancy forcing with no wind but that its location and structure are significantly altered by wind forcing initial distribution of water stratification and southward coastal flow from the upstream area momentum analysis indicates that the flow field of the eddy was in geostrophic balance with the baroclinic pressure gradient forcing about the same order of magnitude as the surface pressure gradient forcing

millennial scale variability in red sea circulation in response to holocene insolation forcing in order to assess how insolation driven climate change superimposed on sea level rise and millennial events influenced the red sea during the holocene we present new paleoceanographic records from two sediment cores to develop a comprehensive reconstruction of holocene circulation dynamics in the basin we show that the recovery of the planktonic foraminiferal fauna after the younger dryas was completed earlier in the northern than in the central red sea implying significant changes in the hydrological balance of the northern red sea region during the deglaciation in the early part of the holocene the environment of the red sea closely followed the development of the indian summer monsoon and was dominated by a circulation mode similar to the current summer circulation with low productivity throughout the central and northern red sea the climatic signal during the late holocene is dominated by a faunal transient event centered around 2 4 ka bp its timing corresponds to that of north atlantic bond event 2 and to a widespread regionally recorded dry period this faunal transient is characterized by a more productive foraminiferal fauna and can be explained by an intensification of the winter circulation mode and high evaporation the modern distribution pattern of planktonic foraminifera reflecting the prevailing circulation system was established after 1 7 ka bp

on the origin of a chain of eddies in the gulf of eilat aqaba abstractthe gulf of eilat aqaba is a terminal elongated basin that exchanges water with the northern red sea via the straits of tiran this study used energy budgets of mean kinetic energy mke and eddy kinetic energy eke differentiated by a simple horizontal averaging filter instability analysis and numerical simulations to study the horizontal circulation of the gulf which is characterized by the existence of a chain of eddies along its main axis the kinetic energy is predominantly in the form of eke energy conversion between mke and eke is negligible where the main sources for both energy reservoirs are the conversions from the available potential energy ape this term is balanced by the work done by pressure at the straits in case of mke and by dissipation in the case of eke the mke balance represents the coupling between the exchange flow at the straits and the wintertime dense water formation the dense water exits through the straits while sinking adiabatically along the gulf the stro

wind induced sea level variability in the red sea analysis of topex poseidon altimetry data for the red sea shows a large seasonal sea level signal in agreement with the few available coastal sea level stations the results are compared with the predictions from a simple model that balances the sea surface elevation against the wind stress the winter sea level field in the central and northern red sea is shown to be a response to the convergent wind pattern associated with the indian monsoon consisting of nnw winds in the northern red sea and sse winds in the south there is a very good agreement between the model and observations indicating that the basic mechanism responsible for the variability of the sea surface height inside the red sea on seasonal time scales is the wind pattern

an oceanic general circulation model ogcm investigation of the red sea circulation 2 three dimensional circulation in the red sea 1 the three dimensional circulation of the red sea is studied using a set of miami isopycnic coordinate ocean model micom simulations the model performance is tested against the few available observations in the basin and shows generally good agreement with the main observed features of the circulation the main findings of this analysis include an intensification of the along axis flow toward the coasts with a transition from western intensified boundary flow in the south to eastern intensified flow in the north and a series of strong seasonal or permanent eddy like features model experiments conducted with different forcing fields wind stress forcing only surface buoyancy forcing only or both forcings combined showed that the circulation produced by the buoyancy forcing is stronger overall and dominates the wind driven part of the circulation the main circulation pattern is related to the seasonal buoyancy flux mostly due to the evaporation which causes the density to increase northward in the basin and produces a northward surface pressure gradient associated with the downward sloping of the sea surface the response of the eastern boundary to the associated mean crossbasin geostrophic current depends on the stratification and b effect in the northern part of the basin this results in an eastward intensification of the northward surface flow associated with the presence of kelvin waves while in the south the traditional westward intensification due to rossby waves takes place the most prominent gyre circulation pattern occurs in the north where a permanent cyclonic gyre is present that is involved in the formation of red sea outflow water rsow beneath the surface boundary currents are similarly intensified southward undercurrents that carry the rsow to the sill to flow out of the basin into the indian ocean index terms 4243 oceanography general marginal and semienclosed seas 4255 oceanography general numerical modeling 4532 oceanography physical general circulation keywords red sea marginal sea oceanic general circulation model water mass formation

on the sources formation and circulation of red sea deep water red sea deep water is renewed from sources in the far north of the red sea upwelling of deep water throughout the basin maintains the sharp pycnocline with its base near the depth of the sill at bab el mandeb before now deep water renewal was thought to occur mainly by means of convective deep water formation in the north which renews the bottom water and gives rise to a southward flowing bottom current carbon 14 and 3he data from the geosecs indian ocean expedition lead to the identification of an additional volumetrically larger mode of northern deep water formation in which new deep water is injected immediately beneath the pycnocline this mode of deep water formation to be called the isopycnal mode also gives rise to a southward flowing current in this case at the top of the deep water mass geosecs data also demonstrate the existence at intermediate depths in the deep water of a return flow to the north the surface history in the nuclear era of the 14c in the deep water source region was reconstructed by direct radiocarbon measurements on annual growth bands of corals calculation then shows that new deep water forms in the convective mode at a rate of 0 05 0 01 sverdrup sv expressed as if the flow were continuous and is due principally to processes occurring in the mouth of the gulf of suez the injection beneath the pycnocline of new deep water formed in the isopycnal mode is 0 11 0 02 sv this new deep water appears to originate mainly in the extreme open northern red sea the gulf of aqaba makes a modest but significant contribution to both modes the total deep water renewal rate is about 0 16 sv yielding a bulk deep water residence time of about 36 years oxygen consumption in the deep water shows approximately exponential decrease of consumption rate with depth as expected on geological and geophysical grounds hydrographically significant fluxes of heat and salt from the sea floor into the red sea deep water are discernible in the hydrography helium 3 flux from the sea floor into the deep water is about 69 1 stp year

physical and biological characteristics of the winter summer transition in the central red sea the central red sea crs lies between two distinct hydrographic and atmospheric regimes in the southern red sea seasonal monsoon reversal regulates the exchange of water between the red sea and the indian ocean in the northern red sea intermediate and occasionally deep water are formed during winter to sustain the basin s overturning circulation highly variable mesoscale eddies and the northward flowing eastern boundary current ebc determine the physical and biogeochemical characteristics of the crs ship based and glider observations in the crs between march and june 2013 capture key features of the transition from winter to summer and depict the impact of the eddy activity on the ebc flow less saline and relatively warmer water of indian ocean origin reaches the crs via the ebc initially an anticyclonic eddy with diameter of 140km penetrating to 150m depth with maximum velocities up to 30 35 cm s 1 prevails in the crs this anticyclonic eddy appears to block or at least redirect the northward flow of the ebc dissipation of the eddy permits the near coastal northward flow of the ebc and gives place to a smaller cyclonic eddy with a diameter of about 50km penetrating to 200m depth by the end of may as the northerly winds become stronger and persistent throughout the basin characteristic of the summer southwest monsoon wind regime the ebc and its associated lower salinity water became less evident replaced by the saltier surface water that characterizes the onset of the summer stratification in the crs

sensitivity of red sea circulation to monsoonal variability during the holocene an integrated data and modeling study received 20 october 2009 revised 6 march 2010 accepted 30 june 2010 published 4 november 2010 1 we used an oceanic general circulation model to evaluate the sensitivity of the hydrography and circulation of the red sea in response to reduced sea level and modified atmospheric conditions during the holocene with holocene sea level close to the modern level the red sea was sensitive to changes in atmospheric conditions and it only shows a relatively mild response to sea level change changes in the monsoon system influence the exchange flow through the strait of bab el mandab the meridional overturning circulation of the red sea and its hydrography forced by humid conditions the modeled red sea temperature increased by 1 5 c while when arid conditions were imposed the temperature decreased by 2 5 c similar heating and cooling events during the early and late holocene are seen in a sea surface temperature record from the northern red sea derived from the temperature sensitive tex86 molecular biomarker which suggests that humid conditions prevailed during the early holocene and more arid conditions prevailed during the late holocene the gradual decline in red sea temperature between these two time periods suggests a gradual decline in the summer monsoon strength this monsoon trend and the resulting changes in the red sea circulation are supported by the distribution of crenarchaea fossil lipids in red sea sediments from this period monsoon driven changes in the exchange flow through the strait of bab el mandab affected the crenarchaea population structure and therefore their molecular fossil distribution in the sediments of the red sea potentially provides an index for the summer monsoon strength during the holocene

palaeozoic early tertiary tethyan evolution of melanges rift and passive margin units in the karaburun peninsula western turkey and chios island greece

topographic preconditioning of open ocean deep convection abstract evidence for oceanic convection over maud rise in the weddell sea suggests that bottom topography may select the location and scale of deep convecting oceanic chimneys forced by seasonal large scale atmospheric cooling in this paper the role of bottom topography in open mean deep convection is studied using an idealized three dimensional primitive equation model a barotropic mean flow impinges on a gaussian shaped seamount in a stratified domain generating a taylor cap a region of topographically trapped fluid uniform surface cooling is applied throughout the domain when the taylor cap is tall enough to interact with the surface mixed layer the local isolation from the advection of heat by the mean flow forms a conduit into the deep water convection within this region is significantly enhanced relative to ambient levels away from the seamount and to similar numerical simulations performed without bottom topography given uniform background stratification domed isopycnals are not importa

magnesium content of non marine ostracod shells a new palaeosalinometer and palaeothermometer abstract ostracods are microcrustaceans with calcitic carapaces each consisting of two valves or shells that grow by moulting and regeneration of sequentially larger valves up to nine times before reaching maturity the mg content of these valves is species dependent and is a function of their growth stage and the temperature salinity mg content and mg ca ratio of their host water newly formed partly calcified valves of the non marine nektic ostracod mytilocypris henricae have high mg contents 100 000 ppm mg in caco3 at individual shell weights of 2 g this relative mg content decreases as calcification proceeds until shell weights exceed 120 g whereupon the mg content is constant and useful as an indicator of the ostracod s environment mg ca ratios in individual ostracod valves from several species of the genera mytilocypris and australocypris from culture experiments and a series of australian lakes indicate that the valve s mg content increases as a function of increasing temperature and salinity within the range 11 25 c and for waters containing 24 2325 ppm mg the molar mg ca ratio in these ostracods fully calcified valves increases by 0 0015 or 370 ppm mg in caco3 per 1 c and per change of 125 ppm mg in solution for most mainland australian lakes a change in water composition of 125 ppm mg corresponds to a change of 3 5 in salinity for a given mg content of a lake the mg ca ratio of the water may vary within the range of common lacustrine values without significantly affecting mg uptake in the ostracod valves these relationships can provide palaeosalinities and or palaeotemperatures for ostracods recovered from continental sediments for mg partitioning an increase in temperature and salinity produce increased mg content in ostracods whereas for 18o fractionation in biogenic calcite an increase in temperature produces a decrease in 18o of the ostracod and an increase in salinity leads to an increase in 18o of the ostracod thus a combination of 18o and mg measurements on non marine ostracods should enable unique resolution of palaeotemperature and palaeosalinity variations

regional effects of the mount pinatubo eruption on the middle east and the red sea the 1991 eruption of mount pinatubo had dramatic effects on the regional climate in the middle east though acknowledged these effects have not been thoroughly studied to fill this gap and to advance understanding of the mechanisms that control variability in the middle east s regional climate we simulated the impact of the 1991 pinatubo eruption using a regional coupled ocean atmosphere modeling system set for the middle east and north africa mena domain we used the coupled ocean atmosphere wave sediment transport coawst framework which couples the weather research and forecasting model wrf model with the regional oceanic modeling system roms we modified the wrf model to account for the radiative effect of volcanic aerosols our coupled ocean atmosphere simulations verified by available observations revealed strong perturbations in the energy balance of the red sea which drove thermal and circulation responses our modeling approach allowed us to separate changes in the atmospheric circulation caused by the impact of the volcano from direct regional radiative cooling from volcanic aerosols the atmospheric circulation effect was significantly stronger than the direct volcanic aerosols effect we found that the red sea response to the pinatubo eruption was stronger and qualitatively different from that of the global ocean system our results suggest that major volcanic eruptions significantly affect the climate in the middle east and the red sea and should be carefully taken into account in assessments of long term climate variability and warming trends in mena and the red sea

physical mechanisms routing nutrients in the central red sea mesoscale eddies and boundary currents play a key role in the upper layer circulation of the red sea this study assesses the physical and biochemical characteristics of an eastern boundary current ebc and recurrent eddies in the central red sea crs using a combination of in situ and satellite observations hydrographic surveys in november 2013 autumn and in april 2014 spring in the crs 22 15 24 1 n included a total of 39 and 27 ctd stations respectively in addition high resolution hydrographic data were acquired in spring 2014 with a towed undulating vehicle scanfish in situ measurements of salinity temperature chlorophyll fluorescence colored dissolved organic matter cdom and dissolved nitrate phosphorous ratios reveal distinct water mass characteristics for the two periods an ebc observed in the upper 150 m of the water column during autumn transported low salinity and warm water from the south toward the crs patches of the low salinity water of southern origin tended to contain relatively high concentrations of chlorophyll and cdom the prominent dynamic feature observed in spring was a cyclonic anticyclonic eddy pair the cyclonic eddy was responsible for an upward nutrient flux into the euphotic zone higher chlorophyll and cdom concentrations and concomitant lower nitrate phosphorous ratios indicate the influence of the ebc in the crs at the end of the stratified summer period

the formation of labrador sea water part i large scale processes abstract data obtained in the western labrador sea during march 1976 by hudson are analysed to show that new labrador sea water was being formed at this time on the basis of hydrographic and moored current meter data it is hypothesized that a 200 km scale cyclonic gyre forms in winter in the western labrador sea and that this gyre retains the developing deep mixed layers in this general area long enough for the transformation to labrador sea water to take place using a model it is demonstrated that water columns found along the western boundary of the labrador sea can be modified by cooling evaporation and mixing to form deep mixed layers with the properties of labrador sea water approximately 105 km3 of new labrador sea water was formed in 1976 an estimate that is consistent with earlier estimates of mean annual production rates this water 2 9 c 34 84 is some 0 6 c cooler and 0 06 fresher than that defined by lazier 1973 from his data collected in 1966 the variation of labrador sea water

lateglacial and holocene variation in aeolian sediment flux over the northeastern tibetan plateau recorded by laminated sediments of a saline meromictic lake predominantly laminated lake sediments from a saline closed basin lake on the northeastern tibetan plateau were investigated using a multi proxy approach 14c accelerator mass spectrometry dating smear slide analysis loss on ignition grain size x ray diffraction elemental concentration ostracod assemblages stable isotopes of ostracod shells to trace the regional environmental and climatic history in the lateglacial and holocene before about 15 cal ka bp small saline water bodies probably filled the basin under unstable cold and harsh environmental conditions soon after about 14 9 cal ka bp a relatively deep saline lake was established probably as a result of runoff from melting snow ice and frozen ground in the lake s catchment large changes in flux of aeolian material to the lake were recorded during this initial period of formation of lake kuhai highest lake levels a low sediment accumulation rate and less saline conditions were maintained between about 12 8 and 7 1 cal ka bp when the aeolian influx diminished significantly after about 7 1 cal ka bp the aeolian influx remained at a moderate level apart from a strongly increased dust delivery to the lake between about 6 1 and 5 4 cal ka bp and a minor short lived period of slightly enhanced aeolian influx at about 2 7 cal ka bp the strongly enhanced dust input to the lake between 6 1 and 5 4 cal ka bp represented the largest influx of aeolian material to lake kuhai during the entire holocene however evidence for climatic deterioration during this period is not seen at most other palaeoclimate sites on the tibetan plateau but instead a significant increase in aridity has been recorded at numerous sites in the northern foreland of the tibetan plateau and on the chinese loess plateau the large dust input to lake kuhai between 6 1 and 5 4 cal ka bp probably did not result from a severe climate deterioration on the tibetan plateau itself but from the pronounced aridity in its northern and eastern foreland in contrast the increase in dust influx about 2 7 cal ka bp seems to correspond to a brief warming spell recorded at other sites on the tibetan plateau too a slight increase in lake level and decrease in salinity after about 0 6 cal ka bp suggests a slightly higher effective moisture during the final lake stage accompanied by a somewhat larger dust influx this apparent contradiction possibly results from enhanced human activities on the northeastern tibetan plateau during the last 600 years copyright 2009 john wiley sons ltd

seasonal overturning circulation in the red sea 1 model validation and summer circulation the overturning circulation in the red sea exhibits a distinct seasonally reversing pattern and is studied using high resolution mit general circulation model simulations in the first part of this study the vertical and horizontal structure of the summer overturning circulation and its dynamical mechanisms are presented from the model results the seasonal water exchange in the strait of bab el mandeb is successfully simulated and the structures of the intruding subsurface gulf of aden intermediate water are in good agreement with summer observations in 2011 the model results suggest that the summer overturning circulation is driven by the combined effect of the shoaling of the thermocline in the gulf of aden resulting from remote winds in the arabian sea and an upward surface slope from the red sea to the gulf of aden set up by local surface winds in the red sea in addition during late summer two processes associated respectively with latitudinally differential heating and increased salinity in the southern red sea act together to cause the reversal of the contrast of the vertical density structure and the cessation of the summer overturning circulation dynamically the subsurface northward pressure gradient force is mainly balanced by vertical viscosity resulting from the vertical shear and boundary friction in the strait of bab el mandeb unlike some previous studies the three layer summer exchange flows in the strait of bab el mandeb do not appear to be hydraulically controlled

observations of the summer red sea circulation 1 aiming at exploring and understanding the summer circulation in the red sea a cruise was conducted in the basin during the summer of 2001 involving hydrographic meteorological and direct current observations the most prominent feature characteristic of the summer circulation and exchange with the indian ocean is a temperature salinity and oxygen minimum located around a depth of 75 m at the southern end of the basin associated with gulf of aden intermediate water inflowing from the gulf of aden during the summer season as an intruding subsurface layer stirring and mixing with ambient waters lead to marked increases in temperature from 16 5 to almost 33 c and salinity from 35 7 to more than 38 psu in this layer by the time it reaches midbasin the observed circulation presents a very vigorous pattern with strong variability and intense features that extend the width of the basin a permanent cyclone detected in the northern red sea verifies previous observations and modeling studies while in the central sector of the basin a series of very strong anticyclones were observed with maximum velocities exceeding 1 m s the three layer flow pattern representative of the summer exchange between the red sea and the gulf of aden is observed in the strait of bab el mandeb in the southern part of the basin the layer flow is characterized by strong banking of the inflows and outflows against the coasts both surface and intermediate water masses involved in the summer red sea circulation present prominent spatial variability in their characteristics indicating that the eddy field and mixing processes play an important role in the summer red sea circulation

the characteristics and dynamics of wave driven flow across a platform coral reef in the red sea current dynamics across a platform reef in the red sea near jeddah saudi arabia are examined using 18 months of current profile pressure surface wave and wind observations the platform reef is 700 m long 200 m across with spatial and temporal variations in water depth over the reef ranging from 0 6 to 1 6 m surface waves breaking at the seaward edge of the reef cause a 2 10 cm setup of sea level that drives cross reef currents of 5 20 cm s 1 bottom stress is a significant component of the wave setup balance in the surf zone over the reef flat where waves are not breaking the cross reef pressure gradient associated with wave setup is balanced by bottom stress the quadratic drag coefficient for the depth average flow decreases with increasing water depth from cda 0 17 in 0 4 m of water to cda 0 03 in 1 2 m of water the observed dependence of the drag coefficient on water depth is consistent with open channel flow theory and a hydrodynamic roughness of zo 0 06 m a simple one dimensional model driven by incident surface waves and wind stress accurately reproduces the observed depth averaged cross reef currents and a portion of the weaker along reef currents over the focus reef and two other red sea platform reefs the model indicates the cross reef current is wave forced and the along reef current is partially wind forced

on the crossover of boundary currents in an idealized model of the red sea the west to east crossover ofboundarycurrents has been seen in mean circulationschemes fromseveral past models of the red sea this study investigates the mechanisms that produce and control the crossover in an idealized eddy resolving numerical model of the red sea the authors also review the observational evidence and derive an analytical estimate for the crossover latitude the surface buoyancy loss increases northward in the idealized model and the resultant mean circulation consists of an anticyclonic gyre in the south and a cyclonicgyreinthenorth in themidbasin thenorthwardsurfaceflow crossesfromthewestern boundarytothe eastern boundary numerical experiments with different parameters indicate that the crossover latitude of the boundary currents changes with f0 b and the meridional gradient of surface buoyancy forcing in the analytical estimate which is based on quasigeostrophic b plane dynamics the crossover is predicted to lie at the latitude where the net potential vorticity advection including an eddy component is zero various terms in the potential vorticity budget can be estimated using a buoyancy budget a thermal wind balance and a parameterization of baroclinic instability

zonal surface wind jets across the red sea due to mountain gap forcing along both sides of the red sea 1 mesoscale atmospheric modeling over the red sea validated by in situ meteorological buoy data identifies two types of coastal mountain gap wind jets that frequently blow across the longitudinal axis of the red sea 1 an eastward blowing summer daily wind jet originating from the tokar gap on the sudanese red sea coast and 2 wintertime westward blowing wind jet bands along the northwestern saudi arabian coast which occur every 10 20 days and can last for several days when occurring both wind jets can attain wind speeds over 15 m s 1 and contribute significantly to monthly mean surface wind stress especially in the cross axis components which could be of importance to ocean eddy formation in the red sea the wintertime wind jets can cause significant evaporation and ocean heat loss along the northeastern red sea coast and may potentially drive deep convection in that region an initial characterization of these wind jets is presented

paleoecology of limnic ostracodes a review of some major topics abstract the paleoecology of limnic ostracodes is reviewd in the context of the evolution of their environment in order to understand why there is a rich ostracode fossil record we examine data such as the quantitative and qualitative distribution of living ostracode species and ostracode assemblages ways of describing and limitations importance of biological and physico chemical factors for the local accumulation of high numbers of ostracodes and diversified assemblages is emphasized we discuss the limits of extrapolations of information from ecology to paleocology we stress how paleontological knowledge can be applied to neontological studies the possibility of using holocene ostracodes as indicators of morphometric changes of lakes temperature salinity eutrophication and as a criterion of meromictic conditions is demonstrated relationships between ostracodes and the chemical environment and particularly the morphological response of the carapace are considered e g diversity and qualitative composition of assemblages and chemical stability types of carapace mineralization and ornamentation and chemistry of bottom waters these ideas developed from studies on recent material are tested for limnic cenozoic faunas in the mesozoic the main questions arising from the study of nonmarine ostracodes deal with the possible evaluation of paleosalinities in marginal lagoonal environments purbeck wealden and with evaluation of depth and hydrochemical and paleoclimatological regime in truly lacustrine intracratonic basins some peculiarities of paleozoic nonmarine ostracode assemblages are described the paleoecological cause of changes in diversity of several ostracode groups in the carboniferous and permian is emphasized

observations of vertical currents and convection in the central greenland sea during the winter of 1988 1989 during the winter of 1988 1989 five acoustic doppler current profilers adcps were moored in the central greenland sea to measure vertical currents that might occur in conjunction with deep mixing and convection two adcps were looking up from about 300 m and combined with thermistor strings in the depth range 60 260 m two were looking downward from 200 m and one was looking upward from 1400 m first maxima of vertical velocity variance occurred at two events of strong cold winds in october and november when cooling and turbulence in the shallow mixed layer generated internal waves in the thermocline beginning in late november the marginal ice zone expanded eastward over the central greenland sea reaching its maximum extent in late december in mid january a bay of ice free water opened over the central greenland sea leaving a wedge of ice the is odden curled around it along the axis of the jan mayen current and then northeastward and existing well into april 1989 below the ice a mixed layer at freezing temperatures developed that increased in thickness from 60 to 120 m during the period of ice cover corresponding to an average heat loss of about 40 w m 2 through brine rejection mixed layer salinity increased steadily reducing stability to underlying weakly stratified layers roach et al 1993 during the ice cover period vertical currents were at a minimum after the opening of the ice free bay successive mixed layer deepening to 350 m occurred in conjunction with cooling events around february 1 and 15 accompanied by strong small scale vertical velocity variations upward mixing of more saline waters of atlantic origin during this phase reduced the stability further generating a pool of homogeneous water of 50 km horizontal extent in the central greenland sea preconditioned for subsequent convection to greater depths individual convection events were observed during march 6 16 associated with downward velocities at the 1400 m level of about 3 cm s l one event was identified as a plume of about 300 m horizontal scale in agreement with recently advanced scaling arguments and model results and with earlier similar observations in the gulf of lions western mediterranean the deep convection occurred in the center of the ice free bay hence brine rejection did not seem necessary for its generation plume temperatures at 1400 m were generally higher than that of the homogeneous surface pool suggesting entrainment of surrounding warmer waters on the way down mean vertical velocity over a period of convection events was indistinguishable from zero suggesting that plumes served as a mixing agent rather than causing mean downward transport of water masses however different from the surface pool that was governed by mixed layer physics the water between 400 and 1400 m was not horizontally homogenized in a large patch by the sporadic plumes overall and compared to results from the gulf of lions convection activity in the central greenland sea was weak and limited to intermediate depths in winter 1988 1989

baroclinic tides simulation in the red sea comparison to observations and basic characteristics the author would like to thank james h churchill larry pratt and jim thomas for the discussions and help the topography data are derived from general bathymetric chart of the oceans gebco https www gebco net the initial salinity and temperature is extracted from world ocean atlas 2009 woa09 https www nodc noaa gov oc5 woa09 pr woa09 html the barotropic tidal boundary currents and the spatial distribution of elevation amplitudes and phases are derived from tpxo 7 2 inverse model http volkov oce orst edu tides global html the mitgcm model output data files sea level data from gauges and mooring data can be found at figshare https figshare com projects data for b2018jc013970 bc redsea 57407 the research reported in this manuscript was supported by king abdullah university of science and technology this research made use of the resources from the supercomputing laboratory and or computer clusters at king abdullah university of science and technology

energetics of semienclosed basins with two layer flows at the strait examination of the energy budget for semienclosed seas with two layer exchange flow at the strait shows that the energy flux at the open portion of the boundary the strait is proportional to the surface buoyancy fluxintegratedoverthebasinarea withtheconstantofproportionalitygivenbytheinterfacedepth whenthe surface buoyancy flux is positive the energy flux is negative these types of basins have an estuarine circulation antiestuarine basins have a negative surface buoyancy flux which provides a positive energy flux augmenting the wind work in powering the circulation the energy budget for the semienclosed seas with vertically separated flows at the strait is examined using reanalysis products for four major semienclosed basins the mediterranean and red seas antiestuarine and the black and baltic seas estuarine important differencesintherelativecontributiontotheenergybudgetofthewindworkversusthesurfacebuoyancyflux are found within basins of the same type and these differences help explain some qualitative aspects of the basins flow

seasonal overturning circulation in the red sea 2 winter circulation author posting 0american geophysical union 2014 this article is posted here by permission of american geophysical union for personal use not for redistribution the definitive version was published in journal of geophysical research oceans 119 2014 2263 2289 doi 10 1002 2013jc009331

westward mountain gap wind jets of the northern red sea as seen by quikscat abstract we analyse ten years of quikscat satellite surface winds to statistically characterize the spatio temporal variability of the westward mountain gap wind jets over the northern red sea these wind jets bring relatively cold and dry air from the arabian desert increasing heat loss and evaporation over the region similar to cold air outbreaks from mid and subpolar latitudes quikscat captures the spatial structure of the wind jets and agrees well with in situ observations from a heavily instrumented mooring in the northern red sea the local linear correlations between quikscat and in situ winds are 0 96 speed and 0 85 direction quikscat also reveals that cross axis winds such as the mountain gap wind jets are a major component of the regional wind variability the cross axis wind pattern appears as the second or third mode in the four vector empirical orthogonal function analyses we performed explaining between 6 to 11 of the wind variance westward wind jets are typical in winter especially in december and january but with strong interannual variability several jets can occur simultaneously and cover a large latitudinal range of the northern red sea which we call large scale westward events quikscat recorded 18 large scale events over ten years with duration between 3 to 8 days and strengths varying from 3 4 to 9 10 m s these events cause large changes in the wind stress curl pattern imposing a remarkable sequence of positive and negative curl along the red sea main axis which might be a wind forcing mechanism for the oceanic mesoscale circulation