importance of mean state in simulating different types of el nino revealed by snu coupled gcms abstract recent studies suggest that there are two types of el nino events which differ in terms of zonal distribution of sea surface temperature sst anomalies in this study we investigate mechanisms in controlling simulation of two types of el nino using three different versions of the seoul national university snu air sea coupled general circulation models the occurrences of two types of el nino are related to the simulated climatological sst over the eastern pacific it is found that a model with relatively less canonical or frequent warm pool or central pacific el nino occurrence has colder cold tongue in the equatorial central pacific due to the cold mean sst and associated dryness over the eastern pacific positive el nino related sst anomalies over the eastern pacific cannot trigger local convection effectively the eastern pacific dryness leads to the confinement of anomalous convective activity in the western pacific which results in weak canonical el nino and reduction in canonical el nino occurrence instead the confined convective activity in the western pacific can lead to strong sst anomalies over western central pacific through local air sea interaction which can increase warm pool wp el nino occurrence in addition we found that mean equatorial thermocline structure is also related to the occurrences of wp el nino and canonical el nino that is a model with deep thermocline depth simulates less wp el nino occurrence consistent with yeh et al 2009

understanding the responses of sea surface temperature to the two different types of el nino in the western north pacific abstract in this study we examine the physical processes of the response of sea surface temperature sst in the western north pacific to the two different types of el nino the central pacific el nino and the eastern pacific el nino while a center of anomalous warm sst is observed in the eastern tropical pacific in the case of the eastern pacific el nino it is located in the central tropical pacific for the central pacific el nino we investigate the detailed sst response in the kuroshio extension region where the anomalous sst is warm cool in the central pacific el nino eastern pacific el nino during the boreal fall and winter we diagnose the sst tendency to identify the roles of the surface net heat fluxes and ekman transport during the fall and winter the atmospheric teleconnections over the north pacific are quite different between the two types of el nino which might be due to changes in atmospheric diabatic forcing in relation to rainfall in the tropical pacific our results suggest that the physical processes which are responsible for the western north pacific sst in response to the two different types of el nino are basically similar that is ekman heat transport plays a key role in warming and cooling of the sst anomalies in the kuroshio extension region in the central pacific el nino and eastern pacific el nino respectively in contrast the net surface heat fluxes act to weaken the sst anomalies this result indicates that changes in the anomalous atmospheric circulation over the north pacific which is directly associated with ekman currents at the upper levels are important to determine the responses of sst in the kuroshio extension region to the two types of el nino

a three dimensional model of the mean and seasonal circulation of the gulf of california 1 the mean and seasonal circulation of the gulf of california is simulated with a three dimensional numerical model forced by the pacific ocean through specifying the sea level the temperature and the salinity fields at its entrance at the sea surface the wind and the heat and freshwater fluxes are specified the model reproduces the observed mean and seasonal variability of sea level of heat and salt balances and the sea surface temperature sst climatology it also reproduces the general surface circulation of the northern gulf which consists of a seasonally reversing basin wide gyre it is found that tides and heat fluxes are both indispensable to reproduce the spatial structure and temporal evolution of the sst tides provide the mixing to upwell the cooler subsurface waters in the large islands area and the heating from the surface raises the sst the general circulation of the southern part of the gulf is due to the wind and the pacific forcing in the ekman layer two periods of anticyclonic circulation and one cyclonic per year occur below this layer two cyclonic periods develop in the northern part the tides play an important role in producing mean residual currents and both tides and winds compete against the pacific forcing to produce a cyclonic and anticyclonic circulation once a year contrary to conclusions of previous studies the thermohaline circulation is found to be unimportant in the gulf

regolith production and chemical weathering of granitic rocks in central chile abstract we have evaluated the long term chemical and physical weathering mass balance of an anomalously thick saprolite profile 30 m thickness developed in granitic rocks near curacavi coastal range of central chile the results of geochemical mass balance calculations for the regolith profile point to a moderate depletion for na and sr due to the plagioclase dissolution and precipitation of kaolinite furthermore silicon shows a predominantly constant behaviour along the profile that is indicative of incongruent weathering of plagioclase strongly suggesting that quartz dissolution conditions are not reached in addition low depletion of k mg ca rb and ba in the saprolite indicates a low degree of k feldspar biotite and hornblende weathering denudation rates calculated using cosmogenic 10be data range from 20 to 70 m ma if the saprolite thickness has reached a steady state condition the reported denudation rates lead to mineral residence times in the upper part of the saprolite profile of about 0 5 to 1 8 ma with such duration a higher weathering degree than observed at curacavi would be expected this apparent contradiction might be explained if all of the weatherable plagioclase has been dissolved under the present day precipitation and temperature conditions of the curacavi region therefore we propose that the curacavi profile could be in local equilibrium with respect to the weatherable fraction of plagioclase a local equilibrium regime may be reached when the overall degree of depletion is small in a weathering profile uniform elemental distribution and low weathering degree in the thick weathering profile at curacavi defy the traditional notion of weathering regimes and reveal the importance of exploratory studies in order to better understand weathering process in mediterranean and semi arid climate regions

tidal and atmospheric forcing of the upper ocean in the gulf of california 1 sea surface temperature variability two years of satellite infrared imagery 1984 1986 are used to examine the sea surface temperature sst variability in the northern gulf of california empirical orthogonal functions eofs of the temporal and spatial sst variance for 20 monthly mean images show that the dominant sst patterns are generated by spatially varying tidal mixing in the presence of seasonal heating and cooling these patterns are modified in the fall and winter when shelf temperatures south of tiburon island cool in response to upwelling favorable winds these same winds bring cold dry air from off the continental united states causing local cooling of the shallow northern shelf during the rest of the year the broad shallow shelves are warmer than offshore the seasonally reversing temperature patterns are consistent with recent hydrographic observations which show a cyclonic surface circulation in the summer and a weaker anticyclonic circulation during the rest of the year atmospheric forcing of the northern gulf appears to occur over large spatial scales area averaged ssts for the guaymas basin island region and northern basin show significant fluctuations which are highly correlated these fluctuations in sst correspond to similar fluctuations in the air temperature which are related to synoptic weather events over the gulf during periods of particularly low wind speeds the air temperature over the gulf increases dramatically by afternoon intense heating of the sea surface results in the appearance of warm sst anomalies in the satellite data these ssts are approximately 2 c warmer than surrounding ssts and most likely occur as a result of a spatially varying wind field a regression analysis of the sst relative to the fortnightly tidal range shows that tidal mixing occurs over the sills in the island region as well as on the shallow norther shelf mixing over the sills however occurs as a result of large breaking internal waves or internal hydraulic jumps which mix water over the upper 300 500 m this mixing pumps heat away from the surface deep into the water column there by maintaining the cool ssts since mixing occurs over greater depths in the island region the temperatures there are much colder than those generated by tidal mixing on the shallow shelves resulting in the persistent pool of cool water evident in the satellite data this cooler water is mixed horizontally by the basin scale circulation lowering the ssts over much of the northern gulf these reduced ssts have a large impact on the surface heat flux by lowering the saturation vapor pressure of the air as a result the amount of heat lost to the atmosphere through the latent or evaporative heat flux is reduced this may explain why the gulf of california gains heat on an annual average rather than losing heat as occurs in the mediterranean and red seas where tidal mixing is not significant

observations of three dimensional radiative effects that influence modis cloud optical thickness retrievals abstract when cloud properties are retrieved from satellite observations current calculations apply one dimensional 1d theory to the three dimensional 3d world they consider only vertical processes and ignore horizontal interactions this paper proposes a novel approach that estimates 3d effects in cloud optical thickness retrievals the proposed method combines visible and thermal infrared images to see whether 3d radiative effects make clouds appear asymmetric that is whether cloud surfaces tilted toward the sun are systematically brighter than surfaces tilted away from it the observed asymmetries are then used to estimate 3d effects for 1 km size pixels as well as 50 km size areas initial results obtained for moderate resolution imaging spectroradiometer modis images reveal that 3d effects cause abundant uncertainties in the 1 km resolution 1d retrievals averaging over 50 km by 50 km areas greatly reduces the errors but does not remove them completely conservative estimates show that the m

on the three dimensional numerical modeling of the deep circulation around angel de la guarda island in the gulf of california a three dimensional nonlinear baroclinic model is used to model the circulation in the ballenas channel gulf of california mexico which was inferred from current meter observations over three sills that surround the area the suggested circulation consists of deep inflow that follows two paths the first one is a direct spill of water through san lorenzo sill into ballenas channel the second one a larger route that starts at san esteban sill then flows north of the island passing over tiburon and delfin basins and then turns to the south reaching the north ballenas channel sill and then spills into ballenas channel following the latter result a previous modeling effort to reproduce the circulation was partially obtained the long path was not reproduced and it was believed that finer horizontal resolution was needed in this work the bathymetric resolution was increased by a factor of three and the full path of this deep circulation is now obtained and corroborated

meteorologically forced subinertial flows through the strait of gibraltar the observed transport due to subinertial flows with periods ranging from days to a few months through the strait of gibraltar reaches values up to 106 m3 s 1 and is well correlated with atmospheric pressure fluctuations over the mediterranean sea this transport is barotropic and accounts for 84 of the variance observed at these frequencies a second mode accounts for 12 of the variance and is characterized by a node zero amplitude located at the mean depth of the interface between atlantic and mediterranean waters this baroclinic mode is modulated by the spring neap tidal cycle corresponding to an increased exchange of waters between atlantic and mediterranean at neap tides a simple model of the mediterranean which includes two basins and two straits indicates that the system has two resonant frequencies at periods of 1 2 and 5 6 days the 1 2 day resonance corresponds to the eastern and western basins oscillating through the strait of sicily while that at 5 6 days is the resonance of the mediterranean sea with the north atlantic ocean a good approximation to the observed flows is obtained when this model is forced with the most energetic mode of the atmospheric pressure over the eastern and the western mediterranean and a friction term is included to limit the flow through the strait of gibraltar restricting the flow through the strait of sicily does not improve the agreement between the model and the observations for the flows at gibraltar

view angle dependence of cloud optical thicknesses retrieved by moderate resolution imaging spectroradiometer modis 1 this study examines whether cloud inhomogeneity influences the view angle dependence of modis cloud optical thickness retrieval results the degree of cloud inhomogeneity is characterized through the local gradient in 11 m brightness temperature the analysis of liquid phase clouds in a 1 year long global data set of collection 4 modis data reveals that while optical thickness retrievals give remarkably consistent results for all view directions if clouds are homogeneous they give much higher values for oblique views than for overhead views if clouds are inhomogeneous and the sun is fairly oblique the mean optical thickness retrieved for the most inhomogeneous third of cloudy pixels is more than 40 higher for oblique views than for overhead views if the solar zenith angle exceeds 60 after considering a variety of possible scenarios the paper concludes that the most likely reason for the increase lies in three dimensional radiative interactions that are not considered in current one dimensional retrieval algorithms namely the radiative effect of cloud sides viewed at oblique angles seems to contribute most to the enhanced optical thickness values the results presented here will help understand and estimate cloud retrieval uncertainties related to cloud inhomogeneity and may eventually help correct for the observed view angle dependent biases

two overflows in the northern gulf of california 1 two overflows originating at sills in the northern gulf of california are marked by strong average downstream slopes of 17 and 4 near bottom stratification upstream of both sills is relatively strong but the near bottom water is very well mixed downstream of the sills the homogenization of a thick bottom layer downstream albeit close to the sills is indicative of very strong mixing waters in the downstream basins are well ventilated with relatively high oxygen concentrations these hydrographic patterns were observed during three different seasons time series of temperature salinity and potential density show that water flowing over the sills is essentially subsurface subtropical water from the pacific ocean the time series also indicate that water is nearly always denser at the sills compared to water in the downstream basins despite the two fold 800 m and more than three fold 1500 m increase in depth the long term more than a year average current at both sills is bottom intensified with maximum average speeds of 33 and 17 cm s there are also strong tidal currents at the sills although the subinertial currents near the bottom are quite persistent with nearly no flow reversals transports estimated exclusively with the mean flow are about 0 08 and 0 09 sv 1 sv 1 106 m3 s which agree well with previous estimates based on shorter time series and a lower vertical resolution these results indicate that the deep water at both downstream basins are renewed by these overflows which enter at sill depths 400 m and are capable of reaching the deepest part of both basins the overflows appear to be responsible for the main mechanisms that transform subsurface subtropical water into gulf of california water

thermohaline circulation in the gulf of california the gulf of california a narrow semienclosed sea is the only evaporative basin of the pacific ocean as a result of evaporative forcing salinities in the gulf are 1 to 2 higher than in the adjacent pacific at the same latitude this paper examines the thermohaline structure of the gulf and the means by which thermohaline exchange between the pacific and the gulf occurs over time scales of months to years in addition to evaporative forcing air sea heat fluxes and momentum fluxes are important to thermohaline circulation in the gulf from observations presented here it appears that the gulf gains heat from the atmosphere on an annual average unlike the mediterranean and red seas which have comparable evaporative forcing as a result outflow from the gulf tends to be less dense than inflow from the pacific winds over the gulf change direction with season blowing northward in summer and southward in winter this same seasonal pattern appears in near surface transports averaged across the gulf the thermohaline circulation then consists of outflow mostly between about 50 m and 250 m inflow mostly between 250 m and 500 m and a surface layer in which the direction of transport changes with seasonal changes in the large scale winds using hydrographic observations from a section across the central gulf total transport in or out of the northern gulf is estimated to be 0 9 sv heat gain from the atmosphere is estimated to be 20 to 50 w m 2 and evaporation is estimated to be 0 95 m yr 1 these estimates are annual averages based on cruises from several years seasonal variations in thermohaline structure in the gulf are also examined and found to dominate the variance in temperature and density in the top 500 m of the water column salinity has little seasonal variability but does exhibit more horizontal variablility than temperature or density major year to year variations in thermohaline structure may be attributable to el nino southern oscillation events

the effect of pedological conditions on the sources and sinks of silicon in the vertic planosols in south western ethiopia as a dynamic source and sink of elements the secondary si bearing solid phases in soil partly govern transfer of elements and pollutants terrestrial plants affect silicate mineral weathering and make si readily soluble through the formation of phytoliths a biogenic form of amorphous silica which return on topsoil through litterfall besides phytoliths other readily soluble si components such as pedogenic opal volcanic glass adsorbed si onto fe oxides and poorly crystalline aluminosilicates take part in the regulation of the si balance the aim of this paper is to assess the impact of pedological conditions on the sources of dissolved si and its dynamics in a vertic planosol characterized by contrasting bleached and vertic horizons the si containing readily soluble phases were quantified by specific extractions na2co3 sialk oxalate siox dcb sidcb and cacl2 sicacl2 performed on samples of the bleached and vertic horizons moreover amorphous silica asi from the soil including phytoliths and volcanic glass was extracted by gravimetric separation in the bleached horizon phytoliths are the main si bearing readily soluble phases of the silt sized fraction while si in the sand sized fraction is largely controlled by volcanic glass and feldspars the higher sicacl2 concentration and the significant increase of si al cacl2 ratios in soil solution of the vertic horizon attest for a marked difference in terms of si dynamics

internal waves in the gulf of california observations from a spaceborne radar pronounced signatures of internal waves were detected repeatedly in the gulf of california by the seasat synthetic aperture radar sar a series of nine images with exactly repeating ground coverage was used to study the temporal variability of the internal wave field in the area it was found that the number of observed wave groups was highly correlated with the strength of the local tides the maximum number occurred during spring tides and the minimum number occurred during neap tides indicating that the internal waves were tidally forced most of the wave activity was found to the north of 28 n where the tides were the strongest in the gulf the application of a simple nonlinear internal wave model to the observations indicated that the peak to peak amplitude of the observed waves was about 50 m with an uncertainty of a factor of 2 the estimated upper bound for the rate of the loss of tidal energy to internal waves was about 5 1015 erg s representing only 10 of the rate of the dissipation of the dominant m2 tide in the gulf

case study of inhomogeneous cloud parameter retrieval from modis data 1 cloud parameter retrieval of inhomogeneous and fractional clouds is performed for a stratocumulus scene observed by modis at a solar zenith angle near 60 the method is based on the use of neural network technique with multispectral and multiscale information it allows to retrieve six cloud parameters i e pixel means and standard deviations of optical thickness and effective radius fractional cloud cover and cloud top temperature retrieved cloud optical thickness and effective radius are compared to those retrieved with a classical method based on the homogeneous cloud assumption subpixel fractional cloud cover and optical thickness inhomogeneity are compared with their estimates obtained from 250m pixel observations this comparison shows a fairly good agreement the cloud top temperature appears also retrieved quite suitably

saprolite soil transformations in the piedmont and mountains of north carolina abstract in the piedmont and mountain provinces of north carolina average annual precipitation exceeds evapotranspiration soil solum thickness is usually 1 to 2 m saprolite thickness is variable but related to rock type and geomorphic position slow hydraulic conductivity in the zone between the soil and the saprolite appears to restrict vertical percolation of water thus slowing saprolite weathering on convex slopes in saprolite zones immediately above granitic gneiss often about 5 m below the surface halloysite gibbsite and x ray amorphous aluminosilicate clay are the initial secondary minerals formed halloysite contents increase upward in the saprolite apparently from resilication of gibbsite and the amorphous aluminosilicates in the upper zones of the saprolite the halloysite is recrystallized into kaolinite which is the predominant clay sized mineral in the soil over gabbro and metagabbro rocks the lower zones of the saprolite contain appreciable quantities of smectite vermiculite and where chlorite is present regularly interstratified chlorite smectite although these smectite minerals become partially interlayered with hydroxy aluminum in the overlying soil they p persist as a substantial component of the clay sized fraction saprolite thickness is less than over the granitic rocks increased run off and lateral through flow produced by low hydraulic conductives of smectite rich argillic horizons and convex hill slopes are believed to be responsible for the thin saprolite above mafic bedrock soils and saprolites from biotitic gneiss on upper sideslopes in the mountain physiographic province have mineralogical trends with depth similar to those found over the granitic gneisses of the piedmont gibbsite often constitutes as much as 30 of the clay and contents tend to increase in the deeper saprolite zones biotite sand which is common throughout the soil and saprolite alters to kaolinite sand under the acidic conditions of the saprolite sand sized mica appears resistant to weathering except where there is evidence of physical transport

impact of low denudation rates on soil chemical weathering intensity a multiproxy approach abstract quantifying the influence of denudation i e physical erosion and chemical weathering on soil weathering intensity is an important component for a comprehensive understanding of element biogeochemical cycles the relation between the weathering intensity and the denudation rate is not clear and requires further investigation in a variety of climatic and erosional settings here in the betic cordillera southern spain we assess the soil chemical weathering intensity with a multiproxy approach combining different indicators of chemical weathering of the soil the total reserve in bases trb the content in fe oxides the quartz and clay content the soil cation exchange capacity cec and the silicon si isotope composition of the clay sized fraction our multiproxy approach demonstrates that in this semi arid environment at low denudation rates an increasing denudation rate decreases the soil weathering intensity whereas si mobility remains limited our results converge with previous conclusions based on chemical mass balance methods in the same geological setting mass balance methods and particularly chemical depletion fractions cdf are based on the immobility of a refractory element commonly zirconium zr relative to major cations in soils interestingly our study suggests that a weathering index such as the trb may provide a useful complement to assess soil chemical weathering intensity in eroding landscapes where the application of chemical mass balances may be hampered by potential zr mobility in the soil or by heterogeneity of zr concentrations in the bedrock

tidal dissipation and stratification in the gulf of california the effect of tidal mixing upon the distribution of stratification and sea surface temperature sst in the gulf of california is studied by direct observation and by numerical modeling data from conductivity temperature depth surveys made in september and december of 1986 are used to describe the distribution of stratification and sst a vertically integrated finite differences numerical model was used to obtain the geographical distribution of available turbulent kinetic energy tke from the m2 tide the following three areas were found to be strongly affected by tidal mixing the shallow coastal area at the head of the gulf the shelf south of tiburon island and the area of the midgulf archipelago the first two are vertically well mixed and are therefore similar to other shelf sea frontal areas dissipation occurs all around the islands of the archipelago and the sills are foci of the most intense tidal dissipation stratification in this area was reduced with respect to the background but complete vertical mixing does not occur therefore the strong sst fronts that occur in this area do not mark the boundary between well mixed and stratified water the simpson hujiter criterion simpson and hunter 1974 for stratification and frontal position produced 2 75 crit 3 0 for the frontal position in the shallow northern gulf this value of crit is larger than in other shelf sea fronts which may be due to horizontal advection which is not included in the criterion we found that the effect of advection may be of the same order of magnitude as that of buoyancy flux in the area over the sills criti the available tke is not enough to produce complete mixing over the 400 m of water over the sills

mineralogy and genesis of planosols under a semi arid climate borborema plateau ne brazil abstract planosols such as those found on the borborema plateau ne brazil form an important class of moderately weathered soils that support subsistence agriculture in underdeveloped regions of africa asia and south america despite its socioeconomic importance the genesis of this soil class has not yet been fully elucidated this study was conducted with the aim of improving knowledge about the genesis of planosols under a semi arid climate three planosol profiles on the borborema plateau in ne brazil were collected classified and described morphologically and the main physical and chemical attributes the pedogenetic forms of iron oxides and the mineralogical compositions of the sand silt and clay fractions were determined the results indicate that a parent materials richer in feldspar and biotite favor the formation of planosols with a higher clay content b the dissolution of primary minerals and the formation of clay minerals known as the argillation process are fundamental for the genesis of bt horizons c depth drainage deficiency leads to hydromorphism an associated gray color and the formation of mottles and d monosialitization and bisialitization processes kaolinite formation and the formation of 2 1 clay minerals respectively prevail in planosols located within landscape positions that have good and poor drainage respectively in addition the present study shows that planosols under a semi arid climate can have a clay fraction consisting predominantly of kaolinite and mineralogical alteration pathways similar to those described in soils under an analogous climate and geology in northwest africa this refutes classical theories that soils with 2 1 clay minerals prevail in warmer and drier regions this study thus provides greater knowledge about the attributes of planosols in dry and poor regions and can be used as a reference in studies on the sustainable use and management of such soils

why does the ballenas channel have the coldest sst in the gulf of california 1 moored and hydrographic observations at the three most important sills in the northern gulf of california ngc are used to describe the circulation at the deepest san esteban se sill 600 m the mean along gulf flow is weak and outward toward the mouth of the gulf in the entire water column whereas the mean deep flow is inward and bottom intensified at the san lorenzo sl sill 400 m which controls the southern entrance to the ballenas channel bc however large tidal currents 1 m s during spring tides in the se sill drive a net inward bottom transport of 0 09 sv 1 sv 1 106 m3 s due to a tidal pumping process at the sl sill the net transport is also about 0 09 sv but here the mean flow contributes more than the tides and both are into the gulf at the northern bc sill which controls the northward entrance to the bc the mean near bottom flow is southward implying that the bottom water of this deep basin is renewed at both of its ends moreover the mean surface flow at both ends of the bc is out of the channel and hence the convergence at the bottom is compensated by a divergence at the surface generating a persistent upwelling 5 m day within the channel this circulation pattern primarily explains why the bc has the coldest sst and is one of the most biologically productive basins in the gulf of california

effect of granite crystal grain size on soil properties and pedogenic processes along a lithosequence this study generated new insight into the effect of bedrock grain sizes on pedogenesis under identical topographic and climatic environment the physico chemical and mineralogical properties of two adjacent typic dystrochrepts usda 1999 respectively developed from fine and coarse textured granites were compared this research study was performed in the morvan mountains france analysis of the two underlying bedrocks revealed similar chemical and mineralogical properties with the crystal grain size being the only parameter which differed in these soils bedrock played the key role in the particle size fraction distribution the main factor controlling water retention in the soils weathering reactions of clay minerals were more marked in the fine textured granite soil in this soil both clay mineral swelling and mica transformation into expansible phyllosilicates were greater compared to the coarse textured granite soil in the clay fraction of the fine textured granite soil there were smaller amounts of low crystallised fe and al minerals with higher carbon content in the topsoil as compared to the coarse granite soil the exchangeable cation analysis of the fine textured granite soil revealed a higher proportion of base saturation and a smaller proportion of altit than in coarse textured granite soil which could be explained by preferential leaching of al cations the decrease in exchangeable al the higher swelling of the smectitic layer and the smaller proportion of fe and al oxy hydroxides could be explained by the complexing acid conditions which increased mineral weathering and al leaching the higher water retention increased the time of contact between minerals and the soil solution and the higher carbon content in the topsoil could have enhanced the complexing acid conditions resume d auteur

seasonal surface connectivity in the gulf of california abstract a three dimensional numerical model is used to study seasonal connectivity in the gulf of california from the eulerian velocity fields of the model particle trajectories were calculated for the 12 months of the year using an advection diffusion scheme connectivity was quantified for twelve gulf provinces with different dynamic circulation characteristics being defined by the eulerian velocity field strong or weak coastal currents eddies and areas of mixing and exchange retention occurred for 9 12 months of the year in the upper gulf eddy and sonora regions of the northern gulf because of the gulf wide eddy circulation which implies high potential for the auto recruitment of larvae in this province high retention was also found on the peninsula side of the southern gulf in association with weaker residual currents again implying potential for self recruitment in contrast low retention was observed on the mainland side of the central and southern gulf from which particles are exported to many areas by the faster residual currents enhancing the potential for recruitment of distant coastal species empirical orthogonal function analyses revealed a strong annual and semiannual evolution in accordance with the strong seasonality of the gulf dynamics

the upper oceanic response to overflows a mechanism for the azores current abstract the oceanic response to overflows is explored using a two layer isopycnal model overflows enter the open ocean as dense gravity currents that flow along and down the continental slope while descending the slope overflows typically double their volume transport by entraining upper oceanic water the upper oceanic layer must balance this loss of mass and the resulting convergent flow produces significant vortex stretching overflows thus represent an intense and localized mass and vorticity forcing for the upper ocean in this study simulations show that the upper ocean responds to the overflow induced forcing by establishing topographic plumes that are aligned more or less along isobaths and that have a transport that is typically a few times larger than that of the overflows for the topographic plume driven by the mediterranean overflow the occurrence of eddies near cape st vincent portugal allows the topographic plume to flow across isobaths the modeled topographic plume circu

proterozoic history of the borborema province ne brazil correlations with neighboring cratons and pan african belts and implications for the evolution of western gondwana 1 geological and geochronological correlations between borborema province ne brazil and neighboring cratons and brasiliano pan african belts indicate that the amazonian west african and sao francisco congo cratons and the basement of the araguaia borborema nigerian and cameroon provinces were part of the atlantica supercontinent this continent was established at the end of the transamazonian eburnean cycle 2 0 ga and apart from ubiquitous taphrogenesis in the 1 8 1 7 ga interval remained largely unaffected for the following 1 ga around 1 ga an important magmatic event in borborema province correlates with rifting episodes and anorogenic magmatism in the sao francisco congo and amazonian cratons these events are interpreted as failed attempts to break up atlantica which at this time may have been part of the larger rodinia supercontinent renewed extensional conditions in borborema province during the middle and late neoproterozoic are attributed to far field stresses transmitted to the interior of atlantica by outwardly dipping subduction zones that encircled its northern present day coordinates portion the rarity of petrotectonic assemblages typical of subduction zone environments indicates that extension did not evolve enough to form large oceans basins and thus that the borborema province essentially includes reworked intracontinental domains regional deformation and metamorphism starting at 650 640 ma and shear zone development beginning at 590 595 ma were continuously developed through time and were synchronous throughout most of the borborema araguaia cameroon and nigerian provinces postorogenic conditions were reached 540 530 myr ago while active deformation was still occurring in other belts that accreted around atlantica to form western gondwana

summer generation of the southern gulf of california eddy train 1 ocean color and sea surface temperature satellite observations show the existence of a series of anticyclonic eddies along the axis of the southern gulf of california sgoc to investigate the summer generation of these eddies a regional version of the hybrid coordinate ocean model hycom has been configured for the goc and has been nested inside the global model a suite of experiments using the nested goc model was developed and used to isolate the effects of the local wind and the effects of the oceanic remote forcing on the generation of the sgoc eddies the results indicate that the local wind is not essential for the generation of these eddies rather it is the oceanic remote forcing in the sgoc the monthly variability of the currents and sea surface height is mainly due to the deterministic near coastal poleward eastern boundary currents pebc the interaction of the pebc with the topographic irregularities the capes at topolobampo and cabo lobos and the ridges extending offshore from the entrance of the san lorenzo and sinaloa rivers generates the sgoc eddies the northward upper ocean transport induced by the pebc includes two maximums one in may june and the other in december during the summers of 1999 and 2004 the pebc were intensified by the arrival of equatorially originated downwelling coastally trapped waves ctws which contributed to the generation of the sgoc eddies the summer 2004 ctw increased the northward upper ocean transport by 2 sv this particular ctw was measured by several tide gauges located along the coast

microscopic features of quartz and clay particles from fault gouges and infilled fractures in granite discriminating between active and inactive faulting abstract to assist in identifying faults that have a significant potential for displacement at or near the ground surface we carried out in depth investigations on fault gouges and a fracture infilled with clay clay vein in the kojaku granite on the tsuruga peninsula central japan we sampled several fault gouges at different stages of evolutions and clay rich infilling of a fracture with no evidence of offset based on our field observations gouge in an active fault is characterized by 1 stacked layers of different colors made up of comminuted fragments and clays and 2 injection of the fragments and clays from the gouge into the surrounding rocks indicating an accumulation of seismic induced shearing our thin section observations and x ray diffraction analyses show that all our samples are similar in the degree of fragmentation and mineral composition and because of this our study became focused mainly on microscopic features using laser diffraction particle size analysis scanning electron microscopy sem and transmission electron microscopy tem we identified the mineralogical and textural characteristics of the samples in order to improve our ability to discriminate between active and inactive faulting particle size distribution analysis showed that the gouge in the active fault contains the greatest abundance of finer particles due to multiple slip events which contrasts with the clay rich infilling of a fracture sem examination of the quartz particles showed that the gouge in the active fault contains more particles that have retained sharp and smooth crystal surfaces formed by fracturing than do either the gouges in minor faults that show no evidence of recent shear or the clay rich infilling of a fracture in contrast tem observations of very fine clay minerals approximately

neural network retrieval of cloud parameters of inhomogeneous clouds from multispectral and multiscale radiance data feasibility study 1 in this paper we investigated the feasibility of retrieving cloud parameters of inhomogeneous and fractional clouds from simulated multispectral and multiscale radiometric data by using mapping neural networks a radiometric database prepared for neural network training consists of area averaged radiance data for two pixel scales i e 1 km 1 km and 0 25 km 0 25 km pixels respectively the cloud parameter retrieval assumes a vertically uniform inhomogeneous and fractional cloud defined with 6 parameters i e the mean and standard deviation of optical thickness the mean and standard deviation of effective radius the fractional cloud cover and the cloud top temperature all defined at a scale of cloud parameter retrieval the retrieval procedure comprises two separate steps the first one is relative to the angular interpolation and correction of radiance data surface reflection and thermal emission contribution the second step concerns the cloud parameter retrieval as such from interpolated and corrected radiance data the input vector to the retrieval mnns consists of 8 radiometric data in addition to a number of necessary ancillary data such as surface temperature and ground albedo the 8 radiometric data are 5 area averaged radiances over 1 km 1 km pixel and 3 standard deviations of radiance over 1 km 1 km pixel estimated from 0 25 km 0 25 km pixel radiances after evaluating the performance of the neural networks trained for each step we tested the whole retrieval procedure for three types of inhomogeneous and fractional clouds flat top bounded cascade clouds and flat top and non flat top gaussian process clouds all the cloud parameters of these clouds can be retrieved with reasonable accuracy in spite of the fact that the mean and standard deviation of optical thickness of non flat top clouds exhibit some dispersion the inclusion of 0 25 km 0 25 km pixel radiance data as input vector components improved significantly the performance of the cloud parameter retrieval finally we analyzed the consequences of some simplifying assumptions on the retrieved cloud parameters and discussed the perspectives of the cloud parameter retrieval based on the neural networks

surface heat flux in the northern gulf of california recent coastal meteorological data 1979 1986 are used to evaluate the seasonal cycle of surface heat fluxes in the northern gulf of california although net heat loss occurs from october to january the annual mean of the net surface heat flux was found to be into the sea 69 w m 2 near the coast and 83 w m 2 offshore with a mean evaporation rate 0 9 m yr 1 these results require an oceanic export of heat and salt out of the northern gulf to achieve a balance and imply that the annual mean thermohaline circulation must have an inflowing component at depth thus enriching the central and northern parts of the gulf these results differ from previous meteorological estimates which suggested a net surface heat loss but confirm those based on hydrographic data

the lower atmosphere over the gulf of california automated meteorological observations at coastal and island stations instrumented aircraft flights and coastal soundings were made between july 1983 and june 1985 to define the variations of the lower atmosphere over the northern half of the gulf of california during the two important climatic seasons the mid latitude winter and the subtropical summer a marine layer is well defined over water during both seasons but dissipates within a few kilometers inland the winter large scale pressure field is dominated by the great basin high over the southwestern united states modulated by upper level synoptic activity it causes 3 to 6 days events of northwesterly winds 8 12 m s 1 directed along the gulf s axis which are coherent over basin scales and bring cool dry desert air over the gulf the vertical scale of these winds is 700 1000 m over land on the western side of the gulf close to the height of the baja california mountains but only 100 400 m over water defined by the wintertime inversion cross gulf winds related to topographic effects during upper level trough passages over baja california are particularly intense in the northwestern portion of the gulf the winter marine layer is defined by a 1 to 4 5 c temperature inversion and a dew point temperature of 6 11 c a moisture content of 6 8 g kg 1 weak subsidence reduces dew point values to 4 c above the inversion winter winds above the marine layer are coherent 0 8 across the width of the gulf the summer large scale pressure field is dominated by a thermal low over the southwestern united states and drives weak 2 5 m s 1 southeasterly winds also directed primarily along the gulf which are less spatially uniform than winter winds air temperature and moisture content are rather constant and topographic effects are absent the summer marine layer is on the order of 200 300 m thick with dew point temperatures of 26 28 c 21 24 g kg 1 and capped by a weak temperature inversion 1 2 c over water aloft the dew point temperature is 17 21 c and winds are weak and uncorrelated across the width of the gulf during june and early july 1984 four week long pulses of southeasterly winds 10 m s 1 support the existence reported previously of moisture surges from the gulf into the sonoran desert a dynamical analysis of subdiurnal motions shows that the cross gulf momentum balance is geostrophic the along gulf balance is ageostrophic with the along gulf pressure gradient opposed by friction at the surface these results are consistent with a scale analysis of the equations of motion in the marine layer over the gulf of california

sill processes related to deep water renewal in a fjord observations of the gravitational circulation over the sill at the entrance to puget sound indicate a fortnightly modulation of the two layer flow with a corresponding variation in stratification gravitational circulation and stratification reach a maximum during neap tides and a minimum during spring tides the modulation appears to be a function of the turbulence generation by tidal flow over the sill which varies as a function of tidal amplitude the enhanced gravitational circulation during neap tides augments the flux of dense water across the sill region and episodes of bottom water renewal in puget sound result intrusions of dense water in the main basin of the sound show a fortnightly periodicity with a phase lag appropriate for the propagation of an internal bore from the sill region commencing at the neap tide observations indicate that the intrusions take the form of gravity currents propagating at approximately 20 cm s 1 down the main basin the detailed dynamics of the turbulent mixing processes that modulate the onset of inflow were not resolved in this study but the integrated effect of tidal mixing on the low frequency circulation is clearly demonstrated

genesis of two planosols in the massif central france abstract two planosols developed on gravelly quaternary sediments of the river allier in the limagne rift valley massif central france were studied parent material contained in addition to a granitic component large amounts of volcanic particles morphological chemical mineralogical and physical properties of both profiles were investigated to indicate some of the changes which have taken place during pedogenesis both profiles were characterized by pronounced textural contrasts between sandy a and e horizons and clayey b horizons soil formation rather than a transient depositional environment is thought to be responsible for this marked textural change clear dissolution features of all mineral grains except quartz and increasing amounts of volcanic fragments with depth suggested weathering increasing ratios of mobile basic cations to tio 2 with increasing depth corroborated this observation the presence of non laminated isotropic and anisotropic limpid clay coatings were also evidence of in situ mineral weathering in both profiles kaolinite predominated as clay mineral and increased towards the surface micromorphological observations of microlaminated dusty and impure clay coatings in b horizons of both profiles were clear signs of clay illuviation bulk densities were high in lower e horizons and upper b horizons field observations and micromorphological data showed clear signs of periglacial features the combination of pedogenic and periglacial processes has apparently lead to a considerable compaction abundant cemented iron and manganese features predominantly occurring in e horizons suggested surface water gleying micromorphological observations of illuviation coatings in b horizons and of fine material in a and e horizons demonstrated grainy aspects suggesting ferrolysis

a note on why does the ballenas channel have the coldest sst in the gulf of california 1 a three dimensional nonlinear baroclinic model is used to verify the circulation in the ballenas channel gulf of california deduced from observations which concluded that the cold sst of the channel is due to the deep inflow of water over the sills at both ends of the channel this convergence at depth would lead to upwelling divergence in the upper layers and to surface outflow through both ends here it is reported that the deep flow from the south does enters into the channel but not that from the north the deep inflow returns back mainly along the surface through the same southern end of the channel and a small fraction flows out through the northern end of the channel and between angel de la guarda and san lorenzo islands the bottom flow that enters through san esteban sill does not go all the way along tiburon and delfin basins and into ballenas channel through the northern sill instead it returns in the intermediate and surface layers after mixing in those basins

mechanisms of granite alteration into grus karkonosze granite sw poland abstract granitic gruses are usually considered as a product of deep weathering but the influence of hydrothermal fluids was also noticed in this work a wide range of mineralogical and chemical methods performed on 43 samples from three representative outcrops and a reference site is used to determine the influence of hydrothermal and weathering fluids on the development of granitic gruses from the coarse grained karkonosze granite four types of altered granites have been distinguished including compact and friable granite typical grus and localized heavy altered zones mineralogical observations such as complete albitization of plagioclase and crystallization of secondary quartz revealed an important role of hydrothermal alteration at the early stage of grusification the origin of smectite and alteration of biotite into muscovite are likely to be connected with circulation of hydrothermal fluids too grusification sensu stricto was primarily caused by vermiculitization of biotite which resulted in volumetric expansion and the development of transmineral microcracks with non accordant pore surfaces thus it requires hydrothermal alteration to be relatively minor confined to postmagmatic changes since more advanced alteration of biotite into muscovite rather than vermiculite arrests further development of microcracks and leads to the development of friable granite

surface circulation in the gulf of california in summer from surface drifters and satellite images 2004 2006 surface drifters released in the gulf of california between june 2004 and august 2006 are used to describe the surface circulation in late spring and summer in the june to september mean there was a poleward coastal current on the shelf and slope of the mainland side of the gulf with mean speed 0 3 m s it reached the northern gulf and joined the cyclonic circulation typical of this zone in summer in the western half of the southern gulf the drifters presented recirculating currents that are due to mesoscale eddies that appear to dominate the surface circulation in summer in june 2004 the coastal current presented an enhancement event with mean speed around 0 60 m s and maximum 0 80 m s it took 20 days for a particular drifter to travel the 1000 km from the gulf entrance to the head this strengthening of the coastal current was apparent in chlorophyll a and sst satellite images the drifters following closely the intrusion of warm chlorophyll poor surface water from outside the gulf the drifters and the satellite images suggest that the current enhancement event lasted less than a month this mesoscale event was linked with a mesoscale remote forcing in the tropical pacific coast and with a mesoscale local forcing of the wind these events seem to occur every year and are probably important in carrying organisms and properties from the entrance to the whole length of the gulf

the deepwater exchange cycle in indian arm british columbia abstract a silled fjord on the british columbia coast indian arm was used to study the exchange processes controlling deepwater exchange in fjords bottom water renewal took place during the winter of 1984 85 hydraulic control of the exchange is exerted over the long sill which restricts access to the fjord the maximum density at the sill occurs during neap tides no distinct peaks in the velocity at the sill are observed during periods of inflow reduced vertical mixing over the long sill during periods of neap tides sets the timing of the bottom water exchange during each inflow over the 1984 85 winter about 20 of the water in the fjord was replaced these exchanges occurred over periods of 5 10 days between the exchange years diffusion of the water in the basin is important in conditioning the water for the next exchange event the vertical diffusion coefficient k t was determined from an analysis of the salinity data and was found to be related to the buoyancy frequency n by the relationship k v n 1 6

gneiss saprolite weathering and soil genesis along an east west regolith sequence ne brazil abstract the pressure to increase biomass production worldwide has pushed the boundaries of agricultural lands towards fragile soils this process is particularly intense in pernambuco state ne brazil pernambuco features a moisture gradient with soils developed from similar gneisses resistant structures within the rock influenced the internal movement and distribution of water consequently influencing regolith genesis this paper presents the mineralogical characteristics of three regolith profiles with shallow soils here assumed to be soils in which the top of the cr horizon is at a depth of 1 5 m or less along a transect at 8 s and discusses their weathering and pedogenetic processes samples were investigated via optical microscopy and scanning electron microscopy sem x ray diffraction xrd and total chemical analysis by inductively coupled plasma atomic emission spectrometry icp aes the presence of weathering resistant quartz veins and planes in the rock structure played a central role in controlling the water dynamics and the advancement of the weathering front therefore desilication was dominantly controlled by the pore network hence the weathering indexes did not differ appreciably among the climatic zones and both 1 1 and 2 1 type clays were found in all profiles although the amount of clay minerals that formed and the degree of dissolution of the primary minerals varied among the climate types from an agricultural perspective the thinness of these soil profiles and the presence of leucocratic layers are the main drawbacks of the regoliths whereas the capacity to supply plant nutrients via primary mineral dissolution near the root zone can be an advantage

an analysis of errors in sea surface temperature in a series of infrared images from noaa 6 as part of the coastal ocean dynamics experiment 58 infrared satellite images were analyzed for the magnitude and source of their errors in predicting sea surface temperature comparisons with near surface thermistors on moorings and differences between images from consecutive days showed that a two channel atmospheric correction using the 3 7 m and the 11 m channels was ineffective in reducing errors large systematic errors which have the form of a constant over an image were found in both channels a simple viewing angle correction reduced fluctuations in the area mean 11 m channel temperature from 0 74 to 0 45 c a satisfactory correction could not be found for the larger fluctuations in the 3 7 m channel which appears to be degraded by reflected or scattered solar radiation by taking account of the known dependence of atmospheric effects on viewing angle geometry it was possible to isolate the primary causes of error to estimate typical magnitudes and to correct for them the 11 m channel temperature error from the northern california atmosphere was found to be nearly constant in time over a 100 day period but to vary slowly with distance from the coast

silicon isotopes and the tracing of desilication in volcanic soil weathering sequences guadeloupe abstract silicon si stable isotopes have the potential to become a useful weathering proxy given that light si isotopes are preferentially incorporated into secondary clay minerals here we investigate how si depletion in soils and associated clay mineralogy influence the si isotope fractionation associated with clay mineral formation we report 30 si compositions in bulk soils and clay fractions relative to their parent andesite in three soil weathering sequences from guadeloupe that were formed under contrasting climatic conditions strongly desilicated soils containing kaolinite that formed in wet areas high precipitation are compared with less desilicated soils containing smectite formed in drier conditions low precipitation clay fractions are isotopically lighter than the parent andesite 30 si 0 23 and increasingly lighter with si depletion in soils which supports the view that the si isotope composition in secondary clay fractions is controlled by the degree of soil desilication it is shown that the si isotope fractionation factor between the parent silicate material and the secondary clay minerals is smaller for si rich secondary clay minerals such as smectite and larger for si poor secondary clay minerals such as kaolinite this study provides new insights to better define si isotopes as a proxy for environmental conditions for clay neoformation

water mass formation in the gulf of california the gulf of california is a long narrow marginal sea lying between the baja california peninsula and the mainland of mexico air sea fluxes of heat and moisture in the gulf are enhanced because of geographical isolation from the pacific provided by the mountainous baja california peninsula in the northern gulf annual evaporation rates are about 1 m y 1 unlike most evaporative basins however the gulf gains heat from the atmosphere at an annual average rate of 20 to 80 w m 2 bray 1988 given the unusual air sea forcing of the gulf what form or forms should water mass formation take the annual moisture loss and heat gain require that high salinity surface water be transported downward to an intermediate depth and that cold fresh inflow be transported upward to an intermediate depth this is accomplished through several mechanisms 1 winter convection this occurs only in a limited geographical region the wagner basin of the far northern gulf except in el nino southern oscillation years when convection appears to be more widespread 2 dispersion of convected water in small eddylike features this occurs within a large scale southward transport possibly driven by the large scale density gradient associated with atmospheric fluxes 3 an anticyclonic circulation in the northern gulf this is found south of the convection region and transports high salinity water off the shallow shelves and to substantial depths where it may mix with water of central gulf origin 4 tidal mixing most of the energy available for mixing in the northern gulf derives from the tides in particular tidal mixing over the sill in the island region is responsible for the substantial reduction in salinity of northern gulf waters as they enter the central gulf

shelf circulation in the gulf of california a description of the variability the first long term measurements 1983 1984 of winds temperature bottom pressure and currents made in the gulf of california are used to describe the dynamically important spatial and temporal scales and to compare and contrast the shelf circulation on opposite sides of the guaymas basin in addition a qualitative assessment of possible forcing mechanisms of gulf shelf circulation and an account of an energetic coastal trapped wave event are presented winds over the gulf are weak and variable with maximum wind speeds of 10 15 m s and sustained wind events of less than a week low frequency 3 cpd fluctuations in the dominant along gulf component of the wind field which are largely coherent over the study area are directed upgulf during summer and downgulf for the remainder of the year low frequency winds are not significantly correlated 95 confidence level with currents temperature and pressure in part because of weak local winds and nonlocally forced coastal trapped waves on longer time scales seasonal upwelling on both sides of the gulf and guaymas basin mean currents are related to local winds low frequency current fluctuations on the two facing shelf regions guaymas on the mexican mainland and santa rosalia on the baja california peninsula are not significantly correlated along gulf currents in the basin however are negatively correlated with alongshelf currents at guaymas 0 54 due to sporadically occurring eddylike features and santa rosalia 0 61 due to seasonal flow patterns low frequency fluctuations on the mainland shelf are significantly correlated during the summer e g 0 67 in temperature between topolobampo and guaymas separation of 375 km such that topolobampo leads guaymas by approximately 1 5 days this lagged signal is associated with coastal trapped waves that are generated by tropical storms and hurricanes south of the gulf and propagate poleward along the mainland shelf at speeds of 200 250 km day near guaymas current speeds of approximately 50 cm s were measured at the 100 m isobath on the mainland shelf during an event with a 20 cm coastal sea level rise the offshore decay of these waves is of the order of 50 km on the guaymas shelf low frequency temperature or equivalently density and sea level fluctuations are correlated 0 78 such that a 10 cm rise in sea level corresponds to a 20 m drop in isotherm depths over much of the water column this sea surface isotherm relationship is such that the amplitude of pressure fluctuations decays rapidly with depth e folding scale 160 m a similar relationship is only weakly apparent correlation 0 39 on the santa rosalia shelf cross gulf geostrophy is observed with 35 of the along gulf current averaged across the gulf related to dp dx measured between guaymas and santa rosalia on the guaymas and santa rosalia shelves dp dx measured across each shelf explains approximately 20 of the variability in alongshelf currents in the alongshelf momentum balance dp dy accounts for approximately 40 of the low frequency variability in dv dt at the guaymas shelf break consistent with the dynamics of freely propagating coastal trapped waves the same balance is only weakly apparent 10 of variance explained at santa rosalia at higher frequencies temperature fluctuations at guaymas are coherent and in phase to 200 m depth coherent 0 74 with the alongshelf near surface current at the shelf break m8 and exhibit a spring neap modulation consistent with internal tides

satellite derived sea surface temperature variability off california during the upwelling season abstract an empirical orthogonal function analysis of an advanced very high resolution radiometer sea surface temperature data set encompassing the spring summer period during 1991 1993 was used to examine patterns of temperature variability off northern and central california this analysis decomposed the spatial variability of remotely sensed sea surface temperature in 124 images that covered an offshore distance of 200 km and an alongshore distance of 500 km the first mode empirical orthogonal function described 65 of the spatial variability in the data set the spatial amplitude pattern of the first mode which closely resembled the mean of all the images revealed a strong cross shore gradient with much cooler water nearshore and warmer water offshore these areas of cool waters were associated with known upwelling locales and the large scale temperature structure compared favorably to that derived from historical california cooperative oceanographic fisheries investigation calcofi climatology the mode 1 temporal amplitude function representing the temporal modulation of this spatial pattern was coupled with changes in the alongshore component of the coastal wind field interannual variations in the timing of the spring transition were reflected in this temporal amplitude time series the second mode empirical orthogonal function described 11 of the variability in the data set the spatial pattern revealed a north south structure that appeared to be related to regional spatial variations in the strength of upwelling favorable wind the third empirical orthogonal function described only 3 of the data variability and the spatial structure suggested a meandering of the coastal surface flow the results of this investigation indicate that the empirical orthogonal function method was effective at characterizing from the satellite data the dominant nearshore surface properties of the california current system related to upwelling and wind and by extension suggest that it is a suitable approach for remotely investigating other less well known eastern boundary current systems

three dimensional connectivity in the gulf of california based on a numerical model abstract quantifying connectivity is useful for understanding the exchange and trapping of some tracers such as fish larvae and nutrients in the gulf of california connectivity studies have been limited to certain periods and regions the current study investigated the connectivity among 17 areas defined by the presence of eddies and weak or strong flows as obtained from a three dimensional non linear baroclinic model the particles were released into the water column and advected for 28 days using an advection diffusion scheme the results revealed a seasonal connectivity pattern in the northern region particle trapping was greater during the cyclonic circulation period june to september compared with the anticyclonic period november to march this high retention was due to both the presence of a cyclonic eddy in the central portion of the region and the intense northwestward flow off the coast of sonora retentions were low for the large island region due to the intense exchange between the northern and southern regions east of angel de la guarda island the transport occurred predominantly towards the northwest due to the nearly permanent deep flow in that direction and to a branching of the surface flow among the large islands during the anticyclonic period and the northwestward low during the cyclonic period in the peninsular and central areas of the southern region retentions were high due to weak flows and the presence of eddies respectively the greatest retention and low dispersion of particles in practically all of the provinces were recorded during the transition periods of the circulation

observations of the coastal upwelling region near 34 30 n of california spring 1981 abstract coordinated meteorological and oceanographic ctd measurements were made near point conception california during march april 1981 the goal of the observations was to study coastal upwelling and the local characteristics of the assumed wind driving results showed substantial topographically induced spatial structure in the near surface winds with weaker winds generally occurring within the santa barbara channel the 1981 spring transition event was monitored by mews of hydrographic and sea level measurements the details of the event suggest that it was not entirely driven by lead wind stress the mean sea surface temperature pattern suggests the existence of an upwelling center between points arguello and conception the individual sea surface temperature charts are all dominated by patchiness on a scale of 5 15 km the nature of these structures is not well understood but on the one occasion when a patch was isolated by a ctd survey its structure penetrated to at 1east 50 db

weathering rates and carbon storage along a climosequence of soils developed from contrasting granites in northeast brazil abstract i and s type granites comprise large areas and play a key role in global soil weathering patterns i type granites are originated from melting of igneous source rocks whereas s type granites result from melting of sedimentary sources this gives rise to differences in mineralogical and geochemical characteristics of the rocks the objective of this study was to address the effect of petrology and mineralogy of i and s type granites on weathering pedogenesis and total organic carbon stocks across a climosequence significant differences in morphological physical and chemical properties of soils derived from i and s type granites were observed and directly linked to petrological mineralogical and geochemical signatures of the underlying granites e g presence of more mafic minerals in the i type granite and therefore a higher clay and iron content in their derived soils in addition this higher iron content favored the hematite pathway and thus the red soil development despite the influence of the climate on weathering patterns i e higher soil development in humid areas parent material seems to play a decisive role in determining soils characteristics in the studied area the type of parent material also governed the rates of carbon accumulation in soils i type granites originated soils with higher toc stocks than soil profiles developed from s type granites this carbon accumulation is mainly due to soil chemical and physical characteristics driven by the type of granite notably soil fertility and clay content

quantitative clay mineralogy of a vertic planosol in southwestern ethiopia impact on soil formation hypotheses abstract planosols characterised by a bleached silt textured surface horizon abruptly overlying a dense clayey subsoil are a very common soil type in ethiopia the origin of the abrupt textural change is still often debated in literature one of the processes frequently put forward to explain the coarse textured material in the topsoil is ferrolysis an oxidation reduction sequence driven by bacterial decomposition of soil organic matter resulting in the destruction of open 2 1 clay minerals recent studies of representative profiles of vertic planosols in south western ethiopia indicate that these soils are composed of a weathered volcanic ash layer deposited on top of a deflated vertic subsoil which refutes the ferrolysis hypothesis to strengthen the geogenetic origin of these profiles a quantitative mineralogical analysis of the clay fraction was undertaken results of a sequential fractionation revealed a strong aggregation of clay particles in the bleached horizon while the effect of aggregation was far more limited in the vertic horizon this is believed to be related to the dispersed impregnative nature of iron oxides in the bleached horizon compared to the segregated nature of the sharp nodular concretions found in the vertic horizon the annealing xrd analysis revealed only minor changes in dehydroxylation temperatures of kaolinites and 2 1 minerals between untreated and dcb treated samples indicating that the pretreatment did not significantly alter the mineral lattices multi specimen full profile fitting of xrd patterns revealed no large quantitative differences between sub fractions of the bleached and vertic horizons although a net increase of 1 1 layers over 2 1 layers towards the top of the profile can be observed in the bleached horizon this could be interpreted as the result of neo formation of kaolinite the main mineralogical differences between the bleached and vertic horizons of the

biotite alteration to halloysite and kaolinite in soil saprolite profiles developed from mica schist and granite gneiss abstract the chemical weathering of biotite and associated formation of secondary minerals has important implications for the genesis mineralogy chemical properties and physical properties of soils and saprolites developed from biotite rich parent rocks in this study we used a combination of x ray diffraction micromorphological and scanning electron microscopy techniques to investigate biotite weathering in two soil saprolite profiles typic kanhapludults developed from granite gneiss and mica schist in the piedmont region of north carolina usa in both profiles sand sized biotite grains appeared to be transformed directly into kaolinized pseudomorphs of biotite without going through a detectable vermiculite or interstratified biotite vermiculite intermediate weathering stage minerals with biotite vermiculite mixed layers were only detected in small amounts in the clay and silt sized fractions of the saprolite weathering sand sized biotite grains exhibited expanded edges exfoliation and cleavage along 001 planes in the saprolite developed from granite gneiss kaolin intergrowths within weathering biotite grains were observed the edges of weathering biotite grains were densely covered with tubular halloysite suggesting a complex transformation of biotite to halloysite halloysite was the dominant clay mineral in the saprolite but the halloysite content in the clay fractions diminished towards the soil surface

use of misr measurements to study the radiative transfer of an isolated convective cloud implications for cloud optical thickness retrieval 1 radiative transfer simulations of an isolated deep convective cloud reconstructed with stereo techniques from the multiangle imaging spectroradiometer misr are compared with the reflectances measured at the nine misr viewing angles the simulations were done using a three dimensional monte carlo model in which ocean reflectance aerosol and rayleigh scattering were prescribed to match the surrounding clear sky misr measurements making reasonable assumptions regarding the vertical and horizontal distribution of the volume extinction coefficient we were able to reproduce the misr measurements with the 3d radiative calculations while the uniqueness of the these distributions cannot be proven they all lead to retrievals of much larger cloud optical thickness and cloud water content than for a 1d retrieval averaged over the cloud the difference was a factor of about 3 rising to 9 locally this is a consequence of horizontal photon transport that serves to highlight the inadequacy of 1d retrievals for the case of deep convective cloud concerning the internal cloud properties we noticed the angular distribution of modeled radiances did not match the measured radiances when an ice crystal phase function was applied better estimates of the optical depths and water contents of deep convective clouds appear to be obtainable by integrating an estimate of the extinction coefficient over the vertical cloud extent when this can assessed than by attempting to invert the radiance measured from a single angle view using 1d theory