surface track discontinuity of tropical cyclones crossing taiwan a statistical study surface tracks of some cross taiwan tropical cyclones were discontinuous as a result of the blockage of the north northeast south southwest oriented central mountain range cmr this paper tries to identify the variables that may be used to diagnose track continuity in advance the track records of 131 westbound crosstaiwan tropical cyclones between 1897 and 2009 are examined it is found that the track continuity of awestboundcross taiwantropicalcyclonedependsmostlyuponthelandfalllocation ylf theapproaching direction ang and the maximum wind vmx of the cyclone according to the empirical probability of track continuity estimated from the data the dependence on ylf which is nonlinear and remarkably asymmetric with respect to the midpoint of the east coast may be well approximated by a quadratic function of ylf the nonlinearity and asymmetry can be interpreted in terms of the length scale of the cmr and the north south antisymmetry of the cyclonic flow the estimated dependence of track continuity on cyclone intensity and size may be approximated by a linear function of vmx the estimated dependence of track continuity on ang may be approximated by a single term of the modified variable dir 5jang 2 110j where 110 is the direction in degrees perpendicular to the cmr s long axis usingthe64tracksbetween1944and1996asthetrainingsample alogisticregressionequationmodel built in terms of ylf ylf square dir and vmx gives an overall accuracy score of 89 as to the probability estimates of individual tracks 49 of the 64 tracks have estimated probabilities outside the 0 5 2 0 127 0 5 1 0 127 rms error range and are correctly classified a prediction test using another set of 67 tracks not included in the model training sample scores a success rate of 82 as to the probability predictions for individual tracks 49 of the 67 tracks have predicted probabilities outside the rms error range and are correctly predicted these results confirm the appropriateness of the model and moreover demonstrate that the three parameters ylf dir and vmx primarily control the surface track continuity of a westbound tropical cyclone crossing taiwan

the inland eyewall reintensification of typhoon fanapi 2010 documented from an observational perspective using multiple doppler radar and surface measurements abstractthis study documents observational changes in the eyewall of typhoon fanapi 2010 after landfall in taiwan the observations indicate that fanapi s eye and eyewall disappeared on the eastern side of taiwan s central mountain range cmr after landfall but reemerged on the western side of cmr the cyclonic circulation increasing wind speed a low level low pressure and high temperature zone the associated updrafts and downdrafts and surface pressure and rainfall measurements all support the existence of a reintensified eyewall the storm slowed down during the redeveloping stage thus prolonging the rainfall duration over taiwan on the western side of cmr a northwest southeast oriented rainband formed at an earlier stage possibly due to the large scale interaction between fanapi s remnant flow and the environment however the subsequent reintensification might be attributed to the interaction between the circulation and topography this is supported by the finding that adjacent to cmr stron

idealized simulations of the effect of local and remote topographies on tropical cyclone tracks this is the second part of a study on the effect of topography on tropical cyclone tc tracks in part i idealized simulations using the weather research and forecast wrf model were conducted with artificial tcs inserted at a location such that they make landfall on the central part of taiwan and the luzon in this second part the effects of local and remote topographies are studied by examining the tracks of several tcs approaching taiwan at different latitudes tropical cyclones approaching to the south of taiwan remote effect slow down and are first deflected southwestward and then northward moreover a sharp northward deflection occurs for a tc passing further south of taiwan but the deflection is small for a tc passing further north of taiwan in the presence of china s terrain an additional larger but weaker anticyclonic gyre is induced so that the tc is affected even when it is further away from the land the flow associated with this gyre reduces the northward deflection caused by the taiwan terrain but enhances the southwestward shift of the tc however no cyclonic gyre is found over inland china if the tc is far away from china s coast probably because of the irregular elevated topography for tcs making landfall on south china a westward shift is found just prior to landfall which is more significant if the height of china s terrain is doubled this westward shift can be explained by the horizontal advection vertical advection and diabatic heating terms in the potential vorticity tendency equation

distribution and genesis of soils of the northeastern united states abstract the soils of the northeastern united states central and northern appalachians north of the glacial border are spodosols inceptisols alfisols and some entisols and histosols these soils are relatively young 12 18 ka climate frigid soil temperatures parent material acidic sandy and vegetation conifers are the major soil forming factors affecting the genesis of the spodosols while parent material calcareous material is a determining factor affecting the genesis of the alfisols the inceptisols of southern new england are slightly different better developed cambic horizon than those of the appalachian plateau the genesis of the alfisols of the unglaciated appalachian plateau and triassic lowlands are also significantly influenced by carbonates and basic minerals in their parent material ultisols are found only south of the glacial border ultisols on the appalachian plateau and in the northern ridge and valley are young soils and should be identified as parent material ultisols while those of the southern ridge and valley piedmont and coastal plain show significant soil development and should be identified as genetic ultisols the soils south of the glacial border on steep slopes have been affected significantly by erosion during the cold cycles of the pleistocene while soils on gentle slopes have been affected to a lesser degree much of the material eroded during the late pleistocene has accumulated on lower sideslopes as colluvium the erosional and depositional processes have resulted in a complex mosaic of moderate to well developed soils on the more stable landscape surfaces and moderate to weakly developed soils on the erosional and depositional surfaces

relative age dating of transported regolith and application to study of landform evolution in the appalachians abstract surficial deposits in the appalachians generally are thin discontinuous and difficult to date in the absence of numerical dates particularly for older deposits relative age indices based on degree of weathering and soil development have been used to distinguish and correlate deposits of different ages a favorite locale of relative age studies has been stream terraces where chronosequences have been developed to shed light on the relationship between time and weathering soil development the lack of applicable numerical dating techniques has led some researchers to establish relative chronosequences in which height of stream or fan terraces above modern river level arl serves as a proxy for time approximate incision rates can then be used to estimate numerical ages of the deposits relative age correlations between the weathering indices on the terraces and comparable indices on dated deposits on the coastal plain and in nearby glaciated regions suggest that ages so estimated are the right order of magnitude relative age indices show correlations with height arl that are as high as those with time perhaps because more data sets are available for relative chronosequences than for true chronosequences analogous relative age sequences can be established for alluvial fans and even for hillslope colluvium many weathering indices have been employed but weathering rind thickness on mafic to intermediate clasts has proved to be a particularly consistent and useful parameter in addition to showing how weathering and soil development progress over time relative age dating has shed light on the manner in which landforms evolve along some rivers for example the areal extent of old highly weathered alluvium far exceeds that of younger alluvium suggesting that formerly floodplains and low terraces were much more extensive than at present in addition the manner in which weathering indices on some river terrace sequences vary with height arl suggests that incision rate has changed through time relative age mapping of alluvial fans produces a map pattern of older and younger fan surfaces that allows the sequence of fan development to be inferred in one case suggesting a scenario different from those previously described for fans mapping also shows that the relative abundance of young intermediate and old fan surfaces varies greatly from one area to another several studies have demonstrated clustering of relative age values into a small number of groups suggesting temporal grouping and thus episodic deposition on fans regression of weathering rind thickness against height above modern drainageways of remnant fan surfaces in two areas suggests that fans are being incised more rapidly in one area than in another relative age of hillslope colluvium also aids geomorphic interpretation young brown colluvium is much more common than old red colluvium near the glacier border where red colluvium rarely occurs at the surface but typically is covered by brown colluvium probably mobilized during the late pleistocene distant from the ice margin however red colluvium is extensively exposed on interfluves relatively stable hillslopes can also be distinguished from active ones in this manner for example colluvium on hillslope noses is somewhat more weathered than that on hollow floors and sideslopes

late pleistocene relic ultisols and alfisols in an alluvial fan complex in coastal tuscany detailed stratigraphic sedimentary facies and palaeosol analyses were performed on an outcrop on late quaternary deposits in the coastal area of tuscany the outcrop was selected as representative of one of the major quaternary alluvial fan complexes of central italy the ancient cecina river fan and as showing contrasting if related palaeosols the oldest relic palaeosol was identified as an ultisol representative of the most developed soil type normally found as relic soil in italy and about whose possible ages only approximate interpretations presently exist osl dating set the whole succession of sediments palaeosols and geomorphic surfaces into a firm chronological setting as a result evolution of the cecina fan complex in late pleistocene could be fully reconstructed assessment of the age of the relic ultisol produced results contrasting with current interpretations showing how such a soil type can have developed in italian conditions in a relatively short time i e since about mis 5d

archean gold mineralization in the wabigoon subprovince a product of crustal accretion evidence from u pb geochronology in the lake of the woods area superior province canada within the lake of the woods greenstone terrain in the wabigoon subprovince of northwest ontario gold is in faults shears and tension veins that developed in response to a late archean northwest directed contraction and emplacement of contemporaneous plutons nine rocks in this area have been dated using u pb analyses of zircon in order to obtain precise time constraints on gold mineralization and to compare its timing with the age of major crustal events in the region a mineralized dike at the duport mine shoal lake is 2716 pm 2 ma old whereas a later dike that cuts mineralized rocks has an age of 2709 pm 2 ma gold mineralization is therefore distinctly younger than calc alkaline and tholeiitic rocks dated at 2724 pm 2 ma in the shoal lake area and 2727 pm 2 ma in the high lake area to the north hydrothermal activity associated with mineralization at the duport mine overprints the amphibolite facies contact metamorphic aureole of the snowshoe bay batholith 2708 pm 7 ma

u pb zircon ages from the eastern savant lake crow lake metavolcanic metasedimentary belt northwest ontario five rocks from three areas in the eastern part of the savant lake crow lake metavolcanic metasedimentary belt have been dated by u pb analysis of zircons the sioux lookout area is composed of a sequence of generally fault bounded metavolcanic and metasedirnentary belts the age of a felsic tuff in the central volcanic belt is 2732 72 ma this is possibly the youngest sequence in the area the savant lake volcanic belt comprises the jutten volcanic unit at its base separated by an angular unconforrnity from the handy lake volcanic sequence the age of a dacitic tuff near the base of the handy lake volcanic sequence is 2745 22 i ma the south sturgeon lake volcanic belt is composed of four volcanic cycles the age of a felsic tuff from the top of the uppermost cycle is 2717 92 ma the felsic beidelman bay pluton and the mafic pike lake pluton which both intruded the lower art of the sequence give ages of 2733 82 and 2732 721 a respectively this establishes a minimum time span of 15 921 ma for deposition of the sequence this interval along with the 27 ma span between the ages of the handy lake sample and the volcanic sample from the south sturgeon lake area suggests that the sequences were laid down by a series of discrete volcanic episodes for samples subjected to multistage lead loss the reliability of ages has been greatly enhanced by air abrasion of zircons several cases of suspected biasing of analyses by the air abrasion process have been encountered it appears that this biasing problem can be overcome by selection and abrasion of low uranium grains that are free of imperfections

relative age relationships of debris flow deposits in the southern blue ridge north carolina abstract periods of increased landscape instability in the southern blue ridge were assessed with relative ages of three sequences of debris flow deposits the sequences consist of a series of lobate deposits that are expressed as step like landforms on the floors of host valleys data were collected at three sites from soil pits on the toe and apex of debris flow deposits relative ages were obtained by qualitatively and statistically examining data on clast weathering soil color clay content and iron species consistent results among the indicators of relative age demonstrate that they have utility in warm to temperate humid environments at each site the topographically highest debris flow deposits are slightly older than those at lower elevations one deposit at each of the three sites has a relative age that is very similar to that of one deposit at the other sites this similarity in age indicates that an external factor such as extreme precipitation accounts for the formation of debris flows at approximately the same time in the geological past one of the sites however also has deposits that are clearly younger than the deposits at the other sites which indicates that intrinsic factors also affect the formation of debris flows in the region

basement terrane correlations and crustal recycling in the western superior province nd isotopic character of granitoid and felsic volcanic rocks in the wabigoon subprovince n ontario canada abstract the western superior province represents a collage of mesoarchean continental 3 2 2 8 ga and neoarchean continental arc and oceanic 2 8 2 66 ga crustal fragments nd isotope data presented here for 89 felsic volcanic and plutonic rocks have been combined with compiled data to generate a data set of over 240 analyses from the wabigoon and winnipeg river subprovinces these samples from both oceanic and continental environments have been used as crustal probes their nd isotopic character used to investigate the extent of basement terranes the ancestry of crustal fragments their interaction with each other and the degree of sialic crustal reworking the wabigoon and winnipeg river subprovinces include three isotopically distinct terranes 1 the winnipeg river terrane comprises the winnipeg river subprovince the north central wabigoon and the north eastern wabigoon subprovince this region is dominated by neoarchean granitoid rocks with mesoarchean vestiges of previous workers have suggested that the boundary between the western wabigoon and winnipeg river terranes represents a cryptic suture resulting from a collision at circa 2 71 ga the boundary between the western wabigoon and marmion terranes although obscured by late intrusions may be a continuation of this suture zone the boundary between the winnipeg river and marmion terranes in the central wabigoon is also cryptic isotopic data suggest that the marmion terrane is allochthonous with respect to the winnipeg river terrane common magmatism in these two terranes at 2 93 2 87 ga suggests that they may have collided during this time in the eastern wabigoon subprovince this collision zone is speculated to occur at the humboldt bay high strain zone a complex history of crustal recycling throughout the mesoarchean and neoarchean is revealed which demonstrates the importance of autochthonous development of granite greenstone terranes in a continental environment the data also support models of tectonic accretion during the archean indicated by the presence of granite greenstone terranes of allochthonous origin

idealized simulations of the effect of taiwan and philippines topographies on tropical cyclone tracks the effects of topography on tropical cyclone tc tracks are investigated using the weather research and forecasting model running on a beta plane with actual topography two sets of experiments are performed one focusing on taiwan topography and the other on the philippines in each set different parts of the terrain are set to be either present or absent and the tcs are inserted at a location southeast of the mountain so that landfall occurs at the central part of the mountain in the no terrain control cases relative to the control case a pair of terrain induced gyres is found in all with terrain experiments this pair of gyres rotates cyclonically around the tc and the gyre associated flow near the tc centre causes a northward deflection of the tc track prior to landfall an examination of the potential vorticity tendencies pvts suggests that in addition to the pvt produced by this flow the pvt from diabatic heating cannot be ignored in explaining the tc track during landfall the asymmetric diabatic heating is significant which tends to retard the fast displacement of the tc caused by horizontal advection this diabatic heating distribution results from three different mechanisms an incursion of dry air from the mountain low level convergence induced by the terrain altered wind field in the southwestern part of the tc and the development of convergence cyclonically inward from the eastern side of the mountain to the tc core however the first two mechanisms are apparently missing in the philippine experiments because of the lower height and the moister air over the mountains on luzon island

an observational study of a coastal barrier jet induced by a landfalling typhoon abstractin this study the structure and evolution of a coastal barrier jet cbj along the east coast of taiwan is documented using operational doppler radars the formation of the cbj was control

analytical and numerical studies of the beta effect in tropical cyclone motion part i zero mean flow abstract the effect on tropical cyclone motion is studied using an analytical as well as a numerical model in a nondivergent barotropic framework the analytical model and the linear version of the numerical model give essentially the same result the linear effect causes a westward stretching of the model vortex but no significant movement of the vortex center an east west asymmetry in the meridional wind field is also created it is the inclusion of the nonlinear term that produces the northwestward movement of the vortex previously found by other investigators e g kitade 1981 this northwestward movement increases with both the maximum wind speed and the radius of maximum wind in a constant shape vortex a wind maximum is also found to the northeast of the vortex which appears to be consistent with the observational findings of shea and gray this asymmetry plays an important role in the vortex motion

soil geomorphic research a selective overview abstract much soil geomorphologic research involves tracking the development of soils with time otherwise known as soil chronosequences most of these have been undertaken on landforms underlain by quaternary depsits of varying ages in general there is a predictable variation in both soil horizon sequence and amounts of constituents such as clay fe and caco 3 with time the rate at which these constituents accumulate in the soil is a function of parent material bioclimate and atmospheric dust influx and because of the latter soils in aridic regions can form at rapid rates profile properties can be used to estimate the ages of deposits and faulting events but the error on the estimated age can be 50 or greater the position of salt accumulations in soil profiles is one of the best indications of climatic change and these can be modelled to compare with various climatic parameters present and past profile characteristics due to pedogenic thresholds however can mimic those due to climatic change so close dating is necessary to differentiate the effects of both soil geomorphic data are essential to understand the origin of ancient paleosols in the sedimentary rock records but a major problem still is one of recognition of these features as soils and to separate the effects of pedogenesis from those of diagenesis

structure of precipitating systems over taiwan s complex terrain during typhoon morakot 2009 as revealed by weather radar and rain gauge observations summary this study documents from an observational perspective the structure of precipitation systems over the complex topography of taiwan as typhoon morakot 2009 impinged on the island on 8 august 2009 an advanced multiple doppler radar synthesis technique particularly designed for dealing with non flat surfaces is applied to analyze the three dimensional wind fields over the ocean and terrain in the northern and southern portion of the analysis domain where the mountain slope is relatively gentle and steep respectively the radar reflectivity measurements indicate that the precipitation systems exhibit very distinct features namely horizontal translation in the north and abrupt intensification in the south while still far from the southern mountainous region a north south oscillation of an east west oriented band of strong radar reflectivity 40 dbz with a horizontal span of 20 km is observed along the mountain slopes the band of strong radar reflectivity has a much wider north south extent both the radar and rain gauge observations show that the major precipitation is primarily confined to the windward side of the mountains an analysis of the saturated brunt vaisala frequency reveals that the upstream atmosphere is statically unstable which implies that the lifting of the incoming convective cells by the topography will easily trigger precipitation thus most of the moisture will be consumed before the air reaches the leeward side of the mountains the long duration and the wide range of heavy precipitation in the mountainous regions resulted in a record breaking average over the gauges rainfall amount of 2000 mm over 4 days the prevailing winds approaching the mountains are from the west the cross barrier wind speed has a maximum 40 m s 1 above the mountain crest that can be reasonably explained by a simplified shallow water model the capability of applying the weather radar to provide a reliable quantitative estimate of the rainfall over a large area with high temporal and spatial resolution is demonstrated using dual polarimetric radar data the potential applications of the knowledge of the wind and precipitation characteristics in hydrology and other fields are addressed in this manuscript

sensitivity of typhoon track to asymmetric latent heating rainfall induced by taiwan topography a numerical study of typhoon fanapi 2010 1 typhoon fanapi 2010 traveled westward across the central mountain range of taiwan on 19 september and its rainfall shifted from a symmetric to an asymmetric pattern with convection mostly to the south and southeast meanwhile the storm slowed down from 22 to 14 km h 1 for 12 h upon leaving taiwan and led to heavy rainfall 800 mm and serious flooding over the low lying southwestern plains through simulation and sensitivity tests using the cloud resolving storm simulator at 3 km grid size this study shows that the sudden and temporary speed reduction was caused by the asymmetric latent heating lh not the environmental flow specifically over a 9 h period the model storm moved westward at 16 km h 1 in the control run but increasingly faster and more toward the northwest when the moisture and thus the lh effect and its asymmetry is gradually reduced steering flow analysis and estimation using model results suggest an eastward motion vector of about 8 km h 1 consistent with the observation is produced by the asymmetric lh effect when the effects from the vertical wind shear and beta drift are both taken into account this result is further supported by the diagnosis on storm motion based on potential vorticity tendency although important such feedback to typhoon track from rainfall asymmetry that is induced by the blocking effect of topography have not been reported or studied

orographic influence on basic flow and cyclone circulation and their impacts on track deflection of an idealized tropical cyclone abstracta series of idealized numerical experiments and vorticity budget analyses is performed to examine several mechanisms proposed in previous studies to help understand the orographic influence on track deflection over a mesoscale mountain range when an idealized tropical cyclone tc is embedded in a uniform easterly flow and passes over a mountain with a moderate froude number it is deflected to the south upstream moves over the mountain anticyclonically and then resumes its westward movement the vorticity budget analysis indicates that the tc movement can be predicted by the maximum vorticity tendency vt the orographic effects on the above tc track deflection are explained by the following 1 upstream of the mountain the easterly basic flow is decelerated as a result of orographic blocking that causes the flow to become subgeostrophic which advects the tc to the southwest analogous to the advection of a point vortex embedded in a flow the vt is primarily dominated by the horizontal vo

spodosol alfisol intergrades bisequal soils in ne michigan usa abstract twenty three well drained boralfs most of which exhibit bisequal soil morphology were described and sampled in ne lower michigan where they occur on landscapes shaped by greatlakean ice ca 12 ka bisequal soils in michigan are intergrades between orthods and udalfs with a spodic like upper sequum a e bs overlying a sequence of e bt c horizons thus they frequently occupy a pedogenic ecotone the purpose of the study was to characterize these soils which have been little studied and to determine if parent material homogeneity and texture are correlated with various aspects of their morphology the soils have formed in coarse loamy and fine loamy materials often with a distinct lithologic discontinuity between the two sequa the lower material interpreted as glacial till is strongly calcareous and slightly coarser textured with considerably more dolomitic gravel than the upper material water flowing through the material above may hang at the discontinuity and deposit illuvial clay bt horizons are found at or immediately below the discontinuity statistical correlations indicate that bisequal sola and their eluvial horizons are thicker when developed in coarser textured materials finer textured pedons contain more extractable fe and al in the spodic sequum but have thinner eluvial zones which have not been as completely stripped of metal cations in the finest textured pedons the e horizon may be completely lacking

a soil chronosequence study of the reno valley italy insights into the relative role of climate versus anthropogenic forcing on hillslope processes during the mid holocene abstract relatively few soil chronosequences with good age control exist for late pleistocene and holocene deposits in the mediterranean region of europe yet surface soils and their young buried counterparts can provide meaningful information about the timing and processes of landscape response to external forcing such as climate or anthropogenic change here we present the results of a study that examines a well dated chronosequence of nineteen soil exposures in surficial deposits ranging in age from hundreds of years to hundreds of thousands of years located in the reno river valley near bologna italy the soil forming climate of the reno valley sits on a threshold between that which facilitates the accumulation of caco 3 and that which facilitates the translocation and formation of clay minerals and iron oxides once formed secondary iron oxides are relatively immobile in oxidizing conditions in the soil profile and therefore consistently record age trends with feo fed ratios decreasing predictably with soil age for all soils in the chronosequence the morphology of secondary carbonate accumulation and its depth of leaching also vary predictably with soil age but only for soils younger than about 12 000 years in these young soils horizons that contain secondary carbonate progress from relatively shallow stage i bk horizons in late holocene aged soils to deeper stage iii bk horizons in latest pleistocene aged soils in soils older than approximately 12 000 cal ybp however carbonate dissolution during wetter climates and the addition of colluvium and or dust to terrace surfaces become important factors in the preservation of carbonate in the profile and carbonate content is not predictable by age alone without significant depositional additions these older soils become decalcified pedogenic carbonate precipitated during drier climates is susceptible to dissolution during wetter periods as evidenced by discontinuous carbonate coatings on grains in some soils therefore overall measurable pedogenic carbonate content is spatially and temporally variable as a function of input of fresh carbonate and locally controlled soil moisture conditions particle size does not decrease predictably with soil age for reno valley soils and appears to be strongly influenced by parent material variability in younger soils and by dust additions in older soils our detailed examination of soil stratigraphy in the reno valley revealed evidence of significant aggradation of colluvium and tributary fans in the middle holocene between 6000 and 4000 ybp this aggradation pre dates bronze age agricultural expansion and appears to be instead attributable to the climate conditions of the middle holocene that have been documented elsewhere in italy for this time period this study demonstrates that late pleistocene and holocene surface soils in the mediterranean region of europe can effectively help elucidate rates and processes of landscape evolution

a numerical study of the effect of island terrain on tropical cyclones abstract a triply nested movable mesh model was used to study the behavior of tropical cyclones encountering island mountain ranges the integration domain consisted of a 37 wide and 45 long channel with an innermost mesh resolution of 1 6 the storms used for this study were embedded in easterly flows of 5 and 10 m s 1 initially realistic distributions of island topography at 1 6 resolution were inserted into the model domain for the region of the caribbean including the islands of cuba hispaniola and puerto rico the island of taiwan and the region of luzon in the northern philippines it was found that the islands affected the basic flow as well as the wind field directly associated with the storm system the combination of these effects caused changes in the track and translational speed of the storm in particular in the case of the 5 m s 1 easterly flow the storm accelerated and veered to the north well before reaching taiwan for the other island distributions the northward deflecti

crustal evolution of archean rocks in the kakagi lake area wabigoon subprovince ontario as interpreted from high precision u pb geochronology the evolution of the archean volcanic plutonic complex in the kakagi lake area occurred during a time interval of ca 32 ma the earliest age is from analysis of zircon and baddeleyite in a gabbro intruding the lowermost katimiagamak volcanic group an age of 2723 2 1 8 ma on a tonalite gneiss from the interior of the underlying sabaskong batholith is indistinguishable from a previously dated massive border phase of the batholith and shows no evidence for inheritance from an older sialic component an early tonalite phase from the adjacent aulneau batholith is dated at and the latest granodiorite phase is dated at this defines a time span of about 7 ma for intrusion of the bulk of the batholith and indicates that previously dated felsic volcanism from the uppermost sequence above the kakagi lake volcanic group is coeval with late plutonic activity in the aulneau batholith the end of regional deformation in the area is given by the ages of two late tectonic intrusions the heronry lake pluton and

sedimentary and structural evidence for 2 7 ga continental arc oceanic arc collision in the savant sturgeon greenstone belt western superior province canada the western superior province sustained rapid crustal growth in the interval 2 72 2 68 ga through amalgamation of microcontinental crustal blocks and juvenile oceanic terranes recent field isotopic and geophysical surveys provide insight on the nature timing and scale of this accretionary growth however few places offer the rich tectono stratigraphic and structural detail with which to establish accretion of oceanic and continental blocks as does the savant sturgeon area here 3 4 2 8 ga continental crust of the winnipeg river terrane is juxtaposed with 2 775 2 718 ga juvenile oceanic rocks of the western wabigoon terrane across a 2 85 2 75 ga southwest facing continental margin sequence the continental margin was reactivated at 2 715 ga with the establishment of an arc recorded by 2 715 2 70 ga tonalite and associated intermediate volcanic rocks this magmatic activity is interpreted to reflect north and east dipping subduction that led to consumption of a small tract of oceanic crust betwe

on typhoon track deflections near the east coast of taiwan abstracttyphoons with deflection tracks dts within a 200 km distance of the mountainous island of taiwan are examined we analyze 84 landfalling typhoons that compose 49 dt cases turning to the left hand side including 18 with very large deflection angles da 20 and another 7 having looped tracks lts most of the large da and lt cases are northern landfall type reaching taiwan s east coast poleward of 24 n and originally possessing relatively slow translation speeds 4 m s 1 their average translation speeds however increase by 50 in the 3 h prior to landfall the wrf model is used to simulate dt cases and potential vorticity pv tendency diagnosis is used to interpret the contributions of the horizontal advection ha vertical advection va and diabatic heating dh terms the northern landfall tropical cyclones tcs possess significant cross mountain flow to the south of the storm near the coast resulting in vorticity stretching the va effect and subsidence warming the subsi

geochronology of the belmont lake metavolcanic complex and implications for crustal development in the central metasedimentary belt grenville province ontario u pb analyses of zircon and titanite were carried out on eight rocks from the belmont lake metavolcanic complex a volcano sedimentary sequence in the central metasedimentary belt of the grenville province of southeastern ontario the ages of concordant supracrustal rocks within the complex do not accord with stratigraphic position the youngest volcanic age is from a rhyolite near the base of the sequence the oldest age is from a dacite in the middle this is overlain by a rhyolite in age a rhyolite at the top of the sequence appears to contain zircon inherited from a source about 1870 ma old the complex is therefore interpreted as comprising a lithotectonic sequence composed of structurally interleaved segments of contrasting age tectonic emplacement of these segments was most likely along previously unrecognized thrust faults the supracrustal rocks were subjected to at least two major deformational events as well as a late metamorphism the earliest event was probably associated with thrusting t

morphology and distribution of fossil soils in the permo pennsylvanian wichita and bowie groups north central texas usa implications for western equatorial pangean palaeoclimate during icehouse greenhouse transition analysis of stacked permo pennsylvanian palaeosols from north central texas documents the influence of palaeolandscape position on pedogenesis in aggradational depositional settings palaeosols of the eastern shelf of the midland basin exhibit stratigraphic trends in the distribution of soil horizons structure rooting density clay mineralogy and colour that record long term changes in soil forming conditions driven by both local processes and regional climate palaeosols similar to modern histosols ultisols vertisols inceptisols and entisols all bearing morphological mineralogical and chemical characteristics consistent with a tropical humid climate represent the late pennsylvanian suite of palaeosol orders palaeosols similar to modern alfisols vertisols inceptisols aridisols and entisols preserve characteristics indicative of a drier and seasonal tropical climate throughout the lower permian strata the changes in palaeosol morphology are interpreted as being a result of an overall climatic trend from relatively humid and tropical moist conditions characterized by high rainfall in the late pennsylvanian to progressively drier semi arid to arid tropical climate characterized by seasonal rainfall in early permian time based on known late palaeozoic palaeogeography and current hypotheses for atmospheric circulation over western equatorial pangea the pennsylvanian palaeosols in this study may be recording a climate that is the result of an orographic control over regionalscale atmospheric circulation the trend towards a drier climate interpreted from the permian palaeosols may be recording the breakdown of this preexisting orographic effect and the onset of a monsoonal atmospheric circulation system over this region

the influence of island topography on typhoon track deflection abstracthigh resolution simulations for typhoon krosa 2007 and a set of idealized experiments are conducted using a full physics model to investigate the eminent deflection of typhoon track prior to its landfall over mountainous island topography the terrain height of taiwan plays the most important role in typhoon krosa s looping motion at its landfall while the surface properties details in the topographic shape of taiwan and the cloud microphysics are shown to be secondary to the track deflection a simulation with 3 km resolution and realistic model settings reproduces the observed krosa s track while that with 9 km resolution fails suggesting that high resolution to better resolve the typhoon terrain interactions is important for the prediction and simulation of typhoon track deflection prior to landfall results from idealized experiments with model configurations mimicking those of supertyphoon krosa show that vortices approaching the northern and central topography are significantly deflec

interaction of a baroclinic vortex with background shear application to hurricane movement abstract most extant studies of tropical cyclone movement consider a barotropic vortex on a plane however observations have shown that real tropical cyclones are strongly baroclinic with broad anticyclones aloft also the distribution of the large scale potential vorticity gradient in the tropical atmosphere is very nonuniform these properties may substantially influence the movement of such storms note that the anticyclone above a hurricane will interact with the lower hurricane vortex and induce storm motion such interaction can be caused by both the direct effect of ambient vertical shear and the effect of vertical variation of the background potential vorticity gradient in this paper an attempt to isolate the effect of background vertical shear is made the hurricane is represented in a two layer quasigeostrophic model as a point source of mass and zero potential vorticity air in the upper layer collocated with a point cyclone in the lower layer the model is integrated by the method of co

the effect of hawai i s big island on track and structure of tropical cyclones passing to the south and west abstractthe effect of the big island of hawai i on tropical cyclone tc track and structure is investigated using the weather research and forecasting wrf model the high 4000 m mountains of the big island modulate lower tropospheric flow in such a way that it can influence tcs hundreds of kilometers away from the island when a tc approaches from the east the blocking of lower tropospheric flow leads to a slowing of the tc s movement as a tc passes close to the south side of the big island it deviates southward the tc core convection and winds can become axisymmetric because of the blocking of the stronger northeasterly flow to the north of the storm the authors hypothesize that this axisymmetrization led to the unexpected eye formation of hurricane flossie 2007 just southeast of the big island as a tc moves into the lee southwest side of the big island the flow associated with the island wake leads to a track deviated to the right the hurricane dot 1959 simulations suggest that this

soil morphology of an alluvial chronosequence from the little river north carolina coastal plain usa abstract a soil chronosequence on terraces of the little river in the north carolina coastal plain was characterized to evaluate age related trends in pedogenesis five representative pedons per landform were studied from six late quaternary fluvial surfaces and temporal trends were assessed by regression of morphological parameters against previously reported terrace optical age estimates solum b horizon and bt horizon thickness subsoil clay content and buntley westin index rubification have strong positive correlations with age and together distinguish between soils of the floodplain 200 yr bp the first terrace 9 9 2 0 ka intermediate surfaces t2 t3b t4 17 4 4 2 74 6 10 4 ka and the oldest terrace t5b 94 0 15 9 ka over time soils develop from entisols with respective a c and a e bw c profiles on the floodplain and first terrace to ultisols with increasing argillic horizon thickness rubification and clay content on t2 t5b solum thickness bt horizon thickness and clay content display linear increases through time with soil thickening reflective of downward pedogenesis through permeable coarse grained alluvium increasing argillic horizon clay content is attributable to illuviation and possibly also to a combined bioturbation translocation process whereby clays scattered throughout sandy parent sediments are delivered to the surface by bioturbation then concentrated in b horizons by eluviation illuviation rubification increases with age and reflects transformation and subsoil concentration of inherited free iron rather than iron oxide formation from primary mineral weathering t5b pedons display morphologies comparable to those of 200 ka to 1 ma soils along coastal plain rivers that also drain the appalachian piedmont probably because sandy coastal plain derived little river alluvium has a higher hydraulic conductivity that promotes faster rates of downward weathering clay translocation and rubification than the more finely grained sediments of piedmont draining rivers thus textural differences related to sedimentary provenance should be recognized when interpreting chronosequences from the region although rates of pedogenesis differ among coastal plain alluvial soils linear trends in the 100 ka little river chronosequence may nonetheless correspond to the early more linear phases of development in studies from the region that span much longer intervals of time

effects of landfall location and the approach angle of a cyclone vortex encountering a mesoscale mountain range abstractthe orographic effects of landfall location approach angle and their combination on track deflection during the passage of a cyclone vortex over a mesoscale mountain range are investigated using idealized model simulations for an elongated mesoscale mountain range the local vorticity generation driving the cyclone vortex track deflection is more dominated by vorticity advection upstream of the mountain range by vorticity stretching over the lee side and its immediate downstream area and by vorticity advection again far downstream of the mountain as it steers the vortex back to its original direction of movement the vorticity advection upstream of the mountain range is caused by the flow splitting associated with orographic blocking it is found that the ideally simulated cyclone vortex tracks compare reasonably well with observed tracks of typhoons over taiwan s central mountain range cmr in analyzing the relative vorticity budget the authors found that jumps in the vortex path are lar

soil chronosequence studies in temperate to subtropical low latitude low relief terrain with data from the eastern united states the coastal plain of the eastern united states is a low latitude low altitude low relief terrain composed primarily of gently dipping marine and marginal marine sediments that range in age from cretaceous to quaternary population density of the area is moderate and most of the population is concentrated along the coast inland of the coast agriculture including growing trees for pulp is the dominant economy in this region soils have developed along two different pathways one pathway is dominated by the dissolution and movement of oxyhydroxides and the accumulation of organic matter the other by the accumulation of clays and oxyhydroxyides and the adsorption or oxidation of organic matter the first pathway has resulted in the formation of spodosols the second in the development of ultisols no clearly distinguishable age trends have been identified in the spodosols but the properties of ultisols can be measured to quantify surface material alteration through time ultisols are therefore suited to order of magnitude chronostratigraphic interpretations potentially data derived through the study of ultisols can be used to develop models that predict how surface processes will change due to continued weathering and pedogenesis or as the result of climate change

a numerical study of the track deflection of supertyphoon haitang 2005 prior to its landfall in taiwan abstract a series of numerical simulations are conducted using the advanced research version of the weather research and forecasting model with a 4 km fine mesh to examine the physical processes responsible for the significant track deflection and looping motion before the landfall of supertyphoon haitang 2005 in taiwan which poses a unique scientific and forecasting issue in the control experiment a low level northerly jet induced by the channeling effect forms in the western quadrant of the approaching storm where the inner core circulation is constrained by the presence of taiwan s terrain because of the channeling effect the strongest winds of the storm are shifted to the western portion of the eyewall the northerly advection flow averaged asymmetric winds within 100 km radius results in a sharp southward turn of the westward moving storm the time series of the advection flow shows that the advection wind vectors rotate cyclonically in time and well match the motion of the simulated vortex

on the geographic asymmetry of typhoon translation speed across the mountainous island of taiwan abstractthis paper examines the effect of topographically phase locked convection on the motion of typhoons across the island of taiwan data for 84 typhoons that reached taiwan s eastern coast from 1960 to 2010 are analyzed with motions compared to the long term average overland translation speed for 61 continuous track typhoons among all cases 77 of the slow moving tropical cyclones tcs made landfall on the northern end of taiwan s eastern coast while 60 of the fast storms had southeastern coastal landfalls this geographic asymmetry with respect to typhoon translation speeds widened after landfall as the slow movers typically decelerated during the overland period whereas the faster tcs sped up in particular the average overland duration was 16 h for the slow class compared to only 3 h for the fast moving typhoons the combination of slower translation with longer duration for the northern class of tcs led to large rainfall on the southwestern slope of the island s central mountain range we

roots of an archean volcanic arc complex the lac des iles area in ontario canada abstract the lac des iles area is located in the wabigoon subprovince an archean granite greenstone terrain in the superior province in ontario canada the area consists of several unmetamorphosed plutons of biotite and hornblende tonalite and mafic and ultramafic intrusions which are emplaced into an older tonalitic gneiss the mafic ultramafic bodies are concentric in shape and consist of periodotite pyroxenite gabbro and hornblende gabbro cumulates and diorite the largest intrusion the lac des iles complex consists of several mafic and ultramafic centers an internal sm nd isochron from the southern ultramafic complex gives an intrusion age of 2736 28 ma mswd 1 5 nd t 1 2 this age is also assumed to be representative of the time of emplacement of the other mafic and ultramafic bodies as well as the unmetamorphosed tonalite plutons the tonalitic gneiss represents older continental crust and had an nd value of 1 at this time the nd t values of the felsic and mafic ultramafic suites are positive ranging from 0 to 2 this range can be explained if primary magmas derived from a depleted mantle reservoir assimilated continental crust such as the tonalite gneiss during their ascent this implies that the tonalite magmas in the lac des iles area represent mixtures of the tonalite country rock and mantle magmas which formed by partial melting of depleted mantle or of mafic rocks underplated beneath the continental lithosphere the morphology and the rock assemblages of the mafic and ultramafic intrusions in the lac des iles area resemble alaskan type intrusions which are common components of phanerozoic magmatic arcs associated with subduction zones in addition the crystallization sequence in the mafic ultramafic intrusions suggests that they are derived from a parental magma with high al basalt affinities the mafic ultramafic rocks are depleted in high field strength elements but enriched in large ion lithophile elements and the tonalites belong to calc alkaline rock series displaying fractionation trends towards trondhjemitic compositions thus the archean lac des iles area and the root zones of phanerozoic active continental margins share many geological geochemical and petrological features which would suggest that the lac des iles area formed in an andean type continental margin

rb sr and u pb ages of volcanism and granite emplacement in the michipicoten belt wawa ontario the michipicoten greenstone belt at wawa ontario is typical of archean volcanic belts in the superior province the supracrustal rocks are divisible into lower middle and upper metavolcanic sequences which are separated by iron formation and clastic metasedimentary rocks these are intruded by granitic stocks and embayed by granitic batholiths this study reports whole rock rb sr and zircon u pb ages for the lower and upper metavolcanics for the granitic rocks that are physically within the greenstone belt internal granites and for the granitic rocks that embay the greenstone belt external granites the apparent rb sr ages for the lower metavolcanics are 2530 90 2285 70 and 2680 490 ma the u pb ages are 2749 2 and 2744 10 ma the internal granites give an rb sr age of 2560 270 ma and a u pb age of 2737 6 ma the external granite at hawk lake indicates an rb sr age of 2550 175 ma and a u pb age of 2747 7 ma it is possible that this unit contains elements older than 2812 ma as

interaction of typhoons with the taiwan orography part ii continuous and discontinuous tracks across the island abstract numerical model simulations of west moving tropical cyclones approaching and crossing the taiwan orography are shown to contain many of the observed surface features vortices tend to track continuously around the northern end of the island due to the deflection of the deep layer mean flow and the vortex circulation is modified less because the higher winds to the right of the center do not have a strong interaction with the barrier discontinuous tracks predominate for vortices approaching the central southern portions of the taiwan orography severe distortions of the inner core circulation occur and the surface pressure and surface wind centers become decoupled and may be dissipated at different rates numerical sensitivity studies demonstrate that more intense and rapidly moving vortices are more like to cross directly over the barrier and thus maintain a continuous track in one special case of a weak but fast moving vortex approaching the southern end the model simulates the existence of

the temporal evolution of sanukitoids in the karelian craton baltic shield an ion microprobe u th pb isotopic study of zircons abstract the u th pb isotopic systematics of zircons from six sanukitoid intrusions in the karelian craton has been investigated using the secondary ion mass spectrometer sims our results show that karelian sanukitoids formed between 2745 and 2705 ma ago and that there is an age difference of about 30 ma between sanukitoids in the eastern and western karelia results for intrusions made up of a number of magmatic phases show no internal age variation in the east of the study region zircons from a monzodiorite and two quartz monzonites from the panozero pluton were dated at 2737 11 2739 11 and 2741 8 ma in the hautavaara pluton a monzodiorite and a subalkaline granite were dated at 2743 8 and 2742 23 ma and a quartz diorite from the elmus pluton gave an age of 2741 7 ma in addition a lamprophyre dyke within the sjargozero pluton gave an age of 2742 14 ma in the west zircons from a quartz monzonite and a granodiorite in the njuk intrusion gave ages of 2709 10 and 2716 11 ma in the kurgelampi pluton zircons from a diorite and two granodiorites were dated at 2707 9 2719 6 and 2712 9 ma respectively zircons from the granodiorites and the alkaline granites contain older cores with 207 pb 206 pb ages greater than 2800 ma the absence of inherited zircons in the more mafic sanukitoids is attributed to their higher saturation levels for zirconium sanukitoid zircons have th u ratios above 0 5 and often higher whereas nearby tonalite tondhjemite granodiorites ttgs have th u ratios below 0 5 typically tonalites are older than sanukitoids by more than 100 ma and it is possible that tectonic processes associated with the collision of the belomorian mobile belt provided the heat necessary to initiate the generation of the sanukitoid melts

convergent margin tectonics central wabigoon subprovince superior province canada abstract best known for its neoarchean greenstone granite terranes in the east and west the wabigoon subprovince of the superior province features a central transverse corridor of meso and neoarchean gneissic granitoid and minor supracrustal rocks resembling an eroded intermontane plateau structural analysis and u pb geochronology in the north central wabigoon subprovince reveal a complex history of plutonism supracrustal rock deposition polyphase deformation and amphibolite facies metamorphism between 3075 and 2670 ma the geometric and kinematic character of d 1 and d 2 deformational events recorded in 2890 2718 ma tonalitic gneisses remain cryptic as a result of magmatic and structural d 3 5 overprinting but the early structures are bracketed in age between 2725 and 2713 ma by a polydeformed gneiss and tonalite dyke these events occurred deep within an active continental magmatic arc and correspond in age to a collision between the juvenile wabigoon and continental winnipeg river subprovinces recognized to the west clastic sediments deposited after 2701 ma are the youngest rocks involved in subsequent regional deformation a d 3 event is responsible for rapid burial of supracrustal units to 15 km within warm arc crust and imposition of a regional penetrative s 3 foliation that accommodated some relative uplift prior to 2697 ma the age of a discordant granodiorite dyke this event corresponds to variably preserved steep north trending d 1 structures recognized in adjacent greenstone belts subsequent d 4 ductile deformation defines the map pattern in the deep crustal rocks of the central wabigoon subprovince upright east trending f 4 folds developed synchronously with d 2 dextral transpressive structures that formed throughout the wabigoon subprovince prior to 2698 ma the final d 5 sinistral shearing event occurred during emplacement of mantle derived granodiorites of sanukitoid affinity 2688 ma and crust derived granites 2685 ma this event appears to have triggered rapid cooling reflected in 2680 2670 ma titanite dates and late brittle increments of displacement

numerical simulation of typhoon gladys 1994 and its interaction with taiwan terrain using the gfdl hurricane model abstract numerical integrations using the geophysical fluid dynamics laboratory gfdl hurricane model were performed to study the evolution of typhoon gladys 1994 and its interaction with the taiwan terrain consistent with most previous studies the taiwan topography results in the deceleration of gladys s translation speed and southward deviation as it approaches taiwan on the other hand gladys accelerates northwestward while passing taiwan which is likely to be related to the moist processes and differs from the track pattern in the dry model of lin et al although the gfdl hurricane model forecast underestimates gladys s intensity the model can capture the evolution of gladys s intensity especially its weakening during landfall which is primarily due to the cutoff of the water vapor supply in the boundary layer as gladys approached the taiwan terrain other mesoscale phenomena including the pattern of heavy precipitation and the formation of secondary lows are well simulated by the model

tropical cyclone movement and surrounding flow relationships abstract this paper presents results of a comprehensive study of the relationship between the movement of tropical cyclones and the large scale circulation which surrounds them cyclones have been stratified by direction and speed of movement latitude intensity change and size as determined by the radius of the outermost closed surface isobar in three ocean basins the northwest pacific the west atlantic and the australian south pacific region twenty one different stratifications are available in the northwest pacific 13 in the west atlantic and 6 in the australian south pacific area cyclone movement and surrounding flow relationships were studied at different pressure levels and a variety of radii pressure weighted layer averages were also analyzed in search of such relationships results show an important relationship between surrounding large scale flow and tropical cyclone movement for all stratifications the winds in the mid troposphere 500 700 mb at 5 7 latitude radius from the cyclone

the use of element clay ratios assessing gains and losses of iron manganese and phosphorus in soils of sedimentary rocks on a landscape scale abstract quantitative statements about soil development on a landscape level of scale are difficult to work out especially in soils of stratified sediments this article presents an easily applicable method to infer gains and losses of fe mn and p in soilscapes developed on sedimentary rocks for this an element clay ratio was introduced the amounts of pedogenic cbd fe mn and total p in kg were calculated on a pedon basis i e for the volume under 1 m 2 down to the c horizon or any arbitrary depth in soils without a c horizon and divided by the amounts of clay in the same volume p ratio a comparison with the element clay ratio of the mixture of parent material s c ratio allows semi quantitative statements about elemental gains and losses due to solutional processes if only transformation processes are working p ratios should equal the c ratios in the case of fe and mn i e remaining constant with time any depletion or relative or absolute accumulation of the elements can be inferred from values which differ from this trend in the case of phosphorus the p ratios should decrease with time compared to the c ratios relative and absolute gains should result in minor differences between p and c ratios or p ratios exceeding c ratios the results of mass balance calculations on 27 pedons of southwestern germany with a broad amplitude of parameters fe mn p clay redoximorphism as well as the results of chronosequences of different climates parent materials and durations of soil development fits very well with the results of the ratio method developed by using the ratio method areas of depletion and accumulation can be identified in catenary studies as well as linkages between soils inferred e g interpedon translocations deductions of influences of man are possible too the assumptions and restrictions of the method were discussed in detail

soil forming processes and rates on uplifted marine terraces in southwestern oregon usa soil chronosequences were examined on flights of tectonically uplifted marine terraces near cape blanco and cape arago southwestern oregon all of the soils contain abundant organic c and are strongly acidic ph in h2o 30 of the exchange sites saturated with al the soils in the two areas show a progression in development from spodosols to spodosols with clay enriched horizons and eventually to ultisols although the spodic and argillic horizons appear to be forming concurrently in the soils evidence is presented to support the concept that the spodic horizon is eventually masked by clay accumulation because of weathering in situ neoformation of clays and clay translocation the primary age related trends include increases in 1 the relative abundance of silt and clay 2 the ratio of quartz to feldspars in the very fine sand 100 50 m fraction and 3 the amounts of dithionite extractable fe and al and crystalline forms of fe in the profile

a numerical investigation of the convective systems in the vicinity of southern taiwan associated with typhoon fanapi 2010 formation mechanism of double rainfall peaks the westbound typhoon fanapi 2010 brought 872 mm daily rainfall over the coastal plain in southern taiwan which is comparable to the extreme rainfall of 1080 mm over the southern central mountain range cmr in this study the weather research and forecast model was used to investigate the formation mechanism of the two rainfall peaks and the associated dynamics of the convective systems in the vicinity of southern taiwan as the vortex that deflects somewhat southward near landfall moves over the cmr the vortex slows down significantly during westward departure and induces strong near coastal convergence at lower levels with the westerly to southwesterly outer flow the associated intense latent heating of the near coastal rainfall greatly contributes to positive potential vorticity pv with enhanced vorticity stretching near the convex eyewall when the vortex becomes more asymmetric and longitudinally elongated the positive pv tendency near the coast is induced not only by vertical differential diabatic heating ddh but also by the longitudinal ddh mainly associated with positive vorticity tilting the longitudinal ddh indeed dominates all other processes in the pv generation inside the eyewall further offshore which is vital to the maintenance of the eyewall with the strong banded convergence and is special to typical intense cyclones over the open ocean the formation of the double intense rainfall peaks cannot occur without a precise departing track near the southwest coast in association with the slowdown of the vortex core when the cmr height is significantly reduced or latent heating is deactivated after landfall

interaction of typhoons with the taiwan orography part i upstream track deflections abstract a combined observational and numerical modeling approach is used to study the upstream track deflections of westward moving tropical cyclones approaching the mountainous terrain of taiwan although the standard deviations are large the mean track deflections are larger and have a different orientation for storms approaching the southern end of the island from those approaching the northern end the deflections tend to be larger for weaker and slower moving storms two distinct regions of upstream track deflections that are detected in the observations are explored in a sensitivity study with a 45 km horizontal resolution and 16 layer numerical model as the outer circulation of the tropical cyclone begins to interact with the mountain barrier the zonal decelerations and southward track deflections are explained by an enhanced blocking and deflection of the environmental flow advecting the cyclone the larger effect for southern approaching storms compared to northern storms is because the stron

monsoonal influence on typhoon morakot 2009 part ii numerical study abstractin the second part of this study numerical experiments are conducted to investigate the influences of multi time scale monsoonal flows on the track change of typhoon morakot 2009 while the control simulation captures the slowing and northward deflections in the vicinity of taiwan island the highly asymmetric rainfall structure and the associated rainfall pattern sensitivity experiments suggest that the westward movement prior to the landfall on taiwan and the subsequent northward shifts in the vicinity of taiwan were closely associated with the interaction between morakot and multi time scale monsoonal flows prior to the landfall on taiwan morakot moved westward directly toward taiwan because of a synoptic wave train like pattern which consisted of goni over mainland china morakot and a cyclone over the western north pacific with an anticyclone to the west of morakot numerical simulation suggests that strong northerly winds between morakot and the anticyclone reduced the northward stee

rates and processes of soil evolution on uplifted marine terraces northern california time dependent changes in soil development have been evaluated for two flights of uplifted marine terraces with similar site characteristics and a range in terrace ages 3 9 ka to 330 ka in northern california six pedogenic properties of soils developed in unconsolidated deposits overlying bedrock marine platforms have systematic time dependent trends but each property differs in rate of change and in the time period over which its changes are useful as relative age dating or correlation tools changes in accumulated mass of organic carbon and ph are useful properties only for the youngest soils and probably for soils less than 10 20 ka in this climatic region soils on terraces older than 29 ka have nearly similar amounts of mass of organic carbon with values of about 3 6 by weight for the upper meter of the soil profile soil reaction ph in the top 20 cm of the soil profile decreases at a rapidly declining rate reaching and maintaining a value of 5 by 39 40 ka total mass of accumulated clay is an excellent indicator of relative soil age during all stages of soil development the rate of accumulation of clay is about 0 4 g cm2 soil column per thousand years so that pedons on terraces with inferred ages of about 124 ka have accumulated at least 50 g cm2 soil column of clay systematic and linear increases in accumulated mass of several forms of pedogenic iron make them very useful for chronological purposed for at least 240 ky of soil development crystalline forms of iron enable greater distinction among young soils than amorphous forms which have negligible accumulations until at least 40 ka the rate of accumulation of crystalline forms of iron fed feo is about 0 02 g cm2 soil column per thousand years so that pedons on terraces with inferred ages of about 124 ka have accumulated about 3 g cm2 soil column of crystalline forms of pedogenic iron changes with time in accumulated mass of amorphous forms of pedogenic aluminum alo are negligible within the first 29 ka then reflect a rapid increase in rate of accumulation until at least 124 ka two pedons from the same terrace inferred age 124 ka contain strikingly different amounts of pedogenic alo however and suggest that alo may be an unreliable indicator of the degree of soil development in addition to mass values of different soil substances maximum percent values were calculated soils developed on marine terraces older than 29 ka have at least 10 maximum clay older than 100 ka at least 30 maximum clay and older than 240 ka at least 40 50 maximum clay soils on terraces younger than 29 ka have less than 1 maximum fed and soils older than 240 ka at have at least 4 maximum fed these easily obtained values provide textural and chemical boundaries for separating marine terraces younger or older than about 29 100 and 240 ka in this region but are useful only as very general tools for correlation maximum percent clay is a more reliable indicator of soil age than maximum percent fed as the latter is greatly influenced by local groundwater flux and percent values of fed have a high degree of scatter

geochemical and u pb zircon geochronological constraints on the development of a late archean greenstone belt at birch lake superior province canada abstract this paper presents new high precision u pb zircon ages that place constraints on the timing of magmatic activity volcanic and plutonic deformation and gold mineralization within the late archean birch confederation lakes greenstone belt within the uchi subprovince of the superior province geochemical data including sm nd isotopic analyses place additional constraints on the nature of the magmatic activity three volcanic rocks from the birch lake area have similar ages 2742 2 1 8 1 7 2739 1 2 8 and 2741 7 2 3 2 2 ma and together with previously published data suggest that a major proportion of the volcanic rocks of the greenstone belt were erupted in a narrow time interval from 2742 to 2735 ma older volcanic rocks recognized to the south of the birch lake area are either absent or of limited extent plutonic rocks include the pre to syn tectonic horseshoe island stock 2725 0 2 5 ma the syn tectonic mainprize lake batholith 2724 3 1 8 1 5 ma and the late to post tectonic shabumeni lake stock 2710 8 1 9 1 3 ma and okanse lake pluton 2700 8 1 9 1 4 ma these ages and structural relationships indicate that the development of a d2 regional penetrative fabric at least in part post dates the emplacement of the horseshoe island stock this is consistent with the interpretation that d2 deformation developed synchronously with and perhaps in response to the emplacement of the mainprize lake batholith an earlier d1 penetrative deformational event as well as possible large scale subhorizontal structures d0 developed subsequent to the deposition of the youngest volcanic rocks and prior to d2 plutons are younger than and unrelated to volcanism in contrast to volcanic rocks plutons show no indication of having interacted with older felsic crustal rocks and are interpreted to be derived from partial melting of metasomatized mantle and subducted tholeiitic basalt the okanse lake pluton has affinities with the sanukitoid suite and is closely comparable in age to similar plutons over a wide area it is proposed that a 2700 ma sanukitoid magmatic event may reflect melting of previously metasomatized mantle in response to thermal re equilibration associated with the transition from an earlier subduction dominated regime to a later post collisional stage culminating in the stabilization of the northern superior province

the lac des iles complex ontario petrology and platinum group elements mineralization in an archean mafic intrusion the lac des iles complex is a late archean mafic to ultramafic complex that is host to 20 4 106 t pt pd and au mineralization with an average grade of 6 34 g t platinum group elements pge the 30 km2 complex located in the wabigoon subprovince consists of several coalescing mafic to ultramafic intrusive centers the complex is emplaced into early gneissic tonalite and is contemporaneous with late granitoids the magmatic evolution of the complex reflects the emplacement of multiple pulses of previously fractionated magma some of which underwent subsequent in situ fractionation distinct magma sequences are recognized on the basis of intrusive relationships differences in the cumulus minerals crystallization order and trace element chemistry these sequences are 1 hornblende gabbro 2 gabbro and gabbronorite and 3 ultramafic where there is evidence of intrusive relations the most primitive sequences are emplaced late and occur toward the north end of the complex microprobe analyses in

zircon u pb ages from the wabigoon manitou lakes region wabigoon subprovince northwest ontario three distinct stratigraphic units have been recognized in the crow lake savant lake belt these are a basal unit consisting of high magnesium tholeiitic flows a middle unit consisting mostly of tholeiitic to calc alkaline pyroclastic rocks and flows and an upper unit of high iron tholeiitic flows a zircon u pb study has been carried out on seven rocks from the wabigoon manitou lakes region of this belt in the manitou lakes area a minimum age of 2755 ma on a porphyry pluton intruded into the wapageisi volcanics gives a minimum age for the high magnesium tholeiitic sequence a trondhjemite phase of the atikwa batholith near wabigoon lake that is dated at 2732 2 2 9 ma has the same age within experimental error as a rhyolite flow from the lower wabigoon volcanics in the same area that is dated at however a trondhjemite phase of the atikwa batholith at eagle lake that is dated at is distinctly younger than a dacite flow collected nearby from the lower wabigoon volcanics that is dated at both thes

idealized simulations of the effect of taiwan topography on the tracks of tropical cyclones with different steering flow strengths this is the fourth part of a study on the effect of topography on tropical cyclone tc tracks in previous parts idealized simulations were conducted using the weather research and forecasting model to investigate the underlying mechanisms for the upstream deflection and the local and remote topography effect on tcs with different sizes none of these simulations included any background flow in this part uniform easterly steering flows of 5 and 10 m s 1 are introduced to study the track changes under such conditions lee vortices are generated downstream of the taiwan topography by the steering flow the tc terrain induced gyres found in the previous parts also develop when the tc circulation begins to interact with the topography and subsequently dominate over taiwan the cyclonic gyre merges with the cyclonic lee vortex induced by the steering flow and the anticyclonic gyre is advected cyclonically around the tc centre which later deflects the tc because the circulation at the outer radii of a tc competes with the steering flow a smaller tc under a stronger steering flow has to move closer to taiwan in order to generate such gyres this delayed generation of the gyres then leads to the delayed onset of the northward deflection for such a tc for a large tc the circulation at its southern part is weakened by the steering flow so that the track of the anticyclonic terrain induced gyre is changed which results in a larger track deflection of the tc

archean tectonic and metallogenic evolution of the superior province of the canadian shield abstract the superior province of the canadian shield has mainly experienced an archean tectonic history comprising several cycles of volcanism plutonism and tectonism although the rocks of the superior province span more than 500 million years of archean time most mineral deposits formed in an interval of 100 million years or less corresponding to a period of accretion of oceanic and pre existing continental fragments in the late archean at 2 7 ga in accord with recent tectonic syntheses which argue for the accretionary origin of the superior province the metallogenic history of the superior province can also be interpreted in the same context provided secular anomalies in the early history of the earth are acknowledged for relatively unique deposit types such as komatiitic nickel deposits and voluminous iron formations volcanogenic massive sulphide iode gold and granitoid associated deposits as well as ni cu pge cr and ti deposits associated with mafic ultramafic intrusions are readily interpreted in terms of the construction and accretion of late archean island arcs

track deflection of typhoon nesat 2017 as realized by multiresolution simulations of a global model abstracttyphoon nesat 2017 headed west northwestward toward taiwan but took a relatively larger northward deflection about 300 km away and then a leftward deflection after landfall at northern ta

stratigraphy and petrology of the lower part of the mulcahy gabbro northwestern ontario origin of reverse and normal fractionation trends and implications for tectonic setting of late archean mafic magmatism the mulcahy gabbro 2 73 ga is an exceptionally well preserved tholeiitic layered intrusion located in the wabigoon subprovince of the superior province the intrusion has a 900 m thick marginal z

monsoonal influence on typhoon morakot 2009 part i observational analysis abstracttyphoon morakot made landfall on taiwan with a record rainfall of 3031 5 mm during 6 13 august 2009 while previous studies have emphasized the influence of southwesterly winds associated with intraseasonal oscillations and monsoon surges on moisture supply the interaction between morakot and low frequency monsoon flows and the resulting influence on the slow movement and asymmetric precipitation structure of the typhoon were examined observationally embedded in multi time scale monsoonal flows morakot generally moved westward prior to its landfall on taiwan and underwent a coalescence process first with a cyclonic gyre on the quasi biweekly oscillation time scale and then with a cyclonic gyre on the madden julian oscillation time scale the coalescence enhanced the synoptic scale southwesterly winds of morakot and thus decreased its westward movement and turned the track northward leading to an unusually long residence time in the vicinity of taiwan the resulting slow movement and collocation

a soil chronosequence on quaternary marine terraces san clemente island california a soil chronosequence on marine terraces was examined on san clemente island california in an arid mediterranean climate in order to see which soil properties differ most systematically with time ages of the geomorphic surfaces were determined by radiocarbon uranium series and amino acid racemization techniques and range from 1 000 000 yrs soils on surfaces 200 000 yrs old are vertisols or alfisols with vertic properties such as slickensides and cracks and they exhibit both prismatic and angular blocky sphenoidal or only angular blocky structure solum thickness increases linearly with age of geomorphic surface clay soluble salts ald smectite mica ratios in the clay fraction and quartz plagioclase ratios in the silt fraction when expressed as profile summations show increases with age of geomorphic surface the best fit regression equations are linear with the exception of ald which is best expressed as a power function important soilforming processes appear to be alteration of mica to smectite accumulation at depth of soluble salts derived from marine aerosols possibly additions of eolian materials clay illuviation in the younger soils and pedoturbation in the older soils the observations reported here allow the following conclusions to be drawn about soils in this environment 1 certain soil properties which show distinct trends with time can be used for relative age dating in geomorphic and stratigraphic studies 2 soils have not reached a steady state condition with respect to many of their properties and 3 alfisols and mollisols with natric b horizons may be precursors to vertisols

orographic influence on a drifting cyclone abstract in this study a primitive equation numerical model is adopted to investigate the orographic influence on a drifting cyclone over an idealized topography similar to that of taiwan for a cyclone propagating from the east and impinging on the central portion of the mountain a northerly surface jet tends to form upstream of the mountain between the primary cyclone and the mountain due to blocking and channeling effects two pressure ridges and one trough are also produced when the cyclone approaches the mountain the low level vorticity and low pressure centers decelerate and turn southward upstream of the mountain due to orographic blocking at the same time the upstream low level vorticity is blocked by the mountain the abrupt increase of surface vorticity and the contraction of cyclone scale on the lee side are explained by the generation of new potential vorticity pv due to wave breaking associated with the severe downslope wind and hydraulic jump the generation of this new pv is evidenc

the impact of idealized terrain on upstream tropical cyclone track abstracttropical cyclones tcs encountering the terrain of taiwan usually experience prominent track deflection resulting in uncertainty in tc track forecasts the underlying mechanisms of tc def

zircon u pb ages from the kakagi lake area wabigoon subprovince northwest ontario five rocks have been dated from the kakagi lake area of the wabigoon subprovince by means of u pb analysis of zircons using the techniques of air abrasion and high gradient magnetic separation zi

shallow sampling by multi shot laser ablation and its application within u pb zircon geochronology abstract the interaction of incident laser radiation and sample substrate is complex and difficult to predict natural zircons are often both structurally and chemically heterogeneous in 3 dimensional space encountering growth related structural micro heterogeneities inclusions and chemical complexities is almost inevitable during a static ablation of several tens of seconds a multi shot approach to laser ablation described here implements a minimal sample exposure time to incident laser radiation by applying multiple 1 hz shots to a single sample location in delayed succession this process can be conceptualised as a slowing down of a high frequency 5 20 hz static laser ablation inductively coupled plasma mass spectrometry la icp ms analysis until each laser pulse is distinct albeit transient the ability to integrate and collate signal pulses for a small number of consecutive laser shots as opposed to continuously pulsing the laser produces precise age determinations 1 reproducibility 2 level on small sample volumes 704 23 m3 on 91500 zircon standard the multi shot la icp ms protocol employed here significantly reduces the effect of downhole fractionation as the resultant craters are extremely shallow as shallow as 0 56 0 02 m on 91500 zircon standard and maintain an aspect ratio of 1 further benefits include a reduced probability of thermally induced effects e g substrate melting plasma loading and the potential for signal mixing with depth in a heterogeneous sample

some aspects of vortex structure related to tropical cyclone motion abstract some effect of tropical cyclone structure on the vortex motion are examined in a nondivergent barotropic numerical model with no basic current as suggested earlier by demaria the initial maximum wind speed has little effect on the track vortex translation associated with the beta effect depends sensitively on the strength of the flow between 300 and 1000 km from the center if the flow in this annulus is made more cyclonic the track will turn cyclonically and move more toward the west in the northern hemisphere the dynamics of this beta drift is studied via a decomposition into symmetric and asymmetric circulations the symmetric flow experiences a slight weakening of the maximum wind speed and an anticyclonic circulation is induced beyond 600 km the asymmetric circulation is dominated by an azimuthal wavenumber one circulation with an anticyclonic gyre east of the center a cyclonic gyre to the west and a nearly uniform broad scale ventilation flow between the gyres the vortex translati

geochronologic evidence for a possible mis 11 emergent barrier beach ridge in southeastern georgia usa abstract predominantly clastic off lapping transgressive near shore marine sediment packages that are morphologically expressed as subparallel ne trending barriers beach ridges and associated back barrier areas characterize the near surface stratigraphic section between the savannah and the ogeechee rivers in effingham county southeastern georgia each barrier back barrier shoreline complex is lower than and cut into a higher older complex each barrier or shoreline complex overlies miocene strata no direct age data are available for these deposits previous researchers have disagreed on their age and provenance using luminescence and meteoric beryllium 10 10 be inventory analyses we estimated a minimum age for the largest westernmost morphologically identifiable and topographically highest barrier beach ridge the wicomico shoreline barrier and constrained the age of a suite of younger barrier beach ridges that lie adjacent and seaward of the wicomico shoreline barrier at the study site the near shore marine estuarine deposits underlying the wicomico shoreline barrier are overlain by eolian sand and an intervening zone of mixing optically stimulated luminescence osl data indicate ages of 43 ka for the eolian sand and 116 ka for the zone of mixing meteoric 10 be and pedostratigraphic data indicate minimum residence times of 33 4 ka for the eolian sand 80 6 ka for the zone of mixing and 247 ka for the paleosol the combined osl and 10 be age data indicate that at this locality the barrier beach ridge has a minimum age of about 360 ka this age for the wicomico shoreline barrier deposit is the first for any pleistocene near shore marine estuarine deposit in southeast georgia that is conclusively older than 80 ka the 360 ka minimum age is in agreement with other geochronologic data for near coastline deposits in georgia and south carolina the geomorphic position of this barrier beach ridge is similar to deposits in south carolina considered to be 450 ka to 1 ma the age and geomorphic data for georgia and south carolina possibly suggest the presence of mis 11 420 360 ka shoreline deposits between 15 m and 28 m above present sea level in the southeastern atlantic coastal plain

numerical study of convection observed during the winter monsoon experiment using a mesoscale two dimensional model abstract a two dimensional version of the pennsylvania state university mesoscale model has been applied to winter monsoon experiment data in order to simulate the diurnally occurring convection observed over the south china sea the domain includes a representation of part of borneo as well as the sea so that the model can simulate the initiation of convection also included in the model are parameterizations of mesoscale ice phase and moisture processes and longwave and shortwave radiation with a diurnal cycle this allows use of the model to test the relative importance of various heating mechanisms to the stratiform cloud deck which typically occupies several hundred kilometers of the domain frank and cohen s cumulus parameterization scheme is employed to represent vital unresolved vertical transports in the convective area the major conclusions are ice phase processes are important in determining the level of maximum large scale heating and vertical motion because there is a strong anvil componen

an investigation on how inner core structures obtained through radar data assimilation affect track forecasting of typhoon jangmi 2008 near taiwan island the impacts of radar data assimilation da on the westward track deflection of typhoon jangmi 2008 near taiwan island and the deflection mechanism are investigated initial conditions from two data assimilation experiments with significant track forecast differences are analyzed and compared the environmental axisymmetric wavenumber 1 to 3 asymmetric fields of the typhoon are decomposed using vortex separation and fourier decomposition methods the components are selectively recomposed into new initial conditions that include different vortex scale components to examine the impact of individual components on the track prediction the wavenumber 1 asymmetric structure is found to play a dominant role in the westward deflection of typhoon jangmi and the accurate analysis of this component with radar da helps to improve the track forecast the wavenumber 1 asymmetric circulation is manifested as a pair of cyclonic and anticyclonic gyres with well defined ventilation flows through the inner core region which provides additional steering of the typhoon vortex the layer mean environmental steering flow and ventilation flow associated with the wavenumber 1 gyres are further calculated to quantitatively evaluate the impact of ventilation flow the ventilation flow is shown to be responsible for most of the westward motion component suggesting again its role in causing the westward track deflection of typhoon jangmi the results also suggest the importance of analyzing vortex scale asymmetric structures for accurate tropical cyclone track forecasting especially when there is a significant track deflection

a semi quantitative model for fractionation of rhyolite from rhyodacite in a compositionally altered archean volcanic complex superior province canada abstract the phinncy dash lakes complex pdlc of the western wabigoon subprovince northwestern ontario consists of subvolcanic and pyroclastic rhyodacite subordinate rhyolite pyroclastic rocks and lava flows minor intercalated basalt lava flows and related clastic and chemical sediments which have been metamorphosed to low greenschist grade the basalt lying stratigraphically below the complex is intruded by tonalite that is coeval with the felsic volcanic rocks rhyolite in pdlc differs from the associated rhyodacite by containing k feldspar and having lower la yb ratios negative eu anomalies and generally lower fe mg ca ti al p zr sc and cr but higher si k rb ba and nb major and trace element calculations using estimates of rhyodacite and rhyolite primary phenocryst compositions and estimates of partition coefficients were done to determine if the rhyolite may have been generated by fractional crystallization from the rhyodacite it was found that fractionation of plagioclase clinopyroxene quartz and small amounts of apatite zircon allanite and fe ti oxides from the rhyodacite would produce a composition similar to the rhyolite only if the abundances of the mobile elements si ca na sr ba and mg in the rhyodacite initial composition were adjusted from the measured values if the rhyolite fractionated from the rhyodacite then there must have been a net addition of si 2 net depletion of ca na sr and ba and 3 net depletion of mg but conservation of fe in the rhyodacite during synvolcanic alteration or regional metamorphism these inferences are supported by thin section evidence of 1 addition of quartz in microfractures and groundmass 2 breakdown of primary plagioclase and 3 breakdown of primary mafic silicates plots of mgo versus tio2 and feo versus tio2 also demonstrate that by comparison with the nearby and coeval kishkutena tonalite mg is depleted and fe is conserved in the pdlc rocks the secondary mineral assemblages combined with the apparent chemical reconstitution suggest that during alteration of the pdlc rocks 1 the water to rock ratio was small 2 the fluid temperature was low probably below about 300 c 3 if the temperature and water to rock ratio were large however then the fluid source was probably not seawater because of the limited precipitation of mg to the rocks

idealized simulations of the effect of taiwan topography on the tracks of tropical cyclones with different sizes this is the third part of a study of the effect of topography on tropical cyclone tc tracks in previous parts idealized simulations were conducted using the weather research and forecasting model to study the underlying mechanisms for the upstream northward deflection of a tc and the effects of local and remote topography the initial tc size was the same in all these simulations in this third part the track deflections of tcs with different sizes are investigated as in the two earlier parts the simulations are made on a beta plane with no background flow for a tc approaching taiwan there is an apparent optimal tc size with the largest northward deflection however an appreciable track deflection is only found for smaller tcs approaching taiwan directly in addition as might be expected the onset location of the northward deflection is closer to taiwan for smaller tcs moreover the contribution from diabatic heating is opposite to that from horizontal advection ha in the potential vorticity tendency pvt calculation due to the vertical wind shear induced by the terrain induced gyres although ha is still the dominant term in the pvt equation a southward deflection on the eastern side of taiwan is found in some smaller tc cases a looping track occurs for a medium size tc approaching central taiwan and a v shape track is found for a small size tc approaching northern taiwan among the cases some similarities can be found first the gyre flow becomes weak so that the tc is slowed down second an individual cyclonic gyre is found on the southeastern side of taiwan so that the tc is deflected westward and then southward third another newly generated gyre pair pushes the tc northward after the southward deflection

evolution and tectonic significance of intermediate to felsic plutonism associated with the hemlo greenstone belt superior province canada abstract plutonic rocks from the hemlo area in the southern superior province span a period from ca 2720 to 2677 ma early ttg plutons intruded into lower basaltic volcanic sequences and were probably derived from melting of basaltic crust at upper mantle depths they predate major regional deformation and span ages from 2719 to 2697 ma felsic to intermediate volcanism 2697 2688 ma partially overlaps ttg plutonism but is mostly slightly younger and lacking plutonic equivalents regional deformation and metamorphism of the greenstone belt and ttg plutons progressed rapidly following deposition of the youngest supracrustal rocks syn to late tectonic plutons emplaced between 2684 and 2677 ma have a distinctive dual primitive evolved character that is interpreted to reflect their derivation by direct melting of long term depleted mantle that was metasomatically enriched in a wide range of lile and hfse this secular evolutionary change in the nature of intermediate to felsic plutonism at hemlo and its relationship to regional deformation and metamorphism parallels that occurring more regionally within the superior province and is interpreted to be the consequence of a transition in the nature of large scale tectonic processes intermediate to felsic magmatism within a protracted period of volcanism and ttg plutonism originated primarily by melting of subducted basaltic crust probably in an oceanic arc related environment the termination of this style of magmatic activity and initiation of regional deformation and metamorphism at ca 2688 ma is interpreted to be a consequence of collisional orogeny the petrogenetic characteristics of the latest period of magmatism at 2684 2677 ma requires that the melting regime migrate into sub arc lithospheric mantle that was metasomatized during the earlier magmatic stage slab breakoff following terrane accretion is suggested as one possible mechanism for the abrupt termination of ttg magmatism and ensuing rapid and progressive introduction of large amounts of heat into sub arc mantle and basal portions of the crust this pattern of development is seen in many superior province greenstone belts but is older in the north therefore it is probably an inevitable consequence of the tectonic processes that led to accretion of the superior province

effects of terrain on the surface structure of typhoons over taiwan abstract the island of taiwan is situated in the main path of western north pacific typhoons its dominant central mountain range cmr with a hoizontal scale comparable to the radius of a typhoon often produces significant distortions in the typhoon circulation a 20 year dataset from 22 surface stations is used to describe the effects of the taiwan terrain on the surface structure of typhoons empirical orthogonal function analysis on the pressure field is used to identify the primary structure modes the first mode is a uniform sign anomaly pattern portraying the decrease in pressure as a typhoon is approaching the second mode represents the strong terrain induced west east pressure gradient that is normal to the main axis of the cmr the third mode results mainly from the west cast pressure gradient arising from the relative location of the typhoon center to the east or west of taiwan but it also contains a weak south north pressure gradient that can he attributed to the terrain a regression tech

control parameters for the influence of a mesoscale mountain range on cyclone track continuity and deflection abstract in this study prospective control parameters are identified for diagnosing the continuity and deflection of cyclone tracks across a mesoscale mountain range based on idealized simulations of a westward moving cyclone it was found that the cyclone track becomes a discontinuous continuous track and the cyclone experiences more less deflection with a combination of small large values of vmax nh u nh r ly u flx and vmax fr and large small value of h lx the symbols are defined as follows vmax the maximum tangential wind n the brunt vaisala frequency h the mountain height u the basic wind speed r the radius of vmax f the coriolis parameter and lx and ly the horizontal scales of the mountain in x and y directions respectively a conceptual model is proposed to explain track deflection and continuity for a westward moving cyclone encountering idealized topography representative of the central mountain range of taiwan with weak orographic blocking a cyclone crosses over the mount

age and isotopic composition of late archean leucogranites implications for continental collision in the western superior province u pb and sm nd isotopic data are presented for leucogranites and pegmatites from the boundary zones of the english river winnipeg river and wabigoon subprovinces in the late archean superior prov

influence of mesoscale topography on tropical cyclone tracks further examination of the channeling effect abstractobservations have documented typhoons experiencing pronounced track deflection before making landfall in taiwan in this study idealized full physics model experiments are conducted to assess the orographic influence on tropical cyclone tc track an intense and westward moving tc is simulated to approach the bell shaped terrain imitating the taiwan topography sensitivity numerical experiments are carried out to evaluate the topographic effect under different flow regimes and parameters such as tc intensity terrain height and incident angle of the tc movement toward the topography all the presented simulated storms experience southward track deflection prior to landfall different from the mechanism related to the channeling effect induced low level northerly jet as suggested in previous studies this study indicates the leading role of the northerly asymmetric flow in the midtroposphere in causing the southward deflection of the simulated tc tracks the midtropospheric northerly asymmetric

on the upstream track deflection of tropical cyclones past a mountain range idealized experiments abstractupstream track deflection of a propagating cyclonic vortex past an isolated mountain range is investigated by using idealized simulations with both boundary layer turbulent mixing and cloud effects the westbound vortex past a shorter mountain range may experience an earlier northward deflection prior to landfall the vortex then takes a sudden southward turn as it gets closer to the mountain range in response to the effects of the stronger northerly wind over the mountain due to the effects of channeling flow the vortex may deflect southward when approaching a longer mountain range and then rebound northward upstream of the mountain ridge the southward deflection is primarily induced by the convergence stretching effect due to the combination of the speedy core at the southwestern flank of the vortex and a northerly jet between the vortex and the mountain the vortex then rebounds northward to pass over the mountain as the speedy core rotates counterclockwise to the eastern flank of the vort

accretion of japanese island arcs and implications for the origin of archean greenstone belts the present day region of arc arc collision between the izu bonin arc and mainland japan honshu arc in the western pacific called the izu collision zone or icz provides a useful kinematic model for the development of many archean greenstone belts the compositional assemblage thermal structure and structural style of the crust in the icz are very similar to those inferred for many archean greenstone belts in both cases thick young and flaky arc crust with a high heat flux is in collision with another crustal block the icz has resulted in the imbrication of very thick slices of crust and associated sediments juxtaposed against older accretionary prisms many archean greenstone belts show similar geological features and we suggest that the incremental imbrication of the crust was a common tectonic style in some archean convergent margins

a numerical study on the combined effect of midlatitude and low latitude systems on the abrupt track deflection of typhoon megi 2010 abstractin 2010 supertyphoon megi experienced an abrupt track deflection in the south china sea scs after traversing luzon island to reveal the physical processes responsible for the timing and location of the sudden track deflection the potential vorticity pv diagnosis and numerical simulations with initial strength perturbations are applied to investigate the individual and combined effects of environmental systems on megi s motion based on the steering flow theory results indicate that megi s northward track deflection was mainly determined by the effect of the midlatitude circulation or rather the break of the high pressure belt joined by the continental high ch and the pacific subtropical high sh the retraction of ch played a particularly critical role in the break of the high pressure belt making it the most important feature of the midlatitude circulation to determine megi s deflection in addition a small low latitude anticyclone sa southeast of megi was crucial in affecting the

oxygen isotope ratios of archean plutonic zircons from granite greenstone belts of the superior province indicator of magmatic source zircons commonly preserve primary magmatic oxygen isotope ratios even through high grade metamorphic events unlike quartz which more readily loses its primary 18o value by subsolidus exchange intrusive bodies from the superior province canada have an average 18o zircon of 5 8 0 6 n 59 rocks those from granite greenstone belts have an average 18o zrc 5 8 0 6 n 55 in contrast to those from metasedimentary belts that average 18o zrc 6 7 0 2 n 4 the 18o zircon values from granite greenstone belts indicate a maximum allowable input of 14 supracrustal high 18o material into archean magmas of the superior province relative to mantle 18o values igneous bodies of the superior province have been separated into two groups based on geochemistry unenriched plutons and sanukitoids magmatic oxygen isotope ratios inferred from these zircons indicate up to a subtle but significant division of 1 between the two geochemical sets of rocks this distinction is apparent only in the 18o zrc and not in more commonly analyzed less refractory minerals such as quartz and feldspar oxygen isotope data correlate with geochemical modeling of sanukitoids the average 18o zrc for sanukitoids is 6 4 0 2 in comparison to 5 5 0 4 for unenriched plutons there is almost no overlap in values the elevation of sanukitoid 18o zrc indicates input from a high 18o source such as fluids from the subducting oceanic crust melts of subducted sediments or continental crust all of the plutons analyzed in this study have been dated by u pb zircon techniques and the combination of u pb ages and 18o zrc indicates little variability of 18o versus age during archean plutonism in the superior province therefore recycling of sediments and other high 18o sources was not a dominant process during crustal growth from 3003 to 2670 ma in the superior province

temporal changes of the primary circulation in tropical cyclones abstract more than 900 radial profiles of in situ aircraft observations collected in 19 atlantic hurricanes and tropical storms over 13 years confirm that the usual mechanism of tropical cyclone intensification involves contracting maxima of the axisymmetric swirling wind radar shows that annuli of convective echoes accompany the wind maxima these features called convective rings exist and move inward because latent heat released in the rings leads to descent adiabatic warming and rapid isobaric height falls in the area they enclose the radial change in rate of isobaric height fall is concentrated at the inner edge of the wind maximum causing the gradient wind to increase there and the maximum to contract vigorous convection organized in rings invariably causes well defined inward moving wind maxima but when convection is weak the rings are also weak or even absent in this case the swirling wind may be nearly constant with radius and change slowly in time hurricanes that have a single vigor

polyphase deformation and crustal evolution in the pipestone lake area of the archean wabigoon subprovince superior province canada archean supracrustal rocks in the western wabigoon subprovince superior province canadian shield have undergone four phases of deformation d1 d4 d1 confined to the oldest rocks includes a large refolded reclined isoclinal anticline f1 with moderately developed axial planar cleavage s1 rocks affected by d1 are overlain by a regional unconformity d2 includes post unconformity steeply plunging north northeast south southwest striking isoclinal folds f2 that are approximately coaxial with f1 but have contorted the f1 axial trace d3 is represented by east west striking steeply plunging folds at various scales f3 which occur mainly in rocks near the regional manitou stretch pipestone lake shear zone also interpreted to be a d3 structure d4 is represented by pervasive cleavage s4 locally penetrative but mainly spaced including crenulation cleavage fractures small faults and brittle ductile shears s4 is parallel to the margin of the jackfish lake pluton d1 d3 are ascribed to convergence of the wabigoon subprovince with adjacent subprovinces ending with formation of the manitou stretch pipestone lake shear zone as a presently steep thrust and oblique ramp structure d4 is the result of either diapiric emplacement of the jackfish lake pluton or marginal strain intensification due to the rigidity of the older ash bay dome during late north south compression previously available zircon u pb geochronology provides a maximum age for d1 of 2728 ma and an approximate age for d4 of 2698 ma the unconformity developed between d1 and d2 2725 2713 ma