the interaction of the madden julian oscillation with the maritime continent in a gcm previous studies using the hadley centre coupled model hadcm3 have shown that the islands of the maritime continent act as an unrealistic block to the eastward propagation of the madden julian oscillation mjo this blocking effect is investigated using a simplified aqua planet version of this gcm with various idealized configurations of the maritime continent islands placed on the equator and an mjo like convective signal forced by a propagating sea surface temperature anomaly dipole results suggest that it is the orography of the islands rather than the presence of the islands themselves which results in the blocking of the mjo although the peak elevation of the orography in the gcm is very much lower than in reality it appears to act as effective block to the eastward propagation of the low level kelvin wave signal which accompanies the mjo in particular the representation of sumatra in the gcm as a north south oriented ridge straddling the equator seems to be particularly effective at blocking the kelvin wave signal which in a full gcm would result in the weakening or complete extinction of the mjo signal to the east of the maritime continent

co2 diffuse emission from maar lake an example in changbai volcanic field ne china abstract numerous maars and monogenetic volcanic cones are distributed in northeast china which are related to westward deep subduction of the pacific ocean lithosphere comprising a significant part of the pacific ring of fire it is well known that diffuse co2 emissions from monogenetic volcanoes including wet e g maar lake and dry degassing systems e g soil diffuse emission fault degassing etc may contribute to budget of globally nature derived greenhouse gases however their relationship between wet e g maar lake and concomitant dry degassing systems e g soil diffuse emission fault degassing etc related to monogenetic volcanic field is poorly understood yuanchi maar one of the typical monogenetic volcanic systems is located on the eastern flank of tianchi caldera in changbai volcanic field of northeast china which displays all of three forms of co2 degassing including the maar lake soil micro seepage and fault degassing measurements of efflux of co2 diffusion from the yuanchi maar system yms indicate that the average values of co2 emissions from soil micro seepage fault degassing and water air interface diffusion are 24 3 23 3 g m 2 d 1 39 2 22 4 g m 2 d 1 and 2 4 1 1 g m 2 d 1 respectively the minimum output of co2 diffuse emission from the yms to the atmosphere is about 176 1 88 3 ton yr of which 80 4 results from the dry degassing system degassing from the fault contributes to the most of co2 emissions in all of the three forms of degassing in the yms contributions of mantle crust air and organic co2 to the soil gas are 0 01 0 10 10 20 32 36 and 48 54 respectively which are quantitatively constrained by a he c isotope coupling calculation model we propose that co2 exsolves from the upper mantle melting beneath the tianchi caldera which migrates to the crustal magma chamber and further transports to the surface of yms along the deep fault system during the transportation processes the emission of gas experiences crustal contamination influence of magma chamber beneath the yms sub surface processes and air dilution

a momentum budget analysis of westerly wind events associated with the madden julian oscillation during dynamo abstractthe dynamics of the madden julian oscillation dynamo field campaign was conducted over the indian ocean io from october 2011 to february 2012 to investigate the initiation of the madden julian oscillation mjo three mjos accompanying westerly wind events wwes occurred in late october late november and late december 2011 momentum budget analysis is conducted to understand the contributions of the dynamical processes involved in the wind evolution associated with the mjo over the io during dynamo using european centre for medium range weather forecasts analysis this analysis shows that westerly acceleration at lower levels associated with the mjo active phase generally appears to be maintained by the pressure gradient force pgf which could be partly canceled by meridional advection of the zonal wind westerly acceleration in the midtroposphere tends to be mostly attributable to vertical advection the results herein imply that there is no simple linear dynamic model that can capture t

application of stochastic simulation to co2 flux from soil mapping and quantification of gas release 1 conditional sequential gaussian simulations sgs have been applied for the first time to the study of soil diffuse degassing from different volcanic and nonvolcanic systems the application regards five data sets of soil co2 fluxes measured with the accumulation chamber methodology at the volcanic areas of solfatara of pozzuoli italy vesuvio cone italy nisyros greece and horseshoe lake california and at the nonvolcanic degassing area of poggio dell olivo italy the sgs algorithm was used to generate 100 realizations of co2 flux for each area probabilistic summaries of these simulations together with the information given by probability plots were used 1 to draw maps of the probability that co2 fluxes exceed thresholds specific for a background flux i e to define the probable extension of the degassing structures 2 to calculate the total co2 output and 3 to quantify the uncertainty of the estimation the results show that the sgs is a suitable tool to model soil diffuse degassing producing realistic images of the distribution of the co2 fluxes that honor the histogram and variogram of the original data moreover the relation between the sample design and the uncertainty of estimation was investigated leading to an empirical relation between uncertainty and the sampling density that can be useful for the planning of future co2 flux surveys

origin of the lethal gas burst from lake monoun cameroun abstract on 15 august 1984 a lethal gas burst issued from a submerged 96 m deep crater in lake monoun in cameroun western africa killing 37 people the event was associated with a landslide from the eastern crater rim which slumped into deep water waters below 50 m are anoxic dominated by high fe 2 600 mg l and hco 3 1900 mg l anoxic and supersaturated with siderite which is a major component of the crater floor sediments the unusually high fe 2 levels are attributed to reduction of laterite derived ferric iron gradually brought into the lake as loess and in river input sulfur compounds are below detection limits in both water and gas gases effervescing from depressurized deep waters are dominantly co 2 with minor ch 4 having 13 c of 7 18 and 54 8 per mil respectively bacterial decomposition of organic matter may account for the methane but 14 c of lake water indicates that only 10 of the carbon is modern giving an apparent age of 18 000 years the dominant source of carbon is therefore attributed to long term emission of co 2 as volcanic exhalation from vents within the crater which led to gradual build up of hco 3 in the lake the density stratification of the lake may have been upset by an earthquake and underwater landslide on 15 august which triggered overturn of the lake and caused nucleation of co 2 in the deep water the resultant ebullition of co 2 from deep lake waters led to a gas burst at the surface and locally generated a water wave up to 5 m high people travelling through the gas cloud were asphyxiated presumably from co 2 and suffered skin discoloration from unidentified components

a case study of an outbreak of twin tropical cyclones abstract previous studies have found that twin tropical cyclogenesis typically occurs 2 3 times a year in the pacific ocean during october 1997 however three sets of twin tropical cyclones developed in the central pacific within a single month tropical cyclone archives indicate that this is the only such outbreak from 1969 to 2006 this case study explores the background and synoptic conditions that led to this unique event all three twin tropical cyclogenesis events occurred within a broad and long lasting envelope of warm water low surface pressure active convection and weak or easterly vertical shear westerly winds at the equator and trade easterlies farther poleward created strips of cyclonic vorticity through a deep layer a low pass filter showed that these favorable conditions shifted eastward with time at 1 2 m s 1 in addition to the gradual eastward movement the equatorial westerlies and convection were modulated by higher frequency westward propagation these anomalies appear to have

fold reactivation involving angular unconformable sequences theoretical analysis and natural examples from the cantabrian zone northwest spain abstract during the reactivation of folds truncated by unconformable layers the unconformity surface adopts various geometrical shapes depending on the fold reactivation mechanisms the paleorelief slope is also a determining factor for location and development of cover structures it can be theoretically shown that the reactivation of flexural flow and flexural slip folds below an unconformity produces folds of the same sense of curvature in layers above and below the unconformity viewed in profile that is to say these mechanisms give rise to a cover synform over a basement synform or antiform over antiform when the axes of both folds are subhorizontal folds reactivated by tangential longitudinal strain also behave in the same way in this case the cover folds may become tight even for initially high angles of unconformity which does not happen with flexural mechanisms the reactivation of chevron folds may give rise to opposite curvatures of basement and cover beds hence paradoxical structures such as a cover synform over a basement antiform or viceversa may be produced even if their axes are horizontal when two adjacent parts of the basement sequence are deformed by different folding mechanisms cover beds and unconformity are folded over the homoclinal sequence of each limb in the basement fold during fold reactivation the unconformity surface usually becomes a surface of decollement owing to the structures that have to be developed in the cover in order to accommodate the changes in length of the unconformity the development of extensional or compressional structures in the cover can be predicted from a geometrical study of the unconformity surface natural examples of reactivated folds under unconformable sequences of carboniferous age in the cantabrian zone show a good agreement with the above mentioned theoretical conclusions conclusions obtained on the distribution of folding mechanisms in the limbs and hinge zones and in layers or multilayers of different nature from the geometrical study of folded unconformable sequences in the cantabrian zone also agree with results from published experimental data

which mjo events affect north american temperatures abstracttropical convection from the madden julian oscillation mjo excites and amplifies extratropical rossby waves around the globe this forcing is reflected in teleconnection patterns like the pacific north american pna pattern and it can ultimately result in temperature anomalies over north america previous studies have not explored whether the extratropical response might vary from one mjo event to another this study proposes a new index the multivariate pna mvp to identify variations in the extratropical waveguide over the north pacific and north america that might affect the response to the mjo the mvp is the first combined eof of 20 100 day olr 850 hpa streamfunction and 200 hpa streamfunction over the north pacific and north america the north american temperature patterns that follow each phase of the mjo change with the sign of the mvp for example real time multivariate mjo rmm phase 5 usually leads to warm anomalies over eastern north america this relationship was only found

unraveling tectonic and climatic controls on synorogenic growth strata northern apennines italy we develop a new high resolution stratigraphic age model to unravel the contributions of tectonic and climatic processes on early to late pleistocene synorogenic growth strata we capitalize on excellent continuous exposures along the flank of the po foreland in northern italy to elucidate hydrologic geomorphic and sedimentologic processes that are regularly attributed to but rarely proven to be caused by glacial interglacial climatic changes and unsteady rock uplift we perform our analysis on the enza section a succession of marine and terrestrial strata exposed along the enza river between parma and reggio emilia northern italy bedding in the enza section displays synorogenic growth strata geometry with bedding dips that range from 2 to 55 that becomes progressively shallower upsection we develop an age model that incorporates biostratigraphy magnetostratigraphy rock magnetic cyclostratigraphy cosmogenic radionuclide burial dating and optically stimulated luminescence dating and shows that the enza section spans the interval between 0 04 and 1 65 ma furthermore the age model pins the time of deposition for several lithostratigraphic units of regional significance and shows that sediment accumulation was unsteady ranging from 14 31 cm k y in the marine part of the section to 5 362 cm k y in the overlying littoral and terrestrial part of the section unsteady deposition is most pronounced in the terrestrial deposits where thick fluvial gravel packages accumulated in short 10 15 k y time periods that coincide with quaternary glacial intervals there is direct evidence for a dominant tectonic control in the older marine part of the section here sediment accumulation rates on the limb of the fold growing along this portion of the northern apennine mountain front show that between 1 07 and 1 65 ma repetitive progradation of neritic sand units directly followed pulses of rapid punctuated uplift in contrast the cyclic terrestrial facies variations in the enza section reveal that once the section became emergent at ca 1 ma and uplift slowed climate was the dominant control on sediment production and deposition

structural evolution of the northern los angeles basin california based on growth strata subsurface structure contour maps and cross sections show that the northern los angeles basin is underlain by a south facing monocline complicated by secondary faults and folds the monocline and associated structures form a structural high the northern los angeles shelf which marks the northern margin of the los angeles central trough analysis of growth strata sediments deposited during structural growth shows that during the miocene the predominant structural style was extension growth strata show that at approximately the beginning of the pliocene 5 ma contraction reactivated the miocene normal faults as reverse faults and formed the monocline its secondary structures and the los angeles central trough lensing out of earliest pliocene delmontian stage growth sandstones onto the flanks of the monocline and secondary structures the south salt lake the east beverly hills and the las cienegas anticlines indicates that these contractional structures all began to form at this time all of the secondary structures became largely inactive prior to the deposition of upper pico member of early pleistocene age 1 2 ma however thick accumulations of growth strata of the upper pico member of the fernando formation within the los angeles central trough attest to continued monoclinal folding after the secondary structures became largely inactive the growth strata record both vertical and horizontal components of structural growth of the monocline so that the dip of the blind fault zone causing the monocline the los angeles fault can be calculated in the east beverly hills area the dip of the los angeles fault is 61 and at las cienegas the dip is 62 these are maximum values based on the assumption that the growth strata bed lengths record all shortening the pliocene pleistocene average fault slip rates for the los angeles fault are 1 1 1 3 mm yr in the east beverly hills and 1 3 1 5 mm yr at las cienegas the resulting pliocene pleistocene horizontal convergence rates are 0 5 0 6 mm yr and 0 6 0 7 mm yr respectively the pliocene pleistocene growth strata show increased dip with age indicating that the monocline grew by progressive limb rotation rather than by kink band migration therefore fault bend and fault propagation fold models based on kink band migration are inadmissible solutions to explain the growth of the monocline we suggest a basement involved shear zone to explain the geometry of the northern los angeles shelf

tracking and mean structure of easterly waves over the intra americas sea abstract easterly waves ews are prominent features of the intertropical convergence zone itcz found in both the atlantic and pacific during the northern hemisphere summer and fall where they commonly serve as precursors to hurricanes over both basins a large proportion of atlantic ews are known to form over africa but the origin of ews over the caribbean and east pacific in particular has not been established in detail in this study reanalyses are used to examine the coherence of the large scale wave signatures and to obtain track statistics and energy conversion terms for ews across this region regression analysis demonstrates that some ew kinematic structures readily propagate between the atlantic and east pacific with the highest correlations observed across costa rica and panama track statistics are consistent with this analysis and suggest that some individual waves are maintained as they pass from the atlantic into the east pacific whereas others are generated locally in the caribbean a

influence of pre tectonic carbonate facies architecture on deformation patterns of syntectonic turbidites an example from the central mexican fold thrust belt abstract the mexican fold thrust belt in central mexico excellently exposes relatively well preserved syntectonic deposits that overlay rocks with lateral lithostratigraphic changes across the belt we consider the deformational effects of these changes by investigating the geometry kinematics and strain distribution within syntectonic turbidites which are deposited on top of albian cenomanian shallow and deep water carbonate layers field observations and detailed structural analysis at different stratigraphic and structural levels of the late cretaceous syntectonic formation are compared with the deformation as a function of lithological and structural variations in the underlying carbonate units to better understand the effect of these lithostratigraphic variations on deformation kinematics strain distribution and propagation of deformation from our kinematic analyses we conclude that the syntectonic strata are pervasively affected by folding in all areas and that deformation partitioning localized shear zones at the boundaries of this unit particularly along the contact with massive carbonates at the boundaries with massive platformal carbonates the turbidites are strongly deformed by isoclinal folding with a pervasive sub horizontal axial plane cleavage and 70 60 shortening in contrast contacts with thinly bedded carbonate layers basinal facies do not show strain localization and have horizontal shortening of 50 40 that is accommodated by buckle folds with a less pervasive steeply dipping cleavage the mechanical properties variations in the underlying pre tectonic units as a function of changes in lithostratigraphy fundamentally control the deformation in the overlying syntectonic strata which is an effect that could be expected to occur in any deformed sedimentary sequence with such variations

bed by bed fold growth by kink band migration sant llorenc de morunys eastern pyrenees ahstract rowth strata deposited over and against the flank of the sant llorenc de morunys fold during its final stages of deformation have been mapped at high resolution as the basis for unraveling the kinematics of fold growth we use restoration techniques based on normal balancing assumptions to decipher the detailed kinematic history of folding the progressive restorations as well as balanced forward modeling show that the last few hundred meters of fold growth were dominated by kink band migration of a sort that is typical of much faultrelated folding the kink band migration has produced complex anticlinal hinge zone geometry including segmented fold hinges linked by disconformities and unconformities which has direct and detailed explanation in terms of fluctuations in deposition rate relative to curved hinge kink band migration rate large fluctuations in the convolution of non steady sedimentation and deformation are demonstrated although the absolute fluctuations in deformation and sedimentation are unknown at a length scale of 100 m kink band migration with little or no deposition is interspersed with sedimentation with little or no deformation at the length scale of 500 m deposition ranges from 200 to 50 of uplift 0 1997 elsevier science ltd all rights reserved

orographic influence on the synoptic scale circulations associated with the genesis of hurricane guillermo 1991 abstract the early stages of tropical cyclogenesis in the eastern pacific ocean are investigated in this case study which is focused on the development of the initial circulation that eventually intensified into hurricane guillermo 1991 the authors document the synoptic and mesoscale winds from upper air soundings satellite imagery and a gridded analysis in addition flight level observations taken during the tropical experiment in mexico are used these winds reveal that prior to the formation of the tropical cyclone an easterly wave moved over the caribbean sea and that the initial circulation developed while the easterly wave was located over the central caribbean east of the mountains in central america numerical simulations with the pennsylvania state university national center for atmospheric research mesoscale model are used to examine the details of the structure of the flow that resulted in the formation of the eastern pacific circulation in these simulations the model is initialized

pulsating subsidence during a rift episode stratigraphic and tectonic consequences aptian albian northern spain backstripping analysis has been carried out on nine outcrop sections of the basque cantabrian aptian and albian of northern spain which consist of shallow water marine deposits up to 7000 m thick it reveals four main pulses of common accelerated subsidence i early aptian ii early albian iii lower late albian and iv uppermost late albian separated by tectonic quiescent intervals tectonic subsidence rates of 70 m myr 1 for the aptian and 101 m myr 1 for the albian were recorded sopuerta section the calculated stretching factor referred to a pre rift continental crust of 35 km is bs 1 32 and represents approximately 8 5 km of crustal thinning points of change towards lesser subsidence rate in the curves are correlated with major unconformities in the sections in the basque cantabrian basin and in boreal europe suggesting geodynamic changes related with the opening of bay of biscay minor variations of spreading direction and intensity are proposed to explain the subsidence pulses

multiple dolomitization events along the pozalagua fault pozalagua quarry basque cantabrian basin northern spain the pozalagua quarry in the basque cantabrian basin of northern spain exposes a unique set of fault associated dolomites that can be studied on a decametre scale the dolomites developed along the pozalagua fault system in slope deposited limestones of albian age following marine phreatic diagenesis the limestones were subject to meteoric karst formation the resulting cavities were filled either by angular limestone fragments in a black clay rich matrix or by cave floor pond now dolomitized sediments the subsequent diagenetic history reflects repeated periods of fracturing fluid expulsion dissolution and cementation contrasting fluid pulses resulted in the formation of a network of hydrothermal karst and the subsequent development of coarse crystalline calcite cement zebra dolomite recrystallized coarse crystalline dolomite elongated blue grey coarse crystalline dolomite cement in the open fault and finally coarse crystalline saddle dolomite decimetre size reworked host rock fragments present in the latter two dolomite phases probably reflect roof collapse fragments of a cave system that developed along the pozalagua fault system however there are also metre scale host rock fragments that apparently float in the coarse crystalline saddle dolomites implying that either fragment assimilation was a widespread process or violent expulsion of fluids occurred along the pozalagua fault system the presence of pre dolomite and post dolomite stylolites parallel to bedding supports a linkage between the diagenetic events and the late albian tectonism that affected the region

volatile fluxes from volcanoes volatile fluxes from mid ocean ridge mor and subaerial volcanism have been estimated or re evaluated using several natural tracers 3he 210po so2 and chemical ratios of volatile species in lavas and volcanic gases these estimates confirm the net predominance of anthropogenic fluxes over volcanic fluxes for co2 so2 and trace metals they also suggest that while most of the volatiles transferred during mor volcanism come from the mantle volatiles stored at the surface of the earth supply an appreciable fraction of subaerial fluxes and can be the dominant source for some of them the surface inventory of volatile species cannot result from steady state degassing with constant rate and needs much greater fluxes in the past or other volatile supply processes this inventory is the result of several of the following processes capture of the solar nebula and its subsequent partial escape impact degassing of accreting bodies and from archean to present mantle degasssing through volcanism and associated phenomena with recycling into the mantle through subduction

gas emission from diffuse degassing structures dds of the cameroon volcanic line cvl implications for the prevention of co2 related hazards abstract in the mid 1980s lakes nyos and monoun violently released massive gas mainly magmatic co 2 killing about 1800 people subsequent geochemical surveys and social studies indicate that lakes nyos and monoun event is cyclic in nature and may occur anywhere in the about 37 other volcanic lakes located in the corridor of the cameroon volcanic line cvl this potential threat motivated us to check if alike nyos and monoun the internal dynamic of the other lakes is also controlled by inputs of deep seated derived co 2 and attempt to measure and provide comprehensive insights on the passive gas emission along the cvl this knowledge shall contribute to the prevention of volcanic lake related hazards in cameroon and the refinement of the global carbon cycle we used in situ fixation and dry gas phase sampling methods to determine co 2 origin and the concentration and the accumulation chamber technique to measure diffuse co 2 emission from nine lakes and on soil at nyos valley and mount manenguba caldera the results suggest that although in minor concentrations compared to nyos and monoun ranging from 0 56 mmol kg 1 to 8 75 mmol kg 1 the bottom waters of some lakes also contain measurable magmatic co 2 with 13 c varies from 4 42 to 9 16 vs pdb that finding implies that under certain circumstances e g increase to volcanic and or tectonic activities along the cvl the concerned lakes could develop a nyos type behavioural scheme the diffuse gas emission results indicate that the nine surveyed lakes release approximately 3 69 0 37 kt km 2 yr 1 of co 2 to the atmosphere extrapolation to the approximately 39 volcanic lakes located on the cvl yields an approximate co 2 output of 27 37 0 5 kt km 2 yr 1 representing 0 023 of the global co 2 output from volcanic lakes in addition to the precedent value the gas removal operation in lakes nyos and monoun released approximately 2 52 0 46 10 8 mol km 2 yr 1 co 2 to the atmosphere from january 2001 to march 2013 more than double the per area co 2 released by the yellowstone volcanic system the co 2 emission from soil was estimated to be 4 57 1 30 kt km 2 yr 1 the soil gas geochemistry of the mount manenguba caldera also indicates a dominant magma derived co 2 mean 13 c 8 6 vs vpdb

global emissions of helium 3 by subaerial volcanism the emission rate of helium 3 by subaerial volcanism is re evaluated by coupling 3he co2 ratios in volcanic gases with new estimate of the flux of carbon dioxide from both arc and non arc volcanoes steady volcanic plume emissions are computed to supply 240 310 mole 3he yr most of which is due to non arc volcanoes major eruptions represent minor additions on average whereas diffuse 3he emanations through volcanic piles may be important sources although not including this contribution the above figure is equivalent to 20 40 of the 3he flux from mid ocean ridges and thus suggests that primordial 3he degassing from subaerial volcanic regions may be larger than expected

equatorial dry air intrusion and related synoptic variability in mjo initiation during dynamo abstractdynamics of the madden julian oscillation dynamo was conducted over the equatorial indian ocean io from october 2011 to march 2012 during mid to late november a strong madden julian oscillation mjo event denoted mjo 2 initiated in the western io and passed through the dynamo observation array dry air intrusions associated with synoptic variability in the equatorial region played a key role in the evolution of mjo 2 first a sharp dry air intrusion surging from the subtropics into the equatorial region suppresses convection in the itcz south of the equator this diminishes subsidence on the equator associated with the itcz convection which leads to an equatorward shift of convection it is viewed as a contributing factor for the onset of equatorial convection in mjo 2 once the mjo convection is established a second type of dry air intrusion is related to synoptic gyres within the mjo convective envelope the westward propagating gyres draw drier air from the subtropics into the equa

co2 fluxes of two lakes in volcanic caves in the azores portugal abstract this paper characterises diffuse co2 degassing from lakes located inside volcanic caves on the islands of terceira and graciosa in the azores archipelago portugal the algar do carvao lake is located inside a volcanic pit on terceira at an altitude of 92 m and has a surface area of 11 500 m2 and a maximum depth of 8 2 m the furna do enxofre lake is located inside a lava cave on graciosa at an altitude of 500 m and has a surface area of approximately 300 m2 and a maximum depth of 9 3 m the water temperature of both lakes is low with values ranging between 11 c and 13 c in both the winter and summer periods and no variations are observed along their water columns the electrical conductivity ranges from 585 s cm 1 to 687 s cm 1 in furna do enxofre and from 117 s cm 1 to 131 s cm 1 in algar do carvao reflecting a higher mineralisation in the former lake the ph values in furna do enxofre range between 6 50 and 6 58 which reflects the effect of co2 dissolution while in algar do carvao the ph values are more basic 7 42 8 53 the water types are mg hco3 for furna do enxofre and na hco3 for algar do carvao the mg enrichment in furna do enxofre is associated with water rock interactions which are enhanced by the acidic environment diffuse co2 flux measurements were made using the accumulation chamber method with a total of 37 measurements split into two surveys at algar do carvao and 71 measurements during a single survey at furna do enxofre the total co2 emitted from furna do enxofre was 6100 kg d 1 which was much lower than that emitted from algar do carvao 0 32 2 0 kg d 1 a volcanic origin was assigned to the lake on graciosa due to the 13c isotopic signature of the co2 conversely the co2 released in algar do carvao is derived from a biogenic co2 source considering the surface areas of the studied lakes the co2 flux is in the range of 1 5 6 7 t km 2 d 1 for algar do carvao and is 508 3 t km 2 d 1 for furna do enxofre

low level potential vorticity and cyclogenesis to the lee of the alps abstract high resolution numerical model simulations over the alpine region are presented that reveal the presence of low level elongated bands of potential vorticity pv downstream of high topography these pv streamers or pv banners occur when the synoptic scale wind turns into a direction across the alps individual pairs of banners with anomalously positive and negative values of pv can be attributed to flow splitting either on the scale of the whole of the alps primary banners or on that of individual massifs and peaks of the model topography secondary banners the pv bands have amplitudes of up to 2 5 and 5 pvu a width of 50 150 km can attain a length of up to 1500 km and extend in the vertical from the surface up to the 500 hpa level on occasions the pv banners are associated with zones of enhanced horizontal wind shear the analysis of daily output from the operational nwp model run of the swiss meteorological institute also demonstrates that such pv streamers are a frequent feature

diffuse co2 emission rate from pululahua and the lake filled cuicocha calderas ecuador abstract we report herein the first results of two soil co 2 efflux surveys carried out at cuicocha lake filled and pululahua caldera volcanic systems ecuador a total of 172 and 217 soil co 2 efflux measurements were taken at the surface environment of pululahua and cuicocha calderas respectively by means of the accumulation chamber method during the summer of 2006 to constrain the total co 2 output from the studied area soil co 2 efflux values ranged from non detectable up to 48 5 and 141 7 g m 2 d 1 for cuicocha and pululahua calderas respectively in addition probability graphs were used to distinguish the existence of different geochemical populations sequential gaussian simulation was used to construct an average map for 100 simulations and to compute the total co 2 emission at each studied area 106 and 270 t d 1 metric tons per day for cuicocha 13 3 km 2 and pululahua 27 6 km 2 volcanoes respectively

a mesozoic time scale we present an integrated geomagnetic polarity and stratigraphic time scale for the triassic jurassic and cretaceous periods of the mesozoic era with age estimates and uncertainty limits for stage boundaries the time scale uses a suite of 324 radiomenc dates including high resolution 40 ar 39 ar age estimates this framework involves the observed ties between 1 radiometric dates biozones and stage boundaries and 2 between biozones and magnetic reversals on the seafloor and in sediments interpolation techniques include maximum likelihood estimation smoothing cubic spline fitting and magnetochronology

the role of topographically induced vortices in tropical cyclone formation over the indian ocean abstractthe role of sumatra and adjacent topographic features in tropical cyclone tc formation over the indian ocean io is investigated sumatra as well as the malay peninsula and java have mountainous terrain that partially blocks low level flow under typical environmental stratification for easterly low level flow these terrain features often produce lee vortices some of which subsequently shed and move westward from the northern and southern tips of sumatra and thence downstream over the io since sumatra straddles the equator extending in a northwest southeast direction from approximately 6 n to 6 s the lee vortices while counter rotating are both cyclonic hence they can serve as initial disturbances that eventually contribute to tc formation over the io in addition low level equatorial westerly flow impinging on sumatra is also typically blocked and diverges at times contributing to cyclonic circulations over the io primarily near the southern end of the island data from two recen

the interaction of easterly waves orography and the intertropical convergence zone in the genesis of eastern pacific tropical cyclones the interaction of an idealized easterly wave with an orographic feature representing the sierra madre of mexico and a large scale meridionally sheared zonal flow representing the itcz in the eastern north pacific is examined through numerical integration of the shallow water equations on an equatorial beta plane channel the model simulations show that as a wave approaches the orography from the east the relative vorticity in the lee increases due to the wave being modified by the orography this relative vorticity maximum increases the northward advection of the itcz in the lee of the mountain that occurs due to the influence of the mountain anticyclone the result of this interaction is the development of a localized region of enhanced cyclonic vorticity that moves parallel to the contours of the model orography there is a minimal increase in the amplitude of the vorticity occuring during interactions between the wave and orography itcz and orography and wave and itcz the position of the incident wave upstream of the orography at the time that the disturbance in the lee begins to develop and the subsequent motion of the leeside vorticity maximum are in agreement with an observed case of eastern pacific tropical cyclogenesis which is also presented

the mjo kelvin wave transition 1 as the madden julian oscillation mjo moves eastward from the indian to the pacific ocean it typically accelerates becomes less strongly coupled to convection and becomes more similar to a dry kelvin wave this transition is analyzed using observations of outgoing longwave radiation and era interim reanalyses of surface pressure and 850 hpa zonal wind two individual example events as well as composites are shown the transitions are well defined with distinct disturbances on either side of the transition whose identities as mjo or kelvin waves are clear in some cases there appears to be a pre existing kelvin wave passing through the mjo from the west to the east but this feature is not apparent in the composites the transitions occur at different longitudes in different events over a wide range from the eastern indian to the central pacific oceans

low froude number flow past three dimensional obstacles part i baroclinically generated lee vortices abstract we study the flow of a density stratified fluid past a three dimensional obstacle using a numerical model our special concern is the response of the fluid when the froude number is near or less than unity linear theory is inapplicable in this range of froude number and the present numerical solutions show the rich variety of phenomena that emerge in this essentially nonlinear flow regime two such phenomena which occupy parts i and ii of this study are the formation of a pair of vertically oriented vortices on the lee side and a zone of flow reversal on the windward side of the obstacle the ice vortices have been explained as a consequence of the separation of the viscous boundary layer from the obstacle however this boundary layer is absent by design in the present experiments and lee vortices still occur we argue that a vertical component of vorticity develops on the lee side owing to the tilting of horizontally oriented vorticity produced baroclinically as the isentropes deform in r

convectively coupled kelvin wave propagation past sumatra a june case and corresponding composite analysis 1 the propagation of two sequential convectively coupled cc kelvin waves past sumatra in june 2006 is examined in reanalysis data and satellite observations rainfall data are presented that are consistent with a considerable damping of the first wave such damping is not unexpected however reanalysis data suggest that in some instances including the episode described here cc kelvin waves can condition the low level flow in a manner that promotes passage of subsequent waves past the island the mechanism involves a sustained northward shift in the low level equatorial westerly winds and the latitude of zero absolute vorticity generated as a cc kelvin wave passes for the june 2006 case kelvin wave filtered low level winds are presented which are consistent with the view that such conditioning associated with the first wave caused the second wave to be shifted northward assisting its eastward propagation a vorticity analysis points to the development of widespread low level divergence within a vortex to the west of sumatra and associated vortex expansion as key factors in the observed conditioning a composite analysis is presented for the region demonstrating recurring divergence events of this nature coupled with concomitant northward shifts in the dynamic equator it finds that such events often occur in association with cc kelvin waves though the climatological extent to which the propagation of successor waves is affected is not addressed possible causes of the observed divergence events including equatorial rossby waves and contributions from transitions to stratiform convection are investigated

tropical cyclogenesis associated with kelvin waves and the madden julian oscillation abstractthe madden julian oscillation mjo influences tropical cyclone formation around the globe convectively coupled kelvin waves are often embedded within the mjo but their role in tropical cyclogenesis remains uncertain this case study identifies the influences of the mjo and a series of kelvin waves on the formation of two tropical cyclones typhoons rammasun and chataan developed in the western north pacific on 28 june 2002 two weeks earlier conditions had been unfavorable for tropical cyclogenesis because of uniform trade easterlies and a lack of organized convection the easterlies gave way to equatorial westerlies as the convective envelope of the madden julian oscillation moved into the region a series of three kelvin waves modulated the development of the westerlies cyclonic potential vorticity pv developed in a strip between the growing equatorial westerlies and the persistent trade easterlies farther poleward rammasun and chataan emerged from the apparent breakdown of this strip the

late albian ammonite biostratigraphy of the kirchrode i borehole hannover germany abstract the ammonite biostratigraphy of the 245 m of sediments of late albian age traversed in the kirchrode i 1 91 boring situated in the south eastern suburbs of the city of hannover lower saxony basin is described correlation is made with the actinoceramus birostrina bivalve biostratigraphy in the part of the core of early late albian age and with the inoceramus inoceramus lissa aucellina gryphaeoides succession above the earliest sediments of late albian age are of late dipoloceras cristatum subzone age with a good representation of the hysteroceras orbignyi subzone and an incomplete representation of the hysteroceras varicosum subzone a notable feature of the succession is the presence of a considerable thickness ca 164 m of sediments of callihoplites auritus subzone age sediments of stoliczkaia dispar zone age indicate the representation of the mortoniceras mortoniceras rostratum mortoniceras durnovarites perinflatum and arrhaphoceras praeschloenbachia briacensis subzones the ammonite fauna of the borehole is listed and the ammonite biostratigraphy of the clay sediments traversed is discussed a brief comparison is made with other surface and borehole sections in northern germany and elsewhere and the more cosmopolitan tethyan elements of the fauna are indicated and discussed

very low frequency resistivity self potential and ground temperature surveys on taal volcano philippines implications for future activity abstract taal volcano is one of the most dangerous volcanoes in the philippines thirty three eruptions have occurred through historical time with several exhibiting cataclysmic phases most recent eruptions are confined to volcano island located within the prehistoric taal collapse caldera that is now filled by taal lake the last eruptive activity from 1965 to 1977 took place from mt tabaro about 2 km to the southwest of the main crater center since this time episodes of seismic activity ground deformation gas release surface fissuring fumarole activity and temperature changes are recorded periodically around the main crater but no major eruption has occurred this period of quiescence is the third longest period without eruptive activity since 1572 in march 2010 a campaign based on very low frequency vlf resistivity surveys together with repeated surveys of self potential ground temperature and fissure activity was intensified and the results compared to a large scale electrical resistivity tomography experiment this work fortunately occurred before within and after a new seismovolcanic crisis from late april 2010 to march 2011 the joint analysis of these new data together with results from previous magnetotelluric soundings allows a better description of the electrical resistivity and crustal structure beneath the main crater down to a depth of several kilometers no indication of growth of the two geothermal areas located on both sides of the northern crater rim was apparent from 2005 to march 2010 these areas appear controlled by active fissures opened during the 1992 and 1994 crises that dip downward towards the core of the hydrothermal system located at about 2 5 km depth beneath the crater older mineralized fissures at lower elevations to the north of the geothermal areas also dip downward under the crater repeated self potential and ground temperature surveys completed between 2005 and 2015 show new geothermal and hydrothermal activity in the areas of these older mineralized fissures that occurred during the april 2010 to march 2011 seismovolcanic crisis this dramatically extends the geothermal activity further to the north on the volcano the occurrence of these newly activated fissures after a long period of quiescence and indications of inflation in mid 2010 under the north rim of the main crater suggests that new eruptive activity near the north rim of the crater could occur in the future

geochemical evidence of magma intrusion inferred from diffuse co 2 emissions and fumarole plume chemistry the 2010 2011 volcanic unrest at taal volcano philippines we report herein significant increases in the diffuse co2 emission through the lake and soils of the taal volcano main crater philippines during a volcano seismic unrest period in april 2010 june 2011 monitoring of co2 emissions from the taal main crater lake and soils in the fumarole areas started in 2008 with a collaborative project between iter and phivolcs in august 2010 the total diffuse co2 emission from the taal main crater lake increased almost three times from a previously measured baseline emission value 1 000 t day 1 to 2 716 54 t day 1 this increase occurred during anomalous seismic activity which started in april 2010 the highest co2 emission value in the crater lake was measured in march 2011 at 4 670 159 t day 1 when the volcano was still showing signs of unrest significant changes in the co2 so2 co2 h2o and so2 h2s ratios in the fumarole gases suggest the occurrence of a magmatic injection several weeks before the onset of the volcano seismic unrest period these observed changes in the co2 emission rate and the fumarole gas composition as the result of magmatic activity were likely caused by magma moving from a deep reservoir to a shallow reservoir

mid cretaceous hydrothermal vents and authigenic carbonates in a transform margin basque cantabrian basin western pyrenees a multidisciplinary study a comprehensive study of authigenic carbonates and associated fauna in late albian organic rich deep water deposits the black flysch group reveals that carbonate precipitation was a by product of the anaerobic oxidation of hydrocarbon rich hydrothermal fluids the authigenic carbonates are exposed along the kardala and alkolea sea cliffs in the western pyrenees the two vent carbonates occur 1 km apart adjacent to the synsedimentary right reverse mutriku fault but in contrasting structural domains the kardala carbonates occur on a structural ridge hangingwall and the alkolea carbonates are positioned at the base of an erosional scarp folded downward footwall the similarity in pattern of the carbonate phases and complex paragenetic events for both vent precipitates implies that hydrothermal fluid generation processes and pore water evolution during early and late diagenesis were similar nevertheless a comparison of the geochemistry fossil fauna and morphology of carbonate structures of both precipitates suggests that the vented hydrocarbon type flow intensity and temperature of hydrothermal fluids were different at the kardala vent intense focused flow of hot up to 109 c oil rich fluids were generated allowing the development of a relatively abundant chemosynthesis based fauna in contrast at the alkolea vent diffuse flows of warm thermogenic methane rich fluids were expelled to the sea floor and no chemosynthetic fauna developed these differences are related to the contrasting structural setting of each locality similar d 13 corg values for both pyrobitumen fills and host unit organic matter suggest that the hydrocarbon source was the black flysch group contact alteration of these organic rich sediments by syndepositional hydrothermal fluids generated hydrothermal petroleum oil and gas hydrocarbons which probably migrated updip to the sea floor by contemporary compression tectonics

external influences on hurricane intensity part i outflow layer eddy angular momentum fluxes abstract outflow layer winds were objectively analyzed every 12 h for 6 days during the life cycle of hurricane elena 1985 a high correlation was found between angular momentum fluxes by azimuthal eddies at large radii and central pressure changes in the storm 27 33 h later momentum flux by eddies exceeded that by the azimuthal mean outside the 800 km radius while vortex spinup by the eddies reached instantaneous magnitudes as large as 25 m s 1 day outflow maxima and minima repeatedly appeared more than 1000 km from the hurricane center and tracked inward with time the results provide evidence of significant environmental control on the behavior of the storm after reaching hurricane strength elena experienced a major secondary intensification associated with a large inward cyclonic eddy momentum flux produced by the passage of a middle latitude trough north of the hurricane an outflow maximum appeared radially inside of the eddy momentum source consistent with balanced vortex theory and tracke

diffuse emission of co2 and convective heat release at nisyros caldera greece abstract the diffuse emission of co2 from the south east sector of nisyros caldera lakki plain has been measured during a detailed survey 1400 soil co2 flux measurements performed in october 2018 the gas emissions are fed by hydrothermal sources and in minor part by the soil biogenic activity whose mean co2 flux 4 g m 2 d 1 is here estimated for the first time the total amount of hydrothermal co2 reaches 92 8 t d a value that is slightly higher than that estimated with the same method between 1999 and 2001 74 7 t d the gas is emitted by different diffuse degassing structures ddss including volcanic hydrothermal structures craters and domes and ne sw and nw se trending tectonic lineaments even if the total co2 emission is not particularly high at nisyros close to the median of co2 emissions measured in volcanoes worldwide the process is very energetic the thermal energy associated with the shallow condensation of the steam in the ddss reaches 60 mw while we estimate at 134 270 mw the total amount of thermal energy involved in the convective rising of the deep geothermal liquids that transport the gas from the depth toward the surface this large flux of energy could dramatically increase during future earthquakes by addition of heat and mass from a deep hydrothermal reservoir potentially triggering hydrothermal explosions as it happened several times in the past few centuries

albian syndepositional block rotation and its geological consequences basque cantabrian basin western pyrenees stratigraphic structural palaeocurrent and palaeomagnetic analyses of upper albian deep water deposits in and around the deba block northern iberia are presented results indicate an anticlockwise vertical axis rotation of this block by 35 during a maximum time span of c 1 ma late albian intra c auritus ammonite subzone this albian syndepositional block rotation is interpreted to be the consequence of the coeval activity of conjugate major sinistral strike slip faults and minor antithetic dextral strike slip faults which border the deba block on the base of conservative estimations a minimum block rotation rate of 35 ma 1 and a sinistral strike slip rate of 1 2 km ma 1 are calculated as a consequence of the interaction of the rotated deba block with adjacent non rotated blocks its corners experienced coeval transpressive nw and se corners and transtensional deformations sw and possibly ne corners at the transtensional sw corner two domal high reflective seismic structures have been recorded and interpreted as high level magmatic laccoliths these magmatic intrusions triggered the development of a mineralizing hydrothermal system which vented to the late albian seafloor warm to hot hydrocarbon rich fluids vented hydrocarbon was generated from albian organic rich sediments by contact alteration with hydrothermal fluids

analysis of convectively coupled kelvin waves in the indian ocean mjo abstract the active convective phase of the madden julian oscillation hereafter active mjo comprises enhanced moist deep convection on its own temporal and spatial scales as well as increased variance in convection associated with higher frequency modes synoptic scale cloud superclusters apparently associated with convectively coupled kelvin waves occur within the active convective envelopes of most mjo events these convectively coupled kelvin waves also occur during the suppressed convective phase of the mjo hereafter suppressed mjo this observational study presents an analysis of outgoing longwave radiation and reanalysis data to determine how these waves behave differently as they propagate through the active and suppressed mjo time indices of the mjo and kelvin waves are derived for over the equatorial indian ocean dates of local extrema in these indices are used to composite data to discern how the waves and associated circulations behave on average then further composites are made based o

why precipitation is mostly concentrated over islands in the maritime continent abstract high resolution observations and regional climate model simulations reveal that precipitation over the maritime continent is mostly concentrated over islands analysis of the diurnal cycles of precipitation and winds indicates that this is predominantly caused by sea breeze convergence over islands reinforced by mountain valley winds and further amplified by the cumulus merger processes comparison of a regional climate model control simulation to a flat island run and an all ocean run demonstrates that the underrepresentation of islands and terrain in the maritime continent weakens the atmospheric disturbance associated with the diurnal cycle and hence underestimates precipitation the implication of these regional modeling results is that systematic errors in coarse resolution global circulation models probably result from insufficient representation of land sea breezes associated with the complex topography in the maritime continent it is found that precipitation in the maritime continent

a climatology of waves in the equatorial region abstract propagating anomalies of moisture and moist deep convection in the tropics are organized into a variety of large scale modes these include but are not limited to the so called intraseasonal oscillations convectively coupled waves similar to those predicted by shallow water theory on the equatorial beta plane and tropical depression type disturbances along with the annual and diurnal cycles these modes act and interact to control much of the variance of tropical convection analyses of 10 yr of outgoing longwave radiation olr and precipitable water pw data are carried out to develop comparative climatologies of these wavelike modes the analysis relaxes the commonly used cross equatorial symmetry constraints which allows study of the portions of the wavelike processes that are asymmetric across the equator mean background states are found for olr and for pw as functions of day of the year examination of anomalies together with the background reveals much about how the waves are affec

estimation of the co2 flux from furnas volcanic lake sao miguel azores abstract a study on diffuse co 2 degassing was undertaken at furnas lake sao miguel island azores in order to estimate the total diffuse co 2 output and identify anomalous degassing areas over the lake furnas lake is located in furnas volcano the easternmost of the three active central volcanoes of the sao miguel island the lake has an area of 1 87 km 2 and a maximum length and width equal to 2025 and 1600 m respectively the maximum depth of the water column is 15 m and the estimated water storage is 14 10 6 m 3 lake water temperature is cold with temperature values between 13 c and 15 c in the winter period and 18 9 c to 19 3 c in early autumn and the variation along the water column suggests a monomictic character the major ion relative composition is in decreasing order na k ca 2 mg 2 for cations and hco 3 cl so 4 2 for anions and conductivity and ph measurements respectively in the range of 152 to 165 s cm 1 and 5 3 to 8 7 suggests that furnas has neutral diluted waters and can be classified as a non active lake diffuse co 2 flux measurements were made using the accumulation chamber method with a total of 1537 and 2577 measurements performed in two different sampling campaigns the total amount of diffuse co 2 emitted to the atmosphere was estimated between 28 and 321 t km 2 d 1 respectively in the second and first sampling campaigns corresponding to 52 and 600 t d 1 the main anomalous degassing area identified over the furnas lake during both surveys is probably associated to a wnw ese trending tectonic structure other secondary areas are also suggested to be tectonically influenced identified anomalous areas showed similarities to the ones observed during previous soil co 2 degassing studies

paleomagnetically derived folding rates southern pyrenees spain well dated syntectonic unconformities with the spanish pyrenees allow characterization of sedimentation and deformation within an orogenic foreland the spanish pyrenees are composed of a south vergent thrust belt and foreland basin in which folds developed both parallel and perpendicular to tectonic transport unconformity geometries and magnetostratigraphic data from synorogenic strata provide a precise temporal framework for the quantitative analysis of the mediano anticline the largest of the transverse folds folding began in the early eocene and ended by 42 ma at which time an anticline 20 km long and 5 km in wavelength had been produced angular and progressive unconformities within syntectonic sedimentary units preserve the history of fold development fold growth resulted from west ward salt movement driven by prograding sediments and was characterized by 2 3 m y intervals of slow continuous limb tilting 2 2 4 2 m y preserved as progressive unconformities within syntectonic strata because the emplacement of the cotiella montsec thrust sheet was episodic intervals of slow fold growth were punctuated by intervals lasting

the flexural slip mechanism abstract detailed field studies of turbiditic sequences from south georgia south atlantic north devon england and cardigan bay wales show that flexural slip occurs on discrete movement horizons between rock packets in which the beds have welded contacts stair stepping displacements of sedimentary dykes and of early quartz veins show that the movement horizons generally have a decimetre to metre spacing and are marked by bedding parallel quartz veins these veins are from 1 mm to several cm thick and can be used to identify movement horizons in the absence of displaced markers they consist of several sheets of quartz fibres which each carry a slickenfibre lineation and which together preserve a record of the displacements on an individual surface complex slickenfibre patterns and departures from ideal behaviour in which slip occurs orthogonal to the fold hinge probably result from changes in slip vector on the limbs of growing non cylindrical folds movement horizons show many of the features associated with large scale thrusting such as ramps duplexes and imbricate structures and the shear sense given by fibre steps on these surfaces and by duplexes within stratigraphically restricted packages changes across fold hinges chevron folds are thought to develop mainly by flexural flow in the early stages with flexural slip becoming dominant later as the beds become lithified new slip surfaces are generated as the dip of the fold limbs increases

co2 discharge from the bottom of volcanic lake rotomahana new zealand 1 from april 2010 to february 2011 co2 flux surveys were performed on lake rotomahana new zealand the area has been hydrothermally active with fumaroles and sublacustrine hydrothermal activity before and since the eruption of mt tarawera in 1886 the total co2 emission from the lake calculated by sequential gaussian simulation is 549 72 t d 1 two different mechanisms of degassing diffusion through the water air interface and bubbling are distinguished using a graphical statistical approach the carbon dioxide budget calculated for the lake confirms that the main source of co2 to the atmosphere is by diffusion covering 94 5 of the lake area mean co2 flux 25 g m 2 d 1 and to a lesser extent bubbling mean co2 flux 1297 g m 2 d 1 mapping of the co2 flux over the entire lake including over lake floor vents detected during the survey correlates with eruption craters formed during the 1886 eruption these surveys also follow regional tectonic patterns present in the southeastern sector of lake rotomahana suggesting a deep magmatic source 10 km for co2 and different pathways for the gas to escape to the surface the values of 13cco2 2 88 and 2 39 confirm the magmatic origin of co2

mantle co2 degassing at mt vulture volcano italy relationship between co2 outgassing of volcanoes and the time of their last eruption abstract mantle volatiles are mainly lost from the earth to the atmosphere through subaerial and submarine volcanism recent studies have shown that degassing of mantle volatiles also occurs from inactive volcanic areas and in tectonically active areas a new challenge in earth science is to quantify the mantle derived flux of volatiles e g co2 which is important for understanding such diverse issues as the evolution of the atmosphere the relationships between magma degassing and volcanic activity gas pressure and seismogenic processes and the hazards posed by volcanic lakes here we present a detailed study of mantle derived co2 budget from mt vulture volcano in the apennines italy whose latest eruption occurred 141 11 kyr ago the relationship between 13cco2 and total dissolved carbon at mt vulture volcano indicates that the emitted co2 is a mixture of a biogenic end member with an average 13cco2 of about 17 and a mantle derived co2 end member with 13cco2 values from 3 to 2 these values of mantle derived 13cco2 are in the range of those for gas emitted from active volcanoes in the mediterranean we calculated the contribution of individual components co2 in groundwater in lakes and from main pools to the total co2 budget in the area we used new measurements of water flow combined with literature data to calculate the co2 flux associated with groundwater and measured the gas flux from the main pools on the volcanic edifice finally we calculated the co2 flow in the lakes based on the gradient concentration and eddy diffusivity the total mantle derived co2 budget in the area is 4 85 10 8 mol yr 1 which is more than double previous estimates this is higher than those observed in younger volcanic systems elsewhere thereby supporting the existence of actively degassing mantle melts below mt vulture volcano a structural map highlights the tectonic control on co2 flow across the mt vulture volcanic edifice indeed the tectonic discontinuities that controlled the magma upwelling during the most recent volcanic activity are still the main active degassing structures the new estimate of co2 budget in the mt vulture area together with literature data on co2 budget from historically active and inactive italian volcanoes suggests a power law functional relationship between the age of the most recent volcanic eruption and both total discharged co2 r 2 0 73 and volcano size normalized co2 flux r 2 0 66 this relation is also valid by using data from worldwide volcanoes highlighting that deep degassing can occur over very long time too in turn the highlighted relation provides also an important tool to better evaluate the state of activity of a volcano whose last activity occurred far in time finally our study highlights that in the southern apennines an active degassing of mantle derived volatiles i e he co2 occurs indiscriminately from west to east this is in contrast to the central northern apennine which is characterized by a crustal radiogenic volatile contribution which increases eastward coupled to a decrease in deep co2 flux this difference between the two regions is probably due to lithospheric tears which control the upwelling of mantle melts their degassing and the transport of volatiles through the crust

attributing tropical cyclogenesis to equatorial waves in the western north pacific abstract tropical cyclogenesis is attributed to an equatorial wave when the filtered rainfall anomaly exceeds a threshold value at the genesis location it is argued that 0 mm day 1 simply requiring a positive anomaly is too small a threshold because unrelated noise can produce a positive anomaly a threshold of 6 mm day 1 is too large because two thirds of storms would have no precursor disturbance between these extremes consistent results are found for a range of thresholds from 2 to 4 mm day 1 roughly twice as many tropical cyclones are attributed to tropical depression td type disturbances as to equatorial rossby waves mixed rossby gravity waves or kelvin waves the influence of the madden julian oscillation mjo is even smaller the use of variables such as vorticity and vertical wind shear in other studies gives a larger contribution for the mjo it is suggested that its direct influence on the rainfall in forming tropical cyclones is less than for other variables the impacts of tropical

convectively coupled equatorial waves 1 convectively coupled equatorial waves ccews control a substantial fraction of tropical rainfall variability their horizontal structures and dispersion characteristics correspond to matsuno s 1966 solutions of the shallow water equations on an equatorial beta plane namely kelvin equatorial rossby mixed rossby gravity and inertio gravity waves because of moist processes the tilted vertical structures of ccews are complex and their scales do not correspond to that expected from the linear theory of dry waves the dynamical structures and cloud morphology of ccews display a large degree of self similarity over a surprisingly wide range of scales with shallow convection at their leading edge followed by deep convection and then stratiform precipitation mirroring that of individual mesoscale convective complexes ccews have broad impacts within the tropics and their simulation in general circulation models is still problematic although progress has been made using simpler models a complete understanding of ccews remains a challenge in tropical meteorology

diffuse co2 flux emission in two maar crater lakes from sao miguel island azores portugal abstract santiago and congro are two maar crater lakes located at sao miguel the largest island of the azores archipelago santiago lake is located on the sete cidades volcano at an altitude of 364 m presenting a surface area of 0 25 km2 and a maximum depth of 33 m congro lake is located on the congro fissural volcanic system at an altitude of 420 m and has a surface area of 0 04 km2 and a maximum depth of 22 m both lakes are monomictic in character with low mineralized waters of meteoric origin being the temperature in the range between 12 4 c winter period and 23 8 c summer period the main water type is na hco3 and the relative major ion composition is hco3 cl so42 f for anions and na k mg2 ca2 for cations four sampling surveys were carried out between 2013 and 2016 in each lake in order to estimate surface diffuse co2 degassing a total of 1612 and 713 co2 flux measurements were made with an accumulation chamber at santiago and congro lakes respectively the higher co2 fluxes were measured during the winter surveys 0 2 t d 1 in congro and 5 6 t d 1 in santiago while the lowest values 0 1 t d 1 and 0 2 t d 1 respectively in congro and santiago lakes were recorded in the summer these seasonal differences observed in both lakes are associated with the monomictic character of the lakes as the co2 is not able to ascend to the surface when the water column is stratified during the warmer period due to the physical processes that occur in both lakes the co2 emission is mostly associated to a biogenic origin but the higher co2 emissions measured in santiago lake suggest that a volcanic influence cannot be excluded as also shown through the heavier 13c isotopic measured in this water body the tectonic structures that cross santiago lake probably enable the observed degassing

co2 emissions from fogo intracaldera volcanic lakes sao miguel island acores a tool for volcanic monitoring abstract a geochemical study was carried out at fogo lake during june 2016 in one of the deepest lakes on sao miguel island as well as on small associated pond in order to identify possible anomalous degassing areas fogo lake is located inside the summit caldera of fogo volcano one of the three active central volcanoes that dominate sao miguel geology the hydrogeochemical profile carried out along the water column of the fogo lake suggests that the lake was thermally stratified corresponding to poorly mineralized and cold na cl type waters the same composition is found in the small pond but with a slight ca enrichment to measure the co2 flux at the lake surface the modified accumulation chamber method was used and a total of 1696 measurements were accomplished covering an area of approximately 1 56 km2 measured co2 flux values are relatively low ranging from 0 to 28 4 g m 2 d 1 mean 2 6 g m 2 d 1 and from 2 1 to 15 0 g m 2 d 1 mean 6 3 g m 2 d 1 respectively at fogo lake and at the small pond the very low values measured in the central area of fogo lake are associated with the monomictic character of the lake as the co2 is not able to ascend into the surface when the water column is stratified during the warmer period statistical analyses suggest that the co2 emission is associated with a single source of co2 probably biogenic a similar signature is pointed by the water 13c isotopic content the estimated total co2 emissions from the fogo lake was approximately 4 04 t d 1 much higher than the value observed at the small pond 0 19 t d 1

carbon dioxide dynamics in kelud volcanic lake 1 in november 2007 the extrusion of a new lava dome evaporated kelud volcanic lake in java indonesia four months before a detailed echo sounding survey of the volcanic lake coupled to floating accumulation chamber measurements detected abnormally high carbon dioxide emissions it constituted the earliest sign of the volcanic unrest well before any other monitored parameter co2 flux is quantified using an empirical equation based on the volume of bubbles backscattered in the water column its comparison with the fluxes retrieved from the floating chamber method better constrain carbon dioxide dynamics in the volcanic lake it reveals that 70 of the carbon dioxide enters the lake in a dissolved form while the remaining 30 is supplied to the lake on a gaseous state almost three quarter of the ascending bubbles dissolve in the water column leaving the majority of the 330 tons day 1 of carbon dioxide diffusing at the air water interface

non volcanic co2 earth degassing case of mefite d ansanto southern apennines italy mefite d ansanto southern apennines italy is the largest natural emission of low temperature co2 rich gases from non volcanic environment ever measured in the earth

intense magmatic degassing through the lake of copahue volcano 2013 2014 here we report on the first assessment of volatile fluxes from the hyperacid crater lake hosted within the summit crater of copahue a very active volcano on the argentina chile border our observations were performed using a variety of in situ and remote sensing techniques during field campaigns in march 2013 when the crater hosted an active fumarole field and in march 2014 when an acidic volcanic lake covered the fumarole field in the latter campaign we found that 566 to 1373 t d 1 of so2 were being emitted from the lake in a plume that appeared largely invisible this combined with our derived bulk plume composition was converted into flux of other volcanic species h2o 10989 t d 1 co2 638 t d 1 hcl 66 t d 1 h2 3 3 t d 1 and hbr 0 05 t d 1 these levels of degassing comparable to those seen at many open vent degassing arc volcanoes were surprisingly high for a volcano hosting a crater lake copahue s unusual degassing regime was also confirmed by the chemical composition of the plume that although issuing from a hot 65 c lake preserves a close to magmatic signature eq3 6 models of gas water rock interaction in the lake were able to match observed compositions and demonstrated that magmatic gases emitted to the atmosphere were virtually unaffected by scrubbing of soluble s and cl species finally the derived large h2o flux 10 988 t d 1 suggested a mechanism in which magmatic gas stripping drove enhanced lake water evaporation a process likely common to many degassing volcanic lakes worldwide

syntectonic deposits and punctuated limb rotation in an albian submarine transpressional fold mutriku village basque cantabrian basin northern spain deep water syntectonic deposits and angular unconformities record the denudation and deformation history of the middle cretaceous aitzeta structure interpreted here as a monoclinal syncline associated with the high angle reverse mutriku fault basque cantabrian basin northern spain sedimentological and structural analyses combined with a precise chronostratigraphy based on ammonites permit us to document in detail the history of this syncline during 0 53 m y late albian callihoplites auritus subzone tectonism occurred during two major and two minor short lived pulses the sedimentary signatures of these pulses include unconformities and resedimented deposits derived from the uplifted rocks showing inverted clast stratigraphy in contrast intervening phases of tectonic calm were characterized by gentle hemipelagic sedimentation the major tectonic pulses were characterized by strong rotation and uplift of the syncline limb the two major pulses coincided with the lower and upper limits of the auritus subzone respectively and resulted in the following limb rotation and uplift values 42 and 250 m in the first pulse and 66 and 100 140 m in the second pulse a maximum duration of 0 12 m y for each major pulse has been calculated from which limb rotation and uplift rates of 0 35 k y and 2 08 m k y first pulse and 0 55 k y and 0 83 1 16 m k y second pulse are estimated growth strata and angular unconformity geometries temporal variation of deformation rates and bedding parallel faulting indicate folding by progressive limb rotation and associated flexural slip local northwest southeast compression is deduced in formation of the aitzeta syncline the presence of bedding parallel oblique faulting and minor drag folds suggests a component of right oblique movement along the mutriku fault

an explosive convective cloud system and its environmental conditions in mjo initiation observed during dynamo an unusually large explosive convective cloud system was observed over the equatorial indian ocean on 28 november 2011 during the dynamo dynamics of the madden julian oscillation mjo field campaign the significance of this mesoscale convective system mcs is its size and explosive development of cold cloud tops 96 c during the initiation of a strong mjo event observations from the dynamo show that the large mcs developed within a well defined synoptic scale cyclonic circulation associated with an equatorial low pressure system with characteristics of a mixed rossby gravity wave that dominated the flow in the dynamo array prior to the development of the mcs the equatorial flow was characterized by strong vertical wind shear with low level westerlies and upper level easterlies a region of decreased wind shear and enhanced upper level divergence emerged concurrently with the passage of the westward moving mixed rossby gravity wave related low pressure system and convective activity in situ sounding observations suggest that widespread deep convection upstream of the large mcs may have contributed to the reduction of the upper level easterlies through vertical momentum transport and convective outflow both the reduction in vertical wind shear and enhanced low level convergence induced by the equatorial low pressure system created a favorable environment for the rapid development of the mcs this study examines the development of the mcs and the associated synoptic scale equatorial low pressure system within the large scale mjo circulation using in situ sounding observations from dynamo which provide new insights into the interaction between convection and environmental flow during mjo initiation over the equatorial indian ocean

the role of tropical waves in tropical cyclogenesis abstract this paper analyzes relationships between tropical wave activity and tropical cyclogenesis in all of the earth s major tropical cyclone basins twenty nine years of outgoing longwave radiation data and global reanalysis winds are filtered and analyzed to determine statistical relationships between wave activity in each basin and the corresponding cyclogenesis composite analyses relative to the storm genesis locations show the structures of the waves and their preferred phase relationships with genesis five wave types are examined in this study including mixed rossby gravity waves tropical depression type or easterly waves equatorial rossby waves kelvin waves and the madden julian oscillation the latter is not one of the classical tropical wave types but is a wavelike phenomenon known to have a strong impact on tropical cyclogenesis tropical cyclone formation is strongly related to enhanced activity in all of the wave filter bands except for the kelvin band in each basin the structure o

topographic influence on the mjo in the maritime continent abstract this study demonstrates that during the passage of the mjo through the maritime continent in the boreal winter the corresponding deep convection and near surface wind anomalies tend to skirt around mountainous islands flow bifurcation around elongated mountainous islands such as new guinea is clearly seen topographic blocking generates distinctive vorticity and convergence distributions in this specific domain mountain wave like structures are also observed throughout the maritime continent with a clear spatial relationship with the high terrains in sumatra sulawesi and new guinea the existence of topography seems to create extra lifting and sinking within the large scale circulation and thus the convective system exhibits quasi stationary features near the major topography during the mjo passage through the maritime continent it is suggested that resolving the detailed topographic effects may play a key role in simulating realistic characteristics of the mjo in the maritime continent

mechanisms for the dipolar patterns of rainfall variability over large islands in the maritime continent associated with the madden julian oscillation abstractbefore the eastward propagating rainy envelope of a madden julian oscillation mjo arrives at the maritime continent mc some islands in the mc experience dipolar patterns of rainfall va

geometric and numerical model of progressive limb rotation in detachment folds a simple area balanced geometric model of progressive limb rotation in detachment folds allows the quantification of displacement uplift and rotation and the assessment of their effect upon growth strata geometries translation of this geometric model into a velocity model of deformation allows the modeling of associated growth strata resulting from background sedimentation and local erosion transport and deposition we show that with constant displacement and sedimentation rate this model predicts a progressive unconformity indicating the onlap and eventual overlap of the fold limb caused by a decreasing uplift rate this decrease is a consequence of the kinematics of progressive limb rotation increases in displacement rate with sedimentation rate kept constant can lead to offlap and angular unconformities although subsequent onlap does not necessarily reflect a return to a lower displacement rate modeled growth strata geometries exhibit many of the features reported from the literature

unfolding an inverse approach to fold kinematics preservedfoldshapesusuallyreveallittleabouttheirkinematicevolution syntectonic strata preserved in growth synclines in contact with a fold however can permit unfolding a sequential reconstruction of fold growth backward through time from a geometry observed at present to an initial undeformed state such reconstructions can define the kinematics of fold growth growth strata associated with anticlinal forelimbs in the ebro basin exhibit depositional tapering of beds on fold flanks and progressive limb rotation unfoldingawell dateddetachmentfolddefinesitskinematicevolutionandcoevallyvarying rates of shortening forelimb uplift and forelimb rotation interplay of these rates with sedimentation rates controls onlap and offlap relations

global co2 emission from volcanic lakes the global co 2 discharge from subaerial volcanism has been estimated at 300 mt yr 1 however estimates of co 2 emissions from volcanic lakes have not been considered in order to improve this information extensive research on co 2 emissions of volcanic lakes worldwide has been performed the observed normalized average co 2 emission rates increase from alkaline 5 5 t km 2 d 1 to neutral 201 2 t km 2 d 1 to acid 614 2 t km 2 d 1 in volcanic lakes taking into account 1 normalized co 2 emission rates 2 the number of volcanic lakes in the world 769 and 3 the fraction and average areas of the investigated alkaline neutral and acid volcanic lakes the estimated global co 2 emission from volcanic lakes is 117 19 mt yr 1 with 94 17 mt yr 1 as deep seated co 2 this study highlights the importance of a revision of the actual global co 2 discharge from subaerial volcanism

volcano tectonic structures and co2 degassing patterns in the laacher see basin germany the laacher see volcano is the youngest 12 900 year bp eruption center of the quarternary east eifel volcanic field in germany and has formed laacher see the largest volcanic lake in the eifel area new bathymetric data of laacher see were acquired by an echo sounder system and merged with topographic light detection and ranging lidar data of the laacher see volcano area to form an integrated digital elevation model this model provides detailed morphological information about the volcano basin and results of sediment transport therein morphological analysis of laacher see volcano indicates a steep inner crater wall slope up to 30 which opens to the south the laacher see basin is divided into a deep northern and a shallower southern part the broader lower slopes inclined with up to 25 change to the almost flat central part maximum water depth of 51 m with a narrow transition zone erosion processes of the crater wall result in deposition of volcaniclastics as large deltas in the lake basin a large subaqueous slide was identified at the northeastern part of the lake co2 degassing vents wet mofettes of laacher see were identified by a single beam echo sounder system through gas bubbles in the water column these are more frequent in the northern part of the lake where wet mofettes spread in a nearly circular shaped pattern tracing the crater rim of the northern eruption center of the laacher see volcano additionally preferential paths for gas efflux distributed concentrically inside the crater rim are possibly related to volcano tectonic faults in the southern part of laacher see co2 vents occur in a high spatial density only within the center of the arc shaped structure barschbuckel possibly tracing the conduit of a tuff ring

carbon sources in arc volcanism with implications for the carbon cycle new co2 3 he data from the east sunda arc indonesia confirm earlier observations that arc volcanic gases have higher co2 3 he ratios than mor environments on average 80 of arc volcanic co2 is recycled exogene carbon addition of a few percent of carbonate bearing sediments to the mantle wedge explains much of the carbon abundance andcarbon isotopic data of arc gases but can not explain the he isotope observations the co2 3he in arc volcanoes is not strongly dependent on the composition of modem trough sediments e g deep sea clays vs carbonate rich sequences and calcite veins in the hydrothermally altered subducted slab may provide a contribution to the recycled carbon flux of arcs the sum of globally deep subducted sediment and slab carbon exceeds the estimated arc co2 flux and approximately 3 5 teramole of carbon may return annually to the mantle in convergent zones the modem combined processes of mor volcanism slab alteration and subduction volcanism do not produce a substantial carbon flux into the exosphere and rate changes in ocean floor spreading are unlikely to cause major changes in atmospheric co2 as a result of changes in the volcanic co2 fluxes intense pulses of flood basalt volcanism however may alter the co2 contents of the atmosphere over the course of a millenium or so and influence global climate

the co2 flux from hydrothermal systems of the karymsky volcanic centre kamchatka abstract the co 2 flux provided by the hydrothermal activity within the karymsky volcanic centre kamchatka was measured and the co 2 balance of the karymsky caldera lake was estimated in the framework of a deep carbon observatory dco project the karymsky volcanic centre located in the se of the kamchatka peninsula in the middle of the modern volcanic front consists of two calderas hosts a caldera lake and is characterized by hydrothermal activity that is manifested at several thermal fields within the akademii nauk an caldera which is filled by a caldera lake the akademii nauk springs discharge boiling water into the lake the lake is drained by the karymsky river that then crosses the caldera of the karymsky volcano karymsky caldera and drains the thermal field of co 2 rich karymsky springs the lake after the 1996 sublimnic eruption is in a steady state condition with the total dynamic co 2 budget of about 4 t day and has a total amount of co 2 stored inside of the lake of around 8000 t the thermal springs of the karymsky caldera drained by the karymsky river enrich the river in dissolved carbon species a total co 2 output of 320 t day from both karymsky centre calderas was estimated carrying around 130 t day carbon species expressed as co 2 as dissolved species hco 3 and co 2 aq and emitting to the atmosphere around 190 t day of co 2 as the diffusion flux from the soil and bubbling emanations from the springs

kelvin waves and tropical cyclogenesis a global survey abstractconvectively coupled atmospheric kelvin waves are among the most prominent sources of synoptic scale rainfall variability in the tropics but large uncertainties surround their role in tropical cyclogenesis this study identifies the modulation of tropical cyclones relative to the passage of a kelvin wave s peak rainfall i e its crest in each basin tropical cyclogenesis is generally inhibited for 3 days before the crest and enhanced for 3 days afterward composites of storms forming in the most favorable lags illustrate the dynamical impacts of the waves in most basins the tropical cyclone actually forms during the convectively suppressed phase of the wave the 850 hpa equatorial westerly anomalies provide the cyclonic vorticity for the nascent storm and 200 hpa easterly anomalies enhance the outflow the wind anomalies persist at both levels longer than the kelvin wave s period and are often related to the madden julian oscillation mjo the onset of these wind anomalies occurs with the

volcanic lake systematics i physical constraints volcanic lakes have a wide range of characteristics and we make an attempt to delineate the limiting physical conditions for several lake classes the ratio between heat input and heat dissipation capacity of a lake constrains the temperature for perfectly mixed steady state volcanic lakes poorly mixed lakes are also conditioned by this ratio but their temperature structure is also strongly influenced by the hydrodynamics resulting from different mechanisms of heat transfer the steady state temperatures of volcanic lakes are largely determined by the magnitude of the volcanic heat influx relative to the surface area of the lake small lakes have only a small capacity for heat dissipation and their temperature rises quickly with only small heat inputs large lakes are buffered against variations in heat input both the heat dissipation and meteoric water input into a lake are functions of lake surface area and therefore each lake water temperature demands a certain precipitation rate for mass conservation independent of lake size the results of energy mass balance modeling shows that under common atmospheric conditions most steady state volcanic lakes are unlikely to maintain a temperature in excess of 45 50 c validation of the volcanic lake model was performed using published data from yugama lake japan and the keli mutu lakes indonesia also the model was applied to 24 natural systems to provide a baseline assessment of energy fluxes under the model assumptions so future work on those systems can identify nuances in individual systems that deviate from the simple model conditions we recommend the model for use in assessing temperature variations and volcanic lake stability in settings with known physical and atmospheric conditions application of the energy mass balance calculations of model lakes provides a genetic classification scheme largely based on physical process parameters

volcanic lakes of the azores archipelago portugal geological setting and geochemical characterization abstract a representative set of 30 lakes from the azores archipelago portugal has been studied to obtain data on their volcanic setting and water geochemistry the majority of the studied lakes are located inside volcanic craters and subsidence calderas while the remaining lakes are located in topographic depressions not associated with volcanic centres in depressions of tectonic origin and inside lava caves in general the azorean volcanic lakes are small with surface areas between 8 94 10 4 km 2 and 4 35 km 2 and volumes between 2 4 10 3 and 4 78 10 7 m 3 median 3 99 10 4 m 3 presenting maximum depths between 0 8 and 33 m mostly of the na cl to na hco 3 type the lake waters are generally low temperature 11 9 24 6 c very dilute tds range between 11 0 and 356 2 mg l median 36 8 mg l and a clear exception is furna do enxofre lake graciosa island that shows a mg trend two types of lake waters can be recognized 1 one is characterized by na cl ratio close to the seawater value and have evolved and evolve by marine contribution and 2 na hco 3 type waters that in addition to sea salt input have been influenced by other processes e g water rock interaction hydrothermal seepage into the lake bottom evident from higher total co 2 content 365 1 mg l and sio 2 content 74 9 mg l as well demonstrated by in the furna do enxofre lake nevertheless volcanic contribution cannot be excluded for some lakes as furna do enxofre vertical profiles made at the deepest lakes of sao miguel reveal that major ion content varies little with depth largely independent of the occurrence of thermally driven density stratification in summer for some lakes however dissolved co 2 increases with depth and is kept in the hypolimnion in summer whereas the hco 3 content is stable suggesting that co 2 release exceeds acidity neutralization by water rock interaction during winter without stratification the dissolved co 2 increase is less sharp for the majority of the lakes with the exception of furnas and furna do enxofre lakes the co 2 enrichment observed for certain lakes e g furna do enxofre and furnas implies a volcanic input moreover as these lakes themselves are located near hydrothermal surface manifestations they therefore offer good targets of volcano monitoring in the azores

rift margin extensional forced folds and salt tectonics in the eastern basque cantabrian rift basin western pyrenees abstract in this paper we present and discuss cretaceous extensional folds of the eastern basque cantabrian basin northern spain geometry and kinematics of folds is constrained by means of structural and sedimentological fieldwork integrated with geological mapping revealing an intimate link between coeval folding extensional faulting and salt mobilization in detail the mesozoic succession of the northwestern and southern borders of the palaeozoic bortziriak cinco villas massif eastern margin of the bcb host late albian early cenomanian syn rift forced folds the studied forced fold axes trend parallel and are located above main and inferred cretaceous syn sedimentary basement faults structural data indicate that these folds formed during the late albian early cenomanian interval the presence of upper triassic clay and evaporite outcrops along and or close to the axes of folds and their stratigraphic relationship with upper cretaceous strata indicate their halokinetic origin and extrusion during folding the trigger of salt tectonics is attributed to a basement extensional pulse during the bay of biscay pyrenean rifting related high subsidence rates allowed salt to flow towards faults forming salt walls and causing the inflation and folding of the overburden

carbon dioxide bursts of lake nyos cameroon modelled as periodic supersaturation in a countercurrent reactor abstract large scale degassing of carbon dioxide from lake nyos cameroon on august 21 1986 was caused by local gas supersaturation within the lake water carbon dioxide of volcanic origin accumulates in the lake but the dissolved solids originate from leaching of the bedrock atmospheric and organic nitrogen diffuses into the lake from its surface the lake is modelled as a countercurrent chemical reactor carbon dioxide bubbles rising from the bottom sediment dissolve as aqueous co2 which control the ph of the water at about 3 8 siderite formed within the lake settles and counteracts the upwards transport of co2 rising co2 bubbles also account for upwards transport of dissolved nitrogen local gass supersaturation causes a spontaneous large scale degassing event giving rise to catastrophic bursts of co2 chemical hazard evaluation at lake nyos can only be based on monitoring of total dissolved gases since variables such as conductivity and ph are insensitive to changes in aqueous co2 hazard prevention at lake nyos can be accomplished due to the great volume of annual precipitation relative to the volume of the lake by damming of the natural outlet of the lake and draining of the co2 rich bottom layer through a pipeline resulting in the gradual replacement of the gas rich bottom layer

a numerical study on the influences of sumatra topography and synoptic features on tropical cyclone formation over the indian ocean abstractspanning across the equator with a northwest southeast orientation the island of sumatra can exert significant influences on low level flow under northeasterly flow in particular lee vo