moored wind temperature and current observations made during coastal ocean dynamics experiments 1 and 2 over the northern california continental shelf and upper slope moored observations of winds currents and temperature made over the northern california shelf and upper slope during the 1981 and 1982 upwelling seasons as part of the coastal ocean dynamics experiment code are described in both field experiments code 1 and code 2 the onset of the upwelling season is triggered by the strengthening of the north pacific high off northern california and signalled by the presence of water colder than 9 c near the bottom over the shelf vertical temperature stratification over the shelf is reduced during active upwelling local winds and subtidal currents over the shelf are strongly polarized in the alongshelf direction and the mean wind stress is directed equatorward response of alongshelf currents to wind forcing is similar at all depths over the shelf the response of the cross shelf current is more complex in the surface layer offshelf flow is significantly and positively correlated with the upwelling favorable alongshelf wind stress beneath this layer a weak return flow exists the thickness of the upper mixed layer varies greatly reaching 60 m during upwelling events thus direct wind forcing affects a substantial fraction of the water over the shelf low frequency wind stress current and temperature fields are adequately described by a few energetic empirical orthogonal functions with simple spatial structure the most energetic mode typically accounts for 75 or more of the variance of wind stress and temperature over the middle and inner shelf the most energetic current mode accounts for 90 or more of the variance is dominated by he alongshelf component and veers to the left with depth the low frequency alongshelf flow fluctuations are quasi barotropic with some vertical shear but no reversal with depth vertical shear in alongshelf current and the cross shelf density gradient obey the thermal wind relation the simple structure of the subdiurnal currents allow estimation of the alongshelf volume transport between the 60 and 130 m isobaths through three cross shelf transects in code 2 volume transport over the shelf is often nearly two dimensional but occasional large differences indicate significant mass exchange between the shelf and the adjacent upper slope correlation of low frequency currents and alongshelf wind stress shows the response of alongshelf current to be maximum near the surface and near midshelf where a 15 cm 1 alongshelf flow lags a 1 dyn cm 2 alongshelf wind stress by the order of 10 hours currents over the upper slope are not significantly correlated with local wind alongshelf transport over the shelf is highly correlated with local wind stress explaining 80 of the variance in the low frequency transport during code 2 volume transport is best correlated with wind stress approximately 30 km to the south winds in the code area during spring and summer are characterized by strong and persistent upwelling favorable winds interrupted by shorter periods of weak winds regression analysis indicates that in the absence of wind a poleward barotropic current jet exists over the shelf with a maximum amplitude over the inner shelf in the code area an upwelling favorable wind counters this jet over the shelf so that the alongshore flow is everywhere equator ward during strong wind events since the maximum response to wind forcing is found at midshelf and near surface the mean current over the upwelling season is strongly sheared in both the vertical and cross shelf directions mean flow over the outer shelf is surface intensified and is directed offshelf and equatorward while the deeper flow at midshelf and through most of the water column over the inner shelf is directed poleward

north pacific cloud feedbacks inferred from synoptic scale dynamic and thermodynamic relationships abstract daily satellite cloud observations and reanalysis dynamical parameters are analyzed to determine how midtropospheric vertical velocity and advection over the sea surface temperature gradient control midlatitude north pacific cloud properties optically thick clouds with high tops are generated by synoptic ascent but two different cloud regimes occur under synoptic descent when vertical motion is downward during summer extensive stratocumulus cloudiness is associated with near surface northerly wind while frequent cloudless pixels occur with southerly wind examination of ship reported cloud types indicates that midlatitude stratocumulus breaks up as the boundary layer decouples when it is advected equatorward over warmer water cumulus is prevalent under conditions of synoptic descent and cold advection during winter poleward advection of subtropical air over colder water causes stratification of the near surface layer that inhibits upward mixing of moisture and suppresses cloudiness until a

a cold path for the gulf stream troposphere connection abstractthe mechanism by which the gulf stream sea surface temperature sst front anchors a band of precipitation on its warm edge is still a matter of debate and little is known about how synoptic activity contributes to the mean state in the present study the influence of the sst front on precipitation is investigated during the course of a single extratropical cyclone using a regional configuration of the met office unified model the comparison of a control run with a simulation in which sst gradients were smoothed brought the following conclusions a band of precipitation is reproduced for a single extratropical cyclone and the response to the sst gradient is dominated by a change of convective precipitation in the cold sector of the storm several climatological features described by previous studies such as surface wind convergence on the warm edge or a meridional circulation cell across the sst front are also reproduced at synoptic time scales in the cold sector based on these results a s

bacterial oxidation of manganese and iron in a modern cold spring a marshy cold spring occurs in late pleistocene glacial outwash exposed on the floor of the squalicum creek valley near bellingham washington a 5 m by 25 m zone of black soil with an average depth of 30 cm surrounds the spring this soil contains about 43 mno 2 and 20 to 30 iron oxide calculated as fe 2 o 3 the oxidized material appears amorphous when analyzed by x ray diffraction field observations and laboratory studies indicate mn and fe are accumulated due to bacterial oxidation of trace amounts of these metals supplied by ground water two strains of pseudomonad bacteria isolated from the black soil rapidly oxidize fe and mn when grown on a culture medium containing soil organic matter as a nutrient both bacteria can be cultured on tryptone glycerol agar but are unable to oxidize mn or fe added to this synthetic medium although the composition of the culture medium is important in controlling whether oxidation occurs the reaction is not merely due to the catalytic effect of hydroxy acids contained within the nutrient mixture optical microscopy and x ray fluorescence analysis using a scanning electron microscope equipped with an energy dispersive detector reveal that fe and mn oxides precipitated by the microbes occur as extra cellular deposits and these metals are not accumulated within the bacterial cells although microbiologists have shown that several genera of bacteria are able to oxidize mn in laboratory cultures these studies are of uncertain value when used to explain the role microbes play in sedimentary mn oxide deposits because most studies have involved microbes isolated from ordinary soil rather than from mn rich environments this locality demonstrates the ability of soil bacteria to accumulate high concentrations of fe and mn under natural conditions

a variational scheme for retrieving ice cloud properties from combined radar lidar and infrared radiometer 1 a variational method is described for retrieving profiles of visible extinction coefficient ice water content and effective radius in ice clouds using the combination of ground based or spaceborne radar lidar and infrared radiometer the forward model includes effects such as non rayleigh scattering by the radar and molecular and multiple scattering by the lidar by rigorous treatment of errors and a careful choice of state variables and associated a priori estimates a seamless retrieval is possible between regions of the cloud detected by both radar and lidar and regions detected by just one of these two instruments thus when the lidar signal is unavailable for reasons such as strong attenuation the retrieval tends toward an empirical relationship using radar reflectivity factor and temperature and when the radar signal is unavailable such as in optically thin cirrus accurate retrievals are still possible from the combination of lidar and radiometer the method is tested first on simulated profiles from aircraft data and then on real observations taken in west africa it would be straightforward to expand the approach to include other measurements simply by including a forward model for them

pedogenic manganese oxide coatings calcium buserite on fracture surfaces in tortonian upper miocene red mudstones southern turkey abstract fracture surfaces of red mudstones overbank deposits within the kuzgun formation of late miocene tortonian age are coated by thin black colored manganese oxide beneath a thin soil cover in the mersin area of southern turkey these manganese oxide coatings have been investigated by a range of analytical techniques including x ray diffraction xrd infrared spectral ir differential thermal analysis thermal gravimetric dta tg scanning electron microscopy and energy dispersive x ray sem edx analyses the basal reflections at 10 00 7 22 5 00 3 35 2 50 2 29 and 2 10 a sharp infrared spectral lines at 469 and 519 cm 1 and typical dehydration of interlayer water

influence of small scale north atlantic sea surface temperature patterns on the marine boundary layer and free troposphere a study using the atmospheric arpege model a high resolution global atmospheric model is used to investigate the influence of the representation of small scale north atlantic sea surface temperature sst patterns on the atmosphere during boreal winter two ensembles of forced simulations are performed and compared in the first ensemble hres the full spatial resolution of the sst is maintained while small scale features are smoothed out in the gulf stream region for the second ensemble smth the model shows a reasonable climatology in term of large scale circulation and air sea interaction coefficient when compared to reanalyses and satellite observations respectively the impact of small scale sst patterns as depicted by differences between hres and smth shows a strong meso scale local mean response in terms of surface heat fluxes convective precipitation and to a lesser extent cloudiness the main mechanism behind these statistical differences is that of a simple hydrostatic pressure adjustment related to increased sst and marine atmospheric boundary layer temperature gradient along the north atlantic sst front the model response to small scale sst patterns also includes remote large scale effects upper tropospheric winds show a decrease downstream of the eddy driven jet maxima over the central north atlantic while the subtropical jet exhibits a significant northward shift in particular over the eastern mediterranean region significant changes are simulated in regard to the north atlantic storm track such as a southward shift of the storm density off the coast of north america towards the maximum sst gradient a storm density decrease is also depicted over greenland and the nordic seas while a significant increase is seen over the northern part of the mediterranean basin changes in rossby wave breaking frequencies and weather regimes spatial patterns are shown to be associated to the jets and storm track changes

low latitude boundary layer clouds as seen by calipso 1 the distribution of low level cloud in the tropical belt is investigated using 6 months of level 2 retrievals from cloud aerosol lidar and infrared pathfinder satellite observation calipso at 333 m and 1 km horizontal resolutions regional patterns of tropical clouds emerge from the data matching expectations from existing observations the advantage of the lidar is highlighted by the distribution of cloud top height revealing the preponderance of low level clouds over the tropical oceans over land cloud top is more uniformly distributed under the influence of diurnal variation the integrated cloud top distribution suggests tropical marine low cloud amount around 25 30 a merged calipso cloudsat product has a similar cloud top distribution and includes a complementary estimate of cloud fraction based on the lidar detections the low cloud distribution is similar to that found in fields of shallow cumulus observed during the rain in cumulus over the ocean rico field study the similarity is enhanced by sampling near the rico site or sampling large scale conditions similar to those during rico this finding shows how satellite observations can help to generalize findings from detailed field observations

momentum balances on the north carolina inner shelf four months of moored current pressure temperature conductivity wave and wind observations on the north carolina shelf indicate three dynamically distinct regions the surf zone the inner shelf between the surf zone and the 13 m isobath and the midshelf in the surf zone the along shelf momentum balance is between the cross shelf gradient of the wave radiation stress and the bottom stress the linear drag coefficient in the surf zone is about 10 times larger than seaward of the surf zone on the inner shelf the along shelf momentum balance is also frictional the along shelf wind stress and pressure gradient are balanced by bottom stress in the cross shelf momentum balance the pressure gradient is the superposition of roughly equal contributions from the coriolis force geostrophy and wave setdown from shoaling unbroken surface gravity waves at midshelf the along shelf momentum balance is less frictional and hence flow accelerations are important the cross shelf momentum balance is predominantly geostrophic because the greater depth and smaller bottom slope at midshelf reduce the importance of wave setdown the cross shelf density gradient is in thermal wind balance with the vertical shear in the along shelf flow in depths as shallow as 10 m the dominant along shelf momentum balances provide a simple estimate of the depth averaged along shelf current in terms of the measured forcing i e wind stress wave radiation stress divergence and along shelf pressure gradient that reproduces accurately the observed cross shelf variation of the depth averaged along shelf current between the surf zone and midshelf

satellite measurements reveal persistent small scale features in ocean winds four year averages of 25 kilometer resolution measurements of near surface wind speed and direction over the global ocean from the quikscat satellite radar scatterometer reveal the existence of surprisingly persistent small scale features in the dynamically and thermodynamically important curl and divergence of the wind stress air sea interaction over sea surface temperature fronts throughout the world ocean is evident in both the curl and divergence fields as are the influences of islands and coastal mountains ocean currents such as the gulf stream generate distinctive patterns in the curl field these previously unresolved features have important implications for oceanographic and air sea interaction research

manganese rich rock varnish does occur in antarctica abstract despite accounts to the contrary we have found that mn rich rock varnish is present in antarctica as others have before it is chemically and texturally similar to many varnishes found in lower latitudes antarctic varnishes show considerable potential as a dating and paleoenvironmental research tool

low level cloud response to the gulf stream front in winter using calipso a sharp sea surface temperature front develops between the warm water of the gulf stream and cold continental shelf water in boreal winter this front has a substantial impact on the marine boundary layer the present study analyzes and synthesizes satellite observations and reanalysis data to examine how the sea surface temperature front influences the three dimensional structure of low level clouds the cloud aerosol lidar and infrared pathfinder satellite observations calipso satellite captures a sharp lowlevel cloud transition across the gulf stream front a structure frequently observed under the northerly condition low level cloud top 4km increases by about 500m from the cold to the warm flank of the front the sea surface temperature front induces a secondary low level circulation through sea level pressure adjustment with ascending motion over the warm water and descending motion over cold water the secondary circulation further contributes to the cross frontal transition of low level clouds composite analysis shows that surface meridional advection over the front plays an important role in the development of the marine atmospheric boundary layer and low level clouds under cold northerly advection over the gulf stream front strong near surface instability leads to a well mixed boundary layer over the gulf stream causing southward deepening of low level clouds across the sea surface temperature front moreover the front affects the freezing level by transferring heat to the atmosphere and therefore influences the cross frontal variation of the cloud phase

observed variations of the atmospheric boundary layer and stratocumulus over a warm eddy in the kuroshio extension abstracta research vessel sailing across a warm eddy in the kuroshio extension on 13 april 2016 captured an abrupt development of stratocumulus under synoptic high pressure shipboard observations

ocean currents along a nearshore frontal zone on the continental shelf of the southeastern united states abstract river and estuarine discharges mix to form a frontal zone along a 400 km length of the coast of the south eastern united states the frontal width extends from the coast outward 10 20 km two ships anchored across the frontal zone during autumn obtained simultaneous hourly profiles of currents and density for five consecutive tidal cycles the frontal zone contained a baroclinic coastal current flowing southward the flow was strongly convergent more water entered on the coastal side than exited on the seaward side much of the inflow was apparently turned southward thus the frontal zone acted as a dynamic barrier that inhibited the advection of mixed river discharge farther offshore a thermal wind relationship suitably predicted vertical shear through the frontal zone bottom friction seemed to play only a secondary role data suggest that the baroclinic coastal current was modified by the presence of a barotropic current seaward of the frontal zone the force responsible for the barotrop

effects of the hawaiian islands on the vertical structure of low level clouds from calipso lidar the steady northeast trade winds impinge on the hawaiian islands producing prominent island wakes of multispatial scales from tens to thousands of kilometers cloud aerosol lidar and infrared pathfinder satellite observations calipso reveal rich three dimensional structures of low level clouds that are induced by the islands distinct from the background environment the cloud frequency peaks between 1 5 and 2 0 km in cloud top elevation over the windward slopes of the islands of kauai and oahu due to orographic lifting and daytime island heating in the nighttime near island wake of kauai calipso captures a striking cloud hole below 1 6 km as the cold advection from the island suppresses low level clouds the cyclonic eddy of the mechanical wake behind the island of hawaii favors the formation of low level clouds below 2 5 km and the anticyclonic eddy suppresses the low level cloud formation indicative of the dynamical effect on the vertical structure of low level clouds in the long hawaiian wake due to air sea interaction low level clouds form over both the warmer and colder waters but the cloud tops are 400 600 m higher over the warm than the cold waters in addition the day night differences and the sensitivity of low level clouds to the background trade wind inversion height are also studied

transport and fate of river discharge on the continental shelf of the southeastern united states the authors analyzed 8 years of wind and salinity data from a frontal zone in a region of the inner continental shelf off the southeastern united states the changes in low salinity water stored in the frontal zone have been parameterized by analyzing the monthly rate of change in freshwater content when the rate of change in freshwater content was negative this was interpreted as a loss of low salinity water from the frontal zone when this parameter was compared with seasonally averaged alongshore wind stress the rate of loss was independent of the alongshore wind stress magnitude until threshold of about 0 1 dyne cm sup 2 was reached above the threshold there was a clear relationship between northward alongshore wind stress and rate of loss of freshwater from the inner shelf experimental evidence suggests that horizontal currents in the inner shelf frontal zone have cyclonic shear with increasing depth when wind stress is northward and offshore near surface low salinity water is transported offshore by ekman transport while near bottom high salinity water is transported shoreward 9 figures 2 tables

ocean frontal effects on the vertical development of clouds over the western north pacific in situ and satellite observations abstract a suite of shipboard and satellite observations are analyzed and synthesized to investigate the three dimensional structure of clouds and influences from sea surface temperature fronts over the western north pacific sharp transitions are observed across the kuroshio extension ke front in the marine atmospheric boundary layer mabl and its clouds the ocean s influence appears to extend beyond the mabl with higher cloud tops in altitude along the ke front than the surroundings in winter intense turbulent heat release from the ocean takes place on the southern flank of the ke front where the cloud top penetrates above the mabl and reaches the midtroposphere in this band of high cloud tops frequent lightning activity is observed the results of this study suggest a sea level pressure mechanism for which the temperature gradient in the mabl induces strong surface wind convergence on the southern flank of the ke front deepening the clouds there in early summer sea fog frequently occurs on

on the role of sea surface temperature gradients in forcing low level winds and convergence in the tropics abstract we examine the importance of pressure gradients due to surface temperature gradients to low level p 700 mb flow and convergence in the tropics over time scales 1 month the latter plays a crucial role in determining the distribution of cumulonimbus convection and rainfall our approach is to consider a simple one layer model of the trade cumulus boundary layer wherein surface temperature gradients are mixed vertically consistent with ecmwf analyzed data the top of the layer is taken at 700 mb the influence from higher levels is intentionally suppressed by setting horizontal pressure gradients and frictional stresses to zero at the top of the layer horizontal convergence within the layer is taken up by cumulonimbus mass flux however the development of the cumulonimbus mass flux is associated with a short relaxation time o hr roughly the development time for such convection during this short time horizontal convergence acts to redistribute mass so as to reduce horizontal pressur

a groundwater hypothesis for the origin of fire areas on the northern channel islands california abstract pleistocene areas of red sediments and carbonized vegetation on the northern channel islands california have in the past been interpreted as caused by fires of either natural or human origin some are associated with darkened mammoth and bird fossils and these fossils have been considered as having been burned by early man reevaluation of these so called fire areas indicates that the above phenomena are the result of low temperature 100 c nonheating processes occurring in groundwater evidence for this conclusion is derived from field observations on fossil carbonized vegetation and the geology of the areas additional evidence derives from experiments on the red sediments and fossil wood x ray diffraction analyses magnetic analyses studies on the clay minerals smectite and illite and the demonstration that fossil mammoth bone contains sufficient fe and mn to account for their discoloration much of the carbonization of vegetation probably occurred in water rather than in fire radiocarbon dates from the islands will probably need to be reevaluated these data provide evidence contrary to the concept of the occurrence of significant fires either natural or set by early man on the northern channel islands

a modeling study of shelf circulation off northern california in the region of the coastal ocean dynamics experiment 2 simulations and comparisons with observations 1 this is the second part of a modeling study of wind forced flow on the continental shelf off northern california in the region 37 40 n of the coastal ocean dynamics experiment code gan and allen 2002 analyzed the shelf flow response to idealized wind stress forcing in a process oriented study the study here applies forcing from observed winds and heat flux for april may 1982 and compares the model results with moored current and temperature measurements the princeton ocean model pom is used in a three dimensional limited area domain with a high resolution curvilinear grid approximately 1 km horizontal spacing 60 vertical levels and realistic coastline and bottom topography the objectives of the study are to simulate the response of the shelf circulation field to time varying observed wind stress and heat flux to compare model results with oceanographic observations to establish confidence in the model and to subsequently analyze the model fields and the model dynamical balances to help understand the behavior of the observed flow the model variables show overall good agreement with corresponding observations similar to the conclusions by gan and allen 2002 it is found that the alongshore variability of upwelling is mainly controlled by the interaction of the wind forced shelf flow with the coastline and bottom topography different dynamical regimes in the regions north and south of the coastal capes formed by pt reyes and pt arena and in the more uniform region between these capes are identified and investigated the results demonstrate that the coastal capes play a dominant role in causing alongshore variability of the upwelling flow including the setup of an alongshore pressure gradient that forces northward currents during relaxation of southward upwelling favorable winds an analysis of the balance of terms in the equation for potential temperature indicates that across shore temperature advection is the major contributor to the cooling of coastal water during upwelling with a larger magnitude to the south of the capes to the north of the capes however alongshore temperature advection is the dominant contributor to the colder water near the coast

relaxation from upwelling in the coastal ocean dynamics experiment a relaxation of the upwelling system on the northern california shelf occurs when upwelling favorable winds decay or reverse observations from the coastal ocean dynamics experiment are used to investigate this process with emphasis on the near surface temperature evolution models of relaxation warming are tested for the surface layer 0 30 m over midshelf with the result that the surface heat flux and poleward alongshelf advection can account for the observed temperature behavior onshore advection of the upwelled isopycnal field is a relatively unimportant contribution the warming patterns that are observed and which provide the gradients for the advective process have wedgelike shapes warmest inshore and in the south of the experimental area these patterns appear to be related to a topographic influence of point reyes possibly through the generation of gradients in the wind field remote advection of warm water from as far south as san francisco occasionally occurs as well the nature of the relaxation mechanism has general implications a new warm saline nutrient rich water mass may be formed in the surface layer since the warming processes are not the reverse of the cooling an important asymmetry is present it causes time variable upwelling to generate conditions very different from steady upwelling a new upwelling front is created during each event with upwelled water seaward of it and reversed alongshelf flow contributes to the warming and exchange mechanisms the system cannot be described or understood without the irreversible processes during upwelling and relaxation or without a mixed layer

the inner shelf response to wind driven upwelling and downwelling abstract a two dimensional numerical model is used to study the response to upwelling and downwelling favorable winds on a shelf with a strong pycnocline during upwelling or downwelling the pycnocline intersects the surface or bottom forming a front that moves offshore the characteristics of the front and of the inner shelf inshore of the front are quite different for upwelling and downwelling for a constant wind stress the upwelling front moves offshore at roughly a constant rate while the offshore displacement of the downwelling front scales as t because the thickness of the bottom layer increases as the front moves offshore the geostrophic alongshelf transport in the front is larger during downwelling than upwelling for the same wind stress magnitude because the geostrophic shear is near the bottom in downwelling as opposed to near the surface in upwelling during upwelling weak stratification is maintained over the inner shelf by the onshore flux of denser near bottom water this weak stratif

mesoscale stratocumulus bands caused by gulf stream meanders abstract examination of visible and infrared imagery from geosynchronous and polar orbiter satellites reveals the occasional existence of mesoscale cloud bands of unusual width and area originating over the open northwest atlantic ocean during cold air outbreaks this phenomenon is of both dynamic and synoptic interest as a dynamic phenomenon it represents a mesoscale flow that is driven by transient surface features which are meanders in the gulf stream the forcing geometry and the resulting cloud pattern are similar in many respects to the anomalous cloud lines observed downwind of chesapeake and delaware bays in similar conditions these open ocean cloud bands are often of a larger scale however because the gulf stream meanders represent the largest scale high amplitude coastal features in the western north atlantic these cloud bands are of synoptic interest because when present they play a major role in determining the cloud pattern over much of this oceanic region examination of surface

a modeling study of shelf circulation off northern california in the region of the coastal ocean dynamics experiment response to relaxation of upwelling winds 1 a two part modeling study of the wind forced flow on the continental shelf off northern california in the region 37 40 n of the coastal ocean dynamics experiment code is pursued this paper involves a process oriented study with idealized wind stress forcing gan and allen 2002 involves forcing with observed winds and heat flux for april may 1982 and comparison of model results with code observations a characteristic but previously unexplained response observed during code following the weakening or relaxation of southward upwelling favorable winds is the time dependent development of northward currents over the inner shelf next to the coast the presence of northward winds is not necessary for this occurrence the objective in this paper is to investigate the dynamics of the shelf flow response to upwelling wind relaxation events under idealized conditions in the basic case experiment a spatially uniform upwelling favorable southward wind stress of 0 1 pa is applied to the ocean initially at rest the stress is held constant for 10 days and then decreased linearly to zero over 3 days in response to the southward wind stress southward alongshore currents develop on the shelf accompanied by upwelling of cold dense water near the coast considerable spatial variability in the shelf flow clearly related to the alongshore variations in coastline and bottom topography is found the alongshore currents tend to separate from the coast south of capes and the coldest surface water is found at those locations as the winds decrease northward currents similar to those observed develop on the inner shelf next to the coast at many alongshore locations examination of the alongshore momentum balances shows that the northward currents are forced by a northward pressure gradient force associated with negative alongshore pressure gradients these pressure gradients are set up by the interaction of the wind forced flow with the alongshore variations in shelf topography in general negative alongshore pressure gradients intensified off pt reyes and pt arena by the gradient wind balance are found south of capes the negative pressure gradients geostrophically balance onshore flow at depth and upwelling is strengthened in these locations north of capes positive pressure gradients that are primarily in balance with nonlinear advective effects are found after the winds cease the forced across shelf circulation weakens and the resulting unbalanced negative pressure gradients south of the capes accelerate the alongshore currents northward processes with similar dynamics are found embedded in the more complex coastal ocean response to observed time varying winds by gan and allen 2002

the vertical cloud structure of the west african monsoon a 4 year climatology using cloudsat and calipso the west african summer monsoon wam is an important driver of the global climate and locally provides most of the annual rainfall a solid climatological knowledge of the complex vertical cloud structure is invaluable to forecasters and modelers to improve the understanding of the wam in this paper 4 years of data from the cloudsat profiling radar and calipso are used to create a composite zonal mean vertical cloud and precipitation structure for the wam for the first time the near coincident vertical radar and lidar profiles allow for the identification of individual cloud types from optically thin cirrus and shallow cumulus to congestus and deep convection a clear diurnal signal in zonal mean cloud structure is observed for the wam with deep convective activity enhanced at night producing extensive anvil and cirrus while daytime observations show more shallow cloud and congestus a layer of altocumulus is frequently observed over the sahara at night and day extending southward to the coastline and the majority of this cloud is shown to contain supercooled liquid in the top the occurrence of deep convective systems and congestus in relation to the position of the african easterly jet is studied but only the daytime cumulonimbus distribution indicates some influence of the jet position

the effects of sst induced surface wind speed and direction gradients on midlatitude surface vorticity and divergence abstract the effects of surface wind speed and direction gradients on midlatitude surface vorticity and divergence fields associated with mesoscale sea surface temperature sst variability having spatial scales of 100 1000 km are investigated using vector wind observations from the seawinds scatterometer on the quick scatterometer quikscat satellite and sst from the advanced microwave scanning radiometer for earth observing system amsr e aqua satellite the wind sst coupling is analyzed over the period june 2002 august 2008 corresponding to the first 6 years of the amsr e mission previous studies have shown that strong wind speed gradients develop in response to persistent mesoscale sst features associated with the kuroshio extension gulf stream south atlantic and agulhas return current regions midlatitude sst fronts also significantly modify surface wind direction the surface wind speed and direction responses to typical sst differences of about 2 4 c are on average about 1 2 m s 1 and 4

nearshore coastal currents on the south carolina continental shelf simultaneous current sea level wind and atmospheric pressure data from the south carolina nearshore shelf during the summer are analyzed and compared the current record was taken in the nearshore region at 10m depth an area where the current regime has not been well studied most of the variance in the series is concentrated in two frequency bands 1 2 12 days meteorological and 2 12 25 hours tidal and daily the variance of the two bands is approximately equal in both the alongshore and the cross shore current components but net flow is primarily due to low frequency events the nearshore current flows predominantly to the northeast possibly an ekman response to the northerly blowing wind regime current reversals occur in response to frontal passages approximately every 6 days low frequency alongshore currents and winds are highly coherent at 2 12 days with the currents having a phase lag of about 3 hours cross shore currents are not coherent with cross shore winds but have a statistically significant 7 hour lag to alongshore currents coastal sea level is also coherent with alongshore currents lagging by 15 hours at 4 4 days indicating that the nearshore current may drive sea level changes the reason for the significant lag in sea level is not clearly understood

a cloud line over the gulf stream 1 a 1000 km long cloud line over the major axis of the gulf stream was detected in imagery from a number of satellites on april 24 2001 analysis of environmental conditions shows that such a cloud line is formed when the synoptic low level wind is parallel to the gulf stream axis and the sky is clear conditions that rarely occur in the high temperature and high moisture gulf stream region the psu ncar fifth generation mesoscale model mm5 is used to study the cloud line results show that upward motion of the air in the middle of the gulf stream caused by mesoscale solenoidal circulation induced by the large surface thermal gradient is the source for the large cloud line formation this cloud line formation mechanism is different from that of commonly observed ship cloud lines induced by ship stack emissions and its extent is much longer than that of cloud lines induced by lake effects

dynamical analyses of marine atmospheric boundary layer structure near the gulf stream oceanic front the effects of the sea surface temperature s s t front at the edge of the gulf stream on the marine atmospheric boundary layer mabl are investigated using a numerical model to study the modification effects of an oceanic front on the mabl structure the situation simulated is flow from over cold shelf water to over the warm water of the gulf stream the initial temperature and humidity profiles of the air are specified to be near neutral over the cold water and are therefore typical of undisturbed conditions the differential in s s t across the oceanic front creates a horizontal variation in the surface perturbation pressure and the stability the surface perturbation pressure and turbulent fluxes modulate the flow and produce horizontal variations in horizontal wind components with associated vertical motions a thermally direct cell is produced as a result of the s s t difference across the front the isotherms slope upward towards the warm water entrainment of inversion layer air and upward vertical motion over the warm water cause the mabl to be deeper there a layer of cloud forms over warm water and is associated with mixed layer deepening rather than lowering of the condensation level turbulent fluxes in the mabl show considerable spatial variation surface stress is much larger over the front and over the warm water than over the cold water this is mostly caused by wind speed changes associated with the front changes in the drag coefficient due to changes in surface roughness and stability are much less important mean budgets for temperature and total water indicate that there is a balance between horizontal advection and turbulent flux divergence the u momentum budget shows that once the geostrophic balance terms are subtracted the balance is mainly between the pressure gradient force associated with the induced temperature field and turbulent friction with horizontal advection and the coriolis force acting on the geostrophic departure playing minor roles the v momentum budget shows a balance between horizontal advection coriolis force and friction although there are few data for comparison the results are in qualitative agreement with observations in the area this study shows that the s s t front at the gulf stream edge produces marked local changes in the nearby atmospheric surface layer

cross shore variation of wind driven flows on the inner shelf in long bay south carolina united states and exceeded 0 1 n m 2 vertical mixing occurred the two layered flow pattern disappeared and currents were directed alongshore with the wind at all sites and throughout the water column in the fall near bed flows close to the shore water depth 7 m were often reduced compared to or opposed those measured farther offshore under southwestward winds a simplified analysis of the depth averaged alongshore momentum balance illustrates that the alongshore pressure gradient approached or exceeded the magnitude of the alongshore wind stress at the same time that the nearshore alongshore current opposed the wind stress and alongshore currents farther offshore in addition the analysis suggests that the wind stress is reduced closer to shore so that the alongshore pressure gradient is large enough to drive the flow against the wind

explosive cyclogenesis in the west central north atlantic ocean 1981 84 part i composite structure and mean behavior abstract tracks and central values of surface low pressure centre and 500 mb absolute vorticity maxima were gathered from operational analysis for 48 casts of expressive cyclogenesis in the west central north atlantic the cases were stratified into relatively strong moderate and weak categories tracking was done from 36 h before to 24 h after the time of most rapid surface deepening the surface center often first appeared only 12 to 24 h before maximum deepening but the upper vorticity maximum was present 36 h or more in advance often many days mean motion of the surface low was rapidly northeastward from the southeastern states or just offshore to newfoundland intense deepening occurred in a period of no more than 24 36 h strong cyclones moved most rapidly and most meridionally traveled farther over warm water and deepened dramatically in a single 12 h period while crossing the closely spaced isotherms of sea surface temperature north of the gulf stream the upper vorticity center moved rapid

flow reversals during upwelling conditions on the new jersey inner shelf 1 the temporal evolution of a flow reversal during upwelling conditions along new jersey s inner shelf is characterized with shipboard moored and remote observations the flow reversal occurs nearshore in the form of a subsurface jet with maximum velocities exceeding 30 cm s the jet is most intense in the thermocline commences during maximum alongshore wind stress and has a spin up time approximately equal to the local inertial period the jet also has a surface signature apparent in ocean current radar data that shows the jet veering offshore and feeding an upwelling center that drifts southward at 5 cm s moored instrumentation within the upwelling center indicates that cross shelf transport in the warm surface layer is consistent with the predicted ekman transport prior to the spin up of the jet but exceeds ekman transport thereafter however onshore transport in the lower layer never compensates for offshore flow in the surface layer suggestive that the mass balance requires a three dimensional closure finally we suggest that the flow reversal provides a significant fraction of cool water to the evolving upwelling center and that the offshore veering is due to enhanced friction over a shoaling and rougher topography

the gulf stream rainband a recurrent and almost stationary region of banded clouds and precipitation has been identified over the gulf stream off cape hatteras north carolina in winter this rainband is attributed to the large fluxes of heat and moisture from the warm waters of the gulf stream to the colder overlying air it is speculated that the gulf stream rainband could play a role in cyclogenesis which is common off the carolina coast

modeling stratified wave and current bottom boundary layers on the continental shelf the glenn and grant 1987 continental shelf bottom boundary layer model for the flow and suspended sediment concentration profiles in the constant stress layer above a noncohesive movable sediment bed has been updated the reynolds fluxes for sediment mass and fluid momentum are closed using a continuous time invariant linear eddy viscosity modified by a continuous stability parameter to represent the influence of suspended sediment induced stratification throughout the constant stress region glenn and grant 1987 use a less realistic discontinuous eddy viscosity and neglect the stratification correction in the wave boundary layer for typical model parameters the two models produce currents above the wave boundary layer that are in better agreement than the suspended sediment concentrations within the wave boundary layer the differences are much greater for both the current and the sediment concentration this leads to significant differences in the sediment transport throughout the constant stress layer sensitivities of the updated model were examined on the basis of observed wave and current data acquired during storms on the inner continental shelf comparisons between the stratified and neutral versions of the updated model indicate that the stratified version produces a total depth integrated sediment transport that can be 2 orders of magnitude less than and time averaged shear velocities that can be nearly half of that predicted by the neutral version sensitivities to grain size distributions indicate that even a small amount of finer sediment can stratify the storm driven flows sensitivities to closure constants within the range of reported values also produce up to an order of magnitude variation in sediment transport illustrating the need for dedicated field experiments to refine further estimates of these parameters

rock varnish in new york an accelerated snapshot of accretionary processes abstract samples of manganiferous rock varnish collected from fluvial bedrock outcrop and erie barge canal settings in new york state host a variety of diatom fungal and bacterial microbial forms that are enhanced in manganese and iron use of a dual beam focused ion beam scanning electron microscope to manipulate the varnish in situ reveals microbial forms that would not have otherwise been identified the relative abundance of mn fe enriched biotic forms in new york samples is far greater than varnishes collected from warm deserts moisture availability has long been noted as a possible control on varnish growth rates a hypothesis consistent with the greater abundance of mn enhancing bioforms sub micron images of incipient varnish formation reveal that varnishing in new york probably starts with the mortality of microorganisms that enhanced mn on bare mineral surfaces microbial death results in the adsorption of the mn rich sheath onto the rock in the form of filamentous networks clay minerals are then cemented by remobilization of the mn rich material thus the previously unanswered question of what comes first clay mineral deposition or enhancement of mn can be answered in new york because of the faster rate of varnish growth in contrast very slow rates of varnishing seen in warm deserts of microns per thousand years make it less likely that collected samples will reveal varnish accretionary processes than samples collected from fast accreting moist settings

two regimes of cloud water over the okhotsk sea and the adjacent regions around japan in summer this study derived two regimes of cloud water with a dipole structure between over the okhotsk sea and over the adjacent regions around japan in summer by using a climate index for cool summer when the okhotsk high develops clouds are confined to a thin low level layer owing to the enhanced stability in the lower atmosphere induced by the downward motion associated with the okhotsk high the resulting optically thin clouds allow more downward shortwave radiation to reach the surface of the okhotsk sea in contrast the low level easterly winds blowing toward the japanese islands and the eurasian continent enhance cloud formation this is due to the convergence of the water vapor flux induced by the easterly winds associated with the okhotsk high and the southerly winds associated with the baiu frontal zone and the pacific high and due to the orographic uplift of air mass when a cyclonic circulation occurs over the okhotsk sea a thick layer of low level clouds extending close to the sea surface is formed the convergence of the water vapor flux over the subarctic sea surface temperature sst frontal zone and the cool sst promote fog formation and upward motion associated with the cyclonic circulation supports the high cloud water content from the lower to the upper troposphere the resulting optically thick clouds reduce the downward shortwave radiation at the surface of the okhotsk sea over the regions around japan water vapor flux diverges owing to dry air originating from land and cloud water decreases

mn and fe rich black travertine shrubs bacterially and nanobacterially induced precipitates abstract black shrubs i e arborescent forms are present within hot water travertine deposits from morocco the shrubs are commonly a few centimeters high and laterally grouped along individual laminae other than in mineral composition the black shrubs closely resemble the calcite shrubs from other hot water travertine deposits e g bagni di tivoli italy and mammoth hot springs yellowstone national park they are composed of a variety of minerals that are mn rich and also have a significant fe oxide component similar mn and fe rich shrub like forms have been described from desert varnish deep sea mn nodules and marine carbonates frutexites sem analyses show that bacterial bodies are densely packed within the mn rich black travertine shrubs whereas no bacterial bodies are evident within the enclosing aragonite and calcite laminae the bacterial bodies range in shape and size from rods commonly 0 8 m long by 0 1 m in diameter to spherical forms commonly 0 3 m in diameter that form chains up to 1 m long to nanobacterial spheres 150 to 200 nm in diameter that make up densely packed chains commonly 15 m in length it is well documented within the microbiological literature that not only do bacteria have the ability to induce the precipitation of mn and fe they can concentrate mn in mineral precipitates from waters with very low to essentially undetectable concentrations of mn the black mn rich shrubs within the moroccan travertines other hot water travertines and related features such as desert varnish deep sea mn nodules and frutexites are postulated to also be the result of bacterially induced precipitation

response of south carolina continental shelf waters to wind and gulf stream forcing during winter of 1986 the south carolina shelf water response to strong winter atmospheric forcing and gulf stream variations over the slope is discussed with the aid of a comprehensive set of atmospheric and oceanic observations made during project gale genesis of atlantic lows experiment a mixed response is observed to wind and gulf stream forcing subtidal variability of inner and middle shelf waters is primarily a barotropic forced response to coherent synoptic scale alongshore winds this response is not trapped over the shelf as has been found for other wide non equatorial shelves but is also significant at the shelf edge possibly because of the comparable widths of the shelf and slope the outer shelf also shows a significant gulf stream influence the gulf stream appears to have two preferred position modes either onshore with the stream flowing over the charleston bump and along the shelf break or offshore when the stream can be located up to 100 km east of the shelf break transition between the two states is rapid subtidal variability in the outer shelf is dominated by weekly period frontal eddies and meanders when the stream is in an onshore mode and by persistent southward flow when the stream is offshore this southward flow is produced by enlarged cyclonic eddies with upwelled centers located over the slope between the offshore stream and the shelf edge sometimes referred to as the charleston gyre positive mean alongshore sea level slopes at the shelf edge due to the persistence of the cyclonic gyres are geostrophically balanced by mean onshore flow which transports upwelled waters onto the shelf enhancing the biological productivity of the area relative to other regions of the south atlantic bight

low cloud transitions across the kuroshio front in the east china sea abstractthe east china sea kuroshio ecsk flows in the east asian monsoon region where the background atmospheric circulation varies significantly with season a sea surface temperature sst front associated with the ecsk becomes narrower and sharper from winter to spring the present study investigates how low clouds respond to the ecsk front in different seasons by synthesizing spaceborne lidar and surface visual observations the results reveal prominent cross frontal transitions in low clouds which exhibit distinct behavior between winter and spring in winter cloud responses are generally confined below 4 km by the strong background descending motion and feature a gradual cloud top elevation from the cold to the warm flank of the front the ice clouds on the cold flank of the ecsk front transform into liquid water clouds and rain on the warm flank the springtime clouds by contrast are characterized by a sharp cross frontal transition with deep clouds reaching up to 7 km over the ecsk in both

intrinsic versus extrinsic controls on the development of calcite dendrite bushes shuzhishi spring rehai geothermal area tengchong yunnan province china abstract in the rehai geothermal area located near tengchong there is an old succession of crystalline calcite that formed from a spring that is no longer active the thin bedded succession exposed on the south bank of zaotang river is formed of three dimensional dendrite bushes that are up to 6 cm high and 3 cm in diameter with multiple levels of branching bedding is defined by color which ranges from white to gray to almost black and locally accentuated by differential weathering that highlights the branching motif of the dendrites the succession developed through repeated tripartite growth cycles that involved phase i that was characterized by rapid vertical growth of the dendrite bushes with ever increasing branching phase ii that developed once growth of the dendrites had almost or totally ceased and involved an initial phase of etching that was followed by the precipitation of various secondary minerals sheet calcite trigonal calcite crystals hexagonal calcite crystals hexagonal plates formed of ca and p mn precipitates si mg reticulate coatings opal ct lepispheres on the branches of the calcite dendrites and phase iii that involved deposition of detrital quartz feldspar clay and calcite on top of the dendrite bushes the tripartite growth cycle is attributed primarily to aperiodic cycles in the co 2 content of the spring water that was controlled by subsurface igneous activity rather than climatic controls high co 2 coupled with rapid co 2 degassing triggered growth of the dendrite bushes as co 2 levels waned saturation levels in the spring water decreased and calcite dendrite growth ceased and precipitation of the secondary minerals took place possibly in the microcosms of microbial mats deposition of the detrital sediment was probably related to surface runoff that was triggered by periods of high rainfall critically this study shows that intrinsic factors rather than extrinsic factors e g climate were the prime control on the development of the tripartite growth cycle

north atlantic oscillation effect on interannual variability in winter precipitation over the gulf stream abstractin winter the warm water of the gulf stream anchors a salient precipitation band previous studies suggested a close relationship between the sea surface temperature sst front and the pr

a study of non linear tidal propagation in shallow inlet estuarine systems part i observations the offshore tide becomes strongly distorted as it propagates into shallow estuarine systems observations of sea surface elevation and horizontal currents over periods ranging from three days to one year at nine stations within nauset inlet estuary document the non linear interaction of the off shore equilibrium tidal constituents despite strong frictional attenuation within the estuary the overtides and compound tides of m2 s2 and n2 in particular reach significant amplitude resulting in strong tidal distortion high frequency forced constituents in sea surface are phase locked consistently leading the forcing tides by 60 70 resulting in a persistent distortion where falling tide is longer than rising tide forced constituents in currents are more nearly in phase with equilibrium constituents producing flood currents which are shorter but more intense than ebb currents a compound fortnightly tide msf modulates the mean water level such that lowest tides occur during neap phase instead of spring phase this fortnightly tide can be contaminated by storm surge changing the phase characteristics of this constituent implications of the overtides compound tides and lower frequency tides on near bed suspended and dissolved material transport are profound

analysis of current observations on the georgia shelf abstract an analysis is made of hf radar measurements of surface currents in shallow water near the georgia coast and also of vertical profile measurements of current and density the dominant structure is found to be a clockwise ellipse of semidiurnal periodicity the ellipses becoming smaller narrower and turning clockwise with depth there is a definite phase lead of the bottom currents with respect to the upper currents and some evidence of veering of the currents in the non ekman sense in order to explain the observed vertical variations a simple analytical expression is developed for periodic rotary currents in a barotropic ocean of constant eddy viscosity and depth h when the free surface elliptic motion is known the solution depends on the ratios f and h hekman and also on the sense of turning of the free surface ellipse the model is able to explain several features of the observed vertical variations as frictional effects

physical processes controlling the formation evolution and perturbation of the low salinity front in the inner shelf off the southeastern united states a modeling study physical processes that control the formation evolution and perturbation of the low salinity front over the inner shelf of the south atlantic bight have been examined using a fully three dimensional primitive equation and turbulent closure model the model was forced by semidiurnal tides m2 s2 and n2 climatological means of multiple river discharges and upwelling favorable wind this model has provided a reasonable simulation of the fortnightly and monthly variations of semidiurnal tides computed amplitudes and phases of tides show good agreement with observational data available at tidal gauge stations along the coast spatial structures of buoyancy currents are significantly modified by stratified tidal rectification as a result the southward residual current intensifies significantly at the front and reduces or reverses close to the coast a weak velocity area forms in the downstream region of each river which blocks the low salinity water to form multiple tongue like domes in the inner shelf for a given springtime climatological upwelling favorable wind isolated low salinity lenses can form episodically in two steps at first a geometrically controlling wave like frontal shape develops at the outer edge of the frontal zone as a result of the interaction between tides multiple river discharges and upwelling favorable wind then isolated low salinity lenses form at the crest when water on the shoreward side of the crest is displaced by relatively high salinity water advected from the upstream trough south of the crest and diffused upward from the deeper region wind induced upwelling is noticeable to compensate for the water loss due to the near surface offshore ekman transport but it does not play a critical role in the formation of isolated lenses under the climatological conditions of river discharges and upwelling favorable winds over the inner shelf of the south atlantic bight

lightning over the gulf stream during the period 15 january 15 march 1986 the average frequency and strength of lightning flashes to the earth s surface over the gulf stream off the carolina coast was greater than that over the adjacent land near the north carolina coast in prefrontal situations the mean number of flashes to the earth s surface per lightning day per grid area 1 latitude 1 longitude was 20 9 in the vicinity of the gulf stream and 4 8 over the adjacent land in postfrontal situations the corresponding numbers were 18 4 and 8 9 most but not all of the lightning flashes over the gulf stream conveyed negative charge to the earth s surface and the increase in the frequency of lightning over the gulf stream was greater for these lightning flashes than for those that carried positive charge to the earth s surface the enhancement in lightning activity over the gulf stream is attributed to the recurrent convective rainbands that form in this region