structural characterization of natural loess and remolded loess under triaxial tests this paper characterizes the microstructural evolution of saturated natural loess from a site in jingyang china during triaxial test along two stress paths for comparison the same soil in remolded state is also characterized mercury intrusion porosimetry mip scanning electron microscopy sem and environmental scanning electron microscopy esem were used for the microstructure investigation results show that the microstructure of natural loess is similar to that of remolded loess before the consolidated undrained cu triaxial tests including conventional triaxial compression ctc test and reduced triaxial compression rtc test on the contrary their microstructures are different after the tests deeper examination shows that loading led to a significant change of inter aggregate pores without modifying the intra aggregate pores in addition the volume of inter aggregate pores after the rtc test is greater than that after the ctc test under the same consolidation stress the microstructure features of natural and remolded loess after the tests are further used to analyze the macro mechanical behavior for better understanding the relationship between them the results show that it is the cementation bonds of which breakage is influenced by stress path and confining pressure that play important roles in the strength and deformation behavior

eddy zonal flow feedback in the southern hemisphere abstract the variability of the zonal mean zonal wind in the southern hemisphere is studied using eof analysis and momentum budget diagnostics of ncep reanalysis data 1978 97 the leading eof of the zonal mean zonal wind is well separated from the remaining eofs and represents the north south movement of the midlatitude jet analysis of the momentum budget shows that a positive feedback between the zonal mean wind anomalies and the eddy momentum fluxes accounts for the unusual persistence of eof1 and plays an important role in the selection of the leading eof of midlatitude variability further analysis also shows a propagating feedback common to both eof1 and eof2 which is responsible for the poleward drift of wind anomalies with time the observations support the following feedback mechanism anomalous baroclinic wave activity is generated at the latitude of anomalous temperature gradient that by thermal wind coincides with the latitude of the anomalous zonal jet the net propagation of baroclinic

poleward stationary eddy heat transport by the tibetan plateau and equatorward shift of westerlies during northern winter the orographic effect of the tibetan plateau on atmospheric poleward heat transport is investigated using an atmospheric general circulation model the linear interference between the tibetan plateau induced winds and the eddy temperature field associated with the land sea thermal contrast is a key factor for enhancing the poleward stationary eddy heat transport specifically tibetan plateau induced stationary waves producenortherliesoverthecoldeasterneurasiancontinent leadingtoapolewardheattransport inanother hot spot of stationary eddy heat transport over the eastern north pacific tibetan plateau induced stationary waves transport relatively warm marine air northward in an experiment where the tibetan plateau is removed the poleward heat transport is mostly accomplished by transient eddies similar to the southern hemisphere in the presence of the tibetan plateau the enhanced stationary eddy heat transport is offset by a comparable reduction in transient eddy heat transport this compensation between stationary and transient eddy heat transport is seen in observed interannual variability both the model and observations indicate that an enhanced poleward heat transport by stationary waves weakens transienteddiesbydecreasingthemeridionaltemperaturegradientandtheassociatedwesterliesinmidlatitudes

the role of stationary waves in the maintenance of the northern annular mode as deduced from model experiments abstract the influence of stationary waves on the maintenance of the tropospheric annular mode am is examined in a simple global circulation model with perpetual january conditions the presented model experiments vary in the configurations of stationary wave forcing by orography and land sea heating contrasts all simulations display an am like pattern in the lower troposphere the zonal momentum budget shows that the feedback between eddies with periods less than 10 days and the zonal mean zonal wind is generally the dominating process that maintains the am the kinetic energy of the high frequency eddies depends on the stationary wave forcing where orographic forcing reduces and thermal forcing enhances it the ams in the model experiments differ in the superposed anomalous stationary waves and in the strength of the zonally symmetric component if only orographic stationary wave forcing is taken into account the mountain torque decelerates the barotropic wind anomaly and thus acts to weaken the a

interactions of synoptic and planetary waves scale dependent forcing of a gcm abstract in order to better understand planetary wave synoptic wave interactions in the atmosphere and to develop a tool for further studies the authors have applied a wavenumber dependent external forcing to a general circulation model gcm the forcing constrains various length scales of the gcm to be close to those in the evolving analyses of the european centre for medium range weather forecasts and the national centers for environmental prediction the forcing acts either on the planetary waves pw defined as zonal wavenumbers 0 5 the synoptic waves sw defined as zonal wavenumbers 6 20 the synoptic waves plus the zonal mean sw0 or the synoptic waves plus the zonal mean and wavenumber 1 sw01 the form of the forcing is a linear relaxation to the evolving analyses with a time constant of 8 h this forcing is applied only to the temperature and vorticity equations of the gcm which has a spectral truncation of t42 control integrations of length 30 days have been run starting on 15 dece

spatial thickness variability of the 2011 tohoku oki tsunami deposits along the coastline of sendai bay abstract soon after the 2011 tohoku oki event approximately 1300 tsunami deposit thickness data were collected spatially by the governors to cover the entire tsunami affected area sendai plain along the sendai bay coastline this dataset along with high resolution and high precision data of flow depth and pre tsunami and post tsunami elevation enables us first to conduct a direct comparison of the sedimentation and erosion volumes as well as the tsunami hydrodynamic features e g flow depth and sediment thickness the total balance of sedimentation and erosion volumes revealed that the volume of tsunami deposited sediments can be explained roughly using the erosion volumes at the beach and sand dunes for sandy deposits and at rice paddy fields for muddy deposits both the flow depth and sediment thickness showed positive correlations with the distance from the shoreline while sediment thickness is no correlation to the elevation except in the zone closest to the shoreline where erosion is present in addition a statistical relation was found between the flow depth and sediment thickness in fact the frequency distribution of sediment concentration defined here as the sediment thickness divided by the maximum flow depth at each survey site fits well with the logarithmic normal distribution with geometric average of about 2 this fit indicates that the tsunami deposits on the sendai plain can be explained generally if we simply assume that the saturated level of the sediment concentration in the flow is limited to about 2 on average irrespective of the grain size such a simple explanation might be applicable only for the tsunami deposits on the sendai plain because the topography is remarkably flat and low therefore the tsunami inundation process is relatively simple nevertheless a possible relation between tsunami flow depth and sediment thickness suggested here would be very useful to consider the ideal sedimentary process of the tsunami deposits and to improve forward and inverse modelings

the solsticial pause on mars 2 modelling and investigation of causes 2015 elsevier inc the martian solsticial pause presented in a companion paper lewis et al this issue icarus was investigated further through a series of model runs using the uk version of the lmd uk mars global climate model it was found that the pause could not be adequately reproduced if radiatively active water ice clouds were omitted from the model when clouds were used along with a realistic time dependent dust opacity distribution a substantial minimum in near surface transient eddy activity formed around solstice in both hemispheres the net effect of the clouds in the model is by altering the thermal structure of the atmosphere to decrease the vertical shear of the westerly jet near the surface around solstice and thus reduce baroclinic growth rates a similar effect was seen under conditions of large dust loading implying that northern midlatitude eddy activity will tend to become suppressed after a period of intense flushing storm formation around the northern cap edge suppression of baroclinic eddy generation by the barotropic component of the flow and via diabatic eddy dissipation were also investigated as possible mechanisms leading to the formation of the solsticial pause but were found not to make major contributions zonal variations in topography were found to be important as their presence results in weakened transient eddies around winter solstice in both hemispheres through modification of the near surface flow the zonal topographic asymmetry appears to be the primary reason for the weakness of eddy activity in the southern hemisphere relative to the northern hemisphere and the ultimate cause of the solsticial pause in both hemispheres the meridional topographic gradient was found to exert a much weaker influence on near surface transient eddies

orographic influences on the distribution and generation of atmospheric variability in a gcm abstract the effect of large scale mountains on atmospheric variability is studied in a series of gcm experiments in which a single mountain is varied in height from 0 to 4 km high frequency 30 days variability are largest in the jet exit region while the intermediate frequency 7 30 days variability has its maximum upstream of the mountain where it exhibits enhanced equatorward propagation high and intermediate frequencies change from zonal wave trains to localized wave packets as orographic forcing is increased but they retain their characteristic scale and frequency the dominant pattern of low frequency is variability changes from a zonally symmetric oscillation for which transient eddy zonal flow interaction is the dominant mechanism to a more localized oscillation of the jet downstream of the mountain the transient eddy forcing still plays a significant role in maintaining the variations of this more localized jet however the total amount of wave

surface deformation and coherence measurements of kilauea volcano hawaii from sir c radar interferometry the shuttle imaging radar c x synthetic aperture radar sir c x sar radar on board the space shuttle endeavor imaged kilauea volcano hawaii in april and october 1994 for the purpose of measuring active surface deformation by the methods of repeat pass differential radar interferometry observations at 24 cm l band and 5 6 cm c band wavelengths were reduced to interferograms showing apparent surface deformation over the 6 month interval and over a succession of 1 day intervals in october a statistically significant local phase signature in the 6 month interferogram is coincident with the pu u o o lava vent interpreted as deformation the signal implies centimeter scale deflation in an area several kilometers wide surrounding the vent peak deflation is roughly 14 cm if the deformation is purely vertical centered southward of the pu u o o caldera delays in the radar signal phase induced by atmospheric refractivity anomalies introduce spurious apparent deformation signatures at the level of 12 cm peak to peak in the radar line of sight direction though the phase observations are suggestive of the wide area deformation measured by global positioning system gps methods the atmospheric effects are large enough to limit the interpretation of the result it is difficult to characterize centimeter scale deformations spatially distributed over tens of kilometers using differential interferometry without supporting simultaneous spatially distributed measurements of refractivity along the radar line of sight studies of the interferometric correlation of images acquired at different times show that l band is far superior to c band in the vegetated areas even when the observations are separated by only 1 day these results imply longer wavelength instruments are more appropriate for studying surfaces by repeat pass observations

dependence of the annular mode in the troposphere and stratosphere on orography and land sea heating contrasts 1 using an idealized general circulation model we explore the influence of orography and land sea heating contrasts on the development of annular modes am under perpetual january conditions in the troposphere model experiments with different stationary wave forcing all show an internally induced am but with significantly different amplitudes only the combined forcing of orography and land sea heating contrast leads to a localization of the am similar to the north atlantic oscillation and additionally to a stratospheric am and its downward propagation a tropospheric feedback mechanism between the anomalies of zonal mean wind and stationary waves applies in the simulation with the combined forcing only where the coupling of orographically and thermally forced waves reproduces the observed stationary waves and where the simulated diabatic heating supports the feedback mechanism in contrast transient forcing dominates the variability in the experiments without orography comparable to the southern am

impacts of northern tibetan plateau on east asian summer rainfall via modulating midlatitude transient eddies roles of the tibetan plateau tp in forming and changing the seasonal asian climate system have been widely explored however little is known about modulation effects of the tp on extratropical transient eddies tes and subsequent synoptic responses of the east asian rainfall in this study the community atmospheres model version 5 1 coupled with a slab ocean model is employed to highlight the important role of the tp in regulating the upper tropospheric transient wave train comparison between sensitivity experiments with and without the tp shows that the northern tp excites a strong anomalous anticyclone which shifts the upper level east asian westerly jet northward and helps transfer barotropic and baroclinic energy from the mean flow to the synoptic te flow the transient wave train is primarily shifted northward by northern tp and is forced to propagate southeastward along the eastern flank of the tp until reaching eastern china before the strengthening of monsoonal southerlies the tp modulated transient wave train cools the troposphere which decreases the static stability over northern china meanwhile the associated anomalous warm advection induces ascending motion leading to excessive rainfall by releasing unstable energy as the southerly strengthens due to the southeastward propagation of the wave train anomalous heavy rainfall subsequently appears over eastern china from north to south which increases day to day rainfall variation in this region additionally occurrence of this upper tropospheric transient wave train associated with low level southerly peak is substantially increased by northern tp

elemental and mineralogical analysis of marine and coastal sediments from phra thong island thailand insights into the provenance of coastal hazard deposits abstract sediment records left by coastal hazards e g tsunami and or storms may shed light on the sedimentary and hydrodynamic processes happening during such events modern onshore and offshore sediment samples were compared with the 2004 indian ocean tsunami three palaeotsunami and a 2007 storm deposit from phra thong island thailand to determine provenance relationships between these coastal overwash deposits sedimentological and stratigraphic characteristics are generally inadequate to discriminate tsunami and storm deposits so a statistical approach including cluster analysis principal component analysis and discriminant function analysis was used based on grain size mineralogy and trace element geochemistry the mineral content and trace element geochemistry are statistically inadequate to distinguish the provenance of the modern storm and tsunami deposits at this site but the mean grain size can potentially discriminate these overwash deposits the 2007 storm surge deposits were most likely sourced from the onshore sediment environment whereas all four tsunami units statistically differ from each other indicating diverse sediment sources our statistical analyses suggest that the 2004 tsunami deposit was mainly derived from nearshore marine sediments the uppermost palaeotsunami deposit was possibly derived from both onshore and nearshore materials while the lower palaeotsunami deposits showed no clear evidence of their sediment sources such complexity raises questions about the origin of the sediments in the tsunami and storm deposits and strongly suggests that local context and palaeogeography are important aspects that cannot be ignored in tsunami provenance studies

monitoring of land subsidence and ground fissures in xian china 2005 2006 mapped by sar interferometry the city of xian china has been experiencing significant land subsidence and ground fissure activities since 1960s which have brought various severe geohazards including damages to buildings bridges and other facilities monitoring of land subsidence and ground fissure activities can provide useful information for assessing the extent of and mitigating such geohazards in order to achieve robust synthetic aperture radar interferometry insar results six interferometric pairs of envisat asar data covering 2005 2006 are collected to analyze the insar processing errors firstly such as temporal and spatial decorrelation error external dem error atmospheric error and unwrapping error then the annual subsidence rate during 2005 2006 is calculated by weighted averaging two pairs of d insar results with similar time spanning lastly gps measurements are applied to calibrate the insar results and centimeter precision is achieved as for the ground fissure monitoring five insar cross sections are designed to demonstrate the relative subsidence difference across ground fissures in conclusion the final insar subsidence map during 2005 2006 shows four large subsidence zones in xian hi tech zones in western eastern and southern suburbs of xian city among which two subsidence cones are newly detected and two ground fissures are deduced to be extended westward in yuhuazhai subsidence cone this study shows that the land subsidence and ground fissures are highly correlated spatially and temporally and both are correlated with hi tech zone construction in xian during the year of 2005 2006

frictional heating in global climate models abstract a new finite difference formulation of the frictional heating associated with atmospheric vertical momentum diffusion is proposed it is derived from the requirement that according to the no slip condition the sum of internal and kinetic energy of a fluid column is not changed by surface friction the present form is designed to be implemented along with the hybrid coordinate differencing scheme of simmons and burridge the effects of incorporating frictional heating in general circulation models gcms of the atmosphere are assessed by analyzing representative long term january simulations performed with an idealized gcm the model employs the proposed discretization of vertical terms as well as recently derived horizontal diffusion and dissipation forms for the conventional definition of a gcm with no frictional heating the climatological global energy budget yields a spurious thermal forcing of about 2 w m 2 in the equivalent new model definition this shortcoming is reduced by two orders

ostracodes reveal the sea bed origin of tsunami deposits 1 in rikuzentakata city ostracode assemblages in sediment deposited by the tohoku oki earthquake and tsunami of 11 march 2011 revealed that the sediment was derived from the seafloor from at least 9 m water depth and was transported inland more than 1 km the tsunami wave height at this location was higher than 10 m four hundred fifty seven modern ostracode assemblages were used in the modern analogue technique to estimate the depth source of the tsunami deposited assemblages the application of this method to paleo tsunami deposits may provide insight into past tsunami wave height and potentially earthquake slip and magnitude

the displacement field of the landers earthquake mapped by radar interferometry geodetic data obtained by ground or space based techniques can be used to infer the distribution of slip on a fault that has ruptured in an earthquake although most geodetic techniques require a surveyed network to be in place before the earthquake1 3 satellite images when collected at regular intervals can capture co seismic displacements without advance knowledge of the earthquake s location synthetic aperture radar sar interferometry first introduced4 in 1974 for topographic mapping5 8 can also be used to detect changes in the ground surface by removing the signal from the topography9 10 here we use sar interferometry to capture the movements produced by the 1992 earthquake in landers california11 we construct an interferogram by combining topographic information with sar images obtained by the ers 1 satellite before and after the earthquake the observed changes in range from the ground surface to the satellite agree well with the slip measured in the field with the displacements measured by surveying and with the results of an elastic dislocation model as a geodetic tool the sar interferogram provides a denser spatial sampling 100 m per pixel than surveying methods1 3 and a better precision 3 cm than previous space imaging techniques12 13

a diagnostic study of cold air outbreaks over south america midlatitude disturbances such as intense cold fronts and cutoff lows are a very important cause of severeweather events over the southern part of south america particularly during the austral winter months behind cold fronts cold air from higher latitudes is forced to flow equatorward to the east of the andes occasionally fronts might produce cold surges in tropical latitudes with freezing temperatures referred as to geadas in portuguese over crop growing areas of southern southeastern and central brazil the structure and dynamical processes of winter synoptic scale waves associated with cold surges over south america are documented in this paper it is shown that the rotated extended empirical orthogonal function technique is capable of extracting well defined regional patterns from 850 hpa meridional wind perturbation fields over south america waves behave very differently in the lower and middle troposphere while upperlevel waves propagate northeastward as they cross the andes evolving in a manner consistent with the concept of rossby wave dispersion at lower levels waves tend to conform to the shape of the mountain range in agreement with the theory of topographic rossby waves however it was found that cold surges do not seem to result from the generation of rotationally trapped waves significant differences have been found between synoptic scale patterns associated with cold surges over extratropical south america no geada composites and synoptic scale patterns associated with major coldair outbreaks that produce extreme low temperatures at tropical regions geada composites while both surges are characterized by a long wave pattern consisting of a cyclonic perturbation over south america and anticyclonic perturbation behind over the southern pacific ocean at the early stages of geada composites two additional features were identified a subpolar and subtropical short wave pattern the presence of the upperlevel subtropical cyclonic perturbation is associated with the subtropical jetstream location farther north which would facilitate the equatorward penetration of frontal systems in addition this cyclonic perturbation enhances rising motion at subtropical and tropical latitudes that is associated with a well defined secondary circulation with its descending branch over central argentina it is shown that this configuration favors the rapid and equatorward penetration of the subpolar short wave trough the temperature decrease over southern brazil and the anticyclone intensification over central argentina thus the presence of the subtropical upper level feature plays a key role on the cold surge occurrence over tropical regions of south america

ostracods as tsunami tracers in holocene sequences this review analyses the ostracod record in holocene tsunami deposits using an overview of the 2004 indian ocean tsunami impact on its recent populations and the associated tsunamigenic deposits together with results from numerous investigations of other holocene sequences different features such as the variability of the local assemblages population density species diversity age population structure e g percentages of adults and juvenile stages or taphonomical signatures suggest that these microorganisms may be included amongst the most promising tracers of these high energy events in marshes lakes lagoons or shallow marine areas

annular modes in the extratropical circulation part i month to month variability the leading modes of variability of the extratropical circulation in both hemispheres are characterized by deep zonally symmetric or annular structures with geopotential height perturbations of opposing signs in the polar cap region and in the surrounding zonal ring centered near 458 latitude the structure and dynamics of the southern hemisphere sh annular mode have been extensively documented whereas the existence of a northern hemisphere nh mode herein referred to as the arctic oscillation ao has only recently been recognized like the sh mode the ao can be defined as the leading empirical orthogonal function of the sea level pressure field or of the zonally symmetric geopotential height or zonal wind fields in this paper the structure and seasonality of the nh and sh modes are compared based on data from the national centers for environmental prediction national center for atmospheric research reanalysis and supplementary datasets the structures of the nh and sh annular modes are shown to be remarkably similar not only in the zonally averaged geopotential height and zonal wind fields but in the mean meridional circulations as well both exist year round in the troposphere but they amplify with height upward into the stratosphere during those seasons in which the strength of the zonal flow is conducive to strong planetary wave mean flow interaction midwinter in the nh and late spring in the sh during these active seasons the annular modes modulate the strength of the lagrangian mean circulation in the lower stratosphere total column ozone and tropopause height over mid and high latitudes and the strength of the trade winds of their respective hemispheres the nh mode also contains an embedded planetary wave signature with expressions in surface air temperature precipitation total column ozone and tropopause height it is argued that the horizontal temperature advection by the perturbed zonal mean zonal wind field in the lower troposphere is instrumental in forcing this pattern a companion paper documents the striking resemblance between the structure of the annular modes and observed climate trends over the past few decades

northern hemisphere winter circulation associated with the north atlantic oscillation and stratospheric polar night jet the interannual variability of the atmospheric winter circulation as characterized by the geopotential height at 500 hpa and temperature at 850 hpa associated with the north atlantic oscillation nao and stratospheric polar night jet pnj is examined it is suggested that the wintertime atmospheric circulation related to the nao index can be separated into two different modes of variability one is a regional mode characterized by a meridional dipole type pattern in the 500 hpa geopotential height anomaly field over the atlantic region the other having more zonal structure extends over wider region of the northern hemisphere this is also related to the lower stratospheric polar night jet air temperature near the surface over the eastern part of the eurasian continent is more closely correlated with the above mentioned hemispheric mode of variability than the regional nao

on horizontal wind gradient variability from the stratosphere to the lower troposphere in the arctic 1 previous studies have demonstrated changes in vertical wind shear in recent decades with implications for upward propagating planetary waves the stratospheric polar vortex and tracer transport changes in vertical wind shear combined with horizontal gradients have also been shown to contribute to an increase in vertical gradients in tracer fields with important implications for vertical transport in order to explore the extent to which changes in vertical wind shear are reflected in changes to horizontal stirring we examine horizontal wind gradient fields from the stratosphere to the lower troposphere from 1979 to 2006 studied in particular are the spatial and temporal properties and trends for relative vorticity divergence strain and the okubo weiss criterion which monitors the competition between strain and vorticity dominated fields to illustrate how horizontal wind gradients have changed over the last several decades the results from this investigation show negative vorticity and strain anomalies during winter following 1998 associated with an increase in sudden stratospheric warmings and perturbations to the polar vortex noted in recent years spatial distributions for relative vorticity and strain fields exhibit coherent structures near the tropopause and middle stratosphere during fall and winter which are captured by the okubo weiss fields trend analyses highlight statistically significant trends in relative vorticity and okubo weiss fields during winter the results from this investigation demonstrate that statistically significant trends exist from the stratosphere to the lower troposphere it is hypothesized that the coupling from the lower troposphere to the upper atmosphere will be important in the development of our understanding of the response of sea ice concentrations to climate variability and change

radar interferometry and its application to changes in the earth s surface geophysical applications of radar interferometry to measure changes in the earth s surface have exploded in the early 1990s this new geodetic technique calculates the interference pattern caused by the difference in phase between two images acquired by a spaceborne synthetic aperture radar at two distinct times the resulting interferogram is a contour map of the change in distance between the ground and the radar instrument these maps provide an unsurpassed spatial sampling density 100 pixels km 2 a competitive precision 1 cm and a useful observation cadence 1 pass month 1 they record movements in the crust perturbations in the atmosphere dielectric modifications in the soil and relief in the topography they are also sensitive to technical effects such as relative variations in the radar s trajectory or variations in its frequency standard we describe how all these phenomena contribute to an interferogram then a practical summary explains the techniques for calculating and manipulating interferograms from various radar instruments including the four satellites currently in orbit ers 1 ers 2 jers 1 and radarsat the next chapter suggests some guidelines for interpreting an interferogram as a geophysical measurement respecting the limits of the technique assessing its uncertainty recognizing artifacts and discriminating different types of signal we then review the geophysical applications published to date most of which study deformation related to earthquakes volcanoes and glaciers using ers 1 data we also show examples of monitoring natural hazards and environmental alterations related to landslides subsidence and agriculture in addition we consider subtler geophysical signals such as postseismic relaxation tidal loading of coastal areas and interseismic strain accumulation we conclude with our perspectives on the future of radar interferometry the objective of the review is for the reader to develop the physical understanding necessary to calculate an interferogram and the geophysical intuition necessary to interpret it

northern hemisphere teleconnection patterns during extreme phases of the zonal mean circulation abstract regional climate anomalies associated with year to year changes in the tropospheric zonal mean zonal wind are examined this study focuses on the wintertime northern hemisphere extratropics and compares seasonal mean anomalies associated with to those associated with the el nino southern oscillation during the 1947 94 period dynamical model experiments indicate that a single zonal index characterized by out of phase anomalies at 35 and 55 n is of primary importance for zonal flow stationary wave interactions in the northern hemisphere extratropies such fluctuations in the zonal mean zonal flow are shown to occur independently of tropical sst variability consistent with earlier studies dynamical model experiments and regression analyses of the historical data indicate that such a zonal index explains a significant fraction of the wintertime stationary wave variability in several regions the principal centers of action reside within wave trains over the north pacific north american

the use of atmospheric relative angular momentum to diagnose the arctic oscillation abstract recent studies suggest that the north atlantic oscillation is a regional expression of the northern hemisphere annular mode however the lack of an apparent link between atlantic and pacific sectors questions the annular paradigm in any case the phenomenon is the largest and most fundamental mode of variability in the northern hemisphere troposphere being responsible for much of the warming in the northern hemisphere surface temperature the main aim of this study is to diagnose the northern hemisphere annular mode using an annular magnitude such as the relative angular momentum ram ram from 500 hpa to 200 hpa is computed for the polar cap using 60 longitude sectors as well as the whole cap from 55 to 90 n and for the period 1958 1998 using ncep ncar reanalysis data annual values of ram are then correlated to temperature and geopotential height at 200 500 and 850 hpa the artic region is dominated by very negative correlations for the northern hemisphere ram and for the six different ram sectors midlatitudes are dominated by positive correlation with intermittent or alternating significant regions not showing a regular annular pattern the pacific ocean area is only significantly correlated with the pacific ram sector since an annular pattern is characterized by its hemispheric symmetry two symmetric latitude rings are expected but only the polar one is detected the rest being incomplete due to the proximity of the grid points near the pole which can lead to artificial zonal symmetry all the calculations are repeated for ram from 45 to 65 n finding a similar pattern with lower correlations and less symmetry so the results do not support the annular paradigm understood as organized along latitude sectors but a hemispheric dimension cannot be excluded

dynamics of eddy driven low frequency dipole modes part iii meridional displacement of westerly jet anomalies during two phases of nao abstract in this paper the north south variability of westerly jet anomalies during the two phases of the north atlantic oscillation nao is examined in a theoretical model it is found that the north south variability of the zonal mean westerly anomaly results from the interaction between the eddy driven anomalous stationary waves with a dipole meridional structure nao anomalies and topographically induced climatological stationary waves with a monopole structure which is dependent upon the phase of the nao the westerly jet anomaly tends to shift northward during the positive nao phase but southward during the negative phase synoptic scale eddies tend to maintain westerly jet anomalies through the excitation of nao anomalies but the climatological stationary wave and its position relative to the eddy driven anomalous stationary wave appear to dominate the north south shift of westerly jet anomalies on the other hand it is shown that when the climatological stationary wave ridge is located downs

thermally driven and eddy driven jet variability in reanalysis two important dynamical processes influence the extratropical zonal wind field angular momentum transport by the thermally direct hadley circulation thermal driving t and momentum flux convergence by atmospheric waves eddies that develop in regions of enhanced baroclinicity eddy driving e the relationship between extratropical zonal wind variability and these driving processes is investigated using 40 yr european centre for medium range weather forecasts re analysis era 40 data indices representing the processes it and ie are defined based on vertically integrated diabatic heating and meridional convergence of the meridionalflux of zonal momentum by eddies respectively zonal wind signatures associated with these indices are identified via composite analysis in the atlantic sector zonal wind variability is mainly associated with momentum flux convergence by baroclinic eddies supporting the established view that the atlanticjetis primarilyeddydriven inthe pacificsector zonal windvariability isassociatedwith bothdriving processes evidence that the pacific jet is both thermally driven and eddy driven the thermally driven pacific signature reflects changes in jet strength intensity and longitudinal extent with some resemblance to the zonal wind anomalies of the pacific north america pna pattern the eddy driven signature reflects a latitudinal shift of the jet exit region in both sectors that resembles the zonal wind anomalies of the north atlantic oscillation nao or west pacific wp patterns

the seasonally varying effect of the tibetan plateau on northern hemispheric blocking frequency and amplitude the northern hemisphere atmospheric blocking is a primary weather and climate system that accompanies extreme cold spells and heat waves this study assesses effects of the tibetan plateau tp the largest continental mountain belt on the blocking frequency bf and amplitude ba with progressive tp uplift experiments from 0 to 100 using a coupled atmosphere ocean general circulation model the tp uplift increases the annual mean bf by 3 and 21 over the pacific and atlantic basins respectively a particular focus is placed on the seasonally distinct mechanism in the effects of tp uplift on the boreal winter and summer blockings during winter the tp uplift increases the bf over the active centers of both ocean basins via amplifying the eddy kinetic energy of stationary waves on the other hand in summer the tp uplift tends to shift the location of bf northward due to notable poleward displacement of the jet stream and transient eddy activities particularly over the atlantic compared to the considerable bf increase in both seasons the amplification of ba due to the tp uplift is much stronger in winter than in summer reaffirming the seasonally varying tp effect on the blocking further analyses reveal that in summer the tp uplift modulates more effectively the jet displacement than its strength leading more linear northward shift of jet and bf especially over the atlantic this study will contribute to advances in simulation and prediction of atmospheric blocking events

the 2011 tohoku oki tsunami three years on abstract the 2011 tohoku oki tsunami that devastated the pacific coast of tohoku japan was a turning point for modern research as a result of this event it was recognized that paleotsunami research is vital to help understand the size and recurrence interval of low frequency large tsunamis this paper reviews the progress of geological research on the 2011 tohoku oki tsunami and summarizes new questions that are arising out of this work for example recent work suggests that the landward extent and thickness of the sandy deposit as well as the presence or absence of marine microfossils in the sediment are most likely to be mainly controlled by the initial wave properties sediment source offshore bathymetry and onshore topography this in turn implies that there are certain relationships between the characteristics of a tsunami deposit and the wave properties and it may be possible to reconstruct the latter from the deposits offshore tsunami deposits related to the 2011 tohoku oki tsunami have also been well described this recent research indicates that sedimentation and erosion in inner bay and open ocean 20 m water depth locations can be in the order of several meters suggesting that the tsunami shear force was strong in the nearshore zone on the other hand sandy to muddy deposits a few centimeters thick were observed at about 100 to 6000 m water depth it is likely that the tsunami resulted in resuspension of sea bottom sediments and that suspended material flowed downslope as a turbidity current or suspended flow although many authors recognize the possibility that strong earthquake groundshaking might have also generated turbidity currents studies of the 2011 tohoku oki event have led researchers back to two of the fundamental issues of tsunami geology understanding the linkage between onshore and offshore sedimentation and erosion and establishing identification criteria for tsunami deposits moreover though beyond the issue of simple tsunami geology it is important for all researchers to communicate with governments and the general public in order to reduce future casualties by using risk assessments based on our understanding of infrequent large tsunamis

monitoring land subsidence in the southern part of the lower liaohe plain china with a multi track ps insar technique abstract the lower liaohe plain is one of the most important industrial zones in liaoning province china and activities here include oil and gas exploration aquaculture and salt production heavy land use may have contributed to the different magnitudes of land deformation in this region and this has been detrimental to the environment and economic construction projects in this zone in this paper we employ the permanent scatterer interferometry psi technique with l band alos palsar imagery data to monitor the annual land subsidence and produce accumulative time series maps for the years of 2007 to 2011 the unwrapped grid size was tested in order to recover the maximum deformation insar results from two adjacent tracks were merged by considering the offset over the overlapped area a ps standard deviation of 0 91 cm year was achieved in the vertical direction according to calculation from two independent ps results three kinds of land subsidence were analyzed quantitatively over the oil fields coastal zones and salt production areas some severe land subsidence regions were verified by field investigations

land subsidence and ground fissures in xi an china 2005 2012 revealed by multi band insar time series analysis abstract xi an china has been undergoing significant land subsidence along with ground fissure development these geohazards have brought about severe damages to buildings bridges and other facilities in order to warn of and mitigate disasters it is urgently necessary to obtain the latest rate extent and temporal evolution of land subsidence in xi an with multiple sar datasets as well as leveling gps and ground water level of aquifers we study and map the spatial and temporal evolution of land subsidence and ground fissures over xi an first 62 synthetic aperture radar sar images acquired by envisat alos and terrsar x during 2005 2012 are used to form three independent interferometric stacks to unveil the spatial and temporal variations of land subsidence and ground fissures by using the time series interferometric synthetic aperture radar insar technique gps and leveling measurements are applied to calibrate the insar results precision of our insar annual subsidence results is less than 9 mm we derive the east west and vertical components of the observed land deformation in 2009 using descending and ascending insar observations finding out that the horizontal component of land deformation cannot be ignored if the deformation is large or ground fissures are active second four main land subsidence zones are detected in xi an with an average subsidence rate of 50 mm a during 2005 2012 time series insar results indicate that land subsidence rates in xi an increased by 200 from 2005 2007 to 2008 2010 extending existing ground fissures third insar derived land subsidence correlates with the change in ground water level and seasonal variations in subsidence correlate with changes in ground water pumping last the consistency on the spatial temporal distribution variation between ground fissures and land subsidence could be drawn from the time series results and profile analysis shapes of subsiding zones follow the general trends of mapped ground fissures and main faults in an ene direction changes in the subsidence gradient are also observed over most of the ground fissures and faults subsidence triggered fissures can cause localized surface displacements aggravate localized subsidence discontinue the integrity of ground water flow and limit the horizontal spread of subsidence funnels with continuing mass construction projects in xi an monitoring ground deformation with satellite insar therefore can provide efficient means to image land subsidence movements of fissures and faults and the associated geohazards

distribution and generative mechanisms of ground fissures in china abstract in this study 5002 ground fissures in more than 1500 localities across 22 provinces in china are investigated and mapped to reveal their spatial distribution the distribution of these ground fissures in china exhibits six regular patterns assemblages in north china syngenesis in extensional basins clustering along fault zones distributing along geomorphic boundaries developed on the edge of subsidence areas and clustering in large and medium sized cities combined with regional gps numerical simulations physical model test and in sar monitoring the generative processes of ground fissures are analyzed and discussed in relationship to four mechanisms 1 deep dynamic tectonism controls on the location of ground fissures 2 intracontinental dynamic tectonism resulting in ground fissure assemblages 3 fault stress inducing formation of ground fissures and 4 groundwater overmining resulting in the reactivation and expansion of ground fissures the geological environment is thus responsible for the establishment and appearance of ground fissure more importantly ground fissure propagation in china is the result of the synergistic effects of internal geological dynamic including in deep tectonism intracontinental tectoniim and fault movement coupled with anthropomorphic stress this genetic model can be summarized as one that is tectonically controlled stress driven and affected by regional hydrodynamic

sensing the ups and downs of las vegas insar reveals structural control of land subsidence and aquifer system deformation land subsidence in las vegas nevada united states between april 1992 and december 1997 was measured using spaceborne interferometric synthetic aperture radar the detailed deformation maps clearly show that the spatial extent of subsidence is controlled by geologic structures faults and sediment composition clay thickness the maximum detected subsidence during the 5 75 yr period is 19 cm comparison with leveling data indicates that the subsidence rates declined during the past decade as a result of rising ground water levels brought about by a net reduction in ground water extraction temporal analysis also detects seasonal subsidence and uplift patterns which provide information about the elastic and inelastic properties of the aquifer system and their spatial variability

great earthquake paleogeodesy and tsunamis of the past 2000 years at alsea bay central oregon coast usa the width of plate boundary fault rupture at the cascadia subduction zone a dimension related to earthquake magnitude remains uncertain because of the lack of quantitative information about land level movements during past great earthquake deformation cycles beneath a marsh at alsea bay on the central oregon coast four sheets of tsunami deposited sand blanket contacts between tidal mud and peat radiocarbon ages for the sheets match ages for similar evidence of regional coseismic subsidence and tsunamis during four of cascadia s great earthquakes barring rapid unrecorded postseismic uplift reconstruction of changes in land level from core samples using diatom and foraminiferal transfer functions includes modest coseismic subsidence 0 470 2 m during the four earthquakes interpretation is complicated however by the 30 38 of potentially unreliable transfer function values from samples with poor analogs in modern diatom and foraminiferal assemblages reconstructions of coseismic subsidence using good analog samples range from 0 4670 12 to 0 0970 20 m showing greater variability than implied by sample specific errors from apparent high rates of land uplift following subsidence and tsunamis we infer that postseismic rebound caused by slip on deep parts of the plate boundary and or viscoelastic stress relaxation in the upper plate may be almost as large as coseismic subsidence modest coseismic subsidence 100 km landward of the deformation front implies that plate boundary ruptures in central oregon were largely offshore ruptures may have been long and narrow during earthquakes near magnitude 9 as suggested for the ad 1700 earthquake or of smaller and more variable dimensions and magnitudes r 2008 elsevier ltd all rights reserved

cold season synoptic scale waves over subtropical south america the most active winter synoptic scale wave patterns over south america are identified using an extended empirical orthogonal function eeof technique and are physically diagnosed using composite methods results show that the leading modes of short timescale variability propagate along two main paths over the subtropical jet latitudes 308s and over the subpolar jet latitudes 608s this research focuses on the subtropical mode and its evolution over south america the observed structure of the systems associated with the subtropical mode resembles that of midlatitude baroclinic waves both cyclonic and anticyclonic perturbations display significant modifications in their threedimensional structure as they evolve over extratropical and subtropical south america while the upper level perturbations are mostly unaffected when moving eastward the lower level perturbations advance following the shape of the andes mountains and exhibit an abrupt equatorward migration at the lee side of the mountains as a result of such detachment smaller eddy heat fluxes are observed in the vicinity of the orography and consequently a weaker eddy baroclinic growth is observed once the upper level system is on the lee side the perturbations acquire a more typical baroclinic wave structure and low level intensification of the system occurs the latter is largest around 1000 km east of the orography where enhanced moisture transports from tropical latitudes along the eastern portion of the low level cyclone favor precipitation occurrence over southeastern south america those precipitation processes seem to provide a diabatic source of energy that further contributes to the strengthening of the low level cyclone in addition an intensification of the cyclone once over the ocean was found in 60 of the situations considered which is consistent with previous research suggesting an additional source of moisture and heat flux due to the warm waters of the brazil current

impact of the north american ice sheet orography on the last glacial maximum eddies and snowfall the present work evaluates the influence of the north american ice sheet orography on the last glacial maximum lgm 21 000 years ago atmospheric circulation and snowfall in the northern mid latitudes focusing on the north atlantic sector three atmospheric general circulation model experiments are analysed a control and an lgm climate simulation and an lgm run with flat ice sheets over northern north america this ice sheet orography affects lee cyclogenesis over north america and forces differences in stationary waves and therefore in the baroclinicity of the mean flow as a result the atlantic storm track is reinforced in the flat ice sheet experiment compared to the lgm one this in turn has a profound impact on snowfall over northern europe implying a coupling between the two ice sheets

sediment sources and sedimentation processes of 2011 tohoku oki tsunami deposits on the sendai plain japan insights from diatoms nannoliths and grain size distribution abstract the 11th march 2011 tohoku oki tsunami inundated the low lying sendai plain japan more than 5 km inland leaving sand and mud deposits over most of the area in order to establish the sources of the tsunami deposits and interpret processes of their sedimentation samples were collected from the deposits underlying soils and the beach along a shore perpendicular transect and analysed for grain size diatom assemblages and nannoliths the fining inland tsunami deposits consisted of poorly to moderately sorted medium to coarse sand within 2 km of the coastline and very poorly to poorly sorted mud farther inland more specifically there was a slight fining of the coarse to medium sand mode within the sandy deposits and an increased contribution of the coarse and very coarse silt fraction in the mud deposits the tsunami deposits also exhibited vertical changes including fining upward and coupled coarsening fining upward trends few diatoms were present in beach sediments soils and tsunami deposits within 1 km of the coastline while diatoms were more abundant farther inland diatom assemblages in the soil and tsunami deposits were similar and dominated by species typical of freshwater brackish habitats while no typically marine species were encountered nannoliths were generally absent in the studied sediments except for few specimens our data indicate that there was probably no or only a very minor component of marine sediments transported onland by the tsunami the sandy tsunami deposits within 1 km of the coastline were mostly derived from beach and dune erosion from 1 to 2 km landward the contribution of these sources decreased while sources comprising local soil erosion and the entrainment of sediments from the teizan bori canal increased farther inland local soil erosion was the major sediment source for the mud deposits the tsunami deposits were most likely deposited during at least two inundations mostly out from suspension resulting in an upward grain size fining trend however bed load deposition was also important in the sandy deposits as suggested by a common grain size upward coarsening position on c m diagrams and frequent horizontal lamination the present study reveals that even very large tsunamis may not transport marine sediments onland and thus many commonly applied indicators of tsunami deposits based on the assumption of their offshore origin marine diatoms foraminifera nannoliths marine sediments may be of limited use

the dynamics of nao teleconnection pattern growth and decay this investigation performs both diagnostic analyses with ncep ncar re analysis data and forced barotropic model calculations to examine the dynamical mechanisms associated with the growth and decay of the north atlantic oscillation nao teleconnection pattern the diagnostic calculations include projection and composite analyses of each term in the stream function tendency equation the results of the analyses reveal a complete life cycle of growth and decay within approximately two weeks the positive nao phase is found to develop after anomalous wavetrain propagation across the north pacific to the east coast of north america this contrasts with the negative nao phase which appeared to develop in situ both high frequency period 10 days transient eddy fluxes drive the nao growth after the nao anomaly attains its maximum amplitude the high frequency transient eddy fluxes continue to drive the nao anomaly in a manner that is consistent with a positive feedback process the decay of the nao occurs through both the divergence term and the low frequency transient eddy fluxes the temporal and spatial properties of the divergence term are found to be consistent with ekman pumping these results illustrate many important differences between the nao and pacific north american pna teleconnection patterns perhaps most striking being that the nao life cycle is dominated by nonlinear processes whereas the pna evolution is primarily linear in addition the relation between the nao and the zonal index is discussed copyright 2003 royal meteorological society

sources and transportation modes of the 2011 tohoku oki tsunami deposits on the central east japan coast abstract we evaluated sediment sources of the 2011 tohoku oki tsunami deposits along a 4500 m inland transect from the central east japan coast using grain size mineralogy and foraminifera analyses the tsunami run up height in our study area was 13 to 20 m near the coastline 1 4 to 2 8 m in the middle of the valley and 1 3 m around the inundation limit the inundation distance was around 4800 m the deposits are composed of sand and mud and show a fining and thinning trend mineral composition of the tsunami deposits was similar to that of coastal dune and beach deposits indicating that most of the tsunami sediment originated from there a minor foraminifera population in the deposit 15 specimens per 5 g of sample compared with 100 specimens per 1 g for typical marine sediment indicates that marine sediment source was not dominant topography played an important role in sediment transport process and deposit distribution the run up wave accelerated faster in concave topography became more erosive and resulted in a thin deposit in topographic lows we infer that the deposits up to 2300 m from the coastline were deposited by bedload and suspension whereas suspension was responsible for deposits farther inland

mapping small elevation changes over large areas differential radar interferometry a technique that uses synthetic aperture radar sar images to measure very small 1 cm or less surface motions with good resolution 10 m over large swaths 50 km is presented along with experimental results the method could be used for accurate measurements of many geophysical phenomena including swelling and buckling in fault zones residual displacements from seismic events and prevolcanic swelling the method is based on sar interferometry where two images are made of a scene by simultaneously flying two physically separated antennas then the phases of corresponding pixels are differenced and altitude formation is deduced from some simple computation and image rectification it is also possible to use one antenna flown twice over the same scene then if the second flight exactly duplicates the track of the first an interesting possibility occurs there would be no phase changes between the images at all unless there was a physical change in the scene such as ground swelling that would alter the distance from some resolution element to the antenna since the phase changes all occur at the short carrier wavelength the basic limitation on sensitivity is only the phase noise in the system when the two imaging passes are made from flight tracks that are separated which is the case with the seasat images used here it is no longer possible to distinguish surface changes from the parallax caused by topography however with some additional computation a third image made at some other baseline may be used to remove the topography and leave only the surface changes this method was applied using seasat data to an imaging site in imperial valley california where motion effects were observed that were ascribed to the expansion of water absorbing clays phase change images of this area are shown along with associated ground truth about the presence of water problems with the technique are explored along with a discussion of future experimental possibilities on upcoming sar missions like earth observing system eos earth resources satellite ers 1 sir c and the venus imaging radar magellan

teleconnections and low frequency variability in idealized experiments with two storm tracks low frequency variability and teleconnection patterns induced by two storm tracks in idealized experiments depend on their zonal distance a separation of about 150 which resembles the northern hemisphere storm track distribution reveals teleconnection patterns which are similar to the pacific north american pna pattern and the north atlantic oscillation nao the nao like structure is associated with retrograde travelling rossby waves barotropic stream function tendencies show that the interaction of the stationary eddies with the low frequency flow and the high frequency eddies contribute to the amplification of the pattern its decay is due to their interaction with the zonal mean flow and the low frequency contribution to the divergence term the pna like pattern has a longer memory and is linked to a quasi stationary wave the stationary wave activity flux shows the dominating influence of baroclinic processes and the other storm track further upstream the correlation between the teleconnection indices is significant for storm track distances between 180 and 160 and vanishes between 150 and 130

sedimentary and microfossil imprint from historical earthquakes and tsunamis jalisco coast mexican subduction abstract tsunamis are high energy events capable of leaving their imprint in the geological record the western mexican pacific coast located in the mexican subduction zone is prone to large earthquakes m 8 0 where tsunami hazard has been underrated the geologic archive obtained in a sheltered coastal lagoon was analyzed applying a multi proxy approach to reveal the occurrence of historical earthquakes in the jalisco coast foraminifera and ostracoda aid identifying earthquake and tsunami geologic evidence in this section of the mexican pacific coast where tropical conditions prevail we present the evidence of changes in stratigraphy grain size biostratigraphy supported by archaeomagnetic dating they were complemented with published 210pb dating magnetic properties and historical data we identified three events the tsunami deposit left by the june 3rd 1932 tsunami produced by the largest earthquake m 8 2 recorded in instrumental history in mexico and the coseismic deformation resulting from the 1932 event also a probable tsunami deposit likely produced by an historical earthquake in 1900 and the coseismic deformation associated to this event and the coseismic deformation resulting produced by the 1563 earthquake the site geomorphology with a marginal lagoon closed by a little barrier 7 m 1 m above sea level precludes tropical storms as responsible for marine incursions this work contributes to strengthening the earthquake and associated tsunamis chronology aiming to improve coastal hazard assessment for the area

the pacific center of action of the northern hemisphere annular mode real or artifact the leading empirical orthogonal function eof of the sea level pressure slp field referred to as the arctic oscillation ao or northern hemisphere annular mode nam consists of a dipole between the polar cap region and the surrounding zonal ring centered along 458n embedded within the outer ring are centers of action over the euro atlantic and pacific sectors in which slp fluctuates in phase that the observed slp fluctuations at these two centers of action are virtually uncorrelated raises the question of whether the pacific center in the annular mode could be an artifact of eof analysis it is argued that sea level pressure fluctuations at the pacific and euro atlantic centers of action of the ao nam would be more strongly correlated were it not for the fact that slp variability over the north pacific is dominated by a pattern in which fluctuations over the north atlantic and north pacific are inversely related evidence of the coexistence of such a pattern which resembles an augmented version of the pacific north american pattern is presented

wave maintained annular modes of climate variability abstract the leading modes of month to month variability in the northern and southern hemispheres are examined by comparing a 100 yr run of the geophysical fluid dynamics laboratory gcm with the ncep ncar reanalyses of observations the model simulation is a control experiment in which the ssts are fixed to the climatological annual cycle without any interannual variability the leading modes contain a strong zonally symmetric or annular component that describes an expansion and contraction of the polar vortex as the midlatitude jet shifts equatorward and poleward this fluctuation is strongest during the winter months the structure and amplitude of the simulated modes are very similar to those derived from observations indicating that these modes arise from the internal dynamics of the atmosphere dynamical diagnosis of both observations and model simulation indicates that variations in the zonally symmetric flow associated with the annular modes are forced by eddy fluxes in the free troposphere while

aperiodic recurrence of geologically recorded tsunamis during the past 5500 years in eastern hokkaido japan 1 along hokkaido s pacific coast near the town of kiritappu sandy deposits in a muddy lagoon and on a nearby beach ridge plain provide evidence for 15 tsunamis between 200 and 6000 years ago additional sand beds at the lagoon probably represent the historical tsunamis of a d 1843 and 1894 we observed the sequences of sandy deposits in continuous slices 2 to 4 m deep some of the deposits consist of just a single sand bed whereas others contain multiple units of sand muddy sand or sandy mud and mud caps including plant detritus we also found at the lagoon a 17th century tsunami deposit that thickens and thins regardless of elevation or distance inland we bracketed the ages of most of the inferred tsunamis by radiocarbon dating of detritus mainly seeds and leaves at the lagoon and charcoal at the beach ridge plain from pretsunami and posttsunami beds tsunami dates computed from the bracketing ages commonly have uncertainties spanning 2 to 4 centuries within these uncertainties the inferred sequence of 15 prehistoric tsunamis at the lagoon beginning almost 6000 years ago can be matched tsunami by tsunami with the inferred history at the beach ridge plain 15 km away the sand sheet extents suggest that most of these tsunamis were larger than any generated at hokkaido in the last 200 years the intervals between these inferred outsized tsunamis average nearly 400 years but range widely from about 100 to about 800 years

on the derivation of coseismic displacement fields using differential radar interferometry the landers earthquake we present a map of the coseismic displacement field resulting from the landers california june 28 1992 earthquake derived using data acquired from an orbiting high resolution radar system we achieve results more accurate than previous space studies and similar in accuracy to those obtained by conventional field survey techniques data from the ers 1 synthetic aperture radar instrument acquired in april july and august 1992 are used to generate a high resolution wide area map of the displacements the data represent the motion in the direction of the radar line of sight to centimeter level precision of each 30 m resolution element in a 113 km by 90 km image our coseismic displacement contour map gives a lobed pattern consistent with theoretical models of the displacement field from the earthquake fine structure observed as displacement tiling in regions several kilometers from the fault appears to be the result of local surface fracturing comparison of these data with global positioning system and electronic distance measurement survey data yield a correlation of 0 96 thus the radar measurements are a means to extend the point measurements acquired by traditional techniques to an area map format the technique we use is 1 more automatic 2 more precise and 3 better validated than previous similar applications of differential radar interferometry since we require only remotely sensed satellite data with no additional requirements for ancillary information the technique is well suited for global seismic monitoring and analysis

quantitative interpretation of fossil pollen spectra dissimilarity coefficients and the method of modern analogs abstract dissimilarity coefficients measure the difference between multivariate samples and provide a quantitative aid to the identification of modern analogs for fossil pollen samples how eight coefficients responded to differences among modern pollen samples from eastern north america was tested these coefficients represent three different classes 1 unweighted coefficients that are most strongly influenced by large valued pollen types 2 equal weight coefficients that weight all pollen types equally but can be too sensitive to variations among rare types and 3 signal0to noise coefficients that are intermediate in their weighting of pollen types the studies with modern pollen allowed definition of critical values for each coefficient which when not exceeded indicate that two pollen samples originate from the same vegetation region dissimilarity coefficients were used to compare modern and fossil pollen samples and modern samples so similar to fossil samples were found that most of three late quaternary pollen diagrams could be reconstructed by substituting modern samples for fossil samples when the coefficients indicated that the fossil spectra had no modern analogs then the reconstructed diagrams did not match all aspects of the originals no modern analogs existed for samples from before 9300 yr b p at kirchner marsh minnesota and from before 11 000 yr b p at wintergreen lake michigan but modern analogs existed for almost all holocene samples from these two sites and brandreth bog new york

spatial pattern and zonal shift of the north atlantic oscillation part i a dynamical interpretation abstract this paper presents a possible dynamical explanation for why the north atlantic oscillation nao pattern exhibits an eastward shift from the period 1958 77 p1 to the period 1978 97 p2 or 1998 2007 p3 first the empirical orthogonal function analysis of winter mean geopotential heights during p1 p2 and p3 reveals that the nao dipole anomaly exhibits a northwest southeast nw se tilting during p1 but a northeast southwest ne sw tilting during p2 and p3 the nao pattern especially its northern center undergoes a more pronounced eastward shift from p1 to p2 the composite calculation of nao events during p1 and p2 also indicates that the negative positive nao phase dipole anomaly can indeed exhibit such a nw se ne sw tilting second a linear rossby wave formula derived in a slowly varying basic flow with a meridional shear is used to qualitatively show that the zonal phase speed of the nao dipole anomaly is larger smaller in higher latitudes and smaller larger in lower latitud

arctic oscillation or north atlantic oscillation abstract the definition and interpretation of the arctic oscillation ao are examined and compared with those of the north atlantic oscillation nao it is shown that the nao reflects the correlations between the surface pressure variability at its centers of action whereas this is not the case for the ao the nao pattern can be identified in a physically consistent way in principal component analysis applied to various fields in the euro atlantic region a similar identification is found in the pacific region for the pacific north american pna pattern but no such identification is found here for the ao the ao does reflect the tendency for the zonal winds at 35 and 55 n to anticorrelate in both the atlantic and pacific regions associated with the nao and pna because climatological features in the two ocean basins are at different latitudes the zonally symmetric nature of the ao does not mean that it represents a simple modulation of the circumpolar flow an increase in the ao or nao implies stro

holocene temperature trends in the extratropical northern hemisphere based on inter model comparisons large uncertainties exist in holocene climate estimates especially for the early holocene when large scale reorganization occurred in the climate system to improve our understanding of these uncertainties we compare four holocene simulations performed with the loveclim ccsm3 hadcm3 and famous climate models the simulations are generally consistent for the large scale northern hemisphere extratropics while the multi simulation consistencies are heterogeneous on the sub continental scale consistently simulated temperature trends are found in greenland northern canada north eastern and north western europe and central west siberia these holocene temperatures show a pattern of an early holocene warming mid holocene warmth and gradual decrease towards the pre industrial in winter and the extent of early holocene warming varies spatially with 9 c warming in northern canada compared with 3 c warming in central west siberia in contrast mismatched temperatures are detected in alaska the warm early holocene winter in loveclim primarily results from strongly enhanced southerly winds induced by the ice sheets in eastern siberia the intense early holocene summer warmth anomaly in ccsm3 is caused by large negative albedo anomalies due to overestimated snow cover at 0 ka in the arctic cool winter conditons in famous can be attributed to extensive sea ice coverage probably due to simplified sea ice representations thus the holocene temperature trends in these regions remain inconclusive

time scale and feedback of zonal mean flow variability the physical processes that determine the time scale of zonal mean flow variability are examined with an idealized numerical model that has a zonally symmetric lower boundary in the part of the parameter space where the time mean zonal flow is characterized by a single double jet the dominant form of zonalmean flow variability is the zonal index poleward propagation and the time mean potential vorticity gradient is found to be strong and sharp weak and broad the e folding time scale of the zonal index is found to be close to 55 days much longer than the observed 10 day time scale the e folding time scale of the poleward propagation is about 40 days the long e folding time scales for the zonal index are found to be consistent with an unrealistically strong and persistent eddy zonal mean flow feedback a calculation of the refractive index indicates that the background flow supports eddies that are trapped within midlatitudes undergoing relatively little meridional propagation additional model runs are performed with an idealized mountain to investigate whether zonal asymmetry can disrupt the eddy feedback for single jet states the time scale is reduced to about 30 days if the mountain height is 4 km or less the reduction in the time scale occurs because the stationary eddies excited by the mountain alter the background flow in a manner that leads to the replacement of zonal index events by shorter time scale poleward propagation with a 5 km mountain the time scale reverts and increases to 105 days this threshold behavior is again attributed to a sharpening of the background zonal jet which arises from an extremely strong stationary wave momentum flux convergence in contrast for double jet states the time scale changes only slightly and the poleward propagation is maintained in all mountain runs

estimating lava volume by precision combination of multiple baseline spaceborne and airborne interferometric synthetic aperture radar the 1997 eruption of okmok volcano alaska interferometric synthetic aperture radar insar techniques are used to calculate the volume of extrusion at okmok volcano alaska by constructing precise digital elevation models dems that represent volcano topography before and after the 1997 eruption the posteruption dem is generated using airborne topographic synthetic aperture radar topsar data where a three dimensional affine transformation is used to account for the misalignments between different dem patches the preeruption dem is produced using repeat pass european remote sensing satellite data multiple interferograms are combined to reduce errors due to atmospheric variations and deformation rates are estimated independently and removed from the interferograms used for dem generation the extrusive flow volume associated with the 1997 eruption of okmok volcano is 0 154 spl plusmn 0 025 km sup 3 the thickest portion is approximately 50 m although field measurements of the flow margin s height do not exceed 20 m the in situ measurements at lava edges are not representative of the total thickness and precise dem data are absolutely essential to calculate eruption volume based on lava thickness estimations this study is an example that demonstrates how insar will play a significant role in studying volcanoes in remote areas

definition of antarctic oscillation index following walker s work about his thmous three oscillations published during the 1920 30s many papers were written about atmospheric oscillations a iburth atmospheric oscillation in the middle and high southern latitudes was lbund and nanted the grotarctic oscillation ao a refiers to a large scale alternation of atmospheric mass between the mid latitudes and high latitudes surthce pressure in order to understand the spatial structure of sea level pressure variation in detail empirical orthogonal fitnction analysis is applied an objective index of the antarctic oscillation index aoi is defined as the diffierence of zonal mean sea level pressure between 40os and 65os the aoi has the potential tbr clarifying climate regimes in the southern hemisphere similar to how the na and the npo has been used in the northern hemisphere were there other oscillation s besides nao npo and s especially in the southern hemisphere it had been supposed that there might be other atmospheric oscillation s in the high southern latitudes although as early as in the first quarter of this century walker 1928 had stated that just as in the north atlantic there is a pressure opposition between the azores and iceland there is an opposition between the high pressure belt across chile and the argentine on the one hand and the low pressure area of weddell sea and the bellingshausen sea on the other the scarcity of data in the southern hemisphere hindered the search tbr new oscillation s during the last two decades more comprehensive data over the southern hemisphere became available and more analyses were carried out see kidson 1975 rogers and van loon 1982 mo and l 7 ite 1985 2 4o 1986 connolley 1997 gong and wang 1998 a tburth atmospheric oscillation in the middle and high southern latitudes was tbund and nanted as the antarctic oscillation a wang 1992 gong and wang 1998 the term ao relrs to a large scale alternation of atmospheric mass between the mid latitude sur hce pressure

modern and holocene sublittoral ostracod assemblages crustacea from the caspian sea a unique brackish deep water environment abstract we present a reconnaissance study of sublittoral ostracods from a number of caspian sea core tops collected during a joint french russian scientific cruise in 1994 cores from between 13 and 875 m water depth the modern ostracods show little depth restriction and this reflects the hydrography of the caspian sea which maintains relatively constant conditions 5 c 13 salinity below 50 m throughout the year we also present the ostracod faunal record from a 10 m core of laminated sediments recovered from the central caspian basin at a water depth of 475 m which we believe shows repetitive quasi cyclic changes in bottom water conditions over approximately the last 14 15 000 years with a major change at about the late glacial to holocene transition the faunal record from this core illustrates the potential of these sediments for reconstructing environmental changes in the caspian region during the late quaternary to holocene the continuous occurrence of in situ benthic meiofauna throughout the core also indicates that the bottom water must have remained ventilated throughout this period although variability in the faunal assemblages may reflect long and short term changes in the strength of ventilation

a baroclinic mechanism for the eddy feedback on the zonal index a baroclinic mechanism for the positive eddy feedback on the zonal index is proposed the author considers the quasigeostrophic response of the zonally averaged flow to forcing by baroclinic eddies the transient response to eddy forcing is a largely barotropic acceleration of the westerly flow and a reduction of the baroclinicity at the latitudes of eddy generation but over time the action of surface drag leads to enhanced baroclinicity at these latitudes the steady state response has positive baroclinicity at the latitude of eddy generation if the eddies propagate away from this latitude before they dissipate this reinforcement of the low level baroclinicity provides a positive feedback if it is assumed that baroclinic eddies are generated more vigorously in regions of stronger low level baroclinicity the proposed mechanism explains observed and modeled features of zonal index variations the frequency and drag dependence of eddy feedback the bandedness in latitude of zonal wind variations and the tendency for anomalies in the zonally averaged zonal wind to drift poleward over time

topographic mapping from interferometric synthetic aperture radar observations interferometric synthetic aperture radar observations provide a means for obtaining high resolution topographic terrain maps from data acquired simultaneously at two slightly displaced antennas calculation of the three dimensional coordinates of all the points in a radar image can be made from the combination of along track slant range and interferometer fringe measurements thus the result compensates for the layover exhibited by conventional radar maps and removes the false targets generated by multiple signal paths to a given object in the scene we have derived a topographic map of a portion of the san francisco bay area utilizing data that were recorded by a radar system mounted on a nasa cv990 aircraft and processed by a general purpose digital computer this map displays the height above sea level of a region approximately 11 km by 10 km in size sampled on an 11 m pixel grid uncertainties in the estimated height result from imprecise knowledge of the observational geometry radar bandwidth limitations and finite signal to noise ratios for our system each factor contributed approximately 3 4 m to a relative rms error of about 6 m additional global errors of the order of 10 m can result from inaccurate monitoring of aircraft attitude the statistical variation of the height measurements from the ocean portion of the map which we can presume to be quite flat is 2 10 m rms which is consistent with the theoretical estimate comparison of our results with u s geological survey contour maps indicates a high degree of correlation between the two sets of altitude data

geochemical and micropaleontological impacts caused by the 2011 tohoku oki tsunami in matsushima bay northeastern japan abstract we present stratigraphic geochemical cns elemental analysis and micropaleontological ostracode assemblages evidence for the 2011 tohoku oki tsunami impact in matsushima bay northeastern japan and examine the recovery process after the impact to the bay environment using short sediment cores from two different topographic settings at a water depth of approximately 4 m at both sites tsunami deposits are composed of two sedimentary layers that recorded the first tsunami run up and backwash at the western site near the channel that connects the bay with the pacific ocean the first tsunami wave eroded the bay floor sediments and left the tsunami deposits composed of medium sand rich in shell fragments but with sparse numbers of meiobenthic ostracodes by contrast at the eastern site which is surrounded by many small islands the first wave eroded very little of the bay floor sediments and left tsunami deposits consisting of sandy mud rich in exotic ostracodes such as phytal species shallow marine sand dwelling species and brackish water species overlying post tsunami deposits are composed mainly of organic rich mud in which organic matter was derived primarily from marine plankton ostracode assemblages in the tsunami deposits lack the offshore species that live in water depths 50 m and are dominated by the species from matsushima bay and its adjacent nearshore upper sublittoral areas and brackish water environments the distance from deep water offshore areas to the core sites is too far to transport ostracode valves by tsunami waves

two teleconnection patterns involved in the north atlantic arctic oscillation 1 the north atlantic oscillation nao and arctic oscillation ao are known as phenomena influencing the weather and climate of the euro atlantic region often however they are treated together in this study two indices representing two independent teleconnection patterns in the sea level pressure are introduced to characterize their differences one is a seesaw between the azores and iceland ai and the other is that between the polar and mediterranean pm regions the result of our study shows that differences in the nao ao indices mainly arise from the inclusion of different portions of the ai and pm and the nao ao indices can be reproduced by a linear combination of the ai and pm indices

linear simulation of the stationary eddies in a general circulation model part i the no mountain model abstract the quantitative validity of linear stationary wave theory is examined by comparing the results from a linear primitive equation model on the sphere with the stationary eddies produced by a general circulation model gcm the gcm simulated has a flat lower boundary so that the stationary eddies can be thought of as forced by heating sensible latent and radiative and time averaged transient eddy flux convergences orographic forcing is examined in the second part of this study the distribution of the diabatic heating and transient eddy flux convergences and the zonally symmetric basic state are taken directly from the gcm s climatology for northern winter djf strong rayleigh friction is included in the linear model wherever the zonal mean wind is small as well as near the surface the linear model is found to simulate the stationary eddy pattern of the gcm with considerable skin in both midlatitudes and the tropics some deficiencies include the inaccurate simulation of the upper troposp

contrasting sediment records of marine submersion events related to wave exposure southwest france abstract sediment records of two contrasting backshore coastal marshes extremely vulnerable to recent and historical marine flooding events located on the sw coast of france have been investigated using a multiproxy approach the studied marshes are 30 km apart and have been flooded by similar storm events 7 marine floods in the last 250 years one is located in a wave exposed coast but isolated from the sea by a sediment barrier whereas the other is located in a sheltered estuarine environment and isolated from the sea by a dike one core was collected in each marsh and information on grain size foraminifera shell contents and stable carbon isotopes was obtained along with an age model using 210 pb 137 cs and 14 c core data combined with historical maps give evidence of a typical estuarine backfilling part of the holocene regressive parasequence including an intertidal mudflat at the base and a backshore environment at the top despite the absence of grain size anomalies marine flood related sedimentation in the backshore area of both marshes is identified by a mixture of marine and terrestrial features including marine fauna vegetation debris and variation in the 13 c signature of the organic fraction very low sedimentation rates between flood events and or bioturbation prevents the identification of individual episodic marine floods in the sediment succession comparison of the two sedimentary successions shows that the foraminifera deposited by marine submersions are of two different types foraminifera are monospecific and originate from the upper tidal mudflat in the sheltered marsh whereas in the backshore marsh located in a wave exposed environment they show higher diversity and originate from both shallow and deeper water marine environments this study shows that wave exposure can control the faunal content of marine flood sediment records in coastal marshes

a novel approach to model earth fissure caused by extensive aquifer exploitation and its application to the wuxi case china initially observed in the semi arid basins of southwestern usa earth fissures due to aquifer over exploitation are presently threatening a large number of subsiding basins in various countries worldwide different mechanics have been proposed to explain this process such as differential compaction horizontal movements and fault reactivation numerical modeling and prediction of this major geo hazard caused by overuse of groundwater resources are challenging because of two main requirements shifting from the classical continuous to discontinuous geomechanics and incorporating 2 dimensional features the earth fissures into large 3 dimensional 3d modeling domain the subsiding basin in this work we proposed a novel modeling approach to simulate earth fissure generation and propagation in 3d complex geological settings a nested two scale approach associated with an original non linear elasto plastic finite element interface element simulator allows modeling the mechanics of earth discontinuities in terms of both sliding and opening the model is applied on a case study in wuxi china where groundwater pumping between 1985 and 2004 has caused land subsidence larger than 2 m the model outcomes highlight that the presence of a shallow 80 m deep bedrock ridge crossing the yangtze river delta is the key factor triggering the earth fissure development in this area bending of the alluvial deposits around the ridge tip and shear stress due to the uneven piezometric change and asymmetrical shape of the bedrock have caused the earth fissure to onset at the land surface and propagate downward to a maximum depth of about 20 30 m maximum sliding and opening are computed in the range of 10 to 40 cm in agreement with the order of magnitude estimated in the field

zonal asymmetry of the annular mode and its downstream subtropical jet an idealized model study abstractthis study investigates linkages between the zonal asymmetry of the annular mode am zonal pattern and the subtropical jet stj over its downstream regions of the storm track by using an idealized model observational analyses show that the am zonal patterns are more zonally asymmetric during days when the stj downstream of the storm track is unusually strong and vice versa in the idealized model the stj downstream of the storm track is varied by introducing an additional zonally localized tropical heating the model s am variability exhibits a nearly zonally uniform structure when there is no or only weak tropical heating however the signatures of the am are locally strengthened in the heating sector thus the am zonal pattern is zonally asymmetric when the tropical heating is large enough to create a strong stj the model results also show that the percentage of the variance explained by the am the persistence of the am index and the intensity of eddy feedback are also increased when t

the arctic oscillation signature in the wintertime geopotential height and temperature fields the leading empirical orthogonal function of the wintertime sea level pressure field is more strongly coupled to surface air temperature fluctuations over the eurasian continent than the north atlantic oscillation nao it resembles the nao in many respects but its primary center of action covers more of the arctic giving it a more zonally symmetric appearance coupled to strong fluctuations at the 50 hpa level on the intraseasonal interannual and interdecadal time scales this arctic oscillation ao can be interpreted as the surface signature of modulations in the strength of the polar vortex aloft it is proposed that the zonally asymmetric surface air temperature and mid tropospheric circulation anomalies observed in association with the ao may be secondary baroclinic features induced by the land sea contrasts the same modal structure is mirrored in the pronounced trends in winter and springtime surface air temperature sea level pressure and 50 hpa height over the past 30 years parts of eurasia have warmed by as much as several k sea level pressure over parts of the arctic has fallen by 4 hpa and the core of the lower stratospheric polar vortex has cooled by several k these trends can be interpreted as the development of a systematic bias in one of the atmosphere s dominant naturally occurring modes of variability

microfossils from coastal environments as indicators of paleo earthquakes tsunamis and storms abstract coastal risk assessment and hazard mitigation require datasets on centennial and millennial temporal scales to capture natural variability and multiple occurrences of the largest but least frequent events coastal sediments from low energy depositional environments archive geologic evidence of paleo earthquakes tsunamis and storms many of the best reconstructions of these events are derived from changes in microfossil diatoms foraminifera and pollen assemblages in this review we explain how microfossils are used to reconstruct records of paleoearthquakes by quantifying the amount of coseismic and interseismic vertical land movements along tectonically active coastlines examples from the united states alaska and the pacific northwest japan and chile show that microfossil based transfer functions may provide continuous records of vertical land movement during earthquake deformation cycles we discuss how microfossil habitat preferences and taphonomic character are used to constrain sediment provenance e g beach nearshore or offshore sources and identify overwash deposits and how this information can be used to reconstruct the recurrence of tsunamis and storms analysis of overwash deposits from thailand and malaysia indicates the ability of microfossils to resolve individual waves within tsunami sediments and an example from the sendai coastal plain in japan uses foraminifera to ascribe a beach to nearshore provenance for the 2011 tohoku tsunami deposit finally we present recent examples from the gulf of mexico on the use of foraminifera to estimate the volume and distance of transport of storm overwash from hurricanes

linear stationary wave simulations of the time mean climatological flow abstract a spectral coordinate model linearized about a zonal mean flow is used to investigate the maintenance of the december february climatological stationary waves the model is generally run with 15 levels in the vertical and a t31 truncation the sum of the response to orography diabatic heating and transient eddy flux convergences specified from data gives a generally good northern hemisphere simulation at 200 mb with some deterioration in the lower troposphere the same is true for the southern hemisphere but only when the forcing terms from recent years are used the response is broken down into that associated with particular orographic features tropical and midlatitude heating and transient vorticity and heat flux convergence all of these are shown to be significant in particular orography accounts for approximately 30 of the total 200 mb planetary wave response in midlatitudes the diabatic heating maxima in the two storm tracks are important this heating is related to latent and se

large area landslide detection and monitoring with alos palsar imagery data over northern california and southern oregon usa abstract multi temporal alos palsar images are used to automatically investigate landslide activity over an area of 200 km by 350 km in northern california and southern oregon interferometric synthetic aperture radar insar deformation images insar coherence maps sar backscattering intensity images and a dem gradient map are combined to detect active landslides by setting individual thresholds more than 50 active landslides covering a total of about 40 km 2 area are detected then the short baseline subsets sbas insar method is applied to retrieve time series deformation patterns of individual detected landslides down slope landslide motions observed from adjacent satellite tracks with slightly different radar look angles are used to verify insar results and measurement accuracy comparison of the landslide motion with the precipitation record suggests that the landslide deformation correlates with the rainfall rate with a lag time of around 1 2 months between the precipitation peak and the maximum landslide displacement the results will provide new insights into landslide mechanisms in the pacific northwest and facilitate development of early warning systems for landslides under abnormal rainfall conditions additionally this method will allow identification of active landslides in broad areas of the pacific northwest in an efficient and systematic manner including remote and heavily vegetated areas difficult to inventory by traditional methods

the role of the central asian mountains on the midwinter suppression of north pacific storminess abstractthe role of the central asian mountains on north pacific storminess is examined using an atmospheric general circulation model by varying the height and the areas of the mountains a series of model integrations show that the presence of the central asian mountains suppresses the north pacific storminess by 20 30 during boreal winter their impact on storminess is found to be small during other seasons the mountains amplify stationary waves and effectively weaken the high frequency transient eddy kinetic energy in boreal winter two main causes of the reduced storminess are diagnosed first the decrease in storminess appears to be associated with a weakening of downstream eddy development the mountains disorganize the zonal coherency of wave packets and refract them more equatorward as the zonal traveling distance of wave packets gets substantially shorter downstream eddy development gets weaker second the central asian mountains suppress the global baroclinic energy conversion the decre

transient eddy forcing of the rotational flow during northern winter abstract the total direct transient eddy forcing of the vorticity balance in the upper troposphere during northern winter is examined using 11 years of 2 to 8 day bandpassed global analyses most examinations of the importance of high frequency eddy vorticity fluxes to the maintenance of either the climatological standing waves or low frequency anomalous flows have focused on only the horizontal blow or the rotational component of the horizontal transient flow the latter simplification has been shown to be questionable for planetary scales the vorticity flux by the transient divergent flow produces a forcing of the mean streamfunction that is of comparable magnitude with the equivalent rotational term however the streamfunction forcing by the sum of the transient vertical advection and twisting terms largely balances the fearing by the vorticity flux convergence associated with the divergent flow the result is that the convergence of the eddy vorticity flux by the total transient flow is not a good a

the future of tsunami research following the 2011 tohoku oki event abstract in this paper we summarize the regional setting our previous understanding of historical and pre historical tsunamis on the pacific coast of tohoku japan prior to the 2011 tohoku oki tsunami and our current understanding of the sedimentological geochemical and paleontological features of the onshore and offshore deposits of the event post tsunami surveys revealed many new insights such as 1 the maximum extent of the sand deposit is sometimes only 60 of the inundation distance 2 the inundation limit can be estimated by geochemical analysis even a few months after the event 3 a minor amount of marine sediment was transported inland by the tsunami on the sendai and adjacent plains with the major sediment sources being from beach and dune erosion or vented sediments from liquefaction although nearshore and offshore surveys revealed that there was a significant amount of sediment transport on the seafloor 4 coarse gravel deposits 1 m in thickness were usually thicker than the sand ones 30 cm in thickness and 5 beach erosion was minimal in some places while severe in others another important aspect of this event is that it was a large infrequent tsunami that took place where possible predecessors e g ad869 j gan were already known to have occurred based on historical and geological evidence the ad869 j gan tsunami deposits are noticeably similar to the 2011 tohoku oki sands therefore suggesting that the j gan and its source mechanism may have been larger than previously thought while we have learned many lessons from the 2011 tohoku oki event more research is needed to provide reliable tsunami risk assessments around the world

zonal eddy dynamics of the north atlantic oscillation abstract this research is an attempt to understand the dynamical mechanisms that drive the wintertime north atlantic oscillation nao on monthly and longer timescales in an earlier work by deweaver and nigam the authors showed that momentum fluxes from stationary waves play a large role in maintaining the zonal mean zonal wind u perturbations associated with the nao in this paper a linear stationary wave model is used to show that zonal mean flow anomalies in turn play a large role in maintaining the nao stationary waves a strong two way coupling thus exists between u and the stationary waves in which each is both a source of and a response to the other when forced by zonal eddy coupling terms terms that represent the interaction between nao covariant zonal mean zonal wind anomalies and the climatological eddy flow together with heating and transient fluxes the model produces a realistic simulation of the observed stationary wave pattern zonal eddy coupling terms make the largest contribution

eddy zonal flow feedback in the northern hemisphere winter abstract the variability of the zonal mean zonal wind in the northern hemisphere winter december march is studied using eof analysis and momentum budget diagnostics of ncep ncar reanalysis data 1976 2001 the leading eof of the zonal mean zonal wind is well separated from the remaining eofs and represents the north south movement of the midlatitude westerlies analysis of the momentum budget shows that a positive feedback between the zonal mean wind anomalies and the eddy momentum fluxes selects the leading eof of midlatitude variability like the southern hemisphere the baroclinic eddies reinforce the zonal wind anomalies while external rossby waves damp the wind anomalies in the northern hemisphere the quasi stationary eddies also reinforce the zonal wind anomalies but the baroclinic eddies are most important for the positive eddy zonal flow feedback the observations support the following feedback mechanisms 1 above normal baroclinic wave activity is generated in the region of enhanced wester