Science.gov

Sample records for earth tides effect

  1. Earth tides

    SciTech Connect

    Harrison, J.C.

    1984-01-01

    Nineteen papers on gravity, tilt, and strain tides are compiled into this volume. Detailed chapters cover the calculation of the tidal forces and of the Earth's response to them, as well as actual observations of earth tides. Partial Contents: On Earth tides. The tidal forces: Tidal Forces. New Computations of the Tide-Generating Potential. Corrected Tables of Tidal Harmonics. The Theory of Tidal Deformations. Body Tides on an Elliptical, Rotating, Elastic and Oceanless Earth, Deformation of the Earth by Surface Loads. Gravimetric Tidal Loading Computed from Integrated Green's Functions. Tidal Friction in the Solid Earth. Loading Tides Versus Body Tides. Lunar Tidal Acceleration from Earth Satellite Orbit Analysis. Observations: gravity. Tidal Gravity in Britain: Tidal Loading and the Spatial Distribution of the Marine Tide. Tidal Loading along a Profile Europe-East Africa-South Asia-Australia and the Pacific Ocean. Detailed Gravity-Tide Spectrum between One and Four Cycles per Day. Observations: tilt and strain. Cavity and Topographic Effects in Tilt and Strain Measurement. Observations of Local Elastic Effects on Earth Tide Tilts and Strains.

  2. Dynamic ocean-tide effects on Earth's rotation

    NASA Technical Reports Server (NTRS)

    Dickman, S. R.

    1993-01-01

    This article develops 'broad-band' Liouville equations which are capable of determining the effects on the rotation of the Earth of a periodic excitation even at frequencies as high as semi-diurnal; these equations are then used to predict the rotational effects of altimetric, numerical and 32-constituent spherical harmonic ocean-tide models. The rotational model includes a frequency-dependent decoupled core, the effects of which are especially marked near retrograde diurnal frequencies; and a fully dynamic oceanic response, whose effects appear to be minor despite significant frequency dependence. The model also includes solid-earth effects which are frequency dependent as the result of both anelasticity at long periods and the fluid-core resonance at nearly diurnal periods. The effects of both tidal inertia and relative angular momentum on Earth rotation (polar motion, length of day, 'nutation' and Universal Time) are presented for 32 long- and short-period ocean tides determined as solutions to the author's spherical harmonic tide theory. The lengthening of the Chandler wobble period by the pole tide is also re-computed using the author's full theory. Additionally, using the spherical harmonic theory, tidal currents and their effects on rotation are determined for available numerical and altimetric tide height models. For all models, we find that the effects of tidal currents are at least as important as those of tide height for diurnal and semi-diurnal constituents.

  3. The Earth Tides.

    ERIC Educational Resources Information Center

    Levine, Judah

    1982-01-01

    In addition to oceans, the earth is subjected to tidal stresses and undergoes tidal deformations. Discusses origin of tides, tidal stresses, and methods of determining tidal deformations (including gravity, tilt, and strain meters). (JN)

  4. The influence of earth tides on earth's coordinates

    NASA Technical Reports Server (NTRS)

    Vincente, R. O.

    1978-01-01

    The importance of the Earth's tides on Earth coordinates were examined for the following reasons: (1) the precision for obtaining the Earth's coordinates shows that the effects of Earth tides appear on the values obtained for the coordinates; (2) the possibility of determining the values of the Earth tides; and (3) the consideration of theoretical models that can compute the values of Earth tides. The astronomical and geodetic coordinates of a point at the Earth's surface are described.

  5. Effects of dynamic long-period ocean tides on changes in Earth's rotation rate

    SciTech Connect

    Nam, Y.S.; Dickman, S.R. )

    1990-05-10

    As a generalization of the zonal response coefficient first introduced by Agnew and Farrell (1978), the authors define the zonal response function k of the solid earth-ocean system as the ratio, in the frequency domain, of the tidal change in Earth's rotation rate to the tide-generating potential. Amplitudes and phases of k for the monthly, fortnightly, and 9-day lunar tides are estimated from 2 1/2 years of very long baseline interferometry UTI observations (both 5-day and daily time series), corrected for atmospheric angular momentum effects using NMC wind and pressure series. Using the dynamic ocean tide model of Dickman (1988a, 1989a), the authors predict amplitudes and phases of k for an elastic earth-ocean system. The predictions confirm earlier results which found that dynamic effects of the longer-period ocean tides reduce the amplitude of k by about 1%. However, agreement with the observed k is best achieved for all three tides if the predicted tide amplitudes are combined with the much larger satellite-observed ocean tide phases; in these cases the dynamic tidal effects reduce k by up to 8%. Finally, comparison between the observed and predicted amplitudes of k implies that anelastic effects on Earth's rotation at periods less than fortnightly cannot exceed 2%.

  6. Effects of dynamic long-period ocean tides on changes in earth's rotation rate

    NASA Technical Reports Server (NTRS)

    Nam, Young; Dickman, S. R.

    1990-01-01

    As a generalization of the zonal response coefficient first introduced by Agnew and Farrell (1978), the zonal response function kappa of the solid earth-ocean system is defined as the ratio, in the frequency domain, of the tidal change in earth's rotation rate to the tide-generating potential. Amplitudes and phases of kappa for the monthly, fortnightly, and nine-day lunar tides are estimated from 2 1/2 years of VLBI UT1 observations, corrected for atmospheric angular momentum effects using NMC wind and pressure series. Using the dynamic ocean tide model of Dickman (1988, 1989), amplitudes and phases of kappa for an elastic earth-ocean system are predicted. The predictions confirm earlier results which found that dynamic effects of the longer-period ocean tides reduce the amplitude of kappa by about 1 percent.

  7. Barometric and Earth Tide Correction

    SciTech Connect

    Toll, Nathaniel J.

    2005-11-10

    BETCO corrects for barometric and earth tide effects in long-term water level records. A regression deconvolution method is used ot solve a series of linear equations to determine an impulse response function for the well pressure head. Using the response function, a pressure head correction is calculated and applied.

  8. The effects of the solid inner core and nonhydrostatic structure on the earth's forced nutations and earth tides

    NASA Technical Reports Server (NTRS)

    De Vries, Dan; Wahr, John M.

    1991-01-01

    This paper computes the effects of the solid inner core (IC) on the forced nutations and earth tides, and on certain of the earth's rotational normal modes. The theoretical results are extended to include the effects of a solid IC and of nonhydrostatic structure. The presence of the IC is responsible for a new, almost diurnal, prograde normal mode which involves a relative rotation between the IC and fluid outer core about an equatorial axis. It is shown that the small size of the IC's effects on both nutations and tides is a consequence of the fact that the IC's moments of inertia are less than 1/1000 of the entire earth's.

  9. The effect of ocean tides on the earth's rotation as predicted by the results of an ocean tide model

    NASA Technical Reports Server (NTRS)

    Gross, Richard S.

    1993-01-01

    The published ocean tidal angular momentum results of Seiler (1991) are used to predict the effects of the most important semidiurnal, diurnal, and long period ocean tides on the earth's rotation. The separate, as well as combined, effects of ocean tidal currents and sea level height changes on the length-of-day, UT1, and polar motion are computed. The predicted polar motion results reported here account for the presence of the free core nutation and are given in terms of the motion of the celestial ephemeris pole so that they can be compared directly to the results of observations. Outside the retrograde diurnal tidal band, the summed effect of the semidiurnal and diurnal ocean tides studied here predict peak-to-peak polar motion amplitudes as large as 2 mas. Within the retrograde diurnal tidal band, the resonant enhancement caused by the free core nutation leads to predicted polar motion amplitudes as large as 9 mas.

  10. On the effect of ocean tides and tesseral harmonics on spacecraft flybys of the Earth

    NASA Astrophysics Data System (ADS)

    Acedo, L.

    2016-12-01

    The so-called flyby anomaly has encouraged several authors to analyse in detail the minor perturbative contributions to the trajectory of spacecraft performing a flyby manoeuvre. This anomaly consist of an unexplained increase or decrease of the asymptotic velocity of the spacecraft after a flyby of the Earth in the range of a few mm per second. Some order of magnitude estimations have been performed in recent years to dismiss many possible conventional effects as the source of such an anomaly but no explanation has been found yet. In this paper we perform a study of the perturbation induced by ocean tides in a flybying spacecraft by considering the time dependence of the location of the high tide as the Moon follows its orbit. We show that this effect implies a change of the spacecraft velocity of a few micrometres per second. We also consider the coupling of tesseral harmonics inhomogeneities and the rotation of the Earth and its impact on the spacecraft outgoing velocity. Significant corrections to the observed asymptotic velocities are found in this case but neither their sign nor their magnitude coincide with the anomalies. So, we can also rule this out as a conventional explanation.

  11. The effect of error in theoretical Earth tide on calibration of borehole strainmeters

    USGS Publications Warehouse

    Langbein, John

    2010-01-01

    Since the installation of borehole strainmeters into the ground locally distorts the strain in the rock, these strainmeters require calibration from a known source which typically is the Earth tide. Consequently, the accuracy of the observed strain changes from borehole strainmeters depends upon the calibration derived from modeling the Earth tide. Previous work from the mid-1970s, which is replicated here, demonstrate that the theoretical tide can differ by 30% from the tide observed at surface-mounted, long-baseline strainmeters. In spite of possible inaccurate tidal models, many of the 74 borehole strainmeters installed since 2005 can be “calibrated”. However, inaccurate tidal models affect the amplitude and phase of observed transient strain changes which needs to be considered along with the precision of the data from the inherent drift of these borehole instruments. In particular, the error from inaccurate tidal model dominates the error budget in the observation of impulsive, sub-daily, strain-transients.

  12. Modelling the pole tide and its effect on the earth's rotation

    NASA Technical Reports Server (NTRS)

    Carton, J. A.; Wahr, J. M.

    1986-01-01

    The pole tide is the response of the ocean to incremental centrifugal forces associated with the Chandler wobble. The tide has a potentially important effect on the period and damping of the wobble, but it is at present not well constrained by observations. Here, both analytical and numerical models for the pole tide are constructed. The analytical models consider the tide first in a global ocean and then in an enclosed basin on a beta-plane. The results are found to approach equilibrium linearly with decreasing frequency and inversely with increasing basin depth. The numerical models solve Laplace's tidal equations over the world's oceans using realistic continental boundaries and bottom topography. The results indicate that the effects of non-equilibrium portion of the deep ocean tide on the Chandler wobble period and damping are negligible.

  13. How do earth tides affect astronomers?

    NASA Technical Reports Server (NTRS)

    Sasao, T.

    1978-01-01

    Earth tides affect astronomical observations of the Earth's rotation in the following two ways: (1) verticals are deflected; and (2) the polar moment of inertia of the Earth is changed causing periodic variations in the rotation rate. The diurnal and semidiurnal tides and nutation were examined in periodic variations. Results indicate little change occured in the polar motions. Nutation observations were disturbed rather seriously by the diurnal tides.

  14. Quantifying fractured crystalline-rock properties using well tests, earth tides and barometric effects

    NASA Astrophysics Data System (ADS)

    Burbey, Thomas J.; Hisz, David; Murdoch, Lawrence C.; Zhang, Meijing

    2012-01-01

    SummaryCharacterization of fractured rock aquifers often requires the acquisition and analysis of diverse datasets obtained from various instrumentation configurations. In this investigation at the fractured rock research site in Floyd County, Virginia, a high-precision borehole extensometer and tiltmeter were used during pumping to monitor deformation in the vicinity of fractures identified from borehole logging. Strain data obtained from earth tide analyses were used with the extensometer and tiltmeter data to quantify hydromechanical properties, including fracture volumetric specific storage, porosity, Poisson's ratio, the drained formation elastic modulus, and the effective dip direction of the fracture. Borehole tiltmeter data were used to estimate deformation caused by an aquifer test consisting of three pumping and recovery periods performed in well EX-1. During each period of the aquifer test the extensometer, located in W-03 and 27.7 m from the pumping well, was anchored over 2-m-long sections of (1) a fracture in hydraulic communication with EX-1, (2) a fracture that is not hydraulically connected with EX-1, and (3) an unfractured portion of bedrock directly above the hydraulically connected fracture. Results from the pumping tests yielded compressibilities of 1.3 × 10 -11 Pa -1, and 1.7 × 10 -11 Pa -1 for the lower and upper fractures, respectively. When coupled with areal strain calculated from earth tide analyses the volumetric specific storage values are 3.2 × 10 -11 Pa -1, and 2.8 × 10 -11 Pa -1 and the Poisson's ratios are 0.26 and 0.31, respectively. Using this with a calculated barometric efficiency of 0.45 allows for porosity calculations of 0.02 and 0.03, respectively for the vicinity of fractures in well W-03.

  15. A series expansion of the solid Earth tide effect on geopotential

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, Sergey M.

    2013-04-01

    We develop analytical series representing the main part of corrections to the geopotential coefficients caused by the solid Earth tides, where Love numbers are assumed to be frequency-independent. The series are compact, precise and valid over 1800 A.D.-2200 A.D. The maximum difference between the corrections given by the analytical series and their numerical values, obtained with use of the DE/LE-423 planetary/lunar ephemerides, does not exceed 0.7× 10^{-12}. A new algorithm is proposed for calculating amplitudes of the additional variations of the geopotential coefficients for frequency dependence of Love numbers. It uses the representation of the Earth tide-generating potential in the standard HW95 format and takes into account the phase of tidal waves. Corrections of up to 2× 10^{-12} to the published by the IERS Conventions (2010) amplitudes of the additional variations of the geopotential coefficients are suggested. Examples of use of the obtained series in analytical theories of motion of low-altitude STARLETTE and high-altitude ETALON-1 satellites are given.

  16. Earth tides of an ellipsoidal, inelastic, and laterally heterogeneous Earth

    NASA Astrophysics Data System (ADS)

    Kim, T.; Shibuya, K.

    2012-12-01

    We used five stations covering a range of latitudes from 60°N to 70°S: METSÄHOVI, STRASBOURG, SUTHERLAND, CANBERRA, and SYOWA with Superconducting Gravimeter with sufficiently high-resolution data available for durations of at least five years to validate theoretical estimation based on an existing method. For the Earth model, we selected the model of Dehant et al. (1999) to validate the latitude dependency and inelasticity of gravimetric factor. We also used the model of Métivier and Conrad (2008) to validate the lateral heterogeneity of gravity observation. For the correction of ocean loading effect, we tested recent four global ocean tide models (TPXO7-atlas, EOT11a, DTU10, and HAMTIDE11a) as well as old ocean tide models. We estimated the misfit between the observed loading effect and the modeled ocean loading effect for the three main waves (O1, K1, and M2) at each station. Anomalous discrepancies at METSÄHOVI and SYOWA based on old ocean tide models were diminished by the use of recent ocean tide models. Gravimetric factors for K1, corrected using optimum recent ocean tide models, showed the possibility of obtaining parameters conforming to the prediction curve of model of inelastic non-hydrostatic Earth. Gravimetric factors corrected using optimum ocean tide models at METSÄHOVI, STRASBOURG, and CANBERRA showed tendencies towards the theoretical values for latitude dependence. However, at SUTHERLAND and SYOWA, large offsets from theoretical values were observed. These stations show the remaining misfits, 0.0733 and 0.0847 microGal, respectively. We think the portion of the anomaly could not be explained by the perturbation from the mantle convection, because the amplitude of gravity perturbation at these stations is very small. For example, at SUTHERLAND, the final residual for K1 band is 85 nanoGal but gravity perturbation by lateral heterogeneity is just ~0.81 nanoGal: Gravity perturbations up to 120 nanoGal for all bands come from mostly in Indonesia

  17. Ocean tide models for satellite geodesy and Earth rotation

    NASA Technical Reports Server (NTRS)

    Dickman, Steven R.

    1991-01-01

    A theory is presented which predicts tides in turbulent, self-gravitating, and loading oceans possessing linearized bottom friction, realistic bathymetry, and continents (at coastal boundaries no-flow conditions are imposed). The theory is phrased in terms of spherical harmonics, which allows the tide equations to be reduced to linear matrix equations. This approach also allows an ocean-wide mass conservation constraint to be applied. Solutions were obtained for 32 long and short period luni-solar tidal constituents (and the pole tide), including the tidal velocities in addition to the tide height. Calibrating the intensity of bottom friction produces reasonable phase lags for all constituents; however, tidal amplitudes compare well with those from observation and other theories only for long-period constituents. In the most recent stage of grant research, traditional theory (Liouville equations) for determining the effects of angular momentum exchange on Earth's rotation were extended to encompass high-frequency excitations (such as short-period tides).

  18. Global Earth Response to Loading by Ocean Tide Models

    NASA Technical Reports Server (NTRS)

    Estes, R. H.; Strayer, J. M.

    1979-01-01

    Mathematical and programming techniques to numerically calculate Earth response to global semidiurnal and diurnal ocean tide models were developed. Global vertical crustal deformations were evaluated for M sub 2, S sub 2, N sub 2, K sub 2, K sub 1, O sub 1, and P sub 1 ocean tide loading, while horizontal deformations were evaluated for the M sub 2 tidal load. Tidal gravity calculations were performed for M sub 2 tidal loads, and strain tensor elements were evaluated for M sub 2 loads. The M sub 2 solution used for the ocean tide included the effects of self-gravitation and crustal loading.

  19. Tide effects removed from well tests

    SciTech Connect

    Aase, E.P.B.; Jelmert, T.A.; Vik, S.A.

    1995-05-01

    To avoid distorted data when analyzing well pressure tests of permeable offshore reservoirs, one needs to account for periodic ocean tidal stress. Quartz-crystal bottom hole pressure recorders provide a high resolution of reservoir pressure but also measures pressure fluctuations from tidal effects during well testing. Periodic oscillations in the reservoir pressure are due to the three mechanisms: solid earth tide; barometric tide/effect; and ocean tide. The paper uses sample data from an offshore reservoir to illustrate how tide effects can be identified in the data and the correction procedure to use to remove these effects.

  20. Nonlinearity in rock - Evidence from earth tides

    NASA Technical Reports Server (NTRS)

    Agnew, D. C.

    1981-01-01

    The earth is sinusoidally stressed by tidal forces; if the stress-strain relation for rock is nonlinear, energy should appear in an earth tide record at frequencies which are multiples of those of the larger tidal lines. An examination of the signals to be expected for different nonlinear deformation laws shows that for a nonlinear response without dissipation, the largest anomalous signal should occur at twice the forcing frequency, whereas for nonlinear laws involving dissipation (cusped hysteresis loops) the anomalous signal will be greatest at three times this frequency. The size of the signal in the dissipative case depends on the amount by which dissipation affects the particular response being measured. For measurements of strain tides this depends on whether dissipation is assumed to be present throughout the earth or localized around the point of measurement. An analysis of 5.7 years of strain tide records from Pinon Flat, California, shows a small signal at twice the frequency of the largest (M2) tide.

  1. Influence of fortnightly earth tides at Kilauea Volcano, Hawaii.

    USGS Publications Warehouse

    Dzurisin, D.

    1980-01-01

    Analysis of 52 historic eruptions confirms the premise that fortnightly earth tides play a significant role in triggering activity at Kilauea Volcano, Hawaii. Since January 1832, nearly twice as many eruptions have occurred nearer fortnightly tidal maximum than tidal minimum (34 vs. 18). A straightforward significance test indicates that the likelihood of a fortnightly tidal influence on Kilauea eruptions is roughly 90%. This is not the case for Mauna Loa Volcano, where 37 historic eruptions have been distributed randomly with respect to the fortnightly tide. At Kilauea, stresses induced by fortnightly earth tides presumably act in concert with volcanic and tectonic stresses to trigger shallow magma movements along preexisting zones of weakness. Differences in structure or internal plumbing may limit the effectiveness of this mechanism at Mauna Loa. Tidal effects seem to be less marked at shields than at some island-arc volcanoes, possibly because higher average volcanic stress rates in Hawaii more often override the effects of tidal stresses.-Author

  2. Influence of fortnightly earth tides at Kilauea Volcano, Hawaii

    SciTech Connect

    Dzurisin, D.

    1980-11-01

    Analysis of 52 historic eruptions confirms the premise that fortnightly earth tides play a significant role in triggering activity at Kilauea Volcano, Hawaii. Since January 1832, nearly twice as many eruptions have occurred nearer fortnightly tidal maximum than tidal minimum (34 vs 18). A straightforward significance test indicates that the likelihood of a fortnightly tidal influence on Kilauea eruptions is roughly 90%. This is not the case for Mauna Loa Volcano, where 37 historic eruptions have been distributed randomly with respect to the fortnightly tide. At Kilauea, stresses induced by fortnightly earth tides presumably act in concert with volcanic and tectonic stresses to trigger shallow magma movements along preexisting zones of weakness. Differences in structure or internal plumbing may limit the effectiveness of this mechanism at Mauna Loa. Tidal effects seem to be less marked at shields than at some island-arc volcanoes, possibly because higher average volcanic stress rates in Hawaii more often override the effects of tidal stresses.

  3. Fortnightly Earth Rotation, Ocean Tides, and Mantle Anelasticity

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.; Egbert, Gary D.

    2011-01-01

    Sustained accurate measurements of earth rotation are one of the prime goals of Global Geodetic Observing System (GGOS). We here concentrate on the fortnightly (Mf) tidal component of earth-rotation data to obtain new results concerning anelasticity of the mantle at this period. The study comprises three parts: (1) a new determination of the Mf component of polar motion and length-of-day from a multi-decade time series of space-geodetic data; (2) the use of the polar-motion determination as one constraint in the development of a hydrodynamic ocean model of the Mf tide; and (3) the use of these results to place new constraints on mantle anelasticity. Our model of the Mf ocean tide assimilates more than fourteen years of altimeter data from the Topex/Poseidon and Jason-1 satellites. The polar motion data, plus tide-gauge data and independent altimeter data, give useful additional information, with only the polar motion putting constraints on tidal current velocities. The resulting ocean-tide model, plus the dominant elastic body tide, leaves a small residual in observed length-of-day caused by mantle anelasticity. The inferred effective tidal 0 of the anelastic body tide is 90 and is in line with a omega-alpha frequency dependence with alpha in the range 0.2--0.3.

  4. Fortnightly Ocean Tides, Earth Rotation, and Mantle Anelasticity

    NASA Technical Reports Server (NTRS)

    Ray, Richard; Egbert, Gary

    2012-01-01

    The fortnightly Mf ocean tide is the largest of the long-period tides (periods between 1 week and 18.6 years), but Mf is still very small, generally 2 cm or less. All long-period tides are thought to be near equilibrium with the astronomical tidal potential, with an almost pure zonal structure. However, several lines of evidence point to Mf having a significant dynamic response to forcing. We use a combination of numerical modeling, satellite altimetry, and observations of polar motion to determine the Mf ocean tide and to place constraints on certain global properties, such as angular momentum. Polar motion provides the only constraints on Mf tidal currents. With a model of the Mf ocean tide in hand, we use it to remove the effects of the ocean from estimates of fortnightly variations in length-of-day. The latter is dominated by the earth's body tide, but a small residual allows us to place new constraints on the anelasticity of the earth's mantle. The result gives the first experimental confirmation of theoretical predictions made by Wahr and Bergen in 1986.

  5. What can earth tide measurements tell us about ocean tides or earth structure?

    NASA Technical Reports Server (NTRS)

    Baker, T. F.

    1978-01-01

    Current experimental problems in Earth tides are reviewed using comparisons of tidal gravity and tilt measurements in Europe with loading calculations are examples. The limitations of present day instrumentation and installation techniques are shown as well as some of the ways in which they can be improved. Many of the geophysical and oceanographic investigations that are possible with Earth tide measurements are discussed with emphasis on the percentage accuracies required in the measurements in order to obtain new information about Earth or its oceans.

  6. Estimating Hydraulic Properties of the Floridan Aquifer System by Analysis of Earth-Tide, Ocean-Tide, and Barometric Effects, Collier and Hendry Counties, Florida

    USGS Publications Warehouse

    Merritt, Michael L.

    2004-01-01

    Aquifers are subjected to mechanical stresses from natural, non-anthropogenic, processes such as pressure loading or mechanical forcing of the aquifer by ocean tides, earth tides, and pressure fluctuations in the atmosphere. The resulting head fluctuations are evident even in deep confined aquifers. The present study was conducted for the purpose of reviewing the research that has been done on the use of these phenomena for estimating the values of aquifer properties, and determining which of the analytical techniques might be useful for estimating hydraulic properties in the dissolved-carbonate hydrologic environment of southern Florida. Fifteen techniques are discussed in this report, of which four were applied. An analytical solution for head oscillations in a well near enough to the ocean to be influenced by ocean tides was applied to data from monitor zones in a well near Naples, Florida. The solution assumes a completely non-leaky confining unit of infinite extent. Resulting values of transmissivity are in general agreement with the results of aquifer performance tests performed by the South Florida Water Management District. There seems to be an inconsistency between results of the amplitude ratio analysis and independent estimates of loading efficiency. A more general analytical solution that takes leakage through the confining layer into account yielded estimates that were lower than those obtained using the non-leaky method, and closer to the South Florida Water Management District estimates. A numerical model with a cross-sectional grid design was applied to explore additional aspects of the problem. A relation between specific storage and the head oscillation observed in a well provided estimates of specific storage that were considered reasonable. Porosity estimates based on the specific storage estimates were consistent with values obtained from measurements on core samples. Methods are described for determining aquifer diffusivity by comparing the

  7. Observing atmospheric tides in Earth rotation parameters with VLBI

    NASA Astrophysics Data System (ADS)

    Girdiuk, Anastasiia; Böhm, Johannes; Schindelegger, Michael

    2015-04-01

    In this study, we assess the contribution of diurnal (S1) and semi-diurnal (S2) atmospheric tides to variations in Earth rotation by analyzing Very Long Baseline Interferometry (VLBI) observations. Particular emphasis is placed on the dependency of S1 and S2 estimates on varying settings in the a priori delay model. We use hourly Earth rotation parameters (ERP) of polar motion and UT1 as determined with the Vienna VLBI Software (VieVS) from 25 years of VLBI observations and we adjust diurnal and semi-diurnal amplitudes to the hourly ERP estimates after disregarding the effect of high-frequency ocean tides. Prograde and retrograde polar motion coefficients are obtained for several solutions differing in processing strategies (with/without thermal deformation, time span of observations, choice of a priori ERP model and celestial pole offsets) and we compare the corresponding harmonics with those derived from atmospheric and non-tidal oceanic angular momentum estimates.

  8. The effects of mantle and anelasticity on nutations, earth tides, and tidal variations in rotation rate

    NASA Technical Reports Server (NTRS)

    Wahr, John; Bergen, Zachary

    1986-01-01

    The paper models the effects of mantle anelasticity on luni-solar nutations, on tidal deformation, on tidal variations in rotation rate, and on the eigenfrequency of the free core nutation. The results can be used to invert observations to solve for the anelastic contributions to the shear and bulk moduli of the upper and lower mantle. Specific anelastic models are used to numerically estimate the effects of anelasticity on these geodetic observables. The nutation estimates are compared with observational results. Among the conclusions: (1) mantle anelasticity is likely to be the most important source of damping for the free core nutation; (2) present VLBI nutation results are, in principle, accurate enough to usefully bound anelasticity at diurnal periods. But the discrepancy between the VLBI observed nutations and the 1984 IAU nutation model cannot be explained by anelasticity and is not yet well enough understood to allow anelasticity to be determined from the data.

  9. The global S1 tide and Earth's nutation

    NASA Astrophysics Data System (ADS)

    Schindelegger, M.; Böhm, J.; Salstein, D. A.

    2015-08-01

    Diurnal S1 tidal atmospheric oscillations induced by the cyclic heating of air masses through solar radiation elicit a small contribution to Earth's prograde annual nutation at a level of 100 μas (microarcseconds). Previously published estimates of this Sun-synchronous perturbation based on angular momentum series from global geophysical fluid models have however diverged, and within the present conventional nutation theory, the effect has been instead accounted for in an empirical manner based on analyzing residual spectra of observed celestial pole offsets. This study constitutes a first, tentative reassessment of the S1 signal in nutation by resorting to modern-day atmospheric reanalyses as well as available hydrodynamic solutions for diurnal oceanic angular momentum changes that are driven by daily air pressure variations at the water surface. We elucidate the global character of the S1 tide with particular regard to Earth rotation variations and investigate to which extent atmospheric and oceanic excitation terms from various sources can be superimposed. The combined influence of the principal diurnal tide on Earth's nutation, associated with both atmosphere and ocean dynamics, is found to yield a sound agreement with its observational evidence from geodetic VLBI (Very Long Baseline Interferometry) measurements.

  10. Interpretation of earth tide response of three deep, confined aquifers

    SciTech Connect

    Narasimhan, T.N.; Kanehiro, B.Y.; Witherspoon, P.A.

    1984-03-10

    The response of a confined, areally infinite aquifer to external loads imposed by earth tides is examined. Because the gravitational influence of celestial objects occurs over large areas of the earth, the confined aquifer is assumed to respond in an undrained fashion. Since undrained response is controlled by water compressibility, earth tide response can be directly used only to evaluate porous medium compressibility if porosity is known. Moreover, since specific storage S/sub s/ quantifies a drained behavior of the porous medium, one cannot directly estimate S/sub s/from earth tide response. Except for the fact that barometric changes act both on the water surface in the well and on the aquifer as a whole while stress changes associated with earth tides act only in the aquifer, the two phenomena influence the confined aquifer in much the same way. In other words, barometric response contains only as much information on the elastic properties of the aquifer as the earth tide response does. Factors such as well bore storage, aquifer transmissivity, and storage coefficient contribute to time lag and damping of the aquifer response as observed in the well. Analysis shows that the observation of fluid pressure changes alone, without concurrent measurement of external stress changes, is sufficient to interpret uniquely earth tide response. In the present work, change in external stress is estimated from dilatation by assuming a reasonable value for bulk modulus. Earth tide response of geothermal aquifers from Marysville, Montana. East Mesa, California; and Raft River Valley, Idaho, were analyzed, and the ratio of S/sub 3/ to porosity was estimated. Comparison of these estimates with independent pumping tests show reasonable agreement.

  11. Constraints on Energy Dissipation in the Earth's Body Tide From Satellite Tracking and Altimetry

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.; Eanes, Richard J.; Lemoine, Frank G.

    1992-01-01

    The phase lag by which the earth's body tide follows the tidal potential is estimated for the principal lunar semidiurnal tide M(sub 2). The estimate results from combining recent tidal solutions from satellite tracking data and from Topex/Poseidon satellite altimeter data. Each data type is sensitive to the body-tide lag: gravitationally for the tracking data, geometrically for the altimetry. Allowance is made for the lunar atmospheric tide. For the tidal potential Love number kappa(sub 2) we obtain a lag epsilon of 0.20 deg +/- 0.05 deg, implying an effective body-tide Q of 280 and body-tide energy dissipation of 110 +/- 25 gigawatts.

  12. The Global S_1 Tide in Earth's Nutation

    NASA Astrophysics Data System (ADS)

    Schindelegger, Michael; Einšpigel, David; Salstein, David; Böhm, Johannes

    2016-05-01

    Diurnal S_1 tidal oscillations in the coupled atmosphere-ocean system induce small perturbations of Earth's prograde annual nutation, but matching geophysical model estimates of this Sun-synchronous rotation signal with the observed effect in geodetic Very Long Baseline Interferometry (VLBI) data has thus far been elusive. The present study assesses the problem from a geophysical model perspective, using four modern-day atmospheric assimilation systems and a consistently forced barotropic ocean model that dissipates its energy excess in the global abyssal ocean through a parameterized tidal conversion scheme. The use of contemporary meteorological data does, however, not guarantee accurate nutation estimates per se; two of the probed datasets produce atmosphere-ocean-driven S_1 terms that deviate by more than 30 μ as (microarcseconds) from the VLBI-observed harmonic of -16.2+i113.4 μ as. Partial deficiencies of these models in the diurnal band are also borne out by a validation of the air pressure tide against barometric in situ estimates as well as comparisons of simulated sea surface elevations with a global network of S_1 tide gauge determinations. Credence is lent to the global S_1 tide derived from the Modern-Era Retrospective Analysis for Research and Applications (MERRA) and the operational model of the European Centre for Medium-Range Weather Forecasts (ECMWF). When averaged over a temporal range of 2004 to 2013, their nutation contributions are estimated to be -8.0+i106.0 μ as (MERRA) and -9.4+i121.8 μ as (ECMWF operational), thus being virtually equivalent with the VLBI estimate. This remarkably close agreement will likely aid forthcoming nutation theories in their unambiguous a priori account of Earth's prograde annual celestial motion.

  13. Body tides of a convecting, laterally heterogeneous, and aspherical Earth

    NASA Astrophysics Data System (ADS)

    MéTivier, Laurent; Conrad, Clinton P.

    2008-11-01

    Precise knowledge of Earth's body tides is crucial for correcting geodetic positioning measurements, satellite gravity surveys, and superconducting gravimeters with nanogal precision. With this aim, body tides are generally computed assuming a radially (or elliptically) stratified Earth. However, seismic tomography surveys and fluid dynamic studies show that thermal convection within Earth's mantle produces significant lateral heterogeneity exemplified by superplumes, superswells, and subducting slabs. To determine the influence of this heterogeneity on body tides, we used a tomographic model to constrain lateral variations in mantle density and rigidity. This heterogeneity drives convective flow that deflects Earth's surface and core-mantle boundaries by a few kilometers; we used a viscous flow model to constrain this dynamically supported asphericity. After verifying this complete Earth model using geoid observations, we used the spectral element method to determine how Earth's body tides are perturbed compared to a spherical Earth. We find maximum radial perturbations of surface and geoid displacements of 0.3 and 0.1 mm, respectively, and tidal gravity variations of 150 nGal. The amplitude of tidal gravity perturbations depends strongly on location and is greatest above large mantle density anomalies: e.g., large dense slabs (South America, Indonesia, Marianas), hot spots (Hawaii, Iceland), and the East African Rift. Predicted gravity perturbations are 100 times larger than the present precision of superconducting gravimeters and are comparable in magnitude to the unexplained residue observed at some gravimeter stations after tidal corrections. While this residue has been attributed to unmodeled loading from ocean tides, body tide perturbations caused by convection-induced mantle heterogeneity may contribute to this observed residue.

  14. Transforming Instructional Designs in Earth Science (TIDES)

    NASA Astrophysics Data System (ADS)

    McWilliams, H.; McAuliffe, C.; Penuel, W.

    2008-12-01

    An enduring challenge in Earth system science education has been to prepare teachers to teach for deep understanding of subject matter. Standards and trade textbooks are often too broad to allow for in-depth treatment of specific topics, and many teachers have had limited exposure to how to plan instruction for the core concepts of Earth system science they are expected to teach. High-quality curriculum materials do exist that provide young people with opportunities to explore concepts in depth and to experience the inquiry process. At the same time, few programs provide teachers with the necessary skills and knowledge to enact and adapt those materials to the unique circumstances of their classrooms and schools. Our interdisciplinary team of curriculum and staff developers, researchers, and district personnel developed a program focused on preparing teachers to use a principled approach to curriculum adaptation in Earth system science. In this program, teachers learned how to use the Understanding by Design (UbD) approach developed by Grant Wiggins and Jay McTighe to organize and adapt materials from an expert-designed curriculum. As part of the program, teachers learn to select or modify materials from the curriculum based on how likely the materials are to develop so-called "enduring understandings" of concepts in the district standards. Teachers also learn how to apply the approach in incorporating materials from other sources besides the expert-designed curriculum, which can include their textbook and materials they design on their own or with colleagues. Third, teachers learn how to collect and interpret evidence of student understanding by designing or adapting performance tasks that call for students to apply knowledge acquired during the unit to solve a problem or complete a project. Evidence from a randomized controlled trial indicates the program we created is effective in improving the quality of teacher assignments and in improving student achievement

  15. Why earthquakes correlate weakly with the solid Earth tides: Effects of periodic stress on the rate and probability of earthquake occurrence

    USGS Publications Warehouse

    Beeler, N.M.; Lockner, D.A.

    2003-01-01

    We provide an explanation why earthquake occurrence does not correlate well with the daily solid Earth tides. The explanation is derived from analysis of laboratory experiments in which faults are loaded to quasiperiodic failure by the combined action of a constant stressing rate, intended to simulate tectonic loading, and a small sinusoidal stress, analogous to the Earth tides. Event populations whose failure times correlate with the oscillating stress show two modes of response; the response mode depends on the stressing frequency. Correlation that is consistent with stress threshold failure models, e.g., Coulomb failure, results when the period of stress oscillation exceeds a characteristic time tn; the degree of correlation between failure time and the phase of the driving stress depends on the amplitude and frequency of the stress oscillation and on the stressing rate. When the period of the oscillating stress is less than tn, the correlation is not consistent with threshold failure models, and much higher stress amplitudes are required to induce detectable correlation with the oscillating stress. The physical interpretation of tn is the duration of failure nucleation. Behavior at the higher frequencies is consistent with a second-order dependence of the fault strength on sliding rate which determines the duration of nucleation and damps the response to stress change at frequencies greater than 1/tn. Simple extrapolation of these results to the Earth suggests a very weak correlation of earthquakes with the daily Earth tides, one that would require >13,000 earthquakes to detect. On the basis of our experiments and analysis, the absence of definitive daily triggering of earthquakes by the Earth tides requires that for earthquakes, tn exceeds the daily tidal period. The experiments suggest that the minimum typical duration of earthquake nucleation on the San Andreas fault system is ???1 year.

  16. Patterns of earthquakes and the effect of solid earth and ocean load tides at Mount St. Helens prior to the May 18, 1980, eruption

    SciTech Connect

    McNutt, S.R.; Beavan, R.J.

    1984-05-10

    Seismographs near Mount St. Helens Volcano recorded an earthquake swarm lasting nearly 2 months prior to the May 18, 1980, eruption. The earthquakes are divided into four classes based on station CPW (..delta.. = 116 km) seismogram characteristics: (1) events with Sv:P amplitude ratio > 3 and dominant frequency > 3 Hz; (2) events with Sv:P ratio between 1 and 3 and dominant frequency > 2 Hz; (3) events similar to characteristic 2 but with a strong (probably surface wave) phase just after the S phase; and (4) events with frequencies between 1 and 2 Hz lacking a clear S phase. The seismicity pattern for each of the four classes is unique. Solid earth stress and strain tides were calculated at the average hypocentral depth of 4 km. Stress and strain tides induced by ocean loading were also calculated; their amplitudes are typically 20-40% those of the solid earth tides at the location of Mount St. Helens. A weak but significant correlation exists between the latter two classes of events and the tides for a time interval of about 5 days preceding the first onset of volcanic tremor and about 5 days thereafter. The polarity of the correlation is opposite for the two classes of events. In each case, the phase of the correlation changes systematically with time, the changes coinciding with the onset of tremor on March 31 and with a pronounced decrease in earthquake energy release rate on April 3. There are no significant correlations between the tides and the number of events or energy release of these two classes of earthquakes during any other interval between March 20 and May 18, 1980. The first two classes of events show no evidence of significant tidal correlation at any time during the study period. 20 references, 8 figures, 2 tables.

  17. Resonances in solid Earth tides from VLBI observations

    NASA Astrophysics Data System (ADS)

    Gubanov, V. S.; Kurdubov, S. L.

    2015-05-01

    This work pertains to the area of exploratory research aimed at finding very fine features of the Earth's tidal deformations at the limit of the capabilities of present-day astrogeodetic observations. Based on an analysis of almost all the available VLBI observations performed within the framework of IVS (International VLBI Service) geodetic programs in 1980-2014, we have obtained the corrections to the theoretical values of complex and frequency-dependent tidal parameters (Love/Shida numbers) for the first time. Their frequency dependence arises from the resonances attributable to the retrograde free core nutation (RFCN). Our results largely confirm a high accuracy of the theory of Earth tides presented in the modern International astrogeodetic standard, the IERS Conventions (2010). However, statistically significant corrections have been found for some harmonics of the lunisolar tide-generating potential. For example, the correction to the real part of the Love number h for the wave K 1 with a frequency of 1 cpsd has turned out to be Δ h R = -0.0142 ± 0.0006, which may be indicative of a deeper resonance than that predicted by the theory in the region of diurnal tides.

  18. Chemical evolution of thermal springs at Arenal Volcano, Costa Rica: Effect of volcanic activity, precipitation, seismic activity, and Earth tides

    NASA Astrophysics Data System (ADS)

    López, D. L.; Bundschuh, J.; Soto, G. J.; Fernández, J. F.; Alvarado, G. E.

    2006-09-01

    decrease when precipitation increases. However, correlations between concentrations and the number of seismic events per month and the modeled vertical tidal acceleration are also observed. The intrinsic periodic behavior of all these variables influenced by the Earth's rotation can complicate the interpretation of the chemical changes at hot springs. For example, variations in atmospheric pressure can affect the degassing and seismic tremor of a volcano as well as the rate of precipitation. Frequent monitoring and understanding of these variations is essential at every volcano if we want to use the variations in chemical composition of hot springs in volcanic monitoring.

  19. Measurement of the Earth tides with a MEMS gravimeter

    NASA Astrophysics Data System (ADS)

    Middlemiss, R. P.; Samarelli, A.; Paul, D. J.; Hough, J.; Rowan, S.; Hammond, G. D.

    2016-03-01

    The ability to measure tiny variations in the local gravitational acceleration allows, besides other applications, the detection of hidden hydrocarbon reserves, magma build-up before volcanic eruptions, and subterranean tunnels. Several technologies are available that achieve the sensitivities required for such applications (tens of microgal per hertz1/2): free-fall gravimeters, spring-based gravimeters, superconducting gravimeters, and atom interferometers. All of these devices can observe the Earth tides: the elastic deformation of the Earth’s crust as a result of tidal forces. This is a universally predictable gravitational signal that requires both high sensitivity and high stability over timescales of several days to measure. All present gravimeters, however, have limitations of high cost (more than 100,000 US dollars) and high mass (more than 8 kilograms). Here we present a microelectromechanical system (MEMS) device with a sensitivity of 40 microgal per hertz1/2 only a few cubic centimetres in size. We use it to measure the Earth tides, revealing the long-term stability of our instrument compared to any other MEMS device. MEMS accelerometers—found in most smart phones—can be mass-produced remarkably cheaply, but none are stable enough to be called a gravimeter. Our device has thus made the transition from accelerometer to gravimeter. The small size and low cost of this MEMS gravimeter suggests many applications in gravity mapping. For example, it could be mounted on a drone instead of low-flying aircraft for distributed land surveying and exploration, deployed to monitor volcanoes, or built into multi-pixel density-contrast imaging arrays.

  20. A diurnal resonance in the ocean tide and in the earth's load response due to the resonant free 'core nutation'

    NASA Technical Reports Server (NTRS)

    Wahr, J. M.; Sasao, T.

    1981-01-01

    The effects of the oceans, which are subject to a resonance due to a free rotational eigenmode of an elliptical, rotating earth with a fluid outer core having an eigenfrequency of (1 + 1/460) cycle/day, on the body tide and nutational response of the earth to the diurnal luni-tidal force are computed. The response of an elastic, rotating, elliptical, oceanless earth with a fluid outer core to a given load distribution on its surface is first considered, and the tidal sea level height for equilibrium and nonequilibrium oceans is examined. Computations of the effects of equilibrium and nonequilibrium oceans on the nutational and deformational responses of the earth are then presented which show small but significant perturbations to the retrograde 18.6-year and prograde six-month nutations, and more important effects on the earth body tide, which is also resonant at the free core notation eigenfrequency.

  1. Strong correlation of major earthquakes with solid-earth tides in part of the eastern United States

    USGS Publications Warehouse

    Weems, R.E.; Perry, W.H.

    1989-01-01

    East of the eastern American continental divide and south of lat. 42.5??N, moderate to large historic earthquakes correlate strongly with times of high and low solid-earth tides. This effect is most pronounced when solar declination lies between 17??N and 17??S. Significant correlation also exist between major earthquakes, time of day, lunar declinations, and lunar phase. -Authors

  2. Microearthquakes at st. Augustine volcano, alaska, triggered by Earth tides.

    PubMed

    Mauk, F J; Kienle, J

    1973-10-26

    Microearthquake activity at St. Augustine volcano, located at the mouth of Cook Inlet in the Aleutian Islands, has been monitored since August 1970. Both before and after minor eruptive activity on 7 October 1971, numerous shallow-foci microearthquake swarms were recorded. Plots of the hourly frequency of microearthquakes often show a diurnal peaking of activity. A cross correlation of this activity with the calculated magnitudes of tidal acceleration exhibited two prominent phase relationships. The first, and slightly more predominant, phase condition is a phase delay in the microearthquake activity of approximately 1 hour from the time of maximum tidal acceleration. This is thought to be a direct microearthquake-triggering effect caused by tidal stresses. The second is a phase delay in the microearthquake activity of approximately 5 hours, which correlates well with the time of maximum oceanic tidal loading. Correlation of the individual peaks of swarm activity with defined components of the tides suggests that it may be necessary for tidal stressing to have a preferential orientation in order to be an effective trigger of microearthquakes.

  3. The Global S[Formula: see text] Tide in Earth's Nutation.

    PubMed

    Schindelegger, Michael; Einšpigel, David; Salstein, David; Böhm, Johannes

    Diurnal S[Formula: see text] tidal oscillations in the coupled atmosphere-ocean system induce small perturbations of Earth's prograde annual nutation, but matching geophysical model estimates of this Sun-synchronous rotation signal with the observed effect in geodetic Very Long Baseline Interferometry (VLBI) data has thus far been elusive. The present study assesses the problem from a geophysical model perspective, using four modern-day atmospheric assimilation systems and a consistently forced barotropic ocean model that dissipates its energy excess in the global abyssal ocean through a parameterized tidal conversion scheme. The use of contemporary meteorological data does, however, not guarantee accurate nutation estimates per se; two of the probed datasets produce atmosphere-ocean-driven S[Formula: see text] terms that deviate by more than 30 [Formula: see text]as (microarcseconds) from the VLBI-observed harmonic of [Formula: see text] [Formula: see text]as. Partial deficiencies of these models in the diurnal band are also borne out by a validation of the air pressure tide against barometric in situ estimates as well as comparisons of simulated sea surface elevations with a global network of S[Formula: see text] tide gauge determinations. Credence is lent to the global S[Formula: see text] tide derived from the Modern-Era Retrospective Analysis for Research and Applications (MERRA) and the operational model of the European Centre for Medium-Range Weather Forecasts (ECMWF). When averaged over a temporal range of 2004 to 2013, their nutation contributions are estimated to be [Formula: see text] [Formula: see text]as (MERRA) and [Formula: see text] [Formula: see text]as (ECMWF operational), thus being virtually equivalent with the VLBI estimate. This remarkably close agreement will likely aid forthcoming nutation theories in their unambiguous a priori account of Earth's prograde annual celestial motion.

  4. An objective frequency domain method for quantifying confined aquifer compressible storage using Earth and atmospheric tides

    NASA Astrophysics Data System (ADS)

    Acworth, R. Ian; Halloran, Landon J. S.; Rau, Gabriel C.; Cuthbert, Mark O.; Bernardi, Tony L.

    2016-11-01

    The groundwater hydraulic head response to the worldwide and ubiquitous atmospheric tide at 2 cycles per day (cpd) is a direct function of confined aquifer compressible storage. The ratio of the responses of hydraulic head to the atmospheric pressure change is a measure of aquifer barometric efficiency, from which formation compressibility and aquifer specific storage can be determined in situ rather than resorting to laboratory or aquifer pumping tests. The Earth tide also impacts the hydraulic head response at the same frequency, and a method is developed here to quantify and remove this interference. As a result, the barometric efficiency can be routinely calculated from 6-hourly hydraulic head, atmospheric pressure, and modeled Earth tide records where available for a minimum of 15 days duration. This new approach will be of critical importance in assessing worldwide problems of land subsidence or groundwater resource evaluation that both occur due to groundwater abstraction.

  5. Troposphere-Thermosphere Coupling by Thermal Tides at Earth and Mars

    NASA Astrophysics Data System (ADS)

    Forbes, J. M.

    2008-05-01

    The main point of my talk is to demonstrate that the surface properties of Earth and Mars strongly influence the zonal structures of their thermospheres, more than 100 km overhead. This happens through longitudinal modulation of solar thermal tide excitation near the surface, whereupon the tides propagate vertically, grow exponentially, and impose the same zonal asymmetry on the thermosphere. On Earth, diurnally-varying solar radiation sweeping over the wave-4 land sea distribution leads to evaporation and (ultimately) latent heating that strongly excites the eastward-propagating diurnal tide with zonal wavenumber s = - 3 (DE3). On Mars, the strong wave-2 topography, vis-a-vis the kinematic boundary condition, similarly excites the s = -1 eastward-propagating diurnal tide (DE1), which is in near-resonance on Mars. In the thermosphere, when viewed in a Sun-synchronous frame, DE3 and DE1 appear as wave-4 and wave-2 longitudinal variations, the same zonal wavenumbers characterizing the surfaces of Earth and Mars, respectively. Implications for modulation of Earth's ionosphere, and the aerobraking region of Mars, are also presented.

  6. A study on variation in position of an Indian station due to solid earth tides

    NASA Astrophysics Data System (ADS)

    Ghosh, Jayanta Kumar; Pathak, Shray

    2015-04-01

    In many geodetic analyses, it is important to consider the effect of earth tide on the instantaneous position of a station and its subsequent influence on the computation and interpretation of time series of coordinates as well as related data products. The tidal effect and temporal variations in the position of the IGS (International Global Navigational Satellite Systems [GNSS] Service) stations at Hyderabad (India), Ankara (Turkey) and Beijing Fangshan (China), due to solid earth tides has been studied. Surface tidal displacement of the station has been computed on daily basis for a month, based on the concept of gravity. Further, mean daily coordinates of the station been computed using static precise point positioning (PPP) method for a month. Results show that the station undergoes temporal displacements and its coordinates vary continuously within a day and all the days in the month. The maximum range in vertical displacement of the station has been found to be about 48 cm in a day over a period of a month and that along the north and east directions is respectively 8 cm and 14 cm. This is the maximum range but the mean value in the vertical displacement is 6 cm and along north and east is 1.7 cm and 0.09 cm, respectively. The ranges in variation in the mean value of geodetic latitude, longitude, and height of the station have been found to be 1.23, 2.73, and 3.52 cm, respectively. Further, it has been found that the tidal oscillations follow some periodicity, and thus need to be studied independently for all stations.

  7. The magnetic field induced by the bodily tide in the core of the Earth.

    PubMed

    Pekeris, C L

    1971-06-01

    The motion in the liquid core of the earth due to the bodily tide can induce a periodic magnetic field having the frequency sigma of the tide as well as multiple frequencies, including a steady term. The coupling coefficient for the steady term between the convectively inducing and induced fields is estimated to be of the order of sigmaH(2)/lambda, where H denotes the height of the equilibrium tide, and lambda = 1/4pikappa, kappa denoting the electrical conductivity of the core. With sigma = 1.4 x 10(-4) sec(-1), H = 20 cm, and kappa = 3 x 10(-6) emu, the coupling coefficient comes out only of the order of 10(-6), as against unity in the case of the dynamo theory.

  8. Earth Tide Algorithms for the OMNIS Computer Program System.

    DTIC Science & Technology

    1986-04-01

    This report presents five computer algorithms that jointly specify the gravitational action by which the tidal redistributions of the Earth’s masses...routine is a simplified version of the fourth and is provided for use during computer program verification. All computer algorithms express the tidal

  9. Kingdom of the Tides.

    ERIC Educational Resources Information Center

    Carter, Samuel, III

    Areas of discussion are the history of tides, the forces which exert an influence upon the earth's tides, the behavior of tides as modified by terrestrial features, "freak" behavior of tides, the marine life which inhabits tidal areas, the manner in which tides have helped to shape the course of history, how tides affect our lives on a…

  10. Extensometric observation of Earth tides and local tectonic processes at the Vyhne station, Slovakia

    NASA Astrophysics Data System (ADS)

    Brimich, Ladislav; Bednárik, Martin; Bezák, Vladimír; Kohút, Igor; Bán, Dóra; Eper-Pápai, Ildikó; Mentes, Gyula

    2016-06-01

    The Vyhne Tidal Station of the Earth Science Institute of the Slovak Academy of Sciences is located in the former mining gallery of St. Anthony of Padua in the Vyhne valley, Štiavnické vrchy Mts., Central Slovakia. It is equipped with a 20.5 metre long quartz-tube extensometer measuring Earth's tides, and long-term tectonic deformations of the Earth's crust. Data between 2001 and 2015 with some diverse gaps were digitally collected, processed and analysed. The effects of the local conditions, such as structure of the observatory, cavity effect, topography and geological features of the surrounding rocks, were investigated in detail and these effects were taken into consideration during the interpretation of the results of the data analysis. Tidal analysis of the extensometric data between 2005 and 2015 revealed that the measured tidal amplitudes are close to the theoretical values. The tidal transfer of the observatory was also investigated by coherence analysis between the theoretical and the measured extensometric data. The coherence is better than 0.9 both in the diurnal and semidiurnal band. The effect of the free core nutation resonance was also investigated in the case of the K1 and P1 tidal components. Since the K1/O1 ratio was about the theoretical value 0.8, than the P1/O1 was between 1.0 and 1.15 instead of the theoretical value of 0.9. The rate of the long-term strain rate was also investigated and the obtained -0.05 μstr/y shows a good agreement with the strain rate inferred from GPS measurements in the Central European GPS Reference Network.

  11. Frequency-dependence of the Love Numbers due to the Earth's Quasi-Rheology, Mantle Anelasticity and Ocean Tides

    NASA Astrophysics Data System (ADS)

    Chen, W.; Shen, W.; Huang, C.

    2012-12-01

    Love numbers are defined as dimensionless coefficients to characterize the deformations caused by an applied volume potential. For the complex Earth system, Love numbers are not constants but vary with frequency due to the following three factors: 1. the resonance behavior of the wobble motions near its eigen-frequencies, such as the well-known free core nutation resonance in the diurnal tides; 2. the mantle anelasticity of which the role becomes more significant as the frequency gets lower; and 3. the quasi-fluid rheology describing the Earth's fluid-like deformations at geological time scales. In this study, we present a power law for mantle anelasticity constrained by Chandler wobble parameters (the period TC and the quality factor QC) and an empirical quasi-fluid rheology model with a linear dependence on frequency for a period as long as 18.6 years. The models of mantle anelasticity and quasi-fluid rheology can provide good estimates of oceanless Love numbers at arbitrary frequencies with periods ranging from ~1 day to ~18.6 years, when comparing to the observed values for some frequencies. To account for the effects of dynamic oceans on the Love numbers, the diurnal ocean tides from the IERS Conventions (2010), the long-period ocean model of Dickman & Gross (2010) and the equilibrium ocean pole tide model of Desai (2002) are adopted to calculate the oceanic corrections to the Love numbers. We find due to the mantle anelasticity, the equilibrium ocean pole tides will cause imaginary parts to the Love numbers and have notable influence on the geophysical estimate of the QC value, which was disregarded before. In addition, we show that the Chandler wobble parameters derived from our Love number model are consistent with the observations. Thus, we conclude that our model of frequency-dependent Love numbers should be reliable. This study is supported partly by the National Natural Science Foundation China (Grant Numbers 41174011, 41128003, 41021061 and 40974015).

  12. Response of Water Levels in Devils Hole, Death Valley National Park, Nevada, to Atmospheric Loading, Earth Tides, and Earthquakes

    NASA Astrophysics Data System (ADS)

    Cutillo, P. A.; Ge, S.

    2004-12-01

    Devils Hole, home to the endangered Devils Hole pupfish (Cyprinodon diabolis) in Death Valley National Park, Nevada, is one of about 30 springs and the largest collapse depression in the Ash Meadows area. The small pool leads to an extensive subterranean cavern within the regional Paleozoic carbonate-rock aquifer. Previous work has established that the pool level fluctuates in response to changes in barometric pressure, Earth tides and earthquakes. Analyses of these fluctuations indicate that the formation is a sensitive indicator of crustal strain, and provide important information regarding the material properties of the surrounding aquifer. Over ten years of hourly water-level measurements were analyzed for the effects of atmospheric loading and Earth tides. The short-term water-level fluctuations caused by these effects were found to be on the order of millimeters to centimeters, indicating relatively low matrix compressibility. Accordingly, the Devils Hole water-level record shows strong responses to the June 28, 1992 Landers/Little Skull Mountain earthquake sequence and to the October 16, 1999 Hector Mine earthquake. A dislocation model was used to calculate volumetric strain for each earthquake. The sensitivity of Devils Hole to strain induced by the solid Earth tide was used to constrain the modeling. Water-level decreases observed following the 1992 and 1999 earthquakes were found to be consistent with areas of crustal expansion predicted by the dislocation model. The magnitude of the water-level changes was also found to be proportional to the predicted coseismic volumetric strain. Post-seismic pore-pressure diffusion, governed by the hydraulic diffusivity of the aquifer, was simulated with a numerical model using the coseismic change in pore pressure as an initial condition. Results of the numerical model indicate that factors such as fault-plane geometry and aquifer heterogeneity may play an important role in controlling pore pressure diffusion in the

  13. High-frequency Earth rotation variations deduced from altimetry-based ocean tides

    NASA Astrophysics Data System (ADS)

    Madzak, Matthias; Schindelegger, Michael; Böhm, Johannes; Bosch, Wolfgang; Hagedoorn, Jan

    2016-11-01

    A model of diurnal and semi-diurnal variations in Earth rotation parameters (ERP) is constructed based on altimetry-measured tidal heights from a multi-mission empirical ocean tide solution. Barotropic currents contributing to relative angular momentum changes are estimated for nine major tides in a global inversion algorithm that solves the two-dimensional momentum equations on a regular 0.5° grid with a heavily weighted continuity constraint. The influence of 19 minor tides is accounted for by linear admittance interpolation of ocean tidal angular momentum, although the assumption of smooth admittance variations with frequency appears to be a doubtful concept for semi-diurnal mass terms in particular. A validation of the newly derived model based on post-fit corrections to polar motion and universal time (Δ UT1) from the analysis of Very Long Baseline Interferometry (VLBI) observations shows a variance reduction for semi-diurnal Δ UT1 residuals that is significant at the 0.05 level with respect to the conventional ERP model. Improvements are also evident for the explicitly modeled K_1, Q_1, and K_2 tides in individual ERP components, but large residuals of more than 15 μ as remain at the principal lunar frequencies of O_1 and M_2. We attribute these shortcomings to uncertainties in the inverted relative angular momentum changes and, to a minor extent, to violation of mass conservation in the empirical ocean tide solution. Further dedicated hydrodynamic modeling efforts of these anomalous constituents are required to meet the accuracy standards of modern space geodesy.

  14. Earthquake Weather: Linking Seismicity to Changes in Barometric Pressure, Earth Tides, and Rainfall

    NASA Astrophysics Data System (ADS)

    West, J. D.; Garnero, E.; Shirzaei, M.

    2015-12-01

    It has been widely observed that earthquakes can be triggered due to changes in stress induced by the passage of surface waves from remote earthquakes. These stress changes are typically on the order of a few kiloPascals and occur over time spans of seconds. Less well investigated is the question of whether triggering of seismic activity can result from similar stress changes occurring over periods of hours or days due to changing barometric pressure, rainfall, and Earth tides. Past studies have shown a possible link between these stress sources and slow earthquakes in Taiwan (Hsu et al., 2015). Here, we investigate the relationship between seismicity and changing barometric pressure, Earth tides, and rainfall for four regions of the western United States where regional seismic networks provide high-quality seismic catalogs over relatively long time periods: Southern California, Northern California, the Pacific Northwest, and Utah. For each region we obtained seismic catalogs from January 2001 through September 2014 and acquired hourly data for barometric pressure and rainfall across the regions from the National Climatic Data Center. The vertical stress time series due to Earth tides was computed for the location of each weather station in the study areas. We summed the stresses from these 3 sources and looked for variations in seismicity correlated to the stress changes. We show that seismicity rates increase with increasing magnitude of stress change. In many cases the increase in seismicity is larger for reductions in vertical stress than it is for stress increases. We speculate that the dependency of seismic rate on combined vertical stress is acting through a combination of two mechanisms: (1) Reduced stresses reduce the normal force on faults, triggering failure in critically-stressed faults. (2) Increased stresses may similarly reduce the normal force on faults due to increases in pore pressure induced in the fault region.

  15. Triggering and modulation of geyser eruptions in Yellowstone National Park by earthquakes, earth tides, and weather

    NASA Astrophysics Data System (ADS)

    Hurwitz, Shaul; Sohn, Robert A.; Luttrell, Karen; Manga, Michael

    2014-03-01

    We analyze intervals between eruptions (IBEs) data acquired between 2001 and 2011 at Daisy and Old Faithful geysers in Yellowstone National Park. We focus our statistical analysis on the response of these geysers to stress perturbations from within the solid earth (earthquakes and earth tides) and from weather (air pressure and temperature, precipitation, and wind). We conclude that (1) the IBEs of these geysers are insensitive to periodic stresses induced by solid earth tides and barometric pressure variations; (2) Daisy (pool geyser) IBEs lengthen by evaporation and heat loss in response to large wind storms and cold air; and (3) Old Faithful (cone geyser) IBEs are not modulated by air temperature and pressure variations, wind, and precipitation, suggesting that the subsurface water column is decoupled from the atmosphere. Dynamic stress changes of 0.1-0.2 MPa resulting from the 2002 M-7.9 Denali, Alaska, earthquake surface waves caused a statistically significant shortening of Daisy geyser's IBEs. Stresses induced by other large global earthquakes during the study period were at least an order of magnitude smaller. In contrast, dynamic stresses of >0.5 MPa from three large regional earthquakes in 1959, 1975, and 1983 caused lengthening of Old Faithful's IBEs. We infer that most subannual geyser IBE variability is dominated by internal processes and interaction with other geysers. The results of this study provide quantitative bounds on the sensitivity of hydrothermal systems to external stress perturbations and have implications for studying the triggering and modulation of volcanic eruptions by external forces.

  16. Response of the water level in a well to Earth tides and atmospheric loading under unconfined conditions

    USGS Publications Warehouse

    Rojstaczer, S.; Riley, F.S.

    1990-01-01

    The response to Earth tides is strongly governed by a dimensionless aquifer frequency Q???u. The response to atmospheric loading is strongly governed by two dimensionless vertical fluid flow parameters: a dimensionless unsaturated zone frequency, R, and a dimensionless aquifer frequency Qu. The differences between Q???u and Qu are generally small for aquifers which are highly sensitive to Earth tides. When Q???u and Qu are large, the response of the well to Earth tides and atmospheric loading approaches the static response of the aquifer under confined conditions. At small values of Q???u and Qu, well response to Earth tides and atmospheric loading is strongly influenced by water table drainage. When R is large relative to Qu, the response to atmospheric loading is strongly influenced by attenuation and phase shift of the pneumatic pressure signal in the unsaturated zone. The presence of partial penetration retards phase advance in well response to Earth tides and atmospheric loading. -from Authors

  17. Towards Tidal Tomography: Using Earth's Body-Tide Signal to Constrain Deep-Mantle Density Structure

    NASA Astrophysics Data System (ADS)

    Lau, Harriet; Yang, Hsin-Ying; Davis, James; Mitrovica, Jerry; Tromp, Jeroen; Latychev, Konstantin

    2015-04-01

    Luni-solar forcings drive long wavelength deformation at timescales ranging from 8 hours to 18.6 years. We propose that globally distributed GPS estimates of this deformation within the semi-diurnal band provide a new and independent constraint on long-wavelength deep mantle structure. A particular target of "tidal tomography" is the buoyancy structure of LLSVPs, which constitute a large volumetric fraction of the mantle. Constraining this structure is the key to understanding the longevity of the LLSVPs, and indeed the evolution of the entire mantle and Earth system. To this end, we begin by reporting on the development of a new normal-mode theory, based on relatively recent advances in free oscillation seismology, which is capable of predicting semi-diurnal body tides on a laterally heterogeneous, rotating and anelastic Earth. We next present the results of a suite of benchmark tests involving comparisons with predictions based on both classical tidal Love number theory for 1-D Earth models and finite-volume simulations that incorporate 3-D elastic and density structure. We find that body tide deformation is most sensitive to long wavelength, deep mantle structure, and, in particularly, to shear wave velocity and density structure. When combined with results from seismological datasets, this sensitivity provides a powerful tool to investigate the buoyancy structure of the LLSVPs. For example, adopting a variety of seismic tomography models a priori, we perform an extensive parameter search to determine misfits between model predictions based on the new theory and GPS-derived estimates of the semi-diurnal body tide displacements. Preliminary results, focusing only on density structure, have indicated that the observations are best fit when the LLSVPs have a bulk density greater than average mantle, in broad agreement with previous inferences based upon seismic normal mode inversions. In follow-up work, we have mapped out trade-offs related to the adopted seismic

  18. Numerical modeling of the oceanic S1 tide for Earth rotation studies

    NASA Astrophysics Data System (ADS)

    Schindelegger, Michael; Einspigel, David

    2015-04-01

    Diurnal S1 oceanic oscillations induced by atmospheric pressure loading elicit small but measurable perturbations of universal time, polar motion, and the prograde annual component of nutation. In a priori models of Earth rotation variations, these signals are as-yet unconsidered'partly due to the fact that the underlying globally-gridded S1 harmonics can only be inferred from purely hydrodynamic ocean models which lack the reliable elevation constraints from satellite altimetry. Such free-running forward integrations of the shallow water equations usually overestimate tidal energies and therefore also OAM (oceanic angular momentum), unless the model formulation allows for significant dissipation in the deep ocean. For practical purposes, abyssal energy flux and hence the accuracy of tidal elevations can be controlled by a tunable but inordinately high viscosity value or by evoking additional quadratic wave drag when surface heights change rapidly. A third and physically plausible modeling route is to parametrize the sub-grid scale conversion of barotropic currents into small internal tides by aid of a linear drag term. In the present paper, we study the impact of these different dissipation schemes on the fidelity of surface elevations in a simple barotropic time-stepping model forced by selected gravitational equilibrium tides as well as diurnal air pressure variations. After determining the optimal drag formulation through validation runs with the well-known principal gravitational K1 tide, the OAM values for each of the hydrodynamic S1 solutions are documented and discussed in the specific context of their contribution to the prograde annual signal in Earth's nutation.

  19. Absence of earthquake correlation with Earth tides: An indication of high preseismic fault stress rate

    USGS Publications Warehouse

    Vidale, J.E.; Agnew, D.C.; Johnston, M.J.S.; Oppenheimer, D.H.

    1998-01-01

    Because the rate of stress change from the Earth tides exceeds that from tectonic stress accumulation, tidal triggering of earthquakes would be expected if the final hours of loading of the fault were at the tectonic rate and if rupture began soon after the achievement of a critical stress level. We analyze the tidal stresses and stress rates on the fault planes and at the times of 13,042 earthquakes which are so close to the San Andreas and Calaveras faults in California that we may take the fault plane to be known. We find that the stresses and stress rates from Earth tides at the times of earthquakes are distributed in the same way as tidal stresses and stress rates at random times. While the rate of earthquakes when the tidal stress promotes failure is 2% higher than when the stress does not, this difference in rate is not statistically significant. This lack of tidal triggering implies that preseismic stress rates in the nucleation zones of earthquakes are at least 0.15 bar/h just preceding seismic failure, much above the long-term tectonic stress rate of 10-4 bar/h.

  20. Diurnal and Semidiurnal Variations in the Earth's Rotation Rate Induced by Oceanic Tides.

    PubMed

    Ray, R D; Steinberg, D J; Chao, B F; Cartwright, D E

    1994-05-06

    Recent space-geodetic observations have revealed daily and subdaily variations in the Earth's rotation rate. Although spectral analysis suggests that the variations are primarily of tidal origin, comparisons to previous theoretical predictions based on various ocean models have been less than satisfactory. This disagreement is partly caused by deficiencies in physical modeling. Rotation predictions based on a reliable tidal-height model, with corresponding tidal currents inferred from a modified form of Laplace's momentum equations, yield predictions of tidal variations in Universal Time that agree with very long baseline interferometer observations to 2 microseconds. This agreement resolves a major discrepancy between theory and observation and establishes the dominant role of oceanic tides for inducing variation in the Earth's rotation at these frequencies.

  1. Triggering and modulation of geyser eruptions in Yellowstone National Park by earthquakes, earth tides, and weather

    USGS Publications Warehouse

    Hurwitz, Shaul; Sohn, Robert A.; Luttrell, Karen; Manga, Michael

    2014-01-01

    We analyze intervals between eruptions (IBEs) data acquired between 2001 and 2011 at Daisy and Old Faithful geysers in Yellowstone National Park. We focus our statistical analysis on the response of these geysers to stress perturbations from within the solid earth (earthquakes and earth tides) and from weather (air pressure and temperature, precipitation, and wind). We conclude that (1) the IBEs of these geysers are insensitive to periodic stresses induced by solid earth tides and barometric pressure variations; (2) Daisy (pool geyser) IBEs lengthen by evaporation and heat loss in response to large wind storms and cold air; and (3) Old Faithful (cone geyser) IBEs are not modulated by air temperature and pressure variations, wind, and precipitation, suggesting that the subsurface water column is decoupled from the atmosphere. Dynamic stress changes of 0.1−0.2 MPa resulting from the 2002 M-7.9 Denali, Alaska, earthquake surface waves caused a statistically significant shortening of Daisy geyser's IBEs. Stresses induced by other large global earthquakes during the study period were at least an order of magnitude smaller. In contrast, dynamic stresses of >0.5 MPa from three large regional earthquakes in 1959, 1975, and 1983 caused lengthening of Old Faithful's IBEs. We infer that most subannual geyser IBE variability is dominated by internal processes and interaction with other geysers. The results of this study provide quantitative bounds on the sensitivity of hydrothermal systems to external stress perturbations and have implications for studying the triggering and modulation of volcanic eruptions by external forces.

  2. The influence of formation material properties on the response of water levels in wells to Earth tides and atmospheric loading

    USGS Publications Warehouse

    Rojstaczer, S.; Agnew, D.C.

    1989-01-01

    The water level in an open well can change in response to deformation of the surrounding material, either because of applied strains (tidal or tectonic) or surface loading by atmospheric pressure changes. Under conditions of no vertical fluid flow and negligible well bore storage (static-confined conditions), the sensitivities to these effects depend on the elastic properties and porosity which characterize the surrounding medium. The hydraulic diffusivity which governs pressure diffusion in response to surface loading is slightly smaller than that which governs fluid flow in response to applied strain. Analysis of the static-confined response of five wells to atmospheric loading and Earth tides gives generally reasonable estimates for material properties. -from Authors

  3. What Causes Tides?

    ERIC Educational Resources Information Center

    Donovan, Deborah

    2004-01-01

    The phenomenon of tides has a faraway source. This rise and fall of the water level over a period of several hours is a result of the gravitational pull of the Moon and the Sun on Earth's oceans. Tides exhibit predictable cycles on daily, monthly, and yearly scales. The magnitude of the tides is dependent on the position of the Earth and Moon in…

  4. Review of Florida Red Tide and Human Health Effects.

    PubMed

    Fleming, Lora E; Kirkpatrick, Barbara; Backer, Lorraine C; Walsh, Cathy J; Nierenberg, Kate; Clark, John; Reich, Andrew; Hollenbeck, Julie; Benson, Janet; Cheng, Yung Sung; Naar, Jerome; Pierce, Richard; Bourdelais, Andrea J; Abraham, William M; Kirkpatrick, Gary; Zaias, Julia; Wanner, Adam; Mendes, Eliana; Shalat, Stuart; Hoagland, Porter; Stephan, Wendy; Bean, Judy; Watkins, Sharon; Clarke, Tainya; Byrne, Margaret; Baden, Daniel G

    2011-01-01

    This paper reviews the literature describing research performed over the past decade on the known and possible exposures and human health effects associated with Florida red tides. These harmful algal blooms are caused by the dinoflagellate, Karenia brevis, and similar organisms, all of which produce a suite of natural toxins known as brevetoxins. Florida red tide research has benefited from a consistently funded, long term research program, that has allowed an interdisciplinary team of researchers to focus their attention on this specific environmental issue-one that is critically important to Gulf of Mexico and other coastal communities. This long-term interdisciplinary approach has allowed the team to engage the local community, identify measures to protect public health, take emerging technologies into the field, forge advances in natural products chemistry, and develop a valuable pharmaceutical product. The Review includes a brief discussion of the Florida red tide organisms and their toxins, and then focuses on the effects of these toxins on animals and humans, including how these effects predict what we might expect to see in exposed people.

  5. Structure and dynamical effects of the thermal tide in the Venus atmosphere

    NASA Astrophysics Data System (ADS)

    Takagi, Masahiro; Sugimoto, Norihiko; Ando, Hiroki; Matsuda, Yoshihisa

    2016-10-01

    We investigate structure and dynamical effects of the thermal tide in the Venus atmosphere by using a general circulation model (GCM). The thermal tide is important for the Venus atmospheric dynamics (Fels and Lindzen, 1974; Plumb, 1975; Newman and Leovy, 1992; Takagi and Matsuda, 2007). However, its three-dimensional structure has not been fully investigated so far. It is expected that detailed wind distributions of the thermal tide will be obtained by the Venus Climate Orbiter Akatsuki in the near future. It is necessary to investigate its structure so that the observational results can be interpreted in terms of dynamics. The GCM used in the present study is AFES for Venus (Sugimoto et al., 2014a, b). The resolution is set to T64L120. The model atmosphere extends from the ground to ~120 km. The infrared radiative transfer process is simplified by the Newtonian cooling approximation. See Sugimoto et al. (2014a, b) for more model details. The initial state is an idealized superrotating flow in solid body rotation. The GCM is integrated for 5 Earth years. The result shows that the semidiurnal and diurnal tides are predominant in low and high latitudes poleward of 60 degrees, respectively. The diurnal tide is trapped at 55-75 km levels; the phase is almost unchanged in the vertical direction. This result indicates that the subsolar-antisolar (SS-AS) circulation is predominant at these levels. The strong upward wind is located at early afternoon and near the morning and evening terminators. The vertical velocity of the SS-AS circulation is 0.04 m/s, which is ~10 times as fast as that of the mean meridional circulation (MMC). Titov et al. (2012) pointed out that dark regions are observed in the evening region, suggesting that the dark material is transported from below. These results suggest that the SS-AS circulation is quite important to the material transport at the cloud levels in the Venus atmosphere. The preliminary analysis also shows that the MMC at 50-90 km

  6. The Effect of Warming Oceans at a Tide Gauge Station

    NASA Astrophysics Data System (ADS)

    Bâki Iz, H.

    2016-09-01

    This study proposes a new paradigm for assessing thermosteric effects of warming oceans at a tide gauge station. For demonstration, the trend due to the global thermosteric sea level at the Key West, FL tide gauge station was estimated using the tide gauge measurements and the global sea surface temperature anomalies that were represented by yearly distributed lags. A comparison of the estimate with the trend estimate from a descriptive model revealed that 0.7±0.1 mm/yr, (p<0.01), of the total trend 2.2±0.1 mm/yr (p<0.01) estimated using the descriptive model can be attributed to the global warming of the oceans during the last century at this station. The remaining 1.5±0.1 mm/yr, 70 percent of the total trend, is the lump sum estimate of the secular changes due to the eustatic, halosteric, and various local isostatic contributions.

  7. Influence of ocean tides on the diurnal and semidiurnal earth rotation variations from VLBI observations

    NASA Astrophysics Data System (ADS)

    Gubanov, V. S.; Kurdubov, S. L.

    2015-05-01

    The International astrogeodetic standard IERS Conventions (2010) contains a model of the diurnal and semidiurnal variations in Earth rotation parameters (ERPs), the pole coordinates and the Universal Time, arising from lunisolar tides in the world ocean. This model was constructed in the mid-1990s through a global analysis of Topex/Poseidon altimetry. The goal of this study is to try to estimate the parameters of this model by processing all the available VLBI observations on a global network of stations over the last 35 years performed within the framework of IVS (International VLBI Service) geodetic programs. The complexity of the problemlies in the fact that the sought-for corrections to the parameters of this model lie within 1 mm and, thus, are at the limit of their detectability by all currently available methods of ground-based positional measurements. This requires applying universal software packages with a high accuracy of reduction calculations and a well-developed system of controlling the simultaneous adjustment of observational data to analyze long series of VLBI observations. This study has been performed with the QUASAR software package developed at the Institute of Applied Astronomy of the Russian Academy of Sciences. Although the results obtained, on the whole, confirm a high accuracy of the basic model in the IERS Conventions (2010), statistically significant corrections that allow this model to be refined have been detected for some harmonics of the ERP variations.

  8. Venus' rotation and atmospheric tides

    NASA Technical Reports Server (NTRS)

    Ingersoll, A. P.; Dobrovolskis, A. R.

    1978-01-01

    On the basis of a presented theory, it is suggested that Venus' current rotation is a stable balance between atmospheric and solar body tides. The theory is concerned with Venus' atmospheric tides, driven by solar heating, and how these tides could serve as a third torque to balance the effects of solar body torque and to maintain a stable equilibrium resonance with regard to the earth's gravitational effects. In the absence of the atmospheric tidal torque, or some other torque, it would be expected that Venus would be despun until synchronous rotation (one side always facing the sun) is attained, rather than retain the retrograde rotation period of 243 days.

  9. The use of the Earth tide-seismicity compliance parameter maps for earthquake risk mitigation

    NASA Astrophysics Data System (ADS)

    Arabelos D. N.; Contadakis, M. E.; Vergos, G.; S. Spatalas

    2016-04-01

    Applying the Hi(stogram)Cum(ulation) method, which was introduced recently by Cadicheanu, van Ruymbecke and Zhu (2007), we analyze the series of the earthquakes occurred in the last 50 years in seismic active areas of Greece, i.e. the areas (a) of the Mygdonian Basin(Contadakis et al. 2007), (b) of the Ionian Islands (Contadakis et al. 2012 ) and (c) of the Hellenic Arc (Vergos et al. 2015 ) . The result of the analysis for all the areas indicate that the monthly variation of the earthquake frequency is in accordance with the period of the tidal lunar monthly and semi-monthly (Mm and Mf) variations and the same happens with the corresponding daily variations of the frequencies of earthquake occurrence with the diurnal luni-solar (K1) and semidiurnal lunar (M2) tidal variations. In addition the confidence level for the identification of such period accordance between earthquakes occurrence and tidal periods varies with seismic activity, i.e. the higher confidence level corresponds to time periods with stronger seismic activity. These results are in favor of a tidal triggering process on earthquakes when the stress in the focal area is near the critical level (Vidale 1998). Based on these results, we consider the confidence level of earthquake occurrence - tidal period accordance, which we call "earth tide-seismicity compliance parameter p", as an index of tectonic stress criticality for earthquake occurrence and we construct maps of p's over all the area of Greece for each year from 1964 on. It is seen that these maps indicate roughly the seismic active areas. Thus these maps, as well as those of narrower time windows, may be used in earthquake hazard estimation

  10. Geophysical Effects of the Earth's Monthly Motion

    NASA Astrophysics Data System (ADS)

    Sidorenkov, N. S.; Zhigailo, T. S.

    The generation of a lunar tidal force is a major geophysical effect of the Earth's monthly motion.It is shown that synoptic processes vary simultaneously with tidal oscillations of the Earth's rotation rate and weather exhibits changes near their extremes, i.e., when the Earth is in certain positions on its monthly orbit.It is found that the quasi-biennial oscillation of the wind direction in the equatorial stratosphere is a combined oscillation caused by three periodic processes experienced by the atmosphere: (a) lunisolar tides, (b) the precession of the orbit of the Earth's monthly rotation around the barycenter of the Earth-Moon system, and (c) the motion of the perigee of this orbit.Interference of the 1.20-year Chandler wobble with sidereal, anomalistic, and synodic lunar oscillations gives rise to beats, i.e., to slow periodic variations in the wobble amplitude with periods of 32 to 51 years.

  11. The use of the Earth tide-seismicity compliance parameter maps for earthquake risk mitigation

    NASA Astrophysics Data System (ADS)

    Contadakis, Michae lE.; Arabelos, Demetrios N.; Vergos, George; Spatala, pyrousS

    2016-04-01

    Applying the Hi(stogram)Cum(ulation) method, which was introduced recently by Cadicheanu, van Ruymbecke and Zhu (2007), we analyze the series of the earthquakes occurred in the last 50 years in seismic active areas of Greece, i.e. the areas (a) of the Mygdonian Basin(Contadakis et al. 2007), (b) of the Ionian Islands (Contadakis et al. 2012) and (c) of the Hellenic Arc (Vergos et al. 2015) . The result of the analysis for all the areas indicate that the monthly variation of the earthquake frequency is in accordance with the period of the tidal lunar monthly and semi-monthly (Mm and Mf) variations and the same happens with the corresponding daily variations of the frequencies of earthquake occurrence with the diurnal luni-solar (K1) and semidiurnal lunar (M2) tidal variations. In addition the confidence level for the identification of such period accordance between earthquakes occurrence and tidal periods varies with seismic activity, i.e. the higher confidence level corresponds to time periods with stronger seismic activity. These results are in favor of a tidal triggering process on earthquakes when the stress in the focal area is near the critical level. Based on these results, we consider the confidence level of earthquake occurrence - tidal period accordance,wich we call 'earth tide-seismicity compliance parameter p", as an index of tectonic stress criticality for earthquake occurrence and we construct maps of p's over all the area of Greece for each year from 1964 on. It is seen that these maps indicate roughly the seismic active areas. Thus these maps, as well as those of narrower time windows, may be used in earthquake hazard estimation. References: Cadicheanu, N., van Ruymbeke, M andZhu P.,2007:Tidal triggering evidence of intermediate depth earthquakes in Vrancea zone(Romania), NHESS 7,733-740. Contadakis, M. E., Arabelos, D. N., Spatalas, S., 2009, Evidence for tidal triggering on the shallow earthquakes of the seismic area of Mygdonia basin, North Greece

  12. The pole tide in deep oceans

    NASA Technical Reports Server (NTRS)

    Dickman, S. R.

    1990-01-01

    The fluid-dynamical theory of the pole tide is examined by describing the oceanic response to the Chandler wobble and assessing its implications for mantle anelasticity and low-frequency ocean dynamics. The Laplace tide equations accounting for bottom friction are given, and a spherical harmonic approach is delineated in which the time-independent portion of the tide height is expanded. Pole-tide height and related inertia products are linearly proportional to wobble amplitude, and the final equations are modified to account for mantle elasticity and oceanic loading. Results for pole tide effects are given for various earth models with attention to the role of boundary constraints. A dynamic effect is identified which lengthens the Chandler period by about 1 day more than static lengthening, a contribution that suggests a vigorous low-frequency response. The values derived are shown to agree with previous models that do not incorporate the effects of the pole tide.

  13. New aspects of the equilibrium pole tide

    NASA Technical Reports Server (NTRS)

    Dickman, S. R.; Steinberg, D. J.

    1986-01-01

    A new spherical harmonic algorithm is developed for the calculation of the loading and self-gravitating equilibrium pole tide. Based on a suggestion of Dahlen (1976), this approach minimizes the distortions in tide height caused by an incomplete representation of the ocean function. With slight modification this approach easily could be used to compute self-gravitating and loading lunisolar tides as well. Using the algorithm, the static pole tide is compared with tide observations at a variety of locations around the world, and statistically significant evidence for pole tide enhancements is found in midocean as well as the shallow seas. Also included is a reinvestigation of the effect of the static tide on the Chandler-wobble period. The difference between the wobble period of an oceanless elastic earth with a fluid core (Smith and Dahlen, 1981) and the period of an earth minus static oceans yields a 7.4-day discrepancy. It is concluded from tide observations that much of the discrepancy can probably be accounted for by nonequilibrium pole-tide behavior in the deep oceans.

  14. Quartz tube extensometer for observation of Earth tides and local tectonic deformations at the Sopronbanfalva Geodynamic Observatory, Hungary

    SciTech Connect

    Mentes, Gy.

    2010-07-15

    In May 1990, a quartz tube extensometer was installed in the Sopronbanfalva Geodynamic Observatory of the Geodetic and Geophysical Research Institute (GGRI) of the Hungarian Academy of Sciences for recording Earth tides and recent tectonic movements. The paper describes the construction of the extensometer and a portable calibrator used for the in situ calibration of the instrument. The extensometer is very sensitive. Its scale factor is 2.093{+-}0.032 nm/mV according to the highly precise calibration method developed at the GGRI. Since the stability of extensometers is strongly influenced by the geological structure and properties of the rocks in the vicinity of the recording site, the observatory instrument system was tested by coherence analysis between theoretical (as the input signal) and measured tidal data series (as the output signal). In the semidiurnal tidal frequency band the coherence is better than 0.95, while in the diurnal band it is about 0.8. Probably this is due to the fact that the noise is higher in the diurnal band (0.4-0.5 nstr) than in the semidiurnal band (0.19-0.22 nstr). Coherence analysis between theoretical and measured data corrected for barometric changes yielded a small improvement of coherence in both frequency bands, while using temperature data correction, no observable improvement was obtained. Results of the tidal analysis also show that the observatory instrument system is suitable for recording very small tectonic movements. The 18 years of continuous data series measured by the extensometer prove the high quality of the extensometer. On the basis of investigations, it was pointed out that further efforts should be done to improve the barometric correction method and that correction for ocean load, as well as considering topographic and cavity effects are necessary to increase the accuracy of determining tidal parameters.

  15. Perigean Spring Tides and Apogean Neap Tides in History

    NASA Astrophysics Data System (ADS)

    Olson, Donald W.

    2012-01-01

    On January 4, 1912 - almost exactly 100 years ago - both a full Moon and a lunar perigee occurred, with these two events separated by only a few minutes of time and with the Earth near perihelion. The resulting lunar distance (356,375 km) on that date stands as the closest approach of the Moon to the Earth in an interval of more than 1400 years. The centennial of this extreme lunar perigee is an appropriate time to consider the effect of lunar distance on the range of ocean tides. At most ocean ports, spring tides of increased range occur near new and full Moon. If a lunar perigee falls near new or full Moon, then perigean spring tides of even greater range are possible. Conversely, if a lunar apogee falls near first quarter or last quarter Moon, then apogean neap tides of unusually reduced range can occur. Examples of perigean spring tides include a near-coincidence of lunar perigee and new Moon in December 1340 that may be related to a plot device in Chaucer's "The Franklin's Tale,” a Canterbury tale that describes an extreme high tide covering the rocks on the coast of Brittany in "the cold and frosty season of December.” Another example, the disaster known as the Bristol Channel Flood, occurred shortly after a lunar perigee and new Moon in January 1607. A German U-boat employed an exceptionally high perigean spring tide shortly after the new Moon of October 1939 to enter Scapa Flow by an unexpected route and sink the HMS Royal Oak. An apogean neap tide prevailed during the amphibious assault of the U. S. Marines at Tarawa in November 1943, making the eventual victory more costly because the landing craft were unable to reach the island and instead grounded on the surrounding reef.

  16. Dynamical tides in general relativity: Effective action and effective-one-body Hamiltonian

    NASA Astrophysics Data System (ADS)

    Steinhoff, Jan; Hinderer, Tanja; Buonanno, Alessandra; Taracchini, Andrea

    2016-11-01

    Tidal effects have an important impact on the late inspiral of compact binary systems containing neutron stars. Most current models of tidal deformations of neutron stars assume that the tidal bulge is directly related to the tidal field generated by the companion, with a constant response coefficient. However, if the orbital motion approaches a resonance with one of the internal modes of the neutron star, this adiabatic description of tidal effects starts to break down, and the tides become dynamical. In this paper, we consider dynamical tides in general relativity due to the quadrupolar fundamental oscillation mode of a neutron star. We devise a description of the effects of the neutron star's finite size on the orbital dynamics based on an effective point-particle action augmented by dynamical quadrupolar degrees of freedom. We analyze the post-Newtonian and test-particle approximations of this model and incorporate the results into an effective-one-body Hamiltonian. This enables us to extend the description of dynamical tides over the entire inspiral. We demonstrate that dynamical tides give a significant enhancement of matter effects compared to adiabatic tides, at least for neutron stars with large radii and for low mass-ratio systems, and should therefore be included in accurate models for gravitational-wave data analysis.

  17. Tide generator

    SciTech Connect

    Feltenberger, B.D.

    1981-06-16

    A tidewater power system consisting of a high tide reservoir and a low tide reservoir. The high tide reservoir has an inlet adapted to be supported at high tide level and an outlet with a water wheel and generator between the outlet of the high tide reservoir and the low tide reservoir. The low tide reservoir has an outlet at the low tide level. The outlet from the high tide reservoir is adjustable to control the flow rate and the high tide reservoir can be closed at high tide to retain water for use over a period of time.

  18. Analysis of star pair latitudes. [earth tides tesseral harmonics, and polar wandering

    NASA Technical Reports Server (NTRS)

    Graber, M. A.

    1978-01-01

    Star pair latitude observations forming the basis for the pole positions reported by the International Polar Motion Service (IPMS) are processed to produce a mean pole position. However, the time series of raw observations contains high frequency information which is lost in the calculation of the mean pole. Analysis of 2931 star pair observations reveals a possible large excitation at one cycle per solar day. The average power level in the frequency band of the tesseral tides is seen to be high, although the peaks do not occur at the expected tidal frequencies.

  19. Possible effect of solar tides on radon signals.

    PubMed

    Steinitz, G; Piatibratova, O; Kotlarsky, P

    2011-08-01

    Large temporal variations of radon ((222)Rn) are often encountered in air in the geologic environment, at time scales from diurnal to annual. Interpretations as to the nature of these variations, unique to (222)Rn, often invoke either above surface atmospheric variations, or the influence of subtle active geodynamic processes. So far the eventual geophysical drivers of the variation of (222)Rn as well as its specific qualities enabling this temporal variation are not known. New insight on the temporal variation of (222)Rn is gained by experimental simulation in confined air. Two short laboratory experiments, and one external experiment lasting over 3 years, were performed inside closed canisters and using natural and commercial (222)Rn sources. Internal and external gamma and alpha detectors recorded variations of the radiation, up to around 20% of the equilibrium level. Radon signals of different time scale occurred with: a) periodic annual and semi-annual signals; b) non-periodic multi-day signals; c) periodic daily signals. Similar, related, inversely-related and dissimilar temporal patterns were manifested in the measured time series of the different sensors. Diurnal periodicity was dominated by the solar tide components S1, S2 and S3, exhibiting unlike relative amplitudes and different phases at the different sensors. A compound association occurs among the amplitudes and phases of the diurnal and seasonal periodicities of the daily (222)Rn signal, linking the periodic phenomena to the rotation of earth around its axis and around the sun. (222)Rn variation patterns in the frequency-time domain cannot be driven by the corresponding atmospheric variation patterns. These results, obtained under static and isolated conditions, are in disagreement with the expected radioactive equilibrium and its spatially uniform expression within and around the experimental volume. The external influence which drives the daily signals evolving from (222)Rn inside the canister is

  20. The IERS Special Bureau for Tides

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.; Chao, B. F.; Desai, S. D.

    2002-01-01

    The Global Geophysical Fluids Center of the International Earth Rotation Service (IERS) comprises 8 special bureaus, one of which is the Special Bureau for Tides. Its purpose is to facilitate studies related to tidal effects in earth rotation. To that end it collects various relevant datasets and distributes them, primarily through its website at bowie.gsfc.nasa.gov/ggfc/tides. Example datasets include tabulations of tidal variations in angular momentum and in earth rotation as estimated from numerical ocean tide models and from meteorological reanalysis products. The web site also features an interactive tidal prediction "machine" which generates tidal predictions (e.g., of UT1) from lists of harmonic constants. The Special Bureau relies on the tidal and earth-rotation communities to build and enlarge its datasets; further contributions from this community are most welcome.

  1. Effects of Ocean Tide Models on Gnss-Estimated Ztd and Pwv in Turkey

    NASA Astrophysics Data System (ADS)

    Gurbuz, G.; Jin, S.; Mekik, C.

    2015-12-01

    Global Navigation Satellite System (GNSS) observations can precisely estimate the total zenith tropospheric delay (ZTD) and precipitable water vapour (PWV) for weather prediction and atmospheric research as a continuous and all-weather technique. However, apart from GNSS technique itself, estimations of ZTD and PWV are subject to effects of geophysical models with large uncertainties, particularly imprecise ocean tide models in Turkey. In this paper, GNSS data from Jan. 1st to Dec. 31st of 2014 are processed at 4 co-located GNSS stations (GISM, DIYB, GANM, and ADAN) with radiosonde from Turkish Met-Office along with several nearby IGS stations. The GAMIT/GLOBK software has been used to process GNSS data of 30-second sample using the Vienna Mapping Function and 10° elevation cut-off angle. Also tidal and non-tidal atmospheric pressure loadings (ATML) at the observation level are also applied in GAMIT/GLOBK. Several widely used ocean tide models are used to evaluate their effects on GNSS-estimated ZTD and PWV estimation, such as IERS recommended FES2004, NAO99b from a barotropic hydrodynamic model, CSR4.0 obtained from TOPEX/Poseidon altimetry with the model FES94.1 as the reference model and GOT00 which is again long wavelength adjustments of FES94.1 using TOPEX/Poseidon data at 0.5 by 0.5 degree grid. The ZTD and PWV computed from radiosonde profile observations are regarded as reference values for the comparison and validation. In the processing phase, five different strategies are taken without ocean tide model and with four aforementioned ocean tide models, respectively, which are used to evaluate ocean tide models effects on GNSS-estimated ZTD and PWV estimation through comparing with co-located Radiosonde. Results showed that ocean tide models have greatly affected the estimation of the ZTD in centimeter level and thus the precipitable water vapour in millimeter level, respectively at stations near coasts. The ocean tide model FES2004 that is the product of

  2. Literature Review of Florida Red Tide: Implications for Human Health Effects

    PubMed Central

    Kirkpatrick, Barbara; Fleming, Lora E.; Squicciarini, Dominick; Backer, Lorrie C.; Clark, Richard; Abraham, William; Benson, Janet; Cheng, Yung Sung; Johnson, David; Pierce, Richard; Zaias, Julia; Bossart, Gregory D.; Baden, Daniel G.

    2010-01-01

    Florida red tides are a natural phenomenon caused by dense aggregations of single cell or several species of unicellular organisms. Patches of discolored water, dead or dying fish, and respiratory irritants in the air often characterize these algal blooms. In humans, two distinct clinical entities, depending on the route of exposure, are associated with exposure to the Florida red tide toxins (particularly the brevetoxins). With the ingestion of brevetoxin-contaminated shellfish, neurotoxic shellfish poisoning (NSP) presents as a milder gastroenteritis with neurologic symptoms compared with other marine toxin diseases such as paralytic shellfish poisoning (PSP) or ciguatera fish poisoning. With the inhalation of the aerosolized red tide toxins (especially the brevetoxins) from the sea spray, respiratory irritation and possibly other health effects are reported in both humans and other mammals (Baden 1995, Fleming 1998a, Fleming 1998b, Fleming 1999a, Bossart 1998, Asai 1982, Eastaugh 1989, Pierce 1986, Music 1973, Temple 1995, Anderson 1994). This paper reviews the literature on the known and possible human health effects of exposure to the Florida red tides and their toxins. The review includes discussion of the red tide organisms and their toxins, as well as the effects of these toxins on both wild and laboratory animals as they relate to possible human health effects and exposures. PMID:20411030

  3. Modeling the effect of tides and waves on benthic biofilms

    NASA Astrophysics Data System (ADS)

    Mariotti, G.; Fagherazzi, S.

    2012-12-01

    We propose a simple model for growth of benthic biofilm subject to variable hydrodynamic disturbances and with a biofilm-dependent erodibility (biostabilization). Model results show that, for disturbances with equal intensity, the biofilm is eroded or not depending on its current biomass, which is a function of the past evolution trajectory. Because of the finite time needed for a biofilm to develop, both the intensity and frequency of periodical disturbances, such as tidal currents, determine whether the biofilm can approach its equilibrium biomass. Spring-neap tidal modulation favors biofilm development, since the reduction of the current shear stress associated with neap tides allows biofilm growth, thus increasing biostabilization and the biofilm's likelihood to withstand the subsequent energetic spring tides. On the other hand, diurnal tidal modulations are negative for biofilm development, because the diel biofilm growth is almost negligible. Under stochastic disturbances associated with wind waves, there are two most-likely states for the biofilm biomass: either close to zero or close to the equilibrium value, depending on wave intensity. If biostabilization is reduced or eliminated, the probability of intermediate values for biofilm biomass becomes also significant. The role of biostabilization is hence to exacerbate the probability of the end-member states. Finally, because of the nonmonotonic relationship between water depth and wave induced bed stresses, only extremely shallow and deep areas favor biofilm persistence. If light attenuation with depth is considered, deep water becomes unsuitable for biofilm growth when water turbidity is high.

  4. High tides and rising seas: potential effects on estuarine waterbirds

    USGS Publications Warehouse

    Erwin, R.M.; Sanders, G.M.; Prosser, D.J.; Cahoon, D.R.; Greenberg, Russell; Maldonado, Jesus; Droege, Sam; McDonald, M.V.

    2006-01-01

    Coastal waterbirds are vulnerable to water-level changes especially under predictions of accelerating sea-level rise and increased storm frequency in the next century. Tidal and wind-driven fluctuations in water levels affecting marshes, their invertebrate communities, and their dependent waterbirds are manifested in daily, monthly, seasonal, annual, and supra-annual (e.g., decadal or 18.6-yr) periodicities. Superimposed on these cyclic patterns is a long-term (50?80 yr) increase in relative sea-level rise that varies from about 2?4 + mm/yr along the Atlantic coastline. At five study sites selected on marsh islands from Cape Cod, Massachusetts to coastal Virginia, we monitored marsh elevation changes and flooding, tide variations over time, and waterbird use. We found from longterm marsh core data that marsh elevations at three of five sites may not be sufficient to maintain pace with current sea-level rise. Results of the short-term (3?4 yr) measures using surface elevation tables suggest a more dramatic difference, with marsh elevation change at four of five sites falling below relative sea-level rise. In addition, we have found a significant increase (in three of four cases) in the rate of surface marsh flooding in New Jersey and Virginia over the past 70?80 yr during May?July when waterbirds are nesting on or near the marsh surface. Short-term, immediate effects of flooding will jeopardize annual fecundity of many species of concern to federal and state agencies, most notably American Black Duck (Anas rubripes), Nelson?s Sharp-tailed Sparrow (Ammodramus nelsoni), Saltmarsh Sharp-tailed Sparrow (A. caudacutus), Seaside Sparrow (A. maritima), Coastal Plain Swamp Sparrow (Melospiza georgiana nigrescens), Black Rail (Laterallus jamaicensis), Forster?s Tern (Sterna forsteri), Gull-billed Tern (S. nilotica), Black Skimmer (Rynchops niger), and American Oystercatcher (Haemotopus palliatus). Forster?s Terns are probably most at risk given the large proportion of their

  5. Late proterozoic and paleozoic tides, retreat of the moon, and rotation of the earth

    USGS Publications Warehouse

    Sonett, C.P.; Kvale, E.P.; Zakharian, A.; Chan, M.A.; Demko, T.M.

    1996-01-01

    The tidal rhythmites in the Proterozoic Big Cottonwood Formation (Utah, United States), the Neoproterozoic Elatina Formation of the Flinders Range (southern Australia), and the Lower Pennsylvanian Pottsville Formation (Alabama, United States) and Mansfield Formation (Indiana, United States) indicate that the rate of retreat of the lunar orbit is d??/dt k2 sin(2??) (where ?? is the Earth-moon radius vector, k2 is the tidal Love number, and ?? is the tidal lag angle) and that this rate has been approximately constant since the late Precambrian. When the contribution to tidal friction from the sun is taken into account, these data imply that the length of the terrestrial day 900 million years ago was -18 hours.

  6. Earth-tide-induced fluctuations in the salinity of an inland river, New South Wales, Australia: a short-term study.

    PubMed

    Jasonsmith, J F; Macdonald, B C T; White, I

    2017-04-01

    Wybong Creek discharges salts into the agriculturally and industrially important Hunter River in New South Wales, Australia. Abrupt increases in salinity occur periodically in the mid-Wybong Creek catchment. In order to understand the processes which cause these abrupt increases, changes in surface and groundwater were investigated. It is shown that salinity increases can be attributed to highly discrete groundwater discharge directly into the river from below. Hourly electrical conductivity data measured in the river showed regular, diurnal electrical conductivity fluctuations of up to 350 μS cm(-1). These fluctuations could not be attributed to barometric pressure, temperature, or evapotranspiration. Instead, a similar periodicity in surface water electrical conductivity and groundwater height in nearby groundwater wells was found. Fluctuations were of similar periodicity to the orthotides which cause fluctuations in surface water height and are induced by Earth tides. The geology in the mid-catchment area indicates conditions are optimal for Earth tides to impact groundwater. The reporting of orthotidal changes in water chemistry in this article is believed to be the first of its kind in the scientific literature, with the large fluctuations noted having important implications for water monitoring and management in the catchment. Further research investigating Earth-tide-induced phases of groundwater heights will better constrain the relationships between surface water chemistry and groundwater height.

  7. Monthly and Fortnightly Tidal Variations of the Earth's Rotation Rate Predicted by a TOPEX/POSEIDON Empirical Ocean Tide Model

    NASA Technical Reports Server (NTRS)

    Desai, S.; Wahr, J.

    1998-01-01

    Empirical models of the two largest constituents of the long-period ocean tides, the monthly and the fortnightly constituents, are estimated from repeat cycles 10 to 210 of the TOPEX/POSEIDON (T/P) mission.

  8. A long-term stable equilibrium for synchronous binaries including tides and the byorp effect

    NASA Astrophysics Data System (ADS)

    Jacobson, Seth A.; Scheeres, D. J.

    2011-04-01

    We present theoretical evidence for the existence of a long-term stable equilibrium solution for synchronous binary asteroids accounting for mutual body tides, the binary YORP (BYORP) effect and dynamics. Synchronous binary asteroid systems consist of a rapidly spinning primary and a tidally-locked secondary, analogous to the Earth-Moon system. Tidal evolution of these systems leads to growth in the semi-major axis. Evolution from the BYORP effect can lead to both contraction and growth of the semi-major axis. There are two scenarios for joint evolution of a synchronous binary when both effects are considered: expansive and opposing evolution. During joint expansive evolution, both effects grow the semi-major axis. The system will either grow to the Hill sphere and disrupt if tidally dominated, or the mutual orbit will be de-stabilized due to runaway eccentricity growth if BYORP dominated. During joint opposing evolution, tidal and BYORP evolution act to evolve the system to a stable equilibrium. The location of this equilibrium to first order depends on just the tidal parameters, specific tidal dissipation number Q and the tidal Love number k, as well as the BYORP shape coefficient. If the observed population of small (0.1 - 10 km diameter), synchronous binaries are assumed to be in this static configuration, then our analysis shows that a monolithic geophysical model is not satisfactory, whereas the ``rubble pile'' model proposed by Goldreich & Sari (2009) is sufficient to prevent runaway eccentricity growth. The existence of this equilibrium and a secondary shape model built from observations enables direct study of asteroid geophysics through tidal theory. The existence of this equilibrium would be confirmed by a lack of migration in observational tests for the BYORP effect. Goldreich, P. & R. Sari, ApJ, 691:54-60 (2009)

  9. Effect of tides and source location on nearshore tsunami-induced currents

    NASA Astrophysics Data System (ADS)

    Ayca, Aykut; Lynett, Patrick J.

    2016-12-01

    Here we present the results of a numerical modeling study that investigates how event-maximum tsunami-induced currents vary due to the dynamic effects of tides and wave directivity. First, analyses of tide-tsunami interaction are presented in three harbors by coupling the tsunami with the tide, and allowing the initial tsunami wave to arrive at various tidal phases. We find that tsunami-tide interaction can change the event-maximum current speed experienced in a harbor by up to 25% for the events and harbors studied, and we note that this effect is highly site-specific. Second, to evaluate the effect of wave directionality on event-maximum currents, earthquakes sources were placed throughout the Pacific, with magnitudes tuned to create the same maximum near-coast amplitude at the harbor of study. Our analysis also shows that, for the harbor and sources examined, the effect of offshore directionality and tsunami frequency content has a weak effect on the event-maximum currents experienced in the harbor. The more important dependency of event-maximum currents is the near-harbor amplitude of the wave, indicating that event-maximum currents in a harbor from a tsunami generated by a large far-field earthquake may be reasonably well predicted with only information about the predicted local maximum tsunami amplitude. This study was motivated by the hope of constructing a basis for understanding the dynamic effects of tides and wave directivity on current-based tsunami hazards in a coastal zone. The consideration of these aspects is crucial and yet challenging in the modeling of tsunami currents.

  10. Weight, gravitation, inertia, and tides

    NASA Astrophysics Data System (ADS)

    Pujol, Olivier; Lagoute, Christophe; Pérez, José-Philippe

    2015-11-01

    This paper deals with the factors that influence the weight of an object near the Earth's surface. They are: (1) the Earth's gravitational force, (2) the centrifugal force due to the Earth's diurnal rotation, and (3) tidal forces due to the gravitational field of the Moon and Sun, and other solar system bodies to a lesser extent. Each of these three contributions is discussed and expressions are derived. The relationship between weight and gravitation is thus established in a direct and pedagogical manner readily understandable by undergraduate students. The analysis applies to the Newtonian limit of gravitation. The derivation is based on an experimental (or operational) definition of weight, and it is shown that it coincides with the Earth’s gravitational force modified by diurnal rotation around a polar axis and non-uniformity of external gravitational bodies (tidal term). Two examples illustrate and quantify these modifications, respectively the Eötvös effect and the oceanic tides; tidal forces due to differential gravitation on a spacecraft and an asteroid are also proposed as examples. Considerations about inertia are also given and some comments are made about a widespread, yet confusing, explanation of tides based on a centrifugal force. Finally, the expression of the potential energy of the tide-generating force is established rigorously in the appendix.

  11. The effect of changing topography on coastal tides and storm surge: a historical perspective

    NASA Astrophysics Data System (ADS)

    Talke, Stefan; Jay, David; Helaire, Lumas; Familkhalili, Ramin

    2016-11-01

    Over decadal and century time scales, the topography of coastal harbors changes due to natural and anthropogenic factors. These changes alter the mass and momentum balances of incoming waves, producing measureable changes to tides and surge. Here we use recently recovered archival data, historic bathymetric charts, and numerical models to assess changes in multiple estuaries. In the Columbia River estuary, Ems estuary, and Cape Fear Estuary, channel deepening has increased the M2 tide between 10 to 100% since the 19th century, due to both reduced frictional effects and altered resonance. The bathymetric perturbations also affect the propagation of other long-period waves: in Wilmington (NC), the worst-case scenario CAT-5 storm surge is modeled to increase by 50% since 19th century conditions. Similarly, in New York harbor, the 10 year storm-tide level has outpaced sea-level rise by nearly 30 cm since 1850. In the Columbia River, reduced friction has decreased the river slope (reducing water levels), but also led to amplification of both tides and flood waves. Going forward, historical bathymetric change may provide a clue to the future effects of climate change and continued anthropogenic development. National Science Foundation; US Army Corp of Engineers.

  12. Initial Evaluation of the Effects of Aerosolized Florida Red Tide Toxins (Brevetoxins) in Persons with Asthma

    PubMed Central

    Fleming, Lora E.; Kirkpatrick, Barbara; Backer, Lorraine C.; Bean, Judy A.; Wanner, Adam; Dalpra, Dana; Tamer, Robert; Zaias, Julia; Cheng, Yung Sung; Pierce, Richard; Naar, Jerome; Abraham, William; Clark, Richard; Zhou, Yue; Henry, Michael S.; Johnson, David; Van De Bogart, Gayl; Bossart, Gregory D.; Harrington, Mark; Baden, Daniel G.

    2005-01-01

    Florida red tides annually occur in the Gulf of Mexico, resulting from blooms of the marine dinoflagellate Karenia brevis. K. brevis produces highly potent natural polyether toxins, known as brevetoxins, that activate voltage-sensitive sodium channels. In experimental animals, brevetoxins cause significant bronchoconstriction. A study of persons who visited the beach recreationally found a significant increase in self-reported respiratory symptoms after exposure to aerosolized Florida red tides. Anecdotal reports indicate that persons with underlying respiratory diseases may be particularly susceptible to adverse health effects from these aerosolized toxins. Fifty-nine persons with physician-diagnosed asthma were evaluated for 1 hr before and after going to the beach on days with and without Florida red tide. Study participants were evaluated with a brief symptom questionnaire, nose and throat swabs, and spirometry approved by the National Institute for Occupational Safety and Health. Environmental monitoring, water and air sampling (i.e., K. brevis, brevetoxins, and particulate size distribution), and personal monitoring (for toxins) were performed. Brevetoxin concentrations were measured by liquid chromatography mass spectrometry, high-performance liquid chromatography, and a newly developed brevetoxin enzyme-linked immunosorbent assay. Participants were significantly more likely to report respiratory symptoms after Florida red tide exposure. Participants demonstrated small but statistically significant decreases in forced expiratory volume in 1 sec, forced expiratory flow between 25 and 75%, and peak expiratory flow after exposure, particularly those regularly using asthma medications. Similar evaluation during nonexposure periods did not significantly differ. This is the first study to show objectively measurable adverse health effects from exposure to aerosolized Florida red tide toxins in persons with asthma. Future studies will examine the possible chronic

  13. Effects of tide cycles on habitat selection and habitat partitioning by migrating shorebirds

    USGS Publications Warehouse

    Burger, J.; Howe, M.A.; Hahn, D.C.; Chase, J.

    1977-01-01

    We studied assemblages of feeding shorebirds in three intertidal habitats on the coast of New Jersey during August to document how species segregates patially both among and within habitats and to determine the effects of tidal cycles on these patterns. The habitats were a sandy beach facing the ocean proper (outer beach), a sandy beach on the mainland side of a barrier island (inner beach), and a small mudflat adjacent to a Spartina alternifiora salt marsh. We were able to identify several microhabitats on the outer beach and mudflat. Most speciesfe d in more than one habitat, but only two, Charadrius semipalmatus and Calidris canutus, used all three habitats regularly. Within habitats, most species exhibited strong preferences for the wettest areas, but we found differences among species in degrees of preference. The least amount of partitioning occurred on the inner beach, where birds crowded into a small zone near the water's edge and had frequent agonistic encounters suggesting intense competition. Shorebird feeding activity was partly a function of tide time: each habitat had a characteristic temporal pattern of use by shorebirds related to tide time rather than diel time; within habitats, we found species-characteristic feeding activity rhythms that were also a function of tide time. Feeding by most species peaked during the first 2 hours after low tide on the outer beach and mudflat. The results are discussed in terms of feeding strategies and interspecific competition.

  14. Quantifying the Effects of Combined Waves and Tides on Deltas: An Experimental Study

    NASA Astrophysics Data System (ADS)

    Paola, C.; Baumgardner, S. E.

    2015-12-01

    The classical Galloway diagram captures qualitatively the dramatic effect waves and tides have on reshaping river deltas. Here we investigate these controls in a series of laboratory experiments in which the relative energetics of river, wave, and tidal forcing could be controlled and systematically varied. The delta is fed from a single source of water and low-density, sand-size sediment in one corner of a 5m x 5m basin. Experimental tides are produced by transferring water back and forth between the main experimental basin and an auxiliary holding basin. The tidal period is 60 s and a typical tidal range is 30 mm. Waves are produced using a floating, oscillating paddle placed opposite the sediment feed location. They typically have a period of 1 s and an amplitude of 10 mm. The total energy flux associated with waves and tides is controlled by varying the temporal intermittency of each process, while river energy and sediment fluxes are held steady. The experiments show a variation in delta morphology as a function of wave and tidal forcing that parallels that observed in the field: increasing wave strength redistributes sediment and flattens the shoreline; increasing tidal strength creates well defined tidal channels as well as inlets through the wave-worked shoreline. Both waves and tides reduce the mobility of the main fluvial channel. Quantitative morphologic measures of these effects vary systematically as a function of dimensionless relative wave and tidal strength. The image below shows typical experimental delta morphology associated with mixed wave-tide forcing.

  15. Tides and Decadal Variability

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.

    2003-01-01

    This paper reviews the mechanisms by which oceanic tides and decadal variability in the oceans are connected. We distinguish between variability caused by tides and variability observed in the tides themselves. Both effects have been detected at some level. The most obvious connection with decadal timescales is through the 18.6-year precession of the moon's orbit plane. This precession gives rise to a small tide of the same period and to 18.6-year modulations in the phase and amplitudes of short-period tides. The 18.6-year "node tide" is very small, no more than 2 cm anywhere, and in sea level data it is dominated by the ocean's natural Variability. Some authors have naively attributed climate variations with periods near 19 years directly to the node tide, but the amplitude of the tide is too small for this mechanism to be operative. The more likely explanation (Loder and Garrett, JGR, 83, 1967-70, 1978) is that the 18.6-y modulations in short-period tides, especially h e principal tide M2, cause variations in ocean mixing, which is then observed in temperature and other climatic indicators. Tidally forced variability has also been proposed by some authors, either in response to occasional (and highly predictable) tidal extremes or as a nonlinear low-frequency oscillation caused by interactions between short-period tides. The former mechanism can produce only short-duration events hardly more significant than normal tidal ranges, but the latter mechanism can in principle induce low-frequency oscillations. The most recent proposal of this type is by Keeling and Whorf, who highlight the 1800-year spectral peak discovered by Bond et al. (1997). But the proposal appears contrived and should be considered, in the words of Munk et al. (2002), "as the most likely among unlikely candidates."

  16. Understanding Earth's Albedo Effect

    ERIC Educational Resources Information Center

    Fidler, Chuck

    2012-01-01

    Earth and space science in the middle school classroom are composed of intricately intertwined sets of conceptual systems (AAAS 1993; NRC 1996). Some systems of study, such as the water and rock cycles, are quite explicit and often found as stand-alone middle school science units. Other phenomena are not so apparent, yet they play an extremely…

  17. Quartz tube extensometer for observation of Earth tides and local tectonic deformations at the Sopronbánfalva Geodynamic Observatory, Hungary.

    PubMed

    Mentes, Gy

    2010-07-01

    In May 1990, a quartz tube extensometer was installed in the Sopronbánfalva Geodynamic Observatory of the Geodetic and Geophysical Research Institute (GGRI) of the Hungarian Academy of Sciences for recording Earth tides and recent tectonic movements. The paper describes the construction of the extensometer and a portable calibrator used for the in situ calibration of the instrument. The extensometer is very sensitive. Its scale factor is 2.093+/-0.032 nm/mV according to the highly precise calibration method developed at the GGRI. Since the stability of extensometers is strongly influenced by the geological structure and properties of the rocks in the vicinity of the recording site, the observatory instrument system was tested by coherence analysis between theoretical (as the input signal) and measured tidal data series (as the output signal). In the semidiurnal tidal frequency band the coherence is better than 0.95, while in the diurnal band it is about 0.8. Probably this is due to the fact that the noise is higher in the diurnal band (0.4-0.5 nstr) than in the semidiurnal band (0.19-0.22 nstr). Coherence analysis between theoretical and measured data corrected for barometric changes yielded a small improvement of coherence in both frequency bands, while using temperature data correction, no observable improvement was obtained. Results of the tidal analysis also show that the observatory instrument system is suitable for recording very small tectonic movements. The 18 years of continuous data series measured by the extensometer prove the high quality of the extensometer. On the basis of investigations, it was pointed out that further efforts should be done to improve the barometric correction method and that correction for ocean load, as well as considering topographic and cavity effects are necessary to increase the accuracy of determining tidal parameters.

  18. Effects of tides on Riverine and Glacial freshwater transport in the Arctic Ocean.

    NASA Astrophysics Data System (ADS)

    Luneva, Maria; Aksenov, Yevgeny; Harle, James; Holt, Jason

    2016-04-01

    In this study we use a novel pan-Arctic sea NENO-shelf ice-ocean coupled model, to examine the effects of tides, river runoff and vertical mixing schemes on sea ice and the mixing of water masses. Several 20-year long (1990-2010) simulations were performed: with explicitly resolved tides and without any tidal dynamics, with climatology river runoff, Dai et al. ,2009 database and freshwater source from melting Greenland glaciers. We examine also three different turbulent closures structural functions, based on the k-epsilon version of the Generic Length Scale Model: by Canuto group (2001) and two by Kantha and Clayson (1994, 2004). The results have been compared with sea ice volume and concentration trends and temperature and salinity profiles from World Ocean Database . We compared the following characteristics: potential energy anomalies, depth of halocline, mixed layer depth , salinity at the subsurface layer.

  19. A UNIFIED THEORY FOR THE EFFECTS OF STELLAR PERTURBATIONS AND GALACTIC TIDES ON OORT CLOUD COMETS

    SciTech Connect

    Collins, Benjamin F.; Sari, Re'em

    2010-11-15

    We examine the effects of passing field stars on the angular momentum of a nearly radial orbit of an Oort cloud comet bound to the Sun. We derive the probability density function of the change in angular momentum from one stellar encounter, assuming a uniform and isotropic field of perturbers. We show that the total angular momentum follows a Levy flight, and determine its distribution function. If there is an asymmetry in the directional distribution of perturber velocities, the marginal probability distribution of each component of the angular momentum vector can be different. The constant torque attributed to Galactic tides arises from a non-cancellation of perturbations with an impact parameter of order the semimajor axis of the comet. When the close encounters are rare, the angular momentum is best modeled by the stochastic growth of stellar encounters. If trajectories passing between the comet and the Sun occur frequently, the angular momentum exhibits the coherent growth attributed to the Galactic tides.

  20. Variation of the Earth tide-seismicity compliance parameter the last 50 years for the seismic area of Evoikos, Greece

    NASA Astrophysics Data System (ADS)

    Contadakis, Michael E.; Arabelos, Demetrious N.; Vergos, George; Spatalas, Spyrous

    2015-04-01

    seismic area of Mygdonia basin, North Greece, in Terrestrial and Stellar Environment, eds.D. Arabelos, M.E.Contadakis, C.Kaltsikis, I.Tziavos,Ziti Press Thessaloniki,Greece,pp 223-235 Contadakis, M. E.,Arabelos, D.N., Spatalas, S.D., 2012, Evidence for tidal triggering for the earthquakes of the Ionian geological zone, Greece, Annals of Geophysics, Vol. 55, No. 1, p. 73-81 Vergos, G., Arabelos, D. N., Contadakis, M. E., 2012, Evidence for Tidal triggering on the earthquakes of the Hellenic Arc, Greece., Geoph.Res.Abs, Vol 14,2325 Contadakis, M.E,Arabelos, D.N.,Vergos, G.,Spatalas, S.D.,2014, Variation of the Earth tide-seismicity compliance parameter during the recent seismic activity of Fthiotida, Greece, EGU General Assembly 2014 1121

  1. The Effects of Thermal Tides and Dust on Traveling Waves in the Martian Atmosphere

    NASA Astrophysics Data System (ADS)

    Wang, H.; Toigo, A. D.; Richardson, M. I.

    2014-12-01

    Observations show that traveling waves with zonal wavenumber k = 3 correlate closely with the development of frontal / flushing dust storms which are important in the Martian dust cycle. Previous modeling work suggests that both the polar hood [Barnes et al., 2014] and the cap edge dust storms [Wang et al., 2013] have the potential to enhance these waves. In this presentation, we investigate the case of cap edge dust further, focusing on the following results. We will show that the relative strength of the traveling waves depends not only on the time, geolocation, height and variable under consideration, but also on the analysis method. For near surface temperature which is observable by spacecraft, the spectral and time averaged wave power can lead to a different answer than the monochromatic wave power. In particular, in the presence of cap edge dust, the modeled zonal wavenumber k = 3 can dominate the traveling wave spectra at times. In the presence of cap edge dust in the model, the enhancement of the k = 3 traveling waves is accompanied by pronounced increase of the diurnal tide. To test the effect of thermal tides on traveling waves, we have performed sensitivity runs where the insolation is replaced by the diurnally averaged value. We find that the amplitude of the k = 3 traveling waves are greatly reduced without thermal tides. Detailed analyses of the relationship between the waves will be presented.

  2. Aerosolized Red Tide Toxins (Brevetoxins) and Asthma: Continued health effects after 1 hour beach exposure.

    PubMed

    Kirkpatrick, Barbara; Fleming, Lora E; Bean, Judy A; Nierenberg, Kate; Backer, Lorraine C; Cheng, Yung Sung; Pierce, Richard; Reich, Andrew; Naar, Jerome; Wanner, Adam; Abraham, William M; Zhou, Yue; Hollenbeck, Julie; Baden, Daniel G

    2011-01-01

    Blooms of the toxic dinoflagellate, Karenia brevis, produce potent neurotoxins in marine aerosols. Recent studies have demonstrated acute changes in both symptoms and pulmonary function in asthmatics after only 1 hour of beach exposure to these aerosols. This study investigated if there were latent and/or sustained effects in asthmatics in the days following the initial beach exposure during periods with and without an active Florida red tide.Symptom data and spirometry data were collected before and after 1 hour of beach exposure. Subjects kept daily symptom diaries and measured their peak flow each morning for 5 days following beach exposure. During non-exposure periods, there were no significant changes in symptoms or pulmonary function either acutely or over 5 days of follow-up. After the beach exposure during an active Florida red tide, subjects had elevated mean symptoms which did not return to the pre-exposure baseline for at least 4 days. The peak flow measurements decreased after the initial beach exposure, decreased further within 24 hours, and continued to be suppressed even after 5 days. Asthmatics may continue to have increased symptoms and delayed respiratory function suppression for several days after 1 hour of exposure to the Florida red tide toxin aerosols.

  3. Improving a prediction system for oil spills in the Yellow Sea: effect of tides on subtidal flow.

    PubMed

    Kim, Chang-Sin; Cho, Yang-Ki; Choi, Byoung-Ju; Jung, Kyung Tae; You, Sung Hyup

    2013-03-15

    A multi-nested prediction system for the Yellow Sea using drifter trajectory simulations was developed to predict the movements of an oil spill after the MV Hebei Spirit accident. The speeds of the oil spill trajectories predicted by the model without tidal forcing were substantially faster than the observations; however, predictions taking into account the tides, including both tidal cycle and subtidal periods, were satisfactorily improved. Subtidal flow in the simulation without tides was stronger than in that with tides because of reduced frictional effects. Friction induced by tidal stress decelerated the southward subtidal flows driven by northwesterly winter winds along the Korean coast of the Yellow Sea. These results strongly suggest that in order to produce accurate predictions of oil spill trajectories, simulations must include tidal effects, such as variations within a tidal cycle and advections over longer time scales in tide-dominated areas.

  4. King Tide floods in Tuvalu

    NASA Astrophysics Data System (ADS)

    Lin, C.-C.; Ho, C.-R.; Cheng, Y.-H.

    2013-05-01

    The spatial and temporal distributions of sea level rise present regional floods in some certain areas. The low-lying island countries are obviously the spots affected severely. Tuvalu, an atoll island country located in the south-west Pacific Ocean, is suffering the devastating effects of losing life, property, and intending migration caused by floods. They blame the regional flooding to King Tide, a term used but not clearly identified by Pacific islanders. In this study, we clarify what King Tide is first. By the tide gauge and topography data, we estimated the reasonable value of 3.2 m as the threshold of King Tide. This definition also fits to the statement by National Oceanic and Atmospheric Administration (NOAA) of King Tide occurring once or twice a year. In addition, We cross validate the 19 yr data of tide gauge and satellite altimeter (1993-2012), the correlation coefficient indicates King Tide phenomenon is considerable connected to warm water mass. The 28 King Tide events revealed the fact that flooding can be referenced against spring tide levels, so can it be turned up by warm water mass. The warm water mass pushes up sea level; once spring tide, storm surge, or other climate variability overlaps it, the rising sea level might overflow and so has been called "King Tide" for the floods in Tuvalu. This study provides more understanding of the signals of King Tide and an island country case study of regional sea level rise.

  5. Effect of horizontal displacements due to ocean tide loading on the determination of polar motion and UT1

    NASA Astrophysics Data System (ADS)

    Scherneck, Hans-Georg; Haas, Rüdiger

    We show the influence of horizontal displacements due to ocean tide loading on the determination of polar motion and UT1 (PMU) on the daily and subdaily timescale. So called ‘virtual PMU variations’ due to modelling errors of ocean tide loading are predicted for geodetic Very Long Baseline Interferometry (VLBI) networks. This leads to errors of subdaily determination of PMU. The predicted effects are confirmed by the analysis of geodetic VLBI observations.

  6. Atmospheric tides and the rotation of Venus. I - Tidal theory and the balance of torques

    NASA Technical Reports Server (NTRS)

    Dobrovolskis, A. R.; Ingersoll, A. P.

    1980-01-01

    Insolation absorbed by the surface of Venus is quickly redeposited at the bottom of the atmosphere. This periodic heating causes mass to flow away from the warm afternoon side of the planet and into the cooler morning region. The Sun's gravitational field exerts a torque on this atmospheric tide tending to accelerate the retrograde zonal circulation. When this torque is transmitted to the crust, it can balance the despinning effect of tides in the body of Venus. The slow retrograde rotation of Venus may be a steady state among tides in the atmosphere, tides in the solid body, and possibly the influence of the Earth.

  7. The self-consistent dynamic pole tide in non-global oceans

    NASA Technical Reports Server (NTRS)

    Dickman, S. R.

    1988-01-01

    The dynamic pole tide is determined by solving Laplace tide equations which take into account the presence of continents in oceans, oceanic self-gravitation and loading, and mantle elasticity. Dynamical effects are found to be only mild. It is shown that the dynamical pole tide contributes about one day more to the Chandler period than a static pole tide would, and dissipates wobble energy at a very weak rate. It is noted that, depending on the wobble period predicted for an oceanless elastic earth, mantle anelasticity at low frequencies may nevertheless contribute negligibly to the Chandler period.

  8. Calculating Rotating Hydrodynamic and Magnetohydrodynamic Waves to Understand Magnetic Effects on Dynamical Tides

    NASA Astrophysics Data System (ADS)

    Wei, Xing

    2016-09-01

    To understand magnetic effects on dynamical tides, we study the rotating magnetohydrodynamic (MHD) flow driven by harmonic forcing. The linear responses are analytically derived in a periodic box under the local WKB approximation. Both the kinetic and Ohmic dissipations at the resonant frequencies are calculated, and the various parameters are investigated. Although magnetic pressure may be negligible compared to thermal pressure, the magnetic field can be important for the first-order perturbation, e.g., dynamical tides. It is found that the magnetic field splits the resonant frequency, namely the rotating hydrodynamic flow has only one resonant frequency, but the rotating MHD flow has two, one positive and the other negative. In the weak field regime the dissipations are asymmetric around the two resonant frequencies and this asymmetry is more striking with a weaker magnetic field. It is also found that both the kinetic and Ohmic dissipations at the resonant frequencies are inversely proportional to the Ekman number and the square of the wavenumber. The dissipation at the resonant frequency on small scales is almost equal to the dissipation at the non-resonant frequencies, namely the resonance takes its effect on the dissipation at intermediate length scales. Moreover, the waves with phase propagation that is perpendicular to the magnetic field are much more damped. It is also interesting to find that the frequency-averaged dissipation is constant. This result suggests that in compact objects, magnetic effects on tidal dissipation should be considered.

  9. Internal tide oceanic tomography

    NASA Astrophysics Data System (ADS)

    Zhao, Zhongxiang

    2016-09-01

    A concept of internal tide oceanic tomography (ITOT) is proposed to monitor ocean warming on a global scale. ITOT is similar to acoustic tomography, but that work waves are internal tides. ITOT detects ocean temperature changes by precisely measuring travel time changes of long-range propagating internal tides. The underlying principle is that upper ocean warming strengthens ocean stratification and thus increases the propagation speed of internal tides. This concept is inspired by recent advances in observing internal tides by satellite altimetry. In particular, a plane wave fit method can separately resolve multiple internal tidal waves and thus accurately determines the phase of each wave. Two examples are presented to demonstrate the feasibility and usefulness of ITOT. In the eastern tropical Pacific, the yearly time series of travel time changes of the M2 internal tide is closely correlated with the El Niño-Southern Oscillation index. In the North Atlantic, significant interannual variations and bidecadal trends are observed and consistent with the changes in ocean heat content measured by Argo floats. ITOT offers a long-term, cost-effective, environmentally friendly technique for monitoring global ocean warming. Future work is needed to quantify the accuracy of this technique.

  10. Pattern formation in a spatial plant-wrack model with tide effect on the wrack.

    PubMed

    Sun, Gui-Quan; Li, Li; Jin, Zhen; Li, Bai-Lian

    2010-03-01

    Spatial patterns are a subfield of spatial ecology, and these patterns modify the temporal dynamics and stability properties of population densities at a range of spatial scales. Localized ecological interactions can generate striking large-scale spatial patterns in ecosystems through spatial self-organization. Possible mechanisms include oscillating consumer-resource interactions, localized disturbance-recovery processes, and scale-dependent feedback. However, in this paper, our main aim is to study the effect of tide on the pattern formation of a spatial plant-wrack model. We discuss the changes of the wavelength, wave speed, and the conditions of the spatial pattern formation, according to the dispersion relation formula. Both the mathematical analysis and numerical simulations reveal that the tide has great influence on the spatial pattern. More specifically, typical traveling spatial patterns can be obtained. Our obtained results are consistent with the previous observation that wracks exhibit traveling patterns, which is useful to help us better understand the dynamics of the real ecosystems.

  11. Effects of Neutron-Star Dynamic Tides on Gravitational Waveforms within the Effective-One-Body Approach

    NASA Astrophysics Data System (ADS)

    Hinderer, Tanja; Taracchini, Andrea; Foucart, Francois; Buonanno, Alessandra; Steinhoff, Jan; Duez, Matthew; Kidder, Lawrence E.; Pfeiffer, Harald P.; Scheel, Mark A.; Szilagyi, Bela; Hotokezaka, Kenta; Kyutoku, Koutarou; Shibata, Masaru; Carpenter, Cory W.

    2016-05-01

    Extracting the unique information on ultradense nuclear matter from the gravitational waves emitted by merging neutron-star binaries requires robust theoretical models of the signal. We develop a novel effective-one-body waveform model that includes, for the first time, dynamic (instead of only adiabatic) tides of the neutron star as well as the merger signal for neutron-star-black-hole binaries. We demonstrate the importance of the dynamic tides by comparing our model against new numerical-relativity simulations of nonspinning neutron-star-black-hole binaries spanning more than 24 gravitational-wave cycles, and to other existing numerical simulations for double neutron-star systems. Furthermore, we derive an effective description that makes explicit the dependence of matter effects on two key parameters: tidal deformability and fundamental oscillation frequency.

  12. Asymmetric effects on Earth's polar motion

    NASA Astrophysics Data System (ADS)

    Bizouard, Christian; Zotov, Leonid

    2013-06-01

    Differential equations ruling the Earth's polar motion are slightly asymmetric with respect to the pole coordinates. This is not only associated with the lack of axial symmetry around the Earth figure axis (triaxiality) but also with the longitude dependency of the pole tide (the main contribution). We propose a consistent handling of both asymmetric contributions, formulating a unique equation in the complex equatorial plane, of which we derive a general solution. Difference with respect to the usual symmetric solution is discussed and found significant in light of the present accuracy of the observed pole coordinates. For the same geophysical excitation, the prograde Chandler wobble is accompanied by a retrograde component up to 2 milliarcseconds (mas), transforming it in a slight elliptic motion. The asymmetric contribution is relatively larger in the geodetic excitation function, for Chandler wobble excitation mixes prograde and retrograde components of comparable level (1 mas).

  13. Age, habitat and tide effects on feeding activity of Emperor Geese during Autumn migration

    USGS Publications Warehouse

    Schmutz, Joel A.

    1994-01-01

    I studied feeding activity of Emperor Geese (Chen canagica) on the Alaska Peninsula during autumn migration, 1991. Scan samples were used to estimate the proportion of birds feeding in flocks as a measure of feeding intensity. Most geese fed during low tides and roosted during high tides. However, flocks with disproportionately more juveniles continued to feed during high tides in either blue mussel (Mytilus edulis) beds (during relatively low high tides) or in vegetated habitats. Feeding intensity was higher in mussel habitats than in mud/sand or vegetated habitats, and juveniles fed more than adults. Juvenile geese probably have greater nutritional needs than adults, and feeding during high tide may represent their attempt to satisfy these disproportionate demands. Vegetated habitats may be used when high value bivalve prey are unavailable due to tidal inundation.

  14. Effects of internal tidal dissipation and self-attraction and loading on semidiurnal tides in the Bohai Sea, Yellow Sea and East China Sea: a numerical study

    NASA Astrophysics Data System (ADS)

    Teng, Fei; Fang, Guohong; Xu, Xiaoqing

    2016-09-01

    A parameterized internal tide dissipation term and self-attraction and loading (SAL) tide term are introduced in a barotropic numerical model to investigate the dynamics of semidiurnal tidal constituents M2 and S2 in the Bohai Sea, Yellow Sea and East China Sea (BYECS). The optimal parameters for bottom friction and internal dissipation are obtained through a series of numerical computations. Numerical simulation shows that the tide-generating force contributes 1.2% of M2 power for the entire BYECS and up to 2.8% for the East China Sea deep basin. SAL tide contributes 4.4% of M2 power for the BYECS and up to 9.3% for the East China Sea deep basin. Bottom friction plays a major role in dissipating tidal energy in the shelf regions, and the internal tide effect is important in the deep water regions. Numerical experiments show that artificial removal of tide-generating force in the BYECS can cause a significant difference (as much as 30 cm) in model output. Artificial removal of SAL tide in the BYECS can cause even greater difference, up to 40 cm. This indicates that SAL tide should be taken into account in numerical simulations, especially if the tide-generating force is considered.

  15. Revisiting the pole tide for and from satellite altimetry

    NASA Astrophysics Data System (ADS)

    Desai, Shailen; Wahr, John; Beckley, Brian

    2015-12-01

    Satellite altimeter sea surface height observations include the geocentric displacements caused by the pole tide, namely the response of the solid Earth and oceans to polar motion. Most users of these data remove these effects using a model that was developed more than 20 years ago. We describe two improvements to the pole tide model for satellite altimeter measurements. Firstly, we recommend an approach that improves the model for the response of the oceans by including the effects of self-gravitation, loading, and mass conservation. Our recommended approach also specifically includes the previously ignored displacement of the solid Earth due to the load of the ocean response, and includes the effects of geocenter motion. Altogether, this improvement amplifies the modeled geocentric pole tide by 15 %, or up to 2 mm of sea surface height displacement. We validate this improvement using two decades of satellite altimeter measurements. Secondly, we recommend that the altimetry pole tide model exclude geocentric sea surface displacements resulting from the long-term drift in polar motion. The response to this particular component of polar motion requires a more rigorous approach than is used by conventional models. We show that erroneously including the response to this component of polar motion in the pole tide model impacts interpretation of regional sea level rise by ± 0.25 mm/year.

  16. Analyze satellite-tracking laser data in order to study satellite ephemerides, solid-Earth and ocean tides and laser system performance

    NASA Technical Reports Server (NTRS)

    Gaposchkin, E. M.

    1981-01-01

    The decrease in the semimajor axis of Lageos is considerably larger than expected. Gravitational effects, reference system effects, solar radiation pressure, Earth albedo pressure, neutral atmospheric drag, the Poynting Robertson Effect, and electrodynamic effects were used in explaining the observations. Quick look data provided are used to determine the Earth's polar motion and length of day. This process is routine, and provides these geophysical data every five days.

  17. Modelling the 2013 Typhoon Haiyan storm surge: Effect of waves, offshore winds, tide phase, and translation speed

    NASA Astrophysics Data System (ADS)

    Bilgera, P. H. T.

    2015-12-01

    Super Typhoon Haiyan, with wind speeds exceeding 300 km h-1 (160 knots) generated a storm surge in San Pedro Bay reaching heights of more than 6m in Tacloban City. Delft Dashboard (DDB), an open-source standalone Matlab based graphical user interface linked to the FLOW and WAVE modeling software of Deltares, was used to develop a coupled flow and wave storm surge model to understand the Typhoon Haiyan storm surge development and propagation. Various experiments were designed to determine the effect of waves, the occurrence of offshore winds prior to the surge, tidal phase, and typhoon translation speed on the surge height. Wave coupling decreased the surge height by about 0.5m probably due to energy dissipation from white capping, bottom friction, and depth-induced breaking. Offshore-directed winds before the arrival of the storm eye resulted to receding of the water level in San Pedro and Cancabato Bay, corroborated by eyewitness and tide gauge data. The experiment wherein the offshore winds were removed resulted to no water receding and a surge with a smaller and gentler surge front, pointing to the importance of the initial water level drawdown in contributing to the destructive power of the wave front. With regard to tides, the effect in Tacloban was actually neither linear nor additive to the surge, with higher surge coincident to low tides and lower surge coincident to high tides. Lastly, the model run with typhoon having a slower translation speed than Haiyan was found to generate higher surges.

  18. Effects of Cd, Cu, Ni, and Zn on brown tide alga Aureococcus anophagefferens growth and metal accumulation.

    PubMed

    Wang, Bin; Axe, Lisa; Michalopoulou, Zoi-Heleni; Wei, Liping

    2012-01-03

    Trace metals play important roles in regulating phytoplankton growth and could influence algal bloom development. Laboratory studies were conducted to evaluate the influence of environmentally relevant concentrations of Cd, Cu, Ni, and Zn on Aureococcus anophagefferens bloom (brown tide) development. Results show that the elevated Ni(2+) concentrations, e.g. those of brown tide waters in the northeastern US, greatly stimulated A. anophagefferens growth (as compared to the control without Ni addition), yet, only low amounts of dissolved Ni were sequestered, thus leaving excessive Ni directly promoting A. anophagefferens blooms. The medium effective concentration EC(50) (Me(2+)) suggests A. anophagefferens has similar Cd sensitivity but much greater Cu tolerance as compared to cyanobacteria, as such, excessive Cu could indirectly promote A. anophagefferens blooms by inhibiting competitors such as Synechococcus sp. The effects of Ni and Cu promoting growth are consistent with the recent genomic study of this alga. In addition, Zn(2+) concentrations lower than those in brown tide waters enhance A. anophagefferens growth, but Zn sequestration in A. anophagefferens would not substantially reduce total dissolved Zn in these waters. Overall, this study, showing that excessive Cu and Ni likely promote brown tides, provides evidence for trace metal linkages in algal bloom development.

  19. Atmospheric effects on earth rotation and polar motion

    NASA Technical Reports Server (NTRS)

    Salstein, David A.

    1988-01-01

    The variability in the earth's rotation rate not due to known solid body tides is dominated on time scales of about four years and less by variations in global atmospheric angular momentum (M) as derived from the zonal wind distribution. Among features seen in the length of day record produced by atmospheric forcing are the strong seasonal cycle, quasi-periodic fluctuations around 40-50 days, and an interannual signal forced by a strong Pacific warming event known as the El Nino. Momentum variations associated with these time scales arise in different latitudinal regions. Furthermore, winds in the stratosphere make a particularly important contribution to seasonal variability. Other related topics discussed here are: (1) comparisons of the M series from wind fields produced at different weather centers; (2) the torques that dynamically link the atmosphere and earth; and (3) longer-term nonatmospheric effects that can be seen upon removal of the atmospheric signal.an interestigapplication for climatological purposes is the use of the historical earth rotation series as a proxy for atmospheric wind variability prior to the era of upper-air data. Lastly, results pertaining to the role of atmospheric pressure systems in exciting rapid polar motion are presented.

  20. Geodesy by radio interferometry - Determinations of baseline vector, earth rotation, and solid earth tide parameters with the Mark I very long baseline radio interferometery system

    NASA Technical Reports Server (NTRS)

    Ryan, J. W.; Clark, T. A.; Coates, R. J.; Ma, C.; Wildes, W. T.

    1986-01-01

    Thirty-seven very long baseline radio interferometry experiments performed between 1972 and 1978 are analyzed and estimates of baseline vectors between six sites, five in the continental United States and one in Europe are derived. No evidence of significant changes in baseline length is found. For example, with a statistical level of confidence of approximately 85 percent, upper bounds on such changes within the United States ranged from a low of 10 mm/yr for the 850 km baseline between Westford, Massachusetts, and Green Bank, West Virginia, to a high of 90 mm/yr for the nearly 4000 km baseline between Westford and Goldstone, California. Estimates for universal time and for the x component of the position of the earth's pole are obtained. For the last 15 experiments, the only ones employing wideband receivers, the root-mean-square differences between the derived values and the corresponding ones published by the Bureau International de l'Heure are 0.0012 s and 0.018 arc sec respectively. The average value obtained for the radial Love number for the solid earth is 0.62 + or - 0.02 (estimated standard error).

  1. Permanent components of the crust, geoid and ocean depth tides

    NASA Astrophysics Data System (ADS)

    Sun, Wenke; Sjöberg, Lars E.

    2001-04-01

    The tidal deformation caused by the luni-solar potential includes not only a periodic part, but also a time-independent part, called the permanent tide. How to deal with the tidal correction in gravimetric observations, especially the treatment of the permanent tide, has been discussed for a long time, since some practical and physical problems exist anyhow. A resolution adopted by IAG (1983) was that the permanent tidal attraction of the Moon and the Sun should be eliminated, but the permanent tidal deformation of the Earth be maintained. This is called zero gravity, and the geoid associated with it is the zero geoid. As to the crust deformation, Poutanen et al. (Poutanen, M., Vermeer, M., Mäkinen, J., 1996. The permanent tide in GPS positioning. Journal of Geodesy 70, 499-504.) suggested that co-ordinates should be reduced to the zero crust, i.e. the crust that includes the effect of the permanent tide. This research shows that horizontal components of the permanent earth tides, which are not considered in recent studies, are also important in GPS positioning and geoid determination. Since the tide-generating potential can be expanded into harmonics and divided into two parts (geodetic coefficients and the group of harmonic waves), the permanent earth tides can be easily obtained by multiplying the amplitude of the zero-frequency wavelength by the corresponding geoid geodetic coefficient. Formulas for both elastic and fluid cases are presented. Numerical results for the elastic case show that he vertical permanent crust (zero crust), geoid and ocean depth tides reach -12.0, -5.8 and 6.1 cm at the poles, and 5.9, 2.9 and -3.0 cm at the equator, respectively. The horizontal permanent crust, geoid and ocean depth tide components reach as much as 2.5, 8.7 and 6.3 cm, respectively. According to the solution of IAG (1983), the permanent vertical components are kept in GPS positioning and geoid computation. Thus, it is natural to include the horizontal components

  2. TideNet

    DTIC Science & Technology

    2014-10-27

    mapping tools to query sources of tide data in a desired geographic region of the U.S. and its territories. Users can select a tide data source...produce tables and figures, and prepare input files for numerical models used in USACE projects. TideNet can fetch tide data, including plots and...tables from the source, or process tide data downloaded from any source site to perform additional analyses. The home page of the TideNet map in

  3. Research on Earth's rotation and the effect of atmospheric pressure on vertical deformation and sea level variability

    NASA Technical Reports Server (NTRS)

    Wahr, John

    1993-01-01

    The work done under NASA grant NAG5-485 included modelling the deformation of the earth caused by variations in atmospheric pressure. The amount of deformation near coasts is sensitive to the nature of the oceanic response to the pressure. The PSMSL (Permanent Service for Mean Sea Level) data suggest the response is inverted barometer at periods greater than a couple months. Green's functions were constructed to describe the perturbation of the geoid caused by atmospheric and oceanic loading and by the accompanying load-induced deformation. It was found that perturbation of up to 2 cm are possible. Ice mass balance data was used for continental glaciers to look at the glacial contributions to time-dependent changes in polar motion, the lod, the earth's gravitational field, the position of the earth's center-of-mass, and global sea level. It was found that there can be lateral, non-hydrostatic structure inside the fluid core caused by gravitational forcing from the mantle, from the inner core, or from topography at the core/mantle or inner core/outer core boundaries. The nutational and tidal response of a non-hydrostatic earth with a solid inner core was modeled. Monthly, global tide gauge data from PSMSL was used to look at the 18.6-year ocean tide, the 14-month pole tide, the oceanic response to pressure, the linear trend and inter-annual variability in the earth's gravity field, the global sea level rise, and the effects of post glacial rebound. The effects of mantle anelasticity on nutations, earth tides, and tidal variation in the lod was modeled. Results of this model can be used with Crustal Dynamics observations to look at the anelastic dissipation and dispersion at tidal periods. The effects of surface topography on various components of crustal deformation was also modeled, and numerical models were developed of post glacial rebound.

  4. Variation of the Earth tide-seismicity compliance parameter during the recent seismic activity in Fthiotida, central Greece

    NASA Astrophysics Data System (ADS)

    Arabelos, Dimitrios N.; Contadakis, Michael E.; Vergos, Georgios; Spatalas, Spyrous

    2016-01-01

    Based on the results of our previous studies concerning the tidal triggering effect on the seismicity in Greece, we consider the confidence level of earthquake occurrence - tidal period accordance as an index of tectonic stress criticality, associated with earthquake occurrence. Then, we investigate whether the recent increase in the seismic activity at Fthiotida in Greek mainland indicates faulting maturity and the possible production a stronger earthquake. In this paper we present the results of this investigation

  5. Variation of the Earth Tide-Seismicity Compliance Parameter the Last 50 Years for the South Himalaya Fault, Nepal

    NASA Astrophysics Data System (ADS)

    Contadakis, M. E.; Arabelos, D. N.; Vergos, G.; Scordilis, E. M.; Spatalas, S. D.

    2016-12-01

    Based on the results of our studies for the tidal triggering effect on the seismicity of the Hellenic area, we consider the confidence level of earthquake occurrence - tidal period accordance p as an index of tectonic stress criticality for earthquake occurrence. In this paper, by the occasion of the recent catastrophic earthquake of Nepal, we investigate the variation of the index p for the South Himalaya Fault area. The preliminary results indicate positive correlation of the index p with seismicity, for all the tidal periods. We suggest that this compliance parameter p may be used as an additional element for the seismic risk assessment.

  6. New ERP predictions based on (sub-)daily ocean tides from satellite altimetry data

    NASA Astrophysics Data System (ADS)

    Madzak, Matthias; Böhm, Sigrid; Böhm, Johannes; Bosch, Wolfgang; Schuh, Harald

    2013-04-01

    A new model for Earth rotation variations based on ocean tide models is highly desirable in order to close the gap between geophysical Earth rotation models and geodetic observations. We have started a project, SPOT (Short Period Ocean Tidal variations in Earth Rotation), with the goal to develop a new model of short period Earth rotation variations based on one of the best currently available empirical ocean tide models obtained from satellite altimetry. We employ the EOT11a model which is an upgrade of EOT08a, developed at DGFI, Munich. As EOT11a does not provide the tidal current velocities which are fundamental contributors to Earth rotation excitation, the calculation of current velocities from the tidal elevations is one of three main areas of research in project SPOT. The second key aspect is the conversion from ocean tidal angular momentum to the corresponding ERP variations using state-of-the-art transfer functions. A peculiar innovation at this step will be to consider the Earth's response to ocean tidal loading based on a realistic Earth model, including an anelastic mantle. The third part of the project deals with the introduction of the effect of minor tides. Ocean tide models usually only provide major semi-diurnal and diurnal tidal terms and the minor tides have to be inferred through admittance assumptions. Within the proposed project, selected minor tidal terms and the corresponding ERP variations shall be derived directly from satellite altimetry data. We determine ocean tidal angular momentum of four diurnal and five sub-daily tides from EOT11a and apply the angular momentum approach to derive a new model of ocean tidal Earth rotation variations. This poster gives a detailed description of project SPOT as well as the status of work progress. First results are presented as well.

  7. Effect of Lunar Phases, Tides, and Wind Speed on the Abundance of Diptera Calliphoridae in a Mangrove Swamp.

    PubMed

    Batista-da-Silva, J A

    2014-02-01

    Abiotic factors, such as lunar phases and tides, have a significant effect on insect development. Reproduction and immature development are usually interlinked to these abiotic factors. The tide is at its highest levels at full moon or new moon, hindering the feeding of the immature or causing their drowning. The oviposition by adult females is also compromised on these days because much of the available food is submerged. Another important abiotic factor is the wind, which displaces odoriferous particles in the air. Wind speed and direction are important elements to indicate potential sources of food for insects. I report on the effects of lunar phases, tides, and wind speed on the Calliphoridae fauna in mangrove swamps. The different species collected were identified, and the predominant species in the area were quantified. A total of 1,710 flies were collected over a 1-year period. Six Calliphoridae flies, Chloroprocta idioidea (Robineau-Desvoidy), Chrysomya megacephala (Fabricius), Chrysomya albiceps (Wiedemann), Chrysomya putoria (Wiedemann), Cochliomyia macellaria (Fabricius), and Lucilia eximia (Wiedemann) were collected. Data indicated that lunar phases have a significant effect on the abundance of C. albiceps (r = 0.39, p < 0.01), and that the variation of the tides also affected the abundance of C. putoria (r = 0.40, p < 0.00), C. macellaria (r = 0.41, p < 0.00), and C. idioidea (r = 0.31, p < 0.04). The wind speed, however, did not affect these species.

  8. The human health effects of Florida red tide (FRT) blooms: an expanded analysis.

    PubMed

    Hoagland, Porter; Jin, Di; Beet, Andrew; Kirkpatrick, Barbara; Reich, Andrew; Ullmann, Steve; Fleming, Lora E; Kirkpatrick, Gary

    2014-07-01

    Human respiratory and digestive illnesses can be caused by exposures to brevetoxins from blooms of the marine alga Karenia brevis, also known as Florida red tide (FRT). K. brevis requires macro-nutrients to grow; although the sources of these nutrients have not been resolved completely, they are thought to originate both naturally and anthropogenically. The latter sources comprise atmospheric depositions, industrial effluents, land runoffs, or submerged groundwater discharges. To date, there has been only limited research on the extent of human health risks and economic impacts due to FRT. We hypothesized that FRT blooms were associated with increases in the numbers of emergency room visits and hospital inpatient admissions for both respiratory and digestive illnesses. We sought to estimate these relationships and to calculate the costs of associated adverse health impacts. We developed environmental exposure-response models to test the effects of FRT blooms on human health, using data from diverse sources. We estimated the FRT bloom-associated illness costs, using extant data and parameters from the literature. When controlling for resident population, a proxy for tourism, and seasonal and annual effects, we found that increases in respiratory and digestive illnesses can be explained by FRT blooms. Specifically, FRT blooms were associated with human health and economic effects in older cohorts (≥55 years of age) in six southwest Florida counties. Annual costs of illness ranged from $60,000 to $700,000 annually, but these costs could exceed $1.0 million per year for severe, long-lasting FRT blooms, such as the one that occurred during 2005. Assuming that the average annual illness costs of FRT blooms persist into the future, using a discount rate of 3%, the capitalized costs of future illnesses would range between $2 and 24 million.

  9. Tides and deltaic morphodynamics

    NASA Astrophysics Data System (ADS)

    Plink-Bjorklund, Piret

    2016-04-01

    Tide-dominated and tide-influenced deltas are not widely recognized in the ancient record, despite the numerous modern and Holocene examples, including eight of the twelve modern largest deltas in the world, like the Ganges-Brahmaputra, Amazon, Chang Jiang, and Irrawadi. Furthermore, tide-dominated or tide-influenced deltas are suggested to be more common in inner-shelf or embayment settings rather than close to or at a shelf edge, primarily because wave energy is expected to be higher and tidal energy lower in outer shelf and shelf-edge areas. Thus, most shelf-edge deltas are suggested to be fluvial or wave dominated. However, there are ancient examples of tide-influenced shelf-edge deltas, indicating that the controls on tidal morphodynamics in deltas are not yet well understood. This paper asks the following questions: (1) How do tides influence delta deposition, beyond creating recognizable tidal facies? (2) Does tidal reworking create specific geometries in delta clinoforms? (3) Does tidal reworking change progradation rates of deltas? (4) Is significant tidal reworking of deltas restricted to inner-shelf deltas only? (5) What are the conditions at which deltas may be tidally influenced or tide-dominated in outer-shelf areas or at the shelf edge? (6) What are the main morphodynamic controls on the degree of tidal reworking of deltas? The paper utilizes a dataset of multiple ancient and modern deltas, situated both on the shelf and shelf edge. We show that beyond the commonly recognized shore-perpendicular morphological features and the recognizable tidal facies, the main effects of tidal reworking of deltas are associated with delta clinoform morphology, morphodynamics of delta lobe switching, delta front progradation rates, and the nature of the delta plain. Strong tidal influence is here documented to promote subaqueous, rapid progradation of deltas, by efficiently removing sediment from river mouth and thus reducing mouth bar aggradation and fluvial delta

  10. Simulation of the effects of proposed tide gates on circulation, flushing, and water quality in residential canals, Cape Coral Florida

    USGS Publications Warehouse

    Goodwin, Carl R.

    1991-01-01

    Decades of dredging and filling of Florida's low-lying coastal wetlands have produced thousands of miles of residential tidal canals and adjacent waterfront property. Typically, these canals are poorly flushed, and over time, accumulated organic-rich bottom materials, contribute to an increasingly severe degraded water quality. One-dimensional hydrodynamic and constituent-transport models were applied to two dead-end canal systems to determine the effects of canal system interconnection using tide gates on water circulation and constituent flushing. The model simulates existing and possible future circulation and flushing conditions in about 29 miles of the approximately 130 miles of tidally influenced canals in Cape Coral, located on the central west coast of peninsular Florida. Model results indicate that tidal water-level differences between the two canal systems can be converted to kinetic energy, in the form of increased water circulation, but the use of one-way tide gate interconnections. Computations show that construction of from one to four tide gates will cause replacement of a volume of water equivalent to the total volume of canals in both systems in 15 to 9 days, respectively. Because some canals flush faster than others, 47 and 21 percent of the original canal water will remain in both systems 50 days after start of operation of one and four tide gates, respectively. Some of the effects that such increased flushing are expected to have include reduced density stratification and associated dissolved-oxygen depletion in canal bottom waters, increased localized reaeration, and more efficient discharge of stormwater runoff entering the canals.

  11. Restoration and recovery of hurricane-damaged mangroves using the knickpoint retreat effect and tides as dredging tools.

    PubMed

    Bashan, Yoav; Moreno, Manuel; Salazar, Bernardo G; Alvarez, Leonardo

    2013-02-15

    In 2001, a hurricane moved a large sand dune, blocking the sole outlet channel of a mangrove. In the absence of daily tidal flow, the two ponds containing the mangrove vegetation evaporated, the secondary drainage channels were lost, and a salt crust formed on the bed of the ponds. The mangrove lost most of its trees and the remaining suffered from osmotic shock that led to defoliation. Restoration involved creating a knickpoint retreat (waterfall retreat effect) and tidal flow as a dredging mechanism to restore the outlet and form secondary channels in the ponds. During a very low tide, we deepened the mouth of the outlet channel by 1 m below high tide level to form a small waterfall when high tides receded. During successive tides, this one-step knickpoint deteriorated and formed a series of low rapids. With a steep gradient, the rapids retreated upstream into the ponds, first reopening the outlet channel and then carving new secondary channels in the pond mud flat. The excavation process of the outlet channel was repeated three times and was sufficient to effectively improve the hydrology of the entire pond system; allowing adequate flooding and draining of the mangrove ponds. Hydrology analysis tested by the Engelund-Hansen sediment transport formula established that the output of sediment from the ecosystem is greater than the input of sand into the mangroves. This is keeping the main channel continuously open. After eight years, tidal flow continues to keep the channels open; the salt crust has disappeared; the trees have recovered, and a large area of new vegetation has emerged.

  12. Europa Tide Movie

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Click on the image for Europa Tide Movie

    In this movie Europa is seen in a cutaway view through two cycles of its 3.5 day orbit about the giant planet Jupiter. Like Earth, Europa is thought to have an iron core, a rocky mantle and a surface ocean of salty water. Unlike on Earth, however, this ocean is deep enough to cover the whole moon, and being far from the sun, the ocean surface is globally frozen over. Europa's orbit is eccentric, which means as it travels around Jupiter, large tides, raised by Jupiter, rise and fall. Jupiter's position relative to Europa is also seen to librate, or wobble, with the same period. This tidal kneading causes frictional heating within Europa, much in the same way a paper clip bent back and forth can get hot to the touch, as illustrated by the red glow in the interior of Europa's rocky mantle and in the lower, warmer part of its ice shell. This tidal heating is what keeps Europa's ocean liquid and could prove critical to the survival of simple organisms within the ocean, if they exist.

  13. EVALUATION OF THE EFFECTS ON BENTHIC ORGANISMS FROM CLAY FLOCCULATION OF RED TIDE ORGANISMS

    EPA Science Inventory

    Evaluating the feasibility of controlling red tide using clay flocculation is part of an ECOHAB-funded project. One aspect for the feasibility and future application of clays is the determination of potential negative environmental impacts. The removal of toxin-containing dinofl...

  14. Effects of Tide Stage on the Use of Salt Marshes by Wading Birds in Rhode Island

    EPA Science Inventory

    To determine how tide stage affects wading bird abundance, behavior, and foraging in three Narragansett Bay salt marshes (RI), we conducted surveys at 10-min intervals—across the full tidal range—during six days at each marsh in July/September of 2006. The wading bird community ...

  15. Detecting supernovae neutrino with Earth matter effect

    NASA Astrophysics Data System (ADS)

    Liao, Wei

    2016-12-01

    We study Earth matter effect in oscillations of supernovae neutrinos. We show that detecting Earth matter effect gives an independent measurement of spectra of supernovae neutrinos, i.e., the flavor difference of the spectra of supernovae neutrinos. We study the effect of energy resolution and angular resolution of a final electron or positron on detecting the signal of Earth matter effect. We show that varying the widths of energy bins in analysis can change the signal strength of Earth matter effect and the statistical fluctuation. A reasonable choice of energy bins can both suppress the statistical fluctuation and make a good signal strength relative to the statistical fluctuation. Neutrino detectors with good energy resolution and good angular resolution are therefore preferred so that there is more freedom to vary energy bins and to optimize the signal of Earth matter effect in analyzing events of supernovae neutrinos.

  16. Tides In The Subglacial Lake Vostok, Antarctica

    NASA Astrophysics Data System (ADS)

    Dietrich, R.; Shibuya, K.; Pötzsch, A.; Ozawa, T.

    Subglacial lakes belong to the most interesting glaciological features in Antarctica, where the 240-km-long Lake Vostok is the most prominent one. For the understanding of the dynamics of the Lake Vostok system different compo- nents such as ice thickness and ice motion, lake bathymetry, geothermal heat flow, water circulation and melting-refreezing have to be investigated and modelled in a complex way. An aspect, which has not been considered yet, are lake tides. We present evidence based on observations which indicate the existence of tides in the lake. Earlier gravimetric tidal observations at Vostok Station show a significant deviation from theoretical solid earth tides which may be explained as the tidal effect of the water underneath the station. Interferometric SAR analysis yields a specific sur- face deformation pattern which is interpreted as a tidal signal too. According to our estimation the resulting magnitude of the vertical surface deformation is in the order of a few centimetres. The role of a `tidal pump' concerning the water circulation in the lake will be empha- sized.

  17. The effect of tides on sea ice, temperature and salinity fields in the Arctic Ocean on multi-decadal scales.

    NASA Astrophysics Data System (ADS)

    Luneva, Maria; Harle, James; Holt, Jason; Aksenov, Yevgeny

    2014-05-01

    The effects of tides on the hydrographical fields and sea-ice on multi-decadal timescales (from 1978-2007) has been examined using a newly developed Arctic Ocean NEMO-shelf-ice coupled model of moderate (10-15km) resolution, which explicitly simulates tides and processes in the benthic boundary layer. The model realistically reproduces the tides, which can be extremely strong on the Arctic shelf, with amplitudes reaching 4.4m in the Hudson Strait, 2-3m in the White Sea and above 1m in the Canadian Archipelago. It also accurately predicts the sea ice volume trends over this period, when compared with PIOMAS results, and demonstrates a stronger reduction in ice volume (by ~15%) and extent (by ~5%) in comparison with simulations without tides. By including tides in the Arctic simulation we find: (i) a decrease in ice thickness from 0.1 to 1m in Central Arctic, and up to 2m in the Canadian Archipelago; (ii) ice melting and thinning is accompanied by an increase in average surface salinity by 2PSU and changes of river freshwater pathways; (iii) cooling of the upper 300m of the Arctic Ocean in comparison with non-tidal simulations. We hypothesize that tidal mixing and advection support the supply of heat from warm Atlantic waters through the strongly stratified halocline layer. It has been found that tidal effects on the water mass structure are regionally localised, but subsequent can be transported across the entire basin. We discuss the following physical mechanisms for tidal influence: (a) increased vertical mixing near the bottom layer and on the ice-ocean interface; (b) opening and closing of leads in the sea ice in summer time altering the solar radiation flux to water below, thus affecting the ocean heat content and amount of ice melt ; (c) opening and closing of leads in the sea ice during winter leading to an increase the heat loss from the ocean to atmosphere, with subsequent ice production and brine rejection; (d) increased mixing in the pycnocline and at the

  18. Partitions and vertical profiles of 9 endocrine disrupting chemicals in an estuarine environment: Effect of tide, particle size and salinity.

    PubMed

    Yang, Lihua; Cheng, Qiao; Lin, Li; Wang, Xiaowei; Chen, Baowei; Luan, Tiangang; Tam, Nora F Y

    2016-04-01

    Phenolic endocrine disrupting chemicals (EDCs) in an estuarine water column in a depth profile of five water layers (0.05 D, 0.20 D, 0.60 D, 0.80 D and 0.90 D, D = Depth, 10.7 ± 0.7 m) and their corresponding environmental parameters (tide, salinity and particle size) were investigated over a year. Water sample from each layer was further separated into three fractions, which were dissolved, coarse (SPM-D, Φ ≥ 2.7 μm) and fine (SPM-F, 2.7 μm > Φ ≥ 0.7 μm) suspended particulate matters. Most of EDCs in the water column were presented in the dissolved fraction. Vertical profiles of salinity fluctuations showed that the upper water layer was most influenced by upstream flow. Estriol (E3), mestranol (Mes) and 17α-ethynylestradiol (EE2) concentrations were significantly higher in ebb tide than in flood tide, indicating that EDCs mainly came from terrestrial source, the upstream flow. Dissolved EDCs also exhibited high levels in the surface layer (0.05 D) due to the upstream source and atmosphere deposition, followed by the bottom layer (0.90 D) owing to the re-suspension of EDCs-containing sediment. Compared to the dissolved phase, the contents of BPA, Mes and EE2 in the solid phase were affected by particle size and exhibited a trend of SPM-F > SPM-D > sediment. On the other hand, the concentrations of octylphenol (OP) and t-nonylphenol (NP), the degradation products from common nonionic surfactants, in sediment were higher than those in suspended particles, and NP concentration was higher in flood tide than that in ebb tide. For both SPM-D and SPM-F, their corresponding EDCs concentrations were negatively related to SPM concentrations due to particle concentration effect (PCE). Owing to the "salting-out effect", salinity pushed EDCs from dissolved fraction to particulate or sedimentary phase.

  19. Altimetry, Orbits and Tides

    NASA Technical Reports Server (NTRS)

    Colombo, O. L.

    1984-01-01

    The nature of the orbit error and its effect on the sea surface heights calculated with satellite altimetry are explained. The elementary concepts of celestial mechanics required to follow a general discussion of the problem are included. Consideration of errors in the orbits of satellites with precisely repeating ground tracks (SEASAT, TOPEX, ERS-1, POSEIDON, amongst past and future altimeter satellites) are detailed. The theoretical conclusions are illustrated with the numerical results of computer simulations. The nature of the errors in this type of orbits is such that this error can be filtered out by using height differences along repeating (overlapping) passes. This makes them particularly valuable for the study and monitoring of changes in the sea surface, such as tides. Elements of tidal theory, showing how these principles can be combined with those pertinent to the orbit error to make direct maps of the tides using altimetry are presented.

  20. The magnetic tides of Honolulu

    USGS Publications Warehouse

    Love, Jeffrey J.; Rigler, Erin Joshua

    2013-01-01

    We review the phenomenon of time-stationary, periodic quiet-time geomagnetic tides. These are generated by the ionospheric and oceanic dynamos, and, to a lesser-extent, by the quiet-time magnetosphere, and they are affected by currents induced in the Earth's electrically conducting interior. We examine historical time series of hourly magnetic-vector measurements made at the Honolulu observatory. We construct high-resolution, frequency-domain Lomb-periodogram and maximum-entropy power spectra that reveal a panorama of stationary harmonics across periods from 0.1 to 10000.0-d, including harmonics that result from amplitude and phase modulation. We identify solar-diurnal tides and their annual and solar-cycle sideband modulations, lunar semi-diurnal tides and their solar-diurnal sidebands, and tides due to precession of lunar eccentricity and nodes. We provide evidence that a method intended for separating the ionospheric and oceanic dynamo signals by midnight subsampling of observatory data time series is prone to frequency-domain aliasing. The tidal signals we summarize in this review can be used to test our fundamental understanding of the dynamics of the quiet-time ionosphere and magnetosphere, induction in the ocean and in the electrically conducting interior of the Earth, and they are useful for defining a quiet-time baseline against which magnetospheric-storm intensity is measured.

  1. The magnetic tides of Honolulu

    NASA Astrophysics Data System (ADS)

    Love, J. J.; Rigler, E. J.

    2013-12-01

    We review the phenomenon of time-stationary, periodic quiet-time geomagnetic tides. These are generated by the ionospheric and oceanic dynamos, and, to a lesser-extent, by the quiet-time magnetosphere, and they are affected by currents induced in the Earth's electrically conducting interior. We examine historical time series of hourly magnetic-vector measurements made at the Honolulu observatory. We construct high-resolution, frequency-domain Lomb-periodogram and maximum-entropy power spectra that reveal a panorama of stationary harmonics across periods from 0.1 to 10000.0-d, including harmonics that result from amplitude and phase modulation. We identify solar-diurnal tides and their annual and solar-cycle sideband modulations, lunar semi-diurnal tides and their solar-diurnal sidebands, and tides due to precession of lunar eccentricity and nodes. We provide evidence that a method intended for separating the ionospheric and oceanic dynamo signals by midnight subsampling of observatory data time series is prone to frequency-domain aliasing. The tidal signals we summarize in this review can be used to test our fundamental understanding of the dynamics of the quiet-time ionosphere and magnetosphere, induction in the ocean and in the electrically conducting interior of the Earth, and they are useful for defining a quiet-time baseline against which magnetospheric-storm intensity is measured.

  2. The effect of channel deepening on tides and storm surge: A case study of Wilmington, NC

    NASA Astrophysics Data System (ADS)

    Familkhalili, R.; Talke, S. A.

    2016-09-01

    In this study we investigate the hypothesis that increasing channel depth in estuaries can amplify both tides and storm surge by developing an idealized numerical model representing the 1888, 1975, and 2015 bathymetric conditions of the Cape Fear River Estuary, NC. Archival tide gauge data recovered from the U.S. National Archives indicates that mean tidal range in Wilmington has doubled to 1.55 m since the 1880s, with a much smaller increase of 0.07 m observed near the ocean boundary. These tidal changes are reproduced by simulating channel depths of 7 m (1888 condition) and 15.5 m (modern condition). Similarly, model sensitivity studies using idealized, parametric tropical cyclones suggest that the storm surge in the worst-case, CAT-5 event may have increased from 3.8 ± 0.25 m to 5.6 ± 0.6 m since the nineteenth century. The amplification in both tides and storm surge is influenced by reduced hydraulic drag caused by greater mean depths.

  3. Lunar Core and Tides

    NASA Technical Reports Server (NTRS)

    Williams, J. G.; Boggs, D. H.; Ratcliff, J. T.

    2004-01-01

    Variations in rotation and orientation of the Moon are sensitive to solid-body tidal dissipation, dissipation due to relative motion at the fluid-core/solid-mantle boundary, and tidal Love number k2 [1,2]. There is weaker sensitivity to flattening of the core-mantle boundary (CMB) [2,3,4] and fluid core moment of inertia [1]. Accurate Lunar Laser Ranging (LLR) measurements of the distance from observatories on the Earth to four retroreflector arrays on the Moon are sensitive to lunar rotation and orientation variations and tidal displacements. Past solutions using the LLR data have given results for dissipation due to solid-body tides and fluid core [1] plus Love number [1-5]. Detection of CMB flattening, which in the past has been marginal but improving [3,4,5], now seems significant. Direct detection of the core moment has not yet been achieved.

  4. Effect of spring-neap tide and evaporation on the salt dynamics in estuarine marshes

    NASA Astrophysics Data System (ADS)

    Zhang, Chenming; Shen, Chengji; Xin, Pei; Li, Ling

    2016-04-01

    Salt dynamics in estuarine tidal marshes are strongly associated with their intrinsic hydrological processes and ecological behaviors, which are not well understood. Numerical simulations were carried out to investigate the transport and distribution of pore-water and salt in a vertical cross section perpendicular to a tidal creek that subjects to spring-neap tide and evaporation. Vaporizing pore-water from the unsaturated soil surface with salt left in, the time-variant actual evaporation is affected by aerodynamic factors as well as soil conditions, including pore-water saturation, salinity and the thickness of salt precipitation above the soil surface (efflorescence). Different simulation cases were performed by adjusting the potential evaporation rate, tidal signals, marsh platform slope and soil properties. The simulation analysis indicates that, the tide-averaged soil salinity increases with the reduction of inundation period under a spring-neap tide cycle. As the salt accumulated by evaporation could leave soil from seepage back to seawater during ebbtide, the pore-water salinity at the surface within the tidal range remains below solubility. Coarse soils tend to have more intensified seepage flow and hence less pore-water salinity than fine soils. With the presence of hyper-saline soil and efflorescence, salt flat develops only in the area where capillary connection between evaporating surface and water table is maintained while tidal inundation absent. On the contrary, the supratidal marsh where hydrological connections are disrupted keeps a relatively low soil salinity (40-60 ppt) and pore-water saturation as evaporation remains low throughout the tidal cycles.

  5. A survey of the theory of the Earth's rotation

    NASA Technical Reports Server (NTRS)

    Cannon, W. H.

    1981-01-01

    The theory of the Earth's rotation and the geophysical phenomena affecting it is examined. First principles are reviewed and the problem of polar motion and UT1 variations is formulated in considerable generality and detail. The effects of Earth deformations and the solid Earth tides are analyzed.

  6. In vivo effects of brown tide on the feeding function of the gill of the northern quahog Mercenaria mercenaria (Bivalvia: Veneridae).

    PubMed

    Robbins, Heather M; Bricelj, V Monica; Ward, J Evan

    2010-08-01

    The in vivo response of adult northern quahogs, Mercenaria mercenaria, to Aureococcus anophagefferens (brown tide) at the level of the gill was determined using video-endoscopy. Feeding activity, particle-approach velocities, and ventral-groove-transport velocities were documented after the quahogs were exposed to Isochryis galbana (baseline observations) supplemented with either toxic or nontoxic A. anophagefferens at two bloom concentrations (8 x 10(5) or 2 x 10(6) cells ml(-1)). Externally, there was no evidence of adverse effects of brown tide on feeding, as siphons remained extended and dilated. Toxic brown tide at both concentrations elicited gill muscular contractions, intermittent cessation of water flow, and decreased particle loading within the pallial cavity. The 8 x 10(5) cell ml(-1) toxic treatment had no significant effect on approach velocities or ventral-groove-transport velocities after 2 h, although time-averaging showed significant reduction of the latter during the last 30 min of exposure. The higher concentration of toxic brown tide caused a significant decrease in these velocities after only 1 h. Nontoxic brown tide produced none of these effects. Thus, A. anophagefferens compromised quahog feeding by stimulating contractions of the branchial musculature and interfering with lateral and ventral groove ciliary beating. These effects were both time- and concentration-dependent and could be caused by either a dopaminergic or a serotonergic toxic factor.

  7. A numerical model of nonmigrating diurnal tides between the surface and 65 km

    NASA Technical Reports Server (NTRS)

    Lieberman, Ruth S.; Leovy, Conway B.

    1995-01-01

    Observations of surface pressure and middle atmosphere temperatures and winds indicate that a substantial nonmigrating component is present in the diurnal tide. The nonmigrating tides, which propagate with a zonal phase speed that is different from the earth's rotation, are attributed to the diurnal heating of geographically fixed sources. In this study we utilize a classical tidal model to examine the propagation characteristics of diurnal tides. The global fields of tropospheric sensible, radiative, and latent heating used to drive the model are supplied from summer and winter diurnal climatologies of the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM2). A novel aspect of this study is the focus on the relative importance of the nonmigrating components. The classical model successfully reproduces many observed features of the low-latitude diurnal surface pressure tides. In the middle atmosphere, the simulated migrating (or sun-synchronous) tide shows qualitative agreement with November-March Limb Infrared Monitor of the Stratosphere (LIMS) observations. Tropospheric solar heating is clearly the dominant driving force for the migrating tide, with secondary contributions from boundary-layer sensible heating and tropospheric latent heat release. The leading modes of the zonal mean tide are also driven chiefly by tropospheric solar heating. The higher-order modes of the zonal mean and eastward propagating tides may be attributed to the joint effects of tropospheric solar heating, sensible heating, and latent heat release. The LIMS and other data reveal features that cannot be explained or examined within the context of the classical model used in the present study. These include upward phase propagation, vertical attenuation, and temporal variations in the migrating diurnal tide.

  8. Pole tide Love number - an important parameter for polar motion modeling

    NASA Astrophysics Data System (ADS)

    Kirschner, S.; Schmidt, M. G.; Seitz, F.

    2013-12-01

    The Euler-Liouville equation is the basic physical model to describe Earth rotation. It is based on the balance of angular momentum in the Earth system. The pole tide Love number is needed to characterize the rotational deformation effect, which depends on the internal structure and rheology of the Earth. There is a direct dependency between the pole tide Love number and the period and damping of the Chandler oscillation. Here we estimate the pole tide Love number on the basis of an inversion of the Euler-Liouville equation. The Earth orientation parameters are used as input parameters. They have been observed precisely over several decades by geodetic methods (C01 and C04 time series). It will be shown that the estimated pole tide Love number leads to significantly better results for polar motion compared to the original value taken from the Conventions of the International Earth Rotation and Reference System Service (IERS). Nevertheless the estimation is dependent on the input models for the subsystems (e.g. atmosphere and ocean models), applied estimation approach and time frame. These aspects are analyzed and discussed in detail.

  9. Effects of Assimilation Window Length and Radiatively Active Water Ice Clouds on Martian Thermal Tides and Martian Atmosphere Predictability

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Greybush, S. J.; Kalnay, E.; Hoffman, R. N.; Wilson, R.

    2013-12-01

    Martian therrnal tides are a particularly prominent feature that contribute much to the Martian atmospheric circulation and dust transport. To study the Mars diurnal features (or thermal tides), data assimilation based on the GFDL Mars Global Climate Model (MGCM) with the 4D-Local Ensemble Transform Kalman Filter (4D-LETKF) is used to perform a reanalysis of spacecraft temperature retrievals from the Thermal Emission Spectrometer (TES) and Mars Climate Sounder (MCS) instruments. Since the traditional 6-hr assimilation cycle induces spurious resonance in the Kelvin waves represented in both surface pressure and mid-level temperature, short assimilation window lengths (1-hour and 2-hour) are introduced in 4D-LETKF. In order to compare the performances of different assimilation window lengths, 10-sol forecasts based on the hour 00 and 12 reanalysis are evaluated and compared. The shorter windows show improved forecast root mean square difference with respect to observations, and not only remove the spurious resonance but also better compensate for the absence of radiatively active water ice clouds (RAC). The predictability of Martian atmosphere is also studied using multi-sol forecasts initiated from analyses employing different assimilation window lengths, and the effect of RAC on Martian atmospheric predictability is also discussed.

  10. Stratospheric Sudden Warming Effects on the Ionospheric Migrating Tides during 2008-2010 observed by FORMOSAT-3/COSMIC

    NASA Astrophysics Data System (ADS)

    Lin, J.; Lin, C.; Chang, L. C.; Liu, H.; Chen, W.; Chen, C.; Liu, J. G.

    2013-12-01

    In this paper, ionospheric electron densities obtained from radio occultation soundings of FORMOSAT-3/COSMIC are decomposed into their various constituent tidal components for studying the stratospheric sudden warming (SSW) effects on the ionosphere during 2008-2010. The tidal analysis indicates that the amplitudes of the zonal mean and major migrating tidal components (DW1, SW2 and TW3) decrease around the time of the SSW, with phase/time shifts in the daily time of maximum around EIA and middle latitudes. Meanwhile consistent enhancements of the SW2 and nonmigrating SW1 tides are seen after the stratospheric temperature increase. In addition to the amplitude changes of the tidal components, well matched phase shifts of the ionospheric migrating tides and the stratospheric temperatures are found for the three SSW events, suggesting a good indicator of the ionospheric response. Although the conditions of the planetary waves and the mean winds in the middle atmosphere region during the 2008-2010 SSW events may be different, similar variations of the ionospheric tidal components and their associated phase shifts are found. Futher, these ionospheric responses will be compared with realistic simulations of Thermosphere-Ionosphere-Mesophere-Electrodynamics General Circulation Model (TIME-GCM) by nudging Modern-Era Retrospective analysis for Research and Applications (MERRA) data.

  11. The ultimate high tide

    SciTech Connect

    Dean, R.G. )

    1990-01-01

    This paper discusses the possible coastal impacts of a rise in sea level. Control measures that are available to coastal communities are emphasized, including pumping of seawater into the ground, replenishing beach sand, protection or moving of potable-water intakes, elevating roadways, and building dikes. Economics will determine which, if any, measures are reasonable at a particular site. There is an upward trend in the mean CO{sub 2} concentration and predictions about the greenhouse effect are creating a rising tide of concern.

  12. Tides and Modern Geodesy

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.; Chao, Benjamin F. (Technical Monitor)

    2002-01-01

    In modem high-precision geodesy, and especially in modem space geodesy, every measurement that one makes contains tidal signals. Generally these signals are considered noise and must somehow be eliminated. The stringent requirements of the latest space geodetic missions place severe demands on tidal models. On the other hand, these missions provide the strongest data for improving tidal models. In particular, TOPEX/POSEIDON altimetry and LAGEOS laser ranging have improved models to such an extent that new geophysical information about the ocean and the solid Earth are coming to light. Presumably GRACE intersatellite ranging data will also add to this information. This paper discusses several of these new geophysical results, with special emphasis given to the dissipation of tidal energy. Strong constraints have recently been placed on the partitioning of energy dissipation among the ocean, atmosphere, and solid earth and between the deep and shallow ocean. The dissipation in deep water is associated with internal tides and has potentially important implications for understanding the ocean's thermohaline circulation.

  13. Solar Cycle Variability in Mean Thermospheric Composition and Temperature Induced by Atmospheric Tides

    NASA Astrophysics Data System (ADS)

    Jones, M., Jr.; Forbes, J. M.; Hagan, M. E.

    2015-12-01

    Vertically-propagating atmospheric thermal tides whose origins lie in Earth's lower atmosphere are now widely recognized as one of the dominant "meteorological" drivers of space weather. Many prior research efforts have focused on documenting and understanding the role that dissipating tides play in determining the longitudinal and seasonal variability associated with lower thermospheric winds, temperature, and constituent densities. However, considerably less attention has focused on understanding the potential solar cycle variability in the mean thermospheric state induced by the tides. In this paper we utilize the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM), forced with observationally-based tides at the model lower boundary from the Climatological Tidal Model of the Thermosphere (CTMT, from Oberheide et al. [2011]), to elucidate how the dissipating tides induce variations of up to 30 K in the zonal-mean thermosphere temperature between solar minimum and maximum. Numerical experiments are performed for the month of September and for solar minimum, medium, and maximum conditions in order to quantify the solar cycle variability associated with the different terms in the thermodynamic energy, major and minor neutral constituent continuity equations. Our analysis indicates that solar cycle variability in neutral temperatures results from a combination of net eddy heat transport effects and tidal modulation of net nitric oxide (NO) cooling. The chemical and dynamical pathways through which dissipating tides affect mean NO cooling differently at solar minimum and maximum are diagnosed.

  14. Tides and Trends in Higher Education.

    ERIC Educational Resources Information Center

    Fincher, Cameron

    This paper examines changes in American higher education, using the metaphor of ocean tides. The tides of change in the 1980s included public demands for assessment and accountability; fairness and credibility in advantages and benefits; improved quality of education; effectiveness and efficiency; assurance that college graduates were personally…

  15. Effects of Florida Red Tides on histone variant expression and DNA methylation in the Eastern oyster Crassostrea virginica.

    PubMed

    Gonzalez-Romero, Rodrigo; Suarez-Ulloa, Victoria; Rodriguez-Casariego, Javier; Garcia-Souto, Daniel; Diaz, Gabriel; Smith, Abraham; Pasantes, Juan Jose; Rand, Gary; Eirin-Lopez, Jose M

    2017-03-07

    Massive algal proliferations known as Harmful Algal Blooms (HABs) represent one of the most important threats to coastal areas. Among them, the so-called Florida Red Tides (FRTs, caused by blooms of the dinoflagellate Karenia brevis and associated brevetoxins) are particularly detrimental in the southeastern U.S., causing high mortality rates and annual losses in excess of $40 million. The ability of marine organisms to cope with environmental stressors (including those produced during HABs) is influenced by genetic and epigenetic mechanisms, the latter resulting in phenotypic changes caused by heritable modifications in gene expression, without involving changes in the genetic (DNA) sequence. Yet, studies examining cause-effect relationships between environmental stressors, specific epigenetic mechanisms and subsequent responses are still lacking. The present work contributes to increase this knowledge by investigating the effects of Florida Red Tides on two types of mechanisms participating in the epigenetic memory of Eastern oysters: histone variants and DNA methylation. For that purpose, a HAB simulation was conducted in laboratory conditions, exposing oysters to increasing concentrations of K. brevis. The obtained results revealed, for the first time, the existence of H2A.X, H2A.Z and macroH2A genes in this organism, encoding histone variants potentially involved in the maintenance of genome integrity during responses to the genotoxic effect of brevetoxins. Additionally, an increase in H2A.X phosphorylation (γH2A.X, a marker of DNA damage) and a decrease in global DNA methylation were observed as the HAB simulation progressed. Overall, the present work provides a basis to better understand how epigenetic mechanisms participate in responses to environmental stress in marine invertebrates, opening new avenues to incorporate environmental epigenetics approaches into management and conservation programs.

  16. The magnetic tides of Honolulu

    NASA Astrophysics Data System (ADS)

    Love, Jeffrey J.; Rigler, E. Joshua

    2014-06-01

    We review and analyse the phenomenon of time-invariant, periodic geomagnetic tides. These are generated by the deterministic physics of the ionospheric and oceanic dynamos, and, to a lesser extent, by the solar-quiet magnetosphere, and they are affected by currents induced in the Earth's electrically conducting interior. Using a long historical time-series of hourly magnetic vector measurements made at the Honolulu observatory, we construct high-resolution, frequency-domain power spectra across periods from 0.1 to 10 000.0 d using maximum-entropy and Lomb periodogram algorithms. Recognizing that harmonics corresponding to fundamental forcing periods can, themselves, have amplitude and phase modulation driven by other forcing harmonics, we identify solar-diurnal tides and their annual and solar-cycle sideband modulations, lunar semidiurnal tides and their solar-diurnal sidebands, and tides due to precession of lunar eccentricity and nodes. In contrast to reports by other investigators, we cannot identify tidal signals that might be related to the 22-yr Hale cycle, the Chandler wobble and the quasi-biennial oscillation. Using a least-squares algorithm to estimate the amplitudes and phases of individual tidal constituents, we construct synthetic model time-series that are representative of geomagnetic tidal variation. The signals summarized in this report can be used to test fundamental understanding of the dynamics of the solar-quiet ionosphere and magnetosphere, the ocean and the electrically conducting interior of the Earth, and they can be used to specify a quiet-time baseline against which magnetospheric storm disturbance can be measured.

  17. Investigations of earth dynamics from satellite observations

    NASA Technical Reports Server (NTRS)

    Gaposchkin, E. M.

    1973-01-01

    The consequences of the earth's elasticity are examined for close-earth satellites. The ideas of polar motion and earth tides are developed in a form applicable to satellite studies, since the polar motion, the body tide, and the ocean tide are all suitable for study by use of satellites. Analysis of available polar-motion data is performed.

  18. Excitation of nutation by the global radiational S1 tide

    NASA Astrophysics Data System (ADS)

    Schindelegger, M.; Salstein, D. A.; Einspigel, D.; Boehm, J.

    2014-12-01

    Cyclic mass redistributions in the atmosphere and oceans related to the global radiational S1 tide elicit seasonal perturbations of Earth's nutation at a level of 0.1 mas (milliarcseconds). The present study provides an up-to-date assessment of these excitation effects on the basis of 10-year surface and isobaric level data from three, previously unavailable global atmospheric reanalysis systems. We retrieve numerical values of in- and out-of-phase nutation corrections for seasonally modulated S1 variations and indicate how model improvements, specifically in terms of the representation of tidal oscillations, lead to different estimates with respect to earlier reanalyses. Motion term signals in nutation display a close agreement across all probed datasets, whereas larger disparities remain among mass term excitation estimates due to their dependency on small-scale diurnal surface pressure oscillations. A simple time-stepping model for barotropic ocean dynamics, based on the shallow water equations and driven by air pressure tide climatologies, represents an appropriate means to determine global S1 estimates of sea level heights and currents that are consistent with the respective forcing fields from each reanalysis. We address the intricacies of constructing such a model and compare our preliminary oceanic angular momentum solutions to those from more established hydrodynamic forward integrations. The combined influence of the S1 tide on Earth's nutation, associated with both atmosphere and ocean dynamics, is found to yield a rough agreement with observations from geodetic VLBI (Very Long Baseline Interferometry) measurements.

  19. Changes in the Earth's Spin Rotation due to the Atmospheric Effects and Reduction in Glaciers

    NASA Astrophysics Data System (ADS)

    Na, Sung-Ho; Cho, Jungho; Kim, Tu-Hwan; Seo, Kiweon; Youm, Kookhyoun; Yoo, Sung-Moon; Choi, Byungkyu; Yoon, Hasu

    2016-12-01

    The atmosphere strongly affects the Earth's spin rotation in wide range of timescale from daily to annual. Its dominant role in the seasonal perturbations of both the pole position and spinning rate of the Earth is once again confirmed by a comparison of two recent data sets; i) the Earth orientation parameter and ii) the global atmospheric state. The atmospheric semi-diurnal tide has been known to be a source of the Earth's spin acceleration, and its magnitude is re-estimated by using an enhanced formulation and an up-dated empirical atmospheric S2 tide model. During the last twenty years, an unusual eastward drift of the Earth's pole has been observed. The change in the Earth's inertia tensor due to glacier mass redistribution is directly assessed, and the recent eastward movement of the pole is ascribed to this change. Furthermore, the associated changes in the length of day and UT1 are estimated.

  20. Tides at the east coast of Lanzarote Island

    NASA Astrophysics Data System (ADS)

    Benavent, M.; Arnoso, J.; Vélez, E. J.

    2012-04-01

    The main goal of this work is the study of the ocean tides at the east coast of Lanzarote (Canary Islands). We have analyzed time series of tide gauge and bottom pressure observations available in the region and we have made a further comparative validation with recent global and local ocean tide models. Lanzarote island shows singular features, with regard its volcanic structure and geomorphological properties and, also, concerning the characteristics of the ocean tides in the surrounding waters. For this reason, this region experiences a great interest in Geodesy and Geodynamics. Particularly, an accurate modelization of the ocean tides is of great importance to correct with high accuracy the effect of the ocean over the multiple geodetic measurements that are being carried out in the Geodynamic Laboratory of Lanzarote, LGL (Vieira et al., 1991; 2006). Furthermore, the analysis of tide gauge and bottom pressure records in this area is of great importance to investigate sea level variations, to evaluate and quantify the causes of these changes and the possible correlation with vertical movements of the Earth's crust. The time series of sea level and bottom pressure data considered in this work are obtained at two different locations of the island and, in each of them, using several sensors at different periods of time. First location is Jameos del Agua (JA) station, which belongs to the LGL. This station is placed in the open ocean, 200 meters distant from the northeastern coast of the island and at 8 meters depth. The observations have been carried out using 3 bottom pressure sensors (Aanderaa WLR7, SAIV TD301A and Aqualogger 210PT) at different periods of time (spanning a total of six years). Second location is Arrecife (AR) station, which is 23 km south of JA station. In this case, the sea level data come from a float tide gauge belonging to the Instituto Español de Oceanografía, installed at the beginning of the loading bay, and a radar tide gauge from the

  1. [Synergistic effects of low temperature in winter and ebb tide at night on Sonneratia apetala seedlings growth and key eco-physiological traits].

    PubMed

    Chen, Lu-Zhen; Du, Xiao-Na; Lu, Luan-Mei; Zheng, Shi-Jie; Yang, Sheng-Chang

    2012-04-01

    By setting up a set of simulated tidal systems with different air- and water temperature and tidal flood conditions, this paper studied the synergistic effects of low temperature in winter and ebb tide at night on the growth and key eco-physiological traits of Sonneratia apetala seedlings. Low air temperature depressed the seedlings growth, but the reduction in the seedling height and basal stem diameter was compensated 41.2% and 44.6%, respectively by a 5 degrees C increase of water temperature. Low air temperature (15 degrees C) reduced the leaf Fv/Fm significantly, indicating a dramatic reduction in the leaf photosynthetic capacity, whereas the flooded tide with higher water temperature could not compensate this damage. The flooded tide with high air temperature increased the proline and soluble sugar contents in mature leaves, which could protect the mature leaves from cold damage. When extreme cold events occurred, the flooded tide at night worked as a heat storage medium, which alleviated the cold damage on the seedlings growth and leaf physiological traits, and promoted the survival rate of S. apetala seedlings.

  2. Red Tide Strands South African Rock Lobsters

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Although some red tides form a healthy part of phytoplankton production, recurrent harmful or toxic blooms also occur, with results depending upon the type of plankton and on atmospheric and oceanic conditions. At Elands Bay in South Africa's Western Cape province, about 1000 tons of rock lobsters beached themselves during February 2002, when the decay of dense blooms of phytoplankton caused a rapid reduction in the oxygen concentration of nearshore waters. The lobsters (or crayfish, as they are known locally) moved toward the breaking surf in search of oxygen, but were stranded by the retreating tide.

    The Multi-angle Imaging SpectroRadiometer's nadir camera acquired these red, green, blue composites on February 2 and 18, 2002, during Terra orbits 11315 and 11548. The colors have been accentuated to highlight the bloom, and land and water have been enhanced separately. The two views show the shoreward migration of the algal bloom. Each image represents an area of about 205 kilometers x 330 kilometers. Elands Bay is situated near the mouth of the Doring River, about 75 kilometers northeast of the jutting Cape Columbine.

    The term 'red tide' is used to refer to a number of different types of phytoplankton blooms of various hues. The wine color of certain parts of this bloom are consistent with the ciliate species Mesodinium rubrum, which has been associated with recurring harmful algal blooms along the Western Cape coast. Under these conditions, the lobsters are not poisoned. During the recent event, government and military staff transported as many of the living lobsters as possible to areas that were less affected by the red tide. At the same time, people came from across South Africa to gather the undersized creatures for food. The effects of the losses on the maritime economy are expected to be felt over the next few years.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington

  3. Red Tide Strands South African Rock Lobsters

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Although some red tides form a healthy part of phytoplankton production, recurrent harmful or toxic blooms also occur, with results depending upon the type of plankton and on atmospheric and oceanic conditions. At Elands Bay in South Africa's Western Cape province, about 1000 tons of rock lobsters beached themselves during February 2002, when the decay of dense blooms of phytoplankton caused a rapid reduction in the oxygen concentration of nearshore waters. The lobsters (or crayfish, as they are known locally) moved toward the breaking surf in search of oxygen, but were stranded by the retreating tide. The Multi-angle Imaging SpectroRadiometer's nadir camera acquired these red, green, blue composites on February 2 and 18, 2002, during Terra orbits 11315 and 11548. The colors have been accentuated to highlight the bloom, and land and water have been enhanced separately. The two views show the shoreward migration of the algal bloom. Each image represents an area of about 205 kilometers x 330 kilometers. Elands Bay is situated near the mouth of the Doring River, about 75 kilometers northeast of the jutting Cape Columbine. The term 'red tide' is used to refer to a number of different types of phytoplankton blooms of various hues. The wine color of certain parts of this bloom are consistent with the ciliate species Mesodinium rubrum, which has been associated with recurring harmful algal blooms along the Western Cape coast. Under these conditions, the lobsters are not poisoned. During the recent event, government and military staff transported as many of the living lobsters as possible to areas that were less affected by the red tide. At the same time, people came from across South Africa to gather the undersized creatures for food. The effects of the losses on the maritime economy are expected to be felt over the next few years. MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra

  4. Tide operated power generating apparatus

    SciTech Connect

    Kertzman, H. Z.

    1981-02-03

    An improved tide operated power generating apparatus is disclosed in which a hollow float, rising and falling with the ocean tide, transmits energy to a power generator. The improvement comprises means for filling the float with water during the incoming tide to provide a substantial increase in the float dead weight during the outgoing tide. Means are further provided to then empty the float before the outgoing tide whereby the float becomes free to rise again on the next incoming tide.

  5. A Modeling Study of the Effect of Tide Energy Extraction on Estuarine Circulation and Its Implication on Water Quality

    NASA Astrophysics Data System (ADS)

    Wang, T.; Yang, Z.; Copping, A. E.

    2011-12-01

    The growing interest in harnessing tidal energy has raised concerns about the impact of energy extraction on water circulation, and the implication those changes can have on water quality and the marine food web. There are few direct observations of the effect of energy extraction on ecosystems; however our understanding of the magnitude and importance of these effects can be enhanced through numerical analysis at the appropriate temporal and spatial scales This paper presents a numerical modeling study to simulate in-stream tidal energy extraction and assess its effect on the circulation and mixing in a tide-dominated estuary using a three-dimensional (3D) unstructured grid finite volume coastal ocean model. A tidal turbine module is incorporated into the hydrodynamic model using a momentum source/sink approach. The tidal turbine module is applied to simulate the tidal energy extraction in an idealized tidal system. A series of numerical experiments are carried out to assess the effect of tidal energy extraction on volume flux, vertical velocity structure, and flushing time within the system. The implication of changes in physical processes due to tidal energy extraction on water quality is also discussed, including changes in dissolved oxygen, nutrients and chlorophyll.

  6. Earth Sphericity Effects on Subduction Morphology

    NASA Astrophysics Data System (ADS)

    Morra, G.; Chatelain, P.; Tackley, P.; Koumoutsakos, P.

    2007-12-01

    We present here the first application in Geodynamics of a Multipole accelerated Boundary Element Method (FMM- BEM) for Stokes Flow. The approach offers the advantage of a reduced number of computational elements and linear scaling with the problem size. We show that this numerical mehod can be fruitfully applied to the simulation of several geodynamic systems at the planetary scale in spheical coordinates and we suggest a general appraoch for modeling combined mantle convection and plate tectonics. The potentialities of the approach are shown investigating the effect played by Earth sphericity on the subduction of a very wide oceanic lithosphere , comparing the morphology of the subducted lithosphere in a spherical and in flat setting. The results show a striking difference between the two models: while the slab on a "flat Earth" shows slight undulation, the same subducting plate on a spherical Earth-like setting presents a distinct folding below the trench far from the edges, with wavelength of (1000km-2000km) as Pacific trenches.

  7. Effect of rotating earth for AOTV analysis

    NASA Astrophysics Data System (ADS)

    Ikawa, H.

    The Aeroassisted Orbit Transfer Vehicle (AOTV) operates in the endo/exoatmosphere. Exoatmospheric flight phase is dictated only by the inertial properties. In endoatmospheric flight phase, the trajectory is also shaped by the inertial velocity. However, the aerodynamic maneuver that causes the trajectory perturbation is controlled by the relative velocity. For example, along the equatorial flight path: (1) the velocity difference between the inertial and the relative reference frames represents 5 to 7 percent of the entry velocity; (2) the dynamic pressure difference becomes 10 to 14 percent, which is significant in evaluating the proper atmospheric flight maneuver; (3) in consequence, exit errors that are induced at the edge of the sensible atmosphere produce significant deviation in the final orbit transfer. The possible errors affecting AOTV analyses conducted by neglecting the earth's rotation are discussed. The control laws using the shallow glide path ascent and the constant altitude glide trajectories in the atmosphere, with the required pull-up maneuver, are also demonstrated. Conclusions are: (1) AOTV analyses using the stationary earth assumption tend to underpredict the final LEO altitude and to overpredict the orbital inclination change, and (2) effects of the rotating earth cannot be ignored for realistic AOTV simulations.

  8. Florida Red Tide Perception: Residents versus Tourists

    PubMed Central

    Nierenberg, Kate; Byrne, Margaret; Fleming, Lora E.; Stephan, Wendy; Reich, Andrew; Backer, Lorraine C.; Tanga, Elvira; Dalpra, Dana R.; Kirkpatrick, Barbara

    2010-01-01

    The west coast of Florida has annual blooms of the toxin-producing dinoflagellate, Karenia brevis with Sarasota, FL considered the epicenter for these blooms. Numerous outreach materials, including Frequently Asked Question (FAQ) cards, exhibits for local museums and aquaria, public beach signs, and numerous websites have been developed to disseminate information to the public about this natural hazard. In addition, during intense onshore blooms, a great deal of media attention, primarily via newspaper (print and web) and television, is focused on red tide. However to date, the only measure of effectiveness of these outreach methods has been counts of the number of people exposed to the information, e.g., visits to a website or number of FAQ cards distributed. No formal assessment has been conducted to determine if these materials meet their goal of informing the public about Florida red tide. Also, although local residents have the opinion that they are very knowledgeable about Florida red tide, this has not been verified empirically. This study addressed these issues by creating and administering an evaluation tool for the assessment of public knowledge about Florida red tide. A focus group of Florida red tide outreach developers assisted in the creation of the evaluation tool. The location of the evaluation was the west coast of Florida, in Sarasota County. The objective was to assess the knowledge of the general public about Florida red tide. This assessment identified gaps in public knowledge regarding Florida red tides and also identified what information sources people want to use to obtain information on Florida red tide. The results from this study can be used to develop more effective outreach materials on Florida red tide. PMID:20824108

  9. Florida Red Tide Perception: Residents versus Tourists.

    PubMed

    Nierenberg, Kate; Byrne, Margaret; Fleming, Lora E; Stephan, Wendy; Reich, Andrew; Backer, Lorraine C; Tanga, Elvira; Dalpra, Dana R; Kirkpatrick, Barbara

    2010-09-01

    The west coast of Florida has annual blooms of the toxin-producing dinoflagellate, Karenia brevis with Sarasota, FL considered the epicenter for these blooms. Numerous outreach materials, including Frequently Asked Question (FAQ) cards, exhibits for local museums and aquaria, public beach signs, and numerous websites have been developed to disseminate information to the public about this natural hazard. In addition, during intense onshore blooms, a great deal of media attention, primarily via newspaper (print and web) and television, is focused on red tide. However to date, the only measure of effectiveness of these outreach methods has been counts of the number of people exposed to the information, e.g., visits to a website or number of FAQ cards distributed. No formal assessment has been conducted to determine if these materials meet their goal of informing the public about Florida red tide. Also, although local residents have the opinion that they are very knowledgeable about Florida red tide, this has not been verified empirically. This study addressed these issues by creating and administering an evaluation tool for the assessment of public knowledge about Florida red tide. A focus group of Florida red tide outreach developers assisted in the creation of the evaluation tool. The location of the evaluation was the west coast of Florida, in Sarasota County. The objective was to assess the knowledge of the general public about Florida red tide. This assessment identified gaps in public knowledge regarding Florida red tides and also identified what information sources people want to use to obtain information on Florida red tide. The results from this study can be used to develop more effective outreach materials on Florida red tide.

  10. Tides and tsunamis

    NASA Technical Reports Server (NTRS)

    Zetler, B. D.

    1972-01-01

    Although tides and tsunamis are both shallow water waves, it does not follow that they are equally amenable to an observational program using an orbiting altimeter on a satellite. A numerical feasibility investigation using a hypothetical satellite orbit, real tide observations, and sequentially increased levels of white noise has been conducted to study the degradation of the tidal harmonic constants caused by adding noise to the tide data. Tsunami waves, possibly a foot high and one hundred miles long, must be measured in individual orbits, thus requiring high relative resolution.

  11. The moon's acceleration produced by the ocean tides

    NASA Astrophysics Data System (ADS)

    Pimenta, A. F.; Afonso, G. B.

    2003-08-01

    The well-known tides induced on Earth by the Sun and the Moon have had several long-term effects over the age of Earth. Most notably, the transfer of angular momentum from Earth to the Moon has resulted in an appreciable secular increase in the length of the day and a retreat of the Moon from Earth. The implications of employing the present rate of tidal energy dissipation on a geological timescale are catastrophic: around 1500 Ma the Moon would have been close to Earth, with the consequence that the much larger tidal forces would have disrupted the Moon. Based on the data about the Earth's rotation, since 1623, provided by IERS, we investigated the secular perturbations in the past of the Earth-Moon system. Using IERS data and the equation for the transfer of rotational angular momentum from Earth to the lunar orbital angular momentum due to tidal friction of the Moon and the Sun we found equations for the Earths angular velocity and semi-major axis of Moons orbit. Our model furnishes a point of maximum approximation of the Moon at 4500 Ma, in a good agreement with the modern theories about the Earth-Moon system formation and with the results obtained through the analysis of sedimentary cyclic rhythmites. Thus, our model gives a good description of the Earth-Moon system past for any time. It can be further improved by including recent, high-accurate measurements and more reliable data concerning the ancient Earth's rotation values for comparison.

  12. Pole tide in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Medvedev, I. P.; Rabinovich, A. B.; Kulikov, E. A.

    2014-03-01

    The pole tide, which is driven by the Chandler Wobble, has a period of about 14 months and typical amplitudes in the World Ocean of ˜0.5 cm. However, in the Baltic Sea the pole tide is anomalously high. To examine this effect we used long-term hourly sea level records from 23 tide gauges and monthly records from 64 stations. The lengths of the series were up to 123 years for hourly records and 211 years for monthly records. High-resolution spectra revealed a cluster of neighboring peaks with periods from 410 to 440 days. The results of spectral analysis were applied to estimate the integral amplitudes of pole tides from all available tide gauges along the coast of the Baltic Sea. The height of the pole tide was found to gradually increase from the entrance (Danish Straits, 1.5-2 cm) to the northeast end of the sea. The largest amplitudes—up to 4.5-7 cm—were observed in the heads of the Gulf of Finland and the Gulf of Bothnia. Significant temporal fluctuations in amplitudes and periods of the pole tide were observed during the 19th and 20th centuries.

  13. A Rising Tide

    ERIC Educational Resources Information Center

    Nation, Molly Trendell; Feldman, Allan; Wang, Ping

    2015-01-01

    Global climate change and its effects are real and immediate. Students must gain an understanding of climate science so they can participate in public debate about how to reduce the emission of heat-trapping gases and how their communities can mitigate the effects of global warming. In this activity, students model these effects on Earth's oceans…

  14. MST radar detection of middle atmosphere tides

    NASA Technical Reports Server (NTRS)

    Forbes, J. M.

    1983-01-01

    Meteorological and dynamical requirements pertaining to the specification of middle atmosphere tides by the MST radar technique are outlined. Major issues addressed include: (1) the extraction of tidal information from measurements covering a fraction of a day; (2) the ramifications of transient effects (tidal variability) on the determination and interpretation of tides; (3) required temporal and spatial resolutions and; (4) global distributions of MST radars, so as to complement existing MST, meteor wind, and partial reflection drift radar locations.

  15. Modelling the effects of tides and storm surges on coastal aquifers using a coupled surface-subsurface approach.

    PubMed

    Yang, Jie; Graf, Thomas; Herold, Maria; Ptak, Thomas

    2013-06-01

    Coastal aquifers are complex hydrologic systems because many physical processes interact: (i) variably saturated flow, (ii) spatial-temporal fluid density variations, (iii) tidal fluctuations, (iv) storm surges overtopping dykes, and (v) surface runoff of storm water. The HydroGeoSphere model is used to numerically simulate coastal flow dynamics, assuming a fully coupled surface-subsurface approach, accounting for all processes listed above. The diffusive wave approximation of the St. Venant equation is used to describe surface flow. Surface flow and salt transport are fully coupled with subsurficial variably saturated, variable-density flow and salt transport through mathematical terms that represent exchange of fluid mass and solute mass, respectively. Tides and storm surges induce a time-variant head that is applied to nodes of the surface domain. The approach is applied to real cases of tide and storm surge events. Tide simulation results confirm the existence of a recirculating zone, forming beneath the upper part of the intertidal zone. By monitoring the exchange fluid flux rates through the beach, it was found that the major inflow to the aquifer takes place at the upper part of the intertidal zone, which explains the formation of the recirculating zone. The recirculating zone is forming particularly during rising tide. Results from a storm surge simulation show that plume fingers develop below the flooded land surface. Natural remediation by seaward flowing freshwater is relatively slow, such that reducing the salt concentration in the aquifer down to drinking water standards takes up to 10 years.

  16. Co-Seismic Mass Dislocation and Its Effect on Earth's Rotation and Gravity

    NASA Technical Reports Server (NTRS)

    Chao, Benjamin F.

    1999-01-01

    Mantle processes often involve large-scale mass transport, ranging from mantle convection, tectonic motions, glacial isostatic adjustment, to tides, atmospheric and oceanic loadings, volcanism and seismicity. On very short time scale of less than an hour, co-seismic event, apart from the "shaking" that is the earthquake, leaves behind permanent (step-function-like) dislocations in the crust and mantle. This redistribution of mass changes the Earth's inertia tensor (and hence Earth's rotation in both length-of-day and polar motion), and the gravity field (in terms of spherical harmonic Stokes coefficients). The question is whether these effects are large enough to be of any significance. In this paper we report updated calculation results. The calculation uses the normal mode summation scheme, applied to 15,814 major earthquakes that occurred during 1976-1998, according to source mechanism solutions given by the Harvard Central Moment Tensor catalog. Compared to the truly large ones earlier in the century, the earthquakes we study are individually all too small to have left any discernible signature in geodetic records of Earth rotation or global gravity field. However, their collective effects continue to exhibit an extremely strong statistical tendencies. For example, earthquakes conspire to decrease J(sub 2) and J(sub 22) while shortening LOD, resulting in a rounder and more compact Earth. Strong tendency is also seen in the earthquakes trying to "nudge" the Earth rotation pole towards about 140 degree E, roughly opposite to the observed polar drift direction. The geophysical significance and implications will be further studied.

  17. Co-Seismic Mass Displacement and its Effect on Earth's Rotation and Gravity

    NASA Technical Reports Server (NTRS)

    Chao, B. F.; Gross, R. S.

    2004-01-01

    Mantle processes often involve large-scale mass transport, ranging from mantle convection, tectonic motions, glacial isostatic adjustment, to tides, atmospheric and oceanic loadings, volcanism and seismicity. On very short time scale of less than an hour, co-seismic event, apart from the "shaking" that is the earthquake, leaves behind permanent (step-function-like) displacements in the crust and mantle. This redistribution of mass changes the Earth's inertia tensor (and hence Earth's rotation in both length-of-day and polar motion), and the gravity field. The question is whether these effects are large enough to be of any significance. In this paper we report updated calculation results based on Chao & Gross. The calculation uses the normal mode summation scheme, applied to over twenty thousand major earthquakes that occurred during 1976-2002, according to source mechanism solutions given by the Harvard Centroid Moment Tensor catalog. Compared to the truly large ones earlier in the century, the earthquakes we study are individually all too small to have left any discernible signature in geodetic records of Earth rotation or global gravity field. However, their collective effects continue to exhibit an extremely strong statistical tendencies, conspiring to decrease J2 and J22 while shortening LOD, resulting in a rounder and more compact Earth. Strong tendency is also seen in the earthquakes trying to "nudge" the Earth rotation pole towards approx. 140 deg.E, roughly opposite to the observed polar drift direction. Currently, the Gravity Recovery And Climate Experiment (GRACE) is measuring the time-variable gravity to high degree and order with unprecedented accuracy. Our results show that great earthquakes such as the 1960 Chilean or 1964 Alaskan events cause gravitational field changes that are large enough to be detected by GRACE.

  18. Co-Seismic Mass Dislocation and its Effect on Earth's Rotation and Gravity

    NASA Technical Reports Server (NTRS)

    Chao, B. F.; Gross, R. S.

    2002-01-01

    Mantle processes often involve large-scale mass transport, ranging from mantle convection, tectonic motions, glacial isostatic adjustment, to tides, atmospheric and oceanic loadings, volcanism and seismicity. On very short time scale of less than an hour, co-seismic event, apart from the shaking that is the earthquake, leaves behind permanent (step-function-like) dislocations in the crust and mantle. This redistribution of mass changes the Earth's inertia tensor (and hence Earth's rotation in both length-of-day and polar motion), and the gravity field (in terms of spherical harmonic Stokes coefficients). The question is whether these effects are large enough to be of any significance. In this paper we report updated calculation results based on Chao & Gross (1987). The calculation uses the normal mode summation scheme, applied to nearly twenty thousand major earthquakes that occurred during 1976-2002, according to source mechanism solutions given by the Harvard Central Moment Tensor catalog. Compared to the truly large ones earlier in the century, the earthquakes we study are individually all too small to have left any discernible signature in geodetic records of Earth rotation or global gravity field. However, their collective effects continue to exhibit an extremely strong statistical tendencies. For example, earthquakes conspire to decrease J2 and J22 while shortening LOD, resulting in a rounder and more compact Earth. Strong tendency is also seen in the earthquakes trying to nudge the Earth rotation pole towards approximately 140 degrees E, roughly opposite to the observed polar drift direction. The geophysical significance and implications will be further studied.

  19. Mapping Hurricane Rita inland storm tide

    USGS Publications Warehouse

    Berenbrock, Charles; Mason, Jr., Robert R.; Blanchard, Stephen F.; Simonovic, Slobodan P.

    2009-01-01

    Flood-inundation data are most useful for decision makers when presented in the context of maps of effected communities and (or) areas. But because the data are scarce and rarely cover the full extent of the flooding, interpolation and extrapolation of the information are needed. Many geographic information systems (GIS) provide various interpolation tools, but these tools often ignore the effects of the topographic and hydraulic features that influence flooding. A barrier mapping method was developed to improve maps of storm tide produced by Hurricane Rita. Maps were developed for the maximum storm tide and at 3-hour intervals from midnight (0000 hour) through noon (1200 hour) on September 24, 2005. The improved maps depict storm-tide elevations and the extent of flooding. The extent of storm-tide inundation from the improved maximum storm-tide map was compared to the extent of flood-inundation from a map prepared by the Federal Emergency Management Agency (FEMA). The boundaries from these two maps generally compared quite well especially along the Calcasieu River. Also a cross-section profile that parallels the Louisiana coast was developed from the maximum storm-tide map and included FEMA high-water marks.

  20. Long-Period Tidal Variations of the Earth's Rotation Rate

    NASA Technical Reports Server (NTRS)

    Desai, S.; Gross, R.; Wahr, J.

    1999-01-01

    Long-period tidal variations of the Earth's rotation rate are caused by the redistribution of mass associated with the respective elastic solid Earth tides, the ocean tide heights, and the anelasticity of the Earth's mantle, and by the relative angular momentum associated with the long-period ocean tide currents.

  1. Waves: Internal Tides

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.

    1999-01-01

    Oceanic internal tides are internal waves with tidal periodicities. They are ubiquitous throughout the ocean, although generally more pronounced near large bathymetric features such as mid-ocean ridges and continental slopes. The internal vertical displacements associated with these waves can be extraordinarily large. Near some shelf breaks where the surface tides are strong, internal displacements (e.g., of an isothermal surface) can exceed 200 meters. Displacements of 10 meters in the open ocean are not uncommon. The associated current velocities are usually comparable to or larger than the currents of the surface tide. On continental shelves internal tides can occasionally generate packets of internal solitons, which are detectable in remote sensing imagery. Other common nonlinear features are generation of higher harmonics (e.g., 6-hr waves) and wave breaking. Internal tides are known to be an important energy source for mixing of shelf waters. Recent research suggests that they may also be a significant energy source for deep-ocean mixing.

  2. Mapping hurricane rita inland storm tide

    USGS Publications Warehouse

    Berenbrock, C.; Mason, R.R.; Blanchard, S.F.

    2009-01-01

    Flood-inundation data are most useful for decision makers when presented in the context of maps of affected communities and (or) areas. But because the data are scarce and rarely cover the full extent of the flooding, interpolation and extrapolation of the information are needed. Many geographic information systems provide various interpolation tools, but these tools often ignore the effects of the topographic and hydraulic features that influence flooding. A barrier mapping method was developed to improve maps of storm tide produced by Hurricane Rita. Maps were developed for the maximum storm tide and at 3-h intervals from midnight (00:00 hours) through noon (12:00 hours) on 24 September 2005. The improved maps depict storm-tide elevations and the extent of flooding. The extent of storm-tide inundation from the improved maximum storm-tide map was compared with the extent of flood inundation from a map prepared by the Federal Emergency Management Agency (FEMA). The boundaries from these two maps generally compared quite well especially along the Calcasieu River. Also a cross-section profile that parallels the Louisiana coast was developed from the maximum storm-tide map and included FEMA high-water marks. ?? 2009 Blackwell Publishing Ltd.

  3. Tides of global ice-covered oceans

    NASA Astrophysics Data System (ADS)

    Wunsch, Carl

    2016-08-01

    The tides of an ice-covered ocean are examined using a Cartesian representation of the elastic and fluid equations. Although unconstrained by any observations, the ocean tides of a Neoproterozoic "snowball" Earth could have been significantly larger than they are today. Time-mean tidal-residual circulations would then have been set up that are competitive with the circulation driven by geothermal heating. In any realistic configuration, the snowball Earth would have had an ice cover that is in the thin shell limit, but by permitting the ice thickness to become large, more interesting ice tidal response can be found, ones conceivably of application to bodies in the outer Solar System or hypothetical exoplanets. Little can be said concerning a reduction in tidal dissipation necessary to avoid a crisis in the history of the lunar orbit.

  4. Ocean science. Enhanced: internal tides and ocean mixing.

    PubMed

    Garrett, Chris

    2003-09-26

    Recent satellite and in situ observations have shown that at ocean ridges and other seafloor topographic features, a substantial amount of energy is transferred from the main ocean tides into "internal tides." In his Perspective, Garrett explains how these internal waves with tidal periods propagate through the density-stratified deep ocean and eventually break down into turbulence. The resulting mixing affects ocean stratification and ocean circulation. It thus influences climate as well as biological production. The energy for the internal tides is derived from the rotational energy of the Earth-Moon system changes of the length of the day and the distance to the Moon.

  5. Interactions between tides and other frequencies in the Indonesian seas

    NASA Astrophysics Data System (ADS)

    Robertson, Robin

    2011-01-01

    Interactions of tidal constituents and the transfer of energy from the tidal frequencies to other frequencies are investigated using 3-D tidal simulations for the Indonesian seas, focusing on an area of active internal tides. Semidiurnal tides strongly affect diurnal tides; however, semidiurnal tides are essentially unaffected by diurnal tides. The semidiurnal and diurnal constituents interact with each other through non-linear interference, both destructive and constructive. Semidiurnal tides generate harmonics at nearly the diurnal frequency and higher vertical wavenumbers. In Ombai Strait, these harmonics are out of phase with the diurnal tides and interact destructively with the diurnal tides, effectively negating the diurnal response in some locations. However, this is not a general response, and interactions differ between locations. Energy is also transferred from both semidiurnal and diurnal tides to other frequencies across the spectrum, with more energy originating from semidiurnal tides. These energy transfers are not homogeneous, and the spectral responses differ between the Makassar and Ombai Straits, with the region east of Ombai showing a more active surface response compared to a more intense benthic response in Makassar. In deep water away from topography, velocity spectra generally follow the Garrett-Munk (GM) relation. However, in areas of internal tide generation, spectral density levels exceed GM levels, particularly between 4 and 8 cycles per day (cpd), indicating increased non-linear interactions and energy transfer through resonant interactions. The model indicates strong surface trapping of internal tides, with surface velocity spectra having significantly higher energy between 4 and 8 cpd even 100 km away from the prominent sill generating the internal tides.

  6. Ocean Tide Loading Computation

    NASA Technical Reports Server (NTRS)

    Agnew, Duncan Carr

    2005-01-01

    September 15,2003 through May 15,2005 This grant funds the maintenance, updating, and distribution of programs for computing ocean tide loading, to enable the corrections for such loading to be more widely applied in space- geodetic and gravity measurements. These programs, developed under funding from the CDP and DOSE programs, incorporate the most recent global tidal models developed from Topex/Poscidon data, and also local tide models for regions around North America; the design of the algorithm and software makes it straightforward to combine local and global models.

  7. Modeling the Effects of Tropospheric Tides on the Ionosphere using SAMI3 Coupled with TIME-GCM

    NASA Astrophysics Data System (ADS)

    McDonald, S. E.; Huba, J.; Hagan, M. E.; Maute, A. I.; Basu, S.

    2009-12-01

    Recent modeling studies performed with the NCAR thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM) have shown that tides of tropospheric origin are capable of affecting the thermosphere and ionosphere and can explain the wave-four longitudinal structure that has been observed in the equatorial ionization anomaly (EIA). The eastward propagating zonal wavenumber-3 diurnal tide (DE3) has a particularly strong signature that peaks near 110 km and penetrates into the upper thermosphere. In this study, we couple the TIME-GCM thermosphere with NRL’s comprehensive 3D ionosphere model, SAMI3, in order to investigate the impact of non-migrating tides on the E- and F-region ionosphere. SAMI3 includes a potential equation to self-consistently solve for the electric field. Simulation runs have been performed for March equinox and June solstice conditions at solar minimum (F10.7 = 75.) The SAMI3 results are compared with TIME-GCM as well as with measurements of electron density and electric fields.

  8. Apparent Relations Between Solar Activity and Solar Tides Caused by the Planets

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    2007-01-01

    A solar storm is a storm of ions and electrons from the Sun. Large solar storms are usually preceded by solar flares, phenomena that can be characterized quantitatively from Earth. Twenty-five of the thirty-eight largest known solar flares were observed to start when one or more tide-producing planets (Mercury, Venus, Earth, and Jupiter) were either nearly above the event positions (less than 10 deg. longitude) or at the opposing side of the Sun. The probability for this to happen at random is 0.039 percent. This supports the hypothesis that the force or momentum balance (between the solar atmospheric pressure, the gravity field, and magnetic field) on plasma in the looping magnetic field lines in solar corona could be disturbed by tides, resulting in magnetic field reconnection, solar flares, and solar storms. Separately, from the daily position data of Venus, Earth, and Jupiter, an 11-year planet alignment cycle is observed to approximately match the sunspot cycle. This observation supports the hypothesis that the resonance and beat between the solar tide cycle and nontidal solar activity cycle influences the sunspot cycle and its varying magnitudes. The above relations between the unpredictable solar flares and the predictable solar tidal effects could be used and further developed to forecast the dangerous space weather and therefore reduce its destructive power against the humans in space and satellites controlling mobile phones and global positioning satellite (GPS) systems.

  9. Characterizing and minimizing the effects of noise in tide gauge time series: relative and geocentric sea level rise around Australia

    NASA Astrophysics Data System (ADS)

    Burgette, Reed J.; Watson, Christopher S.; Church, John A.; White, Neil J.; Tregoning, Paul; Coleman, Richard

    2013-08-01

    We quantify the rate of sea level rise around the Australian continent from an analysis of tide gauge and Global Positioning System (GPS) data sets. To estimate the underlying linear rates of sea level change in the presence of significant interannual and decadal variability (treated here as noise), we adopt and extend a novel network adjustment approach. We simultaneously estimate time-correlated noise as well as linear model parameters and realistic uncertainties from sea level time series at individual gauges, as well as from time-series differences computed between pairs of gauges. The noise content at individual gauges is consistent with a combination of white and time-correlated noise. We find that the noise in time series from the western coast of Australia is best described by a first-order Gauss-Markov model, whereas east coast stations generally exhibit lower levels of time-correlated noise that is better described by a power-law process. These findings suggest several decades of monthly tide gauge data are needed to reduce rate uncertainties to <0.5 mm yr-1 for undifferenced single site time series with typical noise characteristics. Our subsequent adjustment strategy exploits the more precise differential rates estimated from differenced time series from pairs of tide gauges to estimate rates among the network of 43 tide gauges that passed a stability analysis. We estimate relative sea level rates over three temporal windows (1900-2011, 1966-2011 and 1993-2011), accounting for covariance between time series. The resultant adjustment reduces the rate uncertainty across individual gauges, and partially mitigates the need for century-scale time series at all sites in the network. Our adjustment reveals a spatially coherent pattern of sea level rise around the coastline, with the highest rates in northern Australia. Over the time periods beginning in 1900, 1966 and 1993, we find weighted average rates of sea level rise of 1.4 ± 0.6, 1.7 ± 0.6 and 4.6 ± 0

  10. Stemming the Tide.

    ERIC Educational Resources Information Center

    Heller, Michele A.

    1994-01-01

    Hispanic Americans who fit stereotypical descriptions of illegal immigrants have become scapegoats under the rising tide of public and political pressure to crack down on illegal immigration. Provides examples of proposals to control illegal immigration and limit access to services. Summarizes studies and statistics used by both sides of the issue…

  11. Variation of the Earth tide-seismicity compliance parameter the last 50 years for the west site of the Aegean Volcanic Arc, Greece

    NASA Astrophysics Data System (ADS)

    Contadakis, M. E.; Arabelos, D. N.; Vergos, G.; Spatalas, S.

    2015-07-01

    Based on the results of our studies for the tidal triggering effect on the seismicity of the Hellenic area, we consider the confidence level of earthquake occurrence - tidal period accordance as an index of tectonic stress criticality for earthquake occurrence and we check if the recent increase in the seismic activity at the west site of the Aegean Volcanic Arc indicate faulting maturity for a stronger earthquake. In this paper we present the results of this test which are positive.

  12. Temperature tides determined with meteor radar

    NASA Astrophysics Data System (ADS)

    Hocking, W. K.; Hocking, A.

    2002-09-01

    A new analysis method for producing tidal temperature parameters using meteor radar measurements is presented, and is demonstrated with data from one polar and two mid-latitude sites. The technique further develops the temperature algorithm originally introduced by Hocking (1999). That earlier method was used to produce temperature measurements over time scales of days and months, but required an empirical model for the mean temperature gradient in the mesopause region. However, when tides are present, this temperature gradient is modulated by the presence of the tides, complicating extraction of diurnal variations. Nevertheless, if the vertical wavelengths of the tides are known from wind measurements, the effects of the gradient variations can be compensated for, permitting determination of temperature tidal amplitudes and phases by meteor techniques. The basic theory is described, and results from meteor radars at Resolute Bay (Canada), London (Canada) and Albuquerque (New Mexico, USA) are shown. Our results are compared with other lidar data, computer models, fundamental tidal theory and rocket data. Phase measurements at two mid-latitude sites (Albuquerque, New Mexico, and London, Canada) show times of maximum for the diurnal temperature tide to change modestly throughout most of the year, varying generally between 0 h and 6 h, with an excursion to 12 h in June at London. The semidiurnal tide shows a larger annual variation in time of maximum, being at 2 4 h in the winter months but increasing to 9 h during the late summer and early fall. We also find that, at least at mid-latitudes, the phase of the temperature tide matches closely the phase of the meridional tide, and theoretical justification for this statement is given. We also demonstrate that this is true using the Global Scale Wave Model (Hagan et al., 1999). Median values for the temperature amplitudes for each site are in the range 5 to 6 Kelvin. Results from a more northern site (Resolute Bay) show

  13. Precise Comparisons of Bottom-Pressure and Altimetric Ocean Tides

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.

    2013-01-01

    A new set of pelagic tide determinations is constructed from seafloor pressure measurements obtained at 151 sites in the deep ocean. To maximize precision of estimated tides, only stations with long time series are used; median time series length is 567 days. Geographical coverage is considerably improved by use of the international tsunami network, but coverage in the Indian Ocean and South Pacific is still weak. As a tool for assessing global ocean tide models, the data set is considerably more reliable than older data sets : the root-mean-square difference with a recent altimetric tide model is approximately 5 mm for the M2 constituent. Precision is sufficiently high to allow secondary effects in altimetric and bottom-pressure tide differences to be studied. The atmospheric tide in bottom pressure is clearly detected at the S1, S2, and T2 frequencies. The altimetric tide model is improved if satellite altimetry is corrected for crustal loading by the atmospheric tide. Models of the solid body tide can also be constrained. The free corenutation effect in the K1 Love number is easily detected, but the overall estimates are not as accurate as a recent determination with very long baseline interferometry.

  14. Polar Motion Constraints on Models of the Fortnightly Tide

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.; Egbert, G. D.; Smith, David E. (Technical Monitor)

    2002-01-01

    Estimates of the near-fortnightly Mf ocean tide from Topex/Poseidon satellite altimetry and from numerical solutions to the shallow water equations agree reasonably well, at least in their basin-scale features. For example, both show that the Pacific Ocean tide lags the Atlantic tide by roughly 30 degrees. There are hints of finer scale agreements in the elevation fields, but noise levels are high. In contrast, estimates of Mf currents are only weakly constrained by the TP data, because high-wavenumber Rossby waves (with intense currents) are associated with relatively small perturbations in surface elevation. As a result, a wide range of Mf current fields are consistent with both the TP data and the hydrodynamic equations within a priori plausible misfit bounds. We find that a useful constraint on the Mf currents is provided by independent estimates of the Earth's polar motion. At the Mf period polar motion shows a weak signal (both prograde and retrograde) which must be almost entirely caused by the ocean tide. We have estimated this signal from the SPACE2000 time series, after applying a broad-band correction for atmospheric angular momentum. Although the polar motion estimates have relatively large uncertainties, they are sufficiently precise to fix optimum data weights in a global ocean inverse model of Mf. These weights control the tradeoff between fitting a prior hydrodynamic model of Mf and fitting the relatively noisy T/P measurements of Mf. The predicted polar motion from the final inverse model agrees remarkably well with the Mf polar motion observations. The preferred model is also consistent with noise levels suggested by island gauges, and it is marginally consistent with differences observed by subsetting the altimetry (to the small extent that this is possible). In turn, this new model of the Mf ocean tide allows the ocean component to be removed from Mf estimates of length of day, thus yielding estimates of complex Love numbers less contaminated by

  15. Long-period perturbations in Starlette orbit and tide solution

    SciTech Connect

    Cheng, M.K.; Shum, C.K.; Eanes, R.J.; Schutz, B.E.; Tapley, B.D. )

    1990-06-10

    Continuous and dynamically consistent orbits have been computed using satellite laser ranging (SLR) data to Starlette for one-year period during 1976 and 1977 and the three-year period from 1983 through 1985. A low degree and order ocean tide solution, consisting of a total of 66 tidal parameters from 14 tidal constituents, was obtained in a combined solution using both the one-and three-year Starlette orbits. Yearly values for the second-degree annual tides, S{sub a}, which produce seasonal variations on the Starlette node, were obtained also. These variations were found to have year-to-year fluctuations of more than 25% about the mean value and produced significant long-period perturbations in the Starlette orbit. The Starlette tide solution is in good agreement with the Schwiderski tide solutions and with other satellite solutions, including multi-satellite tide solutions. The average uncertainties are approximately 0.1 cm for the estimated semidiurnal and diurnal tides and 0.4 cm for the long-period tides. The discrepancies of effective k{sub 2} inferred from the Starlette tide solution and other tide solutions are less than 0.01. The tide solutions were evaluated using orbit fits of a three-year LAGEOS and a one-year Starlette long arc. The results indicate that the Starlette tide solution produces significantly improved orbit fits for both LAGEOS and Starlette. The uncertainties for the estimated tide model coefficients were used to predict tidal errors for the LAGEOS orbit and were found to be consistent with the apparent tidal errors present in this orbit. The computed secular change in the Moon's mean motion due to tidal dissipation is {minus}24.8 {plus minus} 0.8 arc second/century{sup 2}, which is in good agreement with the results obtained from other investigations.

  16. Artificial tide generation and its effects on the water environment in the backwater of Three Gorges Reservoir

    NASA Astrophysics Data System (ADS)

    Sha, Yukun; Wei, Yongping; Li, Weipeng; Fan, Jihui; Cheng, Genwei

    2015-09-01

    Since the water impounding of the Three Gorges Reservoir (TGR) in 2003, the water stage in the backwater region increased from 65 m before water impounding to 145 m, and the velocity of the stream flow decreased significantly. The outflows of the tributaries that flow into TGR were also obstructed by the backwater. Stopping the stream flow prevented the pollutants from diffusing and transporting themselves into the water body, hence polluting the water in several tributaries. The authors proposed an artificial tide generation approach to solve this problem. The man-made flood peak in the downstream and the waves of the water stage in the upstream of the TGR can be produced by operating hydropower generators daily to deal with peak-and-bottom variations in the electricity demand. These waves will propagate upwards and form artificial tides in the backwater area. The water stage variation will intensify the flow exchange between the main stem and the tributaries as well as enhance the diffusion of pollutants, which will subsequently decrease the eutrophication of the water body in the outlet of branches as well as relieve the algal bloom problem in the region. The daily operations in the reservoir were simulated and tested by using the proposed hydrodynamic model of TGR. The hydropower operation for the peak load of electricity demand will produce artificial tides in the backwater area of TGR as well as increase the water stage variation from 0.30 m to 0.50 m within a day. This periodic fluctuation of water stage waves will intensify the water exchange between the main reach of Changjiang (Yangtze River) and its tributaries with an additional inflow or outflow of up to 300-500 m3/s, which is equivalent to the average discharge of these tributaries during the summer. The artificial tide generation can enhance the internal exchange of backwater as well as improve the water environment condition in the backwater area. This operation approach provides a new technology

  17. Earth tides, global heat flow, and tectonics

    USGS Publications Warehouse

    Shaw, H.R.

    1970-01-01

    The power of a heat engine ignited by tidal energy can account for geologically reasonable rates of average magma production and sea floor spreading. These rates control similarity of heat flux over continents and oceans because of an inverse relationship between respective depth intervals for mass transfer and consequent distributions of radiogenic heat production.

  18. Earth tides, global heat flow, and tectonics.

    PubMed

    Shaw, H R

    1970-05-29

    The power of a heat engine ignited by tidal energy can account for geologically reasonable rates of average magma production and sea floor spreading. These rates control similarity of heat flux over continents and oceans because of an inverse relationship between respective depth intervals for mass transfer and consequent distributions of radiogenic heat production.

  19. Effects of spraying rare earths on contents of rare Earth elements and effective components in tea.

    PubMed

    Wang, Dongfeng; Wang, Changhong; Ye, Sheng; Qi, Hongtao; Zhao, Guiwen

    2003-11-05

    Rare earth (RE) fertilizer is widely applied in China to increase the yield and the quality of crops including tea. However, the effects of spraying RE fertilizer on the contents of rare earth elements (REE) and effective components in tea are unknown. The results from basin and field experiments show that the values of the REE concentrations in new shoots of tea plants and the concentration of REE in the soil (REE/REEs) either from control basins or from treatment basins were smaller than those in other parts of tea plant and similar between control and treatment. The longer the interval between spraying RE fertilizer and picking the shoots of tea plants, the less the effects from spraying. About 80% summation operator REE (the sum of the concentrations of 15 REE) in tea, whether it came from spraying or not, was insoluble in the infusion. About 10% the soluble REE of summation operator REE in tea infusion was bound to polysaccharide, and the amount of REE bound polysaccharide decreased over time. At least a 25 day safety interval is needed between spraying and picking if the microelement fertilizer is used, in order to enhance tea output and to ensure tea safety.

  20. Investigating earthquake cycle vertical deformation recorded by GPS and regional tide gauge stations in California

    NASA Astrophysics Data System (ADS)

    Hardy, S.; Konter, B.

    2013-12-01

    Geodetic and tide gauge measurements of vertical deformation record localized zones of uplift and subsidence that may document critical components of both long and short-period earthquake cycle deformation. In this study, we compare vertical tide gauge data from the Permanent Service for Mean Sea Level (PSMSL) and vertical GPS data from the EarthScope Plate Boundary Observatory (PBO) for 10 approximately co-located station pairs along coastal California from Point Reyes, CA to Ensenada, Mexico. To compare these two datasets, we first truncate both datasets so that they span a common time frame for all stations (2007 - 2012). PSMSL data are treated for both average global sea level rise (~1.8 mm/yr) and global isostatic adjustment. We then calculate a 2-month running mean for tide gauge and a 1-month running mean for GPS datasets to smooth out daily oceanographic or anthropologic disturbances but maintain the overall trend of each dataset. As major ocean-climate signals, such as El Nino, are considered regional features of the Pacific Ocean and likely common to all California tide gauge stations, we subtract a reference sea level record (San Francisco station) from all other stations to eliminate this signal. The GPS and tide gauge data show varying degrees of correlation spanning both 3-month and 4-year time-scales. We infer that the slope of vertical displacements are largely controlled by interseismic motions, however displacements from major earthquakes are evident and are required to explain some of the unique signatures in the tide gauge and GPS data. Specifically, we find that stations from both datasets in Southern California show an anomalous trend since the 2010 Baja California earthquake. To further investigate this trend and others, we compare these data to vertical motions estimated by a suite of 3-D viscoelastic earthquake cycle deformation models. Long-term tide gauge time series are well simulated by the models, but short-term time series are not as

  1. Effects of the tidal mass redistribution on the Earth rotation

    NASA Astrophysics Data System (ADS)

    Baenas, T.; Ferrándiz, J.; Escapa, A.; Getino, J.

    2015-08-01

    The effects of the tidal mass redistributions on the Earth precession and nutations are revisited, under various hypothesis on the elastic response of the Earth and using the Hamiltonian approach. New non-negligible secular and periodic contributions have been found.

  2. Fluctuations in tides and geomagnetic variations

    NASA Astrophysics Data System (ADS)

    Kohsiek, A.; Kiefer, M.; Meek, C. E.; Manson, A. H.

    Middle atmosphere tidal winds and the daily geomagnetic Sq-variation show a day-to-day variability, both with a local behaviour. Due to the main cause of the Sq-variation, the ionospheric dynamo effect, day-to-day fluctuation of Sq could be raised by fluctuations in tides. This coupling of fluctuations is investigated with radar wind data measured at Saskatoon at around 100 km height and with magnetic data from four observatories in the vicinity of the radar. We show that our definition of fluctuations exhibits properties of atmospheric tides in the winds and that the magnetic data can be assumed to represent a local behaviour. We find that there are some significant correlations between fluctuations in winds and magnetic variations. Apparently the local fluctuation of geomagnetic variations is weakly coupled not only to the fluctuations of the semidiurnal tides but also to those of the mean winds.

  3. Effects of river discharge and high-tide stage on salinity intrusion in the Weeki Wachee, Crystal, and Withlacoochee River estuaries, southwest Florida

    USGS Publications Warehouse

    Yobbi, D.K.; Knochenmus, L.A.

    1989-01-01

    The Weeki Wachee, Crystal, and Withlacoochee Rivers are coastal streams flowing into the Gulf of Mexico that may be affected by either future surface water or groundwater withdrawals. Reduction of river discharge will affect the upstream extent of saltwater intrusion in the rivers; however, under certain reduced low-flow discharges, the estimated change in upstream extent of saltwater intrusion is on the order of several tenths of a mile and frequently is within the range of predicted error. Data on flow, tides, and salinity describe the physical characteristics of the Weeki Wachee, Crystal, and Withlacoochee River systems. Vertical and longitudinal salinity profiles indicate that salinity of the rivers increases downstream and varies substantially at any given location. The Weeki Wachee River system is the best mixed of the three. The Crystal River system exhibited the next best mixed system, and the Withlacoochee River system exhibited the most variation in its salinity regime. The daily maximum upstream extent of salinity intrusion is described by multiple linear-regression analysis based on daily mean streamflow of each river and high-tide stage of the gulf. The equations are used to show the effects of discharge on the daily maximum upstream extent of salinity intrusion in the rivers. (USGS)

  4. GPS estimates of ocean tide loading in NW-France: determination of ocean tide loading constituents and comparison with a recent ocean tide model

    NASA Astrophysics Data System (ADS)

    Vergnolle, M.; Bouin, M.-N.; Morel, L.; Masson, F.; Durand, S.; Nicolas, J.; Melachroinos, S. A.

    2008-05-01

    Ocean loading effects cause 3-D displacements large enough to affect space geodesy measurements either at the subdiurnal periods or at longer time scales by the means of spurious signals. GPS measurements, in turn, could provide local improvements of the models in coastal areas if their ability to precisely monitor such rapid displacements is assessed. In this paper, we use 105 days of continuous GPS measurements collected in 2004 in the French Brittany and Cotentin region to investigate: (1) the precision achieved by the GPS analysis on measuring 3-D subdiurnal displacements and amplitude and phase of the tidal constituents, (2) the quality of the most recent ocean tide model FES2004 in such a complex coastal context. Indeed, in this area, tide amplitudes are among the largest in the world (up to 16 cm of loading displacements on the vertical component) and are believed to show strong shallow-water tides. From a state of the art GPS analysis using the scientific GAMIT software over 2-h sessions, we test two independent strategies for the realization of the reference frame. The position time series are then compared with the displacements predicted by the FES2004 model applied on an elastic Earth model. The two sets of results are consistent with each other at the same level of agreement than with the predicted displacements, namely 3-5 mm on the horizontal components, 10 mm on the vertical. This assesses the capability of this technique for measuring 3-D ocean tide loading deformation. We validate the FES2004 model in the Brittany area, even though it slightly (2-7 mm) underestimates the three components amplitudes. With a harmonic analysis of the observed position time series, we obtain nevertheless an agreement at a submillimetre level for the M2, N2, O1, Q1 tidal constituents and at a millimetre level for the K1 and S2 tidal constituents. Moreover, we can extract a significant M4 load signal at the 95 per cent confidence level from the GPS time series at the

  5. Collaborative Project. Understanding the effects of tides and eddies on the ocean dynamics, sea ice cover and decadal/centennial climate prediction using the Regional Arctic Climate Model (RACM)

    SciTech Connect

    Hutchings, Jennifer; Joseph, Renu

    2013-09-14

    The goal of this project is to develop an eddy resolving ocean model (POP) with tides coupled to a sea ice model (CICE) within the Regional Arctic System Model (RASM) to investigate the importance of ocean tides and mesoscale eddies in arctic climate simulations and quantify biases associated with these processes and how their relative contribution may improve decadal to centennial arctic climate predictions. Ocean, sea ice and coupled arctic climate response to these small scale processes will be evaluated with regard to their influence on mass, momentum and property exchange between oceans, shelf-basin, ice-ocean, and ocean-atmosphere. The project will facilitate the future routine inclusion of polar tides and eddies in Earth System Models when computing power allows. As such, the proposed research addresses the science in support of the BER’s Climate and Environmental Sciences Division Long Term Measure as it will improve the ocean and sea ice model components as well as the fully coupled RASM and Community Earth System Model (CESM) and it will make them more accurate and computationally efficient.

  6. Minutes of TOPEX/POSEIDON Science Working Team Meeting and Ocean Tides Workshop

    NASA Technical Reports Server (NTRS)

    Fu, Lee-Lueng (Editor)

    1995-01-01

    This third TOPEX/POSEIDON Science Working Team meeting was held on December 4, 1994 to review progress in defining ocean tide models, precision Earth orbits, and various science algorithms. A related workshop on ocean tides convened to select the best models to be used by scientists in the Geophysical Data Records.

  7. Tides of the Caribbean Sea

    SciTech Connect

    Kjerfve, B.

    1981-05-20

    Analysis of tidal characteristics from 45 gauge locations indicates that the Caribbean Sea has a microtidal range, for the most part between 10 and 20 cm. The tide is primarily either mixed semidiurnal or mixed diurnal but a substantial section from Puerto Rico to Venezuela experiences diurnal tides. Empirical charts of six component tides (M/sub 2/, S/sub 2/, N/sub 2/, K/sub 1/, O/sub 1/, and P/sub 1/) show local detail of phase and amplitude. Each of the semidiurnal component tides is characterized by anticlockwise rotating amphidromes centered in the eastern Caribbean. There is evidence of strong radiational forcing of the S/sub 2/ tide in the south-western Caribbean. The diurnal component tides are largely uniform in both phase and amplitude for most of the western and central Caribbean. However, the diurnal phases increase rapidly towards the northwest and the Yucatan Channel.

  8. Impact of sea level rise on tide gate function.

    PubMed

    Walsh, Sean; Miskewitz, Robert

    2013-01-01

    Sea level rise resulting from climate change and land subsidence is expected to severely impact the duration and associated damage resulting from flooding events in tidal communities. These communities must continuously invest resources for the maintenance of existing structures and installation of new flood prevention infrastructure. Tide gates are a common flood prevention structure for low-lying communities in the tidal zone. Tide gates close during incoming tides to prevent inundation from downstream water propagating inland and open during outgoing tides to drain upland areas. Higher downstream mean sea level elevations reduce the effectiveness of tide gates by impacting the hydraulics of the system. This project developed a HEC-RAS and HEC-HMS model of an existing tide gate structure and its upland drainage area in the New Jersey Meadowlands to simulate the impact of rising mean sea level elevations on the tide gate's ability to prevent upstream flooding. Model predictions indicate that sea level rise will reduce the tide gate effectiveness resulting in longer lasting and deeper flood events. The results indicate that there is a critical point in the sea level elevation for this local area, beyond which flooding scenarios become dramatically worse and would have a significantly negative impact on the standard of living and ability to do business in one of the most densely populated areas of America.

  9. Earth matter effects in detection of supernova neutrinos

    NASA Astrophysics Data System (ADS)

    Guo, X.-H.; Young, Bing-Lin

    2006-05-01

    We calculated the matter effect, including both the Earth and supernova, on the detection of neutrinos from type II supernovae at the proposed Daya Bay reactor neutrino experiment. It is found that apart from the dependence on the flip probability PH inside the supernova and the mass hierarchy of neutrinos, the amount of the Earth matter effect depends on the direction of the incoming supernova neutrinos, and reaches the biggest value when the incident angle of neutrinos is around 93°. In the reaction channel ν¯e+p→e++n the Earth matter effect can be as big as about 12%. For other detection processes the amount of the Earth matter effect is a few per cent.

  10. Earth matter effects in detection of supernova neutrinos

    SciTech Connect

    Guo, X.-H.; Young Binglin

    2006-05-01

    We calculated the matter effect, including both the Earth and supernova, on the detection of neutrinos from type II supernovae at the proposed Daya Bay reactor neutrino experiment. It is found that apart from the dependence on the flip probability P{sub H} inside the supernova and the mass hierarchy of neutrinos, the amount of the Earth matter effect depends on the direction of the incoming supernova neutrinos, and reaches the biggest value when the incident angle of neutrinos is around 93 deg. In the reaction channel {nu}{sub e}+p{yields}e{sup +}+n the Earth matter effect can be as big as about 12%. For other detection processes the amount of the Earth matter effect is a few per cent.

  11. Mesospheric and thermospheric tides

    NASA Astrophysics Data System (ADS)

    Forbes, J. M.

    1980-08-01

    Recent calculations of atmospheric solar tides in the mesosphere and thermosphere are reviewed. The numerical models considered consist of a full three-dimensional solution of the tidal equations in a rotating viscous spherical atmosphere (Forbes and Garret 1976, 1978), and an approximate solution for some modes given by an equivalent gravity wave on a rotating plane (Forbes and Hagan 1979, 1980). Both models take into account eddy and molecular diffusion of heating and momentum, rotation, and hydromagnetic coupling, and use new calculations of thermal forcing by insolation absorption due to H2O and O3 below 70 km.

  12. Orthogonal stack of global tide gauge sea level data

    NASA Technical Reports Server (NTRS)

    Trupin, A.; Wahr, J.

    1990-01-01

    Yearly and monthly tide gauge sea level data from around the globe are fitted to numerically generated equilibrium tidal data to search for the 18.6 year lunar tide and 14 month pole tide. Both tides are clearly evident in the results, and their amplitudes and phases are found to be consistent with a global equilibrium response. Global, monthly sea level data from outside the Baltic sea and Gulf of Bothnia are fitted to global atmospheric pressure data to study the response of the ocean to pressure fluctuations. The response is found to be inverted barometer at periods greater than two months. Global averages of tide gauge data, after correcting for the effects of post glacial rebound on individual station records, reveal an increase in sea level over the last 80 years of between 1.1 mm/yr and 1.9 mm/yr.

  13. Detecting the red tide based on remote sensing data in optically complex East China Sea

    NASA Astrophysics Data System (ADS)

    Xu, Xiaohui; Pan, Delu; Mao, Zhihua; Tao, Bangyi; Liu, Qiong

    2012-09-01

    Red tide not only destroys marine fishery production, deteriorates the marine environment, affects coastal tourist industry, but also causes human poison, even death by eating toxic seafood contaminated by red tide organisms. Remote sensing technology has the characteristics of large-scale, synchronized, rapid monitoring, so it is one of the most important and most effective means of red tide monitoring. This paper selects the high frequency red tides areas of the East China Sea as study area, MODIS/Aqua L2 data as the data source, analysis and compares the spectral differences in the red tide water bodies and non-red tide water bodies of many historical events. Based on the spectral differences, this paper develops the algorithm of Rrs555/Rrs488> 1.5 to extract the red tide information. Apply the algorithm on red tide event happened in the East China Sea on May 28, 2009 to extract the information of red tide, and found that the method can determine effectively the location of the occurrence of red tide; there is a good corresponding relationship between red tide extraction result and chlorophyll a concentration extracted by remote sensing, shows that these algorithm can determine effectively the location and extract the red tide information.

  14. Numerical Simulation of Oregon Inlet Control Structures’ Effects on Storm and Tide Elevations in Pamlico Sound.

    DTIC Science & Technology

    1984-04-01

    Engineer Waterways Experiment Station (WES) ( Corson , Resio, and Vincent 1980; Resio, Vincent, and Corson 1982). WIS data are referenced to an earth...Waterways Experiment Station (WES) ( Corson , Resio, and Vincent 1980; Resio, Vincent, and Corson 1982). WIS data are referenced to an earth-coordinate...Meteorological data for the March 1962 storm were obtained from a data base constructed for the WIS project at WES (Resio, Vincent, and Corson 1982

  15. Lunar and Solar Torques on the Oceanic Tides

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.; Bills, Bruce G.; Chao, Benjamin Fong

    1998-01-01

    A general framework for calculating lunar and solar torques on the oceanic tides is developed in terms of harmonic constituents. Axial torques and their associated angular momentum and earth-rotation variations are deduced from recent satellite-altimeter and satellite-tracking tide solutions. Torques on the prograde components of the tide produce the familiar secular braking of the rotation rate. The estimated secular acceleration is approximately -1300 sec/century(sup 2) (less 4% after including atmospheric tides); the implied rate of change in the length of day is 2.28 milliseconds/century. Torques on the retrograde components of the tide produce periodic rotation variations at twice the tidal frequency. Interaction torques, e.g. solar torques on lunar tides, generate a large suite of rotation-rate variations at sums and differences of the original tidal frequencies. These are estimated for periods from 18.6 years to quarter-diurnal. At subdaily periods the angular momentum variations are 5 to 6 orders of magnitude smaller than the variations caused by ocean tidal currents.

  16. How much do tides affect the circulation of the Mediterranean Sea? From local processes in the Strait of Gibraltar to basin-scale effects

    NASA Astrophysics Data System (ADS)

    Naranjo, C.; Garcia-Lafuente, J.; Sannino, G.; Sanchez-Garrido, J. C.

    2014-09-01

    The effects of tidal forcing on the exchange flow through the Strait of Gibraltar and the circulation in the near-field region are revisited with a regional numerical model. Also a basin-scale model run is conducted in a first attempt to assess the impact of these local processes on the Western Mediterranean thermohaline circulation. In the Strait of Gibraltar, tides are found to (1) increase the exchange flow volume transport, (2) modify the hydrological properties of Atlantic inflowing waters through the enhancement of mixing, and (3) facilitate the drainage of Mediterranean deep water. In the far-field, the model reveals that these local processes can favor deep convection in the Gulf of Lion. Some thoughts are provided offering possible explanations.

  17. Understanding the variability of an extreme storm tide along a coastline

    NASA Astrophysics Data System (ADS)

    Lewis, M.; Schumann, G.; Bates, P.; Horsburgh, K.

    2013-05-01

    Correctly determining the peak storm tide height along the coastline, and expressing the associated natural variability, is essential for a robust prediction of coastal flood risk. A new approach is proposed that calculates a storm tide relationship (relative to a tide gauge) by using a storm surge model to describe the natural spatial variability based on the features of a large number of very high storm tides. Two historic flood events (1953 and 2007) were used to validate this characteristics approach along the East Anglia coastline (U.K.), and predicted water-levels were found to be in good agreement with tide gauge observations (Root Mean Squared Error of 36 cm), especially when compared to the method of assuming a storm tide of constant return period (Root Mean Squared Error of 59 cm). Detailed observations of storm tide height between tide gauge locations are rare; therefore, Synthetic Aperture Radar (SAR) was employed to calculate the LiDAR geo-referenced storm tide height along the North Somerset coastline of the Bristol Channel (U.K.). Two SAR observed "extreme" storm tide events were used to validate the characteristics approach between tide gauges (Root Mean Squared Error of 1.2 m and 0.7 m), and indicated the presence of localised wave effects to the observed storm tide height that could have a significant effect to flood risk estimates.

  18. FULLY COMPRESSIVE TIDES IN GALAXY MERGERS

    SciTech Connect

    Renaud, F.; Boily, C. M.; Naab, T.; Theis, Ch.

    2009-11-20

    The disruptive effect of galactic tides is a textbook example of gravitational dynamics. However, depending on the shape of the potential, tides can also become fully compressive. When that is the case, they might trigger or strengthen the formation of galactic substructures (star clusters and tidal dwarf galaxies), instead of destroying them. We perform N-body simulations of interacting galaxies to quantify this effect. We demonstrate that tidal compression occurs repeatedly during a galaxy merger, independently of the specific choice of parameterization. With a model tailored to the Antennae galaxies, we show that the distribution of compressive tides matches the locations and timescales of observed substructures. After extending our study to a broad range of parameters, we conclude that neither the importance of the compressive tides (approx15% of the stellar mass) nor their duration (approx10{sup 7} yr) is strongly affected by changes in the progenitors' configurations and orbits. Moreover, we show that individual clumps of matter can enter compressive regions several times in the course of a simulation. We speculate that this may spawn multiple star formation episodes in some star clusters, through, e.g., enhanced gas retention.

  19. Effect of tides, river flow, and gate operations on entrainment of juvenile salmon into the interior Sacramento–San Joaquin River Delta

    USGS Publications Warehouse

    Perry, Russell W.; Brandes, Patricia L.; Burau, Jon R.; Sandstrom, Philip T.; Skalski, John R.

    2015-01-01

    Juvenile Chinook Salmon Oncorhynchus tshawytscha emigrating from natal tributaries of the Sacramento River, California, must negotiate the Sacramento-San Joaquin River Delta (hereafter, the Delta), a complex network of natural and man-made channels linking the Sacramento River with San Francisco Bay. Fish that enter the interior and southern Delta—the region to the south of the Sacramento River where water pumping stations are located—survive at a lower rate than fish that use alternative migration routes. Consequently, total survival decreases as the fraction of the population entering the interior Delta increases, thus spurring management actions to reduce the proportion of fish that are entrained into the interior Delta. To better inform management actions, we modeled entrainment probability as a function of hydrodynamic variables. We fitted alternative entrainment models to telemetry data that identified when tagged fish in the Sacramento River entered two river channels leading to the interior Delta (Georgiana Slough and the gated Delta Cross Channel). We found that the probability of entrainment into the interior Delta through both channels depended strongly on the river flow and tidal stage at the time of fish arrival at the river junction. Fish that arrived during ebb tides had a low entrainment probability, whereas fish that arrived during flood tides (i.e., when the river's flow was reversed) had a high probability of entering the interior Delta. We coupled our entrainment model with a flow simulation model to evaluate the effect of nighttime closures of the Delta Cross Channel gates on the daily probability of fish entrainment into the interior Delta. Relative to 24-h gate closures, nighttime closures increased daily entrainment probability by 3 percentage points on average if fish arrived at the river junction uniformly throughout the day and by only 1.3 percentage points if 85% of fish arrived at night. We illustrate how our model can be used to

  20. Effects of Earth Encounters on the Rotational Properties of Near-Earth Objects

    NASA Astrophysics Data System (ADS)

    Chit Siu, Ho; Keane, James T.; Moskovitz, Nicholas; Binzel, Richard P.

    2015-11-01

    The effects of Earth encounters on the physical properties of near-Earth objects (NEOs) have been shown to be significant factors in their evolution. Previous studies have examined the effects of these encounters on reflectance spectra, and effects such as spin state and shape changes have been studied for specific asteroids and through simulation. In this study, archive data from previous NEO surveys were used to investigate rotational frequencies as a function of minimum orbit intersection distance (MOID), which we use as a proxy for Earth encounter likelihood.When comparing objects of similar sizes, we find a highly significant difference in the dispersion of rotational frequency (p < 0.01; significant at a >99% confidence level) between NEO populations that were likely to have had an Earth encounter and those that are less likely to have had such an encounter. The encounter/non-encounter distinction is found at a dividing MOID value of 1 lunar distance (LD). These results were robust to changes in the size of the moving average window, as well as to removal of the smallest objects from the encounter population and the largest objects from the non-encounter population, which would be most strongly affected by a known size/spin period bias where smaller objects tend to have shorter periods. There was no statistically significant difference in the mean rotation rates of encounter and non-encounter objects, however, indicating that encounters cause greater dispersion, but do not preferentially spin objects up or down at a detectable level. Recent modeling work also lends credibility to the idea that NEO interactions with the Earth-Moon system as a whole may be leading to the dispersion difference boundary at 1 LD (Keane et al. 2015, DPS).

  1. Forecasting Tides in Global HYCOM

    DTIC Science & Technology

    2013-05-01

    ocean tides significantly impact the deep ocean tides. Blocking the Sea of Okhotsk creates differences in the tidal amplitudes over much of the...increasing the skill. Unfortunately, we can’t use this approach in the baroclinic global model with sea ice. Tidal resonances represent a challenge for

  2. King Tides and Climate Change

    EPA Pesticide Factsheets

    The highest predicted high tide of the year at a coastal location can bring unusually high water levels and can cause flooding. Learn about these tides including what they are, when they occur, and what they can mean for the future.

  3. Lunar and Solar Torques on the Oceanic Tides

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.; Bills, Bruce G.; Chao, Benjamin F.

    1998-01-01

    Brosche and Seiler recently suggested that direct lunar and solar tidal torques on the oceanic tides play a significant role in the earth's short-period angular momentum balance ("short-period" here meaning daily and sub-daily). We reexamine that suggestion here, concentrating on axial torques and hence on variations in rotation rate. Only those spherical harmonic components of the ocean tide having the same degree and order as the tidal potential induce nonzero torques. Prograde components (those moving in the same direction as the tide-generating body) produce the familiar secular braking of the earth's rotation. Retrograde components, however, produce rapid variations in UTI at twice the tidal frequency. There also exist interaction torques between tidal constituents, e.g. solar torques on lunar tides. They generate UTI variations at frequencies equal to the sums and differences of the original tidal frequencies. We give estimates of the torques and angular momentum variations for each of the important regimes, secular to quarter-diurnal. For the M(sub 2) potential acting on the M(sub 2) ocean tide, we find an associated angular momentum variation of amplitude 3 x 10(exp 19) N m. This is 5 to 6 orders of magnitude smaller than the angular momentum variations associated with tidal currents. We conclude that these torques do not play a significant role in the short-period angular momentum balance.

  4. The effects of nitrogen, phosphorus, vitamins and trace metals on the growth of the red tide organism Prorocentrum Micans

    NASA Astrophysics Data System (ADS)

    Wang, Zheng-Fang; Zhang, Qing; Gong, Min

    1995-12-01

    Laboratory culture experiments showed that <100μ mol/L nitrate, amonium or mixture of amino acids promote the growth of the red tide organism Prorocentrum micans Ehrenb, but that >100μmol/L of ammonium, or mixture of glycine and glutamate was harmful to growth, and that orthophosphate was P. micans’ main phosphorous source in the ocean. Presence of 80μ mol/L EDTA, 0.5 to 1 μmol/L Fe3+, 1.0 to 20.0 μ mol/L Mn2+ 0.1 to 0.4 μmol/L Co2+ in the culture medium could improve the growth of P. micans. Vitamin B1 promoted growth, but vitamin B12 and biotin did not. The estimated minimum cell quotas ( q o) for nitrogen and phosphorus being 0.74 pmole/cell and 0.045 pmole/cell show that phosphorus (more than nitrogen) limits the growth of P. micans in the study area.

  5. [Illumination's effect on the growth and nitrate reductase activity of typical red-tide algae in the East China Sea].

    PubMed

    Li, Hong-mei; Shi, Xiao-yong; Ding, Yan-yan; Tang, Hong-jie

    2013-09-01

    Two typical red-tide algae, Skeletonema costatum and Prorocentrum donghaiense were selected as studied objects. The nitrate reductase activity (NRA) and the growth of the two algae under different illuminations through incubation experiment were studied. The illumination condition was consistent with in situ. Results showed that P. donghaiense and S. costatum could grow normally in the solar radiation ranged from 30-60 W x m(-2), and the growth curve was "S" type. However, when solar radiation was below 9 W x m(-2), the two alga could hardly grow. In the range of 0-60 W x m(-2), three parameters (NRAmax, micro(max), Bf) increased with the increasing of light intensity, indicating that the light intensity can influence the grow of alga indirectly through influencing the nitrate reductase activity. The micro(max) and NRAmax in unite volume of Skeletonema costatum were higher than those of Prorocentrum donghaiense, indicating that Skeletonema costatum can better utilize the nitrate than Prorocentrum donghaiense.

  6. Turning the tide: effects of river inflow and tidal amplitude on sandy estuaries in laboratory landscape experiments

    NASA Astrophysics Data System (ADS)

    Kleinhans, Maarten; Braat, Lisanne; Leuven, Jasper; Baar, Anne; van der Vegt, Maarten; van Maarseveen, Marcel; Markies, Henk; Roosendaal, Chris; van Eijk, Arjan

    2016-04-01

    Many estuaries formed over the Holocene through a combination of fluvial and coastal influxes, but how estuary planform shape and size depend on tides, wave climate and river influxes remains unclear. Here we use a novel tidal flume setup of 20 m length by 3 m width, the Metronome (http://www.uu.nl/metronome), to create estuaries and explore a parameter space for the simple initial condition of a straight river in sandy substrate. Tidal currents capable of transporting sediment in both the ebb and flood phase because they are caused by periodic tilting of the flume rather than the classic method of water level fluctuation. Particle imaging velocimetry and a 1D shallow flow model demonstrate that this principle leads to similar sediment mobility as in nature. Ten landscape experiments recorded by timelapse overhead imaging and AGIsoft DEMs of the final bed elevation show that absence of river inflow leads to short tidal basins whereas even a minor discharge leads to long convergent estuaries. Estuary width and length as well as morphological time scale over thousands of tidal cycles strongly depend on tidal current amplitude. Paddle-generated waves subdue the ebb delta causing stronger tidal currents in the basin. Bar length-width ratios in estuaries are slightly larger to those in braided rivers in experiments and nature. Mutually evasive ebb- and flood-dominated channels are ubiquitous and appear to be formed by an instability mechanism with growing bar and bifurcation asymmetry. Future experiments will include mud flats and live vegetation.

  7. Effects of three macroalgae, Ulva linza (Chlorophyta), Corallina pilulifera (Rhodophyta) and Sargassum thunbergii (Phaeophyta) on the growth of the red tide microalga Prorocentrum donghaiense under laboratory conditions

    NASA Astrophysics Data System (ADS)

    Wang, Renjun; Xiao, Hui; Wang, You; Zhou, Wenli; Tang, Xuexi

    2007-10-01

    Allelopathic effects of several concentrations of fresh tissue and dry powder of three macroalgae, Ulva linza, Corallina pilulifera and Sargassum thunbergii, on the red tide microalga Prorocentrum donghaiense were evaluated in microcosms. Preliminary studies on the algicidal effects of one aqueous and four organic solvent extracts from the macroalgae on the microalga were carried out to confirm the existence of allelochemicals in the tissues of the macroalgae. The effects of macroalgal culture medium filtrate on P. donghaiense were investigated using initial or semi-continuous filtrate addition. Furthermore, the potential effects of the microalga on these three macroalgae were also tested. The results of the microcosm assay showed that the growth of P. donghaiense was strongly inhibited by using fresh tissues and dry powder of the three macroalgae. Both aqueous and methanol extracts of the macroalgae had strong growth inhibitory effects on P. donghaiense, while the other three organic solvent extracts (acetone, ether and chloroform) had no apparent effect on its growth; this suggested that the allelochemicals from these three macroalga had relatively high polarities. The three macroalgal culture medium filtrates exhibited apparent growth inhibitory effect on the microalgae under initial or semi-continuous addition, which suggested that the cells of P. donghaiense are sensitive to the allelochemicals. In contrast, P. donghaiense had no apparent effect on the growth of the macroalgae in coexistence experiment.

  8. Effects of currents and tides on fine-scale use of marine bird habitats in a Southeast Alaska hotspot

    USGS Publications Warehouse

    Drew, Gary S.; Piatt, John F.; Hill, David J.

    2013-01-01

    Areas with high species richness have become focal points in the establishment of marine protected areas, but an understanding of the factors that support this diversity is still incomplete. In coastal areas, tidal currents—modulated by bathymetry and manifested in variable speeds—are a dominant physical feature of the environment. However, difficulties resolving tidally affected currents and depths at fine spatial-temporal scales have limited our ability to understand their influence the distribution of marine birds. We used a hydrographic model of the water mass in Glacier Bay, Alaska to link depths and current velocities with the locations of 15 common marine bird species observed during fine-scale boat-based surveys of the bay conducted during June of four consecutive years (2000-2003). Marine birds that forage on the bottom tended to occupy shallow habitats with slow-moving currents; mid-water foragers used habitats with intermediate depths and current speeds; and surface-foraging species tended to use habitats with fast-moving, deep waters. Within foraging groups there was variability among species in their use of habitats. While species obligated to foraging near bottom were constrained to use similar types of habitat, species in the mid-water foraging group were associated with a wider range of marine habitat characteristics. Species also showed varying levels of site use depending on tide stage. The dramatic variability in bottom topography—especially the presence of numerous sills, islands, headlands and channels—and large tidal ranges in Glacier Bay create a wide range of current-affected fine-scale foraging habitats that may contribute to the high diversity of marine bird species found there.

  9. Gastrointestinal Emergency Room Admissions and Florida Red Tide Blooms.

    PubMed

    Kirkpatrick, Barbara; Bean, Judy A; Fleming, Lora E; Kirkpatrick, Gary; Grief, Lynne; Nierenberg, Kate; Reich, Andrew; Watkins, Sharon; Naar, Jerome

    2010-01-01

    Human exposure to brevetoxins during Florida red tide blooms formed by Karenia brevis has been documented to cause acute gastrointestinal, neurologic, and respiratory health effects.. Traditionally, the routes of brevetoxin exposure have been through the consumption of contaminated bivalve shellfish and the inhalation of contaminated aerosols. However, recent studies using more sensitive methods have demonstrated the presence of brevetoxins in many components of the aquatic food web which may indicate potential alternative routes for human exposure.This study examined whether the presence of a Florida red tide bloom affected the rates of admission for a gastrointestinal diagnosis to a hospital emergency room in Sarasota, FL. The rates of gastrointestinal diagnoses admissions were compared for a 3-month time period in 2001 when Florida red tide bloom was present onshore to the same 3-month period in 2002 when no Florida red tide bloom occurred. A significant 40% increase in the total number of gastrointestinal emergency room admissions for the Florida red tide bloom period was found compared to the non red tide period.These results suggest that the healthcare community may experience a significant and unrecognized impact from patients needing emergency medical care for gastrointestinal illnesses during Florida red tide blooms. Thus, additional studies characterizing the potential sources of exposure to the toxins, as well as the dose/effect relationship of brevetoxin exposure, should be undertaken.

  10. Instability of some divalent rare earth ions and photochromic effect

    NASA Astrophysics Data System (ADS)

    Egranov, A. V.; Sizova, T. Yu.; Shendrik, R. Yu.; Smirnova, N. A.

    2016-03-01

    It was shown that the divalent rare earth ions (La, Ce, Gd, Tb, Lu, and Y) in cubic sites in alkaline earth fluorides are unstable with respect to electron autodetachment since its d1(eg) ground state is located in the conduction band which is consistent with the general tendency of these ions in various compounds. The localization of doubly degenerate d1(eg) level in the conduction band creates a configuration instability around the divalent rare earth ion that leading to the formation of anion vacancy in the nearest neighborhood, as was reported in the previous paper [A. Egranov, T. Sizova, Configurational instability at the excited impurity ions in alkaline earth fluorites, J. Phys. Chem. Solids 74 (2013) 530-534]. Thus, the formation of the stable divalent ions as La, Ce, Gd, Tb, Lu, and Y (PC+ centers) in CaF2 and SrF2 crystals during x-ray irradiation occurs via the formation of charged anion vacancies near divalent ions (Re2+va), which lower the ground state of the divalent ion relative to the conductivity band. Photochromic effect occurs under thermally or optically stimulated electron transition from the divalent rare earth ion to the neighboring anion vacancy and reverse under ultraviolet light irradiation. It is shown that the optical absorption of the PC+ centers due to d → d and d → f transitions of the divalent rare-earth ion.

  11. The self-consistent dynamic pole tide in global oceans

    NASA Technical Reports Server (NTRS)

    Dickman, S. R.

    1985-01-01

    The dynamic pole tide is characterized in a self-consistent manner by means of introducing a single nondifferential matrix equation compatible with the Liouville equation, modelling the ocean as global and of uniform depth. The deviations of the theory from the realistic ocean, associated with the nonglobality of the latter, are also given consideration, with an inference that in realistic oceans long-period modes of resonances would be increasingly likely to exist. The analysis of the nature of the pole tide and its effects on the Chandler wobble indicate that departures of the pole tide from the equilibrium may indeed be minimal.

  12. Spectroscopic analysis of global tide gauge sea level data

    NASA Technical Reports Server (NTRS)

    Trupin, A.; Wahr, J.

    1990-01-01

    Yearly and monthly global tide-gage sea-level data are fitted to numerically generated tidal data in order to search for the 18.6-yr lunar nodal tide and 14-month pole tide. Both of these tides are clearly evident, with amplitudes and phases that are consistent with a global equilibrium response. The ocean's response to atmospheric pressure is studied with the least-squares fit technique. Consideration is given to the global rise in sea level, the effects of postglacial rebound, and the possible causes of the enhanced pole tides in the North Sea, the Baltic Sea, and the Gulf of Bothnia. The results support O'Connor's (1986) suggestion that the enhanced pole tide in these regions is due to meteorological forcing rather than a basin-scale resonance. Also, the global average of the tide-gage data show an increase in sea level over tha last 80 yr of between 1.1 and 1.9 mm/yr.

  13. M2 world ocean tide from tide gauge measurements

    SciTech Connect

    Francis, O.; Mazzega, P. )

    1991-06-01

    An empirical model of the M2 oceanic tide has been computed form the harmonic constants of a subset of deep sea and coastal tide gauge measurements. The optimal interpolation of these data based on inverse theory' uses a priori covariance functions deduced from a global hydrodynamical model. The inverse solution, produced with its associated error maps and samples of error spectra, is surprisingly good when compared to in situ data and to a hydrodynamical model.

  14. A study into the effects of gravity wave activity on the diurnal tide and airglow emissions in the equatorial mesosphere and lower thermosphere using the Coupled Middle Atmosphere and Thermosphere (CMAT) general circulation model

    NASA Astrophysics Data System (ADS)

    England, S. L.; Dobbin, A.; Harris, M. J.; Arnold, N. F.; Aylward, A. D.

    2006-02-01

    Momentum deposition by gravity wave breaking is known to affect the amplitude and phase of the diurnal tide. Modelling studies of this interaction have produced some conflicting results and as yet, the exact nature of this interaction is not fully understood. In this study, the effects of parameterised gravity wave momentum deposition on the diurnal tide and subsequently on green line airglow from atomic oxygen during equinox are investigated using the Coupled Middle Atmosphere and Thermosphere (CMAT) general circulation model. The effects of gravity wave drag calculated by two different parameterisations, Meyer [1999. Gravity wave interactions with the diurnal propagating tide. Journal of Geophysical Research 104, 4223 4239] and Medvedev and Klaassen [2000. Parameterisation of gravity wave momentum deposition based on non-linear wave interactions: basic formulation and sensitivity tests. Journal of Atmospheric and Terrestrial Physics 62, 1015 1033], are compared in the low latitude MLT region between 70 and 120 km, where the amplitude of the diurnal tide and green line volume emission rates maximise. Results indicate that momentum sources from both gravity wave parameterisations act to reduce the mid-latitude zonal jets and advance the phase of the diurnal tide, such that the peak amplitude at a given height occurs at an earlier time of day. Gravity wave momentum deposition as parameterised by Meyer [1999. Gravity wave interactions with the diurnal propagating tide. Journal of Geophysical Research 104, 4223 4239] results in a reduction of the amplitude of the diurnal tide in the MLT region, whereas the tidal amplitude is increased when the Medvedev and Klaassen [2000. Parameterisation of gravity wave momentum deposition based on non-linear wave interactions: basic formulation and sensitivity tests. Journal of Atmospheric and Terrestrial Physics 62, 1015 1033] parameterisation is used. Both parameterisations affect the local time variability of the simulated

  15. Propagation Effects in Space/Earth Paths.

    DTIC Science & Technology

    1980-08-01

    staff and other collaborators. H.J.ALBRECHT Editor &COeSsioi or- XTIS GRPA.I TDC TAB LVve ounc ed Justification Di t ribut’i / .li /vfl.,Q4."s Codes...SOLUTIONS by E.Baha and B.S.Agrawal 24 1979-1980 DATA PROCESSING AND RESULTS FROM THE OTS BEACONS BO/B I AND TM , AND RADIOMETRY AT 11.4 AND 35 GHz by...scatterers, neglecting high order scattering 1 4 may be written: a(dB) =[1/(l-w)]10 log [ Tm /( Tm -TA)] where w is the scattering albedo and Tm the effective

  16. The measurement of Earth rotation on a deformable Earth

    NASA Technical Reports Server (NTRS)

    Cannon, W. H.

    1980-01-01

    Until recently, the methods of geodetic positioning on the Earth were limited to a precision of roughly one part in 10 to the 6th power. At this level of precision, the Earth can be regarded as a rigid body since the largest departure of the Earth from rigidity is manifested in the strains of the Earth tides which are of the order of one part in 10 to the 7th power. Long baseline interferometry is expected to routinely provide global positioning to a precision of one part in 10 to the 8th power or better. At this level of precision, all parts of the Earth's surface must be regarded as being, at least potentially, in continual motion relative to the geocenter as a result of a variety of geophysical effects. The general implications of this phenomenon for the theory of the Earth's rotation is discussed. Particular attention is given to the question of the measurement of the 'Earth's rotation vector' on a deformable Earth.

  17. The Runaway Greenhouse Effect on Earth and other Planets

    NASA Technical Reports Server (NTRS)

    Rabbette, Maura; Pilewskie, Peter; McKay, Christopher; Young, Robert

    2001-01-01

    Water vapor is an efficient absorber of outgoing longwave infrared radiation on Earth and is the primary greenhouse gas. Since evaporation increases with increasing sea surface temperature, and the increase in water vapor further increases greenhouse warming, there is a positive feedback. The runaway greenhouse effect occurs if this feedback continues unchecked until all the water has left the surface and enters the atmosphere. For Mars and the Earth the runaway greenhouse was halted when water vapor became saturated with respect to ice or liquid water respectively. However, Venus is considered to be an example of a planet where the runaway greenhouse effect did occur, and it has been speculated that if the solar luminosity were to increase above a certain limit, it would also occur on the Earth. Satellite data acquired during the Earth Radiation Budget Experiment (ERBE) under clear sky conditions shows that as the sea surface temperature (SST) increases, the rate of outgoing infrared radiation at the top of the atmosphere also increases, as expected. Over the pacific warm pool where the SST exceeds 300 K the outgoing radiation emitted to space actually decreases with increasing SST, leading to a potentially unstable system. This behavior is a signature of the runaway greenhouse effect on Earth. However, the SST never exceeds 303K, thus the system has a natural cap which stops the runaway. According to Stefan-Boltzmann's law the amount of heat energy radiated by the Earth's surface is proportional to (T(sup 4)). However, if the planet has a substantial atmosphere, it can absorb all infrared radiation from the lower surface before the radiation penetrates into outer space. Thus, an instrument in space looking at the planet does not detect radiation from the surface. The radiation it sees comes from some level higher up. For the earth#s atmosphere the effective temperature (T(sub e)) has a value of 255 K corresponding to the middle troposphere, above most of the

  18. The effects of general relativity on near-earth satellites

    NASA Technical Reports Server (NTRS)

    Ries, J. C.; Watkins, M. M.; Tapley, B. D.; Huang, C.

    1990-01-01

    Whether one uses a solar system barycentric frame or a geocentric frame when including the general theory of relativity in orbit determination for near-earth satellites, the results should be equivalent to some limiting accuracy. The purpose of this paper is to clarify the effects of relativity in each frame and to demonstrate their equivalence through the analysis of three years of laser tracking data taken on the Lageos satellite. It is demonstrated that the simpler formulation in the geocentric frame is adequate for the purpose of near-earth satellite orbit determination. A correction to the conventional barycentric equations of motion is shown to be required.

  19. Systematic Effects in Earth Orientation Parameters Determined by VLBI

    NASA Astrophysics Data System (ADS)

    Schuh, H.; Heinkelmann, R.

    2015-12-01

    Very Long Baseline Interferometry (VLBI) is the only technique that directly connects on the observation level the realizations of ITRS and ICRS in terms of their orientation. Many applications in spacecraft navigation, fundamental astronomy, astrometry and geosciences depend on the Earth Orientation Parameters (EOP) determined by VLBI. Currently, under the IAG/IAU Joint Working Group on the Theory of Earth Rotation, activities are supported to advance the theory of Earth rotation. Some components of Earth Rotation, such as the free modes like the Free Core Nutation (FCN) are not predictable but rely entirely on the observation through VLBI. In our presentation we investigate the EOP when alternating various VLBI analysis options such as correction models, a priori parameters, and other choices with the aim to detect and quantify possible systematic effects. Our approach is purely empirical: we alternate certain analysis options and assess the differences with respect to the reference solution that adheres to the IERS Conventions (2010) and applies the standard parameterization. For demonstration we analyze the regular International VLBI Service for Geodesy and Astrometry (IVS) sessions IVS-R1 and IVS-R4.The IAG flagship component GGOS (Global Geodetic Observing System) aims to provide the EOP with an accuracy of 1 mm on the Earth surface (about 30 microarcseconds). This accuracy target will be applied as a limit to interpret the significance of the differences obtained in our comparisons.

  20. A review of ionospheric effects on Earth-space propagation

    NASA Technical Reports Server (NTRS)

    Klobuchar, J. A.

    1984-01-01

    A short description is given of each ionospheric total electron content (TEC) effect upon radio waves, along with a representative value of the magnitude of each of these effects under normal ionospheric conditions. A discussion is given of the important characteristics of average ionospheric TEC behavior and the temporal and spatial variability of TEC. Radio waves undergo several effects when they pass through the Earth's ionosphere. One of the most important of these effects is a retardation, or group delay, on the modulation or information carried on the radio wave that is due to its encounter with the free, thermal electrons in the Earth's ionosphere. Other effects the ionosphere has on radio waves include: radio frequency (RF) carrier phase advance; Doppler shift of the RF carrier of the radio wave; Faraday rotation of the plane of polarization of linearly polarized waves; angular refraction or bending of the radio wave path as it travels through the ionosphere; and amplitude and phase scintillations.

  1. Effects of megascale eruptions on Earth and Mars

    USGS Publications Warehouse

    Thordarson, T.; Rampino, M.; Keszthelyi, L.P.; Self, S.

    2009-01-01

    Volcanic features are common on geologically active earthlike planets. Megascale or "super" eruptions involving >1000 Gt of magma have occurred on both Earth and Mars in the geologically recent past, introducing prodigious volumes of ash and volcanic gases into the atmosphere. Here we discuss felsic (explosive) and mafi c (flood lava) supereruptions and their potential atmospheric and environmental effects on both planets. On Earth, felsic supereruptions recur on average about every 100-200,000 years and our present knowledge of the 73.5 ka Toba eruption implies that such events can have the potential to be catastrophic to human civilization. A future eruption of this type may require an unprecedented response from humankind to assure the continuation of civilization as we know it. Mafi c supereruptions have resulted in atmospheric injection of volcanic gases (especially SO2) and may have played a part in punctuating the history of life on Earth. The contrast between the more sustained effects of flood basalt eruptions (decades to centuries) and the near-instantaneous effects of large impacts (months to years) is worthy of more detailed study than has been completed to date. Products of mafi c supereruptions, signifi cantly larger than known from the geologic record on Earth, are well preserved on Mars. The volatile emissions from these eruptions most likely had global dispersal, but the effects may not have been outside what Mars endures even in the absence of volcanic eruptions. This is testament to the extreme variability of the current Martian atmosphere: situations that would be considered catastrophic on Earth are the norm on Mars. ?? 2009 The Geological Society of America.

  2. Design of Scalable and Effective Earth Science Collaboration Tool

    NASA Astrophysics Data System (ADS)

    Maskey, M.; Ramachandran, R.; Kuo, K. S.; Lynnes, C.; Niamsuwan, N.; Chidambaram, C.

    2014-12-01

    Collaborative research is growing rapidly. Many tools including IDEs are now beginning to incorporate new collaborative features. Software engineering research has shown the effectiveness of collaborative programming and analysis. In particular, drastic reduction in software development time resulting in reduced cost has been highlighted. Recently, we have witnessed the rise of applications that allow users to share their content. Most of these applications scale such collaboration using cloud technologies. Earth science research needs to adopt collaboration technologies to reduce redundancy, cut cost, expand knowledgebase, and scale research experiments. To address these needs, we developed the Earth science collaboration workbench (CWB). CWB provides researchers with various collaboration features by augmenting their existing analysis tools to minimize learning curve. During the development of the CWB, we understood that Earth science collaboration tasks are varied and we concluded that it is not possible to design a tool that serves all collaboration purposes. We adopted a mix of synchronous and asynchronous sharing methods that can be used to perform collaboration across time and location dimensions. We have used cloud technology for scaling the collaboration. Cloud has been highly utilized and valuable tool for Earth science researchers. Among other usages, cloud is used for sharing research results, Earth science data, and virtual machine images; allowing CWB to create and maintain research environments and networks to enhance collaboration between researchers. Furthermore, collaborative versioning tool, Git, is integrated into CWB for versioning of science artifacts. In this paper, we present our experience in designing and implementing the CWB. We will also discuss the integration of collaborative code development use cases for data search and discovery using NASA DAAC and simulation of satellite observations using NASA Earth Observing System Simulation

  3. Flattening Earth acceleration in atomic fountains

    SciTech Connect

    Bertoldi, Andrea

    2010-07-15

    A method to compensate for Earth's gravity tide over an extended axial region is reported. Flattening acceleration is important in experiments where the coupling of the dynamics of free-falling probes to the gravity gradient generates stochastic noise on the measurement. Optimized cylindrically symmetric mass distributions lower Earth's tidal effect over 10 cm by a factor 10{sup 3}. A multimass compensation system with comparable performance is devised for tall atom interferometers. Reducing the gravity gradient is essential in terrestrial experiments based on atom fountain configurations being developed to precisely test general relativity or the neutrality of matter.

  4. M2, S2, K1 models of the global ocean tide

    NASA Technical Reports Server (NTRS)

    Parke, M. E.; Hendershott, M. C.

    1979-01-01

    Ocean tidal signals appear in many geophysical measurements. Geophysicists need realistic tidal models to aid in interpretation of their data. Because of the closeness to resonance of dissipationless ocean tides, it is difficult for numerical models to correctly represent the actual open ocean tide. As an approximate solution to this problem, test functions derived by solving Laplace's Tidal Equations with ocean loading and self gravitation are used as a basis for least squares dynamic interpolation of coastal and island tidal data for the constituents M2, S2, and Kl. The resulting representations of the global tide are stable over at least a ?5% variation in the mean depth of the model basin, and they conserve mass. Maps of the geocentric tide, the induced free space potential, the induced vertical component of the solid earth tide, and the induced vertical component of the gravitational field for each contituent are presented.

  5. Red Tide off Texas Coast

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Red tides (algae) bloomed late this summer along a 300-mile stretch of Texas' Gulf Coast, killing millions of fish and shellfish as well as making some people sick. State officials are calling this the worst red tide bloom in 14 years. The algae produces a poison that paralyzes fish and prevents them from breathing. There is concern that the deadly algae could impact or even wipe out this year's oyster harvest in Texas, which usually peaks during the Thanksgiving and Christmas holidays. The red tides were first observed off the Texas coast in mid-August and have been growing steadily in size ever since. Red tides tend to bloom and subside rapidly, depending upon changes in wind speed and direction, water temperature, salinity, and rainfall patterns (as the algae doesn't do as well in fresher water). This true-color image of the Texas Gulf Coast was acquired on September 29, 2000, by the Moderate-resolution Imaging Spectroradiometer (MODIS) flying aboard NASA's Terra spacecraft. The red tide can be seen as the dark reddish discoloration in the ocean running southwest to northeast along the coast. In this scene, the bloom appears to be concentrated north and east of Corpus Christi, just off Matagorda Island. The image was made at 500-meter resolution using a combination of MODIS' visible bands 1 (red), 4 (green), and 3 (blue). The city of Houston can be seen clearly as the large, greyish cluster of pixels to the north and west of Galveston Bay, which is about mid-way up the coastline in this image. Also visible in this image are plumes of smoke, perhaps wildfires, both to the north and northeast of Houston. For more information about red tides, refer to the Texas Red Tide Web site. Image courtesy Andrey Savtchenko, MODIS Data Support Team, and the MODIS Ocean Team, NASA's Goddard Space Flight Center

  6. Downwelling wind, tides, and estuarine plume dynamics

    NASA Astrophysics Data System (ADS)

    Lai, Zhigang; Ma, Ronghua; Huang, Mingfen; Chen, Changsheng; Chen, Yong; Xie, Congbin; Beardsley, Robert C.

    2016-06-01

    The estuarine plume dynamics under a downwelling-favorable wind condition were examined in the windy dry season of the Pearl River Estuary (PRE) using the PRE primitive-equation Finite-Volume Community Ocean Model (FVCOM). The wind and tide-driven estuarine circulation had a significant influence on the plume dynamics on both local and remote scales. Specifically, the local effect of downwelling-favorable winds on the plume was similar to the theoretical descriptions of coastal plumes, narrowing the plume width, and setting up a vertically uniform downstream current at the plume edge. Tides tended to reduce these plume responses through local turbulent mixing and advection from upstream regions, resulting in an adjustment of the isohalines in the plume and a weakening of the vertically uniform downstream current. The remote effect of downwelling-favorable winds on the plume was due to the wind-induced estuarine sea surface height (SSH), which strengthened the estuarine circulation and enhanced the plume transport accordingly. Associated with these processes, tide-induced mixing tended to weaken the SSH gradient and thus the estuarine circulation over a remote influence scale. Overall, the typical features of downwelling-favorable wind-driven estuarine plumes revealed in this study enhanced our understanding of the estuarine plume dynamics under downwelling-favorable wind conditions.

  7. Revised predictions of long-period ocean tidal effects on Earth's rotation rate

    NASA Technical Reports Server (NTRS)

    Dickman, S. R.; Nam, Young S.

    1995-01-01

    The rotational response of Earth to long-period tidal forces, embodied in a 'zonal response function,' can be expected to vary with frequency because of variable contributions by the oceans, mantle, and core. The zonal response function has been estimated from 9 years of International Radio Interferometric Surveying (IRIS) universal time (UT1) data and compared with theoretical predictions, using a spherical harmonic tide model to compute the oceans' dynamic response, at semiannual, monthly, fortnightly, and 9-day lunisolar tidal frequencies. Different amounts of mantle anelasticity have been considered for both the oceanic and soild earth responses; predictions have been made assuming axial core-mantle coupling which is either complete or absent. Additionally, an extensive recalibration of the ocean model's frictional parameters was performed using constraints derived in part from Space92 polar motion data; zonal response function predictions have also been made employing this recalibrated ocean tide model. Our results indicate that any amount of core coupling can be ruled out at a fortnightly period and probably at a 9-day period, but not at a monthly period. Our results also suggest that the mantle responds purely elastically at a 9-day period but may behave increasingly anelastically at longer periods. A simple dispersive rule is postulated for periods ranging up to the 14-month Chandler wobble period.

  8. Tides and the evolution of planetary habitability.

    PubMed

    Barnes, Rory; Raymond, Sean N; Jackson, Brian; Greenberg, Richard

    2008-06-01

    Tides raised on a planet by the gravity of its host star can reduce the planet's orbital semi-major axis and eccentricity. This effect is only relevant for planets orbiting very close to their host stars. The habitable zones of low-mass stars are also close in, and tides can alter the orbits of planets in these locations. We calculate the tidal evolution of hypothetical terrestrial planets around low-mass stars and show that tides can evolve planets past the inner edge of the habitable zone, sometimes in less than 1 billion years. This migration requires large eccentricities (>0.5) and low-mass stars ( less or similar to 0.35 M(circle)). Such migration may have important implications for the evolution of the atmosphere, internal heating, and the Gaia hypothesis. Similarly, a planet that is detected interior to the habitable zone could have been habitable in the past. We consider the past habitability of the recently discovered, approximately 5 M(circle) planet, Gliese 581 c. We find that it could have been habitable for reasonable choices of orbital and physical properties as recently as 2 Gyr ago. However, when constraints derived from the additional companions are included, most parameter choices that indicate past habitability require the two inner planets of the system to have crossed their mutual 3:1 mean motion resonance. As this crossing would likely have resulted in resonance capture, which is not observed, we conclude that Gl 581 c was probably never habitable.

  9. Magnetostatic Effects in the Nucleation of Rare Earth Ferromagnetic Phases

    SciTech Connect

    Durfee, C. S.; Flynn, C. P.

    2001-07-30

    It has been reported that superheating, supercooling, and explosive kinetics coupled to other degrees of freedom occur at the ferromagnetic transitions of Er and Dy, and that metastable phases occur during the transition kinetics of Er. We explain these observations in terms of magnetostatic energy, which requires highly eccentric nuclei in the homogeneous nucleation of magnetic transitions in heavy rare earths. The magnetostatics favor transitions through ferrimagnetic intermediaries. The unusual kinetics derive from effective spin lattice relaxation.

  10. Earth matter effect on active-sterile neutrino oscillations

    NASA Astrophysics Data System (ADS)

    Acero, Mario A.; Aguilar-Arevalo, Alexis A.; D'Olivo, J. C.

    2011-08-01

    Oscillations between active and sterile neutrinos remain as an open possibility to explain some experimental observations. In a four-neutrino mixing scheme, we use the Magnus expansion of the evolution operator to study the evolution of neutrino flavor amplitudes within the Earth. We apply this formalism to calculate the transition probabilities from active to sterile neutrinos taking into account the matter effect for a varying terrestrial density.

  11. On the tidal effects in the motion of earth satellites and the love parameters of the earth

    NASA Technical Reports Server (NTRS)

    Musen, P.; Estes, R.

    1972-01-01

    The tidal effects in the motion of artificial satellites are studied to determine the elastic properties of the earth as they are observed from extraterrestrial space. Considering Love numbers, the disturbing potential is obtained as the analytical continuation of the tidal potential from the surface of the earth into-outer space, with parameters which characterize the earth's elastic response to tidal attraction by the moon and the sun. It is concluded that the tidal effects represent a superposition of a large number of periodic terms, and the rotation of the lunar orbital plane produces a term of 18 years period in tidal perturbations of the ascending node of the satellite's orbit.

  12. On the polarization relations of diurnal and semidiurnal tide in the mesopause region

    NASA Astrophysics Data System (ADS)

    She, Chiao-Yao; Krueger, David A.; Yuan, Tao; Oberheide, Jens

    2016-05-01

    The polarization relations for gravity waves are well known and have proven to be very powerful for the investigation of their dynamics. Though tides are sometimes regarded as low-frequency gravity waves, their polarization relations are hardly considered. We derive the polarization relationships of tides from the primitive equations for perturbations of a dissipation-less atmosphere. The vertical wind tide is found to relate directly to temperature tide, independent of tidal structure and geometric location. On the other hand, the relation between meridional wind tide and zonal wind tide is found to depend on the horizontal derivatives of the associated geopotential perturbation, thus depending on tidal structure and geometric location. Lidar observed tides at a local station (tidal period perturbations) in the midlatitude mesopause region (80-105 km) and the Climatological Tidal Model of the Thermosphere (CTMT) based on Hough Mode Extension (HME) technique at the lidar site, both of which include the effect of dissipation, are then compared. These tidal amplitudes and phases are employed to discuss the results and implications of the derived tidal wave polarization relations. The dominance of the migrating tide follows from the phase relationship between zonal and meridional wind tides. By comparing the observed and derived vertical wind tides, we reveal qualitatively the altitude dependence of tidal wave dissipation.

  13. Three-Dimensional Orbits of Earth Satellites, Including Effects of Earth Oblateness and Atmospheric Rotation

    NASA Technical Reports Server (NTRS)

    Nielsen, Jack N.; Goodwin, Frederick K.; Mersman, William A.

    1958-01-01

    The principal purpose of the present paper is to present sets of equations which may be used for calculating complete trajectories of earth satellites from outer space to the ground under the influence of air drag and gravity, including oblateness effects, and to apply these to several examples of entry trajectories starting from a circular orbit. Equations of motion, based on an "instantaneous ellipse" technique, with polar angle as independent variable, were found suitable for automatic computation of orbits in which the trajectory consists of a number of revolutions. This method is suitable as long as the trajectory does not become nearly vertical. In the terminal phase of the trajectories, which are nearly vertical, equations of motion in spherical polar coordinates with time as the independent variable were found to be more suitable. In the first illustrative example the effects of the oblateness component of the earth's gravitational field and of atmospheric rotation were studied for equatorial orbits. The satellites were launched into circular orbits at a height of 120 miles, an altitude sufficiently high that a number of revolutions could be studied. The importance of the oblateness component of the earth's gravitational field is shown by the fact that a satellite launched at circular orbital speed, neglecting oblateness, has a perigee some 67,000 feet lower when oblateness forces are included in the equations of motion than when they are not included. Also, the loss in altitude per revolution is double that of a satellite following an orbit not subject to oblateness. The effect of atmospheric rotation on the loss of altitude per revolution was small. As might be surmised, the regression of the line of nodes as predicted by celestial mechanics is unchanged when drag is included. It is clear that the inclination of the orbital plane to the equator will be relatively unaffected by drag for no atmospheric rotation since the drag lies in the orbital plane in

  14. New Jersey Tide Telemetry System

    USGS Publications Warehouse

    Hoppe, Heidi L.

    2007-01-01

    Each summer the population of the barrier-island communities of New Jersey increases by tens of thousands. When a coastal storm threatens these communities, the limited number of bridges and causeways that connect the islands with the mainland become overcrowded, making evacuations from the barrier islands to the mainland difficult. Timely evacuation depends on well-defined emergency evacuation plans used in conjunction with accurate flood forecasting and up to the minute (real-time) tide-level information. The 'Great Nor'easter' storm that struck the coastal areas of New Jersey on December 11, 1992, caused about $270 million in insured damages to public and private property (Dorr and others, 1995). Most of the damage was due to tidal flooding and storm surge, which were especially severe along the back bay areas. Comprehensive and reliable tide-level and meteorological data for the back bays was needed to make accurate flood forecasts. Collection of tidal data for the ocean and large bays was adequately covered by the National Oceanic and Atmospheric Administration's National Ocean Service (NOAA's NOS), but in New Jersey little to no data are available for the back-bay areas. The back bays behave quite differently than the ocean as a result of the complex interaction between the winds and the geometry of the inlets and bays. A slow moving Nor'easter can keep tide levels in back bays several feet higher than the ocean tide by not allowing tides to recede, resulting in flooding of bridges and causeways that link the barrier islands to the mainland. The U.S. Geological Survey (USGS), in cooperation with the New Jersey Department of Transportation (NJDOT), designed and installed the New Jersey Tide Telemetry System (NJTTS) with assistance from NOAA's NOS in 1997. This system is part of a statewide network of tide gages, weather stations, and stream gages that collect data in real time. The NJTTS supplies comprehensive, reliable real-time tide-level and meteorological

  15. Relativistic effects in earth-orbiting Doppler lidar return signals.

    PubMed

    Ashby, Neil

    2007-11-01

    Frequency shifts of side-ranging lidar signals are calculated to high order in the small quantities (v/c), where v is the velocity of a spacecraft carrying a lidar laser or of an aerosol particle that scatters the radiation back into a detector (c is the speed of light). Frequency shift measurements determine horizontal components of ground velocity of the scattering particle, but measured fractional frequency shifts are large because of the large velocities of the spacecraft and of the rotating earth. Subtractions of large terms cause a loss of significant digits and magnify the effect of relativistic corrections in determination of wind velocity. Spacecraft acceleration is also considered. Calculations are performed in an earth-centered inertial frame, and appropriate transformations are applied giving the velocities of scatterers relative to the ground.

  16. Barometric Tides from ECMWF Operational Analyses

    NASA Technical Reports Server (NTRS)

    Ray, R. D.; Ponte, R. M.

    2003-01-01

    The solar diurnal and semidiurnal tidal oscillations in surface pressure are extracted from the the operational analysis product of the European Centre for Medium Range Weather Forecasting (ECMWF). For the semidiurnal tide this involves a special temporal interpolation, following Van den Dool and colleagues. The resulting tides are compared with a ground truth tide dataset, a compilation of well-determined tide estimates deduced from long time series of station barometer measurements. These comparisons show that the ECMWF tides are significantly more accurate than the tides deduced from two other widely available reanalysis products. Spectral analysis of ECMWF pressure series shows that the tides consist of sharp central peaks with modulating sidelines at integer multiples of 1 cycle/year, superimposed on a broad cusp of stochastic energy. The integrated energy in the cusp dominates that of the sidelines. This complicates development of a simple model that can characterize the full temporal variability of the tides.

  17. A computer software system for the generation of global ocean tides including self-gravitation and crustal loading effects

    NASA Technical Reports Server (NTRS)

    Estes, R. H.

    1977-01-01

    A computer software system is described which computes global numerical solutions of the integro-differential Laplace tidal equations, including dissipation terms and ocean loading and self-gravitation effects, for arbitrary diurnal and semidiurnal tidal constituents. The integration algorithm features a successive approximation scheme for the integro-differential system, with time stepping forward differences in the time variable and central differences in spatial variables. Solutions for M2, S2, N2, K2, K1, O1, P1 tidal constituents neglecting the effects of ocean loading and self-gravitation and a converged M2, solution including ocean loading and self-gravitation effects are presented in the form of cotidal and corange maps.

  18. Anomalous Hall Effect in a Feromagnetic Rare-Earth Cobalite

    NASA Technical Reports Server (NTRS)

    Samoilov, A. V.; Yeh, N. C.; Vasquez, R. P.

    1996-01-01

    Rare-Earth manganites and cobalites with the perovskite structure have been a subject of great recent interest because their electrical resistance changes significantly when a magnetic field is applied...we have studied the Hall effect in thin film La(sub 0.5)Ca(sub 0.5)CoO(sub 3) material and have obtained convincing evidence fo the so called anomalous Hall effect, typical for magnetic metals...Our results suggest that near the ferromagnetic ordering temperature, the dominant electron scattering mechanism is the spin fluctuation.

  19. A computer software system for the generation of global ocean tides including self-gravitation and crustal loading effects

    NASA Technical Reports Server (NTRS)

    Estes, R. H.

    1977-01-01

    A computer software system is described which computes global numerical solutions of the integro-differential Laplace tidal equations, including dissipation terms and ocean loading and self-gravitation effects, for arbitrary diurnal and semidiurnal tidal constituents. The integration algorithm features a successive approximation scheme for the integro-differential system, with time stepping forward differences in the time variable and central differences in spatial variables.

  20. Effect of rare earth oxides for improvement of MCFC

    NASA Astrophysics Data System (ADS)

    Ota, Ken-ichiro; Matsuda, Yoshiyuki; Matsuzawa, Koichi; Mitsushima, Shigenori; Kamiya, Nobuyuki

    The solubility of rare earth metal oxides and their effect on the NiO solubility have been discussed to stabilize the cathode of molten carbonate fuel cells. The solubility of Ho, Yb, and Nd oxides were 4.4 × 10 -4, 3.4 × 10 -4, and 1.3 × 10 -3 (mole fraction) at 923 K, respectively. The solubilities of NiO in (Li 0.52/Na 0.48) 2CO 3 with the saturated Ho, Yb, and Nd were 1.57 × 10 -5, 1.41 × 10 -5, and 9.5 × 10 -6, respectively. Among these three, Nd, which has the highest solubility in the carbonates, reduced the NiO solubility most; although, the La reduced the NiO solubility more than Nd. The logarithm of the solubility of the rare earth metal oxides has a linear relation to the Coulomb force ratio between the rare earth metal and the alkaline metal. Following this relation, the La should have the highest solubility among all the lanthanides. The basicity which NiO solubility closely relates has a linear relationship to the Coulomb force parameter of the melts. Based on these two models, the La would be the best additive to reduce the NiO solubility in Li/Na eutectic carbonate melt, among all the lanthanides.

  1. Inverse Modeling of Coastal Tides

    DTIC Science & Technology

    1999-09-30

    data in the tidal band. We have concluded that understanding this discrepancy and developing assimilation methods for baroclinic tides will require...Alexandre Kurapov to develop practical assimilation methods for coastal HF radar data. REFERENCES Bennett, A.F., B.S. Chua, and L.M. Leslie, Generalized

  2. Inverse Modeling of Coastal Tides

    DTIC Science & Technology

    1998-01-01

    produced. We are also working with Profs. J. Allen and R. Miller on developing practical assimilation methods for the coastal problem. REFERENCES...40, 81--108, 1997. Egbert, G.D. and A.F. Bennett, Data assimilation methods for ocean tides, in Modern approaches to data assimilation in ocean

  3. Why the 18.6 year tide cannot explain the change of sign observed in j2

    NASA Astrophysics Data System (ADS)

    Deleflie, F.; Exertier, P.; Metris, G.; Berio, P.; Laurain, O.; Lemoine, J.-M.; Biancale, R.

    2003-06-01

    Recent studies show a change, starting in 1998, in the behavior of the variation of the dynamical flattening of the Earth (J2), supposed to be constant (secular), and mainly due to the post glacial rebound effect. In this paper, we study to what extent this behavior can be correlated or not with the 18.6 year tide: with more than twenty years of tracking data on LAGEOS-1, that is to say more than a period of 18.6 years, this effect can now be separated from the secular variation. We use our theory of mean orbital motion, dedicated to studies of the long period effects on the orbital motion. We build one single arc of LAGEOS-1 from 1980 to 2002, which provides a continuous description of the orbital parameters. This is the great originality of our approach. We focus our attention on the ascending node of LAGEOS-1, and we show that the change observed in j2 cannot be attributed to a statistical error due to a correlation, in short arcs results, between the secular variation of J2 and the 18.6 year tide. The proof is based on the adjustment of amplitudes and phases of the long period tides, and on the shape of the residuals.

  4. NONLINEAR TIDES IN CLOSE BINARY SYSTEMS

    SciTech Connect

    Weinberg, Nevin N.; Arras, Phil; Quataert, Eliot; Burkart, Josh

    2012-06-01

    We study the excitation and damping of tides in close binary systems, accounting for the leading-order nonlinear corrections to linear tidal theory. These nonlinear corrections include two distinct physical effects: three-mode nonlinear interactions, i.e., the redistribution of energy among stellar modes of oscillation, and nonlinear excitation of stellar normal modes by the time-varying gravitational potential of the companion. This paper, the first in a series, presents the formalism for studying nonlinear tides and studies the nonlinear stability of the linear tidal flow. Although the formalism we present is applicable to binaries containing stars, planets, and/or compact objects, we focus on non-rotating solar-type stars with stellar or planetary companions. Our primary results include the following: (1) The linear tidal solution almost universally used in studies of binary evolution is unstable over much of the parameter space in which it is employed. More specifically, resonantly excited internal gravity waves in solar-type stars are nonlinearly unstable to parametric resonance for companion masses M' {approx}> 10-100 M{sub Circled-Plus} at orbital periods P Almost-Equal-To 1-10 days. The nearly static 'equilibrium' tidal distortion is, however, stable to parametric resonance except for solar binaries with P {approx}< 2-5 days. (2) For companion masses larger than a few Jupiter masses, the dynamical tide causes short length scale waves to grow so rapidly that they must be treated as traveling waves, rather than standing waves. (3) We show that the global three-wave treatment of parametric instability typically used in the astrophysics literature does not yield the fastest-growing daughter modes or instability threshold in many cases. We find a form of parametric instability in which a single parent wave excites a very large number of daughter waves (N Almost-Equal-To 10{sup 3}[P/10 days] for a solar-type star) and drives them as a single coherent unit with

  5. Can tides influence volcanic eruptions?

    NASA Astrophysics Data System (ADS)

    Girona, T.; Huber, C.

    2015-12-01

    The possibility that the Moon-Sun gravitational force can affect terrestrial volcanoes and trigger eruptions is a controversial issue that has been proposed since ancient times, and that has been widely debated during the last century. The controversy arises mainly from two reasons. First, the days of initiation of eruptions are not well known for many volcanoes, and thus a robust statistical comparison with tidal cycles cannot be performed for many of them. Second, the stress changes induced by tides in the upper crust are very small (10-3 MPa) compared to the tensile strength of rocks (~ 10-1-10 MPa), and hence the mechanism by which tidal stresses might trigger eruptions is unclear. In this study, we address these issues for persistently degassing volcanoes, as they erupt frequently and thus the initiation time of a significant number of eruptions (>30) is well known in several cases (9). In particular, we find that the occurrence of eruptions within ±2 days from neap tides (first and third quarter moon) is lower than 34% (e.g., 29% for Etna, Italy; 28% for Merapi, Indonesia), which is the value expected if eruptions occur randomly with no external influence. To understand this preference for erupting far away from neap tides, we have developed a new lumped-parameter model that accounts for the deformation of magma reservoirs, a partially open conduit, and a gas layer where bubbles accumulate beneath volcanic craters before being released. We demonstrate that this system reservoir-conduit-gas layer acts as an amplifier of the tidal stresses, such that, when a volcano approaches to a critical state, the gas overpressure beneath the crater can reach up to several MPa more during a spring tide (full and new moon) than during a neap tide. This amplification mechanism can explain why active volcanoes are sensitive to the moon cycles.

  6. The effect of atmospheric pressure on Snowball Earth deglaciation

    NASA Astrophysics Data System (ADS)

    Edkins, Nicholas; Davies, Roger

    2017-02-01

    The most common explanation for the escape from a Snowball Earth state involves, among other factors, a strong greenhouse effect caused by a large partial pressure of CO2. This leads to an increase in surface pressure, which most models do not account for. With a higher surface pressure, pressure broadening increases, and convection reaches a deeper layer, both of which result in higher surface temperatures. The latter mechanism, which has not previously been reported, is found to be a greater source of warming than pressure broadening in the normal range of CO2 partial pressures at the point of deglaciation.

  7. The thermodynamic effect of atmospheric mass on early Earth's temperature

    NASA Astrophysics Data System (ADS)

    Chemke, R.; Kaspi, Y.; Halevy, I.

    2016-11-01

    Observations suggest that Earth's early atmospheric mass differed from the present day. The effects of a different atmospheric mass on radiative forcing have been investigated in climate models of variable sophistication, but a mechanistic understanding of the thermodynamic component of the effect of atmospheric mass on early climate is missing. Using a 3-D idealized global circulation model (GCM), we systematically examine the thermodynamic effect of atmospheric mass on near-surface temperature. We find that higher atmospheric mass tends to increase the near-surface temperature mostly due to an increase in the heat capacity of the atmosphere, which decreases the net radiative cooling effect in the lower layers of the atmosphere. Additionally, the vertical advection of heat by eddies decreases with increasing atmospheric mass, resulting in further near-surface warming. As both net radiative cooling and vertical eddy heat fluxes are extratropical phenomena, higher atmospheric mass tends to flatten the meridional temperature gradient.

  8. Magnus Effect on a Spinning Satellite in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Ramjatan, Sahadeo; Fitz-Coy, Norman; Yew, Alvin Garwai

    2016-01-01

    A spinning body in a flow field generates an aerodynamic lift or Magnus effect that displaces the body in a direction normal to the freestream flow. Earth orbiting satellites with substantial body rotation in appreciable atmospheric densities may generate a Magnus force to perturb orbital dynamics. We investigate the feasibility of using this effect for spacecraft at a perigee of 80km using the Systems Tool Kit (STK). Results show that for a satellite of reasonable properties, the Magnus effect doubles the amount of time in orbit. Orbital decay was greatly mitigated for satellites spinning at 10000 and 15000RPM. This study demonstrates that the Magnus effect has the potential to sustain a spacecraft's orbit at a low perigee altitude and could also serve as an orbital maneuver capability.

  9. The radiative effect of aerosols in the earth's atmosphere

    NASA Technical Reports Server (NTRS)

    Wang, W.-C.; Domoto, G. A.

    1974-01-01

    A modified two-flux approximation is employed to compute the transfer of radiation in a finite, inhomogeneous, turbid atmosphere. A perturbation technique is developed to allow the treatment of nongray gaseous absorption with multiple scattering. The perturbation method, which employs a backscatter factor as a parameter, can be used with anisotropic particle scattering as well as Rayleigh scattering. This method is used to study the effect of aerosols on radiative solar heating and infrared cooling as well as the radiative-convective temperature distribution in the earth's atmosphere. It is found that the effect of aerosols in the infrared cannot be neglected; while in the visible, the effect can be of the same order as that due to absorption by water vapor. For a high surface albedo (greater than 0.30) heating of the earth-atmosphere system results due to the presence of aerosols. The aerosols also reduce the amount of convection needed to maintain a stable atmosphere. For the case of a dense haze a temperature inversion is found to exist close to the ground.

  10. The Effect of Dark Matter on Solar System and Perihelion Precession of Earth Planet

    NASA Astrophysics Data System (ADS)

    Saadat, Hassan; Mousavi, S. N.; Saadat, M.; Saadat, N.; Saadat, A. M.

    2010-10-01

    This paper visualizes effect of dark matter on solar system and especially perihelion precession of Earth planet. The relation between the rate of perihelion shift of Earth planet and dark matter are obtained.

  11. Effect of river discharge and geometry on tides and net water transport in an estuarine network, an idealized model applied to the Yangtze Estuary

    NASA Astrophysics Data System (ADS)

    Alebregtse, N. C.; de Swart, H. E.

    2016-07-01

    Tidal propagation in, and division of net water transport over different channels in an estuarine network are analyzed using a newly developed idealized model. The water motion in this model is governed by the cross-sectionally averaged shallow water equations and is forced by tides at the seaward boundaries and by river discharge. Approximate analytical solutions are constructed by means of a harmonic truncation and a perturbation expansion in a small parameter, being the ratio of tidal amplitude and depth. The net water transport results from an imposed river discharge and from residual water transport generated by nonlinear tidal rectification. Two new drivers are identified that contribute to the net water transport in tidal estuarine networks, viz. the generation of residual water transport due to gradients in dynamic pressure and due to a coupling between the tidally averaged and quarter diurnal currents through the quadratic bottom stress. The model is applied in a case study on the Yangtze Estuary, to investigate tides and division of net water transport over its multiple channels during the wet and dry season, as well as before and after the construction of the Deepwater Navigation Channel. Model results agree fairly well with observations. Process analysis reveals that the decrease in tides from dry to wet season is due to enhanced bottom stress generated by river-tide interactions. Also, the seasonal variations in net water transport are explained. It is furthermore shown and explained that due to the Deepwater Navigation Channel tidal currents have increased and net water transport has decreased in the North Passage. These changes have profound implications for net sediment transport and salinity intrusion.

  12. TideNet: A Web-Based Tidal Data Access, Processing and Analysis Tool, Part 1 -NWS Tidal Database

    DTIC Science & Technology

    2013-08-01

    gravitational influences of the Moon and Sun on Earth, the tilt of the rotational axis of Earth, the elliptical shape of the Moon’s orbit around Earth...periodic change or variation in the relative positions of Earth, Moon , and Sun and has a period of less than half a day. Report Documentation Page Form...theory_of_tides .The majority of tide databases provide elevation amplitudes and phases for the eight primary harmonic constituents (M2, S2, K2, N2, K1, O1

  13. WIMP capture and annihilation in the Earth in effective theories

    NASA Astrophysics Data System (ADS)

    Catena, Riccardo

    2017-01-01

    I calculate the rate of WIMP capture and annihilation in the Earth in the non-relativistic effective theory of dark matter-nucleon interactions. Neglecting operator interference, I consider all Galilean invariant interaction operators that can arise from the exchange of a heavy particle of spin less than or equal to one when WIMPs have spin 0, 1/2 or 1. I compute position and shape of the expected resonances in the mass—capture rate plane and show that Iron is not the most important element in the capture process for many currently ignored interaction operators. I compare these predictions with the recent results of an Earth WIMP analysis of IceCube in the 86-string configuration and set limits on all isoscalar and isovector coupling constants of the effective theory of dark matter-nucleon interactions. For certain interaction operators and for a dark matter particle mass of about 50 GeV, I find that these limits are stronger than those I have previously derived in an analysis of the solar WIMP search performed at IceCube in the 79-string configuration.

  14. Limiting amplitudes of fully nonlinear interfacial tides and solitons

    NASA Astrophysics Data System (ADS)

    Aguiar-González, Borja; Gerkema, Theo

    2016-08-01

    A new two-fluid layer model consisting of forced rotation-modified Boussinesq equations is derived for studying tidally generated fully nonlinear, weakly nonhydrostatic dispersive interfacial waves. This set is a generalization of the Choi-Camassa equations, extended here with forcing terms and Coriolis effects. The forcing is represented by a horizontally oscillating sill, mimicking a barotropic tidal flow over topography. Solitons are generated by a disintegration of the interfacial tide. Because of strong nonlinearity, solitons may attain a limiting table-shaped form, in accordance with soliton theory. In addition, we use a quasi-linear version of the model (i.e. including barotropic advection but linear in the baroclinic fields) to investigate the role of the initial stages of the internal tide prior to its nonlinear disintegration. Numerical solutions reveal that the internal tide then reaches a limiting amplitude under increasing barotropic forcing. In the fully nonlinear regime, numerical experiments suggest that this limiting amplitude in the underlying internal tide extends to the nonlinear case in that internal solitons formed by a disintegration of the internal tide may not reach their table-shaped form with increased forcing, but appear limited well below that state.

  15. Hydroxyl radical generation by red tide algae.

    PubMed

    Oda, T; Akaike, T; Sato, K; Ishimatsu, A; Takeshita, S; Muramatsu, T; Maeda, H

    1992-04-01

    The unicellular marine phytoplankton Chattonella marina is known to have toxic effects against various living marine organisms, especially fishes. However, details of the mechanism of the toxicity of this plankton remain obscure. Here we demonstrate the generation of superoxide and hydroxyl radicals from a red tide unicellular organism, C. marina, by using ESR spectroscopy with the spin traps 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and N-t-butyl-alpha-phenylnitrone (PBN), and by using the luminol-enhanced chemiluminescence response. The spin-trapping assay revealed productions of spin adduct of superoxide anion (O2-) (DMPO-OOH) and that of hydroxyl radical (.OH) (DMPO-OH) in the algal suspension, which was not observed in the ultrasonic-ruptured suspension. The addition of superoxide dismutase (500 U/ml) almost completely inhibited the formation of both DMPO-OOH and DMPO-OH, and carbon-centered radicals were generated with the disappearance of DMPO-OH after addition of 5% dimethyl sulfoxide (Me2SO) and 5% ethanol. Furthermore, the generation of methyl and methoxyl radicals, which are thought to be produced by the reaction of hydroxyl radical and Me2SO under aerobic condition, was identified using spin trapping with a combination of PBN and Me2SO. Luminol-enhanced chemiluminescence assay also supported the above observations. These results clearly indicate that C. marina generates and releases the superoxide radical followed by the production of hydroxyl radical to the surrounding environment. The velocity of superoxide generation by C. marina was about 100 times faster than that by mammalian phagocytes per cell basis. The generation of oxygen radical is suggested to be a pathogenic principle in the toxication of red tide to susceptible aquaculture fishes and may be directly correlated with the coastal pollution by red tide.

  16. Fate of Earth Microbes on Mars -- UV Radiation Effects

    NASA Technical Reports Server (NTRS)

    Cockell, Charles

    2000-01-01

    A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment. Biological action spectra for DNA inactivation are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Although the present-day martian UV flux is similar to early earth and thus may not be a limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Here calculations for loss of microbial viability on the Pathfinder and Polar lander spacecraft are presented and the effects of martian dust on loss of viability are discussed. Details of the radiative transfer model are presented.

  17. Fate of Earth Microbes on Mars: UV Radiation Effects

    NASA Technical Reports Server (NTRS)

    Cockell, Charles

    2000-01-01

    A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment. Biological action spectra for DNA inactivation are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Although the present-day martian UV flux is similar to early earth and thus may not be a limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Here calculations for loss of microbial viability on the Pathfinder and Polar lander spacecraft are presented and the effects of martian dust on loss of viability are discussed. Details of the radiative transfer model are presented.

  18. Observation of 18.6-year modulation tide at the South Pole

    NASA Astrophysics Data System (ADS)

    Rydelek, P. A.; Knopoff, L.; Zürn, W.

    1982-07-01

    We have observed long-period variations in the amplitudes of the diurnal and semidiurnal gravity tides at the South Pole which we attribute to the tidal effects of the 18.6-year regression of the nodes of the lunar orbit. The observations are in agreement with theoretical values of the 18.6-year amplitude modulation of these tides.

  19. The Anomalously High Pole Tide in the North and Baltic Seas Estimated by the PSMSL Tide Gauge Data

    NASA Astrophysics Data System (ADS)

    Medvedev, Igor; Rabinovich, Alexander; Kulikov, Evgueni

    2014-05-01

    Pole tide driven by the Chandler wobble, has the period of about 14 months and typical amplitudes in the World Ocean of ~ 0.5 cm. However, in the North and Baltic Seas they are anomalously high. To examine this effect we used long monthly sea level records from 80 stations with the length up to 212 years. High-resolution spectra revealed a cluster of neighboring peaks with periods from 410 to 440 days. The results of spectral analysis were applied to estimate the integral amplitudes of pole tides from all available tide gauges along the coast of seas. The height of the pole tide was found to gradually increase from the entrance of the Baltic Sea (Danish Straits) to the northeast end of the Baltic Sea. The largest amplitudes - up to 4.5-7 cm - were observed in the heads of the Gulf of Finland and the Gulf of Bothnia. Significant temporal fluctuations in amplitudes and periods of the pole tide were observed during XIX and XX centuries.

  20. Storm Surge and Tide Interaction: A Complete Paradigm

    NASA Astrophysics Data System (ADS)

    Horsburgh, K.

    2014-12-01

    Estimates show that in 2005, in the largest 136 coastal cities, there were 40 million people and 3,000 billion of assets exposed to 1 in 100 year coastal flood events. Mean sea level rise will increase this exposure to 150 million people and 35,000 billion of assets by 2070. Any further change in the statistics of flood frequency or severity would impact severely on economic and social systems. It is therefore crucial to understand the physical drivers of extreme storm surges, and to have confidence in datasets used for extreme sea level statistics. Much previous research has focussed on the process of tide-surge interaction, and it is now widely accepted that the physical basis of tide-surge interaction is that a phase shift of the tidal signal represents the effect of the surge on the tide. The second aspect of interaction is that shallow water momentum considerations imply that differing tidal states should modulate surge generation: wind stress should have greater surge-generating potential on lower tides. We present results from a storm surge model of the European shelf that demonstrate that tidal range does have an effect on the surges generated. The cycle-integrated effects of wind stress (i.e. the skew surge) are greater when tidal range is low. Our results contradict the absence of any such correlation in tide gauge records. This suggests that whilst the modulating effect of the tide on the skew surge (the time-independent difference between peak prediction and observations) is significant, the difference between individual storms is dominant. This implies that forecasting systems must predict salient detail of the most intense storms. A further implication is that flood forecasting models need to simulate tides with acceptable accuracy at all coastal locations. We extend our model analysis to show that the same modulation of storm surges (by tidal conditions) applies to tropical cyclones. We conduct simulations using a mature operational storm surge model

  1. Storm surge and tide interaction: a complete paradigm

    NASA Astrophysics Data System (ADS)

    Horsburgh, Kevin; Williams, Jane; Proctor, Robert

    2014-05-01

    Globally, 200 million people live on coastal floodplains and about 1 trillion worth of assets lie within 1 metre of mean sea level. Any change in the statistics of flood frequency or severity would impact on economic and social systems. It is therefore crucial to understand the physical drivers of extreme storm surges, and to have confidence in datasets used for extreme sea level statistics. Much previous research has focussed on the process of tide-surge interaction, and it is now widely accepted that the physical basis of tide-surge interaction is that a phase shift of the tidal signal represents the effect of the surge on the tide. The second aspect of interaction is that shallow water momentum considerations imply that differing tidal states should modulate surge generation: wind stress should have greater surge-generating potential on lower tides. This has been shown previously by analytical models but not as yet confirmed by fully non-linear models of the continental shelf. We present results from an operational model of the European shelf that demonstrate that tidal range does have an effect on the surges generated. The cycle-integrated effects of wind stress (i.e. the skew surge) are generally greater when tidal range is low. Our results contradict the absence of any such correlation observed in the complete record of UK tide gauge data. This suggests that whilst the modulating effect of the tide on the skew surge (the time-independent difference between peak prediction and observations) is significant, the difference between individual storms is dominant. This implies that forecasting systems must predict salient detail of the most intense storms. A further implication is that operational models need to simulate tides with acceptable accuracy at all coastal locations. We extend our model analysis to show that the same modulation of storm surges (by tidal conditions) applies to tropical cyclones. We conduct simulations using a mature operational storm surge

  2. The Role of Tides in Known Multi-Planet Systems

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    The first known extrasolar planet system, upsilon Andromedae, was discovered in 1999. The number of stars known to possess more than one planet has been growing rapidly since then. The dynamical interactions among such planets can be quite strong. These interactions can excite the orbital eccentricities of planets, even planets orbiting very close to their stars. Stellar tides can damp the eccentricities of such close-in planets, removing dynamical energy from the system and ultimately affecting the motions of all of the planets. These and other effects of tides in extrasolar multi-planet systems will be discussed.

  3. Atomic oxygen effects on POSS polyimides in low earth orbit.

    PubMed

    Minton, Timothy K; Wright, Michael E; Tomczak, Sandra J; Marquez, Sara A; Shen, Linhan; Brunsvold, Amy L; Cooper, Russell; Zhang, Jianming; Vij, Vandana; Guenthner, Andrew J; Petteys, Brian J

    2012-02-01

    Kapton polyimde is extensively used in solar arrays, spacecraft thermal blankets, and space inflatable structures. Upon exposure to atomic oxygen in low Earth orbit (LEO), Kapton is severely eroded. An effective approach to prevent this erosion is to incorporate polyhedral oligomeric silsesquioxane (POSS) into the polyimide matrix by copolymerizing POSS monomers with the polyimide precursor. The copolymerization of POSS provides Si and O in the polymer matrix on the nano level. During exposure of POSS polyimide to atomic oxygen, organic material is degraded, and a silica passivation layer is formed. This silica layer protects the underlying polymer from further degradation. Laboratory and space-flight experiments have shown that POSS polyimides are highly resistant to atomic-oxygen attack, with erosion yields that may be as little as 1% those of Kapton. The results of all the studies indicate that POSS polyimide would be a space-survivable replacement for Kapton on spacecraft that operate in the LEO environment.

  4. Florida Red Tide Knowledge and Risk Perception: Is there a need for tailored messaging?

    PubMed Central

    Kirkpatrick, Barbara; Kohler, Kate; Byrne, Margaret M.; Studts, Jamie

    2013-01-01

    Harmful algal blooms of the toxic dinoflagellate, Karenia brevis, occur throughout the Gulf of Mexico. Recent research efforts sponsored by the National Institute of Environmental Health Sciences (NIEHS) and others found that Florida red tide causes both acute and possibly chronic health effects from the toxic aerosols. Florida red tide also demonstrated significant social and economic impacts to both coastal residents and visitors. In conjunction with the research, persistent outreach efforts were conducted over the 11 year period. The goal of this project was to assess potential needs for tailored messaging needed among different red tide information user groups. Survey participants included 303 local residents, both with asthma and without, and ‘snowbirds (seasonal residents that reside in the Sarasota area for more than 3 months but less than 6 months/year), also both with asthma and without. The questionnaire assessed Florida red tide knowledge and risk perception regarding Florida red tide using items drawn from two previously published surveys to allow comparison. Our results reveal that overall knowledge of Florida red tide has not changed. We found that knowledge was consistent across our selected groups and also did not vary by age, gender and education level. However, knowledge regarding consumption of seafood during Florida red tide has declined. Risk perception increased significantly for people who have asthma. Individuals responsible for public health communication regarding Florida red tide and human health concerns need to continue to pursue more effective outreach messages and delivery methods. PMID:24563634

  5. Florida Red Tide Knowledge and Risk Perception: Is there a need for tailored messaging?

    PubMed

    Kirkpatrick, Barbara; Kohler, Kate; Byrne, Margaret M; Studts, Jamie

    2014-02-01

    Harmful algal blooms of the toxic dinoflagellate, Karenia brevis, occur throughout the Gulf of Mexico. Recent research efforts sponsored by the National Institute of Environmental Health Sciences (NIEHS) and others found that Florida red tide causes both acute and possibly chronic health effects from the toxic aerosols. Florida red tide also demonstrated significant social and economic impacts to both coastal residents and visitors. In conjunction with the research, persistent outreach efforts were conducted over the 11 year period. The goal of this project was to assess potential needs for tailored messaging needed among different red tide information user groups. Survey participants included 303 local residents, both with asthma and without, and 'snowbirds (seasonal residents that reside in the Sarasota area for more than 3 months but less than 6 months/year), also both with asthma and without. The questionnaire assessed Florida red tide knowledge and risk perception regarding Florida red tide using items drawn from two previously published surveys to allow comparison. Our results reveal that overall knowledge of Florida red tide has not changed. We found that knowledge was consistent across our selected groups and also did not vary by age, gender and education level. However, knowledge regarding consumption of seafood during Florida red tide has declined. Risk perception increased significantly for people who have asthma. Individuals responsible for public health communication regarding Florida red tide and human health concerns need to continue to pursue more effective outreach messages and delivery methods.

  6. Turning the tide.

    PubMed

    Kahane, T

    1993-07-01

    It is estimated that 120,000-800,000 people in Vietnam out of a population of 67 million use injectable drugs for recreational purposes. Concurrently, HIV is spreading rapidly in the southern provinces of the country. The sharing of HIV-contaminated needles and injection equipment facilitate the dissemination of HIV so that more than 90% of the 332 cases of HIV infection officially notified by May 1993 are drug related. The most common injected drug is liquid opium. Large quantities of the drug are needed for the user to feel any effect, so large veins must be punctured with large needles. To realize this objective, each group of 20 IV-drug users (IVDU) tends to have its own skilled, yet untrained person who is paid to find and inject the opium in large veins in the leg or thigh. The same needle is used for everyone without sterilization. Funded by a group of American Vietnam war veterans, Jon Stuen-Parker, founder of the Boston-based National AIDS Brigade which provides AIDS information and runs needle exchange programs, visited Vietnam in March 1993 to establish a needle exchange program in the main areas of Ho Chi Minh City frequented by drug users. Unlike in the US, he was warmly received by officials and the program was implemented without controversy. Since IVDUs in this population do not self-inject, the report notes the need to educate only those who inject others about sterile needles and clean paraphernalia. Taking a different approach in recognition of the fact that needles are more expensive than liquid opium, CARE International proposes cleaning needles with bleach for both medical use and IVDUs. Accordingly, the Health Information and Education Center in Vietnam has produced literature promoting the bleach strategy which awaits approval for release. Stuen-Parker warns, however, that needles must soak for at least 30 seconds in 100% bleach to become sterile. He has planned a 2nd trip in July with the founder of the Vietnam Veterans with AIDS Committee

  7. Titan's Eccentricity Tides

    NASA Astrophysics Data System (ADS)

    Iess, L.; Jacobson, R.; Ducci, M.; Stevenson, D. J.; Lunine, J. I.; Armstrong, J. W.; Asmar, S.; Racioppa, P.; Rappaport, N. J.; Tortora, P.

    2011-12-01

    The large eccentricity (e=0.03) of Titan's orbit causes significant variations in the tidal field from Saturn and induces periodic stresses in the satellite body at the orbital period (about 16 days). Peak-to-peak variations of the tidal field (from pericenter to apocenter) are about 18% (6e). If Titan hosts a liquid layer (such as an internal ocean), the gravity field would exhibit significant periodic variations. The response of the body to fast variations of the external, perturbing field is controlled by the Love numbers, defined for each spherical harmonic as the ratio between the perturbed and perturbing potential. For Titan the largest effect is by far on the quadrupole field, and the corresponding Love number is indicated by k2 (assumed to be identical for all degree 2 harmonics). Models of Titan's interior generally envisage a core made up of silicates, surrounded by a layer of high pressure ice, possibly a liquid water or water-ammonia ocean, and an ice-I outer shell, with variations associated with the dehydration state of the core or the presence of mixed rock-ice layers. Previous analysis of Titan's tidal response [1] shows that k2 depends crucially on the presence or absence of an internal ocean. k2 was found to vary from about 0.03 for a purely rocky interior to 0.48 for a rigid rocky core surrounded by an ocean and a thin (20 km) ice shell. A large k2 entails changes in the satellite's quadrupole coefficients by a few percent, enough to be detected by accurate range rate measurements of the Cassini spacecraft. So far, of the many Cassini's flybys of Titan, six were used for gravity measurements. During gravity flybys the spacecraft is tracked from the antennas of NASA's Deep Space Network using microwave links at X- and Ka-band frequencies. A state-of-the-art instrumentation enables range rate measurements accurate to 10-50 micron/s at integration times of 60 s. The first four flybys provided the static gravity field and the moment of inertia factor

  8. How Tidal Forces Cause Ocean Tides in the Equilibrium Theory

    ERIC Educational Resources Information Center

    Ng, Chiu-king

    2015-01-01

    We analyse why it is erroneous to think that a tidal bulge is formed by pulling the water surface directly up by a local vertical tidal force. In fact, ocean tides are caused by the global effect of the horizontal components of the tidal forces.

  9. Analysis of earth rotation solution from Starlette

    NASA Technical Reports Server (NTRS)

    Schutz, B. E.; Cheng, M. K.; Shum, C. K.; Eanes, R. J.; Tapley, B. D.

    1989-01-01

    Earth rotation parameter (ERP) solutions were derived from the Starlette orbit analysis during the Main MERIT Campaign, using a technique of a consider-covariance analysis to assess the effects of errors on the polar motion solutions. The polar motion solution was then improved through the simultaneous adjustment of some dynamical parameters representing identified dominant perturbing sources (such as the geopotential and ocean-tide coefficients) on the polar motion solutions. Finally, an improved ERP solution was derived using the gravity field model, PTCF1, described by Tapley et al. (1986). The accuracy of the Starlette ERP solution was assessed by a comparison with the LAGEOS-derived ERP solutions.

  10. An Epidemiologic Approach to the Study of Aerosolized Florida Red Tides.

    PubMed

    Fleming, Lora E; Backer, Lorraine C; Kirkpatrick, Barbara; Clark, Richard; Dalpra, Dana; Johnson, David R; Bean, Judy A; Cheng, Yung Sung; Benson, Janet; Squicciarrini, Dominick; Abraham, William M; Pierce, Richard; Zaias, Julia; Naar, Jerome; Weisman, Richard; Bossart, Greg; Campbell, Susan; Wanner, Adam; Harrington, Mark; Van De Bogart, Gayl; Baden, Daniel G

    Very little has been published in the scientific literature on the human health effects of Florida red tide, either as human clinical case reports or formal epidemiologic studies. In addition to the health effects associated with the ingestion of contaminated shellfish, there have been multiple anecdotal reports of respiratory irritation and possible immunologic effects associated with the inhalation of aerosolized Florida red tide. To investigate the human health effects from environmental exposure to red tide toxins, we have formed an interdisciplinary team of scientists. We have created a network of public and environmental health workers who periodically report local conditions as a red tide develops. In addition, we have access to environmental monitoring data as well as data from a surveillance program supported through the Florida Poison Information Network. When a red tide moves onshore where people might be exposed, the team rapidly assembles at the site to collect environmental samples and epidemiologic data. To assess the more long-term effects from environmental exposure to red tide toxins, we are conducting epidemiologic studies involving occupational and sensitive populations who live in areas that are regularly impacted by red tides. Other scientists are evaluating the acute and chronic respiratory effects of red tides and brevetoxins in both rat and sheep models as well as refinement of toxin measurement methodology. These models are being used to refine and validate the biomarkers of brevetoxins exposure as well as explore the pathophysiology of health effects from brevetoxins respiratory exposure. Bolstered by the additional research in rat and sheep models, this interdisciplinary scientific team is exploring the acute and chronic exposures and health effects of aerosolized Florida red tides in animal models and various human populations. In the future, this research can be applied to the understanding of exposure and effects of other aerosolized

  11. The lunar nodal tide and the distance to tne Moon during the Precambrian era

    NASA Technical Reports Server (NTRS)

    Walker, J. C. G.; Zahnle, K. J.

    1986-01-01

    The origin and early evolution of life on Earth occurred under physical and chemical conditions distinctly different from those of the present day. The broad goal of this research program is to characterize these conditions. One aspect involves the dynamics of the Earth-Moon system, the distance of the Moon from the Earth, and the length of the day. These have evolved during the course of Earth history as a result of the dissipation of tidal energy. As the moon has receded the amplitude of oceanic tides has decreased while the increasing length of the day should have influenced climate and the circulation of atmosphere and ocean. A 23.3 year periodicity preserved in a 2500 million year old banded iron-formation was interpreted as reflecting the climatic influence of the lunar nodal tide. The corresponding lunar distance would then have been approx. 52 Earth radii. The influence of the lunar nodal tide is also apparent in rocks with an age of 680 million years B.P. The derived value for lunar distance 2500 million years ago is the only datum on the dynamics of the Earth-Moon system during the Precambrian era of Earth history. The implied development of Precambrian tidal friction is in accord with more recent paleontological evidence as well as the long term stability of the lunar orbit.

  12. Effects of the low Earth orbital environment on spacecraft materials

    NASA Technical Reports Server (NTRS)

    Leger, L. J.

    1986-01-01

    It is evident from space flights during the last three years that the low Earth orbital (LEO) environment interacts with spacecraft surfaces in significant ways. One manifestation of these interactions is recession of, in particular, organic-polymer-based surfaces presumably due to oxidation by atomic oxygen, the major component of the LEO environment. Three experiments have been conducted on Space Shuttle flights 5, 8 and 41-G to measure reaction rates and the effects of various parameters on reaction rates. Surface recession on these flights indicates reaction efficiencies approximately 3 x 10(-24) cu cm/atoms for unfilled organic polymers. Of the metals, silver and osmium are very reactive. Effects on spacecraft or experiment surfaces can be evaluated using the derived reaction efficiencies and a definition of the total exposure to atomic oxygen. This exposure is obtained using an ambient density model, solar activity data and spacecraft parameters of altitude, attitude and operational date. Oxygen flux on a given surface is obtained from the ambient density and spacecraft velocity and can then be integrated to provide the total exposure or fluence. Such information can be generated using simple computational programs and can be converted to various formats. Overall, the extent of damage is strongly dependent on the type of surface and total exposure time.

  13. Laboratory simulation of Low Earth Orbit (LEO) atomic oxygen effects

    NASA Technical Reports Server (NTRS)

    Caledonia, George E.; Krech, Robert H.; Oakes, David B.

    1994-01-01

    A pulsed fast oxygen atom source has been used extensively over the last 7 years to investigate the effects of ambient oxygen atoms impacting materials placed in low Earth orbit. In this period, we irradiated well over 2000 material samples with 8 km/s oxygen atoms generated in our source. Typical irradiance level is 3 x 10(exp 20) O atoms/sq cm although some materials have been irradiated to fluence levels as high as 6 x 10(exp 21) O atoms/sq cm. The operating principles and characteristics of our source are reviewed along with diagnostic and handling procedures appropriate to material testing. Representative data is presented on the velocity dependence of oxygen atom erosion rates (the PSI source provides oxygen atoms tunable over the velocity range of 5 to 12 km/s) as well as the dependence on material temperature. Specific examples of non-linear oxidative effects related to surface contamination and test duration are also be provided.

  14. Public perceptions of Florida red tide risks.

    PubMed

    Kuhar, Sara E; Nierenberg, Kate; Kirkpatrick, Barbara; Tobin, Graham A

    2009-07-01

    This research integrates theoretical frameworks of risk perception, social amplification of risk, and the role of place-specific contexts in order to explore the various perceptions surrounding Florida red tides. Florida red tides are naturally occurring events that are increasing in frequency, duration, and severity. This has implications for public health, the local economy, and ecosystem health. While many of the negative impacts of Florida red tides are not easily controlled, some of the secondary impacts may be mitigated through individuals' responses. However, public perception and consequent reactions to Florida red tides have not been investigated. This research uses questionnaire surveys, and semi-structured interviews, to explore the various perceptions of the risk surrounding red tides. Surveys and interviews were conducted along two Florida west coast beaches. The results indicate that the underlying foundations of the social amplification of the risk framework are applicable to understanding how individuals form perceptions of risk relative to red tide events. There are key differences between the spatial locations of individuals and corresponding perceptions, indicating that place-specific contexts are essential to understanding how individuals receive and interpret risk information. The results also suggest that individuals may be lacking efficient and up-to-date information about Florida red tides and their impacts because of inconsistent public outreach. Overall, social and spatial factors appear to be influential as to whether individuals amplify or attenuate the risks associated with Florida red tides.

  15. Internal Tide Generation by Steep Topography

    DTIC Science & Technology

    2007-09-01

    acting on the barotropic tide ( Foda and Hill 1998) was incomplete. Kunze will put this work in the context of recent internal tide research and...Topographically generated internal waves in the open ocean. J. Geophys. Res., 80, 320-327. Foda , M.A., and D.F. Hill, 1998: Nonlinear energy

  16. Earth curvature and atmospheric refraction effects on radar signal propagation.

    SciTech Connect

    Doerry, Armin Walter

    2013-01-01

    The earth isnt flat, and radar beams dont travel straight. This becomes more noticeable as range increases, particularly at shallow depression/grazing angles. This report explores models for characterizing this behavior.

  17. Effects of differentiation on the geodynamics of the early Earth

    NASA Astrophysics Data System (ADS)

    Piccolo, Andrea; Kaus, Boris; White, Richard; Johnson, Tim

    2016-04-01

    Archean geodynamic processes are not well understood, but there is general agreement that the mantle potential temperature was higher than present, and that as a consequence significant amounts of melt were produced both in the mantle and any overlying crust. This has likely resulted in crustal differentiation. An early attempt to model the geodynamic effects of differentiation was made by Johnson et al. (2014), who used numerical modeling to investigate the crust production and recycling in conjunction with representative phase diagrams (based on the inferred chemical composition of the primary melt in accordance with the Archean temperature field). The results of the simulations show that the base of the over-thickened primary basaltic crust becomes gravitational unstable due to the mineral assemblage changes. This instability leads to the dripping of dense material into the mantle, which causes an asthenospheric return flow, local partial melting and new primary crust generation that is rapidly recycled in to mantle. Whereas they gave important insights, the previous simulations were simplified in a number of aspects: 1) the rheology employed was viscous, and both elasticity and pressure-dependent plasticity were not considered; 2) extracted mantle melts were 100% transformed into volcanic rocks, whereas on the present day Earth only about 20-30% are volcanic and the remainder is plutonic; 3) the effect of a free surface was not studied in a systematic manner. In order to better understand how these simplifications affect the geodynamic models, we here present additional simulations to study the effects of each of these parameters. Johnson, T.E., Brown, M., Kaus, B., and VanTongeren, J.A., 2014, Delamination and recycling of Archaean crust caused by gravitational instabilities: Nature Geoscience, v. 7, no. 1, p. 47-52, doi: 10.1038/NGEO2019.

  18. Effects of simulated rare earth recycling wastewaters on biological nitrification

    DOE PAGES

    Fujita, Yoshiko; Barnes, Joni; Eslamimanesh, Ali; ...

    2015-07-16

    Current efforts to increase domestic availability of rare-earth element (REE) supplies by recycling and expanded ore processing efforts will result in increased generation of associated wastewaters. In some cases disposal to a sewage treatment plant may be favored but plant performance must be maintained. To assess the potential effects of such wastewaters on biological wastewater treatment, model nitrifying organisms Nitrosomonas europaea and Nitrobacter winogradskyi were exposed to simulated wastewaters containing varying levels of yttrium or europium (10, 50 and 100 ppm), and the REE extractant tributyl phosphate (TBP, at 0.1 g/L). Y and Eu additions above 10 ppm inhibited N.more » europaea activity, even when initially virtually all of the REE was insoluble. The provision of TBP together with Eu increased inhibition of nitrite production by the N. europaea, although TBP alone did not substantially alter nitrifying activity N. winogradskyi was more sensitive to the stimulated wastewaters, with even 10 ppm Eu or Y inducing significant inhibition, and a complete shutdown of nitrifying activity occurred in the presence of the TBP. To analyze the availability of REEs in aqueous solutions, REE solubility has been calculated using the previously developed MSE (Mixed-Solvent Electrolyte) thermodynamic model. The model calculations reveal a strong pH dependence of solubility, which is typically controlled by the precipitation of REE hydroxides but may also be influenced by the formation of a phosphate phase.« less

  19. Effects of simulated rare earth recycling wastewaters on biological nitrification

    SciTech Connect

    Fujita, Yoshiko; Barnes, Joni; Eslamimanesh, Ali; Lencka, Malgorzata M.; Anderko, Andrzej; Riman, Richard E.; Navrotsky, Alexandra

    2015-07-16

    Current efforts to increase domestic availability of rare-earth element (REE) supplies by recycling and expanded ore processing efforts will result in increased generation of associated wastewaters. In some cases disposal to a sewage treatment plant may be favored but plant performance must be maintained. To assess the potential effects of such wastewaters on biological wastewater treatment, model nitrifying organisms Nitrosomonas europaea and Nitrobacter winogradskyi were exposed to simulated wastewaters containing varying levels of yttrium or europium (10, 50 and 100 ppm), and the REE extractant tributyl phosphate (TBP, at 0.1 g/L). Y and Eu additions above 10 ppm inhibited N. europaea activity, even when initially virtually all of the REE was insoluble. The provision of TBP together with Eu increased inhibition of nitrite production by the N. europaea, although TBP alone did not substantially alter nitrifying activity N. winogradskyi was more sensitive to the stimulated wastewaters, with even 10 ppm Eu or Y inducing significant inhibition, and a complete shutdown of nitrifying activity occurred in the presence of the TBP. To analyze the availability of REEs in aqueous solutions, REE solubility has been calculated using the previously developed MSE (Mixed-Solvent Electrolyte) thermodynamic model. The model calculations reveal a strong pH dependence of solubility, which is typically controlled by the precipitation of REE hydroxides but may also be influenced by the formation of a phosphate phase.

  20. Satellite Motion Effects on Current Collection in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Zhang, T. X.; Hwang, K. S.; Wu, S. T.; Stone, N. H.; Chang, C. L.; Drobot, A.; Wright, K. H., Jr.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Results from the Tethered Satellite System (TSS) missions unambiguously show that the electrodynamic tether system produced 2 to 3 times the predicted current levels in the tether. The pre-mission predictions were based on the well-known Parker-Murphy (PM) model, which describes the collection of current by an electrically biased satellite in the ionospheric plasma. How the TSS satellite was able to collect 2-3 times the PM current has remained an open question. In the present study, self-consistent potential and motional effects are introduced into the Thompson and Dobrowolny sheath models. As a result, the magnetic field aligned sheath-an essential variable in determining current collection by a satellite-is derived and is shown to be explicitly velocity dependent. The orientation of the satellite's orbital motion relative to the geomagnetic field is also considered in the derivation and a velocity dependent expression for the collected current is obtained. The resulting model provides a realistic treatment of current collection by a satellite in low earth orbit. Moreover, the predictions, using the appropriate parameters for TSS, are in good agreement with the tether currents measured during the TSS-1R mission.

  1. Effects of Simulated Rare Earth Recycling Wastewaters on Biological Nitrification.

    PubMed

    Fujita, Yoshiko; Barnes, Joni; Eslamimanesh, Ali; Lencka, Malgorzata M; Anderko, Andrzej; Riman, Richard E; Navrotsky, Alexandra

    2015-08-18

    Increasing rare earth element (REE) supplies by recycling and expanded ore processing will result in generation of new wastewaters. In some cases, disposal to a sewage treatment plant may be favored, but plant performance must be maintained. To assess the potential effects of such wastewaters on biological treatment, model nitrifying organisms Nitrosomonas europaea and Nitrobacter winogradskyi were exposed to simulated wastewaters containing varying levels of yttrium or europium (10, 50, and 100 ppm), and the extractant tributyl phosphate (TBP, at 0.1 g/L). Y and Eu additions at 50 and 100 ppm inhibited N. europaea, even when virtually all of the REE was insoluble. Provision of TBP with Eu increased N. europaea inhibition, although TBP alone did not substantially alter activity. For N. winogradskyi cultures, Eu or Y additions at all tested levels induced significant inhibition, and nitrification shut down completely with TBP addition. REE solubility was calculated using the previously developed MSE (Mixed-Solvent Electrolyte) thermodynamic model. The model calculations reveal a strong pH dependence of solubility, typically controlled by the precipitation of REE hydroxides but also likely affected by the formation of unknown phosphate phases, which determined aqueous concentrations experienced by the microorganisms.

  2. Observations and Effects of Dipolarization Fronts Observed in Earth's Magnetotail

    NASA Technical Reports Server (NTRS)

    Goldstein, Melvyn L.

    2011-01-01

    Dipolarization fronts in Earth's magnetotail are characterized by sharp jumps in magnetic field, a drop in density, and often follow earthward fast plasma flow. They are commonly detected near the equatorial plane of Earth s tail plasma sheet. Sometimes, but not always, dipolarization fronts are associated with global substorms and auroral brightenings. Both Cluster, THEMIS, and other spacecraft have detected dipolarization fronts in a variety of locations in the magnetotail. Using multi-spacecraft analyses together with simulations, we have investigated the propagation and evolution of some dipolarization events. We have also investigated the acceleration of electrons and ions that results from such magnetic-field changes. In some situations, the velocities of fast earthward flows are comparable to the Alfven speed, indicating that the flow bursts might have been generated by bursty reconnection that occurred tailward of the spacecraft. Based on multi-spacecraft timing analysis, dipolarization fronts are found to propagate mainly earthward at 160-335 km/s and have thicknesses of 900-1500 km, which corresponds to the ion inertial length or gyroradius scale. Following the passage of dipolarization fronts, significant fluctuations are observed in the x and y components of the magnetic field. These peaks in the magnetic field come approximately 1-2 minutes after passage of the dipolarization front. These Bx and By fluctuations propagate primarily dawnward and earthward. Field-aligned electron beams are observed coincident with those magnetic field fluctuations. Non-Maxwellian electron and ion distributions are observed that are associated with the dipolarization that may be unstable to a range of electrostatic and/or whistler instabilities. Enhanced electrostatic broadband noise at frequencies below and near the lower-hybrid frequency is also observed at or very close to these fronts. This broadband noise is thought to play a role in further energizing the particles

  3. Effects of Low Earth Orbit on Docking Seal Materials

    NASA Technical Reports Server (NTRS)

    Imka, Emily C.; Asmar, Olivia C.; deGroh, Henry C., III; Banks, Bruce A.

    2014-01-01

    Spacecraft docking seals are typically made of silicone elastomers. When such seals are exposed to low Earth orbit (LEO) conditions, they can suffer damage from ultraviolet (UV) radiation and atomic oxygen (AO, or monoatomic oxygen, the predominant oxygen species in LEO). An experiment flew on the International Space Station (ISS) to measure the effects of LEO on seal materials S0383-70 and ELA-SA-401 and various mating counterface materials which included anodized aluminum. Samples flown in different orientations received different amounts of UV and AO. The hypotheses were that most of the damage would be from UV, and 10 days or more of exposure in LEO would badly damage the seals. Eighteen seals were exposed for 543 days in ram (windward), zenith (away from Earth), or wake (leeward) orientations, and 15 control samples (not flown) provided undamaged baseline leakage. To determine post-flight leak rates, each of the 33 seals were placed in an O-ring groove of a leak test fixture and pressure tested over time. Resistance temperature detectors (RTDs), pressure transducers, and LabVIEW (National Instruments) programs were used to measure and analyze the temperature and pressure and calculate leakage. Average leakage of control samples was 2.6 x 10(exp -7) lbs/day. LEO exposure did not considerably damage ELA-SA-401. The S0383-70 flight samples leaked at least 10 times more than ELA-SA-401 in all cases except one, demonstrating that ELA-SA-401 may be a more suitable sealing material in LEO. AO caused greater damage than UV; samples in ram orientation (receiving an AO fluence of 4.3 x 10(exp 21) atoms/(sq cm) and in wake (2.9x 10(exp 20) atoms/(sq cm)) leaked more than those in zenith orientation (1.58 x 10(exp 20) atoms/(sq cm)), whereas variations in UV exposure did not seem to affect the samples. Exposure to LEO did less damage to the seals than hypothesized, and the data did not support the conjecture that UV causes more damage than AO.

  4. The Art of Red Tide Science.

    PubMed

    Hall, Emily R; Nierenberg, Kate; Boyes, Anamari J; Heil, Cynthia A; Flewelling, Leanne J; Kirkpatrick, Barbara

    2012-05-01

    Over the years, numerous outreach strategies by the science community, such as FAQ cards and website information, have been used to explain blooms of the toxic dinoflagellate, Karenia brevis that occur annually off the west coast of Florida to the impacted communities. Many state and federal agencies have turned to funded research groups for assistance in the development and testing of environmental outreach products. In the case of Florida red tide, the Fish and Wildlife Research Institute/Mote Marine Laboratory (MML) Cooperative Red Tide Agreement allowed MML to initiate a project aimed at developing innovative outreach products about Florida red tide. This project, which we coined "The Art of Red Tide Science," consisted of a team effort between scientists from MML and students from Ringling College of Art and Design. This successful outreach project focused on Florida red tide can be used as a model to develop similar outreach projects for equally complex ecological issues.

  5. Comparison of relativistic effects in barycentric and Earth-centered coordinates and implications for determination of GM for Earth

    NASA Technical Reports Server (NTRS)

    Ashby, Neil

    1987-01-01

    The results of an investigation of relativistic effects which have an influence on the determination of GM sub E (M sub E is the mass of the Earth, G is the Newtonian gravitaional constant) are summarized. The detailed arguments and derivations are discussed. The Parametrized Post-Newtonian (PPN) coordinates; Eddington-Clark (EC) coordinates; a coordinate system based on barycentric dynamical time (TBC coordinates); and Local Inertial coordinates are discussed.

  6. Environmental Chemistry and Chemical Ecology of "Green Tide" Seaweed Blooms.

    PubMed

    Van Alstyne, Kathryn L; Nelson, Timothy A; Ridgway, Richard L

    2015-09-01

    Green tides are large growths or accumulations of green seaweeds that have been increasing in magnitude and frequency around the world. Because green tides consist of vast biomasses of algae in a limited area and are often seasonal or episodic, they go through periods of rapid growth in which they take up large amounts of nutrients and dissolved gases and generate bioactive natural products that may be stored in the plants, released into the environment, or broken down during decomposition. As a result of the use and production of inorganic and organic compounds, the algae in these blooms can have detrimental impacts on other organisms. Here, we review some of the effects that green tides have on the chemistry of seawater and the effects of the natural products that they produce. As blooms are developing and expanding, algae in green tides take up inorganic nutrients, such as nitrate and ortho-phosphate, which can limit their availability to other photosynthetic organisms. Their uptake of dissolved inorganic carbon for use in photosynthesis can cause localized spikes in the pH of seawater during the day with concomitant drops in the pH at night when the algae are respiring. Many of the algae that form green-tide blooms produce allelopathic compounds, which are metabolites that affect other species. The best documented allelopathic compounds include dimethylsulfoniopropionate (DMSP), dopamine, and reactive oxygen species (ROS) and their breakdown products. DMSP and dopamine are involved in defenses against herbivores. Dopamine and ROS are released into seawater where they can be allelopathic or toxic to other organisms. Thus, these macroalgal blooms can have harmful effects on nearby organisms by altering concentrations of nutrients and dissolved gas in seawater and by producing and releasing allelopathic or toxic compounds.

  7. Thermospheric energy flux of the semidiurnal tide

    NASA Astrophysics Data System (ADS)

    Groves, G. V.

    1983-10-01

    The upward energy flux of the (2,2,2) mode of atmospheric oscillation generated by water vapor and ozone radiational heating is calculated at 125 km for mean January, April, July and October conditions. The values obtained for the global mean flux lie close to 0.05 mW per sq m with a small reduction in July amounting to 13 percent of the average for the other 3 months. The effect of semidiurnal tidal heating on exospheric temperature is discussed with reference to the earlier work of Lindzen and Blake (1970) and it is concluded that the semidiurnal tide causes a relatively small increase in exospheric temperature of about 33 K.

  8. On the tidal oscillations of the liquid core of the earth

    NASA Technical Reports Server (NTRS)

    Musen, P.

    1978-01-01

    An important goal of a tidal theory is the improvement of nutational amplitude and of the parameters of the earth's elastic response. A theory of tidal oscillations inside a rotating elliptical earth was developed, with special emphasis on tides in the liquid core. The Molodensky and Kramer theory of the resonance effect, as caused by the proximity of the frequency of the free diurnal wobble of the liquid core to the frequency of K sub 1 astronomical tide, was amended to include the effect of the possible deviation of the liquid core from the state of neutral stability. Coupling effects between the toroidal and spheroidal oscillations, as caused by the Coriolis force, were taken into consideration.

  9. Differential Responses of Net Ecosystem Exchange of Carbon Dioxide to Light and Temperature between Spring and Neap Tides in Subtropical Mangrove Forests

    PubMed Central

    Li, Qing; Lu, Weizhi; Chen, Hui; Luo, Yiqi; Lin, Guanghui

    2014-01-01

    The eddy flux data with field records of tidal water inundation depths of the year 2010 from two mangroves forests in southern China were analyzed to investigate the tidal effect on mangrove carbon cycle. We compared the net ecosystem exchange (NEE) and its responses to light and temperature, respectively, between spring tide and neap tide inundation periods. For the most time of the year 2010, higher daytime NEE values were found during spring tides than during neap tides at both study sites. Regression analysis of daytime NEE to photosynthetically active radiation (PAR) using the Landsberg model showed increased sensitivity of NEE to PAR with higher maximum photosynthetic rate during spring tides than neap tides. In contrast, the light compensation points acquired from the regression function of the Landsberg model were smaller during spring tides than neap tides in most months. The dependence of nighttime NEE on soil temperature was lower under spring tide than under neap tides. All these results above indicated that ecosystem carbon uptake rates of mangrove forests were strengthened, while ecosystem respirations were inhibited during spring tides in comparison with those during neap tides, which needs to be considered in modeling mangrove ecosystem carbon cycle under future sea level rise scenarios. PMID:25133267

  10. Differential responses of net ecosystem exchange of carbon dioxide to light and temperature between spring and neap tides in subtropical mangrove forests.

    PubMed

    Li, Qing; Lu, Weizhi; Chen, Hui; Luo, Yiqi; Lin, Guanghui

    2014-01-01

    The eddy flux data with field records of tidal water inundation depths of the year 2010 from two mangroves forests in southern China were analyzed to investigate the tidal effect on mangrove carbon cycle. We compared the net ecosystem exchange (NEE) and its responses to light and temperature, respectively, between spring tide and neap tide inundation periods. For the most time of the year 2010, higher daytime NEE values were found during spring tides than during neap tides at both study sites. Regression analysis of daytime NEE to photosynthetically active radiation (PAR) using the Landsberg model showed increased sensitivity of NEE to PAR with higher maximum photosynthetic rate during spring tides than neap tides. In contrast, the light compensation points acquired from the regression function of the Landsberg model were smaller during spring tides than neap tides in most months. The dependence of nighttime NEE on soil temperature was lower under spring tide than under neap tides. All these results above indicated that ecosystem carbon uptake rates of mangrove forests were strengthened, while ecosystem respirations were inhibited during spring tides in comparison with those during neap tides, which needs to be considered in modeling mangrove ecosystem carbon cycle under future sea level rise scenarios.

  11. Atmospheric Tides in Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Guzewich, Scott D,; Newman, C. E; de la Torre Juarez, M.; Wilson, R. J.; Lemmon, M.; Smith, M. D.; Kahanpaa, H.; Harri, A.-M.

    2015-01-01

    Atmospheric tides are the primary source of daily air pressure variation at the surface of Mars. These tides are forced by solar heating of the atmosphere and modulated by the presence of atmospheric dust, topography, and surface albedo and thermal inertia. This results in a complex mix of sun-synchronous and nonsun- synchronous tides propagating both eastward and westward around the planet in periods that are integer fractions of a solar day. The Rover Environmental Monitoring Station on board the Mars Science Laboratory has observed air pressure at a regular cadence for over 1 Mars year and here we analyze and diagnose atmospheric tides in this pressure record. The diurnal tide amplitude varies from 26 to 63 Pa with an average phase of 0424 local true solar time, while the semidiurnal tide amplitude varies from 5 to 20 Pa with an average phase of 0929. We find that both the diurnal and semidiurnal tides in Gale Crater are highly correlated to atmospheric opacity variations at a value of 0.9 and to each other at a value of 0.77, with some key exceptions occurring during regional and local dust storms. We supplement our analysis with MarsWRF general circulation modeling to examine how a local dust storm impacts the diurnal tide in its vicinity. We find that both the diurnal tide amplitude enhancement and regional coverage of notable amplitude enhancement linearly scales with the size of the local dust storm. Our results provide the first long-term record of surface pressure tides near the martian equator.

  12. [Mechanisms of removing red tide organisms by organo-clays].

    PubMed

    Cao, Xi-Hua; Song, Xiu-Xian; Yu, Zhi-Ming; Wang, Kui

    2006-08-01

    We tested the influence of the preparation conditions of the quaternary ammonium compounds (QACs) modified clays on their capacities to remove red tide organisms, then discussed the mechanisms of the organo-clays removing red tide organisms. Hexadecyltrimethylammonium (HDTMA) improved the capacity of clays to flocculate red tide algae, and the HDTMA in metastable state enhanced the toxicity of the clay complexes to algae. The capacities of the organo-clays correlated with the toxicity and the adsorbed amount of the QACs used in clays modification, but as the incubation time was prolonged the stability of the organo-clays was improved and the algal removal efficiencies of the clay complexes decreased. When the adsorbed HDTMA was arranged in different clays in which the spatial resistance was different, there was more HDTMA in metastable state in the three-layer montmorillonite. Because of the homo-ion effect the bivalent or trivalent metal ions induced more HDTMA in metastable state and the corresponding organo-clays had high capacities to remove red tide organisms. When the reaction temperature was 60 degrees C the adsorbed HDTMA was easily arranged on cation exchange sites, if the temperature rose or fell the metastable HDTMA would increase so that the capacity of the clays was improved.

  13. Atmospheric attenuation relative to earth-viewing orbital sensors. [atmospheric moisture effects on microwaves

    NASA Technical Reports Server (NTRS)

    Brown, S. C.; Jayroe, R. R., Jr.

    1973-01-01

    Earth viewing space missions offer exciting new possibilities in several earth resources disciplines - geography, hydrology, agriculture, geology, and oceanography, to name a few. A most useful tool in planning experiments and applying space technology to earth observation is a statistical description of atmospheric parameters. Four dimensional atmospheric models and a world wide cloud model are used to produce atmospheric attenuation models to predict degradation effects for all classes of sensors for application to earth sensing experiments from spaceborne platforms. To insure maximum utility and application of these products, the development of an interaction model of microwave energy and atmospheric variables provides a complete description of the effects of atmospheric moisture upon microwaves.

  14. Assessing change of environmental dynamics by legislation in Japan, using red tide occurrence in Ise Bay as an indicator.

    PubMed

    Suzuki, Chika

    2016-01-30

    Tokyo Bay, Ise Bay, and the Seto Inland Sea are the total pollutant load control target areas in Japan. A significant correlation between the incidence of red tides and water quality has been observed in the Seto Inland Sea (Honjo, 1991). However, while red tides also occur in Ise Bay and Tokyo Bay, similar correlations have not been observed. Hence, it is necessary to understand what factors cause red tides to effectively manage these semi-closed systems. This study aims to investigate the relationship between the dynamics of the Red Tide Index and nitrogen regulation as well as phosphorus regulation, even in Ise Bay where, unlike Tokyo Bay, there are few observation items, by selecting a suitable objective variable. The introduction of a new technique that uses the Red Tide Index has revealed a possibility that the total pollution load control has influenced the dynamics of red tide blooms in Ise Bay.

  15. The Effect of the Earth's Atmosphere on LSST Photometry

    SciTech Connect

    Rahlin, Alexandra S.; /MIT /SLAC

    2006-08-30

    The Large Synoptic Survey Telescope (LSST), a ground-based telescope currently under development, will allow a thorough study of dark energy by measuring, more completely and accurately than previously, the rate of expansion of the universe and the large-scale structure of the matter in it. The telescope utilizes a broadband photometric system of six wavelength bands to measure the redshifts of distant objects. The earth's atmosphere makes it difficult to acquire accurate data, since some of the light passing through the atmosphere is scattered or absorbed due to Rayleigh scattering, molecular absorption, and aerosol scattering. Changes in the atmospheric extinction distribution due to each of these three processes were simulated by altering the parameters of a sample atmospheric distribution. Spectral energy distributions of standard stars were used to simulate data acquired by the telescope. The effects of changes in the atmospheric parameters on the photon flux measurements through each wavelength band were observed in order to determine which atmospheric conditions must be monitored most closely to achieve the desired 1% uncertainty on flux values. It was found that changes in the Rayleigh scattering parameter produced the most significant variations in the data; therefore, the molecular volume density (pressure) must be measured with at most 8% uncertainty. The molecular absorption parameters produced less significant variations and could be measured with at most 62% uncertainty. The aerosol scattering parameters produced almost negligible variations in the data and could be measured with > 100% uncertainty. These atmospheric effects were found to be almost independent of the redshift of the light source. The results of this study will aid the design of the atmospheric monitoring systems for the LSST.

  16. Satellite-tracking and Earth dynamics research programs

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Tracking of LAGEOS for polar motion and Earth rotation studies and for other geophysical investigations, including crustal dynamics, Earth and ocean tides, and the general development of precision orbit determination continues. The BE-C and Starlette satellites were tracked for refined determinations of station coordinates and the Earth's gravity field and for studies of solid Earth dynamics.

  17. Oceanic tides from Geosat altimetry

    NASA Technical Reports Server (NTRS)

    Cartwright, D. E.; Ray, R. D.

    1990-01-01

    Direct tidal analysis of the altimetry from the Geosat Exact Repeat Mission's first year is used to derive estimates of the diurnal and semidiurnal oceanic tides. The geoid is removed by collinear differences at 34.1-day separation, and the orbit error is reduced by subtracting a slowly modulated 1-cycle/revolution term. A sequence of independent analyses at grid areas of 1 deg latitude x 1.5 deg longitude using 'orthotide' functions ensures complete definition of the diurnal and semidiurnal species. Global admittance maps for M2 and S2 within the latitudes 58 deg N and 59 deg S compare well with ground truth at 66 open-ocean sites. Maps of differences between Geosat and the Naval Surface Weapons Center model show important areas of the order of 10-15 cm.

  18. Mesospheric Non-Migrating Tides Generated With Planetary Waves: II Influence of Gravity Waves

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Mengel, J. G.; Talaat, E. L.; Porter, H. S.; Chan, K. L.

    2003-01-01

    We demonstrated that, in our model, non-linear interactions between planetary waves (PW) and migrating tides could generate in the upper mesosphere non-migrating tides with amplitudes comparable to those observed. The Numerical Spectral Model (NSM) we employ incorporates Hines Doppler Spread Parameterization for small-scale gravity waves (GW), which affect in numerous ways the dynamics of the mesosphere. The latitudinal (seasonal) reversals in the temperature and zonal circulation, which are largely caused by GWs (Lindzen, 198l), filter the PWs and contribute to the instabilities that generate the PWs. The PWs in turn are amplified by the momentum deposition of upward propagating GWs, as are the migrating tides. The GWs thus affect significantly the migrating tides and PWs, the building blocks of non-migrating tides. In the present paper, we demonstrate that GW filtering also contributes to the non-linear coupling between PWs and tides. Two computer experiments are presented to make this point. In one, we simply turn off the GW source to show the effect. In the second case, we demonstrate the effect by selectively suppressing the momentum source for the m = 0 non-migrating tides.

  19. Unusual locations of Earth`s bow shock on September 24-25, 1987: Mach number effects

    SciTech Connect

    Cairns, I.H.; Anderson, R.R.; Fairfield, D.H.; Carlton, V.E.H.; Paularena, K.I.; Lazarus, A.J.

    1995-01-01

    ISEE 1 and IMP 8 data are used to identify 19 crossings of Earth`s bow shock during a 30-hour period following 0000 UT on September 24, 1987. Apparent standoff distances for the shock are calculated for each crossing using two methods and the spacecraft location; one method assumes the average shock shape, while the other assumes a ram pressure-dependent shock shape. The shock`s apparent standoff distance normally {approximately}14 R{sub E}, is shown to increase from near 10 R{sub E} initially to near 19 R{sub E}. The Alfven M{sub A} and fast magnetosonic M{sub ms} Mach numbers remain above 2 and the number density above 4 cm{sup {minus}3} for almost the entire period. Ram pressure effects produce the initial near-Earth shock location, whereas expansions and contractions of the bow shock due to low Mach number effects account, qualitatively and semiquantitatively, for the timing and existence of almost all the remaining ISEE crossings and both IMP 8 crossings. Ram pressure-induced changes in the shock`s shape are discussed but found to be quantitatively unimportant for the shock crossings analyzed. Approximate estimates of both the deviation of the shock`s standoff distance from the standard model and of the shock`s shape are determined independently (but not consistently) for M{sub ms}{approximately}2.4. The estimates imply substantial changes in standoff distance and/or shock shape at low M{sub A} and M{sub ms}. Mach number effects can therefore be quantitatively important in determining and predicting the shape and location of the bow shock, even when M{sub A} and M{sub ms} remain above 2. This study confirms and generalizes previous studies of Mach number effects on Earth`s bow shock. Statistical studies and simulations of the bow shock`s shape and location should be performed as a function of Mach number, magnetic field orientation, and ram pressure. 25 refs., 12 figs.

  20. Solar rotation effects on the thermospheres of Mars and Earth.

    PubMed

    Forbes, Jeffrey M; Bruinsma, Sean; Lemoine, Frank G

    2006-06-02

    The responses of Earth's and Mars' thermospheres to the quasi-periodic (27-day) variation of solar flux due to solar rotation were measured contemporaneously, revealing that this response is twice as large for Earth as for Mars. Per typical 20-unit change in 10.7-centimeter radio flux (used as a proxy for extreme ultraviolet flux) reaching each planet, we found temperature changes of 42.0 +/- 8.0 kelvin and 19.2 +/- 3.6 kelvin for Earth and Mars, respectively. Existing data for Venus indicate values of 3.6 +/- 0.6 kelvin. Our observational result constrains comparative planetary thermosphere simulations and may help resolve existing uncertainties in thermal balance processes, particularly CO2 cooling.

  1. Geocenter location and variations in earth orientation using global positioning system measurements

    NASA Technical Reports Server (NTRS)

    Malla, R. P.; Wu, S. C.; Lichten, S. M.

    1993-01-01

    We have studied the use of GPS ground and flight tracking data to measure short-period earth orientation variations and changes in geocenter location. Comparisons between GPS-estimated earth rotation variations and those calculated from ocean tide models suggest that observed subdaily variations in earth rotation are dominated by oceanic tidal effects. Our preliminary GPS estimates for geocenter location agree with an independent satellite laser ranging estimates to 10-15 cm. Covariance analysis predicts that temporal resolution of GPS estimates for earth orientation and geocenter improves significantly when data collected from low earth-orbiting satellites as well as from ground sites are combined. The low-earth GPS tracking data enhance the accuracy and resolution for measuring high-frequency global geodynamical signals over time scales less than 1 day.

  2. Nonmigrating diurnal tides in the equatorial middle atmosphere

    SciTech Connect

    Lieberman, R.S.

    1992-01-01

    Data from the Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS) are used to analyze the diurnal tides in the middle atmosphere. A novel aspect of this study is the emphasis on the relative importance of the nonmigrating components. These modes display a high degree of temporal variability during the LIMS observing period, and contribute substantially to the diurnal signal in wind and temperature. Their observed vertical phase variations are variable; however there is evidence for upward energy propagation. It has long been hypothesized that nonmigrating tides are driven by the diurnally-varying zonally asymmetric tropospheric heating constituents. This premise is examined by employing a linear tidal model to simulate the response of the atmosphere to realistic tidal drives. These quantities are calculated from the NCAR Community Climate Model. The large-scale CCM2 diurnal surface pressure, OLR and hydrology are well simulated under July and January conditions. The CCM2 diurnal fields of short-wave radiative, convective and diffusive PBL heating are used as input to a linear tidal model with Newtonian cooling. This model successfully reproduces many observed features of the migrating and nonmigrating diurnal surface pressure tides at low latitudes. In the middle atmosphere, tropospheric solar heating is the dominant source of the migrating tide. The zonal means and eastward migrating wavenumber one components are also associated with radiative heating. The eastward migrating wavenumber three pattern is strongly linked to the dry and moist convective heating as well. The observed eastward migrating tides are harder to simulate, due in part to the failure of the linear model to incorporate the dissipative effects to which they are prone.

  3. The effect of aerosols on the earth-atmosphere albedo

    NASA Technical Reports Server (NTRS)

    Herman, B. M.; Browning, S. R.

    1975-01-01

    The paper presents calculations of the change in reflected flux by the earth-atmosphere system in response to increases in the atmospheric aerosol loading for a range of complex indices of refraction, solar elevation angle and ground albedo. Results show that, for small values of ground albedo, the reflected solar flux may either increase or decrease with increasing aerosol loadings, depending upon the complex part of the index of refraction of the aerosols. For high ground albedos, an increase in aerosol levels always results in a decrease of reflected flux (i.e., a warming of the earth-atmosphere system).

  4. COLORS OF A SECOND EARTH. II. EFFECTS OF CLOUDS ON PHOTOMETRIC CHARACTERIZATION OF EARTH-LIKE EXOPLANETS

    SciTech Connect

    Fujii, Yuka; Suto, Yasushi; Turner, Edwin L.; Kawahara, Hajime; Fukuda, Satoru; Nakajima, Teruyuki; Livengood, Timothy A.

    2011-09-10

    As a test bed for future investigations of directly imaged terrestrial exoplanets, we present the recovery of the surface components of the Earth from multi-band diurnal light curves obtained with the EPOXI spacecraft. We find that the presence and longitudinal distribution of ocean, soil, and vegetation are reasonably well reproduced by fitting the observed color variations with a simplified model composed of a priori known albedo spectra of ocean, soil, vegetation, snow, and clouds. The effect of atmosphere, including clouds, on light scattered from surface components is modeled using a radiative transfer code. The required noise levels for future observations of exoplanets are also determined. Our model-dependent approach allows us to infer the presence of major elements of the planet (in the case of the Earth, clouds, and ocean) with observations having signal-to-noise ratio (S/N) {approx}> 10 in most cases and with high confidence if S/N {approx}> 20. In addition, S/N {approx}> 100 enables us to detect the presence of components other than ocean and clouds in a fairly model-independent way. Degradation of our inversion procedure produced by cloud cover is also quantified. While cloud cover significantly dilutes the magnitude of color variations compared with the cloudless case, the pattern of color changes remains. Therefore, the possibility of investigating surface features through light-curve fitting remains even for exoplanets with cloud cover similar to Earth's.

  5. BLOOMING MECHANISM OF FRESHWATER RED-TIDE IN EUTRORHIC ABOLISHED-RIVER

    NASA Astrophysics Data System (ADS)

    Nagabayashi, Hisao; Hirayama, Kazuo; Horikawa, Kunihiko

    This paper analyzes blooming mechanism of freshwater red-tide in an abolished-river which eutrophicated by seventy-years. Outbreaks of red tide of the river is depend on two phenomenon; the first one is the effect of secondary current generated by the wind along with the temperature rise, the second is the flow for the downstream by the release discharge from the power generation-dam in the downstream. Euglena spp. in euglena and Uroglena spp. in yellow-zooxanthellas is clarified to be the dominant species of the freshwater red-tide.

  6. [Adaptability of mangrove Avicennia marina seedlings to simulated tide-inundated times].

    PubMed

    Liao, Bao-wen; Qiu, Feng-ying; Zhang, Liu-en; Han, Jing; Guan, Wei

    2010-05-01

    A laboratory test on the effects of differents simulated tide-inundated times with 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24 h x d(-1) on the growth of Avicennia marina seedlings was conducted. The ten growth information indices including chlorophyll, root vigor, growth, biomass and photosynthetic rate were mensurated. The principal components analysis was made combining the ten growth information indices. The 210 d experimental results showed that the chlorophyll, root vigor, growth and biomass would rise first and then fall as the extension of the inundate time; and they changed suddenly at the threshold inundate time 16 h x d(-1). The growth and biomass of Avicennia marina seedlings with more than 16 hours tide-inundated time per day were less than them with no more than 16 hours tide-inundated time per day. The maximum value of stem increment each month, leaf blade increment each month, dry weight of stem, dry weight of root and total biomass were under the 10 hours tide-inundated time per day. It concluded that Avicennia marina seedlings would grow adaptively with less than 16 hours tide-inundated time per day, 8-12 hours of tide-inundated time per day is the most suitable for the growth of Avicennia marina seedlings, while 16 h x d(-1) is a critical tide-inundated time when the plant responded to be obviously inadaptable.

  7. Best Mitigation Paths To Effectively Reduce Earth's Orbital Debris

    NASA Technical Reports Server (NTRS)

    Wiegman, Bruce M.

    2009-01-01

    This slide presentation reviews some ways to reduce the problem posed by debris in orbit around the Earth. It reviews the orbital debris environment, the near-term needs to minimize the Kessler syndrome, also known as collisional cascading, a survey of active orbital debris mitigation strategies, the best paths to actively remove orbital debris, and technologies that are required for active debris mitigation.

  8. Tidal effects on Earth, Planets, Sun by far visiting moons

    NASA Astrophysics Data System (ADS)

    Fargion, Daniele

    2016-07-01

    The Earth has been formed by a huge mini-planet collision forming our Earth surface and our Moon today. Such a central collision hit was statistically rare. A much probable skimming or nearby encounter by other moons or planets had to occur. Indeed Recent observations suggest that many planetary-mass objects may be present in the outer solar system between the Kuiper belt and the Oort cloud. Gravitational perturbations may occasionally bring them into the inner solar system. Their passage near Earth could have generated gigantic tidal waves, large volcanic eruptions, sea regressions, large meteoritic impacts and drastic changes in global climate. They could have caused the major biological mass extinctions in the past in the geological records. For instance a ten times a terrestrial radius nearby impact scattering by a peripherical encounter by a small moon-like object will force huge tidal waves (hundred meter height), able to lead to huge tsunami and Earth-quake. Moreover the historical cumulative planet hits in larger and wider planets as Juppiter, Saturn, Uranus will leave a trace, as observed, in their tilted spin axis. Finally a large fraction of counter rotating moons in our solar system probe and test such a visiting mini-planet captur origination. In addition the Earth day duration variability in the early past did show a rare discountinuity, very probably indebt to such a visiting planet crossing event. These far planets in rare trajectory to our Sun may, in thousands event capture, also explain sudden historical and recent temperature changes.

  9. Wind Forcing of the North Sea Pole Tide

    NASA Technical Reports Server (NTRS)

    OConnor, W.; Chao, B. F.; Zheng, D. W.; Au, Z. Y.

    1998-01-01

    The Chandler wobble of the earth's rotation has a period near 14 months and sets up the 0.5 cm amplitude pole tide in the deep oceans, However, the pole tide is anomalously large in the North Sea, where the amplitude increases sharply up to 3 cm along the continental coast. It is shown here that the sea levels are well correlated with winds at the pole tide frequency. The Princeton Ocean Model is used to investigate the response of the North Sea to wind forcing. The barotropic numerical ocean model depicts realistic coastlines and bathymetry at 5 ft x 5 ft resolution, with 97 x 73 grid points. The monthly mean wind fields for the 40-year period (1958-1997) from the National Centers for Atmospheric Prediction (NCEP) reanalysis were used to force the model. The winds were converted to stress with a neutral drag coefficient that varied linearly with windspeed (instead of using the NCEP windstress). A 5-day simulation was made for each month until the resulting flow regime came into equilibrium, and model water levels at various station locations were saved for comparison with tidal-gauge observed sea levels from the Permanent Service for Mean Sea Level (PSMSL). The comparison is made for 10 North Sea stations with high quality tide gauge data. We find: (1) good agreement in annual and semi-annual phases and in the trend of amplitude w.r.t. latitude; (2) more importantly for this study, the model-predicted and observed non-seasonal sea level variations show a very significant temporal correlation as well as spectral coherence. However, a large amplitude difference exists between the two sets -- the overall amplitude variability of the observed is generally a factor of 2-3 larger than the model prediction (this same phenomenon has been reported in ocean circulation studies, although the cause is not yet clear.) Our results indicate that the wind forcing is the main cause of the observed large pole tide in the North Sea.

  10. Observation of the Earth liquid core resonance by extensometers

    NASA Astrophysics Data System (ADS)

    Bán, Dóra; Mentes, Gyula

    2016-04-01

    The axis of the fluid outer core of the Earth and the rotation axis of the mantle do not coincide therefore restoring forces are set up at the core-mantle boundary which try to realign the two axes causing a resonance effect. In celestial reference system it is called the "Free Core Nutation" (FCN), which can be characterized by a period of 432 days while in the Earth reference system it is called the "Nearly Diurnal Free Wobble" (NDFW). The frequency of this phenomenon is near to the diurnal tidal frequencies, especially to P1 and K1 waves. Due to its resonance effect this phenomenon can be detected also by quartz tube extensometers suitable for Earth tides recording. In this study data series measured in several extensometric stations were used to reveal the presence of the FCN resonance. In the Pannonian Basin there are five observatories where extensometric measurements were carried out in different lengths of time. Four stations in Hungary: Sopronbánfalva Geodynamical Observatory (2000-2014), Budapest Mátyáshegy Gravity and Geodynamic Observatory (2005-2012), Pécs uranium mine (1991-1999), Bakonya, near to Pécs (2004-2005) and in Slovakia: Vyhne Earth Tide Observatory (2001-2013). Identical instrumentation in different observatories provides the opportunity to compare measurements with various topography, geology and environmental parameters. The results are also compared to values inferred from extensometric measurements in other stations.

  11. Chandler oscillations of the Earth's pole in the presence of fluctuational dissipative perturbations

    NASA Astrophysics Data System (ADS)

    Markov, Yu. G.; Perepelkin, V. V.; Rykhlova, L. V.; Filippova, A. S.

    2017-02-01

    Effects of fluctuational dissipative perturbations on the Earth's polar motion due to random components of the centrifugal potential are studied using a numerical-analytical approach. A combined model for the polar fluctuations is used to take into account stochastic components of the polar tides. Fluctuations excited at frequencies close to the Chandler frequency are analyzed using observations of sea level and the gravitional acceleration. Equations describing the correlation characteristics of the polar motions are presented.

  12. Galileo and Descartes on Copernicanism and the cause of the tides.

    PubMed

    Schmaltz, Tad M

    2015-06-01

    Galileo and Descartes were on the front lines of the defense of Copernicanism against theological objections that took on special importance during the seventeenth century. Galileo attempted to overcome opposition to Copernicanism within the Catholic Church by offering a demonstration of this theory that appeals to the fact that the double motion of the earth is necessary as a cause of the tides. It turns out, however, that the details of Galileo's tidal theory compromise his demonstration. Far from attempting to provide a demonstration of the earth's motion, Descartes ultimately argued that his system is compatible with the determination of the Church that the earth is at rest. Nonetheless, Descartes's account of the cause of the tides creates difficulty for this argument.

  13. Seasonal Variations of the Earth's Gravitational Field: An Analysis of Atmospheric Pressure, Ocean Tidal, and Surface Water Excitation

    NASA Technical Reports Server (NTRS)

    Dong, D,; Gross, R.S.; Dickey, J.

    1996-01-01

    Monthly mean gravitational field parameters (denoted here as C(sub even)) that represent linear combinations of the primarily even degree zonal spherical harmonic coefficients of the Earth's gravitational field have been recovered using LAGEOS I data and are compared with those derived from gridded global surface pressure data of the National meteorological center (NMC) spanning 1983-1992. The effect of equilibrium ocean tides and surface water variations are also considered. Atmospheric pressure and surface water fluctuations are shown to be the dominant cause of observed annual C(sub even) variations. Closure with observations is seen at the 1sigma level when atmospheric pressure, ocean tide and surface water effects are include. Equilibrium ocean tides are shown to be the main source of excitation at the semiannual period with closure at the 1sigma level seen when both atmospheric pressure and ocean tide effects are included. The inverted barometer (IB) case is shown to give the best agreement with the observation series. The potential of the observed C(sub even) variations for monitoring mass variations in the polar regions of the Earth and the effect of the land-ocean mask in the IB calculation are discussed.

  14. The Impenetrable Barrier Revisited - Anthroprogenic Effects on Earth's Radiation Belts

    NASA Astrophysics Data System (ADS)

    Foster, J. C.; Baker, D. N.; Erickson, P. J.; Albert, J.; Fennell, J. F.; Mishin, E. V.; Starks, M. J.; Jaynes, A. N.; Li, X.; Kanekal, S. G.; Kletzing, C.

    2015-12-01

    The Van Allen Probes are contributing significantly to the understanding of processes effecting Earth's radiation belts. It has been noted that the earthward extent of the outer zone highly-relativistic electrons encounters a nearly impenetrable barrier at a radial distance (L) near 2.8 RE inside of which they are not observed. Modeling suggests that this is the result of a balance between slow inward diffusion and hiss-induced precipitation. The large storm of 17 March 2015 afforded an excellent opportunity to investigate the impenetrable barrier using the full complement of sensors carried by the Van Allen Probes. The storm was marked by the rapid reappearance of strong fluxes of MeV electrons directly outside the barrier with the formation of very steep MeV flux gradients. In spite of the strong rapid recovery of MeV electron fluxes immediately outside the barrier, the sharpness and constancy of the gradient at the barrier is strongly suggestive of a previously unrecognized fast-acting and spatially localized mechanism responsible for the formation of such a well-defined feature during these dramatic circumstances. The Van Allen Probes regularly observe a magnetically confined bubble of VLF emissions of terrestrial origin filling the inner magnetosphere. Strongest signals are from US Navy VLF transmitters used for one-way communication to submarines. These signals largely are confined to the region of L space where their frequency is < ½ fce. The strong signal from station NAA at 24 kHz is confined to L < 2.8 where it encounters the ½ fce limit. During the event, the flux of MeV electrons decreased by 1000x across 0.5 RE outside L = 2.8 simultaneous with a 6 order of magnitude increase in the VLF wave intensity as the Probes entered the VLF bubble. The VLF transmitter frequencies are amplified at the point where they overlap natural chorus band near ½ fce suggestive of transmitter-induced triggered emissions. MeV radiation belt electrons encounter this

  15. Long-range propagation and associated variability of internal tides in the South China Sea

    NASA Astrophysics Data System (ADS)

    Xu, Zhenhua; Liu, Kun; Yin, Baoshu; Zhao, Zhongxiang; Wang, Yang; Li, Qun

    2016-11-01

    The variability of internal tides during their generation and long-range propagation in the South China Sea (SCS) is investigated by driving a high-resolution numerical model. The present study clarifies the notably different processes of generation, propagation, and dissipation between diurnal and semidiurnal internal tides. Internal tides in the SCS originate from multiple source sites, among which the Luzon Strait is dominant, and contributes approximately 90% and 74% of the baroclinic energy for M2 and K1, respectively. To the west of the Luzon Strait, local generation of K1 internal tides inside the SCS is more energetic than the M2 tides. Diurnal and semidiurnal internal tides from the Luzon Strait radiate into the SCS in a north-south asymmetry but with different patterns because of the complex two-ridge system. The tidal beams can travel across the deep basin and finally arrive at the Vietnam coast and Nansha Island more than 1000-1500 km away. During propagation, M2 internal tides maintain a southwestward direction, whereas K1 exhibit complicated wave fields because of the superposition of waves from local sources and island scattering effects. After significant dissipation within the Luzon Strait, the remaining energy travels into the SCS and reduces by more than 90% over a distance of ˜1000 km. Inside the SCS, the K1 internal tides with long crests and flat beam angles are more influenced by seafloor topographical features and thus undergo apparent dissipation along the entire path, whereas the prominent dissipation of M2 internal tides only occurs after their arrival at Zhongsha Island.

  16. Measurement of diurnal and semidiurnal rotational variations and tidal parameters of Earth

    NASA Technical Reports Server (NTRS)

    Herring, Thomas A.; Dong, Danan

    1994-01-01

    tidal models, i.e., deficiencies of up to 0.9 mm in the treatment of the free core nutation resonance. In the semidiurnal band, our analysis yields estimates of the second-degree harmonic radial Love number h(sub 2) at the M2 tide of 0.604 + i0.005 +/- 0.002. The most likely explanation for the rotational variations are the effects of ocean tides, but there may also be some contributions from atmospheric tides, the effects of triaxiality of Earth, and the equatorial second-degree-harmonic components of the core- mantle boundary.

  17. The small and large lags of the elastic and anelastic tides. The virtual identity of two rheophysical theories

    NASA Astrophysics Data System (ADS)

    Ferraz-Mello, Sylvio

    2015-07-01

    The aim of this paper is to discuss the virtual identity of two recent tidal theories: our creep tide theory and one Maxwell model recently developed. It includes the discussion of the basic equations of the theories, which, in both cases, include an elastic and an anelastic component, and shows that the basic equations of the two theories are equivalent and differ by only a numerical factor in the anelastic tide. It also includes a discussion of the lags: the lag of the full tide (geodetic), dominated by the elastic component, and the phase of the anelastic tide. In rotating rocky bodies not trapped in a spin-orbit resonance (e.g., the Earth) the geodetic lag is close to zero and the phase of the semidiurnal argument in the anelastic tide is close to 90 degrees. The results obtained from combining tidal solutions from satellite tracking data and from the Topex/Poseidon satellite altimeter data are extended to determine the phase of the semi-diurnal argument in the Earth's anelastic tide as σ0 = 89.80 ± 0.05 degrees.

  18. Analysis of earth albedo effect on sun sensor measurements based on theoretical model and mission experience

    NASA Technical Reports Server (NTRS)

    Brasoveanu, Dan; Sedlak, Joseph

    1998-01-01

    Analysis of flight data from previous missions indicates that anomalous Sun sensor readings could be caused by Earth albedo interference. A previous Sun sensor study presented a detailed mathematical model of this effect. The model can be used to study the effect of both diffusive and specular reflections and to improve Sun angle determination based on perturbed Sun sensor measurements, satellite position, and an approximate knowledge of attitude. The model predicts that diffuse reflected light can cause errors of up to 10 degrees in Coarse Sun Sensor (CSS) measurements and 5 to 10 arc sec in Fine Sun Sensor (FSS) measurements, depending on spacecraft orbit and attitude. The accuracy of these sensors is affected as long as part of the illuminated Earth surface is present in the sensor field of view. Digital Sun Sensors (DSS) respond in a different manner to the Earth albedo interference. Most of the time DSS measurements are not affected, but for brief periods of time the Earth albedo can cause errors which are a multiple of the sensor least significant bit and may exceed one degree. This paper compares model predictions with Tropical Rainfall Measuring Mission (TRMM) CSS measurements in order to validate and refine the model. Methods of reducing and mitigating the impact of Earth albedo are discussed. ne CSS sensor errors are roughly proportional to the Earth albedo coefficient. Photocells that are sensitive only to ultraviolet emissions would reduce the effective Earth albedo by up to a thousand times, virtually eliminating all errors caused by Earth albedo interference.

  19. Investigations in Marine Chemistry: Tide Pool Ecology.

    ERIC Educational Resources Information Center

    Schlenker, Richard M.

    Students investigated the salinity of tide pools at different levels in the intertidal zone. Data are analyzed collectively. Students graphed and discussed data. Included are suggestions for evaluation and further study. (Author)

  20. The Tides--A Neglected Topic.

    ERIC Educational Resources Information Center

    Hartel, Hermann

    2000-01-01

    Finds that computer simulations can be used to visualize the processes involved with lunar tides. Technology adds value, thus opening new paths for a more distinct analysis and increased learning results. (Author/CCM)

  1. Effects of Superthermal Electrons in The Young Earth Atmosphere and Its Habitability

    NASA Astrophysics Data System (ADS)

    Airapetian, V.; Khazanov, G. V.

    2014-12-01

    In this presentation, we use the Fokker-Plank code to model the effect of intensive short-wavelength (X-rays to UV band) emission from the young Sun on Earth's atmosphere. Our simulations include the photoionization processes of the Earth's atmosphere forming a population of superthermal electrons (E<600 eV), the kinetic effects of their propagation associated and their contribution in ionosphere-magnetosphere energy redistribution. We also evaluated associated non-thermal atmospheric mass loss due to induced ambipolar electric field and its effect on the habitability of early Earth.

  2. The Effect of Fulvic Acid on the Leaching of a Weathered Rare-Earth Ore

    NASA Astrophysics Data System (ADS)

    Luo, Xian-ping; Feng, Bo; Wang, Peng-cheng; Zhou, He-peng; Chen, Xiao-ming

    2015-12-01

    The effect of fulvic acid on the leaching of a weathered crust elution-deposited rare-earth ore, using ammonium sulfate as lixiviant, has been investigated. The results show that fulvic acid can enhance the leaching process effectively. With the addition of fulvic acid to the lixiviant at a concentration of 0.1 wt pct, the leaching extraction of rare-earth elements increased by 8.38 pct and the ammonium sulfate concentration decreased by 25 wt pct. Fulvic acid promotes the leaching process. It also reacts with rare-earth ions, forms soluble complexes, reduces the activity of the leached rare-earth ions, and increases the concentration difference of ion diffusion. These results highlight a new approach for making the leaching process of low-grade weathered crust elution-deposited rare-earth ore more efficient and also for lowering the lixiviant consumption.

  3. The effect of the earth's rotation on ground water motion.

    PubMed

    Loáiciga, Hugo A

    2007-01-01

    The average pore velocity of ground water according to Darcy's law is a function of the fluid pressure gradient and the gravitational force (per unit volume of ground water) and of aquifer properties. There is also an acceleration exerted on ground water that arises from the Earth's rotation. The magnitude and direction of this rotation-induced force are determined in exact mathematical form in this article. It is calculated that the gravitational force is at least 300 times larger than the largest rotation-induced force anywhere on Earth, the latter force being maximal along the equator and approximately equal to 34 N/m(3) there. This compares with a gravitational force of approximately 10(4) N/m(3).

  4. 18.6-year Earth tide regulates geyser activity.

    PubMed

    Rinehart, J S

    1972-07-28

    Over 40 years of records from Yellowstone National Park, Wyoming, show that the 18.6-year tidal component strongly regulates the frequencies of eruption of Grand and Steamboat geysers. The frequency of Grand Geyser increases with increasing tidal force and that of Steamboat Geyser decreases, which suggests that tidal dilatation is one factor affecting heat flow to a geyser.

  5. Simultaneous generation and scattering of internal tides by ocean floor topography

    NASA Astrophysics Data System (ADS)

    Mathur, Manikandan

    2015-11-01

    Internal waves play a significant role in the global energy budget of the ocean, with internal tides potentially contributing to the conversion of a large amount of mechanical energy into heat in the deep ocean. Several studies in the past decade have investigated internal tide generation and internal tide scattering by ocean floor topography, but by treating them as two separate, independent processes. In this talk, we use the recently developed Green function model (Mathur et al., J. Geophys. Res. Oceans, 119, 2165-2182, 2014), sans the WKB approximation, to quantify the extent to which internal tide generation (scattering) that results from barotropic (baroclinic) forcing on small- and large-scale topography in uniform and nonuniform stratifications is modified by the presence of a background baroclinic (barotropic) tide. Results on idealized topography, stratification and forcing will first be presented, followed by a discussion on the relevance of our studies in the real ocean scenario. The author thanks the Ministry of Earth Sciences, Government of India for financial support under the Monsoon Mission Grant MM/2014/IND-002.

  6. Subdaily Earth Rotation Models Estimated From GPS and VLBI Data

    NASA Astrophysics Data System (ADS)

    Steigenberger, P.; Tesmer, V.; MacMillan, D.; Thaller, D.; Rothacher, M.; Fritsche, M.; Rülke, A.; Dietrich, R.

    2007-12-01

    Subdaily changes in Earth rotation at diurnal and semi-diurnal periods are mainly caused by ocean tides. Smaller effects are attributed to the interaction of the atmosphere with the solid Earth. As the tidal periods are well known, models for the ocean tidal contribution to high-frequency Earth rotation variations can be estimated from space- geodetic observations. The subdaily ERP model recommended by the latest IERS conventions was derived from an ocean tide model based on satellite altimetry. Another possibility is the determination of subdaily ERP models from GPS- and/or VLBI-derived Earth rotation parameter series with subdaily resolution. Homogeneously reprocessed long-time series of subdaily ERPs computed by GFZ/TU Dresden (12 years of GPS data), DGFI and GSFC (both with 24 years of VLBI data) provide the basis for the estimation of single-technique and combined subdaily ERP models. The impact of different processing options (e.g., weighting) and different temporal resolutions (1 hour vs. 2 hours) will be evaluated by comparisons of the different models amongst each other and with the IERS model. The analysis of the GPS and VLBI residual signals after subtracting the estimated ocean tidal contribution may help to answer the question whether the remaining signals are technique-specific artifacts and systematic errors or true geophysical signals detected by both techniques.

  7. Tide and tidal current observation in the Karimata Strait

    NASA Astrophysics Data System (ADS)

    Wei, Zexun; Fang, Guohong; Sulistiyo, Budi; Dwi Susanto, R.; Setiawan, Agus; Rameyo Adi, Tukul; Qiao, Fangli; Fan, Bin; Li, Shujiang

    2013-04-01

    It is believed that the water exchanges between the South China Sea and the Indonesian Seas are significant, and play an important role in the water mass formation and air-sea interactions of both the South China Sea and Indonesian Seas. It has also been found that the current in Sunda Strait has been obvious seasonal variation, which indicates the water exchange between West Indonesian Seas and India Ocean. In order to make quantitative evaluation of the magnitudes of the exchange, the First Institute of Oceanography (FIO), China, the Agency for Marine and Fisheries Research, Indonesia, and the Lamont-Doheries Earth Observatory, USA established a collaborative program, "The South-China Sea-Indonesian Seas Transport/Exchange (SITE) and Impacts on Seasonal Fish Migration" in 2006. And, they extend and expand the cooperation to Sunda Strait in 2008, the title of the collaborative program was changed to "The South China Sea - Indonesian Seas Transport/Exchange (SITE) and Dynamics of Sunda and Lombok Straits, and Their Impacts on Seasonal Fish Migration". Till now, 12 joint cruises have been conducted since December, 2007. Ten Trawl-Resistant Bottom Mounts (TRBM) have been deployed in the Karimata and Sunda Straits. The TRBMs are equipped with ADCPs and tide gauges for measuring current profiles and sea levels, respectively. The temperature-salinity profiles were measured with ship-board CTD during the cruises. Data obtained in Karimata Strait revealed that a significant water mass transport. This indicates that the Karimata Strait throughflow can greatly impacts the circulation of both the South China Sea and the Indonesian Seas. The data obtained at the 5 stations alone the two sections in the Karimata Strait were used to study the tide and tidal currents in the Karimata Strait. 2 TRBMs were deployed at Section A, as well as 3 at Section B, which lies at the southeast of Section A. Station B1 is in the Gaspar Strait between Bangka Island and Belitung Island, Stations

  8. Single Event Effects Testing For Low Earth Orbit Missions with Neutrons

    NASA Technical Reports Server (NTRS)

    Reddell, Brandon; O'Neill, Pat; Bailey, Chuck; Nguyen, Kyson

    2015-01-01

    Neutrons can effectively be used to screen electronic parts intended to be used in Low Earth Orbit. This paper compares neutron with proton environments in spacecraft and discusses recent comparison testing.

  9. Telluric currents have no significant effect on the Earth's core seismicity

    NASA Astrophysics Data System (ADS)

    Chernogor, L. F.

    2017-01-01

    We show that telluric currents have no effect on the formation of macrofaults in the Earth's crust or on implementation of the intensification regime. This is mainly associated with the weakness of telluric currents and induction of the geomagnetic field.

  10. Modeling Tides, Planetary Waves, and Equatorial Oscillations in the MLT

    NASA Technical Reports Server (NTRS)

    Mengel, J. G.; Mayr, H. G.; Drob, D. P.; Porter, H. S.; Bhartia, P. K. (Technical Monitor)

    2001-01-01

    Applying Hines Doppler Spread Parameterization for gravity waves (GW), our 3D model reproduces some essential features that characterize the observed seasonal variations of tides and planetary waves in the upper mesosphere. In 2D, our model also reproduces the large Semi-Annual Oscillation (SAO) and Quasi Biennial Oscillation (QBO) observed in this region at low latitudes. It is more challenging to describe these features combined in a more comprehensive self consistent model, and we give a progress report that outlines the difficulties and reports some success. In 3D, the GW's are partially absorbed by tides and planetary waves to amplify them. Thus the waves are less efficient in generating the QBO and SAO at equatorial latitudes. Some of this deficiency is compensated by the fact that the GW activity is observed to be enhanced at low latitudes. Increasing the GW source has the desired effect to boost the QBO, but the effect is confined primarily to the stratosphere. With increasing altitude, the meridional circulation becomes more important in redistributing the momentum deposited in the background flow by the GW's. Another factor involved is the altitude at which the GW's originate, which we had originally chosen to be the surface. Numerical experiments show that moving this source altitude to the top of the troposphere significantly increases the efficiency for generating the QBO without affecting much the tides and planetary waves in the model. Attention to the details in which the GW source comes into play thus appears to be of critical importance in modeling the phenomenology of the MLT. Among the suite of numerical experiments reported, we present a simulation that produced significant variations of tides and planetary waves in the upper mesosphere. The effect is related to the QBO generated in the model, and GW filtering is the likely cause.

  11. Seasonal variations in Pluto's atmospheric tides

    NASA Astrophysics Data System (ADS)

    French, Richard G.; Toigo, Anthony D.; Gierasch, Peter J.; Hansen, Candice J.; Young, Leslie A.; Sicardy, Bruno; Dias-Oliveira, Alex; Guzewich, Scott D.

    2015-01-01

    Pluto's tenuous atmosphere exhibits remarkable seasonal change as a result of the planet's substantial obliquity and highly eccentric orbit. Over the past two decades, occultations have revealed that the atmospheric pressure on Pluto has increased substantially, perhaps by a factor as large as 2 to 4, as the planet has moved from equinox towards solstice conditions. These data have also shown variations in the strength of the dynamical activity in the atmosphere, as revealed by the varying abundance and amplitude of spikes in the occultation light curves resulting from refractive focussing by atmospheric waves. Toigo et al. (Toigo et al. [2010]. Icarus, 208, 402-411) explored the possibility that these waves are caused by solar-induced sublimation and diurnal deposition from N2 frost patches, driven by weak vertical winds resulting from the rising and sinking gas as it is released from or deposited onto the surface. Here, we extend this model to account explicitly for seasonal variations in average insolation and for the significant damping of vertical wave propagation by kinematic viscosity and thermal diffusivity (Hubbard et al. [2009]. Icarus, 204, 284-289). Damping is extremely effective in suppressing vertical propagation of waves with vertical wavelengths of a few kilometers or less, and the dominant surviving tidal modes have characteristic vertical wavelengths λ ∼ 10-13 km . We estimate the expected strength and regional characteristics of atmospheric tides over the course of Pluto's orbit for a variety of assumed spatial distributions of surface frost and atmospheric surface pressure. We compute the predicted strength of tide-induced wave activity based on the actual frost distribution observed on Pluto from Hubble Space Telescope (HST) observations (Stern et al. [1997]. Astron. J., 113, 827; Buie et al. [2010]. Astron. J., 139, 1128-1143), and compare the results to calculations for volatile transport models of Young (Young [2013]. Astrophys. J., 766

  12. Study of effects of space power satellites on life support functions of the earth's magnetosphere

    NASA Technical Reports Server (NTRS)

    Douglas, M.; Laquey, R.; Deforest, S. E.; Lindsey, C.; Warshaw, H.

    1977-01-01

    The effects of the Satellite Solar Power System (SSPS) on the life support functions of the earth's magnetosphere were investigated. Topics considered include: (1) thruster effluent effects on the magnetosphere; (2) biological consequences of SSPS reflected light; (3) impact on earth bound astronomy; (4) catastrophic failure and debris; (5) satellite induced processes; and (6) microwave power transmission. Several impacts are identified and recommendations for further studies are provided.

  13. An Assessment of Relativistic Effects for Low Earth Orbiters: The GRACE Satellites

    DTIC Science & Technology

    2007-01-01

    IOP PUBLISHING METROLOGIA Metrologia 44 (2007) 484–490 doi:10.1088/0026-1394/44/6/007 An assessment of relativistic effects for low Earth orbiters...for the larger-eccentricity orbit is shown in figure 2(b). Metrologia , 44 (2007) 484–490 485 K M Larson et al Figure 1. Amplitude of the once/rev...486 Metrologia , 44 (2007) 484–490 Assessment of relativistic effects for low Earth orbiters combination was launched on TOPEX in 1992. Unfortunately

  14. Tide-related biological rhythm in the oxygen consumption rate of ghost shrimp (Neotrypaea uncinata).

    PubMed

    Leiva, Félix P; Niklitschek, Edwin J; Paschke, Kurt; Gebauer, Paulina; Urbina, Mauricio A

    2016-07-01

    The effects of tidal height (high and low), acclimation to laboratory conditions (days in captivity) and oxygen level (hypoxia and normoxia) were evaluated in the oxygen consumption rate (OCR) of the ghost shrimp Neotrypaea uncinata We evaluated the hypothesis that N. uncinata reduces its OCR during low tide and increases it during high tide, regardless of oxygen level or acclimation. Additionally, the existence of an endogenous rhythm in OCR was explored, and we examined whether it synchronized with tidal, diurnal or semidiurnal cycles. Unexpectedly, high OCRs were observed at low tide, during normoxia, in non-acclimated animals. Results from a second, longer experiment under normoxic conditions suggested the presence of a tide-related metabolic rhythm, a response pattern not yet demonstrated for a burrowing decapod. Although rhythms persisted for only 2 days after capture, their period of 12.8 h closely matched the semidiurnal tidal cycle that ghost shrimp confront inside their burrows.

  15. Study of red tide prediction model for the Changjiang Estuary

    NASA Astrophysics Data System (ADS)

    Wang, Zheng-Fang; Lu, Hai-Yan; Zhang, Qing; Lu, Yong; Zeng, Jiang-Ning; Zhou, Qing-Song

    2000-12-01

    This paper based on field data (on red tide water quality monitoring at the Chaggjiang River mouth and Hutoudu mariculture area in Zhejiang Province from May to August in 1995, and May to September in 1996) presents an effective model for short term prediction of red tide in the Changjiang Estuary. The measured parameters include: depth, temperature, color diaphaneity, density, DO, COD and nutrients (PO4-P, NO2-N, NO3-N, NH4-N). The model was checked by field-test data, and compared with other related models. The model: Z=SAL-3.95 DO-2.974 PH-5.421 PO4-P is suitable for application to the Shengsi aquiculture area near the Changjiang Estuary.

  16. Does lunisolar gravitational tide affect the activity of animals?

    NASA Astrophysics Data System (ADS)

    Deshcherevskii, A. V.; Sidorin, A. Ya.

    2010-12-01

    Multiyear time series obtained by the continuous instrumental monitoring of the electrical activity (EA) of weakly electric fish Gnathonemus leopoldianus and the motor activity (MA) of the freshwater catfish Hoplosternum thoracatum and the cockroach Blaberus craniifer are compared to the parameters of the lunisolar gravitational tide. These curves are observed to be very similar for a large number of time intervals. However, a more detailed analysis shows this to be only a superficial resemblance caused by the closeness of the periods of diurnal and semidiurnal rhythms of bioindicator activity (the dominant rhythms in EA and MA patterns) and the periods of main gravitational tidal waves. It is concluded that the lunisolar gravitational tide has no significant effect on animal behavior in our experiment.

  17. The effect of EarthPulse on learning of declarative knowledge

    NASA Astrophysics Data System (ADS)

    McKinney, Heather E.

    The purpose of this double-blind, bio-medical research study was to investigate the effect of EarthPulse, a brainwave entrainment and pulsed electromagnetic field (PEMF) device, on learning of declarative knowledge. Currently, PEMF research explores physiological and psychological effects but a gap exists in the potential effects of PEMF on learning. The study explored whether a relationship existed between receiving a thirty minute EarthPulse treatment on the "Entrain Up" setting and learning of declarative knowledge; whether the relationship remained over time; whether EarthPulse had an effect on sleep; and whether EarthPulse had an effect on attrition. Ninety-eight, randomly assigned, undergraduate students participated in this double-blind, experimental design study, of which 87 remained after attrition. After receiving a thirty minute EarthPulse or placebo treatment, experimental and control groups read identical passages and completed identical instruments to test learning and retention of declarative knowledge. Participants completed the same test in two intervals: an immediate (learning) and delayed (retention) posttest. Assumptions for normality and reliability were met. One-way ANOVA revealed no statistically significant effects on learning or retention at the 0.05 level. However, Chi square analysis revealed those who received the EarthPulse treatment were significantly less likely to fall asleep than those who received the control treatment (p=0.022) and very closely approached significance for attrition (p=0.051).

  18. Excitation mechanism of non-migrating tides

    NASA Astrophysics Data System (ADS)

    Miyoshi, Yasunobu; Pancheva, Dora; Mukhtarov, Plamen; Jin, Hidekatsu; Fujiwara, Hitoshi; Shinagawa, Hiroyuki

    2017-04-01

    Using an atmosphere-ionosphere coupled model, the excitation source and temporal (seasonal and interannual) variations in non-migrating tides are investigated in this study. We first focus our attention on temporal variations in eastward moving diurnal tide with zonal wavenumber 3 (DE3), which is the largest of all the non-migrating tides in the mesosphere and lower thermosphere (MLT). Our simulation results indicate that upward propagation of the DE3 excited in the troposphere is sensitive to the zonal mean zonal wind in the stratosphere and mesosphere. The DE3 amplitude is enhanced in the region where the vertical shear of the zonal mean zonal wind is positive (westerly shear). Quasi-2-year variation in the DE3 amplitude in the MLT region is generated by quasi-2-year variation in the zonal mean zonal wind between 40 and 70 km, which is modulated by the stratospheric QBO. The excitation mechanisms of SW3 (westward moving semidiurnal tide with zonal wavenumber 3) and SW1 (westward moving semidiurnal tide with zonal wavenumber 1) are also investigated. During equinoxes, the SW3 and SW1 are excited by tropospheric heating (latent heat release and solar radiative heating) associated with cumulus convection in the tropics, and propagate upward into the MLT region. On the other hand, during solstices, SW3 and SW1 are generated in the winter stratosphere and mesosphere through the nonlinear interaction between the stationary planetary wave and migrating semidiurnal tide, and propagate upward to the lower thermosphere. The excitation sources of other non-migrating tides are also discussed.

  19. The Effect of Rare Earth on the Structure and Performance of Laser Clad Coatings

    NASA Astrophysics Data System (ADS)

    Bao, Ruiliang; Yu, Huijun; Chen, Chuanzhong; Dong, Qing

    Laser cladding is one kind of advanced surface modification technology and has the abroad prospect in making the wear-resistant coating on metal substrates. However, the application of laser cladding technology does not achieve the people's expectation in the practical production because of many defects such as cracks, pores and so on. The addiction of rare earth can effectively reduce the number of cracks in the clad coating and enhance the coating wear-resistance. In the paper, the effects of rare earth on metallurgical quality, microstructure, phase structure and wear-resistance are analyzed in turns. The preliminary discussion is also carried out on the effect mechanism of rare earth. At last, the development tendency of rare earth in the laser cladding has been briefly elaborated.

  20. M2 Internal Tide Propagation Through a Geostrophic Front Near the Critical Latitude

    NASA Astrophysics Data System (ADS)

    Chavanne, C. P.; Massad, A.; Heywood, K. J.

    2012-12-01

    A year-long (February 2009 - February 2010) record of ocean currents from instruments (RDI ADCP and Nortek Aquadopp) moored across the continental shelf and slope in the south-east Weddell Sea (~18 W, ~72.5 S) is analysed to investigate the propagation of M2 internal tides through a geostrophic front, the Antarctic Slope Front, near the M2 critical latitude (74.5 S). The record is long enough to separate M2 tides from local inertial currents, as confirmed by the downward phase propagation of M2 currents, indicative of upward energy propagation consistent with topographically-generated internal tides. Vertically-localized peaks of kinetic energy, indicative of internal tide beams, are found just above the bottom at the shelf break, and between 100 and 200 m depths at four of the five moorings. Ray tracing in the absence of background currents predicts internal ray paths inconsistent with the observed kinetic energy peak locations. The effects of the Antarctic Slope Front on internal tide propagation are investigated in two steps. Firstly, the background shears are neglected in the dispersion relation (except for their effect on the local buoyancy frequency), but allowed to refract the internal tides. Predicted internal ray paths are substantially modified from those in an ocean at rest, but they are still inconsistent with observations. Secondly, the background shears are allowed to modify the dispersion relation, dramatically modifying the predicted ray paths and vertical wavenumbers. These results demonstrate that geostrophic shears strongly affect internal tides propagation near their critical latitude, with implications on localization and parametrisation of internal-tide induced diapycnal mixing.

  1. The Near-Earth Plasma Environment

    NASA Technical Reports Server (NTRS)

    Pfaff, Robert F., Jr.

    2012-01-01

    An overview of the plasma environment near the earth is provided. We describe how the near-earth plasma is formed, including photo-ionization from solar photons and impact ionization at high latitudes from energetic particles. We review the fundamental characteristics of the earth's plasma environment, with emphasis on the ionosphere and its interactions with the extended neutral atmosphere. Important processes that control ionospheric physics at low, middle, and high latitudes are discussed. The general dynamics and morphology of the ionized gas at mid- and low-latitudes are described including electrodynamic contributions from wind-driven dynamos, tides, and planetary-scale waves. The unique properties of the near-earth plasma and its associated currents at high latitudes are shown to depend on precipitating auroral charged particles and strong electric fields which map earthward from the magnetosphere. The upper atmosphere is shown to have profound effects on the transfer of energy and momentum between the high-latitude plasma and the neutral constituents. The article concludes with a discussion of how the near-earth plasma responds to magnetic storms associated with solar disturbances.

  2. Landslide movement in southwest Colorado triggered by atmospheric tides

    USGS Publications Warehouse

    Schulz, W.H.; Kean, J.W.; Wang, G.

    2009-01-01

    Landslides are among the most hazardous of geological processes, causing thousands of casualties and damage on the order of billions of dollars annually. The movement of most landslides occurs along a discrete shear surface, and is triggered by a reduction in the frictional strength of the surface. Infiltration of water into the landslide from rainfall and snowmelt and ground motion from earthquakes are generally implicated in lowering the frictional strength of this surface. However, solid-Earth and ocean tides have recently been shown to trigger shear sliding in other processes, such as earthquakes and glacial motion. Here we use observations and numerical modelling to show that a similar processatmospheric tidescan trigger movement in an ongoing landslide. The Slumgullion landslide, located in the SanJuan Mountains of Colorado, shows daily movement, primarily during diurnal low tides of the atmosphere. According to our model, the tidal changes in air pressure cause air and water in the sediment pores to flow vertically, altering the frictional stress of the shear surface; upward fluid flow during periods of atmospheric low pressure is most conducive to sliding. We suggest that tidally modulated changes in shear strength may also affect the stability of other landslides, and that the rapid pressure variations associated with some fast-moving storm systems could trigger a similar response. ?? 2009 Macmillan Publishers Limited. All rights reserved.

  3. Glacier Melting Effect on the Earth's Rotation - Revisited

    NASA Astrophysics Data System (ADS)

    Na, S. H.; Sahagian, D. L.; Kim, T. H.; Jo, B. G.; Ahn, K. D.; Shin, Y. H.

    2014-12-01

    The direction of polar wander has recently been tilted eastward by several degrees. By direct calculation of Earth's inertia tensor perturbation due to observed glacier mass changes (twenty year average), we found the yearly drift polar motion excitation as (ψ1, ψ2)=(1.00, 0.05) milliarcsec. This direction closely matches the observed pole drift, and we infer that glacier melting is the primary driver of the observed polar wander. Analysis of polar motion data indicates that a substantial portion of the observed eastward pole drift has occurred since the late 1990s, also consistent with the accelerated rate of glacier melting. The associated change in LOD due to average glacier melting for the last twenty years is estimated as +114 microsec, which implies total 0.42 s delay in UT1 for the same time span.

  4. Discover Earth

    NASA Technical Reports Server (NTRS)

    Steele, Colleen

    1998-01-01

    Discover Earth is a NASA-sponsored project for teachers of grades 5-12, designed to: (1) enhance understanding of the Earth as an integrated system; (2) enhance the interdisciplinary approach to science instruction; and (3) provide classroom materials that focus on those goals. Discover Earth is conducted by the Institute for Global Environmental Strategies in collaboration with Dr. Eric Barron, Director, Earth System Science Center, The Pennsylvania State University; and Dr. Robert Hudson, Chair, the Department of Meteorology, University of Maryland at College Park. The enclosed materials: (1) represent only part of the Discover Earth materials; (2) were developed by classroom teachers who are participating in the Discover Earth project; (3) utilize an investigative approach and on-line data; and (4) can be effectively adjusted to classrooms with greater/without technology access. The Discover Earth classroom materials focus on the Earth system and key issues of global climate change including topics such as the greenhouse effect, clouds and Earth's radiation balance, surface hydrology and land cover, and volcanoes and climate change. All the materials developed to date are available on line at (http://www.strategies.org) You are encouraged to submit comments and recommendations about these materials to the Discover Earth project manager, contact information is listed below. You are welcome to duplicate all these materials.

  5. Malaria and Red Tide Chemistry

    NASA Astrophysics Data System (ADS)

    Heinhorst, Sabine; Cannon, Gordon

    1998-10-01

    The January 1st, 1998, issue of Nature (Vol. 391) presented us with the annual "Anniversaries" commentary (pp 13-16) which commemorates landmark scientific discoveries and puts them in a historical perspective. Pierre and Marie Curie discovered polonium and radium in 1898; Henry Cavendish measured gravity and determined the density of the earth for the first time in 1798; and Hildegard von Bingen was born in 1098.

  6. Planetary meteorology - A new perspective on the earth's weather

    NASA Technical Reports Server (NTRS)

    Joels, K.

    1976-01-01

    Meteorological observations of other planets which may contribute to an understanding of the meteorological processes on the earth are discussed. The high solar input and extremely low rotation rate of Venus simplify the analysis of the interaction of solar energy with the atmosphere. The dust present in the atmosphere of Mars may provide a useful model for studying the effects of anthropogenic aerosols in the atmosphere of earth. Observations of Mars may also be expected to yield information on the evolution of severe storms and on atmospheric tides. The belts and zones in the Jovian atmosphere bear some similarities to cyclones on earth, although they are produced differently; careful modeling of Jupiter's atmosphere may cast light on terrestrial cyclonic activity.

  7. The Global S$_1$ Ocean Tide

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.; Egbert, G. D.

    2003-01-01

    The small S$_1$ ocean tide is caused primarily by diurnal atmospheric pressure loading. Its excitation is therefore unlike any other diurnal tide. The global character of $S-1$ is here determined by numerical modeling and by analysis of Topex/Poseidon satellite altimeter data. The two approaches yield reasonably consistent results, and large ( $ greater than $l\\cm) amplitudes in several regions are further confirmed by comparison with coastal tide gauges. Notwithstanding their excitation differences, S$-1$ and other diurnal tides are found to share several common features, such as relatively large amplitudes in the Arabian Sea, the Sea of Okhotsk, and the Gulf of Alaska. The most noticeable difference is the lack of an S$-1$ Antarctic Kelvin wave. These similarities and differences can be explained in terms of the coherences between near-diurnal oceanic normal modes and the underlying tidal forcings. While gravitational diurnal tidal forces excite primarily a 28-hour Antarctic-Pacific mode, the S$_1$ air tide excites several other near-diurnal modes, none of which has large amplitudes near Antarctica.

  8. Secular Changes in the Tide of the Gulf of Maine

    NASA Astrophysics Data System (ADS)

    Ray, R. D.

    2008-12-01

    For the past century the amplitude of the principal semidiurnal lunar tide in the Gulf of Maine has been dramatically increasing. For example, at Eastport, Maine, the trend in M2 amplitude is 13 cm/century, comparable to the rise in mean sea level. At the same time the solar tide S2 has been decreasing. These tidal changes, which occur throughout the entire Gulf, presumably reflect changes in basin configuration--- geometry, depth, or both. Tidal models that account for Holocene sea level rise do predict an amplification of M2, but much smaller than the currently observed trends. An increasing M2 and decreasing S2 could reflect a shift of the gulf's dominant resonant frequency toward M2 and away from S2. This seems unlikely, however, because Garrett and others have shown that the primary resonance of the Gulf of Maine lies near or below the frequency of N2, so any shift should affect M2 and S2 similarly. Preliminary analysis suggests a small perturbation in the Q of the gulf tide, thus pointing to dissipation rather the frequency-shifting as the cause. In addition, the changes in S2 appear to be induced by a far more widespread decrease in S2 amplitudes throughout much of the northeast Atlantic Ocean, extending at least as far as Bermuda. The cause of this is not understood, but radiational effects in S2 can be ruled out because similar changes occur in K2. We review the evidence---primarily from long tide-gauge time series---for these changes in tidal "constants" and the status of our still-incomplete theories of causative mechanisms.

  9. Biological effects of high ultraviolet radiation on early earth--a theoretical evaluation.

    PubMed

    Cockell, C S

    1998-08-21

    The surface of early Earth was exposed to both UVC radiation (< 280 nm) and higher doses of UVB (280-315 nm) compared with the surface of present day Earth. The degree to which this radiation environment acted as a selection pressure on organisms and biological systems has rarely been theoretically examined with respect to the biologically effective irradiances that ancient organisms would receive. Here action spectra for DNA inactivation and isolated chloroplast inhibition are used to estimate biologically effective irradiances on archean Earth. Comparisons are made with present day Earth. The theoretical estimations on the UV radiation screening required to protect DNA on archean Earth compare well with field and laboratory observations on protection strategies found in present day microbial communities. They suggest that many physical and biological methods may have been effective and would have allowed for the radiation of life even under the high UV radiation regimes of archean Earth. Such strategies would also have provided effective reduction of photoinhibition by UV radiation. The data also suggest that the UV regime on the surface of Mars is not a life limiting factor per se, although other environmental factors such as desiccation and low temperatures may contribute towards the apparent lack of a surface biota.

  10. Frontiers in Outreach and Education: The Florida Red Tide Experience.

    PubMed

    Nierenberg, Kate; Hollenbeck, Julie; Fleming, Lora E; Stephan, Wendy; Reich, Andrew; Backer, Lorraine C; Currier, Robert; Kirkpatrick, Barbara

    2011-05-01

    To enhance information sharing and garner increased support from the public for scientific research, funding agencies now typically require that research groups receiving support convey their work to stakeholders. The National Institute of Environmental Health Sciences-(NIEHS) funded Aerosolized Florida Red Tide P01 research group (Florida Red Tide Research Group) has employed a variety of outreach strategies to meet this requirement. Messages developed from this project began a decade ago and have evolved from basic print material (fliers and posters) to an interactive website, to the use of video and social networking technologies, such as Facebook and Twitter. The group was able to track dissemination of these information products; however, evaluation of their effectiveness presented much larger challenges. The primary lesson learned by the Florida Red Tide Research Group is that the best ways to reach specific stakeholders is to develop unique products or services to address specific stakeholders needs, such as the Beach Conditions Reporting System. Based on the experience of the Group, the most productive messaging products result when scientific community engages potential stakeholders and outreach experts during the very initial phases of a project.

  11. Frontiers in Outreach and Education: The Florida Red Tide Experience

    PubMed Central

    Nierenberg, Kate; Hollenbeck, Julie; Fleming, Lora E.; Stephan, Wendy; Reich, Andrew; Backer, Lorraine C.; Currier, Robert; Kirkpatrick, Barbara

    2011-01-01

    To enhance information sharing and garner increased support from the public for scientific research, funding agencies now typically require that research groups receiving support convey their work to stakeholders. The National Institute of Environmental Health Sciences-(NIEHS) funded Aerosolized Florida Red Tide P01 research group (Florida Red Tide Research Group) has employed a variety of outreach strategies to meet this requirement. Messages developed from this project began a decade ago and have evolved from basic print material (fliers and posters) to an interactive website, to the use of video and social networking technologies, such as Facebook and Twitter. The group was able to track dissemination of these information products; however, evaluation of their effectiveness presented much larger challenges. The primary lesson learned by the Florida Red Tide Research Group is that the best ways to reach specific stakeholders is to develop unique products or services to address specific stakeholders needs, such as the Beach Conditions Reporting System. Based on the experience of the Group, the most productive messaging products result when scientific community engages potential stakeholders and outreach experts during the very initial phases of a project. PMID:21532966

  12. Obliquity Tides in Hot Jupiters

    NASA Astrophysics Data System (ADS)

    Peale, S. J.

    two papers have pointed out that this is not so (Levrard et al. 2007; Fabrycky et al. 2007). The rotation continues to decrease below the synchronous value with increasing obliquity. As is perhaps expected, state 2 becomes unstable as the planet slows. The planet then rapidly evolves to Cassini state 1 with a negligibly small obliquity, and all isolated hot Jupiters will evolve to nearly circular orbits with their spin axes nearly normal to their orbit planes. Obliquity tides cannot be invoked as a means of additional heating of hot gaseous planets.

  13. Effect of alkaline-earth ions on the dynamics of alkali ions in bismuthate glasses

    NASA Astrophysics Data System (ADS)

    Dutta, A.; Ghosh, A.

    2005-12-01

    The effect of alkaline earth ions on the dynamics of Li+ ions in bismuthate glasses has been studied in the temperature range 353-503K and in the frequency range 10Hz-2MHz . The dc conductivity increases and activation energy decreases with the increase of a particular alkaline earth content for the glasses with a fixed alkali content. The increased modification of the network due to the increase in alkaline earth content in the compositions is responsible for the increasing conductivity. Also the compositions with smaller alkaline earth ions were found to exhibit higher conductivity. Although the conductivity increases with the decrease of ionic radii of alkaline earth ions, the activation energy shows a maximum for the Sr ion. The electric modulus and the conductivity formalisms have been employed to study the relaxation dynamics of charge carriers in these glasses. The alkali ions were observed to change their dynamics with the change of the alkaline earth ions. The same anomalous trend for activation energy for the conductivity relaxation frequency and the hopping frequency was also observed for glasses containing SrO. It was also observed that the mobile lithium ion concentrations are independent of nature of alkaline earth ions in these glasses.

  14. Earth and ocean dynamics satellites and systems

    NASA Technical Reports Server (NTRS)

    Vonbun, F. O.

    1975-01-01

    An overview is presented of the present state of satellite and ground systems making observations of the dynamics of the solid earth and the oceans. Emphasis is placed on applications of space technology for practical use. Topics discussed include: satellite missions and results over the last two decades in the areas of earth gravity field, polar motions, earth tides, magnetic anomalies, and satellite-to-satellite tracking; laser ranging systems; development of the Very Long Baseline Interferometer; and Skylab radar altimeter data applications.

  15. Lunar Fluid Core and Solid-Body Tides

    NASA Technical Reports Server (NTRS)

    Williams, J. G.; Boggs, D. H.; Ratcliff, J. T.

    2005-01-01

    Variations in rotation and orientation of the Moon are sensitive to solid-body tidal dissipation, dissipation due to relative motion at the fluid-core/solid-mantle boundary, and tidal Love number k2 [1,2]. There is weaker sensitivity to flattening of the core-mantle boundary (CMB) [2-5] and fluid core moment of inertia [1]. Accurate Lunar Laser Ranging (LLR) measurements of the distance from observatories on the Earth to four retroreflector arrays on the Moon are sensitive to lunar rotation and orientation variations and tidal displacements. Past solutions using the LLR data have given results for dissipation due to solid-body tides and fluid core [1] plus Love number [1-5]. Detection of CMB flattening has been improving [3,5] and now seems significant. This strengthens the case for a fluid lunar core.

  16. Effects of selective fusion on the thermal history of the earth's mantle

    USGS Publications Warehouse

    Lee, W.H.K.

    1968-01-01

    A comparative study on the thermal history of the earth's mantle was made by numerical solutions of the heat equation including and excluding selective fusion of silicates. Selective fusion was approximated by melting in a multicomponent system and redistribution of radioactive elements. Effects of selective fusion on the thermal models are (1) lowering (by several hundred degrees centigrade) and stabilizing the internal temperature distribution, and (2) increasing the surface heat-flow. It was found that models with selective fusion gave results more compatible with observations of both present temperature and surface heat-flow. The results therefore suggest continuous differentiation of the earth's mantle throughout geologic time, and support the hypothesis that the earth's atmosphere, oceans, and crust have been accumulated throughout the earth's history by degassing and selective fusion of the mantle. ?? 1968.

  17. Effect of limb darkening on earth radiation incident on a spherical satellite

    NASA Technical Reports Server (NTRS)

    Katzoff, S.; Smith, G. L.

    1974-01-01

    The thermal radiation from the earth incident on a spherical satellite depends on the angular distribution of earth-emitted radiation. An analysis is presented of this dependency, and calculated results are given, based on a published limb-darkening curve for the earth. The curve was determined from Tiros data, and is a statistical average over the entire globe between 75 deg latitude. The computed effect of limb darkening was 1.8 percent at 900 km altitude, 2.5 percent at 500 km altitude, and 3.0 percent at 300 km altitude. Below 300 km, it increased rapidly with decreasing altitude. Discussion is included of various other problems inherent in the use of orbiting spheres and stabilized flat plates to measure the heat radiated from the earth.

  18. Effects of Rare-Earth Oxides on the Reliability of X7R Dielectrics

    NASA Astrophysics Data System (ADS)

    Sakabe, Yukio; Hamaji, Yukio; Sano, Harunobu; Wada, Nobuyuki

    2002-09-01

    The effects of rare-earth oxides, e.g., La, Nd, Sm, Dy and Yb, on the reliability of multilayer capacitors (MLCs) with X7R dielectrics and Ni electrodes were investigated. Microstructures of the dielectrics were analyzed by transmission electron microscopy (TEM) and electron probe microanalysis (EPMA) in order to characterize the rare-earth ions. Incorporation of rare-earth ions to BaTiO3 ceramics depended on their ionic radius, resulting in different microstructures and electric performances of dielectrics. Dy ions provided BaTiO3 ceramics with ideal X7R characteristics and high reliability. The mechanism governing leakage current was discussed in terms of the voltage dependence of leakage current. Electric properties and related reliability of the capacitors were attributed to solubility, distribution of rare-earth oxides and their occupation site in BaTiO3.

  19. Using the Earth as an Effective Model for Integrating Space Science Into Education Outreach Programs

    NASA Astrophysics Data System (ADS)

    Morris, P. A.; Allen, J.; Galindo, C.; McKay, G.; Obot, V.; Reiff, P.

    2005-05-01

    Our methods of teaching Earth and space science as two disciplines do not represent the spirit of earlier scientists such as Aristotle, da Vinci, and Galileo. We need to re-evaluate these methods and take advantage of the excitement created in the general public over the recent space science exploration programs. The information that we are obtaining from both the Mars missions and Cassini-Huygens focuses on interpreting geomorphology, mineral compositions and gas identification based on Earth as a baseline for data evaluation. This type of evaluation is an extension of Hutton's 18th century principle of Uniformitarianism, the present is the key to the past, or Earth is the key for understanding extraterrestrial bodies. Geomorphological examples are volcanic activity, meteoritic impacts, and evidence of water altering surface features. The Hawaiian, or shield, type volcanoes are analogues for Olympus Mons and the other volcanoes on Mars. Other examples include comparing sand dunes on Earth with possible Martian dunes, known stream patterns on Earth with potential stream patterns on Mars, and even comparing meteoritic impact features on Mars, the Earth, Moon and Mercury. All of these comparisons have been developed into inquiry-based activities and are available through NASA publications. Each of these activities is easily adapted to emphasize either Earth science or space science or both. Beyond geomorphology, solar storms are an excellent topic for integrating Earth and space science. Solar storms are traditionally part of space science studies, but most students do not understand their effect on Earth or the intense effects they could have on humans, whether traveling through space or exploring the surfaces of the Moon or Mars. Effects are not only limited to space travel and other planetary surfaces but also include Earth's magnetosphere, which in turn, affect radio transmission and potentially climate. Like geomorphology courses, there are extensive NASA

  20. Modeling vertical deformation along the San Andreas Fault System using geodetic, geologic, groundwater, and tide gauge data

    NASA Astrophysics Data System (ADS)

    Thornton, G. M.; Smith-Konter, B. R.

    2011-12-01

    Vertical motions along the San Andreas Fault System (SAFS) are recorded by several datasets. Geodetic (EarthScope PBO GPS & InSAR) data offer ideal spatial coverage, but often include anthropogenic effects and span short time periods (~5-20 years). Geologic data (from the SCEC Vertical Motion Database) primarily capture tectonic motions over long time periods (10 Ka to 7 Ma), but offer sparse spatial coverage. Tide gauge data (from the Permanent Service for Mean Sea Level) provide a temporal record of sea level change over intermediate time periods (~30-100+ years) and reflect variations in crustal uplift and subsidence at a few isolated locations along the California coastline. Using a 3-D viscoelastic earthquake cycle deformation model spanning the last 1000 years, this study aims to explore the first-order vertical tectonic motions reflected in each of these data sets. Previous work has shown that vertical GPS and geologic data in southern California do not correlate well, possibly related to groundwater contamination and the different timescales of the datasets. To isolate groundwater deformation recorded by the GPS data, a simple groundwater correction was applied to these data using regional well log data. To isolate a tectonic signal in the tide gauge data, global sea level rise and isostatic adjustment were removed from each station and additional processing was applied to eliminate major ocean-climate signals. A suite of vertical deformation models was then computed, reflecting variations in elastic plate thickness and mantle viscosity, to search the model parameter space for the optimal parameters that minimize residual data-model misfit. Preliminary results suggest that GPS, geologic, and tide gauge datasets are best fit by thick elastic plates ranging from 70 to 90 km and viscosities ranging from 1.5e18 to 1.5e19 Pa s. These values are consistent with previous results, however further work is needed to investigate sources of misfit and unmodeled

  1. COST Action ES1401 TIDES: a European network on TIme DEpendent Seismology

    NASA Astrophysics Data System (ADS)

    Morelli, Andrea

    2016-04-01

    Using the full-length records of seismic events and background ambient noise, today seismology is going beyond still-life snapshots of the interior of the Earth, and look into time-dependent changes of its properties. Data availability has grown dramatically with the expansion of seismographic networks and data centers, so as to enable much more detailed and accurate analyses. COST Action ES1401 TIDES (TIme DEpendent Seismology; http://tides-cost.eu) aims at structuring the EU seismological community to enable development of data-intensive, time-dependent techniques for monitoring Earth active processes (e.g., earthquakes, volcanic eruptions, landslides, glacial earthquakes) as well as oil/gas reservoirs. The main structure of TIDES is organised around working groups on: Workflow integration of data and computing resources; Seismic interferometry and ambient noise; Forward problems and High-performance computing applications; Seismic tomography, full waveform inversion and uncertainties; Applications in the natural environment and industry. TIDES is an open network of European laboratories with complementary skills, and is organising a series of events - workshops and advanced training schools - as well as supporting short-duration scientific stays. The first advanced training school was held in Bertinoro (Italy) on June 2015, with attendance of about 100 participants from 20 European countries, was devoted to how to manage and model seismic data with modern tools. The next school, devoted to ambient noise, will be held in 2016 Portugal: the program will be announced at the time of this conference. TIDES will strengthen Europe's role in a critical field for natural hazards and natural resource management.

  2. Perceived Barriers and Strategies to Effective Online Earth and Space Science Instruction

    NASA Astrophysics Data System (ADS)

    Pottinger, James E.

    With the continual growth and demand of online courses, higher education institutions are attempting to meet the needs of today's learners by modifying and developing new student centered services and programs. As a result, faculty members are being forced into teaching online, including Earth and Space science faculty. Online Earth and Space science courses are different than typical online courses in that they need to incorporate an inquiry-based component to ensure students fully understand the course concepts and science principles in the Earth and Space sciences. Studies have addressed the barriers in other inquiry-based online science courses, including biology, physics, and chemistry. This holistic, multiple-case qualitative study investigated perceived barriers and strategies to effective online Earth and Space science instruction through in-depth interviews with six experienced post-secondary online science instructors. Data from this study was analyzed using a thematic analysis approach and revealed four common themes when teaching online Earth and Space science. A positive perception and philosophy of online teaching is essential, the instructor-student interaction is dynamic, course structure and design modification will occur, and online lab activities must make science operational and relevant. The findings in this study demonstrated that online Earth and Space science instructors need institutional support in the form of a strong faculty development program and support staff in order to be as effective as possible. From this study, instructors realize that the instructor-student relationship and course structure is paramount, especially when teaching online science with labs. A final understanding from this study was that online Earth and Space science lab activities must incorporate the use and application of scientific skills and knowledge. Recommendations for future research include (a) qualitative research conducted in specific areas within the

  3. Effect of the shrinking dipole on solar-terrestrial energy input to the Earth's atmosphere

    NASA Astrophysics Data System (ADS)

    McPherron, R. L.

    2011-12-01

    The global average temperature of the Earth is rising rapidly. This rise is primarily attributed to the release of greenhouse gases as a result of human activity. However, it has been argued that changes in radiation from the Sun might play a role. Most energy input to the Earth is light in the visible spectrum. Our best measurements suggest this power input has been constant for the last 40 years (the space age) apart from a small 11-year variation due to the solar cycle of sunspot activity. Another possible energy input from the Sun is the solar wind. The supersonic solar wind carries the magnetic field of the Sun into the solar system. As it passes the Earth it can connect to the Earth's magnetic field whenever it is antiparallel t the Earth's field. This connection allows mass, momentum, and energy from the solar wind to enter the magnetosphere producing geomagnetic activity. Ultimately much of this energy is deposited at high latitudes in the form of particle precipitation (aurora) and heating by electrical currents. Although the energy input by this process is miniscule compared to that from visible radiation it might alter the absorption of visible radiation. Two other processes affected by the solar cycle are atmospheric entry of galactic cosmic rays (GCR) and solar energetic protons (SEP). A weak solar magnetic field at sunspot minimum facilitates GCR entry which has been implicated in creation of clouds. Large coronal mass ejections and solar flares create SEP at solar maximum. All of these alternative energy inputs and their effects depend on the strength of the Earth's magnetic field. Currently the Earth's field is decreasing rapidly and conceivably might reverse polarity in 1000 years. In this paper we describe the changes in the Earth's magnetic field and how this might affect GCR, SEP, electrical heating, aurora, and radio propagation. Whether these effects are important in global climate change can only be determined by detailed physical models.

  4. Relativity mission with two counter-orbiting polar satellites. [nodal dragging effect on earth orbiting satellites

    NASA Technical Reports Server (NTRS)

    Van Patten, R. A.; Everitt, C. W. F.

    1975-01-01

    In 1918, J. Lense and H. Thirring calculated that a moon in orbit around a massive rotating planet would experience a nodal dragging effect due to general relativity. We describe an experiment to measure this effect with two counter-orbiting drag-free satellites in polar earth orbit. For a 2 1/2 year experiment, the measurement accuracy should approach 1%. In addition to precision tracking data from existing ground stations, satellite-to-satellite Doppler ranging data are taken at points of passing near the poles. New geophysical information on both earth harmonics and tidal effects is inherent in the polar ranging data.

  5. TIDE TOOL: Open-Source Sea-Level Monitoring Software for Tsunami Warning Systems

    NASA Astrophysics Data System (ADS)

    Weinstein, S. A.; Kong, L. S.; Becker, N. C.; Wang, D.

    2012-12-01

    -series data in the GUI as well. This GUI also includes mouse-clickable functions such as zooming or expanding the time-series display, measuring tsunami signal characteristics (arrival time, wave period and amplitude, etc.), and removing the tide signal from the time-series data. De-tiding of the time series is necessary to obtain accurate measurements of tsunami wave parameters and to maintain accurate historical tsunami databases. With TIDE TOOL, de-tiding is accomplished with a set of tide harmonic coefficients routinely computed and updated at PTWC for many of the stations in PTWC's inventory (~570). PTWC also uses the decoded time series files (previous 3-5 days' worth) to compute on-the-fly tide coefficients. The latter is useful in cases where the station is new and a long-term stable set of tide coefficients are not available or cannot be easily obtained due to various non-astronomical effects. The international tsunami warning system is coordinated globally by the UNESCO IOC, and a number of countries in the Pacific and Indian Ocean, and Caribbean depend on Tide Tool to monitor tsunamis in real time.

  6. Effect of Solar Variability on Earth Climate Patterns.

    NASA Astrophysics Data System (ADS)

    Ruzmaikin, A.; Feynman, J.

    2006-12-01

    We discuss the impact of solar variability on the patterns of Earth climate variability. These climate patterns are naturally excited in the noisy atmosphere-ocean dynamical system as deviations (anomalies) from a global (mean) state. The patterns include North Atlantic Oscillation (NAO) and related Northern Annular Mode (NAM), Southern Annular Mode (SAM), Pacific Decadal Oscillation (PDO), Atlantic Multidecadal Oscillation (AMO). An example of a pattern influenced by variations in solar UV irradiance is the NAM, a wintertime climate anomaly with two states corresponding to higher pressure at high latitudes with a band of lower pressure at lower latitudes and the other way round (Thompson &Wallace, 1998). Two states of the NAM arise due to the dynamical interaction of planetary waves and zonal mean wind (Limpasuvan &Hartmann, 2001; Ruzmaikin et al., 2006). The NAM accounts for 23% of atmospheric variability at sea level and about 50% of the variability in the stratosphere. Solar variability affects the NAM and that the influence varies dependent on the phase of the Quasi Biennial Oscillation and time in the winter season (Ruzmaikin &Feynman, 2002). The temperature pattern (cold in Europe-warm in Greenland) produced by the negative NAM was dominant during the Maunder Minimum of solar activity (Ruzmaikin et al., 2004). We discuss possible physical mechanisms by which solar variability can influence the climate patterns. In particular, we address the Rossby-Palmer hypothesis (Palmer, 1998) that external forcing (in our case solar variability) may affect only the magnitude of the pattern variability without changing its spatial structure. References: Thompson, D. W. J. &J. M. Wallace, Geophys. Res. Lett., 25, 1297, 1998; Palmer, T. N., Bull. Amer. Meteor. Soc., 79, 1412 1998; Baldwin, M. P. and T. J. Dunkerton, J. Geophys. Res. 104, 30,937, 1999; Limpasuvan, V., &D. Hartmann, J. Climate, 13, 4414, 2001; Ruzmaikin, A., J, Feynman, J. Geophys. Res., 107, D14, 10

  7. Green and golden seaweed tides on the rise.

    PubMed

    Smetacek, Victor; Zingone, Adriana

    2013-12-05

    Sudden beaching of huge seaweed masses smother the coastline and form rotting piles on the shore. The number of reports of these events in previously unaffected areas has increased worldwide in recent years. These 'seaweed tides' can harm tourism-based economies, smother aquaculture operations or disrupt traditional artisanal fisheries. Coastal eutrophication is the obvious, ultimate explanation for the increase in seaweed biomass, but the proximate processes that are responsible for individual beaching events are complex and require dedicated study to develop effective mitigation strategies. Harvesting the macroalgae, a valuable raw material, before they beach could well be developed into an effective solution.

  8. The effect of SST emissions on the earth's ozone layer

    NASA Technical Reports Server (NTRS)

    Whitten, R. C.; Turco, R. P.

    1974-01-01

    The work presented here is directed toward assessment of environmental effects of the supersonic transport (SST). The model used for the purpose includes vertical eddy transport and the photochemistry of the O-H-N system. It is found that the flight altitude has a pronounced effect on ozone depletion. The largest ozone reduction occurs for NO deposition above an altitude of 20 km.

  9. New Miscellaneous Results in Tides from Topex/Poseidon

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.; Egbert, G.; Cartwright, D.; Smith, David E. (Technical Monitor)

    2000-01-01

    This paper describes a variety of new results concerning ocean tides that have been derived from Topex/Poseidon satellite altimeter data. Most of these results are based on new tidal solutions employing nearly 8 years of data. The topics covered include internal tides and long-period tides.

  10. Using Tide Data in Introductory Classes

    ERIC Educational Resources Information Center

    De Jong, Marvin L.

    2006-01-01

    Oceantides are not typically high in our consciousness here in Missouri, but in teaching astronomy and physical science the subject always comes up, and teachers of physical science and astronomy are all quite familiar with the textbook explanations. Our goal here is not to explain tides but to make some suggestions about how, on their own,…

  11. Tidal asymmetry in a funnel-shaped estuary with mixed semidiurnal tides

    NASA Astrophysics Data System (ADS)

    Gong, Wenping; Schuttelaars, Henk; Zhang, Heng

    2016-05-01

    competition among the above interactions determines the FDA and TDA, whereas for the FVA, aside from the interaction among different tidal constituents, an extra component, the residual flow, plays an important role. The results show that the FDA exhibits a predominant tendency of shorter duration of low water slack, favoring the landward transport of fine sediment. The FVA demonstrates prevailing ebb dominance in the study period, favoring the seaward transport of coarse sediment. This ebb dominance is primarily induced by the interaction among the residual flow and the tidal constituents. The external TDA in the ocean experiences distinct cyclic variations with positive asymmetry when semidiurnal tides dominate and negative asymmetry during the periods when diurnal tides dominate. The funnel shape of the HE is advantageous for the development of positive tidal asymmetry as the semidiurnal tides are more amplified than the diurnal tides. The effect of river flow can enhance the ebb dominance, while the baroclinic effect is more complex. The existence of channel and shoals favors the development of residual pattern with seaward flow (ebb dominance) in the channel and landward flow (flood dominance) at the shoal when the tides are strong (semidiurnal tides dominate) and the residual pattern with landward flow (flood dominance) in the channel and seaward flow (ebb dominance) at the shoal when the baroclinic effect is dominant (diurnal tides dominate).

  12. Changes in Work Habits of Lifeguards in Relation to Florida Red Tide.

    PubMed

    Nierenberg, Kate; Kirner, Karen; Hoagland, Porter; Ullmann, Steven; Leblanc, William G; Kirkpatrick, Gary; Fleming, Lora E; Kirkpatrick, Barbara

    2010-05-01

    The marine dinoflagellate, Karenia brevis, is responsible for Florida red tides. Brevetoxins, the neurotoxins produced by K. brevis blooms, can cause fish kills, contaminate shellfish, and lead to respiratory illness in humans. Although several studies have assessed different economic impacts from Florida red tide blooms, no studies to date have considered the impact on beach lifeguard work performance. Sarasota County experiences frequent Florida red tides and staffs lifeguards at its beaches 365 days a year. This study examined lifeguard attendance records during the time periods of March 1 to September 30 in 2004 (no bloom) and March 1 to September 30 in 2005 (bloom). The lifeguard attendance data demonstrated statistically significant absenteeism during a Florida red tide bloom. The potential economic costs resulting from red tide blooms were comprised of both lifeguard absenteeism and presenteeism. Our estimate of the costs of absenteeism due to the 2005 red tide in Sarasota County is about $3,000. On average, the capitalized costs of lifeguard absenteeism in Sarasota County may be on the order of $100,000 at Sarasota County beaches alone. When surveyed, lifeguards reported not only that they experienced adverse health effects of exposure to Florida red tide but also that their attentiveness and abilities to take preventative actions decrease when they worked during a bloom, implying presenteeism effects. The costs of presenteeism, which imply increased risks to beachgoers, arguably could exceed those of absenteeism by an order of magnitude. Due to the lack of data, however, we are unable to provide credible estimates of the costs of presenteeism or the potential increased risks to bathers.

  13. Plasma and magnetic field variations in the distant magnetotail associated with near-earth substorm effects

    NASA Technical Reports Server (NTRS)

    Baker, D. N.; Bame, S. J.; Mccomas, D. J.; Zwickl, R. D.; Slavin, J. A.; Smith, E. J.

    1987-01-01

    Examination of many individual event periods in the ISEE 3 deep-tail data set has suggested that magnetospheric substorms produce a characteristic pattern of effects in the distant magnetotail. During the growth, or tail-energy-storage phase of substorms, the magnetotail appears to grow diametrically in size, often by many earth radii. Subsequently, after the substorm expansive phase onset at earth, the distant tail undergoes a sequence of plasma, field, and energetic-particle variations as large-scale plasmoids move rapidly down the tail following their disconnection from the near-earth plasma sheet. ISEE 3 data are appropriate for the study of these effects since the spacecraft remained fixed within the nominal tail location for long periods. Using newly available auroral electrojet indices (AE and AL) and Geo particle data to time substorm onsets at earth, superposed epoch analyses of ISEE 3 and near-earth data prior to, and following, substorm expansive phase onsets have been performed. These analyses quantify and extend substantially the understanding of the deep-tail pattern of response to global substorm-induced dynamical effects.

  14. Relativistic Effect on Multiplet Terms of Rare Earth Ions

    NASA Astrophysics Data System (ADS)

    Itoh, Shinichi; Saito, Riichiro; Kimura, Tadamasa; Yabushita, Satoshi

    1994-02-01

    Ab initio Spin-Orbit Configuration Interaction (SOCI) calculations for the trivalent lanthanide group ions are presented for the special purpose to investigate the relativistic SO effects on their multiplet terms. The effective nuclear charges (Z eff's) for one-body spin-orbit Hamiltonian are calculated by an atomic Dirac-Slater Xα equation and applied to the lanthanide ions. The relativistic effects of core electrons can easily be included in the reduction of Z eff and the multiplet levels shift up to 200 cm-1 by the reduction. The multiplet energies obtained by the present method are in good agreement with experimental values.

  15. Climatic effects due to halogenated compounds in the earth's atmosphere

    NASA Technical Reports Server (NTRS)

    Wang, W.-C.; Pinto, J. P.; Yung, Y. L.

    1980-01-01

    Using a one-dimensional radiative-convective model, a sensitivity study is performed of the effect of ozone depletion in the stratosphere on the surface temperature. There could be a cooling of the surface temperature by approximately 0.2 K due to chlorofluoromethane-induced ozone depletion at steady state (assuming 1973 release rates). This cooling reduces significantly the greenhouse effect due to the presence of chlorofluoromethanes. Carbon tetrafluoride has a strong nu sub 3 band at 7.8 microns, and the atmospheric greenhouse effect is shown to be 0.07 and 0.12 K/ppbv with and without taking into account overlap with CH4 and N2O bands. At concentrations higher than 1 ppbv, absorption by the nu sub 3 band starts to saturate and the greenhouse effect becomes less efficient.

  16. Thulium anomalies and rare earth element patterns in meteorites and Earth: Nebular fractionation and the nugget effect

    NASA Astrophysics Data System (ADS)

    Dauphas, Nicolas; Pourmand, Ali

    2015-08-01

    This study reports the bulk rare earth element (REEs, La-Lu) compositions of 41 chondrites, including 32 falls and 9 finds from carbonaceous (CI, CM, CO and CV), enstatite (EH and EL) and ordinary (H, L and LL) groups, as well as 2 enstatite achondrites (aubrite). The measurements were done in dynamic mode using multi-collector inductively coupled plasma mass spectrometers (MC-ICPMS), allowing precise quantification of mono-isotopic REEs (Pr, Tb, Ho and Tm). The CI-chondrite-normalized REE patterns (LaN/LuN; a proxy for fractionation of light vs. heavy REEs) and Eu anomalies in ordinary and enstatite chondrites show more scatter in more metamorphosed (petrologic types 4-6) than in unequilibrated (types 1-3) chondrites. This is due to parent-body redistribution of the REEs in various carrier phases during metamorphism. A model is presented that predicts the dispersion of elemental and isotopic ratios due to the nugget effect when the analyzed sample mass is limited and elements are concentrated in minor grains. The dispersion in REE patterns of equilibrated ordinary chondrites is reproduced well by this model, considering that REEs are concentrated in 200 μm-size phosphates, which have high LaN/LuN ratios and negative Eu anomalies. Terrestrial rocks and samples from ordinary and enstatite chondrites display negative Tm anomalies of ∼-4.5% relative to CI chondrites. In contrast, CM, CO and CV (except Allende) show no significant Tm anomalies. Allende CV chondrite shows large excess Tm (∼+10%). These anomalies are similar to those found in group II refractory inclusions in meteorites but of much smaller magnitude. The presence of Tm anomalies in meteorites and terrestrial rocks suggests that either (i) the material in the inner part of the solar system was formed from a gas reservoir that had been depleted in refractory dust and carried positive Tm anomalies or (ii) CI chondrites are enriched in refractory dust and are not representative of solar composition for

  17. A tide prediction and tide height control system for laboratory mesocosms

    PubMed Central

    Long, Jeremy D.

    2015-01-01

    Experimental mesocosm studies of rocky shore and estuarine intertidal systems may benefit from the application of natural tide cycles to better replicate variation in immersion time, water depth, and attendant fluctuations in abiotic and edaphic conditions. Here we describe a stand-alone microcontroller tide prediction open-source software program, coupled with a mechanical tidal elevation control system, which allows continuous adjustment of aquarium water depths in synchrony with local tide cycles. We used this system to monitor the growth of Spartina foliosa marsh cordgrass and scale insect herbivores at three simulated shore elevations in laboratory mesocosms. Plant growth decreased with increasing shore elevation, while scale insect population growth on the plants was not strongly affected by immersion time. This system shows promise for a range of laboratory mesocosm studies where natural tide cycling could impact organism performance or behavior, while the tide prediction system could additionally be utilized in field experiments where treatments need to be applied at certain stages of the tide cycle. PMID:26623195

  18. A tide prediction and tide height control system for laboratory mesocosms.

    PubMed

    Miller, Luke P; Long, Jeremy D

    2015-01-01

    Experimental mesocosm studies of rocky shore and estuarine intertidal systems may benefit from the application of natural tide cycles to better replicate variation in immersion time, water depth, and attendant fluctuations in abiotic and edaphic conditions. Here we describe a stand-alone microcontroller tide prediction open-source software program, coupled with a mechanical tidal elevation control system, which allows continuous adjustment of aquarium water depths in synchrony with local tide cycles. We used this system to monitor the growth of Spartina foliosa marsh cordgrass and scale insect herbivores at three simulated shore elevations in laboratory mesocosms. Plant growth decreased with increasing shore elevation, while scale insect population growth on the plants was not strongly affected by immersion time. This system shows promise for a range of laboratory mesocosm studies where natural tide cycling could impact organism performance or behavior, while the tide prediction system could additionally be utilized in field experiments where treatments need to be applied at certain stages of the tide cycle.

  19. Galactic cosmic rays - atmosphere clouds effect and bifurcation model of the Earth global climate

    NASA Astrophysics Data System (ADS)

    Glushkov, Alexander

    The possible physical linkage between the cosmic rays, atmosphere cloud and indirect aerosol effects is discussed using analysis of first indirect aerosol effect (Twomey effect) and its experimental representation as the dependence of mean cloud droplet effective radius versus aerosol index defining the column aerosol number. It is shown that the main kinetic equation of Earth climate energy-balance model [1] is described by the bifurcation equation (relative to the Earth surface temperature) in the form of fold catastrophe with two controlling parameters defining the variations of insolation and Earth magnetic field (or cosmic rays intensity in the atmosphere) respectively. The results of comparative analysis on the time-dependent solution (time series of global paleotemperature ) of Earth climate energy-balance model taking into account nontrivial role of galactic cosmic rays and the known experimental data on the palaeotemperature from the EPICA Dome C and Vostok ice core are pre-sented. It is discussed the sin-earth mechanism of arising the abnormal temperature breaks which are observed in the EPICA Dome C and Vostok experiments. It has been found its link with the ‘order-chaos' transitions in evolution of the convection in the Earth liquid core which are responsible for mechanism of arising inversions of the magnetic field of the Earth. It should be noted a stabilization role of the slow nuclear burning [1] georeactor with power 30 TW) on the boundary of the liquid and solid phases of the Earth's core in evolution of convection in the Earth liquid core and magnetic field. In the bifurcation model (i) the possibility of abrupt glacial climate changes analogous to the Dansgaard-Oeschger events due to stochastic resonance is theoretically argued, (ii) the concept of the climatic sensitivity of water (vapour and liquid) in the atmosphere is introduced. This concept reveals the property of temperature instability in a form of so-called hysteresis loop. It is

  20. Temporal variations of groundwater salinity and temperature in a tidal flat in front of a tide pool

    NASA Astrophysics Data System (ADS)

    Nakashita, Shinya; Hibino, Tadashi; Komai, Katsuaki; Narong, Touch

    2016-07-01

    A tidal flat in an estuary is a complex hydrological system, which is characterized by interactions between surface water in river and groundwater and is particularly driven by tides. Small-scale variability in the discharge or inflow could lead to variable results of surface groundwater salinity and temperature. In particular, there is a high possibility that a hydraulic head difference due to the presence of a tide pool, lagoon, or seep would cause the generation of small-scale spatial submarine groundwater discharge. This study investigates the spatio-temporal variations in surface groundwater salinity and temperature (0-50 cm depth) and the groundwater table in a tidal flat in the presence and absence of a tide pool. A tide pool formed in the Ota River diversion channel at the study observation site following the construction of a masonry revetment in the intertidal zone. We established observation sites at three locations to consider the effects of the presence or absence of a tide pool. Specifically, we measured the surface water in river and groundwater salinity, temperature, and level in the presence and absence of a tide pool in 2007 and 2009. Reviewing the past data based on these results, we found the characteristic variation of groundwater salinity around the tide pool during flood event in 2004. Groundwater salinity and temperature were directly measured by setting conductivity-temperature meters in the tidal flat. We conclude that the groundwater table in the presence of the tide pool was 20 cm higher than in areas where no tide pool existed. The temporal variation of groundwater salinity in the presence of the tide pool was 5 psu lower than those where a tide pool was absent. Moreover, we confirmed the increase in groundwater salinity up to 8 psu in the tidal flat during flood, when river water salinity was at 0 psu and groundwater salinity in the tide pool was at 10 psu. We consider that the high groundwater table, the low salinity, and the increase

  1. Tides and lake-level variations in the great Patagonian lakes: Observations, modelling and geophysical implications.

    NASA Astrophysics Data System (ADS)

    Marderwald, Eric; Richter, Andreas; Horwath, Martin; Hormaechea, Jose Luis; Groh, Andreas

    2016-04-01

    In Patagonia, the glacial-isostatic adjustment (GIA) to past ice-mass changes (Ivins & James 2004; Klemann et al. 2007) is of particular interest in the context of the determination of the complex regional rheology related to plate subduction in a triple-junction constellation. To further complicate the situation, GIA is overlaid with load deformation not only due to present ice mass changes but also due to water-level changes in the lakes surrounding the icefields and the ocean surrounding Patagonia. These elastic deformations affect the determination of glacial-isostatic uplift rates from GPS observations (Dietrich et al. 2010; Lange et al. 2014). Observations of lake tides and their comparison with the theoretical tidal signal have been used previously to validate predictions of ocean tidal loading and have revealed regional deviations from conventional global elastic earth models (Richter et al. 2009). In this work we investigate the tides and lake-level variations in Lago Argentino, Lago Viedma, Lago San Martín/O'Higgins and Lago Buenos Aires/General Carrera. This allows us to test, among other things, the validity of tidal loading models. We present pressure tide-gauge records from two sites in Lago Argentino extending over 2.5 years (Richter et al. 2015). These observations are complemented by lake-level records provided by the Argentine National Hydrometeorological Network. Based on these lake-level time series the principal processes affecting the lake level are identified and quantified. Lake-level changes reflecting variations in lake volume are dominated by a seasonal cycle exceeding 1 m in amplitude. Lake-volume changes occur in addition with a daily period in response to melt water influx from surrounding glaciers. In Lago Argentino sporadic lake-volume jumps are caused by bursting of the ice dam of Perito Moreno glacier. Water movements in these lakes are dominated by surface seiches reaching 20 cm in amplitude. A harmonic tidal analysis of the lake

  2. Female "Big Fish" Swimming against the Tide: The "Big-Fish-Little-Pond Effect" and Gender-Ratio in Special Gifted Classes

    ERIC Educational Resources Information Center

    Preckel, Franzis; Zeidner, Moshe; Goetz, Thomas; Schleyer, Esther Jane

    2008-01-01

    This study takes a second look at the "big-fish-little-pond effect" (BFLPE) on a national sample of 769 gifted Israeli students (32% female) previously investigated by Zeidner and Schleyer (Zeidner, M., & Schleyer, E. J., (1999a). "The big-fish-little-pond effect for academic self-concept, test anxiety, and school grades in…

  3. Global single ion effects within the Earth's plasma sheet

    NASA Astrophysics Data System (ADS)

    Rothwell, Paul L.; Yates, G. Kenneth

    Two global properties of single ion motion in the magnetotail are examined. The first effect is caused by the magnetic field in the plasma sheet directing boundary ions to the neutral sheet. Exact solutions to the Lorentz equation indicate that these ions can have sufficient energy to trigger the ion tearing mode if Bo/aBz > 6.0, where Bo is the tail lobe magnetic field, Bz is the magnetic field in the north-south direction and `a' is a parameter related to the growth of the ion tearing instability. It is found that this effect occurs at a lower energy for oxygen than for protons. The second global property is related to the thinning or expansion of the plasma sheet. The results indicate that in the absence of reconnection the plasma sheet adiabatically maintains equilibruim by allowing plasma and magnetic flux to cross the boundaries. The presence of reconnection modifies the flow across the boundaries as well as the spatial distribution of the induced electric field.

  4. Global single ion effects within the earth's plasma sheet

    NASA Astrophysics Data System (ADS)

    Rothwell, P. L.; Yates, G. K.

    Two global properties of single-ion motion in the magnetotail are examined. The first effect is caused by the magnetic field in the plasma sheet directing boundary ions to the neutral sheet. Exact solutions to the Lorentz equation indicate that these ions can have sufficient energy to trigger the ion tearing mode if B0/aBz is greater than 6.0, where B0 is the tail-lobe magnetic field, Bz is the magnetic field in the north-south direction, and a is a parameter related to the growth of the ion tearing instability. It is found that this effect occurs at a lower energy for oxygen than for protons. The second global property is related to the thinning or expansion of the plasma sheet. In the absence of reconnection, the plasma sheet adiabatically maintains equilibrium by allowing plasma and magnetic flux to cross the boundaries. The presence of reconnection modifies the flow across the boundaries as well as the spatial distribution of the induced electric field.

  5. Low Earth Orbit Environmental Effects on Space Tether Materials

    NASA Technical Reports Server (NTRS)

    Finckernor, Miria M.; Gitlemeier, Keith A.; Hawk, Clark W.; Watts, Ed

    2005-01-01

    Atomic oxygen (AO) and ultraviolet (UV) radiation erode and embrittle most polymeric materials. This research was designed to test several different materials and coatings under consideration for their application to space tethers, for resistance to these effects. The samples were vacuum dehydrated, weighed and then exposed to various levels of AO or UV radiation at the NASA Marshall Space Flight Center. They were then re-weighed to determine mass loss due to atomic oxygen erosion, inspected for damage and tensile tested to determine strength loss. The experiments determined that the Photosil coating process, while affording some protection, damaged the tether materials worse than the AO exposure. TOR-LM also failed to fully protect the materials, especially from UV radiation. The POSS and nickel coatings did provide some protection to the tethers, which survived the entire test regime. M5 was tested, uncoated, and survived AO exposure, though its brittleness prevented any tensile testing.

  6. Imaging the earth's magnetosphere - Effects of plasma flow and temperature

    NASA Technical Reports Server (NTRS)

    Garrido, D. E.; Smith, R. W.; Swift, D. S.; Akasofu, S.-I.

    1991-01-01

    The effects of Doppler shifting on the line centers of the magnetospheric O(+) cross section are investigated, and the resulting structure of the scattering rate as a function of bulk density is explained. Whereas the Doppler shifting frequently results in a decrease of the scattering rate, it is demonstrated that for certain drift speeds the overlap of the cross section and the solar intensity profile can lead to an increased rate, thus enhancing the relative brightness of the image above that obtained when v(p) is zero. Simulated images of the magnetosphere are obtained which are used to show quantitively how the magnetospheric image responds to variations in plasma drift speed and temperature. Changes in the brightness of the magnetospheric images also depend on the variability of the solar flux at 83.4 nm. In regions where there are plasma drifts, the brightness in the image is governed by the structure of the scattering rate, assuming a fixed temperature.

  7. The Effects of an Earth Science Curriculum Revision on Teacher Behavior and Student Achievement. Final Report.

    ERIC Educational Resources Information Center

    Orgren, James R.

    A two-year study on the effects of adopting the 1970 revision of the New York State Regents Earth Science Syllabus on teachers' teaching strategies and educational opinions and students' abilities and performance was reported. A total of about 30 teachers and their classrooms were used. One group used the old syllabus in the first year and the new…

  8. Relativistic effects of the rotation of the earth on remote clock synchronization

    NASA Technical Reports Server (NTRS)

    Reinhardt, V.

    1974-01-01

    A treatment is given of relativistic clock synchronization effects due to the rotation of the earth. Unlike other approaches, the point of view of an earth fixed coordinate system is used which offers insight to many problems. An attempt is made to give the reader an intuitive grasp of the subject as well as to provide formulae for his use. Specific applications to global timekeeping, navigation, VLBI, relativistic clock experiments, and satellite clock synchronization are discussed. The question of whether atomic clocks are ideal clocks is also treated.

  9. The effects of solar Reimers η on the final destinies of Venus, the Earth, and Mars

    NASA Astrophysics Data System (ADS)

    Guo, Jianpo; Lin, Ling; Bai, Chunyan; Liu, Jinzhong

    2016-04-01

    Our Sun will lose sizable mass and expand enormously when it evolves to the red giant branch phase and the asymptotic giant branch phase. The loss of solar mass will push a planet outward. On the contrary, solar expansion will enhance tidal effects, and tidal force will drive a planet inward. Will our Sun finally engulf Venus, the Earth, and Mars? In the literature, one can find a large number of studies with different points of view. A key factor is that we do not know how much mass the Sun will lose at the late stages. The Reimers η can describe the efficiency of stellar mass-loss and greatly affect solar mass and solar radius at the late stages. In this work, we study how the final destinies of Venus, the Earth, and Mars can be depending on Reimers η chosen. In our calculation, the Reimers η varies from 0.00 to 0.75, with the minimum interval 0.0025. Our results show that Venus will be engulfed by the Sun and Mars will most probably survive finally. The fate of the Earth is uncertain. The Earth will finally be engulfed by the Sun while η <0.4600, and it will finally survive while η ≥ 0.4600. New observations indicate that the average Reimers η for solar-like stars is 0.477. This implies that Earth may survive finally.

  10. Crystal-field interaction and oxygen stoichiometry effects in strontium-doped rare-earth cobaltates

    NASA Astrophysics Data System (ADS)

    Furrer, A.; Podlesnyak, A.; Frontzek, M.; Sashin, I.; Embs, J. P.; Mitberg, E.; Pomjakushina, E.

    2014-08-01

    Inelastic neutron scattering was employed to study the crystal-field interaction in the strontium-doped rare-earth compounds RxSr1-xCoO3-z (R=Pr, Nd, Ho, and Er). Particular emphasis is laid on the effect of oxygen deficiencies that naturally occur in the synthesis of these compounds. The observed energy spectra are found to be the result of a superposition of crystal fields with different nearest-neighbor oxygen coordination at the R sites. The experimental data are interpreted in terms of crystal-field parameters, which behave in a consistent manner through the rare-earth series, thereby allowing a reliable extrapolation for rare-earth ions not considered in the present work.

  11. The Study of Effects of Time Variations in the Earth's Gravity Field on Geodetic Satellites

    NASA Technical Reports Server (NTRS)

    Shum, C. K.

    1998-01-01

    The temporal variations in the Earth's gravity field are the consequences of complex interactions between atmosphere, ocean, solid Earth, hydrosphere and cryosphere. The signal ranges from several hours to 18.6 years to geological time scale. The direct and indirect consequences of these variations are manifested in such phenomena as changes in the global sea level and in the global climate pattern. These signals produce observable geodetic satellites. The primary objectives of the proposed effects on near-Earth orbiting investigation include (1) the improved determination of the time-varying gravity field parameters (scale from a few hour to 18.6 year and secular) using long-term satellite laser rs ranging (SLR) observations to multiple geodetic satellites, and (2) the enhanced understanding of these variations with their associated meteorological and geophysical consequences.

  12. Spatial nonlinearities: Cascading effects in the earth system

    USGS Publications Warehouse

    Peters, Debra P.C.; Pielke, R.A.; Bestelmeyer, B.T.; Allen, Craig D.; Munson-McGee, S.; Havstad, K. M.

    2006-01-01

    Nonlinear interactions and feedbacks associated with thresholds through time and across space are common features of biological, physical and materials systems. These spatial nonlinearities generate surprising behavior where dynamics at one scale cannot be easily predicted based on information obtained at finer or broader scales. These cascading effects often result in severe consequences for the environment and human welfare (i.e., catastrophes) that are expected to be particularly important under conditions of changes in climate and land use. In this chapter, we illustrate the usefulness of a general conceptual and mathematical framework for understanding and forecasting spatially nonlinear responses to global change. This framework includes cross-scale interactions, threshold behavior and feedback mechanisms. We focus on spatial nonlinearities produced by fine-scale processes that cascade through time and across space to influence broad spatial extents. Here we describe the spread of catastrophic events in the context of our cross-disciplinary framework using examples from biology (wildfires, desertification, infectious diseases) and engineering (structural failures) and discuss the consequences of applying these ideas to forecasting future dynamics under a changing global environment.

  13. Using inquiry-based instruction with Web-based data archives to facilitate conceptual change about tides among preservice teachers

    NASA Astrophysics Data System (ADS)

    Ucar, Sedat

    The purpose of this mixed methods study was to describe and understand preservice teachers' conceptions of tides and to explore an instructional strategy that might promote the learning of scientific concepts. The participants were preservice teachers in three initial licensure programs. A total of 80 graduate students, in secondary, middle, and early childhood education programs completed a multiple choice assessment of their knowledge of tides-related concepts. Thirty of the 80 participants were interviewed before the instruction. Nineteen of the 30 students who were interviewed also participated in the instruction and were interviewed after the instruction. These 19 students also completed both the pre-test and 18 of them completed the post-test on tides and related content. Data regarding the participants' conceptual understandings of tides were collected before and after the instruction using both qualitative and quantitative data collection methods. A multiple choice pre-test was developed by the researcher. The same test was used before and after the instructional intervention. Structured interviews were conducted with participants before and after instruction. In addition to interviews, participants were asked to write a short journal after instruction. The constant comparative method was used to analyze the qualitative data. Preservice teachers' conceptual understandings of tides were categorized under six different types of conceptual understandings. Before the instruction, all preservice teachers held alternative or alternative fragments as their types of conceptual understandings of tides, and these preservice teachers who held alternative conceptions about tides were likely to indicate that there is one tidal bulge on Earth. They tried to explain this one tidal bulge using various alternative conceptions. After completing an inquiry-based and technology-enhanced instruction of tides, preservice teachers were more likely to hold a scientific conceptual

  14. The Effect of Rare Earth Dopants on UO2 Oxidation

    SciTech Connect

    Hanson, Brady D.; Cumblidge, Stephen E.; Scheele, Randall D.; Sell, Rachel L.

    2003-06-01

    Recent work by Hanson [1] has demonstrated a clear dependence of the oxidation of Light Water Reactor spent fuel on burnup. Oxidation of spent fuel was shown to proceed via the two-step reaction UO2?UO2.4?UO2.67+x, where the U3O8-like phase does not form until conversion to UO2.4 is complete. The temperature-dependent activation energy (Ea) of the transition from UO2.4 to the hyperstoichiometric U3O8 was found to be {approx}150 kJ mol-1. Each MWD/kg M burnup added {approx}1.0 kJ mol-1. The work of McEachern et.al. [2], Choi et. al. [3], and You et. al. [4] have all verified this oxidation dependence on SIMFUEL or unirradiated doped-UO2. All present work agrees that the soluble actinides or fission products that substitute in the U matrix act to delay the onset of U3O8. However, no single model exists to explain the observed behavior, including the fact that most dopants actually allow an earlier onset for UO2.4 formation. The present work is part of a Nuclear Energy Research Initiative project attempting to develop a UO2-based matrix capable of achieving extended burnups by including soluble dopants. The resulting fuel should be highly oxidation and dissolution resistant, which will be beneficial during accident scenarios or for disposal in a geologic repository. In addition, the stabilized matrix may help delay the onset of fuel restructuring that occurs at higher burnups. Initial results of the oxidation tests to quantify effects as a function of ionic radii and charge of the dopant are presented.

  15. The vertical structure and temporal variability of the atmospheric tides over South Pole

    NASA Astrophysics Data System (ADS)

    Lau, E.; Palo, S.; Avery, S.; Avery, J.; Iimura, H.; Makarov, N.

    Studies of the mesosphere and lower thermosphere MLT over the South Pole during the 1990s revealed the existence of an unexpected westward propagating semidiurnal tidal component with zonal wavenumber one This tidal component was first observed in the austral winter using optical instruments Observations made later with a meteor radar in the mid 1990s showed that this nonmigrating component of the semidiurnal tide had a much larger amplitude during the austral summer sim 20 m s and practically disappeared during the winter A similar behavior was observed for the migrating diurnal tide but with smaller amplitudes Initial comparisons of the nonmigrating component of the semidiurnal tide with models like the Global Scale Wave Model GSWM showed that the observed amplitudes were significantly larger than the model predictions However the GSWM only includes nonmigrating tidal components generated via latent heating and it is believed that the nonmigrating semidiurnal tide observed at South Pole is the result of a nonlinear interaction between the migrating semidiurnal tide and the wave one stationary planetary wave Recently the Middle Atmosphere Circulation Model at Kyushu University MACMKU was able to reproduce some of the main temporal variations of the observations as nonlinear effects are included in this general circulation model However the MACMKU maximum amplitudes were larger than the observations A new meteor radar was installed at the Amundsen-Scott station at the South Pole in 2001 to further the understanding of the dynamics

  16. QBO Generated Inter-annual Variations of the Diurnal Tide in the Mesosphere

    NASA Technical Reports Server (NTRS)

    Mayr, Hans G.; Mengel, John G.

    2004-01-01

    We report results from a study with the Numerical Spectral Model (NSM), which produces in the d i d tide significant inter-annual variations. Applying Hines' Doppler Spread Parameterization (DPS), small-scale gravity waves (GW) drive the Quasi-biennial Oscillation (QBO) and Semi-annual Oscillation (SAO). With a GW source that peaks at the equator and is taken to be isotropic and independent of season, the NSM generates a QBO with variable periods around 27 months and zonal wind amplitudes close to 20 m/s at 30 lan, As reported earlier, the NSM reproduces the observed equinoctial maxima in the diurnal tide at altitudes around 95 km. In the present paper it is shown that the QBO modulates the tide such that the seasonal amplitude maxima can vary from one year to another by as much as 30%. Since the period of the QBO is variable, its phase relative to the seasonal cycle changes. The magnitude of the QBO modulation of the tide thus varies considerably as our long-term model simulation shows. To shed light on the underlying mechanisms, we discuss (a) the relative importance of the linearized advection terms that involve the meridional and vertical winds of the diurnal tide and (b) the effects momentum deposition from GWs filtered by the QBO.

  17. The Effect of the Earth's and Stray Magnetic Fields on Mobile Mass Spectrometer Systems

    NASA Astrophysics Data System (ADS)

    Bell, Ryan J.; Davey, Nicholas G.; Martinsen, Morten; Short, R. Timothy; Gill, Chris G.; Krogh, Erik T.

    2015-02-01

    Development of small, field-portable mass spectrometers has enabled a rapid growth of in-field measurements on mobile platforms. In such in-field measurements, unexpected signal variability has been observed by the authors in portable ion traps with internal electron ionization. The orientation of magnetic fields (such as the Earth's) relative to the ionization electron beam trajectory can significantly alter the electron flux into a quadrupole ion trap, resulting in significant changes in the instrumental sensitivity. Instrument simulations and experiments were performed relative to the earth's magnetic field to assess the importance of (1) nonpoint-source electron sources, (2) vertical versus horizontal electron beam orientation, and (3) secondary magnetic fields created by the instrument itself. Electron lens focus effects were explored by additional simulations, and were paralleled by experiments performed with a mass spectrometer mounted on a rotating platform. Additionally, magnetically permeable metals were used to shield (1) the entire instrument from the Earth's magnetic field, and (2) the electron beam from both the Earth's and instrument's magnetic fields. Both simulation and experimental results suggest the predominant influence on directionally dependent signal variability is the result of the summation of two magnetic vectors. As such, the most effective method for reducing this effect is the shielding of the electron beam from both magnetic vectors, thus improving electron beam alignment and removing any directional dependency. The improved ionizing electron beam alignment also allows for significant improvements in overall instrument sensitivity.

  18. Earth matter effects on supernova neutrinos in large-volume detectors

    NASA Astrophysics Data System (ADS)

    Borriello, Enrico

    2013-04-01

    Neutrino oscillations in the Earth matter may introduce peculiar modulations in the supernova (SN) neutrino spectra. The detection of this effect has been proposed as diagnostic tool for the neutrino mass hierarchy. We perform an updated study on the observability of this effect at large next-generation underground detectors (i.e., 0.4 Mton water Cherenkov, 50 kton scintillation and 100 kton liquid Argon detectors) based on neutrino fluxes from state-of-the-art SN simulations and accounting for statistical fluctuations via Montecarlo simulations. Since the average energies predicted by recent simulations are lower than previously expected and a tendency towards the equalization of the neutrino fluxes appears during the SN cooling phase, the detection of the Earth matter effect will be more challenging than expected from previous studies. We find that none of the proposed detectors shall be able to detect the Earth modulation for the neutrino signal of a typical galactic SN at 10 kpc. It should be observable in a 100 kton liquid Argon detector for a SN at few kpc and all three detectors would clearly see the Earth signature for very close-by stars only (d˜200 pc).

  19. Tide-influenced sedimentary environments and facies

    SciTech Connect

    De Boer, P.L.; Van Gelder, A.; Nio, S.D.

    1988-01-01

    This volume contains examples of recent as well as fossil tide-influenced sedimentary facies. Studies of recent tidal processes and sediments provide an insight into the way in which tidal facies and sequences develop, and into the processes which are active. The studies performed on fossil rocks give information on one-to-one scale model experiments that have been executed by nature both relatively recently and in the distant past. In this work, the parallel presentation of papers on recent and fossil examples of tide-influenced sedimentary facies and environments follows the philosophy of comparative sedimentology, aiming at an understanding of both the past and the present, with the aim also, of forecasting future developments.

  20. Population dynamics of red tide dinoflagellates

    NASA Astrophysics Data System (ADS)

    Wyatt, Timothy; Zingone, Adriana

    2014-03-01

    Sea-surface discolorations due to high concentrations of phytoplankton are called red tides. Their ecological significance is a long standing puzzle, and they are sometimes considered pathological. Here we propose that many red tides, particularly but not exclusively those composed of certain autotrophic dinoflagellates, are presexual/sexual swarms, essential links in their complex life cycles. This view provides a rationale for the appearance of these organisms in thin surface layers, and helps explain their ephemeral nature. We suggest that further understanding of this phenomenon, and of phytoplankton ecology in general, would benefit from attention to the 'net reproductive value‧ (r) over the whole life cycle as well as to the division rate (μ) of the vegetative phase. It is argued that r is strategically adapted to seasonal cycles and long term environmental variability, while μ reflects tactical needs (timing) and constraints (grazers, parasites) on vegetative growth.

  1. Radiational tides at the southeastern coast of the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Rabinovich, A. B.; Medvedev, I. P.

    2015-05-01

    The tides in the Baltic Sea are weak but unmistakably recognizable in sea-level spectra. Multiyear hourly tide gauge series enable us to examine specific tidal properties in detail and to identify some unexpected effects. Two nearby stations on the southeastern coast of the sea, namely Baltiysk, located in the strait connecting the Vistula Lagoon to the Baltic Sea, and Otkrytoe, on the coast of the Curonian Lagoon, are found to have very different character of tidal motions. Based on 13 years of simultaneous observations at these stations we constructed high-resolution spectra of sea level fluctuations that demonstrated that the tidal spectrum at Baltiysk is "classical" with sharp peaks corresponding to the major tidal constituents: M2, S2, N2, K1, O1, and P1. Unlike at Baltiysk, the main tidal peak at Otkrytoe is at the S1 frequency; the K1, P1, and S2 tidal harmonics also have significant peaks, while the other harmonics (including M2 and O1) are undistinguishable. Further analysis indicated that the tides at Baltiysk are generated by ordinary gravitational tidal forces, while at Otkrytoe they are induced by solar radiation, specifically by the breeze winds creating wind setups and setdowns in the Curonian Lagoon. Moreover, our findings demonstrate that the observed K1 and P1 peaks at Otkrytoe are related not to gravitational forces but to the seasonal modulation of the S1 radiational tidal constituent. The separate analysis of the "summer" and "winter" sea level spectra at Otkrytoe reveals prominent radiational tidal peaks (S1 and S2) in summer and the absence of these peaks in winter. The results of the analysis support the assumption that these motions are generated by the breeze winds associated with the sea/land temperature contrasts, which are substantial during the warm (ice-free) season but vague during the cold season when ice cover diminishes these contrasts.

  2. Effects of rare-earth co-doping on the local structure of rare-earth phosphate glasses using high and low energy X-ray diffraction.

    PubMed

    Cramer, Alisha J; Cole, Jacqueline M; FitzGerald, Vicky; Honkimaki, Veijo; Roberts, Mark A; Brennan, Tessa; Martin, Richard A; Saunders, George A; Newport, Robert J

    2013-06-14

    Rare-earth co-doping in inorganic materials has a long-held tradition of facilitating highly desirable optoelectronic properties for their application to the laser industry. This study concentrates specifically on rare-earth phosphate glasses, (R2O3)x(R'2O3)y(P2O5)(1-(x+y)), where (R, R') denotes (Ce, Er) or (La, Nd) co-doping and the total rare-earth composition corresponds to a range between metaphosphate, RP3O9, and ultraphosphate, RP5O14. Thereupon, the effects of rare-earth co-doping on the local structure are assessed at the atomic level. Pair-distribution function analysis of high-energy X-ray diffraction data (Q(max) = 28 Å(-1)) is employed to make this assessment. Results reveal a stark structural invariance to rare-earth co-doping which bears testament to the open-framework and rigid nature of these glasses. A range of desirable attributes of these glasses unfold from this finding; in particular, a structural simplicity that will enable facile molecular engineering of rare-earth phosphate glasses with 'dial-up' lasing properties. When considered together with other factors, this finding also demonstrates additional prospects for these co-doped rare-earth phosphate glasses in nuclear waste storage applications. This study also reveals, for the first time, the ability to distinguish between P-O and P[double bond, length as m-dash]O bonding in these rare-earth phosphate glasses from X-ray diffraction data in a fully quantitative manner. Complementary analysis of high-energy X-ray diffraction data on single rare-earth phosphate glasses of similar rare-earth composition to the co-doped materials is also presented in this context. In a technical sense, all high-energy X-ray diffraction data on these glasses are compared with analogous low-energy diffraction data; their salient differences reveal distinct advantages of high-energy X-ray diffraction data for the study of amorphous materials.

  3. Bodily Tides Near Spin-Orbit Resonances

    DTIC Science & Technology

    2012-01-01

    Celest Mech Dyn Astr (2012) 112:283–330 DOI 10.1007/s10569-011-9397-4 ORIGINAL ARTICLE Bodily tides near spin–orbit resonances Michael Efroimsky...tidal dissipation rate in the Moon, discovered by LLR. Electronic supplementary material The online version of this article (doi:10.1007/s10569-011...relevant (Bills et al. 2005). Another class of exceptions is constituted by close binary asteroids . The topic is addressed by Taylor and Margot (2010), who

  4. Deep sea tides determination from GEOS-3

    NASA Technical Reports Server (NTRS)

    Maul, G. A.; Yanaway, A.

    1978-01-01

    GEOS 3 altimeter data in a 5 degree X 5 degree square centered at 30 deg N, 70 deg W were analyzed to evaluate deep sea tide determination from a spacecraft. The signal to noise ratio of known tidal variability to altimeter measurement of sea level above the ellipsoid was 0.1. A sample was obtained in a 5 deg x 5 deg area approximately once every four days. The randomly spaced time series was analyzed using two independent least squares techniques.

  5. Methods for analysis of internal-tide propagation variability

    NASA Astrophysics Data System (ADS)

    Duda, T. F.; Lin, Y. T.

    2014-12-01

    The strong variability of internal tidal phase with respect to tidal phase has been recently documented. The slowness of internal tidal propagation through evolving uncertain environmental conditions offers a simple descriptive explanation for this effect. Here, a method for analyzing the propagation of internal tides through the random medium is presented. The equations of motion for internal waves are recast into vertical and horizontal equations. The vertical equation is a generalization of the internal-wave modal equation and the Taylor-Goldstein equation. This equation takes into account the effects of two-dimensionally sheared currents into the normal mode wavelength and speed. The horizontal equation is the Helmholtz equation with an azimuthally variable (anisotropic) phase speed. Ray tracing methods for this anisotropic speed scenario are presented. Tehniques for solving the equations and some example results are shown. The method differs from other internal tide propagation analysis methods that use the long wave approximation normal modes and include current effects in the horizontal equations. The figure shows, at the right, phase speed as a function of azimuth for three M2-frequency internal-wave modes for the shear flow and stratification conditions shown at the left.

  6. Solar activity and atmospheric tide effect on the polar conductivity and the vertical electric field in the stratosphere at low latitude

    NASA Astrophysics Data System (ADS)

    Gupta, S. P.

    2004-01-01

    Balloonborne measurements of the polar conductivity and the vertical electric field were carried out over a period of 1984-1994 from Hyderabad, Central India. The conductivity values show positive correlation with solar activity between 20 and 35 km. Between 5 and 20 km the conductivity values show an anti-correlation with solar activity. The vertical electric field does not show solar cycle effect. However, the electric field and the conductivity show a semi-diurnal variation at balloon float altitude.

  7. Internal tide in the Kara Gates Strait

    NASA Astrophysics Data System (ADS)

    Morozov, E. G.; Kozlov, I. E.; Shchuka, S. A.; Frey, D. I.

    2017-01-01

    We observed strong internal tidal waves in the Kara Gates Strait. Internal tides are superimposed over a system of mean currents from the Barents to the Kara Sea. Field studies of internal tides in the Kara Gates were performed in 1997, 2007, and 2015. In 2015, we analyzed data from towed CTD measurements, numerical model calculations, and satellite images in the region. An internal tidal wave with a period of 12.4 h is generated due to the interaction between the currents of the barotropic tide and the bottom relief on the slopes of a ridge that crosses the strait from Novaya Zemlya to the continent. The depths of the ridge crest are 30-40 m. A constant current of relatively warm water flows from the Barents to the Kara Sea. An internal wave propagates in both directions from the ridge. In the Barents Sea, internal waves are intensified by the current from the Barents to the Kara Sea. Internal bores followed by a packet of short-period internal waves are found in both directions from the strait. Satellite images show that short-period internal waves are generated after the internal bore. A hydraulic jump was found on the eastern side of the strait. Numerical modeling agrees with the experimental results.

  8. Cheap electricity from French tides

    NASA Astrophysics Data System (ADS)

    Andre, H.

    1980-02-01

    A tidal power plant built in Saint-Malo, France is examined, and some of the problems that have resulted in recent years are analyzed. These include mechanical problems due to turbine runner-blade seal failure and electrical problems involving electroerosion and structural station difficulties. the effects of tidal power plants on the environment are discussed, and it is noted that all possible side effects of the operations are very limited. Attention is given to the basic requirements for constructing power sites.

  9. The association of coronal mass ejections with their effects near the Earth

    NASA Astrophysics Data System (ADS)

    Schwenn, R.; dal Lago, A.; Huttunen, E.; Gonzalez, W. D.

    2005-03-01

    To this day, the prediction of space weather effects near the Earth suffers from a fundamental problem: The radial propagation speed of "halo" CMEs (i.e. CMEs pointed along the Sun-Earth-line that are known to be the main drivers of space weather disturbances) towards the Earth cannot be measured directly because of the unfavorable geometry. From inspecting many limb CMEs observed by the LASCO coronagraphs on SOHO we found that there is usually a good correlation between the radial speed and the lateral expansion speed Vexp of CME clouds. This latter quantity can also be determined for earthward-pointed halo CMEs. Thus, Vexp may serve as a proxy for the otherwise inaccessible radial speed of halo CMEs. We studied this connection using data from both ends: solar data and interplanetary data obtained near the Earth, for a period from January 1997 to 15 April 2001. The data were primarily provided by the LASCO coronagraphs, plus additional information from the EIT instrument on SOHO. Solar wind data from the plasma instruments on the SOHO, ACE and Wind spacecraft were used to identify the arrivals of ICME signatures. Here, we use "ICME" as a generic term for all CME effects in interplanetary space, thus comprising not only ejecta themselves but also shocks as well. Among 181 front side or limb full or partial halo CMEs recorded by LASCO, on the one hand, and 187 ICME events registered near the Earth, on the other hand, we found 91 cases where CMEs were uniquely associated with ICME signatures in front of the Earth. Eighty ICMEs were associated with a shock, and for 75 of them both the halo expansion speed Vexp and the travel time Ttr of the shock could be determined. The function Ttr=203-20.77*ln (Vexp fits the data best. This empirical formula can be used for predicting further ICME arrivals, with a 95% error margin of about one day. Note, though, that in 15% of comparable cases, a full or partial halo CME does not cause any ICME signature at Earth at all; every

  10. New Models of Water Delivery To Earth: The Effects of Ice Longevity and Collisional Water Transport

    NASA Astrophysics Data System (ADS)

    Maindl, Thomas I.; Haghighipour, Nader

    2016-10-01

    It is widely accepted that the vast majority of Earth's water was delivered to its accretion zone by water-carrying planetesimals and planetary embryos from the outer regions of the asteroid belt while Earth was still forming. Modern simulations of the formation of terrestrial planets show this process with high resolution. However, their treatment of the actual delivery of water is still rudimentary assuming that a water-carrying object will maintain all its water content during its journey from its original orbit to the accretion zone of Earth. Models of the ice longevity have, however, shown that the water-ice may not stay intact, and asteroids and planetary embryos may lose some of their original water in form of ice sublimation during the dynamical evolution of these bodies. Also, collisions among these bodies while on their journey to Earth's accretion zone will result in the loss of large amounts of their water. These effects could be especially important during the formation of terrestrial planets as this process takes tens to hundreds of millions of years. We have developed a more accurate model in which the sublimation of ice during the process of the scattering of icy asteroids and planetary embryos into the accretion zone of Earth is taken into account. Our model includes two different modes of handling ice sublimation, one for sub-surface water and one for deeper ice. We also estimate water loss and retention during collisions which depends on the physical and dynamical parameters of the impacts. The results of our simulations put stringent constraints on the initial water distribution in the protoplanetary disk, the location of snowline, and the contribution of water from the primordial nebula to the final water budget of Earth. In this poster, we will present the results of our new simulations and discuss their implications for models of solar system formation and dynamics.

  11. Effect of Oxygen Enrichment in Propane Laminar Diffusion Flames under Microgravity and Earth Gravity Conditions

    NASA Astrophysics Data System (ADS)

    Bhatia, Pramod; Singh, Ravinder

    2017-01-01

    Diffusion flames are the most common type of flame which we see in our daily life such as candle flame and match-stick flame. Also, they are the most used flames in practical combustion system such as industrial burner (coal fired, gas fired or oil fired), diesel engines, gas turbines, and solid fuel rockets. In the present study, steady-state global chemistry calculations for 24 different flames were performed using an axisymmetric computational fluid dynamics code (UNICORN). Computation involved simulations of inverse and normal diffusion flames of propane in earth and microgravity condition with varying oxidizer compositions (21, 30, 50, 100 % O2, by mole, in N2). 2 cases were compared with the experimental result for validating the computational model. These flames were stabilized on a 5.5 mm diameter burner with 10 mm of burner length. The effect of oxygen enrichment and variation in gravity (earth gravity and microgravity) on shape and size of diffusion flames, flame temperature, flame velocity have been studied from the computational result obtained. Oxygen enrichment resulted in significant increase in flame temperature for both types of diffusion flames. Also, oxygen enrichment and gravity variation have significant effect on the flame configuration of normal diffusion flames in comparison with inverse diffusion flames. Microgravity normal diffusion flames are spherical in shape and much wider in comparison to earth gravity normal diffusion flames. In inverse diffusion flames, microgravity flames were wider than earth gravity flames. However, microgravity inverse flames were not spherical in shape.

  12. Cretaceous tide-dominated carbonate ramp: Comparison of reservoir hetergeneity in tide-versus wave-dominated carbonate ramp systems

    SciTech Connect

    Kerans, C.

    1995-08-01

    Cretaceous (upper Albian) carbonate ramp strata, Pecos River Canyon, Texas, provide a uniquely continuous exposure of a tide-dominated ramp reservoir analog. The continuous 100-km shelf-to-basin outcrop begins in inner ramp mud-rich facies that record both high-frequency (20-100 ky) and intermediate frequency (>200 ky) cyclicity. The ramp-crest is up to 40 km across depositional dip. Intermediate-scale cycles in the ramp crest include basal oyster and toucasid wackestones, chondrodontid-rudist packstones, rudist-skeletal grainstones, and caprinid biostromes. Ramp-crest grainstones are 4-23 m in thickness and extend more than 20 km in a shelf to basin direction. Rudist biostromes are 3-7 m in thickness and are up to several kilometers in dip continuity except in deeper outer ramp settings where 100-200 m wide mounds are more common. The ramp crest is dominated by grain-rich facies with moderate to high permeability. Toucasid wackestones and oyster marls are 1-5 m in thickness and extend tens of kilometers in a dip direction, representing potential fluid flow barriers. Wave-dominated ramp systems of the Permian of West Texas provide a contrast to the Cretaceous tide-dominated setting. Low-permeability high-frequency cycle base mudstones and high-permeability cycle-top grainstones are preserved in both inner ramp and ramp crest settings. Fluid-flow modeling of these Permian wave-dominated reservoir strata illustrates that the intercalation of thin high- and low-permeability layers result in crossflow trapping and thief zones controlling the position and amount of remaining oil saturation. The depositional homogeneity of the Cretaceous tide-dominated ramp indicates that diagenetic heterogeneities and gravitational effects are potentially dominant controls on reservoir performance for these strata.

  13. [Effects of marine bacteria on the growth and toxin production of red-tide algae under different pH and salinities].

    PubMed

    Su, Jianqiang; Zheng, Tianling; Hu, Zhong; Xu, Jingsen; Yu, Zhiming; Song, Xiuxian

    2003-07-01

    The effects of strain S10 isolated from sediments of Xiamen Western Sea Area on the growth and paralytic shellfish poison (PSP) production of Alexandrium tamarense at different pH and salinities were studied. The results showed that the alga grew well at pH 6-8 and at salinity of 20-34. The toxicity of A. tamarense varied markedly at different pH and salinities: it decreased with increasing pH, while increased with salinity and reached its peak value at the salinity of 30, and then declined. The strain S10 inhibited the growth and the PSP production of A. tamarense at different pH and salinities. It had the best inhibitory function on the growth of A. tamarense at pH 7 and salinity of 34. The best inhibitory function on the PSP production of A. tamarense was at pH 7, but this inhibitory function was not related to salinity.

  14. Radial deformation of the earth by oceanic tidal loading

    NASA Technical Reports Server (NTRS)

    Ray, R. D.; Sanchez, B. V.

    1989-01-01

    A high-degree spherical harmonic series is used to compute the radial deformation of the Earth by oceanic tidal loading. By exploiting fast numerical transforms, this approach is found to be much more efficient, but no less accurate, than the traditional Green's function approach. The method is used to derive an atlas of load tide maps for 10 constitutents of the NSWC ocean tide model.

  15. [Effects of arbuscular mycorrhizal fungi on the growth and rare earth elements uptake of soybean grown in rare earth mine tailings].

    PubMed

    Guo, Wei; Zhao, Ren-xin; Zhao, Wen-jing; Fu, Rui-ying; Guo, Jiang-yuan; Zhang, Jun

    2013-05-01

    A greenhouse pot experiment was conducted to investigate the influence of arbuscular mycorrhizal (AM) fungi Glomus versiforme on the plant growth, nutrient uptake, C: N: P stoichiometric, uptake of heavy metals and rare earth elements by soybean (Glycine max) grown in rare earth mine tailings. The aim was to provide a basis for the revegetation of rare earth mine tailings. The results indicated that soybean had a high mycorrhizal colonization and symbiotic associations were successfully established with G. versiforme, with an average rate of approximately 67%. The colonization of G. versiforme significantly promoted the growth of soybean, increased P, K contents, and decreased C: N: P ratios, supporting the growth rate hypothesis. Inoculation with G. versiforme significantly decreased shoots and roots La, Ce, Pr and Nd concentrations of soybean compared to the control treatment. However, inoculation with G. versiforme had no significant effect on the heavy metal concentrations, except for significantly decreased shoot Fe and Cr concentrations and increased root Cd concentrations. The experiment demonstrates that AM fungi have a potential role for soybean to adapt the composite adversity of rare earth tailings and play a positive role in revegetation of rare earth mine tailings. Further studies on the role of AM fungi under natural conditions should be conducted.

  16. Monitoring red tide with satellite imagery and numerical models: a case study in the Arabian Gulf.

    PubMed

    Zhao, Jun; Ghedira, Hosni

    2014-02-15

    A red tide event that occurred in August 2008 in the Arabian Gulf was monitored and assessed using satellite observations and numerical models. Satellite observations revealed the bloom extent and evolution from August 2008 to August 2009. Flow patterns of the bloom patch were confirmed by results from a HYCOM model. HYCOM data and satellite-derived sea surface temperature data further suggested that the bloom could have been initiated offshore and advected onshore by bottom Ekman layer. Analysis indicated that nutrient sources supporting the bloom included upwelling, Trichodesmium, and dust deposition while other potential sources of nutrient supply should also be considered. In order to monitor and detect red tide effectively and provide insights into its initiation and maintenance mechanisms, the integration of multiple platforms is required. The case study presented here demonstrated the benefit of combing satellite observations and numerical models for studying red tide outbreaks and dynamics.

  17. Gravity and Tide Parameters Determined from Satellite and Spacecraft Orbits

    NASA Astrophysics Data System (ADS)

    Jacobson, Robert A.

    2015-05-01

    As part of our work on the development of the Jovian and Saturnian satellite ephemerides to support the Juno and Cassini missions, we determined a number of planetary system gravity parameters. This work did not take into account tidal forces. In fact, we saw no obvious observational evidence of tidal effects on the satellite or spacecraft orbits. However, Lainey et al. (2009 Nature 459, 957) and Lainey et. al (2012 Astrophys. J. 752, 14) have published investigations of tidal effects in the Jovian and Saturnian systems, respectively. Consequently, we have begun a re-examination of our ephemeris work that includes a model for tides raised on the planet by the satellites as well as tides raised on the satellites by the planet. In this paper we briefly review the observations used in our ephemeris production; they include astrometry from the late 1800s to 2014, mutual events, eclipses, occultatons, and data acquired by the Pioneer, Voyager, Ulysses, Cassini, Galileo, and New Horizons spacecraft. We summarize the gravity parameter values found from our original analyses. Next we discuss our tidal acceleration model and its impact on the gravity parameter determination. We conclude with preliminary results found when the reprocessing of the observations includes tidal forces acting on the satellites and spacecraft.

  18. Human Impacts on Tides Overwhelm the Effect of Sea Level Risee on Extreme Water Levels in the Rhine-Meuse Delta

    NASA Astrophysics Data System (ADS)

    Hoitink, T.; Vellinga, N.; Hoekstra, P.; Van Der Vegt, M.; Zhang, W.

    2014-12-01

    Mean sea level rise receives ample attention in the literature. However, peak water levels, which are most important for flood vulnerability and salinity intrusion in tidal river networks, may not be linearly related with mean surface levels. To quantify tidal and subtidal water level changes and to link these changes to human intervention, 70 years of water level data for the Rhine-Meuse tidal river network is analysed using a variety of statistical methods. Using a novel parameterization of probability density functions, mean high and low water levels are examined, and extreme water levels are investigated by applying the combined Mann-Kendall and Pettitt tests to find trends and trend changes. Tidal water levels are studied based on harmonic analysis. Results show that the mean water levels throughout the system rise with the same pace as the mean sea level. However, high and low water levels do not show the same increase, and the spatial variability in decadal trends in high- and low water levels is high. High water and low water extremes generally decrease. Both the extreme water level analysis and the harmonic analysis display significant trend breaks in 1970, 1981 and 1997. These breaks can be attributed to the closure of the Haringvliet estuary, the removal of sluices and the removal of a dam, respectively, which radically alter the tidal motion. These results demonstrate that the direct human influence on the tidal motion can overwhelm the effect of mean sea level rise on water level extremes.

  19. Low Earth orbit environmental effects on the space station photovoltaic power generation systems

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.

    1987-01-01

    A summary of the Low Earth Orbital Environment, its impact on the Photovoltaic Power systems of the space station and the solutions implemented to resolve the environmental concerns or issues are described. Low Earth Orbital Environment (LEO) presents several concerns to the Photovoltaic power systems of the space station. These concerns include atomic oxygen interaction with the polymeric substrate of the solar arrays, ionized environment effects on the array operating voltage, the effects of the meteoroids and debris impacts and penetration through the different layers of the solar cells and their circuits, and the high energy particle and radiation effects on the overall solar array performance. Potential solutions to some of the degrading environmental interactions that will provide the photovoltaic power system of the space station with the desired life are also summarized.

  20. Low earth orbit environmental effects on the Space Station photovoltaic power generation systems

    NASA Technical Reports Server (NTRS)

    Nahra, H. K.

    1988-01-01

    A summary of the low earth orbital environment, its impact on the photovoltaic power systems of the Space Station and the solutions implemented to resolve the environmental concerns or issues are described. Low earth orbital environment (LEO) presents several concerns to the photovoltaic power systems of the Space Station. These concerns include atomic oxygen interaction with the polymeric substrate of the solar arrays, ionized environment effects on the array operating voltage, the effects of the meteoroids and debris impacts and penetration through the different layers of the solar cells and their circuits, and the high energy particle and radiation effects on the overall solar array performance. Potential solutions to some of the degrading environmental interactions that will provide the photovoltaic power system of the Space Station with the desired life are also summarized.

  1. Precambrian climate: The effects of land area and earth's rotation rate

    SciTech Connect

    Jenkins, G.S. ); Marshall, H.G.; Kuhn, W.R. )

    1993-05-20

    The authors present results of model studies using general circulation models of climatic effects of variations in the rotation rate of the earth. These studies are of relevance for the Precambrian times, when the rotation period of the earth was considerably shorter. The authors include in their model studies a number of factors which were left out in previous studies. The rotation rate has a strong effect on atmospheric circulation, as evidenced in the theory of geostrophic turbulence, mid-latitude baroclinic instability, and the Hadley cell. One can expect the contraction of circulation patterns, both horizontally and vertically. This should also impact heat transport, though questions of mean temperature effects are more open, unless one allows cloud cover to vary. The authors put more realistic starting conditions into the model, and also allow clouds and hydrology to have a feedback role to see what impact rotation rates will have on global climate.

  2. Effect of rare earth metal on the spin-orbit torque in magnetic heterostructures

    NASA Astrophysics Data System (ADS)

    Ueda, Kohei; Pai, Chi-Feng; Tan, Aik Jun; Mann, Maxwell; Beach, Geoffrey S. D.

    2016-06-01

    We report the effect of the rare earth metal Gd on current-induced spin-orbit torques (SOTs) in perpendicularly magnetized Pt/Co/Gd heterostructures, characterized using harmonic measurements and spin-torque ferromagnetic resonance (ST-FMR). By varying the Gd metal layer thickness from 0 nm to 8 nm, harmonic measurements reveal a significant enhancement of the effective fields generated from the Slonczewski-like and field-like torques. ST-FMR measurements confirm an enhanced effective spin Hall angle and show a corresponding increase in the magnetic damping constant with increasing Gd thickness. These results suggest that Gd plays an active role in generating SOTs in these heterostructures. Our finding may lead to spin-orbitronics device application such as non-volatile magnetic random access memory, based on rare earth metals.

  3. What Is the Atmosphere’s Effect on Earth's Surface Temperature?

    NASA Astrophysics Data System (ADS)

    Zeng, Xubin

    2010-04-01

    It is frequently stated in textbooks and scholarly articles that the surface temperature of Earth is 33°C warmer than it would be without the atmosphere and that this difference is due to the greenhouse effect. This Forum shows that the atmosphere effect leads to warming of only 20°C. This new conclusion requires a revision to all of the relevant literature in K-12, undergraduate, and graduate education material and to science papers and reports. The greenhouse effect on Earth's surface temperature is well understood qualitatively and is regarded as basic knowledge about Earth's climate and climate change. The 33°C warming has been used to quantify the greenhouse effect of greenhouse gases, or of greenhouse gases and clouds, in K-12 educational material (e.g., http://epa.gov/climatechange/kids/greenhouse.html), undergraduate freshman introductory textbooks on weather and climate [e.g., Ahrens, 2008], and graduate textbooks on climate [e.g., Peixoto and Oort, 1992]. Some textbooks and various other publications have less stringently attributed the warming to the greenhouse effect [e.g., Wallace and Hobbs, 2006; Le Treut et al., 2007; American Meteorological Society, 2000].

  4. A social marketing approach to implementing evidence-based practice in VHA QUERI: the TIDES depression collaborative care model

    PubMed Central

    2009-01-01

    Abstract Collaborative care models for depression in primary care are effective and cost-effective, but difficult to spread to new sites. Translating Initiatives for Depression into Effective Solutions (TIDES) is an initiative to promote evidence-based collaborative care in the U.S. Veterans Health Administration (VHA). Social marketing applies marketing techniques to promote positive behavior change. Described in this paper, TIDES used a social marketing approach to foster national spread of collaborative care models. TIDES social marketing approach The approach relied on a sequential model of behavior change and explicit attention to audience segmentation. Segments included VHA national leadership, Veterans Integrated Service Network (VISN) regional leadership, facility managers, frontline providers, and veterans. TIDES communications, materials and messages targeted each segment, guided by an overall marketing plan. Results Depression collaborative care based on the TIDES model was adopted by VHA as part of the new Primary Care Mental Health Initiative and associated policies. It is currently in use in more than 50 primary care practices across the United States, and continues to spread, suggesting success for its social marketing-based dissemination strategy. Discussion and conclusion Development, execution and evaluation of the TIDES marketing effort shows that social marketing is a promising approach for promoting implementation of evidence-based interventions in integrated healthcare systems. PMID:19785754

  5. The effects of refraction on transit transmission spectroscopy: application to Earth-like exoplanets

    SciTech Connect

    Misra, Amit; Meadows, Victoria; Crisp, Dave

    2014-09-01

    We quantify the effects of refraction in transit transmission spectroscopy on spectral absorption features and on temporal variations that could be used to obtain altitude-dependent spectra for planets orbiting stars of different stellar types. We validate our model against altitude-dependent transmission spectra of the Earth from ATMOS and against lunar eclipse spectra from Pallé et al. We perform detectability studies to show the potential effects of refraction on hypothetical observations of Earth analogs with the James Webb Space Telescope NIRSPEC. Due to refraction, there will be a maximum tangent pressure level that can be probed during transit for each given planet-star system. We show that because of refraction, for an Earth-analog planet orbiting in the habitable zone of a Sun-like star only the top 0.3 bars of the atmosphere can be probed, leading to a decrease in the signal-to-noise ratio (S/N) of absorption features by 60%, while for an Earth-analog planet orbiting in the habitable zone of an M5V star it is possible to probe almost the entire atmosphere with minimal decreases in S/N. We also show that refraction can result in temporal variations in the transit transmission spectrum which may provide a way to obtain altitude-dependent spectra of exoplanet atmospheres. Additionally, the variations prior to ingress and subsequent to egress provide a way to probe pressures greater than the maximum tangent pressure that can be probed during transit. Therefore, probing the maximum range of atmospheric altitudes, and in particular the near-surface environment of an Earth-analog exoplanet, will require looking at out-of-transit refracted light in addition to the in-transit spectrum.

  6. Spectral Characteristic of Tholin Produced from Possible Early Earth Atmospheres and its Role in Antigreenhouse Effect on Early Earth

    NASA Technical Reports Server (NTRS)

    Khare, B. N.; Imanaka, H.; Wilhite, P.; McKay, C.; Bakes, E.; Cruikshank, D. P.; Arakawa, E. T.

    2003-01-01

    We have produced organic material simulating a methane photochemical haze in a CO2- rich atmosphere of the early Earth by irradiating gas mixtures in an inductively coupled cold plasma chamber with pressure approx. 0.25 mbar at 100 W total power. The flow rate was 24 cm3 min. We added progressively higher levels of CH, by combining gas mixtures of N2/CH4 (9/1) and N2/CO2 (9/1) to change the ratio of CH4/CO2. Tholin was accumulated for 5 hours in each experiment; the onset of tholin formation is in the range CH4/CO2 = 0.5 to 1. As the mixing ratio of CH, is increased, the production rate of the brownish tholin film increases. IR spectra showed the C-H and N-H bands similar to that of Titan tholin and closely resemble Titan tholin made at 0.13 mbar pressure. A decrease in the CH bonds on decreasing CH4/CO2 is noted. Ether bands (-(2-O-C) were tentatively detected, but no detectable carbonyl (C=O) band was found. The absorption in the UV region for the early Earth tholin is found to be substantially greater than the Titan tholin. Quantitative values of the optical constants of early Earth tholin are currently being measured.

  7. Effect of Earth and Mars departure delays on human missions to Mars

    NASA Astrophysics Data System (ADS)

    Desai, Prasun N.; Tartabini, Paul V.

    1993-08-01

    This study determines the impact on the initial mass in low-Earth orbit (IMLEO) for delaying departure from Mars and Earth by 5, 15, and 30 days, once a nominal mission to Mars has been selected. Additionally, the use of a deep space maneuver (DSM) is attempted to alleviate the IMLEO penalties. Three different classes of missions are analyzed using chemical and nuclear thermal propulsion systems in the 2000-2025 time-frame: opposition, conjunction, and fast-transfer conjunction. The results indicate that Mars and Earth delays can lead to large IMLEO penalties. Opposition and fast-transfer conjunction class missions have the highest IMLEO penalties, upwards of 432.4 mt and 1977.3 mt, respectively. Conjunction class missions, on the other hand, tend to be insensitive to Mars and Earth delays having IMLEO penalties under 103.5 mt. As expected, nuclear thermal propulsion had significantly lower IMLEO penalties as compared to chemical propulsion. The use of a DSM is found not to have a significant impact on reducing the IMLEO penalties. Through this investigation, the effect of off-nominal departure conditions on the overall mission (i.e., IMLEO) can be gained, enabling mission designers to incorporate the influence of off-nominal departure conditions of the interplanetary trajectory in the overall conceptual design process of a Mars transfer vehicle.

  8. Effects of the same CIR on the plasma environment of Venus, Earth and Mars

    NASA Astrophysics Data System (ADS)

    Opitz, A.; Witasse, O.; Svedhem, H.; Sauvaud, J.-A.; Fedorov, A.

    2013-09-01

    During the recent solar activity minimum the solar wind streams were very persistent, even after a few solar rotations the global solar wind properties were unchanged. The compression regions due to the fast stream - slow stream interaction were sweeping through the ecliptic plane without large longitudinal alterations, these are named corotating interaction regions (CIR). Their persistence allows the comparison of the effects of the same CIR on the different terrestrial planets. We investigated the time period in January and February 2007, when the twin solar spacecraft STEREO were still nearby Earth observing simultaneously the solar wind and the terrestrial magnetotail. When considering the solar rotation and the corotating solar wind structures, Venus was ~10 days ahead Earth, while Mars ~10 days behind. For this reason, the Venus Express in-situ plasma and magnetic field measurements were shifted by such a timelag to Earth orbit, and respectively the Mars Express observations in order to find the corresponding CIRs. Since the investigated three planets have different magnetic characteristics, their response to the CIR passage is expected to be different. We find energetic particle bursts escaping from the magnetized Earth and the unmagnetized planets Venus and Mars have increased ion escape rates.

  9. Effect of Earth and Mars departure delays on human missions to Mars

    NASA Technical Reports Server (NTRS)

    Desai, Prasun N.; Tartabini, Paul V.

    1993-01-01

    This study determines the impact on the initial mass in low-Earth orbit (IMLEO) for delaying departure from Mars and Earth by 5, 15, and 30 days, once a nominal mission to Mars has been selected. Additionally, the use of a deep space maneuver (DSM) is attempted to alleviate the IMLEO penalties. Three different classes of missions are analyzed using chemical and nuclear thermal propulsion systems in the 2000-2025 time-frame: opposition, conjunction, and fast-transfer conjunction. The results indicate that Mars and Earth delays can lead to large IMLEO penalties. Opposition and fast-transfer conjunction class missions have the highest IMLEO penalties, upwards of 432.4 mt and 1977.3 mt, respectively. Conjunction class missions, on the other hand, tend to be insensitive to Mars and Earth delays having IMLEO penalties under 103.5 mt. As expected, nuclear thermal propulsion had significantly lower IMLEO penalties as compared to chemical propulsion. The use of a DSM is found not to have a significant impact on reducing the IMLEO penalties. Through this investigation, the effect of off-nominal departure conditions on the overall mission (i.e., IMLEO) can be gained, enabling mission designers to incorporate the influence of off-nominal departure conditions of the interplanetary trajectory in the overall conceptual design process of a Mars transfer vehicle.

  10. Earth remote sensing as an effective tool for the development of advanced innovative educational technologies

    NASA Astrophysics Data System (ADS)

    Mayorova, Vera; Mayorov, Kirill

    2009-11-01

    Current educational system is facing a contradiction between the fundamentality of engineering education and the necessity of applied learning extension, which requires new methods of training to combine both academic and practical knowledge in balance. As a result there are a number of innovations being developed and implemented into the process of education aimed at optimizing the quality of the entire educational system. Among a wide range of innovative educational technologies there is an especially important subset of educational technologies which involve learning through hands-on scientific and technical projects. The purpose of this paper is to describe the implementation of educational technologies based on small satellites development as well as the usage of Earth remote sensing data acquired from these satellites. The increase in public attention to the education through Earth remote sensing is based on the concern that although there is a great progress in the development of new methods of Earth imagery and remote sensing data acquisition there is still a big question remaining open on practical applications of this kind of data. It is important to develop the new way of thinking for the new generation of people so they understand that they are the masters of their own planet and they are responsible for its state. They should desire and should be able to use a powerful set of tools based on modern and perspective Earth remote sensing. For example NASA sponsors "Classroom of the Future" project. The Universities Space Research Association in United States provides a mechanism through which US universities can cooperate effectively with one another, with the government, and with other organizations to further space science and technology, and to promote education in these areas. It also aims at understanding the Earth as a system and promoting the role of humankind in the destiny of their own planet. The Association has founded a Journal of Earth System

  11. Possible Effect of the Earth's Inertial Induction on the Orbital Decay of LAGEOS

    NASA Astrophysics Data System (ADS)

    Dey, Ujjal; Kar, Samanwita; Ghosh, Amitabha

    2016-09-01

    The theory of velocity dependent inertial induction, based upon extended Mach's principle, has been able to generate many interesting results related to celestial mechanics and cosmological problems. Because of the extremely minute magnitude of the effect its presence can be detected through the motion of accurately observed bodies like Earth satellites. LAGEOS I and II are medium altitude satellites with nearly circular orbits. The motions of these satellites are accurately recorded and the past data of a few decades help to test many theories including the general theory of relativity. Therefore, it is hoped that the effect of the Earth's inertial induction can have any detectable effect on the motion of these satellites. It is established that the semi-major axis of LAGEOS I is decreasing at the rate of 1.3 mm/d. As the atmospheric drag is negligible at that altitude, a proper explanation of the secular change has been wanting, and, therefore, this paper examines the effect of the Earth's inertial induction effect on LAGEOS I. Past researches have established that Yarkovsky thermal drag, charged and neutral particle drag might be the possible mechanisms for this orbital decay. Inertial induction is found to generate a perturbing force that results in 0.33 mm/d decay of the semi major axis. Some other changes are also predicted and the phenomenon also helps to explain the observed changes in the orbits of a few other satellites. The results indicate the feasibility of the theory of inertial induction i.e. the dynamic gravitation phenomenon of the Earth on its satellites as a possible partial cause for orbital decay.

  12. Effects of inherent alkali and alkaline earth metallic species on biomass pyrolysis at different temperatures.

    PubMed

    Hu, Song; Jiang, Long; Wang, Yi; Su, Sheng; Sun, Lushi; Xu, Boyang; He, Limo; Xiang, Jun

    2015-09-01

    This work aimed to investigate effects of inherent alkali and alkaline earth metallic species (AAEMs) on biomass pyrolysis at different temperatures. The yield of CO, H2 and C2H4 was increased and that of CO2 was suppressed with increasing temperature. Increasing temperature could also promote depolymerization and aromatization reactions of active tars, forming heavier polycyclic aromatic hydrocarbons, leading to decrease of tar yields and species diversity. Diverse performance of inherent AAEMs at different temperatures significantly affected the distribution of pyrolysis products. The presence of inherent AAEMs promoted water-gas shift reaction, and enhanced the yield of H2 and CO2. Additionally, inherent AAEMs not only promoted breakage and decarboxylation/decarbonylation reaction of thermally labile hetero atoms of the tar but also enhanced thermal decomposing of heavier aromatics. Inherent AAEMs could also significantly enhance the decomposition of levoglucosan, and alkaline earth metals showed greater effect than alkali metals.

  13. Thermal evolution of the earth - Effects of volatile exchange between atmosphere and interior

    NASA Technical Reports Server (NTRS)

    Mcgovern, Patrick J.; Schubert, Gerald

    1989-01-01

    The thermal history of the earth is investigated using a parameterized model of mantle convection, that includes the effects of volatile exchange between the mantle and the surface reservoir and the softening of the mantle by the dissolved volatiles. The mantle degassing rate is taken to be directly proportional to the rate of seafloor spreading which depends on the mantle heat flow. It is shown that the dependence of the mantle viscosity on the volatile content has important effects on the thermal evolution of planetary interiors and the evolution of planetary atmospheres. Degassing is compensated by an increase in temperature, while regassing is compensated by a decrease in temperature. Reasonable degassing scenarios can account for an early rapid formation of the earth's atmosphere inferred from noble gas abundances.

  14. Dynamic effect of metro-induced vibration on the rammed earth base of the Bell Tower.

    PubMed

    Lai, Jinxing; Niu, Fangyuan; Wang, Ke; Chen, Jianxun; Qiu, Junling; Fan, Haobo; Hu, Zhinan

    2016-01-01

    Xi'an Bell Tower (the Bell Tower) is a state-level ancient relic in China. The vibration caused by metro will exert adverse effect on the Bell Tower. This paper aims at presenting 3D-FEM models to predict the peak period velocity (PPV) of rammed earth base when the metro passing through the Bell Tower. The calculation results are compared with those of field test. Both results were found to be in good agreement. Furthermore, the results indicated that the effect of shock absorption measures is significant. The shock absorption tracks can obviously decrease the vibration of the Bell Tower, and the maximum decrease of PPV of the rammed earth base is 78.91 %. The proposed prediction has the potential to be developed as a decision and management tool for the evaluation of the risk associated with the influence of vibration caused by metro on buildings in urban areas.

  15. Effect of Rheology on Mantle Dynamics and Plate Tectonics in Super-Earths

    NASA Astrophysics Data System (ADS)

    Tackley, P. J.; Ammann, M. W.; Brodholt, J. P.; Dobson, D. P.; Valencia, D. C.

    2011-12-01

    The discovery of extra-solar "super-Earth" planets with sizes up to twice that of Earth has prompted interest in their possible lithosphere and mantle dynamics and evolution. Simple scalings [1,2] suggest that super-Earths are more likely than an equivalent Earth-sized planet to be undergoing plate tectonics. Generally, viscosity and thermal conductivity increase with pressure while thermal expansivity decreases, resulting in lower convective vigor in the deep mantle, which, if extralopated to the largest super-Earths might, according to conventional thinking, result a very low effective Rayleigh number in their deep mantles and possibly no convection there. Here we evaluate this. (i) As the mantle of a super-Earth is made mostly of post-perovskite we here extend the density functional theory (DFT) calculations of post-perovskite activation enthalpy of [3] to a pressure of 1 TPa. The activation volume for diffusion creep becomes very low at very high pressure, but nevertheless for the largest super-Earths the viscosity along an adiabat may approach 10^30 Pa s in the deep mantle, which would be too high for convection. (ii) We use these DFT-calculated values in numerical simulations of mantle convection and lithosphere dynamics of planets with up to ten Earth masses. The models assume a compressible mantle including depth-dependence of material properties and plastic yielding induced plate-like lithospheric behavior, solved using StagYY [4]. Results confirm the likelihood of plate tectonics and show a novel self-regulation of deep mantle temperature. The deep mantle is not adiabatic; instead internal heating raises the temperature until the viscosity is low enough to facilitate convective loss of the radiogenic heat, which results in a super-adiabatic temperature profile and a viscosity increase with depth of no more than ~3 orders of magnitude, regardless of what is calculated for an adiabat. It has recently been argued [5] that at very high pressures, deformation

  16. Secular trends and evaluation of complex interventions: the rising tide phenomenon.

    PubMed

    Chen, Yen-Fu; Hemming, Karla; Stevens, Andrew J; Lilford, Richard J

    2016-05-01

    Evaluations of service delivery interventions with contemporaneous controls often yield null results, even when the intervention appeared promising in advance. There can be many reasons for null results. In this paper we introduce the concept of a 'rising tide' phenomenon being a possible explanation of null results. We note that evaluations of service delivery interventions often occur when awareness of the problems they intend to address is already heightened, and pressure to tackle them is mounting throughout a health system. An evaluation may therefore take place in a setting where the system as a whole is improving - where there is a pronounced temporal trend or a 'rising tide causing all vessels to rise'. As a consequence, control sites in an intervention study will improve. This reduces the difference between intervention and control sites and predisposes the study to a null result, leading to the conclusion that the intervention has no effect. We discuss how a rising tide may be distinguished from other causes of improvement in both control and intervention groups, and give examples where the rising tide provides a convincing explanation of such a finding. We offer recommendations for interpretation of research findings where improvements in the intervention group are matched by improvements in the control group. Understanding the rising tide phenomenon is important for a more nuanced interpretation of null results arising in the context of system-wide improvement. Recognition that a rising tide may have predisposed to a null result in one health system cautions against generalising the result to another health system where strong secular trends are absent.

  17. Preliminary Results on the Gravitational Slingshot Effect and the Population of Hyperbolic Meteoroids at Earth

    NASA Technical Reports Server (NTRS)

    Wiegert, P. A.

    2011-01-01

    Interstellar meteoroids, solid particles arriving from outside our Solar System, are not easily distinguished from local meteoroids. A velocity above the escape velocity of the Sun is often used as an indicator of a possible interstellar origin. We demonstrate that the gravitational slingshot effect, resulting from the passage of local meteoroid near a planet, can produce hyperbolic meteoroids at the Earth s orbit with excess velocities comparable to those expected of interstellar meteoroids.

  18. The effects from high-altitude storm discharges in Earth atmosphere

    NASA Astrophysics Data System (ADS)

    Kozak, L.; Odzimek, A.; Ivchenko, V.; Kozak, P.; Gala, I.; Lapchuk, V.

    2016-06-01

    The regularities of appearance of transient luminous effects in Earth atmosphere and features of their ground-based observations are considered. Using video-observations obtained in the Institution of Geophysics of Poland Academy of Sciences the energy of atmospheric afterglow from these processes in visual wavelength range has been determined. Calibrating curve was plotted using unfocal images of Vega. The star spectrum,atmosphere absorption coefficient and characteristics of the observational camera were used.

  19. The Role of Stereo Projection in Developing an Effective Concluding Earth Science Course

    NASA Astrophysics Data System (ADS)

    Kirkby, K. C.; Morin, P. J.; Finley, F.

    2003-12-01

    Remarkably few students enrolled in introductory earth science courses have any intention of continuing in earth science, and for most students, these classes are often the last science course they will take in their academic careers. These students would be better served, if the course was instead designed to be a 'concluding' science course. One that explicitly provided students with the knowledge they need to become more informed citizens in the global community. The University of Minnesota is attempting to develop a national model of an effective 'concluding' earth science course by integrating three essential approaches: use of regional case studies to increase student comprehension; a comprehensive evaluation of students' prior knowledge, misconceptions and post-instructional knowledge that is woven throughout the project; and, an ambitious use of 'GeoWall' stereo projection systems to facilitate the students' use of maps and data sets and level the classroom playing field with regard to spatial conceptualization. In every discipline there are some critical skills or assessments that serve as conscious or unconscious 'gate-keepers' for progress in that field. In earth science, map interpretation is probably the critical restriction curtailing students' ability to access and explore course concepts. So much of our discipline's information is encoded in maps, that students who are not innately predisposed to understanding maps find it difficult to understand much of the course content and methodology. GeoWall stereo projection systems can reduce the efficiency of this 'gate-keeping' process, allowing students of diverse backgrounds and abilities to understand map data and succeed in the course. In doing so, these systems will not only help increase students' scientific literacy, but may also greatly increase the diversity of students who do go on to consider earth science as a potential career.

  20. Effect of UV Radiation on the Spectral Fingerprints of Earth-like Planets Orbiting M Stars

    NASA Astrophysics Data System (ADS)

    Rugheimer, S.; Kaltenegger, L.; Segura, A.; Linsky, J.; Mohanty, S.

    2015-08-01

    We model the atmospheres and spectra of Earth-like planets orbiting the entire grid of M dwarfs for active and inactive stellar models with Teff = 2300 K to Teff = 3800 K and for six observed MUSCLES M dwarfs with UV radiation data. We set the Earth-like planets at the 1 AU equivalent distance and show spectra from the visible to IR (0.4-20 μm) to compare detectability of features in different wavelength ranges with the James Webb Space Telescope and other future ground- and spaced-based missions to characterize exo-Earths. We focus on the effect of UV activity levels on detectable atmospheric features that indicate habitability on Earth, namely, H2O, O3, CH4, N2O, and CH3Cl. To observe signatures of life—O2/O3 in combination with reducing species like CH4—we find that early and active M dwarfs are the best targets of the M star grid for future telescopes. The O2 spectral feature at 0.76 μm is increasingly difficult to detect in reflected light of later M dwarfs owing to low stellar flux in that wavelength region. N2O, another biosignature detectable in the IR, builds up to observable concentrations in our planetary models around M dwarfs with low UV flux. CH3Cl could become detectable, depending on the depth of the overlapping N2O feature. We present a spectral database of Earth-like planets around cool stars for directly imaged planets as a framework for interpreting future light curves, direct imaging, and secondary eclipse measurements of the atmospheres of terrestrial planets in the habitable zone to design and assess future telescope capabilities.

  1. EFFECT OF UV RADIATION ON THE SPECTRAL FINGERPRINTS OF EARTH-LIKE PLANETS ORBITING M STARS

    SciTech Connect

    Rugheimer, S.; Kaltenegger, L.; Segura, A.; Linsky, J.; Mohanty, S.

    2015-08-10

    We model the atmospheres and spectra of Earth-like planets orbiting the entire grid of M dwarfs for active and inactive stellar models with T{sub eff} = 2300 K to T{sub eff} = 3800 K and for six observed MUSCLES M dwarfs with UV radiation data. We set the Earth-like planets at the 1 AU equivalent distance and show spectra from the visible to IR (0.4–20 μm) to compare detectability of features in different wavelength ranges with the James Webb Space Telescope and other future ground- and spaced-based missions to characterize exo-Earths. We focus on the effect of UV activity levels on detectable atmospheric features that indicate habitability on Earth, namely, H{sub 2}O, O{sub 3}, CH{sub 4}, N{sub 2}O, and CH{sub 3}Cl. To observe signatures of life—O{sub 2}/O{sub 3} in combination with reducing species like CH{sub 4}—we find that early and active M dwarfs are the best targets of the M star grid for future telescopes. The O{sub 2} spectral feature at 0.76 μm is increasingly difficult to detect in reflected light of later M dwarfs owing to low stellar flux in that wavelength region. N{sub 2}O, another biosignature detectable in the IR, builds up to observable concentrations in our planetary models around M dwarfs with low UV flux. CH{sub 3}Cl could become detectable, depending on the depth of the overlapping N{sub 2}O feature. We present a spectral database of Earth-like planets around cool stars for directly imaged planets as a framework for interpreting future light curves, direct imaging, and secondary eclipse measurements of the atmospheres of terrestrial planets in the habitable zone to design and assess future telescope capabilities.

  2. Vibrios associated with red tides caused by Mesodinium rubrum.

    PubMed Central

    Romalde, J L; Barja, J L; Toranzo, A E

    1990-01-01

    Vibrios were isolated from red tides caused by Mesodinium rubrum and also throughout the year in the Ria de Pontevedra, Spain. The isolates were grouped into 14 phena by numerical toxonomy. Strains associated with red tides were restricted to four phena: phena I and II were Vibrio alginolyticus, and phena III and IV were Vibrio tubiashii and Vibrio anguillarum, respectively. V. anguillarum-like strains (phena V through XI) predominated throughout the year outside the red tide areas. Cytotoxicity assays conducted in different poikilothermic and homoiothermic cell lines showed that cytotoxin production was not necessarily associated with the species selected during the red tides. PMID:2268167

  3. Oceanic tide maps and spherical harmonic coefficients from Geosat altimetry

    NASA Technical Reports Server (NTRS)

    Cartwright, D. E.; Ray, R. D.; Sanchez, B. V.

    1991-01-01

    Maps and tables for the global ocean tides, 69 degree N to 68 degree S, derived from two years of Geosat altimetry are presented. Global maps of local and Greenwich admittance of the (altimetric) ocean tide, and maps of amplitude and Greenwich phase lag of the ocean tide are shown for M(sub 2), S(sub 2), N(sub 2), O(sub 1), and K(sub 1). Larger scale maps of amplitude and phases are also shown for regional areas of special interest. Spherical harmonic coefficients of the ocean tide through degree and order 8 are tabulated for the six major constituents.

  4. COCONet enhancements to circum-Caribbean tsunami warning, tidal, and sea-level monitoring: update on tide gauge installations

    NASA Astrophysics Data System (ADS)

    Dausz, K.; Dittmann, S. T.; Feaux, K.; von Hillebrandt-Andrade, C.; Mattioli, G. S.; Normandeau, J.

    2014-12-01

    The Continually Operating Caribbean GPS Observational Network (COCONet) is a National Science Foundation (NSF) funded multi-hazard geodetic and meteorological network distributed throughout the Caribbean, which provides infrastructure and capacity building for a broad range of earth science questions. The network is a multi-national collaboration consisting of 46 newly constructed continuous Global Positioning Systems (cGPS) and 21 refurbished existing GPS stations, all co-located with meteorological sensors. One recommendation of the COCONet working group was to improve the vertical reference frame for long-term sea level monitoring. A COCONet supplement was awarded by the NSF to further address this particular objective through the co-location of GPS and tide gauges. This COCOnet infrastructure, along with the new tide gauges, will have broad scientific implications for hazards mitigation, solid earth, and atmospheric science research. UNAVCO engineers have meet with members of the Caribbean tide gauge community to establish target locations and design station layout. Allocated NSF funds allow for the construction of two complete new tide gauge systems each with two complimentary cGPS. Following the recommendations of NOAA and the sea level monitoring community, the two "new" locales will be Port Royal, Jamaica and Puerto Morelos, Mexico. Both locations had previously existing, but currently non-operational tide gauges. UNAVCO engineers will install a Sutron Radar Level Recorder and a backup pressure sensor tide gauge with GOES satellite telemetry. Tide data will be freely available by the Intergovernmental Oceanographic Commission (www.ioc-sealevelmonitoring.org). The NSF supplement also provided funds for adding cGPS to two additional locations where currently functioning tide gauge systems exist. Proposed locations for this additional infrastructure are Barahona, Dominican Republic and Bocas del Toro, Panama. All four locations will feature two standard

  5. The effect of cloud type on Earth's energy balance - Global analysis

    NASA Technical Reports Server (NTRS)

    Hartmann, Dennis L.; Ockert-Bell, Maureen E.; Michelsen, Marc L.

    1992-01-01

    The role of fractional area coverage by cloud types in the energy balance of the earth is investigated through joint use of International Satellite Cloud Climatology Project (ISCCP) C1 cloud data and Earth Radiation Budget Experiment (ERBE) broadband energy flux data for the one-year period March 1985 through February 1986. Multiple linear regression is used to relate the radiation budget data to the cloud data. Comparing cloud forcing estimates obtained from the ISCCP-ERBE regression with those derived from the ERBE scene identification shows generally good agreement except over snow, in tropical convective regions, and in regions that are either nearly cloudless or always overcast. It is suggested that a substantial fraction of the disagreement in longwave cloud forcing in tropical convective regions is associated with the fact that the ERBE scene identification does not take into account variations in upper-tropospheric water vapor. On a global average basis, low clouds make the largest contribution to the net energy balance of the Earth, because they cover such a large area and because their albedo effect dominates their effect on emitted thermal radiation. High, optically thick clouds can also very effectively reduce the energy balance, however, because their very high albedos overcome their low emission temperatures.

  6. The Earth Exploration Toolbook: Scaffolding Access and Use of Earth Science Data to Promote Effective Inquiry Investigations by Students

    NASA Astrophysics Data System (ADS)

    Ledley, T. S.; Dahlman, L.; McAuliffe, C.; Haddad, N.

    2007-12-01

    The Earth Exploration Toolbook (EET, http://serc.carleton.edu/eet) is an online collection of computer-based Earth science activities. Each activity, or chapter, introduces one or more data sets and an analysis tool that enables users to explore some aspect of the Earth system. Series of step-by-step instructions show users how to 1) access the data and analysis tool and install it if necessary, 2) examine, visualize, and interpret the data, and 3) conduct a data-based investigation using the data and analysis tool. Step-by-step instructions walk users through valid scientific inquiries of the data to produce a map, graph, or other data product. The implicit goal of each chapter though, is to build the skills and confidence of teachers and students to enable them to learn and teach with data. When educators become familiar enough with data and analysis tools, they can adapt the use of data to match their curriculum and their students" abilities. This enables educators to promote a greater use of inquiry into students learning of scientific concepts. EET chapters are rich launching points for inquiry. Embedded open-ended questions ask users to consider various aspects of the data. These questions can begin the process of guided inquiry. The "Going Further" section of each EET chapter provides ideas for independent investigations, using another dataset or employing the same analysis strategy with a different analysis tool. At least one chapter inspired an award-winning high school science fair project. In this session we will examine the components of EET chapters that promote inquiry, describe the use of EET chapters in our teacher professional development programs, and give examples of how these programs have impacted participating teachers" use of data, analysis tools, and inquiry in their teaching.

  7. Antarctic tides from GRACE satellite accelerations

    NASA Astrophysics Data System (ADS)

    Wiese, D. N.; Killett, B.; Watkins, M. M.; Yuan, D.-N.

    2016-05-01

    The extended length of the GRACE data time series (now 13.5 years) provides the unique opportunity to estimate global mass variations due to ocean tides at large (˜300 km) spatial scales. State-of-the-art global tide models rely heavily on satellite altimetry data, which are sparse for latitudes higher than 66°. Thus, the performance of the models is typically worse at higher latitudes. GRACE data, alternately, extend to polar latitudes and therefore provide information for both model validation and improvement at the higher latitudes. In this work, 11 years of GRACE inter-satellite range-acceleration measurements are inverted to solve for corrections to the amplitudes and phases of the major solar and lunar ocean tidal constituents (M2, K1, S2, and O1) from the GOT4.7 ocean tide model at latitudes south of 50°S. Two independent inversion and regularization methods are employed and compared against one another. Uncertainty estimates are derived by subtracting two independent solutions, each spanning a unique 5.5 years of data. Features above the noise floor in the derived solutions likely represent errors in GOT4.7. We find the GOT4.7 amplitudes to be generally too small for M2 and K1, and too large for S2 and O1, and to spatially correlate with geographic regions where GOT4.7 predicts the largest tidal amplitudes. In particular, we find GOT4.7 errors to be dominant over the Patagonia shelf (M2), the Filchner-Ronne Ice Shelf (M2 and S2), the Ross Ice Shelf (S2), and the Weddell and Ross Seas (K1 and O1).

  8. Numerical simulation of tides in Ontario Lacus

    NASA Astrophysics Data System (ADS)

    Vincent, David; Karatekin, Ozgür

    2015-04-01

    Hydrocarbons liquid filled lakes has been recently detected on Titan's surface. Most of these lakes are located in the northern latitudes but there is a substantial lake in the southern latitudes: Ontario Lacus. This lake gets our attention because of possible shoreline changes suggested by Cassini flybys over Ontario Lacus between September 2005 (T7) et January 2010 (T65). The shoreline changes could be due to evaporation-precipitation processes but could also be a consequence of tides. Previous studies showed that the maximal tidal amplitudes of Ontario Lacus would be about 0.2m (for an uniform bathymetry of 20m). In this study we simulate tidal amplitude and currents with SLIM (Second-generation Louvain-la-Neuve Ice-ocean Model, http://sites.uclouvain.be/slim/ ) which resolves 2D shallow water equation on an unstructured mesh. Unstructured mesh prevents problems like mesh discontinuities at poles and allows higher accuracy at some place like coast or straits without drastically increasing computing costs. The tide generating force modeled in this work is the gradient of tidal potential due to titan's obliquity and titan's orbital eccentricity around Saturn (other contribution such as sun tide generating force are unheeded). The uncertain input parameters such as the wind direction and amplitude, bottom friction and thermo-physical properties of hydrocarbons liquids are varied within their expected ranges. SAR data analysis can result in different bathymetry according to the method. We proceed simulations for different bathymetries: tidal amplitudes doesn't change but this is not the case for tidal currents. Using a recent bathymetry deduced from most recent RADAR/SAR observations and a finer mesh, the peak-to peak tidal amplitudes are calculated to be up to 0.6 m. which is more than a factor two larger than the previous results. The maximal offshore tidal currents magnitude is about 0.06 m/s.

  9. 3D animations explaining the rotation, libration, and tides of planets

    NASA Astrophysics Data System (ADS)

    van Marcke de Lummen, J.; de Viron, O.; Dehant, V.; Defraigne, P.; Rosenblatt, P.; Karatekin, O.; van Hoolst, T.

    Space missions have always been appealing to the broad audience. In addition, the recent success of several experiments, revealing fascinating new information about the planets of the Solar System has had wide media coverage. For that reason, our team, involved in the preparation and analysis of missions such as Mars Express and BepiColombo is in contact with the press and with the public on a regular basis. It is not always an easy task to explain to a broad audience what we are doing on planets and why, because our science involves rather complicated computations of the deformations of the planet in response to gravitational forces, and of the variations of its orientation in space. Consequently, we decided to create computer animations to explain our work. These animations show how and why the rotations of the planets are not uniform and how and why the planets are changing their orientation in space. The films describe the precession, nutations, and polar motion, characteristics of the terrestrial planets such as the Earth and Mars, and the librations, characteristic of the terrestrial bodies such as Mercury and the icy satellites. The animations also describe the gravitational effects on a spacecraft orbiting around a planet as well as the tides induced by the Sun or the planets on the planets themselves. These films have the advantage of allowing the press and the public to have a correct and appealing representation of phenomena as complex as planetary tides, gravity perturbation on an ˇ orbit, precession, etcE The concept of the animations is a result of many discussions between scientists, and the movies have been generated on Blender, which is an open source software for 3D modeling, animation, rendering, post-production, interactive creation and playback (available on www.blender3D.org). Those movies have been shown very helpful when meeting the press (some of them aired on television), or the science decision makers, which fully justifies the work

  10. Use of global positioning system measurements to determine geocentric coordinates and variations in Earth orientation

    NASA Technical Reports Server (NTRS)

    Malla, R. P.; Wu, S.-C.; Lichten, S. M.

    1993-01-01

    Geocentric tracking station coordinates and short-period Earth-orientation variations can be measured with Global Positioning System (GPS) measurements. Unless calibrated, geocentric coordinate errors and changes in Earth orientation can lead to significant deep-space tracking errors. Ground-based GPS estimates of daily and subdaily changes in Earth orientation presently show centimeter-level precision. Comparison between GPS-estimated Earth-rotation variations, which are the differences between Universal Time 1 and Universal Coordinated Time (UT1-UTC), and those calculated from ocean tide models suggests that observed subdaily variations in Earth rotation are dominated by oceanic tidal effects. Preliminary GPS estimates for the geocenter location (from a 3-week experiment) agree with independent satellite laser-ranging estimates to better than 10 cm. Covariance analysis predicts that temporal resolution of GPS estimates for Earth orientation and geocenter improves significantly when data collected from low Earth-orbiting satellites as well as from ground sites are combined. The low Earth GPS tracking data enhance the accuracy and resolution for measuring high-frequency global geodynamical signals over time scales of less than 1 day.

  11. Long-term increase in New York Harbor storm tides, 1844-present

    NASA Astrophysics Data System (ADS)

    Talke, S. A.; Orton, P. M.; Jay, D. A.

    2014-12-01

    Eight of the largest twenty recorded water levels in the New York Harbor region recorded since 1821 occurred after 1990, and three of the 10 largest have occurred since 2010 (March 2010, August 2011, and October 2012). Archival research and numerical modeling indicates, however, that the storm surge during an 1821 hurricane exceeded that from hurricane Sandy (~3.5m vs. 2.8m). To investigate flood risk we recover archival tide gauge data back to 1844 and evaluate whether the recent cluster of extreme water levels is random, driven solely by sea-level rise, or is caused by changes to storm tides (the sum of storm surge and tidal effects). Results indicate both long term trends and decadal variability in the annual maximum storm tide (AMST). Approximately half of long-term AMST variability is explained by a long term increase in storm tides, while the remainder is explained by the North Atlantic Oscillation. The magnitude of the 10 year return period storm tide has increased by 0.28m. Combined with a 0.44m increase in local sea level since 1856, the 10 year flood level has increased by approximately 0.72 ± 0.25m, and magnified the annual probability of overtopping the nominal Manhattan seawall from less than 1% to about 20-25%. Further, including the 1821 event in extreme value analysis suggests that the return period of hurricane Sandy storm tides is much smaller than other estimates. Though the cause of the long-term AMST trend is unclear, analysis of tidal properties indicates that long-wave propagation in New York harbor has shifted since the 1850s. Because storm surge is also a long-wave with a component in the tidal band, at least a portion of changed storm-tide hazard is likely driven by local anthropogenic alterations of the region's waterways. Along with sea-level rise, local development and climate-induced shifts to the North Atlantic Oscillation may continue to affect the New York harbor storm tide hazard in the future.

  12. The impact of future sea-level rise on the European Shelf tides

    NASA Astrophysics Data System (ADS)

    Pickering, M. D.; Wells, N. C.; Horsburgh, K. J.; Green, J. A. M.

    2012-03-01

    This paper investigates the effect of future sea-level rise (SLR) on the tides of the northwest European Continental Shelf. The European shelf tide is dominated by semidiurnal constituents. This study therefore focuses primarily on the changes in the M2 tidal constituent and the spring and neap tidal conditions. The validated operational Dutch Continental Shelf Model is run for the present day sea-level as well as 2 and 10 m SLR scenarios. The M2 tidal amplitude responds to SLR in a spatially non-uniform manner, with substantial amplitude increases and decreases in both scenarios. The M2 tidal response is non-linear between 2 and 10 m with respect to SLR, particularly in the North Sea. Under the 2 m SLR scenario the M2 constituent is particularly responsive in the resonant areas of the Bristol Channel and Gulf of St. Malo (with large amplitude decreases) and in the southeastern German Bight and Dutch Wadden Sea (with large amplitude increases). Changes in the spring tide are generally greater still than those in the M2 or neap tides. With 2 m SLR the spring tidal range increases up to 35 cm at Cuxhaven and decreases up to -49 cm at St. Malo. Additionally the changes in the shallow water tides are larger than expected. With SLR the depth, wave speed and wave length (tidal resonance characteristics) are increased causing changes in near resonant areas. In expansive shallow areas SLR causes reduced energy dissipation by bottom friction. Combined these mechanisms result in the migration of the amphidromes and complex patterns of non-linear change in the tide with SLR. Despite the significant uncertainty associated with the rate of SLR over the next century, substantial alterations to tidal characteristics can be expected under a high end SLR scenario. Contrary to existing studies this paper highlights the importance of considering the modification of the tides by future SLR. These substantial future changes in the tides could have wide reaching implications; including

  13. Proceedings of the Geodesy/Solid Earth and Ocean Physics (GEOP) Research Conferences

    NASA Technical Reports Server (NTRS)

    Mueller, I. I. (Editor)

    1975-01-01

    Papers are presented dealing with interdisciplinary research in the fields of geodesy, solid earth and ocean physics. Topics discussed include: solid earth and ocean tides; the rotation of the earth and polar motion; vertical crustal motions; the geoid and ocean surface; earthquake mechanism; sea level changes; and lunar dynamics.

  14. Applicability of Hydrogen Peroxide in Brown Tide Control – Culture and Microcosm Studies

    PubMed Central

    Randhawa, Varunpreet; Thakkar, Megha; Wei, Liping

    2012-01-01

    Brown tide algal blooms, caused by the excessive growth of Aureococcus anophagefferens, recur in several northeastern US coastal bays. Direct bloom control could alleviate the ecological and economic damage associated with bloom outbreak. This paper explored the effectiveness and safety of natural chemical biocide hydrogen peroxide (H2O2) for brown tide bloom control. Culture studies showed that H2O2 at 1.6 mg L−1 effectively eradicated high density A. anophagefferens within 24-hr, but caused no significant growth inhibition in the diatoms, prymnesiophytes, green algae and dinoflagellates of >2–3 μm cell sizes among 12 phytoplankton species tested over 1-week observation. When applied to brown tide bloom prone natural seawater in a microcosm study, this treatment effectively removed the developing brown tide bloom, while the rest of phytoplankton assemblage (quantified via HPLC based marker pigment analyses), particularly the diatoms and green algae, experienced only transient suppression then recovered with total chlorophyll a exceeding that in the controls within 72-hr; cyanobacteria was not eradicated but was still reduced about 50% at 72-hr, as compared to the controls. The action of H2O2 against phytoplankton as a function of cell size and cell wall structure, and a realistic scenario of H2O2 application were discussed. PMID:23082223

  15. Applicability of hydrogen peroxide in brown tide control - culture and microcosm studies.

    PubMed

    Randhawa, Varunpreet; Thakkar, Megha; Wei, Liping

    2012-01-01

    Brown tide algal blooms, caused by the excessive growth of Aureococcus anophagefferens, recur in several northeastern US coastal bays. Direct bloom control could alleviate the ecological and economic damage associated with bloom outbreak. This paper explored the effectiveness and safety of natural chemical biocide hydrogen peroxide (H(2)O(2)) for brown tide bloom control. Culture studies showed that H(2)O(2) at 1.6 mg L(-1) effectively eradicated high density A. anophagefferens within 24-hr, but caused no significant growth inhibition in the diatoms, prymnesiophytes, green algae and dinoflagellates of >2-3 μm cell sizes among 12 phytoplankton species tested over 1-week observation. When applied to brown tide bloom prone natural seawater in a microcosm study, this treatment effectively removed the developing brown tide bloom, while the rest of phytoplankton assemblage (quantified via HPLC based marker pigment analyses), particularly the diatoms and green algae, experienced only transient suppression then recovered with total chlorophyll a exceeding that in the controls within 72-hr; cyanobacteria was not eradicated but was still reduced about 50% at 72-hr, as compared to the controls. The action of H(2)O(2) against phytoplankton as a function of cell size and cell wall structure, and a realistic scenario of H(2)O(2) application were discussed.

  16. Compact High Current Rare-Earth Emitter Hollow Cathode for Hall Effect Thrusters

    NASA Technical Reports Server (NTRS)

    Hofer, Richard R. (Inventor); Goebel, Dan M. (Inventor); Watkins, Ronnie M. (Inventor)

    2012-01-01

    An apparatus and method for achieving an efficient central cathode in a Hall effect thruster is disclosed. A hollow insert disposed inside the end of a hollow conductive cathode comprises a rare-earth element and energized to emit electrons from an inner surface. The cathode employs an end opening having an area at least as large as the internal cross sectional area of the rare earth insert to enhance throughput from the cathode end. In addition, the cathode employs a high aspect ratio geometry based on the cathode length to width which mitigates heat transfer from the end. A gas flow through the cathode and insert may be impinged by the emitted electrons to yield a plasma. One or more optional auxiliary gas feeds may also be employed between the cathode and keeper wall and external to the keeper near the outlet.

  17. Angular momentum budget of the radiational S1 ocean tide

    NASA Astrophysics Data System (ADS)

    Schindelegger, Michael; Dobslaw, Henryk; Poropat, Lea; Salstein, David; Böhm, Johannes

    2016-04-01

    The balance of diurnal S1 oceanic angular momentum (OAM) variations through torques at the sea surface and the bottom topography is validated using both a barotropic and a baroclinic numerical tide model. This analysis discloses the extent to which atmosphere-driven S1 forward simulations are reliable for use in studies of high-frequency polar motion and changes in length-of-day. Viscous and dissipative torques associated with wind stress, bottom friction, as well as internal tidal energy conversion are shown to be small, and they are overshadowed by gravitational and pressure-related interaction forces. In particular, the zonal OAM variability of S1 is almost completely balanced by the water pressure torque on the local bathymetry, whereas in the prograde equatorial case also the air pressure torque on the seafloor as well as ellipsoidal contributions from the non-spherical atmosphere and solid Earth must be taken into account. Overall, the OAM budget is well closed in both the axial and the equatorial directions, thus allowing for an identification of the main diurnal angular momentum sinks in the ocean. The physical interaction forces are found to be largest at shelf breaks and continental slopes in low latitudes, with the most dominant contribution coming from the Indonesian archipelago.

  18. A reappraisal of Darwin's fission hypothesis and a possible limit to the primordial angular momentum of the Earth

    NASA Technical Reports Server (NTRS)

    Mckinnon, W. B.; Mueller, S. W.

    1984-01-01

    G. H. Darwin proposed that the primordial Earth may have rotated fast enough that the solar tidal period was nearly resonant with the fundamental free oscillation period of a fluid Earth and that a large and unstable tidal oscillation split off to become the moon. Jeffreys argumented that dissipation during resonance would be sufficient to prevent such an unstable oscillation greater than the tidal frequency (period - 2.68 hr). It is considered that solar tides have extracted angular momentum from the Earth-Moon system over 4.5 b.y. The correspondence of the primordial tidal and resonant frequencies is nearly exact. (The effect of central condensation of the proto earth is to increase both frequencies by a similar amount, though the resonance is not precisely known. This result, was unknown to Darwin or Jeffreys. The effects of resonance were evaluated. The resonance is likely to be too damped for fission. This argument is more general than Jeffreys', who considered friction between the oscillating mantle and a rigid core. It is argued that the fact that Q must be so great for fission that equilibrium can not be maintained; the fluid proto Earth passes so quickly through resonance that maximum amplitude is not reached. It is suggested that solar resonant tides acted as a brake on the spin of the primordial partially molten Earth. Certain proposed origins for the Moon do not necessarily involve addition of substantial amounts of angular momentum to the Earth-Moon system. The primordial Earth-Moon system may have had nearly the same angular momentum as it has today.

  19. Reappraisal of Darwin's fission hypothesis and a possible limit to the primordial angular momentum of the Earth

    SciTech Connect

    Mckinnon, W.B.; Mueller, S.W.

    1984-01-01

    G. H. Darwin proposed that the primordial Earth may have rotated fast enough that the solar tidal period was nearly resonant with the fundamental free oscillation period of a fluid Earth and that a large and unstable tidal oscillation split off to become the moon. Jeffreys argumented that dissipation during resonance would be sufficient to prevent such an unstable oscillation greater than the tidal frequency (period - 2.68 hr). It is considered that solar tides have extracted angular momentum from the Earth-Moon system over 4.5 b.y. The correspondence of the primordial tidal and resonant frequencies is nearly exact. (The effect of central condensation of the proto earth is to increase both frequencies by a similar amount, though the resonance is not precisely known. This result, was unknown to Darwin or Jeffreys. The effects of resonance were evaluated. The resonance is likely to be too damped for fission. This argument is more general than Jeffreys, who considered friction between the oscillating mantle and a rigid core. It is argued that the fact that Q must be so great for fission that equilibrium can not be maintained. The fluid proto Earth passes so quickly through resonance that maximum amplitude is not reached. It is suggested that solar resonant tides acted as a brake on the spin of the primordial partially molten Earth. Certain proposed origins for the Moon do not necessarily involve addition of substantial amounts of angular momentum to the Earth-Moon system. The primordial Earth-Moon system may have had nearly the same angular momentum as it has today.

  20. Tidal Friction in the Earth and Ocean

    NASA Astrophysics Data System (ADS)

    Ray, R. D.

    2006-12-01

    "Tidal Friction" is a classic subject in geophysics, with ties to some of the great scientists of the Victorian era. The subject has been reinvigorated over the past decade by space geodesy, and particularly by the Topex/Poseidon satellite altimeter mission. In fact, the topic has now taken on some significance in oceanography, with potential implications for problems of mixing, thermocline maintenance, and the thermohaline circulation. Likewise, tidal measurements have become sufficiently precise to reveal new information about the solid earth. In this respect, the tidal force is an invaluable "probe" of the earth, at frequencies well outside the seismic band. This talk will "follow the energy" of tides while noting some important geophysical implications at each stage. In the present earth-moon-sun configuration, energy for tides is extracted from the earth's rotation. Ancient eclipses bear witness to this, and the discrepancy between Babylonian (and other) observations and tidal predictions yields unique information about the mantle and the overlying fluid envelope. Complementary information comes from tidal anelasticity estimates, which are now available at frequencies ranging from semidiurnal to fortnightly, monthly, and 18.6 years. These data, when combined with various kinds of gravity measurements, are relevant to the present-day sea-level problem. Solid-earth tidal dissipation represents less than 5% of the system total. As has long been realized, the largest energy sink is the ocean. About 70% of the oceanic dissipation occurs in shallow seas (the traditional sink) and 30% in the deep ocean, generally near rugged bottom topography. The latter represents a substantial amount of power, roughly 1 gigawatt, available for generation of internal tides and other baroclinic motions. Experiments like HOME are helping unravel the links between barotropic tides, internal tides, turbulence, and mixing. The latter opens possible linkages to climate, and recent work

  1. Europa Tide Inversion from REASON Altimetry

    NASA Astrophysics Data System (ADS)

    Haynes, M.; Schroeder, D. M.; Steinbrügge, G.; Bills, B. G.

    2015-12-01

    Determining the amplitude of Europa's tides is central to understanding its ice shell and subsurface ocean. We assess the accuracy of retrieving the tidal amplitude solely using altimetry profiles produced by the REASON instrument (Radar for Europa Assessment and Sounding: Ocean to Near-surface), selected for the Europa Clipper mission. We investigate retrieval of the first Love number, h2, by inverting the entire set of altimetric ground tracks over the life of the mission. The inversion simultaneously estimates h2, long-wavelength topography, and spacecraft orbit parameters. In its simplest form, the inversion is quite robust: the time and location of the ground track uniquely fixes the phase of the sampled tide, where surface roughness acts as noise to be averaged out. In addition, we make an initial evaluation of altimetric biases that arise from known and hypothesized Europa topography using surface point target simulations. Overall, we find that the altimeter alone is capable of retrieving the first tidal Love number with accuracy sufficient to observationally constrain ice-shell thickness.

  2. Effects on optical systems from interactions with oxygen atoms in low earth orbits

    NASA Technical Reports Server (NTRS)

    Peters, P. N.; Swann, J. T.; Gregory, J. C.

    1986-01-01

    Modifications of material surface properties due to interactions with ambient atomic oxygen have been observed on surfaces facing the orbital direction in low earth orbits. Some effects are very damaging to surface optical properties while some are more subtle and even beneficial. Most combustible materials are heavily etched, and some coatings, such as silver and osmium, are seriously degraded or removed as volatile oxides. The growth of oxide films on metals and semiconductors considered stable in dry air was measured. Material removal, surface roughness, reflectance, and optical densities are reported. Effects of temperature, contamination, and overcoatings are noted.

  3. Test of general relativity and measurement of the lense-thirring effect with two earth satellites

    PubMed

    Ciufolini; Pavlis; Chieppa; Fernandes-Vieira; Perez-Mercader

    1998-03-27

    The Lense-Thirring effect, a tiny perturbation of the orbit of a particle caused by the spin of the attracting body, was accurately measured with the use of the data of two laser-ranged satellites, LAGEOS and LAGEOS II, and the Earth gravitational model EGM-96. The parameter &mgr;, which measures the strength of the Lense-Thirring effect, was found to be 1.1 +/- 0.2; general relativity predicts &mgr; identical with 1. This result represents an accurate test and measurement of one of the fundamental predictions of general relativity, that the spin of a body changes the geometry of the universe by generating space-time curvature.

  4. Empirical determination of the effects of clouds on the Earth's Radiation Budget over the Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Ziskin, Daniel; Strobel, Darrell F.

    1992-01-01

    The main objectives of this research has been to learn how clouds interact with the Earth's Radiation Budget (ERB). This broad goal has been approached in three distinct ways. The first has been to analyze the direct effect cloud amount has on the radiative components of the ERB. The second has been to investigate the indirect effects clouds and water vapor may have on the climate as a feedback mechanism. And finally an attempt has been made to simulate the findings in a simple radiative-convective climate model. This report will summarize these three phases of the research.

  5. Solar and terrestrial physics. [effects of solar activities on earth environment

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The effects of solar radiation on the near space and biomental earth, the upper atmosphere, and the magnetosphere are discussed. Data obtained from the OSO satellites pertaining to the solar cycle variation of extreme ultraviolet (EUV) radiation are analyzed. The effects of solar cycle variation of the characteristics of the solar wind are examined. The fluid mechanics of shock waves and the specific relationship to the characteristics of solar shock waves are investigated. The solar and corpuscular heating of the upper atmosphere is reported based on the findings of the AEROS and NATE experiments. Seasonal variations of the upper atmosphere composition are plotted based on OGO-6 mass spectrometer data.

  6. On the Effects of the Evolution of Microbial Mats and Land Plants on the Earth as a Planet. Photometric and Spectroscopic Light Curves of Paleo-Earths

    NASA Astrophysics Data System (ADS)

    Sanromá, E.; Pallé, E.; García Munõz, A.

    2013-04-01

    Understanding the spectral and photometric variability of the Earth and the rest of the solar system planets has become of utmost importance for the future characterization of rocky exoplanets. As this is not only interesting at present times but also along the planetary evolution, we studied the effect that the evolution of microbial mats and plants over land has had on the way our planet looks from afar. As life evolved, continental surfaces changed gradually and non-uniformly from deserts through microbial mats to land plants, modifying the reflective properties of the ground and most likely the distribution of moisture and cloudiness. Here, we used a radiative transfer model of the Earth, together with geological paleo-records of the continental distribution and a reconstructed cloud distribution, to simulate the visible and near-IR radiation reflected by our planet as a function of Earth's rotation. We found that the evolution from deserts to microbial mats and to land plants produces detectable changes in the globally averaged Earth's reflectance. The variability of each surface type is located in different bands and can induce reflectance changes of up to 40% in period of hours. We conclude that by using photometric observations of an Earth-like planet at different photometric bands it would be possible to discriminate between different surface types. While recent literature proposes the red-edge feature of vegetation near 0.7 μm as a signature for land plants, observations in near-IR bands can be equally or even better suited for this purpose.

  7. ON THE EFFECTS OF THE EVOLUTION OF MICROBIAL MATS AND LAND PLANTS ON THE EARTH AS A PLANET. PHOTOMETRIC AND SPECTROSCOPIC LIGHT CURVES OF PALEO-EARTHS

    SciTech Connect

    Sanroma, E.; Palle, E.; Garcia Munoz, A.

    2013-04-01

    Understanding the spectral and photometric variability of the Earth and the rest of the solar system planets has become of utmost importance for the future characterization of rocky exoplanets. As this is not only interesting at present times but also along the planetary evolution, we studied the effect that the evolution of microbial mats and plants over land has had on the way our planet looks from afar. As life evolved, continental surfaces changed gradually and non-uniformly from deserts through microbial mats to land plants, modifying the reflective properties of the ground and most likely the distribution of moisture and cloudiness. Here, we used a radiative transfer model of the Earth, together with geological paleo-records of the continental distribution and a reconstructed cloud distribution, to simulate the visible and near-IR radiation reflected by our planet as a function of Earth's rotation. We found that the evolution from deserts to microbial mats and to land plants produces detectable changes in the globally averaged Earth's reflectance. The variability of each surface type is located in different bands and can induce reflectance changes of up to 40% in period of hours. We conclude that by using photometric observations of an Earth-like planet at different photometric bands it would be possible to discriminate between different surface types. While recent literature proposes the red-edge feature of vegetation near 0.7 {mu}m as a signature for land plants, observations in near-IR bands can be equally or even better suited for this purpose.

  8. Mesosphere Dynamics with Gravity Wave Forcing. 1; Diurnal and Semi-Diurnal Tides

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Mengel, J. G.; Chan, K. L.; Porter, H. S.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    We present results from a nonlinear, 3D, time dependent numerical spectral model (NSM), which extends from the ground up into the thermosphere and incorporates Hines' Doppler Spread Parameterization for small-scale gravity waves (GW). Our focal point is the mesosphere that is dominated by wave interactions. We discuss diurnal and semi-diurnal tides ill the present paper (Part 1) and planetary waves in the companion paper (Part 2). To provide an understanding of the seasonal variations of tides, in particular with regard to gravity wave processes, numerical experiments are performed that lead to the following conclusions: 1. The large semiannual variations in tile diurnal tide (DT), with peak amplitudes observed around equinox, are produced primarily by GW interactions that involve, in part, planetary waves. 2. The DT, like planetary waves, tends to be amplified by GW momentum deposition, which reduces also the vertical wavelength. 3.Variations in eddy viscosity associated with GW interactions tend to peak in late spring and early fall and call also influence the DT. 4. The semidiurnal semidiurnal tide (SDT), and its phase in particular, is strongly influenced by the mean zonal circulation. 5. The SDT, individually, is amplified by GW's. But the DT filters out GW's such that the wave interaction effectively reduces the amplitude of the SDT, effectively producing a strong nonlinear interaction between the DT and SDT. 6.) Planetary waves generated internally by baroclinic instability and GW interaction produce large amplitude modulations of the DT and SDT.

  9. Complex demodulation in VLBI estimation of high frequency Earth rotation components

    NASA Astrophysics Data System (ADS)

    Böhm, S.; Brzeziński, A.; Schuh, H.

    2012-12-01

    The spectrum of high frequency Earth rotation variations contains strong harmonic signal components mainly excited by ocean tides along with much weaker non-harmonic fluctuations driven by irregular processes like the diurnal thermal tides in the atmosphere and oceans. In order to properly investigate non-harmonic phenomena a representation in time domain is inevitable. We present a method, operating in time domain, which is easily applicable within Earth rotation estimation from Very Long Baseline Interferometry (VLBI). It enables the determination of diurnal and subdiurnal variations, and is still effective with merely diurnal parameter sampling. The features of complex demodulation are used in an extended parameterization of polar motion and universal time which was implemented into a dedicated version of the Vienna VLBI Software VieVS. The functionality of the approach was evaluated by comparing amplitudes and phases of harmonic variations at tidal periods (diurnal/semidiurnal), derived from demodulated Earth rotation parameters (ERP), estimated from hourly resolved VLBI ERP time series and taken from a recently published VLBI ERP model to the terms of the conventional model for ocean tidal effects in Earth rotation recommended by the International Earth Rotation and Reference System Service (IERS). The three sets of tidal terms derived from VLBI observations extensively agree among each other within the three-sigma level of the demodulation approach, which is below 6 μas for polar motion and universal time. They also coincide in terms of differences to the IERS model, where significant deviations primarily for several major tidal terms are apparent. An additional spectral analysis of the as well estimated demodulated ERP series of the ter- and quarterdiurnal frequency bands did not reveal any significant signal structure. The complex demodulation applied in VLBI parameter estimation could be demonstrated a suitable procedure for the reliable reproduction of

  10. High-Accuracy Ring Laser Gyroscopes: Earth Rotation Rate and Relativistic Effects

    NASA Astrophysics Data System (ADS)

    Beverini, N.; Di Virgilio, A.; Belfi, J.; Ortolan, A.; Schreiber, K. U.; Gebauer, A.; Klügel, T.

    2016-06-01

    The Gross Ring G is a square ring laser gyroscope, built as a monolithic Zerodur structure with 4 m length on all sides. It has demonstrated that a large ring laser provides a sensitivity high enough to measure the rotational rate of the Earth with a high precision of ΔΩE < 10-8. It is possible to show that further improvement in accuracy could allow the observation of the metric frame dragging, produced by the Earth rotating mass (Lense-Thirring effect), as predicted by General Relativity. Furthermore, it can provide a local measurement of the Earth rotational rate with a sensitivity near to that provided by the international system IERS. The GINGER project is intending to take this level of sensitivity further and to improve the accuracy and the long-term stability. A monolithic structure similar to the G ring laser is not available for GINGER. Therefore the preliminary goal is the demonstration of the feasibility of a larger gyroscope structure, where the mechanical stability is obtained through an active control of the geometry. A prototype moderate size gyroscope (GP-2) has been set up in Pisa in order to test this active control of the ring geometry, while a second structure (GINGERino) has been installed inside the Gran Sasso underground laboratory in order to investigate the properties of a deep underground laboratory in view of an installation of a future GINGER apparatus. The preliminary data on these two latter instruments are presented.

  11. Displacements of the earth's surface due to atmospheric loading - Effects of gravity and baseline measurements

    NASA Technical Reports Server (NTRS)

    Van Dam, T. M.; Wahr, J. M.

    1987-01-01

    Atmospheric mass loads and deforms the earth's crust. By performing a convolution sum between daily, global barometric pressure data and mass loading Green's functions, the time dependent effects of atmospheric loading, including those associated with short-term synoptic storms, on surface point positioning measurements and surface gravity observations are estimated. The response for both an oceanless earth and an earth with an inverted barometer ocean is calculated. Load responses for near-coastal stations are significantly affected by the inclusion of an inverted barometer ocean. Peak-to-peak vertical displacements are frequently 15-20 mm with accompanying gravity perturbations of 3-6 micro Gal. Baseline changes can be as large as 20 mm or more. The perturbations are largest at higher latitudes and during winter months. These amplitudes are consistent with the results of Rabbel and Zschau (1985), who modeled synoptic pressure disturbances as Gaussian functions of radius around a central point. Deformation can be adequately computed using real pressure data from points within about 1000 km of the station. Knowledge of local pressure, alone, is not sufficient. Rabbel and Zschau's hypothesized corrections for these displacements, which use local pressure and the regionally averaged pressure, prove accurate at points well inland but are, in general, inadequate within a few hundred kilometers of the coast.

  12. A complete spherical harmonic approach to luni-solar tides

    NASA Technical Reports Server (NTRS)

    Dickman, S. R.

    1989-01-01

    In this work a spherical harmonic theory of ocean tides is presented. The theory is based on Laplace tide equations modified to include turbulence with constant eddy viscosity, linearized bottom friction, and oceanic loading and self-gravitation. Variable bathymetry is also treated in harmonic terms, and no-flow boundary conditions are applied at continental coastlines. The tide and boundary constraint equations are reduced to matrix form and solved by a weighted least-squares procedure. Five zonal luni-solar tides, ranging in period from 14 days to 18.6 yr, are investigated using the theory; such tides have typically been difficult to compute using traditional numerical approaches. The polar motion and changes in the length of day induced by these long-period tides are calculated. Tidal solutions are compared extensively with results from other tidal theories and from recent satellite and sea-level observations. The greatest limitation to accurate prediction of zonal tides - for any theory - appears to be the marginal failure of all tide theories to conserve mass globally; the use of additional mass constraints may be warranted.

  13. The Effect of Alkaline Earth Metal on the Cesium Loading of Ionsiv(R) IE-910 and IE-911

    SciTech Connect

    Fondeur, F.F.

    2001-01-16

    This study investigated the effect of variances in alkaline earth metal concentrations on cesium loading of IONSIV(R) IE-911. The study focused on Savannah River Site (SRS) ''average'' solution with varying amounts of calcium, barium and magnesium.

  14. Truncation effects in computing free wobble/nutation modes explored using a simple Earth model

    NASA Astrophysics Data System (ADS)

    Seyed-Mahmoud, Behnam; Rochester, Michael G.; Rogers, Christopher M.

    2017-03-01

    The displacement field accompanying the wobble/nutation of the Earth is conventionally represented by an infinite chain of toroidal and spheroidal vector spherical harmonics, coupled by rotation and ellipticity. Numerical solutions for the eigenperiods require truncation of that chain, and the standard approaches using the linear momentum description (LMD) of deformation during wobble/nutation have truncated it at very low degrees, usually degree 3 or 4, and at most degree 5. The effects of such heavy truncation on the computed eigenperiods have hardly been examined. We here investigate the truncation effects on the periods of the free wobble/nutation modes using a simplified Earth model consisting of a homogeneous incompressible inviscid liquid outer core with a rigid (but not fixed) inner core and mantle. A novel Galerkin method is implemented using a Clairaut coordinate system to solve the classic Poincaré problem in the liquid core and, to close the problem, we use the Lagrangean formulation of the Liouville equation for each of the solid parts of the Earth model. We find that, except for the free inner core nutation (FICN), the periods of the free rotational modes converge rather quickly. The period of the tiltover mode (TOM) is found to excellent accuracy. The computed periods of the Chandler wobble (CW) and free core nutation (FCN) are nearly identical to the values cited in the literature for similar Earth models, but that for the inner core wobble (ICW) is slightly different. Truncation at low-degree harmonics causes the FICN period to fluctuate over a range as large as 90 sd, with different values at different truncation levels. For example, truncation at degree 6 gives a period of 752 sd (almost identical with the value cited in the literature for such an Earth model) but truncation at degree 24 is required to obtain convergence, and the resulting period is 746 ± 1 sd, as more terms are included, with no guarantee that its proximity to earlier values

  15. Human responses to Florida red tides: policy awareness and adherence to local fertilizer ordinances.

    PubMed

    Kirkpatrick, Barbara; Kohler, Kate; Byrne, Margaret; Fleming, Lora E; Scheller, Karen; Reich, Andrew; Hitchcock, Gary; Kirkpatrick, Gary; Ullmann, Steven; Hoagland, Porter

    2014-09-15

    To mitigate the damages of natural hazards, policy responses can be beneficial only if they are effective. Using a self-administered survey approach, this paper focuses on the adherence to local fertilizer ordinances (i.e., county or municipal rules regulating the application of fertilizer to private lawns or facilities such as golf courses) implemented in jurisdictions along the Southwest Florida coast in response to hazardous blooms of Florida red tides (Karenia brevis). These ordinances play a role in the context of evolving programs of water pollution control at federal, state, water basin, and local levels. With respect to policy effectiveness, while the strength of physical linkages is of critical importance, the extent to which humans affected are aware of and adhere to the relevant rules, is equally critical. We sought to understand the public's depth of understanding about the rationales for local fertilizer ordinances. Respondents in Sarasota, Florida, were asked about their fertilizer practices in an area that has experienced several major blooms of Florida red tides over the past two decades. A highly educated, older population of 305 residents and "snowbirds" reported relatively little knowledge about a local fertilizer ordinance, its purpose, or whether it would change the frequency, size, or duration of red tides. This finding held true even among subpopulations that were expected to have more interest in or to be more knowledgeable about harmful algal blooms. In the face of uncertain science and environmental outcomes, and with individual motivations at odds with evolving public policies, the effectiveness of local community efforts to decrease the impacts of red tides may be compromised. Targeted social-science research on human perceptions about the risks of Florida red tides and education about the rationales for potential policy responses are warranted.

  16. New estimates of secular sea level rise from tide gauge data and GIA modelling

    NASA Astrophysics Data System (ADS)

    Spada, Giorgio; Galassi, Gaia

    2012-12-01

    During the last three decades, at least 30 independent estimates of the secular global mean sea level rise (GMSLR) have been published, based on sufficiently long tide gauge (TG) records. Despite its apparent simplicity, the problem of GMSLR is fraught with a number of difficulties, which make it one of the most challenging questions of climate change science. Not surprisingly, published estimates show considerable scatter, with rates ranging between 1 and 2 mm yr-1 for observations on the century timescale. In previous work, the importance of Glacial Isostatic Adjustment (GIA) upon the assessment of the GMSLR has been clearly demonstrated. In particular, starting from the 1980s, GIA models have been routinely employed to decontaminate TG observations from the effects of melting of the late-Pleistocene ice sheets, to fully highlight the sea level variations driven by climate change. However, uncertainties associated with the Earth's rheological profile and the time history of the past continental ice sheets can propagate into the GIA corrections. After revisiting previous work and estimates, we suggest a significant modification of the criteria for the selection of the TGs which are most suitable for the robust assessment of the secular GMSLR. In particular, we seek a set of TGs for which GIA corrections are essentially independent of the parametrization of the rheological profile of the Earth's mantle and of the detailed time chronology of surface loading. This insensitivity is established by considering predictions based upon three GIA models widely employed in the recent literature (namely, ICE-3G, ICE-5G and the one developed at the Research School of Earth Sciences of the National Australian University). Applying this approach and selection criteria previously proposed in the literature, we identify a set of 22 sufficiently evenly distributed TGs. By simple statistical methods, these records yield a 'preferred', GIA-independent GMSLR estimate since 1880

  17. Effect of Irregularities in the Earth's Rotation on Relativistic Shifts in Frequency and Time of Earthbound Atomic Clocks

    NASA Astrophysics Data System (ADS)

    Fateev, V. F.; Kopeikin, S. M.; Pasynok, S. L., S. L.

    2015-10-01

    The effect of irregularities in the earth's rotation (precession and nutation of the earth's axis of rotation, oscillations in the modulus of the angular velocity, periodic deviations in the line of the poles, and the angular momentum of the globe) on the frequency and time of high-stability atomic clocks are examined in terms of the theory of relativity. It is shown that the relative shift in frequency and time owing to these effects can exceed 5×10-16.

  18. Storm-tide elevations produced by Hurricane Andrew along the southern Florida coasts, August 24, 1992

    USGS Publications Warehouse

    Murray, Mitchell H.

    1994-01-01

    On August 24, 1992, Hurricane Andrew crossed southern peninsular Florida. The combined effects of storm surge from the hurricane and astronomical tide, referred to as storm tide, caused flooding over a large part of southern Florida. Subsequent to the flooding, many high-water marks were identified, described, and surveyed along the south- eastern coast of Florida (Miami to Key Largo) and at selected areas along the southwestern coast of Florida (Flamingo to Goodland). Descriptions of these 336 high-water makrs are presented in tabular form in this report and their locations are plotted on nineteen 7.5-minute topographic quadrangle maps. For the southeastern coast, north-south profiles of the high-water makrs along the outher and inner barrier islands and the western shoreline of Biscayne Bay are presented. Average storm-tide elevations (relative to sea level) ranged from 4 to 6 feet in northern Biscayne Bay, were as much as 17 feet on the western shoreline near the center of the bay and ranged from 3 to 6 feet in southern Biscayne Bay and Barnes Sound. Storm-tide elevations along the southwestern coast ranged from 4 to 5 feet at Flamingo and 5 to 7 feet at Goodland in the Ten Thousand Islands area.

  19. Integration of coastal inundation modeling from storm tides to individual waves

    NASA Astrophysics Data System (ADS)

    Li, Ning; Roeber, Volker; Yamazaki, Yoshiki; Heitmann, Troy W.; Bai, Yefei; Cheung, Kwok Fai

    2014-11-01

    Modeling of storm-induced coastal inundation has primarily focused on the surge generated by atmospheric pressure and surface winds with phase-averaged effects of the waves as setup. Through an interoperable model package, we investigate the role of phase-resolving wave processes in simulation of coastal flood hazards. A spectral ocean wave model describes generation and propagation of storm waves from deep to intermediate water, while a non-hydrostatic storm-tide model has the option to couple with a spectral coastal wave model for computation of phase-averaged processes in a near-shore region. The ocean wave and storm-tide models can alternatively provide the wave spectrum and the surface elevation as the boundary and initial conditions for a nested Boussinesq model. Additional surface-gradient terms in the Boussinesq equations maintain the quasi-steady, non-uniform storm tide for modeling of phase-resolving surf and swash-zone processes as well as combined tide, surge, and wave inundation. The two nesting schemes are demonstrated through a case study of Hurricane Iniki, which made landfall on the Hawaiian Island of Kauai in 1992. With input from a parametric hurricane model and global reanalysis and tidal datasets, the two approaches produce comparable significant wave heights and phase-averaged surface elevations in the surf zone. The nesting of the Boussinesq model provides a seamless approach to augment the inundation due to the individual waves in matching the recorded debris line along the coast.

  20. Loss of Water in Early Earth's Atmosphere and Its Effects on Habitability

    NASA Astrophysics Data System (ADS)

    Airapetian, Vladimir; Glocer, Alex; Khazanov, George

    2015-08-01

    The short wavelength emission from the Sun has a profound impact on the Earth’s atmosphere. High energy photons ionize the atmosphere and produce photoelectrons. This process provides a major contribution to the acceleration of atmospheric ions due to the vertical separation of ions and electrons, and the formation of the resulting ambipolar electric field. Observations and theory suggest that even a relatively small fraction of super-thermal electrons (photoelectrons) produced due to photoionization can drive the ”polar wind” that is responsible for the transport of ionospheric constituents to the Earth’s magnetosphere.The young Sun was a magnetically active star generating powerful radiative output from its chromosphere, transition region and corona which was a few hundred times greater than that observed today. What effects would the photoionization processes due to the X-ray-UV solar flux from early Sun have on the loss of water from the early Earth?We use the Fokker-Plank code coupled with 1D hydrodynamic code to model the effect of intensive short-wavelength (X-rays to UV band) emission from the young Sun (3.8 and 4.4 Ga) on Earth's atmosphere. Our simulations include the photoionization processes of the Earth’s atmosphere forming a population of photoelectrons (E<600 eV), the kinetic effects of their propagation associated and their contribution in ionosphere - magnetosphere energy redistribution. Our coupled simulations show that the ambipolar electric field can drag atmospheric ions of oxygen and hydrogen to the magnetosphere and produce significant mass loss that can affect the loss of water from the early Earth in the first half a billion years. This process became less efficient in the next 0.2-0.3 Ga that could have provided a window of opportunity for origin of life.