upper ocean response to typhoon choi wan as measured by the kuroshio extension observatory mooring 1 the kuroshio extension observatory keo is a highly instrumented moored reference station located at 32 3 n 144 5 e in the recirculation gyre south of the kuroshio extension on 19 september 2009 the eye of typhoon choi wan international designation 0914 passed 40 km to the southeast of the keo surface mooring hourly meteorological and physical oceanographic measurements together with 3 hourly air sea carbon dioxide observations telemetered from keo in near real time show the evolution of the upper ocean and its associated air sea fluxes during the passage of this storm and its aftermath during the approach of the storm the mixed layer freshened because of intense rainfall this was followed by a large outgassing of co2 rapid cooling and an increase in salinity although these changes in mixed layer properties imply substantial entrainment they were accompanied by upwelling and ultimately a temporary 20 m shoaling of the mixed layer this upwelling which was observed at all depths including the deepest sensor near 500 m was coincident with the onset of near inertial oscillations in the mixed layer currents after the typhoon passed inertial pumping caused 15 20 m amplitude vertical displacements throughout the top 500 m that continued for at least 6 days a large oceanic response was observed in this case even though the eye of choi wan passed to the right of keo resulting in winds rotating cyclonically with time in opposition to the anticyclonic rotating near inertial currents

two phytoplankton blooms near luzon strait generated by lingering typhoon parma two phytoplankton blooms near luzon strait triggered by typhoon parma in 2009 were investigated using remote sensing data and in situ observations parma was slow moving a translation speed of similar to 2ms 1 and relatively weak a maximum sustained wind of similar to 30ms 1 during its lingering path northwest of luzon island after it reached a point 120 5 degrees e 20 3 degrees n west of luzon strait parma turned sharply back toward the northern philippines along approximately the same course such long similar to 7days lingering typhoons are rather rare in the south china sea scs before parma low chl a concentrations 0 6mgm 3 appeared west of the central luzon strait a nearshore phytoplankton increase was also observed north of luzon island together with high cdom color dissolved organic matter during and after the typhoon sea surface cooling similar to 3 degrees c stronger wind 20ms 1 and heavy rainfall 100mmday 1 were seen in the above regions the offshore bloom occurred where parma s translation speed was the slowest similar to 1ms 1 it may be caused primarily by the ekman pumping which brought nutrients upward to the euphotic zone and also by the entrainment mixing the nearshore bloom may be triggered by the heavy typhoon induced rainfall which supplied nutrients for the coast region north of luzon island the rapid increase of cdom in the nearshore region implied that terrestrial input may be the source of nutrients

analyses and simulations of the upper ocean s response to hurricane felix at the bermuda testbed mooring site 13 23 august 1995 causedalargeincreaseinkineticenergyatnear inertialfrequencies internalgravitywavesin the thermocline and inertial pumping mixed layer deepening and significant vertical redistribution of heat with cooling of the upper 30 m and warming at depths of 30 70 m the temperature evolution was simulated using four one dimensional mixed layer models price weller pinkel pwp k profile parameterization kpp mellor yamada 2 5 my and a modified version of my2 5 my2 the primary differences in the model results were in their simulations of temperature evolution in particular when forced using a drag coefficient thathadalinear dependenceonwindspeed the kppmodelpredicted seasurface cooling mixed layer currents and the maximum depth of cooling closer to the observations than any of the other models this was shown to be partly because of a special parameterization for gradient richardson number rgkpp shear instability mixing in responsetoresolvedshearintheinterior themy2modelpredictedmoreseasurfacecooling and greater depth penetration of kinetic energy than the my model in the my2 model the dissipation rate of turbulent kinetic energy is parameterized as a function of a locally defined richardson number rgmy2 allowing for a reduction in dissipation rate for stable richardsonnumbers rgmy2 wheninternalgravitywavesarelikelytobepresent sensitivity simulations with the pwp model which has specifically defined mixing procedures show that most of the heat lost from the upper layer was due to entrainment parameterized as a function of bulk richardson number rbpwp with the remainder due to local richardson number rgpwp instabilities with the exception of the my model the models predicted reasonable estimates of the north and east current components during and after the hurricane passage at 25 and 45 m although the results emphasize differences between the modeled responsestoagivenwindstress currentcontroversyovertheformulationofwindstressfrom wind speed measurements including possible sea state and wave age and sheltering effects cautions against using our results for assessing model skill in particular sensitivity studies show that my2 simulations of the temperature evolution are excellent when the wind stress is increased albeit with currents that are larger than observed sensitivity experiments also indicate that preexisting inertial motion modulated the amplitude of poststormcurrents butthattherewasprobablynotasignificantresonantresponsebecauseof clockwise wind rotation for our study site index terms 4504 oceanography physical air sea interactions 0312 4572 oceanography physical upper ocean processes 4255 oceanography general numericalmodeling 4544oceanography physical internalandinertialwaves keywords hurricane tropical cyclone mixed layer modeling upper ocean processes inertial currents ocean storms

observation based estimates of surface cooling inhibition by heavy rainfall under tropical cyclones tropical cyclones drive intense ocean vertical mixing that explains most of the surface cooling observed in their wake the cold wake in this paper the authors investigate the influence of cyclonic rainfall on the cold wake at a global scale over the 2002 09 period for each cyclone the cold wake intensity and accumulated rainfall are obtained from satellite data and precyclone oceanic stratification from the global eddy permitting ocean reanalysis glorys2 the impact of precipitation on the cold wake is estimated by assuming that cooling is entirely due to vertical mixing and that an extra amount of energy corresponding to the energy used to mix the rain layer into the ocean would be available for mixing the ocean column in the hypothetical case with no rain the positive buoyancy flux of rainfall reduces the mixed layer depth after the cyclone passage hence reducing cold water entrainment the resulting reduction in cold wake amplitude is generally small median of 0 07 k for a median 1 k cold wake but not negligible 19 for 10 of the cases despite similar cyclonic rainfall the effect of rain on the cold wake is strongest in the arabian sea and weak in the bay of bengal an analytical approach with a linearly stratified ocean allows attributing this difference to the presence of barrier layers in the bay of bengal the authors also show that the cold wake is generally a salty wake because entrainment of subsurface saltier water overwhelms the dilution effect of rainfall finally rainfall temperature has a negligible influence on the cold wake

the 3d oceanic mixed layer response to hurricane gilbert upper ocean heat and mass budgets are examined from three snapshots of data acquired during and after the passage of hurricane gilbert in the western gulf of mexico measurements prior to storm passage indicated a warm core eddy in the region with velocities of o 1 m s21 based upon conservation of heat and mass the threedimensional mixed layer processes are quantified from the data during and subsequent to hurricane passage horizontal advection due to geostrophic velocities is significant in the eddy regime suggesting that prestorm oceanic variability is important when background flows have the same magnitude as the mixed layer current response storm induced near inertial currents lead to large vertical advection magnitudes as they diverge from and converge toward the storm track surface fluxes estimated by reducing flight level winds to 10 m indicate a maximum wind stress of 4 2 n m22 and a heat flux of 1200 w m 22 in the directly forced region the upward heat flux after the passage of the storm has a maximum of 200 w m22 corresponding to a less than 7 m s21 wind speed entrainment mixing across the mixed layer base is estimated using three bulk entrainment closure schemes that differ in their physical basis of parameterization entrainment remains the dominant mechanism in controlling the heat and mass budgets irrespective of the scheme depending on the magnitudes of friction velocity surface fluxes and or shear across the mixed layer base the pattern and location of maximum entrainment rates differ in the directly forced region while the general area of maximum entrainment is in the right rear quadrant of the storm shear induced entrainment scheme predicts a narrow region of cooling compared to the the stressinduced mixing scheme and observed sst decreases after the storm passage the maximum contribution to the mixed layer dynamics is associated with shear induced entrainment mixing forced by near inertial motions up to the third day as indicated by bulk richardson numbers that remained below criticality thus entrainment based on a combination of surface fluxes friction velocity and shear across the entrainment zone may be more relevant for three dimensional ocean response studies

dynamic and thermal responses of the kuroshio to typhoon megi 2004 relatively weak hurricane induced cooling 1 c is often observed in the loop current while observed sea surface temperature sst cooling is much stronger in the kuroshio this was previously attributed to strong advection effects by the loop current based on a budget analysis this study quantitatively diagnoses the dynamic and thermal responses of the kuroshio to typhoon megi and four additional tropical cyclones tcs which produce up to 3 c sst cooling within the kuroshio itself the results show that the surface thermal response of the kuroshio is a wind induced temperature cooling primarily due to vertical mixing up to 96 the dynamic response of the kuroshio depends not only on tc conditions intensity and wind direction but also on prestorm ocean conditions e g ocean mixed layer depth baroclinicity and current velocity differently from the open ocean where the ocean gains kinetic energy mainly from wind stress work the kuroshio can obtain greater kinetic energy from its baroclinic pressure work especially in the upper ocean the strong sst cooling observed in the kuroshio region is therefore likely associated with the kinetic energy extracted from the kuroshio baroclinic potential energy which greatly enhances local vertical mixing

upper ocean temperature response to hurricane felix as measured by the bermuda testbed mooring hurricane felix passed over the bermuda testbed mooring on 15 august 1995 providing a unique opportunity to observe the response of the upper ocean to a hurricane in the vicinity of bermuda felix was a particularly large hurricane with hurricane force winds over a diameter of about 300 400 km and tropical storm force winds over a diameter of about 650 800 km felix moved northwestward at about 25 km h21 with the eye passing about 65 km southwest of the mooring on 15 august peak winds reached about 135 km h21 at the mooring complementary satellite sea surface temperature maps show that a swath of cooler water by about 3 58 4 08c was left in the wake of felix with the mooring in the center of the wake prior to the passage of felix the mooring site was undergoing strong heating and stratification however this trend was dramatically interrupted by the passage of the hurricane as felix passed the mooring large inertial currents speeds of 100 cm s 21 at 25 m were generated within the upper layer the e folding decay timescale of the inertial currents was about 9 days the mixed layer depth was about 15 m before the arrival of felix and deepened to about 45 m within three days after felix s passage the temperature at 25 m decreased by approximately 3 5 8 4 08c large amplitude temperature oscillations 1 58c near the inertial period inertial pumping effect were set up by the hurricane in the seasonal thermocline resulting in vertical displacements of isotherms of approximately 15 m at 60 70 m comparative scale analyses of the upper ocean responses to hurricane felix and hurricane gloria 1985 indicate that they have several similarities

observations of the response of thermocline currents to a hurricane abstract in september 1985 the eye of hurricane gloria passed within about 100 km of a current meter mooring in the western north atlantic data from this mooring provide a clear view of the vertical structure of the near inertial wake in the main thermocline the response at 159 m was strong 25 cm s 1 amplitude and lasted about 18 days at greater depths the response was weaker and more irregular the phase of the near inertial currents increased with depth consistent with the downward spreading of enemy the total phase change across the thermocline reached about a half cycle seven days after the hurricane s passage indicating a large vertical scale of the response the observations are briefly compared with other time series measurements on the continental margin and with models

pge enrichment in chromitite layers and the merensky reef of the western bushveld complex a re os and rb sr isotope study abstract four poikilitic pyroxenites of the bastard unit all being relatively low in osmium concentrations define a re os isochron age of 2043 11 ma with initial 187os 188os 0 151 which is in accordance with the normally cited crystallization age of the bushveld complex the isochron fit demonstrates an excellent radiogenic os isotopic homogeneity of this portion of the complex at the time of crystallization and excludes any later disturbance of the re os isotope system initial 187os 188os ratios of platinum group element pge enriched sulfides and whole rocks of the directly underlying merensky reef are highly radiogenic and variable with values between 0 168 and 0 181 separates of chromite grains and interstitial phases of critical zone chromitite layers show initial 187os 188os signatures ranging from the near chondritic mantle values of lower group chromitites i e 0 120 to 0 137 for middle group chromitites and to 0 150 for the upper group 2 chromitite layer osmium concentrations of interstitial phases exceed those of the associated chromite in all layers by up to 30 fold showing the presence of highly pge enriched interstitial sulfides equal or very similar initial 187os 188os signatures of the interstitial minerals and the cumulus chromite grains together with their coupled increasing and decreasing trends in this ratio clearly demonstrate that interstitial sulfides and associated cumulus chromite of the different chromitite layers scavenged their osmium from the same or similar sources therefore a pge enrichment of the interstitial sulfides by a primary magmatic process such as precipitation of immiscible sulfide droplets during magma mixing appears more likely than a scenario involving fluid or melt transport of pge into these layers such a primary magmatic pge enrichment process is also preferred for the formation of the merensky reef

observations of strong inertial oscillations after the passage of tropical cyclone ofa one week after tropical cyclone ofa passed near samoa near inertial oscillations of almost 1 m s 1 in amplitude were observed with a shipboard acoustic doppler current profiler adcp the velocity was nearly uniform with depth in the upper 80 m the strongest currents in this layer were found about 300 km from ofa s track farther than expected from previous observations and models below 80 m was a layer 50 100 m thick in which the shear exceeded 0 01 s 1 strong near inertial oscillations with currents over 0 6 m s 1 from 130 to 200 m extended through the shear layer to at least 300 m the limit of the adcp measurements the phase of the oscillations propagated upward consistent with downward propagation of energy a simple slab model driven by an idealized wind field approximately matches the observed amplitude and phase of the oscillations in the surface layer within 150 km of ofa s track but not the stronger current 300 km from the track

cold wake of hurricane frances 1 an array of instruments air deployed ahead of hurricane frances measured the three dimensional time dependent response of the ocean to this strong 60 ms 1 storm sea surface temperature cooled by up to 2 2 c with the greatest cooling occurring in a 50 km wide band centered 60 85 km to the right of the track the cooling was almost entirely due to vertical mixing not air sea heat fluxes currents of up to 1 6 ms 1 and thermocline displacements of up to 50 m dispersed as near inertial internal waves the heat in excess of 26 c decreased behind the storm due primarily to horizontal advection of heat away from the storm track with a small contribution from mixing across the 26 c isotherm sst cooling under the storm core 0 4 c produced a 16 decrease in air sea heat flux implying an approximately 5 ms 1 reduction in peak winds

response of sea surface properties to hurricane dennis in the eastern gulf of mexico 1 sea surface reflectance ssr and sea surface temperature sst were assessed in the eastern gulf of mexico in early july 2005 after passage of hurricane dennis a category 4 storm using data from the modis seawifs and avhrr satellite sensors historical hydrographic and nutrient surveys and a simple vertical water column mixing model the bathymetric gradient across the shelf break the offshore deep nutricline and nearby loop current eddies led to unique ssr and sst changes after the passage of dennis in waters shallower than 50 m a strong sediment resuspension event led to higher ssr in the visible and an increase in the modis fluorescence line height flh these variables returned to pre storm conditions after about 10 days the flh change indicates increasing biomass in the short response time 50 m deep cooled down significantly but there was no apparent change in ssr presumably because the nutricline was too deep to be affected by vertical mixing due to the storm the three dimensional hydrographic and nutrient structure in waters near the west florida shelf defines what changes may be detected at the surface with remote sensing

directional wind wave coupling in fully coupled atmosphere wave ocean models results from cblast hurricane abstractthe extreme high winds intense rainfall large ocean waves and copious sea spray in hurricanes push the surface exchange parameters for temperature water vapor and momentum into untested regimes the coupled boundary layer air sea transfer cblast hurricane program is aimed at developing improved coupling parameterizations using the observations collected during the cblast hurricane field program for the next generation hurricane research prediction models hurricane induced surface waves that determine the surface stress are highly asymmetric which can affect storm structure and intensity significantly much of the stress is supported by waves in the wavelength range of 0 1 10 m which is the unresolved spectral tail in present wave models a directional wind wave coupling method is developed to include effects of directionality of the wind and waves in hurricanes the surface stress vector is calculated using the two dimensional wave spectra from a wave model with an added short wave s

the bay of bengal upper ocean response to tropical cyclone forcing during 1999 1 the regional upper ocean dynamical and thermodynamical responses to two consecutive strong tropical cyclones tcs 04b 15 19 october and 05b 25 october to 3 november in 1999 hereafter tc1 and tc2 in the bay of bengal bob and the associated oceanic processes are investigated using an eddy permitting hybrid coordinate ocean model the tc winds induce positive sea surface height anomalies ssha along the northern bob coastline and andaman sea due to onshore convergence and negative ssha along the tc tracks due to ekman divergence which in turn induce geostrophic flow the tc associated radiation and precipitation have negligible effects on the northwestern bob top 30 m averaged temperature t0 30 m while the strong tc winds significantly enhance turbulent heat flux causing t0 30 m decrease due to the existence of the barrier layer and subsurface warm advection in the northwestern bob vertical mixing may induce near surface warming by entraining warm water from below as a result the proportion of the t0 30 m cooling caused by turbulent heat flux is likely elevated in the 6 6 footprints of the tcs both tc wind induced vertical mixing and upwelling significantly cool t0 30 m in tc1 s wake while upwelling dominates the maximum cooling region in tc2 s wake likely due to the preceding deepening of the mixed layer by tc1 the near surface cooling for both tcs has rightward bias because of the higher winds and the resonant response on the right and ekman divergence extends the cooling areas outward tc1 and tc2 s sizes and prestorm oceanic conditions are found to be the most influential factors for near surface cooling

advective spreading of storm induced inertial oscillations in a model of the northwest atlantic ocean the spreading of inertial oscillations induced by the passage of hurricane juan 2003 across the gulf stream and the scotian shelf is examined using a regional model of the northwest atlantic ocean it is found that surface intensified inertial oscillations develop at locations remote from the storm track after a period of 5 10 days a diagnostic technique reveals the importance of advection by the background geostrophic flow for explaining this effect the results suggest that advection by mean circulation can play a role in redistributing near inertial energy in the ocean we argue that advective redistribution could have important consequences for understanding diapycnal mixing in the ocean

forced stage response to a moving hurricane abstract the upper ocean s response to three hurricanes norbert 1984 josephine 1984 and gloria 1985 is examined using field observations and a numerical ocean model our goal is to describe the physical processes that determine the structure and amplitude of hurricane driven upper ocean currents all three of these northern hemisphere hurricanes produced a rightward biased response of the mixed layer current and transport this asymmetry arises because the wind stress vector rotates clockwise on the right side of the track and remains nearly parallel with the inertially rotating mixed layer current during most of the hurricane passage the maximum observed mixed layer current varied from 0 8 m s 1 in response to josephine which was a large but comparatively weak hurricane to 1 7 m s 1 in response to gloria which was very large and also intense these cases have been simulated with a three dimensional numerical model that includes a treatment of wind driven vertical mixing within the primitive

observations of the cold wake of typhoon fanapi 2010 1 several tens of thousands of temperature profiles are used to investigate the thermal evolution of the cold wake of typhoon fanapi 2010 typhoon fanapi formed a cold wake in the western north pacific ocean on 18 september characterized by a mixed layer that was 2 5 c cooler than the surrounding water and extending to 80 m twice as deep as the preexisting mixed layer the initial cold wake became capped after 4 days as a warm thin surface layer formed the thickness of the capped wake defined as the 26 c 27 c layer decreased approaching the background thickness of this layer with an e folding time of 23 days almost twice the e folding lifetime of the sea surface temperature sst cold wake 12 days the wake was advected several hundreds of kilometers from the storm track by a preexisting mesoscale eddy the observations reveal new intricacies of cold wake evolution and demonstrate the challenges of describing the thermal structure of the upper ocean using sea surface information alone

depositional environments of the pleistocene loess soil series inferred from sand grain morphoscopy a case study of the east european plain abstract morphoscopy of sand grains from the late pleistocene loess paleosol series exposed on the east european plain along a longitudinal profile from the southern limit of the late pleistocene ice sheet to the azov sea coasts is examined the data presented refer to three main zones of the loess accumulation different in characteristics of the processes the northern zone including the vicinity of the valdai ice sheet the middle zone with the maximum sedimentation rate and the southern zone adjoining seacoasts the earlier part of the valdai glacial epoch before the bryansk interstadial was distinct for a rather moderate rate of subaerial processes without any noticeable spatial differentiation with respect to the latitudinal zones in post bryansk time after 24 ka bp the most active dust accumulation is recorded in the middle zone the maximum thickness of the late pleistocene loess has been recorded there in the middle reaches of the dnieper river in the northern zone the rate of dust settling was not so high presumably due to high speed of descending winds from the ice sheet in the southern periglacial zone aeolian abrasion of sand grains was less pronounced as compared with areas farther to the north

seasonal and interannual variability in deep ocean particle fluxes at the oceanic flux program ofp bermuda atlantic time series bats site in the western sargasso sea near bermuda abstract since 1978 the oceanic flux program ofp time series sediment traps have measured particle fluxes in the deep sargasso sea near bermuda there is currently a 20 yr flux record at 3200 m depth a 12 yr flux at 1500 m depth and a 9 yr record at 500 m depth strong seasonality is observed in mass flux at all depths with a flux maximum in february march and a smaller maximum in december january there is also significant interannual variability in the flux especially with respect to the presence absence of the december january flux maximum and in the duration of the high flux period in the spring the flux records at the three depths are surprisingly coherent with no statistically significant temporal lag between 500 and 3200 m fluxes at our biweekly sample resolution bulk compositional data indicate an extremely rapid decrease in the flux of organic constituents with depth between 500 and 1500 m and a smaller decrease with depth between 1500 and 3200 m depth in contrast carbonate flux is uniform or increases slightly between 500 and 1500 m possibly reflecting deep secondary calcification by foraminifera the lithogenic flux increases by over 50 between 500 and 3200 m depth indicating strong deep water scavenging repackaging of suspended lithogenic material concurrent with the rapid changes in flux composition there is a marked reduction in the heterogeneity of the sinking particle pool with depth especially within the mesopelagic zone by 3200 m depth the bulk composition of the sinking particle pool is strikingly uniform both seasonally and over variations in mass flux of more than an order of magnitude these ofp results provide strong indirect evidence for the intensity of reprocessing of the particle pool by resident zooplankton within mesopelagic and bathypelagic waters the rapid loss of organic components the marked reduction in the heterogeneity of the bulk composition of the flux and the increase in terrigenous fluxes with depth are most consistent with a model of rapid particle turnover and material scavenging from the suspended pool during new particle formation we suggest that much of the deep mass flux is generated in situ by deep dwelling zooplankton and that mass flux as well as scavenging of suspended materials from the deep water column varies in proportion to changes in grazer activity labile very rapidly sinking aggregates e g salp fecal material arriving in the bathypelagic zone within days of their upper ocean production may act to stimulate zooplankton grazing rates and increase large particle production and deep mass flux days to weeks in advance of the arrival of bulk of surface produced material this process could reconcile mean particle sinking rate estimates with the phase coherence observed between upper and deep ocean mass fluxes

satellite measurements of sea surface cooling during hurricane gloria hurricanes and other strong storms can cause important decreases in sea surface temperature by means of vertical mixing within the upper ocean and by air sea heat exchange here we use satellite derived infrared images of the western north atlantic to study sea surface cooling caused by hurricane gloria 1985 significant regional variations in sea surface cooling are well correlated with hydrographic conditions the greatest cooling up to 5 c occurred in slope waters north of the gulf stream where the seasonal thermocline is shallowest and most compressed moderate cooling up to 3 c occurred in the open sargasso sea where the thermocline is deeper and more diffused little or no cooling occurred in shallow coastal waters bottom depth less than 20 m which were isothermal before the passage of hurricane gloria there is a pronounced right side asymmetry of sea surface cooling with stronger by a factor of 4 and more extensive by a factor of 3 cooling found on the right side of the hurricane track these qualitative results are consistent with the notion that vertical mixing within the upper ocean is the dominant sea surface cooling mechanism of hurricanes

formation processes at sites with high resolution sequences in the crimean middle paleolithic the kabazi v rock shelter and the open air site of kabazi ii compared abstract several paleolithic sites in the crimea are characterized by long stratigraphic sequences with numerous thin in situ archaeological horizons in this case study we compare two neighboring sites at kabazi mountain parts of whose sequences are contemporaneous for similarities and differences in their site formation processes during ois 3 at kabazi ii 15 m of mainly colluvial sediments accumulated behind a huge limestone block differences in the dynamics of the colluvial sedimentation led to archaeological horizons preserved in situ and assemblages moving downslope into the excavation area periods of stability due to vegetation cover upslope made soil formation processes possible kabazi v is a buried rock shelter with a different sedimentological setting here sediments were built up by the dissolution of soft nummulitic limestone and influenced by running water and are in part sandwiched between massive rock fall despite the differences in site type the deposits of both sites are characterized by autochthonous inside and allochthonous outside deposits in both cases the preservation of deposits is due to their protection by large rock fall mean annual sedimentation rates show that the archaeological resolution of the sequences is more a consequence of recurrent human use over long periods than of high absolute sedimentation rates the average time elapsing in each case between the archaeological layers indicates that the base camp of kabazi v was more frequently used by neanderthals than the kill and butchering site of kabazi ii this suggests long term persistence of the site catchment criteria applied at kabazi mountain and an important role for base camps in the crimean middle paleolithic perception of landscape

effect of typhoon kalmaegi 2014 on northern south china sea explored using muti platform satellite and buoy observations data abstract based on observational data from a buoy mooring array and satellite remote sensing data for sea surface winds temperature and height during the passage of typhoon kalmaegi 2014 a systematic analysis is performed on the atmospheric and oceanic variables of winds sea level air pressure surface air temperature sensible and latent heat fluxes rainfall water temperature salinity and ocean currents kalmaegi passed through the south china sea scs with a mean non dimensional speed of 2 87 typical of a fast moving storm with a predominantly baroclinic oceanic response in addition to some well documented response features such as rightward biased intensifications in sea surface cooling and currents a much deeper mixed layer to the right side of the storm and a strong near inertial oscillation in the thermocline we here identify several new features as follows 1 the current velocity to the right side of the track decays faster than that to the left side 2 on the right side of the track the typhoon induced water temperature anomaly exhibits a three layered cooling warming cooling structure in the vertical with salinity and density anomaly profiles sharing a similar pattern 3 on the left side of the track the whole upper ocean is cooled whereas salinity shows no variation in the uppermost 20 m layer with a negative anomaly for water at depths from 20 to 50 m and a positive anomaly below 50 m the associated mechanisms are discussed in the text 4 the storm induced maximum cooling is not unique to kalmaegi 2014 in fact storms with tracks similar to that of kalmaegi 2014 may induce similar maximum cooling in the northern scs which may be useful in predictions of where such storms would induce the maximum cooling

implementation of a mesh movement scheme in a multiply nested ocean model and its application to air sea interaction studies a mesh movement scheme is implemented in a multiply nested primitive equation ocean model mesh movement can be specified or determined in the course of the model run so as to follow an evolving oceanic feature such as a wave front or propagating eddy or atmospheric forcing such as a tropical cyclone mass heat and momentum are conserved during the movement the mesh movement scheme is tested in idealized and realistic configurations of the model the idealized tests include simulations in which the moving meshes follow a propagating equatorial kelvin wave a dipole or move across an existing mesoscale eddy the tests demonstrate that the solutions in the fine mesh region of the nested meshes reproduce well the equivalent solutions from uniform fine mesh models the model is applied for simulations of the ocean response to tropical cyclones in which the moving meshes maintain high resolution near the cyclone center the solution in the inner meshes reproduces very well the uniform fine mesh simulation in particular the sea surface temperature it demonstrates that the moving meshes do not degrade the solution even with the application of strong winds and the generation of energetic surface currents and near inertial gravity waves the mesh movement scheme is also successfully applied for a real case simulation of the ocean response to typhoon roy 1988 in the western north pacific for this experiment the model is initialized using the fields from a general circulation model gcm multiyear spinup integration of the large scale circulation in the tropical pacific ocean the nested mesh solution shows no difficulty simulating the interaction of the storm induced currents with the existing background circulation

observed oceanic response over the upper continental slope and outer shelf during hurricane ivan abstract hurricane ivan passed directly over an array of 14 acoustic doppler current profilers deployed along the outer continental shelf and upper slope in the northeastern gulf of mexico currents in excess of 200 cm s 1 were generated during this hurricane shelf currents followed ekman dynamics with overlapping surface and bottom layers during ivan s approach and transitioned to a dominant surface boundary layer as the wind stress peaked slope currents at the onset of ivan were wind driven near the surface but deeper in the water column they were dominated during and after the passage of ivan by subinertial waves with a period of 2 5 days that had several characteristics of topographic rossby waves currents on the slope at 50 m and greater depths commonly exceeded 50 cm s 1 surprisingly the strongest currents were present to the left of the storm track on the shelf while more energetic currents were to the right of the hurricane path on the slope during the forced stage near inertial motion last

role of near inertial internal waves in subthermocline diapycnal mixing in the northern gulf of mexico abstractmoored adcp data collected in the northern gulf of mexico are analyzed to examine near inertial internal waves and their contribution to subthermocline diapycnal mixing based on a finescale parameterization of deep ocean mixing the focus of the study is on the impact of near inertial internal waves generated by an extreme weather event that is hurricane katrina and by month to month variation in weather patterns on the diapycnal mixing the inferred subthermocline diapycnal mixing exhibits pronounced elevation in the wake of katrina both the increased near inertial 0 8 1 8f where f is the coriolis frequency and superinertial 1 8f shear variances contribute to the elevated diapycnal mixing but the former plays a more dominant role the intense wind work on near inertial motions by the hurricane is largely responsible for the energetic near inertial shear variance energy transfer from near inertial to superinertial internal waves however appears to play an important role in elevating th

observation of tropical cyclone induced shallow water currents in taiwan strait the data from three stations equipped with acoustic doppler current profilers adcps deployed in the shallow water of the taiwan strait tws were used to study the shallow coastal ocean response to five quasi continuous tropical cyclone tc events in the late summer 2006 we revealed that in the forced stage when the large and strong tc bilis transited the geostrophic currents were formed which dominated the whole event while the strong but relatively small one saomai or the weak one bopha primarily leaded to the generation of ekman currents in the relaxation stage the barotropic subinertial waves and or the baroclinic near inertial oscillations nios were triggered typically during the transit of the saomai subinertial waves were induced which demonstrated a period of 2 8 4 1 days and a mean alongshore phase velocity of 14 9 3 2 m s in the form of free barotropic continental shelf waves however the nios are only notable in the area in which the water column is stably stratified and also where the wind stress is dominated by the clockwise component and accompanied by high frequency near inertial variations we also demonstrated that due to the damping effects the nonlinear wave wave interaction e g between nio and semidiurnal tide in our case together with the well known bottom friction led to the rapid decay of the observed tc induced near inertial currents giving a typical e folding time scale of 1 3 inertial periods moreover such nonlinear wave wave interaction was even found to play a major role during the spring tide in tws

processes of loess lithogenesis during the pleistocene holocene southeast siberia regional studies have been conducted on loess deposits cohesive sands and loess like neoformations in the technogenesis zones in southeast siberia cryogenic processes and distribution of geological formations have been ascribed to influential factors of loess lithogenesis the processes of loess formation are active in the present environment

horizontal variability of near inertial oscillations associated with the passage of a typhoon 1 surface currents to the east of okinawa island were observed by using hf high frequency ocean radars in august september 1995 during that period a typhoon passed near the observation area and the horizontal variability of near inertial oscillations associated with the typhoon passage was estimated in addition the near inertial amplitudes and horizontal wave number vectors were estimated these estimations showed that the near inertial amplitude was large in the offshore area and small near the coast the maximum near inertial wavelength was estimated to be in the order of 1000 km and the near inertial wave direction was southward and changed to northwestward on 23 august in 1995 a slab model incorporating low frequency currents was used to calculate near inertial currents it was found that the amplitude of calculated near inertial oscillations was also large in the offshore area moreover the phase propagation direction of the near inertial waves was southward and changed to northwestward or westward on 22 august the growth rate obtained from the dispersion relation was large in the offshore area where the near inertial amplitude was large

near inertial ocean response to tropical cyclone forcing on the australian north west shelf the regional ocean modeling system roms was applied to the australian north west shelf nws to hindcast the ocean response to four intense historical tropical cyclones tcs while the four cyclones had very different trajectories across the nws all passed within 150 km of a long term vertical mooring located on the continental shelf in 125 m depth the observed ocean response at this relatively shallow southern hemisphere shelf site was characterized by the development of a peak in the counter clockwise ccw near inertial kinetic energy mixed layer deepening and subsequent restratification strong near inertial isotherm oscillations were also observed following two of the cyclones roms reproduced these features and also showed that the peak in the near inertial ccw kinetic energy was observed on the left side of each cyclone trajectory the time rate of change of near inertial kinetic energy depended strongly on the storm rossby number i e defined based on the storm speed the storm length scale and the coriolis frequency the shallow water depth on the nws resulted in first a more rapid decay of near inertial oscillations than in the deep ocean and second a generation efficiency the ratio of near inertial power to the rate of wind work of up to 10 smaller than found for cyclones propagating across deeper water the total energy put into near inertial motions is nevertheless large compared to the background tidal energy the rapid decay of near inertial motions emphasizes the importance of frictional effects in characterizing the response to cyclone forcing in shallow seas

the dynamics of the late pleistocene loess formation lozhok section ob loess plateau sw siberia abstract there are unique loess paleosol sections that fully reflect paleoclimate changes during the late pleistocene in southern west siberia this record of climate shows a good correlation with the marine oxygen isotope curve and other global climate records and consequently the loess paleosol sequence of west siberia is a detailed reference scale lozhok is a key section for the late pleistocene loess paleosol sequence of the novosibirsk ob region average loess accumulation rates of each studied loess layer were calculated on the basis of previous 14c and tl dating results and on correlation of the loess paleosol sequence of southern west siberia with mis and the middle siberia loess paleosol sequence the grain size distribution data indicates intensification of environmental dynamics until the last glacial bulk chemical composition reveals the intensification of aridization from the tulino to the bagan loess and that this trend was not constant greater accumulation loess activity during bagan time mis 2 is also confirmed by loess accumulation rate calculations results of sand quartz grain morphoscopy show that loess layers were formed by aeolian processes in periods of deep cooling and aridization the late pleistocene loess layers were formed in periglacial environments in arid cold deserts

the three dimensional steady circulation in a homogenous ocean induced by a stationary hurricane based on the classical ekman layer theory a simple analytical solution of the steady flow induced by a stationary hurricane in a homogenous ocean is discussed the model consists of flow converging in an inward spiral in the deeper layer and diverging in the upper layer the simple analytical model indicates that both the upwelling flux and the horizontal transport increase linearly with increasing radius of maximum winds furthermore they both have a parabolic relationship with the maximum wind speed the coriolis parameter also affects the upwelling flux the response to a hurricane is stronger at low latitudes than that at middle latitudes numerical solutions based on a regional version of an ocean general circulation model are similar to the primary results obtained through the analytical solution thus the simplifications made in formulating the analytical solution are reasonable although the analytical solution in this paper is sought for a rather idealized ocean it can help to make results from the more complicated numerical model understandable these conceptual models provide a theoretical limit structure of the oceanic response to a moving hurricane over a stratified ocean

tropical cyclone enhanced vertical transport in the northwestern south china sea i mooring observation analysis for washi 2005 abstract using mooring observed horizontal velocities and temperature from july 28 to august 2 2005 this study analyzes the temporal vertical variation of the diagnostic vertical velocity and mass transport during passage of tropical storm washi 2005 over the northwestern continental shelf of the south china sea scs the results show that the total vertical velocity is of the order of o 1 10 4 m s 1 in the mixed layer above 25 m and of o 1 10 5 m s 1 in the lower layer dynamically the geostrophic advection and unsteady behavior of density induced by near inertial oscillation are dominant factors in the upper and lower layers respectively as tropical storm washi 2005 passed by from july 29 to 31 2005 the upward vertical velocity was dominant and significantly enhanced to the order of o 1 10 3 m s 1 the diagnosed vertical velocity in the upper layer is one order greater than the averaged ekman pumping velocity which occurred one day earlier the vertical advection transport calculated from the diagnosed vertical velocity reaches o 1 10 5 kg s 1m 3 one order greater than that induced by turbulent mixing time averaged transports by vertical advection and mixing are both upward in the layer above the thermocline during the storm passage

observed upper ocean response to typhoon megi 2010 in the northern south china sea typhoon megi passed between two subsurface moorings in the northern south china sea in october 2010 and the upper ocean thermal and dynamical response with strong internal tides present was examined in detail the entire observed water column 60 360 m was cooled due to strong ekman pumped upwelling up to 50 m in the thermocline by megi with maximum cooling of 4 2 c occurring in thermocline a relatively weak maximum amplitude of 0 4 m s 1 and quickly damped e folding time scale of 2 inertial periods near inertial oscillation nio was observed in the mixed layer power spectrum and wavelet analyses both indicated an energy peak appearing at exactly the sum frequency fd1 with maximum amplitude up to 0 2 m s 1 of nio f and diurnal tide d1 indicating enhanced nonlinear wave wave interaction between f and d1 during and after typhoon numerical experiments suggested that energy transfer from nio to fd1 via nonlinear interaction between f and d1 may have limited the growth and accelerated the damping of mixed layer nio generated by megi the occurrence of fd1 had a high correlation with nio the vertical nonlinear momentum term associated with the vertical shear of nio and vertical velocity of d1 or vertical shear of d1 and vertical velocity of nio was more than 10 times larger than the horizontal terms and was responsible for forcing fd1 after megi surface layer diurnal energy was enhanced by up to 100 attributed to the combined effect of the increased surface layer stratification and additional megi forced diurnal current

the relationship between downward irradiance and upper ocean structure abstract the relationship between downward irradiance and upper ocean structure has been studied using a numerical model two general classes of irradiance parameterizations were utilized the first case i employed a single attenuation length while the second cast ii involved two attenuation lengths the latter formulation provided for enhanced absorbance in the upper few meters wind speeds of 0 1 2 3 4 5 10 and 20 m s 1 were used for the simulations in order to characterize heat versus wind dominated regimes a one dimensional second moment turbulent closure model was selected for the study so that heat could be treated differentially with depth the case ii results indicated warmer surface temperatures shallower mixed layers and more intense thermoclines than case i for wind speeds 10 m s 1 results converged for higher wind speeds there was considerably greater sensitivity to wind speed for case ii when compared with case i mean horizontal velocity as well as thermal structure was sensi

the influence of the ocean on typhoon nuri 2008 abstracttyphoon nuri 2008 was 1 of approximately 120 typhoons in the past 60 years that passed through a narrow gap the luzon strait connecting the western north pacific and the south china sea scs in total 70 of these storms including nuri reached their maximum intensities over the warm waters east of luzon and in the kuroshio then rapidly weakened in the scs numerical experiments were conducted to understand the intensity change of nuri westward across the kuroshio in the luzon strait the 26 c isotherm shallows rapidly by half this and stronger mixing by wind ocean resonance preferentially cooled sea surface temperature and weakened the typhoon in scs a positive feedback mechanism is then described to explain the intensification of nuri over the western north pacific

observed near surface flows under all tropical cyclone intensity levels using drifters in the northwestern pacific 1 data from drifters of the surface velocity program and tropical cyclones tcs of the joint typhoon warning center during 1985 2009 were analyzed to demonstrate strong currents under various storm intensities such as category 4 to 5 category 2 to 3 and tropical storm to category 1 tcs in the northwestern pacific current speeds over 2 0 m s 1 are observed under major tcs with the strongest mean currents to the right of the storm track this study provides the characterization of the near surface velocity response to all recorded tcs and agrees roughly with geisler s theory 1970 our observations also verify earlier modeling results of price 1983

the response of georges bank to the passage of hurricane edouard abstract on september 2 1996 hurricane edouard passed directly over georges bank moving generally northeastward the center of the hurricane passed close to an instrumented mooring site sf located on the southern flank of the bank at 76 m high winds were observed at sf over a 2 5 day period the maximum wind speed at the sf site at 3 m above the sea level was about 22 m s which corresponded to a surface stress of about 1 5 pa this occurred just prior to the rapid veering of the wind as the center of the hurricane passed the net surface heat flux at sf decreased to about 27 w m 2 primarily due to the reduced solar radiation through the hurricane cloud cover the maximum wind forced currents observed at sf due to hurricane edouard were about 50 cm s as large as the dominant semidiurnal tidal flow a 35 m deep mixed layer at sf was created as the hurricane approached which then varied between 15 and 45 m deep until restratification began on september 4 the evolution of this mixed layer was complex due to the spatially varying stratification in this region and its advection past the mooring site by the tidal and subtidal frequency flows the initial forcing of the baroclinic wake appeared to be present in the detided currents as strong opposing on and off bank flows of the upper and lower layers observed immediately after the center of the hurricane had passed however this flow quickly decayed and the near inertial waves of the baroclinic wake generally observed in the deep ocean were not present we suggest that the lack of any distinct baroclinic wake and the rapid decay of the hurricane driven flows were due to the high frictional damping which occurred over georges bank due to its shallow topography and strong tidal currents

mooring observations and numerical modeling of thermal structures in the south china sea 1 three sets of autonomous temperature line acquisition systems were deployed in the south china sea gaps aside the data covered nearly 3 years at the northern station and about 2 years farther south fluctuations ranged from episodic to interannual internal tides more diurnal than semidiurnal were active basinwide twelve typhoons passed during measurement periods the most severe one typhoon babs in 1998 caused a temperature drop of over 7 c at 50 m despite strong monsoons only near surface temperature showed clear seasonal variations intraseasonal variations induced by mesoscale eddy stood out much better at subsurface depths propagating eddies aside some eddies were seasonal and nearly stationary from daily archives of an eddy resolving data assimilating ocean model east asian seas nowcast forecast system we identified two paradigms leading to the generation of a persistent spring summer warm eddy in the central western basin in normal years a complete cyclonic gyre was driven by a strong winter northeast monsoon water piled up along the periphery of the south china sea afterward a warm eddy could be generated from west of luzon island and propagated westward while intensifying under a weak northeast monsoon such as in el nino years piled up water tended to stay in the southern basin when the wind relaxed in spring warm water returned northward to form a warm eddy in the central western basin transition from sw to ne monsoon also often led to a warm eddy generation in southern latitudes when the summer eastward jet departing from central vietnam broke up

relationship between footwall composition crustal contamination and fluid rock interaction in the platreef bushveld complex south africa in the northern limb of the 2 06 ga bushveld complex the platreef is a platinum group elements pge cu and ni mineralized zone of pyroxenite that developed at the intrusion margin from north to south the footwall rocks of the platreef change from archaean granite to dolomite hornfels and quartzite where the footwall is granite the sr isotope system is more strongly perturbed than where the footwall is sr poor dolomite in which samples show an approximate isochron relationship the nd isotope system for samples of pyroxenite and hanging wall norite shows an approximate isochron relationship with an implied age of 2 17 0 2 ga and initial nd isotope ratio of 0 5095 assuming an age of 2 06 ga the nd values range from 6 2 to 9 6 ave 7 8 n 17 and on average are slightly more negative than the main zone of the bushveld these data are consistent with local contamination of an already contaminated magma of main zone composition the similarity in isotope composition between the platreef pyroxenites and the hanging wall norites suggests a common origin where the country rock is dolomite the platreef has generally higher plagioclase and pyroxene 18o values and this indicates assimilation of the immediate footwall throughout the platreef there is considerable petrographic evidence for sub solidus interaction with fluids and the plagioclase pyroxene values range from 2 to 6 which indicates interaction at both high and low temperatures whole rock and mineral d values suggest that the platreef interacted with both magmatic and meteoric water and the lack of disturbance to the sr isotope system suggests that fluid rock interaction took place soon after emplacement where the footwall is granite less negative d values suggest a greater involvement of meteoric water consistently higher values of plagioclase pyroxene in the platreef pyroxenites and hanging wall norites in contact with dolomite suggest prolonged interaction with co2 rich fluid derived from decarbonation of the footwall rocks the overprint of post crystallization fluid rock interaction is the probable cause of the previously documented lack of correlation between pge and sulfide content on the small scale the platreef in contact with dolomite is the focus of the highest pge grades and this suggests that dolomite contamination played a role in pge concentration and deposition but the exact link remains obscure it is a possibility that the co2 produced by decarbonation of assimilated dolomite enhanced the process of pge scavenging by sulfide precipitation

influence of the size of supertyphoon megi 2010 on sst cooling abstractsupertyphoon megi 2010 left behind two very contrasting sst cold wake cooling patterns between the philippine sea 1 5 c and the south china sea 7 c based on various radii of radial winds we found that the size of megi doubles over the south china sea when it curving northwards on average the radius of maximum wind rmw increased from 18 8 km over the philippine sea to 43 1 km over the south china sea the radius of 64 kt typhoon force wind r64 increased from 52 6 km to 119 7 km the radius of 50 kt damaging force wind r50 increased from 91 8 km to 210 km and the radius of 34 kt gale force wind r34 increased from 162 3 km to 358 5 km to investigate the typhoon size effect we conduct a series of numerical experiments on megi induced sst cooling by keeping other factors unchanged i e typhoon translation speed and ocean subsurface thermal structure the results show that if it were not for megi s size increase over the south china sea the during megi sst cooling magnitude woul

asymmetric oceanic response to a hurricane deep water observations during hurricane isaac the eye of hurricane isaac passed through the center of an array of six deep water water column current meter moorings deployed in the northern gulf of mexico the trajectory of the hurricane provided for a unique opportunity to quantify differences in the full water column oceanic response to a hurricane to the left and right of the hurricane trajectory prior to the storm passage relative vorticity on the right side of the hurricane was strongly negative while on the left relative vorticity was positive this resulted in an asymmetry in the near inertial frequencies oceanic response at depth and horizontally a shift in the response to a slightly larger inertial frequencies 1 11f was observed and verified by theory additionally the storm passage coincided with an asymmetric change in relative vorticity in the upper 1000 m which persisted for 15 inertial periods vertical propagation of inertial energy was estimated at 29 m d while horizontal propagation at this frequency was approximately 5 7 km d wavelet analysis showed two distinct subinertial responses one with a period of 2 5 days and another with a period of 5 12 days analysis of the subinertial bands reveals that the spatial and temporal scales are shorter and less persistent than the near inertial variance as the array is geographically located near the site of the deep water horizon oil spill the spatial and temporal scales of response have significant implications for the fate transport and distribution of hydrocarbons following a deep water spill event

symmetric and asymmetric structures of hurricane boundary layer in coupled atmosphere wave ocean models and observations abstractit is widely accepted that air sea interaction is one of the key factors in controlling tropical cyclone tc intensity however the physical mechanisms for connecting the upper ocean and air sea interface with storm structure through the atmospheric boundary layer in tcs are not well understood this study investigates the air sea coupling processes using a fully coupled atmosphere wave ocean model especially the coupling induced asymmetry in surface winds sea surface temperature air sea fluxes and their impacts on the structure of the hurricane boundary layer hbl numerical experiments of hurricane frances 2004 with and without coupling to an ocean model and or a surface wave model are used to examine the impacts of the ocean and wave coupling respectively model results are compared with the airborne dropsonde and surface wind measurements on board the noaa wp 3d aircraft the atmosphere ocean coupling reduces the mixed layer depth in the rear right quadrant due to storm induced ocean

response of subsurface waters in the eastern arabian sea to tropical cyclones abstract thermister chain data at different depths for june 1998 cyclone in the arabian sea at a location 69 2 e 15 5 n which is about 60 km to the left of the cyclone track indicates subsurface warming below 60 m and inertial oscillations of temperature with a periodicity of about 2 days the oscillations continued for 15 days even after the cyclone crossed the coast the analysis of the buoy ds1 located at the same position also suggests a stabilized southward flow after about two weeks of the cyclone crossed the coast analysis of the buoy data for may 1999 cyclone in the same region also indicates similar pattern in order to investigate the effect of cyclone ocean interaction and primarily to understand the process for the subsurface warming 3 dimensional princeton ocean model is configured for the eastern part of the arabian sea the model uses high horizontal resolution of about 6 km near the coast and a terrain following sigma coordinate in the vertical with 26 levels the study focuses on surface cooling and temperature rise in the underlying waters and explains its mechanism through upwelling and downwelling respectively the simulations in concurrence with the observations suggest that the occurrence of subsurface warming precedes the surface cooling with a lag of a day as the cyclone advances ds1 the simulations also demonstrate local temperature stratification plays an important role for cooling of the upper ocean and warming of the subsurface waters and extent of warming is directly related to the depth of the thermocline

new chemical bio optical and physical observations of upper ocean response to the passage of a mesoscale eddy off bermuda a mesoscale eddy advected across the bermuda testbed mooring site over a 30 day period centered on july 14 1995 temperature and current measurements along with biogeochemical measurements were used to characterize the biological response of the upper ocean associated with the introduction of nitrate into the euphotic layer due to the doming of isotherms associated with the eddy complementary shipboard data showed an anomalous water mass which extended from a depth of 50 to 1000 m manifesting as a cold surface expression and warm anomaly at depth although mesoscale eddies are frequently observed in the sargasso sea the present observations are particularly unique because of the high temporal resolution measurements of the new instrumentation deployed on the mooring analyzers that measure nitrate plus nitrite were placed at depths of 80 and 200 m and bio optical sensors were located at depths of 20 35 45 71 and 86 m peak nitrate values of nearly 3 0 mm at 80 m and chlorophyll a values of 1 4 mg m 23 at 71 m were observed as well as a 25 to 30 meter shoaling of the 1 light level depth a doppler shift from the inertial period 22 8 hours to 25 2 hours was observed in several time series records due to the movement of the eddy across the mooring inertial pumping brought cold nutrient rich waters farther into the euphotic zone than would occur solely by isothermal lifting silicic acid was depleted to undetectable levels owing to the growth of diatoms within the eddy the chlorophyll a values associated with the eddy appear to be the largest recorded during the 8 years of the ongoing u s jgofs bermuda atlantic time series study bats program

dust and pollution a recipe for enhanced ocean fertilization 1 for fe contained in aeolian dust to act as a micronutrient for oceanic phytoplankton some fraction of it must first be transformed mobilized into a form soluble in ocean water fe solubilization in deliquesced mineral dust aerosols emanating from east asia during the springtime outflow conditions is investigated here with a lagrangian box model of the gas and aqueous phase chemistry the model simulates the scavenging of soluble and reactive gaseous species by mineral dust aerosols chemical reactions of these species and mineral dust ions in deliquesced solution and dissolution of fe iii oxides that occurs as a result of the acid mobilization the calculations indicate that mineral calcite caco3 strongly buffers deliquesced dust aerosols with a ph that remains close to 8 until the amount of acid added to the aerosol solution exceeds caco3 alkalinity so2 pollutant emissions are a potential source of acidity to advecting dust from east asia the model is used to simulate the chemical evolution of dust plumes formed from two contrasting documented gobi desert storms that advected dust to fe limited regions of the north pacific ocean npo these calculations indicate that only plumes with relatively high initial so2 to dust ratios are capable of delivering significant amounts of bioavailable fe to the npo the estimated change in phytoplankton population inferred from the model calculated inputs of bioavailable fe for these two episodes is consistent with the satellite measured chlorophyll a concentrations in the npo model simulations indicate that 1 large dust advection episodes that can export vast amounts of mineral dust to the open ocean should have insignificant dissolved iron fraction dif as the amount of so2 required to acidify such dust plumes is about an order of magnitude higher than what can typically be entrained in the plume during its advection 2 smaller dust plumes will generally have higher difs because they require lower amounts of so2 and even if such small plumes may not cause algae blooms they could still be important sources of dissolved fe to the npo the calculations suggest that future changes in so2 pollutant emissions from east asia either up or down may affect the productivity of the npo

chattermark trails surface features on detrital quartz grains indicative of a tropical climate abstract with respect to weathering erosional processes and sediment transport quartz is one of the most stable minerals and makes up to 98 of the mineral volume of siliciclastic sands pettijohn et al 1987 although a major component in a wide variety of rocks quartz has almost no characteristic properties that allow determining parent rock types quartz does not contain characteristic cleavage planes and quartz grains react to impact or collision with other sediment particles by producing conchoidal fractures very similar to those observed for broken glass for sedimentologists physical geographers and soil scientists detrital quartz grains are poor in characteristic features except for a suite of surface features that may be indicative of various transport environments or even climate related alterations one of these surface features are chattermark trails chattermark trails are a series of linearly arranged rune like grooves on surfaces of minerals grains such as quartz and garnet lacking any type of cleavage these trails have been described from many unconsolidated sediments and are attributed mostly to glacial sediments laboratory experiments on polished quartz beads reveal that chattermark trails are not primary surface features but become visible after etching by dilute hydrofluoric acid comparison of the etched and non etched surface of the same quartz bead reveals that mechanically produced invisible cracks related to blunt collisions with other polished quartz beads became visible only after chemical etching chattermark trails on detrital quartz grains are the product of two processes the dynamic one is an invisible transport related blunt collision followed by a second stationary process which enables quartz dissolution to make the chattermarks visible in the broad field of laterite research it is well accepted that quartz dissolution in surface or near surface deposits is restricted to stationary chemical weathering in a wet tropical or at least subtropical climate drawing on this information chattermark trails are no longer considered a product of a specific sedimentary environment but reveal a distinct history of the quartz grain they are formed by blunt collisions in a sediment transport stage before experiencing some dissolution during a depositional stage in a tropical climate grains can be remobilized in an active sediment transport system collectively the results reveal that chattermark trails on quartz grains provide unique insights into the transport and climate history of sediments

late glacial to holocene aeolian deposition in northeastern europe the timing of sedimentation at the iisaku site ne estonia abstract the late glacial and holocene aeolian inland dune complex at iisaku ne estonia has been investigated using an accurate and detailed compilation of the sedimentary properties and chronological framework the quartz grains forming the dunes are very variable reflecting aeolian weathering and periglacial conditions both prior and after deposition although the morphological forms and the sedimentary record point to a dune like environment the transport record reflects either a short transport time or and distance and a contribution from neighbouring sedimentary environments dune development in the area was strongly controlled by the formation of the baltic ice lake bil in front of the retreating glacier luminescence ages from the aeolian complex suggest continuous deposition between 13 3 1 2 to 10 5 0 7 ka however the chronology of sand deposition also suggests phases in this aeolian activity 1 at 13 3 1 2 ka and onwards possibly correlated with the existence of an island separating the bil and peipsi lake 2 between 12 7 0 8 12 5 0 8 ka representing the younger dryas cold reversal 3 between 11 5 0 7 10 9 0 8 ka indicating that aeolian deposition continued over the younger dryas holocene boundary and 4 early holocene sand drift at 10 5 0 7 ka

an ocean coupling potential intensity index for tropical cyclones american geophysical union 2013 this article is posted here by permission of american geophysical union for personal use not for redistribution the definitive version was published in geophysical research letters 40 2013 1878 1882 doi 10 1002 grl 50091

parametric subharmonic instability of the semidiurnal internal tides at the east china sea shelf slope abstracton the basis of measurements from an observing mooring system the observational evidence of parametric subharmonic instability psi that transfers energy from semidiurnal internal tides

restratification of the upper ocean after the passage of a tropical cyclone a numerical study abstractthe role of baroclinic instability in the restratification of the upper ocean after the passage of a tropical cyclone tc is determined by means of numerical simulations using a regional ocean model the regional ocean modeling system roms a high resolution three dimensional simulation that includes the process of baroclinic instability and is initialized with moderate amplitude eddy structures reproduces the satellite observed decay rate of the tc induced sea surface temperature sst anomaly and is also in qualitative agreement with published observations after the passage of hurricane fabian in 2003 that showed decaying cold and warm anomalies located in the climatological mixed layer cml and upper thermocline respectively the model ocean is restratified after approximately one month with a net heat gain in the water column due to anomalous air sea heat fluxes the model shows however that vertical heat fluxes associated with baroclinic instability dominate over air sea heat fluxes i

tropical cyclone ocean interaction in typhoon megi 2010 a synergy study based on itop observations and atmosphere ocean coupled model simulations a mesoscale model coupling the weather research and forecasting model and the three dimensional price weller pinkel ocean model is used to investigate the dynamical ocean response to megi 2010 it is found that megi induces sea surface temperature sst cooling very differently in the philippine sea ps and the south china sea scs the results are compared to the in situ measurements from the impact of typhoons on the ocean in the pacific itop 2010 field experiment satellite observations and ocean analysis field from eastern asian seas ocean nowcast forecast system of the u s naval research laboratory the uncoupled and coupled experiments simulate relatively accurately the track and intensity of megi over ps however the simulated intensity of megi over scs varies significantly among the experiments only the experiment coupled with three dimensional ocean processes which generates rational sst cooling reasonably simulates the storm intensity in scs our results suggest that storm translation speed and upper ocean thermal structure are two main factors responsible for megi s distinct different impact over ps and over scs in addition it is shown that coupling with one dimensional ocean process i e only vertical mixing process is not enough to provide sufficient ocean response especially under slow translation speed 2 3 m s 1 during which vertical advection or upwelling is significant therefore coupling with three dimensional ocean processes is necessary and crucial for tropical cyclone forecasting finally the simulation results show that the stable boundary layer forms on top of the megi induced cold sst area and increases the inflow angle of the surface wind

upper ocean response to hurricane gonzalo 2014 salinity effects revealed by targeted and sustained underwater glider observations during october 2014 hurricane gonzalo traveled within 85 km from the location of an underwater glider situated north of puerto rico observations collected before during and after the passage of this hurricane were analyzed to improve our understanding of the upper ocean response to hurricane winds the main finding in this study is that salinity potentially played an important role on changes observed in the upper ocean a near surface barrier layer likely suppressed the hurricane induced upper ocean cooling leading to smaller than expected temperature changes poststorm observations also revealed a partial recovery of the ocean to prestorm conditions 11 days after the hurricane comparison with a coupled ocean atmosphere hurricane model indicates that model observations discrepancies are largely linked to salinity effects described results presented in this study emphasize the value of underwater glider observations for improving our knowledge of how the ocean responds to tropical cyclone winds and for tropical cyclone intensification studies and forecasts

spatial and temporal characterization of sea surface temperature response to tropical cyclones abstractthe spatial structure and temporal evolution of the sea surface temperature sst anomaly ssta associated with the passage of tropical cyclones tcs as well as their sensitivity to tc characteristics including tc intensity and translation speed and oceanic climatological conditions represented here by latitude are thoroughly examined by means of composite analysis using satellite derived sst data the magnitude of the tc generated ssta is larger for more intense slower moving and higher latitude tcs and it occurs earlier in time for faster moving and higher latitude storms the location of maximum ssta is farther off the tc track for faster moving storms and it moves toward the track with time after the tc passage the spatial extension of the cold wake is greater for more intense and for slower moving storms but its shape is quite independent of tc characteristics consistent with previous studies the calculations show that the mean ssta over a tc centered box nearly linearly corre

observed currents over the outer continental shelf during hurricane ivan 1 hurricane ivan crossed the gulf of mexico as a category 4 5 storm before making landfall in alabama here we show in unprecedented detail the oceanic response generated by ivan as it crossed the outer continental shelf the current structure was found to be frictionally dominated with overlapping surface and bottom boundary layers as ivan approached before transitioning to a dominant surface boundary layer as the wind stress peaked the strongest currents largest temperature fluctuations and greatest transports were generated left of the storm track

evidence and mechanism of hurricane fran induced ocean cooling in the charleston trough evidence of enhanced sea surface cooling during and following the passage of hurricane fran in september 1996 over an oceanic depression located on the ocean margin offshore of charleston south carolina referred to as the charleston trough pietrafesa 1983 is documented approximately 4c of sea surface temperature sst reduction within the charleston trough following the passage of hurricane fran was estimated based on sst imagery from advanced very high resolution radiometer avhrr on the noaa 14 polar orbiting satellite simulations using a three dimensional coastal ocean model indicate that the largest sst reduction occurred within the charleston trough this sst reduction can be explained by oceanic mixing due to storm induced internal inertia gravity waves

an examination of the thermodynamic impacts of western north pacific tropical cyclones on their tropical tropospheric environment abstractthe present study examines the tropospheric thermodynamic anomalies induced by western north pacific tropical cyclone tc passage using storm relative composites negative moist static energy mse anomalies containing embedded westward propagating anomalies generally occur only following larger tcs for two months following tc passage in a region extending from the domain center to 3000 km to its west larger tcs force negative mse anomalies likely because of feedbacks from stronger broader tc induced negative sea surface temperature sst anomalies and the excitation of tc induced rossby waves to the southeast of the tc the negative mse anomalies are composed of lower and midtropospheric negative latent energy anomalies with smaller contributions from boundary layer and upper tropospheric negative sensible heat anomalies the lower and midtropospheric negative mse anomalies are forced by the tc whereas the upper tropospheric negative mse anomalies are forced by the madden julian oscillatio

upper ocean response to hurricane frances 2004 observed by profiling em apex floats abstractthree autonomous profiling electromagnetic autonomous profiling explorer em apex floats were air deployed one day in advance of the passage of hurricane frances 2004 as part of the coupled boundary layer air sea transfer cblast high field experiment the floats were deliberately deployed at locations on the hurricane track 55 km to the right of the track and 110 km to the right of the track these floats provided profile measurements between 30 and 200 m of in situ temperature salinity and horizontal velocity every half hour during the hurricane passage and for several weeks afterward some aspects of the observed response were similar at the three locations the dominance of near inertial horizontal currents and the phase of these currents whereas other aspects were different the largest amplitude inertial currents were observed at the 55 km site where sst cooled the most by about 2 2 c as the surface mixed layer deepened by about 80 m based on the time depth evolution of the richar

observations and analyses of upper ocean responses to tropical storms and hurricanes in the vicinity of bermuda 1 a circular region within a radius of 400 km of bermuda has been struck by 188 tropical storms or hurricanes from 1851 through 2005 and by 20 since 1995 here we describe new direct and remote sensing observations and analyses of recent events near the bermuda testbed mooring including hurricane fabian 2003 tropical storm harvey 2005 and hurricane nate 2005 the most impressive upper ocean response of the recent events was produced by hurricane fabian when sst cooling exceeded 3 5 c vertical mixing occurred to a depth of greater than 130 m and upper ocean currents reached 100 cm s 1 fabian also triggered an ocean color event visible in seawifs satellite images related implications include improved estimates of the roles of tropical cyclones in driving meridional overturning circulation moc and testing of hypotheses concerning warming of the tropical oceans which could cause more intense tropical storms and hurricanes

uncertainty propagation in coupled atmosphere wave ocean prediction system a study of hurricane earl 2010 abstractthis study focuses on understanding the evolution of hurricane earl 2010 with respect to random perturbations in the storm s initial strength size and asymmetry in wind distribution we

the ocean boundary layer below hurricane dennis abstract three neutrally buoyant floats were air deployed ahead of hurricane dennis on 28 august 1999 these floats were designed to accurately follow three dimensional water trajectories and measure pressure i e their own depth and temperature the hurricane eye passed between two of the floats both measured the properties of the ocean boundary layer beneath sustained 30 m s 1 winds the floats repeatedly moved through a mixed layer 30 70 m deep at average vertical speeds of 0 03 0 06 m s 1 the speed was roughly proportional to the friction velocity mixed layer temperature cooled about 2 8 and 0 75 c at the floats on the east and west sides of the northward going storm respectively much of the cooling occurred before the eye passage the remaining terms in the horizontally averaged mixed layer heat budget the vertical velocity temperature covariance and the lagrangian heating rate were computed from the float data surface heat fluxes accounted for only a small part of the cooling most of th

crustal contamination and fluid rock interaction during the formation of the platreef northern limb of the bushveld complex south africa the platreef is the main platinum group element pge bearing and contains some of the most important magmatic ore deposits yet discovered the intrusion covers an area of facies of the northern limb of the bushveld complex but unlike the merensky reef of the eastern and western limbs it is in direct roughly 65 000 km e g tankard et al 1982 and lies almost entirely within the bounds of the transvaal basin contact with the country rock mineral separate o values for samples from the upper zone and main zone of the northern limb fig 1 the layered igneous rocks the rustenburg layered suite sacs 1980 can be divided into eastern indicate crystallization from a well mixed already contaminated magma having a o value of 7 5 pyroxenes from the pyroxenites and western limbs of approximately the same size and a smaller northern limb the northern limb differs in facies of the platreef at sandsloot mine have o values that are up to 2 4 higher than pyroxenes from the upper and main several important aspects from the more well known eastern and western limbs e g van der merwe 1976 zones these differences can be explained by additional assimilation of up to 18 dolomite which is in contact with the intrusion at buchanan et al 1981 cawthorn et al 1985 eales cawthorn 1996 first the layered rocks show a this locality samples from the platreef that have plagioclase and pyroxene not in oxygen isotope equilibrium appear to have interacted pronounced transgression across the floor rocks from a with fluids during slow cooling quartz veins with granophyric level above the magaliesberg quartzite formation south margins have o values between 10 1 and 12 2 which of the town of potgietersrus across the whole pretoria suggest that the fluid that passed through the cooling platreef had group and the banded iron formations and dolomites a o value of 7 9 these data together with hydrogen isotope of the older chuniespoort group onto archaean granitic data from minerals and whole rock samples d of biotite 60 rocks fig 1 second the igneous layering shows an to 88 of the platreef suggest interaction with magmatic fluid apparent transgressive relationship with respect to the at low water rock ratios interaction of this fluid with the calcsilicate contact such that ultramafic rocks of the lower zone footwall rocks lowered their o values abut against the contact south of potgietersrus whereas to the north rocks forming the base of the intrusion are progressively higher in the stratigraphic succession of the

upper ocean response to typhoon kalmaegi 2014 typhoon kalmaegi passed over an array of buoys and moorings in the northern south china sea in september 2014 leaving a rare set of observations on typhoon induced dynamical and thermohaline responses in the upper ocean the dynamical response was characterized by strong near inertial currents with opposite phases in the surface mixed layer and in the thermocline indicating the dominance of the response by the excitation of the first baroclinic mode the thermohaline response showed considerable changes in the mean fields in addition to a near inertial oscillation in particular temperature and salinity anomalies generally exhibited a three layer vertical structure with the surface layer becoming cooler and saltier the subsurface layer warmer and fresher and the lower layer cooler and saltier again the response in the surface and subsurface layers was much stronger to the right of the typhoon track while that in the lower layer was stronger along the track and to the left these features of the upper ocean response were grossly reproduced by a three dimensional numerical model a model based heat budget analysis suggests that vertical mixing was mainly responsible for the surface cooling and subsurface warming while upwelling was the cause of cooling from below both observations and model results indicate that the whole upper ocean experienced an overall cooling in the wake of typhoon kalmaegi

numerical study of the storm induced circulation on the scotian shelf during hurricane juan using a nested grid ocean model a nested grid ocean circulation modelling system is used to assess the upper ocean response of the scotian shelf and adjacent slope to hurricane juan in september 2003 the nested grid system consists of a fine grid inner model covering the scotian shelf slope and a coarse grid outer model covering the northwest atlantic ocean the model calculated upper ocean response to hurricane juan is characterized by large divergent surface currents forced by the local wind forcing under the storm and intense near inertial currents in the wake of the storm the sea surface temperature sst cooling produced by the model is biased to the right of the storm track and agrees well with a satellite derived analysis over the deep water off the scotian shelf some of the near inertial energy input by the storm is advected eastward by the gulf stream away from the storm track the hurricane also generates shelf waves that propagate equatorward with the coastline on their right in comparison with the outer model results the inner model captures more meso scale structures greater sst cooling and stronger near inertial currents in the study region

the sensitivity of upper ocean structure to time varying wind direction observations and models show that sudden changes in the magnitude of the wind stress which occur within a time interval of one half inertial period are most effective in increasing surface current speeds and mixing the upper layers of the ocean the purpose of the present study is to quantify the effects of concurrent time dependent wind direction the mellor yamada level 2 1 2 turbulence closure model is used a series of model runs was executed in order to determine the relative sensitivity of mixed layer depth and sea surface temperature to wind speed as compared with the rate of change of wind direction the results indicate that the accuracy and time resolution of wind direction should be given special consideration in the design and interpretation of field experiments which will be used for testing prognostic mixed layer models

response of upper ocean currents to typhoon fanapi the response of upper ocean currents to typhoon fanapi in fall 2010 was studied using an extensive air deployed drifter array separation of the observations into near inertial and sub inertial motions quantified the importance of strong advection by the sub inertial circulation for the evolution of the cold wake formed by typhoon fanapi the near inertial currents generated during the storm showed the expected rightward bias with peak magnitudes of up to 0 6 m s and an e folding time of about 4 days for the strong currents within the cold wake the shear of the near inertial currents is crucial for the storm induced cooling and deepening of the mixed layer and such instabilities were here directly observed across the base of the mixed layer in typhoon fanapi s cold wake during the recovery the diurnal cycle a dominant process for the wake warming was found to be noticeably reduced when the near inertial motions were strongest

tropical cyclone induced ocean response a comparative study of the south china sea and tropical northwest pacific abstractthe thermocline shoals in the south china sea scs relative to the tropical northwest pacific ocean nwp as required by geostrophic balance with the kuroshio the present study examines the effect of this difference in ocean state on the response of sea surface temperature sst and chlorophyll concentration to tropical cyclones tcs using both satellite derived measurements and three dimensional numerical simulations in both regions tc produced sst cooling strongly depends on tc characteristics including intensity as measured by the maximum surface wind speed translation speed and size when subject to identical tc forcing the sst cooling in the scs is more than 1 5 times that in the nwp which may partially explain weaker tc intensity on average observed in the scs both a shallower mixed layer and stronger subsurface thermal stratification in the scs contribute to this regional difference in sst cooling the mixed layer effect dominates when tcs are weak fast moving and or small

highly resolved observations and simulations of the ocean response to a hurricane 1 an autonomous profiling float called em apex was developed to provide a quantitative and comprehensive description of the ocean side of hurricane ocean interaction em apex measures temperature salinity and pressure to ctd quality and relative horizontal velocity with an electric field sensor three prototype floats were air deployed into the upper ocean ahead of hurricane frances 2004 all worked properly and returned a highly resolved description of the upper ocean response to a category 4 hurricane at a float launched 55 km to the right of the track the hurricane generated large amplitude inertially rotating velocity in the upper 120 m of the water column coincident with the hurricane passage there was intense vertical mixing that cooled the near surface layer by about 2 2 c we find consistent model simulations of this event provided the wind stress is computed from the observed winds using a high wind speed saturated drag coefficient

loop current mixed layer energy response to hurricane lili 2002 part ii idealized numerical simulations abstractin this second part of a two part study details of the upper ocean response within an idealized baroclinic current to a translating tropical cyclone are examined in a series of nonlinear reduced gravity numerical simulations based on observations obtained as part of a joint noaa national science foundation nsf experiment in hurricane lili 2002 the preexisting ocean mass and momentum fields are initialized with a gulf of mexico loop current like jet which is subsequently forced by a vortex whose wind stress field approximates that observed in the lili experiments because of 1 favorable coupling between the wind stress and preexisting current vectors and 2 wind driven currents flowing across the large horizontal pressure gradient wind energy transfer to the mixed layer can be more efficient in such a regime as compared to the case of an initially horizontally homogeneous ocean however nearly all energy is removed by advection and wave flux by two local inertial periods after storm pa

the responses of cyclonic and anticyclonic eddies to typhoon forcing the vertical temperature salinity structure changes associated with the horizontal convergence divergence the responses of the cyclonic eddies ces and anti cyclonic eddies aes to typhoon forcing in the western north pacific ocean wnpo are analyzed using argo profiles both ces and aes have the primary cooling at the surface 0 10 m depth and deep upwelling from the top of thermocline 200 m depth down to deeper ocean shortly after typhoon forcing due to the deep upwelling part of warm and fresh water at the top of aes move out of the eddy which leads to a colder and saltier subsurface in the aes after the passage of the typhoon in contrast the inflow of warm and fresh water heats and freshens the subsurface in the ces to compensate the cooling induced by the typhoon this explains why the observed strong sst cooling were much less than modeled since the aes are more frequent than ces in the wnpo it indicates that there is divergence convergence of warm and fresh water in the surface of aes subsurface of ces the divergence convergence effects of the aes and ces lead to the secondary cooling center locate at a shallow layer of 100 m in the aes and a much deeper layer of 350 m in the ces this shallow divergence convergence flow could lead a shallow overturning flow in upper oceans which may potentially influences the large scale ocean circulations and climates

hurricane forced upwelling and chlorophyll a enhancement within cold core cyclones in the gulf of mexico 1 clear skies subsequent to hurricane ivan s passage across the gulf of mexico in september 2004 provided a unique opportunity to investigate upper ocean responses to a major hurricane oceanic cyclonic circulation was rapidly intensified by the hurricane s wind field 59 62 m s 1 maximizing upwelling and surface cooling 3 7 c in two large areas along ivan s track upward isothermal displacements of 50 65 m computed from wind stress and sea surface height changes caused rapid ventilation of thermoclines and nutriclines leading to phytoplankton blooms with peak concentrations 3 4 days later wind speed changes along ivan s track demonstrated that the cool waters 20 26 c provided immediate negative feedback to the hurricane s intensity although our study focused on a relatively small ocean area it revealed that mesoscale cyclones in addition to warm anticyclones may play an important role in producing along track hurricane intensity changes

simulations of the ocean response to a hurricane nonlinear processes abstract superinertial internal waves generated by a tropical cyclone can propagate vertically and laterally away from their local generation site and break contributing to turbulent vertical mixing in the deep ocean and maintenance of the stratification of the main thermocline in this paper the results of a modeling study are reported to investigate the mechanism by which superinertial fluctuations are generated in the deep ocean the general properties of the superinertial wave wake were also characterized as a function of storm speed and central latitude the massachusetts institute of technology mit ocean general circulation model ogcm was used to simulate the open ocean response to realistic westward tracking hurricane type surface wind stress and heat and net freshwater buoyancy forcing for regions representative of midlatitudes in the atlantic the caribbean and low latitudes in the eastern pacific the model had high horizontal x y and vertical z 5 m in top 100 m resolution

a reassessment of the integrated impact of tropical cyclones on surface chlorophyll in the western subtropical north atlantic the impact of tropical cyclones on surface chlorophyll concentration is assessed in the western subtropical north atlantic ocean during 1998 2011 previous studies in this area focused on individual cyclones and gave mixed results regarding the importance of tropical cyclone induced mixing for changes in surface chlorophyll using a more integrated and comprehensive approach that includes quantification of cyclone induced changes in mixed layer depth here it is shown that accumulated cyclone energy explains 22 of the interannual variability in seasonally averaged june november chlorophyll concentration in the western subtropical north atlantic after removing the influence of the north atlantic oscillation nao the variance explained by tropical cyclones is thus about 70 of that explained by the nao which has well known impacts in this region it is therefore likely that tropical cyclones contribute significantly to interannual variations of primary productivity in the western subtropical north atlantic during the hurricane season

large eddy simulations of upper ocean response to a midlatitude storm and comparison with observations abstract a large eddy simulation les model is used to investigate an upper ocean response to a fall storm in the open ocean of the north pacific ocean the storm is characterized by rapid increases in wind speed and surface heat loss but a relatively steady wave field the les model shows that surface convergence zones or windrows organize into line patterns aligned with the wind direction evolving from nearly parallel lines to irregular structures featuring y junctions as the wind speed increases the downwelling to upwelling velocity ratio ranges between 1 2 and 1 6 indicating a moderate level of asymmetry between the downwelling and upwelling plumes in langmuir circulation during the storm the turbulent langmuir number lat increases from 0 2 to 0 5 while the vertical turbulence intensity w2 decreases from 1 4 to 0 7 u 2 where u is the friction velocity the order of turbulence intensities in three directions switches from crosswind vertical downwind directions to downwind crosswind ver