eddy resolving observation of the north pacific subtropical mode water abstracthydrographic data obtained by high resolution shipboard observations and argo profiling floats have been analyzed to study the mesoscale structure and circulation of the north pacific subtropical mode water stmw the float data show that in the late winter of 2008 stmw having a temperature of approximately 18 8 17 7 and 16 6 c formed west of 140 e at 140 150 e and east of 150 e respectively in the recirculation gyre south of the kuroshio extension after spring the newly formed stmw gradually shift southward decreasing in thickness simultaneously the stmws of 16 6 and 17 7 c are gradually stirred and then mixed in terms of properties in late fall they seem to be integrated to form a single group of stmws having a temperature centered at 17 2 c such stmw circulation in 2008 is much more turbulent than that in 2006 which was investigated in a previous study the difference between the two years is attributed to the more variable state of the kuroshio extension in 2008 associate

observational evidence for oceanic forcing of atmospheric variability in the nordic seas area abstractsubstantial predictability of the wintertime atmospheric variability in the nordic greenland iceland norwegian and barents seas region is reported based on oceanic observations and atmospheric reanalysis data in particular about 60 of the variance of the winter december march regional average surface air temperature sat and early winter november february zonal geostrophic winds over the western barents sea opening bso area in the period 1982 2006 is explained by the previous summer june september atlantic water temperature awt anomalies in this area the atmospheric response to oceanic heat anomalies mainly occurs in the marginal ice zone miz where the sea ice and corresponding surface heat flux shf anomalies should be triggered by entrainment of subsurface heat anomalies into the deepening mixed layer and sustained through winter by anomalous oceanic heat transport the latter should be caused by geostrophic current anomalies forced by anomalous ocean ekman suction and or on

anatomy of north pacific decadal variability abstract a systematic analysis of north pacific decadal variability in a full physics coupled ocean atmosphere model is executed the model is an updated and improved version of the coupled model studied by latif and barnett evidence is sought for determining the details of the mechanism responsible for the enhanced variance of some variables at 20 30 yr timescales the possible mechanisms include a midlatitude gyre ocean atmosphere feedback loop stochastic forcing remote forcing or sampling error decadal variability in the model is expressed most prominently in anomalies of upper ocean streamfunction sea surface temperature sst and latent surface heat flux in the kuroshio oyashio extension koe region off japan the decadal signal off japan is initiated by changes in strength and position of the aleutian low the atmospheric perturbations excite sst anomalies in the central and eastern north pacific with opposing signs and canonical structure the atmospheric perturbations also change the ekm

predicting north atlantic sea surface temperature variability on the basis of the first mode baroclinic rossby wave model 1 predictability of sea surface temperature sst variations over the north atlantic ocean is studied on the basis of the first mode baroclinic rossby wave model this simple linear wave model can explain about 10 46 of the wintertime sst variability in several regions of the north atlantic basin including the tropics between 5 n and 20 n the eastern subtropics between 27 n and 34 n and the east of newfoundland it is shown that the wintertime sst anomalies can be skillfully predicted up to 3 months ahead in the tropical atlantic 18 months in the eastern subtropical atlantic and 3 years east of newfoundland on the basis of the first mode baroclinic rossby wave adjustment

on the persistence of cold season sst anomalies associated with the annular modes abstractin this study a simple stochastic climate model is used to examine the impact of the ocean mixed layer depth surface turbulent energy fluxes and ekman currents on the persistence of cold season extratropical sea surface temperature sst anomalies associated with variability in the annular modes of atmospheric circulation in both hemispheres observational analysis reveals that during the cold season sst anomalies associated with the southern annular mode sstsam persist considerably longer than those associated with the northern annular mode sstnam using the simple model it is shown that the persistence of the cold season sstsam is consistent with the simple stochastic climate paradigm in which the atmospheric forcing is approximated as white noise and the persistence of sst anomalies can be largely determined by the thermal inertia of the ocean mixed layer in the north atlantic however the simple climate model overestimates the persistence of the cold season sstnam it is thought th

upper ocean variability between iceland and newfoundland 1993 1998 we investigate the variability of upper ocean temperature and surface salinity between iceland and newfoundland along world ocean circulation experiment line ax2 in 1993 1998 north of 54 n as well as close to newfoundland deviations from the seasonal cycle indicate upper ocean warming from 1994 to 1998 with largest anomalous warming during late 1995 early 1996 and during the winter 1997 1998 north of 54 n surface salinity increases after mid 1996 the winter of 1995 1996 is the first winter of weak westerlies after more than 20 years of strong westerly conditions in the subarctic gyre and the ocean loses less heat during that winter than during a normal year the magnitude of upper ocean heat content change is at least twice as large as what results from the change in air sea fluxes which indicates a complementary contribution to heat content change by advection altimetric sea level data indicate also an increase of sea level of the order of 6 5 cm during that year out of which more than 4 cm is contributed by the steric change associated with the temperature increase a principal component analysis of the sea level data suggests that the increase sensed along line ax2 west of the reykjanes ridge is found in most of the subpolar gyre although to a lesser extent in most other areas

sediment yield exceeds sediment production in arid region drainage basins we use 10 be and 26 al to determine long term sediment generation rates identify significant sediment sources and test for landscape steady state in nahal yael an extensively studied hyperarid drainage basin in southern israel comparing a 33 yr sediment budget with 33 paired 10 be and 26 al analyses indicates that short term sediment yield 113 138 t km 2 yr 1 exceeds long term sediment production 74 16 t km 2 yr 1 by 53 86 the difference suggests that the basin is not in steady state but is currently evacuating sediment accumulated during periods of more rapid sediment generation and lower sediment yield nuclide data indicate that 1 sediment leaving the basin is derived primarily from hillslope colluvium 2 bedrock weathers more rapidly beneath a cover of colluvium than when exposed and 3 long term erosion rates of granite schist and amphibolite are similar

atlantic multidecadal oscillation and northern hemisphere s climate variability proxy and instrumental records reflect a quasi cyclic 50 80 year climate signal across the northern hemisphere with particular presence in the north atlantic modeling studies rationalize this variability in terms of intrinsic dynamics of the atlantic meridional overturning circulation influencing distribution of sea surface temperature anomalies in the atlantic ocean hence the name atlantic multidecadal oscillation amo by analyzing a lagged covariance structure of a network of climate indices this study details the amo signal propagation throughout the northern hemisphere via a sequence of atmospheric and lagged oceanic teleconnections which the authors term the stadium wave initial changes in the north atlantic temperature anomaly associated with amo culminate in an oppositely signed hemispheric signal about 30 years later furthermore shorter term interannual to interdecadal climate variability alters character according to polarity of the stadium wave induced prevailing hemispheric climate regime ongoing research suggests mutual interaction between shorter term variability and the stadium wave with indication of ensuing modifications of multidecadal variability within the atlantic sector results presented here support the hypothesis that amo plays a significant role in hemispheric and by inference global climate variability with implications for climate change attribution and prediction

atlantic meridional overturning circulation slowdown cooled the subtropical ocean 1 observations show that the upper 2 km of the subtropical north atlantic ocean cooled throughout 2010 and remained cold until at least december 2011 we show that these cold anomalies are partly driven by anomalous air sea exchange during the cold winters of 2009 2010 and 2010 2011 and more surprisingly by extreme interannual variability in the ocean s northward heat transport at 26 5 n this cooling driven by the ocean s meridional heat transport affects deeper layers isolated from the atmosphere on annual timescales and water that is entrained into the winter mixed layer thus lowering winter sea surface temperatures here we connect for the first time variability in the northward heat transport carried by the atlantic meridional overturning circulation to widespread sustained cooling of the subtropical north atlantic challenging the prevailing view that the ocean plays a passive role in the coupled ocean atmosphere system on monthly to seasonal timescales

sediment transfer by shallow landsliding in the queen charlotte islands british columbia despite the importance of landsliding in routing sediment through mountainous drainage basins few studies have documented landsliding rates over extended time and space scales we have investigated landsliding in surficial material in the queen charlotte islands using a large inventory of events derived from aerial photography covering an area of 166 7 km 2 the mean erosion rate for shallow landsliding is 0 10 mm a 1 which is at the upper end of shallow landsliding rates observed in the pacific northwest and coastal british columbia but several orders of magnitude lower than rock based landsliding rates reported in the literature probability distributions for landslide area and volume are somewhat convex in form flattening of the curve found at low magnitudes may be due to sampling bias or physical mechanisms inhibiting failure and the steepening for high values may exist because the sampling period is not long enough to adequately represent large events landslides generally initiate on hillslope gradients greater than 0 50 0 60 the largest numbers of landslides occur on south to southwest facing slopes and east to northeast facing slopes most events occur on concave and straight hillslopes in upper slope positions landsliding rates were found not to be af fected by rock type hillslopes in the queen charlotte islands are often mantled by weathered quaternary deposits and hence landsliding events are not directly controlled by weathering of bedrock about 31 of landslides identified in this study deposited material in stream reaches with about 83 of these landslides deposited in reaches with gradients between 3 and 10 resume malgre la grande contribution des glissements de terrain a acheminer des sediments a travers des bassins de drainage montagneux peu d etudes ont documente les taux de glissements de terrain sur une longue periode de temps et sur de grandes superficies nous avons fait des recherches sur des glissements de materiaux de surface dans les iles de la reine charlotte en utilisant un grand inventaire d evenements tires de photographies aeriennes couvrant une re

extratropical subduction and decadal modulation of el nino an extension of the battisti hirst delayed oscillator model is developed in an attempt to understand the potential effects of extratropical subduction on el nino in particular a meridional delay term is included to parameterise the effects of extratropical subduction on eastern equatorial pacific pycnocline anomalies the magnitude of the eastern equatorial pycnocline displacement and the time delay for its response to an extratropical sea surface temperature anomaly are inferred from both ocean and coupled atmosphere ocean gcm experiments the inclusion of the delayed subduction term causes el nino to modulate on decadal interdecadal timescales consistent with observations and the expectations of gu and philander

is there a low frequency bias in multiproxy reconstructions of tropical pacific sst variability abstract decadal and longer term variability in the tropical pacific has the potential to impact climate worldwide yet paleoclimate observations and climate model simulations disagree on the nature of this variability in this study we investigate whether biases from paleoclimate reconstruction methodology and the currently available proxy network cause reconstructions of enso to overestimate the multidecadal century scale variability of the pacific we build new reconstructions using a variety of commonly employed methods and test the effects of four types of bias on analogous pseudoproxy reconstructions these biases include 1 the number of records used in the reconstruction 2 chronological uncertainty 3 noise in individual proxy records and 4 the geographical distribution of the proxy network we find that each of these biases cause enso reconstructions to overestimate the importance of low frequency variability these biases may partially explain why multiproxy reconstructions of pacific variability have stronger low frequency variability than predicted by historical observations or climate models and why these reconstructions do not have coherent signals over the multidecadal century scale

heat budget in the kuroshio extension region 1993 99 abstract processes responsible for the seasonal and interannual variations of the sea surface temperature as well as of the heat content of the upper ocean 0 400 m in the kuroshio extension region are examined from a 3d advection diffusion model in finite elements with an embedded bulk mixed layer the geostrophic velocity is specified externally from topex poseidon altimeter data and ekman velocity is specified from ncep wind stress the thermal field from the model shows good agreement with observations while both atmospheric and oceanic processes are required to explain observed nonseasonal sst changes the interannual heat storage rate is dominated by horizontal advection in particular the transition between an elongated and a contracted state of the kuroshio caused by geostrophic advection has a clear signature in the sst there is an indication that this process is accompanied by consistent changes in nonseasonal entrainment when the kuroshio is in an elongated state and warmer waters are pr

observations inferences and mechanisms of the atlantic meridional overturning circulation a review this is a review about the atlantic meridional overturning circulation amoc its mean structure temporal variability controlling mechanisms and role in the coupled climate system the amoc plays a central role in climate through its heat and freshwater transports northward ocean heat transport achieved by the amoc is responsible for the relative warmth of the northern hemisphere compared to the southern hemisphere and is thought to play a role in setting the mean position of the intertropical convergence zone north of the equator the amoc is a key means by which heat anomalies are sequestered into the ocean s interior and thus modulates the trajectory of climate change fluctuations in the amoc have been linked to low frequency variability of atlantic sea surface temperatures with a host of implications for climate variability over surrounding landmasses on intra annual timescales variability in amoc is large and primarily reflects the response to local wind forcing meridional coherence of anomalies is limited to that of the wind field on interannual to decadal timescales amoc changes are primarily geostrophic and related to buoyancy anomalies on the western boundary a pacemaker region for decadal amoc changes is located in a western transition zone along the boundary between the subtropical and subpolar gyres decadal amoc anomalies are communicated meridionally from this region amoc observations as well as the expanded ocean observational network provided by the argo array and satellite altimetry are inspiring efforts to develop decadal predictability systems using coupled atmosphere ocean models initialized by ocean data

eastward propagating surface anomalies at ocean gyre boundaries 1 inspection of animations and time distance hovmoller plots of unfiltered data from a state of the art coupled climate model hadcm3 reveals eastward propagating surface temperature salinity anomalies at subpolar subtropical gyre boundaries throughout the world ocean maximum anomalies are 4 c and 0 3 practical salinity units horizontal length scales are 1000 km the anomalies travel at a speed consistent with advection by mean near surface currents generation regions are located at western boundaries and possess an order of magnitude higher variability than all other regions in some cases surface heat fluxes are shown to cause anomaly generation in other cases surface current anomalies are likely to be responsible eastward anomaly propagation also occurs in the estimating the circulation and climate of the ocean model the coarser resolution fast ocean rapid troposphere experiment forte coupled model shows no propagating anomalies sea surface anomalies in the instrumental record are investigated using ship based sea surface temperature sst and heat fluxes and satellite sst and altimetry unlike the models hovmoller plots and animations of the unfiltered observational data showed no evidence of eastward propagation by applying a decadal timescale band pass filter to the sst time series we identify underlying propagation of basin scale anomalies in both hadcm3 and observations maximum anomalies are 1 c and length scales are 2500 km these anomalies travel at speeds significantly slower than mean near surface currents ten anomalies are identified during the period 1870 2002 mostly in the eastern atlantic basin east of 45 w hadcm3 displayed only one propagating anomaly of this type in a typical 100 years of data we discuss possible reasons for the range of results in models and observations

large changes in the hydrographic structure of the bay of biscay after the extreme mixing of winter 2005 the extremely cold and dry winter of 2005 in southwestern europe caused a profound transformation of the upper ocean hydrographic structure of the bay of biscay area making it completely different from the previous decade the strong local winter cooling resulted in the highest density flux estimated since the 1960s the extreme buoyancy loss triggered the mixed layer to reach unprecedented depths affecting directly the level of local modal waters that are usually unconnected to air sea interaction the water column just below the climatological average mixed layer entered in a process of quick cooling that compensated in 2 years the 0 5 c gained in the period 1994 2004 enhanced by a pronounced precipitation deficit the event caused concurrently a downward salt injection that made deeper levels of east north atlantic central water begin a process of warming by isopycnal change something never observed during the 1990s as an overall result the stratification of the upper permanent thermocline was dramatically reduced the observed cold low stratification anomaly had a substantial spatial extent and remained for 2 years below the seasonal thermocline development constituting a typical case of the reemergence mechanism but was abruptly interrupted in the warmest winter on record of 2007 in addition to the hydrographic changes the winter 2005 event had a notable effect on the marine ecosystem

north atlantic modeling of low frequency variability in mode water formation abstract the generation of interannual and near decadal variability in the formation of mode waters in the western north atlantic is investigated in the realistic framework of an isopycnic coordinate ocean model forced with atmospheric data from 1946 to 1988 at bermuda the model reproduces quite well the observed potential vorticity and isopycnal depth anomalies associated with the subtropical mode water stmw heat storage and preconditioning of the convective activity are found to be the important factors for the generation of stmw variability with persistence of cold warm conditions associated with anomalous heat loss gain over the western subtropics being more significant for the generation of the simulated variability than are strong anomalous events in isolated years in the labrador sea the model captures the phase and order of magnitude of the observed near decadal variability in the convective activity if not its maximum amplitude the simulated potential vorticity anomalies are as o

notes and correspondenceatmospheric effects on upper ocean temperature in the southeast tasman sea abstract the temperature profile in the ocean mixed layer was simulated using a turbulence closure model for a period of 18 years 1980 97 at a site in the southeast tasman sea 42 s 170 e the simulation was forced at the surface by a meteorological dataset derived from land station data sea surface temperature sst from the model was compared with the ncep 1 sst analysis beginning in 1982 the mean annual cycle and monthly anomalies in modeled sst agree with the ncep dataset in several respects modeled and observed sst anomalies are highly correlated with each other and are similar in overall magnitude timescale and phase however the model underpredicts the magnitude of sst anomalies in winter modeled and observed sst lagged correlation fields are similar with both showing a high correlation of sst anomalies in winter with anomalies in the previous spring the model has a pronounced recurrence mechanism that is anomalous temperatures in the deep mixed layer in spring remain below the sha

role of the gulf stream and kuroshio oyashio systems in large scale atmosphere ocean interaction a review abstract ocean atmosphere interaction over the northern hemisphere western boundary current wbc regions i e the gulf stream kuroshio oyashio and their extensions is reviewed with an emphasis on their role in basin scale climate variability sst anomalies exhibit considerable variance on interannual to decadal time scales in these regions low frequency sst variability is primarily driven by basin scale wind stress curl variability via the oceanic rossby wave adjustment of the gyre scale circulation that modulates the latitude and strength of the wbc related oceanic fronts rectification of the variability by mesoscale eddies reemergence of the anomalies from the preceding winter and tropical remote forcing also play important roles in driving and maintaining the low frequency variability in these regions in the gulf stream region interaction with the deep western boundary current also likely influences the low frequency variability surface heat fluxes damp the low frequency sst anomalies ove

north atlantic decadal variability air sea coupling oceanic memory and potential northern hemisphere resonance in this paper the causes and mechanisms of north atlantic decadal variability are explored in a series of coupled ocean atmosphere simulations the model captures the major features of the observed north atlantic decadal variability the north atlantic sst anomalies in the model control simulation exhibit a prominent decadal cycle of 12 16 yr and a coherent propagation from the western subtropical atlantic to the subpolar region a series of additional modeling experiments are conducted in which the air sea coupling is systematically modified in order to evaluate the importance of air sea coupling for the north atlantic decadal variability being studied this shall be referred to as modeling surgery the results suggest the critical role of ocean atmosphere coupling in sustaining the north atlantic decadal oscillation at selected time scales the coupling in the north atlantic is characterized by a robust north atlantic oscillation nao like atmospheric response to the sst tripole anomaly which tends to intensify the sst anomaly and meanwhile also provide a delayed negative feedback this delayed negative feedback is predominantly associated with the adjustment of the subtropical gyre in response to the anomalous wind stress curl in the subtropical atlantic atmospheric stochastic forcing can drive sst patterns similar to those in the fully coupled ocean atmosphere system but fails to generate any preferred decadal time scales the simulated north atlantic decadal variability therefore can be viewed as a coupled ocean atmosphere mode under the influence of stochastic forcing this modeling study also suggests some potential resonance between the pacific and the north atlantic decadal fluctuations mediated by the atmosphere the modeling surgery indicates that the pacific climate although not a necessary precondition can impact the north atlantic climate variability substantially

simulation of north atlantic decadal multidecadal winter sst anomalies driven by basin scale atmospheric circulation anomalies the north atlantic winter sea surface temperature anomaly tsa response to anomalous surface atmospheric circulation anomalies that vary over decadal and short term inter decadal periods is simulated for 1950 through 1992 anomalous ocean variability is driven by adding monthly coads derived anomalous fields of vector wind stress and wind speed to the climatological annual cycle forcing a simple model is derived relating winter tsa to the integrated atmospheric forcing present earlier in time that is responsible for its existence the basinscale structure of forced winter tsa patterns depends on the structure of the atmospheric forcing along with regional differences in the dominant mixed layer processes that generate tsa for example when the atmospheric subtropical high and subpolar low pressure systems are simultaneously strong enhanced flow around and baroclinic adjustments within the subtropical gyre results in anomalously warm water in the gulf stream region off the u s east coast at the same time however the open ocean generally cools because the westerlies and trades are anomalously strong by analyzing tsa variability not driven by the atmosphere an anomalously cold decade is identified characterized by rapid onset and termination that both occur within one year the onset during 1968 coincides with the appearance of the great salinity anomaly while the termination during 1977 coincides with an abrupt northern hemisphere climate shift that is particularly evident in the pacific

winter to winter recurrence of sea surface temperature salinity and mixed layer depth anomalies abstract the mean seasonal cycle of mixed layer depth mld in the extratropical oceans has the potential to influence temperature salinity and mixed layer depth anomalies from one winter to the next temperature and salinity anomalies that form at the surface and spread throughout the deep winter mixed layer are sequestered beneath the mixed layer when it shoals in spring and are then re entrained into the surface layer in the subsequent fall and winter here we document this re emergence mechanism in the north pacific ocean using observed ssts subsurface temperature fields from a data assimilation system and coupled atmosphere ocean model simulations observations indicate that the dominant large scale sst anomaly pattern that forms in the north pacific during winter recurs in the following winter the model simulation with mixed layer ocean physics reproduced the winter to winter recurrence while model simulations with observed ssts specified in the tropical pacific and a 50 m slab in the north pacific did not this difference between the model results indicates that the winter to winter sst correlations are the result of the re emergence mechanism and not of similar atmospheric forcing of the ocean in consecutive winters the model experiments also indicate that sst anomalies in the tropical pacific associated with el nino are not essential for re emergence to occur the recurrence of observed sst and simulated sst and sss anomalies are found in several regions in the central north pacific and are quite strong in the northern 50 n part of the basin the winter to winter autocorrelation of sss anomalies exceed those of sst since only the latter are strongly damped by surface fluxes the re emergence mechanism also has a modest influence on mld through changes in the vertical stratification in the seasonal thermocline

timing and extent of allerod and younger dryas age ca 12 500 10 000 14c yr b p oscillations of the cordilleran ice sheet in the fraser lowland western north america the use of shaded digital topographic models to visualizes suites of topographic features stratigraphy and field mapping reveals newly recognized multiple moraines associated with oscillations of the remnants of the cordilleran ice sheet in the fraser lowland along the western washington british columbia border morphologic features show the extent of ice represented by sumas drift ca 11 600 10 000 14c yr b p following ca 3000 yr of retreat from the glacial maximum fraser glaciation positions 80 km south of seattle and in the strait of juan de fuca the paleogeography of the ice margin and timing of ice retreat during the sumas stade is reconstructed and bracketed by 70 radiocarbon dates 24 on marine shells 46 on wood and peat which are secured by morphologic and stratigraphic evidence four topographically distinct phases of the sumas deglaciation model are suggested phase si 11 600 11 400 14c yr b p outermost drift scattered remnants of ice contact deposits phase sii 11 600 11 400 14c yr b p glacier readvance building prominent moraine followed by glacier retreat phase siii 10 980 10 250 14c yr b p glacier readvance building of multiple moraines followed by glacier retreat phase siv 10 250 10 000 14c yr b p glacier readvance building of inner moraine followed by glacier retreat

western boundary currents and frontal air sea interaction gulf stream and kuroshio extension abstract in the northern hemisphere midlatitude western boundary current wbc systems there is a complex interaction between dynamics and thermodynamics and between atmosphere and ocean their potential contribution to the climate system motivated major parallel field programs in both the north pacific kuroshio extension system study kess and the north atlantic climate variability and predictability clivar mode water dynamics experiment climode and preliminary observations and analyses from these programs highlight that complexity the gulf stream gs in the north atlantic and the kuroshio extension ke in the north pacific have broad similarities as subtropical gyre wbcs but they also have significant differences which affect the regional air sea exchange processes and their larger scale interactions the 15 yr satellite altimeter data record which provides a rich source of information is combined here with the longer historical record from in situ data to describe and compare the curr

wintertime atmospheric response to north atlantic ocean circulation variability in a climate model abstractmaximum covariance analysis of a preindustrial control simulation of the ncar community climate system model version 4 ccsm4 shows that a barotropic signal in winter broadly resembling a negative phase of the north atlantic oscillation nao follows an intensification of the atlantic meridional overturning circulation amoc by about 7 yr the delay is due to the cyclonic propagation along the north atlantic current nac and the subpolar gyre of a sst warming linked to a northward shift and intensification of the nac together with an increasing sst cooling linked to increasing southward advection of subpolar water along the western boundary and a southward shift of the gulf stream gs these changes result in a meridional sst dipole which follows the amoc intensification after 6 or 7 yr the sst changes were initiated by the strengthening of the western subpolar gyre and by bottom torque at the crossover of the deep branches of the amoc with the nac on the western flank of the mid atlantic

re emerging ocean temperature anomalies in late 2010 associated with a repeat negative nao northern europe was influenced by consecutive episodes of extreme winter weather at the start and end of the 2010 calendar year a tripole pattern in north atlantic sea surface temperature anomalies sstas associated with an exceptionally negative phase of the north atlantic oscillation nao characterized both winter periods this pattern was largely absent at the surface during the 2010 summer season however equivalent sub surface temperature anomalies were preserved within the seasonal thermocline throughout the year here we present evidence for the re emergence of late winter 2009 10 sstas during the following early winter season of 2010 11 the observed re emergence contributes toward the winter to winter persistence of the anomalous tripole pattern considering the active influence of the oceans upon leading modes of atmospheric circulation over seasonal timescales associated with the memory of large scale sea surface temperature anomaly patterns the re emergence of remnant temperature anomalies may have also contributed toward the persistence of a negative winter nao and the recurrence of extreme wintry conditions over the initial 2010 11 winter season

the reemergence of sst anomalies in the north pacific ocean abstract sea surface temperature sst data and two different upper ocean temperature analyses are used to study the winter to winter recurrence of sst anomalies in the north pacific ocean the ssts recur when temperature anomalies that form in the deep ocean mixed layer in late winter early spring are isolated from the atmosphere in the summer seasonal thermocline and then reemerge at the surface when the mixed layer deepens during the following fall winter this reemergence mechanism is evaluated over the basin by correlating the time series of the leading pattern of ocean temperature anomalies in the summer seasonal thermocline 60 85 m in august september with sst anomalies over the course of the year the results indicate that the dominant large scale sst anomaly pattern that forms in the north pacific during late winter with anomalies of one sign in the central pacific and the opposite sign along the coast of north america is sequestered in the seasonal thermocline in summer and returns to the

advection and dissipation rates in the upper ocean mixed layer heat anomaly budget over the north atlantic in summer 1 processes contributing to the heat anomaly budget of the upper ocean mixed layer are examined over the north atlantic in summer season on the basis of the inversion of the sea temperature profiles the net advection velocity the subgrid heat diffusivity and the surface heat flux feedback are estimated two inversion strategies are pursued with and without the explicit parameterization of the entrainment heat flux into the upper mixed layer the regression estimator is employed for the inversion the data involved are the compilation of the comprehensive ocean atmosphere data set sea surface temperature sst and world ocean database 2001 temperature profiles over a 2 latitude 3 longitude grid for sequential 10 day intervals in june september during 1965 2000 the inversion is constrained by the autocorrelation of the national centers for environmental prediction net air sea heat flux the regression estimator allows for prediction of up to 60 70 of the sst anomaly value 10 days in advance by using the regressions on the sst anomalies lagged by two time steps the sst anomaly transport over the north atlantic agrees broadly with the known features of the surface circulation although the quantitative details of the sst anomaly propagation obtained in this inversion have not previously been available the heat anomaly that originates in the gulf stream region near the western boundary either moves northeastward with speed of up to 0 12 m s 1 downstream of the north atlantic current and the north atlantic drift current or it turns southeastward and then propagates southwestward along the broad subtropical recirculation in the subtropics the westward propagation is seemingly reinforced by the effects of the planetary waves the air sea feedback is negative with the feedback factor having the average value of 39 w m 2 k 1 with substantial variations throughout the north atlantic the entrainment rate is generally about 0 15 m d 1 relatively rapid deepening of the mixed layer by more than 2 10 6 m s 1 occurs near the gulf stream

north pacific subtropical mode water volume decrease in 2006 09 estimated from argo observations influence of surface formation and basin scale oceanic variability abstractanalysis of argo temperature and salinity profiles gridded at 0 5 0 5 resolution for 2005 12 shows a strong north pacific subtropical mode water npstmw volume and density decrease during 2006 09 in this time period upper ocean temperature stratification and potential vorticity pv all increased within the region in and around the npstmw low pv pool contributing to the npstmw volume decrease in two ways i the volume of water satisfying the low pv constraint that is part of the mode water definition decreased and ii some water that was initially in the npstmw density range 25 0 25 5 kg m 3 was transformed into lighter water both changes in density and in pv in the npstmw region were a manifestation of basinwide changes a positive pv anomaly started to propagate westward from the central pacific in 2005 followed by a negative density anomaly in 2007 which caused a dramatic npstmw volume and density decrease a walin estimate of surface formation in the npstmw density ran

subannual to interannual variabilities of sst in the north atlantic ocean abstractbased on observational data this work examines the multi time scale feature of the sea surface temperature sst variability averaged in the whole north atlantic ocean to be referred to a

a linear inverse model of tropical and south pacific seasonal predictability a multivariate linear inverse model lim is developed to demonstrate the mechanisms and seasonal predictability of the dominant modes of variability from the tropical and south pacific oceans we construct a lim whose covariance matrix is a combination of principal components derived from tropical and extratropical sea surface temperature and south pacific ocean vertically averaged temperature anomalies eigen decomposition of the linear deterministic system yields stationary and or propagating eigenmodes of which the least damped modes resemble el nino southern oscillation enso and the south pacific decadal oscillation spdo we show that although the oscillatory periods of enso and spdo are distinct they have very close damping time scales indicating that the predictive skill of the surface enso and spdo is comparable the most damped noise modes occur in the midlatitude south pacific ocean reflecting atmospheric eastward propagating rossby wave train variability we argue that these ocean wave trains occur due to the high frequency atmospheric variability of the pacific south american pattern imprinting onto the surface ocean the enso spring predictability barrier is apparent in lim predictions initialized in march may mam but displays a significant correlation skill of up to 3 months for the spdo the predictability barrier tends to appear in june september jas indicating remote but delayed influences from the tropics we demonstrate that subsurface processes in the south pacific ocean are the main source of decadal variability and further that by characterizing the upper ocean temperature contribution in the lim the seasonal predictability of both enso and the spdo variability is increased

precessional forced extratropical north pacific mode and associated atmospheric dynamics using transient accelerated simulations of the community climate system model version 3 and an earth system model of intermediate complexity as well as equilibrium experiments of the community earth system model we identified a response of the extratropical air ocean coupled system to the precessional insolation changes at orbital timescales and named this extratropical response pattern as the north pacific mode npm corresponding to the increased decreased boreal winter summer insolation at 22 ka relative to 10 8 ka the npm is characterized by a western warm eastern cold seesaw pattern of sea surface temperature sst over the extratropical north pacific from november to april a weakened winter aleutian low and an anomalous anticyclonic circulation throughout the troposphere this feature forms a barotropic warm ridge response of tropospheric temperature and geopotential height to the precessional insolation at the surface rainfall increases over east asia and the northwest pacific which indicates a weakened east asian winter monsoon while drier conditions appear over the northeast pacific and the western coasts of north america associated with a negative phase of npm is a weaker warming over the equatorial pacific during winter the increased winter insolation at precessional band not only induces the in phase sst warming over the northwest pacific and the tropical pacific but also explains those extratropical atmospheric changes associated with npm the latter might be associated with the warm sst induced tropospheric downstream ridge response through transient eddy activities besides the vital role of air ocean interactions the decreased summer insolation is also essential to the zonal sst seesaw of npm at precessional band

decadal buoyancy forcing in a simple model of the subtropical gyre the decadal response of the ventilated thermocline to surface buoyancy forcing is investigated using simplified mixed layer thermodynamics and two layer planetary geostrophic dynamics the model is forced by a stationary ekman pumping and a fluctuating sea surface density while the associated surface buoyancy flux is diagnosed from the buoyancy budget of ventilated columns the decadal forcing is represented as a slow modulation of the seasonal cycle rather than a slow periodic forcing as in liu and pedlosky it is found that the amplitude and the degree of nonlinearity of the interior response depend on the anomalies of the yearly averaged surface buoyancy flux but that omitting the seasonal cycle leads to an overestimation of the thermocline variability by a factor of 2 at periods longer than 10 years the interior response becomes linear and frequency independent so that in the presence of stochastic buoyancy forcing the spectrum of potential vorticity or interface displacement is white at low frequency and red at high frequency a statistical signature of the buoyancy forcing is the asymmetric shape of the cross covariance function between sea surface density and interface displacement anomalies in lead and lag conditions

the persistence of winter sea surface temperature in the north atlantic abstract the impact of the seasonal variations of the mixed layer depth on the persistence of sea surface temperature sst anomalies is studied in the north atlantic using observations a significant recurrence of winter sst anomalies during the following winter occurs in most of the basin but not in the subtropical area of strong subduction when taking reemergence into account the e folding timescale of winter sst anomalies generally exceeds 1 yr and is about 16 months for the dominant sst anomaly tripole the influence of advection by the mean oceanic currents is investigated by allowing for a displacement of the maximum recurrent correlation and alternatively by considering the sst anomaly evolution along realistic mean displacement paths taking into account the nonlocality of the reemergence generally increases the wintertime persistence most notably in the northern part of the domain the passive response of the mixed layer to the atmospheric forcing thus has a red spectrum down to near dec

dynamics of sea surface temperature anomalies in the southern ocean diagnosed from a 2d mixed layer model we analyze the processes responsible for the generation and evolution of sea surface temperature anomalies observed in the southern ocean during a decade based on a 2d diagnostic mixed layer model in which geostrophic advection is prescribed from altimetry anomalous air sea heat flux is the dominant term of the heat budget over most of the domain while anomalous ekman heat fluxes account for 20 40 of the variance in the latitude band 40 60 s in the acc pathway lateral fluxes of heat associated with anomalous geostrophic currents are a major contributor dominating downstream of several topographic features reflecting the influence of eddies and frontal migrations a significant fraction of the variability of large scale sst anomalies is correlated with either enso or the sam each mode contributing roughly equally the relation between the heat budget terms and these climate modes is investigated showing in particular that anomalous ekman and air sea heat fluxes have a co operating effect with regional exceptions hence the large sst response associated with each mode it is further shown that enso or sam locked anomalous geostrophic currents generate substantial heat fluxes in all three basins with magnitude comparable with that of atmospheric forcings for enso and smaller for the sam except for limited areas enso locked forcings generate sst anomalies along the acc pathway and advection by mean flows is found to be a non negligible contribution to the heat budget exhibiting a wavenumber two zonal structure characteristic of the antarctic circumpolar wave by contrast sam related forcings are predominantly zonally uniform along the acc hence smaller zonal sst gradients and a lesser role of mean advection except in the southwest atlantic while modeled sst anomalies are significantly correlated with observations over most of the southern ocean the analysis of the data model discrepancies suggests that vertical ocean physics may play a significant role in the nonseasonal heat budget especially in some key regions for mode water formation

seasonality of decadal sea surface temperature anomalies in the northwestern pacific abstract the seasonality of the decadal sea surface temperature sst anomalies and the related physical processes in the northwestern pacific were investigated using a three dimensional bulk mixed layer model in the kuroshio oyashio extension koe region the strongest decadal sst anomaly was observed during december february while that of the central north pacific occurred during february april from an examination of the seasonal heat budget of the ocean mixed layer it was revealed that the seasonal scale enhancement of the decadal sst anomaly in the koe region was controlled by horizontal ekman temperature transport in early winter and by vertical entrainment in autumn the temperature transport by the geostrophic current made only a slight contribution to the seasonal variation of the decadal sst anomaly despite controlling the upper ocean thermal conditions on decadal time scales through the slow rossby wave adjustment to the wind stress curl when averaging over the entire koe region the cont

feedbacks of sea surface temperature to wintertime storm tracks in the north atlantic abstractin this study the lagged maximum covariance analysis is performed on winter storm track anomalies represented by the meridional heat flux by synoptic scale 2 8 days transient eddies and sea surface temperature sst anomalies in the north atlantic which are both derived from reanalysis datasets spanning the twentieth century the analysis shows significant seasonal and interannual coupling between storm track and sst variations on seasonal time scales it is found that sst anomalies in the preceding early winter november december which are expected to change the lower tropospheric baroclinicity can significantly influence storm tracks in early spring march that is an intensification and slight northward shift of storm tracks in response to a midlatitude sst dipole with a cold pole centered to the southeast of newfoundland and a warm pole in the western subtropical atlantic this storm track response pattern is similar to the storm track forcing pattern in early spring which resembl

mg ca ratios in coralline algae record northwest atlantic temperature variations and north atlantic oscillation relationships climate variability in the north atlantic has been linked in part to the north atlantic oscillation nao the nao influences marine ecosystems in the northwestern atlantic and transport variability of the cold labrador current understanding historic patterns of nao variability requires long term and high resolution climate records that are not available from instrumental data here we present the first century scale proxy record of sea surface temperature sst variability from the newfoundland shelf a region from which other annual resolution shallow marine proxies are unavailable the 116 year record was obtained from three sites along the eastern newfoundland shelf using laser ablation inductively coupled mass spectrometry determined mg ca ratios in the crustose coralline alga clathromorphum compactum the alga is characterized by a high mg calcite skeleton exhibiting annual growth increments and a century scale lifespan results indicate positive correlations between interannual variations in mg ca ratios and both station based and gridded instrumental sst in addition the record shows high spatial correlations to sst across the newfoundland shelf and the gulf of st lawrence before 1950 the mg ca proxy record reveals significant departures from gridded temperature records while the newfoundland shelf is generally considered a region of negative correlations to the nao the algal time series as well as a recent modeling study suggest a variable negative relationship with the nao which is strongest after 1960 and before the mid 1930s

extratropical forcing of tropical atlantic variability during boreal summer and fall abstractthe connection between midlatitude atlantic sea surface temperature sst anomalies and tropical sst variations during boreal summer and fall are investigated using a coupled general circulation model gcm this research follows on an observational study that finds that using linear inverse modeling lim predictions of boreal summer tropical atlantic meridional mode amm variations can be made with skill exceeding persistence with lead times of about one year the lim framework identified extratropical atlantic sst anomalies as important precursors to the amm variations the authors have corroborated this finding using a general circulation model coupled to a slab ocean which represents a completely different physical basis from the lim initializing the gcm with the lim derived optimal sst anomaly in november results in a steady equatorward propagation of sst anomalies into the subtropics during the following boreal spring thereafter the gcm suggests that two possible feedbacks propagate

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

mountain erosion over 10 yr 10 k y and 10 m y time scales we used cosmogenic 10 be to measure erosion rates over 10 k y time scales at 32 idaho mountain catchments ranging from small experimental watersheds 0 2 km 2 t o large river basins 35 000 km 2 these long term sediment yields are on average 17 times higher than stream sediment fluxes measured over 10 84 yr but are consistent with 10 m y erosion rates measured by apatite fission tracks our results imply that conventional sediment yield measurements even those made over decades can greatly underestimate long term average rates of sediment delivery and thus overestimate the life spans of engineered reservoirs our observations also suggest that sediment delivery from mountainous terrain is extremely episodic sporadically subjecting mountain stream ecosystems to extensive disturbance

sediment yield from disturbed earth systems changes of sediment yield rates through time reflect evolutionary changes within a landscape when a drainage basin is perturbed significantly by base level climatic or tectonic change sediment yields increase dramatically but with no further disturbance they decline rapidly these sediment yield changes have been documented at all scales from small experimental studies to incised channels to the colorado river basin and to the himalaya mountains thus the shape of the sediment yield curve can be used to estimate future sediment yields and to interpret past tectonic events

decadal variability of hydrography in the upper northern north atlantic in 1948 1990 we investigate the variability of the north atlantic subarctic gyre in recent decades from time series of station temperature and salinity decadal variability stronger at the surface is identified which exhibits vertical coherence over a layer deeper than the late winter mixed layer in the northwestern atlantic it corresponds to the layer with a component of water from the arctic ocean or from the canadian arctic the spatial coherence of the signal is investigated an empirical orthogonal function decomposition of lagged time series indicates that a single pattern explains 70 of the variance in upper ocean salt content corresponding to a propagating signal from the west to the northeast in the subarctic gyre the most likely interpretation is that the salinity signal originates in the slope currents of the labrador sea and is diffused advected eastward of the grand banks over the near western atlantic in the northwestern atlantic temperature fluctuations are strongly correlated to salinity fluctuations and are aligned along the average t s characteristics this signal suggests large variations in the outflow of fresh cold water in the slope current and is strongly correlated with ice cover a basin scale atmospheric circulation of weakened westerlies at 55 n weaker northwesterlies west of greenland and weaker southerlies over the central and eastern north atlantic is associated with the high salinity and warm water phase of the first principal component this circulation pattern leads fluctuations in the northeast atlantic and lags those in the northwestern part of the basin the wind indices also suggest that the fluctuations of the fresh water outflow occur during intervals of anomalously northerly winds either east of greenland 1965 1968 1969 or off the canadian archipelago 1983 1984

observational evidence of reemergence in the extratropical southern hemisphere observations of subsurface temperatures are used to examine the winter to winter reemergence of sea surface temperature sst anomalies in the extratropical south pacific ocean reemergence is the mechanism through which sst anomalies formed in the late winter are sequestered beneath the relatively shallow summer mixed layer and then reentrained into the deepening mixed layer during the following autumn winter although several studies have extensively examined reemergence in the northern hemisphere nh this is the first study to use observations of subsurface temperatures to document reemergence in the extratropical southern hemisphere sh the sh subsurface data reveal a pronounced reemergence signal in the western extratropical south pacific in this region surface thermal anomalies formed during late sh winter are observed to persist below the summertime mixed layer and reemerge at the surface during the followingearly winter months as such sst anomalies formed during late winter are strongly correlated with sst anomalies during the following early winter but are not significantly correlated with sst anomalies during the intervening summer months the results based on subsurface data are robust to small changes in the period of analysis and are qualitatively similar to existing evidence of reemergence in the nh analyses of independent sst data reveal that reemergence is widespread in the western extratropical south pacific basin but is less discernible in sst anomalies over the eastern part of the basin

winter to winter recurrence of sea surface temperature anomalies in the northern hemisphere the spatiotemporal characteristics of the winter to winter recurrence wwr of sea surface temperature anomalies ssta in the northern hemisphere nh are comprehensively studied through lag correlation analysis on this basis the relationships between the ssta wwr and the wwr of the atmospheric circu lation anomalies el nino southern oscillation enso and ssta interdecadal variability are also in vestigated results showthat the ssta wwr occurs over most parts of the north pacific and atlantic oceans but the spatiotemporaldistributionsofthesstawwraredistinctlydifferentinthesetwooceans analysesindicate that the spatiotemporal distribution of the ssta wwr in the north atlantic ocean is consistent with the spatial distribution of the seasonal cycle of its mixed layer depth mld whereas that in the north pacific ocean particularly the recurrence timing cannot be fully explained by the change in the mld between winterandsummerin someregions inaddition theatmospheric circulationanomaliesalsoexhibitthewwr at the mid high latitude of the nh which is mainly located in eastern asia the central north pacific and the north atlantic the sea level pressure anomalies slpa in the central north pacific are essential for the occurrenceofthesstawwrinthisregion moreover thestrongestpositivecorrelationoccurswhentheslpa lead ssta in the central northpacific by 1 month whichsuggeststhat the atmospheric forcingon the ocean may play a dominant role in this region therefore the reemergence mechanism is not the only process influ encing the ssta wwr and the wwr of the atmospheric circulation anomalies may be one of the causes of the ssta wwr in the central north pacific finally the occurrence of the ssta wwr in the nh is closely related to ssta interdecadal variability in the nh but it is linearly independent of enso

interannual variations in upper ocean heat content and heat transport convergence in the western north atlantic subsurface temperature data in the western north atlantic ocean are analyzed to study the variations in the heat content above a fixed isotherm and contributions from surface heat fluxes and oceanic processes the study region is chosen based on the data density its northern boundary shifts with the gulf stream position and its southern boundary shifts to contain constant volume the temperature profiles are objectively mapped to a uniform grid 0 5 latitude and longitude 10 m in depth and 3 months in time the interannual variations in upper ocean heat content show good agreement with the changes in the sea surface height from the ocean topography experiment topex poseidon altimeter both indicate positive anomalies in 1994 and 1998 99 and negative anomalies in 1996 97 the interannual variations in surface heat fluxes cannot explain the changes in upper ocean heat storage rate on the contrary a positive anomaly in heat released to the atmosphere corresponds to a positive upper ocean heat content anomaly the oceanic heat transport mainly owing to the geostrophic advection controls the interannual variations in heat storage rate which suggests that geostrophic advection plays an important role in the air sea heat exchange the 18 c isotherm depth and layer thickness also show good correspondence to the upper ocean heat content a deep and thin 18 c layer corresponds to a positive heat content anomaly the oceanic transport in each isotherm layer shows an annual cycle converging heat in winter and diverging in summer in a warm layer it also shows interannual variations with the largest heat convergence occurring in even warmer layers during the period of large ocean to atmosphere flux

an intimate coupling of ocean atmospheric interaction over the extratropical north atlantic and pacific the inter basin teleconnection between the north atlantic and the north pacific ocean atmosphere interaction is studied using a coupled ocean atmosphere general circulation model in the model an idealized oceanic temperature anomaly is initiated over the kuroshio and the gulf stream extension region to track the coupled evolution of ocean and atmosphere interaction respectively the experiments explicitly demonstrate that both the north pacific and the north atlantic ocean atmosphere interactions are intimately coupled through an inter basin atmospheric teleconnection this fast inter basin communication can transmit oceanic variability between the north atlantic and the north pacific through local ocean to atmosphere feedbacks the leading mode of the extratropical atmospheric internal variability plays a dominant role in shaping the hemispheric scale response forced by oceanic variability over the north atlantic and pacific modeling results also suggest that a century two centuries long observations are necessary for the detection of pacific response to atlantic forcings atlantic response to pacific forcing

quantitative analysis of debris torrent hazards for design of remedial measures debris torrents which are rapid flows of soil and organic debris down steep mountain channels are a major natural hazard in many parts of british columbia a series of recent occurrences along the

reemergence areas of winter sea surface temperature anomalies in the world s oceans 1 using datasets of sea surface temperature sst surface heat flux upper ocean thermal data and climatological temperature and salinity profiles we try to detect reemergence areas of winter sst anomalies in the world s oceans and describe characteristics of these areas in terms of mixed layer depth mld annual mean heat flux and properties of waters formed in winter mixed layer eventually seven reemergence areas are found four in the northern hemisphere and three in the southern hemisphere all areas have a large seasonal variation of mld and are the regions where annual mean heat fluxes are relatively small except for two regions in the northern hemisphere in the viewpoint of water properties it is found that these areas correspond to the mode water formation regions subtropical mode waters of the indian ocean south pacific south atlantic north pacific and north atlantic and north pacific central and north atlantic subpolar mode waters

on the reemergence of north atlantic sst anomalies abstract the reemergence mechanism whereby temperature anomalies extending over the deep winter mixed layer are stored beneath the surface in summer and are reentrained into the mixed layer when it deepens again in the following autumn and winter is studied in the north atlantic using approximately 40 years of surface and subsurface data reemergence is found to be robust in the sargasso sea and the northeast atlantic regions where i the mixed layer is much deeper in winter than in summer ii currents are relatively weak and iii temperature anomalies are coherent over broad areas the two leading empirical orthogonal functions of north atlantic sst anomalies also exhibit strong reemergence signatures a novel application of empirical orthogonal function analysis to temperature anomalies in the time depth plane which also incorporates information from all grid points is shown to be an efficient and useful approach for detecting reemergence without dependence on specific spatial patterns or prio

landslide inventory in a rugged forested watershed a comparison between air photo and field survey data abstract landslide inventories are routinely compiled by means of aerial photo interpretation api when examining photo pairs the forest canopy notably in old growth forest hides a population of not visible landslides in the present study we attempt to estimate how important is the contribution of landslides not detectable from aerial photographs to the global mass of sediment production from mass failures on forested terrain of the capilano basin coastal british columbia api was coupled with intensive fieldwork for identification and measurement of all landslides a 30 year framework was adopted we show that not visible landslides can represent up to 85 of the total number of failures and account for 30 of the volume of debris mobilised such percentages display high sub basin variability with rates of sediment production varying by one order of magnitude between two sub basins of the study area this is explained qualitatively by gis based analysis of slope frequency distributions drainage density and spatial distribution of surficial materials such observations find further support in the definitions of transport limited and supply limited basins as a practical consideration to land managers we envisage that supplementary fieldwork for landslide identification is mandatory in transport limited systems only fieldwork has demonstrated that gully related failures have a greater importance than one could expect from api

the effect of milankovitch variations in insolation on equatorial seasonality although the sun crosses the equator 2 times per year at the equinoxes at times in the past the equatorial insolation has had only one maximum and one minimum throughout the seasonal cycle because of milankovitch orbital variations here a state of the art coupled atmosphere ocean general circulation model is used to study the effect of such insolation forcing on equatorial surface properties including air and sea temperature salinity winds and currents it is shown that the equatorial seasonality is altered according to the insolation with for example either maximum sea surface temperature sst close to the vernal equinox and minimum sst close to the autumnal equinox or vice versa the results may have important implications for understanding tropical climate as well as for the interpretation of proxy data collected from equatorial regions

year to year reoutcropping of eighteen degree water in an eddy resolving ocean simulation abstractwinter outcropping of the eighteen degree water edw and its subsequent dispersion are studied using a eddy resolving simulation of the family of linked atlantic modeling experiments flame outcropped edw columns in the model simulations are detected in each winter from 1990 to 1999 and particles are deployed in the center of each outcropped edw column subsequently the trajectories of these particles are calculated for the following 5 yr the particles slowly spread away from the outcropping region into the nonoutcropping subducted edw region south of 30 n and eventually to the non edw region in the greater subtropical gyre approximately 30 of the particles are found in non edw waters 1 yr after deployment after 5 yr only 25 of the particles are found within edw the reoutcropping time is defined as the number of years between when a particle is originally deployed in an outcropping edw column and when that particle is next found in an outcropping edw column of the particles 66 ar

remote reemergence areas of winter sea surface temperature anomalies in the north pacific 1 taking account of water movement we detect pairs of formation and reemergence areas of winter sea surface temperature sst anomalies in the north pacific by analyzing various kinds of data sets two pairs of formation and reemergence areas are detected one pair is located in the northern subtropical gyre and water properties in both the formation and reemergence areas well correspond to those of north pacific central mode water npcmw another pair is found in the western to central part of the subtropical gyre the formation area corresponds well to that of north pacific subtropical water npstmw but the reemergence area is remote from the formation area examinations on upper ocean current field trace of temperature anomalies in the subsurface and change of water properties from the formation area to the reemergence area clearly indicate that waters with winter sst anomalies move from the formation area to the reemergence area in a year

summertime evolution of decadal sea surface temperature anomalies in the midlatitude north pacific abstract to clarify the summertime evolution of decadal sea surface temperature sst anomalies and related physical processes in the midlatitudes of the north pacific numerical solutions of a three dimensional bulk mixed layer model are analyzed focusing on the contribution of the net shortwave radiative forcing at the sea surface a quantitative heat budget analysis for the ocean mixed layer relating to late 1980s decadal sst change reveals that the decadal sst anomalies decay from late spring to early summer over the entire midlatitudes of the north pacific this quasi seasonal decay of the decadal sst anomalies is controlled by an anomalous local thermal damping i e anomalous surface heat fluxes from midsummer to early autumn the anomalous net shortwave radiation flux associated with a meridional shift of the storm track acts to induce strong seasonal damping of the decadal sst anomaly in the northern kuroshio oyashio extension region in contrast in the north of the subtropical frontal region

on the north atlantic ocean heat content change between 1955 70 and 1980 95 theupper oceanheatcontentofthenorthatlantichasundergonesignificantchangesoverthelast50years but the underlying physical mechanisms are not yet well understood in the present study the authors examine the north atlantic ocean heat content change in the upper 700 m between the 1955 70 and 1980 95 periods consistent with previous studies the large scale pattern consists of warming of the tropics and subtropics and cooling of the subpolar ocean however this study finds that the most significant heat content change in the north atlanticduring these two time periods is the warmingofthe gulfstream region numerical experiments strongly suggest that this warming in the gulfstream region is largely driven by changes of the large scale wind forcing furthermore the increased ocean heat content inthe gulfstream regionappears tofeedbackon tothe atmosphere resulting in warmer surface air temperature and enhanced precipitation there

reconnaissance sediment budgets for lynn valley british columbia holocene and contemporary time scales volumes of erosional and depositional landforms were estimated by reconnaissance methods in a steep forested drainage basin in the coast mountains british columbia to examine what insight might be gained into the sediment budget in the absence of direct measurements of sediment transfer processes sediment transfers in postglacial and contemporary time were inferred on hillslopes from hillslopes to stream channels and within stream channels data were collected by aerial photographic analysis and field observation postglacial sediment sources are major gullies created by debris slides and flows failures in glaciolacustrine terraces and stream channel degradation depositional landforms consist of talus slopes and colluvial and alluvial fans contemporary sediment sources include debris slides and flows in established gullies and minor processes on hillslopes debris slide and debris flow volumes were calculated and other processes were estimated from regional values erosion rate averaged over postglacial time is 276 t km 2 a 1 0 15 mm a 1 surface lowering with gullies and stream channel degradation contributing 170 and 82 t km 2 a 1 respectively a terminal alluvial fan provides an independent check of the results in contemporary time erosion rates are calculated to be 350 t km 2 a 1 with debris flows and slides contributing nearly all of this sediment the contemporary rate is probably perturbed by recent land use history mass movement processes appear to be the dominant mechanism of sediment transfer and contributions from pleistocene valley deposits have declined significantly during holocene time resume les volumes de terrain erodes et deposes ont ete estimes par des methodes de reconnaissance dans un bassin de drainage boise a pentes abruptes des montagnes cotieres de la colombie britannique afin d etudier quelles connaissances sur le budget sedimentaire pourraient etre acquises en l absence de mesures directes du processus de transfert de sediments les transferts de sediments a l epoque post glaciaire et contemporaine ont ete inferes sur les flancs des cotes des flancs des cotes vers les chenaux des rivieres et dans les chenaux des rivieres les donnees proviennent de l analyse de photographies aeriennes et d observations sur le terrain les sources de sediments post glaciaires sont des ravines creees par des glissements et des coulees de debris des effondrements de terrasses glacio lacustres et la degradation de chenaux les formes de terrain creees par deposition comprennent des tabliers d eboulis et des deltas colluviaux et alluvionnaires les sources contemporaines de sediments comprennent des glissements et des coulees de debris dans des ravines etablies et des processus mineurs sur des pentes les volumes des glissements et des coulees de debris ont ete calcules et d autres processus ont ete evalues a partir de valeurs regionales la moyenne du taux d erosion pour la periode post glaciaire est de 276 tonnes km 2 a 1 abaissement de la surface de 0 15 mm a les ravines et la degradation des chenaux des ruisseaux contribuant respectivement 170 et 82 tonnes km 2 a 1 un delta alluvionnaire terminal permet une verification independante des resultats a l epoque contemporaine les taux d erosion sont calcules comme etant 350 tonnes km 2 a 1 et les glissements et des coulees de debris y contribueraient pour la presque totalite le taux contemporain est probablement perturbe par l utilisation recente du terrain les processus de mouvements de masse semblent etre le mecanisme dominant de transfert de sediments et les contributions provenant des depositions dans les vallees au pleistocene ont diminue de facon significative durant l holocene traduit par la redaction campbell and church 713

southern ocean mixed layer depth from argo float profiles 1 argo float profiles of temperature salinity and pressure are used to derive the mixed layer depth mld in the southern ocean mld is determined from individual profiles using both potential density and potential temperature criteria and a monthly climatology is derived from individual mlds using an objective mapping method quantitative data are available in the auxiliary material the spatial structures of mlds are similar in each month with deep mixed layers within and just north of the antarctic circumpolar current acc in the pacific and indian oceans the deepest mixed layers are found from june to october and are located just north of the acc where antarctic intermediate water aaiw and subantarctic mode water samw are formed examination of individual mlds indicates that deep mixed layers mld 400 m from both the density and temperature criteria are concentrated in a narrow surface density band which is within the density range of samw the surface salinity for these deep mixed layers associated with the samw formation are slightly fresher compared to historical estimates differences in air sea heat exchanges wind stress and wind stress curl in the pacific and indian oceans suggest that the mode water formation in each ocean basin may be preconditioned by different processes wind mixing and ekman transport of cold water from the south may assist the samw formation in the indian ocean in the eastern pacific the formation of mode water is potentially preconditioned by the relative strong cooling and weak stratification from upwelling

a mechanism for the recurrence of wintertime midlatitude sst anomalies abstract in the early 1970s namias and born speculated that ocean temperature anomalies created over the deep mixed layer in winter could be preserved in the summer thermocline and reappear at the surface in the following fall or winter this hypothesis is examined using upper ocean temperature observations and simulations with a mixed layer model the data were collected at six ocean weather stations in the north atlantic and north pacific concurrent and lead lag correlations are used to investigate temperature variations associated with the seasonal cycle in both the observations and the model simulations concurrent correlations between the surface and subsurface temperature anomalies in both the data and the model indicate that the penetration of temperature anomalies into the ocean is closely tied to the seasonal cycle in mixed layer depth high correlations extend to relatively deep shallow depths in winter summer lead lag correlations in both the data and the model at some of the stations

spiciness anomalies in the upper south indian ocean abstractthis study investigates an isopycnal temperature salinity t s or spiciness anomaly in the upper south indian ocean for the period from 2004 to 2015 using observations and reanalyses spic

ocean gyre circulation changes associated with the north atlantic oscillation abstract observational evidence is presented for interannual to interdecadal variability in the intensity of the north atlantic gyre circulation related to the atmospheric north atlantic oscillation nao patterns a two point baroclinic pressure difference between the subtropical and subpolar gyre centers an oceanic analogue to the much used sea level pressure slp based atmospheric nao indices is constructed from time series of potential energy anomaly pea derived from hydrographic measurements in the labrador basin and at station s near bermuda representing the upper 2000 db eastward baroclinic mass transport between the two centers the transport index indicates a gulf stream and north atlantic current that gradually weakened during the low nao period of the 1960s and then intensified in the subsequent 25 years of persistently high nao to a record peak in the 1990s the peak to peak amplitude difference was 15 20 megatons per second mt s 1 with a 43 yr mean of about 60 mt s 1 a change of 25 33

representing the landslide magnitude frequency relation capilano river basin british columbia we use magnitude frequency analysis as a statistical tool to quantify the erosion caused by landslides and debris ows using air photo and ground derived data we show that the departure from power law distribution customarily observed for small magnitude is an artefact of sampling de ciencies nonetheless the total distribution is not sensitive to the frequency of small slides and total erosion remains adequately represented in the air photo derived data our data also demonstrate a real departure from simple scaling at much larger magnitudes the cause of which is not de nitively established copyright 2004 john wiley sons ltd

coupled atmosphere mixed layer ocean response to ocean heat flux convergence along the kuroshio current extension the winter response of the coupled atmosphere ocean mixed layer system to anomalous geostrophic ocean heat flux convergence in the kuroshio extension is investigated by means of experiments with an atmospheric general circulation model coupled to an entraining ocean mixed layer model in the extra tropics the direct response consists of positive sst anomalies along the kuroshio extension and a baroclinic low level trough and upper level ridge circulation anomaly over the north pacific the low level component of this atmospheric circulation response is weaker in the case without coupling to an extratropical ocean mixed layer especially in late winter the inclusion of an interactive mixed layer in the tropics modifies the direct coupled atmospheric response due to a northward displacement of the pacific inter tropical convergence zone which drives an equivalent barotropic anomalous ridge over the north pacific although the tropically driven component of the north pacific atmospheric circulation response is comparable to the direct response in terms of sea level pressure amplitude it is less important in terms of wind stress curl amplitude due to the mitigating effect of the relatively broad spatial scale of the tropically forced atmospheric teleconnection

seasonal evolutions of atmospheric response to decadal sst anomalies in the north pacific subarctic frontal zone observations and a coupled model simulation abstractpotential impacts of pronounced decadal scale variations in the north pacific sea surface temperature sst that tend to be confined to the subarctic frontal zone safz upon seasonally varying atmospheric states are investigated by using 48 yr observational data and a 120 yr simulation with an ocean atmosphere coupled general circulation model cgcm sst fields based on in situ observations and the ocean component of the cgcm have horizontal resolutions of 2 0 and 0 5 respectively which can reasonably resolve frontal sst gradient across the safz both the observations and cgcm simulation provide a consistent picture between sst anomalies in the safz yielded by its decadal scale meridional displacement and their association with atmospheric anomalies correlated with sst anomalies persistent in the safz from fall to winter a coherent decadal scale signal in the wintertime atmospheric circulation over the north pacific starts emerging in november and develops into an equivalent barotropic an

scale variation of post glacial sediment yield in chilliwack valley british columbia the holocene volumetric sediment budget is estimated for coarse textured sediments sand and gravel in a large formerly glaciated valley in southwest british columbia erosion is estimated by compiling volumetric loss estimated in digital elevation models dems of gullied topography and by applying a non linear diffusion model on planar undissected hillslopes estimates of steepland yield are based on estimates of post glacial deposition volumes in fans cones and deltas at the outlets of low order tributary catchments erosion of post glacial fans and tributary valley fills is estimated by reconstructing formerly continuous surfaces results are classed by catchment order and compared across scales of contributing area revealing declining specific sediment yield in m3 km 2 a 1 with catchment area for the smaller tributaries 10 km2 and increasing specific sediment yield for larger tributaries and chilliwack valley itself approximately 60 of mobilized sediment is redeposited in first to third order catchments with lesser proportions stored at the outlets of higher order catchments a simple network routing model emphasizes the significant sediment flux contributions from colluvium drift blankets and gullies in steeper terrain as this material is deposited at junctions within the lower drainage network an increasing proportion of material is derived from remnant valley fills and para glacial fans in the major valleys yield from lower order steepland catchments tends to remain in storage indefinitely sequestered on footslopes these observations have implications for modelling the post glacial sediment balance amongst catchments of varying size after 104 years the system remains in disequilibrium the critical linkage lies between low order hillslope catchments fourth order and the larger valleys with more complex fluvial systems copyright 2010 john wiley sons ltd

geomorphic and tectonic process rates effects of measured time interval analysis of the original numerical components of diverse geomorphic and tectonic process rates indicates that process rate is not independent of measured time interval this implies that direct comparison of geologic process rates measured over variable time intervals may not be valid and that conclusions based on those comparisons regarding changes in rates through geologic time may be misleading in some cases calculation of statistically derived scaling functions is one approach that can be used to account for this measurement interval bias and to improve comparisons of geologic process rate data when this approach is used a 10 4 or 10 5 yr variation in the measured time interval accounts for approximately one order of magnitude change in the measured process rate the magnitude of the correction can substantially affect conclusions of studies that compare uncorrected process rates calculated from variable time intervals

persistence and predictions of the remarkable warm anomaly in the northeastern pacific ocean during 2014 16 abstractin this work the evolution and prediction of the persistent and remarkable warm sea surface temperature anomaly ssta in the northeastern pacific during october 2013 june 2016 are examined based on experiments with an atmospheric model the possible contribution of sstas in different ocean basins to the atmospheric circulation anomalies is identified further through verifying the real time forecasts current capabilities in predicting such an extreme warm event with a state of the art coupled general circulation model are assessed during the long lasting warm event there were two warm maxima in the area averaged ssta around january 2014 and july 2015 respectively the warm anomaly originated at the oceanic surface and propagated downward and reached about 300 m model experiments forced by observed sst suggest that the long persistence of the atmospheric anomalies in the northeastern pacific as a whole may be partially explained by sst forcing particularly in the tropical pacific ocean ass