low frequency variation in the seasonal intensity of coastal weather systems and sediment movement on the beachface of a sandy beach abstract variation in the seasonal intensity of weather systems generating onshore winds incident on port kembla n s w have been examined for the period 1965 to 1983 the onshore wind events were identified from anemograph records in turn they were related to synoptic weather records an intensity index 1 for each weather system was estimated as a function of the barometric pressure gradient between port kembla and the system centre the events were grouped by seasons and the intensity of the upper tercile i 1 3 value for each season utilised to represent the record for that season values of the seasonal i 1 3 intensities were spectrally analysed by fast fourier transform techniques the results identified quasi periodic variations of onshore wind activity with recurrence intervals corresponding to those in the frequency band shared by the southern oscillation so as well as the stratospheric quasi biennial oscillation qbo and the tropospheric quasi biennial oscillation bo the dominant quasi periodic components identified from a time series filtered to remove high frequency fluctuations include 3 years 27 months and 21 6 months the triennial and biennial components combine to account for approximately 32 of variance in the time series describing seasonal i 1 3 anomalies in onshore wind activity the filtered time series correlated with the southern oscillation index soi with r 0 49 p i 1 3 anomalies with the period of both the qbo and the m1 index of the tropospheric biennial oscillation were also noted in the latter instance direct comparison of the m1 phase shift was not possible because the i 1 3 data is contaminated with a strong soi type signal peak i 1 3 intensities are in phase to 1 month with the monthly mean sea level peaks at fort denison sydney n s w over corresponding periods more accurate resolution is not possible because of the specification of the weather system intensities as seasonal values in turn the sea level fluctuations lead movement of sediment on warilla beach n s w by a month over the 9 years for which observations are available from 1976 to 1985 peak weather system intensities for port kembla are co incidental with low volumes of sediment stored above msl on warilla beach conversely periods of low onshore wind activity are associated with increases in the volume of sediment stored on the beach

the influence of coastal reefs on spatial variability in seasonal sand fluxes the effect of coastal reefs on seasonal erosion and accretion was investigated on 2 km of sandy coast the focus was on how reef topography drives alongshore variation in the mode and magnitude of seasonal beach erosion and accretion and the effect of intra and inter annual variability in metocean conditions on seasonal sediment fluxes this involved using monthly and 6 monthly surveys of the beach and coastal zone and comparison with a range of metocean conditions including mean sea level storm surges wind and wave power alongshore zones were revealed with alternating modes of sediment transport in spring and summer compared to autumn and winter zone boundaries were determined by rock headlands and reefs interrupting littoral drift the seasonal build up of sand over the reef in the south zone and current jets generated by wave set up over reefs in spring and summer constant sand resuspension and northerly littoral drift due to sea breezes allowed a sand ramp to form in the south zone so that sand overtopped the reef to infill the lagoon this blocked the main pathway for sand supply to downdrift zones which subsequently eroded in autumn and winter with the dominance of northwesterly storms and reversal in the direction of littoral drift the south zone eroded and sand travelled through the lagoon in the current jet to nourish the northern beaches inter annual and seasonal variation in sea level storm frequency and intensity together with pulsational effects of local sand fluxes at yanchep due to inter seasonal switching in the direction of littoral drift determined marked differences in the volumes of seasonal sand transport these seasonal sediment zones highlighted interesting and unexplored parallels between coasts fronted seaward by coral reefs and rock formations

meso scale transfer of sand during and after storms implications for prediction of shoreline movement abstract monitoring beach volume changes of the texas coast following a major hurricane reveals the impact of storms on sand dispersal and shoreline movement at spatial and temporal scales encompassing tens of kilometers and decades beach volume histories at profile sites show the interdependence of sand exchange among adjacent sites and the spatial autocorrelation of sand movement beach volume histories also indicate periods when either longshore or cross shore transport predominate and illustrate the long term effects of coastal structures on beach mobility this study confirms that net losses of sand from updrift barriers may not be directly linked with net gains of sand on adjacent downdrift barriers instead sand dispersal within a coastal compartment may depend partly on the dynamics of shoals and temporary sand storage at the intervening tidal inlet in our study sand eroded from the updrift barrier galveston island is deposited in a terminal sand flat of the barrier whereas sand accreted to the downdrift barrier follets island is derived from the intermediate ebb tidal delta san luis pass unlike continuous sand bypassing on some microtidal wave dominated coasts sand bypassing at san luis pass is episodic event driven and inefficient and sand is not transferred directly from one barrier to the next p because storms rapidly redistribute beach sediment they can be the most important factor controlling short term

regional sea level southern oscillation and beach change new south wales australia coastal erosion is a problem of increasing concern that affects 60 of the world s sandy coastline1 this erosion has been attributed to increased storminess tectonic subsidence eustatic sea level rise decreased shoreward sediment movement from the shelf permanent longshore leakage of sediment from beach compartments shifts in global pressure belts resulting in changes in the directional component of wave climates and human interference2 3 no one explanation has worldwide applicability because all factors vary in importance regionally evaluation of factors is complicated by a lack of accurate continuous long term erosional data historical map evidence spanning 100 1 000 yr has been used in a few isolated areas4 7 however temporal resolution has not been sufficient to evaluate the effect of climatic variables air photographic evidence8 is restricted to the past 40 yr and often suffers from insufficient ground control for accurate mapping over time ground surveying of beaches was rarely carried out before 1960 and is often discontinuous in time and space i have resolved the problems of temporal and spatial continuity by studying change for the whole of stanwell park beach new south wales australia for the period 1895 1980 fig 1 i report here that using the average high tide wave run up position measured accurate to 2 5 m from oblique and vertical photographs changes could be linked to regional sea level variation and a globally significant climatic variable the southern oscillation so

geomorphological study of the fadalto landslide venetian prealps italy abstract this research deals with the fadalto landslide lapisina valley venetian prealps which took place in the lateglacial and has continued its activity until today our aim is to recognize how the landslide failed the causes of such failure and the activity of this landslide the study of this landslide is important not only to understand the geomorphological history of this alpine area and why the piave river modified its course in the late pleistocene but also the links with human activities and specifically with the road and rail network the geomorphological study carried out by the interpretation of aerial photos and by a detailed field survey has been integrated with a geological survey geophysical investigations and a morphometric analysis dtm the fadalto landslide is considered to be a rockslide reactivated in various phases with different dimensions and with different characters slides slumps and flows the landslides have been provoked by natural causes both external and internal the fundamental external causes are the retreat of the wurmian glacier and tectonic activity the internal factors that decrease the shear resistance are the bedding planes and joints of the bedrock the attitude of the rocks dipping towards the valley bottom and as regards more recent failures the presence of glacial deposits underlying the landslide debris besides in recent times we must also consider human activity as a cause of slope instability as to the activity the fadalto landslide is defined dormant this means that in this area there is a geomorphological risk connected with the important road and rail network of the lapisina valley

arctic sea ice variability in the context of recent atmospheric circulation trends abstract forty years 1958 97 of reanalysis products and corresponding sea ice concentration data are used to document arctic sea ice variability and its association with surface air temperature sat and sea level pressure slp throughout the northern hemisphere extratropics the dominant mode of winter january march sea ice variability exhibits out of phase fluctuations between the western and eastern north atlantic together with a weaker dipole in the north pacific the time series of this mode has a high winter to winter autocorrelation 0 69 and is dominated by decadal scale variations and a longer term trend of diminishing ice cover east of greenland and increasing ice cover west of greenland associated with the dominant pattern of winter sea ice variability are large scale changes in sat and slp that closely resemble the north atlantic oscillation the associated sat and surface sensible and latent heat flux anomalies are largest over the portions of the marginal sea ice zone in which the tr

why the western pacific subtropical high has extended westward since the late 1970s the western pacific subtropical high wpsh is closely related to asian climate previous examination of changes in the wpsh found a westward extension since the late 1970s which has contributed to the inter decadal transition of east asian climate the reason for the westward extension is unknown however the present study suggests that this significant change of wpsh is partly due to the atmosphere s response to the observed indian ocean western pacific iwp warming coordinated by a european union s sixth framework programme understanding the dynamics of the coupled climate system dynamite five agcms were forced by identical idealized sea surface temperature patterns representative of the iwp warming and cooling the results of these numerical experiments suggest that the negative heating in the central and eastern tropical pacific and increased convective heating in the equatorial indian ocean maritime continent associated with iwp warming are in favor of the westward extension of wpsh the sst changes in iwp influences the walker circulation with a subsequent reduction of convections in the tropical central and eastern pacific which then forces an enso gill type response that modulates the wpsh the monsoon diabatic heating mechanism proposed by rodwell and hoskins plays a secondary reinforcing role in the westward extension of wpsh the low level equatorial flank of wpsh is interpreted as a kelvin response to monsoon condensational heating while the intensified poleward flow along the western flank of wpsh is in accord with sverdrup vorticity balance the iwp warming has led to an expansion of the south asian high in the upper troposphere as seen in the reanalysis

sst and ice sheet impacts on the mis 13 climate as a first qualitative assessment tool loveclim has been used to investigate the interactions between insolation ice sheets and the east asian monsoon at the marine isotopic stage 13 mis 13 in work by yin et al clim past 4 79 90 2008 clim past 5 229 243 2009 the results are in need of validation with a more sophisticated model which is done in this work with the arpege atmospheric general circulation model as in the earth system model of intermediate complexity loveclim arpege shows that the northern hemispheric high insolation in summer leads to strong mis 13 monsoon precipitation data from the chinese loess plateau indicate that mis 13 was locally a warm and humid period guo et al in clim past 5 21 31 2009 yin and guo in chin sci bull 51 2 213 220 2006 this is confirmed by these general circulation model gcm results where the mis 13 climate is found to be hotter and more humid both in the presence and absence of any added ice sheets loveclim found that the combined effects of the ice sheets and their accompanying ssts contribute to more precipitation in eastern china whilst in arpege the impact is significant in northeastern china nonetheless the results of arpege confirm the counter intuitive results of loveclim where ice sheets contribute to enhance monsoon precipitation this happens through a topography induced wave propagating through eurasia with an ascending branch over northeastern china a feature which is also seen in loveclim the sst forcing in arpege results in a strong zonal temperature gradient between the north atlantic and east eurasia which in turn triggers an atmospheric gravity wave this wave induces a blocking okhotskian high preventing the northwards penetration of the meiyu monsoon front the synergism between the ice sheets and sst is found through the factor separation method yielding an increase in the meiyu precipitation though a reduction of the changma precipitation the synergism between the ice sheets and sst play a non negligible role and should be taken into consideration in gcm studies preliminary fully coupled aogcm results presented here further substantiate the finding of stronger mis 13 monsoons and a reinforcement from ice sheets this work increases our understanding of the signals found in the paleo observations and the dynamics of the complex east asian summer monsoon

geologically constrained morphological variability and boundary effects on embayed beaches abstract headlands rock outcrops and engineering structures impact beach and nearshore dynamics of coastal embayments inducing boundary effects that constrain the lateral and vertical beach variability this study analyses morphological change in six embayed beaches with diverse levels of exposure to wave action and various degrees of geological control in the mesotidal coast of southwestern portugal the aim is to identify whether geological boundaries constrain the morphological behaviour of embayed beaches and assess whether their effects can be decoupled from datasets of morphological change topographic data obtained over a two year period on each of the six embayments were analysed using empirical orthogonal functions eof to decompose temporal and spatial variability in the datasets first and second mode eigenfunctions were explored using time variable linear correlation analysis with several nearshore parameters that include hydrodynamic variables sedimentary and geometric characteristics of each embayment in order to derive forcing response relationships our results demonstrate that natural geological boundaries constrain the morphological behaviour of embayed beaches producing conspicuous alongshore variability in all embayments localised responses induced by lateral and vertical boundary interference with beach and nearshore dynamics include beach rotation topographically controlled rip circulation and restrained profile fluctuation spatial decoupling in cross and longshore responses is accompanied by a temporal decoupling in response times both of which are slower in more constrained embayments from 1 day in exposed embayments to 1 week or more in the most sheltered ones normalised wave power was correlated at the 99 confidence level with the primary mode of morphological variability at most embayments which represent 67 to 94 of the variance in the datasets this correlation stresses the importance of combined parameterization of wave and tide forcing in process response relations between hydrodynamics and morphological change for mesotidal coastal environments lateral and vertical geological boundaries exert their effects fundamentally by restraining longshore sediment transport inducing cellular surf zone circulation and by impacting cross shore sediment transport it is postulated that decreasing sediment abundance and substrate depth intensify vertical boundary effects while higher indentation and wave obliquity enhance the effects of lateral boundaries

gis techniques and statistical models in evaluating landslide hazard geographical information systems gis and numerical cartography may greatly facilitate the development and use of statistical models for the assessment of regional landslide hazard from a small drainage basin located in central italy relevant geological and geomorphological factors were collected and processed by applying gis technology in particular modules were used which both generate high fidelity digital terrain models and automatically partition the terrain into main slope units the resulting information was then analysed by discriminant analysis which enabled landslide hazard and risk to be evaluated in each slope unit although not lacking drawbacks the method proved to be a feasible and cost effective approach to landslide susceptibility assessment and mapping

interannual fluctuations of the tropical pacific wind field and the southern oscillation abstract linear regression analysis of tropical pacific winds versus a southern oscillation index soi show departures from the seasonal mean wind associated with the phase of soi when the soi is low the largest departures are westerlies on the equator and in the subtropics west of the dateline the intertropical convergence zone itcz and the south pacific convergence zone spcz shift equatorward departures from mean wind are strongest from september through february and weakest from march to may the usual pattern of cyclonic wind stress curl in the tropics and anticyclonic wind stress curl in the subtropics intensifies when the soi is low effects of these changes on ocean circulation are discussed and compared to changes in ocean circulation data

climate transition in the asia inland at 0 8 0 6 ma related to astronomically forced ice sheet expansion abstract knowing the evolution history of the climate systems in the asian inland dominated by either the westerlies or the asian monsoon and understanding their associated driving mechanisms are crucial for assessing future trends of climate and environmental conditions in this region but both the evolution and mechanisms are still under debate in this study we present a comparative analysis of massive data from an accurately dated drill core retrieved from the westerlies controlled western qaidam basin qb with records from the chinese loess plateau clp dominated by the east asia summer monsoon easm to track the time and frequency domain evolution patterns and dynamic changes of the qb and the clp systems the results infer two main conclusions first a critical transition in the evolution of qaidam paleolake occurred at 0 8 0 6 ma characterized by striking changes in proxy variations and a system shift from periodic variations to more irregular fluctuations after 0 6 ma second a similar evolution pattern prevailed in the qaidam paleolake region and in the easm dominated clp between 2 7 and 1 2 ma but a divergence of both systems started at 1 2 ma and fully established after 0 6 ma when largely fluctuating climate conditions in the qb with a distinct drying trend was accompanied by synchronous largely fluctuated easm with an increasing trend after 0 6 ma we suggest that ice sheet expansion in the northern hemisphere promoted by co occurrence of low obliquity amplitudes and low eccentricity drove both systems across a threshold at 1 2 ma and the internal forcing due to glaciation disturbed the previous response of both systems to solar insolation and led to the divergence of two systems at 0 9 0 8 ma a node of the 1 2 myr obliquity cycle co occurred with an eccentricity minimum which together with coeval decrease in atmospheric co2 concentration could have facilitated a striking expansion of ice sheets the resulting more equatorial and zonally oriented northern hemisphere westerly jet could serve as key factor leading to the final collapse of qaidam paleolake after 0 6 ma and the divergence of the qb and the clp systems

assessment of southern oscillation sea level pressure indices abstract monthly sea level pressure anomalies at easter island rapa tahiti and darwin for the period 1951 79 are analysed to reveal their temporal characteristics and the coherence and time lead lag relationships among them for interannual scale oscillations the pressure variations at rapa and easter island lead those at tahiti and those of opposite phase at darwin by 2 8 months where the large lead times are associated with lower frequency oscillations of the four stations rapa has the smallest percentage of its variance in the range of periods containing the southern oscillation darwin has the largest spatial smoothing by combining stations enhances the percentage of variance in the longer periods combining tahiti and darwin gives a substantial increase combining rapa and easter island much less normalization of the time series through division by the monthly standard deviations is also treated the combination of tahiti and darwin is recommended as a southern oscillation index for diagno

an 800 ky proxy record of climate from lake sediments of the zoige basin eastern tibetan plateau abstract we present the results of magnetic susceptibility geochemical and pollen analyses of a 120 m long core of lacustrine and fluvial sediments from the zoige basin eastern tibetan plateau palaeomagnetic dating indicates that the sediment sequence spans the last ca 800 ky the magnetic susceptibility record appears to be related to global ice volume over this period and this relationship is used to produce a tentative revised chronology for the sediment sequence the various climate proxies show a pattern of periodic variations over the last 800 ky bp the date of 500 ky bp is a significant boundary prior to this date the climate proxies show a pattern of more frequent variability after 500 ky bp the variations are of lower frequency and higher amplitude the results also indicate that marine oxygen isotope stage 13 was an unusually intense interglacial in the eastern tibetan plateau and chinese loess plateau areas

asian jet waveguide and a downstream extension of the north atlantic oscillation abstract anomalous atmospheric fields associated with the north atlantic oscillation nao are analyzed on interannual and intraseasonal time scales in order to examine the extent to which the nao is a regional phenomenon analyses on the interannual time scale reveal that the nao signal is relatively confined to the euro atlantic sector in december while it extends toward east asia and the north pacific in february the difference is most clearly seen in the meridional wind anomaly which shows a wave train along the asian jet collocated with an anomalous vorticity source near the jet entrance diagnoses using a linear barotropic model indicate that this wave train is interpreted as quasi stationary rossby waves trapped on the asian jet waveguide and effectively excited by the anomalous upper level convergence over the mediterranean sea it is found that when the nao accompanies the mediterranean convergence mc anomaly most frequently seen in february the nao indeed has a much wider horizontal str

the climate of the mis 13 interglacial according to hadcm3 the climate of the marine isotopic stage 13 mis 13 is explored in the fully coupled atmosphere ocean general circulation model the hadley centre coupled model version 3 hadcm3 it is found that the strong insolation forcing at the time imposed a strengthened land ocean thermal contrast resulting in an intensified summer monsoon over asia the addition of land ice over north america and eurasia results in a stationary wave feature across the eurasian continent this leads to a high pressure anomaly over the sea of japan with increased advection of warm moist air onto the chinese landmasses this in turn reinforces the east asian summer monsoon easm highlighting the counterintuitive notion that depending on the background insolation and its size ice can indeed contribute to strengthening the easm the modeling results support the geological record indication of a strong easm 500 000 years ago furthermore arctic oscillation el nino southern oscillation and indian ocean dipole like teleconnection features are discussed in the mis 13 environment it is shown that the change in the tropical pacific sea surface temperature has the potential to impact the north atlantic climate through an atmospheric bridge

detecting major terrain parameters relating to mass movements occurrence using gis remote sensing and statistical correlations case study lebanon abstract among the various natural hazards mass movements mm are probably the most damaging to the natural and human environment in mediterranean countries including lebanon which represents a good case study this research deals with how to use geographic information systems gis for establishing the relationships between mm occurrence and different factor terrain parameters over a representative region of lebanon parameters expressed by 1 ancillary data like lithology proximity to fault zone soil type land cover use distance to drainage line and rainfall quantity and 2 derived data like slope gradient and slope aspect were correlated with mm using gis approaches the mm were first detected through visual interpretation of two stereo pairs of spot 4 images anaglyph at 10 m resolution this study indicates depending on bivariate remote sensing and gis statistical correlations kendall tau b correlation that the lithology is the most influencing factor on mm occurrence it also shows that statistical correlations to mass movements exist best between factors at the following decreasing order of importance lithology proximity to fault line lithology soil type and lithology distance to drainage line at 1 level of significance and soil land cover use slope aspect land cover use and soil slope gradient at 5 level of significance these correlations were verified and checked through field observations and explained using univariate statistical correlations therefore they could be extrapolated to other mediterranean countries having similar geoenvironmental conditions

orbital and millennial antarctic climate variability over the past 800 000 years a high resolution deuterium profile is now available along the entire european project for ice coring in antarctica dome c ice core extending this climate record back to marine isotope stage 20 2 800 000 years ago experiments performed with an atmospheric general circulation model including water isotopes support its temperature interpretation we assessed the general correspondence between dansgaard oeschger events and their smoothed antarctic counterparts for this dome c record which reveals the presence of such features with similar amplitudes during previous glacial periods we suggest that the interplay between obliquity and precession accounts for the variable intensity of interglacial periods in ice core records

magnetic susceptibility evidence of monsoon variation on the loess plateau of central china during the last 130 000 years the magnetic susceptibility of loess and paleosols in central china represents a proxy climate index closely related to past changes of precipitation and vegetation and thus to summer monsoon intensity time series of magnetic susceptibility constructed for three loess paleosol sequences in the southern part of the chinese loess plateau document the history of summer monsoon variation during the last 130 000 yr they correlate closely with the oxygen isotope record of stages 1 to 5 in deep sea sediments soils were forming during intervals of strong summer monsoon whereas loess units were deposited at times of reduced monsoon intensity the chinese loess paleosol sequence can thus be viewed as a proxy record of asian monsoon variability extending over the last 2 5 myr

impact of ice sheet induced north atlantic oscillation on east asian summer monsoon during an interglacial 500 000 years ago marine isotope stage mis 13 an interglacial about 500 000 years ago is unique due to an exceptionally strong east asia summer monsoon easm occurring in a relatively cool climate with low greenhouse gas concentrations ghg this paper attempts to find one of the possible mechanisms for this seeming paradox simulations with an earth system model loveclim show that the presence of ice sheets over north america and eurasia during mis 13 induces a positive phase of the winter north atlantic oscillation nao like feature the ocean having a longer memory than the atmosphere the oceanic anomalies associated with nao persists until summer the signals of summer nao are transmitted to east asia to reinforce the monsoon there through the stationary waves excited at the asian jet entrance the geopotential height shows clearly a mid latitude wave train with positive anomalies over the eastern mediterranean caspian sea and the okhotsk sea and a negative anomaly over lake baikal this reinforces the effect of the high latitude wave train induced independently by the eurasian ice sheet topography as shown in previous study these features reinforce the meiyu front and enhance the precipitation over east asia the results obtained from loveclim are further confirmed by an atmospheric general circulation model arpege

low frequency changes of sediment volume on the beachface at warilla beach new south wales 1975 1985 abstract characteristic patterns of shore parallel and shore normal movements of sediment on a sandy beach are described in this study the sediment movements are apparent as low frequency variations in the volume of sediment stored above mean low water spring tide mlwst level on warilla beach n s w they were determined by an empirical orthogonal function eof analysis of beach profile records the profiles were surveyed from eighteen stations along a 2 km long beach at least monthly generally fortnightly for over 10 years from july 1975 until august 1985 results from the eof analysis confirm and substantially extend an earlier study of warilla beach when the first 5 years of the beach survey record was examined the importance of low frequency beachface change identified in the earlier shorter study was confirmed from the extended data set zones of maximum variability linked with rip current activity are consistent in both studies and similar patterns of alongshore sediment movement in the swash zone were determined from both analyses the principal differences between the two sets of results highlight beachface responses to processes operating in different time scales amplitude spectra from time series describing the characteristic modes of sediment movement along and across the beachface have periodicities of 2 0 1 7 and 1 0 years beach changes with periods close to 3 years are apparent in the record but cannot be resolved by standard spectral analysis techniques each period is associated with a characteristic pattern of beach change the triennial and 1 7 year cycles with alongshore sediment transport and the biennial cycle with onshore offshore sediment exchange eigenvectors from the eof analysis identify the characteristic patterns of beach change from survey data specified to highlight the shore parallel sediment movement along 0 5 m deep horizontal segments of beach and shore normal sediment movement along the beach profiles in the analysis of shore parallel variation in beach profile configuration the fundamental eigenvectors explain between 70 and 80 of beachface variance in each instance and different patterns of sediment movement were identified for each horizontal slice on the upper part of the beachface all eigenvectors identified a zone of low variability along the shoreline skirting a rockwall below berm crest in the swash and intertidal zones of the beach and away from the rockwall the northern half of the beach was highly variable second mode eigenvectors cellular flux modes explain a further 5 to 14 of the variance and describe sediment exchanges between discrete zones in each horizontal segment of the beachface zones of greatest variability occurred landward of places where rip currents frequently develop conversely zones of low variability are coincident with areas of beachface in the lee of places where inshore bars frequently form analysis of sediment movement along each profile is consistent with the beach changes described the fundamental eigenvectors account for 91 to 99 of the variance on each profile they describe an onshore offshore movement of sediment through the intertidal zone of the beach

tropical extratropical teleconnections in boreal summer observed interannual variability abstractmaximum covariance analysis is performed on the fields of boreal summer tropical rainfall and northern hemisphere nh 200 hpa height for the 62 yr period of record of 1948 2009 the leading mode which appears preferentially in summers preceding the peak phases of the el nino southern oscillation enso cycle involves a circumglobal teleconnection cgt pattern in the nh extratropical 200 hpa height field observed in association with indian monsoon rainfall anomalies the second mode which tends to occur in summers following enso peak phases involves a western pacific north america wpna teleconnection pattern in the height field observed in association with western north pacific summer monsoon rainfall anomalies the cgt pattern is primarily a zonally oriented wave train along the westerly waveguide while the wpna pattern is a wave train emanating from the western pacific monsoon trough and following a great circle the cgt is accompanied by a pronounced tropical extratropical seesaw in t

analysis of observed two and three dimensional nearshore bar behaviour abstract shore parallel sandbar systems often exhibit considerable quasi regular alongshore variations such as crescentic plan shapes therefore morphological change in such systems commonly consists of two and three dimensional variability the former is related to overall on offshore bar migration whereas the latter is induced by the horizontal amplitude growth migration or length scale change of the quasi regular topography in this paper we used a six week data set of bathymetric surveys and video images of breaking induced foam to quantify short term days weeks two and three dimensional variability in the bar crest position of the double barred beach at egmond aan zee netherlands the alongshore uniform response was computed as the mean of each bar crest line whereas the alongshore non uniform behaviour was characterised by the amplitude around each mean a more sophisticated description of the inner bar data set was provided by complex empirical orthogonal function ceof analysis the first complex mode containing about 85 of the variance in the data set corresponded to the amplitude growth and longshore migration of an approximately 600 m long alongshore non uniformity the longshore migration rate varied between 0 and 150 m day and was found to be well related to the longshore component of the offshore wave energy flux the second complex mode explained about 10 of the variance and largely described the alongshore averaged cross shore bar migration the ceof results suggest that short term variability in bar crest position is largely due to changes in the quasi regular topography and not to alongshore uniform on offshore oriented behaviour

late onset of the holocene rainfall maximum in northeastern china inferred from a pollen record from the sediments of tianchi crater lake the timing of the holocene summer monsoon maximum hsmm in northeastern china has been much debated and more quantitative precipitation records are needed to resolve the issue in the present study holocene precipitation and temperature changes were quantitatively reconstructed from a pollen record from the sediments of tianchi crater lake in northeastern china using a plant functional type modern analogue technique pft mat the reconstructed precipitation record indicates a gradual increase during the early to mid holocene and a hsmm at similar to 5500 3100 cal yr bp while the temperature record exhibits a divergent pattern with a marked rise in the early holocene and a decline thereafter the trend of reconstructed precipitation is consistent with that from other pollen records in northeastern china confirming the relatively late occurrence of the hsmm in the region however differences in the onset of the hsmm within northeastern china are also evident no single factor appears to be responsible for the late occurrence of the hsmm in northeastern china pointing to a potentially complex forcing mechanism of regional rainfall in the east asian monsoon region we suggest that further studies are needed to understand the spatiotemporal pattern of the hsmm in the region

circumglobal teleconnection in the northern hemisphere summer analysis of the 56 yr ncep ncar reanalysis data reveals a recurrent circumglobal teleconnection cgt pattern in the summertime midlatitude circulation of the northern hemisphere this pattern represents the second leading empirical orthogonal function of interannual variability of the uppertropospheric circulation the cgt having a zonal wavenumber 5 structure is primarily positioned within a waveguide that is associated with the westerly jet stream the spatial phases of cgt tend to lock to preferred longitudes the geographically phase locked patterns bear close similarity during june august and september but the pattern in july shows shorter wavelengths in the north pacific north america sector the cgt is accompanied by significant rainfall and surface air temperature anomalies in the continental regions of western europe european russia india east asia and north america this implies that the cgt may be a source of climate variability and predictability in the above mentioned midlatitude regions the cgt has significant correlations with the indian summer monsoon ism and el nino southern oscillation enso however in normal ism years the cgt enso correlation disappears on the other hand in the absence of el nino or la nina the cgt ism correlation remains significant it is suggested that the ism acts as a conductor connecting the cgt and enso when the interaction between the ism and enso is active enso may influence northern china via the ism and the cgt additionally the variability of the cgt has no significant association with the arctic oscillation and the variability of the western north pacific summer monsoon the circulation of the wave train shows a barotropic structure everywhere except the cell located to the northwest of india where a baroclinic circulation structure dominates two possible scenarios are proposed the abnormal ism may excite an anomalous west central asian high and downstream rossby wave train extending to the north pacific and north america on the other hand a wave train that is excited in the jet exit region of the north atlantic may affect the westcentral asian high and thus the intensity of the ism it is hypothesized that the interaction between the global wave train and the ism heat source may be instrumental in maintaining the boreal summer cgt

the southern oscillation in the stratosphere abstract the signal of the southern oscillation in the lower half of the northern hemisphere stratosphere in winter appears to be as follows in the extreme of the southern oscillation when the trade winds are comparatively weak in the south pacific ocean stratospheric geopotential heights and temperatures tend to be higher over the arctic and lower in middle latitudes than in the opposite extreme at the same time the polar night stratospheric jetstream tends to be weaker and the subtropical westerlies to be stronger the conclusions are based on 11 extremes within a 15 year period and on data at standard pressure levels as high as 10 mb

mean sea level and beach width variation at scarborough western australia abstract a sixteen year record of beach width change at six profile stations on scarborough beach in the perth metropolitan area of western australia was analysed by eliot and colleagues their results described long term beach progradation measured over the sixteen years and identified cyclic beach changes with periods of 0 5 1 0 3 5 and 7 0 yrs and a long term secular progradational trend in this paper the beach width measurements from scarborough are compared with twelve years of mean sea level record from fremantle western australia approximately 18 km south of scarborough beach the annual cycles of each respond in an inverse manner such that a 1 cm rise in mean sea level corresponds with a 1 m decrease in the beach width the sea level rise leads the beach width retreat by approximately one fifth of a cycle a long period oscillation of 3 5 yrs in the mean sea level shows a similar 100 1 ratio for beach gradation with a lead of approximately one tenth of a cycle however the secular trend in beach width change was not evident in the mean sea level record indicating that the progradation is tied to other processes such as a northerly sediment drift related to prevailing sw swell and associated current activity

pacific east asian teleconnection how does enso affect east asian climate observational evidence is presented to show a teleconnection between the central pacific and east asia during the extreme phases of enso cycles this pacific east asian teleconnection is confined to the lower troposphere the key system that bridges the warm cold events in the eastern pacific and the weak strong east asian winter monsoons is an anomalous lower tropospheric anticyclone cyclone located in the western north pacific the western north pacific wind anomalies develop rapidly in late fall of the year when a strong warm or cold event matures the anomalies persist until the following spring or early summer causing anomalously wet dry conditions along the east asian polar front stretching from southern china northeastward to the east of japan kuroshio extension using atmospheric general circulation and intermediate models the authors show that the anomalous philippine sea anticyclone results from a rossby wave response to suppressed convective heating which is induced by both the in situ ocean surface cooling and the subsidence forced remotely by the central pacific warming the development of the anticyclone is nearly concurrent with the enhancement of the local sea surface cooling both the anticyclone and the cooling region propagate slowly eastward the development and persistence of the teleconnection is primarily attributed to a positive thermodynamic feedback between the anticyclone and the sea surface cooling in the presence of mean northeasterly trades the rapid establishment of the philippine sea wind and sst anomalies implies the occurrence of extratropical tropical interactions through cold surge induced exchanges of surface buoyancy flux the central pacific warming plays an essential role in the development of the western pacific cooling and the wind anomalies by setting up a favorable environment for the anticyclone sst interaction and midlatitude tropical interaction in the western north pacific

dynamic effect of last glacial maximum ice sheet topography on the east asian summer monsoon the effect of ice sheet topography on the east asian summer monsoon easm during the last glacial maximum is studied using ccsm3 in a hierarchy of model configurations it is found that receding ice sheets result in a weakened easm with the reduced ice sheet thickness playing a major role the lower ice sheet topography weakens the easm through shifting the position of the midlatitude jet and through altering northern hemisphere stationary waves in the jet shifting mechanism the lowering of ice sheets shifts the westerly jet northward and decreases the westerly jet over the subtropics in summer which reduces the advection of dry enthalpy and in turn precipitation over the easm region in the stationary wave mechanism the lowering of ice sheets induces an anomalous stationary wave train along the westerly waveguide that propagates into the easm region generating an equivalent barotropic low response this leads to reduced lower tropospheric southerlies which in turn reduces the dry enthalpy advection into east asia and hence the easm precipitation less

efficiency of eigenfunctions for discriminant analysis of subaerial non tidal beach profiles abstract a one year set of subaerial beach profiles from the southern mediterranean beaches of israel measured at fortnightly intervals was analysed by applying eigenfunctions and computations of scour and fill the eigenfunction associated with the first eigenvalue is shown not to be efficient for beach categorization however the second eigenfunction effectively classified three subenvironments of the exposed beaches these constitute the upper foreshore the stable segment and the upper backshore a model of subaerial beach types based on the second eigenfunction is confirmed by scour and fill indices and by morphological characteristics

the unusual summer of 1994 in east asia iod teleconnections 1 an extremely hot and dry summer of 1994 was reported in east asian countries using observational data we have demonstrated that the indian ocean dipole iod is at least one possible cause of the abnormal east asian summer climate an anomalous cyclonic circulation over the western pacific and the southern china weakened the monsoonal northward flow in the lower troposphere an anomalous anticyclonic circulation with the equivalent barotropic structure around japan korea and the northeastern part of china caused the hot and dry summer of 1994 this accumulation of the lower potential vorticity in the far east is related to the wave activity from the mediterranean sahara region the monsoon desert mechanism connects a rossby wave source with the iod induced diabatic heating around the bay of bengal another rossby wave train pattern was generated in the upper troposphere and propagates northeastward from the southern china both the rossby wave patterns influenced the circulation changes over east asia

the impact of temperate reefs on 34years of shoreline and vegetation line stability at yanchep southwestern australia and implications for coastal setback coastal setbacks are used to protect populations and infrastructure and involve determining baselines and historic trends in shoreline movements assessing these movements can be difficult on coasts with especially complex geomorphology such as due to rock and coral reefs reefs are often assumed to provide coastal protection and stability however little is known about the spatial variability of beach dynamics on beaches with reefs over inter annual and decadal time scales spatial variability in inter annual vegetation line and shoreline stability was assessed on three adjacent beaches at yanchep southwestern australia using 34 years 1974 2008 of aerial photographs over 96 of the study area beach width narrowed over the 34 years this trend was statistically significant on 83 of the middle beach 43 of the northern beach and only 29 of the southern beach the maximum mean annual change in beach width was 1 7 m yr 1 at the south end of the southern beach the first mode of the empirical orthogonal function eof explained 45 of the variability alongshore and correlated significantly p 0 05 with the 90th percentile of annual wave height and annual mean sea level beach rotation and reef controlled currents resulted in cellular beach morphodynamics and vegetation line and shoreline movements varied greatly alongshore on one occasion the beach widened by more than 50 m inter annually while other areas eroded by 50 m the southern beach that was fronted by the most continuous and highest supratidal section of reef was the most temporally variable even the vegetation line here moved by up to 20 m inter annually so cannot be assumed to be a stable baseline for setback the impact of reefs on inter annual shoreline and vegetation line stability should be considered in future guidelines for determining coastal setback

possible link of an exceptionally strong east asian summer monsoon to a la nina like condition during the interglacial mis 13 abstract previous studies from the central and eastern chinese loess plateau clp showed that the s5 1 paleosol which corresponding to marine isotope stage mis 13 was the strongest developed during the last million years suggesting extremely strong east asian summer monsoon easm however evidence shows that regional diversity exists in the relative intensity of the s5 1 soil formation in this study we first verify systematically the s5 1 soil development across the whole clp by using numerous loess records we then examine the spatial variation of the magnetic susceptibility of different loess paleosol sections to identify the spatial change of the easm intensity during mis 13 we also compare the loess records with other monsoon records in china our results show that in central clp s5 1 is indeed the strongest developed as suggested by previous studies whereas in the western clp it is weakly developed and the s4 paleosol developed during mis 11 is the strongest as compared to mis 11 the northern front of the easm during mis 13 didn t penetrate into western clp but was located more northerly and eastward based on sea surface temperature records in the tropical pacific we suggest that the temporal and spatial abnormal variation of the easm during mis 13 could be related to a strong la nina or la nina like climate condition under such condition the western pacific subtropical high wpsh becomes weaker and retreats more northeastward leading to more precipitation in the mid east region of northern china but less rainfall in the western inland

landslide hazard zoning using the gis approach a case study from the ramganga catchment himalayas abstract this paper deals with the development of a technique for risk assessment of landslide hazards using the geographic information system gis approach the method has been applied to the ramganga catchment lying in the lower himalayas and the investigations are based on multi data sets the landslide activity is related to a number of parameters viz lithology land use distance from major tectonic shear zone and azimuth direction based on the data for 522 landslides in four selected sub basins an index value called landslide nominal risk factor lnrf is defined and developed for each of the important factors different weights have been assigned to the terrain depending upon the lnrf and integrated in an ordinal scale to help locate areas of high moderate and low landslide risk

atmospheric summer circulation and coastal upwelling in the arabian sea during the holocene and the last glaciation accumulation rates of biogenic and lithogenic components were studied in 39 turbidite free well dated sediment cores from the northern indian ocean to define the proportions of fluvial and eolian input and to reconstruct quaternary patterns of coastal upwelling the majority of dust deposited in the western arabian sea during the holocene about 100 106 t yr 1 is advected from arabia by northwesterly winds which overlie the low level southwest monsoon the glacial increase in dust flux to 160 106 t yr 1 culminated in the northern arabian sea most probably due to i entrainment of dust rich in chlorite dolomite and lithogenic carbonate in the then dry persian gulf and ii a southward shift of the mean position of the southwest monsoon during glacial summer this shift is recorded in reduced accumulation rates of biogenic opal and increased rates of marine carbonate off somalia and oman both the terrigenous and biogenic sediment records show that the northwesterly winds and the southwest monsoon persisted over the last 27 000 yr as well as the asian continental summer heat low however the glacial seasonal time span of the southwest monsoon season was much reduced most likely because of a delay in the seasonal onset of the southwest monsoon

impacts of extremely asymmetrical polar ice sheets on the east asian summer monsoon during the mis 13 interglacial abstract marine isotope stage mis 13 500 ka ago was a relatively weak interglacial according to the benthic 18o and antarctic ice core records however proxy records from the northern hemisphere indicate that mis 13 was at least as warm as or even warmer than more recent interglacials with an extremely strong summer monsoon and possible melting of the greenland ice sheet in this study assuming an asymmetric hemispheric climate we investigate the response of the east asian summer monsoon to various greenland and antarctic ice sheet sizes using a set of sensitivity experiments with the hadcm3 model through factor separation analysis results show that with no greenland ice sheet and a large antarctic ice sheet there is an enhancement of summer monsoon precipitation in the east asian monsoon region of up to 7 in agreement with the direction of change from proxy reconstructions for china this enhancement is associated with a stronger land sea thermal contrast more water vapor transport to east asia and a northward shift of the intertropical convergence zone the response to the greenland ice sheet removal is related to thermodynamic and topographical effects that influence the east asian monsoon through an orographically induced wave train the response to the larger antarctic ice sheet involves stronger upwelling of circumpolar deep water in the southern ocean melts the sea ice leading to a warmer sst this warming propagates to the north affecting the east asian summer monsoon

variation in subaerial beach sediment volume on a small sandy beach over a monthly lunar tidal cycle abstract three major patterns of sediment movement along 0 5 m deep horizontal segments of beachface on a small sandy beach at coledale new south wales were determined by empirical orthogonal function eof analysis of a 36 day record of beach change the fundamental beach response is identified by the first eigenfunction mode the mode describes sediment transfers occurring over the beachface between the low tide zone and the berm crest as well as sediment movement along the beach the alongshore translocations occurred about a nodal point located approximately 0 75 of distance along the beach from its southern end transfers across the beach were established by comparing the time series associated with the eigenfunctions describing alongshore transfers of sediment in different segments the slice to slice comparisons showed an increasing phase down the beachface from the berm crest segment to the mid tidal zone the phase difference was approximately 2 5 days per 0 5 m segment the fundamental beach response and secondary sediment transfers typical of the supratidal zone occur with an apparent 28 30 day lunar tide cycle they were unrelated to short term variations in the incident wave amplitude lower down the beachface the time series associated with the eigenfunction describing sediment translocations in the mid tidal zone is aperiodic the irregularities can be linked to particular process events however similar beach changes were not always related to similar process conditions and they were not simply related to wave regime fluctuations the patterns of sediment movement along coledale beach were consistent with similar patterns reported from elsewhere by clarke and eliot 1982 1983a in that they were closely related to variation in the nearshore water circulation system in particular nodal points identified by the eof analysis commonly occurred on the beachface landward of inshore regions where bars most frequently developed the antinodal positions were similarly associated with regions where rip channels are frequently formed

the southwest indian monsoon over the last 18 000 years previously published results suggest that the strength of the sw indian monsoon can vary significantly on century to millenium time scales an observation that has important implications for assessments of future climate and hydrologic change over densely populated portions of asia we present new well dated multi proxy records of past monsoon variation from three separate arabian sea sediment cores that span the last glacial maximum to late holocene to a large extent these records confirm earlier published suggestions that the monsoon strengthened in a series of abrupt events over the last deglaciation however our data provide a somewhat refined picture of when these events took place and suggest the primacy of two abrupt increases in monsoon intensity one between 13 and 12 5 ka and the other between 10 and 9 5 ka this conclusion is supported by the comparisons between our new marine data and published paleoclimatic records throughout the african asian monsoon region the comparison of data sets further supports the assertion that maximum monsoon intensity lagged peak insolation forcing by about 3000 years and extended from about 9 5 to 5 5 ka the episodes of rapid monsoon intensification coincided with major shifts in north atlantic european surface temperatures and ice sheet extent this coincidence coupled with new climate model experiments suggests that the large land sea thermal gradient needed to drive strong monsoons developed only after glacial conditions upstream of and on the tibetan plateau receded cold north atlantic sea surface temperatures european ice sheets and extensive asian snow cover it is likely that abrupt changes in seasonal soil hydrology were as important to past monsoon forcing as were abrupt snow related changes in regional albedo our analysis suggests that the monsoon responded more linearly to insolation forcing after the disappearance of glacial boundary conditions decreasing gradually after about 6 ka our data also support the possibility that significant century scale decreases in monsoon intensity took place during the early to mid holocene period of enhanced monsoon strength further highlighting the need to understand paleomonsoon dynamics before accurate assessments of future monsoon strength can be made

decadal variations of the relationship between the summer north atlantic oscillation and middle east asian air temperature 1 the relationship between the summer july september north atlantic oscillation snao and simultaneous east asian air temperature is investigated the results show that the snao is related to middle east asian summer air temperature however this linkage varies with time on decadal timescale a strong connection appears after the late 1970s but a weak connection before the late 1970s further analysis indicates that this instable relationship may have resulted from the shift of the snao mode around the late 1970s in the period of 1979 2003 the centers of the snao mode are located more eastward a positive phase negative phase snao produces a strong lower level divergence convergence over the asian jet entrance region in turn stimulates a strong upper level convergence divergence via the ekman pumping such a convergence divergence then excites a zonally oriented quasi stationary barotropical rossby wave train along the asian upper level jet thus the snao signal is transported eastward to east asia resulting in an anomalous summer air temperature over middle east asia however in the period of 1951 1975 the centers of the snao mode are located more westward the associated upper level divergence convergence is away from the asian jet entrance region and the snao signal cannot be transported eastward to east asia hence the connection is broken

time transgressive onset of the holocene optimum in the east asian monsoon region abstract the east asian summer monsoon affects precipitation and hence vegetation in the densely populated northwest pacific region yet a long standing controversy exists concerning the spatial and temporal dynamics of the holocene optimum ho in the east asian monsoon region here we use a detailed 14 000 year record reconstructing vegetation variations from a strategically selected crater lake from northeast china as well as a compilation of previous paleoclimatic studies to show that the ho began around 6 000 cal a bp in northeast china significantly later than generally recognized by comparing our paleoenvironmental data with holocene vegetation records from other regions of east asia we identified a marked northward shift for the onset of the ho from 10 260 cal a bp in south china to 6 000 cal a bp in northeast china the gradual northward transgression of the vegetation change could be caused by both the temperature and precipitation changes in different regions finally we fitted a regression model of the start of the ho period versus latitude which allowed us to make predictions for the beginning of the ho at different geographical locations this study reveals a strong relationship between latitude and the initiation of the ho and provides a window towards better understanding the forcing of vegetation changes in the east asian monsoon region

relationship between the tibetan plateau heating and east asian summer monsoon rainfall 1 this study reveals the close correspondence between the interannual variability of the dominant east asian summer rainfall pattern and the diabatic heating over the tibetan plateau in both spring and summer the heating fluctuation over the tibetan plateau is associated with two wave like circulation patterns which bear the characteristics of forced rossby wave emanating away from the deep heating the wave like pattern in turn affects the east asian summer rainfall because of the persistent heating over the tibetan plateau from spring to summer and its possible effect on the surrounding areas the heating index defined in this study can be used as a good predictor for the jja heating and precipitation distributions evidences shown suggest that external conditions other than the sst anomaly must be considered to understand the interannual variability of the east asian summer rainfall

the generation of global rotational flow by steady idealized tropical divergence abstract tropical convective heating is balanced on the large scale by the adiabatic cooling of ascent the horizontal divergence of the wind above this heating may be viewed as driving the upper tropospheric rotational wind field a vorticity equation model is used to diagnose this relationship it is shown that because of the advection of vorticity by the divergent component of the flow the rossby wave source can be very different from the simple fd source often used in particular an equatorial region of divergence situated in easterly winds can lead to a rossby wave source in the subtropical westerlies where it is extremely effective this part of the source can be relatively insensitive to the longitudinal position of the equatorial divergence a divergence field which is asymmetric about the equator can lead to a quite symmetric rossby wave source for a steady frictionless flow the rossby wave source averaged over regions within closed streamfunction or absolute vorticity contours is under cert

large scale dynamics of the meiyu baiu rainband environmental forcing by the westerly jet abstract meiyu baiu is the major rainy season from central china to japan brought by a zonally elongated rainband from june to mid july large scale characteristics and environmental forcing of this important phenomenon are investigated based on a reanalysis dataset the meiyu baiu rainband is accompanied by a trough of sea level pressure horizontal shears and sharp moisture gradients near the surface a westerly jet tilted northward with height and large northeastward moisture transport from the south the analysis here reveals the westerly jet as an important culprit for meiyu baiu along the rainband mean ascending motion corresponds well with a band of warm horizontal temperature advection in the midtroposphere throughout summer this adiabatic induction of upward motion originates from the advection of warm air by the westerlies from the eastern flank of the tibetan plateau the ascending motion both induces convection and is enhanced by the resultant condensational heating the westerly jet anch

the influence of continental ice sheets on the climate of an ice age the climate influence of the land ice that existed 18 000 years before present 18k b p is investigated by use of a general circulation model of the atmosphere coupled with a static mixed layer ocean simulated climates are obtained from two versions of the model one with the land ice distribution of the present and the other with that of 18k b p in the northern hemisphere the tropospheric flow field is strongly influenced by the laurentide ice sheet and features a split flow straddling the ice sheet with a strong jet stream forming the southern branch the northern branch of the flow brings very cold air over the north atlantic ocean where thick sea ice is maintained the distribution of sea surface temperature sst difference between the two experiments in the northern hemisphere resembles the difference between the sst at 18k b p and at present as estimated by the climap project 1981 the 18k b p ice sheets have very little influence upon atmospheric temperature and sst in the southern hemisphere this is because the interhemispheric heat transport hardly changes as the loss of heat energy due to the reflection of solar radiation by continental ice sheets in the northern hemisphere is almost completely counterbalanced by the in situ reduction of upward terrestrial radiation hydrologic changes in the model climate are also found with statistically significant decreases in soil moisture occurring in a zone located to the south of the ice sheets in north america and eurasia these findings are consistent with some geological evidence of regionally drier climates from the last glacial maximum

how to measure the strength of the east asian summer monsoon defining the intensity of the east asian summer monsoon easm has been extremely controversial this paper elaborates on the meanings of 25 existing easm indices in terms of two observed major modes of interannual variation in the precipitation and circulation anomalies for the 1979 2006 period the existing indices can be classified into five categories the east west thermal contrast north south thermal contrast shear vorticity of zonal winds southwesterly monsoon and south china sea monsoon the last four types of indices reflect various aspects of the leading mode of interannual variability of the easm rainfall and circulations which correspond to the decaying el nino while the first category reflects the second mode that corresponds to the developing el nino the authors recommend that the easm strength can be represented by the principal component of the leading mode of the interannual variability which provides a unified index for the majority of the existing indices this new index is extremely robust captures a large portion 50 of the total variance of the precipitation and three dimensional circulation and has unique advantages over all the existing indices the authors also recommend a simple index the reversed wang and fan index which is nearly identical to the leading principal component of the easm and greatly facilitates real time monitoring the proposed index highlights the significance of the mei yu baiu changma rainfall in gauging the strength of the easm the mei yu which is produced in the primary rain bearing system the east asian ea subtropical front better represents the variability of the easm circulation system this new index reverses the traditional chinese meaning of a strong easm which corresponds to a deficient mei yu that is associated with an abnormal northward extension of southerly over northern china the new definition is consistent with the meaning used in other monsoon regions worldwide where abundant rainfall within the major local rain bearing monsoon system is considered to be a strong monsoon

evaluation of a small volume renourishment strategy on a narrow mediterranean beach abstract a renourishment strategy for width maintenance of a mediterranean beach was evaluated using historical aerial photographs and topographic surveys the 5 5 km can picafort beach balearic islands spain consists of urbanised areas with associated anthropogenic pressures and a natural park extending for about 1 5 km where a backshore dune and a lagoon system have been preserved with the exception of this protected area the beach has been recurrently nourished over the past 20 years using relatively small volumes of sand

annual and interannual changes on a reef fringed pocket beach kailua bay hawaii abstract historical aerial photographs and topographic survey sheets are used to establish a 70 year shoreline history 1926 1996 for kailua beach oahu hawaiian islands the shoreline has migrated seaward over this period at an average rate of 0 5 m yr with a maximum net accretion along the beach of 58 7 m and a maximum net erosion of 13 2 m net accretion has taken place even while sea levels have risen on the order of 0 1 m semi annual and monthly beach profile surveys 1995 1999 at seven transects reveal short term variations of shoreline position sand volume and beach shape a relationship between beach width and corresponding sand volume fluctuations established from the beach profile data is applied to the historical shoreline change data to establish a history of sand volume fluctuations results show that kailua has experienced a net accretion of 673 000 m3 of sand over the period 1926 1996 with average annual rates of volume change varying between 6 8 m3 m yr and 0 1 m3 m yr the most recent period 1989 1996 shows a net volume increase of 41 000 m3 given the lack of sand inputs at the ends of the beach exchange with offshore deposits is a likely mechanism for long term accretional trends seasonal fluctuations in kailua beach morphology dominate the variability with a response to seasonal wave state that varies along the length of the beach in magnitude and sign at least four alongshore zones are observed with the first and third zones exhibiting high low sand volumes during the summer winter and the second and fourth zones exhibiting opposite behavior with high low volumes during the winter summer although seasonal sand accumulation varies along the beach the overall beach profile is largely maintained moreover changes in sand volume occur in phase over the subaqueous and subaerial sections of the beach this behavior suggests that longshore rather than cross shore sand transport is important at annual time scales a simple seasonal transport pattern is proposed to account for these observed fluctuations which depends in part on the topography of the offshore reef

the effects of storms and storm generated currents on sand beaches in southern maine usa storms are one of the most important controls on the cycle of erosion and accretion on beaches current meters placed in shoreface locations of saco bay and wells embayment me recorded bottom currents during the winter months of 2000 and 2001 while teams of volunteers profiled the topography of nearby beaches coupling offshore meteorological and beach profile data made it possible to determine the response of nine beaches in southern maine to various oceanographic and meteorological conditions the beaches selected for profiling ranged from pristine to completely developed and permitted further examination of the role of seawalls on the response of beaches to storms current meters documented three unique types of storms frontal passages southwest storms and northeast storms in general the current meter results indicate that frontal passages and southwest storms were responsible for bringing sediment towards the shore while northeast storms resulted in a net movement of sediment away from the beach during the 1999 2000 winter there were a greater percentage of frontal passages and southwest storms while during the 2000 2001 winter there were more northeast storms the sediment that was transported landward during the 1999 2000 winter was reworked into the berm along moderately and highly developed beaches during the next summer a northeast storm on march 5 6 2001 resulted in currents in excess of 1 m s 1 and wave heights that reached six meters the storm persisted over 10 high tides and caused coastal flooding and property damage topographic profiles made before and after the storm demonstrate that developed beaches experienced a loss of sediment volume during the storm while sediment was redistributed along the profile on moderately developed and undeveloped beaches two months after the storm the profiles along the developed beaches had not reached their pre storm elevation in comparison the moderately developed and undeveloped beaches reached and exceeded their pre storm elevation and began to show berm buildup characteristic of the summer months

intraseasonal teleconnection between the summer eurasian wave train and the indian monsoon this study investigated the most recurrent coupled pattern of intraseasonal variability between midlatitude circulation and the indian summer monsoon ism the leading singular vector decomposition svd pattern reveals a significant coupled intraseasonal variation between a rossby wave train across the eurasian continent and the summer monsoon convection in northwestern india and pakistan hereafter referred to as nism the wave train associated with an active phase of nism rainfall displays two high pressure anomalies one located over central asia and the other over northeastern asia they are accompanied by increased rainfall over the western siberia plain and northern china and decreased rainfall over the eastern mediterranean sea and southern japan the circulation of the wave train shows a barotropic structure everywhere except the anomalous central asian high located to the northwest of india where a heat induced baroclinic circulation structure dominates the time lagged svd analysis shows that the midlatitude wave train originates from the northeastern atlantic and traverses europe to central asia the wave train enhances the upper level high pressure and reinforces the convection over the nism region meanwhile it propagates farther toward east asia along the waveguide provided by the westerly jet after an outbreak of nism convection the anomalous central asian high retreats westward composite analysis suggests a coupling between the central asian high and the convective fluctuation in the nism the significance of the midlatitude ism interaction is also revealed by the close resemblance between the individual empirical orthogonal functions and the coupled svd modes of the midlatitude circulation and the ism it is hypothesized that the eastward and southward propagation of the wave train originating from the northeastern atlantic contributes to the intraseasonal variability in the nism by changing the intensity of the monsoonal easterly vertical shear and its associated moist dynamic instability on the other hand the rainfall variations over the nism reinforce the variations of the central asian high through the monsoon desert mechanism thus reenergizing the downstream propagation of the wave train the coupling between the eurasian wave train and nism may be instrumental for understanding their interaction and can provide a way to predict the intraseasonal variations of the indian summer monsoon and east asian summer monsoon

a generalized equilibrium model for predicting daily to interannual shoreline response coastal zone management requires the ability to predict coastline response to storms and longer term seasonal to interannual variability in regional wave climate shoreline models typically rely on extensive historical observations to derive site specific calibration to circumvent the challenge that suitable data sets are rarely available this contribution utilizes twelve 5 year shoreline data sets from around the world to develop a generalized model for shoreline response the shared dependency of model coefficients on local wave and sediment characteristics is investigated enabling the model to be recast in terms of these more readily measurable quantities study sites range from microtidal to macrotidal coastlines spanning moderate to high energy beaches the equilibrium model adopted here includes time varying terms describing both the magnitude and direction of shoreline response as a result of onshore offshore sediment transport between the surf zone and the beach face the model contains two coefficients linked to wave driven processes 1 the response factor that describes the memory of a beach to antecedent conditions and 2 the rate parameter c that describes the efficiency with which sand is transported between the beach face and surf zone across all study sites these coefficients are shown to depend in a predictable manner on the dimensionless fall velocity that in turn is a simple function of local wave conditions and sediment grain size when tested on an unseen data set the new equilibrium model with generalized forms of and c exhibited high skill brier skills score bss 0 85

behaviour of beach profiles during accretion and erosion dominated periods beach profiles have been surveyed at monthly intervals between 1972 and 1988 at moruya on the south coast of new south wales australia four profile sites have been used as a data set to provide an understanding of changes to beach volume width and shape moruya beach represents a moderately high energy microtidal environment which responds in a dramatic way to major storm events such as those experienced in the mid 1970s this study distinguishes between profile characteristics associated with such a period erosion dominated or edp compared with periods when accretion dominated adp accompanied by foredune expansion in both height and width