natural and anthropogenic schwertmannites from towada hachimantai national park honshu japan abstract schwertmannite a recently described iron hydroxysulfate mineral ideal formula fe 8 o 8 oh 6 so 4 forms naturally as a fluffy brownish yellow precipitate in lake matsuo goshikinuma iwate prefecture japan during part of the distinctive annual geochemical cycle of the lake the dominant inflow to the lake is anoxic ground water which drains disseminated pyritic deposits and enters through a vent in the lake floor the lake water typically has ph 3 and contains 125 mg l soluble s and 30 mg l soluble fe from approximately september to june each year the lake circulates completely dissolved oxygen levels are relatively high iron oxidizing bacteria thiobacillus ferrooxidans are abundant and the lake is turbid brown as schwertmannite is formed samples have been identified and characterized by x ray powder diffraction x ray fluorescence analysis and by extraction with oxalate and dithionite reagents freshly precipitated samples are predominantly schwertmannite samples that have remained in contact with the lake water for months or more show partial transformation to goethite though the transformation is incomplete in material 30 year in age schwertmannite was also found to be formed in the oxidation processes employed by two plants that treat drainage from disused pyrite mines in japan

pacific interdecadal variability in this century s sea surface temperatures analysis of this century s sea surface temperatures over the pacific ocean reveals an interdecadal oscillation with a period of 15 20 years our results show that the well known 1976 77 climate regime shift is not unique but represents one of several phase transitions associated with this interdecadal oscillation also found around 1924 25 1941 42 and 1957 58 the oscillation s striking north south symmetry across the equator implies strong interactions between tropics and extratropics a mode with a period of approximately 70 years and an apparently different spatial pattern is also identified tentatively but has to be evaluated further using longer time series

surface climate variations over the north atlantic ocean during winter 1900 1989 abstract the low frequency variability of the surface climate over the north atlantic during winter is described using 90 years of weather observations from the comprehensive ocean atmosphere data set results are based on empirical orthogonal function analysis of four components of the climate system sea surface temperature sst air temperature wind and sea level pressure an important mode of variability of the wintertime surface climate over the north atlantic during this century is characterized by a dipole pattern in ssts and surface air temperatures with anomalies of one sign cast of newfoundland and anomalies of the opposite polarity off the southeast coast of the united states wind fluctuations occur locally over the regions of large surface temperature anomalies with stronger than normal winds overlying cooler than normal ssts this mode exhibits variability on quasi decadal and biennial time scales the decadal fluctuations are irregular in length averaging 9 years before 1945 and 1

re os geochronology of the hitachi volcanogenic massive sulfide deposit the oldest ore deposit in japan the hitachi volcanogenic massive sulfide vms deposit in the hitachi belt is one of the largest cu zn sulfide deposits in japan however its primary formation age has not been precisely determined because regional and contact metamorphism have disturbed some radiometric isotope systems e g k ar ages on wall rocks further metamorphism has greatly reduced the fossil record which has limited the use of biostratigraphy to establish the ore deposit age we applied re os isotope dating to samples from two representative sulfide deposits of the greater hitachi vms deposit the fudotaki and fujimi deposits re os isotope data from the fudotaki deposit yields a model 3 age of 533 13 ma with an initial 187 os 188 os ratio of 0 35 0 20 in contrast re os isotope data from the fujimi sulfide ore did not exhibit a linear correlation suggesting that the re os isotope system there has been disturbed by regional metamorphism of higher grade than the fudotaki deposit as well as contact metamorphism during intrusion of cretaceous granitic rocks although the fudotaki sulfide ores have been metamorphosed to lower epidote amphibolite facies the well defined re os isochron allowed us to interpret the timing of primary sulfide deposition on the paleoseafloor some orebodies of the greater hitachi vms deposit have been estimated to be early carboniferous based on the scarce fossil records and considered to be distributed in the daioin formation but our results revealed that the fudotaki deposit were formed during the cambrian and occurs in the upper akazawa formation which strongly supports the idea that the cambrian beds are widely distributed in the hitachi belt and that a significant unconformity exists between the cambrian and early carboniferous above the fudotaki deposit the cambrian re os date classifies the hitachi vms deposit as the oldest dated ore deposit in japan and in turn provides an insight to understand the geologic framework and genesis of the proto japanese islands and the east asian region

retrograding wintertime low frequency disturbances over the north pacific ocean abstract retrograding westward moving features over the middle and high latitudes of the northern hemisphere during winter are examined in observations and data from a gcm simulation using complex principal component analysis the first eigenvector of the low frequency middle troposphere geopotential height over the north pacific has a zonal scale of 120 160 deg longitude and a dipole like meridional structure with maximum amplitude over the gulf of alaska and the bering sea these disturbances propagate westward and go through a life cycle of growth and decay over a period of about three weeks the temporal evolution of the energy and its conversions during the life cycle of the simulated pacific disturbances are composited using the time dependent coefficient of the principal component analysis as an index for their occurrence the composite energy cycle indicates that the kinetic and available potential energy of these disturbances grow and decay together both baroclinic and barotropic conversion

the behavior of trace elements during schwertmannite precipitation and subsequent transformation into goethite and jarosite schwertmannite is a ubiquitous mineral formed from acid rock drainage ard and plays a major role in controlling the water chemistry of many acid streams the formation of schwertmannite was investigated in the acid discharge of the monte romero abandoned mine iberian pyrite belt sw spain schwertmannite precipitated from supersaturated solutions mainly owing to the oxidation of fe ii to fe iii and transformed with time into goethite and jarosite in a few hours schwertmannite precipitation removed more than half of the arsenic load from solution whereas the concentration of divalent trace metals zn cu pb cd ni and co remained almost unchanged in the laboratory natural schwertmannite was kept in contact with its coexisting acid water in a flask with a solid liquid mass ratio of 1 5 for 353 days during this time the ph of the solution dropped from 3 07 to 1 74 and the concentrations of sulfate and fe increased during the first 164 days schwertmannite transformed into goethite plus h3o jarosite but subsequently goethite was the only mineral to form some of the trace elements such as al cu pb and as were depleted in solution during the first stage as schwertmannite transformed into goethite plus h3o jarosite on the contrary the transformation of schwertmannite to goethite with no jarosite during the second stage released al cu and as to the solution despite the variation in their concentrations in solution approximately 80 of the total al and cu inventories and more than 99 as and pb remained in the solid phase throughout the entire aging process

intraseasonal oscillations in the global atmosphere part ii southern hemisphere abstract in part ii of this two part article we complete the systematic examination of oscillatory modes in the global atmosphere by studying 12 years of 500 mb geopotential heights in the southern hemisphere as in part i for the tropics and northern hemisphere extratropics the data were band pass filtered to focus on intraseasonal is phenomena and spatial eofs were obtained the leading principal components were subjected to singular spectrum analysis ssa in order to identify nonlinear is oscillations with high statistical confidence in the southern hemisphere the dominant mode has a period of 23 days with spatial patterns carried by the second and third winter eof of the is band it has a zonal wavenumber four structure the 40 day mode is second and dominated by wavenumbers three and four while a 16 day mode is too weak to separate its spatial behavior from the previous two the is dynamics in the southern hemisphere is more complex and dominated by shorter wavenumbers than the northern

mountain torques and atmospheric oscillations theoretical work and general circulation model gcm experiments suggest that the midlatitude jet stream s interaction with large scale topography can drive intrasea sonal oscillations in large scale atmospheric circulation pat terns in support of this theory we present new observa tional evidence that mountain induced torques play a key role in 15 30 day oscillations of the northern hemisphere circulation s dominant patterns the affected patterns in clude the arctic oscillation ao and the pacific north american pna pattern positive torques both accelerate and anticipate the midlatitude westerly winds at these peri odicities moreover torque anomalies anticipate the onsets of weather regimes over the pacific as well as the break ups of hemispheric scale regimes

air sea interaction effects in the lower troposphere across the north wall of the gulf stream abstract significant atmospheric and oceanographic differences have often been observed in the regions lying on either side of the north wall of the gulf stream satellite visible range sensors have revealed changes in reflectivity across the gulf stream believed to be due to changes in sea state that are related to these atmospheric and oceanic differences in addition lines of low level cloud paralleling the edge of the gulf stream have been observed to persist in satellite imagery for several days at a time anomalous radar propagation also has been noted to occur in these same regions in an attempt to document the interrelation of these phenomena the lower atmosphere over the north wall of the gulf stream was studied on two separate occasions sea state photography and measurements of sea surface temperature air temperature dew point temperature and atmospheric pressure were made by an instrumented rp 3a aircraft flying at various altitudes from the gulf stream across the north wall and onto

modeling and analysis of ageostrophic circulation over the azores oceanic front during the semaphore experiment abstract in the conventional quasigeostrophic qg form of the equation developed by hoskins et al the unique forcing of vertical velocity is the geostrophic deformation as the qg or even the semigeostrophic sg hypotheses are not adapted to study the frontal dynamics in the atmospheric boundary layer this paper proposes a generalized expression of the hoskins et al form of the vertical velocity two thermal and three dynamical sources of the vertical velocity are identified these forcings allow for identification of each of the physical processes acting simultaneously on the ageostrophic circulation in the boundary layer this new form of the equation is used to explain wind increase in the atmospheric boundary layer over the warm waters of the sea surface temperature sst front observed during a fair anticyclonic day of the semaphore experiment 1993 and simulated with a nonhydrostatic mesoscale atmospheric model since the sst gradients are weak of the order of 1 5 c 100 km 1 the surfac

intraseasonal variability in a barotropic model with seasonal forcing abstract it has recently been suggested that oscillatory topographic instability could contribute to low frequency variability over the northern hemisphere midlatitudes a barotropic potential vorticity model with a hierarchy of forcing and topography configurations on the sphere is used to investigate the nature of low frequency oscillations induced by such instabilities steady state solutions of the model include multiple unstable equilibria that sustain oscillatory instabilities with periods of 10 15 days 35 50 days and 150 180 days for a realistic forcing pattern time dependent solutions exhibit chaotic behavior with episodic oscillations featuring both the intraseasonal 35 50 day and biweekly 10 15 day modes the former is dominated by standing spatial patterns the latter by traveling wave patterns the phases of the intraseasonal oscillation are robust for all cases exhibiting a clear oscillatory exchange of atmospheric angular momentum with the solid earth via mountain torque it is d

chemical and physical properties of iron hydroxide precipitates associated with passively treated coal mine drainage in the bituminous region of pennsylvania and maryland abstract changes in precipitate mineralogy morphology and major and trace element concentrations and associations throughout 5 coal mine drainage cmd remediation systems treating discharges of varying chemistries were investigated in order to determine the factors that influence the characteristics of precipitates formed in passive systems the 5 passive treatment systems sampled in this study are located in the bituminous coal fields of western pennsylvania and northern maryland and treat discharges from pennsylvanian age coals the precipitates are dominantly 70 goethite crystallinity varies throughout an individual system and lower crystallinity is associated with enhanced sorption of trace metals degree of crystallinity and subsequently morphology and trace metal associations is a function of the treatment system and how rapidly fe ii is oxidized forms precipitates aggregates and settles precipitates formed earlier in the passive treatment systems tend to have the highest crystallinity and the lowest concentrations of trace metal cations high surface area and cation vacancies within the goethite structure enable sorption and incorporation of metals from coal mine drainage polluted waters sorption affinities follow the order of zn co ni mn cobalt and ni are preferentially sorbed to mn oxide phases when these phases are present as ph increases in the individual cmd treatment systems toward the phpzc of goethite as sorption decreases and transition metal co mn ni and zn sorption increases sulfate na and fe ii concentrations may all influence the sorption of trace metals to the fe hydroxide surface results of this study have implications not only for solids disposal and resource recovery but also for the optimization of passive cmd treatment systems

brownish discoloration of the summit crater lake of mt shinmoe dake kirishima volcano japan volcanic microbial coupled origin a drastic change in lake water color from blue green to brown was observed in the summit crater lake of mt shinmoe dake kirishima volcano about 8 months after its 2008 eruption the color change lasted for about 2 months april june 2009 the discoloration was attributed to a brownish color suspension that had formed in the lake water x ray fluorescence and fourier transform infrared analyses of a sample of the suspension identified schwertmannite fe8o8 oh 6 so4 a cultivation test of iron oxidizing bacteria for the sampled lake water with lakebed sediment revealed that the crater lake hosts iron oxidizing bacteria which likely participated in schwertmannite formation we suggest that pyrite fes2 provided an energy source for the iron oxidizing bacteria since the mineral was identified in hydrothermally altered tephra ejected by the august 2008 eruption from consideration of these and other factors the brownish discoloration of the summit crater lake of mt shinmoe dake was inferred to have resulted from a combined volcanic microbial process

decadal variability of two oceans and an atmosphere a model of the midlatitude large scale interaction between the upper ocean and the troposphere is used to illustrate possible mechanisms of connection between the decadal variability in the north atlantic and in the north pacific the two ocean basins are connected to each other only through their coupling to the common zonally averaged atmosphere the ocean atmosphere coupling takes place via wind driven torques and heat fluxes at the air sea interface in this formulation the decadal variability in each ocean basin consists of ocean atmosphere modes and arises from a delayed feedback of the upper ocean heat content onto the wind driven flow mediated by the atmosphere through the requirements of global heat and momentum balances the presence of two ocean basins leads to three basic kinds of coupling induced behavior phase locking oscillation death and chaos in the phase locked regime the western boundary currents of the two basins oscillate in synchrony with the narrower basin following the wider basin by a small time lag in the oscillation death solutions a steady solution is reached even though each ocean basin when uncoupled would have sustained oscillations in the chaotic regime the interbasin coupling induces aperiodic fluctuations in both basins characterized by variability at centennial as well as decadal timescales

propagation of gulf stream meanders between 74 and 70 w abstract positions of the gulf stream path from 74 to 45 w were obtained from satellite infrared images for the period of april 1982 december 1989 the propagation of meanders between 74 and 70 w was studied through spectral analysis in wavenumber frequency space empirical orthogonal function analysis in time and frequency domains and direct measurements of individual meander properties progressive meanders are found to have a broad range of periods from days to years and wavelengths from about 200 to 1100 km good agreement is found between the satellite and inverted echo sounder data for short period 80 days progressive propagation retrogressive meanders with wavelengths longer than 1100 km are found to coexist with progressive ones at periods longer than 4 months the empirical dispersion relation is in qualitative agreement with the linear prediction of a recent equivalent barotropic plane thin jet model the comparison also suggests that topographic may need to be considered in order to

interdecadal variations in north atlantic sea surface temperature and associated atmospheric conditions abstract evidence is presented for a distinct pattern of ocean atmosphere relationship associated with interdecadal variability in the north atlantic region using a century of surface marine observations it is shown that middle and high latitude sea surface temperature sst display a long term fluctuation with negative anomalies before 1920 and during the 1970s and 1980s positive sst conditions prevailed from about 1930 to 1960 the pattern of interdecadal sst variability is constructed by subtracting the average field during 15 cold years from that during a similar interval of warm years the early century warming and the more recent cooling display a similar spatial pattern in both cases the pattern is basin scale and largely of one polarity with maxima in the vicinity of iceland in the labrador sea and northeast of bermuda the corresponding differences in surface atmospheric conditions are determined by averaging and subtracting in the same manner fields of sea level pressure slp and surf

low frequency variability in the midlatitude atmosphere induced by an oceanic thermal front abstract this study examines the flow induced in a highly idealized atmospheric model by an east west oriented oceanic thermal front the model has a linear marine boundary layer coupled to a quasigeostrophic equivalent barotropic free atmosphere the vertical velocity at the top of the boundary layer drives the flow in the free atmosphere and produces an eastward jet parallel to the oceanic front s isotherms a large gyre develops on either side of this jet cyclonic to the north and anticyclonic to the south of it as the jet intensifies during spinup from rest it becomes unstable the most unstable wave has a length of about 500 km it evolves into a meander and eddies detach from the eastern edge of each gyre the dependence of the atmospheric dynamics on the strength t of the oceanic front is studied the gulf stream and kuroshio fronts correspond roughly in the scaling used here to t 7 c for weak fronts t 4 c the circulation is steady and exhibits two large antisymmetric gyres sepa

nonhydrostatic simulations of coastal mesobeta scale vortices and frontogenesis abstract a nonhydrostatic version of the pennsylvania state university national center for atmospheric research mesoscale model with a horizontal resolution of 5 km is used with measurements taken during intensive observation period 2 of the genesis of atlantic lows experiment to study the offshore mesobeta scale coastal front structure results from the 24 h model simulation and doppler radar data indicate that precipitation bands with embedded convective elements are present along the coastal front in the vicinity of the gulf stream as the frontogenesis evolves the simulated surface frontal zone becomes fractured and discontinuous lines of confluence and mesoscale ascent become apparent a collapse of the cross frontal thermal gradient is driven by intense gradients of the surface fluxes in the vicinity of the gulf stream a mesoscale wave train consisting of a series of shallow weak vortices with horizontal scales between 50 and 100 km forms along the front in agreement with the doppler radar

barotropic wave propagation and instability and atmospheric teleconnection patterns abstract a global barotropic model linearized about the 300 mb climatological mean january flow is perturbed by applying a series of localized forcings distributed throughout the tropics and subtropics structures which resemble the observed pacific north american and east atlantic teleconnection patterns noted by wallace and gutzler 1981 tend to recur in the responses similar patterns are found to result from the dispersion of isolated initial perturbations placed at a variety of locations in the tropics and midlatitudes it is shown that these structures are related to the most rapidly growing mode associated with barotropic instability of the zonally varying climatological basic state in the absence of damping this mode has an e folding time of about a week and a period close to 50 days in localized regions the instantaneous growth rates can be competitive with those of baroclinic instability these episodes of rapid local barotropic growth are interspersed with intervals in which the local

mesoscale coastal processes during gale iop 2 abstract during intensive observation period 2 of the genesis of atlantic lows experiment a number of mesoscale phenomena were observed with special and conventional observing systems over the land and coastal waters this study involved analysis of these data for the period 24 26 january 1986 in order to define the structure and dynamics of three features the coastal front a shallow cyclone that propagated along the coastal front modifying it as it moved northward and a low level jet that formed in the strong coastal pressure gradient field the coastal front formed in an existing pressure trough over the gulf stream as a result of both ageostrophic deformation and differential diabatic heating there existed considerable variability in the frontal strength and position on both the mesoalpha and mesobeta scales the level of strongest frontogenesis was near the surface with frontolysis calculated above 950 mb the marine atmospheric boundary layer mabl over the gulf stream was conducive to cyclon

mountain torques and northern hemisphere low frequency variability part i hemispheric aspects the ncep ncar reanalysis dataset for 1958 97 is used to analyze intraseasonal variations in mountain torques and the large scale atmospheric circulation patterns associated with them spectral analysis of the atmospheric angular momentum aam budget shows that the dominant variations of mountain torque have periodicities near 30 days and shorter while the dominant aam variations occur in the 40 60 day band this difference is due to the 40 60 day aam variations being primarily related to equatorial processes while mountain torque variations are associated mostly with extratropical processes the northern hemisphere nh mountain torque has enhanced power and significant spectral peaks in the 20 30 day band the signal in this band accounts for 33 of the nh mountain torque variance once the seasonal cycle has been removed lag composites of the nh 700 hpa geopotential heights based on the 20 30 day mountain torque signal show the latter to be associated with coherent large scale patterns that resemble lowfrequency oscillations identified in this band by previous authors the composite patterns that are in phase quadrature with the 20 30 day nh mountain torque have a pronounced zonally symmetric component these patterns are associated with substantial aam variations arguably driven by the nh mountain torque in this band principal component pc analysis of the nh 700 hpa heights shows that in the 20 30 day band the mountain torque is also in phase quadrature with the two leading pcs the first corresponds to changes in the midlatitude jet intensity near the subtropics while the second corresponds to the arctic oscillation the relationships with aam of the latter essentially occurs through the mass term mountain torques are furthermore nearly in phase with dominant patterns of low frequency variability that exhibit substantial pressure gradients across the rockies and the tibetan plateau

spells of low frequency oscillations and weather regimes in the northern hemisphere abstract the low frequency variability in the midlatitudes is described through an analysis of the oscillatory phenomena in order to isolate nearly periodic components of the atmospheric flow the multichannel version of the singular spectrum analysis m ssa is developed and applied to an nmc 32 year long set of 700 hpa geopotential heights in the same way that principal component analysis identifies the spatial patterns dominating the variability m ssa identifies dynamically relevant space time patterns and provides an adaptive filtering technique three major low frequency oscillations lfos are found with periods of 70 days 40 45 days and 30 35 days the 70 day oscillation consists of fluctuations in both position and amplitude of the atlantic jet with a poleward propagating anomaly pattern the 40 45 day oscillation is specific to the pacific sector and has a pronounced pacific north american pna structure in its high amplitude phase the 30 35 day mode is confined over the atlantic region

pelagic boundary conditions affect the biological formation of iron rich particles iron snow and their microbial communities we studied the formation of iron rich particles at steeply opposing gradients of oxygen and fe ii within the redoxcline of an acidic lignite mine lake ph 2 9 particles formed had a diameter of up to 380 m showed high sedimentation velocity 2 m h 1 and were dominated by the iron mineral schwertmannite although the particles were highly colonized by microbial cells 1010 cells g dry weight 1 the organic carbon content was below 11 bathymetry and the inflow of less acidic fe ii rich groundwater into the northern basin of the lake results in two distinct mixing regimes in the same lake the anoxic monimolimnion of the northern basin had higher ph fe ii dissolved organic carbon and co2 values compared with the more central basin particles formed in the northern basin differed in color were smaller had higher organic carbon contents but were still dominated by schwertmannite microcosm incubations revealed the dominance of microbial fe ii oxidation comparison of bacterial clone libraries suggested that ph was a major driving force shaping the microbial communities responsible for the oxidation of fe ii in both basins acidophilic ferrovum spp and chlorobia related bacteria were present in the central basin whereas neutrophilic sideroxydans spp dominated the northern basin snow like particles had a high sinking velocity and acted as a carrier for organic carbon microorganisms trace metals and fe iii to the sediment because these particles are fundamentally different from organic rich snows from lakes rivers and oceans we propose a new term iron snow

a striking example of the atmosphere s leading traveling pattern abstract conventional and complex empirical orthogonal function eof techniques show that for at least four months during the fall and winter of 1979 80 a large amplitude large scale traveling flow anomaly existed in the troposphere and stratosphere this feature evolved in a cyclic manner exhibiting an average period of about 23 days its phase propagation was toward the west while its amplitude was concentrated in a broad envelope centered over canada the phenomenon was equivalent barotropic in the troposphere and increased in amplitude with altitude it represented about 25 of the variance of geopotential heights in the troposphere and stratosphere for the months of november through march the meridional and zonal structure of the zonal wavenumber one component of the traveling anomaly is similar to that of the theoretical 16 day wave however it is distinct from that theoretical mode in that its period is longer and in the troposphere zonal wave two makes a large contribution to its structur

iron and aluminum hydroxysulfates from acid sulfate waters acid sulfate waters are produced mostly by the oxidation of common sulfide minerals such as pyrite chalcopyrite pyrrhotite and marcasite in rocks soils sediments and industrial wastes this spontaneous process of mineral weathering plays a fundamental role in the supergene alteration of ore deposits the formation of acid sulfate soils and the mobilization and release of acidity and metals to surface and ground waters the purely natural process of acid rock drainage is often intensified by human activities related to mining mineral processing construction soil drainage and dredging geochemical reaction rates are accelerated because physical disturbance gives greater exposure of mineral surfaces to air and water and to microbes that catalyze the reaction process large quantities of reactive sulfides are also concentrated and exposed to air as a result of mining and mineral processing acid sulfate waters produce a number of fairly insoluble hydroxysulfate and oxyhydroxide minerals that precipitate during oxidation hydrolysis and neutralization the objective of this chapter is to describe the formation properties fate and environmental implications of the nano to microphase hydroxy sulfates of fe and al that are precipitated from acid sulfate waters these minerals are commonly of poor crystallinity and difficult to characterize much remains to be learned about their occurrence formation and properties mine drainage the best known examples of acid sulfate waters are those released from mines where coal and metallic sulfide ores have been exploited ash et al 1951 barton 1978 nordstrom 1982a rose and cravotta 1998 nordstrom and alpers 1999 there may be as many as 500 000 inactive or abandoned mine sites in the united states alone lyon et al 1993 although most of these pose no immediate water quality problem kleinmann 1989 estimated that about 19 300 km of streams and more than 72 000 ha of lakes and reservoirs have been

intraseasonal oscillations in the global atmosphere i northern hemisphere and tropics abstract we have examined systematically oscillatory modes in the northern hemisphere and in the tropics the 700 mb heights were used to analyze extratropical oscillations and the outgoing longwave radiation to study tropical oscillations in convection all datasets were band pass filtered to focus on the intraseasonal is band of 10 120 days leading spatial patterns of variability were obtained by applying eof analysis to these is data the leading principal components pcs were subjected to singular spectrum analysis ssa ssa is a statistical technique related to eof analysis but in the time domain rather than the spatial domain it helps identify nonlinear oscillations in short and noisy time series in the northern hemisphere there are two important modes of oscillation with periods near 48 and 23 days respectively the 48 day mode is the most important of the two it has both traveling and standing components and is dominated by a zonal wavenumber two the 23 day mode has the spatial stru

trends interdecadal and interannual oscillations in global sea surface temperatures this study aims at a global description of climatic phenomena that exhibit some regularity during the twentieth century multi channel singular spectrum analysis is used to extract long term trends and quasi regular oscillations of global sea surface temperature sst fields since 1901 regional analyses are also performed on the pacific northern and southern atlantic and indian ocean basins the strongest climatic signal is the irregular long term trend characterized by overall warming during 1910 1940 and since 1975 with cooling especially of the northern hemisphere between these two warming intervals substantial cooling prevailed in the north pacific between 1950 and 1980 and continues in the north atlantic today both cooling and warming are preceded by sst anomalies of the same sign in the subpolar north atlantic near decadal oscillations are present primarily over the north atlantic but also over the south atlantic and the indian ocean a 13 15 y oscillation exhibits a seesaw pattern between the gulf stream region and the north atlantic drift and affects also the tropical atlantic another 7 8 y oscillation involves the entire double gyre circulation of the north atlantic being mostly of one sign across the basin with a minor maximum of opposite sign in the subpolar gyre and the major maximum in the northwestern part of the subtropical gyre three distinct interannual signals are found with periods of about 60 65 45 and 24 30 months all three are strongest in the tropical eastern pacific the first two extend throughout the whole pacific and still exhibit some consistent albeit weak patterns in other ocean basins the latter is weaker overall and has no consistent signature outside the pacific the 60 month oscillation obtains primarily before the 1960s and the 45 month oscillation afterwards

comparison of foraminiferal cleaning procedures for mg ca paleothermometry on core material deposited under varying terrigenous input and bottom water conditions a down core comparison of two commonly applied foraminiferal cleaning procedures for mg ca paleothermometry has been conducted using well preserved globigerinoides ruber white 250 300 mm from core material deposited under varying terrigenous input and bottom water conditions this study demonstrates that in the majority of investigated core materials both cleaning methods yield fairly comparable results of mg ca ratios however fe and mn phases are effectively removed by the cleaning procedure containing a reductive step in a core interval indicating gradual transition of terrigenous deposition and pore water conditions the cleaning procedure without a reductive step results in anomalously higher mg ca ratios accompanied by high fe ca and mn ca ratios indicating the presence of high mg contaminants considering that the mg ca deviation of the comparison study is the cumulative sum of 1 the difference in cleaning efficiency of the applied methods 2 the cleaning method dependent partial dissolution of mg and 3 the heterogeneity of subsamples we suggest that selective mg loss from well preserved globigerinoides ruber shells caused by the reductive sample treatment is not substantial enough to significantly bias paleotemperature estimation thus for core material deposited under varying sources and amounts of terrigenous material and bottom water conditions favorable for formation of authigenic mineral phases the use of cleaning methods that do include a reductive step yields more effective cleaning results by successful removal of mineral phases that may contain high mg

the marine boundary layer in the vicinity of an ocean front abstract aircraft observations obtained during the frontal air sea interaction experiment fasinex are used to investigate the structure of the marine atmospheric boundary layer in the vicinity of an ocean front a quasi stationary sea surface temperature sst discontinuity of 2 c was maintained across the frontal zone throughout the duration of the experiment the primary response of the atmosphere to changes in the sst was observed in the surface related turbulence fluxes in the case of warm air flowing over cold water the boundary layer appears to develop an internal boundary layer ibl in response to the sudden change in the sea surface temperature the organized updrafts and downdrafts within this layer collapse with entrainment detrainment processes in these cells dominating the turbulence statistics the ibl grows in response to the wind shear in this layer although the surface shear stress is much smaller on the colder side of the front than on the warm the depth of the ibl and in the abse