shallow borehole tilt a reprise we describe results from nearly a decade of tilt measurements produced by two arrays of shallow borehole tiltmeters one in a semiarid environment at pinon flat observatory pfo california depth of burial 4 5 m and the other in a maritime arctic environment at adak alaska depth of burial 2 m although renovation and reinstallation of the instruments at the two sites reduced thermal noise it did not change the secular records significantly this implies that the large tilts observed reflect instability of the ground rather than the sensor so that deeper installations should give better results the pfo data show large rainfall related tilts caused by near surface weathering and also periodic temperature related tilts from several thermoelastic effects the adak data are dominated by tilts from the annual temperature cycle though by a smaller amount than at pfo but at other frequencies they show essentially the same power levels as at pfo both data sets confirm earlier results that burial at such shallow depths even in apparently stable material is inadequate for the measurement of tectonic tilts

precision of seafloor gravity and pressure measurements for reservoir monitoring changeswithgravityovertimehaveproventobevaluable forinferringsubsurfacedensitychangesassociatedwithproduction from oil and natural gas reservoirs such inferences allowthemonitoringofmovingfluidfrontsinareservoirand provideanopportunitytooptimizeproductionoverthelifeof the reservoir our group began making time lapse seafloor gravityandpressuremeasurementsin1998 todate wehave surveyed sixfields offshore norway we have made three repeatsurveysatonefieldandonerepeatsurveyatanother we incorporated a land gravity sensor into a remotely operated seafloor housing three such relative gravity sensors mountedinasingleframearecarriedbyaremotelyoperatedvehicle rov to concrete benchmarks permanently placed on the seafloor reference benchmarks sited outside the reservoir boundaries are assumed to provide stable fiducial points typicalsurveyslastfromafewdaystoafewweeksandcover from8to80benchmarks withmultipleobservationsofeach in our earliest surveys we obtained an intrasurvey repeatability of approximately 20 gal but recently we have been achieving 3 gal repeatability in gravity and approximately 5 mminbenchmarkdepthdeducedfromsimultaneouslyrecorded ambient seawater pressure we attribute the improved precision to several operational factors including the use of multiple gravity sensors frequent benchmark reoccupation precise relocation and orientation of the sensors repeated calibrations on land and minimization of vibrational and thermal perturbations to the sensors we believe that high precision time lapse gravity monitoring can be used to trackchangesintheheightofagas watercontactinaflooded reservoir withaprecisionofafewmeters

phosphatic limestones from tuvalu ellice islands phosphatic limestones and associated soils occur on each of the nine islands of tuvalu central pacific deposits range from gram sized crusts to 500 000 metric tons carbonate hydroxylapatite dahllite forms multilaminar botryoidal crustose cement around calcareous bioclasts which it sometimes replaces consolidated rock occurs as hardpan with unconsolidated phosphatic layers above and below the genetic relationship of phosphatic limestone to unconsolidated phosphatic sediments and to phosphatic soil is unclear phosphatization has occurred either continuously or episodically within the vadose zone for at least 2 000 yrs while relative sea level has fluctuated the present deposits are exhumed accumulations of apatite formed at earlier higher holocene sea levels with phosphorous derived from possibly both terrestrial and marine organisms including birds plants and degradation of the bioclastic calcareous substrate humic complexes could enable phosphate to enter the lensoid fresh water table degradation of these humic complexes would liberate free hpo super 2 4 with subsequent precipitation of apatite under suitable conditions of alkalinity and carbonate and magnesium activity pisonia grandis should not be regarded as a geobotanical indicator of phosphate deposits in present day tuvalu

composition of characteristic soils on the raised atoll bellona solomon islands abstract knowledge is scarce about the composition of soils on bellona and other pacific atolls such knowledge is important as it is closely related to sustainable land use of these special soils formed on carbonatic phosphatic materials therefore the micromorphological chemical and mineralogical composition of samples from genetic horizons in three dominant bellonese soils malanga kenge ungi and kenge toaha and underlying rock tanahu were investigated tanahu mainly consists of dolomite but this mineral is absent in the three soils which are dominated by phosphate containing minerals the malanga soil is strongly dominated by ca and p with minor amounts of al f and fe present in fluorapatite hydroxyapatite and crandallite in contrast al fe and p dominate in the kenge ungi and kenge toaha soils in accordance with a mineralogy consisting of crandallite together with aluminum oxides gibbsite boehmite and iron oxides mainly goethite with minor contents of hematite the observed carbonate for phosphate substitution in the apatites and crandallite is important as it indicates an increased phosphate availability in the soils all three soil samples contain 1 si and very little k and mg total contents of essential microelements are considered adequate but the rather high contents of sr and u especially in the kenge ungi soil may be problematic although the composition of the soils suggests substantial fertility and resilience the lack of k containing weatherable minerals silicate minerals is in line with a very low k and low mg content and explains why fertilization may be needed to sustain future cultivation of these special soils due to a possible low bioavailability of fe mn and maybe other micronutrients at the circumneutral ph of these carbonatic phosphatic soils as well as the rather high contents of sr and u it may be recommended to test element availability using appropriate chemical soil tests supplemented by plant experiments to ensure safe and sustainable optimal soil use however according to the local farmers the malanga kenge toaha and kenge ungi soils are considered well suited for production of the preferred crops

paleoenvironmental implications of the guano phosphatic cementation on dongdao island in the south china sea abstract the phosphatic cement in the bioclastic sediment sequence on the northeastern shore of dongdao island in the south china sea was studied and its paleoenvironmental implications discussed petrological characteristics and major trace ree element data unequivocally supported the notion that phosphatization was closely associated with avian guano decomposition and leaching whereas carbon and oxygen isotope results further revealed that meteoric water were involved in these processes ams 14 c dates on the brown phosphate cements indicate that they were formed around 5700 5000 5100 and 2900 yr bp respectively the multi episodes of phosphatization very likely correspond to intermittent seabird occupation on this island possibly reflecting holocene sea level oscillation and or long term climate changes in the south china sea that have controlled seabird habitat the phosphate cementation which occurs widely in tropical islands may be another useful monitor for sea level and or paleoclimate changes

a revised conceptual model of the tropical marine boundary layer part iii bragg scattering layer statistical properties abstractthis paper examines the structure and variability of the moisture field in the tropical marine boundary layer tmbl as defined by bragg scattering layers bsls observed with s band radar typically four to five bsls were present in the tmbl including the transition layer at the top of the surface based mixed layer the transition layer depth 350 m exhibited a weak diurnal cycle because of changes in the mixed layer depth bsls and the clear layers between them each had a median thickness of about 350 m and a lifetime over the radar of 8 4 h with about 25 having lifetimes longer than 20 h more fewer bsls were present when surface winds had a more southerly northerly component both bsls and clear layers increased in depth with increasing rain rates with the rainiest days producing layers that were about 100 m thicker than those on the driest days the analyses imply that the relative humidity rh field in the tmbl exhibits layering on scales observable by radar satellite and wind

the geochemical role of atoll phosphates on vaitupu nukulaelae funafuti and neighbouring low islands of tuvalu central pacific bioclastic limestones cemented by dahllite carbonate hydroxy apatite admixed with organic mucilage are a normal aspect of low island geology occurring on at least eight of the nine islands of the central pacific archipelago of tuvalu analyses of rocks associated soils groundwaters and vegetation from three islands show concentrations of phosphorus range from 102 g g in the fresh groundwater through 102 104 g g in the calcareous substrate and terrestrial flora to 104 g g in terrestrial fauna the phosphatic limestones have concentrations two orders of magnitude greater than in the non phosphatized substrate precipitation of apatite occurs in the vadose zone following transport of phosphorus from the surface as a humate complex and in response to prevailing bicarbonate alkalinity high calcium concentration net ionic strength and moderate ph formation of mineral phosphate provides a stable geochemical sink for excess phosphorus cycling through the atoll s ecosystem immobilizing the element and effectively removing it from further participation in an island s geochemical cycle a combination of physical and chemical factors may control deposition of the apatite including climate sea level changes and composition of the substrate and its connate waters

isotope studies of insular phosphates explain atoll phosphatization carbonate apatite1 with the general formula ca10 po4 co3 6 f oh 2 is a major component of the phosphate deposits that occur on numerous coral reef islands2 6 such insular pohsphates are generally accepted to be the result of chemical interaction between solutions leaching seabird guano and the underlying reef limestone2 7 details of this process however and the specific environmental conditions which promote it are not yet fully understood8 we present here oxygen and carbon isotope data from carbonate apatites which elucidate the process of phosphogenesis on the pacific atolls and the palaeoclimatic conditions in which it occurs we suggest that there were drier climates in the tropics during the quaternary ice ages associated with an extension of equatorial upwelling in the pacific

coated phosphate grains proxy for physical chemical and ecological changes in seawater irrespective of geologic age phanerozoic coated phosphate grains deposited beneath productive surface waters in organic rich paleoenvironments are of only two types unconformity bounded grains contain internal discordances and erosional surfaces attributable to multiple episodes of phosphogenesis and sedimentary reworking during periods of stratigraphic condensation redox aggraded grains consist of concordant concentric phosphate laminae that are intimately interlayered with circumgranular layers containing pyrite chamosite or barite recording in situ diagenetic mineralization driven by changes in pore water redox potential such changes can be attributed to variations in biological oxygen demand within suboxic pore water environments resulting from fluctuations in sedimentation rate of organic carbon redox aggraded grains are thus sensitive indicators of variations in organic carbon export and record changes in primary productivity and or ecological dynamics of the surface ocean this concept of coated grain formation necessitates a long residence time just below the sediment water interface if sedimentation rate is too high grains are rapidly buried and so removed from the zone of active phosphate precipitation coated phosphate grains can therefore be considered the granular equivalents of condensed beds these concepts are equally applicable to the interpretation of other types of coated grains and concretions that contain eh sensitive minerals such as iron bearing ooids and polymineralic concretions

diurnally modulated cumulus moistening in the preonset stage of the madden julian oscillation during dynamo abstractatmospheric soundings radar and air sea flux measurements collected during dynamics of the madden julian oscillation dynamo are employed to study mjo convective onset i e the transition from shallow to deep convection in the tropical indian ocean the findings indicate that moistening of the low midtroposphere during the preonset stage of the mjo is achieved by simultaneous changes in the convective cloud population and large scale circulation namely cumuliform clouds deepen and grow in areal coverage as the drying by large scale subsidence and horizontal westerly advection wane the reduction of large scale subsidence is tied to the reduction of column radiative cooling during the preonset stage which ultimately links back to the evolving cloud population while net column moistening in the preonset stage is tied to large scale circulation changes a new finding of this study is the high degree to which the locally driven diurnal cycle invigorates convective clouds and cumulus moiste

displacement of surface monuments vertical motion several measurements of vertical ground motion at pinon flat observatory california indicate the overall weakness and instability of the earth s weathered surface with respect to the underlying rock cumulative long period motions of order 0 5 mm per year dominate these records though smaller elastic deformations caused by precipitation loading atmospheric loading and tidal strains are evident at higher frequencies all of these help to characterize the near surface material the long period records suggest that near surface weathering is the dominant influence on monument motion at least at this site on crystalline rock in a semi arid environment rainfall loading gives an average vertical modulus of 2 6 gpa for the material in the uppermost 26 m of the ground compared with 88 gpa for granite under moderate confining stress atmospheric loading gives similar results but indicates the ground is permeable to airflow at periods longer than a few hours earth tide records show poisson s ratio to be 0 09 in contrast to the normative range of 0 2 0 25 establishing that horizontal strains couple only weakly into vertical ones so that vertical strains near the surface are a poor measure of areal strain the form of the ground surface displacement power spectrum indicates that analyses of geodetic surveys would be improved with the inclusion of a monument positioning error budget that increases with time because of ground instability and the generally small rate of crustal tectonic motions deeply emplaced monuments will be needed for observational programs designed to detect short term changes in crustal deformation over baselengths of order 10 km and less

a densely spaced array of sea level monitors for the detection of vertical crustal deformation in the shumagin seismic gap alaska a network of sea level gauges has been installed with about 40 km spacing in the shumagin islands in order to detect relative vertical motion in particular possible crustal motion precursory to an expected major earthquake this required the development and deployment of a pressure sensor sea level gauge suitable for installation on remote and harsh coastlines data are collected in near real time via satellite both in order to exploit fully any precursors that may be observed and to provide continuous information on the status of the instruments using wiener filtering techniques it has been determined conservatively that no relative vertical crustal motion greater than 0 1 m between stations has occurred during 1981 1985 this is consistent with independent geodetic leveling and trilateration data though evidence exists for more rapid deformation during 1978 1980 the sea level data collected so far have an rms noise level of about 0 04 m after processing this is limited in part by the pressure sensor and associated electronics improved prressure gauges with better long term stability have recently been installed a short baseline tiltmeter operating in a tunnel has demonstrated that suitably designed and located land based tiltmeters have a lower noise level and hence better precursor detection characteristics than the sea level gauges at monthly and shorter periods

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

gravity waves generated by convection during twp ice i inertia gravity waves gravity waves are analyzed in radiosonde soundings taken during the tropical warm pool international cloud experiment twp ice campaign the properties of the inertia gravity waves are analyzed in part i whereas part ii focuses on high frequency gravity waves two groups of inertia gravity waves are detected group l long vertical wavelength in the middle stratosphere during the suppressed monsoon period and group s short vertical wavelength in the lower stratosphere during the monsoon break period waves belonging to group l propagate to the southeast with a mean intrinsic period of 35 h and have vertical and horizontal wavelengths of about 5 6 km and 3000 6000 km respectively ray tracing calculations indicate that these waves originate from a deep convective region near indonesia waves belonging to group s propagate to the south southeast with an intrinsic period vertical wavelength and horizontal wavelength of about 45 h 2 km and 2000 4000 km respectively these waves appear to originate from convection in the vicinity of new guinea

first observations of turbulence parameters in the troposphere over the bay of bengal and the arabian sea using radiosonde 1 this paper discusses the turbulence characteristics of the free atmosphere over the bay of bengal and the arabian sea during the premonsoon season of 2006 the turbulence scaling concepts developed over the past decades for application to oceanic mixing are used for retrieving turbulence properties in the free atmosphere from high resolution soundings as described by clayson and kantha 2008 the variability in the vertical turbulence structure over a large spatial region is studied using this novel method for the first time investigations revealed the presence of a highly turbulent band at upper troposphere below the cold point tropopause cpt with significant enhancements in thorpe length and eddy diffusion coefficient this increased turbulence is studied in conjunction with the observations of the tropical tropopause layer ttl it is seen that the lower and upper boundaries of this turbulence band nearly coincide with the height where the potential temperature lapse rate begins to show a decrease lrhmin and cold point tropopause respectively the ttl is the transition regime from convectively dominated troposphere to radiatively dominated stratosphere and is characterized by a decrease in the static stability the enhanced zonal and meridional wind shear observed in this region shows that the stability in this region is further weakened because of the breaking of kelvin helmholtz waves which results in the enhancement of turbulence the study reveals the potential of high resolution soundings to be used in the investigations of turbulence in the free atmosphere

alterations in guano phosphates and mio pliocene carbonates of table mountain santa barbara curacao abstract the table mountain santa barbara consisting of the mio pliocene seroe domi limestone formation was probably covered with a guano layer in the pleistocene solutions carrying guano derived phosphate percolated downwards resulting in partial phosphatization of the underlying limestones only two phosphate minerals are present in the table mountain apatite and whitlockite phosphatization includes both replacement of the original carbonate or pre phosphate dolomite and cementation in primary as well as secondary porosity cryptocrystalline isotropic phosphate cement micro crystalline apatite isopachous apatite fringe cement multiple zoned apatite crusts rhombic whitlockite cements two factors controlled the final distribution of the phosphate within the table mountain firstly changing positions of the sea level and therefore of the diagenetic environments determined the overall distribution of the phosphatized interval a horizontal layer 98 128 m above sea level sandwiched between two non phosphatized limestone units original carbonate facies and mineralogy was the second controlling factor causing the final variations in degree of phosphatization the limestones comprise two lithofacies a coralliferous limestone lenses erratically distributed amidst and b micritic limestones these coralliferous limestones are phosphatized preferentially forming so called phosphate pockets sharply outlined within a non phosphatized micritic limestone host these pockets are characteristically organized into five zones which are described in detail higher original porosity permeability of the coralliferous limestone lenses as compared to the micrites additionally enhanced by a phase of pre phosphate dolomitization determined preferential phosphatization of this facies type a second controlling factor was the original carbonate mineralogy and resulting dia

leveling precision and bench mark motions pinon flat observatory california the reliability of relative vertical motions detected by levelings of bench marks installed at pinyon flat is highly dependent on the kinds of bench marks installed for monitoring purposes the most stable marks are the end monuments for two 535 m long fluid tiltmeters nine direct measurements of average slope between tiltmeter end monuments agree to within a standard deviation about the mean of 0 2 mm 0 4 rads comparable to the slope measured by the tiltmeters themselves motions of class b steel rod marks are random with standard deviations ranging from 0 5 to 3 2 mm averaging 1 0 mm the motions of nearly all rod marks decreased greatly in the fourth year evidently because of a time dependent establishment of stability in the decomposed granite fundament other kinds of bench marks are stable between 0 5 and 0 8 mm tectonic tilt is not revealed in 15 levelings of the array in 4 years consistent with the tiltmeters but the random bench mark motions dominate the errors in the estimated tilt

evidence of gravity wave saturation and local turbulence production in the summer mesosphere and lower thermosphere during the state experiment this study utilizes the unique data set obtained during the structure and atmospheric turbulence environment state experiment conducted during june 1983 at poker flat alaska to examine the structure and characteristics of the wave field near the summer mesopause it is shown that the rocket and radar data together permit a much more detailed specification of wave parameters than would be possible using either data set alone the results of this analysis suggest that the wave field near the summer mesopause is composed in general of a superposition of wave motions which act collectively to produce regions in which the wave field is convectively or dynamically unstable these regions are found to correlate well with zones of enhanced turbulence and small scale wave activity suggesting the processes and effects of wave field saturation

water table effects on the measurement of earth strain abstract forced changes in the water head within a granite penetrating borehole were found to induce anomalously large free surface strains and tilts in the vicinity of the hole this deformation is shown to be due to fluid pressure induced changes in the aperture of a compliant hydraulically conductive fracture at a depth of 100 m and a quantitative analysis of the deformation data is performed to recover fracture characteristics the importance of the effect for secular earth strain measurements is discussed in the light of the ubiquitous nature of both water table fluctuations and fractures in the shallow crust

oxygen isotopes of phosphate and the origin of island apatite deposits abstract in an attempt to test the hypothesis that insular phosphorites on high islands e g nauru formed by chemical reactions between seabird guano and carbonate the oxygen isotope compositions of phosphate 18op in modern guano and in the apatite component of phosphorites of various ages and locations have been investigated guano from several species of seabird appears to have 18op values that are in equilibrium with the ambient seawater temperature at each site however recent apatites closely associated with modern guano can have 18op values that are as much as 2 higher than their inferred guano phosphate source this shift in 18op values could be the result of isotopic re equilibration with percolating meteoric waters which have been enriched by evaporative processes in the upper part of the soil profile bacterial degradation of the guano in the soil zone is a possible mechanism for resetting the 18op values in this environment ancient apatites on high islands such as nauru ocean island and makatea have 18op values that are significantly lower than the 18op values of recently formed apatites the results indicate that ancient apatite deposits could not have formed by processes similar to those forming recent apatites without unreasonably high palaeotemperatures and or equilibration with water with much lower 18o values such as meteoric water in a karstic terrain at the time of maximum infiltration if the 18op values in apatite are subject to modification during subaerial weathering and diagenesis perhaps aided by the metabolic activity of micro organisms the application of 18op signatures of insular phosphorites to palaeoenvironmental reconstructions is limited to post depositional history and provides few clues to original setting

residual layer effects on the modeling of convective boundary layer growth rates with a slab model using fife data 1 the ability of slab models for the growth of the convective boundary layer cbl to work in the presence of residual layers above is analyzed in detail with a large data set from the first international satellite land surface climatology project field experiment fife 87 and fife 89 experiments we confirm that the critical element that allows the models to predict the growth as the cbl coalesces with the residual layer is the adoption of a variable lapse rate above the growing cbl this is not a new finding per se as several previous studies in the literature have adopted this strategy different parameterizations of a slab model based on the turbulence kinetic energy budget at the top of the cbl were tested and the inclusion of the storage and dissipation terms did not improve the model among the alternatives for choosing the lapse rate as the cbl grows fair results are obtained with a simple choice of two values with absolute mean errors of the order of 270 m for cases with and without a residual layer both lapse rates representative of the residual layer and the free atmosphere are obtained from the first morning sounding finally an alternative model for the cbl growth into a residual layer that assumes a zero lapse rate above the cbl did not perform well with the fife data

radiosonde observations of partially trapped lee waves over tasmania australia a well defined family of lee waves over southern tasmania australia is analyzed using a routine radiosonde sounding released from hobart at 1100 utc june 18 1991 pronounced fluctuations in the ascent rate of the radiosonde are analyzed using a new technique called the horizontal projection method the dominant horizontal wavelength is found to be 8249 m an advanced very high resolution radiometer avhrr infrared satellite image at 1554 utc is used to check this calculation and gives a horizontal wavelength of 8 9 1 4 km the horizontal projection method takes account of the vertical variation of background flow and the trajectory of the radiosonde when the scorer parameter is a strong function of height as is the case with the 1100 utc sounding it is inappropriate to assume that the vertical wavenumber is constant with height in particular the vertical wavelength at low levels is about 4 5 km the waves become evanescent between the heights of 2 5 km and 9 km and above that the vertical wavelength is typically 10 15 km as a consistency check linear wave theory is used to calculate the resonant wave modes supported by the background profiles of wind and potential temperature these are the wave modes that are most likely responsible for the lee wave clouds seen in the avhrr satellite image the horizontal wavelength for the resonant wave mode is 8188 m in agreement with the estimates based on the avhrr satellite image and from the horizontal projection method the paper highlights the dangers of interpreting radiosonde soundings as vertical snapshots of the atmosphere and assuming that the vertical wavenumber can be characterized by a single value it is shown that treating the radiosonde sounding as a vertical profile and analysing wave like structures in the ascent rate using standard spectral methods gives an incorrect vertical wavelength of 1906 238 m the paper concludes that operational radiosonde soundings can be used to make accurate quantitative measurements of orographically generated waves provided that the vertical variation in the background flow and the motion of the radiosonde through the wave field are taken into account

displacement of surface monuments horizontal motion measurements of tectonic deformation depend on both accurate instrumentation and adequate coupling of the apparatus to the earth s crust existing techniques capable of resolving the signals of interest strain rates of 10 n yr are mainly observatory based the limitation in the baselength of these instruments 1 km results in a requirement that the reference monuments be exceptionally stable 10 tzm yr however records from pition flat observatory california show that the actual horizontal displacements for massive near surface monuments eraplaced in competent weathered granite are of the order of 50 tzm yr the low noise level of the strain measurements at this site indicates that this magnitude of monument displacement is abnormally small until high accuracy geodetic techniques are developed sophisticated monuments or monument monitoring devices will be necessary to record faithfully continuous crustal deformation

reasons for the extremely high ranging planetary boundary layer over the western tibetan plateau in winter abstractthe planetary boundary layer pbl over the tibetan plateau with a mean elevation about 4 km above sea level reaches an unmatched height of 9515 m above sea level the proximity of this height to the tropopause facilitates an exchange between the stratosphere and the boundary layer however the underlying mechanisms responsible for this unique pbl have remained uncertain here the authors explore these mechanisms and their relative importance using measurements of the pbl the associated surface fluxes and single column and regional numerical simulations as well as global reanalysis data results indicate that the dry conditions of both ground soil and atmosphere in late winter cannot explain the special pbl alone rather the results from a single column model demonstrate the key influence of the stability of the free atmosphere upon the growth of extremely deep pbls over the tibetan plateau simulations with the numerical weather prediction model consortium for small scale modelling cosmo

a seafloor long baseline tiltmeter long term monitoring of seismicity and deformation has provided constraints on the eruptive behavior and internal structure and dynamics of subaerial volcanoes but until recently such monitoring of submarine volcanoes has not been feasible little is known about the formation of oceanic crust or seamounts and we have therefore developed a stand alone long baseline tiltmeter to record deformation on active seafloor volcanoes the instrument is a differential pressure two fluid sensor adapted for use on the seafloor combined with an autonomous data logger and acoustic navigation release system the tiltmeter can be installed without use of remotely operated vehicles or manned submersibles and to first order is insensitive to noise driven by temperature or pressure gradients we recorded 65 days of continuous data from one of these tiltmeters on axial seamount on the juan de fuca ridge during a multidisciplinary experiment that included ocean bottom seismographs magnetotelluric instruments and short baseline tiltmeters after instrument equilibration the 100 m iono tiltmeter provided a record with long term drift rates of 0 5 5 rad day and higher frequency variations of the order of 5 10 rad comparison with records of subaerial volcanic tilt shows that this instrument can discriminate volcanic deflation events though none occurred during our deployment a conclusion supported by nearby short baseline tilt and bottom pressure recordings the short and long baseline data constrain volcanic inflation of axial seamount to be below 0 5 1 rad day 1 during mid 1994 analysis of the long baseline tilt data in conjunction with electric field temperature and short baseline tiltmeter data shows that high frequency signals are largely driven by ocean currents improved coupling between the tiltmeter and seafloor should reduce this noise improve stability and drift and further enhance our ability to record tilt related to active submarine volcanism

convective characteristics of the madden julian oscillation over the central indian ocean observed by shipborne radar during dynamo abstractthis study investigates the convective population and environmental conditions during three mjo events over the central indian ocean in late 2011 using measurements collected from the research vessel r v roger revelle deployed in dynamics of the mjo dynamo radar based rainfall estimates from the revelle c band radar are first placed in the context of larger scale tropical rainfall measuring mission trmm rainfall data to demonstrate that the reduced revelle radar range captured the mjo convective evolution time series analysis and mjo phase based composites of revelle measurements both support the recharge discharge mjo theory time series of echo top heights indicate that convective deepening during the mjo onset occurs over a 12 16 day period composite statistics show evident recharging discharging features in convection and the environment population of shallow isolated convective cells sst cape and the lower tropospheric moisture increase recharge substantially approximately tw

observation of gravity wave generation and breaking in the lowermost stratosphere measurements with the aberystwyth vhf radar have revealed a striking illustration of gravity wave generation and breaking in the lowermost stratosphere horizontal wind measurements show an inertia gravity wave that was essentially monochromatic and persisted for longer than 5 days with a maximum perturbation amplitude of approximately 10 ms 1 radiosonde measurements show that this wave induced shear instability that led to intense turbulence close to the tropopause the event was associated with a highly curved jet stream over europe suggesting that geostrophic adjustment was a likely source mechanism

an investigation into shallow borehole tiltmeters shallow borehole tiltmeters are frequently used for ground deformation monitoring in volcanic areas where they are usually installed within a few meters of the surface a major problem concerns the noise affecting the installation at shallow depth where large tilt and strain are caused by temperature effects the long term stability of these instruments and the best shallow depth of installation in terms of best cost benefit are the crucial points we conducted an experiment in order to compare the signals of three shallow borehole electronic tiltmeters installed in the same place at different depths we verified the signal reliability in revealing the long term slow deformation and looked into the reduction of the temperature effects with depth we present three years of data and discuss the limits and the advantages of the different installation depths

a revised conceptual model of the tropical marine boundary layer part ii detecting relative humidity layers using bragg scattering from s band radar abstractpersistent layers of enhanced equivalent radar reflectivity factor and reduced spectral width were commonly observed within cloud free regions of the tropical marine boundary layer tmbl with the national center for atmospheric research s pol radar during the rain in cumulus over the ocean rico field campaign bragg scattering is shown to be the primary source of these layers two mechanisms are proposed to explain the bragg scattering layers bsls the first involving turbulent mixing and the second involving detrainment and evaporation of cloudy air these mechanisms imply that bsls should exist in layers with tops bases defined by local relative humidity rh minima maxima the relationship between bsls and rh is explored an equation for the vertical gradient of radio refractivity n is derived and a scale analysis is used to demonstrate the close relationship between vertical rh and n gradients this is tested using the derived radar bsl boundary altitudes 131 surface based soundings

evolution properties and spatial variability of mjo convection near and off the equator during dynamo abstractthis study investigates the evolution structure and spatial variability of madden julian oscillation mjo convection observed during the 2011 12 dynamics of the mjo dynamo field campaign generally the c band radars located in the near equatorial indian ocean shared mobile atmospheric research and teaching radar smart r on addu atoll gan and nasa toga on the r v roger revelle revelle observed similar trends in echo top heights stratiform rain fraction and precipitation feature size across the mjo life cycle these trends are closely related to changes in mid to upper tropospheric moisture sea surface temperature sst zonal wind and diagnosed vertical air motions however the evolution of convection moisture and vertical air motion at the r v mirai mirai located in the intertropical convergence zone itcz at 8 s exhibited a pattern nearly opposite to gan and revelle when the mjo was active over the equator convection was suppressed around mirai owing to induced subsiden

comparing tiltmeters for crustal deformation measurement a preliminary report a collection of high precision tiltmeters is being operated at pinon flat observatory southern california both to compare instruments and to measure tectonic deformation we report on 1 2 years of data from four of these two michelson gale long fluid tiltmeters one long center pressure tiltmeter and a shallow borehole tiltmeter the three long base instruments are all located on the same baseline with a precise leveling line running between their end monuments at nontidal frequencies only the two michelson gale instruments show some coherence 3 for periods of 2 to 4 days while the center pressure instrument is correlated with air temperature at periods from a few days to a few weeks the most stable tilt record shows a secular rate of 0 28 rad a which may be real over much longer times leveling to specially stabilized benchmarks should confirm this comparing instruments has identified more and less successful measurement techniques it appears that low noise data will most probably be produced only by relatively complex and expensive instruments though even for these the operating costs over any reasonable lifetime will exceed the capital cost even the best existing sensors must be improved to measure continuous tectonic motions

the role of shallow cloud moistening in mjo and non mjo convective events over the arm manus site abstractobservations from the atmospheric radiation measurement program arm site at manus island in the western pacific and re analysis products are used to investigate moistening by shallow cumulus clouds and by the circulation in large scale convective events large scale convective events are defined as rainfall anomalies larger than one standard deviation for a minimum of three consecutive days over a 10 10 domain centered at manus these events are categorized into two groups madden julian oscillation mjo events with eastward propagation and non mjo events without propagation shallow cumulus clouds are identified as continuous time height echoes from 1 min cloud radar observations with their tops below the freezing level and their bases within the boundary layer daily moistening tendencies of shallow clouds estimated from differences between their mean liquid water content and precipitation over their presumed life spans and those of physical processes and advection from re analysis

characteristics of kelvin waves and gravity waves observed with radiosondes over indonesia profiles of wind velocity and temperature at 0 35 km were observed by means of radiosondes in west java indonesia during november 1992 and april 1993 and used to study the behavior of various atmospheric waves in the equatorial atmosphere an oscillation of zonal winds with a period of about 27 days was found in the troposphere which was associated with variations in humidity and cloud top height kelvin waves showed phase progression beginning at cloud top height 13 16 km and were particularly enhanced near the tropopause the kelvin waves strongly modulated the tropopause structure including the tropopause height minimum temperature and atmospheric stability a hodograph analysis was applied to determine the propagation characteristics of inertial gravity waves height variation of the vertical group velocity suggests that the gravity waves were generated in the troposphere while the horizontal phase velocity distribution suggests that they were interacting with the background mean zonal winds these wave activities were enhanced when tall convective clouds passed over the site suggesting that cumulus convection seems to play a key role in generating these waves in the equatorial region

turbulence characteristics over tropical station gadanki 13 5 n 79 2 e estimated using high resolution gps radiosonde data 1 seasonal variation of the turbulence parameters refractivity structure constant cn2 eddy dissipation rate and eddy diffusivity k is presented using 3 years april 2006 to march 2009 of high vertical resolution gps radiosonde measurements over the tropical station gadanki 13 5 n 79 2 e first a correlation analysis was done in order to study the relative contributions of temperature t and relative humidity rh to the refractive index gradient m a strong positive negative correlation between m and rh t gradients is noticed up to 10 km above 10 km a strong positive correlation between m and t gradients is seen except at altitudes near the tropopause in the present study we flag the turbulent layers using the thorpe sorting method and estimate the structure constant cn2 for the turbulent layers the probability of occurrence of cn2 is derived from the cumulative distribution at each height and is found to decrease from 10 7 to 10 17 m 2 3 with height the probability of the occurrence of cn2 conditioned to the occurrence of turbulence as a function of height is derived and it is found that only the mean and the 90th percentile profile reach an altitude of 27 km the demarcation between the boundary layer and the free atmosphere as well as between the troposphere and the stratosphere are quite clear from the turbulence profile which allows us to identify the boundary layer and tropopause heights from turbulence profiles thus the present analysis introduces an alternative approach to identify the height of the boundary layer as well as the tropopause and also to characterize the probability of turbulence and thickness of turbulent eddies in the atmosphere with a finer scale size down to 5 m for the first time from a tropical latitude

a nomenclature system for granular phosphate rocks according to depositional texture abstract because of their striking textural similarities to carbonates a nomenclatural scheme for the classification and interpretation of phosphate sediments is proposed based on the dunham embry and klovan classification for carbonate rocks allochemical phosphate rocks and phosphorites comprise orthochems and allochems matrix cement ooids bioclasts intraclasts and lithoclasts to distinguish such components and their resulting rocks as being phosphatic a phos prefix is proposed i e phosclast mudstone phosclast wackestone phosclast packstone etc this classification nomenclature emphasizes fabrics as well as palaeoenvironmental criteria

origin of endogenetic micrite in karst terrains a case study from the cayman islands abstract cavities in the dolostones of the cayman formation miocene on grand cayman and cayman brae commonly contain spar calcite cements and or a variety of exogenetic derived from sources external to the bedrock and endogenetic derived from sources in the bedrock internal sediments micrite is a common component in many of these internal sediments the exogenetic micrite which is typically laminated and commonly contains fragments of marine biota originated from the nearby shallow lagoons the endogenetic micrite formed as a residue from the breakdown of spar calcite crystals by etching as constructive and destructive envelopes developed around spar calcite crystals by calcification of microbes by breakdown of calcified filamentous microbes and by precipitation from pore waters nce produced the endogenetic micrite may be transported from its place of origin by water flowing through the cavities endogenetic micrite can become mixed with the exogenetic micrite subsequently it is impossible to recognize the origin of individual particles because the particles in endogenetic micrite are morphologically like the particles in exogenetic micrite formation of endogenetic micrite is controlled by numerous extrinsic and intrinsic parameters in the cayman formation for example must endogenetic micrite is produced by etching of meteoric calcite crystals that formed as a cement in the cavities or by microbial calcification as a result the distribution of the endogenetic micrite is ultimately controlled by the distribution of the calcite cement and or the microbes factors controlled by numerous other extrinsic variables irrespective of the factors involved in its formation it is apparent that endogenetic micrite can be produced by a variety of processes that are operating in the confines of cavities in karst terrains

the occurrence of cirrus clouds associated with eastward propagating equatorial n 0 inertio gravity and kelvin waves in november 2011 during the cindy2011 dynamo campaign 1 cirrus cloud variability associated with n 0 eastward inertio gravity equatorial waves and equatorial kelvin waves both with the period of 4 days and equatorial kelvin wave with another periodicity 16 days were observed in the tropical indian ocean 8 0 s 80 5 e in november of 2011 during the cooperative indian ocean experiment on intraseasonal variability in the year 2011 cindy2011 dynamics of the madden julian oscillation dynamo field campaign using balloon borne cryogenic frostpoint hygrometers vaisala radiosondes and a shipborne high spectral resolution lidar system during early to mid november the cirrus cloud appearance corresponded primarily with high supersaturation and high relative humidity caused by the temperature disturbances associated with the 4 day waves between 12 km altitude and the cold point tropopause the cirrus clouds disappeared under the unfavorable downward wind and dry conditions that were caused by the 4 day waves although the 16 day wave was generating favorable conditions our multi instrument cirrus measurements revealed that we must consider the phases of various overlapping waves when estimating dehydration efficiency caused by cirrus clouds around the cold point tropopause

constraints on geological strain rates arguments from finite strain states of naturally deformed rocks a summary of known finite strain states is presented longitudinal strains 1 e as measured in many rocks often range from 1 to 40 and 1 to 0 025 the time span available to produce such measureable strains in young orogenic zones seems to be less than 10 m y possibly less than 1 m y which constrains conventional strain rates into the range of 10 sup 13 s sup 1 to 10 sup 15 s sup 1 for both pure and simple shear the most efficient way and much less efficient way to accumulate incremental strains respectively the ellipticity of the finite strain ellipse increases in a nonlinear manner finite strain variations in adjacent layers which give rise to features such as cleavage refraction arise with only slight differences in the strain rates within these layers

diagenetic processes associated with unconformities in carbonate successions on isolated oceanic islands case study of the pliocene to pleistocene sequence little cayman british west indies abstract the youngest part of the neogene carbonate succession on little cayman is a thin

evolution of the population of precipitating convective systems over the equatorial indian ocean in active phases of the madden julian oscillation three dimensional radar reflectivity fields from a dual wavelength doppler polarimetric radar s polka deployed in the equatorialindian ocean are used to evaluate the composition of the populationof convective cloud elements during active phases of the mjo rainfall in active periods was intermittent occurring in 11 episodesofabout 2 4days separated byseveralnonrainydays dataforthese 2 dayperiodswerecomposited relative to the time of maximum rainfall analysis of the s polka data shows the makeup of the convective population during the rainfall episodes four types of echo structures were analyzed statistically for the 11 rainfallepisodes shallowconvectiveechoes sce deepconvectivecores dcc wideconvectiveechocores wcc and broad stratiform bsr echo regions sce and dcc events were most frequent before the maximum rainfall with the peak frequency of sce leading that of dccs wccs were most frequent during therainfallmaximum and bsr regionswere most frequentinthe later part oftherainfallepisode composited ecmwf interim re analysis era interim data and 3 hourly atmospheric soundings indicate that the 2 4 day episodes were related to the passage of equatorial waves in the early part of a rainfall episode the wave passageconditionswereunstable favoringdeeppenetratingconvectiveelements whileinthelaterperiod the wave divergence profile was commensurate with convective systems in late anvil producing stages these results support the stretched building block notion of the life cycle of tropical convection and confirm satellitebased interpretations of sce dcc wcc and bsr statistics in the composition of the convective population

tilt measurements in western canada pairs of short baselength mercury level tiltmeters mounted on shallow piers coupled to sedimentary rocks have been used to monitor ground tilting at three inland locations in western canada noise levels have been estimated over large nyquist intervals to evaluate site conditions and for comparison with results observed in crystalline rocks at other locations the results show that tilt noise patterns are similar for different locations and that noise levels are higher for unconsolidated sediments tidal estimates for the principal lunar semidiurnal constituentm2 were obtained from the least noisy sections of the tilt series uncertainties in the estimated amplitudes for the record lengths considered range from 4 to 20 depending on location and azimuth comparison of the observedm2 tide with those predicted for an elastic earth loaded by two different ocean configurations schwiderski or parke shows better agreement with the schwiderski marine tidal model differences between observaton and theory suggest a strain induced perturbation source

evolution of precipitation and convective echo top heights observed by trmm radar over the indian ocean during dynamo radar data from the tropical rainfall measuring mission show the evolution of echo tops of convective elements over the indian ocean and maritime continent during the dynamics of the madden julian oscillation dynamo field campaign of 2011 2012 echo top heights exhibited a bimodal distribution wherein cumulonimbi of moderate height constituted a congestus mode while vertically extensive cumulonimbus made up a deep mode an intraseasonal time scale dominated variability in these modes from october to january over much of the indian ocean over the maritime continent there was no clear intraseasonal signal in convective echo top heights where the intraseasonal oscillation was detected radar echoes evolved from being dominated by the congestus mode to being characterized by more deep mode convection on time scales of less than 1 week the areal coverage of congestus echoes began to increase 2 8 days prior to the rise in area of deep echoes these satellite derived results confirm that the time scale for convective deepening seen at individual dynamo observational sites is consistent with that of convection on the large scale over the indian ocean intraseasonal variability of zonal wind temperature and humidity as depicted by reanalysis is also consistent with that derived from rawinsonde observations during dynamo thus the gradual buildup of convection as depicted by recent versions of the discharge recharge hypothesis does not accurately describe evolutions of convection prior to mjo events observed during dynamo although cloud moistening processes may still be relevant on time scales of 1 week or less

gravity wave activity associated with tropical convection detected in toga coare sounding data upper air sounding data collected at santa cruz 10 s 165 e in the western tropical pacific ocean during november 1992 february 1993 have been used to estimate the gravity wave activity in the upper troposphere and lower stratosphere large amplitude gravity waves with vertical wavelengths of 2 5 km were found in almost all the soundings time series describing the wave activity in two height ranges 10 17 km the upper troposphere and 17 24 km the lower stratosphere are presented and compared to simple measures of the convective cloud activity there is enhanced gravity wave activity associated with increased convection on intraseasonal timescales

organic matter in the genesis of high island atoll peloidal phosphorites the lagoonal link abstract in the debate over the origin of insular phosphorites found in the top parts of more or less uplifted atolls evidence is provided by both organic geochemistry abundance and composition of humic compounds and lipidic biomarkers and carbon isotope geochemistry for the formation of phosphatic peloids as well as phosphatized bioclasts in environments containing mostly cyanobacterial and microbial organic matter the composition of hydrocarbons and fatty acids suggests that this organic matter has been altered through bacterial processes the abundance of humic compounds and the common presence of concentrically laminated structure of many peloids indicate that these particles formed during early diagenesis in a microbiologically active environment our data were obtained from 1 elemental analysis of bulk organic matter associated with atoll phosphorites as well as of their acid soluble and humic compounds 2 rock eval pyrolysis of bulk organic matter and 3 chromatographic analyses of hydrocarbons and fatty acids the conclusion of this study is that whatever the source of phosphorus guano supermarine reef organisms marine waters or possibly endo upwelling phosphatogenesis proceeded through growth of lagoonal cyanobacterial biomass the phosphorus of which being partly recycled during subsequent diagenetic steps if closed lagoons are indeed favorable for preservation of organic matter and therefore of phosphorus a closed morphology is not a prerequisite for the course of such processes similar d13c values in apatite co3 and in total dissolved organic carbon in recent microbial atoll deposits suggest that such deposits may be precursors to such peloidal insular phosphorites

vertical fluctuation energy in united states high vertical resolution radiosonde data as an indicator of convective gravity wave sources 1 convectively generated internal gravity waves at extratropical latitudes are difficult to identify by climatological analysis of the temperature and horizontal wind fields from radiosonde profiles using traditional analysis methods here we show that by analyzing ascent rate profiles we define a new variable vertical fluctuation energy ve we can identify convection sources in climatological analyses analysis of a 9 year time series 1998 2006 of united states high vertical resolution radiosonde data shows that ve maximizes in summer in midlatitudes within the troposphere 2 8 9 km and peaks at local afternoon early evening during the summer over most of the contiguous united states furthermore the apparent dominant vertical wavelength based on fourier analysis of the low pass filtered ascent rate fluctuations also increase and decrease with ve both on diurnal and seasonal timescales ve in the lower stratosphere however does not show this same relationship to convection but analysis of the vertical wavelength does show some of the features seen in tropospheric ve unlike midlatitude stations ve within both the troposphere and the lower stratosphere over tropical western pacific island stations is highly correlated with convective precipitation and inversely correlated with outgoing longwave radiation we interpret this difference by using the 4 d gravity wave regional or global ray tracer ray tracing model with a source spectrum representative of a convection source

convectively generated gravity waves observed from radiosonde data taken during mctex the properties of gravity waves generated by deep tropical convective systems are analysed from radiosonde soundings taken during the maritime continent thunderstorm experiment and the results compared against recent cloud scale numerical modelling of convectively generated waves fluctuations in the ascent rate of the radiosonde are used to characterize the high frequency waves whereas the zonal wind fluctuations are used to determine the properties of the inertia gravity waves the density weighted vertical velocity variance shows a pronounced diurnal cycle with the largest amplitude gravity waves developing during the early afternoon following the development of deep convection in contrast the density weighted horizontal velocity variance and by implication the inertia gravity wave activity shows no diurnal variation simple theoretical analysis shows that the observations on 27 november 1995 are consistent with a westward propagating gravity wave with a horizontal wavelength of 17 km and a source frequency equal to 0 007 rad s 1 these findings are consistent also with a high resolution numerical model simulation for the same day nonetheless the character of the high frequency gravity waves cannot be uniquely determined from a single radiosonde sounding copyright 2003 royal meteorological society

hydrostatic levels in precision geodesy and crustal deformation measurement previous attempts to apply the principles of hydrostatic leveling to precision geodesy have been limited by the uniformity of the fluid density attainable in field environments this is largely due to the effects of temperature variations in the fluid tube we have overcome this difficulty by using water maintained near its maximum density at 3 98 c inside a counterflow heat exchanger to limit the variations in density to less than 1 ppm we have demonstrated the feasibility of this method with a 14 m prototype level and have used a computer model of the system to demonstrate the theoretical performance of instruments up to 1 km long it appears possible for example to construct a fluid tube 200 m long 12 5 cm in diameter and weighing 3 8 kg m that would provide uniform density to 1 ppm in field environments between 40 and 50 c in our attempt to use the 14 m prototype pressure transfer level we were unable to exploit the density stability that we had achieved due to inadequacies in available pressure gauges

a meridional scan of the stratospheric gravity wave field over the ocean in 2001 messo2001 1 in order to examine gravity wave characteristics over the ocean we conducted a radiosonde observation campaign to scan the stratosphere meridionally over the middle pacific with hakuho maru research vessel operated by the ocean research institute university of tokyo seventy vertical profiles of temperature winds and humidity were successfully obtained over a wide latitude range of 28 n to 48 s with an interval of 1 degree gravity wave energy and vertical wavenumber spectra were examined as a function of latitude gravity wave energy is maximized in the tropical region where the convection is active and in the middle latitude region where the subtropical westerly jet is situated the wave energy in the tropical region is greater than the climatology based on operational radiosonde observation over land regions the gravity wave amplitude does not necessarily increase with altitude in contradiction to simple vertical propagation the latitudinal distribution of wave energy rather suggests that gravity waves propagate meridionally toward higher latitudes an interesting feature is that a wave packet having large horizontal wind and temperature amplitudes is observed continuously over 7 days in the latitudinal region extending 26 degrees results of hodograph analysis indicate that the wave packet is due to an inertia gravity wave with horizontal and vertical wavelengths of about 1800 km and 4 5km respectively this inertia gravity wave is likely generated in association with vigorous convection in the intertropical convergence zone itcz in the northern hemisphere and propagated southward interhemispherically the results in this study show that there are strong nonstationary gravity wave sources over the ocean the importance of meridionally propagating gravity waves is discussed

tropospheric turbulence over the tropical open ocean role of gravity waves a large set of soundings obtained in the indian ocean during 3 field campaigns is used to provide statistical characteristics of tropospheric turbulence and its link with gravity wave gw activity the thorpe method is used to diagnose turbulent regions of a few hundred meters depth above the mixed layer turbulence frequency varies from 10 in the lower troposphere up to 30 around 12km heights gw are captured by their signature in horizontal wind normalized temperature and balloon vertical ascent rate these parameters emphasize different parts of the wave spectrum from longer to shorter vertical wavelengths respectively composites are constructed in order to reveal the vertical structure of the waves and their link with turbulence the relatively longer wavelength gw described by their signature in temperature gwt are more active in the lower troposphere where they are associated with clear variations in moisture turbulence is then associated with minimum static stability and vertical shear stressing the importance of the former and the possibility of convective instability conversely the short waves described by their signature in balloon ascent rate gww are detected primarily in the upper troposphere and their turbulence is associated with a vertical shear maximum suggesting the importance of dynamic instability furthermore gww appear to be linked with local convection whereas gwt are more active in suppressed and dry phases in particular of the madden julian oscillation these waves maybe associated with remote sources such as organized convection or local fronts such as those associated with dry air intrusions

first observations of elevated ducts associated with intermittent turbulence in the stable boundary layer over bosten lake china nocturnal radiative cooling is a main driver for atmospheric duct formation within this atmospheric process the impacts of intermittent turbulence on ducting have seldom been studied in this paper we reported two confusing ducting events observed in the early morning in august 2014 over bosten lake china when a stable boundary layer sbl still survived by using tethered high resolution gps radiosondes elevated ducts with strong humidity inversions were observed during the balloon ascents but were absent during observations made upon the balloon descent several minutes later this phenomenon was initially hypothesized to be attributable to turbulence motions in the sbl and the connection between the turbulence event and the radar duct was examined by the statistical thorpe method turbulence patches were detected from the ascent profiles but not from the descent profiles the possible reasons for the duct formation and elimination were discussed in detail the turbulent transport of moisture in the sbl and the advection due to airflows coming from the lake are the most probable reasons for duct formation in one case the downward transport of moisture by turbulence mixing within a kelvin helmholtz billow at the top of the low level jet resulted in duct elimination in another case the passage of density currents originating from the lake may have caused the elimination of the duct few studies have attempted to associate intermittent turbulence with radar ducts thus this work represents a pioneering study into the connection between turbulent events and atmospheric ducts in a sbl

a comparison of tiltmeters at tidal frequencies different techniques for measuring crustal deformation are now being tested at pinon flat geophysical observatory in southern california as a part of this comparison we have analyzed five months of data from four different tiltmeters three borehole instruments two 4 5 m and one 26 m deep and a long base 535 m instrument at the surface for periods from 1 hour to 10 days the signals from the deep borehole and long base instruments show comparable noise levels the shallow instruments are much noisier tidal analyses give results for the different sensors which agree to within the errors which are several percent

mu radar and lidar observations of clear air turbulence underneath cirrus abstract turbulence generation mechanisms prevalent in the atmosphere are mainly shear instabilities breaking of internal buoyancy waves and convective instabilities such as thermal convection due to heating of the ground in the present work clear air turbulence underneath a cirrus cloud base is described owing to coincident observations from the vhf 46 5 mhz middle and upper atmosphere mu radar a rayleigh mie raman rmr lidar and a balloon radiosonde on 7 8 june 2006 at shigaraki japan 34 85 n 136 10 e time height cross section of lidar backscatter ratio obtained at 2206 lt 7 june 2006 showed the presence of a cirrus layer between 8 0 and 12 5 km msl downward penetrating structures of ice crystals with horizontal and vertical extents of 1 0 4 0 km and 200 800 m respectively have been detected at the cirrus cloud base for about 35 min at the same time the mu radar data revealed clear air turbulence layers developing downward from the cloud base in the environment of the protuberances

tidal and secular tilt from an earthquake zone thresholds for detection of regional anomalies abstract tiltmeter data from an array of three boreholes at the charlevoix observatory in the charlevoix seismic region of que bec have been analysed for evidence of tectonically related signals the secular tilt is dominated by water table induced effects which can be substantially removed by linear regression of the water level on the tilt short term days to months anomalies are shown to be detectable at the 0 3 rad to 1 rad level depending on the depth of the measurement long term changes in the linear drift as small as 0 1 rad yr would be detectable in all of the boreholes large spatial anomalies in the mean tidal admittance among boreholes preclude its use in refining either models of the regional crustal structure or the adjacent marine tide distribution strongly coherent time variations in the tidal admittance among the observations of all the major tidal constituents are shown to be generated by corresponding variations in marine tidal loading in the st lawrence estuary diurnal band variations are closely correlated with the tide gauge data the semi diurnal constituents show a weaker correlation because of the complex spatial pattern within the estuary of time variations in this band inspection of the residual admittance variations for the m2 and o1 constituents demonstrates that the thresholds for detecting tectonic tidal tilt anomalies are 2 and 5 8 respectively the level of earthquake activity in the charlevoix seismic zone throughout the period of the borehole tiltmeter experiment was sufficiently low that no significant tilt anomalies were expected or were undeniably detected

highstands during marine isotope stage 5 evidence from the ironshore formation of grand cayman british west indies abstract the ironshore formation on grand cayman is formed of six unconformity bounded packages units a f units a b c and d known from the subsurface in the northeastern part of grand cayman formed during marine isotope stages mis 11 9 7 and 5e respectively unconformities at the tops of units a b and c are highlighted by terra rossa and or calcrete layers strata in core obtained from wells drilled in george town harbour and exposed on the west part of grand cayman belong to unit d and the newly defined units e and f corals from unit e yielded th u ages of 104 ka whereas conch shells from unit f gave ages of 84 ka unit e equates to mis 5c whereas unit f developed during mis 5a th u dating of corals and conchs from the ironshore formation on the western part of grand cayman shows that unit d formed during the mis 5e highstand whereas units e and f developed in association with highstands at 95 110 ka mis 5c and 73 87 ka mis 5a unit e 5 m thick in the offshore cores is poorly represented in onshore exposures unit f which unconformably overlies unit d at most localities is formed largely of fossil poor cross bedded ooid grainstones the unconformity at the top of unit d a marine erosional surface with up to 2 5 m relief is not characterized by terra rossa or calcrete in the offshore cores or onshore exposures unit d formed with a highstand of 6 m asl whereas units e and f developed when sea level was 2 to 5 asl and 3 to 6 m asl respectively thus the highstands associated with mis 5e 5c and 5a were at similar elevations

lake level observations to detect crustal tilt san andreas lake california 1979 1989 a pair precision lake level gauging stations installed in 1978 have been monitoring differential crustal uplift crustal tilt at san andreas lake california near the suspected epicenter on the san andreas fault of the m 8 3 1906 san francisco earthquake the stations are installed in the lake with a 4 2 km station separation parallel to the san andreas fault the gauging stations use quartz pressure transducers that are capable of detecting intermediate to long term vertical displacements greater than 0 4 mm relative to a fluid surface differencing data from the two sites reduces the noise contributed by atmospheric pressure temperature and density changes and isolates the relative elevation changes between the ends of the lake at periods less than 20 minutes the differenced data are dominated by lake seiches which have a fundamental mode at a period of 13 plus minus 0 3 minutes these seiche harmonics can be filtered or predicted and removed from the data wind shear typically lasting several days can generate apparent short term tilt of the lake and large seiche amplitudes the tilt noise power spectrum obtained from these data decreases by about 15 db decade of frequency monthly averages of the data between 1979 1989 indicate amore tilt rate of 0 02 plus minus 0 08 microradians yr down s34 degree e no measurable horizontal tilt has apparently occurred in this region of the san andreas fault during the last decade however measurements of trilateration networks show this region to be undergoing a horizontal strain of 0 6 plus minus 0 2 mu strain yr less

borehole tensor strain measurements in california two continuous borehole plane strain monitoring sites have been operational in california since late 1983 using borehole tensor strain monitors implanted at a depth of 150 m shear strain data at subtidal sensitivies were available immediately after installation without contamination by bond curing or thermal recovery signals at pinon flat observatory data indicate a constant shear strain accumulation of 0 6 microstrain per annum with the axis of maximum compression oriented 50 5 west of north this result differs significantly from regional geodetic estimates the amplitude being dominated by continued viscoelastic response of the hole variations of measured strain rate exceeding 100 nstrain yr would be significant at this instrument site at san juan bautista measurements of the angle of maximum compression 10 3 west of north agree closely with previous geodetic and hydrofracture estimates after 2 years of operation the residual shear strain rate is 1 strain yr preliminary analysis of strain steps observed at san juan bautista during the morgan hill earthquake of april 24 1984 show good agreement with calculations from seismically determined source parameters for this event

tilt observations from shallow and deep borehole arrays measurements of the earth tide using tilt and strainmeter data can be used to infer crustal structure however in almost all measurements of crustal motion using shallow tiltmeters and strainmeters reference is made to the degradation of the data implied to be caused by influence of meteorological parameters on near surface layers for example studies by wood and king and goulty et al indicated that a substantial portion of measured crustal motion by shallow tilt and strain data may be attributed to the weather these studies were limited to data outside the tidal band however it is important to determine the effects of weather on these data within the tidal band if shallow tiltmeters are to be used to determine crustal structure collocated deep and shallow borehole tiltmeter arrays were operated by the air force geophysics laboratory in eastern massachusetts and provided an opportunity to investigate weather effects on shallow tilt the tiltmeters installed in deep boreholes 100 m yielded internally consistent m2 amplitudes 2 and phases 3 cabaniss and mcconnell but the collocated shallow 4 m borehole tilt array did not produce the same results least squares analyses of the shallow tilt data revealed variations of 20 for m2 tidal amplitude compared to the deep data a multichannel wiener filter technique was used to investigate the hypothesis that this discrepancy was due to meteorological influence results indicated that approximately one half of the anomalous m2 power was correlated with air and borehole temperatures it is suggested that the remaining anomalous power may be due to ground deformation caused by the action of groundwater if this is true shallow tiltmeters might not be measuring the same deformation as the deep instruments and therefore not capable of measuring the earth tide with the accuracy required to determine crustal structure

origin of recent insular phosphate rock on a coral cay raine island northern great barrier reef australia abstract raine island is a small vegetated coral cay that is capped by recent insular phosphate rock on the northeastern shore phosphate rock also extends into the intertidal zone where it is juxtaposed against calcareous beachrock a petrological and isotopic study was carried out on the phosphate rock in order to clarify some of the uncertainties concerning the genesis of insular phosphate rocks in general and on raine island in particular the main phosphate mineral is dahllite carbonate hydroxyapatite which occurs as microlaminated grain coatings and as a bioclast replacement minor pore filling whitlockite tricalcium phosphate was recorded in one sample organic carbon is intimately associated with phosphate cement and accounts for color variations between microlaminae phosphate 18op smow values range from 14 4 to 16 6o oo indicating that phosphatic porewaters were entirely fresh and had not undergone evaporative 18o enrichment phosphate cement records the passage of both downward percolating near surface porewater and seaward moving groundwater at or close to the freshwater saltwater interface intertidal phosphatic rock on the northeastern shore is a rare example of a lithified intertidal tropical beach sand deposit with a definite fresh water origin

microphysical characteristics of mjo convection over the indian ocean during dynamo the microphysical characteristics of precipitating convection occurring in various stages of the madden julian oscillation mjo over the indian ocean are determined from data obtained from the national center for atmospheric research dual polarimetric doppler s band radar s polka deployed as part of the dynamics of the mjo dynamo field experiment active mjo events with increased rainfall occurred in october november and december 2011 during each of these active mjo phases in addition to enhanced rainfall convection became deeper and ice phase microphysics played a greater role s polka consistently showed nonoriented small ice particles dominating the radar echoes at altitudes of 9 10 km dry aggregates concentrated between 7 and 9 km and wet aggregates and graupel near the melting level 5 km graupel occurred mainly in actively convective towers while the wet aggregates occurred almost exclusively in the stratiform regions of mesoscale convective systems mcss during each of the three multiweek mjo active phases the maximum rainfall occurred in short bursts lasting a few days each multiday rainy period began with deepening convective elements and a concurrent increase in occurrence of dry aggregates which maximized just prior to organization into mcss the peak rainfall occurrence coincided with the maximum coverage of the radar domain by mcss reflecting large stratiform regions that exhibited the most frequent occurrence of wet aggregates during the december active mjo phase however the mcss were shallower and had a slightly lower tendency for wet aggregates in the stratiform regions and therefore generally weaker brightbands

intermittent mixing in strongly stratified fluids as a random walk in strongly stratified geophysical fluids such as the stratosphere and the ocean the vertical mixing of tracers is largely due to patches of turbulence that are intermittent in time and space heuristic models for this type of mixing are studied which extend that of dewan 1981 a the recognition that in these models fluid particles undergo continuous time random walks allows the derivation of closed form results for the particle position statistics the particle dispersion is shown generally to be diffusive in the long time limit however the early time non diffusive regime is also analysed since a time scale estimate indicates its practical importance in particular for stratospheric mixing because the restratification of fluid patches previously homogenized by turbulence takes a finite time the probability for a fluid region to become turbulent may depend on the time elapsed since it has last been turbulent this introduces a memory effect whose consequences for the tracer mixing are analysed in detail using a simple non markovian model the heuristic models studied allow the large scale dispersive effects of the turbulent patches to be inferred from the properties of individual patches this highlights those properties that might most usefully be determined from investigations of the dynamics of the turbulent patches themselves

gravity waves generated by convection during twp ice 2 high frequency gravity waves high frequency gravity waves are analyzed using radiosonde soundings taken during the tropical warm pool international cloud experiment twp ice the intrinsic periods of these waves are estimated to be between 10 and 50 min the high frequency wave activity in the stratosphere defined by mass weighted variance of the vertical motion of the sonde has a maximum following the afternoon local convection indicating that these waves are generated by local convection the wave activity is the strongest in the lower stratosphere below 22 km and during the suppressed monsoon period is modulated with a 3 4 day period the concentration of the wave activity in the lower stratosphere is consistent with the properties of the environment in which these waves propagate whereas its 3 4 day modulation is explained by the variation of the convection activity in the twp ice domain for shallow convection the wave activity has a weak tendency to increase as the rainfall intensity increases the wave activity associated with deep convection which typically occurs at high rainfall intensities is larger and has more spread than that associated with shallow convection

la maree d inclinaison a leduc alberta canada observation analyse et interpretation in geophysics the signal resulting from tidal forcing is the only one precisely known a priori its omnipresence in tilt measurements can be exploited to characterize the spatio temporal properties of rocks in situ but only if experimental uncertainties are less than 2 signal distortions due to unknown material and geometrical discontinuities around sensors limit the observational accuracy tilt tides were measured with a new biaxial tiltmeter installed in a 12 m borehole at leduc alberta where the geology is well defined both locally and regionally at the m frequency the observed parameters error of 2 5 are coherent with results previously obtained with near surface tiltmeters installed 100 m away but 5 times noisier the load tide due to oceans differs according to which configuration is used in its computation and the new measurements favor schwiderski s m model over that of parke and hendershott a topographic perturbation due to a small valley at 500 m from the borehole has been identified by comparing the tilt residuals for m and 0 with the strain tide the results indicate that even a smooth topography can perturb tidal observations to the point of hampering the interpretation of tilt anomalies in terms of regional tectonics

strainmeters and tiltmeters despite steady effort over the last century continuously recording tiltmeters and strainmeters have not yet been successful except for earth tide measurements this article reviews the techniques and instrument designs that have been developed in this field the continuous measurement of true tectonic motions which have rates of 10 14 s 1 requires extremely high instrument stability but more rapid motions tides and seismic waves apart are even smaller and not much more easily detectable much past effort has been spent improving the transducers used in these instruments which usually measure small displacements the commonest choices are optical the most accurate capacitive the most sensitive and inductive the most rugged nowadays building a transducer is the easiest part a much harder task equally important to a good design is attaching the instrument to the ground so that it can detect the signal wanted this part of the design includes choosing a location a large underground opening is thermally stable but distorting a surface installation is easy to build but noisy because of soil weathering and a borehole is inaccessible to weather but also to the operator all such installations and indeed the whole field of strain and tilt measurement of course rely on the assumption that the deformations of interest can be measured over baselengths of a few hundred meters or less this is true for tides and seismic waves but unproven for tectonic motions appropriate attachment techniques differ for each location and many mundane details such as cementing techniques for borehole instruments remain to be worked out the goal of measuring tectonic and tidal tilt has created many tiltmeter designs most are relatively small instruments that use some form of pendulum or bubble level a few use a liquid surface to measure tilts over a long baseline repeated experience has shown the latter type when well built to be superior to the former proving end monument motions to be a dominant source of noise the same appears to hold true for strainmeters the best results coming from long base laser instruments though strainmeters using rigid or flexible material length standards are useful for special purposes and borehole instruments show promise because achieving a good design has been so difficult it is important to select the goals an instrument must meet and be prepared to compromise on others the difficulty of validating results from this type of instrument makes comparison tests essential such tests as have been made so far show that good results cannot be gotten at low cost or without careful attention to details

observations of kelvin helmholtz instability at a cloud base with the middle and upper atmosphere mu and weather radars 1 using the very high frequency 46 5 mhz middle and upper atmosphere radar mur ka band 35 ghz and x band 9 8 ghz weather radars a kelvin helmholtz kh instability occurring at a cloud base and its impact on modulating cloud bottom altitudes are described by a case study on 8 october 2008 at the shigaraki mu observatory japan 34 85 n 136 10 e kh braids were monitored by the mur along the slope of a cloud base gradually rising with time around an altitude of 5 0 km the kh braids had a horizontal wavelength of about 3 6 km and maximum crest to trough amplitude of about 1 6 km nearly monochromatic and out of phase vertical air motion oscillations exceeding 3 m s 1 with a period of 3 min 20 s were measured by the mur above and below the cloud base the axes of the billows were at right angles of the wind and wind shear both oriented east north east at their altitude the isotropy of the radar echoes and the large variance of doppler velocity in the kh billows including the braids indicate the presence of strong turbulence at the bragg 3 2 m scale after the passage of the cloud system the kh waves rapidly damped and the vertical scale of the kh braids progressively decreased down to about 100 m before their disappearance the radar observations suggest that the interface between clear air and cloud was conducive to the presence of the dynamical shear instability by reducing static stability and then the richardson number near the cloud base downward cloudy protuberances detected by the ka band radar had vertical and horizontal scales of about 0 6 1 1 and 3 2 km respectively and were clearly associated with the downward air motions observed oscillations of the reflectivity weighted doppler velocity measured by the x band radar indicate that falling ice particles underwent the vertical wind motions generated by the kh instability to form the protuberances the protuberances at the cloud base might be either kh billow clouds or perhaps some sort of mamma reflectivity weighted particle fall velocity computed from doppler velocities measured by the x band radar and the mur showed an average value of 1 3 ms 1 within the cloud and in the protuberance environment

earthquakes and sea level space and terrestrial metrology on a changing planet the complacency with which man inhabits continent ocean margins or plate boundaries is based on the assumption that sea level rise and periodic seismicity are acceptable risks the forecast of future sea level or future seismicity is essential for informed assessment of these risks the historical data from which forecasts may be derived are in each case of limited antiquity and uneven spatial distribution developments in space geodesy and crustal deformation metrology in the past two decades offer the means to acquire a homogeneous global data set for monitoring relative vertical and horizontal motions of the earth s surface to within several millimeters these new tools are reviewed in terms of their application to forecasting trends in sea level rise and forecasting damaging earthquakes

distribution and interpretation of rare earth elements and yttrium in cenozoic dolostones and limestones on cayman brac british west indies abstract the cenozoic carbonate succession on cayman brac a small island 19 km long and 1 5 to 3 km wide located in the caribbean sea has been dolomitized to varying degrees the rare earth element ree and yttrium y concentrations ree y of 134 carbonate samples 127 from cayman brac and 7 supplementary samples from grand cayman vary from 0 2 to 7 5 ppm average 2 8 ppm n 134 the shale normalized ree y patterns of the carbonate samples akin to those of oxygenated seawater are characterized by 1 lree depletion relative to hree average dy n sm n 1 7 n 125 2 positive la anomalies 3 negative ce anomalies average ce ce 0 4 n 133 and 4 superchondritic y ho molar ratios average y ho 85 n 86 the lack of correlation between the dolomite content of the samples and their ree y dy n sm n la n nd n ce ce or y ho indicates that dolomitization did not have a major impact on ree y signatures and that dolomitization was probably mediated by seawater like fluids the shale normalized patterns e g dy n sm n la n nd n ce ce and y ho vary from formation to formation for samples from the cayman formation the pedro castle formation and the ironshore formation there are subtle but gradual changes in dy n sm n la n nd n ce ce with depth in contrast there are marked changes in la n nd n ce ce y ho and sm nd across the brac unconformity which forms the boundary between the lower oligocene brac formation and the overlying miocene cayman formation variations in the ree y patterns reflect diagenetic processes e g dy n sm n and possibly secular changes in the ree y composition of seawater e g la n nd n y ho and sm nd

the three atmospheric circulations over the indian ocean and the maritime continent and their modulation by the passage of the mjo abstractthe passage of the madden julian oscillation mjo over the indian ocean and the maritime continent is investigated during the episode of 23 30 november 2011 a meso nh convection permittin

radiosonde observations of equatorial atmosphere dynamics over indonesia 2 characteristics of gravity waves this paper discusses the characteristics of gravity waves in the equatorial region revealed by analyzing radiosonde measurements of wind velocity and temperature fluctuations at 0 35 km with a height resolution of 150 m made every 5 7 hours between february 27 and march 22 1990 in east java indonesia we conducted hodograph analysis to delineate vertical and horizontal propagation characteristics and found that most gravity waves were generated in the middle of the troposphere and that they propagated upward into the stratosphere the amplitudes of wind velocity and temperature fluctuations due to gravity waves were larger in the stratosphere than in the troposphere the direction of horizontal propagation of gravity waves was rather uniformly distributed in the troposphere but it became eastward in the lower stratosphere being opposite to that of the mean winds because of quasi biennial oscillation the vertical wavenumber spectra of wind velocity were described fairly well by a saturated model spectrum although their amplitudes were smaller in the stratosphere a typical vertical wavelength was 2 2 5 km while the horizontal phase velocities were 5 7 and 12 m s in the troposphere and stratosphere respectively the amplitudes of small scale gravity waves were significantly larger in the equatorial stratosphere than at middle latitudes time height variation of the wind velocity variance due to gravity waves showed a clear correlation with that for high relative humidity which implies that cloud convection is an important mechanism of gravity wave generation in the equatorial region

mineralogy of sedimentary apatites abstract members of the apatite family are the most common phosphate minerals apatites in igneous and metamorphic rocks generally approach fluorapatite in composition in sedimentary rocks the apatite is usually the carbonate fluorapatite variety francolite which produces x ray diffraction patterns similar to but distinctive from those of fluorapatite variations in francolite compositions and physical properties have also been identified the substitution of co 3 2 for po 4 3 from zero to about 25 of phosphate sites on a 1 1 basis influences all other changes in composition and crystallography of francolites statistical models have reduced the francolite composition to a single parameter problem the dominant factor being the variation in unit cell a value with increasing co 3 2 substitution within a deposit variations in francolite composition with stratigraphical position and particle size may indicate the extent and type of post depositional alteration replacements of so 4 2 for po 4 3 and ca 2 by na 2 and mg 2 are also discussed but these are of more limited significance

january 30 1997 eruptive event on kilauea volcano hawaii as monitored by continuous gps a continuous global positioning system gps network on kilauea volcano captured the most recent fissure eruption in kilauea s east rift zone erz in unprecedented spatial and temporal detail the short eruption drained the lava pond at pueu oeo leading to a two month long pause in its on going eruption models of the gps data indicate that the intrusion s bottom edge extended to only 2 4 km continuous gps data reveal rift opening 8 hours prior to the eruption absence of precursory summit inflation rules out magma storage overpressurization as the eruption s cause we infer that stresses in the shallow rift created by the continued deep rift dilation and slip on the south flank decollement caused the rift intrusion

geochemical evidence for african dust inputs to soils of western atlantic islands barbados the bahamas and florida 1 we studied soils on high purity limestones of quaternary age on the western atlantic ocean islands of barbados the florida keys and the bahamas potential soil parent materials in this region external to the carbonate substrate include volcanic ash from the island of st vincent near barbados volcanic ash from the islands of dominica and st lucia somewhat farther from barbados the fine grained component of distal loess from the lower mississippi river valley and wind transported dust from africa these four parent materials can be differentiated using trace elements sc cr th and zr and rare earth elements that have minimal mobility in the soil forming environment barbados soils have compositions that indicate a complex derivation volcanic ash from the island of st vincent appears to have been the most important influence but african dust is a significant contributor and even mississippi river valley loess may be a very minor contributor to barbados soils soils on the florida keys and islands in the bahamas appear to have developed mostly from african dust but mississippi river valley loess may be a significant contributor our results indicate that inputs of african dust are more important to the genesis of soils on islands in the western atlantic ocean than previously supposed we hypothesize that african dust may also be a major contributor to soils on other islands of the caribbean and to soils in northern south america central america mexico and the southeastern united states dust inputs to subtropical and tropical soils in this region increase both nutrient holding capacity and nutrient status and thus may be critical in sustaining vegetation

the event to event variability of the boreal winter mjo 1 during boreal winters perturbations of the convection by the madden julian oscillation mjo peak over three basins distributed in longitude south of the equator the eastern indian ocean io the south of the maritime continent mc and the western pacific ocean po we use the observed outgoing longwave radiation olr and low level wind to identify and characterize all wintertime mjo events between 1979 and 2010 there is a large event to event variability with some mjo events organized at the planetary scale having their amplitude well distributed over the 3 basins and some showing only basin scale organization with a convective perturbation peaking over one or two basins the average of the mjo amplitude for the three basins shows an intriguing decadal variability consistent for both olr and low level wind the disparity between the 3 basins is dominated by an alternation between mjo amplitude peaking on either the indian or the pacific ocean this indo pacific alternation depicted by an indo pacific index ipi is partly related to enso in el nino conditions there is not only an extension of the mjo perturbation further east but also an increase of the mjo perturbation over the western pacific and a diminution of the mjo perturbation over the eastern indian ocean

radiosonde observations of equatorial atmosphere dynamics over indonesia 1 equatorial waves and diurnal tides this paper describes the characteristics of the mean winds equatorial waves with periods ranging from 4 to 20 days and diurnal tides determined by analyzing the profiles of wind velocity temperature and humidity obtained every 5 7 hours in the height range up to about 35 km with a height resolution of 150 m during an observation campaign conducted february 27 to march 22 1990 in east java indonesia the structures of the mean winds in the troposphere and lower stratosphere seemed to be affected by the australian monsoon and the quasi biennial oscillation respectively frequency spectra indicated that the equatorial waves as well as the diurnal tides were dominant below about 25 km while gravity waves with periods shorter than 4 days became more significant above 25 km a 7 day oscillation showing an antiphase relation between the eastward and northward components and exhibiting large amplitudes was observed in the lower troposphere the time height variations of the activity of this 7 day oscillation were clearly correlated with a region of high relative humidity perturbations in the zonal wind and temperature with wave periods varying from 15 to 17 days were also enhanced in the troposphere while kelvin waves with periods of about 7 and 20 days were detected in the lower stratosphere and activity near the tropopause was conspicuously enhanced we found that the 20 day kelvin wave greatly modified the structure of the tropopause such as the minimum temperature the tropopause height and the values of the brunt vaisala frequency squared n2 which further suggests the effects of kelvin waves on the transportation of tropospheric water vapor into the stratosphere and on the downward mixing of stratospheric minor constituents into the troposphere the observed profiles of the diurnal oscillation were compared with those of a numerical model assuming only migrating tides which reasonably agreed above about 25 km below 25 km however the observed amplitudes were 1 1 5 m s exceeding those of the model about 10 times moreover the phase profiles involved fluctuations with small vertical scales suggesting interference by many nonmigrating tides with short vertical wavelengths

contemporary plate motion and crustal deformation the measurement of relative plate velocities during the past few years is a signal accomplishment in earth science leading to refinement of the precepts of steady motion of plate interiors and cyclic deformation along plate margins regrettably deformation premonitory to an earthquake has yet to be detected with confidence delineation of the spatial and temporal buildup of strain between earthquakes however has put limits on models of the earthquake cycle a diverse set of fault structures and crustal rheologic conditions can explain the pattern of surface strain accumulation and release along strike slip faults in contrast the geometry of thrusts and normal faults revealed by earthquake deformation has been found to differ markedly from expectations geodetic observations have proved vital to monitor the ascent of magma through the earth s crust and to predict volcanic eruptions at the earth s surface episodic vertical and horizontal deformation in southern california remains a subject of dispute if anything it is less certain than it once seemed

sea level highstands over the last 500 000 years evidence from the ironshore formation on grand cayman british west indies abstract the ironshore formation up to 19 m thick in the rogers wreck point area of grand cayman is divided into the unconformity bounded units a b c and d the unconformities are highlighted by caliches and or terra rossa th u dates from aragonitic corals indicate that unit a formed at 400 ka unit b 346 ka unit c 229 ka and unit d 131 ka these ages correlate with the highstands of the last four interglacial periods and probably represent marine isotope stages 5 unit d 7 unit c 9 unit b and 11 unit a the limestones in units a d which have similar biotic and lithologic characteristics represent deposition in shallow water on a narrow coastal shelf unit a has a high faunal diversity and was deposited in open marine conditions whereas units b c and d were deposited in quieter water lagoons that probably had fringing reefs along their sea ward edges although grand cayman is located on the cayman ridge close to an active spreading center and transform fault the island has undergone little or no vertical movement over the last 500 ky available evidence indicates that sea level at the time of deposition of each unit relative to present sea level was unit a 9 0 to 5 5 m unit b 3 0 to 0 5 m unit c 2 5 to 1 1 m and unit d 2 5 to 6 0 m these data are good estimates of eustatic sea level highstands over the last 500 ky