the tilt of mean sea level along the east coast of north america the tilt of mean sea level along the north american east coast has been a subject of debate for many decades improvements in geoid and ocean circulation models and gps positioning of tide gauge benchmarks provide an opportunity to produce new tilt estimates tilts estimated using tide gauge measurements referenced to high resolution geoid models the geodetic approach and ocean circulation models the ocean approach are compared the geodetic estimates are broadly similar with tilts downward to the north through the florida straits and at cape hatteras estimates from the ocean approach show good agreement with the geodetic estimates indicating a convergence of the two approaches and resolving the long standing debate as to the sign of the tilt these tilts differ from those used by yin and goddard 2013 to support a link between changing ocean circulation and coastal sea level rise

local diagnostics to estimate density induced sea level variations over topography and along coastlines 1 in the open ocean sea level variability is primarily steric in origin steric sea level is given by the depth integral of the density field raising the question of how tide gauges which are situated in very shallow water feel deep ocean variability here this question is examined in a high resolution global ocean model by considering a series of assumptions we show that if we wish to reconstruct coastal sea level using only local density information then the best assumption we can make is one of no horizontal pressure gradient and therefore no geostrophic flow at the seafloor coastal sea level can then be determined using density at the ocean s floor when attempting to discriminate between mass and volume components of sea level measured by tide gauges the conventional approach is to take steric height at deep ocean sites close to the tide gauges as an estimate of the steric component we find that with steric height computed at 3000 m this approach only works well in the equatorial band of the atlantic and pacific eastern boundaries in most cases the steric correction can be improved by calculating steric height closer to shore with the best results obtained in the depth range 500 1000 m yet for western boundaries large discrepancies remain our results therefore suggest that on time scales up to about 5 years and perhaps longer the presence of boundary currents means that the conventional steric correction to tide gauges may not be valid in many places

low frequency variability in coastal sea level from tide gauges and altimetry 1 long sea level observations are fundamental for studies of the low frequency changes in ocean circulation and climate tide gauges provide records several decades long but their locations are geographically sparse and confined to the coastline to assess the extent to which tide gauge point measurements represent broader scale conditions in the adjacent ocean we compare tide gauge records to altimeter data in their vicinity for the period 1993 2008 the analysis is based on detrended annual mean series and focuses on interannual variability the best agreement between tide gauge and altimeter series is found for mid ocean islands in the tropical pacific and indian oceans and along the coast of western australia elsewhere along most continental coasts root mean square differences between the two sea level estimates can be substantial when compared to the observed variability or the expected measurement noise with the worst correspondence found in western south america japan and eastern australia differences in magnitude as well as poor correlations between the tide gauge and altimeter estimates are involved although land motions and measurement errors can be a factor results point to the presence of considerable short spatial structure in coastal sea level at interannual time scales which can be related to the low frequency dynamics of coastally trapped circulations western boundary currents and associated eddy regimes or response to river runoff knowing whether coastal sea level variability becomes more spatially homogeneous at longer time scales must await longer sea level records

decadal shift of nao linked interannual sea level variability along the u s northeast coast abstractrecent studies have linked interannual sea level variability and extreme events along the u s northeast coast nec to the north atlantic oscillation nao a natural internal climate mode

the response of stratified frictional flow of shelf and slope waters to fluctuating large scale low frequency wind forcing abstract numerical and analytical models are developed to discuss large scale low frequency wind driven fluctuations over the continental shelf and slope in the presence of realistic density stratification and bottom friction the models employ the long wave assumption that frequencies are small relative to the inertial frequency and that alongshore scales are large relative to cross cross shelf scales an attempt is made to make the effect of bottom friction on the flow as realistic as possible by taking into account the influence of surface gravity waves on bottom stress the results were obtained for sinusoidal wind forcing having frequency and alongshore wavenumber l and are described below a general criterion for barotropic shelf water response for wind forcing frequencies in the weather band 2 few weeks to 2 few days can be derived for the purpose of rapid calculation this criterion reduces approximately tohere ns2 is a shelf averaged value of the buoyancy frequency squared is

what is the thermohaline circulation the term thermohaline circulation is widely used in the context of past and future climate change in his perspective wunsch argues that there are many different and inconsistent definitions for this term he defines ocean circulation in terms of mass fluxes which are largely driven by surface forces such as wind and tides and argues that thermohaline circulation should only refer to the separate transport of heat and salinity in the ocean

north atlantic sea level and circulation summary monthly sea levels from an extensive array of north atlantic tide gauges 26 50 n are examined the spatial scale of the sea level variations and the reasons for them are discussed one application of such a study is clearly in the design of a tide gauge network for monitoring eustatic changes of sea level the spatial scale of the sea level changes is large there is a coherent sealevel signal which can be traced along the eastern boundary of the north atlantic from newlyn 50 n to tenerife 28 n there are also two distinct groupings of tide gauges along the western boundary separated by cape hatteras the contribution of local air pressure and wind stress is quantified at each gauge through multiple regression techniques and the gains are then interpreted in terms of recent theoretical and numerical modelling studies for example the gains suggest that the wind forced boundary current along the nova scotian shelf is trapped to within about 16 km of the coast the influence of local meteorology cannot account for the large scale modes of variability the coherent signal along the eastern boundary is correlated with changes in the sverdrup transport of the north atlantic and hence the large scale wind field the two modes on the western boundary appear to be related to baroclinic boundary current variations the newlyn sea level record is finally corrected for some of the above effects to illustrate the utility of such a residual series in the identification of eustatic changes and vertical crustal movement

the effect of mediterranean exchange flow on european time mean sea level using a suite of ocean model simulations and a set of dedicated twin experiments we show that the exchange flow between the mediterranean and the north atlantic leads to a drop in time mean european coastal sea level along the atlantic coast north of gibraltar the drop is about 7 cm along the portuguese coast and remains apparent though reduced as far north as the norwegian coast we also show that mediterranean time and spatial mean sea level is about 9 cm lower than it would be without the exchange flow but assuming a small supply from the atlantic to balance evaporation each of these relationships makes possible an estimate of the magnitude of the exchange flow based on sea level measurements and estimates of 0 8 and 0 91 sverdrups are made consistent with previous determinations based mainly on current measurements in the strait of gibraltar

relation between sea level and bottom pressure and the vertical dependence of oceanic variability 1 the relation between large scale sea level and bottom pressure variability is studied using long 50 yr simulations of a general circulation model under realistic forcing admittance and coherence analyses are used to characterize the bottom pressure and sea level relationship as a function of period horizontal spatial scale and location at the model grid scale 1 bottom pressure is found to be essentially equivalent to sea level at periods 60 and in shallow depths 200 m elsewhere bottom pressure and sea level fields can differ significantly results indicate an increase of the importance of baroclinic signals with decreasing latitude and spatial scale with significant baroclinic signals at intra seasonal and longer periods present in many subtropical and mid latitude regions variability is clearly baroclinic at inter annual periods regardless of location and spatial scale results have broad implications for the interpretation and processing of both satellite altimetry and gravity data and for their assimilation into numerical models

wind induced interannual variability of sea level slope along shelf flow and surface salinity on the northwest atlantic shelf in this study we examine the importance of regional wind forcing in modulating advective processes and hydrographic properties along the northwest atlantic shelf with a focus on the nova scotian shelf nss gulf of maine gom region long term observational data of alongshore wind stress sea level slope and along shelf flow are analyzed to quantify the relationship between wind forcing and hydrodynamic responses on interannual time scales additionally a simplified momentum balance model is used to examine the underlying mechanisms our results show significant correlation among the observed interannual variability of sea level slope along shelf flow and alongshore wind stress in the nss gom region a mechanism is suggested to elucidate the role of wind in modulating the sea level slope and along shelf flow stronger southwesterly northeastward winds tend to weaken the prevailing southwestward flow over the shelf building sea level in the upstream newfoundland shelf region whereas weaker southwesterly winds allow stronger southwestward flow to develop raising sea level in the gom region the wind induced flow variability can influence the transport of low salinity water from the gulf of st lawrence to the gom explaining interannual variations in surface salinity distributions within the region hence our results offer a viable mechanism besides the freshening of remote upstream sources to explain interannual patterns of freshening in the gom

variations in the difference between mean sea level measured either side of cape hatteras and their relation to the north atlantic oscillation we consider the extent to which the difference in mean sea level msl measured on the north american atlantic coast either side of cape hatteras varies as a consequence of dynamical changes in the ocean caused by fluctuations in the north atlantic oscillation nao from analysis of tide gauge data we know that changes in msl difference and nao index are correlated on decadal to century timescales enabling a scale factor of msl difference change per unit change in nao index to be estimated changes in trend in the nao index have been small during the past few centuries when measured using windows of order 60 120 years therefore if the same scale factor applies through this period of time the corresponding changes in trend in msl difference for the past few centuries should also have been small it is suggested thereby that the sea level records for recent centuries obtained from salt marshes adjusted for long term vertical land movements should have essentially the same nao driven trends south and north of cape hatteras only differing due to contributions from other processes such as changes in the meridional overturning circulation or geophysical fingerprints the salt marsh data evidently support this interpretation within their uncertainties for the past few centuries and perhaps even for the past millennium recommendations are made on how greater insight might be obtained by acquiring more measurements and by improved modelling of the sea level response to wind along the shelf

the sea level budget along the northwest atlantic coast gia mass changes and large scale ocean dynamics sea level rise and decadal variability along the northwestern coast of the north atlantic ocean are studied in a self consistent framework that takes into account the effects of solid earth deformation and geoid changes due to large scale mass redistribution processes observations of sea and land level changes from tide gauges and gps are compared to the cumulative effect of gia present day mass redistribution and ocean dynamics over a 50 year period 1965 2014 gia explains the majority of the observed sea level and land motion trends as well as almost all interstation variability present day mass redistribution resulting from ice melt and land hydrology causes both land uplift and sea level rise in the region we find a strong correlation between decadal steric variability in the subpolar gyre and coastal sea level which is likely caused by variability in the labrador sea that is propagated southward the steric signal explains the majority of the observed decadal sea level variability and shows an upward trend and a significant acceleration which are also found along the coast the sum of all contributors explains the observed trends in both sea level rise and vertical land motion in the region as well as the decadal variability the sum of contributors also explains the observed acceleration within confidence intervals the sea level acceleration coincides with an accelerating density decrease at high latitudes

is there a 60 year oscillation in global mean sea level 1 we examine long tide gauge records in every ocean basin to examine whether a quasi 60 year oscillation observed in global mean sea level gmsl reconstructions reflects a true global oscillation or an artifact associated with a small number of gauges we find that there is a significant oscillation with a period around 60 years in the majority of the tide gauges examined during the 20th century and that it appears in every ocean basin averaging of tide gauges over regions shows that the phase and amplitude of the fluctuations are similar in the north atlantic western north pacific and indian oceans while the signal is shifted by 10 years in the western south pacific the only sampled region with no apparent 60 year fluctuation is the central eastern north pacific the phase of the 60 year oscillation found in the tide gauge records is such that sea level in the north atlantic western north pacific indian ocean and western south pacific has been increasing since 1985 1990 although the tide gauge data are still too limited both in time and space to determine conclusively that there is a 60 year oscillation in gmsl the possibility should be considered when attempting to interpret the acceleration in the rate of global and regional mean sea level rise

does the mid atlantic united states sea level acceleration hot spot reflect ocean dynamic variability 1 to test a hypothesized faster than global sea level acceleration along the mid atlantic united states i construct a gaussian process model that decomposes tide gauge data into short term variability and longer term trends and into globally coherent regionally coherent and local components while tide gauge records indicate a faster than global increase in the rate of mid atlantic u s sea level rise beginning 1975 this acceleration could reflect either the start of a long term trend or ocean dynamic variability the acceleration will need to continue for 2 decades before the rate of increase of the sea level difference between the mid atlantic and southeastern u s can be judged as very likely unprecedented by 20th century standards however the difference is correlated with the atlantic multidecadal oscillation north atlantic oscillation and gulf stream north wall indices all of which are currently within the range of past variability

the relationship between sea level and bottom pressure variability in an eddy permitting ocean model we investigate the relationship between sea level after application of an inverse barometer correction and ocean bottom pressure in an eddy permitting ocean model we find the presence of eddies can disrupt this relationship even on timescales as short as 10 20 days but only in the regions of most energetic eddy variability away from eddies the relationship is similar to that seen in a coarserresolution model with a tight relationship between sea level and bottom pressure at high frequencies but with significant correlations between sea level and bottom pressure at interannual timescales seen only in shelf sea regions in the deep ocean regions where sea level and bottom pressure remain related out to the longest timescales are in the arctic ocean and regions of the southern ocean where particularly large amplitude barotropic fluctuations are found but where the mesoscale signal is weak

enhanced warming of the northwest atlantic ocean under climate change the intergovernmental panel on climate change ipcc fifth assessment of projected global and regional ocean temperature change is based on global climate models that have coarse 100 km ocean and atmosphere resolutions in the northwest atlantic the ensemble of global climate models has a warm bias in sea surface temperature due to a misrepresentation of the gulf stream position thus existing climate change projections are based on unrealistic regional ocean circulation here we compare simulations and an atmospheric co2 doubling response from four global climate models of varying ocean and atmosphere resolution we find that the highest resolution climate model 10 km ocean 50 km atmosphere resolves northwest atlantic circulation and water mass distribution most accurately the co2 doubling response from this model shows that upper ocean 0 300 m temperature in the northwest atlantic shelf warms at a rate nearly twice as fast as the coarser models and nearly three times faster than the global average this enhanced warming is accompanied by an increase in salinity due to a change in water mass distribution that is related to a retreat of the labrador current and a northerly shift of the gulf stream both observations and the climate model demonstrate a robust relationship between a weakening atlantic meridional overturning circulation amoc and an increase in the proportion of warm temperate slope water entering the northwest atlantic shelf therefore prior climate change projections for the northwest atlantic may be far too conservative these results point to the need to improve simulations of basin and regional scale ocean circulation

a simple model of the decadal response of the ocean to stochastic wind forcing abstract a simple linear model is used to estimate the decadal response of the extratropical ocean to wind stress forcing assuming a flat bottom a mean state at rest and no dissipation the barotropic fields are governed by a time dependent sverdrup balance the baroclinic ones by the long rossby wave equation the ocean is bounded by a coast in the east and a radiation condition is used in the west at each frequency the baroclinic response consists of a forced response plus a rossby wave generated at the eastern boundary for zonally independent forcing the response propagates westward at twice the rossby phase speed the wind stress is assumed to be stochastic with a white frequency spectrum so the model represents the continuous excitation of the ocean interior by the weather fluctuations the model predicts the shape and level of the frequency spectra of the oceanic pressure field and their variation with longitude and latitude the baroclinic response is spread over a continuum of frequencies

inverted barometer contributions to recent sea level changes along the northeast coast of north america regional sea level sl changes reflect dynamic and isostatic ocean effects recent works have interpreted accelerated and extreme sl changes along the northeast coast of north america primarily in terms of dynamic changes however dedicated study of isostatic changes related to surface atmospheric pressure loading the inverted barometer ib effect has been lacking this investigation uses five different atmospheric pressure products to analyze the influence of the ib effect on annual mean sl from tide gauge records the ib effect explains 25 of interannual sl variance and accounts for 50 of the magnitude of a recent extreme event of sl rise along atlantic canada and new england estimated ib effects also amount to 10 30 of recent multidecadal sl accelerations over the mid atlantic bight and southern new england these findings reiterate the need for careful estimation and removal of isostatic effects for studies of dynamic sl

seasonal circulation on the western and central scotian shelf abstract a realistic representation of 3d seasonal circulation and hydrography on the western and central scotian shelf has been obtained from historical observations and a combination of diagnostic and prognostic numerical models with forcing by tides wind stress and baroclinic and barotropic pressure gradients the major current features the southwestward nova scotian and shelf edge currents and partial gyres around browns and sable island banks are found to persist year round but with significant seasonal changes comparison with current meter observations shows good agreement for the browns bank southwest nova scotia and inner shelf regions and poorer agreement in the sable island bank and shelf edge regions where current and density observations are sparser and tidal influences weaker there is significant spatial structure in the seasonal circulation and hydrography and in the underlying dynamical processes on the shelf scale there are substantial changes in stratification potential energy

annual sea level changes on the north american northeast coast influence of local winds and barotropic motions abstractunderstanding the relationship between coastal sea level and the variable ocean circulation is crucial for interpreting tide gauge records and projecting sea level rise in this study annual sea level records adjusted for the inverted barometer effect from tide gauges along the north american northeast coast over 1980 2010 are compared to a set of data assimilating ocean reanalysis products as well as a global barotropic model solution forced with wind stress and barometric pressure correspondence between models and data depends strongly on model and location at sites north of cape hatteras the barotropic model shows as much if not more skill than ocean reanalyses explaining about 50 of the variance in the adjusted annual tide gauge sea level records additional numerical experiments show that annual sea level changes along this coast from the barotropic model are driven by local wind stress over the continental shelf and slope this result is interpreted in the light of a simple dynamic

coherent sea level variability on the north atlantic western boundary interannual to decadal sea level variability on the north atlantic western boundary is surprisingly coherent over substantial distances stretching from the caribbean to nova scotia the physical mechanisms responsible for this basin scale low frequency coherence are explored in a diagnosis of simulated ocean fields from gecco which reproduces the observations to good approximation coastal sea level variability on the western boundary is known to be influenced by meridional divergence in the boundary current resulting in a geostrophic tilting of the sea surface this mechanism is found to be of leading order along some stretches of the boundary but it does not account for the coherence spanning the western north atlantic instead the coherence along the entire boundary is accounted for by vertical divergence resulting in the uniform rise and fall of the sea surface west of the 295 e meridian the vertical divergence is found to be due to net vertically integrated zonal transport across this meridian resulting from meridional variation in the sverdrup transport over the basin interior

revisiting the timpson induced earthquake sequence a system of two parallel faults the 17 may 2012 m4 8 timpson earthquake is the largest known earthquake in eastern texas it is suspected to have been induced by wastewater injection from two nearby high volume wells its catalo

on the relationship between the meridional overturning circulation alongshore wind stress and united states east coast sea level in the community earth system model large ensemble

mean sea level variability along the northeast american atlantic coast and the roles of the wind and the overturning circulation the variability in mean sea level msl during 1950 2009 along the northeast american atlantic coast north of cape hatteras has been studied using data from tide gauges and satellite altimetry and information from the liverpool hadley centre lhc ocean model thereby providing new insights into the spatial and temporal scales of the variability although a relationship between sea level and the overturning circulation can be identified an increase of approximately 1 5 cm in msl for a decrease of 1 sv in overturning transport it is the effect of the nearshore wind forcing on the shelf that is found to dominate the interannual sea level variability in particular winds are found to be capable of producing low frequency changes in msl accelerations in a narrow coastal band comparable to those observed by the tide gauges evidence is presented supporting the idea of a common mode of spatially coherent low frequency msl variability both to the north and south of cape hatteras and throughout the northwest atlantic which is associated with large spatial scale density changes from year to year

sea level on the u s east coast decadal variability caused by open ocean wind curl forcing one of the puzzling features of sea level on the east coast of the united states is the decedal scale variability the fluctuations are 10 15 cm peak to peak at periods longer than a few years the authors find that this variability in the frequency band treated with the model is largely caused by a deep sea signal generated by the wind stress curl over the north atlantic a simple forced long rossby wave model of the response of the thermocline to wind forcing is used computing long wave speeds from observed hydrographic data the authors model the response of the ocean at periods longer than 3 years for the full width of the atlantic and for the north south extent of the main anticyclonic gyre 188 388n the model output in deep water shows remarkably good agreement with tide gauges both at bermuda 328n and puerto rico 188n as well as with dynamic height fluctuations of 20 cm peak to peak once these fluctuations reach the western side of the ocean the authors estimate coastal sea level by constructing a complementary coastal model the coastal model is geostrophic and conserves mass within a nearshore region that encompasses the gulf stream by extending this nearshore region as far south as 148 188n and using only the oceanic fluctuations to force the variability in the stream between 80 and 90 of the variance of sea level at coastal tide gauges can be explained sea level along the coast is used to test the model assumptions the basic results however seem important because they are constrained only by open ocean wind forcing and not by input boundary conditions

geometric models of folding at loch monar scotland using computer simulation abstract small scale hand specimens were collected at loch monar scotland one of the classic areas of fold interference patterns from the analysis of these the geometries of the f 1 and f 2 folds were derived by computer simulation the complex three dimensional form of the fold interference shapes can then be reproduced very closely f 2 fold shapes and motion directions derived from the small scale structures along with those derived from field observations of f 1 lineations deformed about f 2 folds were then applied to an extrapolated pre f 2 shape of the loch monar synform this generated a map pattern strikingly similar to that mapped by ramsay 1958 the geometric models provide useful information for mechanical hypotheses of the folding observed at loch monar the simulation reveals an interesting problem that whereas many small scale interference patterns reflect the map pattern of the major structure there are exposures of interference patterns that do not these are dome and basin type 1 patterns found in an area where a major f 2 fold hinge crosses an f 1 fold hinge zone by examining the deformed l 1 lineation patterns found in this area along with the computed d 2 strain orientations and the field observations of f 2 fold geometries we suggest that those patterns formed due to local variations in the displacement directions during the f 2 folding perhaps due to the mechanical influence of relatively competent pegmatite veins on the small scale f 2 folds the very high d 2 strain has then amplified the dome and basin elements to very elongate cone and cylinder forms this creates local type 1 patterns within a regional type 2 interference pattern structure

signature of the atlantic meridional overturning circulation in sea level along the east coast of north america in this letter we examine the relationship between the north atlantic meridional overturning circulation moc and sea level sl along the east coast of north america in the eddy permitting ocean model occam we find a distinctive topography following pattern of sl variability in the western north atlantic that is closely linked with the changing strength of the moc with a 2 cm drop in sl along the us east coast corresponding to a 1sv increase in the moc we find a similar pattern of sl variability in the altimetry record and show that this meridionally coherent sl mode dominates interannual sl variability at tide gauges along the north american east coast between 40 50n hence we conclude that north american coastal sea level may indeed be a useful indicator of moc variability on interannual timescales allowing an observationally based estimate of the likely range of interannual moc fluctuations to be determined citation bingham r j and c w hughes 2009 signature of the atlantic meridional overturning circulation in sea level along the east coast of north america geophys res lett 36 l02603 doi 10 1029 2008gl036215

oceanic control of sea level rise patterns along the east coast of the united states 1 along the eastern seaboard of the u s from florida to maine sea level rise slr shows notable patterns and significant deviation from the global mean which have been attributed to land subsidence consistent with several recent studies we analyze various observation and modeling data and find that ocean dynamics is also an important factor in explaining these coastal slr patterns despite a southward shift since the 1990s an overall northward shift of the gulf stream during the twentieth century contributed to the faster slr in the mid atlantic region north carolina to new jersey in response to the 21st century climatic forcing the rise fall of the dynamic sea level north south of cape hatteras is mainly induced by the significant decline of ocean density contrast across the gulf stream this baroclinic process is the likely cause of the recent switch of the coastal slr to a pattern with faster slower rates north south of cape hatteras citation yin j and p b goddard 2013 oceanic control of sea level rise patterns along the east coast of the united states geophys res lett 40 doi 10 1002 2013gl057992

gyre scale atmospheric pressure variations and their relation to 19th and 20th century sea level rise 1 most of the long tide gauge records in the north atlantic and north pacific commonly used to estimate global sea level rise and acceleration display a marked difference in behavior in the late 1800 s early 1900 s compared to the latter half of the 20th century the rates of sea level rise tend to be lower in the 19th compared to 20th century we show this behavior may be related to long term gyre scale surface pressure variations similar to those associated with the northern annular mode as sea level pressure increases decreases at decadal and longer timescales at the centers of the subtropical atmospheric gyres sea level trends along the eastern margins in each ocean basin decrease increase this is not an isostatic response the scaling between local surface pressure and sea level at interannual and longer timescales is 3 to 6 times greater than expected by that mechanism rather it appears to be the result of large possibly gyre scale changes in ocean circulation some evidence is also presented indicating slow 2 cm sec westward propagation of sea level changes in the atlantic from the west coast of europe to the east coast of the u s which produce the decadal variability seen there

el nino variability in simple ocean data assimilation soda 1871 2008 1 a new ocean reanalysis that covers the period from 1871 to 2008 is used to explore the time evolving characteristics of el nino the new reanalysis assimilates all available hydrographic and sea surface temperature data into a model of the global ocean forced with surface boundary conditions from an atmospheric reanalysis that also covers the period from 1871 through 2008 using traditional measures of el nino our reanalysis shows that the timing of el nino events is in agreement with sea surface temperature reconstructions but el nino in the reanalysis is stronger particularly from 1871 to 1920 a new index based on the first moment of the temperature anomaly is introduced the new index is used to characterize the strength and location of el nino events and has the advantage that it is independent of the location of el nino using the new index el nino in the reanalysis shows prominent decadal variability of strength but relatively little long term trend el nino events were strong in the last part of the 19th century and first part of the 20th century and again in the latter part of the 20th century with weak el nino events in the middle of the 20th century the location of el nino also varies considerably ranging from the western to the eastern pacific near the coast of south america however the null hypothesis that the location of el nino can be represented as a random distribution about a central longitude of about 140 w cannot be rejected

origin of spatial variation in us east coast sea level trends during 1900 2017 identifying the causes of historical trends in relative sea level the height of the sea surface relative to earth s crust is a prerequisite for predicting future changes rates of change along the eastern coast of the usa the us east coast during the past century were spatially variable and relative sea level rose faster along the mid atlantic bight than along the south atlantic bight and the gulf of maine past studies suggest that earth s ongoing response to the last deglaciation1 5 surface redistribution of ice and water5 9 and changes in ocean circulation9 13 contributed considerably to this large scale spatial pattern here we analyse instrumental data14 15 and proxy reconstructions4 12 using probabilistic methods16 18 to show that vertical motions of earth s crust exerted the dominant control on regional spatial differences in relative sea level trends along the us east coast during 1900 2017 explaining most of the large scale spatial variance rates of coastal subsidence caused by ongoing relaxation of the peripheral forebulge associated with the last deglaciation are strongest near north carolina maryland and virginia such structure indicates that earth s elastic lithosphere is thicker than has been assumed in other models19 22 we also find a substantial coastal gradient in relative sea level trends over this period that is unrelated to deglaciation and suggests contributions from twentieth century redistribution of ice and water our results indicate that the majority of large scale spatial variation in long term rates of relative sea level rise on the us east coast is due to geological processes that will persist at similar rates for centuries vertical motions of earth s crust had the greatest effect on regional spatial differences in relative sea level trends along the eastern coast of the usa during 1900 2017 explaining most of the large scale spatial variance in regional rates of sea level rise

relative sea level change in newfoundland canada during the past 3000 years abstract several processes contributing to coastal relative sea level rsl change in the north atlantic ocean are observed and or predicted to have distinctive spatial expressions that vary by latitude to expand the latitudinal range of rsl records spanning the past 3000 years and the likelihood of recognizing the characteristic fingerprints of these processes we reconstructed rsl at two sites big river and placentia in newfoundland from salt marsh sediment bayesian transfer functions established the height of former sea level from preserved assemblages of foraminifera and testate amoebae age depth models constrained by radiocarbon dates and chronohorizons estimated the timing of sediment deposition during the past 3000 years rsl rose by 3 0 m at big river and by 1 5 m at placentia a locally calibrated geotechnical model showed that post depositional lowering through sediment compaction was minimal to isolate and quantify contributions to rsl from global regional linear regional non linear and local scale processes we decomposed the new reconstructions and those in an expanded global database using a spatio temporal statistical model the global component confirms that 20th century sea level rise occurred at the fastest century scale rate in over 3000 years p 0 999 distinguishing the contributions from local and regional non linear processes is made challenging by a sparse network of reconstructions however only a small contribution from local scale processes is necessary to reconcile rsl reconstructions and modeled rsl trends we identified three latitudinally organized groups of sites that share coherent regional non linear trends and indicate that dynamic redistribution of ocean mass by currents and or winds was likely an important driver of sea level change in the north atlantic ocean during the past 3000 years