historical reconstruction of monthly oceanic precipitation 1900 2006 1 an oceanic precipitation reconstruction is developed and evaluated for periods extending back to as early as 1900 large scale monthly oceanic precipitation is reconstructed using the available network of historical gauge data fit to a set of large scale covariance spatial modes based on modern analysis the modern analysis is based on satellite microwave estimates merged with atmospheric reanalysis estimates for 1900 2006 a monthly and 5 spatial product is developed for reconstructing climate scale large scale spatial and inter seasonal and longer timescales variation in pre satellite periods advantages of this study include the use of a homogeneous satellite analysis for computing reconstruction statistics and improved tuning of the reconstruction methods cross validation testing is used to show how much historical variance can be reconstructed with the available sampling in addition reconstructions are performed using several different gauge data sets to evaluate differences due to the choice of gauge data testing shows that that these improved methods produce reconstructions with useful skill in the tropics and northern hemisphere midlatitudes in the southern hemisphere midlatitudes and in polar latitudes in both hemispheres sampling is too sparse to yield much skill the reconstruction is able to resolve large scale modes of variation useful for some diagnostic studies of the 20th century reconstruction efforts will continue as improved satellite and atmospheric reanalyses become available

historical trends in the surface temperature over the oceans based on the coads based on a new and unique compilation of surface ship data over the world ocean the comprehensive ocean atmosphere data set coads the temperature records since 1870 were thoroughly analyzed results for the air and sea surface temperature are presented for the two hemispheres and for individual 10 latitude wide belts the results support most earlier results of a relatively warm period over the oceans in the late 19th century a cool period between about 1905 and 1930 and a warm period from the 1940 s onward of considerable interest and perhaps unique in the historical record are the diverging trends in the midlatitude sea and air temperatures of the two hemispheres during the 1960 s and early 1970 s with relative cooling in the northern hemisphere and relative heating in the southern hemisphere

the 1906 earthquake fault rupture and paleoseismic investigation of the northern san andreas fault at the dogtown site marin county california our research describes historical observations of the 1906 earthquake rupture trace in marin county documents the style of subsurface deformation and summarizes our interpretation of the number and timing of pre 1906 ground rupturing earthquakes exposed in 18 trenches excavated across the northern san andreas fault nsaf at the dogtown site dogtown is located immediately southeast of what was known as the strain ranch in 1906 the trenches reveal two stratigraphic sections of late holocene age separated by a well constrained depositional hiatus the upper section deposited in the past 200 250 yr is separated from the lower section which was deposited between a d 250 and 650 by a hiatus during the interval a d 650 1700 we see evidence for two events in the upper section event i 1906 and event ii a likely penultimate earthquake plus a minimum of two events in the lower section event s a and b in the lower stratigraphic section the oldest exposed potential surface faulting evidence event b is constrained to the interval between a d 330 and 580 while there is sound evidence for ground rupturing earthquakes in the 1100 yr long interval between event b and event ii pedogenic processes have obscured their number and timing faulting evidence at the dogtown site suggests the penultimate earthquake occurred between a d 1695 and 1776 data from the dogtown site although equivocal suggest that the time interval 130 210 yr between the 1906 earthquake and the penultimate earthquake on the san andreas fault north of san francisco may be shorter than previously documented

north atlantic climate variability from a self organizing map perspective 1 north atlantic variability in general and the north atlantic oscillation nao in particular is a long studied very important but still not well understood problem in climatology the recent trend to a higher wintertime nao index was accompanied by an additional increase in the azores high not coupled to changes in the icelandic low as shown by a self organizing maps soms analysis of monthly mean djf mean sea level pressure data from 1957 to 2002 soms are a nonlinear tool to optimally extract a user specified number of patterns or icons from an input data set and to uniquely relate any input data field to an icon allowing analyses of occurrence frequencies and transitions complementary to principal component analysis pca soms analysis of era 40 data finds a north atlantic monopole roughly colocated with the mean position of the azores high as well as the well known nao dipole involving the icelandic low and the subtropical high little trend is shown in december but the azores high increased along with the nao in january and february over the study interval with implications for storminess in northwestern europe in short our som based analyses of winter mslp have both confirmed prior knowledge and expanded it through the relative ease of use and power with nonlinear systems of the som based approach to climatological analysis

observed nonlinearities of monthly teleconnections between tropical pacific sea surface temperature anomalies and central and eastern north american precipitation abstract most investigations of relationships between tropical pacific sea surface temperature anomaly ssta events and regional climate patterns have assumed the teleconnections to be linear whereby the climate patterns associated with cold ssta events are considered to be similar in structure and morphology but opposite in sign to those linked to warm ssta events in contrast and motivated by early evidence of nonlinearity in the above regard this study identifies characteristic i e composite calendar monthly central and eastern north american precipitation patterns separately for warm and cold ssta events in different regions of the tropical pacific central eastern west central horseshoe far western identified through principal component analysis the precipitation anomaly patterns are computed from an approximately 1 lat long set of monthly station data for 1950 92 their robustness and nonlinearity are established using local regional and field statistical significance tests and a va

the normality of el nino the amplitude of the el nino southern oscillation enso would be normally distributed if the coupled pacific ocean atmosphere were a linear system forced by gaussian weather noise moment estimates of skewness and kurtosis demonstrate that this is not the case for monthly mean anomalies in pacific sea surface temperatures during 1950 97 the noted predominance of el nino events compared to la nina events is related to the high skewness in the eastern pacific skewness and kurtosis both exhibit an intriguing geographical variation from positive in the eastern to negative in the western pacific we have also examined nino 3 indices generated by three climate models having widely different complexity these exhibit a wide range of skewness and kurtosis values rather different from those found for the observations skewness and kurtosis can be used to diagnose non linear processes and provide powerful tools for validating models and for testing observed sea surface temperatures for the presence of possible climate change

the earthquake cycle in the san francisco bay region a d 1600 2012 abstract stress changes produced by the 1906 san francisco earthquake had a profound effect on the seismicity of the san francisco bay region sfbr dramatically reducing it in the twentieth century whether the sfbr is still within or has emerged from this seismic quiescence is an issue of debate with implications for earthquake mechanics and seismic hazards historically the sfbr has not experienced one complete earthquake cycle i e the accumulation of stress its release primarily as coseismic slip during surface faulting earthquakes its re accumulation in the interval following and its subsequent rerelease the historical record of earthquake occurrence in the sfbr appears to be complete at about m 5 5 back to 1850 bakun 1999 for large events the record may be complete back to 1776 which represents about half a cycle paleoseismic data provide a more complete view of the most recent pre 1906 sfbr earthquake cycle extending it back to about 1600 using these we have developed estimates of magnitude and seismic moment for alternative sequences of surface faulting paleoearthquakes occurring between 1600 and 1776 on the region s major faults from these we calculate seismic moment and moment release rates for different time intervals between 1600 and 2012 these show the variability in moment release and suggest that in the sfbr regional plate boundary stress can be released on a single fault in great earthquakes such as that in 1906 and in multiple ruptures distributed on the regional plate boundary fault system on a decadal time scale

diatom evidence for earthquake induced subsidence and tsunami 300 yr ago in southern coastal washington fossil diatoms from four stratigraphic sections along the tidal niawiakum river southwestern washington provide an independent paleoecological test of a relative sea level rise that has been attributed to subsidence during an inferred earthquake in the cascadia subduction zone about 300 yr ago diatom assemblages in a buried soil and overlying mud indicate a sudden and lasting shift from marshes and forests near or above highest tides to mud flats and incipient tidal marshes with a progressive return to high level tidal marshes by sediment aggradation and perhaps gradual tectonic uplift the amount of coseismic submergence required to generate the paleoecological changes observed at these sites could have ranged from a minimum of 0 8 1 0 m to a maximum of 3 0 m fossil diatoms also provide an independent test of previous inferences that the subsidence was shortly followed by a tsunami the inferred tsunami deposit is a distinct sandy interval that widely overlies the buried marsh and forest soil diatoms from this interval consist of species observed on modern sand flats of the open bay identifying a bayward source for the sand occurrences of the same sand flat species above the buried soil in the farthest up valley outcrop where a sandy interval is not recognizable suggest that the tsunami extended farther landward than was previously inferred from the stratigraphy these data rule out proposed alternatives to the coseismic subsidence model that is climatically induced sea level rise temporary submergence caused by storms and support the hypothesis that a great earthquake struck southwestern washington 300 yr ago

sst assimilation experiments in a tropical pacific ocean model with a simple 3dvar assimilation algorithm a new scheme of assimilating sea surface temperature sst observations is proposed in this paper in this new scheme the linear relation between any two neighboring depths was derived using singular value decomposition technique and then was applied to estimate the temperatures at deeper levels using the temperature analyses at shallower levels the estimated temperatures were assimilated into an ocean model and the procedure was run iteratively at each time step from the surface to a depth of 250 m the oceanic analyses show that the new scheme can more effectively adjust oceanic thermal and dynamical fields and lead to a more realistic subsurface thermal structure when compared with the control

a damped decadal oscillation in the north atlantic climate system a simple stochastic atmosphere model is coupled to a realistic model of the north atlantic ocean a north south sst dipole with its zero line centered along the subpolar front influences the atmosphere model which in turn forces the ocean model by surface fluxes related to the north atlantic oscillation the coupled system exhibits a damped decadal oscillation associated with the adjustment through the ocean model to the changing surface forcing the oscillation consists of a fast wind driven positive feedback of the ocean and a delayed negative feedback orchestrated by overturning circulation anomalies the positive feedback turns out to be necessary to distinguish the coupled oscillation from that in a model without any influence from the ocean to the atmosphere using a novel diagnosing technique it is possible to rule out the importance of baroclinic wave processes for determining the period of the oscillation and to show the important role played by anomalous geostrophic advection in sustaining the oscillation

late holocene tectonics and paleoseismicity southern cascadia subduction zone holocene deformation indicative of large subduction zone earthquakes has occurred on two large thrust fault systems in the humboldt bay region of northern california displaced stratigraphic markers record three offsets of 5 to 7 meters each on the little salmon fault during the past 1700 years smaller and less frequent holocene displacements have occurred in the mad river fault zone elsewhere as many as five episodes of sudden subsidence of marsh peats and fossil forests and uplift of marine terraces are recorded carbon 14 dates suggest that the faulting subsidence and uplift events were synchronous relations between magnitude and various fault offset parameters indicate that earthquakes accompanying displacements on the little salmon fault had magnitudes of at least 7 6 to 7 8 more likely this faulting accompanied rupture of the boundary between the gorda and north american plates and magnitudes were about 8 4 or greater

the mechanical impact of the tibetan plateau on the seasonal evolution of the south asian monsoon the impact of the tibetan plateau on the south asian monsoon is examined using a hierarchy of atmospheric general circulation models during the premonsoon season and monsoon onset april june when westerly winds over the southern tibetan plateau are still strong the tibetan plateau triggers early monsoon rainfalldownstream particularlyoverthebay ofbengalandsouth china the downstreammoist convection is accompanied by strong monsoonal low level winds in experiments where the tibetan plateau is removed monsoon onset occurs about a month later but the monsoon circulation becomes progressively stronger and reaches comparable strength during the mature phase during the mature and decaying phase of monsoon july september when westerly winds over the southern tibetan plateau almost disappear monsoon circulation strength is not much affected by the presence of the tibetan plateau a dry dynamical core with east west oriented narrow mountains in the subtropics consistently simulates downstream convergence with background zonal westerlies over the mountain in a moist atmosphere the mechanically driven downstream convergence is expected to be associated with significant moisture convergence the authors speculate that the mechanically driven downstream convergence in the presence of the

reconstruction of historical sea surface temperatures using empirical orthogonal functions abstract studies of climate variability often rely on high quality sea surface temperature sst anomalies although the high resolution national centers for environmental prediction formerly the national meteorological center optimum interpolation oi sst analysis is satisfactory for these studies the oi resolution cannot be maintained before november 1931 due to the lack of satellite data longer periods of ssts have come from traditional analyses of in situ ship and buoy sst observations alone a new interpolation method is developed using spatial patterns from empirical orthogonal functions e0fs that is a principal component analysis to improve analyses of sst anomalies from 1950 to 1981 the method uses the more accurate oi analyses from 1982 to 1993 to produce the spatial eofs the dominant eof modes which correspond to the largest variance are used as basis functions and are fit in a least squares sense to the in situ data to determine the time dependence of each mode a complete field

how ubiquitous is the dipole relationship in tropical atlantic sea surface temperatures several kinds of analysis are applied to sea surface temperature anomalies ssta 1856 1991 to determine the degree to which ssta of opposite sign in the tropical north and south atlantic occur antisymmetric dipole configurations of ssta on basin scales are not ubiquitous in the tropical atlantic unless the data are stratified by both season and frequency inherent dipole behavior cannot be demonstrated upon removing the global el nino southern oscillation signal in ssta which is symmetric between the north and south atlantic from the data the regions north or south of the intertropical convergence zone have qualitatively different temporal variabilities and are poorly correlated dipole configurations do occur infrequently 12 15 of the time but no more so than expected by chance for stochastically independent variables nondipole configurations that imply significant meridional ssta gradients occur much more frequently nearly half of the time cross spectral analysis of seasonally averaged ssta indices for the north and south atlantic show marginally significant coherence with antisymmetric phase in two period bands 8 12 years for the boreal winter spring and 2 3 years for the boreal summer fall antisymmetric coherence is optimal for a small subregion west of angola in the south atlantic with respect to ssta of basin scale in the tropical north atlantic dipole variability even where optimal explains only a small fraction of the total variance in tropical atlantic ssta 7

paleoseismic investigations in the santa cruz mountains california implications for recurrence of large magnitude earthquakes on the san andreas fault trenching microgeomorphic mapping and tree ring analysis provide information on timing of paleoearthquakes and behavior of the san andreas fault in the santa cruz mountains at the grizzly flat site alluvial units dated at 1640 1659 a d 1679 1894 a d 1668 1893 a d and the present ground surface are displaced by a single event this was the 1906 surface rupture combined trench dates and tree ring analysis suggest that the penultimate event occurred in the mid 1600 s possibly in an interval as narrow as 1632 1659 a d there is no direct evidence in the trenches for the 1838 or 1865 earthquakes which have been proposed as occurring on this part of the fault zone in a minimum time of about 340 years only one large surface faulting event 1906 occurred at grizzly flat in contrast to previous recurrence estimates of 95 110 years for the santa cruz mountains segment comparison with dates of the penultimate san andreas earthquake at sites north of san francisco suggests that the san andreas fault between point arena and the santa cruz mountains may have failed either as a sequence of closely timed earthquakes on adjacent segments or as a single long rupture similar in length to the 1906 rupture around the mid 1600 s the 1906 coseismic geodetic slip and the late holocene geologic slip rate on the san francisco peninsula and southward are about 50 70 and 70 of their values north of san francisco respectively the slip gradient along the 1906 rupture section of the san andreas reflects partitioning of plate boundary slip onto the san gregorio sargent and other faults south of the golden gate if a mid 1600 s event ruptured the same section of the fault that failed in 1906 it supports the concept that long strike slip faults can contain master rupture segments that repeat in both length and slip distribution recognition of a persistent slip rate gradient along the northern san andreas fault and the concept of a master segment remove the requirement that lower slip sections of large events such as 1906 must fill in on a periodic basis with smaller and more frequent earthquakes

microfossil analysis of sediments representing the 1964 earthquake exposed at girdwood flats alaska usa abstract diatom pollen foraminifera and thecamoebian assemblages from an outcrop of peat and silt at girdwood flats in the upper turnagain arm of the cook inlet alaska record four phases of relative land and sea level changes the first phase is the development of freshwater swamp above high marsh sediments during relative land uplift caused by strain accumulation along the locked portion of the alaska aleutian subduction zone in second phase the top 2 cm of the peat all microfossil groups record pre seismic relative sea level rise relative land subsidence the third phase is rapid land subsidence 1 7 m during the earthquake of march 1964 that initiated intertidal silt accumulation above the peat the final phase is the colonisation of mudflat by salt marsh communities during post seismic land uplift the microfossil data compare favourably with sequences from washington oregon and british columbia that record late holocene submergence events caused by earthquakes the comparable changes in microfossil assemblages record the different phases of relative land and sea level changes and the magnitude of land subsidence caused by each earthquake expressed relative to the tidal range at the site these results raise the question whether preseismic sea level rise represents any kind of warning of large earthquakes

prediction of tropical atlantic sea surface temperatures using linear inverse modeling the predictability of tropical atlantic sea surface temperature on seasonal to interannual timescales by linear inverse modeling is quantified the authors find that predictability of caribbean sea and north tropical atlantic sea surface temperature anomalies sstas is enhanced when one uses global tropical sstas as predictors compared with using only tropical atlantic predictors this predictability advantage does not carry over into the equatorial and south tropical atlantic indeed persistence is a competitive predictor in those regions to help resolve the issue of whether or not the dipole structure found by applying empirical orthogonal function analysis to tropical atlantic ssts is an artifact of the technique or a physically real structure the authors combine empirically derived normal modes and their adjoints to form influence functions maps highlighting the geographical areas to which the north tropical atlantic and the south tropical atlantic ssts are most sensitive at specified lead times when the analysis is confined to the atlantic basin the 6 month influence functions in the north and south tropical atlantic tend to be of the opposite sign and evolve into clear dipoles within 6 months when the analysis is performed on global tropical ssts the 6 month influence functions are connected

hydrological signatures relating the asian summer monsoon and enso using the ncep ncar reanalysis for the 1950 2000 period differences in the atmospheric hydrological cycle between the extremes of enso i e la nina minus el nino are examined zonal vertically integrated moisture transport vimt across 1008e accounts for about half of the variability in net moisture convergence in the north indian ocean region between enso extremes when all enso events are considered changes in vimt across 1008e are associated with large changes in the strength of the pacific ocean trade wind regime during enso the bulk of the remaining vimt anomalies are from the arabian sea and appear to be associated with sea level pressure variations in the northern and western parts of the indian ocean basin this initial analysis therefore suggests that the interaction between the monsoon and enso may be more complex than the direct modulation of vimt by the pacific ocean trade winds alone the analysis is refined further by comparing the differences of the indian and pacific ocean hydrological cycles between enso extremes when they occur concurrently with anomalous monsoons enso anomalous monsoon years eam and when the monsoon is normal enso normal monsoon years enm for both eam and enm years similar differences exist in vimt across 1008e between enso extremes however major differences are noted in vimt anomalies from the west and south into the north indian ocean region thus the principal difference in moisture convergence in the north indian ocean between eam and enm years is associated primarily with vimt anomalies in the western indian ocean region and not those in the eastern indian or pacific oceans to test the hypothesis that pacific ocean sst anomalies occurring prior to the monsoon may be important in influencing the eventual nature of the monsoon the analysis is extended backward to the spring period while may sst differences in the nino 3 region between enso extremes are found to be similar for both eam and enm years vimt differences in both the indian ocean and the central and western pacific oceans are sig nificantly larger during eam years than enm years may sst differences in the central subtropical pacific ocean are also significantly larger during eam than enm years these results show that the anomalous sst gradient between the eastern equatorial and the central subtropical pacific ocean prior to the monsoon onset together with its associated vimts anomalies may be important factors in determining the degree of connection between monsoon and enso in addition the circulation in the indian ocean prior to and during the monsoon onset shares a strong association with the eventual intensity of the monsoon enso coupling

sedimentology of seismo turbidites off the cascadia and northern california active tectonic continental margins northwest pacific ocean abstract holocene turbidites from turbidite channel systems along the active tectonic continental margins of the cascadia subduction zone offshore vancouver island to mendocino triple junction and the northern san andreas transform fault the triple junction to san francisco bay have been analyzed for sedimentologic features related to their seismic origin centimeter thick silt sand beds turbidite base capped by mud layers turbidite tail and interbedded with hemipelagic silty clay intervals with high biogenic content have been characterized by visual core descriptions grain size analysis x ray radiographs and physical properties along the northern california margin in upstream single tributary canyons and channels most turbidites are uni pulsed classic fining up whereas downstream below multiple tributary canyon and channel confluences most deposits are stacked turbidites because each set of stacked turbidites has no hemipelagic sediment between each turbidite unit and each unit has a distinct mineralogy from a different tributary canyon we interpret that a stacked turbidite is deposited by several coeval turbidity currents fed by multiple tributary canyons and channels with synchronous triggering from a single san andreas fault earthquake the cascadia margin is characterized by individual multi pulsed turbidites that contain multiple coarse grained sub units without hemipelagic sediment between pulses because the number and character of multiple coarse grained pulses for each correlative multi pulsed turbidite is almost always constant both upstream and downstream in different channel systems for 600 km along the margin we interpret that the earthquake shaking or aftershock signature is usually preserved for the much stronger cascadia 9 mw compared to weaker california 8 mw earthquakes which result in upstream uni pulsed turbidites and downstream stacked turbidites consequently both the strongest 9 mw great earthquakes and downstream confluences cause multi pulsed and stacked turbidites that are typical for seismo turbidites generated by a single great earthquake along both margins earthquake triggering and multi pulsed or stacked turbidites become an alternative explanation for amalgamated turbidite beds in active tectonic margins and show that multiple grain size pulses and reverse grading are not unique criteria for hyperpycnites thalweg levee turbidites or mini basin margin turbidites the analyses of the turbidites along the cascadia and northern california margins reveal common sedimentologic characteristics of turbidites triggered by great earthquakes that can be used to distinguish seismo turbidites in other active tectonic margins around the world

activity of the yoro fault system determined from coseismic subsidence events recorded in the holocene delta sequence of the nobi plain central japan the holocene delta sequence of the nobi plain central japan records coseismic subsidence in the western part of the plain caused during the past 6000 years by movement on the yoro fault we identified four episodes of upward fining deposition and increasing electrical conductivity in delta front deposits that occurred 600 200 1300 900 4200 3800 and 5600 4700 years ago suggesting that episodes of sea level rise interrupted progradation of the kiso river delta considering the general trend of relative sea level fall during the middle to late holocene under the influence of eustasy and hydroisostasy the temporal correspondence of rises of relative sea level with activity on the yoro fault suggests they reflect coseismic subsidence due to yoro fault activity the timing of the coseismic subsidence events identified in this study also corresponds with that of previously reported faulting events at the kuwana fault to the south of the yoro fault these results are consistent with the previous interpretation that the yoro and kuwana faults comprise a behavioral segment within the yoro fault system our off fault paleoseismic study shows that coseismic subsidence events detected in holocene delta sequences can provide further evidence of faulting events inferred from the on fault paleoseismic studies

seasonal dependence of surface wind stress variability on sst and precipitation over the tropical pacific the dependence of interannual variability of surface zonal and meridional wind stresses x and y on sea surface temperature sst and precipitation over the tropical pacific is examined using observed data a strong seasonality in the dependence is found in january the largest sst and precipitation anomalies are located in the central to eastern and central tropical pacific respectively x anomalies in the southern central tropical pacific and y anomalies in the northern tropical pacific are highly correlated to both the sst and precipitation anomalies in contrast during july the largest sst and precipitation anomalies are located at the eastern and western tropical pacific respectively east of the dateline x anomalies present little dependence on the sst anomalies west of the dateline x anomalies depend strongly on the precipitation anomalies that are not linked to the leading modes of sst

robustness of low frequency circulation patterns derived from eof and rotated eof analyses abstract the robustness of low frequency circulation patterns defined by unrotated and rotated empirical orthogonal functions e0fs are compared based on the northern hemisphere 10 day low pass filtered wintertime 500 hpa height field the pacific north american pattern and the north atlantic oscillation are the most prominent modes of low frequency variability in the data the reproducibility of the spatial patterns derived from eof and rotated eof analysis is assessed by repeating the analysis on 50 subsets of the data each comprised of the maps belonging to 22 randomly selected winters from the 44 winters in the total record the results indicate that rotated spatial patterns are less sensitive to sampling fluctuations than their unrotated counterparts

low frequency variations in global mean sea level 1950 2000 1 low frequency variability in global mean sea level gmsl is studied for the period 1950 2000 by interpolating sparse tide gauge data to a global grid using empirical orthogonal functions eofs of sea level variability determined from topex poseidon t p altimeter data results are based on data with long term trends removed the fact that the results do not have secular trends is an artifact of the analysis and should not be interpreted as an indication that sea level is not rising the eof reconstruction technique is discussed and the resulting gmsl time series is compared to gmsl time series from geosat and t p altimetry and proxy gmsl time series estimated from global sea surface temperature data the error assessment suggests the accuracy of the gmsl time series reconstructed from the tide gauge data is 2 4 mm rms for a 1 year running mean smoothing and about 1 mm for a 5 year running mean smoothing several el nino la nina events are evident in the gmsl as well as significant low frequency variability at a 10 12 year period gmsl appears to have been generally lower than normal in the late 1960s throughout the 1970s and in the 1980s gmsl appears to have been generally higher than normal in the late 1950s and early 1960s and in the early 1980s and has been rising throughout the 1990s when t p is observing the implication of the low frequency signals on the determination the secular rate of gmsl from satellite altimetry is discussed

the generation of synthetic sea surface temperature data for the equatorial pacific ocean abstract synthetic monthly sst anomaly data are constructed using frequency domain analyses of significant principle components derived from reconstructed sst data in the equatorial pacific ocean the model provides insight into the dominant physical processes contained in each component and retains the relevant statistical properties of the original data such as the mean variance and autocorrelation thus numerous sets of synthetic sst anomaly data can be produced for the equatorial pacific that are statistically indistinguishable from the original sst anomaly data the spatial and temporal sst signatures of the biennial intradecadal and decadal pseudoperiodicities are reproduced including their frequency and duration of occurrence specifically the enso warm and cold event signatures recur in the synthetic data at peak return periods of 2 4 3 5 5 0 and 6 4 yr moreover the anticipated return period of an extreme enso event with a maximum sst anomaly magnitude of 1 7 c is approximately every

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

an improved method for analyzing sparse and irregularly distributed sst data on a regular grid the tropical pacific ocean an improved method for interpolating sparsely sampled climatological data onto a regular grid is shown the method uses the spatial and temporal covariance of the field along with the sparse data to fill the full grid this improves on similar methods that have recently been developed by eliminating the development of features that are not sufficiently supported by the data i e overfitting statistical tests are used to tune the method to represent as much variability as the spatial temporal information will support without overfitting the method is further improved by a data checking procedure that detects and removes suspect data the method is developed and evaluated by interpolating tropical pacific sea surface temperature sst monthly anomalies to a regular grid for the 1856 1995 period ship data averaged to 58 squares are used as input and are interpolated to a complete 18 grid comparing the results to interpolations using other methods shows this method s quantitative improvements where satellite data are available for validation comparisons in the presatellite era show sharper and stronger anomaly patterns with this method compared to another method developed for use with sparse data also shown are several periods when data are so sparse that only very weak sst anomalies may be reliably reconstructed in the tropical pacific i e before 1870 and 1915 25 in future research the global sst and possibly other climatological fields will be gridded using improved methods

dynamics of the indian monsoon and enso relationships in the sintex global coupled model this paper uses recent gridded climatological data and a coupled general circulation model gcm simulation in order to assess the relationships between the interannual variability of the indian summer monsoon ism and the el nino southern oscillation enso the focus is on the dynamics of the ism enso relationships and the ability of the state of the art coupled gcm to reproduce the complex lead lag relationships between the ism and the enso the coupled gcm is successful in reproducing the ism circulation and rainfall climatology in the indian areas even though the entire ism circulation is weaker relative to that observed in both observations and in the simulation the ism rainfall anomalies are significantly associated with fluctuations of the hadley circulation and the 200 hpa zonal wind anomalies over the indian ocean a quasi biennial time scale is found to structure the ism dynamical and rainfall indices in both cases moreover ism indices have a similar interannual variability in the simulation and observations the coupled model is less successful in simulating the annual cycle in the tropical pacific a major model bias is the eastward displacement of the western north pacific inter tropical convergence zone itcz near the dateline during northern summer this introduces a strong semiannual component in pacific walker circulation indices and central equatorial pacific sea surface temperatures another weakness of the coupled model is a less than adequate simulation of the southern oscillation due to an erroneous eastward extension of the southern pacific convergence zone spcz year round despite these problems the coupled model captures some aspects of the interannual variability in the tropical pacific enso events are phase locked with the annual cycle as observed but are of reduced amplitude relative to the observations wavelet analysis of the model nino34 time series shows enhanced power in the 2 4 year band as compared to the 2 8 year range for observations during the 1950 2000 period the ism circulation is weakened during enso years in both the simulation and the observations however the model fails to reproduce the lead lag relationship between the ism and nino34 sea surface temperatures ssts furthermore lag correlations show that the delayed response of the wind stress over the central pacific to ism variability is insignificant in the simulation these features are mainly due to the unrealistic interannual variability simulated by the model in the western north pacific the amplitude and even the sign of the simulated surface and upper level wind anomalies in these areas are not consistent with observed patterns during weak strong ism years the ism and western north pacific itcz fluctuate independently in the observations while they are negatively and significantly correlated in the simulation this isolates the pacific walker circulation from the ism forcing these systematic errors may also contribute to the reduced amplitude of enso variability in the coupled simulation most of the unrealistic features in simulating the indo pacific interannual variability may be traced back to systematic errors in the base state of the coupled model

experiments in reconstructing twentieth century sea levels abstract one approach to reconstructing historical sea level from the relatively sparse tide gauge network is to employ empirical orthogonal functions eofs as interpolatory spatial basis functions the eofs are determined from independent global data generally sea surface heights from either satellite altimetry or a numerical ocean model the problem is revisited here for sea level since 1900 a new approach to handling the tide gauge datum problem by direct solution offers possible advantages over the method of integrating sea level differences with the potential of eventually adjusting datums into the global terrestrial reference frame the resulting time series of global mean sea levels appears fairly insensitive to the adopted set of eofs in contrast charts of regional sea level anomalies and trends are very sensitive to the adopted set of eofs especially for the sparser network of gauges in the early 20th century the reconstructions appear especially suspect before 1950 in the tropical pacific while this limits some applications of the sea level reconstructions the sensitivity does appear adequately captured by formal uncertainties all our solutions show regional trends over the past five decades to be fairly uniform throughout the global ocean in contrast to trends observed over the shorter altimeter era consistent with several previous estimates the global sea level rise since 1900 is 1 70 0 26 mm yr 1 the global trend since 1995 exceeds 3 mm yr 1 which is consistent with altimeter measurements but this large trend was possibly also reached between 1935 and 1950

a physical basis for the interannual variability of rainfall in the sahel a major factor in rainfall variability over sahelian west africa is the latitudinal location of the tropical rainbelt when it is displaced abnormally far northward the sahel experiences a wet year an anomalous southward displacement results in drought in this paper we examine the question of what controls the location during the boreal summer hypothesizing that inertial instability plays a role an analysis of surface pressure and temperature fields wind fields divergence and vertical motion show that the criteria for inertial instability are satisfied in wet augusts but not in dry ones the key determinant appears to be the surface pressure gradient between the continent and the equatorial atlantic when this is large inertial instability results in the development of a low level westerly jet the presence of this jet enhances the horizontal and vertical shear and displaces the african easterly jet northwestward associated with this situation is strong vertical motion over the sahel and subsidence over the guinea coast producing dry conditions over the latter the result is a rainfall dipole one of two major modes of variability over west africa important factors include sea surface temperatures ssts in the equatorial atlantic and pressure in the south atlantic the first of these factors suggests a link with the atlantic nino mode of tropical atlantic variability while the second suggests a possible link with the pacific and the extratropical south atlantic overall our study relates the well known sst influence on sahel rainfall to atmospheric dynamics over the continent copyright 2007 royal meteorological society

viscoelastic earthquake cycle models with deep stress driven creep along the san andreas fault system 1 we develop a two dimensional boundary element earthquake cycle model including deep interseismic creep on vertical strike slip faults in an elastic lithosphere coupled to a viscoelastic asthenosphere uniform slip on the upper part of the fault is prescribed periodically to represent great strike slip earthquakes below the coseismic rupture the fault creeps in response to lithospheric shear stresses within a narrow linear viscous fault zone the model is applied to the gps contemporary velocity field across the carrizo plain and northern san francisco bay segments of the san andreas fault as well as triangulation measurements of postseismic strain following the 1906 san francisco earthquake previous analysis of these data using conventional viscoelastic coupling models without stress driven creep segall 2002 shows that it is necessary to invoke different lithosphere asthenosphere rheology in northern and southern california in order to explain the data we show that with deep stress driven interseismic creep on the san andreas fault the data can be explained with the same rheology for northern and southern california we estimate elastic thickness in the range 44 100 km 95 confidence level fault zone viscosity per unit width of 0 5 8 2 1017 pa s m and asthenosphere relaxation time of 24 622 years 0 1 2 9 1020 pa s for northern and southern california we estimate a slip rate of 21 27 mm yr and recurrence time of 188 315 years for the northern san francisco bay san andreas fault and slip rate of 32 42 mm yr with recurrence time of 247 536 years for the carrizo plain

late holocene slip rate and recurrence of great earthquakes on the san andreas fault in northern california the slip rate of the san andreas fault 45 km north of san francisco at olema california is determined by matching offset segments of a buried late holocene stream channel stream deposits from 1 800 plus minus 78 yr b p are offset 42 5 plus minus 3 5 m across the active 1906 fault trace for a minimum late holocene slip rate of 24 plus minus 3 mm yr when local maximum coseismic displacements of 4 9 to 5 5 m from the 1906 earthquake are considered with this slip rate the recurrence of 1906 type earthquakes on the north coast segment of the san andreas fault falls within the interval of 221 plus minus 40 yr both comparable coseismic slip in 1906 and similar late holocene geologic slip rates at the olema site and a site 145 km northwest at point arena prentice 1989 suggest that the north coast segment behaves as a coherent rupture unit

wintertime variability in the euro atlantic region in observations and in ecmwf seasonal ensemble experiments an empirical orthogonal function eof decomposition of monthly mean analyses of 500 hpa height 1949 94 is used to describe the interannual variability of the large scale flow in the euro atlantic region during winter the first four eofs resemble low frequency variability patterns identified in previous studies such as the north atlantic oscillation and the eastern atlantic and eurasian teleconnection patterns the second eof and fourth eof eof4 are associated with the occurrence of el nino like sea surface temperature sst anomalies according to an observational analysis for eof4 correlations with sst anomalies in the west pacific are also important indications of an influence of tropical sst anomalies on the blocking like third eof emerging from the european centre for medium range weather forecasts ecmwf re analysis era data are not confirmed by a longer sst record a negligible correlation exists between the first eof and el nino indices during the era period although a link may be detected in earlier decades in the second part of the paper a 14 winter set of seasonal ensemble simulations performed with the ecmwf atmospheric model forced by observed sst is validated by comparing the projection of era data onto the four leading euro atlantic eofs with those of ensemble experiments and computing composite anomalies of analyses and model fields the performance of the model is uneven and depends on the large scale pattern considered model biases and flow dependent errors affect the simulations of some of the eofs in particular the model has strong problems reproducing the occurrence of european blocks the best correlation 69 between the time series of analysis and ensemble mean principal components is obtained for eof4 which seems to be forced by sst anomalies in the west pacific associated with el nino southern oscillation enso events the effects of this forcing are felt on the zonal wind structure over eurasia and are reasonably reproduced by the ecmwf model conversely the propagation into the atlantic region of planetary waves originating in the east pacific is poorly simulated thus degrading the model performance in predicting euro atlantic anomalies during some strong enso events

the non tropical coral cladocora caespitosa as the new climate archive for the mediterranean high resolution weekly trace element systematics abstract high resolution weekly laser ablation icp ms trace element analyses b sr u mg ba are reported for the scleractinian coral cladocora caespitosa collected from the northern adriatic sea geochemical ratios sr ca b ca mg ca u ca ba ca were measured in a 38 mm long 10 years growth external coralline portion wall region and generally exhibit a close relationship with the in situ measured weekly fortnightly data on sea surface temperature sst available for the last 6 years in particular b ca ratios tuned to fine scale variations in sst show a high degree of correlation r 0 856 n 136 with sst and indicate that coral calcification only occurs above a minimum temperature threshold of 14 16 c in addition the ranges of trace element variability are larger than those typically recorded in tropical corals consistent with the large seasonal variations in sst of the adriatic this study thus demonstrates the feasibility of extracting and exploiting high resolution geochemical records from non tropical corals such as c caespitosa as a proxy for sst

interannual variability of summer monsoon onset over the western north pacific and the underlying processes climatological summer monsoon onset over the south china sea scs and the western north pacific wnp defined as the region of 108 208n 1208 1608e displays three distinct stages around mid may monsoon rain commences in the scs and the philippines in early to mid june the monsoon rain extends to the southwestern philippine sea after mid july the rainy season starts in the northeastern part of the wnp the onset anomaly however displays an in phase interannual variation across the entire wnp domain the standard deviation of the onset date increases eastward from 3 pentads in the scs to 5 pentads in the northeastern part of the domain the large onset variability in the wnp is mainly attributed to large year to year changes of the seasonal cycle

the thermal oceanographic signal of el nino reconstructed from a kiritimati island coral central equatorial pacific sea surface temperature sst anomaly is a critical predictor of basin wide oceanographic and atmospheric effects of the el nino southern oscillation enso phenomenon we employ two geochemical thermometers measured on coralline aragonite to reconstruct an independent proxy based measure of central equatorial pacific sea surface temperature anomaly in addition we assess the observational error associated with extraction of large scale sst anomalies from 18o and sr ca measurements on the basis of paired data for the 1981 1987 period rms error for the estimation of sst from kiritimati coral 18o is about 0 4 c assuming no seawater 18o influence for sr ca the observational error is about 0 5 c singular spectrum analysis of the 18o time series suggests that 1 3 of the variance is explained by sst anomaly and that this variance may be separated from other signals in the frequency domain the interannual component of the 18o record shares 70 variance with the interannual component of local sst anomaly estimates 0 84 and correlates as highly with nino3 region 150 w 90 w 5 n 5 s sst anomaly estimates comparison of annual averages of the 18o data with analyzed sst for 55 years suggests that the error in deriving annually averaged sst anomalies at kiritimati is about 0 4 c a global sst correlation analysis suggests significant correlation with the rest of the pacific basin and the tropical indian and atlantic sectors the ocean wide level of correlation achieved using the coral data is indistinguishable from that achieved using the nino3 sst anomaly index and suggests that a few well located coral reconstructions with low observational error may be sufficient to reconstruct the global sst anomaly field associated with enso activity

local coupled equatorial variability versus remote enso forcing in an intermediate coupled model of the tropical atlantic the relative roles played by the remote el nino southern oscillation enso forcing and the local air sea interactions in the tropical atlantic are investigated using an intermediate coupled model icm of the tropical atlantic the oceanic component of the icm consists of a six baroclinic mode ocean model and a simple mixed layer model that has been validated from observations the atmospheric component is a global atmospheric general circulation model developed at the university of california los angeles ucla in a forced context the icm realistically simulates both the sea surface temperature anomaly ssta variability in the equatorial band and the relaxation of the atlantic northeast trade winds and the intensification of the equatorial westerlies in boreal spring that usually follows an el nino event the results of coupled experiments with or without pacific enso forcing and with or without explicit air sea interactions in the equatorial atlantic indicate that the background energy in the equatorial atlantic is provided by enso however the time scale of the variability and the magnitude of some peculiar events cannot be explained solely by enso remote forcing it is demonstrated that the peak of ssta variability in the 1 3 yr band as observed in the equatorial atlantic is due to the local air sea interactions and is not a linear response to enso seasonal phase locking in boreal summer is also the result of the local coupling the analysis of the intrinsic sustainable modes indicates that the atlantic el nino is qualitatively a noisedriven stable system such a system can produce coherent interdecadal variability that is not forced by the pacific or extraequatorial variability it is shown that when a simple slab mixed layer model is embedded into the system to simulate the northern tropical atlantic nta sst variability the warming over nta following el nino events have characteristics location and peak phase that depend on air sea interaction in the equatorial atlantic in the model the interaction between the equatorial mode and nta can produce a dipolelike structure of the ssta variability that evolves at a decadal time scale the results herein illustrate the complexity of the tropical atlantic ocean atmosphere system whose predictability jointly depends on enso and the connections between the atlantic modes of variability

comparison of the structure of the itcz in the west pacific during the boreal summers of 1989 93 using amip simulations and ecmwf reanalysis the dynamic structure and interannual variability of the itcz in the western north pacific and east asia during the boreal summers of 1989 93 are investigated european centre for medium range weather forecasts ecmwf reanalyses are used to characterize the dynamical structure of the itcz the itcz structure in the national center for atmospheric research ncar community climate model 3 ccm3 6 and the national aeronautics and space administration nasa goddard institute of space studies giss si2000 gcm is also explored the itcz axis can be partitioned into three sections in the western north pacific and east asia the continental monsoon trough cmt in india the bay of bengal and indo china the oceanic monsoon trough omt in the pacific warm pool and the trade wind trough twt in the central pacific the confluence point cp is defined as an area where the broad cyclonic flow in omt changes to the easterly trades of the twt east of the cp both gcms simulate a weaker easterly trade wind regime with a broader itcz due to the dislocation of the pacific high to the west of the cp both gcms simulate a weaker cross equatorial flow and omt both models show skill in simulating the interannual variability of the location of the cp however for the peak enso warm phase years 1992 93 the spread among ensemble members of the cp longitude is comparable to the shift of ensemble mean cp location relative to 1989 that is the internal variability of each gcm is on the same order as the simulated interannual variability in this region

remotely forced variability in the tropical atlantic ocean an ensemble of eight hindcasts has been conducted using an ocean atmosphere general circulation model fully coupled only within the atlantic basin with prescribed observational sea surface temperature sst for 1950 1998 in the global ocean outside the atlantic basin the purpose of these experiments is to understand the influence of the external sst anomalies on the interannual variability in the tropical atlantic ocean statistical methods including empirical orthogonal function analysis with maximized signal to noise ratio have been used to extract the remotely forced atlantic signals from the ensemble of simulations it is found that the leading external source on the interannual time scales is the el nino southern oscillation enso in the pacific ocean the enso signal in the tropical atlantic shows a distinct progression from season to season during the boreal winter of a maturing el nino event the model shows a major warm center in the southern subtropical atlantic together with warm anomalies in the northern subtropical atlantic the southern subtropical sst anomalies is caused by a weakening of the southeast trade winds which are partly associated with the influence of an atmospheric wave train generated in the western pacific ocean and propagating into the atlantic basin in the southern hemisphere during boreal fall in the boreal spring the northern tropical atlantic ocean is warmed up by a weakening of the northeast trade winds which is also associated with a wave train generated in the central tropical pacific during the winter season of an el nino event apart from the atmospheric planetary waves these sst anomalies are also related to the sea level pressure slp increase in the eastern tropical atlantic due to the global adjustment to the maturing el nino in the tropical pacific the tropical slp anomalies are further enhanced in boreal spring which induce anomalous easterlies on and to the south of the equator and lead to a dynamical oceanic response that causes cold sst anomalies in the eastern and equatorial atlantic from boreal spring to summer most of these sst anomalies persist into the boreal fall season

discordant 14c ages from buried tidal marsh soils in the cascadia subduction zone southern oregon coast peaty tidal marsh soils interbedded with estuarine mud in late holocene stratigraphic sequences near coos bay oregon may have been submerged and buried during great m 8 subduction earthquakes smaller localized earthquakes or by nontectonic processes radiocarbon dating might help distinguish among these alternatives by showing that soils at different sites were submerged at different times along this part of the cascadia subduction zone but comparison of conventional 14c ages for different materials from the same buried soils shows that they contain materials that differ in age by many hundreds of years errors in calibrated soil ages represent about the same length of time as recurrence times for submergence events 150 500 yr this similarity precludes using conventional 14c ages to distinguish buried soils along the southern oregon coast accelerator mass spectrometer 14c ages of carefully selected macrofossils from the tops of peaty soils should provide more precise estimates of the times of submergence events

a linear tendency correction technique for improving seasonal prediction of sst tropical atlantic sector using an agcm coupled to a slab ocean by construction the model has systematic biases in its deterministic dynamics because the slab ocean has no ocean dynamics we show that the linear correction procedure successfully corrects the model biases in the regions where ocean dynamics are expected to be important 4 in a recent study chang et al 2003 hereafter csj show that sst anomalies in the tropical north atlantic tna can be predicted two seasons in advance using an agcm coupled to a slab ocean owing to the combined effect of the remote enso influence and local thermodynamic air sea feedbacks but in the tropical south and equatorial atlantic the simple coupled model revealed poor skills and under performed the persistence forecast here we use csj s results as a reference with the exception that the prediction and verification period is expanded from 1959 to 2000 we focus on february may the peak months of the gradient mode of variability in the tropical atlantic chiang et al 2002 allowing us to investigate the importance of ocean dynamics in its evolution

the formation of proval bay as an episode in the development of the baikal rift basin a case study abstract this paper provides a cumulative review of important specific features in the formation and development of proval bay lake baikal as a large seismic dislocation element this bay appeared during one of the largest historical earthquakes in siberia m lh 7 5 on january 12 1862 as a result more than 230 km 2 of the shore was submerged the paper considers the formation of proval bay in the context of analysis conducted on general morphological characteristics of the baikal rift and in terms of the occurrence of the main elements in the mechanism of its neotectonic development it is precisely these seismotectonic phenomena associated with the subsidence of large tectonic blocks which primarily cause the growth of lake baikal basin in spite of the fact that the northwestern side of the rift has a more pronounced morphological structure whose general elements are high and steep monolithic tectonic escarpments major lithospheric extension and its associated extension of the rift thinning and rearrangement of blocks in the upper lithosphere slab occur on the more gently sloping eastern side

abrupt along strike change in tectonic style san andreas fault zone san francisco peninsula seismicity and high resolution aeromagnetic data are used to define an abrupt change from compressional to extensional tectonism within a 10 to 15 km wide zone along the san andreas fault on the san francisco peninsula and offshore from the golden gate this 100 km long section of the san andreas fault includes the hypocenter of the mw 7 8 1906 san francisco earthquake as well as the highest level of persistent microseismicity along that 470 km long rupture we define two distinct zones of deformation along this stretch of the fault using well constrained relocations of all post 1969 earthquakes based a joint one dimensional velocity hypocenter inversion and a redetermination of focal mechanisms the southern zone is characterized by thrust and reverse faulting focal mechanisms with ne trending p axes that indicate fault normal compression in 7 to 10 km wide zones of deformation on both sides of the san andreas fault a 1 to 2 km wide vertical zone beneath the surface trace of the san andreas is characterized by its almost complete lack of seismicity the compressional deformation is consistent with the young high topography of the santa cruz mountains coast ranges as the san andreas fault makes a broad restraining left bend 10 o through the southernmost peninsula a zone of seismic quiescence 15 km long separates this compressional zone to the south from a zone of combined normal faulting and strike slip faulting focal mechanisms including a m l 5 3 earthquake in 1957 on the northernmost peninsula and offshore on the golden gate platform both linear pseudo gravity gradients calculated from the aeromagnetic data and seismic reflection data indicate that the san andreas fault makes an abrupt 3 km right step less than 5 km offshore in this northern zone a similar right stepping dilatational geometry is also observed for the subparallel san gregorio fault offshore persistent seismicity and extensional tectonism occur within the san andreas right stepover region and at least 15 km along strike both to the se and nw the 1906 san francisco earthquake may have nucleated within the san andreas right stepover which may help explain the bilateral nature of rupture of this event our analysis suggests two seismic hazards for the san francisco peninsula in addition to the hazard associated with a m 7 to 8 strike slip earthquake along the san andreas fault the potential for a m 6 normal faulting earthquake just 5 8 km west of san francisco and a m 6 thrust faulting event in the southern peninsula

the response of a coupled model of enso to observed estimates of stochastic forcing in this work the role that observed intraseasonal atmospheric variability may play in controlling and maintaining enso variability is examined to this end an asymptotically stable intermediate coupled model of el nino southern oscillation enso is forced with observed estimates of stochastic forcing which are defined to be the part of the atmospheric variability that is apparently independent of the ocean circulation the stochastic forcing sf was estimated from 51 yr 1950 2000 of ncep ncar reanalyses of surface winds and net surface heat flux 32 yr 1950 81 of reconstructed sea surface temperatures sst and 19 yr 1982 2000 of reynolds sst in the tropical pacific the deterministic component of the surface wind and heat flux anomalies that can be linearly related to sst anomalies was estimated using the singular value decomposition of the covariance between the anomaly fields and was then removed from the atmospheric anomaly fields to recover the stochastic component of the ocean surface forcing principal component analysis reveals that the stochastic component has no preferred mode of variability exhibits decorrelation times of a few days and has a spectrum that is indis tinguishable from red noise a 19 yr stochastically forced coupled model integration qualitatively shows some similarities with the observed equatorial sst the robustness of this result is checked by performing different sensitivity experiments the model mostly exhibits a linear and nonnormal response to the low frequency tail of sf using the ideas of generalized linear stability theory the dynamically important contributions of the sf are isolated and it is shown that most of the variability in the stochastically forced model solution is produced by stochastically induced kelvin waves forced in the western and central pacific moreover the two most dynamically important patterns of stochastic forcing which account for 71 of the expected variance in the model response describe eastward propagation of the forcing similar to the mjo the results of this study support the hypothesis that a significant fraction of enso variability may be due to sf and suggest that a better understanding of the influence of sf on the ocean surface in the western central pacific may be required in order to understand the predictability of enso

characteristics of winter precipitation variation over northern central eurasia and their connections to sea surface temperatures over the atlantic and pacific oceans abstract this study reveals spatial and temporal characteristics of precipitation variability and their teleconnections to sea surface temperatures ssts over the atlantic and pacific oceans by analyzing 68 yr of recent precipitation records over the former soviet union in addition to a general increasing trend of about 0 4 mm yr 1 or 6 decade 1 over much of the study region three major modes of precipitation variation are identified a quasi biennial variation of 2 3 yr is found over the region surrounding the caspian and aral seas an el nino timescale precipitation variation of 4 5 yr is present over southern central siberia and is associated with eastern tropical pacific ssts a quasi decadal timescale variation of about 11 12 yr is evident over central european russia this quasi decadal precipitation variation is closely linked to a major sst anomaly pattern of alternating latitudinal belts over the atlantic and sst variations over the equatorial pacific ocean these associations to ssts are str

detection of large prehistoric earthquakes in the pacific northwest by microfossil analysis geologic and palynological evidence for rapid sea level change 3400 and 2000 carbon 14 years ago 3600 and 1900 calendar years ago has been found at sites up to 110 kilometers apart in southwestern british columbia submergence on southern vancouver island and slight emergence on the mainland during the older event are consistent with a great magnitude m 8 earthquake on the cascadia subduction zone the younger event is characterized by submergence throughout the region and may also record a plate boundary earthquake or a very large crustal or intraplate earthquake microfossil analysis can detect small amounts of coseismic uplift and subsidence that leave little or no lithostratigraphic signature

identifying coseismic subsidence in tidal wetland stratigraphic sequences at the cascadia subduction zone of western north america tidal wetland stratigraphy reveals that great plate boundary earthquakes have caused hundreds of kilometers of coast to subside at the cascadia subduction zone however determining earthquake recurrence intervals and mapping the coastal extent of past great earthquake ruptures in this region are complicated by the effects of many sedimentologic hydrographic and oceanographic processes that occur on the coasts of tectonically passive as well as active continental margins tidal wetland stratigraphy at many cascadia estuaries differs little from that at similar sites on passive margin coasts where stratigraphic sequences form through nonseismic processes unrelated to coseismic land level changes methods developed through study of similar stratigraphic sequences in europe provide a framework for investigating the cascadia estuarine record five kinds of criteria must be evaluated when inferring regional coastal subsidence due to great plate boundary earthquakes the suddenness and amount of submergence the lateral extent of submerged tidal wetland soils the coincidence of submergence with tsunami deposits and the degree of synchroneity of submergence events at widely spaced sites evaluation of such criteria at the cascadia subduction zone indicates regional coastal subsidence during at least two great earthquakes evidence for a coseismic origin remains equivocal however for the many peat mud contacts in cascadia stratigraphic sequences that lack 1 contrasts in lithology or fossils indicative of more than half a meter of submergence 2 well studied tsunami deposits or 3 precise ages needed for regional correlation paleoecologic studies of fossil assemblages are particularly important in estimating the size of sudden sea level changes recorded by abrupt peat mud contacts and in helping to distinguish erosional and gradually formed contacts from coseismic contacts reconstruction of a history of great earthquakes for the cascadia subduction zone will require rigorous application of the above criteria and many detailed investigations

abrupt uplift within the past 1700 years at southern puget sound washington shorelines rose as much as 7 meters along southern puget sound and hood canal between 500 and 1700 years ago evidence for this uplift consists of elevated wave cut shore platforms near seattle and emerged peat covered tidal flats as much as 60 kilometers to the southwest the uplift was too rapid for waves to leave intermediate shorelines on even the best preserved platform the tidal flats also emerged abruptly they changed into freshwater swamps and meadows without first becoming tidal marshes where uplift was greatest it adjoined an inferred fault that crosses puget sound at seattle and it probably accompanied reverse slip on that fault 1000 to 1100 years ago the uplift and probable fault slip show that the crust of the north america plate contains potential sources of damaging earthquakes in the puget sound region

past earthquake induced rapid subsidence along the northern san andreas fault a paleoseismological method for investigating strike slip faults evidence of rapid relative sea level changes preserved in sediment of coastal estuaries along the north coast segment of the san andreas fault provides information on the dates of past earthquakes this approach although successfully used to document large subduction zone earthquakes has not been used previously to constrain the dates of san andreas fault or other strike slip fault earthquakes data on prehistoric san andreas fault earthquakes is needed for development of robust probabilistic hazard assessments in northern california and the san francisco bay area evidence of earthquake induced subsidence is preserved in marshes at the northern margin of bolinas lagoon and the southeastern margin of bodega harbor these sites occupy structural basins or troughs along the northern san andreas fault radiocarbon dating and identification of the first occurrence of nonnative pollen near abrupt sedimentological changes in cores are used to constrain the dates of san andreas fault earthquakes over about the last 800 years estuarine sediment from northern bolinas lagoon preserves evidence of an earthquake that occurred about 750 years ago evidence for this earthquake includes a marsh soil that was abruptly buried by tidal flat mud or coarse poorly sorted deltaic deposits containing a mixture of terrestrial sediment and marine mud evaluation of diatom assemblages from above and below the buried soil horizon provides evidence of at least several decimeters of sustained relative sea level rise three buried soils in a marsh at the southern end of bodega harbor are likely a result of coseismic subsidence all three buried marsh soils have abrupt upper contacts although diatom evidence for decimeters of sustained subsidence is not as strong as it is for the buried soil in bolinas lagoon existing paleoseismic data on the northern san andreas fault is compared with results of this study in order to evaluate the dates of prehistoric large earthquakes and length of past ruptures these data indicate that an earthquake occurred about 400 years ago and another earthquake occurred about 700 years ago the data allow for 1906 type ruptures of the fault from the santa cruz mountains to at least point arena however a sequence of closely timed smaller earthquakes would produce a similar set of paleoseismic data

reconstructing sea level using cyclostationary empirical orthogonal functions 1 cyclostationary empirical orthogonal functions derived from satellite altimetry are combined with historical sea level measurements from tide gauges to reconstruct sea level fields from 1950 through 2009 previous sea level reconstructions have utilized empirical orthogonal functions as basis functions but by using cyclostationary empirical orthogonal functions and by addressing other aspects of the reconstruction procedure an alternative sea level reconstruction can be computed the procedure introduced here is capable of capturing the annual cycle and el nino southern oscillation enso signals back to 1950 with correlations between the reconstructed enso signal and common enso indices found to be over 0 9 the regional trends computed from the new reconstruction show good agreement with the trends obtained from the satellite altimetry but some discrepancies are seen when comparing with previous sea level reconstructions over longer time periods the computed rate of global mean sea level rise from the reconstructed time series is 1 97 mm yr from 1950 to 2009 and 3 22 mm yr from 1993 to 2009

holocene coseismic and aseismic uplift of isla mocha south central chile abstract during the past 6000 years isla mocha a 12 km long island 30 km off the coast of south central chile experienced a 38 m fall of relative sea level caused primarily by rapid tectonic uplift of the island as many as 18 raised shorelines strandlines record this uplift historic accounts of uplift during the great earthquakes m 8 of 1835 and 1960 suggest some of the more prominent prehistoric strandlines also emerged during great earthquakes on the interface between the nazca and south america plates but the close elevational spacing of strandlines subdued morphology of strandline beaches scarcity of exposed bedrock wave cut platforms and the extremely high rates of aseismic uplift ca 70 mm yr of the island since the last great earthquake suggest that many strandlines were raised by aseismic rather than coseismic uplift strandline heights and 14 new radiocarbon ages on marine shells show that the present day uplift rate is more than three times the net rate ca 20 mm yr of the past 1000 years the recent high rate probably reflects increased aseismic slip on an inferred thrust fault in the overriding south america plate isla mocha overlies an area of high stress concentration between two major segments of the chilean subduction zone the inferred high rate of slip on the thrust fault may be a response to stress changes on the plate interface near the boundary between the segments

identification and separation of mount pinatubo and el nino southern oscillation land surface temperature anomalies empirical data analyses are performed to detect and separate the signals of the volcanic eruption and el nino events in the observed surface air temperature sat anomalies over land for the 2 years following the pinatubo eruption composite analyses of surface temperatures for the 1950 1997 period excluding the 2 years following each of the three major volcanic eruptions agung el chichon and pinatubo show that the distribution of sat anomalies over most land areas for the el nino composite is opposite to that for the la nina composite the pattern of sat anomalies changes from season to season this feature is more prominent over north america than over the other continents singular value decomposition analyses show that following the pinatubo eruption el nino signals were weak over eurasia but relatively strong over the other continents over north america the 1991 1992 el nino event contributed more than 50 to the observed surface cooling of about 1 0 c in june july and august 1992 globally averaged the maximum cooling over land with the el nino southern oscillation signals removed is 0 5 c in september october and november 1992 and september october and november 1993

nonlinear interdecadal changes of the el nino southern oscillation nonlinear interdecadal changes in the el nino southern oscillation enso phenomenon are investigated using several tools a nonlinear canonical correlation analysis nlcca method based on neural networks a hybrid coupled model and the delayed oscillator theory the leading nlcca mode between the tropical pacific wind stress ws and sea surface temperature sst reveals notable interdecadal changes of enso behaviour before and after the mid 1970s climate regime shift with greater nonlinearity found during 1981 99 than during 1961 75 spatial asymmetry for both sst and ws anomalies between warm el nino and cool la nina events was significantly enhanced in the later period during 1981 99 the location of the equatorial easterly anomalies was unchanged from the earlier period but in the opposite enso phase the westerly anomalies were shifted eastward by up to 25 according to the delayed oscillator theory such an eastward shift would lengthen the duration of the warm events by up to 45 but leave the duration of the cool events unchanged supporting evidence was found from a hybrid coupled model built with the lamont dynamical ocean model coupled to a statistical atmospheric model consisting of either the leading nlcca or cca mode

artificial intelligence reconstructs missing climate information historical temperature measurements are the basis of global climate datasets like hadcrut4 this dataset contains many missing values particularly for periods before the mid twentieth century although recent years are also incomplete here we demonstrate that artificial intelligence can skilfully fill these observational gaps when combined with numerical climate model data we show that recently developed image inpainting techniques perform accurate monthly reconstructions via transfer learning using either 20cr twentieth century reanalysis or the cmip5 coupled model intercomparison project phase 5 experiments the resulting global annual mean temperature time series exhibit high pearson correlation coefficients 0 9941 and low root mean squared errors 0 0547 c as compared with the original data these techniques also provide advantages relative to state of the art kriging interpolation and principal component analysis based infilling when applied to hadcrut4 our method restores a missing spatial pattern of the documented el nino from july 1877 with respect to the global mean temperature time series a hadcrut4 reconstruction by our method points to a cooler nineteenth century a less apparent hiatus in the twenty first century an even warmer 2016 being the warmest year on record and a stronger global trend between 1850 and 2018 relative to previous estimates we propose image inpainting as an approach to reconstruct missing climate information and thereby reduce uncertainties and biases in climate records an artificial intelligence based method may infill gaps in historical temperature data more effectively than conventional techniques application of this method reveals a stronger global warming trend between 1850 and 2018 than estimated previously

evidence for a large earthquake and tsunami 100 400 years ago on western vancouver island british columbia abstract a peaty marsh soil is sharply overlain by a sand sheet and intertidal mud at tidal marshes near tofino and ucluelet vancouver island british columbia foraminifera and vascular plant fossils show that the buried soil was submerged suddenly and was covered quickly by sand radiocarbon ages place this event between 100 and 400 yr ago the coastal subsidence suggested by the submergence occurred in an area of net late holocene emergence perhaps during the most recent great earthquake on the northern part of the cascadia subduction zone the sand sheet overlying the peaty soil records the tsunami triggered by this earthquake similar stratigraphic sequences of about the same age have been reported from estuaries along the outer coasts of washington and northern oregon suggesting that hundreds of kilometers of the cascadia subduction zone may have ruptured during one or a series of plate boundary earthquakes less than 400 yr ago

atlantic climate variability and its associated atmospheric circulation cells abstract phenomena important for atlantic climate variability include the atlantic zonal equatorial mode the tropical atlantic meridional gradient mode and the north atlantic oscillation nao these climate phenomena and their associated atmospheric circulation cells are described and discussed using the ncep ncar reanalysis field and the ncep sea surface temperature sst from january 1950 to december 1999 atmospheric divergent wind and vertical motion are used for the identification of atmospheric circulation cells during the peak phase of the atlantic equatorial mode the atlantic walker circulation weakens and extends eastward which results in surface westerly wind anomalies in the equatorial western atlantic these westerly wind anomalies are partly responsible for warming in the equatorial eastern atlantic that occurs in the second half of the year the atlantic equatorial mode involves a positive ocean atmosphere feedback associated with the atlantic walker circulation similar to the pacific

analysis of the tsunami generated by the mw 7 8 1906 san francisco earthquake we examine possible sources of a small tsunami produced by the 1906 san francisco earthquake recorded at a single tide gauge station situated at the opening to san francisco bay coseismic vertical displacement fields were calculated using elastic dislocation theory for geodetically constrained horizontal slip along a variety of offshore fault geometries propagation of the ensuing tsunami was calculated using a shallow water hydrodynamic model that takes into account the effects of bottom friction the observed amplitude and negative pulse of the first arrival are shown to be inconsistent with small vertical displacements 4 6 cm arising from pure horizontal slip along a continuous right bend in the san andreas fault offshore the primary source region of the tsunami was most likely a recently recognized 3 km right step in the san andreas fault that is also the probable epicentral region for the 1906 earthquake tsunami models that include the 3 km right step with pure horizontal slip match the arrival time of the tsunami but underestimate the amplitude of the negative first arrival pulse both the amplitude and time of the first arrival are adequately matched by using a rupture geometry similar to that defined for the 1995 m w moment magnitude 6 9 kobe earthquake i e fault segments dipping toward each other within the stepover region 83 dip intersecting at 10 km depth and a small component of slip in the dip direction rake 172 analysis of the tsunami provides confirming evidence that the 1906 san francisco earthquake initiated at a right step in a right lateral fault and propagated bilaterally suggesting a rupture initiation mechanism similar to that for the 1995 kobe earthquake

interdecadal changes of surface temperature since the late nineteenth century we present global fields of decadal annual surface temperature anomalies referred to the period 1951 1980 for each decade from 1881 1890 to 1981 1990 and for 1984 1993 in addition we show decadal calendar seasonal anomaly fields for the warm decades 1936 1945 and 1981 1990 the fields are based on sea surface temperature sst and land surface air temperature data the ssts are corrected for the pre world war ii use of uninsulated sea temperature buckets and incorporate adjusted satellite based ssts from 1982 onward our results extend those published in the 1990 intergovernmental panel on climate change scientific assessment and its 1992 supplement we assess the impact of various sources of error in the fields despite poor data coverage initially and around the two world wars the generally cold end of the nineteenth century and start to the twentieth century are confirmed together with the substantial warming between about 1920 and 1940 slight cooling of the northern hemisphere took place between the 1950s and the mid 1970s although slight warming continued south of the equator recent warmth has been most marked over the northern continents in winter and spring but the 1980s were warm almost everywhere apart from greenland the northwestern atlantic and the midlatitude north pacific parts of the middle to high latitude southern ocean may also have been cool in the 1980s but in this area the 1951 1980 climatology is unreliable the impact of the satellite data is reduced because the record of blended satellite and in situ sst is still too short to yield a climatology from which to calculate representative anomalies reflecting climatic change in the southern ocean however we propose a method of using existing satellite data in a step toward this target the maps are condensed into global and hemispheric decadal surface temperature anomalies we show the sensitivity of these estimated anomalies to alternative methods of compositing the spatially incomplete fields running decadal zonal means and annual global and hemispheric time series are also shown finally we discuss some salient features in terms of observed atmospheric circulation changes and of the results of climate model integrations with increasing atmospheric greenhouse gases

multiscale variabilities in global sea surface temperatures and their relationships with tropospheric climate patterns el nino southern oscillation enso is a global phenomenon with significant phase propagation within and between basins this is captured and described in the first mode of a complex empirical orthogonal function ceof analysis of sea surface temperature anomaly ssta from the midnineteenth century through 1991 the global enso from the ssta data plus a linear trend everywhere are subsequently removed in order to consider other global modes of variability uncontaminated by the intra and interbasin effects of enso an ordinary eof analysis of the ssta residuals reveals three non enso modes of low frequency variability that are related to slow oceanic and climate signals described in the literature the first two modes have decadal to multidecadal timescales with high loadings in the pacific they bear some spatial similarities to the enso pattern but are broader more intense at high latitudes and differ in the time domain a ceof analysis confirms that they are not merely the phase related components of a single mode and that all three modes are without significant phase propagation the third mode is a multidecadal signal with maximal realization in the extratropical north atlantic southeast of greenland it is consistent with studies that have documented connections between north atlantic ssta and the tropospheric north atlantic oscillation nao all three ssta modes have midtropospheric associations related to previously classified northern hemisphere teleconnection patterns the relationships between ssta modes and tropospheric patterns are consistent with the ocean atmosphere interactions discussed in previous studies to explain low frequency climate oscillations in the north pacific and north atlantic sectors the first three leading modes of non enso ssta are most related to the tropospheric patterns of the pacific north american the north pacific and the arctic oscillations ao respectively the 500 hpa pattern associated with the third ssta mode also bears similarities to the nao in its atlantic sector this north atlantic mode has a region of high positive ssta loadings in the gulf of alaska which appear to be connected to the north atlantic ssta by a tropospheric bridge effect in the ao

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

observed evidence of an impact of the antarctic sea ice dipole on the antarctic oscillation abstracta lagged maximum covariance analysis mca is applied to investigate the linear covariability between monthly sea ice concentration sic and 500 mb geopotential height z500 in the southern hemisphere sh the dominant signal is the atmospheric forcing of sic anomalies throughout the year but statistically significant covariances are also found between austral springtime z500 and prior sic anomalies up to four months earlier the mca pattern is characterized by an antarctic dipole adp like pattern in sic and a positively polarized antarctic oscillation aao in z500 such long lead time covariance suggests the forcing of the aao by persistent adp like sic anomalies the leading time of sic anomalies provides an implication for skillful predictability of springtime atmospheric variability

episodic tectonic subsidence of late holocene salt marshes northern oregon central cascadia margin salt marsh subsurface deposits 0 4 m depth in netarts bay a small coastal lagoon of northern oregon record six events of marsh burial in the last several thousand years five of the buried marsh surfaces show sharp nonerosional upper contacts with either anomalous sand layers tsunami deposits or tidal flat mud deposits these sequences indicate episodic abrupt subsidence of the marsh surfaces to low intertidal levels in contrast lower marsh contacts with underlying intertidal muds are gradational indicating gradual uplift and development of the marsh three independent measures of deposit elevation relative to mean tidal level percent organics diatom assemblages and percent eolian sand have been used to estimate vertical displacements of marsh surfaces abrupt subsidence displacements of 1 1 5 m alternate with gradual uplift displacements of the order of 0 5 1 0 m the vertical tectonic movements are interpreted to reflect coseismic strain release abrupt subsidence following interseismic strain accumulation gradual uplift associated with interplate coupling between the juan de fuca plate and the north american plate in the cascadia subduction zone recurrence intervals between subsidence events range from possibly less than 300 years to at least 1000 years with the last dated event likely occurring 300 400 radiocarbon years before present rcybp significant 14c age overlaps of at least four subsidence events recorded at netarts and reported for southern washington and other northern oregon bays at 300 500 1000 1300 1400 1800 and 3000 3300 rcybp suggest the potential for event synchroneity over at least 200 km of the central part of the cascadia subduction zone additional work is needed to test the synchroneity of these episodic events of coseismic subsidence

late holocene rupture of the northern san andreas fault and possible stress linkage to the cascadia subduction zone we relate the late holocene northern san andreas fault nsaf paleo seismic history developed using marine sediment cores along the northern california continental margin to a similar dataset of cores collected along the cascadia margin including channels from barclay canyon off vancouver island to just north of mon terey bay stratigraphic correlation and evidence of synchronous triggering imply earthquake origin and both temporal records are compatible with onshore paleoseis mic data in order to make comparisons between the temporal earthquake records from the nsaf and cascadia we refine correlations of southern cascadia great earth quakes including the land paleoseismic record along the nsaf during the last 2800 yr 15 turbidites including one likely from the great 1906 earthquake establish an average repeat time of 200 yr similar to the onshore value of 240 yr the combined land and marine paleoseismic record from the southern cascadia subduction zone includes a similar number of events during the same period while the average recurrence interval for full margin cascadia events is 520 yr the southern cascadia margin has a repeat time of 220 yr similar to that of the nsaf thirteen of the 15 nsaf events were preceded by cascadia events by 0 80 yr averaging 25 45 yr as compared to 80 400 yr by which cascadia events follow the nsaf based on the temporal association we model the coseismic and cumulative post seismic deformation from great cascadia megathrust events and compute related stress changes along the nsaf in order to test the possibility that cascadia earth quakes triggered the penultimate and perhaps other nsaf events the coulomb fail ure stress cfs resulting from viscous deformation related to a cascadia earthquake over 60 yr does not contribute significantly to the total cfs on the nsaf however the coseismic deformation increases cfs on the northern san andreas fault nsaf b y up to about 9 bars offshore of point delgada most likely enough to trigger that fault to fail in north to south propagating ruptures

response of a small oregon estuary to coseismic subsidence and postseismic uplift in the past 300 years the sixes river estuary south coastal oregon sits above the locked portion of the cascadia subduction zone which intermittently releases in subduction zone earthquakes one such cascadia earthquake 300 years ago caused subsidence and a tsunami at the sixes estuary the subsidence raised the river9s base level resulting in an 3 km upstream shift of the head of tide of the estuary at the upper end of the expanded estuary more than 4 m of overbank sediment was deposited in the first decades or century after subsidence subsequent incision through the overbank deposits accompanied the gradual emergence of the estuary and attendant downstream shift of the head of tide as relative sea level fell in response to interseismic uplift

nonlinear modes of north american winter climate variability derived from a general circulation model simulation abstract nonlinear principal component analysis nlpca via a neural network nn approach was applied to an ensemble of six 47 yr simulations conducted by the canadian centre for climate modelling and analysis cccma second generation atmospheric general circulation model agcm2 each simulation was forced with the observed sea surface temperature from the global sea ice and sea surface temperature dataset gisst from january 1948 to november 1994 the nlpca modes reveal nonlinear structures in both the winter 500 mb geopotential height z500 anomalies and surface air temperature sat anomalies over north america with asymmetric spatial anomaly patterns during the opposite phases of an nlpca mode only during its negative phase is the first nlpca mode related to the el nino southern oscillation enso the positive phase is related to a weakened jet stream spatial patterns of the nlpca mode for the z500 anomalies generally agree with those for the sat anomalies nonlinear canonical correlation

the dependence of caribbean rainfall on the interaction of the tropical atlantic and pacific oceans abstract seasonally stratified analyses of rainfall anomalies over the intra americas sea and surrounding land areas and of onset and end dates of the central american rainy season show that the variability of the tropical atlantic sea surface temperature anomaly ssta is more strongly associated with rainfall over the caribbean and central america than is tropical eastern pacific ssta seasonal differences include the importance of antisymmetric configurations of tropical atlantic ssta in the dry season but not in the rainy season both oceans are related to rainfall but the strength of the rainfall response appears to depend on how ssta in the tropical atlantic and eastern pacific combine the strongest response occurs when the tropical atlantic is in the configuration of a meridional dipole antisymmetric across the itcz and the eastern tropical pacific is of opposite sign to the tropical north atlantic when the tropical north atlantic and tropical pacific are of the same sign the rainfall respons

a model of the earthquake cycle along the san andreas fault system for the past 1000 years 1 we simulate 1000 years of the earthquake cycle along the san andreas fault system by convolving best estimates of interseismic and coseismic slip with the green s function for a point dislocation in an elastic plate overlying a viscoelastic half space interseismic slip rate is based on long term geological estimates while fault locking depths are derived from horizontal gps measurements coseismic and postseismic deformation is modeled using 70 earthquake ruptures compiled from both historical data and paleoseismic data this time dependent velocity model is compared with 290 present day geodetic velocity vectors to place bounds on elastic plate thickness and viscosity of the underlying substrate best fit models rms residual of 2 46 mm yr require an elastic plate thickness greater than 60 km and a substrate viscosity between 2 1018 and 5 1019 pa s these results highlight the need for vertical velocity measurements developed over long time spans 20 years our numerical models are also used to investigate the 1000 year evolution of coulomb stress stress is largely independent of assumed rheology but is very sensitive to the slip history on each fault segment as expected present day coulomb stress is high along the entire southern san andreas because there have been no major earthquakes over the past 150 300 years animations s1 and s2 of the time evolution of vector displacement and coulomb stress are available as auxiliary material

timing of late holocene paleoearthquakes on the northern san andreas fault at the fort ross orchard site sonoma county california paleoseismic trenching within fort ross state historic park provides data on the late holocene rupture history of the north coast segment of the northern san andreas fault the 1906 earthquake ruptured through the fort ross orchard site which is characterized by a narrow shutter ridge and associated linear trough containing latest holocene sediments trenches across the northeast facing fault scarp exposed sediments interpreted as scarp derived colluvium and possible fissure fill deposits and tentative upward fault truncations that provide evidence of three possible surface ruptures prior to 1906 coarse grained scarp derived colluvial sediments were deposited after individual surface rupturing earthquakes that predate the 1906 rupture radiocarbon analyses of 31 detrital radiocarbon samples collected from the colluvial deposits constrain the timing of earthquakes over the past approximately 1000 years based on stratigraphic ordering and a statistical comparison of radiocarbon dates using the oxcal program we estimate at a 95 confidence level that three pre 1906 surface ruptures at the orchard site occurred at a d 1660 1812 a d 1220 1380 and a d 1040 1190 previous trenches at the nearby fort ross archae camp site are consistent with these dates and further suggest the occurrence of an earlier event between a d 555 and 950 collectively the fort ross orchard and archae camp sites suggest pre 1906 ruptures at a d 1660 1812 a d 1220 1380 a d 1040 1190 and a d 555 950 the time windows for these ruptures are consistent with results from other sites on the north coast segment of the san andreas fault however additional information on the late holocene history of rupture events on adjacent fault segments is needed to evaluate whether the long term behavior of the san andreas fault involves a mix of large 1906 type ruptures and shorter segment specific ruptures

el nino la nina and the nonlinearity of their teleconnections the paradigm of an atmospheric system varying linearly with respect to extreme phases of the el nino southern oscillation is questioned it is argued that the global response to tropical pacific sea surface temperature forcing will be inherently nonlinear a physical basis for this intrinsic nonlinearity is the thermodynamic control on deep convection climate statistics for warm and cold events of the tropical pacific are analyzed separately for the northern winter periods during 1950 96 composite analysis of 500 mb heights reveal planetary scale teleconnection patterns as noted in earlier studies a new result is the evidence for an appreciable 358 longitude phase shift between the warm and cold event circulation composites and the two wave trains appear to have different tropical origins a large nonlinear component in north american surface climate anomalies is also found which is consistent with such a phase shift in teleconnections in the tropics rainfall anomalies also show evidence of nonlinear behavior the maximum rain anomalies along the equator are located east of the date line during warm events but west of the date line during cold events the interpretation of this behavior is complicated however by the fact that composite warm event sst anomalies are not the exact inverse of their cold event counterparts idealized atmospheric general circulation model agcm experiments are performed in order to test the question of whether the observed nonlinearity is an intrinsic property of the atmospheric system the model is forced with a composite sst anomaly that undergoes a realistic seasonally varying enso life cycle as described by e rasmusson and t carpenter both positive and negative phases of the sst anomaly are used and a 40 member ensemble of warm and cold event model simulations is conducted a nonlinear climate response in the agcm is found that closely resembles the observed composites including a shift in the equatorial positions of the maxmium rain responses and a phase shift of teleconnection patterns in the upper troposphere barotropic model experiments indicate that the inherent nonlinearity in the tropical rain response may itself be responsible for the phase shift in the extratropical teleconnection patterns

a comparative study of sea level reconstruction techniques using 20 years of satellite altimetry data sea level reconstructions extend spatially dense data sets such as those from satellite altimetry by decomposing the data set into basis functions and fitting those functions to in situ tide gauge measurements with a longer temporal record we compare and evaluate two methods for reconstructing sea level through an idealized study the compared sea level reconstruction methods differ in the technique for calculating basis functions i e empirical orthogonal functions eofs versus cyclostationary eofs cseofs reconstructions are created using archiving validation and interpretation of satellite oceanographic aviso satellite altimetry data and synthetic tide gauges synthetic tide gauge records are simulated using historical distributions and real high frequency signal to test reconstruction skill the cseof reconstructions show high skill in reproducing variations in global mean sea level gmsl and ocean climate indices and are affected less by both limited tide gauge distribution and added high frequency tide gauge signal than eof reconstructions typically cseof reconstructions slightly underestimate sea level amplitudes while eof reconstructions overestimate sea level amplitudes in some cases significantly both of these results are accentuated with decreasing quality of the synthetic tide gauge data set additionally we investigate how the reconstructions differ when reconstructing with more of the variance retained in the basis functions increasing the variance explained by the basis functions from 70 to 90 reduces the efficacy of an eof reconstruction to reproduce common ocean indices when noise is included in the tide gauge data sets these results show that in the idealized comparative cases examined the cseof method of sea level reconstruction creates more robust reconstructions especially when less than ideal tide gauge data are used

estimation of regional sea level change in the pearl river delta from tide gauge and satellite altimetry data the present study proposes a reconstruction of regionally consistent sea level anomalies in the pearl river delta prd over the period 1959 2011 spatial empirical orthogonal functions eofs derived from satellite altimetry dataset and the corresponding time series of tide gauge records were combined to generate regional sea level anomalies based on these datasets regionally consistent sea level anomalies rcsla are reconstructed using a dimension reducing method known as principal components analysis the results show that the accuracy of reconstruction is sensitive to the number of the available tide gauge records however no significantly effect of the length of the records is observed the results also indicate that the eof reconstruction method addresses issues such as the relatively short term coverage of satellite altimetry data and the sparse and discontinuous nature of tide gauge records demonstrating the applicability of this technique in investigation of long term sea level change both river flow and el nino event have considerable impacts on sea level variability in the prd c 2014 elsevier ltd all rights reserved

some aspects of energy balance and tsunami generation by earthquakes and landslides tsunamis are generated by displacement or motion of large volumes of water while there are several documented cases of tsunami generation by volcanic eruptions and landslides most observed tsunamis are attributed to earthquakes kinematic models of tsunami generation by earthquakes where specified fault size and slip determine seafloor and sea surface vertical motion quantitatively explain far field tsunami wave records on the other hand submarine landslides in subduction zones and other tectonic settings can generate large tsunamis that are hazardous along near source coasts furthermore the ongoing exploration of the oceans has found evidence for large paleo landslides in many places not just subduction zones thus we want to know the relative contribution of faulting and landslides to tsunami generation for earthquakes only a small fraction of the minimum earthquake energy less than 1 for typical parameter choices for shallow underthrusting earthquakes can be converted into tsunami wave energy yet this is enough energy to generate terrible tsunamis for submarine landslides tsunami wave generation and landslide motion interact in a dynamic coupling the dynamic problem of a 2 d translational slider block on a constant angle slope can be solved using a green s function approach for the wave transients the key result is that the largest waves are generated when the ratio of initial water depth above the block to downslope vertical drop of the block h 0 w sin is less than 1 the conversion factor of gravitational energy into tsunami wave energy varies from 0 for a slow velocity slide in deep water to about 50 for a fast velocity slide in shallow water and a motion abruptly truncated to compare maximum tsunami wave amplitudes in the source region great earthquakes produce amplitudes of a few meters at a wavelength fixed by the fault width of 100 km or so for submarine landslides tsunami wave heights as measured by b block height are small for most of the parameter regime however for low initial dynamic friction and values of h 0 w sin less than 1 tsunami wave heights in the downslope and upslope directions reach b and b 4 respectively wavelengths of these large waves scale with block width for significant submarine slides the value of b can range from meters up to the kilometer scale thus the extreme case of efficient tsunami generation by landslides produces dramatic hazards scenarios

sea surface temperature variability in coastal areas of the northeastern pacific related to the el nino southern oscillation and the pacific decadal oscillation we examined monthly time series 1950 to 1999 of sea surface temperature sst anomalies in 47 quadrants 2 2 along the coast of north america and their relation to the el nino southern oscillation enso and the pacific decadal oscillation pdo we used the multivariate enso index mei and the pdo index pdoi and assumed a linear interaction of the mechanisms behind their interannual variations then we examined sst anomalies as functions of mei and pdoi using multiple linear regression mlr on average enso influence decreases poleward but is still dominant at 31 n northward the pdo signal dominates mlr was also applied to selected sea level height slh series enso effects on slh were clear up to 48 n while pdo showed a weak effect only in the gulf of alaska this suggests that poleward of southern california enso effects may be largely restricted to the inshore coastal environment