224ra 228ra and226ra in winyah bay and delaware bay the first224ra t1 2 3 64days measurements from mixing zones of estuarine systems are presented for the pee dee river winyah bay and delaware bay estuaries high resolution gamma ray spectrometry was used to determine224ra 228ra t1 2 5 7years and226ra t1 2 1622years activity ratios desorption and diffusion from suspended and bottom sediments contributes to the non conservative increases of the three isotopes in each systems in delaware bay224ra concentrations were nearly constant over the 2 5 to 15 salinity range where two turbidity maximum zones are located 228th scavenging onto the suspended particles in the turbid zones may supply a regenerative source of224ra in this system samples collected on the ebb and flood tide from a salt marsh along delaware bay have a 5 fold increase in224ra from flood to ebb and 3 and 2 fold increases for228ra and226ra respectively indicating salt marshes are another source of radium to estuarine waters

a successful prediction of a strong earthquake in the southwestern hellenic arc by means of the algorithm m8 abstract in an earlier study a current tip time of increased probability has been diagnosed along the southwestern part of the hellenic arc by applying the algorithm m8 in that paper we pointed out that the current tip of duration of five years started at the end of 1986 or at the beginning of 1987 and if the algorithm m8 works reliably then it will be completed by the end of 1992 with an earthquake of a surface waves magnitude in the range 6 0 ms on november 21 1992 an earthquake of ms 6 5 took place in the candidate region in the following we discuss the applicability of the algorithm m8 to delineating critical seismic areas and the necessity of using current tips to focus the attention of multidisciplinary research for evaluating short term precursory phenomena if any

radium isotopes in the chesapeake bay 228ra and 226ra are enriched in waters of chesapeake bay through fluxes from the bottom sediments and desorption from particles entering the estuary the activity ratio of 228ra 226ra increases from 1 5 in the susquehanna river to 3 4 in waters of 15 20 salinity apparently much of the 228ra is supplied by diffusion from sediments within the bay while desorption from particles entering the bay is more important for 226ra because of the multiple inputs and long residence time of water in the bay no curvature is obvious in a plot of radium isotope concentration vs salinity

localization of intermediate term earthquake prediction relative seismic quiescence within a region which has already been diagnosed as having entered a time of increased probability tip for the occurrence of a strong earthquake can be used to refine the locality in which the earthquake may be expected to occur a simple algorithm with parameters fitted from the data in northern california preceding the 1980 magnitude 7 0 earthquake offshore from eureka depicts relative quiescence within the region of a ttp the procedure was tested without readaptation of parameters on 17 other strong earthquake occurrences in north america japan and eurasia most of which were in regions for which a tip had been previously diagnosed the localization algorithm successfully outlined a region within which the subsequent earthquake occurred for 16 of these 17 strong earthquakes the area of prediction in each case was reduced significantly ranging between 7 and 25 of the total area covered by the tip

advances in marine chemistry 1979 1982 these four years saw advances in many areas further developments in sampling and analytical techniques have opened new avenues of exploration for trace elements and particulate matter the impact of the geosecs expedition was further felt in the field of marine chemistry as the results were still being published a major field effort occurred as a follow on to the geosecs work tto and intensive sampling was performed in the newly discovered submarine hydrothermal vent fields an important and unresolved controversy has arisen regarding the ability to measure preformed co2 in the seawater system in many respects the field of marine chemistry appears to be gaining a momentum spurred by both improvements in analytic techniques and an increasing social and economic relevance

premonitory seismicity patterns near vancouver island canada abstract the search for premonitory patterns for large seismic events requires an a priori threshold to define them in the area of the explorer and juan de fuca plates the area of vancouver island canada this threshold appears to be m 6 5 the three strongest earthquakes m 6 0 which have occurred since the seismicity catalog has been acceptably complete for m 2 5 are preceded by activation of the earthquake flow in the lower magnitude range in the generalized sense depicted by the algorithm m8 suggested by soviet scientists one event of magnitude 6 0 may have been preceded by activation but two others were not the times of increased probability tip of a strong earthquake occupy about 30 of the total time space domain considered and there are no false alarms this implies a significant similarity between the earthquake flow here and in other regions of the world where algorithm m8 was tested there is a possibility which remains to be tested of anticipating future strong earthquakes in this area with an accuracy of 5 years and 100 km such anticipation could justify some precautionary measures and could be useful for attempts to make short term predictions analysis using patterns of quiescence restrict the location of the anticipated earthquake there is evidence for the coupling of seismicity in the subduction zone with that above it such interaction is a natural consequence of the model of a lithosphere as an assemblage of interacting blocks

processes driving deep convection over complex terrain a multi scale analysis of observations from cops iop 9c the convective and orographically induced precipitation study cops analyses the processes driving deep convection over complex terrain convection initiation ci is mainly not only expressed by a single process but by a variety of them which interact on different scales in time and space and finally can lead to deep convection a study of such a case over inhomogeneous terrain is presented in this article data from the cops network of stations are taken to identify the time and location of ci in many cases this is not the same location as the first convective clouds showers or even thunderstorms it is shown that the interaction of the ci processes on multiple scales locally leads to either deep convection and severe storms or calm weather the boundary conditions between the different outcomes are narrow during iop 9c 20 july 2007 a mesoscale convective system mcs embedded in a surface low over eastern france propagated north eastward and a gust front of the mcs reached the cops area during the passage of the gust front through the rhine valley convective activity was significantly reduced the gust front reached the slope of the black forest and the warm and humid air above the mountain range prior to the gust front was lifted up to 2000 m within a short time period within the air prior to the gust front aloft from the surface ci started along a north south oriented line above the crest due to insolation ahead of the gust front a convergence line developed the interaction of local scale orographic winds the regional scale gust front the mesoscale convergence line and the synoptic scale cold front led to a squall line finally individual severe convective cells formed along the outer section of the synoptic scale cold front copyright 2011 royal meteorological society

interaction of a warm season frontal system with the coastal mountains of the western united states part ii evolution of a puget sound convergence zone abstract observational analyses and numerical simulations are used to investigate a puget sound convergence zone pscz event that occurred in the lee of the olympic mountains of washington state the pscz which develops when low level airstreams are forced to converge over puget sound by the regional orography is frequently associated with a mesoscale swath of clouds and precipitation across the central puget sound that stretches eastward over the western side of the cascade mountains it was found that latent heat release enhances the pscz circulation and associated precipitation both the olympic and the cascade mountains are important in the formation of the pscz the olympics deflect the low level onshore flow into two branches one along the strait of juan de fuca and another around the southern flank of the olympics in addition a lee trough which develops to the east of this barrier induces convergence over the central puget sound the cascades deflect low level flow over northern puget sound

influence of the wind profile on the initiation of convection in mountainous terrain a number of days with small precipitating convective cells were investigated using weather radars during the cops convective and orographically induced precipitation study field campaign in the region of the vosges and the rhine valley in central europe depending on the weather situation two distinct mechanisms could be identified for the initiation of convection on some days cells were initiated over the ridge of the vosges whereas on other days cells were initiated in the lee of the vosges the initiation of convection appeared to be concentrated in a few favourable locations using the froude number it was possible to describe the two distinct mechanisms when the froude number was low the flow was diverted around the vosges and thermally driven convergence at the ridge initiated convection whereas when the froude number was high the flow passed through mountain gaps and then converged on the lee side with the flow in the rhine valley the convergence on the lee side was enhanced at locations where the outflows through valleys converged low froude numbers were accompanied by weak winds varying with height whereas high froude numbers were observed during situations with stronger southwesterly winds increasing with height

226ra contents and 228ra226ra activity ratios of the fenland rivers and the wash eastern england spatial and seasonal trends measurements of 226ra and 228ra in the fenland rivers and the wash show that physical and hydrological factors play an important role in controlling the transport and fate of radium isotopes in the surficial environment higher 226ra contents and lower 228ra226ra activity ratios are found in waters from catchments with a greater proportion of carbonate rich source materuals this relationship is more obvious during periods of high runoff and river discharge when enhanced surficial weathering and regolith saturation takes place in the nearshore zone 226ra content is relatively uniform whilst 228ra226ra activity ratio is controlled by ionic concentrations cl so4 and co3 and the acquisition of marine characteristics the observed 228ra226ra activity ratio trend can be attributed to a combination of conservative mixing and radium desorption from suspended sediments whilst more uniform 226ra contents may reflec bottom sediment diffusion of excess 226ra over a greater area the relative importance of these two processes is controlled by differential input from the freshwater and saline end members of the estuary

testing an earthquake prediction algorithm a test to evaluate earthquake prediction algorithms is being applied to a russian algorithm known as m8 the m8 algorithm makes intermediate term predictions for earthquakes to occur in a large circle based on integral counts of transient seismicity in the circle in a retroactive prediction for the period january 1 1985 to july 1 1991 the algorithm as configured for the forward test would have predicted eight of ten strong earthquakes in the test area a null hypothesis based on random assignment of predictions predicts eight earthquakes in 2 87 of the trials the forward test began july 1 1991 and will run through december 31 1997 as of july 1 1995 the algorithm had forward predicted five out of nine earthquakes in the test area which success ratio would have been achieved in 53 of random trials with the null hypothesis

on thermally forced circulations over heated terrain abstracta combination of analytical and numerical models is used to gain insight into the dynamics of thermally forced circulations over diurnally heated terrain solutions are obtained for two layer flows representing the boundary layer and the overlying free troposphere over an isolated mountainlike heat source a scaling based on the linearized boussinesq system of equations is developed to quantify the strength of thermally forced updrafts and to identify three flow regimes each with distinct dynamics and parameter sensitivities this scaling closely matches corresponding numerical simulations in two of these regimes the first characterized by a weakly stable boundary layer and significant background winds and the second by a strongly stable boundary layer in the third regime characterized by weak winds and weak boundary layer stability this scaling is outperformed by a fundamentally different scaling based on thermodynamic heat engines within this regime the inability of wind ventilation or

source and distribution of dissolved radium in the bega river estuary southeastern australia abstract measurements of the activities of the four naturally occurring radium isotopes in the surface water and porewater of an estuary have yielded information on the release of radium from sediments and on the extent of surface water porewater interaction in the estuary under low flow conditions the non conservative behaviour of dissolved radium in the estuary is almost entirely due to the flux of radium from estuarine bed sediments radium accumulates in bottom sediment porewater and is then mixed with estuarine surface water probably as a result of tidal action it is shown experimentally that the enrichment of the short lived isotopes 224ra and 223ra relative to 226ra in estuarine porewater can be explained by the repeated leaching of radium from bottom sediments by saline water and the rapid regeneration of the short lived isotope activity from their sediment bound parent nuclides the leaching of radium from bottom sediments is apparently occurring on a time scale which is long weeks months compared with the 224ra and 223ra half lives indicating that the amount of ion exchangeable radium adsorbed to the sediments is large compared with the amount dissolved in porewater by applying a simple 2 d steady state multi box model 224ra and 223ra surface water and porewater concentrations have been used to estimate the daily flux of porewater crossing the sediment water interface in the bega estuary this flux is found to be about 15 of the estuary volume

a mesoscale data analysis and downscaling method over complex terrain abstract a mesoscale data analysis method for meteorological station reports is presented irregularly distributed measured values are combined with measurement independent a priori information about the modification of analysis fields due to topographic forcing as a physical constraint to a thin plate spline interpolation the so called fingerprint method recognizes patterns of topographic impact in the data and allows for the transfer of information to data sparse areas the results of the method are small scale interpolation fields on a regular grid including topographically induced patterns that are not resolved by the station network presently the fingerprint method is designed for the analysis of scalar meteorological variables like reduced pressure or air temperature the principles for the fingerprint technique are based on idealized influence fields they are calculated for thermal and dynamic surface forcing for the former the effects of reduced air volumes in valleys the elevated heat s

226ra and 228ra in the mixing zones of the pee dee river winyah bay yangtze river and delaware bay estuaries 226ra and 228ra have non conservative excess concentrations in the mixing zones of the pee dee river winyah bay estuary the yangtze river estuary and the delaware bay estuary laboratory experiments using pee dee river sediment indicate desorption of 226ra to increase with increasing salinities up to 20 in winyah bay desorption from river borne sediments could contribute almost all of the increases for both isotopes desorption adds only a portion of the excess 228ra measured in the yangtse river and adjacent shelf waters and delaware bay in the yangtze river the mixing zone extends over a considerable portion of the continental shelf where 228ra is added to the water column by diffusion from bottom sediments while 226ra concentrations decrease from dilution diffusion of 228ra from bottom sediments in delaware bay primarily occurs in the upper part of the bay 22 water where fine grained sediments predominate a diffusive flux for 228ra of 0 33 dpm cm 2 year was determined for delaware bay

observation of convection initiation processes with a suite of state of the art research instruments during cops iop 8b in the afternoon of 15 july 2007 a thunderstorm was initiated within a line of cumulus clouds which formed parallel to the crest of the black forest mountains during the intensive observation period iop 8b of the convective and orographically induced precipitation study cops this paper extends the analysis of processes that led to convection initiation ci i e the transition from shallow to deep convection on this day with the data from several cops instruments that have not been considered in previous studies in particular the boundary layer structure lids and the water vapour field in the pre convective environment of the event are discussed for this purpose we investigated measurements of water vapour lidars temperature lidars and wind lidars profiles from radiosondes in situ aircraft data and gridded data of weather stations as well as gps integrated water vapour data and satellite imagery thermally driven circulation systems formed over both the black forest and the vosges mountain ranges which resulted in local convergence zones these superimposed with the large scale convergence in the black forest area in the presence of sufficient moisture and updraught clouds formed close to the mountain crests the related latent heat release allowed larger thermals to be produced which may have had a positive feedback on stabilizing these convergence zones as a whole we believe that differences in the moisture field explain why convection remained shallow and sparse over the vosges mountains because these differences were responsible for differences in convective inhibition cin the stationary location of the convergence zone over the southern black forest was probably decisive for ci because it constantly transported sensible and latent heat into the area in which ci took place

radium isotopes in the orinoco estuary and eastern caribbean sea radium isotopes provide a means of identifying the source of freshened waters in the ocean and determining the time elapsed since these waters were in the estuary we present evidence that during april waters from the amazon mixing zone pass within 50 km of the mouth of the orinoco river these amazon waters are characterized by a lower 228ra 226ra activity ratio ar than are waters from the orinoco at similar salinities during autumn the increased discharge of the orinoco displaces the freshened amazon waters seaward yet the two can be distinguished clearly within the caribbean sea waters of orinoco origin carry a characteristic radium signature including excess activities of 224ra this isotope may be used to estimate the time elapsed since the waters were removed from contact with sediments current speeds based on 224ra dating ranged from 15 to 33 cm s during april the radium isotopes also provide an assessment of sediment mixing in the estuary during low discharge april considerable mixing of older sediment by physical or biological processes or dredging maintained high activities of 228ra in the estuary and produced the highest 228ra 226ra ar s yet measured in any estuary during high discharge september a large fraction of the 228ra was derived from desorption from fresh sediment rather than mixing of older sediments activities of 224ra were high in the estuary during both high and low discharge indicating that considerable mixing of recently introduced sediment must occur during each period the high 224ra 228ra ar s measured in september imply that the same sediments were being resuspended during high discharge and that there was little exposure of older sediments which had been stored in the estuary for months to years during april 224ra and 228ra activities in the water were about equal indicating that most of the sediment being resuspended had been stored in the estuary long enough to reestablish radioactive equilibrium in the 232th decay series i e 20 years

initiation of convection over the black forest mountains during cops iop15a doppler on wheels radar observations made during the convective and orographically induced precipitation study cops on 12 august 2007 showed that precipitating clouds only developed between the north south orientated murg and nagold valleys of the northern black forest the clouds produced moderate precipitation the weather research and forecasting wrf model run at 700 m horizontal resolution in the inner domain was able to simulate the location of the precipitation insight is therefore gained into the physical mechanisms responsible for the initiation and development of the convection convergence lines resulting from thermally driven flows constrained the initial location of the convection within warm and moist cores produced by heating on elevated surfaces the heaviest precipitation was later produced by secondary convection which was initiated within the cores at the boundary between cold pool outflows and thermal flows copyright 2011 royal meteorological society

radium isotopes in coastal waters on the amazon shelf abstract radium isotope distributions on the continental shelf adjacent to the amazon river are a complex function of salinity the river and seawater endmembers for each radium isotope are low data from intermediate salinities plot as a highly scattered region above the conservative mixing line connecting the river and ocean endmembers spatial and temporal variability in sediment mixing and water residence times cause the scatter in the radium isotope data we have used the distributions of 226 ra 228 ra and 224 ra collected during four cruises representing different conditions on the shelf to construct inventories of radium due to nonconservative additions from sediments using estimates of water residence times we calculate fluxes of these radium isotopes from the amazon system the amount of fresh river sediment entering the system each year is adequate to support the nonconservative flux of 226 ra from the shelf sediments however the ultimate release of 226 ra from the sediments requires weeks to months to support the nonconservative flux of 228 ra from this system sediments of the 1 2 m thick surface mixed layer must be resuspended every two years the resulting flux supports 15 of the 228 ra entering the surface atlantic ocean release of 224 ra from suspended sediments primarily fluid mud is more than adequate to support the inventory of 224 ra on the amazon shelf comparing the amasseds low discharge cruise november 1991 to a low discharge sampling in december 1982 revealed no significant changes in the 226 ra and 228 ra distributions

224ra in continental shelf waters abstract measurements of 224 ra off the coasts of south carolina and georgia reveal that significant activities occur up to 70 km offshore although some of this activity may be transported from estuarine salt marsh and nearshore source regions high near bottom activities in stratified waters suggest that additional 224 ra is being supplied by the decay of 228 th in mid shelf sediments this 228 th is probably derived from the decay of 228 ra in the water column 224 ra is potentially a powerfull tracer of water mixing on the shelf however a good understanding of its input functions is required before this potential may be realized

summary of convective storm initiation and evolution during ihop observational and modeling perspective abstract the data rich international h2o project ihop 2002 experiment is used to study convective storm initiation and subsequent evolution for all days of the experiment initiation episodes were almost evenly divided between those triggered along surface based convergence lines and elevated initiation episodes that showed no associated surface convergence the elevated episodes occurred mostly at night and the surface based episodes occurred during the afternoon and evening surface based initiations were mostly associated with synoptic fronts and gust fronts and less so with drylines and bores elevated initiations were frequently associated with observable convergent or confluent features in the rapid update cycle ruc wind analysis fields between 900 and 600 hpa the ruc10 3 h forecast of the precipitation initiation episodes were correct 44 of the time allowing a tolerance of 250 km in space and for the forecast being early by one period however the accuracy was closely tied to the scale of

radium isotopes and their environmental implications in the changjiang river system abstract radium ra isotopes are widely used to trace water motion and nutrient transport in coastal oceans to enhance our understanding of ra behavior from river to ocean this study examines 226 ra and 228 ra activity concentrations in the water column suspended particulate matter and river bed surface sediments along the middle and lower changjiang river cjr basin based on two cruises in 2006 and 2008 the results show that the ra activity concentrations in the cjr basin are comparable with other rivers in the world higher ra activity concentrations and lower 228 ra 226 ra activity ratios are detected in the tributaries i e in the dongting and poyang lakes than in the mainstream the comparison of pre three gorges dam tgd data taken in 1984 and post tgd data this work illuminates the effect that a major dam has on radium transport within the river and into the estuary we estimate a riverine 226 ra flux of 1 04 0 08 tbq yr 1 extended ra datasets collected in the estuary and the east china sea show that the dissolved and sedimentary ra activity concentrations are higher in the estuary but lower in the sea whereas the particulate ra activity concentrations are larger in the river this finding indicates significant ra desorption from particulate to dissolved phase in the brackish estuary where riverborne materials are filtered and trapped overall these results help to elucidate ra transport from river to ocean and assist further application of ra isotopes in land ocean interaction studies such as submarine groundwater discharge mixing and diffusion processes and determination of water mass and or current structures in the estuarine and coastal zones

precursory activation of seismicity in advance of the kobe 1995 m 7 2 earthquake a succession of precursory changes of seismicity characteristic to earthquakes of magnitude 7 0 7 5 occurred in advance of the kobe 1995 m 7 2 earthquake using the japan meteorological agency jma regional catalog of earthquakes the m8 prediction algorithm keilies borko and kossobokov 1987 recognizes the time of increased probability tip for an earthquake with magnitude 7 0 7 5 from july 1991 through june 1996 the prediction is limited to a circle of 280 km radius centered at 33 5 n 133 75 e the broad area of intermediate term precursory rise of activity encompasses a 175 by 175 km square where the sequence of earthquakes exhibited a specific intermittent behavior the square is outlined as the second approximation reduced area of alarm by the mendocino scenario algorithm msc kossobokov et al 1990 moreover since the m8 alarm starts there were no swarms recorded except the one on 9 26 nov 1994 located at 34 9 n 135 4 e time location and magnitude of the 1995 kobe earthquake fulfill the m8 msc predictions its aftershock zone ruptured the 54 km segment of the fault zone marked by the swarm directly in the corner of the reduced alarm area the kobe 1995 epicenter is less than 50 km from the swarm and it coincides with the epicenter of the m 3 5 foreshock which took place 11 hours in advance

predictability in the epidemic type aftershock sequence model of interacting triggered seismicity 1 as part of an effort to develop a systematic methodology for earthquake forecasting we use a simple model of seismicity on the basis of interacting events which may trigger a cascade of earthquakes known as the epidemic type aftershock sequence model etas the etas model is constructed on a bare unrenormalized omori law the gutenberg richter law and the idea that large events trigger more numerous aftershocks for simplicity we do not use the information on the spatial location of earthquakes and work only in the time domain we demonstrate the essential role played by the cascade of triggered seismicity in controlling the rate of aftershock decay as well as the overall level of seismicity in the presence of a constant external seismicity source we offer an analytical approach to account for the yet unobserved triggered seismicity adapted to the problem of forecasting future seismic rates at varying horizons from the present tests presented on synthetic catalogs validate strongly the importance of taking into account all the cascades of still unobserved triggered events in order to predict correctly the future level of seismicity beyond a few minutes we find a strong predictability if one accepts to predict only a small fraction of the large magnitude targets specifically we find a prediction gain defined as the ratio of the fraction of predicted events over the fraction of time in alarms equal to 21 for a fraction of alarm of 1 a target magnitude m 6 an update time of 0 5 days between two predictions and for realistic parameters of the etas model however the probability gains degrade fast when one attempts to predict a larger fraction of the targets this is because a significant fraction of events remain uncorrelated from past seismicity this delineates the fundamental limits underlying forecasting skills stemming from an intrinsic stochastic component in these interacting triggered seismicity models quantitatively the fundamental limits of predictability found here are only lower bounds of the true values corresponding to the full information on the spatial location of earthquakes

variable cirrus shading during csip iop 5 ii effects on the convective boundary layer a combination of radiosonde wind profiler and aircraft observations together with large eddy modelling show that shading from orphaned cirrus anvils had significant effects on the boundary layer during csip iop 5 the control of boundary layer development by the cirrus shading and the subsidence induced by the cirrus cover led to a boundary layer that at an aircraft altitude of around 500 m was less turbulent 0 8 g kg 1 drier and 0 3 k warmer under thick cirrus than in clear skies in addition at the top of the boundary layer turbulence persisted for some time after the onset of cirrus shading allowing continued entrainment and so stabilization of the previously well mixed boundary layer these effects which would have inhibited convective initiation under the cirrus are consistent with the results of the first part of this study marsham et al 2007 power spectra show that while vertical velocities were dominated by variations on the scale of the boundary layer depth for water vapour mixing ratios and potential temperatures mesoscale variations were comparable or dominant in some cases a spectral gap is observed between these two scales of contributions radiosonde data and modelling show that in addition to the variations in the boundary layer caused by the variable cirrus cover pre existing variations in lid strength and boundary layer moisture were also significant on this day these water vapour variations are also detectable in retrievals of total column water vapour from global positioning systern data copyright c 2007 royal meteorological society

radium and barium in the amazon river system data for sup 226 ra and sup 228 ra in the amazon river system show that the activity of each radium isotope is strongly correlated with barium concentrations two trends are apparent one for rivers which drain shield areas and another for all other rivers these data suggest that there has been extensive fractionation of u th and ba during weathering in the amazon basin the sup 226 ra data fit a flux model for the major ions indicating that sup 226 ra behaves conservatively along the main channel of the amazon river

times of increased probability of strong earthquakes m 7 5 diagnosed by algorithm m8 in japan and adjacent territories this paper continues to explore the possibility of identifying the times of increased probability tips of occurrence of a strong earthquake by premonitory intermediate term seismic activation in lower magnitude range as defined in the algorithm m8 a tip refers to a 5 year period and an area whose linear size is several times larger than that of an incipient earthquake in the course of the global test of the algorithm we applied it retrospectively to the data from the national earthquake information center worldwide earthquake catalog since the regional japan meteorological agency catalog was unavailable to authors related to the segment of circum pacific belt between latitudes 20 n and 48 n from the south of kuril arc to the taiwan and izu bonin arc the worldwide catalog allows us to diagnose tips for earthquakes above magnitude 7 5 from 1975 on five out of six earthquakes with m 7 5 occurred within the tips diagnosed by the algorithm m8 with a priori fixed parameters the missed earthquake occurred at the final stage of formation of the corresponding tip altogether the tips occupy less than 20 and times of expectation occupy about 8 of the total space time domain considered there are also current tips covering about half of the territory application of the additional algorithm of localization named mendocino scenario indicates that the southern part of the japan trench is an area deserving particular attention the results obtained here by no means constitute the definitive earthquake prediction but merely outline the territories for more detailed and comprehensive analysis if confirmed by regional data the results may be used for implementation of some safety measures and evaluation of other precursors including short term ones

a 15 year hail streak climatology for the alpine region in this study we present a unique 15 year hail streak climatology for switzerland based on volumetric radar reflectivity two radar based hail detection products and an automatic thunderstorm tracking algorithm were reprocessed for the extended convective season april september between 2002 and 2016 more than 1 1 million convective cells were automatically tracked over the full radar domain and over 191 000 storms and 31 000 hail streaks in the considered subdomain were selected for analysis following consistency and robustness tests the year to year variability in t h e number of hailstorms reveals two types of convective seasons a a few seasons with hail frequency far above the average and b all other years with an average number of hailstorms a high number of hailstorms in a particular year is not correlated with a higher number of convective storms in general but is related to a greater fraction of severe storms convection initiation hail initiation and hail frequency maxima are located along the southern and northern foothills over the pre alpine area and over th e jura mountains few hail streaks are present over the alpine main ridge hail streak frequency and location is found to be strongly dependent on the synoptic scale weather regimes this is important for monthly and seasonal outlooks as well as for climate modelling analysis of storm life cycles shows that a the majority of hail swaths contain only a single hail streak b severe storms follow a more rapid evolution during their initial stages than do less severe storms and c severe storms produce more spatially extended hail streaks finally significant seasonal and diurnal cycles are present in most of the considered storm characteristics

processes controlling the regional distribution of210pb 226ra and anthropogenic zinc in estuarine sediments the concentration of226ra in bottom sediments in chesapeake bay is lower than in incoming sediments and decreases systematically in the seaward direction reflecting both a seaward increase in sediment grain size and a displacement of ra from sediments as salinity increases the amount of226ra lost from sediments approximately balances that gained by the water in the seaward 150 km of this estuary where atmospheric deposition is the dominant210pbex source the210pbexorg c ratio is virtually constant in surface samples because the production of carbon is apparently regulated so as to be roughly constant per unit area from independent productivity estimates about 10 of the carbon is found to survive remineralization in the estuary long enough to be incorporated into surface sediments zinc is enriched in surface sediments of the northern two thirds of the bay by a factor of 2 3 over shales theznexorg c ratio decreases systematically southward unlike the210pborg c ratio this reflects a regional decline southward in deposition of anthropogenic zn from the atmosphere a negative210pb anomaly is the most distinctive indicator of sediments deposited by a major flood in 1972 and testifies to the importance of such events in estuarine sedimentation

fluxes of 226ra and barium in the pacific ocean the importance of boundary processes abstract the 226 ra ba ratio in particles collected in sediment traps decreases with depth fluxes of ba and al increase with depth these observations cannot be explained by simple vertical processes instead they require a component to the deep flux which originates at the ocean margins we suggest that the deep traps are enriched in ba through the advection of barite originally precipitated in biologically productive regions of the ocean margin this source is less important for 226 ra because some is lost by radioactive decay between the precipitation of barite on the margin and outward transport the boundary flux is an important source of material to the deep sea from 226 ra fluxes in the upper 1000 m of the water column we estimate that the residence time of 226 ra in the upper ocean is 400 years the removal of 226 ra in the particle flux is approximately balanced by the upwelling of waters enriched in 226 ra

tracing the amazon component of surface atlantic water using 228ra salinity and silica high 228ra 226ra activity ratios characteristic of waters in the amazon estuary provide a sensitive indicator of the presence of these waters in the atlantic ocean a conservative mixing model utilizing the 228ra 226ra activity ratio ar tied to absolute measurements in the estuary allows us to estimate that 20 34 of the surface water east of the antilles during june 5 9 from the same area during december and 15 20 of the eastern caribbean surface water during december are derived from the amazon estuary differences in 228ra input occur in response to variable stratification of water near the river mouth during high discharge intense vertical mixing enriches the water in the estuary in 22sra a large fraction of this water moves to the north and east of the antilles where its relatively high 22sra 226ra ar distinguishes it over 1500 km from its source during low discharge northern hemisphere fall a significant fraction of river water passes northwest of the zone of intense mixing into a vertically stratified region where 228ra gain is lower this water is transported by the guiana current along the coast of south america and into the caribbean

mountain volume control on deep convective rain amount during episodes of weak synoptic forcing abstractthermally driven upslope flows in mountainous areas provide favorable conditions for diurnal deep moist convection especially during episodes of weak synoptic forcing the present study inv

distinguishing seawater from geologic brine in saline coastal groundwater using radium 226 an example from the sabkha of the uae article sabkhat salt flats are common geographic featuresof low lyingmarinecoastalareas thatdevelopunder hyper aridclimaticconditions theyare characterizedby thepresenceof highlyconcentratedsalinesolutions and evap oritic minerals and have been cited in the geologic literature as present day representations of hyper arid regional paleohydrogeology paleoclimatology coastal processes and sedimentation in the geologic record it is therefore important that a correct understanding of the origin and development of these features be achieved knowledge of the source of solutes is an important first step in understanding these features historically two theories have been advanced as to the main source of solutes in sabkha brines an early concept entailing seawa ter as the obvious source and a more recent and dynamic theory involving ascending geologic brine forced upward into the base of the sabkha by a regional hydraulic gradient in the underlying formations ra 226 coulduniquely distinguish betweenthese sourcesunder certain circumstances asitistypically present atelevat ed activity of hundreds to thousands of bq m 3 becquerels per cubic meter in subsurface formation brines at exceedingly low activities in open ocean and coastal water and not significantly supplied to water from recently formed marine sedimentary framework material the coastal marine sabkha of the emirate of abu dhabi was used to test this hypothesis the distribution of ra 226 in 70 samples of sabkha brine mean 700 bq m 3 7 sam ples of underlying deeper formation brine mean 3416 bq m 3

ground water geochemistry of 228ra 226ra and 222rn abstract 228ra 226ra and 222rn activities were determined on over 150 ground water samples collected from drilled public water supply wells throughout south carolina a wide range of aquifer lithologies were sampled including the crystalline rocks of the piedmont and sedimentary deposits of the coastal plain a significant linear relationship between log 228ra and log 226ra n 182 r 0 83 was indistinguishable between piedmont and coastal plain ground water median 228 ra 226 ra activity ratios for the piedmont 1 2 and coastal plain 1 3 ground water are close to estimated average crustal 232 th 238 u activity ratios of 1 2 to 1 5 corresponding to th u weight ratios of 3 5 to 4 5 a linear correlation was also found between log 222rn and log 226ra for piedmont n 68 r 0 62 and coastal plain n 89 r 0 64 ground water however the median 222 rn 226 ra activity ratio for piedmont ground water 6100 was much higher than for coastal plain ground water 230 higher excess 222rn activities may be due to greater retention of 226ra by the chemically active piedmont aquifers compared to the more inert sand aquifers sampled in the coastal plain the relationship between log 228ra and log 226ra was used to predict total ra 228 ra 226 ra distributions in appalachian and atlantic and gulf coastal plain ground water predictions estimate that 2 4 of appalachian and 5 3 of atlantic and gulf coastal plain ground water supplies contain total ra activities in excess of the 5 pci l limit established by the u s environmental protection agency these predictions also indicate that 40 50 of these ground water wells may be overlooked using the presently suggested screening activity of 3 0 pci l of 226ra for 228ra analysis

seismicity based earthquake forecasting techniques ten years of progress abstract earthquake fault systems interact over a broad spectrum of spatial and temporal scales and in recent years studies of the regional seismicity in a variety of regions have produced a number of new techniques for seismicity based earthquake forecasting while a wide variety of physical assumptions and statistical approaches are incorporated into the various methodologies they all endeavor to accurately replicate the statistics and properties of both the historic and instrumental seismic records as a result the last ten years have seen significant progress in the field of intermediate and short term seismicity based earthquake forecasting these include general agreement on the need for prospective testing and successful attempts to standardize both evaluation methods and the appropriate null hypotheses here we differentiate the predominant approaches into models based upon techniques for identifying particular physical processes and those that filter or smooth the seismicity comparison of the methods suggests that while smoothed seismicity models provide improved forecast capability over longer time periods higher probability gain over shorter time periods is achieved with methods that integrate statistical techniques with our knowledge of the physical process such as the epidemic type aftershock sequence etas model or those related to changes in the b value for example in general while both classes of seismicity based forecasts are limited by the relatively short time period available for the instrumental catalog significant advances have been made in our understanding of both the limitations and potential of seismicity based earthquake forecasting there is general agreement that both short term forecasting on the order of days to weeks and longer term forecasting over five to ten year periods is within reach this recent progress serves to illuminate both the critical nature of the different temporal scales intrinsic to the earthquake process and the importance of high quality seismic data for the accurate quantification of time dependent earthquake hazard

an observational and modeling study of the processes leading to deep moist convection in complex terrain abstracta case study of orographic convection initiation ci that occurred along the eastern slopes of the vosges mountains in france on 6 august 2007 during the convective and orographically induced precipitation study cops is presented global positioning system gps receivers and two doppler on wheels dow mobile radars sampled the preconvective and storm environments and were respectively used to retrieve three dimensional tomographic water vapor and wind fields these retrieved data were supplemented with temperature moisture and winds from radiosondes from a site in the eastern rhine valley high resolution numerical simulations with the weather research and forecasting wrf model were used to further investigate the physical processes leading to convective precipitation this unique time varying combination of derived water vapor and winds from observations illustrated an increase in low level moisture and convergence between upslope easterlies and downslope westerlies along the eastern slo

boundary layer updrafts driven by airflow over heated terrain abstractthis study presents linear and nonlinear scalings for boundary layer ascent forced by airflow over heated terrain and compares them to results from corresponding high resolution numerical simulations close agreement between theory and simulation is found over most of the parameter space considered including variations in background winds boundary layer stability mountain height and diabatic heating rate as expected the linear and nonlinear scalings perform best for linear and nonlinear flows respectively for a convective boundary layer the scalings accurately predict vertical motion for all flows considered including those that extend well into the nonlinear regime thus these scalings may ultimately help to improve the parameterization of subgrid orographic ascent in large scale models the vertical velocity scalings are less accurate for mechanically blocked flows in stable boundary layers for which a simple vertical displacement scaling is superior although the scalings do not tre

improved tests reveal that the accelerating moment release hypothesis is statistically insignificant 1 we test the hypothesis that accelerating moment release amr is a precursor to large earthquakes using data from california nevada and sumatra spurious cases of amr can arise from data fitting because the time period area and sometimes magnitude range analyzed before each main shock are often optimized to produce the strongest amr signal optimizing the search criteria can identify apparent amr even if no robust signal exists for both 1950 2006 california nevada m 6 5 earthquakes and the 2004 m9 3 sumatra earthquake we can find two contradictory patterns in the pre main shock earthquakes by data fitting amr and decelerating moment release we compare the apparent amr found in the real data to the apparent amr found in four types of synthetic catalogs with no inherent amr when spatiotemporal clustering is included in the simulations similar amr signals are found by data fitting in both the real and synthetic data sets even though the synthetic data sets contain no real amr these tests demonstrate that apparent amr may arise from a combination of data fitting and normal foreshock and aftershock activity in principle data fitting artifacts could be avoided if the free parameters were determined from scaling relationships between the duration and spatial extent of the amr pattern and the magnitude of the earthquake that follows it however we demonstrate that previously proposed scaling relationships are unstable statistical artifacts caused by the use of a minimum magnitude for the earthquake catalog that scales with the main shock magnitude some recent amr studies have used spatial regions based on hypothetical stress loading patterns rather than circles to select the data we show that previous tests were biased and that unbiased tests do not find this change to the method to be an improvement the use of declustered catalogs has also been proposed to eliminate the effect of clustering but we demonstrate that this does not increase the statistical significance of amr given the ease with which data fitting can find desired patterns in seismicity future studies of amr like observations must include complete tests against synthetic catalogs that include spatiotemporal clustering

behavior of 226ra in the mississippi river mixing zone the behavior of 226ra in the mississippi river mixing zone is strongly nonconservative and includes desorption similar to that reported for the hudson pee dee and amazon rivers however dissolved and desorbed 226ra concentrations in the mississippi are 2 to 5 times greater than in the other rivers at the same salinity radium concentrations vary inversely with the water discharge rate the 226ra desorption maximum occurs at a salinity of 5 0 much lower than the 18 to 28 salinity values for the maxima of the other three rivers high concentrations of dissolved 226ra up to 82 dpm per 100 l and the low salinity values for the desorption maximum in the mississippi river result from three major factors suspended sediments include a large fraction of montmorillonite which gives the sediment a high cation exchange capacity 0 54 meq g the average suspended sediment load is large about 510 mg l and contains 1 9 dpm g desorbable 226ra the dissolved 226ra river water end member 9 6 dpm per 100 l is higher than in surface seawater the annual contribution of 226ra to the ocean from the mississippi river is 3 7 1014 dpm yr based on data from three cruises evidence of flux of 226ra from estuarine and shelf sediments is common in vertical profile sampling of the deltaic waters but is not reflected in calculations made with an apparent river water ra value extrapolated to zero salinity

radium 228 in the south atlantic bight radium 228 in surface ocean waters is derived from sedimentary fluxes generated in estuaries salt marshes and fine grained sediments of the inner shelf thus the sup 228 ra activity of shelf waters is a measure of their interaction with these sediments mixing of the sup 228 ra signal offshore follows known circulation patterns and examination of the sup 228 ra field as determined by the sup 228 ra sup 226 ra activity ratio ar reveals details of these patterns during february sinking of chilled shelf waters carries high ar water to depths of 80 130 m just below the shelf break in april upwelling from 500 700 m depth brings low ar water to the shelf break where it replaces the high ar waters present 2 months earlier during august low ar waters at the shelf break could be traced to the surface where they separated higher ar waters both inshore and offshore of the shelf break because of such short term variability one dimensional steady state models which balance sup 228 ra decay with mixing do not provide a true measure of horizontal mixing rates fluxes necessary to support the sup 228 ra standing crop in the south atlantic bight are of the order of 2 5 x 10 sup 14 dpm yr thesemore are similar to estimates from the new york bight but 25 times lower than the apparent flux from the amazon system copyrightamerican geophysical union 1987 less

determining groundwater ra end member values for the estimation of the magnitude of submarine groundwater discharge using ra isotope tracers radium isotopes 228ra and 226ra are excellent tracers of submarine groundwater discharge sgd to estimate sgd magnitudes information on the end member values of ra concentrations in groundwater is critical however the distribution characteristics of ra in coastal aquifers are poorly understood in this study we show that ra concentrations in coastal groundwater are primarily dependent on salinity based on the data n 500 obtained from global coastal aquifers although previous end member calculations averaged all ra concentrations without considering salinity if we assume that sgd is composed mainly of seawater infiltrating the aquifer previous estimates of sgd for the atlantic ocean and the global ocean were overestimated twofold to threefold this may be similar for other applications using different ra isotopes our study highlights that the end members of ra isotopes in groundwater should be carefully considered when estimating sgd using ra isotope mass balances in the ocean

times of increased probability of earthquakes of ml 5 5 in greece diagnosed by algorithm m8 an attempt is made to explore the possibility of identifying the times of increased probability tips of occurrence of earthquakes with ml 5 5 by premonitory intermediate term seismic activation in lower magnitude ranges as defined in the algorithm m8 a tip refers to a 5 year period and an area whose length is several times greater than that of an incipient earthquake this algorithm has been already tested retrospectively for the strongest earthquakes of magnitude greater than or equal to 7 0 which have occurred in greece since 1973 in the present study the same algorithm is also applied retrospectively by considering smaller earthquakes of local magnitude ml greater than or equal to 5 5 the obtained results show that ten out of eleven events with m 5 5 which took place in greece and surrounding region from january 1 1977 till december 31 1990 occurred within the tips diagnosed by the algorithm m8 retrospectively only the thessaloniki earthquake of june 20 1978 did not occur within tip the m8 algorithm failed in four cases namely those that occurred in regions for which our catalogue was not complete altogether the tips occupy less than 25 and times expectation about 8 of the total space time considered there is also a current tip started at the end of 1986 or at the beginning of 1987 for the south southwestern part of thehellenic arc indicating that this area deserves particular attention if the algorithm m8 works reliably then this tip will be filled by the end of 1992 this result by no means constitute the definitive earthquake prediction but merely outline a territory for more detailed and comprehensive analysis

plausibility of long distance electrotelluric precursors to earthquakes a systematic analysis of the plausibility of different classes of models which could account for low frequency precursory electrotelluric signals observable at large distances from a large earthquake is carried out first we consider linear models for which either a stationary electrical field is generated by a current dipole in the source volume or a static deformation field results from a precursory strain in the source volume linearly inducing a streaming potential effect near the electrode in the former case only the conjunction of very favorable circumstances may lead to an electrical field larger than 10 mv km at more than 100 km with the constraint that no anomaly exceeds a few volts per kilometer in the source area it indeed requires a powerful electrical dipole current 104 a length 1 km which might be produced by a streaming potential effect associated with the connection of nonhydrostatic fluid reservoirs pore pressure difference up to 100 mpa a two dimensional channeling of the electrical currents from the source to the electrode area which would result from high conductivity horizontal layers and finally a local amplification factor of typically 100 near the electrodes which might be produced by a narrowing of the conductive channel for an elastic long distance interaction an electric field of 10 mv km at a distance 10 times the source length 100 km away from a m 6 earthquake requires a precursory deformation larger than the coseismic deformation if no strong local amplification is considered alternatively nonlinear models are proposed and discussed assuming that the crust is stuffed with small scale local instabilities fractures and nonhydrostatic fluid reservoirs among which a number are close to their instability threshold these instabilities may follow their own evolutionary process inducing sporadic fluid flow and hence streaming potential effect in the vicinity of the electrodes without any relation to a remote tectonic activity however these instabilities may be sensitive to very small changes in the stress field and hence be triggered by the elastic precursory deformation of a remote seismic source this requires that the precursory deformation near the instability is at least larger than the tidal strain 10 7 this necessary condition is met at a distance of up to 10 times the source dimension when the precursory strain source is only 10 of the coseismic deformation provided that the strain source is double the size of the seismic fault itself this model could account for the absence of self potential anomalies related to the earthquake itself as a large proportion of the available instabilities could have been swept away by the precursory strain furthermore with such a model a precursory strain in the source area could induce a detectable change in the background seismic activity over a vast area which may give a new interpretation of the times of increased probability observations for short distances the triggering of fluid instabilities by strain perturbation and the associated streaming potential effect may well be a promising model for explaining low frequency electric and magnetic precursors

times of increased probability of large earthquakes ms 7 5 along the mexican subduction zone abstract using the method of pattern recognition of infrequent events we explore the possibility of identifying the times of increased probability tip of occurrence of large earthquakes ms 7 5 along the mexican subduction zone a tip refers to a 5 year period within which a strong earthquake has a high probability of occurrence we analyzed the seismicity for the regions of chiapas eastern oaxaca 91 97 w region 1 western oaxaca guerrero 97 102 w region 2 and michoacan colima jalisco 102 106 w region 3 for the time interval 1970 1991 with the national oceanic and atmospheric administration seismic catalog as the source data the premonitory intermediate term seismic activation to identify a tip was measured using the algorithm m8 three out of the five earthquakes of ms 7 5 that occurred during the studied period are diagnosed by algorithm m8 and for the region 3 segment a tip is identified that will end between 1994 and 1996 we consider the area between the western colima gap and the jalisco region 103 7 106 0 w as the zone where the forecast earthquake has a higher than usual probability of occurrence our results by no means constitute a definitive earthquake prediction but suggest the need for detailed seismic analysis and the study of other geophysical precursors along the colima jalisco segment

an optimization of using the m8 algorithm for prediction of major m7 0 earthquakes in the iranian plateau the casualties and financial losses caused by large earthquakes have led to an awareness of prediction importance of such earthquakes the earthquake prediction is divided into four categories long term intermediate term short term and immediate the m8 algorithm is one of the intermediate term middle range prediction algorithms primarily used to predict earthquake of magnitude 8 or more and is applied later for smaller magnitudes the iranian plateau is less exposed to earthquake with magnitude 8 or more and it is observed that the seismicity rate in this region is generally low thus the original m8 is not suitable for applying in this region the objective of this study is to modify the m8 algorithm for prediction of major m7 0 earthquakes in the iranian plateau the major earthquake of magnitude 7 or more in the iranian plateau from 1975 to 2018 is considered as the target earthquakes the hit rate times 1 minus alarm rate is defined as objective function and the particles swarm optimization meta heuristic algorithm is used to maximize it the optimum m8 could predict 14 out of 17 large earthquakes in the iranian plateau while occupying 31 7 of the spatio temporal space as the alarm the results show that by employing an optimization algorithm we can modify the m8 algorithm for efficient prediction of the target magnitudes less than 8 in the regions with low seismicity rate

testing an earthquake prediction algorithm the 2016 new zealand and chile earthquakes the 13 november 2016 m7 8 54 km nne of amberley new zealand and the 25 december 2016 m7 6 42 km sw of puerto quellon chile earthquakes happened outside the area of the on going real time global testing of the intermediate term middle range earthquake prediction algorithm m8 accepted in 1992 for the m7 5 range naturally over the past two decades the level of registration of earthquakes worldwide has grown significantly and by now is sufficient for diagnosis of times of increased probability tips by the m8 algorithm on the entire territory of new zealand and southern chile as far as below 40 s the mid 2016 update of the m8 predictions determines tips in the additional circles of investigation cis where the two earthquakes have happened thus after 50 semiannual updates in the real time prediction mode we 1 confirm statistically approved high confidence of the m8 msc predictions and 2 conclude a possibility of expanding the territory of the global test of the algorithms m8 and msc in an apparently necessary revision of the 1992 settings