importance of ekman transport and gyre circulation change on seasonal variation of surface dissolved iron in the western subarctic north pacific iron fe is an essential nutrient for marine phytoplankton and it constitutes an important element in the marine carbon cycle in the ocean this study examined the mechanisms controlling seasonal variation of dissolved fe dfe in the western subarctic north pacific wsnp using an ocean general circulation model coupled with a simple biogeochemical model incorporating a dfe cycle fed by two major sources atmospheric dust and continental shelf sediment the model reproduced the seasonal cycle of observed concentrations of dfe and macro nutrients at the surface in the oyashio region with maxima in winter february march and minima in summer july september although the simulated seasonal amplitudes are a half of the observed values analysis of the mixed layer dfe budget indicated that both local vertical entrainment and lateral advection are primary contributors to the wintertime increase in dfe concentration in early winter strengthened northwesterly winds excite southward ekman transport and ekman upwelling over the western subarctic gyre transporting dfe rich water southward in mid to late winter the southward western boundary current of the subarctic gyre and the outflow from the sea of okhotsk also bring dfe rich water to the oyashio region the contribution of atmospheric dust to the dfe budget is several times smaller than these ocean transport processes in winter these results suggest that the westerly wind induced ekman transport and gyre circulation systematically influence the seasonal cycle of wsnp surface dfe concentration

mechanisms controlling dissolved iron distribution in the north pacific a model study mechanisms controlling the dissolved iron distribution in the north pacific are investigated using the biogeochemical elemental cycling bec model with a resolution of approximately 1 in latitude and longitude and 60 vertical levels the model is able to reproduce the general distribution of iron as revealed in available field data surface concentrations are generally below 0 2 nm concentrations increase with depth and values in the lower pycnocline are especially high in the northwestern pacific and off the coast of california sensitivity experiments changing scavenging regimes and external iron sources indicate that lateral transport of sedimentary iron from continental margins into the open ocean causes the high concentrations in these regions this offshore penetration only appears under a scavenging regime where iron has a relatively long residence time at high concentrations namely the order of years sedimentary iron is intensively supplied around continental margins resulting in locally high concentrations the residence time with respect to scavenging determines the horizontal scale of elevated iron concentrations budget analysis for iron reveals the processes by which sedimentary iron is transported to the open ocean horizontal mixing transports sedimentary iron from the boundary into alongshore currents which then carry high iron concentrations into the open ocean in regions where the alongshore currents separate from the coast most prominently in the northwestern pacific and off of california

simulations of chlorofluorocarbons in and around the sea of okhotsk effects of tidal mixing and brine rejection on the ventilation 1 ventilation of waters in and around the sea of okhotsk was investigated using simulations of chlorofluorocarbons cfcs in the northwestern north pacific we used an ocean general circulation model coupled with a sea ice model the model reproduces the distributions of cfcs similar to observed values and indicates the importance of tidal mixing along the kuril islands and brine rejection to ventilation of waters in and around the sea of okhotsk to clarify the role of each process numerical experiments excluding one of the two processes were carried out results show that brine rejection transports cfcs into the intermediate layer as deep as 200 400 m along the path of dense shelf water in the western sea of okhotsk but hardly to other areas and layers on the other hand tidal mixing transports cfcs into the intermediate and deeper layers throughout the sea of okhotsk we conclude that the tidal mixing has a greater influence than brine rejection on the ventilation of layers below the winter mixed layer

a modeling assessment of the interplay between aeolian iron fluxes and iron binding ligands in controlling carbon dioxide fluctuations during antarctic warm events 1 we add a prognostic biogeochemical model to the bern3d ocean circulation model to test the impact of increased aeolian iron fluxes in various regions of the ocean on long time scales atmospheric co2 is most sensitive when modern dust flux is increased 100 fold in the southern ocean for 1000 years resulting in a reduction of 10 ppmv seeding the indian ocean and south pacific results in increased export production and co2 drawdown in the southern ocean due to interbasinal transport of iron the non sea salt calcium record from dome c antarctica is used to scale aeolian iron deposition in the southern ocean in transient simulations over four antarctic warm events of the last glacial period our results suggest changes in dust flux to the southern ocean played a limited role in modulating co2 variations the impact of iron fluxes on co2 is dependent on parameter values chosen for the iron binding ligand

hydrothermal contribution to the oceanic dissolved iron inventory mineral dust and marine sediment resuspension are generally considered the primary sources of the nutrient iron to the oceans numerical model results suggest that iron released by hydrothermal activity is also an important source of dissolved iron particularly in the southern ocean iron limits phytoplankton growth and hence the biological carbon pump in the southern ocean1 models assessing the impacts of iron on the global carbon cycle generally rely on dust input and sediment resuspension as the predominant sources2 3 although it was previously thought that most iron from deep ocean hydrothermal activity was inaccessible to phytoplankton because of the formation of particulates4 it has been suggested that iron from hydrothermal activity5 6 7 may be an important source of oceanic dissolved iron8 9 10 11 12 13 here we use a global ocean model to assess the impacts of an annual dissolved iron flux of approximately 9 108 mol as estimated from regional observations of hydrothermal activity11 12 on the dissolved iron inventory of the world s oceans we find the response to the input of hydrothermal dissolved iron is greatest in the southern hemisphere oceans in particular observations of the distribution of dissolved iron in the southern ocean3 chever et al manuscript in preparation bowie et al manuscript in preparation can be replicated in our simulations only when our estimated iron flux from hydrothermal sources is included as the hydrothermal flux of iron is relatively constant over millennial timescales14 we propose that hydrothermal activity can buffer the oceanic dissolved iron inventory against shorter term fluctuations in dust deposition

hydrographic structure and transport of the oyashio south of hokkaido and the formation of north pacific intermediate water hydrographic structure and transport of the oyashio south of hokkaido were described with conductivity temperature depth and lowered acoustic doppler current profiler ladcp survey performed in june 1998 the southwestward oyashio transport just off the hokkaido coast was 10 1 sv in the density of 26 6 27 5 in which 2 5 sv was from the okhotsk sea and 7 6 sv was from the western subarctic gyre wsag the oyashio northeastward countercurrent was 4 9 sv the cross gyre oyashio transport in the area from the east coast of hokkaido to the subarctic front was estimated to be 5 2 sv 2 4 sv in 26 6 27 0 was mainly composed of low potential vorticity okhotsk sea water and 2 8 sv in 27 0 27 5 mostly from wsag suggesting that the okhotsk sea water wsag water would contribute to the formation of the upper lower part of the north pacific intermediate water npiw the oyashio water was lower in oxygen than in the subtropical areas south of the subarctic front in the density of 26 9 27 6 possibly because of the absence of the antarctic intermediate water aaiw influence with the relatively high oxygen water that might be transported along the western boundary of the north pacific ocean and along the kuroshio extension increasing the oxygen in the areas south of the subarctic front just south of the subarctic front a cold and fresh core anticyclonic eddy was observed with a salinity minimum in the core suggesting one possible formation process of npiw the density of the potential vorticity minimum in the southwestward oyashio near hokkaido was at around 26 65 which was lower than 26 8 26 9 observed in the early 1990s this is possibly because the potential vorticity vertical profiles in the okhotsk sea and wsag significantly changed corresponding to the water mass regime shift occurred in the subarctic pacific in the mid 1990s kawasaki 1999

effects of temporal variation in tide induced vertical mixing in the kuril straits on the thermohaline circulation originating in the okhotsk sea abstract tidally induced vertical mixing is important for thermohaline circulation previous estimations of tidal mixing have aimed to obtain time averaged values and ocean general circulation models ogcms typically parameterize such mixing using a temporally constant strength however tidal mixing is known to vary temporally during tidal or spring neap cycles here we investigate the effects of temporal change in tidally induced vertical diffusivity t in the kuril straits using an ogcm the results demonstrate that variations of vertical mixing on diurnal 2 week and 1 2 year timescales induce significant differences in the net effect of mixing and therefore in the thermohaline circulation originating in the okhotsk sea for diurnal and 2 week variations the strength of the tidal mixing effect depends on 1 the period and length of the duration over which t is larger than the temporal average and 2 the amplitude of the temporal variation of t even if the time averaged values are the same this is explained by the relative importance of two states in a quasi equilibrium state a larger t results in weaker stratification and vice versa and thus the net tidal mixing effect is weaker when t is variable than when it remains constant conversely in an adjustment stage just after an increase in t a larger t acts on stronger stratification and vice versa resulting in a stronger mixing effect for a 1 2 year variation the strength of the tidal mixing effect also depends on the phase relationship with seasonal variation in stratification these results imply the necessity of considering temporal change when estimating tidal mixing from observations specifying it in ogcms and understanding its effects

size fractionated iron distributions and iron limitation processes in the subarctic nw pacific 1 comparison of vertical profiles of size fractionated iron between the western and eastern subarctic north pacific clearly showed higher labile particulate iron concentrations towards the west and this result strongly supports the higher iron supply in the western region additionally the results of the seeds experiment the first meso scale iron enrichment experiment in the subarctic north pacific clearly showed that artificially enriched iron in the dissolved fraction mainly in colloidal fraction was rapidly transformed to suspended labile particulate iron during phytoplankton growth and was retained in the surface mixed layer probably this same rapid transformation process occurs naturally after sporadic atmospheric iron supply and the labile particulate iron is retained in the western region furthermore this transformation process reduces dissolved concentration of iron and its bioavailability therefore the transformation process is important for understanding how phytoplankton became iron limited and the biogeochemical iron cycle in the western subarctic north pacific

modeling the geochemical cycle of iron in the oceans and its impact on atmospheric co2 concentrations iron occurs at very low concentrations in seawater and seems to be a limiting factor for primary production in the equatorial pacific and the southern ocean the global distribution of iron is still not well understood because of a lack of data and the complex chemistry of iron we develop a 10 box model to study the oceanic distribution of iron and its effect on atmospheric co2 concentration subject to our assumptions we find that a lack of interocean fractionation of deep sea iron concentrations as suggested by johnson et al 1997a is not readily explained by a balance of eolian deposition scavenging and regeneration incorporation of organic complexation in the model as suggested by johnson et al to reduce the scavenging rate of iron when concentrations fall below some ligand stabilized concentration is one solution to this difficulty alternatively the deep sea concentration may be more variable than the current rather sparse data coverage suggests in the model deep sea iron concentrations are responsive to the atmospheric source even if we adopt stabilization of concentrations by a ligand as modeled by johnson et al l997a in the southern ocean where the model suggests iron supply has an important limiting effect on the biota more than 99 of the iron supply to the surface in the present day comes from upwelling and not from the local atmospheric flux in the context of glacial interglacial changes to atmospheric co2 the model suggests that increasing atmospheric iron to the entire global ocean by a factor of 2 leads to decreases in atmospheric co2 of 10 30 ppm depending on assumptions however in our model co2 concentrations are almost unaffected by changes in southern ocean atmospheric fluxes alone unless these are unrealistically large 100 times present day the effect on atmospheric carbon dioxide is slightly stronger if accompanied by increased stratification of the southern ocean the model suggests that eolian iron fertilization of the ocean could have importantly influenced glacial atmospheric co2 concentrations but that other processes must also be at work to account for the full magnitude of the glacial interglacial change

atmospheric transport of iron and its deposition in the ocean the atmospheric transport of continental weathering products is responsible for much of the mineral material and fe entering the open ocean and is probably the dominant source of nutrient fe in the photic zone in regions where other nutrients are present in high concentrations the flux of fe from the atmosphere may be a limiting factor in primary productivity due to the larger source regions for dust north of the equator 8 times more atmospheric fe is deposited in the northern hemisphere than in the southern hemisphere the mineral aerosol and fe transport and deposition are highly variable due to the episodic nature of dust generation and its transport and deposition processes between 10 and 50 of the total atmospheric fe entering the world ocean appears to dissolve i e it will pass through a 0 4 m pore size filter rapidly when the mineral matter enters the ocean much of the atmospheric fe is present as fe ii apparently produced as a result of photochemical reduction reactions taking place during atmospheric transport this readily soluble fe ii should be available immediately for use as a nutrient by phytoplankton atmospheric transport from the continents is estimated to supply 3 times as much dissolved fe to the oceans as that delivered via rivers

evidence of an extensive spread of hydrothermal dissolved iron in the indian ocean abstract ocean scale transect observations covering the entire water depth enable a comprehensive picture of the chemistry including the circulation and biogeochemical cycling of elements in seawater the large scale investigation of dissolved iron fe took place through the japanese geotraces study and here we report a basin scale full depth section profile of dissolved fe in the indian ocean from the arabian sea to the southern ocean the data clearly shows the hydrothermal fe distributed over 3000 km distance in the deep layer centered at a depth of approximately 3000 m around the central indian ridge segment and a large part of the dissolved fe from the hydrothermal sources was in the real soluble fraction rather than the colloidal fraction in the intermediate water in the north arabian sea another dissolved fe rich water mass existed where fe was enriched by remineralization processes from settling particles and or adjacent reducing sediments and preserved in the suboxic water the basin scale section profile indicates that there are several sources supplying dissolved fe to deep waters such as the hydrothermal sources and terrestrial fe input with a persistent condition in the oxygen minimum zone omz between the northern subtropical section though few fe sources were apparent in the southern ocean combining our size fractionated fe data with numerical modeling study suggests that the fe physical chemical form in seawater differs between the sources and is a key factor for controlling residence time and explaining the large scale distributed hydrothermal fe

c band repeat pass interferometric sar observations of the forest properties of ers 1 c band repeat pass interferometric sar information for a forested area are studied the intensity information is rather limited but including coherence and effective interferometric sar insar height more information about the forest parameters can be obtained via satellite such information is also important for correction of insar derived topographic maps coherence properties have been used to identify forested nonforested areas and the interferometric effective height of the forest determined by comparison to a dem of the area the authors have developed a model to relate basic forest properties to insar observations these show that the coherence and interferometric effective height of a forested area change between image pairs the model demonstrates how these properties are related to the temporal decorrelation and the scattering from the vegetation canopy and the ground surface gaps in the vegetation are found to be important in the characterization of boreal forests

comparing the vertical distribution of iron in the eastern and western north pacific ocean 1 labile dissolved fe 0 22 m in the western 165 e and eastern 165 w north pacific ocean had nutrient and apparent oxygen utilization aou like profiles characterized by surface depletion and deep enrichment 5 3000 m depth dissolved fe concentrations in the deep water column at the mid latitudes were approximately one half lower in the eastern region 0 5 0 8 nm than in the western region 0 8 1 3 nm although the dissolved fe concentrations in the surface mixed layer in both regions were extremely depleted to 0 1 0 2 nm surprisingly the labile particulate fe concentrations 0 1 nm total dissolvable fe minus labile dissolved fe throughout the water column at low latitudes in the eastern region were extremely lower than those 0 5 1 nm in the western region it is suggested that the low fe levels in the eastern mid latitude oceanic region are primarily due to the lower atmospheric fe supply in the eastern region

simulation of high concentration of iron in dense shelf water in the okhotsk sea abstract an ocean general circulation model coupled with a simple biogeochemical model was developed to simulate iron circulation in and around the sea of okhotsk the model has two external sources of iron dust iron at the sea surface and sedimentary iron at the seabed shallower than 300 m the model represented characteristic features reasonably well such as high iron concentration in the dense shelf water dsw and its mixing which extends southward in the intermediate layer from the northwestern shelf along sakhalin island and finally flows into the pacific sensitivity experiments for the solubility of dust iron in seawater suggest that a solubility of 1 is appropriate in our simulation higher solubilities 5 and 10 result in too low phosphate in the northwestern north pacific in summer as well as too high iron concentrations at the sea surface compared with observations besides these experiments show that dust iron hardly contributes to the high iron concentration in the intermediate layer to investigate locations from which the iron in the intermediate layer originates the fate of sedimentary iron input from four regions in the okhotsk sea was examined results suggest that the western and central parts of the northern shelf are important

deglacial variability in okhotsk sea intermediate water ventilation and biogeochemistry implications for north pacific nutrient supply and productivity highlights multi proxy multi site reconstruction of okhotsk sea palaeo productivity and mid depth ventilation changes from 8 to 18 ka link between hinterland river discharge and downstream okhotsk sea intermediate water osiw ventilation nutrient signatures surplus fe si oh 4 export in osiw during bolling allerod to pelagic pacific supported transient nutrient replete conditions subarctic and subtropical pacific gyres disconnected during bolling allerod with restricted osiw flow to lower latitudes deglacial osiw export and mid depth pacific biogeochemistry modulate millennial scale regional co2 source sink conditions the modern north pacific plays a critical role in marine biogeochemical cycles as an oceanic sink of co2 and by bearing some of the most productive and least oxygenated waters of the world ocean the capacity to sequester co2 is limited by efficient nutrient supply to the mixed layer particularly from deeper water masses in the pacific s subarctic and marginal seas the region is in addition only weakly ventilated by north pacific intermediate water npiw which receives its characteristics from okhotsk sea intermediate water osiw here we present reconstructions of intermediate water ventilation and productivity variations in the okhotsk sea that cover the last glacial termination between eight and 18 ka based on a set of high resolution sediment cores from sites directly downstream of osiw formation in a multi proxy approach we use total organic carbon toc chlorin biogenic opal and caco3 concentrations as indicators for biological productivity c n ratios and xrf scanning derived elemental ratios si k and fe k as well as chlorophycean algae counts document changes in amur freshwater and sediment discharge that condition the osiw stable carbon isotopes of epi and shallow endobenthic foraminifera in combination with 14c analyses of benthic and planktic foraminifera imply decreases in osiw oxygenation during deglacial warm phases from c 14 7 to 13 ka bolling allerod and c 11 4 to 9 ka preboreal no concomitant decreases in okhotsk sea benthic planktic ventilation ages are observed in contrast to nearby but southerly locations on the japan continental margin we attribute okhotsk sea mid depth oxygenation decreases in times of enhanced organic matter supply to maxima in remineralization within osiw in line with multi proxy evidence for maxima in primary productivity and supply of organic matter sedimentary c n and fe k ratios indicate more effective entrainment of nutrients into osiw and thus an increased nutrient load of osiw during deglacial warm periods correlation of palynological and sedimentological evidence from our sites with hinterland reference records suggests that millennial scale changes in osiw oxygen and nutrient concentrations were largely influenced by fluvial freshwater runoff maxima from the amur caused by a deglacial northeastward propagation of the east asian summer monsoon that increased precipitation and temperatures in conjunction with melting of permafrost in the amur catchment area we suggest that osiw ventilation minima and the high lateral supply of nutrients and organic matter during the allerod and preboreal are mechanistically linked to concurrent maxima in nutrient utilization and biological productivity in the subpolar northwest pacific in this scenario increased export of nutrients from the okhotsk sea during deglacial warm phases supported subarctic pacific shifts from generally fe limiting conditions to transient nutrient replete regimes through enhanced advection of mid depth nutrient and fe rich osiw into the upper ocean this mechanism may have moderated the role of the subarctic pacific in the deglacial co2 rise on millennial timescales by combining the upwelling of old carbon rich waters with a transient delivery of mid depth derived bio available fe and silicate

tidally induced diapycnal mixing in the kuril straits and its role in water transformation and transport a three dimensional nonhydrostatic model experiment 1 baroclinic processes generated by the k1 tidal flow around the kuril straits and their role in the linkage between the okhotsk sea and the north pacific are investigated using a three dimensional nonhydrostatic model large amplitude unsteady lee waves are generated around sill tops all along the kuril island chain and induce significant density inversions from the sea surface down to the 27 6 density layer along with this wave breaking a large flow of energy takes place from the swift tidal flow regions to greater depths as a result of the clockwise propagation of both the topographically trapped waves around the islands and the remaining unsteady lee waves such wave generation and energy exchange eventually cause intense diapycnal mixing over the shallow topographic features and near the bottom leading to a maximum diapycnal diffusivity of over 103 cm2 s 1 even in the deep bussol strait which is thought to be the main exit of the okhotsk sea water considerable mixing corresponding to diapycnal diffusivity values of between 10 50 cm2 s 1 occurs vigorous mixing in the shallow regions produces low potential vorticity pv water in the upper layer and high pv water below accordingly pv fronts are formed along the island chain and sustain instabilities that in turn release baroclinic eddies with low core pv values these features are indicated in recent satellite imagery and in situ observations suggesting that the tide is the controlling factor in the formation of fronts observed in the kuril straits tidally induced mean transport across the straits is estimated to reach 26 sv 1 sv 106 m3 s 1 which is much larger than in the barotropic case however most of the exchanged water tends to circulate around the islands due to the effect of bottom topography whereas eddies pinched off from the tidal fronts carry the exchanged water offshore the amount of eddy driven offshore transport away from the islands reaches 14 sv with roughly half being directed to the north pacific this significant offshore transport spreads the effect of the diapycnal mixing taking place in the straits over wider areas of the north pacific and the okhotsk sea for example the pv values generated in the eddies differ by 30 40 from the ambient water on average whereas sea surface salinity within the eddies is 0 1 psu higher than the surroundings corresponding to the density increase of 0 08 thus the eddy transport provides significant pv and salinity fluxes to both the north pacific and the okhotsk sea hence we infer that a combination of tidally driven processes taking place at the passages leads to the formation of eddies that play a central role in water transport and transformation and are an essential aspect of the physical interplay between the okhotsk sea and the north pacific

a model of the iron cycle in the ocean the ironex ii in situ fertilization experiment showed decisively that availability of iron limits the growth of phytoplankton in equatorial pacific surface waters high nutrient low chlorophyll hnlc surface waters potentially iron limited are also found in the north pacific and the southern ocean a model of seawater iron geochemistry has been incorporated into a global ocean circulation and carbon cycle model and tuned to match the observed ocean fe distribution the model reproduces the observed hnlc areas in the equatorial pacific and southern ocean but predicts nutrient depletion in the north pacific a region of high dust fluxes from asia the model is based on the idea that the concentrations of organic iron binding ligands in seawater control the subsurface fe concentration and predicts that a majority 70 80 of the global carbon export production can be sustained by upwelling of dissolved iron in seawater rather than by atmospheric deposition the ocean iron cycle increases the efficiency of iron utilization in the biological pump buffers new production against interannual fluctuations in iron deposition and contributes several new intrinsic timescales to the ocean carbon cycle several hundred years for the ocean iron concentration and perhaps several thousand for the concentration of ligand in the deep sea ocean recycling of fe appears to play a major role in determining the strength of the biological pump in the ocean and the pco2 of the atmosphere

spatial variation of biogenic and crustal elements in suspended particulate matter from surface waters of the north pacific and its marginal seas abstract the physical and chemical properties of oceanic suspended particulate matter spm reflect the characteristics of the water mass including marine biological activity and riverine and or atmospheric inputs and provide a clue to understanding the ocean biogeochemical processes detailed data mapping of particle number concentration particle volume concentration and elemental composition si ca ti and fe were obtained from surface waters of the north pacific and its marginal seas the sea of okhotsk the bering sea and the chukchi sea during summer and autumn based on bulk and single particle analyses of the spm in the bering sea and chukchi sea the mean concentration of particle number and volume were 35 106 particles l 1 and 960 ppbv respectively and more than 10 times higher than those in the north pacific 2 1 106 particles l 1 and 39 ppbv the mean concentrations of both biogenic si and ca and crustal ti and fe elements in the spm from the bering sea and chukchi sea were also approximately 10 times higher than those from the north pacific and the sea of okhotsk the high concentrations of crustal elements in the continental shelf region of the bering sea appear to be sustained by riverine input from the yukon river nutrients transported together with crustal material from the river could contribute to high primary productivity of the bering sea and result in the high concentrations of biogenic spm the fe to ti ratios in spm varied among the ocean regions the ratios in the bering sea and the chukchi sea were 5 times higher than those in the north pacific individual particle analysis also revealed the spatial difference in size and chemical compositions of aluminosilicate type particles these evidences indicate that the difference in origins and or oceanic processes of crustal particles among the ocean regions affects the spatial variation of elemental ratio in crustal spm

dissolved iron distribution in the western and central subarctic pacific hnlc water formation and biogeochemical processes it is well known that phytoplankton growth is broadly limited by iron fe availability in the subarctic pacific to investigate which fe sources control the amplitude of seasonal variation in biogeochemical parameters in the subarctic pacific we examined the spatial variation in the west to east distribution of dissolved fe dfe across the western and central subarctic pacific through the japanese geotraces program the vertical section profile of the western subarctic pacific gyre showed high dissolved fe concentrations from the bottom of the surface mixed layer to as deep as approximately 3000 m suggesting that fe rich intermediate water is transported laterally and distributed across the western subarctic gyre over 2000 km the section data also indicate that the influence of the western fe rich intermediate water does not reach the alaskan gyre fe index dfe observed po4 observed rfe p distribution clearly indicates that the western fe rich intermediate water is well explained by external sedimentary fe sources and water transport systems from a subpolar marginal sea the sea of okhotsk and the continental margin the spatial pattern of fe to nutrient stoichiometry supplied from the intermediate water to the surface in comparison with reported fe and nutrient demand in surface phytoplankton quantitatively explains the differences in surface macronutrient consumption between the western and eastern gyre as well as the formation of the high nutrient and low chlorophyll region in the whole subarctic pacific

radar interferogram filtering for geophysical applications the use of sar interferometry is often impeded by decorrelation from thermal noise temporal change and baseline geometry power spectra of interferograms are typically the sum of a narrow band component combined with broad band noise we describe a new adaptive filtering algorithm that dramatically lowers phase noise improving both measurement accuracy and phase unwrapping while demonstrating graceful degradation in regions of pure noise the performance of the filter is demonstrated with sar data from the ers satellites over the jakobshavns glacier of greenland

critique of elastic thickness of the venus lithosphere estimated from topography and gravity by a cazenave and k dominh cazenave and dominh compare the topography in a portion of the rolling plains province of venus with a measure of the corresponding gravity perturbations the residual acceleration of the pioneer venus orbiter they ignore substantial geometric factors and make unsubstantiated geophysical assumptions to draw conclusions which we consider logically invalid and numerically implausible

the role of dust deposition in determining surface water distributions of al and fe in the south west atlantic abstract underway dissolved al and fe determinations were made on surface water samples collected between 34 s and 8 n in the southern and tropical atlantic ocean using a towed surface water sampler the general distribution of dissolved al which ranged from 8 nm in the sub tropical gyre to 61 nm under the intertropical convergence zone itcz north of the equator corresponds clearly with atmospheric dust deposition patterns a striking correlation between al and surface water salinities between 28 s and 8 n further indicates that wet deposition is the predominant mechanism of delivery of this atmospheric source iron concentrations in contrast were more uniform varying between 0 6 and 0 8 nm south of the equator highest fe values up to 1 4 nm also were found associated with the maximum dust inputs at the itcz indicating an atmospheric source for this element whose input appears to be limited by the solubility of fe in sea water the lowest fe values 0 4 nm also were observed in the equatorial region and are assumed to result from the biological removal of fe from nutrient rich water masses originating in the nearby equatorial and coastal upwelling regions the high frequency data acquisition of the towed sampler revealed significant variations up to 50 in both al and fe concentrations over short distances most notably along the interface between the south equatorial and canary currents the high variability of a biologically important trace element such as fe in these dynamic regions is indicative of the interplay between chemical and biological patchiness in surface waters

marine methane cycle simulations for the period of early global warming geochemical environments fates and effects are modeled for methane released into seawater by the decomposition of climate sensitive clathrates a contemporary global background cycle is first constructed within the framework of the parallel ocean program input from organics in the upper thermocline is related to oxygen levels and microbial consumption is parameterized from available rate measurements seepage into bottom layers is then superimposed representing typical seabed fluid flow the resulting ch sub 4 distribution is validated against surface saturation ratios vertical sections and slope plume studies injections of clathrate derived methane are explored by distributing a small number of point sources around the arctic continental shelf where stocks are extensive and susceptible to instability during the first few decades of global warming isolated bottom cells are assigned dissolved gas fluxes from porous media simulation given the present bulk removal pattern methane does not penetrate far from emission sites accumulated effects however spread to the regional scale following the modeled current system both hypoxification and acidification are documented sensitivity studies illustrate a potential for material restrictions to broaden the perturbations since methanotrophic consumers require nutrients and trace metals when such factors are considered methane buildup within the arctic basin is enhanced however freshened polar surface waters act as a barrier to atmospheric transfer diverting products into the deep return flow uncertainties in the logic and calculations are enumerated including those inherent in high latitude clathrate abundance buoyant effluent rise through the column representation of the general circulation and bacterial growth kinetics

temporal stability of x band single pass insar heights in a spruce forest effects of acquisition properties and season solberg svein weydahl dan johan astrup rasmus andreas temporal stability of x band single pass insar heights in a spruce forest effects of acquisition properties and season ieee transactions on geoscience and remote sensing 2014 volum 53 3 s 1607 1614

a separating coastal upwelling jet at cape blanco oregon and its connection to the california current system the coastal upwelling region near cape blanco oregon 433n o the west coast of the united states was studied using a towed ctd on seasoar a shipboard acoustic doppler current pro ler adcp satellite sea surface temperature maps and surface drifters during august 1995 the equatorward upwelling jet was inshore of the shelfbreak north of cape blanco meandered gently o shore around the cape and then veered sharply o shore just to the south of the cape analysis of vertical sections of density velocity and spicinessa con rmed the separation of an upwelling jet and front the jet was followed from over the shelfbreak north of the cape to 100 km o shore downstream of the cape the separating jet originates from the coastal upwelling jet leaving the shelf but is augmented by an o shore branching of the poleward undercurrent by combining information from adcp streamfunction maps with analysis of hydrographic data including distributions of the tracer like quantity spicinessa a conceptual model of the three dimensional circulation near the cape emerges a mid shelf upwelling jet encounters a coastal promontory then turns o shore stretching and deepening as it crosses the continental margin the jet then turns back shoreward cyclonically where the deepened equatorward ow encounters the top of the poleward undercurrent owing along the continental slope this causes a portion of the undercurrent to turn o shore to join and strengthen the equatorward transport in the separated jet throughout the separation process the coastal upwelling front and jet are continuous robust features separation of a coastal upwelling jet is an important mechanism for cross shelf transport from the coast to the deep ocean cape blanco appears to be the northernmost point where an equatorward jet regularly separates from the coast to become an oceanic jet and thus serves as the northern boundary of the region where an intense meandering current characteristic of the california current system