Influence of tides and winds on fishing techniques and strategies in the Mamanguape River Estuary, Paraíba State, NE Brazil.

Science.gov (United States)

Bezerra, Dandara M M; Nascimento, Douglas M; Ferreira, Emmanoela N; Rocha, Pollyana D; Mourão, José S

2012-09-01

This work was carried out in two small fishing communities, Barra de Mamanguape and Tramataia, Northeastern Brazil. The aim was to study these traditional fishermen's knowledge and perception about tide and wind classifications, as well as their fishing strategies and techniques. Our research methodology involved various techniques: free interviews and semi-structured ones, guided tours and direct observations. The results obtained show the fishermen's classification of the tides according to the phases of the moon: 'breaking tide', 'flushing tide', 'dead tide' and 'big tide' designated technically these last as neap tide and spring tide, respectively. Wind is also an essential factor for the fishermen to make successful catches, and they classify it according to direction: North, South, East, Southeast, Southwest, Northeast and Northwest. The data show that fishermen's knowledge can also be useful in devising plans for management and conservation studies for this estuary.

The inverse problem: Ocean tides derived from earth tide observations

Science.gov (United States)

Kuo, J. T.

1978-01-01

Indirect mapping ocean tides by means of land and island-based tidal gravity measurements is presented. The inverse scheme of linear programming is used for indirect mapping of ocean tides. Open ocean tides were measured by the numerical integration of Laplace's tidal equations.

Springs-neaps cycles in daily total seabed light: Daylength-induced changes

Science.gov (United States)

Roberts, E. M.; Bowers, D. G.; Davies, A. J.

2014-04-01

In shallow, tidal seas, daily total seabed light is determined largely by the interaction of the solar elevation cycle, the tidal cycle in water depth, and any temporal variability in turbidity. Since tidal range, times of low water, and often turbidity vary in regular ways over the springs-neaps cycle, daily total seabed light exhibits cycles of the same periodicity. Corresponding cycles are likely to be induced in the daily total primary production of benthic algae and plants, particularly those light-limited specimens occupying the lower reaches of a sub-tidal population. Consequently, this effect is an important control on the growth patterns, depth distribution and survival of, for example, macroalgal forests and seagrass meadows. Seasonal changes in daylength exert an important additional control on these cycles, as they alter the fraction of the tidal and turbidity cycles occurring within daylight hours. Bowers et al. (1997) modelled this phenomenon numerically and predicted that for a site with low water at about midday and midnight at neaps tides, 6 am and 6 pm at springs, daily total seabed light peaks at neaps in winter, but the ‘sense' of the cycle ‘switches' so that it peaks at springs in summer - the longer daylength permits the morning and evening low water springs to contribute substantially to the daily total. Observations for such a site in North Wales (UK), presented in this paper, show that no such ‘switch' occurs, and neaps tides host the largest daily totals throughout the year. The predicted ‘switch' is not observed because turbidity increases generally at spring tides, and specifically at low water springs, both of which were not accounted for in the model. Observations at a second site in Brittany (France), diametrically opposite in terms of the times of low water at neaps and at springs, indicate a peak at springs throughout the year. Analytical tools are developed to calculate the percentage of daily total sea surface irradiance

Tides and Decadal Variability

Science.gov (United States)

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."

What Causes Tides?

Science.gov (United States)

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…

Molluscs production associated to lunar-tide cycle: a case study in Paraíba State under ethnoecology viewpoint

Directory of Open Access Journals (Sweden)

Alves Rômulo RN

2006-06-01

Full Text Available Abstract Molluscs have been for a long time a very important food resource for humans. Therefore, oysters, clams, and mussels are highly required at seafood markets. Like any commercial food, it is necessary that molluscs present good quality standards, concerning some criteria such as amount of meat and appearance. In bivalves, condition index or fattening index is considered a satisfactory method for estimating the amount of meat related to the shell cavity. Molluscs gatherers of Paraíba State coast, northeastern Brazil, state that molluscan meat production increases during spring tide (designated by them as maré de lançamento in opposition to the meat decrease which happens during neap tide (maré de quebramento (they are designated technically in Portuguese as maré de sizígia and maré de quadratura, respectively. Weperformed a survey on the production of unha-de-velho or 'oldman'snail' (Tagelus plebeius caught by molluscs gatherers in the estuary of River Paraíba do Norte, by observing locally their work, applying questionnaires, searching for a possible scientific relation of that molluscs condition to the gatherers empirical statement. Thus, we estimatedthe molluscs condition index through the method of solids percentage determination. We studied their work and the molluscs condition index during a full lunar-tide cycle. Determinations were carried out between 2nd September and 20th October, 1998, through 20 catches performed to obtain condition index from 400 bivalves. We observed that several biotic and abiotic ecological factors, namely reproduction cycle, biochemical components variations, animal size, and even parasitism, may affect the animal condition index. Despite this aspect, our present results confirmed a high overlapping (80% of the condition index curve with lunar-tide cycle, in agreement with the gatherers statement. Although we recognize the need for formulating and testing other hypotheses, we consider a priori that

Lunar tides in Loch Ness, Scotland

OpenAIRE

Pugh, David T.; Woodworth, Philip L.; Bos, Machiel S.

2011-01-01

Measurements have been made of the astronomical tide in Loch Ness, Scotland, which is not directly connected to marine tides. Our measurements of the loch tide are, so far as we know, the first in a European lake where the tide originates primarily from ocean tide loading. Loch Ness is a readily accessible lake and is in a region for which the neighboring ocean tides are large and described well by modern global ocean tide models. The principal tidal constituent, M2, was observed to have an a...

Condition of red tide appearance in Wakasa Bay based on Terra, Aqua/MODIS images

Science.gov (United States)

Aoyama, Takashi; Oya, Hiroshi

2006-12-01

Since June, 2004, studies on triggering factors of the red tide have been carried out in Awara Space Radio Observatory (ASRO), Fukui University of Technology utilizing directly received data of MODIS on the Terra and Aqua satellites which have been acquired in ASRO. Preliminary results of the data analyses for the period from July, 2001 to April, 2005 indicate conditions, for the appearance of the red tide bloom in Wakasa bay as follows: (1) the threshold amount of chlorophyll-a is close to 1.5mg/m 3, (2) the range of sea surface temperature (SST) is limited in a range from 12 to 20 °C and (3) the period of sunlit time in spring is also a significantly sensitive factor. We propose here to utilize MODIS band1 images corresponding to a red band with spatial resolution of 250m together with NDVI (Normalized Difference Vegetation Index) images which has also spatial resolution of 250m, for the confirmation of the red tide. The problem of coincidence between colored region due to SS (Suspended Sediment) and red tide region using only band1 of MODIS, has been solved by using NDVI images in addition to band1 images together as two dimensional diagram.

Tides and tsunamis

Science.gov (United States)

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.

Using an Altimeter-Derived Internal Tide Model to Remove Tides from in Situ Data

Science.gov (United States)

Zaron, Edward D.; Ray, Richard D.

2017-01-01

Internal waves at tidal frequencies, i.e., the internal tides, are a prominent source of variability in the ocean associated with significant vertical isopycnal displacements and currents. Because the isopycnal displacements are caused by ageostrophic dynamics, they contribute uncertainty to geostrophic transport inferred from vertical profiles in the ocean. Here it is demonstrated that a newly developed model of the main semidiurnal (M2) internal tide derived from satellite altimetry may be used to partially remove the tide from vertical profile data, as measured by the reduction of steric height variance inferred from the profiles. It is further demonstrated that the internal tide model can account for a component of the near-surface velocity as measured by drogued drifters. These comparisons represent a validation of the internal tide model using independent data and highlight its potential use in removing internal tide signals from in situ observations.

Tides in astronomy and astrophysics

CERN Document Server

Mathis, Stéphane; Tokieda, Tadashi

2013-01-01

Based on the lecture notes of a school titled ‘Tides in Astronomy and Astrophysics’ that brought together students and researchers, this book focuses on the fundamental theories of tides at different scales of the universe—from tiny satellites to whole galaxies—and on the most recent developments. It also attempts to place the study of tides in a historical perspective. Starting with a general tutorial on tides, the theme of tides is approached in 9 chapters from many directions. They allow non-experts to pick up a physical intuition and a sense of orders of magnitude in the theory of tides. These carefully prepared lecture notes by leaders in the field include many illustrative figures and drawings. Some even offer a variety of simple back-of the-envelope problems.

Explorers Presentation: Explaining the Tides to Children

OpenAIRE

Institute, Marine

2015-01-01

Explaining the tides to children Presentation includes information about: Orbits of the Earth, Moon and Sun; Moon phases and the lunar cycle; Gravity; Gravity and the tide; Types of tides; The tides and me!; Tide tables; Extra insight

Barometric Tides from ECMWF Operational Analyses

Science.gov (United States)

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.

Lunar tides in Loch Ness, Scotland

Science.gov (United States)

Pugh, David T.; Woodworth, Philip L.; Bos, Machiel S.

2011-11-01

Measurements have been made of the astronomical tide in Loch Ness, Scotland, which is not directly connected to marine tides. Our measurements of the loch tide are, so far as we know, the first in a European lake where the tide originates primarily from ocean tide loading. Loch Ness is a readily accessible lake and is in a region for which the neighboring ocean tides are large and described well by modern global ocean tide models. The principal tidal constituent, M2, was observed to have an amplitude of approximately 1.5 mm, and to be in antiphase, at each end of the loch. These values are in close agreement with the theoretical combined effects of the direct gravitational tide (body tide) and the tilt effects due to ocean tide loading, computed using Green's functions based on conventional elastic-Earth models. By analyzing over long periods for coherent tidal signals, we are able to significantly improve the signal-to-noise ratio in the tilt values compared with values obtained by direct level differencing. Our tilt accuracy of better than 10-8, measured over 35 km, demonstrates Loch Ness as one the world's longest and most accurate tiltmeters. Despite this unprecedented accuracy, Earth tidal models are still at least as accurate as our ability to measure them.

Comparison of calculated energy flux of internal tides with microstructure measurements

Directory of Open Access Journals (Sweden)

Saeed Falahat

2014-10-01

Full Text Available Vertical mixing caused by breaking of internal tides plays a major role in maintaining the deep-ocean stratification. This study compares observations of dissipation from microstructure measurements to calculations of the vertical energy flux from barotropic to internal tides, taking into account the temporal variation due to the spring-neap tidal cycle. The dissipation data originate from two surveys in the Brazil Basin Tracer Release Experiment (BBTRE, and one over the LArval Dispersal along the Deep East Pacific Rise (LADDER3, supplemented with a few stations above the North-Atlantic Ridge (GRAVILUCK and in the western Pacific (IZU. A good correlation is found between logarithmic values of energy flux and local dissipation in BBTRE, suggesting that the theory is able to predict energy fluxes. For the LADDER3, the local dissipation is much smaller than the calculated energy flux, which is very likely due to the different topographic features of BBTRE and LADDER3. The East Pacific Rise consists of a few isolated seamounts, so that most of the internal wave energy can radiate away from the generation site, whereas the Brazil Basin is characterised by extended rough bathymetry, leading to a more local dissipation. The results from all four field surveys support the general conclusion that the fraction of the internal-tide energy flux that is dissipated locally is very different in different regions.

On the role of tides and strong wind events in promoting summer primary production in the Barents Sea

Science.gov (United States)

Le Fouest, Vincent; Postlethwaite, Clare; Morales Maqueda, Miguel Angel; Bélanger, Simon; Babin, Marcel

2011-11-01

Tides and wind-driven mixing play a major role in promoting post-bloom productivity in subarctic shelf seas. Whether this is also true in the high Arctic remains unknown. This question is particularly relevant in a context of increasing Arctic Ocean stratification in response to global climatic change. We have used a three-dimensional ocean-sea ice-plankton ecosystem model to assess the contribution of tides and strong wind events to summer (June-August 2001) primary production in the Barents Sea. Tides are responsible for 20% (60% locally) of the post-bloom primary production above Svalbard Bank and east of the Kola Peninsula. By contrast, more than 9% of the primary production is due to winds faster than 8 m s -1 in the central Barents Sea. Locally, this contribution reaches 25%. In the marginal ice zone, both tides and wind events have only a limited effect on primary production (central Barents Sea), respectively. When integrated over all Barents Sea sub-regions, tides and strong wind events account, respectively, for 6.8% (1.55 Tg C; 1 Tg C=10 12 g C) and 4.1% (0.93 Tg C) of the post-bloom primary production (22.6 Tg C). To put this in context, this contribution to summer primary production is equivalent to the spring bloom integrated over the Svalbard area. Tides and winds are significant drivers of summer plankton productivity in the Barents Sea.

Biomass loss and nutrient redistribution in an Indonesian Thalassia hemprichii seagrass bed following seasonal low tide exposure during daylight

NARCIS (Netherlands)

Stapel, J.; Manuntun, R.; Hemminga, M.A.

1997-01-01

The intertidal reef flat of Barang Lompo Island, Indonesia, is exposed to air for several hours per day on the days around spring tides. The time of exposure shows a seasonal pattern. In the period January-June, the reef flat only runs dry at night, whereas in the period July-December, exposure only

New insights into ocean tide loading corrections on tidal gravity data in Canary Islands

Science.gov (United States)

Arnoso, J.; Benavent, M.; Bos, M. S.; Montesinos, F. G.

2009-04-01

The Canary Islands are an interesting area to investigate ocean tides loading effects due to the complex coastline of the islands and the varying bathymetry. We present here the quality of five recent global oceanic tidal models, GOT00.2, GOT4.7, FES2004, TPXO.7.1 and AG2006, by comparing their predicted ocean tide loading values with results from tidal gravity observations made on three islands, Lanzarote, Tenerife and El Hierro, for the four harmonic constituents O1, K1, M2 and S2. In order to improve the accuracy of the loading corrections on the gravity tide measurements, we have used the high resolution regional oceanic model CIAM2 to supplement the global models considered here. This regional model has been obtained by assimilating TOPEX/Poseidon altimetry at crossovers and along-track points and tide gauge observations into a hydrodynamic model. The model has a 5'Ã-5' resolution and covers the area between the coordinates 26°.5N to 30°.0N and 19°.0W to 12°.5W. The gravity tide observing sites have been occupied by three different LaCoste&Romberg (LCR) spring gravimeters during different periods of observation. We considered here the most recent gravity tide observations made with LCR Graviton-EG1194 in El Hierro Island, for a period of 6 months during 2008. In the case of Tenerife and Lanzarote sites we have used observation periods of 6 months and 8 years with LCR-G665 and LCR-G434 gravimeters, respectively. The last two sites have been revisited in order to improve the previous tidal analysis results. Thus, the gravity ocean tide loading corrections, based on the five global ocean tide models supplemented with the regional model CIAM2 allowed us to review the normalization factors (scale factor and phase lag) of both two gravimeters. Also, we investigated the discrepancies of the corrected gravimetric factors with the DDW elastic and inelastic non hydrostatic body tide model (Dehant et al., 1999). The lowest values are found for inelastic model in the

Atmospheric Tides in Gale Crater, Mars

Science.gov (United States)

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.

The lunar tide in sporadic E

Directory of Open Access Journals (Sweden)

R. J. Stening

1999-10-01

Full Text Available It seems that the wind shear theory is accepted for the explanation of sporadic E at mid and low latitudes. Some examples from Arecibo are displayed to show this. The effect of lunar tides should then modify the wind-shear theory in a manner that yields the observed features of the lunar tide in the critical frequency foEs and the height h'Es of the sporadic E. This is shown to imply that the phase of the lunar tide in h'Es should be the same as the phase of the lunar tide in the eastward wind and that the phase of the lunar tide in foEs is three hours later. Hourly values of foEs, f bEs (the blanketing critical frequency and h'Es from several observatories are analysed for the lunar semidiurnal tide. It is found that the phase of the tide in foEs is often about 3 hours later than for h'Es in agreement with the theory. Seasonal variations in the tide are also examined with the statistically most significant results (largest amplitudes usually occurring in summer. After reviewing the many difficulties associated with determining the lunar tide in Es, both experimentally and theoretically, the analysed phase results are compared with what might be expected from Hagan's global scale wave model. Agreement is only fair (a success rate of 69% among the cases examined but probably as good as might be expected.Key words. Ionosphere (ionosphere – atmosphere interactions – ionospheric irregularities, Meteorology and atmosphere dynamics (waves and tides

Ocean tides for satellite geodesy

Science.gov (United States)

Dickman, S. R.

1990-01-01

Spherical harmonic tidal solutions have been obtained at the frequencies of the 32 largest luni-solar tides using prior theory of the author. That theory was developed for turbulent, nonglobal, self-gravitating, and loading oceans possessing realistic bathymetry and linearized bottom friction; the oceans satisfy no-flow boundary conditions at coastlines. In this theory the eddy viscosity and bottom drag coefficients are treated as spatially uniform. Comparison of the predicted degree-2 components of the Mf, P1, and M2 tides with those from numerical and satellite-based tide models allows the ocean friction parameters to be estimated at long and short periods. Using the 32 tide solutions, the frequency dependence of tidal admittance is investigated, and the validity of sideband tide models used in satellite orbit analysis is examined. The implications of admittance variability for oceanic resonances are also explored.

Tides and tidal currents

NARCIS (Netherlands)

Roos, A.

1997-01-01

Basic phenomena, origin and generation of tides, analysis and prediction of tides, basic equation and types of long waves in one dimension, tidal propagation in one dimension, tidal propagation in two directions, analytical tidal computation, numerical tidal computation.

Hydraulic effects on nitrogen removal in a tidal spring-fed river

Science.gov (United States)

Hensley, Robert T.; Cohen, Matthew J.; Korhnak, Larry V.

2015-03-01

Hydraulic properties such as stage and residence time are important controls on riverine N removal. In most rivers, these hydraulic properties vary with stochastic precipitation forcing, but in tidal rivers, hydraulics variation occurs on a predictable cycle. In Manatee Springs, a highly productive, tidally influenced spring-fed river in Florida, we observed significant reach-scale N removal that varied in response to tidally driven variation in hydraulic properties as well as sunlight-driven variation in assimilatory uptake. After accounting for channel residence time and stage variation, we partitioned the total removal signal into assimilatory (i.e., plant uptake) and dissimilatory (principally denitrification) pathways. Assimilatory uptake was strongly correlated with primary production and ecosystem C:N was concordant with tissue stoichiometry of the dominant autotrophs. The magnitude of N removal was broadly consistent in magnitude with predictions from models (SPARROW and RivR-N). However, contrary to model predictions, the highest removal occurred at the lowest values of τ/d (residence time divided by depth), which occurred at low tide. Removal efficiency also exhibited significant counterclockwise hysteresis with incoming versus outgoing tides. This behavior is best explained by the sequential filling and draining of transient storage zones such that water that has spent the longest time in the storage zone, and thus had the most time for N removal, drains back into the channel at the end of an outgoing tide, concurrent with shortest channel residence times. Capturing this inversion of the expected relationship between channel residence time and N removal highlights the need for nonsteady state reactive transport models.

The pole tide in deep oceans

Science.gov (United States)

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.

Identification of Msf tide amplification using a network of spatially distributed tide gauges

Digital Repository Service at National Institute of Oceanography (India)

Joseph, A.; Mehra, P.; Sivadas, T.K.; Desai, R.G.P.; Srinivas, K.; Thottam, T.; Vijayan, P.R.; Revichandran, C.; Balachandran, K.K.

. Phys. Maths. Soc. Jpn., 3, 372-380. [17]. Noye, B.J., 1974. Tide-well systems I: Some non-linear effects of the conventional tide-well. J. Marine Res., 32 (2), 129-153. [18]. Picaut, J., and Verstraete, J.M., 1979. Propagation of a 14.7-day wave...

Changes in phytoplankton composition in response to tides, wind-induced mixing conditions, and freshwater outflows in an urbanised estuarine complex.

Science.gov (United States)

Moser, G A O; Ciotti, A M; Giannini, M F C; Tonini, R T; Harari, J

2012-02-01

Recent reports have shown an increase in potentially harmful phytoplankton in Santos bay (Southeastern Brazilian Coast), located in a highly urbanised estuarine complex. Prediction of blooms is, thus, essential but the phytoplankton community structure in very dynamic regions is difficult to determine. In the present work, we discriminate bloom forming microphytoplankton dominance and their relationship to physical and meteorological variables to look for patterns observed in different tides and seasons. Comparing 8 distinct situations, we found five scenarios of dominance that could be related to winds, tides and rainfall: i) Surfers, diatoms occurring during high surf zone energies; ii) Sinkers, represented by larger celled diatoms during spring tide, after periods of high precipitation rates; iii) Opportunistic mixers, composed of chain forming diatoms with small or elongate cells occurring during neap tides; iv) Local mixers, microplanktonic diatoms and dinoflagellates which occurred throughout the 298 sampling stations; and v) Mixotrophic dinoflagellates, after intense estuarine discharges. Results suggest alterations in the temporal patterns for some bloom-forming species, while others appeared in abundances above safe limits for public health. This approach can also illustrate possible impacts of changes in freshwater discharge in highly urbanised estuaries.

Galalctic Tides & the Sinusoidal Potential

Science.gov (United States)

Bartlett, David F.

2011-05-01

The sinusoidal potential is a nonNewtonian alternative to dark matter. Instead of φ = -GM/r we write φ = -(GM/r) cos kor, where ko= 2π/ λo and λo = Ro/20= 400 pc. Evidence for this choice for the "wavelength” λo has been given in one article and many previous meetings of the AAS & DDA. The solar system and nearby stars are trapped in a local groove of width Δr Quality (4 types) and semi-major axis aoriginal . For 10 of the 12 classes radial tides dominate Z-tides. The classic Oort cloud comets (1851-1996) have a particularly strong modulation with galactic longitude. This modulation is exactly in those directions where a radial tide would be important. The equally numerous recent Oort comets (1996-2008) show a different evidence for strong radial tides. The recent comets generally have much larger perihelion distances q than the classic ones. Here the evidence is that a radial tide is removing angular momentum from the orbit and thus bringing the perihelion closer to the earth and to observers.

Tide Predictions, California, 2014, NOAA

Data.gov (United States)

U.S. Environmental Protection Agency — The predictions from the web based NOAA Tide Predictions are based upon the latest information available as of the date of the user's request. Tide predictions...

Investigating tides, where does all the water go?

OpenAIRE

Institute, Marine

2013-01-01

Students will aim to complete a project investigating and researching tides. Each student should seek to develop an understanding of what causes tides and why sea levels change between high and low tide. Investigate and become familiar with tides as a natural feature in the local environment. Explore ways in which tides affect the behaviour of plants, animals and people.

Tides, the PIG, and 'warm' water

International Nuclear Information System (INIS)

Robertson, Robin

2010-01-01

The present rapid melting of the Pine Island Glacier (PIG) has been attributed to basal melting driven by the ocean. Specifically, this ocean melting is attributed to currents and tides pumping 'warm' Circumpolar Deep Water (CDW) into the ice shelf cavity. To identify tidal activity in the region, an observational time series of yo-yo CTD (Conductivity, Temperature, and Depth) data collected in the PIG outflow region was analyzed. The water column in front of the PIG consisted of two primary layers, a meltwater layer exiting the ice shelf cavity over a layer of CDW. Semidiurnal tides were present in both layers, with both the strength and direction of the tides differing between the two layers. The upper layer tides were stronger and directed in and out of the cavity, while the lower layer tides were primarily directed along the front of the cavity. Energy was found to be transferred from the semidiurnal tide to other frequencies and to be reflected by the ice shelf front. These mechanisms were most prominent at the interfaces between layers and indicate potential mixing between the layers. In conclusion, tides were found to contribute to the circulation into the ice shelf cavity and also to mixing of the exiting water, which influences pumping of the CDW into the ice shelf cavity and melting of the PIG.

Mapping Hurricane Rita inland storm tide

Science.gov (United States)

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.

Ocean tides from Seasat-A

Science.gov (United States)

Hendershott, M. C.; Munk, W. H.; Zetler, B. D.

1974-01-01

Two procedures for the evaluation of global tides from SEASAT-A altimetry data are elaborated: an empirical method leading to the response functions for a grid of about 500 points from which the tide can be predicted for any point in the oceans, and a dynamic method which consists of iteratively modifying the parameters in a numerical solution to Laplace tide equations. It is assumed that the shape of the received altimeter signal can be interpreted for sea state and that orbit calculations are available so that absolute sea levels can be obtained.

King Tides and Climate Change

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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.

Characteristics of Phytoplankton Biomass, Primary Production and Community Structure in the Modaomen Channel, Pearl River Estuary, with Special Reference to the Influence of Saltwater Intrusion during Neap and Spring Tides.

Science.gov (United States)

Zhou, Weihua; Gao, Jie; Liao, Jianzu; Shi, Ronggui; Li, Tao; Guo, Yajuan; Long, Aimin

2016-01-01

In recent decades, increasing frequency and intensity of saltwater intrusion in the Modaomen Channel has threatened the freshwater supply in the surrounding cities of the Pearl River Estuary, and ulteriorly changed the environmental conditions of the estuarine waters. Phytoplankton biomass, primary production (PP) and species composition, as well as hydrological and chemical parameters were examined along a downstream transect in the Modaomen Channel during neap tide (NT) and spring tide (ST), when a strong saltwater intrusion event occurred in late September, 2011. A total of 46 species phytoplankton were identified, including Bacillariophyta (25 species), Dinoflagellate (14 species), Chlorophyta (4 species), Cyanophyta (2 species) and Euglenozoa (1 species). The dominant species were shifted from freshwater diatoms (e.g., Melosira granulata and Melosira granulata var. angustissima) in the upper reaches to saline water diatoms (e.g., Skeletonema costatum and Coscinodiscus sp.) in the river mouth. Generally, phytoplankton density, biomass (chl-a) and PP decreased from the upper to lower reaches along the channel, and were significantly higher in NT than those of ST. There was a shift from large-sized phytoplankton (>20 μm) in the upper reaches to relative small-sized cells (5-20 μm) in the lower reaches. Compared to NT, low discharge and flow velocity, coupled with strong easterly winds during ST specially aggravated saltwater intrusion further to the upstream (~50 km from the estuary). The intruded saltwater diluted nutrients, N/P ratios, chl-a, and phytoplankton abundances, and thereby led to a decline in PP during ST.

Future Change to Tide-Influenced Deltas

Science.gov (United States)

Nienhuis, Jaap H.; Hoitink, A. J. F. (Ton); Törnqvist, Torbjörn E.

2018-04-01

Tides tend to widen deltaic channels and shape delta morphology. Here we present a predictive approach to assess a priori the effect of fluvial discharge and tides on deltaic channels. We show that downstream channel widening can be quantified by the ratio of the tide-driven discharge and the fluvial discharge, along with a second metric representing flow velocities. A test of our new theory on a selection of 72 deltas globally shows good correspondence to a wide range of environments, including wave-dominated deltas, river-dominated deltas, and alluvial estuaries. By quantitatively relating tides and fluvial discharge to delta morphology, we offer a first-order prediction of deltaic change that may be expected from altered delta hydrology. For example, we expect that reduced fluvial discharge in response to dam construction will lead to increased tidal intrusion followed by enhanced tide-driven sediment import into deltas, with implications for navigation and other human needs.

Energetics of global ocean tides from Geosat altimetry

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Cartwright, David E.; Ray, Richard D.

1991-01-01

The present paper focuses on resonance and energetics of the daily tides, especially in the southern ocean, the distribution of gravitational power input of daily and half-daily tides, and comparison with other estimates of global dissipation rates. The present global tidal maps, derived from Geosat altimetry, compare favorably with ground truth data at about the same rms level as the models of Schwiderski (1983), and are slightly better in lunar than in solar tides. Diurnal admittances clearly show Kelvin wave structure in the southern ocean and confirm the resonant mode of Platzman (1984) at 28.5 + or - 0.1 hr with an apparent Q of about 4. Driving energy is found to enter dominantly in the North Pacific for the daily tides and is strongly peaked in the tropical oceans for the half-daily tides. Global rates of working on all major tide constituents except S2 agree well with independent results from analyses of gravity through satellite tracking. Comparison at S2 is improved by allowing for the air tide in gravitational results but suggests deficiencies in all solar tide models.

On the salt transport in the Cananéia sea during a spring tide experiment

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Luiz Bruner de Miranda

1996-01-01

Full Text Available Observations of the velocity, salinity, water depths and tides in the southem region of the Cananéia Sea were sampled at an anchored station during two complete tidal cycles. The measurements were made during spring tides on 5-6 December, 1991. The observed non-tidal current profile for this weakly stratified tidal channel is found to be in close agreement with the results of a simple steady state unidimensional analytical model of a well-nuxed estuary. This comparison indicates that the primary driving mechanisms are the longitudinal salinity gradient and the fresh water discharge. The contribution to the advective salt transport is dominateô by the freshwater discharge through the down-stream non-tidal flow and the up-stream dispersive term due to Stokes wave transporto This dispersive term is almost one order of magnitude smaller than the down-stream non-tidãl transport inôuced bythe fresh water discharge. TidaI correlation, acting as a counter-dispersion term, and the steady shear dispersion term are two orders of magnitude smaller than the ôown-stream salt transporto The remaining dispersive terms, which are dependent on the deviations from the mean deptb, are smaller than eitlier of these terms by one order of magnitude. The computed total salt transport per unit width of a section perpendicular to the mean flow was in close agreement (within 12 % with the sum of the individual advective and dispersive terms. On the assumption that the tidal channel sampled is laterally homogeneous, an imoalance of the salt budget across the section was observed.Observações de velocidade, de salinidade, de profundidade e de maré na região sul do Mar de Cananéia foram realizadas numa estação fixa durante dois ciclos completos de maré. Essas medidas foram feitas durante maré de sizígia, no período de 5 a 6 de dezem6ro de 1991. A exame comparativo do perfil estacionário de velocidade desse sistema fracamente estratificado, indicou boa concord

The Global S$_1$ Ocean Tide

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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.

Propagation Velocity of Solid Earth Tides

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Pathak, S.

2017-12-01

One of the significant considerations in most of the geodetic investigations is to take into account the outcome of Solid Earth tides on the location and its consequent impact on the time series of coordinates. In this research work, the propagation velocity resulting from the Solid Earth tides between the Indian stations is computed. Mean daily coordinates for the stations have been computed by applying static precise point positioning technique for a day. The computed coordinates are used as an input for computing the tidal displacements at the stations by Gravity method along three directions at 1-minute interval for 24 hours. Further the baseline distances are computed between four Indian stations. Computation of the propagation velocity for Solid Earth tides can be done by the virtue of study of the concurrent effect of it in-between the stations of identified baseline distance along with the time consumed by the tides for reaching from one station to another. The propagation velocity helps in distinguishing the impact at any station if the consequence at a known station for a specific time-period is known. Thus, with the knowledge of propagation velocity, the spatial and temporal effects of solid earth tides can be estimated with respect to a known station. As theoretically explained, the tides generated are due to the position of celestial bodies rotating about Earth. So the need of study is to observe the correlation of propagation velocity with the rotation speed of the Earth. The propagation velocity of Solid Earth tides comes out to be in the range of 440-470 m/s. This velocity comes out to be in a good agreement with the Earth's rotation speed.

Precise Comparisons of Bottom-Pressure and Altimetric Ocean Tides

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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.

Precise comparisons of bottom-pressure and altimetric ocean tides

Science.gov (United States)

Ray, R. D.

2013-09-01

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 core-nutation 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.

Shellfish Aquaculture from Space: Potential of Sentinel2 to Monitor Tide-Driven Changes in Turbidity, Chlorophyll Concentration and Oyster Physiological Response at the Scale of an Oyster Farm

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Pierre Gernez

2017-05-01

Full Text Available The algorithms of Novoa et al. (2017 and Gons et al. (2005 were recalibrated and applied to Sentinel2 data to retrieve suspended particulate matter (SPM and chlorophyll a (chl a concentration in the environmentally and economically important intertidal zones. Sentinel2-derived chl a and SPM concentration distributions were analyzed at the scale of an oyster farm over a variety of tidal conditions. Sentinel2 imagery was then coupled with ecophysiological modeling to analyze the influence of tide-driven chl a and SPM dynamics on oyster clearance and chl consumption rates. Within the studied oyster farming site (Bourgneuf Bay along the French Atlantic coast, chl consumption rate mirrored the changes in chl a concentration during neap tides, whereas oyster clearance and chl consumption rates were both negatively impacted by high SPM concentration during spring tides.

Shallow-water loading tides in Japan from superconducting gravimetry

DEFF Research Database (Denmark)

Khan, Shfaqat Abbas; Hoyer, J.L.

2004-01-01

energetic constituents in the tide gauge observations are also seen in the gravity observations due to their loading effects on the deformation of the Earth. Even though the shallow-water tides at the Japanese east coast have an amplitude of only a few millimetres. they are still able to Generate a loading...... signal at gravity sites located several hundred kilometres inland. In particular, the S-3, S-4 and S-5 solar tides occur in both gravity and tide gauge observations. It is indicated that in other shelf regions with large shallow water tides, the shallow water loading signals account for a significant...

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

Science.gov (United States)

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.

Ocean Tide Loading Computation

Science.gov (United States)

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.

Fortnightly Ocean Tides, Earth Rotation, and Mantle Anelasticity

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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.

Dynamic ocean-tide effects on Earth's rotation

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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.

The magnetic tides of Honolulu

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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.

Multimission empirical ocean tide modeling for shallow waters and polar seas

DEFF Research Database (Denmark)

Cheng, Yongcun; Andersen, Ole Baltazar

2011-01-01

A new global ocean tide model named DTU10 (developed at Technical University of Denmark) representing all major diurnal and semidiurnal tidal constituents is proposed based on an empirical correction to the global tide model FES2004 (Finite Element Solutions), with residual tides determined using...... tide gauge sets show that the new tide model fits the tide gauge measurements favorably to other state of the art global ocean tide models in both the deep and shallow waters, especially in the Arctic Ocean and the Southern Ocean. One example is a comparison with 207 tide gauge data in the East Asian...... marginal seas where the root-mean-square agreement improved by 35.12%, 22.61%, 27.07%, and 22.65% (M-2, S-2, K-1, and O-1) for the DTU10 tide model compared with the FES2004 tide model. A similar comparison in the Arctic Ocean with 151 gauge data improved by 9.93%, 0.34%, 7.46%, and 9.52% for the M-2, S-2...

Geodynamic Effects of Ocean Tides: Progress and Problems

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Richard, Ray

1999-01-01

Satellite altimetry, particularly Topex/Poseidon, has markedly improved our knowledge of global tides, thereby allowing significant progress on some longstanding problems in geodynamics. This paper reviews some of that progress. Emphasis is given to global-scale problems, particularly those falling within the mandate of the new IERS Special Bureau for Tides: angular momentum, gravitational field, geocenter motion. For this discussion I use primarily the new ocean tide solutions GOT99.2, CSR4.0, and TPXO.4 (for which G. Egbert has computed inverse-theoretic error estimates), and I concentrate on new results in angular momentum and gravity and their solid-earth implications. One example is a new estimate of the effective tidal Q at the M_2 frequency, based on combining these ocean models with tidal estimates from satellite laser ranging. Three especially intractable problems are also addressed: (1) determining long-period tides in the Arctic [large unknown effect on the inertia tensor, particularly for Mf]; (2) determining the global psi_l tide [large unknown effect on interpretations of gravimetry for the near-diurnal free wobble]; and (3) determining radiational tides [large unknown temporal variations at important frequencies]. Problems (2) and (3) are related.

Measurement of the Earth tides with a MEMS gravimeter.

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

2016-03-31

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 hertz(1/2)): 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 hertz(1/2) 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.

Impact of sea level rise on tide gate function.

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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.

Influence of tides and winds on fishing techniques and strategies in the Mamanguape River Estuary, Paraíba State, NE Brazil

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Dandara M.M. Bezerra

2012-09-01

Full Text Available This work was carried out in two small fishing communities, Barra de Mamanguape and Tramataia, Northeastern Brazil. The aim was to study these traditional fishermen's knowledge and perception about tide and wind classifications, as well as their fishing strategies and techniques. Our research methodology involved various techniques: free interviews and semi-structured ones, guided tours and direct observations. The results obtained show the fishermen's classification of the tides according to the phases of the moon: 'breaking tide', 'flushing tide', 'dead tide' and 'big tide' designated technically these last as neap tide and spring tide, respectively. Wind is also an essential factor for the fishermen to make successful catches, and they classify it according to direction: North, South, East, Southeast, Southwest, Northeast and Northwest. The data show that fishermen's knowledge can also be useful in devising plans for management and conservation studies for this estuary.Este trabalho foi desenvolvido junto a duas comunidades de pescadores artesanais: Barra de Mamanguape e Tramataia, Nordeste do Brasil. O objetivo foi estudar o conhecimento e a percepção dos pescadores artesanais sobre a classificação das marés e dos ventos bem como as técnicas e estratégias de pesca. A metodologia empregada envolveu várias técnicas: entrevistas livres, entrevistas semiestruturadas, turnês guiadas e observação direta. Os resultados obtidos junto aos pescadores mostraram a classificação das marés de acordo com as fases lunares em: 'maré de quebramento', 'maré de lançamento', 'maré morta' e 'maré grande', designadas tecnicamente estas últimas como maré de quadratura e maré de sizígia, respectivamente. O vento é também um fator essencial no sucesso da pescaria, eles o classificam de acordo com a direção: Norte, Sul, Leste, Sudeste, Sudoeste, Nordeste, Noroeste. Os dados obtidos nesta pesquisa mostraram que o conhecimento dos pescadores

Statistical selection of tide gauges for Arctic sea-level reconstruction

DEFF Research Database (Denmark)

Svendsen, Peter Limkilde; Andersen, Ole Baltazar; Nielsen, Allan Aasbjerg

2015-01-01

In this paper, we seek an appropriate selection of tide gauges for Arctic Ocean sea-level reconstruction based on a combination of empirical criteria and statistical properties (leverages). Tide gauges provide the only in situ observations of sea level prior to the altimetry era. However, tide...... the "influence" of each Arctic tide gauge on the EOF-based reconstruction through the use of statistical leverage and use this as an indication in selecting appropriate tide gauges, in order to procedurally identify poor-quality data while still including as much data as possible. To accommodate sparse...

Fortnightly Earth Rotation, Ocean Tides, and Mantle Anelasticity

Science.gov (United States)

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.

Performance of modern tide gauges: towards mm-level accuracy

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Belén Martín Míguez

2012-09-01

Full Text Available Considerable efforts are being made worldwide to upgrade tide gauge networks using new technologies. Because of the unique location of the Kerguelen Islands, the measurement of sea level there has received particular attention, with up to four systems equipped with modern sensors functioning simultaneously (two pressure tide gauges, a radar tide gauge, and a GPS-equipped buoy. We analysed and compared the sea level data obtained with these systems from 2003 to 2010, together with a time series of tide pole observations. This is the first time that a multi-comparison study with tide gauges has been undertaken over such a long time span and that the stability of modern radar tide gauges has been examined. The multi-comparison enabled us to evaluate the performance of the tide gauges in several frequency ranges, identify errors and estimate their magnitude. The drift of the pressure sensors (up to 8.0 mm/yr was found to be one of the most relevant sources of systematic error. Other sources of difference such as clock drift, scale error and different locations of the instruments were also detected. After correcting the time series of sea level for these errors we estimated an upper bound for the radar instrumental error in field condition at ~0.3 cm.

The killer tides

Digital Repository Service at National Institute of Oceanography (India)

Devassy, V.P.; Bhat, S.R.

. Various measures adopted to control or contain such harmful events have either proved ineffective or are economically unviable. Red tides generally break out under favourable environmental conditions such as calm, sunny weather and gently breeze or when...

Tidal variability of nutrients in a coastal coral reef system influenced by groundwater

Science.gov (United States)

Wang, Guizhi; Wang, Shuling; Wang, Zhangyong; Jing, Wenping; Xu, Yi; Zhang, Zhouling; Tan, Ehui; Dai, Minhan

2018-02-01

To investigate variation in nitrite, nitrate, phosphate, and silicate in a spring-neap tide in a coral reef system influenced by groundwater discharge, we carried out a time-series observation of these nutrients and 228Ra, a tracer of groundwater discharge, in the Luhuitou fringing reef at Sanya Bay in the South China Sea. The maximum 228Ra, 45.3 dpm 100 L-1, appeared at low tide and the minimum, 14.0 dpm 100 L-1, appeared during a flood tide in the spring tide. The activity of 228Ra was significantly correlated with water depth and salinity in the spring-neap tide, reflecting the tidal-pumping feature of groundwater discharge. Concentrations of all nutrients exhibited strong diurnal variation, with a maximum in the amplitude of the diel change for nitrite, nitrate, phosphate, and silicate in the spring tide of 0.46, 1.54, 0.12, and 2.68 µM, respectively. Nitrate and phosphate were negatively correlated with water depth during the spring tide but showed no correlation during the neap tide. Nitrite was positively correlated with water depth in the spring and neap tide due to mixing of nitrite-depleted groundwater and nitrite-rich offshore seawater. They were also significantly correlated with salinity (R2 ≥ 0.9 and P reef system was closely related with biological processes during both tidal periods, but the biological influence appeared to be less dominant, as inferred from the less significant correlations (R2 = 0.16) during the spring tide when groundwater discharge was more prominent. Thus, the variability of nutrients in the coral reef system was regulated mainly by biological uptake and release in a spring-neap tide and impacted by mixing of tidally driven groundwater and offshore seawater during spring tide.

Global ocean tide models on the eve of Topex/Poseidon

Science.gov (United States)

Ray, Richard D.

1993-01-01

Some existing global ocean tide models that can provide tide corrections to Topex/Poseidon altimeter data are described. Emphasis is given to the Schwiderski and Cartwright-Ray models, as these are the most comprehensive, highest resolution models, but other models that will soon appear are mentioned. Differences between models for M2 often exceed 10 cm over vast stretches of the ocean. Comparisons to 80 selected pelagic and island gauge measurements indicate the Schwiderski model is more accurate for the major solar tides, Cartwright-Ray for the major lunar tides. The adequacy of available tide models for studying basin-scale motions is probably marginal at best.

Can neap-spring tidal cycles modulate biogeochemical fluxes in the abyssal near-seafloor water column?

Science.gov (United States)

Turnewitsch, Robert; Dale, Andrew; Lahajnar, Niko; Lampitt, Richard S.; Sakamoto, Kei

2017-05-01

Before particulate matter that settles as 'primary flux' from the interior ocean is deposited into deep-sea sediments it has to traverse the benthic boundary layer (BBL) that is likely to cover almost all parts of the seafloor in the deep seas. Fluid dynamics in the BBL differ vastly from fluid dynamics in the overlying water column and, consequently, have the potential to lead to quantitative and compositional changes between primary and depositional fluxes. Despite this potential and the likely global relevance very little is known about mechanistic and quantitative aspects of the controlling processes. Here, results are presented for a sediment-trap time-series study that was conducted on the Porcupine Abyssal Plain in the abyssal Northeast Atlantic, with traps deployed at 2, 40 and 569 m above bottom (mab). The two bottommost traps were situated within the BBL-affected part of the water column. The time series captured 3 neap and 4 spring tides and the arrival of fresh settling material originating from a surface-ocean bloom. In the trap-collected material, total particulate matter (TPM), particulate inorganic carbon (PIC), biogenic silica (BSi), particulate organic carbon (POC), particulate nitrogen (PN), total hydrolysable amino acids (AA), hexosamines (HA) and lithogenic material (LM) were determined. The biogeochemical results are presented within the context of time series of measured currents (at 15 mab) and turbidity (at 1 mab). The main outcome is evidence for an effect of neap/spring tidal oscillations on particulate-matter dynamics in BBL-affected waters in the deep sea. Based on the frequency-decomposed current measurements and numerical modelling of BBL fluid dynamics, it is concluded that the neap/spring tidal oscillations of particulate-matter dynamics are less likely due to temporally varying total free-stream current speeds and more likely due to temporally and vertically varying turbulence intensities that result from the temporally varying

Orthogonal stack of global tide gauge sea level data

Science.gov (United States)

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.

The IERS Special Bureau for Tides

Science.gov (United States)

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.

Tide-surge interaction in the English Channel

Directory of Open Access Journals (Sweden)

D. Idier

2012-12-01

Full Text Available The English Channel is characterised by strong tidal currents and a wide tidal range, such that their influence on surges is expected to be non-negligible. In order to better assess storm surges in this zone, tide-surge interactions are investigated. A preliminary data analysis on hourly surges indicates some preferential times of occurrence of large storm surges at rising tide, especially in Dunkerque. To examine this further, a numerical modelling approach is chosen, based on the 2DH shallow-water model (MARS. The surges are computed both with and without tide interaction. For the two selected events (the November 2007 North Sea and March 2008 Atlantic storms, it appears that the instantaneous tide-surge interaction is seen to be non-negligible in the eastern half of the English Channel, reaching values of 74 cm (i.e. 50% of the same event maximal storm surge in the Dover Strait for the studied cases. This interaction decreases in westerly direction. In the risk-analysis community in France, extreme water levels have been determined assuming skew surges and tide as independent. The same hydrodynamic model is used to investigate this dependence in the English Channel. Simple computations are performed with the same meteorological forcing, while varying the tidal amplitude, and the skew surge differences D_SS are analysed. Skew surges appear to be tide-dependent, with negligible values of D_SS (<0.05 m over a large portion of the English Channel, although reaching several tens of centimetres in some locations (e.g. the Isle of Wight and Dover Strait.

Lunar tidal acceleration obtained from satellite-derived ocean tide parameters

Science.gov (United States)

Goad, C. C.; Douglas, B. C.

1978-01-01

One hundred sets of mean elements of GEOS-3 computed at 2-day intervals yielded observation equations for the M sub 2 ocean tide from the long periodic variations of the inclination and node of the orbit. The 2nd degree Love number was given the value k sub 2 = 0.30 and the solid tide phase angle was taken to be zero. Combining obtained equations with results for the satellite 1967-92A gives the M sub 2 ocean tide parameter values. Under the same assumption of zero solid tide phase lag, the lunar tidal acceleration was found mostly due to the C sub 22 term in the expansion of the M sub 2 tide with additional small contributions from the 0 sub 1 and N sub 2 tides. Using Lambeck's (1975) estimates for the latter, the obtained acceleration in lunar longitudal in excellent agreement with the most recent determinations from ancient and modern astronomical data.

Tides at the east coast of Lanzarote Island

Science.gov (United States)

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

Tide-surge Interaction Intensified by the Taiwan Strait

Science.gov (United States)

Zhang, Wen-Zhou; Shi, Fengyan; Hong, Hua-Sheng; Shang, Shao-Ping; Kirby, James T.

2010-06-01

The Taiwan Strait is a long and wide shelf-channel where the hydrodynamics is extremely complex, being characterized by strong tides, and where storm surges frequently occur during the typhoon season. Obvious oscillations due to tide-surge interaction were observed by tide gauges along the northern Fujian coast, the west bank of the Taiwan Strait, during Typhoon Dan (1999). Numerical experiments indicate that nonlinear bottom friction (described by the quadratic formula) is a major factor to predict these oscillations while the nonlinear advective terms and the shallow water effect have little contribution. It is found that the tide-surge interaction in the northern portion of the Taiwan Strait is intensified by the strait. Simulations based on simplified topographies with and without the island of Taiwan show that, in the presence of the island, the channel effect strengthens tidal currents and tends to align the major axes of tidal ellipses along the channel direction. Storm-induced currents are also strengthened by the channel. The pattern of strong tidal currents and storm-induced currents along the channel direction enhances tide-surge interaction via the nonlinear bottom friction, resulting in the obvious oscillations along the northern Fujian coast.

Sea level reconstruction from satellite altimetry and tide gauge data

DEFF Research Database (Denmark)

Svendsen, Peter Limkilde; Andersen, Ole Baltazar; Nielsen, Allan Aasbjerg

2012-01-01

Ocean satellite altimetry has provided global sets of sea level data for the last two decades, allowing determination of spatial patterns in global sea level. For reconstructions going back further than this period, tide gauge data can be used as a proxy. We examine different methods of combining...... for better sensitivity analysis with respect to spatial distribution, and tide gauge data are available around the Arctic Ocean, which may be important for a later high-latitude reconstruction....... satellite altimetry and tide gauge data using optimal weighting of tide gauge data, linear regression and EOFs, including automatic quality checks of the tide gauge time series. We attempt to augment the model using various proxies such as climate indices like the NAO and PDO, and investigate alternative...

Ocean tide models for satellite geodesy and Earth rotation

Science.gov (United States)

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).

Non-Migrating Tides, with Zonally Symmetric Component, Generated in the Mesosphere

Science.gov (United States)

Mayr, H. G.; Mengel, J. G.; Talaat, E. R.; Porter, H. S.; Hines, C. O.

2003-01-01

For comparison with measurements from the TIMED satellite and coordinated ground based observations, we discuss results from our Numerical Spectral Model (NSM) that incorporates the Doppler Spread Parameterization (Hines, 1997) for small-scale gravity waves (GWs). The NSM extends from the ground into the thermosphere and describes the major dynamical features of the atmosphere including the wave driven equatorial oscillations (QBO and SAO), and the seasonal variations of tides and planetary waves. With emphasis on the non-migrating tides, having periods of 24 and 12 hours, we discuss our modeling results that account for the classical migrating solar excitation sources only. As reported earlier, the NSM reproduces the observed seasonal variations and in particular the large equinoctial maxima in the amplitude of the migrating diurnal tide at altitudes around 90 km. Filtering of the tide by the zonal circulation and GW momentum deposition was identified as the cause. The GWs were also shown to produce a strong non-linear interaction between the diurnal and semi-diurnal tides. Confined largely to the mesosphere, the NSM produces through dynamical interactions a relatively large contribution of non-migrating tides. A striking feature is seen in the diurnal and semi-diurnal oscillations of the zonal mean (m = 0). Eastward propagating tides are also generated for zonal wave numbers m = 1 to 4. When the NSM is run without GWs, the amplitudes for the non-migrating tides, including m = 0, are generally small. Planetary wave interaction and non-linear coupling that involves the filtering of GWs and related height integration of dynamical features are discussed as possible mechanisms for generating these non-migrating tides in the NSM. As is the case for the solar migrating tides, the non-migrating tides reveal persistent seasonal variations. Under the influence of the QBO and SAO, interannual variations are produced.

Dynamic Tides and the Evolution of Stars in Close Binaries

OpenAIRE

Willems, B.; Claret, A.

2004-01-01

In this talk, we review some recent advances in the theory of dynamic tides in close binaries. We particularly focus on the effects of resonances of dynamic tides with free oscillation modes and on the role of dynamic tides in the comparison of theoretically predicted and observationally inferred apsidal-motion rates.

A fast-response shallow-water tide gauge

International Nuclear Information System (INIS)

Cavaleri, L.; Curiotto, S.

1979-01-01

The authors describe the characteristics of a fast-response tide gauge suitable for shallow-water conditions. Its time constant is of the order of minutes. Wind waves are filtered better than 99% in the (0/10) s interval. The tide gauge has now been operative for three years on an oceanographic tower in the open sea. (author)

NONLINEAR TIDES IN CLOSE BINARY SYSTEMS

International Nuclear Information System (INIS)

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

2012-01-01

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' ∼> 10-100 M ⊕ at orbital periods P ≈ 1-10 days. The nearly static 'equilibrium' tidal distortion is, however, stable to parametric resonance except for solar binaries with P ∼ 3 [P/10 days] for a solar-type star) and drives them as a single coherent unit with growth rates that are a factor of ≈N faster than the standard three-wave parametric instability. These are local instabilities viewed through the lens of global analysis; the coherent global growth rate follows local rates in the regions where the shear is strongest. In solar-type stars, the dynamical tide is unstable to this collective version of the parametric instability for even sub-Jupiter companion masses with P ∼< a month. (4) Independent of the parametric instability, the dynamical and equilibrium tides excite a wide range of stellar p-modes and g-modes by nonlinear inhomogeneous forcing

Storm Surge and Tide Interaction: A Complete Paradigm

Science.gov (United States)

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

Lake-level variations and tides in Lago Argentino, Patagonia: insights from pressure tide gauge records

Directory of Open Access Journals (Sweden)

Andreas Richter

2015-08-01

Full Text Available Based on precise pressure tide gauge observations lake-level records are derived for two sites in Lago Argentino, southern Patagonia, of 2.5 and 1 years of duration. Applying the tools of time series analysis, 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 of 1.2 m in amplitude. Lake-volume changes occur in addition with a daily period in response to melt water influx from surrounding glaciers. Sporadic lake-volume jumps are caused by bursting of the ice dam of Perito Moreno glacier. Water movements in Lago Argentino are dominated by surface seiches reaching 20 cm in amplitude. Lake tides reach a maximum amplitude of 3 mm. The comparison of the tidal signal extracted from the lake-level observations with a model composed of the contributions of body tide and ocean tidal loading indicates a phase shift of 23° which is most likely explained by an 1 hour phase lag of global ocean tide models in the region of the highly fragmented Pacific coast. The comparison of the obtained results with those of a previous study of Lago Fagnano, Tierra del Fuego, allows to relate differences in the hydrological and hydrodynamic processes between both lakes to morphological properties. This leads to a tentative prediction of the lake-level variability to be expected from other great Patagonian lakes. The presented geodetic results shall serve as a starting point for a detailed limnological investigation of these aquatic ecosystems.

Influence analysis of Arctic tide gauges using leverages

DEFF Research Database (Denmark)

Svendsen, Peter Limkilde; Andersen, Ole Baltazar; Nielsen, Allan Aasbjerg

2014-01-01

a calibration period, in this preliminary case Drakkar ocean model data, which are forced using historical tide gauge data from the PSMSL database. The resulting leverage for each tide gauge may indicate that it represents a distinct mode of variability, or that its time series is perturbed in a way......Reconstructions of historical sea level in the Arctic Ocean are fraught with difficulties related to lack of data, uneven distribution of tide gauges and seasonal ice cover. Considering the period from 1950 to the present, we attempt to identify conspicuous tide gauges in an automated way, using...... the statistical leverage of each individual gauge. This may be of help in determining appropriate procedures for data preprocessing, of particular importance for the Arctic area as the GIA is hard to constrain and many gauges are located on rivers. We use a model based on empirical orthogonal functions from...

Characterizations of geothermal springs along the Moxi deep fault in the western Sichuan plateau, China

Science.gov (United States)

Qi, Jihong; Xu, Mo; An, Chengjiao; Wu, Mingliang; Zhang, Yunhui; Li, Xiao; Zhang, Qiang; Lu, Guoping

2017-02-01

Abundant geothermal springs occur along the Moxi fault located in western Sichuan Province (the eastern edge of the Qinghai-Tibet plateau), highlighted by geothermal water outflow with an unusually high temperature of 218 °C at 21.5 MPa from a 2010-m borehole in Laoyulin, Kangding. Earthquake activity occurs relatively more frequently in the region and is considered to be related to the strong hydrothermal activity. Geothermal waters hosted by a deep fault may provide evidence regarding the deep underground; their aqueous chemistry and isotopic information can indicate the mechanism of thermal springs. Cyclical variations of geothermal water outflows are thought to work under the effect of solid earth tides and can contribute to understanding conditions and processes in underground geo-environments. This paper studies the origin and variations of the geothermal spring group controlled by the Moxi fault and discusses conditions in the deep ground. Flow variation monitoring of a series of parameters was performed to study the geothermal responses to solid tides. Geothermal reservoir temperatures are evaluated with Na-K-Mg data. The abundant sulfite content, dissolved oxygen (DO) and oxidation-reduction potential (ORP) data are discussed to study the oxidation-reduction states. Strontium isotopes are used to trace the water source. The results demonstrate that geothermal water could flow quickly through the Moxi fault the depth of the geothermal reservoir influences the thermal reservoir temperature, where supercritical hot water is mixed with circulating groundwater and can reach 380 °C. To the southward along the fault, the circulation of geothermal waters becomes shallower, and the waters may have reacted with metamorphic rock to some extent. Our results provide a conceptual deep heat source model for geothermal flow and the reservoir characteristics of the Moxi fault and indicate that the faulting may well connect the deep heat source to shallower depths. The

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

Science.gov (United States)

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.

Internal tides and deep diel fades in acoustic intensity.

Science.gov (United States)

White, Andrew W; Henyey, Frank S; Andrew, Rex K; Mercer, James A; Worcester, Peter F; Dzieciuch, Matthew A; Colosi, John A

2016-11-01

A mechanism is presented by which the observed acoustic intensity is made to vary due to changes in the acoustic path that are caused by internal-tide vertical fluid displacements. The position in range and depth of large-scale caustic structure is determined by the background sound-speed profile. Internal tides cause a deformation of the background profile, changing the positions of the caustic structures-which can introduce intensity changes at a distant receiver. Gradual fades in the acoustic intensity occurring over timescales similar to those of the tides were measured during a low-frequency (284-Hz) acoustic scattering experiment in the Philippine Sea in 2009 [White et al., J. Acoust. Soc. Am. 134(4), 3347-3358 (2013)]. Parabolic equation and Hamiltonian ray-tracing calculations of acoustic propagation through a plane-wave internal tide environmental model employing sound-speed profiles taken during the experiment indicate that internal tides could cause significant gradual changes in the received intensity. Furthermore, the calculations demonstrate how large-scale perturbations to the index of refraction can result in variation in the received intensity.

Annual Variation and Global Structures of The DE3 Tide

International Nuclear Information System (INIS)

Ze-Yu, Chen; Da-Ren, Lu

2008-01-01

The SABER/TIMED temperatures taken in 2002–2006 are used to delineate the tidal signals in the middle and upper atmosphere. Then the Hough mode decomposition is applied with the DE3 tide, and the overall features of the seasonal variations and the complete global structures of the tide are observed. Investigation results show that the tide is most prominent at 110 km with the maximal amplitude of > 9K, and exhibits significant seasonal variation with its maximum amplitude always occurring in July every year. Results from the Hough mode decomposition reveal that the tide is composed primarily of two leading propagating Hough modes, i.e., the (−3,3) and the (−3,4) modes, thus is equatorially trapped. Estimation of the mean amplitude of the Hough modes show that the (−3,3) mode and (−3,4) mode exhibit maxima at 110km and 90 km, respectively. The (−3,3) mode plays a predominant role in shaping the global latitude-height structure of the tide, e.g., the vertical scale of > 50km at the equator, and the annual course. Significant influence of the (−3,4) mode is found below 90km, where the tide exhibits anti-symmetric structure about the equator; meanwhile the tide at northern tropical latitudes exhibits smaller vertical wavelength of about 30 km. (geophysics, astronomy, and astrophysics)

Aquifer response to earth tides

International Nuclear Information System (INIS)

Kanehiro, B.Y.; Narasimhan, T.N.

1981-01-01

The relation presented in the first part of this paper are applicable to packed-off wells and other situations where appreciable flow to the well does not exist. Comparisons of aquifer properties determined from the response to earth tides and from the more standard pumping tests for the two California fields are reasonably good. The case of an open well makes the problem more complicated, since there may be an appreciable amount of flow to the well. This flow to the well is seen as either a phase lag or as a difference in the ratio of the well signal to the tide for the semidiurnal and diurnal components of the tide. The latter is probably the better and more accurate indicator of flow to the well. Analyses of such situations, however, become involved and are probably best done as case-by-case studies. The numerical solutions show that treating the inverse problem through numerical modeling is at least feasible for any individual situation. It may be possible to simplify the inverse problem through the generation of type curves, but general type curves that are applicable to diverse situations are not likely to be practical. 7 figures

Construction of Green Tide Monitoring System and Research on its Key Techniques

Science.gov (United States)

Xing, B.; Li, J.; Zhu, H.; Wei, P.; Zhao, Y.

2018-04-01

As a kind of marine natural disaster, Green Tide has been appearing every year along the Qingdao Coast, bringing great loss to this region, since the large-scale bloom in 2008. Therefore, it is of great value to obtain the real time dynamic information about green tide distribution. In this study, methods of optical remote sensing and microwave remote sensing are employed in Green Tide Monitoring Research. A specific remote sensing data processing flow and a green tide information extraction algorithm are designed, according to the optical and microwave data of different characteristics. In the aspect of green tide spatial distribution information extraction, an automatic extraction algorithm of green tide distribution boundaries is designed based on the principle of mathematical morphology dilation/erosion. And key issues in information extraction, including the division of green tide regions, the obtaining of basic distributions, the limitation of distribution boundary, and the elimination of islands, have been solved. The automatic generation of green tide distribution boundaries from the results of remote sensing information extraction is realized. Finally, a green tide monitoring system is built based on IDL/GIS secondary development in the integrated environment of RS and GIS, achieving the integration of RS monitoring and information extraction.

Accuracy Assessment of Global Barotropic Ocean Tide Models

Science.gov (United States)

2014-08-07

Altimetry, Venice . Cartwright, D. E. (1999), Tides: A Scientific History , Cambridge Univ. Press, New York. Cartwright, D. E., and R. D. Ray (1990), Oceanic...E. Harrison, and D. Stammer, p. 4, ESA Publication WPP-306, Venice , Italy. Book, J. W., H. Perkins, and M. Wimbush (2009), North Adriatic tides

Detection of red tide events in the Ariake Sound, Japan

Science.gov (United States)

Ishizaka, Joji

2003-05-01

High resolution SeaWiFS data was used to detect a red tide event occurred in the Ariake Sound, Japan, in winter of 2000 to 2001. The area is small embayment surrounding by tidal flat, and it is known as one of the most productive areas in coast of Japan. The red tide event damaged to seaweed (Nori) culture, and the relation to the reclamation at the Isahaya Bay in the Sound has been discussed. SeaWiFS chlorophyll data showed the red tide started early December 2000, from the Isahaya Bay, although direct relationship to the reclamation was not clear. The red tide persisted to the end of February. Monthly average of SeaWiFS data from May 1998 to December 2001 indicated that the chlorophyll increased twice a year, early summer and fall after the rain. The red tide event was part of the fall bloom which started later and continued longer than other years. Ocean color is useful to detect the red tide; however, it is required to improve the algorithms to accurately estimate chlorophyll in high turbid water and to discriminate toxic flagellates.

Mapping ocean tides with satellites - A computer simulation

Science.gov (United States)

Won, I. J.; Kuo, J. T.; Jachens, R. C.

1978-01-01

As a preliminary study for the future worldwide direct mapping of the open ocean tide with satellites equipped with precision altimeters we conducted a simulated study using sets of artificially generated altimeter data constructed from a realistic geoid and four pairs of major tides in the northeastern Pacific Ocean. Recovery of the original geoid and eight tidal maps is accomplished by a space-time, least squares harmonic analysis scheme. The resultant maps appear fairly satisfactory even when random noises up to + or - 100 cm are added to the altimeter data of sufficient space-time density. The method also produces a refined geoid which is rigorously corrected for the dynamic tides.

Dancing with the Tides: Fluctuations of Coastal Phytoplankton Orchestrated by Different Oscillatory Modes of the Tidal Cycle

Science.gov (United States)

Blauw, Anouk N.; Benincà, Elisa; Laane, Remi W. P. M.; Greenwood, Naomi; Huisman, Jef

2012-01-01

Population fluctuations are often driven by an interplay between intrinsic population processes and extrinsic environmental forcing. To investigate this interplay, we analyzed fluctuations in coastal phytoplankton concentration in relation to the tidal cycle. Time series of chlorophyll fluorescence, suspended particulate matter (SPM), salinity and temperature were obtained from an automated measuring platform in the southern North Sea, covering 9 years of data at a resolution of 12 to 30 minutes. Wavelet analysis showed that chlorophyll fluctuations were dominated by periodicities of 6 hours 12 min, 12 hours 25 min, 24 hours and 15 days, which correspond to the typical periodicities of tidal current speeds, the semidiurnal tidal cycle, the day-night cycle, and the spring-neap tidal cycle, respectively. During most of the year, chlorophyll and SPM fluctuated in phase with tidal current speed, indicative of alternating periods of sinking and vertical mixing of algal cells and SPM driven by the tidal cycle. Spring blooms slowly built up over several spring-neap tidal cycles, and subsequently expanded in late spring when a strong decline of the SPM concentration during neap tide enabled a temporary “escape” of the chlorophyll concentration from the tidal mixing regime. Our results demonstrate that the tidal cycle is a major determinant of phytoplankton fluctuations at several different time scales. These findings imply that high-resolution monitoring programs are essential to capture the natural variability of phytoplankton in coastal waters. PMID:23166639

Never Riding the Tide

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 13; Issue 10. Never Riding the Tide - Seymour Benzer–The Founder of Neurogenetics. K VijayRaghavan Veronica Rodrigues. General Article Volume 13 Issue 10 October 2008 pp 909-915 ...

Influence of tides on the gravitational field of Jupiter

International Nuclear Information System (INIS)

Gavrilov, S.V.; Zharkov, V.N.; Leont'ev, V.V.

1975-01-01

The influence of tides on the gravitational field of giant planets is considered quantitatively. The ''gravitational noise'' due to tides can affect the determination of J 8 and J 10 for Jupiter. Tidal sounding of the giant planets is suggested. (author)

Variation in foraging activity of Acanthochitona garnoti (Mollusca ...

African Journals Online (AJOL)

Foraging activity of Acanthochitona gamoti was studied during spring and neap tides in three different habitats: an aeolian sandstone ... mm) during a spring tide new moon and least on a spring tide full moon (x = 4.0 h; x = 182 rnm). Chitons on the boulder ..... BECKLEY, L.E. 1994. Two Oceans: A guide to Marine Life of.

Ocean Tide Influences on the Antarctic and Greenland Ice Sheets

Science.gov (United States)

Padman, Laurie; Siegfried, Matthew R.; Fricker, Helen A.

2018-03-01

Ocean tides are the main source of high-frequency variability in the vertical and horizontal motion of ice sheets near their marine margins. Floating ice shelves, which occupy about three quarters of the perimeter of Antarctica and the termini of four outlet glaciers in northern Greenland, rise and fall in synchrony with the ocean tide. Lateral motion of floating and grounded portions of ice sheets near their marine margins can also include a tidal component. These tide-induced signals provide insight into the processes by which the oceans can affect ice sheet mass balance and dynamics. In this review, we summarize in situ and satellite-based measurements of the tidal response of ice shelves and grounded ice, and spatial variability of ocean tide heights and currents around the ice sheets. We review sensitivity of tide heights and currents as ocean geometry responds to variations in sea level, ice shelf thickness, and ice sheet mass and extent. We then describe coupled ice-ocean models and analytical glacier models that quantify the effect of ocean tides on lower-frequency ice sheet mass loss and motion. We suggest new observations and model developments to improve the representation of tides in coupled models that are used to predict future ice sheet mass loss and the associated contribution to sea level change. The most critical need is for new data to improve maps of bathymetry, ice shelf draft, spatial variability of the drag coefficient at the ice-ocean interface, and higher-resolution models with improved representation of tidal energy sinks.

Tides in three enclosed basins: the Baltic, Black and Caspian seas

Directory of Open Access Journals (Sweden)

Igor P Medvedev

2016-04-01

Full Text Available Tides are the main type of sea level variability in the world ocean. However, oceanic tides penetrate weakly, or do not penetrate at all, into enclosed basins such as the Baltic, Black and Caspian seas. Consequently, only directly forced tides are formed in these basins. Long observation time series (up to 123 years in the Baltic Sea and 38 years in the Black and Caspian seas at numerous stations were used to precisely estimate tidal constituents. High-resolution spectra revealed fine structure of discrete peaks at tidal frequencies. The diurnal radiational constituent S1 (1 cpd, apparently associated with breeze winds, was found to play an important role in general tidal dynamics in these seas. Harmonic analysis of tides for individual yearly series with consecutive vector averaging over the entire observational period was applied to estimate mean amplitudes and phases of tidal constituents. Our findings indicate that the formation and predominance of diurnal or semidiurnal tides in these seas appears to depend on the frequency-selective properties of the basins. Thus, in the Baltic Sea with fundamental modal period of about 27 h, diurnal tides dominate in the major eastern gulfs. In the Black Sea resonant amplification of semidiurnal tides is observed in the northwestern part. The predominance of semidiurnal tides in the Caspian Sea has also probably a resonant nature. Maximum tidal heights estimated for a 100-year period are 23 cm in the Baltic Sea, 18 cm in the Black Sea and 21 cm in the southern Caspian Sea.

Estimating absolute sea level variations by combining GNSS and Tide gauge data

Digital Repository Service at National Institute of Oceanography (India)

Bos, M.S.; Fernandes, R.M.S; Vethamony, P.; Mehra, P.

Indian tide gauges can be used to estimate sea level rise. To separate relative sea level rise from vertical land motion at the tide gauges, various GNSS stations have been installed in the last years at, or nearby, tide gauges. Using the PSMSL...

Earth tide effects on kinematic/static GPS positioning in Denmark and Greenland

DEFF Research Database (Denmark)

Xu, G.C.; Knudsen, Per

2000-01-01

A detailed Study of the Earth tide effects on the GPS kinematic/static positioning is presented in this paper by using theoretical Earth tide computation and practical GPS data processing. Tidal effects could reach up to 30 cm in Denmark and Greenland depending on the measuring time...... and the position of reference station. With a baseline less than 80 km, the difference of the Earth tide effects could reach more than 5 mm. So, in precise applications of GPS positioning, the Earth tide effect has to be taken into account even for a relative small local GPS network. Several examples are given...... for demonstrating that the Earth tide effects can be viewed by GPS surveying. They are given through static GPS data static processing, static GPS data kinematic processing, and airborne kinematic GPS data processing. In these cases, the Earth tide effects can be subtracted from the GPS results. The determination...

The self-consistent dynamic pole tide in global oceans

Science.gov (United States)

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.

Seasonal variation of semidiurnal internal tides in the East/Japan Sea

Science.gov (United States)

Jeon, Chanhyung; Park, Jae-Hun; Varlamov, Sergey M.; Yoon, Jong-Hwan; Kim, Young Ho; Seo, Seongbong; Park, Young-Gyu; Min, Hong Sik; Lee, Jae Hak; Kim, Cheol-Ho

2014-05-01

The seasonal variation of semidiurnal internal tides in the East/Japan Sea was investigated using 25 month long output from a real-time ocean forecasting system. The z coordinate eddy-resolving high-resolution numerical model, called the RIAM ocean model, incorporates data assimilation that nudges temperature and salinity fields together with volume transport through the Korea Strait to produce realistic oceanic currents and stratification. In addition to atmospheric forcing, it includes tidal forcing of 16 major components along open boundaries. The model generates energetic semidiurnal internal tides around the northern entrance of the Korea Strait. Energy conversion from barotropic to baroclinic (internal) tides varies seasonally with maxima in September (ranging 0.48-0.52 GW) and minima in March (ranging 0.11-0.16 GW). This seasonal variation is induced by the seasonality in stratification near the southwestern East/Japan Sea. The propagation distance of the internal tides is associated with generation intensity and wavelength. From late summer to early winter, the semidiurnal internal tides travel relatively far from the generation region due to stratification changes; its energy dissipates less as a result of longer wavelengths. Our results suggest that spatiotemporal variation of internal-tide-induced mixing due to the seasonality in the generation, propagation, and dissipation of internal tides should be considered for a more realistic simulation of water masses and circulation in models of the East/Japan Sea.

Tidal asymmetry in a funnel-shaped estuary with mixed semidiurnal tides

Science.gov (United States)

Gong, Wenping; Schuttelaars, Henk; Zhang, Heng

2016-05-01

Different types of tidal asymmetry (see review of de Swart and Zimmerman Annu Rev Fluid Mech 41: 203-229, 2009) are examined in this study. We distinguish three types of tidal asymmetry: duration and magnitude differences between flood and ebb tidal flow, duration difference between the rising and falling tides. For waterborne substance transport, the first two asymmetries are important while the last one is not. In this study, we take the Huangmaohai Estuary (HE), Pearl River Delta, China as an example to examine the spatio-temporal variations of the tidal asymmetry in a mixed semidiurnal tidal regime and to explain them by investigating the associated mechanisms. The methodology defining the tidal duration asymmetry and velocity skewness, proposed by Nidzieko (J Geophys Res 115: C08006. doi: 10.1029/2009JC005864 , 2010) and synthesized by Song et al. (J Geophys Res 116: C12007. doi: 10.1029/2011JC007270 , 2011), is utilized here and referred to as tidal duration asymmetry (TDA) and flow velocity asymmetry (FVA), respectively. The methodology is further used to quantify the flow duration asymmetry (FDA). A positive asymmetry means a shorter duration of low water slack for FDA, a shorter duration of the rising tide for TDA, and a flood dominance for FVA and vice versa. The Regional Ocean Modeling System (ROMS) model is used to provide relatively long-term water elevation and velocity data and to conduct diagnostic experiments. In the HE, the main tidal constituents are diurnal tides K 1, O 1 and semidiurnal tides M 2 and S 2. The interaction among the diurnal and semidiurnal tides generates a negative tidal asymmetry, while the interactions among semidiurnal tides and their overtides or compound tides result in a positive tidal asymmetry. The 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

The Effect of Warming Oceans at a Tide Gauge Station

OpenAIRE

Bâki Iz H.

2016-01-01

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/y...

NOS CO-OPS Water Level Data, High Low Tide Prediction

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has High Low Tide Predictions from NOAA NOS Center for Operational Oceanographic Products and Services (CO-OPS). The official Tide and Tidal Current...

NOS CO-OPS Water Level Data, Tide Prediction, 60-Minute

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has High Low Tide Predictions from NOAA NOS Center for Operational Oceanographic Products and Services (CO-OPS). The official Tide and Tidal Current...

NOS CO-OPS Water Level Data, Tide Prediction, 6-Minute

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has High Low Tide Predictions from NOAA NOS Center for Operational Oceanographic Products and Services (CO-OPS). The official Tide and Tidal Current...

Weight, gravitation, inertia, and tides

Science.gov (United States)

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.

Weight, gravitation, inertia, and tides

International Nuclear Information System (INIS)

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

2015-01-01

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. (paper)

Global Earth Response to Loading by Ocean Tide Models

Science.gov (United States)

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.

Impacts of exotic mangroves and mangrove control on tide pool fish assemblages

Science.gov (United States)

Richard A. MacKenzie; Cailtin L. Kryss

2013-01-01

Fish were sampled from tide pools in Hawaii to determine how exotic mangroves Rhizophora mangle and the use of herbicides to chemically eradicate them are impacting tide pool fish assemblages. Ecological parameters were compared among mangrove-invaded, native vegetated, and non-vegetated tide pools before and after mangroves had been chemically...

The Effect of Barotropic and Baroclinic Tides on Coastal Stratification and Mixing

Science.gov (United States)

Suanda, S. H.; Feddersen, F.; Kumar, N.

2017-12-01

The effects of barotropic and baroclinic tides on subtidal stratification and vertical mixing are examined with high-resolution, three-dimensional numerical simulations of the Central Californian coastal upwelling region. A base simulation with realistic atmospheric and regional-scale boundary forcing but no tides (NT) is compared to two simulations with the addition of predominantly barotropic local tides (LT) and with combined barotropic and remotely generated, baroclinic tides (WT) with ≈ 100 W m-1 onshore baroclinic energy flux. During a 10 day period of coastal upwelling when the domain volume-averaged temperature is similar in all three simulations, LT has little difference in subtidal temperature and stratification compared to NT. In contrast, the addition of remote baroclinic tides (WT) reduces the subtidal continental shelf stratification up to 50% relative to NT. Idealized simulations to isolate barotropic and baroclinic effects demonstrate that within a parameter space of typical U.S. West Coast continental shelf slopes, barotropic tidal currents, incident energy flux, and subtidal stratification, the dissipating baroclinic tide destroys stratification an order of magnitude faster than barotropic tides. In WT, the modeled vertical temperature diffusivity at the top (base) of the bottom (surface) boundary layer is increased up to 20 times relative to NT. Therefore, the width of the inner-shelf (region of surface and bottom boundary layer overlap) is increased approximately 4 times relative to NT. The change in stratification due to dissipating baroclinic tides is comparable to the magnitude of the observed seasonal cycle of stratification.

Risk in daily newspaper coverage of red tide blooms in Southwest Florida.

Science.gov (United States)

Li, Zongchao; Garrison, Bruce; Ullmann, Steven G; Kirkpatrick, Barbara; Fleming, Lora E; Hoagland, Porter

This study investigated newspaper coverage of Florida red tide blooms in four metropolitan areas of Southwest Florida during a 25-year period, 1987-2012. We focused on how journalists framed red tide stories with respect to environmental risk, health risk, and economic risk. We determined risk to be a key factor in this news coverage, being an aspect of coverage of red tide itself in terms of environmental risk, tourism risk, and public health risk. The study found that red tide news coverage is most often framed as an environmental story.

Modelling and parameterizing the influence of tides on ice-shelf melt rates

Science.gov (United States)

Jourdain, N.; Molines, J. M.; Le Sommer, J.; Mathiot, P.; de Lavergne, C.; Gurvan, M.; Durand, G.

2017-12-01

Significant Antarctic ice sheet thinning is observed in several sectors of Antarctica, in particular in the Amundsen Sea sector, where warm circumpolar deep waters affect basal melting. The later has the potential to trigger marine ice sheet instabilities, with an associated potential for rapid sea level rise. It is therefore crucial to simulate and understand the processes associated with ice-shelf melt rates. In particular, the absence of tides representation in ocean models remains a caveat of numerous ocean hindcasts and climate projections. In the Amundsen Sea, tides are relatively weak and the melt-induced circulation is stronger than the tidal circulation. Using a regional 1/12° ocean model of the Amundsen Sea, we nonetheless find that tides can increase melt rates by up to 36% in some ice-shelf cavities. Among the processes that can possibly affect melt rates, the most important is an increased exchange at the ice/ocean interface resulting from the presence of strong tidal currents along the ice drafts. Approximately a third of this effect is compensated by a decrease in thermal forcing along the ice draft, which is related to an enhanced vertical mixing in the ocean interior in presence of tides. Parameterizing the effect of tides is an alternative to the representation of explicit tides in an ocean model, and has the advantage not to require any filtering of ocean model outputs. We therefore explore different ways to parameterize the effects of tides on ice shelf melt. First, we compare several methods to impose tidal velocities along the ice draft. We show that getting a realistic spatial distribution of tidal velocities in important, and can be deduced from the barotropic velocities of a tide model. Then, we explore several aspects of parameterized tidal mixing to reproduce the tide-induced decrease in thermal forcing along the ice drafts.

Spring in the Arab Spring

NARCIS (Netherlands)

Borg, G.J.A.

2011-01-01

Column Gert Borg | Spring in the Arab Spring door dr. Gert Borg, onderzoeker bij Islam en Arabisch aan de Radboud Universiteit Nijmegen en voormalig directeur van het Nederlands-Vlaams Instituut Caïro Spring If, in Google, you type "Arab Spring" and hit the button, you get more than

Arctic Tides from GPS on sea-ice

DEFF Research Database (Denmark)

Kildegaard Rose, Stine; Skourup, Henriette; Forsberg, René

2013-01-01

The presence of sea-ice in the Arctic Ocean plays a significant role in the Arctic climate. Sea-ice dampens the ocean tide amplitude with the result that global tidal models perform less accurately in the polar regions. This paper presents, a kinematic processing of global positioning system (GPS....... The results show coherence between the GPS buoy measurements, and the tide model. Furthermore, we have proved that the reference ellipsoid of WGS84, can be interpolated to the tidal defined zero level by applying geophysical corrections to the GPS data....

Sediment transport and fluid mud layer formation in the macro-tidal Chikugo river estuary during a fortnightly tidal cycle

Science.gov (United States)

Azhikodan, Gubash; Yokoyama, Katsuhide

2018-03-01

The erosion and deposition dynamics of fine sediment in a highly turbid estuarine channel were successfully surveyed during the period from August 29 to September 12, 2009 using an echo sounder in combination with a high-resolution acoustic Doppler current profiler. Field measurements were conducted focusing on the tide driven dynamics of suspended sediment concentration (SSC), and fluid mud at the upstream of the macrotidal Chikugo river estuary during semidiurnal and fortnightly tidal cycles. Morphological evolution was observed especially during the spring tide over a period of two weeks. The elevation of the channel bed was stable during neap tide, but it underwent fluctuations when the spring tide occurred owing to the increase in the velocity and shear stress. Two days of time lag were observed between the maximum SSC and peak tidal flow, which resulted in the asymmetry between neap-to-spring and spring-to-neap transitions. During the spring tide, a hysteresis loop was observed between shear stress and SSC, and its direction was different during flood and ebb tides. Although both fine sediments and flocs were dominant during flood tides, only fine sediments were noticed during ebb tides. Hence, the net elevation change in the bed was positive, and sedimentation took place during the semilunar tidal cycle. Finally, a bed of consolidated mud was deposited on the initial bed, and the height of the channel bed increased by 0.9 m during the two-week period. The observed hysteretic effect between shear stress and SSC during the spring tides, and the asymmetrical neap-spring-neap tidal cycle influenced the near-bed sediment dynamics of the channel, and led to the formation of a fluid mud layer at the bottom of the river.

Preliminary study on the influence of the tides of planet earth on hydrostatic leveling system

International Nuclear Information System (INIS)

He Xiaoye; Xu Shaofeng; Wang Peng

2012-01-01

Hydrostatic leveling system, used mainly in survey and alignment technology in particle accelerator and monitoring the tides is introduced in this paper. Based on the theory about the ocean tide and earth tide, we analyze effects of the earth tides on a hydrostatic leveling system. From the data obtained from an HLS, and their F are, and finally we verify the influence of the tides of planet earth. (authors)

Variability of the internal tide on the southern Monterey Bay continental shelf and associated bottom boundary layer sediment transport

Science.gov (United States)

Rosenberger, Kurt; Storlazzi, Curt; Cheriton, Olivia

2016-01-01

A 6-month deployment of instrumentation from April to October 2012 in 90 m water depth near the outer edge of the mid-shelf mud belt in southern Monterey Bay, California, reveals the importance regional upwelling on water column density structure, potentially accounting for the majority of the variability in internal tidal energy flux across the shelf. Observations consisted of time-series measurements of water-column currents, temperature and salinity, and near-bed currents and suspended matter. The internal tide accounted for 15–25% of the water-column current variance and the barotropic tide accounted for up to 35%. The subtidal flow showed remarkably little shear and was dominated by the 7–14 day band, which is associated with relaxations in the dominant equatorward winds typical of coastal California in the spring and summer. Upwelling and relaxation events resulted in strong near-bed flows and accounted for almost half of the current stress on the seafloor (not accounting for wave orbital velocities), and may have driven along-shelf geostrophic flow during steady state conditions. Several elevated suspended particulate matter (SPM) events occurred within 3 m of the bed and were generally associated with higher, long-period surface waves. However, these peaks in SPM did not coincide with the predicted resuspension events from the modeled combined wave–current shear stress, indicating that the observed SPM at our site was most likely resuspended elsewhere and advected along-isobath. Sediment flux was almost equal in magnitude in the alongshore and cross-shore directions. Instances of wave–current shear stress that exceeded the threshold of resuspension for the silty-clays common at these water depths only occurred when near-bed orbital velocities due to long-period surface waves coincided with vigorous near-bed currents associated with the internal tide or upwelling/relaxation events. Thus upwelling/relaxation dynamics are primarily responsible for

Climatologies of tides at mid-latitudes in the lower termosphere

International Nuclear Information System (INIS)

Cevolani, G.

1991-01-01

Time variations of the semi-diurnal and diurnal tides observed at Budrio (45N, 12E) in the wind structure of the lower termosphere ((80-110) km) throughout the period 1976-1990 are herewith represented as monthly contours of both amplitudes and phases vs. height. The semi-diurnal tide has more marked seasonal variations, showing amplitudes generally larger than the diurnal ones ((10-30) m/s vs. (5-15) m/s). The vertical wavelengths are longer in summer than in winter, at least below 100 km. Agreement with new numerical models for semi-diurnal tide at 50N appears to be satisfactory

Phytoplankton and bacterial community structures and their interaction during red-tide phenomena

Science.gov (United States)

Ismail, Mona Mohamed; Ibrahim, Hassan Abd Allah

2017-09-01

Phytoplankton and bacteria diversity were studied before, during and after red tide phenomena during spring season 2015 in the Eastern Harbour (E.H.) of Alexandria, Egypt. Fifty five species of phytoplankton were identified and represented different distinct classes "Bacillariophyceae; Dinophyceae, Chlorophyceae, Cyanophyceae and Eugelenophyceae". Also, Diatom formed the most dominant group. The average number of the phytoplankton density varied from 4.8 × 104 to 1.1 × 106 cell l-1 during the study period and Skeletonema costatum was the agent causing the red tide. The existence percentages of bacteria ranged from 2.6 to 17.9% on all media tested. The bacterial isolates on the nutrient agar medium represented the highest existence with a total percentage of 43.6%, followed by MSA medium (25.7%), while the lowest percentage was for the AA medium at 7.8%. However, twelve isolates were selected as representative for bacterial community during study interval. Based on the morphological, biochemical, physiological and enzymatic characteristics, the bacterial strains were described. Depending on the 16S rDNA gene sequence, three common antagonists were aligned as: Vibrio toranzoniae strain Vb 10.8, Ruegeria pelagia strain NBRC 102038 and Psychrobacter adeliensis strain DSM 15333. The interaction between these bacteria and S. costatum was studied. The growth of S. costatum was significantly lower whenever each bacterium was present as compared to axenic culture. More specifically, 30% (v/v) of the all tested bacteria showed the strongest algicidal activities, as all S. costatum cells were killed after two days. 10% of R. pelagia and P. adeliensis also showed significant algicidal activities within six days.

Effect of Tide Elevation on Extratropical Storm Surge in Northwest Europe

Science.gov (United States)

Keshtpoor, M.; Carnacina, I.; Yablonsky, R. M.

2016-12-01

Extratropical cyclones (ETCs) are the major storm surge-generating meteorological events in northwest Europe. The total water level increase induced by these ETCs is significantly influenced by the local tidal range, which exceeds 8 meters along the southwestern UK coastline. In particular, a surge-generating ETC during high tide may put coastal assets and infrastructure in risk. Also, during low tide, the risk of surge induced by extreme ETC events is diminished. Here, the effect of tidal elevation on storm surge is investigated at 196 tide gauges in northwest Europe. A numerical, hydrodynamic model was developed using Delft3D-FM framework to simulate the coastal hydrodynamics during ETCs. Then, 1750 historical events were simulated to investigate the pattern of coastal inundation. Results suggest that in areas with a large tidal range ( 8 meters) and during the time period surrounding high or low tide, the pattern of coastal hydrodynamics is governed by tide and not storm surge. This result is most evident near the English Channel and Bristol Channel, where low frequency maximum water levels are observed when storm surge is combined with high tide. In contrast, near the tidal phase reversal, coastal hydrodynamics responds primarily to the storm surge, and low frequency maximum water elevation largely depends on the surge. In the areas with a small tidal range, ETC strength determines the pattern of coastal inundation.

M2, S2, K1 models of the global ocean tide

Science.gov (United States)

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.

Tidal variability of nutrients in a coastal coral reef system influenced by groundwater

Directory of Open Access Journals (Sweden)

G. Wang

2018-02-01

Full Text Available To investigate variation in nitrite, nitrate, phosphate, and silicate in a spring–neap tide in a coral reef system influenced by groundwater discharge, we carried out a time-series observation of these nutrients and 228Ra, a tracer of groundwater discharge, in the Luhuitou fringing reef at Sanya Bay in the South China Sea. The maximum 228Ra, 45.3 dpm 100 L−1, appeared at low tide and the minimum, 14.0 dpm 100 L−1, appeared during a flood tide in the spring tide. The activity of 228Ra was significantly correlated with water depth and salinity in the spring–neap tide, reflecting the tidal-pumping feature of groundwater discharge. Concentrations of all nutrients exhibited strong diurnal variation, with a maximum in the amplitude of the diel change for nitrite, nitrate, phosphate, and silicate in the spring tide of 0.46, 1.54, 0.12, and 2.68 µM, respectively. Nitrate and phosphate were negatively correlated with water depth during the spring tide but showed no correlation during the neap tide. Nitrite was positively correlated with water depth in the spring and neap tide due to mixing of nitrite-depleted groundwater and nitrite-rich offshore seawater. They were also significantly correlated with salinity (R2  ≥  0.9 and P < 0.05 at the ebb flow of the spring tide, negative for nitrate and phosphate and positive for nitrite, indicating the mixing of nitrite-depleted, nitrate- and phosphate-rich less saline groundwater and nitrite-rich, nitrate- and phosphate-depleted saline offshore seawater. We quantified variation in oxidized nitrogen (NOx and phosphate contributed by biological processes based on deviations from mixing lines of these nutrients. During both the spring and neap tide biologically contributed NOx and phosphate were significantly correlated with regression slopes of 4.60 (R2  =  0.16 in the spring tide and 13.4 (R2  =  0.75 in the neap tide, similar to the composition of these

Ocean tides in GRACE monthly averaged gravity fields

DEFF Research Database (Denmark)

Knudsen, Per

2003-01-01

The GRACE mission will map the Earth's gravity fields and its variations with unprecedented accuracy during its 5-year lifetime. Unless ocean tide signals and their load upon the solid earth are removed from the GRACE data, their long period aliases obscure more subtle climate signals which GRACE...... aims at. In this analysis the results of Knudsen and Andersen (2002) have been verified using actual post-launch orbit parameter of the GRACE mission. The current ocean tide models are not accurate enough to correct GRACE data at harmonic degrees lower than 47. The accumulated tidal errors may affect...... the GRACE data up to harmonic degree 60. A study of the revised alias frequencies confirm that the ocean tide errors will not cancel in the GRACE monthly averaged temporal gravity fields. The S-2 and the K-2 terms have alias frequencies much longer than 30 days, so they remain almost unreduced...

Subsurface Ocean Tides in Enceladus and Other Icy Moons

Science.gov (United States)

Beuthe, M.

2016-12-01

Could tidal dissipation within Enceladus' subsurface ocean account for the observed heat flow? Earthlike models of dynamical tides give no definitive answer because they neglect the influence of the crust. I propose here the first model of dissipative tides in a subsurface ocean, by combining the Laplace Tidal Equations with the membrane approach. For the first time, it is possible to compute tidal dissipation rates within the crust, ocean, and mantle in one go. I show that oceanic dissipation is strongly reduced by the crustal constraint, and thus contributes little to Enceladus' present heat budget. Tidal resonances could have played a role in a forming or freezing ocean less than 100 meters deep. The model is general: it applies to all icy satellites with a thin crust and a shallow or stratified ocean. Scaling rules relate the resonances and dissipation rate of a subsurface ocean to the ones of a surface ocean. If the ocean has low viscosity, the westward obliquity tide does not move the crust. Therefore, crustal dissipation due to dynamical obliquity tides can differ from the static prediction by up to a factor of two.

Tide-surge interaction along the east coast of the Leizhou Peninsula, South China Sea

Science.gov (United States)

Zhang, Heng; Cheng, Weicong; Qiu, Xixi; Feng, Xiangbo; Gong, Wenping

2017-06-01

A triply-nested two-dimensional (2D) ocean circulation model along with observed sea level records are used to study tide-surge interaction along the east coast of the Leizhou Peninsula (LP) which is characterized by extensive mudflats, large tidal ranges and a complex coastline. The dependency of surge maxima on the water level and the phase of tide are respectively investigated using two statistical approaches. Results show that tide-surge interaction along the east coast of the LP is significant, where surges peak 3-6 h before or after the nearest high water. The triply-nested 2D ocean circulation model is used to quantify tide-surge interaction in this region and to investigate its physical cause. The largest amplitudes of tide-surge interaction are found in the shallow water region of the Leizhou Bay, with values up to 1 m during typhoon events. Numerical experiments reveal that nonlinear bottom friction is the main contributor to tide-surge interaction, while the contribution of the nonlinear advective effect can be neglected. The shallow water effect enhances the role of nonlinear bottom friction in determining tide-surge modulation, leaving the surge peaks usually occur on the rising or falling tide. It is also found that the relative contribution of local wind and remote wind is different depending on the storm track and storm intensity, which would finally affect the temporal and spatial distribution of tide-surge interaction during typhoon events. These findings confirm the importance of coupling storm surges and tides for the prediction of storm surge events in regions which are characterized by shallow water depths and large tidal ranges.

Dynamical significance of tides over the Bay of Bengal

Science.gov (United States)

Bhagawati, Chirantan; Pandey, Suchita; Dandapat, Sumit; Chakraborty, Arun

2018-06-01

Tides play a significant role in the ocean surface circulations and vertical mixing thereby influencing the Sea Surface Temperatures (SST) as well. This, in turn, plays an important role in the global circulation when used as a lower boundary condition in a global atmospheric general circulation model. Therefore in the present study, the dynamics of tides over the Bay of Bengal (BoB) is investigated through numerical simulations using a high resolution (1/12°) Regional Ocean Modeling System (ROMS). Based on statistical analysis it is observed that incorporation of explicit tidal forcing improves the model performance in simulating the basin averaged monthly surface circulation features by 64% compared to the simulation without tides. The model simulates also Mixed Layer Depth (MLD) and SST realistically. The energy exchange between tidal oscillations and eddies leads to redistribution of surface kinetic energy density with a net decrease of 0.012 J m-3 in the western Bay and a net increase of 0.007 J m-3 in the eastern Bay. The tidal forcing also affects the potential energy anomaly and vertical mixing thereby leading to a fall in monthly MLD over the BoB. The mixing due to tides leads to a subsequent reduction in monthly SST and a corresponding reduction in surface heat exchange. These results from the numerical simulation using ROMS reveal that tides have a significant influence over the air-sea heat exchange which is the most important parameter for prediction of Tropical Cyclone frequency and its future variability over the BoB.

Secular Changes in the Solar Semidiurnal Tide of the Western North Atlantic Ocean

Science.gov (United States)

Ray, Richard D.

2009-01-01

An analysis of twentieth century tide gauge records reveals that the solar semidiurnal tide S, has been decreasing in amplitude along the eastern coast of North America and at the mid-ocean site Bermuda. In relative terms the observed rates are unusually large, of order 10% per century. Periods of greatest change, however, are inconsistent among the stations, and roughly half the stations show increasing amplitude since the late 1990s. Excepting the Gulf of Maine, lunar tides are either static or slightly increasing in amplitude; a few stations show decreases. Large changes in solar, but not lunar, tides suggest causes related to variable radiational forcing, but the hypothesis is at present unproven. Citation: Ray, R. D. (2009), Secular changes in the solar semidiurnal tide of the western North Atlantic Ocean

Spring performance tester for miniature extension springs

Science.gov (United States)

Salzbrenner, Bradley; Boyce, Brad

2017-05-16

A spring performance tester and method of testing a spring are disclosed that has improved accuracy and precision over prior art spring testers. The tester can perform static and cyclic testing. The spring tester can provide validation for product acceptance as well as test for cyclic degradation of springs, such as the change in the spring rate and fatigue failure.

TIDE: Lightweight Device Composition for Enhancing Tabletop Environments with Smartphone Applications

DEFF Research Database (Denmark)

Sicard, Leo; Tabard, Aurelien; Ramos, Juan David Hincapie

2013-01-01

platforms have to be re-developed. At the same time, smartphones are pervasive computers that users carry around and with a large pool of applications. This paper presents TIDE, a lightweight device composition middleware to bring existing smartphone applica- tions onto the tabletop. Through TIDE......, applications running on the smartphone are displayed on the tabletop computer, and users can interact with them through the tabletop’s interactive surface. TIDE contributes to the areas of device compo- sition and tabletops by providing an OS-level middleware that is transparent to the smartphone applications...

Geographical representation of radial orbit perturbations due to ocean tides: Implications for satellite altimetry

Science.gov (United States)

Bettadpur, Srinivas V.; Eanes, Richard J.

1994-01-01

In analogy to the geographical representation of the zeroth-order radial orbit perturbations due to the static geopotential, similar relationships have been derived for radial orbit perturbations due to the ocean tides. At each location these perturbations are seen to be coherent with the tide height variations. The study of this singularity is of obvious importance to the estimation of ocean tides from satellite altimeter data. We derive analytical expressions for the sensitivity of altimeter derived ocean tide models to the ocean tide force model induced errors in the orbits of the altimeter satellite. In particular, we focus on characterizing and quantifying the nonresonant tidal orbit perturbations, which cannot be adjusted into the empirical accelerations or radial perturbation adjustments commonly used during orbit determination and in altimeter data processing. As an illustration of the utility of this technique, we study the differences between a TOPEX/POSEIDON-derived ocean tide model and the Cartwright and Ray 1991 Geosat model. This analysis shows that nearly 60% of the variance of this difference for M(sub 2) can be explained by the Geosat radial orbit eror due to the omission of coefficients from the GEM-T2 background ocean tide model. For O(sub 1), K(sub 1), S(sub 2), and K(sub 2) the orbital effects account for approximately 10 to 40% of the variances of these differences. The utility of this technique to assessment of the ocean tide induced errors in the TOPEX/POSEIDON-derived tide models is also discussed.

Nonlinear terms in storm surge predictions: Effect of tide and shelf geometry with case study from Hurricane Rita

Science.gov (United States)

Rego, JoãO. L.; Li, Chunyan

2010-06-01

This study applied the finite volume coastal ocean model (FVCOM) to the storm surge induced by Hurricane Rita along the Louisiana-Texas coast. The model was calibrated for tides and validated with observed water levels. Peak water levels were shown to be lower than expected for a landfall at high tide. For low- and high-tide landfalls, nonlinear effects due to tide-surge coupling were constructive and destructive to total storm tide, respectively, and their magnitude reached up to 70% of the tidal amplitude in the Rita application. Tide-surge interaction was further examined using a standard hurricane under idealized scenarios to evaluate the effects of various shelf geometries, tides, and landfall timings (relative to tide). Nonlinearity was important between landfall position and locations within 2.5 × radius of maximum winds. On an idealized wide continental shelf, nonlinear effects reached up to 80% of the tidal amplitude with an S2 tide and up to 47% with a K1 tide. Increasing average depths by 4 m reduced nonlinear effects to 41% of the tidal amplitude; increasing the slope by a factor of 3 produced nonlinearities of just 26% of tide (both with a K1 tide). The nonlinear effect was greatest for landfalls at low tide, followed by landfalls at high tide and then by landfalls at midebb or midflood.

Consortial brown tide - picocyanobacteria blooms in Guantánamo Bay, Cuba.

Science.gov (United States)

Hall, Nathan S; Litaker, R Wayne; Kenworthy, W Judson; Vandersea, Mark W; Sunda, William G; Reid, James P; Slone, Daniel H; Butler, Susan

2018-03-01

A brown tide bloom of Aureoumbra lagunensis developed in Guantánamo Bay, Cuba during a period of drought in 2013 that followed heavy winds and rainfall from Hurricane Sandy in late October 2012. Based on satellite images and water turbidity measurements, the bloom appeared to initiate in January 2013. The causative species (A. lagunensis) was confirmed by microscopic observation, and pigment and genetic analyses of bloom samples collected on May 28 of that year. During that time, A. lagunensis reached concentrations of 900,000 cells ml -1 (28 ppm by biovolume) in the middle portion of the Bay. Samples could not be collected from the northern (Cuban) half of the Bay because of political considerations. Subsequent sampling of the southern half of the Bay in November 2013, April 2014, and October 2014 showed persistent lower concentrations of A. lagunensis, with dominance shifting to the cyanobacterium Synechococcus (up to 33 ppm in April), an algal group that comprised a minor bloom component on May 28. Thus, unlike the brown tide bloom in Laguna Madre, which lasted 8 years, the bloom in Guantánamo Bay was short-lived, much like recent blooms in the Indian River, Florida. Although hypersaline conditions have been linked to brown tide development in the lagoons of Texas and Florida, observed euhaline conditions in Guantánamo Bay (salinity 35-36) indicate that strong hypersalinity is not a requirement for A. lagunensis bloom formation. Microzooplankton biomass dominated by ciliates was high during the observed peak of the brown tide, and ciliate abundance was high compared to other systems not impacted by brown tide. Preferential grazing by zooplankton on non-brown tide species, as shown in A. lagunensis blooms in Texas and Florida, may have been a factor in the development of the Cuban brown tide bloom. However, subsequent selection of microzooplankton capable of utilizing A. lagunensis as a primary food source may have contributed to the short-lived duration

A technique to circumvent lower density water trapping by tide-wells

Digital Repository Service at National Institute of Oceanography (India)

Joseph, A.; VijayKumar, K.; Desa, E.S.; Desa, E.; Peshwe, V.B.

A 3-year study of water density differences inside and outside of a conventional tide-well indicated that the average water density within the well is consistently lower than the external ambient waters. The tide-well at Goa is situated at the mouth...

Earthquake swarms and the semidiurnal solid earth tide

Energy Technology Data Exchange (ETDEWEB)

Klein, F W

1976-01-01

Several correlations between peak earthquake activity during swarms and the phase and stress orientation of the calculated solid earth tide are described. The events correlating with the tide are clusters of swarm earthquakes. Swarm clusters from many sequences recorded over several years are used. Significant tidal correlations (which have less than a 5% chance of being observed if earthquakes were random) are found in the Reykjanes Peninsula in Iceland, the central Mid-Atlantic Ridge, the Imperial Valley and northern Gulf of California, and larger (m/sub b/ greater than or equal to 5.0) aftershocks of the 1965 Rat Islands earthquake. In addition, sets of larger single earthquakes on Atlantic and north-east Pacific fracture zones are significantly correlated with the calculated solid tide. No tidal correlation, however, could be found for the Matsushiro Japan swarm of 1965 to 1967. The earthquake-tide correlations other than those of the Reykjanes Peninsula and Mid-Atlantic Ridge can be interpreted as triggering caused by enhancement of the tectonic stress by tidal stress, i.e. the alignment of fault and tidal principal stresses. All tidal correlations except in the Aleutians are associated with oceanic rifts or their landward extensions. If lithospheric plates are decoupled at active rifts, then tidal stresses channeled along the lithospheric stress guide may be concentrated at ridge-type plate boundaries. Tidal triggering of earthquakes at rifts may reflect this possible amplification of tidal strains in the weakened lithosphere at ridges. 25 figures, 2 tables.

TideWatch: Fingerprinting the cyclicality of big data workloads

KAUST Repository

Williams, Daniel W.

2014-04-01

Intrinsic to \\'big data\\' processing workloads (e.g., iterative MapReduce, Pregel, etc.) are cyclical resource utilization patterns that are highly synchronized across different resource types as well as the workers in a cluster. In Infrastructure as a Service settings, cloud providers do not exploit this characteristic to better manage VMs because they view VMs as \\'black boxes.\\' We present TideWatch, a system that automatically identifies cyclicality and similarity in running VMs. TideWatch predicts period lengths of most VMs in Hadoop workloads within 9% of actual iteration boundaries and successfully classifies up to 95% of running VMs as participating in the appropriate Hadoop cluster. Furthermore, we show how TideWatch can be used to improve the timing of VM migrations, reducing both migration time and network impact by over 50% when compared to a random approach. © 2014 IEEE.

Correcting GRACE gravity fields for ocean tide effects

DEFF Research Database (Denmark)

Knudsen, Per; Andersen, Ole Baltazar

2002-01-01

[1] The GRACE mission will be launch in early 2002 and will map the Earth's gravity fields and its variations with unprecedented accuracy during its 5-year lifetime. Unless ocean tide signals and their load upon the solid earth are removed from the GRACE data, their long period aliases obscure more...... tide model if altimetry corrected for inverted barometer effects was used in its derivation. To study the temporal characteristics of the ocean tidal constituents when sampled by GRACE, approximate alias frequencies were derived assuming a sampling of half a sidereal day. Those results show...

Tides and sea-level variability

Digital Repository Service at National Institute of Oceanography (India)

Shetye, S.R.; Suresh, I.; Sundar, D.

of the gravitational pull of the Moon and the Sun exerted on the waters of the ocean as the three-body system consisting of the Earth, Moon, and Sun moves in a stable configuration under the influence of the gravitational pull of one another. Tides at any location...

Microbial community analysis of a coastal hot spring in Kagoshima, Japan, using molecular- and culture-based approaches.

Science.gov (United States)

Nishiyama, Minako; Yamamoto, Shuichi; Kurosawa, Norio

2013-08-01

Ibusuki hot spring is located on the coastline of Kagoshima Bay, Japan. The hot spring water is characterized by high salinity, high temperature, and neutral pH. The hot spring is covered by the sea during high tide, which leads to severe fluctuations in several environmental variables. A combination of molecular- and culture-based techniques was used to determine the bacterial and archaeal diversity of the hot spring. A total of 48 thermophilic bacterial strains were isolated from two sites (Site 1: 55.6°C; Site 2: 83.1°C) and they were categorized into six groups based on their 16S rRNA gene sequence similarity. Two groups (including 32 isolates) demonstrated low sequence similarity with published species, suggesting that they might represent novel taxa. The 148 clones from the Site 1 bacterial library included 76 operational taxonomy units (OTUs; 97% threshold), while 132 clones from the Site 2 bacterial library included 31 OTUs. Proteobacteria, Bacteroidetes, and Firmicutes were frequently detected in both clone libraries. The clones were related to thermophilic, mesophilic and psychrophilic bacteria. Approximately half of the sequences in bacterial clone libraries shared <92% sequence similarity with their closest sequences in a public database, suggesting that the Ibusuki hot spring may harbor a unique and novel bacterial community. By contrast, 77 clones from the Site 2 archaeal library contained only three OTUs, most of which were affiliated with Thaumarchaeota.

Twenty Years of Progress on Global Ocean Tides: The Impact of Satellite Altimetry

Science.gov (United States)

Egbert, Gary; Ray, Richard

2012-01-01

At the dawn of the era of high-precision altimetry, before the launch of TOPEX/Poseidon, ocean tides were properly viewed as a source of noise--tidal variations in ocean height would represent a very substantial fraction of what the altimeter measures, and would have to be accurately predicted and subtracted if altimetry were to achieve its potential for ocean and climate studies. But to the extent that the altimetry could be severely contaminated by tides, it also represented an unprecedented global-scale tidal data set. These new data, together with research stimulated by the need for accurate tidal corrections, led to a renaissance in tidal studies in the oceanographic community. In this paper we review contributions of altimetry to tidal science over the past 20 years, emphasizing recent progress. Mapping of tides has now been extended from the early focus on major constituents in the open ocean to include minor constituents, (e.g., long-period tides; non-linear tides in shelf waters, and in the open ocean), and into shallow and coastal waters. Global and spatially local estimates of tidal energy balance have been refined, and the role of internal tide conversion in dissipating barotropic tidal energy is now well established through modeling, altimetry, and in situ observations. However, energy budgets for internal tides, and the role of tidal dissipation in vertical ocean mixing remain controversial topics. Altimetry may contribute to resolving some of these important questions through improved mapping of low-mode internal tides. This area has advanced significantly in recent years, with several global maps now available, and progress on constraining temporally incoherent components. For the future, new applications of altimetry (e.g., in the coastal ocean, where barotropic tidal models remain inadequate), and new mission concepts (studies of the submesoscale with SWOT, which will require correction for internal tides) may bring us full circle, again pushing

Bacterioplancton in different tides of the Perequê tidal creek, Pontal do Sul, Paraná, Brazil Bacterioplâncton em diferentes marés da gamboa do Perequê, Pontal do Sul, Paraná, Brasil

Directory of Open Access Journals (Sweden)

Hedda Elisabeth Kolm

2003-06-01

Full Text Available The influence of tidal phase on bacteria abundance in surface waters was studied in five stations along the Perequê tidal creek (Paraná State, Brazil, at spring and neap low and high tides in July 1999. The stations were located from the mouth (St.1 to the creek's head (St. 5. The following parameters were analyzed: salinity, temperature, pH, dissolved oxygen, total carbon dioxide, seston, particulate organic matter, pluviosity, chlorophyll "a", total heterotrophic bacteria, bacterial biomass, cultivable heterotrophic aerobic halophilic and halophobic bacteria, total coliforms and Escherichia coli. The results showed that the highest values of salinity, pH and dissolved oxygen at stations 1 to 4 were registered during the spring high tide. The amount of total heterotrophic bacteria was directly proportional to seston and chlorophyl values at stations 2 and 3 during low tide of July 28, and at station 5 during high tide of the same day. The values of cultivable heterotrophic aerobic halophilic and halophobic bacteria, total coliforms and E. coli, were directly correlated with particulate organic matter and pluviosity. The largest of these values were registered during the neap low tide of July 6. This period was characterized by high precipitation, which may have influenced the bacterial number variation. During the neap high tide and, sporadically, during the neap and spring low tide, the lowest values of total heterotrophic bacteria and bacterial biomass were registered. The results showed great influence of the tide on the bacteria at stations 1 to 4, but not at station 5.Com o objetivo de verificar a influência da maré sobre as bactérias foram realizadas coletas de águas superficiais em cinco pontos desde a desembocadura da gamboa (Est. 1 até o seu final (Est. 5 ao longo da Gamboa do Perequê (Estado do Paraná, Brasil, durante as preamares e baixa-mares de sizígia e quadratura em julho de 1999. Foram avaliados os seguintes par

On the Temporal Variability of Low-Mode Internal Tides in the Deep Ocean

Science.gov (United States)

Ray, Richard D.; Zaron, E. D.

2010-01-01

In situ measurements of internal tides are typically characterized by high temporal variability, with strong dependence on stratification, mesoscale eddies, and background currents commonly observed. Thus, it is surprising to find phase-locked internal tides detectable by satellite altimetry. An important question is how much tidal variability is missed by altimetry. We address this question in several ways. We subset the altimetry by season and find only very small changes -- an important exception being internal tides in the South China Sea where we observe strong seasonal dependence. A wavenumber-domain analysis confirms that throughout most of the global ocean there is little temporal variability in altimetric internal-tide signals, at least in the first baroclinic mode, which is the mode that dominates surface elevation. The analysis shows higher order modes to be significantly more variable. The results of this study have important practical implications for the anticipated SWOT wide-swath altimeter mission, for which removal of internal tide signals is critical for observing non-tidal submesoscale phenomena.

Partly standing internal tides in a dendritic submarine canyon observed by an ocean glider

Science.gov (United States)

Hall, Rob A.; Aslam, Tahmeena; Huvenne, Veerle A. I.

2017-08-01

An autonomous ocean glider is used to make the first direct measurements of internal tides within Whittard Canyon, a large, dendritic submarine canyon system that incises the Celtic Sea continental slope and a site of high benthic biodiversity. This is the first time a glider has been used for targeted observations of internal tides in a submarine canyon. Vertical isopycnal displacement observations at different stations fit a one-dimensional model of partly standing semidiurnal internal tides - comprised of a major, incident wave propagating up the canyon limbs and a minor wave reflected back down-canyon by steep, supercritical bathymetry near the canyon heads. The up-canyon internal tide energy flux in the primary study limb decreases from 9.2 to 2.0 kW m-1 over 28 km (a dissipation rate of 1 - 2.5 ×10-7 Wkg-1), comparable to elevated energy fluxes and internal tide driven mixing measured in other canyon systems. Within Whittard Canyon, enhanced mixing is inferred from collapsed temperature-salinity curves and weakened dissolved oxygen concentration gradients near the canyon heads. It has previously been hypothesised that internal tides impact benthic fauna through elevated near-bottom current velocities and particle resuspension. In support of this, we infer order 20 cm s-1 near-bottom current velocities in the canyon and observe high concentrations of suspended particulate matter. The glider observations are also used to estimate a 1 °C temperature range and 12 μmol kg-1 dissolved oxygen concentration range, experienced twice a day by organisms on the canyon walls, due to the presence of internal tides. This study highlights how a well-designed glider mission, incorporating a series of tide-resolving stations at key locations, can be used to understand internal tide dynamics in a region of complex topography, a sampling strategy that is applicable to continental shelves and slopes worldwide.

Three-Dimensional Structures of Thermal Tides Simulated by a Venus GCM

Science.gov (United States)

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

2018-02-01

Thermal tides in the Venus atmosphere are investigated by using a GCM named as AFES-Venus. The three-dimensional structures of wind and temperature associated with the thermal tides obtained in our model are fully examined and compared with observations. The result shows that the wind and temperature distributions of the thermal tides depend complexly on latitude and altitude in the cloud layer, mainly because they consist of vertically propagating and trapped modes with zonal wave numbers of 1-4, each of which predominates in different latitudes and altitudes under the influence of mid- and high-latitude jets. A strong circulation between the subsolar and antisolar (SS-AS) points, which is equivalent to a diurnal component of the thermal tides, is superposed on the superrotation. The vertical velocity of SS-AS circulation is about 10 times larger than that of the zonal-mean meridional circulation (ZMMC) in 60-70 km altitudes. It is suggested that the SS-AS circulation could contribute to the material transport, and its upward motion might be related to the UV dark region observed in the subsolar and early afternoon regions in low latitudes. The terdiurnal and quaterdiurnal tides, which may be excited by the nonlinear interactions among the diurnal and semidiurnal tides in middle and high latitudes, are detected in the solar-fixed Y-shape structure formed in the vertical wind field in the upper cloud layer. The ZMMC is weak and has a complex structure in the cloud layer; the Hadley circulation is confined to latitudes equatorward of 30°, and the Ferrel-like one appears in middle and high latitudes.

Exploring Marine Science through the University of Delaware's TIDE camp

Science.gov (United States)

Veron, D. E.; Newton, F. A.; Veron, F.; Trembanis, A. C.; Miller, D. C.

2012-12-01

For the past five years, the University of Delaware has offered a two-week, residential, summer camp to rising sophomores, juniors, and seniors who are interested in marine science. The camp, named TIDE (Taking an Interest in Delaware's Estuary) camp, is designed to introduce students to the breadth of marine science while providing them with a college experience. Campers participate in a variety of academic activities which include classroom, laboratory, and field experiences, as well as numerous social activities. Two unique features of this small, focused camp is the large number of university faculty that are involved, and the ability of students to participate in ongoing research projects. At various times students have participated in fish and dolphin counts, AUV deployment, wind-wave tank experiments, coastal water and beach studies, and ROV activities. In addition, each year campers have participated in a local service project. Through communication with former TIDE participants, it is clear that this two-week, formative experience plays a large role in students choice of major when entering college.2012 Tide Camp - Salt marsh in southern Delaware 2012 Tide Camp - Field trip on a small boat

Atmospheric tides on Neptune

International Nuclear Information System (INIS)

Dement'ev, M.S.; Morozhenko, A.V.

1989-01-01

The dependence of the equivalent width of the methane absorption band at 619 nm in the Neptune's spectrum upon the Triton's orbital position is discovered. It is assumed that observed changes of the equivalent width of the band and colour index (J - K) (Belton et al., 1981; Brown et al., 1981; Cruikshank, 1978) are due to atmospheric tides (period 2 d .9375) and Neptune's rotation (period 10 h .14)

A Plan to Develop a Red Tide Warning System for Seawater Desalination Process Management

Science.gov (United States)

Kim, Tae Woo; Yun, Hong Sik

2017-04-01

The holt of the seawater desalination process for fifty five days due to the eight-month long red tide in 2008 in the Persian Gulf, the Middle East, had lost about 10 billion KRW. The POSCO Seawater Desalination facility, located in Gwangyang Bay Area in the Southern Sea, has produced 30,000 tons of fresh water per day since 2014. Since there has been an incident of red time in the area for three months in August, 2012, it is necessary to establish a warning system for red tide that threatens the stable operation of the seawater desalination facility. A red tide warning system can offer the seawater desalination facility manager customized services on red tide information and potential red tide inflow to the water intake. This study aimed to develop a red tide warning system in Gwangyang Bay Area by combining RS, modeling and monitoring technologies, which provides red tide forecasting information with which to effectively control the seawater desalination process. Using the proposed system, the seawater desalination facility manager can take phased measures to cope with the inflow of red tide. ACKNOWLEDGMENTS This research was supported by a grant(16IFIP-C088924-03) from Industrial Facilities & Infrastructure Research Program funded by Ministry of Land, Infrastructure and Transport(MOLIT) of the Korea government and the Korea Agency for Infrastructure Technology Advancement (KAIA). This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(NRF-2014R1A1A2054975).

Evaluation of Ocean Tide Models Used for Jason-2 Altimetry Corrections

DEFF Research Database (Denmark)

Fok, H.S.; Baki Iz, H.; Shum, C. K.

2010-01-01

It has been more than a decade since the last comprehensive accuracy assessment of global ocean tide models. Here, we conduct an evaluation of the barotropic ocean tide corrections, which were computed using FES2004 and GOT00.2, and other models on the Jason-2 altimetry Geophysical Data Record (G...

On Measurements of the Tide at Churchill, Hudson Bay

Science.gov (United States)

Ray, Richard D.

2016-01-01

Since the late 1990s the semi-diurnal tide at Churchill, on the western shore of Hudson Bay, has been decreasing in amplitude, with M(sub 2) amplitudes falling from approximately 154 cm in 1998 to 146 cm in 2012 and 142 cm in 2014. There has been a corresponding small increase in phase lag. Mean low water, decreasing throughout most of the twentieth century, has levelled off. Although the tidal changes could reflect merely a malfunctioning tide gauge, the fact that there are no other measurements in the region and the possibility that the tide is revealing important environmental changes calls for serious investigation. Satellite altimeter measurements of the tide in Hudson Bay are complicated by the seasonal ice cover; at most locations less than 40% of satellite passes return valid ocean heights and even those can be impacted by errors from sea ice. Because the combined TOPEX/Poseidon, Jason-1, and Jason-2 time series is more than 23 years long, it is now possible to obtain sufficient data at crossover locations near Churchill to search for tidal changes. The satellites sense no changes in M(sub 2) that are comparable to the changes seen at the Churchill gauge. The changes appear to be localized to the harbour, or to the Churchill River, or to the gauge itself.

Thermal Tides During the 2001 Martian Global-Scale Dust Storm

Science.gov (United States)

Guzewich, Scott D.; Wilson, R. John; McConnochie, Timothy H.; Toigo, Anthony D.; Bandfield, Donald J.; Smith, Michael D.

2014-01-01

The 2001 (Mars Year 25) global dust storm radically altered the dynamics of the Martian atmosphere. Using observations from the Thermal Emission Spectrometer onboard the Mars Global Surveyor spacecraft and Mars WRF general circulation model simulations, we examine the changes to thermal tides and planetary waves caused by the storm. We find that the extratropical diurnal migrating tide is dramatically enhanced during the storm, particularly in the southern hemisphere, reaching amplitudes of more than 20 K. The tropical diurnal migrating tide is weakened to almost undetectable levels. The diurnal Kelvin waves are also significantly weakened, particularly during the period of global expansion at Ls=200deg-210deg. In contrast, the westward propagating diurnal wavenumber 2 tide strengthens to 4-8 K at altitudes above 30km. The wavenumber 1 stationary wave reaches amplitudes of 10-12 K at 50deg-70degN, far larger than is typically seen during this time of year. The phase of this stationary wave and the enhancement of the diurnal wavenumber 2 tide appear to be responses to the high-altitude westward propagating equatorial wavenumber 1 structure in dust mixing ratio observed during the storm in previous works. This work provides a global picture of dust storm wave dynamics that reveals the coupling between the tropics and high-latitude wave responses. We conclude that the zonal distribution of thermotidal forcing from atmospheric aerosol concentration is as important to understanding the atmospheric wave response as the total global mean aerosol optical depth.

Effects of Long Period Ocean Tides on the Earth's Rotation

Science.gov (United States)

Gross, Richard S.; Chao, Ben F.; Desai, Shailen D.

1996-01-01

The spectra of polar motion excitation functions exhibit enhanced power in the fortnightly tidal band. This enhanced power is attributed to ocean tidal excitation. Ocean tide models predict polar motion excitation effects that differ with each other, and with observations, by factors as large as 2-3. There is a need for inproved models for the effect of long-period ocean tides on Earth's rotation.

Mapping nonlinear shallow-water tides: a look at the past and future

DEFF Research Database (Denmark)

Andersen, Ole Baltazar; Egbert, G.D.; Erofeeva, S.Y.

2006-01-01

advanced by the pioneering researches of Christian Le Provost who employed analytical theory, physical modeling, and numerical modeling in many extensive studies, especially of the tides of the English Channel. Le Provost's complementary work with satellite altimetry motivates our attempts to merge...... these two interests. After a brief review, we describe initial steps toward the assimilation of altimetry into models of nonlinear tides via generalized inverse methods. A series of barotropic inverse solutions is computed for the M-4 tide over the northwest European Shelf. Future applications of altimetry...

River flow controls on tides an tide-mean water level profiles in a tidel freshwater river

NARCIS (Netherlands)

Sassi, M.G.; Hoitink, A.J.F.

2013-01-01

[1] Tidal rivers feature oscillatory and steady gradients in the water surface, controlled by interactions between river flow and tides. The river discharge attenuates the tidal motion, and tidal motion increases tidal-mean friction in the river, which may act as a barrier to the river discharge.

Multi-satellite ocean tide modelling - the K-1 constituent

DEFF Research Database (Denmark)

Andersen, Ole Baltazar; Knudsen, Per

1997-01-01

All major ocean tide constituents are aliased into signals with periods less than 90 days from TOPEX/POSEIDON altimetry, except the K-1 constituent. The aliased K-1 has a period of 173 days. Consequently, it might be confounded with height variations caused by the semiannual cycle having a period......, where the presence of crossing tracks cannot separate K-1 from the semiannual signal from TOPEX/POSEIDON, the importance of including ERS-1 and GEOSAT observations was demonstrated. A comparison with 29 pelagic and coastal tide gauges in the Southern Ocean south of 50 degrees S gave 5.59 (M-2), 2.27 (S......-2) and 5.04 (K-1) cm RMS agreement for FES95.1 ocean tide model. The same comparison for the best empirical estimated constituents based on TOPEX/POSEIDON + ERS-1 + GEOSAT gave 4.32, 2.21, and 4.29 cm for M-2, S-2 and K-1, respectively....

Tides Stabilize Deltas until Humans Interfere

Science.gov (United States)

Hoitink, T.; Zheng Bing, W.; Vermeulen, B.; Huismans, Y.; Kastner, K.

2017-12-01

Despite global concerns about river delta degradation caused by extraction of natural resources, sediment retention by reservoirs and sea-level rise, human activity in the world's largest deltas intensifies. In this review, we argue that tides tend to stabilize deltas until humans interfere. Under natural circumstances, delta channels subject to tides are more stable than their fluvial-dominated counterparts. The oscillatory tidal flow counteracts the processes responsible for bank erosion, which explains why unprotected tidal channels migrate only slowly. Peak river discharges attenuate the tides, which creates storage space to accommodate the extra river discharge during extreme events and as a consequence, reduce flood risk. With stronger tides, the river discharge is being distributed more evenly over the various branches in a delta, preventing silting up of smaller channels. Human interference in deltas is massive. Storm surge barriers are constructed, new land is being reclaimed and large-scale sand excavation takes place, to collect building material. Evidence from deltas around the globe shows that in human-controlled deltas the tidal motion often plays a destabilizing role. In channels of the Rhine-Meuse Delta, some 100 scour holes are identified, which relates to the altered tidal motion after completion of a storm surge barrier. Sand mining has led to widespread river bank failures in the tidally-influenced Mekong Delta. The catastrophic flood event in the Gauges-Brahmaputra Delta by Cyclone Aila, which caused the inundation of an embanked polder area for over two years, was preceded by river bank erosion at the mouths of formal tidal channels that were blocked by the embankment. Efforts to predict the developments of degrading deltas are few. Existing delta models are capable of reproducing expanding deltas, which is essentially a matter of simulating the transport of sediment from source in a catchment to the sink in a delta. Processes of soil

Consortial brown tide − picocyanobacteria blooms in Guantánamo Bay, Cuba

Science.gov (United States)

Hall, Nathan S; Litaker, R. Wayne; Kenworthy, W. Judson; Vandersea, Mark W.; Sunda, William G.; Reid, James P.; Slone, Daniel H.; Butler, Susan M.

2018-01-01

A brown tide bloom of Aureoumbra lagunensis developed in Guantánamo Bay, Cuba during a period of drought in 2013 that followed heavy winds and rainfall from Hurricane Sandy in late October 2012. Based on satellite images and water turbidity measurements, the bloom appeared to initiate in January 2013. The causative species (A. lagunensis) was confirmed by microscopic observation, and pigment and genetic analyses of bloom samples collected on May 28 of that year. During that time, A. lagunensis reached concentrations of 900,000 cells ml−1 (28 ppm by biovolume) in the middle portion of the Bay. Samples could not be collected from the northern (Cuban) half of the Bay because of political considerations. Subsequent sampling of the southern half of the Bay in November 2013, April 2014, and October 2014 showed persistent lower concentrations of A. lagunensis, with dominance shifting to the cyanobacterium Synechococcus (up to 33 ppm in April), an algal group that comprised a minor bloom component on May 28. Thus, unlike the brown tide bloom in Laguna Madre, which lasted 8 years, the bloom in Guantánamo Bay was short-lived, much like recent blooms in the Indian River, Florida. Although hypersaline conditions have been linked to brown tide development in the lagoons of Texas and Florida, observed euhaline conditions in Guantánamo Bay (salinity 35–36) indicate that strong hypersalinity is not a requirement for A. lagunensis bloom formation. Microzooplankton biomass dominated by ciliates was high during the observed peak of the brown tide, and ciliate abundance was high compared to other systems not impacted by brown tide. Preferential grazing by zooplankton on non-brown tide species, as shown in A. lagunensis blooms in Texas and Florida, may have been a factor in the development of the Cuban brown tide bloom. However, subsequent selection of microzooplankton capable of utilizing A. lagunensis as a primary food source may have contributed to the

Development and Use of Tide Models in Alaska Supporting VDatum and Hydrographic Surveying

Directory of Open Access Journals (Sweden)

Lei Shi

2014-03-01

Full Text Available National Oceanic and Atmospheric Administration’s National Ocean Service uses observations, hydrodynamic models and interpolation techniques to develop many of its products and services. We examine how two projects, computation of tidal datums for vertical datum transformation and the estimation of tidal characteristics for hydrographic surveys, are being developed in Alaska and how they may be more seamlessly integrated. Preliminary VDatum development for Alaska is in progress for the Alaska Panhandle through the setup of a high resolution tide model that will be used to compute spatially varying tidal datums. Tide models such as these can be used for other projects that traditionally rely on estimation of tides in between data locations, such as the planning for hydrographic surveys that need correctors to adjust bathymetry to the chart datum. We therefore also examine how an existing model in western Alaska can be used for better supporting hydrographic survey planning. The results show that integration of tide models with nearshore observations can provide improved information for these correctors and future work will further evaluate this methodology with existing VDatum tide models.

Numerical study of the effect of earth tides on recurring short-term slow slip events

Science.gov (United States)

Matsuzawa, T.; Tanaka, Y.; Shibazaki, B.

2017-12-01

Short-term slow slip events (SSEs) in the Nankai region are affected by earth tides (e.g., Nakata et al., 2008; Ide and Tanaka, 2014; Yabe et al., 2015). The effect of tidal stress on the SSEs is also examined numerically (e.g., Hawthorne and Rubin, 2013). In our previous study (Matsuzawa et al., 2017, JpGU-AGU), we numerically simulated SSEs in the Shikoku region, and reported that tidal stress makes the variance of recurrence intervals of SSEs smaller in relatively isolated SSE regions. However, the reason of such stable recurrence was not clear. In this study, we examine the tidal effect on short-term SSEs based on a flat plate and a realistic plate model (e.g., Matsuzawa et al., 2013, GRL). We adopt a rate- and state-dependent friction law (RS-law) with cutoff velocities as in our previous studies (Matsuzawa et al., 2013). We assume that (a-b) value in the RS-law is negative within the short-term SSE region, and positive outside the region. In a flat plate model, the short-term SSE region is a circular patch with the radius of 6 km. In a realistic plate model, the short-term SSE region is based on the actual distribution of low-frequency tremor. Low effective normal stress is assumed at the depth of SSEs. Calculating stress change by earth tides as in Yabe et al., (2015), we examine the stress perturbation by two different earth tides with the period of semidiurnal (M2) and fortnight (Mf) tide in this study. In the result of a flat plate case, amplitude of SSEs becomes smaller just after the slip at whole simulated area. Recurring SSEs become clear again within one year in the case with tides (M2 or Mf), while the recurrence becomes clear after seven years in the case without tides. Interestingly, the effect of the Mf tide is similar to the case with the M2 tide, even though the amplitude of the Mf tide (0.01 kPa) is two-order smaller than that of the M2 tide. In the realistic plate model of Shikoku, clear recurrence of short-term SSEs is found earlier than the

Behaviour of aluminium, silicon and iron in Tapi Estuary

Digital Repository Service at National Institute of Oceanography (India)

Sharma, P.; Zingde, M.D.

as compared to that associated with the end members. Higher, percentage of removal during spring tides as compared to neaps was attributed to large scale disturbance of bed sediment by high energy spring tides. An inverse relationship between dissolved Al...

Investigations in Marine Chemistry: Tide Pool Ecology.

Science.gov (United States)

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)

EFFECTS OF OCEAN TIDE MODELS ON GNSS-ESTIMATED ZTD AND PWV IN TURKEY

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G. Gurbuz

2015-12-01

Full Text Available 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

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

Science.gov (United States)

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.

NOAA NCCOS: New England Red Tide Research

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Alexandrium blooms are one of several algal bloom types often called "red tides," but more correctly referred to as Harmful Algal Blooms (HABs). Alexandrium produces...

POET: Planetary Orbital Evolution due to Tides

Science.gov (United States)

Penev, Kaloyan

2014-08-01

POET (Planetary Orbital Evolution due to Tides) calculates the orbital evolution of a system consisting of a single star with a single planet in orbit under the influence of tides. The following effects are The evolutions of the semimajor axis of the orbit due to the tidal dissipation in the star and the angular momentum of the stellar convective envelope by the tidal coupling are taken into account. In addition, the evolution includes the transfer of angular momentum between the stellar convective and radiative zones, effect of the stellar evolution on the tidal dissipation efficiency, and stellar core and envelope spins and loss of stellar convective zone angular momentum to a magnetically launched wind. POET can be used out of the box, and can also be extended and modified.

Acoustic observations of internal tides and tidal currents in shallow water.

Science.gov (United States)

Turgut, Altan; Mignerey, Peter C; Goldstein, David J; Schindall, Jeffrey A

2013-04-01

Significant acoustic travel-time variability and frequency shifts of acoustic intensity level curves in broadband signal spectrograms were measured in the East China Sea during the summer of 2008. The broadband pulses (270-330 Hz) were transmitted from a fixed source and received at a bottomed horizontal array, located at the 33 km range. The acoustic intensity level curves of the received signals indicate regular frequency shifts that are well correlated with the measured internal tides. Similarly, regular travel-time shifts of the acoustic mode arrivals correlate well with the barotropic tides and can be explained by tidal currents along the acoustic propagation track. These observations indicate the potential of monitoring internal tides and tidal currents using low-frequency acoustic signals propagating at long ranges.

The Contribution of Io-Raised Tides to Europa's Diurnally-Varying Surface Stresses

Science.gov (United States)

Rhoden, Alyssa Rose; Hurford, Terry A,; Manga, Michael

2011-01-01

Europa's icy surface records a rich history of geologic activity, Several features appear to be tectonic in origin and may have formed in response to Europa's daily-varying tidal stress [I]. Strike-slip faults and arcuate features called cycloids have both been linked to the patterns of stress change caused by eccentricity and obliquity [2J[3]. In fact, as Europa's obliquity has not been directly measured, observed tectonic patterns arc currently the best indicators of a theoretically supported [4] non-negligible obliquity. The diurnal tidal stress due to eccentricity is calculated by subtracting the average (or static) tidal shape of Europa generated by Jupiter's gravitational field from the instantaneous shape, which varies as Europa moves through its eccentric orbit [5]. In other words, it is the change of shape away from average that generates tidal stress. One might expect tidal contributions from the other large moons of Jupiter to be negligible given their size and the height of the tides they raise on Europa versus Jupiter's mass and the height of the tide it raises on Europa, However, what matters for tidally-induced stress is not how large the lo-raised bulge is compared to the Jupiter-raised bulge but rather the differences bet\\Veen the instantaneous and static bulges in each case. For example, when Europa is at apocenter, Jupiter raises a tide 30m lower than its static tide. At the same time, 10 raises a tide about 0.5m higher than its static tide. Hence, the change in Io's tidal distortion is about 2% of the change in the Jovian distortion when Europa is at apocenter

Determination of ocean tides from the first year of TOPEX/POSEIDON altimeter measurements

Science.gov (United States)

Ma, X. C.; Shum, C. K.; Eanes, R. J.; Tapley, B. D.

1994-01-01

An improved geocentric global ocean tide model has been determined using 1 year of TOPEX/POSEIDON altimeter measurements to provide corrections to the Cartwright and Ray (1991) model (CR91). The corrections were determined on a 3 deg x 3 deg grid using both the harmonic analysis method and the response method. The two approaches produce similar solutions. The effect on the tide solution of simultaneously adjusting radial orbit correction parameters using altimeter measurements was examined. Four semidiurnal (N(sub 2), M(sub 2), S(sub 2) and K(sub 2)), four diurnal (Q(sdub 1), O(sub 1), P(sub 1), and K(sub 1)), and three long-period (S(sub sa), M(sub m), and M(sub f)) constituents, along with the variations at the annual frequency, were included in the harmomnic analysis solution. The observed annual variations represents the first global measurement describing accurate seasonal changes of the ocean during an El Nino year. The corrections to the M(sub 2) constituent have an root mean square (RMS) of 3.6 cm and display a clear banding pattern with regional highs and lows reaching 8 cm. The improved tide model reduces the weighted altimeter crossover residual from 9.8 cm RMS, when the CR91 tide model is used, to 8.2 cm on RMS. Comparison of the improved model to pelagic tidal constants determined from 80 tide gauges gives RMS differences of 2.7 cm for M(sub 2) and 1.7 cm for K(sub 1). Comparable values when the CR91 model is used are 3.9 cm and 2.0 cm, respectively. Examination of TOPEX/POSEIDON sea level anomaly variations using the new tide model further confirms that the tide model has been improved.

Impact of large-scale tides on cosmological distortions via redshift-space power spectrum

Science.gov (United States)

Akitsu, Kazuyuki; Takada, Masahiro

2018-03-01

Although large-scale perturbations beyond a finite-volume survey region are not direct observables, these affect measurements of clustering statistics of small-scale (subsurvey) perturbations in large-scale structure, compared with the ensemble average, via the mode-coupling effect. In this paper we show that a large-scale tide induced by scalar perturbations causes apparent anisotropic distortions in the redshift-space power spectrum of galaxies in a way depending on an alignment between the tide, wave vector of small-scale modes and line-of-sight direction. Using the perturbation theory of structure formation, we derive a response function of the redshift-space power spectrum to large-scale tide. We then investigate the impact of large-scale tide on estimation of cosmological distances and the redshift-space distortion parameter via the measured redshift-space power spectrum for a hypothetical large-volume survey, based on the Fisher matrix formalism. To do this, we treat the large-scale tide as a signal, rather than an additional source of the statistical errors, and show that a degradation in the parameter is restored if we can employ the prior on the rms amplitude expected for the standard cold dark matter (CDM) model. We also discuss whether the large-scale tide can be constrained at an accuracy better than the CDM prediction, if the effects up to a larger wave number in the nonlinear regime can be included.

Characteristics of Arctic tides at CANDAC-PEARL (80 N, 86 W) and Svalbard (78 N, 16 E) for 2006-2009. Radar observations and comparisons with the model CMAM-DAS

Energy Technology Data Exchange (ETDEWEB)

Manson, A.H.; Meek, C.E.; Xu, X. [Saskatchewan Univ., Saskatoon (Canada). Inst. of Space and Atmospheric Studies; Aso, T.; Tsutsumi, M. [National Institute for Polar Research, Tokyo (Japan); Drummond, J.R. [Dalhousie Univ., Halifax (Canada). Physics and Atmospheric Science Dept.; Hall, C.M. [Tromsoe Univ. (Norway). Tromsoe Geophysical Observatory; Hocking, W.K. [Western Onatario Univ., London (Canada). Physics and Astronomy Dept.; Ward, W.E. [New Brunswick Univ., Fredericton (Canada). Physics and Astronomy Dept.

2011-07-01

Operation of a Meteor Radar (MWR) at Eureka, Ellesmere Island (80 N, 86 W) began in February 2006: this is the location of the Polar Environmental and Atmospheric Research Laboratory (PEARL), operated by the ''Canadian Network for the Detection of Atmospheric Change'' (CANDAC). The first 36 months of tidal wind data (82-97 km) are here combined with contemporaneous tides from the Meteor Radar (MWR) at Adventdalen, Svalbard (78 N, 16 E), to provide the first significant evidence for interannual variability (IAV) of the High Arctic's diurnal and semidiurnal migrating (MT) and non-migrating tides (NMT). The three-year monthly means for both diurnal (DT) and semi-diurnal (SDT) winds demonstrate significantly different amplitudes and phases at Eureka and Svalbard. Typically the summer-maximizing DT is much larger ({proportional_to}24ms{sup -1} at 97 km) at Eureka, while the Svalbard tide (5-24ms{sup -1} at 97 km) is almost linear (north-south) rather than circular. Interannual variations are smallest in the summer and autumn months. The High Arctic SDT has maxima centred on August/September, followed in size by the winter features; and is much larger at Svalbard (24ms{sup -1} at 97 km, versus 14-18ms{sup -1} in central Canada). Depending on the location, the IAV are largest in spring/winter (Eureka) and summer/autumn (Svalbard). Fitting of wave-numbers for the migrating and nonmigrating tides (MT, NMT) determines dominant tides for each month and height. Existence of NMT is consistent with nonlinear interactions between migrating tides and (quasi) stationary planetary wave (SPW) S =1 (SPW1). For the diurnal oscillation, NMT s = 0 for the east-west (EW) wind component dominates (largest tide) in the late autumn and winter (November-February); and s =+2 is frequently seen in the north-south (NS) wind component for the same months. The semi-diurnal oscillation's NMT s =+1 dominates from March to June/July. There are patches of s =+3 and +1, in

Vertical land motion along the coast of Louisiana: Integrating satellite altimetry, tide gauge and GPS

Science.gov (United States)

Dixon, T. H.; A Karegar, M.; Uebbing, B.; Kusche, J.; Fenoglio-Marc, L.

2017-12-01

Coastal Louisiana is experiencing the highest rate of relative sea-level rise in North America due to the combination of sea-level rise and subsidence of the deltaic plain. The land subsidence in this region is studied using various techniques, with continuous GPS site providing high temporal resolution. Here, we use high resolution tide-gauge data and advanced processing of satellite altimetry to derive vertical displacements time series at NOAA tide-gauge stations along the coast (Figure 1). We apply state-of-the-art retracking techniques to process raw altimetry data, allowing high accuracy on range measurements close to the coast. Data from Jason-1, -2 and -3, Envisat, Saral and Cryosat-2 are used, corrected for solid Earth tide, pole tide and tidal ocean loading, using background models consistent with the GPS processing technique. We reprocess the available GPS data using precise point positioning and estimate the rate uncertainty accounting for correlated noise. The displacement time series are derived by directly subtracting tide-gauge data from the altimetry sea-level anomaly data. The quality of the derived displacement rates is evaluated in Grand Isle, Amerada Pass and Shell Beach where GPS data are available adjacent to the tide gauges. We use this technique to infer vertical displacement at tide gauges in New Orleans (New Canal Station) and Port Fourchon and Southwest Pass along the coastline.

Review of Florida Red Tide and Human Health Effects

Science.gov (United States)

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.

2010-01-01

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. PMID:21218152

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

Science.gov (United States)

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.

Measuring storm tide and high-water marks caused by Hurricane Sandy in New York: Chapter 2

Science.gov (United States)

Simonson, Amy E.; Behrens, Riley

2015-01-01

In response to Hurricane Sandy, personnel from the U.S. Geological Survey (USGS) deployed a temporary network of storm-tide sensors from Virginia to Maine. During the storm, real-time water levels were available from tide gages and rapid-deployment gages (RDGs). After the storm, USGS scientists retrieved the storm-tide sensors and RDGs and surveyed high-water marks. These data demonstrate that the timing of peak storm surge relative to astronomical tide was extremely important in southeastern New York. For example, along the south shores of New York City and western Suffolk County, the peak storm surge of 6–9 ft generally coincided with the astronomical high tide, which resulted in substantial coastal flooding. In the Peconic Estuary and northern Nassau County, however, the peak storm surge of 9 ft and nearly 12 ft, respectively, nearly coincided with normal low tide, which helped spare these communities from more severe coastal flooding.

THERMAL TIDES IN FLUID EXTRASOLAR PLANETS

International Nuclear Information System (INIS)

Arras, Phil; Socrates, Aristotle

2010-01-01

Asynchronous rotation and orbital eccentricity lead to time-dependent irradiation of the close-in gas giant exoplanets-the hot Jupiters. This time-dependent surface heating gives rise to fluid motions which propagate throughout the planet. We investigate the ability of this 'thermal tide' to produce a quadrupole moment which can couple to the stellar gravitational tidal force. While previous investigations discussed planets with solid surfaces, here we focus on entirely fluid planets in order to understand gas giants with small cores. The Coriolis force, thermal diffusion, and self-gravity of the perturbations are ignored for simplicity. First, we examine the response to thermal forcing through analytic solutions of the fluid equations which treat the forcing frequency as a small parameter. In the 'equilibrium tide' limit of zero frequency, fluid motion is present but does not induce a quadrupole moment. In the next approximation, finite frequency corrections to the equilibrium tide do lead to a nonzero quadrupole moment, the sign of which torques the planet away from synchronous spin. We then numerically solve the boundary value problem for the thermally forced, linear response of a planet with neutrally stratified interior and a stably stratified envelope. The numerical results find quadrupole moments in agreement with the analytic non-resonant result at a sufficiently long forcing period. Surprisingly, in the range of forcing periods of 1-30 days, the induced quadrupole moments can be far larger than the analytic result due to response of internal gravity waves which propagate in the radiative envelope. We discuss the relevance of our results for the spin, eccentricity, and thermal evolution of hot Jupiters.

Tides and the evolution of planetary habitability.

Science.gov (United States)

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.

Tides and tidal harmonics at Umbharat, Gujarat

Digital Repository Service at National Institute of Oceanography (India)

Suryanarayana, A.; Swamy, G.N.

A part of the data on tides recorded at Machiwada near Umbharat, Gulf of Cambay during April 1978 was subjected to harmonic analysis following the Admiralty procedure. The general tidal characteristics and the value of four major harmonic...

Observations of the Mf ocean tide from Geosat altimetry

Science.gov (United States)

Cartwright, David E.; Ray, Richard D.

1990-01-01

Zonal averages of the 13.66-day Mf tide are derived from one year of Geosat altimetry records. The orbit errors are reduced by 1/revolution corrections taken over long (several day) arcs. The short-period tides are removed using a model previously derived from the same data. The Mf zonal averages indicate definite nonequilibrium character at nearly all latitudes. The imaginary admittances indicate a Q of at least 8; such a value is consistent with a simplified theory of coupled gravitational and vorticity modes and suggests a value for Proudman's 'friction period' about 123 days.

Accurate Modelling of Surface Currents and Internal Tides in a Semi-enclosed Coastal Sea

Science.gov (United States)

Allen, S. E.; Soontiens, N. K.; Dunn, M. B. H.; Liu, J.; Olson, E.; Halverson, M. J.; Pawlowicz, R.

2016-02-01

The Strait of Georgia is a deep (400 m), strongly stratified, semi-enclosed coastal sea on the west coast of North America. We have configured a baroclinic model of the Strait of Georgia and surrounding coastal waters using the NEMO ocean community model. We run daily nowcasts and forecasts and publish our sea-surface results (including storm surge warnings) to the web (salishsea.eos.ubc.ca/storm-surge). Tides in the Strait of Georgia are mixed and large. The baroclinic model and previous barotropic models accurately represent tidal sea-level variations and depth mean currents. The baroclinic model reproduces accurately the diurnal but not the semi-diurnal baroclinic tidal currents. In the Southern Strait of Georgia, strong internal tidal currents at the semi-diurnal frequency are observed. Strong semi-diurnal tides are also produced in the model, but are almost 180 degrees out of phase with the observations. In the model, in the surface, the barotropic and baroclinic tides reinforce, whereas the observations show that at the surface the baroclinic tides oppose the barotropic. As such the surface currents are very poorly modelled. Here we will present evidence of the internal tidal field from observations. We will discuss the generation regions of the tides, the necessary modifications to the model required to correct the phase, the resulting baroclinic tides and the improvements in the surface currents.

SMLTM simulations of the diurnal tide: comparison with UARS observations

Directory of Open Access Journals (Sweden)

R. A. Akmaev

1997-09-01

Full Text Available Wind and temperature observations in the mesosphere and lower thermosphere (MLT from the Upper Atmosphere Research Satellite (UARS reveal strong seasonal variations of tides, a dominant component of the MLT dynamics. Simulations with the Spectral mesosphere/lower thermosphere model (SMLTM for equinox and solstice conditions are presented and compared with the observations. The diurnal tide is generated by forcing specified at the model lower boundary and by in situ absorption of solar radiation. The model incorporates realistic parameterizations of physical processes including various dissipation processes important for propagation of tidal waves in the MLT. A discrete multi-component gravity-wave parameterization has been modified to account for seasonal variations of the background temperature. Eddy diffusion is calculated depending on the gravity-wave energy deposition rate and stability of the background flow. It is shown that seasonal variations of the diurnal-tide amplitudes are consistent with observed variations of gravity-wave sources in the lower atmosphere.

Risk in Daily Newspaper Coverage of Red Tide Blooms in Southwest Florida

Science.gov (United States)

Li, Zongchao; Garrison, Bruce; Ullmann, Steven G.; Kirkpatrick, Barbara; Fleming, Lora E.; Hoagland, Porter

2015-01-01

This study investigated newspaper coverage of Florida red tide blooms in four metropolitan areas of Southwest Florida during a 25-year period, 1987-2012. We focused on how journalists framed red tide stories with respect to environmental risk, health risk, and economic risk. We determined risk to be a key factor in this news coverage, being an…

Effects of tidal cycles on shorebird distribution and foraging behaviour in a coastal tropical wetland: Insights for carrying capacity assessment

Science.gov (United States)

Fonseca, Juanita; Basso, Enzo; Serrano, David; Navedo, Juan G.

2017-11-01

Wetland loss has driven negative effects on biodiversity by a reduction in potential available habitats, directly impacting wetland-dependent species such as migratory shorebirds. At coastal areas where tidal cycles can restrict food access, the degree to which density of foraging birds is mediated by conspecific abundance or by the available areas is crucial to understanding patterns of bird distribution and wetland carrying capacity. We used the bathymetry of two sectors modeled with two numerical matrices to determine the availability of intertidal foraging areas in relation to tidal level (spring and neap tides), and this information was used to estimate shorebird density and foraging activity throughout the low-tide cycle in a tropical coastal lagoon in northwestern Mexico. Relative to spring tides, an 80% reduction in available foraging areas occurred during neap tides. Overall shorebird abundance was significantly reduced during neap tide periods, with differences between species. Densities of shorebirds increased during neap tides, particularly in one sector, and remained similar throughout the low-tide period (i.e. 4 h) either during spring or neap tides. Time spent foraging was consistently lower during neap-tides relative to spring-tides, especially for Long-billed curlew (44% reduction), Willet (37% reduction) and Black-necked stilt (29% reduction). These decreases in foraging activity when available habitats became reduced can hamper the opportunities of migratory shorebirds to reach their daily energy requirements to survive during the non-breeding season. This study shows that when intertidal habitats are severely reduced an important fraction of shorebird populations would probably be forced to find alternative areas to forage or increase foraging time during the night. Serving an essential function as top-predators, these results can have important implications on carrying capacity assessment for shorebirds at coastal wetlands.

Linear magnetic spring and spring/motor combination

Science.gov (United States)

Patt, Paul J. (Inventor); Stolfi, Fred R. (Inventor)

1991-01-01

A magnetic spring, or a spring and motor combination, providing a linear spring force characteristic in each direction from a neutral position, in which the spring action may occur for any desired coordinate of a typical orthogonal coordinate system. A set of magnets are disposed, preferably symmetrically about a coordinate axis, poled orthogonally to the desired force direction. A second set of magnets, respectively poled opposite the first set, are arranged on the sprung article. The magnets of one of the sets are spaced a greater distance apart than those of the other, such that an end magnet from each set forms a pair having preferably planar faces parallel to the direction of spring force, the faces being offset so that in a neutral position the outer edge of the closer spaced magnet set is aligned with the inner edge of the greater spaced magnet set. For use as a motor, a coil can be arranged with conductors orthogonal to both the magnet pole directions and the direction of desired spring force, located across from the magnets of one set and fixed with respect to the magnets of the other set. In a cylindrical coordinate system having axial spring force, the magnets are radially poled and motor coils are concentric with the cylinder axis.

Impacts of tides on tsunami propagation due to potential Nankai Trough earthquakes in the Seto Inland Sea, Japan

Science.gov (United States)

Lee, Han Soo; Shimoyama, Tomohisa; Popinet, Stéphane

2015-10-01

The impacts of tides on extreme tsunami propagation due to potential Nankai Trough earthquakes in the Seto Inland Sea (SIS), Japan, are investigated through numerical experiments. Tsunami experiments are conducted based on five scenarios that consider tides at four different phases, such as flood, high, ebb, and low tides. The probes that were selected arbitrarily in the Bungo and Kii Channels show less significant effects of tides on tsunami heights and the arrival times of the first waves than those that experience large tidal ranges in inner basins and bays of the SIS. For instance, the maximum tsunami height and the arrival time at Toyomaesi differ by more than 0.5 m and nearly 1 h, respectively, depending on the tidal phase. The uncertainties defined in terms of calculated maximum tsunami heights due to tides illustrate that the calculated maximum tsunami heights in the inner SIS with standing tides have much larger uncertainties than those of two channels with propagating tides. Particularly in Harima Nada, the uncertainties due to the impacts of tides are greater than 50% of the tsunami heights without tidal interaction. The results recommend simulate tsunamis together with tides in shallow water environments to reduce the uncertainties involved with tsunami modeling and predictions for tsunami hazards preparedness. This article was corrected on 26 OCT 2015. See the end of the full text for details.

75 FR 20371 - Certificate of Alternative Compliance for the Offshore Supply Vessel LEBOUEF TIDE

Science.gov (United States)

2010-04-19

... Compliance for the Offshore Supply Vessel LEBOUEF TIDE AGENCY: Coast Guard, DHS. ACTION: Notice. SUMMARY: The... vessel LEBOUEF TIDE as required by 33 U.S.C. 1605(c) and 33 CFR 81.18. [[Page 20372

The variability of SE2 tide extracted from TIMED/SABER observations

Science.gov (United States)

Li, X.; Wan, W.; Ren, Z.

2017-12-01

Based on the temperature observations of the TIMED/SABER in mesosphere/lower thermosphere region (70-110 km altitudes) and at the low latitude and midlatitude (45°S-45°N) from 2002 to 2012, the variability of the nonmigrating tide SE2 with 1 day resolution is analyzed. It is found that the climatological features (large-scale variability) of the semidiurnal nonmigrating tide with zonal wave number 2 (SE2) tide are similar with the results from the previous research works. The SE2 tide manifests mainly at the low-mid latitudes around ±30°. The northern hemisphere tidal amplitudes below 110 km are larger than the southern hemisphere tide. SE2 peaks below 110 km mainly present between 100 and 110 km altitude. The tidal amplitudes below 110 km occur a north-south asymmetry about the equator in the annual variation: in the southern hemisphere, SE2 occurs with an obvious annual variation with a maximum of tidal amplitudes in December, while in the northern one, the semiannual variations with maximum at the equinoxes. Herein, owing to the high-resolution tidal data, we could research the short-term (day-to-day) variations of SE2. We found that the day-to-day variations manifest mainly at between 100 and 110 km altitudes; it increases gradually with latitudes, and it is stronger at the low-mid latitudes; it is relatively slightly stronger around solstices than equinoxes; and it does not present a remarkably interannual variation. The SE2 day-to-day variations may be composed by the absolute amplitudes' variance and the impact of the wave phases, and the latter ones are more important.

Tides and seiches in gulfs

International Nuclear Information System (INIS)

Pierini, S.

1981-01-01

In this paper Garrett's theory of tides in gulfs is extended so that its formalism includes the free oscillations (seiches) of the gulf. The elevation of the free surface zeta and the velocity field u are obtained in a rectangular, one-dimensional gulf opening into an infinite ocean. An application of the results to the Adriatic sea can explain qualitatively the long life of the uninodal seiche of that basin. (author)

Red Tide Strands South African Rock Lobsters

Science.gov (United States)

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

Seasonal variations of the semi-diurnal and diurnal tides in the MLT: multi-year MF radar observations from 2–70° N, modelled tides (GSWM, CMAM

Directory of Open Access Journals (Sweden)

A. H. Manson

2002-05-01

Full Text Available In an earlier paper (Manson et al., 1999a tidal data (1990–1997 from six Medium Frequency Radars (MFR were compared with the Global Scale Wave Model (GSWM, original 1995 version. The radars are located between the equator and high northern latitudes: Christmas Island (2° N, Hawaii (22° N, Urbana (40° N, London (43° N, Saskatoon (52° N and Tromsø (70° N. Common harmonic analysis was applied, to ensure consistency of amplitudes and phases in the 75–95 km height range. For the diurnal tide, seasonal agreements between observations and model were excellent while for the semi-diurnal tide the seasonal transitions between clear solstitial states were less well captured by the model. Here the data set is increased by the addition of two locations in the Pacific-North American sector: Yamagawa 31° N, and Wakkanai 45° N. The GSWM model has undergone two additional developments (1998, 2000 to include an improved gravity wave (GW stress parameterization, background winds from UARS systems and monthly tidal forcing for better characterization of seasonal change. The other model, the Canadian Middle Atmosphere Model (CMAM which is a General Circulation Model, provides internally generated forcing (due to ozone and water vapour for the tides. The two GSWM versions show distinct differences, with the 2000 version being either closer to, or further away from, the observations than the original 1995 version. CMAM provides results dependent upon the GW parameterization scheme inserted, but one of the schemes provides very useful tides, especially for the semi-diurnal component.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides

Quantitative, molecular and growth analyses of Ulva microscopic propagules in the coastal sediment of Jiangsu province where green tides initially occurred.

Science.gov (United States)

Liu, Feng; Pang, Shao Jun; Zhao, Xiao Bo; Hu, Chuan Ming

2012-03-01

From 2007 to 2011, large-scale green tides formed by unattached filamentous alga, Ulva prolifera in Ulva linza-procera-prolifera complex, have initially occurred in Jiangsu coasts of China. The real niche or the substrate(s) on which U. prolifera attaches before it starts to float is still under debate. However, great numbers of Ulva propagules would be supposed to exist in the microscopic, overwintering stage for the next spring's bloom in coastal environments. This study was designed to confirm the above prediction and investigate abundance, species composition and growth characteristics of Ulva propagules in the sediments. Quantification result showed that Ulva propagules widely distributed in the sediments and the abundance of these isolates did not change much over a 3-month testing period at low temperature in darkness. Molecular data based on three DNA markers revealed that four Ulva species existed in the sediments, among which green-tide forming alga, U. prolifera, was included. Elevated levels of temperature, irradiance as well as nutrients in seawater greatly facilitated recovery and growth of propagules. Results of this investigation indicated the possibility of microscopic propagules turning directly into floating biomass in season when temperature, irradiance and nutrients together meet the required levels in questioned coastal water area. Copyright © 2011 Elsevier Ltd. All rights reserved.

Observation, Isolation and Characterization of Microalgal Red Tide Agent Dinoflagellates Prorocentrum sp. (Pengamatan, Isolasi dan Karakterisasi Mikroalga Red Tide dari Dinoflagellata Prorocentrum sp

Directory of Open Access Journals (Sweden)

Dwi Susilaningsih

2014-09-01

Full Text Available Spesies Dinophyte mempunyai habitat dari kutub, perairan tropis, tetapi semakin berlimpah di perairan tropis atau hangat. Dinophyte diduga sebagai penyebab terjadinya "red tide" sehingga nampak berwarna kuning kemerahan di laut ketikan malam hari disebabkan aktivitas bioluminescence.Penelitian ini menggunakan Dinophyte yang diisolasi dari pantai dan sampel air yang diperoleh dari di Prefektur Iwate, Jepang. Tujuan dari penelitian ini adalah untuk mengetahui taksonomi yang menyebabkan blooming. Spesies ini memiliki karakter yang spesifik bernbentuk oval (panjang 20-30 μm dan lebar 1-20 μm, kloroplas berwarna kuning, nukleus yang besar, dua flagel yang berbeda, yang salah satunya disebut flagellum transfer, tidak memiliki selaput tengah yang, ornament sel yang indah "theca"dengan tulang belakang. Berdasarkan hasil squensing pada 18 S rDNA, Dinophyte mempunyai kesamaan dengan strain Prorocentrum MBIC11147 (100%, Di masa yang akan datang penelitian Procentrum sp. bisa menggunakan sebagai model squensing, perilaku pasang mikroalga. Kata kunci: alga, Dinophyte, karakterisasi, isolation, Prorocentrum, red tide Dinophyte species inhabit from polar, temperate to tropical waters, but tend to be more abundant in tropical or warm waters. The Dinophytes is suspected as one of the genera causing red tide in the sea with their yellow-redish colour that make the sea glows in the night because of their bioluminescence activity. In this work, the Dinophyte was isolated from offshore, and water sample collected in Iwate Prefecture, Japan. Purposes of the studies were for understanding the taxonomic features in particular of the dinophytes that usually occur in blooming areas. The species has specific characters, such as oval shape ( 20-30 μm long and 1-20 μm wide, yellow chloroplast, large nucleus, possesses two different flagellas which one of them is specific called transfer flagellum, no middle furrow and beautiful ornament cell covering (theca with spine

Near-surface energy transfers from internal tide beams to smaller vertical scale motions

Science.gov (United States)

Chou, S.; Staquet, C.; Carter, G. S.; Luther, D. S.

2016-02-01

Mechanical energy capable of causing diapycnal mixing in the ocean is transferred to the internal wave field when barotropic tides pass over underwater topography and generate internal tides. The resulting internal tide energy is confined in vertically limited structures, or beams. As internal tide beams (ITBs) propagate through regions of non-uniform stratification in the upper ocean, wave energy can be scattered through multiple reflections and refractions, be vertically trapped, or transferred to non-tidal frequencies through different nonlinear processes. Various observations have shown that ITBs are no longer detectable in horizontal kinetic energy beyond the first surface reflection. Importantly, this implies that some of the internal tide energy no longer propagates in to the abyssal ocean and consequently will not be available to maintain the density stratification. Using the NHM, a nonlinear and nonhydrostatic model based on the MITgcm, simulations of an ITB propagating up to the sea surface are examined in order to quantify the transformation of ITB energy to other motions. We compare and contrast the transformations enabled by idealized, smoothly-varying stratification with transformations enabled by realistic stratification containing a broad-band vertical wavenumber spectrum of variations. Preliminary two-dimensional results show that scattering due to small-scale structure in realistic stratification profiles from Hawaii can lead to energy being vertically trapped near the surface. Idealized simulations of "locally" generated internal solitary waves are analyzed in terms of energy flux transfers from the ITB to solitary waves, higher harmonics, and mean flow. The amount of internal tide energy which propagates back down after near-surface reflection of the ITB in different environments is quantified.

Modelling alongshore flow in a semi-enclosed lagoon strongly forced by tides and waves

Science.gov (United States)

Taskjelle, Torbjørn; Barthel, Knut; Christensen, Kai H.; Furaca, Noca; Gammelsrød, Tor; Hoguane, António M.; Nharreluga, Bilardo

2014-08-01

Alongshore flows strongly driven by tides and waves is studied in the context of a one-dimensional numerical model. Observations from field surveys performed in a semi-enclosed lagoon (1.7 km×0.2 km) outside Xai-Xai, Mozambique, are used to validate the model results. The model is able to capture most of the observed temporal variability of the current, but sea surface height tends to be overestimated at high tide, especially during high wave events. Inside the lagoon we observed a mainly uni-directional alongshore current, with speeds up to 1 ms-1. The current varies primarily with the tide, being close to zero near low tide, generally increasing during flood and decreasing during ebb. The observations revealed a local minimum in the alongshore flow at high tide, which the model was successful in reproducing. Residence times in the lagoon were calculated to be less than one hour with wave forcing dominating the flushing. At this beach a high number of drowning casualties have occurred, but no connection was found between them and strong current events in a simulation covering the period 2011-2012.

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

Science.gov (United States)

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. © The Author 2015. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved

High tide in the Delta

International Nuclear Information System (INIS)

Vellinga, P.

2008-01-01

This inaugural speech takes a closer look at the relation of the Netherlands with water and sea. The author pleas for better connections of land and water and better connections of fresh and salt water. The oration discusses the influence of man on the climate, recent discoveries in the field of climate, urgency in the field of energy, opportunities for high tide protection in the Netherlands and plans for filling the new chair [nl

A Global Ocean Tide Model From TOPEX/POSEIDON Altimetry: GOT99.2

Science.gov (United States)

Ray, Richard D.

1999-01-01

Goddard Ocean Tide model GOT99.2 is a new solution for the amplitudes and phases of the global oceanic tides, based on over six years of sea-surface height measurements by the TOPEX/POSEIDON satellite altimeter. Comparison with deep-ocean tide-gauge measurements show that this new tidal solution is an improvement over previous global models, with accuracies for the main semidiurnal lunar constituent M2 now below 1.5 cm (deep water only). The new solution benefits from use of prior hydrodynamic models, several in shallow and inland seas as well as the global finite-element model FES94.1. This report describes some of the data processing details involved in handling the altimetry, and it provides a comprehensive set of global cotidal charts of the resulting solutions. Various derived tidal charts are also provided, including tidal loading deformation charts, tidal gravimetric charts, and tidal current velocity (or transport) charts. Finally, low-degree spherical harmonic coefficients are computed by numerical quadrature and are tabulated for the major short-period tides; these are useful for a variety of geodetic and geophysical purposes, especially in combination with similar estimates from satellite laser ranging.

Crustal control of dissipative ocean tides in Enceladus and other icy moons

Science.gov (United States)

Beuthe, Mikael

2016-12-01

Could tidal dissipation within Enceladus' subsurface ocean account for the observed heat flow? Earthlike models of dynamical tides give no definitive answer because they neglect the influence of the crust. I propose here the first model of dissipative tides in a subsurface ocean, by combining the Laplace Tidal Equations with the membrane approach. For the first time, it is possible to compute tidal dissipation rates within the crust, ocean, and mantle in one go. I show that oceanic dissipation is strongly reduced by the crustal constraint, and thus contributes little to Enceladus' present heat budget. Tidal resonances could have played a role in a forming or freezing ocean less than 100 m deep. The model is general: it applies to all icy satellites with a thin crust and a shallow ocean. Scaling rules relate the resonances and dissipation rate of a subsurface ocean to the ones of a surface ocean. If the ocean has low viscosity, the westward obliquity tide does not move the crust. Therefore, crustal dissipation due to dynamical obliquity tides can differ from the static prediction by up to a factor of two.

Verifying the body tide at the Canary Islands using tidal gravimetry observations

Science.gov (United States)

Arnoso, J.; Benavent, M.; Bos, M. S.; Montesinos, F. G.; Vieira, R.

2011-05-01

Gravity tide records from El Hierro, Tenerife and Lanzarote Islands (Canarian Archipelago) have been analyzed and compared to the theoretical body tide model (DDW) of Dehant el al. (1999). The use of more stringent criterion of tidal analysis using VAV program allowed us to reduce the error bars by a factor of two of the gravimetric factors at Tenerife and Lanzarote compared with previous published values. Also, the calibration values have been revisited at those sites. Precise ocean tide loading (OTL) corrections based on up-to-date global ocean models and improved regional ocean model have been obtained for the main tidal harmonics O 1, K 1, M 2, S 2. We also point out the importance of using the most accurate coastline definition for OTL calculations in the Canaries. The remaining observational errors depend on the accuracy of the calibration of the gravimeters and/or on the length of the observed data series. Finally, the comparison of the tidal observations with the theoretical body tide models has been done with an accuracy level of 0.1% at El Hierro, 0.4% at Tenerife and 0.5% at Lanzarote.

Modeling the diurnal tide with dissipation derived from UARS/HRDI measurements

Directory of Open Access Journals (Sweden)

M. A. Geller

1997-09-01

Full Text Available This paper uses dissipation values derived from UARS/HRDI observations in a recently published diurnal-tide model. These model structures compare quite well with the UARS/HRDI observations with respect to the annual variation of the diurnal tidal amplitudes and the size of the amplitudes themselves. It is suggested that the annual variation of atmospheric dissipation in the mesosphere-lower thermosphere is a major controlling factor in determining the annual variation of the diurnal tide.

COST Action ES1401 TIDES: a European network on TIme DEpendent Seismology

Science.gov (United States)

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.

INTRODUCING CAFein, A NEW COMPUTATIONAL TOOL FOR STELLAR PULSATIONS AND DYNAMIC TIDES

International Nuclear Information System (INIS)

Valsecchi, F.; Farr, W. M.; Willems, B.; Rasio, F. A.; Kalogera, V.

2013-01-01

Here we present CAFein, a new computational tool for investigating radiative dissipation of dynamic tides in close binaries and of non-adiabatic, non-radial stellar oscillations in isolated stars in the linear regime. For the latter, CAFein computes the non-adiabatic eigenfrequencies and eigenfunctions of detailed stellar models. The code is based on the so-called Riccati method, a numerical algorithm that has been successfully applied to a variety of stellar pulsators, and which does not suffer from the major drawbacks of commonly used shooting and relaxation schemes. Here we present an extension of the Riccati method to investigate dynamic tides in close binaries. We demonstrate CAFein's capabilities as a stellar pulsation code both in the adiabatic and non-adiabatic regimes, by reproducing previously published eigenfrequencies of a polytrope, and by successfully identifying the unstable modes of a stellar model in the β Cephei/SPB region of the Hertzsprung-Russell diagram. Finally, we verify CAFein's behavior in the dynamic tides regime by investigating the effects of dynamic tides on the eigenfunctions and orbital and spin evolution of massive main sequence stars in eccentric binaries, and of hot Jupiter host stars. The plethora of asteroseismic data provided by NASA's Kepler satellite, some of which include the direct detection of tidally excited stellar oscillations, make CAFein quite timely. Furthermore, the increasing number of observed short-period detached double white dwarfs (WDs) and the observed orbital decay in the tightest of such binaries open up a new possibility of investigating WD interiors through the effects of tides on their orbital evolution

Evidence for Excitation of Polar Motion by Fortnightly Ocean Tides

Science.gov (United States)

Gross, Richard S.; Hamdan, Kamal H.; Boggs, Dale H.

1996-01-01

The second-degree zonal tide raising potential, which is responsible for tidal changes in the Earth's rotation rate and length-of-day, is symmetric about the polar axis and hence can excite the Earth's polar motion only through its action upon nonaxisymmetric features of the Earth such as the oceans. Ocean tidal excitation of polar motion in the diurnal and semidiurnal tidal bands has been previously detected and examined. Here, the detection of ocean tidal excitation of polar motion in the long-period tidal band, specifically at the Mf' (13.63-day) and Mf (13.66-day) tidal frequencies, is reported. Spectra of the SPACE94 polar motion excitation series exhibit peaks at the prograde and retrograde fortnightly tidal periods. After removing effects of atmospheric wind and pressure changes, an empirical model for the effect of the fortnightly ocean tides upon polar motion excitation is obtained by least-squares fitting periodic terms at the Mf and Mf' tidal frequencies to the residual polar motion excitation series. The resulting empirical model is then compared with the predictions of two hydrodynamic ocean tide models.

An Adaptive Neuro-Fuzzy Inference System for Sea Level Prediction Considering Tide-Generating Forces and Oceanic Thermal Expansion

Directory of Open Access Journals (Sweden)

Li-Ching Lin Hsien-Kuo Chang

2008-01-01

Full Text Available The paper presents an adaptive neuro fuzzy inference system for predicting sea level considering tide-generating forces and oceanic thermal expansion assuming a model of sea level dependence on sea surface temperature. The proposed model named TGFT-FN (Tide-Generating Forces considering sea surface Temperature and Fuzzy Neuro-network system is applied to predict tides at five tide gauge sites located in Taiwan and has the root mean square of error of about 7.3 - 15.0 cm. The capability of TGFT-FN model is superior in sea level prediction than the previous TGF-NN model developed by Chang and Lin (2006 that considers the tide-generating forces only. The TGFT-FN model is employed to train and predict the sea level of Hua-Lien station, and is also appropriate for the same prediction at the tide gauge sites next to Hua-Lien station.

Groundwater flow cycling between a submarine spring and an inland fresh water spring.

Science.gov (United States)

Davis, J Hal; Verdi, Richard

2014-01-01

Spring Creek Springs and Wakulla Springs are large first magnitude springs that derive water from the Upper Floridan Aquifer. The submarine Spring Creek Springs are located in a marine estuary and Wakulla Springs are located 18 km inland. Wakulla Springs has had a consistent increase in flow from the 1930s to the present. This increase is probably due to the rising sea level, which puts additional pressure head on the submarine Spring Creek Springs, reducing its fresh water flow and increasing flows in Wakulla Springs. To improve understanding of the complex relations between these springs, flow and salinity data were collected from June 25, 2007 to June 30, 2010. The flow in Spring Creek Springs was most sensitive to rainfall and salt water intrusion, and the flow in Wakulla Springs was most sensitive to rainfall and the flow in Spring Creek Springs. Flows from the springs were found to be connected, and composed of three repeating phases in a karst spring flow cycle: Phase 1 occurred during low rainfall periods and was characterized by salt water backflow into the Spring Creek Springs caves. The higher density salt water blocked fresh water flow and resulted in a higher equivalent fresh water head in Spring Creek Springs than in Wakulla Springs. The blocked fresh water was diverted to Wakulla Springs, approximately doubling its flow. Phase 2 occurred when heavy rainfall resulted in temporarily high creek flows to nearby sinkholes that purged the salt water from the Spring Creek Springs caves. Phase 3 occurred after streams returned to base flow. The Spring Creek Springs caves retained a lower equivalent fresh water head than Wakulla Springs, causing them to flow large amounts of fresh water while Wakulla Springs flow was reduced by about half. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Bottom friction optimization for a better barotropic tide modelling

Science.gov (United States)

Boutet, Martial; Lathuilière, Cyril; Son Hoang, Hong; Baraille, Rémy

2015-04-01

At a regional scale, barotropic tides are the dominant source of variability of currents and water heights. A precise representation of these processes is essential because of their great impacts on human activities (submersion risks, marine renewable energies, ...). Identified sources of error for tide modelling at a regional scale are the followings: bathymetry, boundary forcing and dissipation due to bottom friction. Nevertheless, bathymetric databases are nowadays known with a good accuracy, especially over shelves, and global tide models performances are better than ever. The most promising improvement is thus the bottom friction representation. The method used to estimate bottom friction is the simultaneous perturbation stochastic approximation (SPSA) which consists in the approximation of the gradient based on a fixed number of cost function measurements, regardless of the dimension of the vector to be estimated. Indeed, each cost function measurement is obtained by randomly perturbing every component of the parameter vector. An important feature of SPSA is its relative ease of implementation. In particular, the method does not require the development of tangent linear and adjoint version of the circulation model. Experiments are carried out to estimate bottom friction with the HYbrid Coordinate Ocean Model (HYCOM) in barotropic mode (one isopycnal layer). The study area is the Northeastern Atlantic margin which is characterized by strong currents and an intense dissipation. Bottom friction is parameterized with a quadratic term and friction coefficient is computed with the water height and the bottom roughness. The latter parameter is the one to be estimated. Assimilated data are the available tide gauge observations. First, the bottom roughness is estimated taking into account bottom sediment natures and bathymetric ranges. Then, it is estimated with geographical degrees of freedom. Finally, the impact of the estimation of a mixed quadratic/linear friction

Intraseasonal variability and tides in Makassar Strait

Science.gov (United States)

Susanto, R. Dwi; Gordon, Arnold L.; Sprintall, Janet; Herunadi, Bambang

2000-05-01

Intraseasonal variability and tides along the Makassar Strait, the major route of Indonesian throughflow, are investigated using spectral and time-frequency analyses which are applied to sea level, wind and mooring data. Semidiurnal and diurnal tides are dominant features, with higher (lower) semidiurnal (diurnal) energy in the north compared to the south. Sea levels and mooring data display intraseasonal variability which are probably a response to remotely forced Kelvin waves from the Indian Ocean through Lombok Strait and to Rossby waves from the Pacific Ocean. Sea levels in Tarakan and Balikpapan and Makassar mooring velocities reveal intraseasonal features with periods of 48-62 days associated with Rossby waves from the Sulawesi Sea. Kelvin wave features with periods of 67-100 days are seen in Bali (Lombok Strait), at the mooring sites and in Balikpapan, however, they are not seen in Tarakan, which implies that these waves diminish after passing through the Makassar Strait.

Solar cycle variability of nonmigrating tides in the infrared cooling of the thermosphere

Science.gov (United States)

Nischal, N.; Oberheide, J.; Mlynczak, M. G.; Marsh, D. R.

2017-12-01

Nitric Oxide (NO) at 5.3 μm and Carbon dioxide (CO2) at 15 μm are the major infrared emissions responsible for the radiative cooling of the thermosphere. We study the impact of two important diurnal nonmigrating tides, the DE2 and DE3, on NO and CO2 infrared emissions over a complete solar cycle (2002-2013) by (i) analyzing NO and CO2 cooling rate data from SABER and (ii) photochemical modeling using dynamical tides from a thermospheric empirical tidal model, CTMT. Both observed and modeled results show that the NO cooling rate amplitudes for DE2 and DE3 exhibit strong solar cycle dependence. NO 5.3 μm cooling rate tides are relatively unimportant for the infrared energy budget during solar minimum but important during solar maximum. On the other hand DE2 and DE3 in CO2 show comparatively small variability over a solar cycle. CO2 15 μm cooling rate tides remain, to a large extent, constant between solar minimum and maximum. This different responses by NO and CO2 emissions to the DE2 and DE3 during a solar cycle comes form the fact that the collisional reaction rate for NO is highly sensitive to the temperature comparative to that for CO2. Moreover, the solar cycle variability of these nonmigrating tides in thermospheric infrared emissions shows a clear QBO signals substantiating the impact of tropospheric weather system on the energy budget of the thermosphere. The relative contribution from the individual tidal drivers; temperature, density and advection to the observed DE2 and DE3 tides does not vary much over the course of the solar cycle, and this is true for both NO and CO2 emissions.

Prediction of tides using back-propagation neural networks

Digital Repository Service at National Institute of Oceanography (India)

Mandal, S.

Prediction of tides is very much essential for human activities and to reduce the construction cost in marine environment. This paper presents an application of the artificial neural network with back-propagation procedures for accurate prediction...

Application of the Convolution Formalism to the Ocean Tide Potential: Results from the Gravity and Recovery and Climate Experiment (GRACE)

Science.gov (United States)

Desai, S. D.; Yuan, D. -N.

2006-01-01

A computationally efficient approach to reducing omission errors in ocean tide potential models is derived and evaluated using data from the Gravity Recovery and Climate Experiment (GRACE) mission. Ocean tide height models are usually explicitly available at a few frequencies, and a smooth unit response is assumed to infer the response across the tidal spectrum. The convolution formalism of Munk and Cartwright (1966) models this response function with a Fourier series. This allows the total ocean tide height, and therefore the total ocean tide potential, to be modeled as a weighted sum of past, present, and future values of the tide-generating potential. Previous applications of the convolution formalism have usually been limited to tide height models, but we extend it to ocean tide potential models. We use luni-solar ephemerides to derive the required tide-generating potential so that the complete spectrum of the ocean tide potential is efficiently represented. In contrast, the traditionally adopted harmonic model of the ocean tide potential requires the explicit sum of the contributions from individual tidal frequencies. It is therefore subject to omission errors from neglected frequencies and is computationally more intensive. Intersatellite range rate data from the GRACE mission are used to compare convolution and harmonic models of the ocean tide potential. The monthly range rate residual variance is smaller by 4-5%, and the daily residual variance is smaller by as much as 15% when using the convolution model than when using a harmonic model that is defined by twice the number of parameters.

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

Science.gov (United States)

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.

Spring Tire

Science.gov (United States)

Asnani, Vivake M.; Benzing, Jim; Kish, Jim C.

2011-01-01

The spring tire is made from helical springs, requires no air or rubber, and consumes nearly zero energy. The tire design provides greater traction in sandy and/or rocky soil, can operate in microgravity and under harsh conditions (vastly varying temperatures), and is non-pneumatic. Like any tire, the spring tire is approximately a toroidal-shaped object intended to be mounted on a transportation wheel. Its basic function is also similar to a traditional tire, in that the spring tire contours to the surface on which it is driven to facilitate traction, and to reduce the transmission of vibration to the vehicle. The essential difference between other tires and the spring tire is the use of helical springs to support and/or distribute load. They are coiled wires that deform elastically under load with little energy loss.

Studying Springs in Series Using a Single Spring

Science.gov (United States)

Serna, Juan D.; Joshi, Amitabh

2011-01-01

Springs are used for a wide range of applications in physics and engineering. Possibly, one of their most common uses is to study the nature of restoring forces in oscillatory systems. While experiments that verify Hooke's law using springs are abundant in the physics literature, those that explore the combination of several springs together are…

Are there tides within trees?

Science.gov (United States)

Fisahn, Joachim

2018-01-24

Tree stem diameters and electrical stem potentials exhibit rhythmic variations with periodicities of 24-25 h. Under free-running conditions of constant light or darkness these rhythms were suggested to be mediated by the lunisolar gravitational force. To further unravel the regulation of tree stem diameter dilatations, many of the published time courses of diameter variations were re-evaluated in conjunction with the contemporaneous time courses of the lunisolar tidal acceleration. This was accomplished by application of the Etide program, which estimates, with high temporal resolution, local gravitational changes as a consequence of the diurnal variations of the lunisolar gravitational force due to the orbits and relative positions of Earth, Moon and Sun. In all instances investigated, it was evident that a synchronism exists between the times of the turning points of both the lunisolar tide and stem diameter variations when the direction of extension changes. This finding of synchrony documents that the lunisolar tide is a regulator of the tree stem diameter dilatations. Under the described experimental conditions, rhythms in tree stem diameter dilations and electrical stem potentials are controlled by the lunisolar gravitational acceleration. © The Author(s) 2018. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Study of ocean red tide multi-parameter monitoring technology based on double-wavelength airborne lidar system

Science.gov (United States)

Lin, Hong; Wang, Xinming; Liang, Kun

2010-10-01

For monitoring and forecasting of the ocean red tide in real time, a marine environment monitoring technology based on the double-wavelength airborne lidar system is proposed. An airborne lidar is father more efficient than the traditional measure technology by the boat. At the same time, this technology can detect multi-parameter about the ocean red tide by using the double-wavelength lidar.It not only can use the infrared laser to detect the scattering signal under the water and gain the information about the red tise's density and size, but also can use the blue-green laser to detect the Brillouin scattering signal and deduce the temperature and salinity of the seawater.The red tide's density detecting model is firstly established by introducing the concept about the red tide scattering coefficient based on the Mie scattering theory. From the Brillouin scattering theory, the relationship about the blue-green laser's Brillouin scattering frequency shift value and power value with the seawater temperature and salinity is found. Then, the detecting mode1 of the saewater temperature and salinity can be established. The value of the red tide infrared scattering signal is evaluated by the simulation, and therefore the red tide particles' density can be known. At the same time, the blue-green laser's Brillouin scattering frequency shift value and power value are evaluated by simulating, and the temperature and salinity of the seawater can be known. Baed on the multi-parameters, the ocean red tide's growth can be monitored and forecasted.

Beginning Spring

CERN Document Server

Caliskan, Mert

2015-01-01

Get up to speed quickly with this comprehensive guide toSpring Beginning Spring is the complete beginner's guide toJava's most popular framework. Written with an eye towardreal-world enterprises, the book covers all aspects of applicationdevelopment within the Spring Framework. Extensive samples withineach chapter allow developers to get up to speed quickly byproviding concrete references for experimentation, building askillset that drives successful application development byexploiting the full capabilities of Java's latest advances. Spring provides the exact toolset required to build anent

Atmospheric Pressure Corrections in Geodesy and Oceanography: a Strategy for Handling Air Tides

Science.gov (United States)

Ponte, Rui M.; Ray, Richard D.

2003-01-01

Global pressure data are often needed for processing or interpreting modern geodetic and oceanographic measurements. The most common source of these data is the analysis or reanalysis products of various meteorological centers. Tidal signals in these products can be problematic for several reasons, including potentially aliased sampling of the semidiurnal solar tide as well as the presence of various modeling or timing errors. Building on the work of Van den Dool and colleagues, we lay out a strategy for handling atmospheric tides in (re)analysis data. The procedure also offers a method to account for ocean loading corrections in satellite altimeter data that are consistent with standard ocean-tide corrections. The proposed strategy has immediate application to the on-going Jason-1 and GRACE satellite missions.

Integration of coastal inundation modeling from storm tides to individual waves

Science.gov (United States)

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.

Red tide discolouration and its impact on fisheries

Digital Repository Service at National Institute of Oceanography (India)

Devassy, V.P.

months. Although the earlier two red tides did not provide any direct evidence of fish mortality, the 1987 one was followed by a substantial fall in fish catch. The prevailing environmental conditions and the probable impact on the fisheries during...

Coastal Improvements for Tide Models: The Impact of ALES Retracker

Directory of Open Access Journals (Sweden)

Gaia Piccioni

2018-05-01

Full Text Available Since the launch of the first altimetry satellites, ocean tide models have been improved dramatically for deep and shallow waters. However, issues are still found for areas of great interest for climate change investigations: the coastal regions. The purpose of this study is to analyze the influence of the ALES coastal retracker on tide modeling in these regions with respect to a standard open ocean retracker. The approach used to compute the tidal constituents is an updated and along-track version of the Empirical Ocean Tide model developed at DGFI-TUM. The major constituents are derived from a least-square harmonic analysis of sea level residuals based on the FES2014 tide model. The results obtained with ALES are compared with the ones estimated with the standard product. A lower fitting error is found for the ALES solution, especially for distances closer than 20 km from the coast. In comparison with in situ data, the root mean squared error computed with ALES can reach an improvement larger than 2 cm at single locations, with an average impact of over 10% for tidal constituents K 2 , O 1 , and P 1 . For Q 1 , the improvement is over 25%. It was observed that improvements to the root-sum squares are larger for distances closer than 10 km to the coast, independently on the sea state. Finally, the performance of the solutions changes according to the satellite’s flight direction: for tracks approaching land from open ocean root mean square differences larger than 1 cm are found in comparison to tracks going from land to ocean.

Observed characteristics of tide-surge interaction along the east coast of India and the head of Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

Antony, C.; Unnikrishnan, A.S.

before the high tide. Application of a simple model shows the observed surge peak distribution at Hiron Point can be explained in terms of phase alteration of tide due to surge and surge modulation by tide. The degree of interaction tends to increase...

ACCURACY ASSESSMENT OF RECENT GLOBAL OCEAN TIDE MODELS AROUND ANTARCTICA

Directory of Open Access Journals (Sweden)

J. Lei

2017-09-01

Full Text Available Due to the coverage limitation of T/P-series altimeters, the lack of bathymetric data under large ice shelves, and the inaccurate definitions of coastlines and grounding lines, the accuracy of ocean tide models around Antarctica is poorer than those in deep oceans. Using tidal measurements from tide gauges, gravimetric data and GPS records, the accuracy of seven state-of-the-art global ocean tide models (DTU10, EOT11a, GOT4.8, FES2012, FES2014, HAMTIDE12, TPXO8 is assessed, as well as the most widely-used conventional model FES2004. Four regions (Antarctic Peninsula region, Amery ice shelf region, Filchner-Ronne ice shelf region and Ross ice shelf region are separately reported. The standard deviations of eight main constituents between the selected models are large in polar regions, especially under the big ice shelves, suggesting that the uncertainty in these regions remain large. Comparisons with in situ tidal measurements show that the most accurate model is TPXO8, and all models show worst performance in Weddell sea and Filchner-Ronne ice shelf regions. The accuracy of tidal predictions around Antarctica is gradually improving.

Accuracy Assessment of Recent Global Ocean Tide Models around Antarctica

Science.gov (United States)

Lei, J.; Li, F.; Zhang, S.; Ke, H.; Zhang, Q.; Li, W.

2017-09-01

Due to the coverage limitation of T/P-series altimeters, the lack of bathymetric data under large ice shelves, and the inaccurate definitions of coastlines and grounding lines, the accuracy of ocean tide models around Antarctica is poorer than those in deep oceans. Using tidal measurements from tide gauges, gravimetric data and GPS records, the accuracy of seven state-of-the-art global ocean tide models (DTU10, EOT11a, GOT4.8, FES2012, FES2014, HAMTIDE12, TPXO8) is assessed, as well as the most widely-used conventional model FES2004. Four regions (Antarctic Peninsula region, Amery ice shelf region, Filchner-Ronne ice shelf region and Ross ice shelf region) are separately reported. The standard deviations of eight main constituents between the selected models are large in polar regions, especially under the big ice shelves, suggesting that the uncertainty in these regions remain large. Comparisons with in situ tidal measurements show that the most accurate model is TPXO8, and all models show worst performance in Weddell sea and Filchner-Ronne ice shelf regions. The accuracy of tidal predictions around Antarctica is gradually improving.

Review of research in internal-wave and internal-tide deposits of China: Discussion

Directory of Open Access Journals (Sweden)

G. Shanmugam

2014-10-01

Full Text Available This discussion of a review article by [27], published in the Journal of Palaeogeography (2(1: 56– 65, is aimed at illustrating that interpretations of ten ancient examples in China and one in the central Appalachians (USA as deep-water deposits of internal waves and internal tides are unsustainable. This critical assessment is based on an in-depth evaluation of oceanographic and sedimentologic data on internal waves and internal tides derived from 332 print and online published works during 1838–January 2013, which include empirical data on the physical characteristics of modern internal waves and internal tides from 51 regions of the world’s oceans [108]. In addition, core and outcrop descriptions of deep-water strata from 35 case studies worldwide carried out by the author during 1974–2011, and a selected number of case studies published by other researchers are evaluated for identifying the sedimentological challenges associated with distinguishing types of bottom-current reworked sands in the ancient sedimentary record. The emerging conclusion is that any interpretation of ancient strata as deposits of internal waves and internal tides is premature.

Circum-Antarctic Shoreward Heat Transport Derived From an Eddy- and Tide-Resolving Simulation

Science.gov (United States)

Stewart, Andrew L.; Klocker, Andreas; Menemenlis, Dimitris

2018-01-01

Almost all heat reaching the bases of Antarctica's ice shelves originates from warm Circumpolar Deep Water in the open Southern Ocean. This study quantifies the roles of mean and transient flows in transporting heat across almost the entire Antarctic continental slope and shelf using an ocean/sea ice model run at eddy- and tide-resolving (1/48°) horizontal resolution. Heat transfer by transient flows is approximately attributed to eddies and tides via a decomposition into time scales shorter than and longer than 1 day, respectively. It is shown that eddies transfer heat across the continental slope (ocean depths greater than 1,500 m), but tides produce a stronger shoreward heat flux across the shelf break (ocean depths between 500 m and 1,000 m). However, the tidal heat fluxes are approximately compensated by mean flows, leaving the eddy heat flux to balance the net shoreward heat transport. The eddy-driven cross-slope overturning circulation is too weak to account for the eddy heat flux. This suggests that isopycnal eddy stirring is the principal mechanism of shoreward heat transport around Antarctica, though likely modulated by tides and surface forcing.

Heat stress of two tropical seagrass species during low tides

DEFF Research Database (Denmark)

Pedersen, Ole; Colmer, Timothy D.; Borum, Jens

2016-01-01

Seagrasses grow submerged in aerated seawater but often in low O2 sediments. Elevated temperatures and low O2 are stress factors. Internal aeration was measured in two tropical seagrasses, Thalassia hemprichii and Enhalus acoroides, growing with extreme tides and diel temperature amplitudes......), the high temperatures and reduced CO2 would have diminished PN, whereas RD increased (Q10 of 2.0-2.7) above that at 33°C (0.45 and 0.33 μmol O2 m-2 s-1, respectively). During night-time low tides, O2 declined resulting in shoot base anoxia in both species, but incoming water containing c. 20 kPa O2...

Winter variability in the western Gulf of Maine: Part 1: Internal tides

Science.gov (United States)

Brown, W. S.

2011-09-01

During the winter 1997-1998, a field program was conducted in Wilkinson Basin-western Gulf of Maine-as part of a study of winter convective mixing. The field program consisted of (1) Wilkinson basin-scale hydrographic surveys, (2) a tight three-mooring array with ˜100 m separations measured temperature and conductivity at rates of 2-15 min and (3) a single pair of upward/downward-looking pair acoustic Doppler current profiling (ADCP) instruments measured currents with 8 m vertical resolution over the 270 m water column in north-central Wilkinson basin at a rate of 10 min. The moored array measurements below the mixed layer (˜100 m depth) between 11 January and 6 February 1998 were dominated by a combination of the relatively strong semidiurnal external (depth-independent or barotropic) tide; upon which were superposed a weaker phase-locked semidiurnal internal tide and a very weak water column mean currents of about 1 cm/s southward or approximately across the local isobaths. The harmonic analysis of a vertical average of the relatively uniform ADCP velocities in the well-mixed upper 123 m of the water column, defined the external tidal currents which were dominated by a nearly rectilinear, across-isobath (326°T) M 2 semidiurnal tidal current of about 15 cm/s. The depth-dependent residual current field, which was created by subtracting the external tidal current, consisted of (1) clockwise-rotating semidiurnal internal tidal currents of about 5 cm/s below the mixed layer; (2) clockwise-rotating inertial currents; and (3) a considerably less energetic subtidal current variability. The results from both frequency-domain empirical orthogonal function and tidal harmonic analyses of the of isotherm displacement series at each of the three moorings in the 100 m array mutually confirm an approximate east-northeastward phase propagation of the dominant M 2 semidiurnal internal tide across Wilkinson Basin. Further investigation supports the idea that this winter internal

River-tide dynamics : Exploration of nonstationary and nonlinear tidal behavior in the Yangtze River estuary

NARCIS (Netherlands)

Guo, L.; Van der Wegen, M.; Jay, D.A.; Matte, P.; Wang, Z.B.; Roelvink, J.A.; He, Q.

2015-01-01

River-tide dynamics remain poorly understood, in part because conventional harmonic analysis (HA) does not cope effectively with nonstationary signals. To explore nonstationary behavior of river tides and the modulation effects of river discharge, this work analyzes tidal signals in the Yangtze

Just Spring

CERN Document Server

Konda, Madhusudhan

2011-01-01

Get a concise introduction to Spring, the increasingly popular open source framework for building lightweight enterprise applications on the Java platform. This example-driven book for Java developers delves into the framework's basic features, as well as advanced concepts such as containers. You'll learn how Spring makes Java Messaging Service easier to work with, and how its support for Hibernate helps you work with data persistence and retrieval. Throughout Just Spring, you'll get your hands deep into sample code, beginning with a problem that illustrates dependency injection, Spring's co

GOCE++ Dynamical Coastal Topography and tide gauge unification using altimetry and GOCE

DEFF Research Database (Denmark)

Andersen, Ole Baltazar; Knudsen, Per; Nielsen, Karina

Mean Dynamic Topography (MDT) of the ocean along a coastline which contributes/requires reconciling altimetry, tide gauge and vertical land motion. The fundamental use of the MDT computed using altimetry, ocean models or through the use of tide gauges has values of between -2 and +1 meters at different...... processes and physics responsible for sea level changes on various temporal/spatial scales. The study runs from October 2015 to march 2017 and involves elements like: Develop an approach to estimate a consistent DT at tide gauges, coastal areas, and open ocean; Validate the approach in well-surveyed areas......ESA has recently released a study on the potential of ocean levelling as a novel approach to the study of height system unification taking the recent development in geoid accuracy trough GOCE data into account. The suggested investigation involves the use of measurements and modelling to estimate...

High tide, news from a warming world

International Nuclear Information System (INIS)

Lynas, M.

2005-01-01

While governments debate and scientists test ever-more complicated hypotheses, ordinary people all over the world are starting to notice the effects of global warming. In High Tide, British journalist Mark Lynas visits global hot spots to record people's reactions and sound a clarion call for action. Readers looking for a 'we are the world' approach to climate change may be taken aback by Lynas' flat expression of the uncomfortable truth: 'Every time America votes, the world holds its breath.... Climate change begins and ends in America'. Lynas damns the George W. Bush administration for undermining global efforts such as the Kyoto Protocol as well as actively preventing innovation within the United States that would reduce auto and industrial emissions. But High Tide is not the firs or the best book to do that; instead, its narrative strength is in the riveting stories of how small towns, islands, riverside cities, and rural areas are being slowly destroyed. Gardeners in England will be unable to grow heritage plant species within the next 75 years. The Alaskan permafrost is melting, as temperatures there increase ''ten times faster than in the rest of the world.'' An entire Pacific Island nation--Tuvalu--will soon disappear beneath the rising sea, leaving its people homeless. Lynas visits Alaska, Tuvalu, Peru, China, and the east coast of the United States, documenting the lives, places, and cultures that will be lost in the decades to come. Thankfully, just when hopelessness threatens to overwhelm the reader, High Tide offers a five-step plan to mitigate the most catastrophic effects of global climate change. Every step in the plan involves action by United States citizens and their elected representatives, offering American activists and visionaries a chance to do penance for wrecking parts of the world far from our own driveways

Tsunami hazard assessment in the Hudson River Estuary based on dynamic tsunami-tide simulations

Science.gov (United States)

Shelby, Michael; Grilli, Stéphan T.; Grilli, Annette R.

2016-12-01

This work is part of a tsunami inundation mapping activity carried out along the US East Coast since 2010, under the auspice of the National Tsunami Hazard Mitigation program (NTHMP). The US East Coast features two main estuaries with significant tidal forcing, which are bordered by numerous critical facilities (power plants, major harbors,...) as well as densely built low-level areas: Chesapeake Bay and the Hudson River Estuary (HRE). HRE is the object of this work, with specific focus on assessing tsunami hazard in Manhattan, the Hudson and East River areas. In the NTHMP work, inundation maps are computed as envelopes of maximum surface elevation along the coast and inland, by simulating the impact of selected probable maximum tsunamis (PMT) in the Atlantic ocean margin and basin. At present, such simulations assume a static reference level near shore equal to the local mean high water (MHW) level. Here, instead we simulate maximum inundation in the HRE resulting from dynamic interactions between the incident PMTs and a tide, which is calibrated to achieve MHW at its maximum level. To identify conditions leading to maximum tsunami inundation, each PMT is simulated for four different phases of the tide and results are compared to those obtained for a static reference level. We first separately simulate the tide and the three PMTs that were found to be most significant for the HRE. These are caused by: (1) a flank collapse of the Cumbre Vieja Volcano (CVV) in the Canary Islands (with a 80 km3 volume representing the most likely extreme scenario); (2) an M9 coseismic source in the Puerto Rico Trench (PRT); and (3) a large submarine mass failure (SMF) in the Hudson River canyon of parameters similar to the 165 km3 historical Currituck slide, which is used as a local proxy for the maximum possible SMF. Simulations are performed with the nonlinear and dispersive long wave model FUNWAVE-TVD, in a series of nested grids of increasing resolution towards the coast, by one

The influence of tide-topography interaction on low-frequency heat and nutrient fluxes. Application to Cape Trafalgar

Science.gov (United States)

Vargas-Yáñez, Manuel; Viola, Tarek Sarhan; Jorge, Francisco Plaza; Rubín, Juan P.; García-Martínez, M. Carmen

2002-01-01

During July 1994, 1995 and 1996, the Instituto Español de Oceanografía carried out three multidisciplinar surveys in the Northwestern Alboran Sea, Strait of Gibraltar and Gulf of Cadiz. Conductivity-temperature-depth (CTD) data and nutrient measurements revealed the existence of a pool of cool surface waters, rich in nutrients and with high fluorescence values offshore Cape Trafalgar during the three surveys. These data are considered as an indication of some sort of upwelling. The presence of a submarine ridge, breaking the continental shelf off Trafalgar and intercepting along shore tidal currents, and the intense winds in this area make us think that tide-topography interaction, probably enhanced by wind stirring in surface layers, is responsible for this phenomenon. Its permanence is inspected by means of the sea surface temperature (SST) satellite images recompiled for one year. They show that the pool is very frequent in summer and autumn, more unusual in spring and exceptional in winter. The explanation considered is that the mixing of deep and surface waters is only an effective means of heat exchange when the water column is stratified. To support our initial hypothesis and to get some insight of the relevant factors involved, we develop a bidimensional model aimed at studying along shore variations on the temperature, nutrient and chlorophyll distributions. Although the physical-biological model is very simple, it is able to show how large vertical excursions due to tide-topography interaction produce an eddy flux of heat and nutrients, cooling and fertilising areas around the topographic accident. The model is initialised with along-shore homogeneous distributions of all the variables modelled to check if the mechanism proposed is able to break this homogeneity in a similar way to the observed in experimental data. Appreciable differences between areas affected by tide-topography interaction and those far away from it appear in several days, a time

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

Science.gov (United States)

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.

Sediment source, turbidity maximum, and implications for mud exchange between channel and mangroves in an Amazonian estuary

Science.gov (United States)

Asp, Nils Edvin; Gomes, Vando José Costa; Ogston, Andrea; Borges, José Carlos Corrêa; Nittrouer, Charles Albert

2016-02-01

The tide-dominated eastern sector of the Brazilian Amazonian coast includes large mangrove areas and several estuaries, including the estuary associated with the Urumajó River. There, the dynamics of suspended sediments and delivery mechanisms for mud to the tidal flats and mangroves are complex and were investigated in this study. Four longitudinal measuring campaigns were carried out, encompassing spring/neap tides and dry/rainy seasons. During spring tides, water levels were measured simultaneously at 5 points along the estuary. Currents, salinity, and suspended sediment concentrations (SSCs) were measured over the tidal cycle in a cross section at the middle sector of the estuary. Results show a marked turbidity maximum zone (TMZ) during the rainy season, with a 4-km upstream displacement from neap to spring tide. During dry season, the TMZ was conspicuous only during neap tide and dislocated about 5 km upstream and was substantially less apparent in comparison to that observed during rainy season. The results show that mud is being concentrated in the channel associated with the TMZ especially during the rainy season. At this time, a substantial amount of the mud is washed out from mangroves to the estuarine channel and hydrodynamic/salinity conditions for TMZ formation are optimal. As expected, transport to the mangrove flats is most effective during spring tide and substantially reduced at neap tide, when mangroves are not being flooded. During the dry season, mud is resuspended from the bed in the TMZ sector and is a source of sediment delivered to the tidal flats and mangroves. The seasonal variation of the sediments on the seabed is in agreement with the variation of suspended sediments as well.

Head-of-tide bottleneck of particulate material transport from watersheds to estuaries

Science.gov (United States)

Ensign, Scott H.; Noe, Gregory; Hupp, Cliff R.; Skalak, Katherine

2015-01-01

We measured rates of sediment, C, N, and P accumulation at four floodplain sites spanning the nontidal through oligohaline Choptank and Pocomoke Rivers, Maryland, USA. Ceramic tiles were used to collect sediment for a year and sediment cores were collected to derive decadal sedimentation rates using 137Cs. The results showed highest rates of short- and long-term sediment, C, N, and P accumulation occurred in tidal freshwater forests at the head of tide on the Choptank and the oligohaline marsh of the Pocomoke River, and lowest rates occurred in the downstream tidal freshwater forests in both rivers. Presumably, watershed material was mostly trapped at the head of tide, and estuarine material was trapped in oligohaline marshes. This hydrologic transport bottleneck at the head of tide stores most available watershed sediment, C, N, and P creating a sediment shadow in lower tidal freshwater forests potentially limiting their resilience to sea level rise.

Pro Spring Batch

CERN Document Server

Minella, Michael T

2011-01-01

Since its release, Spring Framework has transformed virtually every aspect of Java development including web applications, security, aspect-oriented programming, persistence, and messaging. Spring Batch, one of its newer additions, now brings the same familiar Spring idioms to batch processing. Spring Batch addresses the needs of any batch process, from the complex calculations performed in the biggest financial institutions to simple data migrations that occur with many software development projects. Pro Spring Batch is intended to answer three questions: *What? What is batch processing? What

A review of the green tides in the Yellow Sea, China.

Science.gov (United States)

Liu, Xiangqing; Wang, Zongling; Zhang, Xuelei

2016-08-01

The recurrent green tide of Ulva prolifera caused serious ecological problems in the Yellow Sea and attached substantial scientific study. The bloom originated in the Subei Shoal area and drifted to the coast of Shandong Province during the period from May to July, driven by a series of physical processes. Here we reviewed advances in the understanding of green tides in the Yellow Sea and elucidate the developmental model of this phenomenon. This knowledge will help resource managers to take reasonable measures to mitigate the impacts to the Yellow Sea. Copyright © 2016 Elsevier Ltd. All rights reserved.

Theory of second order tide forces and gravitational wave experiment

International Nuclear Information System (INIS)

Tammelo, R.R.

1989-01-01

Theory of tide forces square by vector radius is presented. The mechanism of 10 18 time gravitational wave pressure increase in case of radiation from pulsars and 10 15 time one in case of standard burst of radiation from astrophysical catastrophe is proposed. This leads to secular shifts of longitudinally free receivers by 10 -16 cm during 10 5 s in the first case and by 10 -19 cm during 10 s in the second one. A possibility of increase effect modulation is available. It is indicated that it is possible to construct a device which produces more energy at the expense of square tide forces than at the expense of linear ones. 21 refs

Design, optimization and numerical modelling of a novel floating pendulum wave energy converter with tide adaptation

Science.gov (United States)

Yang, Jing; Zhang, Da-hai; Chen, Ying; Liang, Hui; Tan, Ming; Li, Wei; Ma, Xian-dong

2017-10-01

A novel floating pendulum wave energy converter (WEC) with the ability of tide adaptation is designed and presented in this paper. Aiming to a high efficiency, the buoy's hydrodynamic shape is optimized by enumeration and comparison. Furthermore, in order to keep the buoy's well-designed leading edge always facing the incoming wave straightly, a novel transmission mechanism is then adopted, which is called the tidal adaptation mechanism in this paper. Time domain numerical models of a floating pendulum WEC with or without tide adaptation mechanism are built to compare their performance on various water levels. When comparing these two WECs in terms of their average output based on the linear passive control strategy, the output power of WEC with the tide adaptation mechanism is much steadier with the change of the water level and always larger than that without the tide adaptation mechanism.

Accuracy assessment of global barotropic ocean tide models

DEFF Research Database (Denmark)

Stammer, D.; Ray, R. D.; Andersen, Ole Baltazar

2014-01-01

, but testing in those regions is impeded by the paucity of high-quality in situ tide records. Long-wavelength components of models tested by analyzing satellite laser ranging measurements suggest that several models are comparably accurate for use in precise orbit determination, but analyses of GRACE...

Temporally Dynamic, Spatially Static, Cobble Bedforms In Reversing Subtidal Currents

Science.gov (United States)

Abdulkade, Akirat; Carling, Paul; Zong, Quanli; Leyland, Julian; Thompson, Charlie

2016-04-01

Cobble bedforms, transverse to the reversing tidal currents, are exposed at extreme low-water Spring tides on an inter-tidal bedrock shelf in the macro-tidal Severn Estuary, UK. Near-bed flow velocities during Spring tides can exceed 1.5m/s, with water depths varying from zero to in excess of 10m. During neap tides the bedforms are not exposed, and sediment is expected to be of limited mobility. When exposed, the bedform geometry tends to be asymmetric; orientated down estuary with the ebb current. During Spring tides, vigorous bedload transport of gravel (including large cobbles) occurs during both flood and ebb over the crests and yet, despite this temporal dynamism, the bedforms remain spatially static over long time periods or show weak down-estuary migration. Stasis implies that the tidal bedload transport vectors are essentially in balance. Near-bed shear stress and bed roughness values vary systematically with the Spring-tide current speeds and the predicted grain-size of the bed load using the Shields criterion is in accord with observed coarser grain-sizes in transport. These hydrodynamic data, delimited by estimates of the threshold of motion, and integrated over either flood or ebb tides are being used to explain the apparent stability of the bedforms. The bulk hydraulic data are supplemented by particle tracer studies and laser-scanning of bed configurations between tides. The high-energy environment results in two forms of armouring. Pronounced steep imbrication of platy-cobbles visible on the exposed up-estuary side of dunes is probably disrupted during flood tides leading to rapid reworking of the toe deposits facing up-estuary. In contrast, some crest and leeside locations have been stable for prolonged periods such that closely-fitted fabrics result; these portions of the bedforms are static and effectively are 'armour-plated'. Ebb-tide deposits of finer, ephemeral sandy-units occur on the down estuary side of the bedforms. Sandy-units (although

Golden Tides: Problem or Golden Opportunity? The Valorisation of Sargassum from Beach Inundations

Directory of Open Access Journals (Sweden)

John J. Milledge

2016-09-01

Full Text Available In recent years there have been massive inundations of pelagic Sargassum, known as golden tides, on the beaches of the Caribbean, Gulf of Mexico, and West Africa, causing considerable damage to the local economy and environment. Commercial exploration of this biomass for food, fuel, and pharmaceutical products could fund clean-up and offset the economic impact of these golden tides. This paper reviews the potential uses and obstacles for exploitation of pelagic Sargassum. Although Sargassum has considerable potential as a source of biochemicals, feed, food, fertiliser, and fuel, variable and undefined composition together with the possible presence of marine pollutants may make golden tides unsuitable for food, nutraceuticals, and pharmaceuticals and limit their use in feed and fertilisers. Discontinuous and unreliable supply of Sargassum also presents considerable challenges. Low-cost methods of preservation such as solar drying and ensiling may address the problem of discontinuity. The use of processes that can handle a variety of biological and waste feedstocks in addition to Sargassum is a solution to unreliable supply, and anaerobic digestion for the production of biogas is one such process. More research is needed to characterise golden tides and identify and develop commercial products and processes.

Correlations between solid tides and worldwide earthquakes MS ≥ 7.0 since 1900

Directory of Open Access Journals (Sweden)

Q. H. Xu

2012-03-01

Full Text Available Most studies on the correlations between earthquakes and solid tides mainly concluded the syzygies (i.e. new or full moons of each lunar cycle have more earthquakes than other days in the month. We show a correlation between the aftershock sequence of the ML = 6.3 Christchurch, New Zealand, earthquake and the diurnal solid tide. Ms ≥ 7 earthquakes worldwide since 1900 are more likely to occur during the 0°, 90°, 180° or 270° phases (i.e. earthquake-prone phases of the semidiurnal solid earth tidal curve (M2. Thus, the semidiurnal solid tides triggers earthquakes. However, the long-term triggering effect of the lunar periodicity is uncertain. This proposal is helpful in defining possible origin times of aftershocks several days after a mainshock and can be used for warning of subsequent larger shocks.

Nutrient environment of red tide- infested waters off south-west coast of India

Digital Repository Service at National Institute of Oceanography (India)

Joseph, T.; Shaiju, P.; Laluraj, C.M.; Balachandran, K.K.; Nair, M.; George, R.; Nair, K.K.C.; Sahayak, S.; Prabhakaran, M.P.

/Accepted: 28 August 2007 /Published online: 19 September 2007 # Springer Science + Business Media B.V. 2007 Abstract The bloom-infested waters along the south- west coast of India were assessed to bring about... tides, a natural phenomenon, are now common in many coastal waters. Various factors contribute to red tide formation such as insolation, wind, rain, salinity and nutrient input from land or by upwelling. Nitrogen and phosphorus are involved in phytoplank...

Possible forcing of global temperature by the oceanic tides

Science.gov (United States)

Keeling, Charles D.; Whorf, Timothy P.

1997-01-01

An approximately decadal periodicity in surface air temperature is discernable in global observations from A.D. 1855 to 1900 and since A.D. 1945, but with a periodicity of only about 6 years during the intervening period. Changes in solar irradiance related to the sunspot cycle have been proposed to account for the former, but cannot account for the latter. To explain both by a single mechanism, we propose that extreme oceanic tides may produce changes in sea surface temperature at repeat periods, which alternate between approximately one-third and one-half of the lunar nodal cycle of 18.6 years. These alternations, recurring at nearly 90-year intervals, reflect varying slight degrees of misalignment and departures from the closest approach of the Earth with the Moon and Sun at times of extreme tide raising forces. Strong forcing, consistent with observed temperature periodicities, occurred at 9-year intervals close to perihelion (solar perigee) for several decades centered on A.D. 1881 and 1974, but at 6-year intervals for several decades centered on A.D. 1923. As a physical explanation for tidal forcing of temperature we propose that the dissipation of extreme tides increases vertical mixing of sea water, thereby causing episodic cooling near the sea surface. If this mechanism correctly explains near-decadal temperature periodicities, it may also apply to variability in temperature and climate on other times-scales, even millennial and longer. PMID:11607740

Acoustic Tomography in the Canary Basin: Meddies and Tides

Science.gov (United States)

Dushaw, Brian D.; Gaillard, Fabienne; Terre, Thierry

2017-11-01

An acoustic propagation experiment over 308 km range conducted in the Canary Basin in 1997-1998 was used to assess the ability of ocean acoustic tomography to measure the flux of Mediterranean water and Meddies. Instruments on a mooring adjacent to the acoustic path measured the southwestward passage of a strong Meddy in temperature, salinity, and current. Over 9 months of transmissions, the acoustic arrival pattern was an initial broad stochastic pulse varying in duration by 250-500 ms, followed eight stable, identified-ray arrivals. Small-scale sound speed fluctuations from Mediterranean water parcels littered around the sound channel axis caused acoustic scattering. Internal waves contributed more modest acoustic scattering. Based on simulations, the main effect of a Meddy passing across the acoustic path is the formation of many early-arriving, near-axis rays, but these rays are thoroughly scattered by the small-scale Mediterranean-water fluctuations. A Meddy decreases the deep-turning ray travel times by 10-30 ms. The dominant acoustic signature of a Meddy is therefore the expansion of the width of the initial stochastic pulse. While this signature appears inseparable from the other effects of Mediterranean water in this region, the acoustic time series indicates the steady passage of Mediterranean water across the acoustic path. Tidal variations caused by the mode-1 internal tides were measured by the acoustic travel times. The observed internal tides were partly predicted using a recent global model for such tides derived from satellite altimetry.

Flood Tide Transport of Blue Crab Postlarvae: Limitations in a Lagoonal Estuary

Science.gov (United States)

Cudaback, C.; Eggleston, D.

2005-05-01

Blue crabs, an important commercial species, spend much of their life in estuaries along the east coast. The larvae spawn at or near the ocean, but the juveniles mature in the lower salinity waters of the estuary. It is generally believed that blue crab postlarvae migrate into near surface waters on flood, possibly cued by increasing salinity, and return to the bottom on ebb. Over several tidal cycles, the postlarvae travel a significant distance up-estuary. This model applies quite well to Chesapeake Bay, which has a strong along-estuary salinity gradient and large tides, but may not apply as well to Pamlico Sound, where circulation and salinity are more wind-driven than tidal. A recently completed study (N. Reyns, PhD), indicates that postlarval blue crabs use flood tides and wind-driven currents to cross Pamlico Sound. This study was based on observations with good spatial coverage, but limited vertical and temporal resolution. We have recently completed a complementary study, sampling crab larvae around the clock at four depths at a single location. Preliminary results from the new study suggest that the crab postlarvae do swim all the way to the surface, on flood only, and that flood currents are strongest slightly below the surface. These observations suggest the utility of flood tide transport in this system. However, near bottom salinity does not seem to be driven by tides; at this point it is unclear what cue might trigger the vertical migration of the postlarvae.

COCONet enhancements to circum-Caribbean tsunami warning, tidal, and sea-level monitoring: update on tide gauge installations

Science.gov (United States)

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

Red tides in the Gulf of Mexico: Where, when, and why?

Science.gov (United States)

Walsh, J. J.; Jolliff, J. K.; Darrow, B. P.; Lenes, J. M.; Milroy, S. P.; Remsen, A.; Dieterle, D. A.; Carder, K. L.; Chen, F. R.; Vargo, G. A.; Weisberg, R. H.; Fanning, K. A.; Muller-Karger, F. E.; Shinn, E.; Steidinger, K. A.; Heil, C. A.; Tomas, C. R.; Prospero, J. S.; Lee, T. N.; Kirkpatrick, G. J.; Whitledge, T. E.; Stockwell, D. A.; Villareal, T. A.; Jochens, A. E.; Bontempi, P. S.

2010-01-01

[1] Independent data from the Gulf of Mexico are used to develop and test the hypothesis that the same sequence of physical and ecological events each year allows the toxic dinoflagellate Karenia brevis to become dominant. A phosphorus-rich nutrient supply initiates phytoplankton succession, once deposition events of Saharan iron-rich dust allow Trichodesmium blooms to utilize ubiquitous dissolved nitrogen gas within otherwise nitrogen-poor sea water. They and the co-occurring K. brevis are positioned within the bottom Ekman layers, as a consequence of their similar diel vertical migration patterns on the middle shelf. Upon onshore upwelling of these near-bottom seed populations to CDOM-rich surface waters of coastal regions, light-inhibition of the small red tide of ~1 ug chl l–1 of ichthytoxic K. brevis is alleviated. Thence, dead fish serve as a supplementary nutrient source, yielding large, self-shaded red tides of ~10 ug chl l–1. The source of phosphorus is mainly of fossil origin off west Florida, where past nutrient additions from the eutrophied Lake Okeechobee had minimal impact. In contrast, the P-sources are of mainly anthropogenic origin off Texas, since both the nutrient loadings of Mississippi River and the spatial extent of the downstream red tides have increased over the last 100 years. During the past century and particularly within the last decade, previously cryptic Karenia spp. have caused toxic red tides in similar coastal habitats of other western boundary currents off Japan, China, New Zealand, Australia, and South Africa, downstream of the Gobi, Simpson, Great Western, and Kalahari Deserts, in a global response to both desertification and eutrophication. PMID:20411040

Performances of the New Real Time Tsunami Detection Algorithm applied to tide gauges data

Science.gov (United States)

Chierici, F.; Embriaco, D.; Morucci, S.

2017-12-01

Real-time tsunami detection algorithms play a key role in any Tsunami Early Warning System. We have developed a new algorithm for tsunami detection (TDA) based on the real-time tide removal and real-time band-pass filtering of seabed pressure time series acquired by Bottom Pressure Recorders. The TDA algorithm greatly increases the tsunami detection probability, shortens the detection delay and enhances detection reliability with respect to the most widely used tsunami detection algorithm, while containing the computational cost. The algorithm is designed to be used also in autonomous early warning systems with a set of input parameters and procedures which can be reconfigured in real time. We have also developed a methodology based on Monte Carlo simulations to test the tsunami detection algorithms. The algorithm performance is estimated by defining and evaluating statistical parameters, namely the detection probability, the detection delay, which are functions of the tsunami amplitude and wavelength, and the occurring rate of false alarms. In this work we present the performance of the TDA algorithm applied to tide gauge data. We have adapted the new tsunami detection algorithm and the Monte Carlo test methodology to tide gauges. Sea level data acquired by coastal tide gauges in different locations and environmental conditions have been used in order to consider real working scenarios in the test. We also present an application of the algorithm to the tsunami event generated by Tohoku earthquake on March 11th 2011, using data recorded by several tide gauges scattered all over the Pacific area.

Tides and lake-level variations in the great Patagonian lakes: Observations, modelling and geophysical implications.

Science.gov (United States)

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

A social marketing approach to implementing evidence-based practice in VHA QUERI: the TIDES depression collaborative care model

Science.gov (United States)

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

Thermal springs of Wyoming

Energy Technology Data Exchange (ETDEWEB)

Breckenridge, R.M.; Hinckley, B.S.

1978-01-01

This bulletin attempts, first, to provide a comprehensive inventory of the thermal springs of Wyoming; second, to explore the geologic and hydrologic factors producing these springs; and, third, to analyze the springs collectively as an indicator of the geothermal resources of the state. A general discussion of the state's geology and the mechanisms of thermal spring production, along with a brief comparison of Wyoming's springs with worldwide thermal features are included. A discussion of geothermal energy resources, a guide for visitors, and an analysis of the flora of Wyoming's springs follow the spring inventory. The listing and analysis of Wyoming's thermal springs are arranged alphabetically by county. Tabulated data are given on elevation, ownership, access, water temperature, and flow rate. Each spring system is described and its history, general characteristics and uses, geology, hydrology, and chemistry are discussed. (MHR)

Sea Level, Land Motion, and the Anomalous Tide at Churchill, Hudson Bay

Science.gov (United States)

Ray, R. D.

2015-12-01

The importance of the tide gauge at Churchill, Manitoba, cannot be overstated. It is the only permanently operating tide gauge in the central Canadian Arctic, and it sits on a prime spot for monitoring the mantle's rebound from the Laurentide ice loss. Yet interpretation of the sea-level time series at Churchill has long been problematic, going back even to early work by Gutenberg in the 1940s. The long-term relative sea-level rates are inconsistent: approximately -4, -19, -5 ± 1 mm/y for the periods 1940-1970, 1970-1990, 1990-2014 respectively. Annual mean high water (MHW) and mean low water (MLW) reflect these trends until around 1990, after which MLW leveled off and is now nearly unchanging. Slightly later, around 2000, the semidiurnal tides became very anomalous, with falling amplitudes and slightly increasing phase lags. The amplitude of M2 was approximately 154 cm before 2000; it dropped to about 146 cm by 2010 and reached an all-time low of 142 cm in 2014. Satellite altimeter estimates of the tide in this region, although challenging because of seasonal ice cover, show no comparable M2 changes, so the tidal changes must be localized to the near vicinity of the gauge (or to the gauge itself if caused by a malfunction). On the other hand, altimetry confirms the post-1992 Churchill measurements of mean sea level, thanks to the long time series of land motion measurements obtained at GPS station CHUR, which gives a vertical uplift of 10.1 mm/y. Combining satellite altimeter data with the Churchill tide-gauge data gives an implied vertical crustal rate of about 9.0 ± 0.8 mm/y, in reasonable agreement with the GPS. In summary, we have still anomalous MSL measurements at the Churchill gauge for the intermediate 1970-1990 era, and very anomalous tidal measurements since 2000, but we have apparently quite reliable MSL rates since 1990.

Spring 5 & reactive streams

CERN Multimedia

CERN. Geneva; Clozel, Brian

2017-01-01

Spring is a framework widely used by the world-wide Java community, and it is also extensively used at CERN. The accelerator control system is constituted of 10 million lines of Java code, spread across more than 1000 projects (jars) developed by 160 software engineers. Around half of this (all server-side Java code) is based on the Spring framework. Warning: the speakers will assume that people attending the seminar are familiar with Java and Spring’s basic concepts. Spring 5.0 and Spring Boot 2.0 updates (45 min) This talk will cover the big ticket items in the 5.0 release of Spring (including Kotlin support, @Nullable and JDK9) and provide an update on Spring Boot 2.0, which is scheduled for the end of the year. Reactive Spring (1h) Spring Framework 5.0 has been released - and it now supports reactive applications in the Spring ecosystem. During this presentation, we'll talk about the reactive foundations of Spring Framework with the Reactor project and the reactive streams specification. We'll al...

Global ocean tides through assimilation of oceanographic and altimeter satellite data in a hydrodynamic model

Science.gov (United States)

Leprovost, Christian; Mazzega, P.; Vincent, P.

1991-01-01

Ocean tides must be considered in many scientific disciplines: astronomy, oceanography, geodesy, geophysics, meteorology, and space technologies. Progress in each of these disciplines leads to the need for greater knowledge and more precise predictions of the ocean tide contribution. This is particularly true of satellite altimetry. On one side, the present and future satellite altimetry missions provide and will supply new data that will contribute to the improvement of the present ocean tide solutions. On the other side, tidal corrections included in the Geophysical Data Records must be determined with the maximum possible accuracy. The valuable results obtained with satellite altimeter data thus far have not been penalized by the insufficiencies of the present ocean tide predictions included in the geophysical data records (GDR's) because the oceanic processes investigated have shorter wavelengths than the error field of the tidal predictions, so that the residual errors of the tidal corrections are absorbed in the empirical tilt and bias corrections of the satellite orbit. For future applications to large-scale oceanic phenomena, however, it will no longer be possible to ignore these insufficiencies.

Oceanic geoid and tides derived from GEOS 3 satellite data in the Northwestern Atlantic Ocean

Science.gov (United States)

Won, I. J.; Miller, L. S.

1979-01-01

Two sets of GEOS 3 altimeter data which fall within about a 2.5-deg width are analyzed for ocean geoid and tides. One set covers a path from Newfoundland to Cuba, and the other a path from Puerto Rico to the North Carolina coast. Forty different analyses using various parameters are performed in order to investigate convergence. Profiles of the geoid and four tides, M2, O1, S2, and K1, are derived along the two strips. While the analyses produced convergent solutions for all 40 cases, the uncertainty caused by the linear orbital bias error of the satellite is too large to claim that the solutions represent the true ocean tides in the area. A spot check of the result with the Mode deep-sea tide gauge data shows poor agreement. A positive conclusion of this study is that despite the uncertain orbital error the oceanic geoid obtained through this analysis can improve significantly the short-wavelength structure over existing spherical harmonic geoid models.

Strontium isotopic composition of hot spring and mineral spring waters, Japan

International Nuclear Information System (INIS)

Notsu, Kenji; Wakita, Hiroshi; Nakamura, Yuji

1991-01-01

In Japan, hot springs and mineral springs are distributed in Quaternary and Neogene volcanic regions as well as in granitic, sedimentary and metamorphic regions lacking in recent volcanic activity. The 87 Sr/ 86 Sr ratio was determined in hot spring and mineral spring waters obtained from 47 sites. The ratios of waters from Quaternary and Neogene volcanic regions were in the range 0.703-0.708, which is lower than that from granitic, sedimentary and metamorphic regions (0.706-0.712). The geographical distribution of the ratios coincides with the bedrock geology, and particularly the ratios of the waters in Quaternary volcanic regions correlate with those of surrounding volcanic rocks. These features suggest that subsurface materials control the 87 Sr/ 86 Sr ratios of soluble components in the hot spring and mineral spring waters. (author)

A natural tracer investigation of the hydrological regime of Spring Creek Springs, the largest submarine spring system in Florida

Science.gov (United States)

Dimova, Natasha T.; Burnett, William C.; Speer, Kevin

2011-04-01

This work presents results from a nearly two-year monitoring of the hydrologic dynamics of the largest submarine spring system in Florida, Spring Creek Springs. During the summer of 2007 this spring system was observed to have significantly reduced flow due to persistent drought conditions. Our examination of the springs revealed that the salinity of the springs' waters had increased significantly, from 4 in 2004 to 33 in July 2007 with anomalous high radon ( 222Rn, t1/2=3.8 days) in surface water concentrations indicating substantial saltwater intrusion into the local aquifer. During our investigation from August 2007 to May 2009 we deployed on an almost monthly basis a continuous radon-in-water measurement system and monitored the salinity fluctuations in the discharge area. To evaluate the springs' freshwater flux we developed three different models: two of them are based on water velocity measurements and either salinity or 222Rn in the associated surface waters as groundwater tracers. The third approach used only salinity changes within the spring area. The three models showed good agreement and the results confirmed that the hydrologic regime of the system is strongly correlated to local precipitation and water table fluctuations with higher discharges after major rain events and very low, even reverse flow during prolong droughts. High flow spring conditions were observed twice during our study, in the early spring and mid-late summer of 2008. However the freshwater spring flux during our observation period never reached that reported from a 1970s value of 4.9×10 6 m 3/day. The maximum spring flow was estimated at about 3.0×10 6 m 3/day after heavy precipitation in February-March 2008. As a result of this storm (total of 173 mm) the salinity in the spring area dropped from about 27 to 2 in only two days. The radon-in-water concentrations dramatically increased in parallel, from about 330 Bq/m 3 to about 6600 Bq/m 3. Such a rapid response suggests a direct

Kilometric Scale Modeling of the North West European Shelf Seas: Exploring the Spatial and Temporal Variability of Internal Tides

Science.gov (United States)

Guihou, K.; Polton, J.; Harle, J.; Wakelin, S.; O'Dea, E.; Holt, J.

2018-01-01

The North West European Shelf break acts as a barrier to the transport and exchange between the open ocean and the shelf seas. The strong spatial variability of these exchange processes is hard to fully explore using observations, and simulations generally are too coarse to simulate the fine-scale processes over the whole region. In this context, under the FASTNEt program, a new NEMO configuration of the North West European Shelf and Atlantic Margin at 1/60° (˜1.8 km) has been developed, with the objective to better understand and quantify the seasonal and interannual variability of shelf break processes. The capability of this configuration to reproduce the seasonal cycle in SST, the barotropic tide, and fine-resolution temperature profiles is assessed against a basin-scale (1/12°, ˜9 km) configuration and a standard regional configuration (7 km resolution). The seasonal cycle is well reproduced in all configurations though the fine-resolution allows the simulation of smaller scale processes. Time series of temperature at various locations on the shelf show the presence of internal waves with a strong spatiotemporal variability. Spectral analysis of the internal waves reveals peaks at the diurnal, semidiurnal, inertial, and quarter-diurnal bands, which are only realistically reproduced in the new configuration. Tidally induced pycnocline variability is diagnosed in the model and shown to vary with the spring neap cycle with mean displacement amplitudes in excess of 2 m for 30% of the stratified domain. With sufficiently fine resolution, internal tides are shown to be generated at numerous bathymetric features resulting in a complex pycnocline displacement superposition pattern.

Observed tides at Mumbai High offshore region near the continental shelf break in the eastern Arabian Sea

Digital Repository Service at National Institute of Oceanography (India)

Joseph, A.; Vijaykumar, K.; Mehra, P.; Unnikrishnan, A.S.; Sundar, D.; Desai, R.G.P.

) at 15 min sampling interval using four tide gauges deployed from an oil drilling platform of the Oil and Natural Gas Corporation of India. All the four gauges provided identical measurements. The measured tides were harmonically analysed...

Response of the Water Level in a Well to Earth Tides and Atmospheric Loading Under Unconfined Conditions

Science.gov (United States)

Rojstaczer, Stuart; Riley, Francis S.

1990-08-01

The response of the water level in a well to Earth tides and atmospheric loading under unconfined conditions can be explained if the water level is controlled by the aquifer response averaged over the saturated depth of the well. Because vertical averaging tends to diminish the influence of the water table, the response is qualitatively similar to the response of a well under partially confined conditions. When the influence of well bore storage can be ignored, 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. When the theoretical response of a phreatic well to Earth tides and atmospheric loading is fit to the well response inferred from cross-spectral estimation, it is possible to obtain estimates of the pneumatic diffusivity of the unsaturated zone and the vertical hydraulic conductivity of the aquifer.

TIGA Tide Gauge Data Reprocessing at GFZ

Science.gov (United States)

Deng, Zhiguo; Schöne, Tilo; Gendt, Gerd

2014-05-01

To analyse the tide gauge measurements for the purpose of global long-term sea level change research a well-defined absolute reference frame is required by oceanographic community. To create such frame the data from a global GNSS network located at or near tide gauges are processed. For analyzing the GNSS data on a preferably continuous basis the International GNSS Service (IGS) Tide Gauge Benchmark Monitoring Working Group (TIGA-WG) is responsible. As one of the TIGA Analysis Centers the German Research Centre for Geosciences (GFZ) is contributing to the IGS TIGA Reprocessing Campaign. The solutions of the TIGA Reprocessing Campaign will also contribute to 2nd IGS Data Reprocessing Campaign with GFZ IGS reprocessing solution. After the first IGS reprocessing finished in 2010 some improvements were implemented into the latest GFZ software version EPOS.P8: reference frame IGb08 based on ITRF2008, antenna calibration igs08.atx, geopotential model (EGM2008), higher-order ionospheric effects, new a priori meteorological model (GPT2), VMF mapping function, and other minor improvements. GPS data of the globally distributed tracking network of 794 stations for the time span from 1994 until end of 2012 are used for the TIGA reprocessing. To handle such large network a new processing strategy is developed and described in detail. In the TIGA reprocessing the GPS@TIGA data are processed in precise point positioning (PPP) mode to clean data using the IGS reprocessing orbit and clock products. To validate the quality of the PPP coordinate results the rates of 80 GPS@TIGA station vertical movement are estimated from the PPP results using Maximum Likelihood Estimation (MLE) method. The rates are compared with the solution of University of LaRochelle Consortium (ULR) (named ULR5). 56 of the 80 stations have a difference of the vertical velocities below 1 mm/yr. The error bars of PPP rates are significant larger than those of ULR5, which indicates large time correlated noise in

A numerical study on the impact of nonlinear interactions on the amplitude of the migrating semidiurnal tide

Directory of Open Access Journals (Sweden)

C. M. Huang

2006-12-01

Full Text Available To quantitatively study the effects of nonlinear interactions on tide structure, a nonlinear numerical tidal model is developed, and the reliability and convergence of the adopted algorithm and coding are checked by numerical experiments. Under the same conditions as those employed by the GSWM-00 (Global Scale Wave Model 2000, our model provides the nonlinear quasi-steady solution of the migrating semidiurnal tide, which differs from the GSWM-00 result (the linear steady solution in the MLT region, especially above 100 km. Additionally, their amplitude difference displays a remarkable month-to-month variation, and its significant magnitudes occur during the month with strong semidiurnal tide. A quantitative analysis suggests that the main cause for the amplitude difference is that the initial migrating 12-h tide will interact with the mean flow as well as the nonlinearity-excited 6-h tide, and subsequently yield a new 12-h tidal part. Furthermore, our simulations also show that the mean flow/tidal interaction will significantly alter the background wind and temperature fields. The large magnitudes of the tidal amplitude difference and the background alteration indicate that the nonlinear processes involved in tidal propagations should be comprehensively considered in the description of global atmospheric dynamics in the MLT region. The comparisons among our simulations, the GSWMs and some observations of tides suggest that the nonlinearity-induced tidal structure variation could be a possible mechanism to account for some discrepancies between the GSWMs and the observations.

Using inquiry-based instruction with Web-based data archives to facilitate conceptual change about tides among preservice teachers

Science.gov (United States)

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

Tides, main lunar phases and babies

OpenAIRE

Silveira, Fernando Lang da; UFRGS - Rio Grande do Sul

2003-01-01

The mechanisms responsible for the tides are discussed, using mathematics that is accessible to secondary school students; we show that both the Moon and the Sun are responsible for the tidal effects on the oceans. Despite the gravitational pull of the Sun on the Earth being approximately 200 times greater than that of the Moon, solar tidal effects are approximately half those of the lunar effects. We present a study of 104,616 dates of birth, with the intention of identi...

Instant Spring Tool Suite

CERN Document Server

Chiang, Geoff

2013-01-01

Filled with practical, step-by-step instructions and clear explanations for the most important and useful tasks. A tutorial guide that walks you through how to use the features of Spring Tool Suite using well defined sections for the different parts of Spring.Instant Spring Tool Suite is for novice to intermediate Java developers looking to get a head-start in enterprise application development using Spring Tool Suite and the Spring framework. If you are looking for a guide for effective application development using Spring Tool Suite, then this book is for you.

DIOPS: A PC-Based Wave, Tide and Surf Prediction System

National Research Council Canada - National Science Library

Allard, Richard; Dykes, James; Kaihatu, James; Wakeham, Dean

2005-01-01

The Distributed Integrated Ocean Prediciton System (DIOPS) is a PC-based wave tide and surf prediction system designed to provide DoD accurate and timely surf predictions for essentially any world-wide location...

ENERGY DISSIPATION THROUGH QUASI-STATIC TIDES IN WHITE DWARF BINARIES

International Nuclear Information System (INIS)

Willems, B.; Deloye, C. J.; Kalogera, V.

2010-01-01

We present a formalism to study tidal interactions in white dwarf binaries in the limiting case of quasi-static tides, in which the tidal forcing frequencies are small, compared to the inverse of the white dwarf's dynamical timescale. The formalism is valid for arbitrary orbital eccentricities and therefore applicable to white dwarf binaries in the Galactic disk as well as globular clusters. In the quasi-static limit, the total perturbation of the gravitational potential shows a phase shift with respect to the position of the companion, the magnitude of which is determined primarily by the efficiency of energy dissipation through convective damping. We determine rates of secular evolution of the orbital elements and white dwarf rotational angular velocity for a 0.3 M sun helium white dwarf in binaries with orbital frequencies in the Laser Interferometer Space Antenna (LISA) gravitational wave frequency band and companion masses ranging from 0.3 M sun to 10 5 M sun . The resulting tidal evolution timescales for the orbital semimajor axis are longer than a Hubble time, so that convective damping of quasi-static tides need not be considered in the construction of gravitational wave templates of white dwarf binaries in the LISA band. Spin-up of the white dwarf, on the other hand, can occur on timescales of less than 10 Myr, provided that the white dwarf is initially rotating with a frequency much smaller than the orbital frequency. For semi-detached white dwarf binaries spin-up can occur on timescales of less than 1 Myr. Nevertheless, the timescales remain longer than the orbital inspiral timescales due to gravitational radiation, so that the degree of asynchronism in these binaries increases. As a consequence, tidal forcing eventually occurs at forcing frequencies beyond the quasi-static tide approximation. For the shortest period binaries, energy dissipation is therefore expected to take place through dynamic tides and resonantly excited g-modes.

On a rising tide

International Nuclear Information System (INIS)

Perera, J.

1998-01-01

The world's oceans contain an enormous potential source of energy. What is surprising is how little this potential is exploited. Now however researchers are beginning to make progress in pursuit of a renewable energy that has been elusive. So far two major sites that can sustain tidal power projects have been identified in India: the Gulf of Bombay and the Gulf of Kutch with a mean tidal range of five and seven metres respectively. They have a combined potential of 9700 MW. The environmental impacts of any tidal power scheme will depend mainly on local geography. Local tides changed only slightly as a result of the La Rance barrage, and the environmental impact has been negligible, but other sites could face more serious problems. (author)

Effect of Southern Hemisphere Sudden Stratospheric Warmings on Antarctica Mesospheric Tides: First Observational Study

Science.gov (United States)

Eswaraiah, S.; Kim, Yong Ha; Lee, Jaewook; Ratnam, M. Vankat; Rao, S. V. B.

2018-03-01

We analyzed the structure and variability of observed winds and tides in the Antarctica mesosphere and lower thermosphere (MLT) during the 2002 major sudden stratospheric warming (SSW) and the 2010 minor SSWs. We noted the effect of SSW on the variability of MLT tides for the first time in the Southern Hemisphere, although it has been well recognized in the Northern Hemisphere. We utilized the winds measured by Rothera (68°S, 68°W) medium frequency radar and King Sejong Station (62.22°S, 58.78°W) meteor radar for estimating the tidal components (diurnal, semi-diurnal, and ter-diurnal) in the MLT region. The unusual behavior of diurnal tide (DT) and semidiurnal tide (SDT) was observed in 2002. Zonal SDT amplitudes were enhanced up to 27 m/s after 18 days from the associated SSW day. However, the meridional tidal amplitudes of both DT and SDT suddenly decreased during the peak SSW, and SDT amplitudes slightly increased to 18 m/s afterward. In the normal years, SDT amplitude stays below 15 m/s. During the 2010 SSW, SDT zonal amplitudes increased up to 40 m/s and 50 m/s at altitudes of 80 km and 90 km, respectively, 30 days after the associated SSW. Similar but weaker effect is noticed in the meridional components. The ter-diurnal tide does not show any significant variation during the SSW. The two SSWs offered a challenging issue to answer: why tidal amplitudes are enhanced with a delay after the SSW. The reasons for the delay are discussed in accordance with theoretical predictions.

Estimating decadal variability in sea level from tide gauge records: An application to the North Sea

NARCIS (Netherlands)

Frederikse, Thomas; Riva, R.E.M.; Slobbe, Cornelis; Broerse, D.B.T.; Verlaan, Martin

2016-01-01

One of the primary observational data sets of sea level is represented by the tide gauge record. We propose a new method to estimate variability on decadal time scales from tide gauge data by using a state space formulation, which couples the direct observations to a predefined state space model by

Estimating decadal variability in sea level from tide gauge records : An application to the North Sea

NARCIS (Netherlands)

Frederikse, T.; Riva, R.E.M.; Slobbe, D.C.; Broerse, D.B.T.; Verlaan, M.

2016-01-01

One of the primary observational data sets of sea level is represented by the tide gauge record. We propose a new method to estimate variability on decadal time scales from tide gauge data by using a state space formulation, which couples the direct observations to a predefined state space model

Longitudinal, seasonal and solar cycle variation in lunar tide influence on the equatorial electrojet

International Nuclear Information System (INIS)

Yizengaw, Endawoke; Carter, Brett A.

2017-01-01

It has been well documented that the lunar tidal waves can modulate the ionospheric electrodynamics and create a visible influence on the equatorial electrojet (EEJ). The lunar tide influence gets intensified around noon, primarily during new and full Moon periods. However, the longitudinal, seasonal and solar cycle variability in the lunar tide influence on ionospheric current systems is not well understood yet. In order to investigate this, 17 years (1998-2014) of extensive magnetometer observations at four longitudinal sectors (western American, western and eastern African, and Asian) have been analyzed. All observations performed during magnetically active periods (K p >3) have been excluded for this study to eliminate storm contributions to the geomagnetic field variation at the geomagnetic equator. This study's quantitative analysis revealed significant longitudinal, seasonal and solar cycle dependence of the lunar tide influence on the equatorial electrojet.

Longitudinal, seasonal and solar cycle variation in lunar tide influence on the equatorial electrojet

Energy Technology Data Exchange (ETDEWEB)

Yizengaw, Endawoke [Boston College, Chestnut Hill, MA (United States). Inst. for Scientific Research; Carter, Brett A. [RMIT Univ., Melbourne, VIC (Australia). SPACE Research Centre

2017-07-01

It has been well documented that the lunar tidal waves can modulate the ionospheric electrodynamics and create a visible influence on the equatorial electrojet (EEJ). The lunar tide influence gets intensified around noon, primarily during new and full Moon periods. However, the longitudinal, seasonal and solar cycle variability in the lunar tide influence on ionospheric current systems is not well understood yet. In order to investigate this, 17 years (1998-2014) of extensive magnetometer observations at four longitudinal sectors (western American, western and eastern African, and Asian) have been analyzed. All observations performed during magnetically active periods (K{sub p}>3) have been excluded for this study to eliminate storm contributions to the geomagnetic field variation at the geomagnetic equator. This study's quantitative analysis revealed significant longitudinal, seasonal and solar cycle dependence of the lunar tide influence on the equatorial electrojet.

Pro Spring Integration

CERN Document Server

Lui, M; Chan, Andy; Long, Josh

2011-01-01

Pro Spring Integration is an authoritative book from the experts that guides you through the vast world of enterprise application integration (EAI) and application of the Spring Integration framework towards solving integration problems. The book is:. * An introduction to the concepts of enterprise application integration * A reference on building event-driven applications using Spring Integration * A guide to solving common integration problems using Spring Integration What makes this book unique is its coverage of contemporary technologies and real-world information, with a focus on common p

Rhythms of locomotion expressed by Limulus polyphemus, the American horseshoe crab: I. Synchronization by artificial tides.

Science.gov (United States)

Chabot, Christopher C; Skinner, Stephen J; Watson, Winsor H

2008-08-01

Limulus polyphemus, the American horseshoe crab, has an endogenous clock that drives circatidal rhythms of locomotor activity. In this study, we examined the ability of artificial tides to entrain the locomotor rhythms of Limulus in the laboratory. In experiments one and two, the activity of 16 individuals of L. polyphemus was monitored with activity boxes and "running wheels." When the crabs were exposed to artificial tides created by changes in water depth, circatidal rhythms were observed in animals exposed to 12.4-h "tidal" cycles of either water depth changes (8 of 8 animals) or inundation (7 of 8 animals). In experiment three, an additional 8 animals were exposed to water depth changes under cyclic conditions of light and dark and then monitored for 10 days with no imposed artificial tides. Most animals (5) clearly synchronized their activity to the imposed artificial tidal cycles, and 3 of these animals showed clear evidence of entrainment after the artificial tides were terminated. Overall, these results demonstrate that the endogenous tidal clock that influences locomotion in Limulus can be entrained by imposed artificial tides. In the laboratory, these tidal cues override the influence of light/dark cycles. In their natural habitat, where both tidal and photoperiod inputs are typically always present, their activity rhythms are likely to be much more complex.

Nutrient and chlorophyll a anomaly in red-tide periods of 2003-2008 in Sishili Bay, China

Science.gov (United States)

Hao, Yanju; Tang, Danling; Yu, Long; Xing, Qianguo

2011-05-01

Sishili Bay is the most important aquiculture and tourism area for the city of Yantai, China; however, red tides occurred frequently and have caused huge economic losses in this bay in recent years. To gain a better understanding of the local ecological environments in the bay, we conducted this research between 2003 and 2008 to analyze variations in nutrients and chlorophyll (chl- a) during high frequency red tide period (May to September). The results show that the chl- a concentration increased from 2.70 in 2003 to 7.26 mg/m3 in 2008, while the concentration of total inorganic nitrogen (TIN) and silicate (SiO3-Si) increased lineally from 5.18 and 1.45 μmol/L in 2003 to 18.57 and 9.52 μmol/L in 2008, respectively, and the annual phosphate (PO4-P) varied between 0.15 and 0.46 μmol/L. Special attention was given to a red tide in August 2007 occurred when water temperature was high and nutrient concentrations increased sharply because of a heavy rainfall. Overall, the results show the P limitation in Sishili Bay, and reveal that red tides were caused by eutrophication from terrestrial inputs and local warm weather, particularly during rainy periods. Therefore, to control red tide, greater efforts should be made to reduce sewage discharges into Sishili Bay, particularly during rainfall seasons.

Representation of solar tides in the stratosphere and lower mesosphere in state-of-the-art reanalyses and in satellite observations

Science.gov (United States)

Sakazaki, Takatoshi; Fujiwara, Masatomo; Shiotani, Masato

2018-02-01

Atmospheric solar tides in the stratosphere and the lower mesosphere are investigated using temperature data from five state-of-the-art reanalysis data sets (MERRA-2, MERRA, JRA-55, ERA-Interim, and CFSR) as well as TIMED SABER and Aura MLS satellite measurements. The main focus is on the period 2006-2012 during which the satellite observations are available for direct comparison with the reanalyses. Diurnal migrating tides, semidiurnal migrating tides, and nonmigrating tides are diagnosed. Overall the reanalyses agree reasonably well with each other and with the satellite observations for both migrating and nonmigrating components, including their vertical structure and the seasonality. However, the agreement among reanalyses is more pronounced in the lower stratosphere and relatively weaker in the upper stratosphere and mesosphere. A systematic difference between SABER and the reanalyses is found for diurnal migrating tides in the upper stratosphere and the lower mesosphere; specifically, the amplitude of trapped modes in reanalyses is significantly smaller than that in SABER, although such difference is less clear between MLS and the reanalyses. The interannual variability and the possibility of long-term changes in migrating tides are also examined using the reanalyses during 1980-2012. All the reanalyses agree in exhibiting a clear quasi-biennial oscillation (QBO) in the tides, but the most significant indications of long-term changes in the tides represented in the reanalyses are most plausibly explained by the evolution of the satellite observing systems during this period. The tides are also compared in the full reanalyses produced by the Japan Meteorological Agency (i.e., JRA-55) and in two parallel data sets from this agency: one (JRA-55C) that repeats the reanalysis procedure but without any satellite data assimilated and one (JRA-55AMIP) that is a free-running integration of the model constrained only by observed sea surface temperatures. Many aspects

High-Resolution Wave Energy Assessment in Shallow Water Accounting for Tides

Directory of Open Access Journals (Sweden)

Dina Silva

2016-09-01

Full Text Available The wave energy in a shallow water location is evaluated considering the influence of the local tide and wind on the wave propagation. The target is the coastal area just north of the Portuguese city of Peniche, where a wave energy converter operates on the sea bottom. A wave modelling system based on SWAN has been implemented and focused on this coastal environment in a multilevel computational scheme. The first three SWAN computational belonging to this wave prediction system were defined using the spherical coordinates. In the highest resolution computational domain, Cartesian coordinates have been considered, with a resolution of 25 m in both directions. An in-depth analysis of the main characteristics of the environmental matrix has been performed. This is based on the results of eight-year model system simulations (2005–2012. New simulations have been carried out in the last two computational domains with the most relevant wave and wind patterns, considering also the tide effect. The results show that the tide level, together with the wind intensity and direction, may influence to a significant degree the wave characteristics. This especially concerns the wave power in the location where the wave converter operates.

The complete spectrum of the equatorial electrojet related to solar tides: CHAMP observations

Directory of Open Access Journals (Sweden)

H. Lühr

2013-08-01

Full Text Available Based on 10 yr of magnetic field measurements by the CHAMP satellite we draw a detailed picture of the equatorial electrojet (EEJ tidal variations. For the first time the complete EEJ spectrum related to average solar tides has been compiled. A large fraction of the resulting spectrum is related to the switch on/off of the EEJ between day and night. This effect has carefully been considered when interpreting the results. As expected, largest amplitudes are caused by the migrating tides representing the mean diurnal variation. Higher harmonics of the daily variations show a 1/f fall-off in amplitude. Such a spectrum is required to represent the vanishing of the EEJ current at night. The migrating tidal signal exhibits a distinct annual variation with large amplitudes during December solstice and equinox seasons but a depression by a factor of 1.7 around June–July. A rich spectrum of non-migrating tidal effects is deduced. Most prominent is the four-peaked longitudinal pattern around August. Almost 90% of the structure can be attributed to the diurnal eastward-propagating tide DE3. In addition the westward-propagating DW5 is contributing to wave-4. The second-largest non-migrating tide is the semi-diurnal SW4 around December solstice. It causes a wave-2 feature in satellite observations. The three-peaked longitudinal pattern, often quoted as typical for the December season, is significantly weaker. During the months around May–June a prominent wave-1 feature appears. To first order it represents a stationary planetary wave SPW1 which causes an intensification of the EEJ at western longitudes beyond 60° W and a weakening over Africa/India. In addition, a prominent ter-diurnal non-migrating tide TW4 causes the EEJ to peak later, at hours past 14:00 local time in the western sector. A particularly interesting non-migrating tide is the semi-diurnal SW3. It causes largest EEJ amplitudes from October through December. This tidal component shows a

Evidence for infragravity wave-tide resonance in deep oceans.

Science.gov (United States)

Sugioka, Hiroko; Fukao, Yoshio; Kanazawa, Toshihiko

2010-10-05

Ocean tides are the oscillatory motions of seawater forced by the gravitational attraction of the Moon and Sun with periods of a half to a day and wavelengths of the semi-Pacific to Pacific scale. Ocean infragravity (IG) waves are sea-surface gravity waves with periods of several minutes and wavelengths of several dozen kilometres. Here we report the first evidence of the resonance between these two ubiquitous phenomena, mutually very different in period and wavelength, in deep oceans. The evidence comes from long-term, large-scale observations with arrays of broadband ocean-bottom seismometers located at depths of more than 4,000 m in the Pacific Ocean. This observational evidence is substantiated by a theoretical argument that IG waves and the tide can resonantly couple and that such coupling occurs over unexpectedly wide areas of the Pacific Ocean. Through this resonant coupling, some of ocean tidal energy is transferred in deep oceans to IG wave energy.

Observing atmospheric tides in Earth rotation parameters with VLBI

Science.gov (United States)

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.

Use of nucleoside (tide) analogues in patients with hepatitis B-related acute liver failure

DEFF Research Database (Denmark)

Dao, Doan Y; Seremba, Emmanuel; Ajmera, Veeral

2012-01-01

The efficacy of nucleoside(tide) analogues (NA) in the treatment of acute liver failure due to hepatitis B virus (HBV-ALF) remains controversial. We determined retrospectively the impact of NAs in a large cohort of patients with HBV-ALF.......The efficacy of nucleoside(tide) analogues (NA) in the treatment of acute liver failure due to hepatitis B virus (HBV-ALF) remains controversial. We determined retrospectively the impact of NAs in a large cohort of patients with HBV-ALF....

Seasonal variability of Internal tide energetics in the western Bay of Bengal

Science.gov (United States)

Mohanty, S.; Rao, A. D.

2017-12-01

The Internal Waves (IWs) are generated by the flow of barotropic tide over the rapidly varying and steep topographic features like continental shelf slope, seamounts, etc. These waves are an important phenomena in the ocean due to their influence on the density structure and energy transfer into the region. Such waves are also important in submarine acoustics, underwater navigation, offshore structures, ocean mixing and biogeochemical processes, etc. over the shelf-slope region. The seasonal variability of internal tides in the western Bay of Bengal is examined by using three-dimensional MITgcm model. The numerical simulations are performed for different periods covering August-September, 2013; November-December, 2013 and March-April, 2014 representing monsoon, post-monsoon and pre-monsoon seasons respectively during which high temporal resolution observed data sets are available. The model is initially validated through the spectral estimate of density and the baroclinic velocities. From the estimate, it is found that its peak is associated with the semi-diurnal frequency at all the depths in both observations and model simulations for November-December and March-April. However in August, the estimate is found to be maximum near the inertial frequency at all available depths. EOF analysis suggests that about 70-80% of the total variance comes from Mode-1 semi-diurnal internal tide in both observations as well as in the model simulations. The phase speed, group speed and wavelength are found to be maximum for post-monsoon season compared to other two seasons. To understand the generation and propagation of internal tides over this region, barotropic-to-baroclinic M2 tidal energy conversion and energy flux are examined. The barotropic-to-baroclinic conversion occurs intensively along the shelf-slope regions and propagate towards the coast. The model simulated energy dissipation rate infers that its maximum occurs at the generation sites and hence the local mixing

Longitudinal, seasonal and solar cycle variation in lunar tide influence on the equatorial electrojet

Directory of Open Access Journals (Sweden)

E. Yizengaw

2017-04-01

Full Text Available It has been well documented that the lunar tidal waves can modulate the ionospheric electrodynamics and create a visible influence on the equatorial electrojet (EEJ. The lunar tide influence gets intensified around noon, primarily during new and full Moon periods. However, the longitudinal, seasonal and solar cycle variability in the lunar tide influence on ionospheric current systems is not well understood yet. In order to investigate this, 17 years (1998–2014 of extensive magnetometer observations at four longitudinal sectors (western American, western and eastern African, and Asian have been analyzed. All observations performed during magnetically active periods (Kp>3 have been excluded for this study to eliminate storm contributions to the geomagnetic field variation at the geomagnetic equator. This study's quantitative analysis revealed significant longitudinal, seasonal and solar cycle dependence of the lunar tide influence on the equatorial electrojet.

Physical-biological coupling induced aggregation mechanism for the formation of high biomass red tides in low nutrient waters.

Science.gov (United States)

Lai, Zhigang; Yin, Kedong

2014-01-01

Port Shelter is a semi-enclosed bay in northeast Hong Kong where high biomass red tides are observed to occur frequently in narrow bands along the local bathymetric isobars. Previous study showed that nutrients in the Bay are not high enough to support high biomass red tides. The hypothesis is that physical aggregation and vertical migration of dinoflagellates appear to be the driving mechanism to promote the formation of red tides in this area. To test this hypothesis, we used a high-resolution estuarine circulation model to simulate the near-shore water dynamics based on in situ measured temperature/salinity profiles, winds and tidal constitutes taken from a well-validated regional tidal model. The model results demonstrated that water convergence occurs in a narrow band along the west shore of Port Shelter under a combined effect of stratified tidal current and easterly or northeasterly wind. Using particles as dinoflagellate cells and giving diel vertical migration, the model results showed that the particles aggregate along the convergent zone. By tracking particles in the model predicted current field, we estimated that the physical-biological coupled processes induced aggregation of the particles could cause 20-45 times enhanced cell density in the convergent zone. This indicated that a high cell density red tide under these processes could be initialized without very high nutrients concentrations. This may explain why Port Shelter, a nutrient-poor Bay, is the hot spot for high biomass red tides in Hong Kong in the past 25 years. Our study explains why red tide occurrences are episodic events and shows the importance of taking the physical-biological aggregation mechanism into consideration in the projection of red tides for coastal management. Copyright © 2013 Elsevier B.V. All rights reserved.

Monitoring storm tide and flooding from Hurricane Matthew along the Atlantic coast of the United States, October 2016

Science.gov (United States)

Frantz, Eric R.; Byrne,, Michael L.; Caldwell, Andral W.; Harden, Stephen L.

2017-11-02

IntroductionHurricane Matthew moved adjacent to the coasts of Florida, Georgia, South Carolina, and North Carolina. The hurricane made landfall once near McClellanville, South Carolina, on October 8, 2016, as a Category 1 hurricane on the Saffir-Simpson Hurricane Wind Scale. The U.S. Geological Survey (USGS) deployed a temporary monitoring network of storm-tide sensors at 284 sites along the Atlantic coast from Florida to North Carolina to record the timing, areal extent, and magnitude of hurricane storm tide and coastal flooding generated by Hurricane Matthew. Storm tide, as defined by the National Oceanic and Atmospheric Administration, is the water-level rise generated by a combination of storm surge and astronomical tide during a coastal storm.The deployment for Hurricane Matthew was the largest deployment of storm-tide sensors in USGS history and was completed as part of a coordinated Federal emergency response as outlined by the Stafford Act (Public Law 92–288, 42 U.S.C. 5121–5207) under a directed mission assignment by the Federal Emergency Management Agency. In total, 543 high-water marks (HWMs) also were collected after Hurricane Matthew, and this was the second largest HWM recovery effort in USGS history after Hurricane Sandy in 2012.During the hurricane, real-time water-level data collected at temporary rapid deployment gages (RDGs) and long-term USGS streamgage stations were relayed immediately for display on the USGS Flood Event Viewer (https://stn.wim.usgs.gov/FEV/#MatthewOctober2016). These data provided emergency managers and responders with critical information for tracking flood-effected areas and directing assistance to effected communities. Data collected from this hurricane can be used to calibrate and evaluate the performance of storm-tide models for maximum and incremental water level and flood extent, and the site-specific effects of storm tide on natural and anthropogenic features of the environment.

Human responses to Florida red tides: policy awareness and adherence to local fertilizer ordinances.

Science.gov (United States)

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. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of internal tides in the distribution and abundance of microzooplankton in Todos Santos Bay (Ensenada, B.C.)

Science.gov (United States)

Valencia, A.; Ibañez Tejero, L.; Ladah, L. B.; Sanchez Velasco, L.; Barton, E. D.

2016-02-01

Microzooplankton trophically connects phytoplankton and zooplanktonic adults. Their distribution and abundance can be directly related to the inherent physical processes in the marine environment. In coastal waters, the distribution and transport of zooplankton, including microzooplankton, can be influenced by high frequency effects such as internal tides. To date, most of the work on planktonic organisms and their interaction with the internal tide has been focused on a few species, such as barnacles, bryozoans and crabs. The aim of this study was to determine the effect of internal tide on the vertical distribution and abundance of microzooplankton, with an emphasis on copepod nauplii, during the evolution of the internal tide in a summer period of strong thermal stratification. Samples were obtained by vertical plankton net (150 micron mesh) hauls at three depth strata (surface, mid-water and bottom in 25 m depth), independently, with a sampling frequency of every hour. The internal tide was detected by rapid changes in temperature and currents observed with thermistor chains and a bottom-mounted upward looking ADCP. Preliminary results shows a strong mode-1 baroclinic tidal signal. The highest abundance of copepod nauplii and microzooplankton biomass occurred at depth, associated with a strong tidal current. The abundance of copepod nauplii and the abundance of microzooplankton biomass in the surface and intermediate strata showed strong vertical displacements between both strata. Data suggest the vertical distribution of microzooplankton can be dependent on the internal tide.

Oceanic Geoid and Tides Obtained from GEOS-3 Satellite Data in the Northwestern Atlantic Ocean

Science.gov (United States)

Won, I. J.; Miller, L. S.

1978-01-01

Two sets of GEO-3 altimeter data which fall within about a 2.5 degree width are analyzed for ocean geoid and tides. One set covers a linear path from Newfoundland to Cuba and the other from Puerto Rico to the North Carolina coast. Forty different analyses using various parameters are performed in order to investigate convergence. Profiles of the geoid and four tides, M sub 2 O sub 1, S sub 2, and K sub 1, are obtained along the two strips. The results demonstrate convergent solutions for all forty cases and show, within expectation, fair agreement with those obtained from the MODE deep-sea tide gauge. It is also shown that the oceanic geoid obtained through this analysis can potentially improve the short wavelength structure over existing geoid models.

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

Science.gov (United States)

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. Copyright © 2012 Elsevier Ltd. All rights reserved.

RETAID DI PERAIRAN PESISIR BARAT TABLASUPA KABUPATEN JAYAPURA, PAPUA (Red-tide at Western Coast of Tablasupa, Jayapura, Papua

Directory of Open Access Journals (Sweden)

Suwarno Hadisusanto

2010-11-01

Full Text Available ABSTRAK Retaid (red-tide adalah fenomena alam yang sering terjadi baik di perairan laut dan tawar. Fenomena ini menunjukkan perubahan warna dari biru laut menjadi merah, coklat, kuning bahkan putih susu. Penelitian ini bertujuan untuk mengetahui potensi terjadinya retaid di perairan Tablasupa, Jayapura, Papua. Pencuplikan plankton dilakukan pada tanggal 8-10 Agustus 2007 di dua lokasi dengan empat ulangan waktu (pagi, siang, sore dan malanr. Hasil analisis laboratorium menunjukkan adanya 18 genus tetapi hanya dua genus yang berpotensi menimbulkan retaid yaitu Ceratium dan Chaetoceros. Kemungkinan kecil terjadinya retaid di perairan Tablasupa karena kemelimpahan fitoplankton cukup rendah.   ABSTRACT Red-tide is natural fenomenon and can be raised at marine and fresh-waters. This fenomenon was visualized by color changes from dark-blue to become redess, browness, yellowish and milkess. The objectives to find red-tide potentially at Tablasupa west coast, Jayapura, Papua. The sample was collected on August 8-10st, 2007, at two locations and four replicated. The results there were 18 genera and two red-tide potential genera was Ceratium dan Chaetoceros. There will no red-tide in Tablasupa because low abundance of phytoplankton.

A three-dimensional mixed finite-difference Galerkin function model for the oceanic circulation in the Yellow Sea and the East China Sea in the presence of M 2 tide

Science.gov (United States)

Lee, Ho Jin; Jung, Kyung Tae; So, Jae Kwi; Chung, Jong Yul

2002-01-01

. Calculation with an inflow of 25.1 Sv through open boundaries on both sides of Taiwan shows that 1.15 Sv goes through Korea/Tsushima Strait, 0.36 Sv through the north of Tokara Strait (between Kyushu and Yakushima Island), 20.95 Sv through Tokara Strait and 2.77 Sv through open boundaries along the Ryukyu Islands. Calculations with fortnightly variation in M 2 open boundary forcings show that the oceanic circulation as well as tidal residuals vary significantly in the southern Yellow Sea; penetration of oceanic flows into the Yellow Sea occurs deeper at the neap tide than at the spring tide. The seasonal variation in the volume transport of the oceanic inflows/outflows without baroclinic effects has little effect on the exchange between the YS and the ECS.

Estimating aquifer properties from the water level response to Earth tides.

Science.gov (United States)

Cutillo, Paula A; Bredehoeft, John D

2011-01-01

Water level fluctuations induced by tidal strains can be analyzed to estimate the elastic properties, porosity, and transmissivity of the surrounding aquifer material. We review underutilized methods for estimating aquifer properties from the confined response to earth tides. The earth tide analyses are applied to an open well penetrating a confined carbonate aquifer. The resulting range of elastic and hydraulic aquifer properties are in general agreement with that determined by other investigators for the area of the well. The analyses indicate that passive monitoring data from wells completed in sufficiently stiff, low porosity formations can provide useful information on the properties of the surrounding formation. Journal compilation © 2010 National Ground Water Association. No claim to original US government works.

Water level fluctuations due to earth tides in a well pumping from slightly fractured crystalline rock

International Nuclear Information System (INIS)

Marine, I.W.

1975-01-01

J At the Savannah River plant of the Atomic Energy Commission near Aiken, South Carolina, there are three distinct groundwater systems: the coastal plain sediments, the crystalline metamorphic rocks, and a buried Triassic basin. The coastal plain sediments include several Cretaceous and Tertiary granular aquifers and aquicludes, the total thickness being about 305 m. Below these sediments, water occurs in small fractures in crystalline metamorphic rock (hornblende schist and gneiss with lesser amounts of quartzite). Water level fluctuations due to earth tides are recorded in the crystalline metamorphic rock system and in the coastal plain sediments. No water level fluctuations due to earth tides have been observed in wells in the Triassic rock because of the very low permeability. The water level fluctuations due to earth tides in the crystalline rock are about 10 cm, and those in the sediments are about 1.8 cm. The use of water level fluctuations due to earth tides to calculate porosity appears to present practical difficulties both in the crystalline metamorphic rock system and in the coastal plain sediments. In a 1-yr pumping test on a well in the crystalline metamorphic rock the flow was controlled to within 0.1 percent of the total discharge, which was 0.94 1/s. The water level fluctuations due to earth tides in the pumping well were 10 cm, the same as when this well was not being pumped. (U.S.)

Water-level fluctuations due to Earth tides in a well pumping from slightly fractured crystalline rock

International Nuclear Information System (INIS)

Marine, I.W.

1975-01-01

At the Savannah River plant of the Atomic Energy Commission near Aiken, South Carolina, there are three distinct groundwater systems: the coastal plain sediments, the crystalline metamorphic rocks, and a buried Triassic basin. The coastal plain sediments include several Cretaceous and Tertiary granular aquifers and aquicludes, the total thickness being about 305 m. Below these sediments, water occurs in small fractures in crystalline metamorphic rock (hornblende schist and gneiss with lesser amounts of quartzite). Water level fluctuations due to earth tides are recorded in the crystalline metamorphic rock system and in the coastal plain sediments. No water level fluctuations due to earth tides have been observed in wells in the Triassic rock because of the very low permeability. The water level fluctuations due to earth tides in the crystalline rock are about 10 cm, and those in the sediments are about 1.8 cm. The use of water level fluctuations due to earth tides to calculate porosity appears to present practical difficulties both in the crystalline metamorphic rock system and in the coastal plain sediments. In a 1-yr pumping test on a well in the crystalline metamorphic rock the flow was controlled to within 0.1 per cent of the total discharge, which was 0.94 l/s. The water level fluctuations due to earth tides in the pumping well were 10 cm, the same as when this well was not being pumped. (U.S.)

Observations and Modeling of Thermal Structure in the Lower Atmosphere and the Upward Propagation of Tides into the Thermosphere

Science.gov (United States)

Wilson, R. J.; Kahre, M.

2017-01-01

Thermal tides are the atmospheric response to diurnally varying thermal forcing resulting from radiative and convective heat transfer from the surface and from aerosol and gaseous heating within the atmosphere. Tides include sun-synchronous (migrating) waves driven in response to solar heating and additional non-migrating waves resulting from longitudinal variations in the distributions of topography, dust aerosol and water ice clouds. The systematic spatial mapping of temperature over 5 Mars years by the Mars Climate Sounder (MCS) has yielded a well-defined climatology of seasonally-varying temperature structures in the lower atmosphere, from 5 to 80 km. Tide theory and Mars global circulation model (MGCM) simulations are a fruitful framework for relating temperature observations to thermal forcing by aerosol fields [1]. The analysis of density and temperature fields derived from MAVEN IUVS and NGIMS observations have revealed the presence of predominantly zonal wave 2 and 3 features at altitudes of 100-170 km that are almost certainly non-migrating tides propagating upward from the lower atmosphere [2,3]. In this presentation we will use the MCS climatology and MGCM simulations to relate the density variations seen by MAVEN with the seasonally varying tide activity in the lower atmosphere. Large amplitude perturbations in density are most sensitive to the tide components with the longest vertical wavelengths in temperature, which are well resolved in MCS observations.

Mercury content in Hot Springs

Energy Technology Data Exchange (ETDEWEB)

Nakagawa, R

1974-01-01

A method of determination of mercury in hot spring waters by flameless atomic absorption spectrophotometry is described. Further, the mercury content and the chemical behavior of the elementary mercury in hot springs are described. Sulfide and iodide ions interfered with the determination of mercury by the reduction-vapor phase technique. These interferences could, however, be minimized by the addition of potassium permanganate. Waters collected from 55 hot springs were found to contain up to 26.0 ppb mercury. High concentrations of mercury have been found in waters from Shimoburo Springs, Aomori (10.0 ppb), Osorezan Springs, Aomori (1.3 approximately 18.8 ppb), Gosyogake Springs, Akita (26.0 ppb), Manza Springs, Gunma (0.30 approximately 19.5 ppb) and Kusatu Springs, Gunma (1.70 approximately 4.50 ppb). These hot springs were acid waters containing a relatively high quantity of chloride or sulfate.

Tide-surge historical assessment of extreme water levels for the St. Johns River: 1928-2017

Science.gov (United States)

Bacopoulos, Peter

2017-10-01

An historical storm population is developed for the St. Johns River, located in northeast Florida-US east coast, via extreme value assessment of an 89-year-long record of hourly water-level data. Storm surge extrema and the corresponding (independent) storm systems are extracted from the historical record as well as the linear and nonlinear trends of mean sea level. Peaks-over-threshold analysis reveals the top 16 most-impactful (storm surge) systems in the general return-period range of 1-100 years. Hurricane Matthew (2016) broke the record with a new absolute maximum water level of 1.56 m, although the peak surge occurred during slack tide level (0.00 m). Hurricanes and tropical systems contribute to return periods of 10-100 years with water levels in the approximate range of 1.3-1.55 m. Extratropical systems and nor'easters contribute to the historical storm population (in the general return-period range of 1-10 years) and are capable of producing extreme storm surges (in the approximate range of 1.15-1.3 m) on par with those generated by hurricanes and tropical systems. The highest astronomical tide is 1.02 m, which by evaluation of the historical record can contribute as much as 94% to the total storm-tide water level. Statically, a hypothetical scenario of Hurricane Matthew's peak surge coinciding with the highest astronomical tide would yield an overall storm-tide water level of 2.58 m, corresponding to an approximate 1000-year return period by historical comparison. Sea-level trends (linear and nonlinear) impact water-level return periods and constitute additional risk hazard for coastal engineering designs.

The DTU15 MSS (Mean Sea Surface) and DTU15LAT (Lowest Astronomical Tide) reference surface

DEFF Research Database (Denmark)

Andersen, Ole Baltazar; Stenseng, Lars; Piccioni, Gaia

in the Arctic Ocean for DTU10MSS and DTU13MSS.A new reference surface for off-shore vertical referencing is introduced. This is called the DTU15LAT.The surface is derived from the DTU15MSS and the DTU10 Global ocean tide to give a 19 year Lowest Astronomical Tide referenced to either the Mean sea surface...

Estimates of vertical land motion along the southwestern coasts of Turkey from coastal altimetry and tide gauge data

DEFF Research Database (Denmark)

Yildiz, Hasan; Andersen, Ole Baltazar; Simav, Mehmet

2013-01-01

The differences between coastal altimetry and sea level time series of tide gauges in between March 1993 and December 2009 are used to estimate the rates of vertical land motion at three tide gauge locations along the southwestern coasts of Turkey. The CTOH/LEGOS along-track coastal altimetry...... retrieves altimetric sea level anomalies closer to the coast than the standard along-track altimetry products. However, the use of altimetry very close to the coast is not found to improve the results. On the contrary, the gridded and interpolated AVISO merged product exhibits the best agreement with tide...... the Aegean Sea) shows no significant vertical land motion. The results are compared and assessed with three independent geophysical vertical land motion estimates like from GPS. The GIA effect in the region is negligible. The VLM estimates from altimetry and tide gauge data are in good agreement both...

Ocean tides and quasi-stationary departures from the marine geoid investigation

Science.gov (United States)

Siry, J. W.; Kahn, W. D.; Bryan, J. W.; Vonbun, F. O.

1973-01-01

The detection of tides and/or currents through the analysis of data generated in connection with the Ocean Geoid Determination Investigation is presented. A discussion of the detailed objectives and approach are included.

Characterization of middle Eocene tide-influenced delta: a study ...

Indian Academy of Sciences (India)

42

Running Title: Eocene tide-influenced delta in South Cambay Basin. Manuscript. Click here to view linked References. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10 .... systematic documentation of the facies types to establish the depositional environment of the .... Hazad Member consists of a number of sandstone units separated by intervening ...

Groundwater monitoring strategies at the Weldon Spring site, Weldon Spring, Missouri

International Nuclear Information System (INIS)

Meyer, K.A. Jr.

1988-01-01

This paper presents groundwater monitoring strategies at the Weldon Spring Site in east-central Missouri. The Weldon Spring Site is former ordnance works and uranium processing facility. In 1987, elevated levels of inorganic anions and nitroaromatics were detected in groundwater beneath the site. Studies are currently underway to characterize the hydrogeologic regime and to define groundwater contamination. The complex hydrogeology at the Weldon Spring Site requires innovative monitoring strategies. Combinations of fracture and conduit flow exist in the limestone bedrock. Perched zones are also present near surface impoundments. Losing streams and springs surround the site. Confronting this complex combination of hydrogeologic conditions is especially challenging

A social marketing approach to implementing evidence-based practice in VHA QUERI: the TIDES depression collaborative care model.

Science.gov (United States)

Luck, Jeff; Hagigi, Fred; Parker, Louise E; Yano, Elizabeth M; Rubenstein, Lisa V; Kirchner, JoAnn E

2009-09-28

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. 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. 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. 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.

The oceanic tides in the South Atlantic Ocean

Directory of Open Access Journals (Sweden)

M. L. Genco

Full Text Available The finite element ocean tide model of Le Provost and Vincent (1986 has been applied to the simulation of the M₂ and K₁ components over the South Atlantic Ocean. The discretisation of the domain, of the order of 200 km over the deep ocean, is refined down to 15 km along the coasts, such refinement enables wave propagation and damping over the continental shelves to be correctly solved. The marine boundary conditions, from Dakar to Natal, through the Drake passage and from South Africa to Antarctica, are deduced from in situ data and from Schwiderski's solution and then optimised following a procedure previously developed by the authors. The solutions presented are in very good agreement with in situ data: the root mean square deviations from a standard subset of 13 pelagic stations are 1.4 cm for M₂ and 0.45 cm for K₁, which is significantly better overall than solutions published to date in the literature. Zooms of the M₂ solution are presented for the Falkland Archipelago, the Weddell Sea and the Patagonian Shelf. The first zoom allows detailing of the tidal structure around the Falklands and its interpretation in terms of a stationary trapped Kelvin wave system. The second zoom, over the Weddell Sea, reveals for the first time what must be the tidal signal under the permanent ice shelf and gives a solution over that sea which is generally in agreement with observations. The third zoom is over the complex Patagonian Shelf. This zoom illustrates the ability of the model to simulate the tides, even over this area, with a surprising level of realism, following purely hydrodynamic modelling procedures, within a global ocean tide model. Maps of maximum associated tidal currents are also given, as a first illustration of a by-product of these simulations.

Relationship between variability of the semidiurnal tide in the Northern Hemisphere mesosphere and quasi-stationary planetary waves throughout the global middle atmosphere

Directory of Open Access Journals (Sweden)

X. Xu

2009-11-01

Full Text Available To investigate possible couplings between planetary waves and the semidiurnal tide (SDT, this work examines the statistical correlations between the SDT amplitudes observed in the Northern Hemisphere (NH mesosphere and stationary planetary wave (SPW with wavenumber S=1 (SPW1 amplitudes throughout the global stratosphere and mesosphere. The latter are derived from the Aura-MLS temperature measurements. During NH summer-fall (July–October, the mesospheric SDT amplitudes observed at Svalbard (78° N and Eureka (80° N usually do not show persistent correlations with the SPW1 amplitudes in the opposite hemisphere. Although the SDT amplitudes observed at lower latitudes (~50–70° N, especially at Saskatoon (52° N, are often shown to be highly and positively correlated with the SPW1 amplitudes in high southern latitudes, these correlations cannot be sufficiently explained as evidence for a direct physical link between the Southern Hemisphere (SH winter-early spring SPW and NH summer-early fall mesospheric SDT. This is because the migrating tide's contribution is usually dominant in the mid-high latitude (~50–70° N NH mesosphere during the local late summer-early fall (July–September. The numerical correlation is dominated by similar low-frequency variability or trends between the amplitudes of the NH SDT and SH SPW1 during the respective equinoctial transitions. In contradistinction, during NH winter (November–February, the mesospheric SDT amplitudes at northern mid-high latitudes (~50–80° N are observed to be significantly and positively correlated with the SPW1 amplitudes in the same hemisphere in most cases. Because both the SPW and migrating SDT are large in the NH during the local winter, a non-linear interaction between SPW and migrating SDT probably occurs, thus providing a global non-migrating SDT. This is consistent with observations of SDT in Antarctica that are large in summer than in winter. It is suggested that

Identification of thermohaline structure of a tropical estuary and its sensitivity to meteorological disturbance through temperature, salinity, and surface meteorological measurements

Digital Repository Service at National Institute of Oceanography (India)

Joseph, A.; Mehra, P.; Desai, R.G.P.; Sivadas, T.K.; Balachandran, K.K.; Vijaykumar, K.; Revichandran, C.; Agarvadekar, Y.; Francis, R.; Martin, G.D.

-neap variability in which thermal and haline variability bear an inverse relationship, with cooling and enhanced salinity during spring tide and vice versa during neap tide. The diurnal variability in temperature is controlled by day/night cyclicity rather than...

Determining slack tide with a GPS receiver on an anchored buoy

Science.gov (United States)

Valk, M.; Savenije, H. H. G.; Tiberius, C. C. J. M.; Luxemburg, W. M. J.

2014-07-01

In this paper we present a novel method to determine the time of occurrence of tidal slack with a GPS receiver mounted on an anchored buoy commonly used to delineate shipping lanes in estuaries and tidal channels. Slack tide occurs when the tide changes direction from ebb to flood flow or from flood to ebb. The determination of this point in time is not only useful for shipping and salvaging, it is also important information for calibrating tidal models, for determining the maximum salt intrusion and for the further refinement of the theory on tidal propagation. The accuracy of the timing is well within 10 min and the method - able to operate in real time - is relatively cheap and easy to implement on a permanent basis or in short field campaigns.

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

Science.gov (United States)

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

Visit to valuable water springs. 22. ; Kanazawa spring and springs at the mountain flank of Iwate volcano. Meisui wo tazunete. 22. ; Kanazawa shimizu to Iwate sanroku yusuigun

Energy Technology Data Exchange (ETDEWEB)

Itadera, K. (Kanagawa Hot Springs Research Institute, Kanagawa (Japan)); Shimano, Y. (Utsunomiya Bunsei Junior College, Tochigi (Japan))

1993-06-30

This paper describes the following matters on the springs at the mountain flank of Iwate volcano in Iwate Prefecture, with the Kanazawa spring as the main subject: The new and old Iwate volcanos have rock-bed flow deposits which resulted from mountain disintegration, distributed over their south, east and north flanks, and most of the spring water wells up in these areas; the south, east and north flanks have about 80 springs, about 30 springs, and about 10 springs, respectively; the number of springs and the water well-up scale show a trend of inverse proportion; the Kanazawa spring is a generic name of the several springs located on the north flank in the Kanazawa area; its main spring forms a spring pond with an area of about 100 m[sup 2] with a spring water temperature of about 11.5[degree]C, electric conductivity of 200 [mu] S/cm or higher, and a flow-out rate of 500 l/s or more; the Kanazawa spring is characterized by having as large total dissolved component amount as 170 mg/l or more and abundant amount of SO4[sup 2-] and Cl[sup -]; and the spring presents properties different from those in other springs. 10 refs., 5 figs., 1 tab.

Spring integration essentials

CERN Document Server

Pandey, Chandan

2015-01-01

This book is intended for developers who are either already involved with enterprise integration or planning to venture into the domain. Basic knowledge of Java and Spring is expected. For newer users, this book can be used to understand an integration scenario, what the challenges are, and how Spring Integration can be used to solve it. Prior experience of Spring Integration is not expected as this book will walk you through all the code examples.

Getting started with Spring Framework a hands-on guide to begin developing applications using Spring Framework

CERN Document Server

Sharma, J

2016-01-01

Getting started with Spring Framework is a hands-on guide to begin developing applications using Spring Framework. The examples (consisting of 74 sample projects) that accompany this book are based on Spring 4.3 and Java 8. You can download the examples described in this book from the following GitHub project:github.com/getting-started-with-spring/3rdEdition This book is meant for Java developers with little or no knowledge of Spring Framework. Getting started with Spring Framework, Third Edition has been updated to reflect changes in Spring 4.3 and also includes new chapters on Java-based configuration and Spring Data (covers Spring Data JPA and Spring Data MongoDB projects). The existing chapters have been revised to include information on Java-based configuration. The book also includes some new information on bean definition profiles, importing application context XML files, lazy autowiring, creating custom qualifier annotations, JSR 349 annotations, spring-messaging module, Java 8's Optional type, and s...

Effect of Long-Period Ocean Tides on the Earth's Polar Motion

Science.gov (United States)

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

1997-01-01

The second-degree zonal tide raising potential is symmetric about the polar axis and hence can excite the Earth's polar motion only through its action upon nonaxisymmetric features of the Earth such as the oceans.

How Tidal Forces Cause Ocean Tides in the Equilibrium Theory

Science.gov (United States)

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.

The source, discharge, and chemical characteristics of water from Agua Caliente Spring, Palm Springs, California

Science.gov (United States)

Contributors: Brandt, Justin; Catchings, Rufus D.; Christensen, Allen H.; Flint, Alan L.; Gandhok, Gini; Goldman, Mark R.; Halford, Keith J.; Langenheim, V.E.; Martin, Peter; Rymer, Michael J.; Schroeder, Roy A.; Smith, Gregory A.; Sneed, Michelle; Martin, Peter

2011-01-01

Agua Caliente Spring, in downtown Palm Springs, California, has been used for recreation and medicinal therapy for hundreds of years and currently (2008) is the source of hot water for the Spa Resort owned by the Agua Caliente Band of the Cahuilla Indians. The Agua Caliente Spring is located about 1,500 feet east of the eastern front of the San Jacinto Mountains on the southeast-sloping alluvial plain of the Coachella Valley. The objectives of this study were to (1) define the geologic structure associated with the Agua Caliente Spring; (2) define the source(s), and possibly the age(s), of water discharged by the spring; (3) ascertain the seasonal and longer-term variability of the natural discharge, water temperature, and chemical characteristics of the spring water; (4) evaluate whether water-level declines in the regional aquifer will influence the temperature of the spring discharge; and, (5) estimate the quantity of spring water that leaks out of the water-collector tank at the spring orifice.

Arctic tides from GPS on sea ice

DEFF Research Database (Denmark)

Kildegaard Rose, Stine; Skourup, Henriette; Forsberg, René

The presence of sea-ice in the Arctic Ocean plays a significant role in the Arctic climate. Sea ice dampens the ocean tide amplitude with the result that global tidal models which use only astronomical data perform less accurately in the polar regions. This study presents a kinematic processing o......-gauges and altimetry data. Furthermore, we prove that the geodetic reference ellipsoid WGS84, can be interpolated to the tidal defined zero level by applying geophysical corrections to the GPS data....

Spring plant phenology and false springs in the conterminous US during the 21st century

Science.gov (United States)

Allstadt, Andrew J.; Vavrus, Stephen J.; Heglund, Patricia J.; Pidgeon, Anna M.; Thogmartin, Wayne E.; Radeloff, Volker C.

2015-01-01

The onset of spring plant growth has shifted earlier in the year over the past several decades due to rising global temperatures. Earlier spring onset may cause phenological mismatches between the availability of plant resources and dependent animals, and potentially lead to more false springs, when subsequent freezing temperatures damage new plant growth. We used the extended spring indices to project changes in spring onset, defined by leaf out and by first bloom, and predicted false springs until 2100 in the conterminous United States (US) using statistically-downscaled climate projections from the Coupled Model Intercomparison Project 5 ensemble. Averaged over our study region, the median shift in spring onset was 23 days earlier in the Representative Concentration Pathway 8.5 scenario with particularly large shifts in the Western US and the Great Plains. Spatial variation in phenology was due to the influence of short-term temperature changes around the time of spring onset versus season long accumulation of warm temperatures. False spring risk increased in the Great Plains and portions of the Midwest, but remained constant or decreased elsewhere. We conclude that global climate change may have complex and spatially variable effects on spring onset and false springs, making local predictions of change difficult.

Zero drift and solid Earth tide extracted from relative gravimetric data with principal component analysis

OpenAIRE

Hongjuan Yu; Jinyun Guo; Jiulong Li; Dapeng Mu; Qiaoli Kong

2015-01-01

Zero drift and solid Earth tide corrections to static relative gravimetric data cannot be ignored. In this paper, a new principal component analysis (PCA) algorithm is presented to extract the zero drift and the solid Earth tide, as signals, from static relative gravimetric data assuming that the components contained in the relative gravimetric data are uncorrelated. Static relative gravity observations from Aug. 15 to Aug. 23, 2014 are used as statistical variables to separate the signal and...

Evidence for rapid, tide-related shifts in the microbiome of the coral Coelastrea aspera

Science.gov (United States)

Sweet, M. J.; Brown, B. E.; Dunne, R. P.; Singleton, I.; Bulling, M.

2017-09-01

Shifts in the microbiome of the intertidal coral Coelastrea aspera (formally known as Goniastrea aspera) from Phuket, Thailand, were noted over the course of a 4-d period of spring tides. During this time, corals were naturally exposed to high temperatures, intense solar radiation, sub-aerial exposure and tidally induced water fluxes. Analysis of the 16S microbiome highlighted that the corals harbored both `core or stable' communities and those which appeared to be more `transient or sporadic.' Only relatively few microbial associates were classified as core microbes; the majority were transient or sporadic. Such transient associates were likely to have been governed by tidally induced variations in mucus thickness and water fluxes. Here we report strong shifts in the bacterial community of C. aspera over a short temporal scale. However, we also show significant differences in the timing of shifts between the two age groups of corals studied. More rapid changes (within 2 d of sub-aerial exposure) occurred within the 4-yr-old colonies, but a slightly delayed response was observed in the 10-yr-old colonies, whereby the microbial associates only changed after 4 d. We hypothesize that these shifts are age related and could be influenced by the observed baseline differences in the microbiome of the 4- and 10-yr-old corals, bacteria-bacteria interactions, and/or host energetics.

Seasonal, lunar and tidal control of ichthyoplankton dynamics at the interface between a temperate estuary and adjacent coastal waters (western Portugal

Directory of Open Access Journals (Sweden)

Ana Lígia Primo

2011-11-01

Full Text Available Influence of season, lunar-tide cycle and tide on ichthyoplankton at the interface between Mondego estuary and the adjacent coast and on up-estuary transport was evaluated. Seasonal samples were collected at a fixed station at the mouth of the estuary during diel cycles, at neap and spring tides. Additionally, four sampling stations along the estuary were assessed. Pomatoschistus spp. was the main estuarine taxon, while Sardina pilchardus and Parablennius pilicornis were the most important marine species. Ichthyoplankton entrance and transport along the estuary presented a seasonal pattern with higher densities during summer. Lunar-tide cycle also represented an important influence, structuring communities that reach the estuary and their subsequent distribution. Solea senegalensis and Sardina pilchardus seemed to take advantage of spring tides to enter the estuary. S. pilchardus appear to be using tides to move upstream of the estuary. Ichthyoplankton entrance in the estuary seemed related to species spawning period, while its distribution within the estuary depends on in situ spawning and on the capacity of species to counteract currents and river flow. The present study provides a better understanding of ichthyoplankton dynamics at the interface of two coastal systems, reinforcing knowledge of the lunar-tide cycle influence on ichthyoplankton communities.

Love numbers for the long-period tides estimated by VLBI

Science.gov (United States)

Krásná, Hana; Böhm, Johannes; Haas, Rüdiger; Schuh, Harald

2013-04-01

Love and Shida numbers are proportionality factors characterizing the deformation of the anelastic Earth which arises as a response to external forces from the Moon and Sun. The increasing precision and quality of the Very Long Baseline Interferometry (VLBI) measurements allow determining those parameters. In particular, the long history of the VLBI data enables the estimation of Love and Shida numbers at the low frequencies of the tidal waves including the periods from 14 days to 18.6 years. In this study we analyse 27 years of VLBI measurements (1984.0 - 2011.0) following the recent IERS Conventions 2010. In several global solutions, we estimate the complex Love and Shida numbers of the solid Earth tides for the main long-period tidal waves. Furthermore, we determine the Love and Shida numbers of the rotational deformation due to polar motion, the so-called pole tide. We also focus on station displacement where still some deficiencies in the long-period signal modelling can be seen.

Global Structures and Multi-Temporal Variabilities of MLT Migrating Diurnal Tide

International Nuclear Information System (INIS)

Ze-Yu, Chen; Da-Ren, Lu

2008-01-01

Migrating diurnal tide in the MLT region is examined by the application of Hough mode decomposition with the tide delineated from the SABER/TIMED temperatures over 2002-2006. The decomposition results show that in the height range 60-100 km, the (1, 1) mode is the most predominant among eight leading Hough modes including four propagating and four trapped modes. It exhibits a sustained maximum at 97 km and significant semi-annual oscillation. Additionally, a novel feature of inter-annual variation with period of about two years is clearly seen in the (1, 1) mode, e.g., repeated maxima are seen at the March equinox of 2002, 2004 and 2006, respectively. This feature is further manifested by the tidal amplitudes in the height range 70-100 km in the height-time cross-section at the equator. It is likely of the QBO as the height range just coincides to where the zonal mean zonal winds derived by using the UARS data exhibiting the QBO. The other results show that the (1, 2) mode is important at < 80km exhibiting comparable amplitude to that of the (1, 1) mode, and in particular the nearly anti-correlation with the (1, 1) mode. The tide at about 85 km is suggested of rather complex as the four trapped modes exhibit maximum at these heights, which indicates the presence of local excitations or sources at below

Mapping tide-water glacier dynamics in east Greenland using landsat data

Science.gov (United States)

Dwyer, John L.

1995-01-01

Landsat multispectral scanner and thematic mapper images were co-registered For the Kangerdlugssuaq Fjord region in East Greenland and were used to map glacier drainage-basin areas, changes in the positions of tide-water glacier termini and to estimate surface velocities of the larger tide-water glaciers. Statistics were compiled to document distance and area changes to glacier termini. The methodologies developed in this study are broadly applicable to the investigation of tide-water glaciers in other areas. The number of images available for consecutive years and the accuracy with which images are co-registered are key factors that influence the degree to which regional glacier dynamics can be characterized using remotely sensed data.Three domains of glacier state were interpreted: net increase in terminus area in the southern part of the study area, net loss of terminus area for glaciers in upper Kangerdlugssuaq Fjord and a slight loss of glacier terminus area northward from Ryberg Fjord. Local increases in the concentrations of drifting icebergs in the fjords coincide with the observed extension of glacier termini positions Ice-surface velocity estimates were derived for several glaciers using automated image cross-correlation techniques The velocity determined for Kangerdlugssuaq Gletscher is approximately 5.0 km a−1 and that for Kong Christian IV Gletscher is 0.9 km a−1. The continuous presence of icebergs and brash ice in front of these glaciers indicates sustained rates of ice-front calving.

Arctic tides from GPS on sea ice

OpenAIRE

Kildegaard Rose, Stine; Skourup, Henriette; Forsberg, René

2012-01-01

The presence of sea-ice in the Arctic Ocean plays a significant role in the Arctic climate. Sea ice dampens the ocean tide amplitude with the result that global tidal models which use only astronomical data perform less accurately in the polar regions. This study presents a kinematic processing of Global Positioning System (GPS) buoys placed on sea-ice at five different sites north of Greenland for the study of sea level height and tidal analysis to improve tidal models in the Central Arctic....

Validation of the Lanzarote Tide Gauges system designed at the Royal Observatory of Belgium

Science.gov (United States)

van Ruymbeke, Michel; Dumont, Philippe; Seknik, Matej

2017-04-01

A series of tide gauges was set-up in a very favorable site located inside a lava tube plunging in the Atlantic ocean. The damping of waves motion is dramaticaly large, allowing to observe very tight modulations of the sea level. The gauges are based on the EDAS interface connected to a capacitor variying with the level of the sea . Filtering is gained by counting of frequency modulated signal during a one minute interval The scale factor is defined by comparizon of the output signals of sensors and reading the water level at different time. We evaluate the performance of our design by analysing the long series of records at disposal. The analysis is based on a stacking approach to extract components for periodicities existing in the spectrum of sea tides . Concordance of the results between the three gauges recording simultaneously the same signal confirms applicability of our design in such environment. After de-tiding application, the residuals signals are correlated to various physical parameters which could contribute to the understanding of the involved geophysical process.

Mean zonal and meridional accelerations and mean heating induced by solar tides for equinox and solstice conditions

International Nuclear Information System (INIS)

Groves, G.V.; Forbes, J.M.

1985-01-01

Evaluations are presented of the momentum and energy flux divergences of the diurnal and semidiurnal tidal fields calculated by Forbes from 0 to 400 km altitude. Results are presented in the form of meridional cross-sections from 0 to 78 0 N or S latitude with a 6 0 latitude interval. Comparisons are made with evaluations of the momentum flux divergences of the diurnal tide by Miyahara and good agreement is obtained in the lower thermosphere (below about 130 km) but a large disparity arises in the upper thermosphere. In the lower thermosphere momentum flux divergences of the semidiurnal tide are comparable with those of the diurnal tide and should be included in general circulation calculations of the 90-120 km region. (author)

Lunar Core and Tides

Science.gov (United States)

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.

Global ocean tide mapping using TOPEX/Poseidon altimetry

Science.gov (United States)

Sanchez, Braulio V.; Cartwright, D. E.; Estes, R. H.; Williamson, R. G.; Colombo, O. L.

1991-01-01

The investigation's main goals are to produce accurate tidal maps of the main diurnal, semidiurnal, and long-period tidal components in the world's deep oceans. This will be done by the application of statistical estimation techniques to long time series of altimeter data provided by the TOPEX/POSEIDON mission, with additional information provided by satellite tracking data. In the prelaunch phase, we will use in our simulations and preliminary work data supplied by previous oceanographic missions, such as Seasat and Geosat. These results will be of scientific interest in themselves. The investigation will also be concerned with the estimation of new values, and their uncertainties, for tidal currents and for the physical parameters appearing in the Laplace tidal equations, such as bottom friction coefficients and eddy viscosity coefficients. This will be done by incorporating the altimetry-derived charts of vertical tides as boundary conditions in the integration of those equations. The methodology of the tidal representation will include the use of appropriate series expansions such as ocean-basin normal modes and spherical harmonics. The results of the investigation will be space-determined tidal models of coverage and accuracy superior to that of the present numerical models of the ocean tides, with the concomitant benefits to oceanography and associated disciplinary fields.

Short-term tidal asymmetry inversion in a macrotidal estuary (Beira, Mozambique)

Science.gov (United States)

Nzualo, Teodósio N. M.; Gallo, Marcos N.; Vinzon, Susana B.

2018-05-01

The distortion of the tide in estuaries, bays and coastal areas is the result of the generation of overtides due to the non-linear effects associated with friction, advection, and the finite effects of the tidal amplitude in shallow waters. The Beira estuary is classified as macrotidal, with a large ratio of S2/M2. Typical tides ranges from 6 m and 0.8 m, during springs and neaps tides, respectively. As a consequence of this large fortnightly tidal amplitude difference and the estuarine morphology, asymmetry inversions occur. Two types of tidal asymmetries were investigated in this paper, one considering tidal duration asymmetry (time difference between rising and falling tide) and the other, related to tidal velocity asymmetry (unequal magnitudes of flood and ebb peaks currents). In the Beira estuary when we examine the tidal duration asymmetry, flood dominance is observed during spring tide periods (negative time difference between rising and falling tide), while ebb dominance appears during neap tides (positive time difference between rising and falling tide). A 2DH hydrodynamic model was implemented to analyze this asymmetry inversion. The model was calibrated with water-level data measured at the Port of Beira and current data measured along the estuary. The model was run for different scenarios considering tidal constituents at the ocean boundary, river discharge and the morphology of the estuary. River discharge did not show significant effects on the tidal duration asymmetry. Through comparison of the scenarios, it was shown that the incoming ocean tide at the boundary has an ebb-dominant asymmetry, changing to flood-dominant only during spring tides due to the effect of shoaling and friction within the estuary. During neap tides, the propagation occurs mainly in the channels, and ebb dominance remains. The interplay between the estuary morphodynamics was thus identified and the relation between tidal duration asymmetry and tidal velocity asymmetry was

[Ecology of Glossina palpalis VANDERPLANK, 1949 (Diptera: Glossinidae) in mangrove area of Guinea: influence of tides on tsetse densities].

Science.gov (United States)

Kagbadouno, S M; Salou, E; Rayaisse, J B; Courtin, F; Sanon, A; Solano, P; Camara, M

2016-05-01

The mangrove area on the Guinea littoral constitutes a favourable habitat for transmission of Trypanosoma brucei gambiens, the parasite causing sleeping sickness also called Human African Trypanosmosis (HAT), due the simultaneous presence of the vector (tsetse flies) and the human hosts. In order to assess the influence of the sea tides on the densities of Glossina palpalis gambiensis (Gpg), major vector of HAT in the mangrove, entomological surveys were performed using two transects, according to tides coefficient (great and small) and tide daily fluctuations (high and low). On each transect, 12 biconical traps were deployed through the mangrove to the continent. In total, up to 612 Gpg were caught, giving a density of 2.13 flies/trap/day (f/t/d). Highest captures were recorded during small tides and more tsetse were caught during the dry season than in the wet season. There were significant differences between captures when considering the different biotopes, and highest tsetse densities were recorded at the junction of the river and the channel of the mangrove (6.17±5.24); and in the channels of mangrove (3.50±3.76), during high tides of small coefficients. The results of this study may be used to improve vector control methods.

Variabilities of Low-Latitude Migrating and Nonmigrating Tides in GPS-TEC and TIMED-SABER Temperature During the Sudden Stratospheric Warming Event of 2013

Science.gov (United States)

Sridharan, S.

2017-10-01

The Global Positioning System deduced total electron content (TEC) data at 15°N (geomagnetic), which is the crest region of equatorial ionization anomaly, are used to study tidal variabilities during the 2013 sudden stratospheric warming (SSW) event. The results from space-time spectral analysis reveal that the amplitudes of migrating diurnal (DW1) and semidiurnal (SW2) tides are larger than those of nonmigrating tides. After the SSW onset, the amplitudes of DW1, SW2, SW1, and DS0 increase. Moreover, they show 16 day variations similar to the periodicity of the high-latitude stratospheric planetary wave (PW), suggesting that the nonmigrating tides (SW1 and DS0) are possibly generated due to nonlinear interaction of migrating tides with PW. Similar spectral analysis on temperature at 10°N obtained from the Sounding of Atmosphere by Broadband Emission Radiometry (SABER) shows that the SW2 enhances at stratospheric heights and the SW2 is more dominant at 80-90 km, but its amplitude decreases around 100 km. The amplitudes of nonmigrating tides become comparable to those of SW2 around 100 km, and their contribution becomes increasingly important at higher heights. This suggests that the nonlinear interaction between migrating tides and PW occurs at low-latitude upper mesospheric heights, as SW2 exhibits 16 day periodicity in SABER temperature at 100 km as observed in TEC. Besides, it is observed that the eastward propagating tides are less dominant than westward propagating tides in both TEC and SABER temperatures.

Longitudinal Variation of the Lunar Tide in the Equatorial Electrojet

Science.gov (United States)

Yamazaki, Yosuke; Stolle, Claudia; Matzka, Jürgen; Siddiqui, Tarique A.; Lühr, Hermann; Alken, Patrick

2017-12-01

The atmospheric lunar tide is one known source of ionospheric variability. The subject received renewed attention as recent studies found a link between stratospheric sudden warmings and amplified lunar tidal perturbations in the equatorial ionosphere. There is increasing evidence from ground observations that the lunar tidal influence on the ionosphere depends on longitude. We use magnetic field measurements from the CHAMP satellite during July 2000 to September 2010 and from the two Swarm satellites during November 2013 to February 2017 to determine, for the first time, the complete seasonal-longitudinal climatology of the semidiurnal lunar tidal variation in the equatorial electrojet intensity. Significant longitudinal variability is found in the amplitude of the lunar tidal variation, while the longitudinal variability in the phase is small. The amplitude peaks in the Peruvian sector (˜285°E) during the Northern Hemisphere winter and equinoxes, and in the Brazilian sector (˜325°E) during the Northern Hemisphere summer. There are also local amplitude maxima at ˜55°E and ˜120°E. The longitudinal variation is partly due to the modulation of ionospheric conductivities by the inhomogeneous geomagnetic field. Another possible cause of the longitudinal variability is neutral wind forcing by nonmigrating lunar tides. A tidal spectrum analysis of the semidiurnal lunar tidal variation in the equatorial electrojet reveals the dominance of the westward propagating mode with zonal wave number 2 (SW2), with secondary contributions by westward propagating modes with zonal wave numbers 3 (SW3) and 4 (SW4). Eastward propagating waves are largely absent from the tidal spectrum. Further study will be required for the relative importance of ionospheric conductivities and nonmigrating lunar tides.

Systematic hydrogeological study of a hypothermal spring (S. Cesarea Terme, Apulia), Italy

Science.gov (United States)

Calò, Giuseppe Cesario; Tinelli, Roccaldo

1995-02-01

A long series of thermo-saline logging has been carried out in wells drilled through the Mesozoic carbonate aquifer from which the sulfur hypothermal springs of S. Cesarea Terme issue. The logging conducted at various timings (i.e. periodically, rapidly sequenced, synchronized with tides and sea conditions), over about 10 years, provides valuable data on the thermal and hydrological regimen of the area. In particular for the inshore zone, both isotherm and thermal gradient trends could be determined, and a close identification of preferential levels through which groundwater discharge takes place was possible. In fact, flow velocity measurements, made by the point diluition method, showed a mostly impervious aquifer except for evident fissured levels through which low-velocity discharge (5-22 cm day -1) takes place. When the sea is low and calm, all levels are influenced by sulfur waters except for the uppermost unconfined zone. When the sea is rough, also owing to the low permeability of the aquifer, a barrier effect against groundwater flow is triggered. Since groundwater is prevented from discharging, it tends to reach deeper permeable levels, thus markedly altering the hydrological and thermal regimen of the deeper sulfur waters. The lithological character of aquifers and their low permeability are confirmed by 222Rn contents (normally 10-15 pCi l -1), groundwater reaching 200 pCi l -1), only at levels where water starts becoming hot. This phenomenon, as supported by all investigations including those on sulfides, occurs only at temperatures exceeding 23°C. Therefore, according to the above investigation, the S. Cesarea springs represent a unique hydraulic model, matching real hydrodynamic situations occurring when surrounding conditions change.

Ground water monitoring strategies at the Weldon Spring Site, Weldon Spring, Missouri

International Nuclear Information System (INIS)

Meyer, K.A. Jr.

1988-01-01

This paper presents ground water monitoring strategies at the Weldon Spring Site in east-central Missouri. The Weldon Spring Site is a former ordnance works and uranium processing facility. In 1987, elevated levels of inorganic anions and nitroaromatics were detected in ground water beneath the site. Studies are currently underway to characterize the hydrogeologic regime and to define ground water contamination. The complex hydrogeology at the Weldon Spring Site requires innovative monitoring strategies. Combinations of fracture and conduit flow exist in the limestone bedrock. Perched zones are also present near surface impoundments. Losing streams and springs surround the site. Solving this complex combination of hydrogeologic conditions is especially challenging

Optimum Design of a Coil Spring for Improving the Performance of a Spring -Operated Mechanism

International Nuclear Information System (INIS)

Lee, Dae Woo; Sohn, Jeong Hyun; Yoo, Wan Suk

2016-01-01

In this study, a release test bed is designed to evaluate the dynamic behaviors of a coil spring. From the release tests, the dynamic behaviors of a coil spring are analyzed. A lumped parameter spring model was established for numerical simulation of a spring. The design variables of a coil spring are optimized by using the design of experiments approach. Two-level factorial designs are used for the design optimization, and the primary effects of the design variables are analyzed. Based on the results of the interaction analysis and design sensitivity analysis, the level of the design variables is rearranged. Finally, the mixed-level factorial design is used for the optimum design process. According to the optimum design of the opening spring, the dynamic performance of the spring-operated mechanism increases by 2.90

Global distributions of diurnal and semidiurnal tides: observations from HRDI-UARS of the MLT region and comparisons with GSWM-02 (migrating, nonmigrating components

Directory of Open Access Journals (Sweden)

A. H. Manson

2004-04-01

Full Text Available HRDI (High Resolution Doppler Interferometer-UARS winds data have been analyzed in 4°-latitude by 10°-longitude cells at 96km to obtain the global distribution of the solar-tidal amplitudes and phases. The solstices June–July (1993, December–January (1993–1994, and one equinox (September–October, 1994 are analyzed. In an earlier paper (Manson et al., 2002b the emphasis was solely upon the longitudinal and latitudinal variations of the amplitudes and phases of the semidiurnal (12h and diurnal (24h tides. The longitudinal structures were shown to be quite distinctive, and in the case of the EW component of the diurnal tide there were typically four maxima/perturbations of amplitudes or phases around a latitude circle. In this case they tended to be associated with the locations of the major oceans. Here, a spatial complex spectral analysis has been applied to the data set, to obtain the zonal wave numbers for the tides as functions of latitude. For the diurnal tide the dominant s=1 migrating component and nonmigrating tides with wave numbers s=–3, –2, 0, 2 are identified; and for the semidiurnal tide, as well as the dominant s=2 migrating component, the spectra indicate the presence of nonmigrating tides with wave numbers s=–2, 0, 4. These wave numbers are also simply related to the global longitudinal structures in the tidal amplitudes and phases. Comparisons are made with the Global Scale Wave Model (GSWM-02, which now incorporates migrating and nonmigrating tides associated with tropospheric latent heat processes, and offers monthly outputs. For the diurnal tide the dominant nonmigrating tidal spectral feature (94km is for wave number s=–3; it is relatively stronger than in the HRDI winds, and produces quite consistent structures in the global tidal fields with four longitudinal maxima. Overall, the modelled 24-h tidal amplitudes are larger than observed during the equinox beyond 40° latitude. For the semidiurnal tide

Semidiurnal tide in the E region from incoherent scatter measurements at Arecibo

International Nuclear Information System (INIS)

Wand, R.H.

1976-01-01

A five-pulse technique was implemented for the 430 MHz incoherent scatter radar at Arecibo Observatory (18.3 0 N) to explore the detailed thermal structure of the E region from 105 to 130 km with an altitude resolution of 3 km. Five days of measurements in Sept-Oct 1970 showed long-period temperature fluctuations having a downward phase progression. The temperature oscillations are interpreted as manifestations of a semidiurnal tide which is quite stable over a 12-day period, together with a superimposed spectrum of shorter-period gravity waves which are randomly phased from day to day. The semidiurnal tide increased to a maximum amplitude of 17 percent of the mean temperature near 115 km and decreased above this altitude as dissipative effects became important. The vertical wavelength, deduced from the altitude variation of semidiurnal tidal phase, showed a smooth increase from about 20 km at an altitude of 109 km to about 50 km at an altitude of 127 km. No ready interpretation of the observed tidal characteristics was possible in terms of present theories for the semidiurnal tide. Altitude profiles of mean daytime temperature and ion-neutral collision frequency were also obtained from the measurements. The mean temperature gradient between 115 and 130 km was 15 K/km, which is somewhat larger than that given by current atmospheric models

Hot springs in Hokuriku District

Energy Technology Data Exchange (ETDEWEB)

Sato, K. (Hot Springs Research Center, Japan)

1971-01-01

In the Hokuriku district including Toyama, Ishikawa, and Fukui Prefectures, hot springs of more than 25/sup 0/C were investigated. In the Toyama Prefecture, there are 14 hot springs which are located in an area from the Kurobe River to the Tateyama volcano and in the mountainous area in the southwest. In Ishikawa Prefecture there are 16 hot springs scattered in Hakusan and its vicinity, the Kaga mountains, and in the Noto peninsula. In northern Fukui Prefecture there are seven hot springs. The hot springs in Shirakawa in Gifu Prefecture are characterized as acid springs producing exhalations and H/sub 2/S. These are attributed to the Quaternary volcanoes. The hot springs of Wakura, Katayamazu, and Awara in Ishikawa Prefecture are characterized by a high Cl content which is related to Tertiary andesite. The hot springs of Daishoji, Yamanaka, Yamashiro, Kuritsu, Tatsunokuchi, Yuwaku, and Yunotani are characterized by a low HCO/sub 3/ content. The Ca and SO/sub 4/ content decreases from east to west, and the Na and Cl content increases from west to east. These fluctuations are related to the Tertiary tuff and rhyolite. The hot springs of Kuronagi, Kinshu, and Babadani, located along the Kurobe River are characterized by low levels of dissolved components and high CO/sub 2/ and HCO/sub 3/ content. These trends are related to late Paleozoic granite. Hot springs resources are considered to be connected to geothermal resources. Ten tables, graphs, and maps are provided.

Phytoplankton absorption and pigment adaptation of a red tide in the ...

African Journals Online (AJOL)

Phytoplankton absorption and pigment characteristics of a red tide were investigated in coastal waters of the southern Benguela. Diagnostic indices indicated that dinoflagellates were the dominant phytoplankton group, with diatoms and small flagellates being of secondary importance. Very high biomass was observed ...

Five red tide species in genus Prorocentrum including the description of Prorocentrum donghaiense Lu SP. nov. from the East China Sea

Science.gov (United States)

Lu, Dou-Ding; Goebel, Jeanette

2001-12-01

A new planktonic dinoflagellate, Prorocentrum donghaiense Lu sp. nov., is described in the present paper. The water sample was collected from the Changjiang Estuary, the East China Sea. The species identification is based on shape, size, surface micro-morphology, ornamentation of thecal plates and the architecture of the periflagellar area and the intercalary bands as seen by light and scanning electron microscope. Prorocentrum donghaiense Lu sp. nov. is compared with other prorocentrum species with respect to morphological characteristics and bloom behavior. It is not known whether Prorocentrum donghaiense Lu sp. nov produces phycotoxins like some other Prorocentrum species. Four other red tide species in the family Prorocentraceae (Dinophyceae), namely P. balticum, P. minimum, P. micans, P. triestinum, were examined and identified by light and scanning electron microscope. They have been recorded as bloom-forming species. Some aggregates of Prorocentrum are observed at the end of blooms. An event of strong discoloration caused by P. donghaiense could be detected by satellite sensor in the East China Sea in the late spring of 1995.

Bottom Pressure Tides Along a Line in the Southeast Atlantic Ocean and Comparisons with Satellite Altimetry

Science.gov (United States)

Ray, Richard D.; Byrne, Deidre A.

2010-01-01

Seafloor pressure records, collected at 11 stations aligned along a single ground track of the Topex/Poseidon and Jason satellites, are analyzed for their tidal content. With very low background noise levels and approximately 27 months of high-quality records, tidal constituents can be estimated with unusually high precision. This includes many high-frequency lines up through the seventh-diurnal band. The station deployment provides a unique opportunity to compare with tides estimated from satellite altimetry, point by point along the satellite track, in a region of moderately high mesoscale variability. That variability can significantly corrupt altimeter-based tide estimates, even with 17 years of data. A method to improve the along-track altimeter estimates by correcting the data for nontidal variability is found to yield much better agreement with the bottom-pressure data. The technique should prove useful in certain demanding applications, such as altimetric studies of internal tides.

Integrating Non-Tidal Sea Level data from altimetry and tide gauges for coastal sea level prediction

DEFF Research Database (Denmark)

Cheng, Yongcun; Andersen, Ole Baltazar; Knudsen, Per

2012-01-01

The main objective of this paper is to integrate Non-Tidal Sea Level (NSL) from the joint TOPEX, Jason-1 and Jason-2 satellite altimetry with tide gauge data at the west and north coast of the United Kingdom for coastal sea level prediction. The temporal correlation coefficient between altimetric...... NSLs and tide gauge data reaches a maximum higher than 90% for each gauge. The results show that the multivariate regression approach can efficiently integrate the two types of data in the coastal waters of the area. The Multivariate Regression Model is established by integrating the along-track NSL...... from the joint TOPEX/Jason-1/Jason-2 altimeters with that from eleven tide gauges. The model results give a maximum hindcast skill of 0.95, which means maximum 95% of NSL variance can be explained by the model. The minimum Root Mean Square Error (RMSe) between altimetric observations and model...

Adaption of Ulva pertusa to multiple-contamination of heavy metals and nutrients: Biological mechanism of outbreak of Ulva sp. green tide.

Science.gov (United States)

Ge, Changzi; Yu, Xiru; Kan, Manman; Qu, Chunfeng

2017-12-15

The multiple-contamination of heavy metals and nutrients worsens increasingly and Ulva sp. green tide occurs almost simultaneously. To reveal the biological mechanism for outbreak of the green tide, Ulva pertusa was exposed to seven-day-multiple-contamination. The relation between pH variation (V pH ), Chl a content, ratio of (Chl a content)/(Chl b content) (R chla/chlb ), SOD activity of U. pertusa (A SOD ) and contamination concentration is [Formula: see text] (pcontamination concentrations of seawaters where Ulva sp. green tide occurred and the contamination concentrations set in the present work, U. pertusa can adapt to multiple-contaminations in these waters. Thus, the adaption to multiple-contamination may be one biological mechanism for the outbreak of Ulva sp. green tide. Copyright © 2017 Elsevier Ltd. All rights reserved.

Temperature sensitivity of drought-induced tree mortality portends increased regional die-off under global-change-type drought

Science.gov (United States)

Adams, Henry D.; Guardiola-Claramonte, Maite; Barron-Gafford, Greg A.; Villegas, Juan Camilo; Breshears, David D.; Zou, Chris B.; Troch, Peter A.; Huxman, Travis E.

2009-01-01

Large-scale biogeographical shifts in vegetation are predicted in response to the altered precipitation and temperature regimes associated with global climate change. Vegetation shifts have profound ecological impacts and are an important climate-ecosystem feedback through their alteration of carbon, water, and energy exchanges of the land surface. Of particular concern is the potential for warmer temperatures to compound the effects of increasingly severe droughts by triggering widespread vegetation shifts via woody plant mortality. The sensitivity of tree mortality to temperature is dependent on which of 2 non-mutually-exclusive mechanisms predominates—temperature-sensitive carbon starvation in response to a period of protracted water stress or temperature-insensitive sudden hydraulic failure under extreme water stress (cavitation). Here we show that experimentally induced warmer temperatures (≈4 °C) shortened the time to drought-induced mortality in Pinus edulis (piñon shortened pine) trees by nearly a third, with temperature-dependent differences in cumulative respiration costs implicating carbon starvation as the primary mechanism of mortality. Extrapolating this temperature effect to the historic frequency of water deficit in the southwestern United States predicts a 5-fold increase in the frequency of regional-scale tree die-off events for this species due to temperature alone. Projected increases in drought frequency due to changes in precipitation and increases in stress from biotic agents (e.g., bark beetles) would further exacerbate mortality. Our results demonstrate the mechanism by which warmer temperatures have exacerbated recent regional die-off events and background mortality rates. Because of pervasive projected increases in temperature, our results portend widespread increases in the extent and frequency of vegetation die-off. PMID:19365070

Spheres of discharge of springs

Science.gov (United States)

Springer, Abraham E.; Stevens, Lawrence E.

2009-02-01

Although springs have been recognized as important, rare, and globally threatened ecosystems, there is as yet no consistent and comprehensive classification system or common lexicon for springs. In this paper, 12 spheres of discharge of springs are defined, sketched, displayed with photographs, and described relative to their hydrogeology of occurrence, and the microhabitats and ecosystems they support. A few of the spheres of discharge have been previously recognized and used by hydrogeologists for over 80 years, but others have only recently been defined geomorphologically. A comparison of these spheres of discharge to classification systems for wetlands, groundwater dependent ecosystems, karst hydrogeology, running waters, and other systems is provided. With a common lexicon for springs, hydrogeologists can provide more consistent guidance for springs ecosystem conservation, management, and restoration. As additional comprehensive inventories of the physical, biological, and cultural characteristics are conducted and analyzed, it will eventually be possible to associate spheres of discharge with discrete vegetation and aquatic invertebrate assemblages, and better understand the habitat requirements of rare or unique springs species. Given the elevated productivity and biodiversity of springs, and their highly threatened status, identification of geomorphic similarities among spring types is essential for conservation of these important ecosystems.

Tides and Modern Geodesy

Science.gov (United States)

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.

Internal tide transformation across a continental slope off Cape Sines, Portugal

Science.gov (United States)

Small, Justin

2002-04-01

During the INTIFANTE 99 experiment in July 1999, observations were made of a prominent internal undular bore off Cape Sines, Portugal. The feature was always present and dominant in a collection of synthetic aperture radar (SAR) images of the area covering the period before, during and after the trial. During the trial, rapid dissemination of SAR data to the survey ship enabled assessment of the progression of the feature, and the consequent planning of a survey of the bore coincident with a new SAR image. Large amplitude internal waves of 50 m amplitude in 250 m water depth, and 40 m in 100 m depth, were observed. The images show that the position of the feature is linked to the phase of the tide, suggesting an internal tide origin. The individual packets of internal waves contain up to seven waves with wavelengths in the range of 500-1500 m, and successive packets are separated by internal tide distances of typically 16-20 km, suggesting phase speeds of 0.35-0.45 m s -1. The internal waves were coherent over crest lengths of between 15 and 70 km, the longer wavefronts being due to the merging of packets. This paper uses the SAR data to detail the transformation of the wave packet as it passes across the continental slope and approaches the coast. The generation sites for the feature are discussed and reasons for its unusually large amplitude are hypothesised. It is concluded that generation at critical slopes of the bathymetry and non-linear interactions are the likely explanations for the large amplitudes.

Turning the tide : tidal power in the UK

OpenAIRE

Sustainable Development Commission

2007-01-01

Contents: Turning the tide : tidal power in the UK -- Executive summary -- Tidal power in the UK : research report 1 : UK tidal resource assessment -- Tidal power in the UK : research report 2 : tidal technologies overview -- Tidal power in the UK : research report 3 : Severn barrage proposals -- Tidal power in the UK : research report 4 : Severn non-barrage options -- Tidal power in the UK : research report 5 : UK case studies. Summarised in the Welsh language version of the executive ...

Data Assimilation Modeling of the Barotropic Tides in the Korea/Tsushima Strait

National Research Council Canada - National Science Library

Book, Jeffrey W; Pistek, Pavel; Perkins, Henry; Thompson, Keith R; Teague, William J

2004-01-01

During 1999-2000, 13 bottom-mounted acoustic Doppler current profilers (ADCPs) and 12 wave/tide gauges were deployed along two lines across the Korea/Tsushima Strait, providing long-term measurements of currents and bottom pressure...

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

Directory of Open Access Journals (Sweden)

F. Deleflie

2003-01-01

Full Text Available 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.Key words. secular variation of J2, 18.6 year tide, mean orbital motione

Sea level differences between Topex/Poseidon altimetry and tide gauges: observed trends and vertical land motions

Science.gov (United States)

Lombard, A.; Dominh, K.; Cazenave, A.; Calmant, S.; Cretaux, J.

2002-12-01

Nine year-long (1993-2001) sea level difference time series have been constructed by comparing sea level recorded by tide gauges and Topex/Poseidon altimetry. Although the primary goal of such an analysis is to define a sub network of good quality tide gauges for calibration of satellite altimetry systems, in particular Jason-1. The difference time series displaying large positive or negative trends may give evidence of vertical land motion at the tide gauge site. We have analyzed 98 tide gauge records from the UHSLC. Among them, 42 sites mainly located on open ocean islands, give very good agreement (better than 2 mm/year) with Topex/Poseidon-derived sea level trends. 22 other sites, mainly located along the continental coastlines of the Pacific Ocean, present sea level trends differing by more than 5 mm/year with Topex/Poseidon. Many of these sites are located in active tectonic areas (either in the vicinity of subduction zones or in active volcanic areas), where vertical land motions (either transient or long-term) are expected. For example, this is the case at Kushimoto, Ofunato, Kushiro (Japan), Kodiak Island and Yakutat (Alaska), La Libertad, Callao, Caldera (western south America), and Rabaul (western Pacific). When possible, we compare these observed trends in sea level differences with GPS and/or DORIS observations.

Coil spring venting arrangement

International Nuclear Information System (INIS)

McCugh, R.M.

1975-01-01

A simple venting device for trapped gas pockets in hydraulic systems is inserted through a small access passages, operated remotely, and removed completely. The device comprises a small diameter, closely wound coil spring which is pushed through a guide temporarily inserted in the access passage. The guide has a central passageway which directs the coil spring radially upward into the pocket, so that, with the guide properly positioned for depth and properly oriented, the coil spring can be pushed up into the top of the pocket to vent it. By positioning a seal around the free end of the guide, the spring and guide are removed and the passage is sealed

Comparative spring mechanics in mantis shrimp.

Science.gov (United States)

Patek, S N; Rosario, M V; Taylor, J R A

2013-04-01

Elastic mechanisms are fundamental to fast and efficient movements. Mantis shrimp power their fast raptorial appendages using a conserved network of exoskeletal springs, linkages and latches. Their appendages are fantastically diverse, ranging from spears to hammers. We measured the spring mechanics of 12 mantis shrimp species from five different families exhibiting hammer-shaped, spear-shaped and undifferentiated appendages. Across species, spring force and work increase with size of the appendage and spring constant is not correlated with size. Species that hammer their prey exhibit significantly greater spring resilience compared with species that impale evasive prey ('spearers'); mixed statistical results show that species that hammer prey also produce greater work relative to size during spring loading compared with spearers. Disabling part of the spring mechanism, the 'saddle', significantly decreases spring force and work in three smasher species; cross-species analyses show a greater effect of cutting the saddle on the spring force and spring constant in species without hammers compared with species with hammers. Overall, the study shows a more potent spring mechanism in the faster and more powerful hammering species compared with spearing species while also highlighting the challenges of reconciling within-species and cross-species mechanical analyses when different processes may be acting at these two different levels of analysis. The observed mechanical variation in spring mechanics provides insights into the evolutionary history, morphological components and mechanical behavior, which were not discernible in prior single-species studies. The results also suggest that, even with a conserved spring mechanism, spring behavior, potency and component structures can be varied within a clade with implications for the behavioral functions of power-amplified devices.

Do the earth tides have an influence on short-term variations in radon concentration?

International Nuclear Information System (INIS)

Barnet, I.; Prochazka, J.; Skalsky, L.

1997-01-01

The short term (diurnal) indoor radon variations are often explained as a result of temperature and air pressure changes inside a dwelling (the so-called stack effect). The observations of indoor and soil gas radon variations related to the temperature and pressure variations in a test dwelling at Lipova, Northern Bohemia, have not proved the expected correlation between the radon and climatic parameters. The stack effect was clearly observed at the beginning of the four week cycles, when the indoor temperature growth was obvious. However, the indoor radon variations were of the same range or higher than at the beginning of the cycles during the whole week cycles, even when the temperature changes were of the 1-3 o C range. A theory is therefore presented, supported by the known fluctuations of the groundwater level caused by the Earth tides, and the widely observed free air radon variations. According to this theory, the Earth tides lead to the compression of the aquifers and synchronous rise of the groundwater level, which displaces the soil gas with radon into the atmosphere or dwellings. The Earth tide components were calculated for the studied locality and time intervals. The very good phase fit of the amplitudes of gravity variations, vertical and volume strain and vertical displacement with the indoor radon variations was found. This agreement leads to the conclusion that the Earth tides can be considered as one of the causes of the indoor radon variations. This conclusion is also supported by the observations of the radon variations in the underground unventilated spaces under constant temperature and air pressure conditions. (Author)

Tides and Their Dynamics over the Sunda Shelf of the Southern South China Sea.

Science.gov (United States)

Daryabor, Farshid; Ooi, See Hai; Abu Samah, Azizan; Akbari, Abolghasem

2016-01-01

A three-dimensional Regional Ocean Modelling System is used to study the tidal characteristics and their dynamics in the Sunda Shelf of the southern South China Sea. In this model, the outer domain is set with a 25 km resolution and the inner one, with a 9 km resolution. Calculations are performed on the inner domain. The model is forced at the sea surface by climatological monthly mean wind stress, freshwater (evaporation minus precipitation), and heat fluxes. Momentum and tracers (such as temperature and salinity) are prescribed in addition to the tidal heights and currents extracted from the Oregon State University TOPEX/Poseidon Global Inverse Solution (TPXO7.2) at the open boundaries. The results are validated against observed tidal amplitudes and phases at 19 locations. Results show that the mean average power energy spectrum (in unit m2/s/cph) for diurnal tides at the southern end of the East Coast of Peninsular Malaysia is approximately 43% greater than that in the East Malaysia region located in northern Borneo. In contrast, for the region of northern Borneo the semidiurnal power energy spectrum is approximately 25% greater than that in the East Coast of Peninsular Malaysia. This implies that diurnal tides are dominant along the East Coast of Peninsular Malaysia while both diurnal and semidiurnal tides dominate almost equally in coastal East Malaysia. Furthermore, the diurnal tidal energy flux is found to be 60% greater than that of the semidiurnal tides in the southern South China Sea. Based on these model analyses, the significant tidal mixing frontal areas are located primarily off Sarawak coast as indicated by high chlorophyll-a concentrations in the area.

Global distributions of diurnal and semidiurnal tides: observations from HRDI-UARS of the MLT region and comparisons with GSWM-02 (migrating, nonmigrating components

Directory of Open Access Journals (Sweden)

A. H. Manson

2004-04-01

Full Text Available HRDI (High Resolution Doppler Interferometer-UARS winds data have been analyzed in 4°-latitude by 10°-longitude cells at 96km to obtain the global distribution of the solar-tidal amplitudes and phases. The solstices June–July (1993, December–January (1993–1994, and one equinox (September–October, 1994 are analyzed.

In an earlier paper (Manson et al., 2002b the emphasis was solely upon the longitudinal and latitudinal variations of the amplitudes and phases of the semidiurnal (12h and diurnal (24h tides. The longitudinal structures were shown to be quite distinctive, and in the case of the EW component of the diurnal tide there were typically four maxima/perturbations of amplitudes or phases around a latitude circle. In this case they tended to be associated with the locations of the major oceans. Here, a spatial complex spectral analysis has been applied to the data set, to obtain the zonal wave numbers for the tides as functions of latitude. For the diurnal tide the dominant s=1 migrating component and nonmigrating tides with wave numbers s=–3, –2, 0, 2 are identified; and for the semidiurnal tide, as well as the dominant s=2 migrating component, the spectra indicate the presence of nonmigrating tides with wave numbers s=–2, 0, 4. These wave numbers are also simply related to the global longitudinal structures in the tidal amplitudes and phases.

Comparisons are made with the Global Scale Wave Model (GSWM-02, which now incorporates migrating and nonmigrating tides associated with tropospheric latent heat processes, and offers monthly outputs. For the diurnal tide the dominant nonmigrating tidal spectral feature (94km is for wave number s=–3; it is relatively stronger than in the HRDI winds, and produces quite consistent structures in the global tidal fields with four longitudinal maxima. Overall, the modelled 24-h tidal amplitudes are larger than observed

Data logger database - Physical and biological effects of fish-friendly tide gates

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The purpose of this one-time stand-alone study is to evaluate how effective "fish-friendly" or self-regulating tide gates (SRTs) are at increasing connectivity for...

Estimating decadal variability in sea level from tide gauge records: An application to the North Sea

OpenAIRE

Frederikse, Thomas; Riva, R.E.M.; Slobbe, Cornelis; Broerse, D.B.T.; Verlaan, Martin

2016-01-01

One of the primary observational data sets of sea level is represented by the tide gauge record. We propose a new method to estimate variability on decadal time scales from tide gauge data by using a state space formulation, which couples the direct observations to a predefined state space model by using a Kalman filter. The model consists of a time-varying trend and seasonal cycle, and variability induced by several physical processes, such as wind, atmospheric pressure changes and teleconne...

Design, history and results of the Thiazolidinedione Intervention with vitamin D Evaluation (TIDE) randomised controlled trial

DEFF Research Database (Denmark)

Punthakee, Z; Bosch, J; Dagenais, G

2012-01-01

AIMS/OBJECTIVE: Conflicting data regarding cardiovascular effects of thiazolidinediones (TZDs) and extra-skeletal effects of vitamin D supported the need for a definitive trial. The Thiazolidinedione Intervention with vitamin D Evaluation (TIDE) trial aimed to assess the effects of TZDs (rosiglit......AIMS/OBJECTIVE: Conflicting data regarding cardiovascular effects of thiazolidinediones (TZDs) and extra-skeletal effects of vitamin D supported the need for a definitive trial. The Thiazolidinedione Intervention with vitamin D Evaluation (TIDE) trial aimed to assess the effects of TZDs...

Interaction of tide and salinity barrier: Limitation of numerical model

Directory of Open Access Journals (Sweden)

Suphat Vongvisessomjai1

2008-07-01

Full Text Available Nowadays, the study of interaction of the tide and the salinity barrier in an estuarine area is usually accomplished vianumerical modeling, due to the speed and convenience of modern computers. However, numerical models provide littleinsight with respect to the fundamental physical mechanisms involved. In this study, it is found that all existing numericalmodels work satisfactorily when the barrier is located at some distance far from upstream and downstream boundary conditions.Results are considerably underestimate reality when the barrier is located near the downstream boundary, usually theriver mouth. Meanwhile, this analytical model provides satisfactory output for all scenarios. The main problem of thenumerical model is that the effects of barrier construction in creation of reflected tide are neglected when specifying thedownstream boundary conditions; the use of the boundary condition before construction of the barrier which are significantlydifferent from those after the barrier construction would result in an error outputs. Future numerical models shouldattempt to account for this deficiency; otherwise, using this analytical model is another choice.

Estimating hydraulic properties of the Floridan Aquifer System by analysis of earth-tide, ocean-tide, and barometric effects, Collier and Hendry Counties, Florida

Science.gov (United States)

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 time

Mockito for Spring

CERN Document Server

Acharya, Sujoy

2015-01-01

If you are an application developer with some experience in software testing and want to learn more about testing frameworks, then this technology and book is for you. Mockito for Spring will be perfect as your next step towards becoming a competent software tester with Spring and Mockito.

Astronomical High Tide Line, Geographic NAD83, NWRC (1995) [hightide_line_NWRC_1995

Data.gov (United States)

Louisiana Geographic Information Center — The astronomical high tide line was compiled from National Wetlands Inventory (NWI) 1:24,000-scale habitat maps that were photo-interpreted from color-infrared...

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

Science.gov (United States)

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.

Characterization of the hydrogeology of the sacred Gihon Spring, Jerusalem: a deteriorating urban karst spring

Science.gov (United States)

Amiel, Ronit Benami; Grodek, Tamir; Frumkin, Amos

2010-09-01

The Gihon Spring, Jerusalem, is important for the major monotheistic religions. Its hydrogeology and hydrochemistry is studied here in order to understand urbanization effects on karst groundwater resources, and promote better water management. High-resolution monitoring of the spring discharge, temperature and electrical conductivity, was performed, together with chemical and bacterial analysis. All these demonstrate a rapid response of the spring to rainfall events and human impact. A complex karst system is inferred, including conduit flow, fissure flow and diffuse flow. Electrical conductivity, Na+ and K+ values (2.0 mS/cm, 130 and 50 mg/l respectively) are very high compared to other nearby springs located at the town margins (0.6 mS/cm, 15 and <1 mg/l respectively), indicating considerable urban pollution in the Gihon area. The previously cited pulsating nature of the spring was not detected during the present high-resolution monitoring. This phenomenon may have ceased due to additional water sources from urban leakage and irrigation feeding the spring. The urbanization of the recharge catchment thus affects the spring water dramatically, both chemically and hydrologically. Appropriate measures should therefore be undertaken to protect the Gihon Spring and other karst aquifers threatened by rapid urbanization.

The enhanced nodal equilibrium ocean tide and polar motion

Science.gov (United States)

Sanchez, B. V.

1979-01-01

The tidal response of the ocean to long period forcing functions was investigated. The results indicate the possibility of excitation of a wobble component with the amplitude and frequency indicated by the data. An enhancement function for the equilibrium tide was postulated in the form of an expansion in zonal harmonics and the coefficients of such an expansion were estimated so as to obtain polar motion components of the required magnitude.

Influence of Green Tides in Coastal Nursery Grounds on the Habitat Selection and Individual Performance of Juvenile Fish.

Science.gov (United States)

Le Luherne, Emilie; Le Pape, Olivier; Murillo, Laurence; Randon, Marine; Lebot, Clément; Réveillac, Elodie

2017-01-01

Coastal ecosystems, which provide numerous essential ecological functions for fish, are threatened by the proliferation of green macroalgae that significantly modify habitat conditions in intertidal areas. Understanding the influence of green tides on the nursery function of these ecosystems is essential to determine their potential effects on fish recruitment success. In this study, the influence of green tides on juvenile fish was examined in an intertidal sandy beach area, the Bay of Saint-Brieuc (Northwestern France), during two annual cycles of green tides with varying levels of intensity. The responses of three nursery-dependent fish species, the pelagic Sprattus sprattus (L.), the demersal Dicentrarchus labrax (L.) and the benthic Pleuronectes platessa L., were analysed to determine the effects of green tides according to species-specific habitat niche and behaviour. The responses to this perturbation were investigated based on habitat selection and a comparison of individual performance between a control and an impacted site. Several indices on different integrative scales were examined to evaluate these responses (antioxidant defence capacity, muscle total lipid, morphometric condition and growth). Based on these analyses, green tides affect juvenile fish differently according to macroalgal density and species-specific tolerance, which is linked to their capacity to move and to their distribution in the water column. A decreasing gradient of sensitivity was observed from benthic to demersal and pelagic fish species. At low densities of green macroalgae, the three species stayed at the impacted site and the growth of plaice was reduced. At medium macroalgal densities, plaice disappeared from the impacted site and the growth of sea bass and the muscle total lipid content of sprat were reduced. Finally, when high macroalgal densities were reached, none of the studied species were captured at the impacted site. Hence, sites affected by green tides are less

Timing of warm water refuge use in Crystal River National Wildlife Refuge by manatees—Results and insights from Global Positioning System telemetry data

Science.gov (United States)

Slone, Daniel H.; Butler, Susan M.; Reid, James P.; Haase, Catherine G.

2017-11-21

Managers at the U.S. Fish and Wildlife Service Crystal River National Wildlife Refuge (CRNWR) desire to update their management plan regarding the operation of select springs including Three Sisters Springs. They wish to refine existing parameters used to predict the presence of federally threatened Trichechus manatus latirostris (Florida manatee) in the springs and thereby improve their manatee management options. The U.S. Geological Survey Sirenia Project has been tracking manatees in the CRNWR area since 2006 with floating Global Positioning System (GPS) satellite-monitored telemetry tags. Analyzing movements of these tagged manatees will provide valuable insight into their habitat use patterns.A total of 136 GPS telemetry bouts were available for this project, representing 730,009 locations generated from 40 manatees tagged in the Gulf of Mexico north of Tampa, Florida. Dates from October through March were included to correspond to the times that cold ambient temperatures were expected, thus requiring a need for manatee thermoregulation and a physiologic need for warm water. Water level (tide) and water temperatures were obtained for the study from Salt River, Crystal River mouth, Bagley Cove, Kings Bay mouth, and Magnolia Spring. Polygons were drawn to subdivide the manatee locations into areas around the most-used springs (Three Sisters/Idiots Delight, House/Hunter/Jurassic, Magnolia and King), Kings Bay, Crystal/Salt Rivers and the Gulf of Mexico.Manatees were found in the Crystal or Salt Rivers or in the Gulf of Mexico when ambient temperatures were warmer (>20 °C), while they were found in or near the springs (especially Three Sisters Springs) at colder ambient water temperatures. There was a trend of manatees entering springs early in the morning and leaving in the afternoon. There was a strong association of manatee movements in and out of the Three Sisters/Idiots Delight polygon with tide cycles: manatees were more likely to enter the Three Sisters

The bottom water exchange between the Singapore Strait and the West Johor Strait

Science.gov (United States)

Sun, Yunfang; Eltahir, Elfatih; Malanotte-Rizzoli, Paola

2017-08-01

As a part of the border between Singapore and Malaysia, the West Johor Strait (WJS) suffered newly from harmful algal blooms. There is no previous study showing the source of the nutrients in the WJS. This paper is investigating the possible water exchange between the water in the WJS and the bottom water in Singapore Strait. This paper adopts a two-level nesting atmosphere-ocean coupled models to downscale the global atmosphere-ocean model into the Singapore coastal water, keeping the large-scale and long-term ocean and climate circulation signals and the advantages of the high-resolution. Based on the high-resolution ocean circulation fields, a Lagrangian particle tracking model is used to trace the Singapore Strait's bottom water movement and the water mixing in the WJS. The results showed that the numerical models well resolved the Singapore coastal water regional circulation. There is a small but significant bottom water (1.25%) transport from the Singapore Strait to the WJS, which occurs from the southwest coastline of Singapore. The bottom water in the Singapore Strait prefers to enter the WJS during the spring tide and the flood period, and stay in Johor Strait for 6.4 days. The spring tide is the first-order factor for the water vertical mixing in the WJS, the wind is also very important for the vertical mixing especially in neap tide condition. An overall very important factor is the light perturbation. With the strongest vertical mixing of nutrients and bottom sediments due to the spring tide, the latter ones may inhibit the light penetration during the spring tide and reduce the algal bloom. The light penetration otherwise is greater during the neap tide, when the winds are the most important factor and hence favor the algal bloom. With the strongest wind in February and the longest permanence time in June and the sufficient nutrient supply in February and June, the most serious algal blooms may happen in February and June in the WJS.

Thermal tides and studies to tune the mechanistic tidal model using UARS observations

Directory of Open Access Journals (Sweden)

V. A. Yudin

1997-09-01

Full Text Available Monthly simulations of the thermal diurnal and semidiurnal tides are compared to High-Resolution Doppler Imager (HRDI and Wind Imaging Interferometer (WINDII wind and temperature measurements on the Upper-Atmosphere Research Satellite (UARS. There is encouraging agreement between the observations and the linear global mechanistic tidal model results both for the diurnal and semidiurnal components in the equatorial and mid-latitude regions. This gives us the confidence to outline the first steps of an assimilative analysis/interpretation for tides, dissipation, and mean flow using a combination of model results and the global measurements from HRDI and WINDII. The sensitivity of the proposed technique to the initial guess employed to obtain a best fit to the data by tuning model parameters is discussed for the January and March 1993 cases, when the WINDII day and night measurements of the meridional winds between 90 and 110 km are used along with the daytime HRDI measurements. Several examples for the derivation of the tidal variables and decomposition of the measured winds into tidal and mean flow components using this approach are compared with previous tidal estimates and modeling results for the migrating tides. The seasonal cycle of the derived diurnal tidal amplitudes are discussed and compared with radar observation between 80 and 100 km and 40°S and 40°N.

Thermal tides and studies to tune the mechanistic tidal model using UARS observations

Directory of Open Access Journals (Sweden)

V. A. Yudin

Full Text Available Monthly simulations of the thermal diurnal and semidiurnal tides are compared to High-Resolution Doppler Imager (HRDI and Wind Imaging Interferometer (WINDII wind and temperature measurements on the Upper-Atmosphere Research Satellite (UARS. There is encouraging agreement between the observations and the linear global mechanistic tidal model results both for the diurnal and semidiurnal components in the equatorial and mid-latitude regions. This gives us the confidence to outline the first steps of an assimilative analysis/interpretation for tides, dissipation, and mean flow using a combination of model results and the global measurements from HRDI and WINDII. The sensitivity of the proposed technique to the initial guess employed to obtain a best fit to the data by tuning model parameters is discussed for the January and March 1993 cases, when the WINDII day and night measurements of the meridional winds between 90 and 110 km are used along with the daytime HRDI measurements. Several examples for the derivation of the tidal variables and decomposition of the measured winds into tidal and mean flow components using this approach are compared with previous tidal estimates and modeling results for the migrating tides. The seasonal cycle of the derived diurnal tidal amplitudes are discussed and compared with radar observation between 80 and 100 km and 40^°S and 40^°N.

Short-term variations in mesozooplankton, ichthyoplankton, and nutrients associated with semi-diurnal tides in a patagonian Gulf

Science.gov (United States)

Castro, L. R.; Cáceres, M. A.; Silva, N.; Muñoz, M. I.; León, R.; Landaeta, M. F.; Soto-Mendoza, S.

2011-03-01

The relationships between the distribution of different zooplankton and ichthyoplankton stages and physical and chemical variables were studied using samples and data (CTD profiles, ADCP and current meter measurements, nutrients, mesozooplankton, ichthyoplankton) obtained from different strata during two 24-h cycles at two oceanographic stations in a Chilean Patagonian gulf during the CIMAR 10-Fiordos cruise (November, 2004). A station located at the Chacao Channel was dominated by tidal mixing and small increments in surface stratification during high tides, leading to decreased nutrient availability. This agreed with short periods of increased phytoplankton abundance during slack waters at the end of flood currents. Increases in larval density for all zooplankton and ichthyoplankton taxa corresponded to the flooding phases of the tidal cycle. When the larval density data were fit to a sinusoidal model, the regression coefficients were high, suggesting that tides are important features that modulate short-term variations in plankton abundance. All larvae did not vary synchronously with the tidal phase; rather, time lags were observed among species. The abundances of older individuals of the copepodite Rhincalanus nasutus and all zoea stages of the squat lobster Munida gregaria increased during night flood tides, whereas younger stages increased during daytime flood tides. At a station located at the Queullin Pass, which was dominated by vertical stratification patterns, the variations in peak larval density were better fitted to the semi-diurnal sea level fluctuations. Other evidence indicated internal tides below the pycnocline, which could promote larval transport in deeper layers. In the overall picture that emerges from this study, planktonic organisms from different habitats and phylogenetic origins seem to respond to the local tidal regimes. In some cases, this response might be beneficial, transporting these individuals inshore to areas that are rich in

Three-Dimensional Dynamics of Baroclinic Tides Over a Seamount

Science.gov (United States)

Vlasenko, Vasiliy; Stashchuk, Nataliya; Nimmo-Smith, W. Alex M.

2018-02-01

The Massachusetts Institute of Technology general circulation model is used for the analysis of baroclinic tides over Anton Dohrn Seamount (ADS), in the North Atlantic. The model output is validated against in situ data collected during the 136th cruise of the RRS "James Cook" in May-June 2016. The observational data set includes velocity time series recorded at two moorings as well as temperature, salinity, and velocity profiles collected at 22 hydrological stations. Synthesis of observational and model data enabled the reconstruction of the details of baroclinic tidal dynamics over ADS. It was found that the baroclinic tidal waves are generated in the form of tidal beams radiating from the ADS periphery to its center, focusing tidal energy in a surface layer over the seamount's summit. This energy focusing enhances subsurface water mixing and the local generation of internal waves. The tidal beams interacting with the seasonal pycnocline generate short-scale internal waves radiating from the ADS center. An important ecological outcome from this study concerns the pattern of residual currents generated by tides. The rectified flows over ADS have the form of a pair of dipoles, cyclonic and anticyclonic eddies located at the seamount's periphery. These eddies are potentially an important factor in local larvae dispersion and their escape from ADS.

Executive summary: Weldon Spring Site Environmental Report for calendar year 1992. Weldon Spring Site Remedial Action Project, Weldon Spring, Missouri

Energy Technology Data Exchange (ETDEWEB)

1993-06-01

This report has been prepared to provide information about the public safety and environmental protection programs conducted by the Weldon Spring Site Remedial Action Project. The Weldon Spring site is located in southern St. Charles County, Missouri, approximately 48 km (30 mi) west of St. Louis. The site consists of two main areas, the Weldon Spring Chemical Plant and raffinate pits and the Weldon Spring Quarry. The objectives of the Site Environmental Report are to present a summary of data from the environmental monitoring program, to characterize trends and environmental conditions at the site, and to confirm compliance with environmental and health protection standards and requirements. The report also presents the status of remedial activities and the results of monitoring these activities to assess their impacts on the public and environment. The scope of the environmental monitoring program at the Weldon Spring site has changed since it was initiated. Previously, the program focused on investigations of the extent and level of contaminants in the groundwater, surface waters, buildings, and air at the site. In 1992, the level of remedial activities required monitoring for potential impacts of those activities, particularly on surface water runoff and airborne effluents. This report includes monitoring data from routine radiological and nonradiological sampling activities. These data include estimates of dose to the public from the Weldon Spring site; estimates of effluent releases; and trends in groundwater contaminant levels. Also, applicable compliance requirements, quality assurance programs, and special studies conducted in 1992 to support environmental protection programs are reviewed.

Recent trend of administration on hot springs

Energy Technology Data Exchange (ETDEWEB)

Okubo, Shigeru [Environment Agency, Tokyo (Japan)

1989-01-01

The Environmental Agency exercises jurisdiction over Hot Spring Act, and plans to protect the source of the hot spring and to utilize it appropriately. From the aspect of utilization, hot springs are widely used as a means to remedy chronic diseases and tourist spots besides places for recuperation and repose. Statistics on Japanese hot springs showed that the number of hot spring spots and utilized-fountainhead increased in 1987, compared with the number in 1986. Considering the utilized-headspring, the number of naturally well-out springs has stabilized for 10 years while power-operated springs have increased. This is because the demand of hot springs has grown as the number of users has increased. Another reason is to keep the amount of hot water by setting up the power facility as the welled-out amount has decreased. Major point of recent administration on the hot spring is to permit excavation and utilization of hot springs. Designation of National hot spring health resorts started in 1954 in order to ensure the effective and original use of hot springs and to promote the public use of them, for the purpose of arranging the sound circumstances of hot springs. By 1988, 76 places were designated. 4 figs., 3 tabs.

Occurrence of larval fishes in a rocky shore-associated nursery area ...

African Journals Online (AJOL)

There was no significant difference in CPUE between the moon phases sampled on the spring tides in this study. Shark Bay was dominated by postflexionstage larvae, consisting in particular of species common to tide pools during the juvenile stage. Certain species were sampled for only short periods during the year.

A normal mode treatment of semi-diurnal body tides on an aspherical, rotating and anelastic Earth

Science.gov (United States)

Lau, Harriet C. P.; Yang, Hsin-Ying; Tromp, Jeroen; Mitrovica, Jerry X.; Latychev, Konstantin; Al-Attar, David

2015-08-01

Normal mode treatments of the Earth's body tide response were developed in the 1980s to account for the effects of Earth rotation, ellipticity, anelasticity and resonant excitation within the diurnal band. Recent space-geodetic measurements of the Earth's crustal displacement in response to luni-solar tidal forcings have revealed geographical variations that are indicative of aspherical deep mantle structure, thus providing a novel data set for constraining deep mantle elastic and density structure. In light of this, we make use of advances in seismic free oscillation literature to develop a new, generalized normal mode theory for the tidal response within the semi-diurnal and long-period tidal band. Our theory involves a perturbation method that permits an efficient calculation of the impact of aspherical structure on the tidal response. In addition, we introduce a normal mode treatment of anelasticity that is distinct from both earlier work in body tides and the approach adopted in free oscillation seismology. We present several simple numerical applications of the new theory. First, we compute the tidal response of a spherically symmetric, non-rotating, elastic and isotropic Earth model and demonstrate that our predictions match those based on standard Love number theory. Second, we compute perturbations to this response associated with mantle anelasticity and demonstrate that the usual set of seismic modes adopted for this purpose must be augmented by a family of relaxation modes to accurately capture the full effect of anelasticity on the body tide response. Finally, we explore aspherical effects including rotation and we benchmark results from several illustrative case studies of aspherical Earth structure against independent finite-volume numerical calculations of the semi-diurnal body tide response. These tests confirm the accuracy of the normal mode methodology to at least the level of numerical error in the finite-volume predictions. They also demonstrate

Influence of topography on tide propagation and amplification in semi-enclosed basins

NARCIS (Netherlands)

Roos, Pieter C.; Schuttelaars, Henk M.

2011-01-01

An idealized model for tide propagation and amplification in semi-enclosed rectangular basins is presented, accounting for depth differences by a combination of longitudinal and lateral topographic steps. The basin geometry is formed by several adjacent compartments of identical width, each having

Influence of topography on tide propagation and amplification in semi-enclosed basins

NARCIS (Netherlands)

Roos, P.C.; Schuttelaars, H.M.

2010-01-01

An idealized model for tide propagation and amplification in semi-enclosed rectangular basins is presented, accounting for depth differences by a combination of longitudinal and lateral topographic steps. The basin geometry is formed by several adjacent compartments of identical width, each having

Spring security 3.x cookbook

CERN Document Server

Mankale, Anjana

2013-01-01

This book follows a cookbook style exploring various security solutions provided by Spring Security for various vulnerabilities and threat scenarios that web applications may be exposed to at the authentication and session level layers.This book is for all Spring-based application developers as well as Java web developers who wish to implement robust security mechanisms into web application development using Spring Security.Readers are assumed to have a working knowledge of Java web application development, a basic understanding of the Spring framework, and some knowledge of the fundamentals o

Geochemical and hydrologic data for wells and springs in thermal-spring areas of the Appalachians

Energy Technology Data Exchange (ETDEWEB)

Hobba, W.A. Jr.; Chemerys, J.C.; Fisher, D.W.; Pearson, F.J. Jr.

1976-07-01

Current interest in geothermal potential of thermal-spring areas in the Appalachians makes all data on thermal springs and wells in these areas valuable. Presented here without interpretive comment are maps showing selected springs and wells and tables of physical and chemical data pertaining to these wells and springs. The chemical tables show compositions of gases (oxygen, nitrogen, argon, methane, carbon dioxide, and helium), isotope contents (tritium, carbon (13), and oxygen (18)), trace and minor element chemical data, and the usual complete chemical data.

Four-peak longitudinal distribution of the equatorial plasma bubbles observed in the topside ionosphere: Possible troposphere tide influence

Science.gov (United States)

Sidorova, L. N.; Filippov, S. V.

2018-03-01

In this paper we consider an idea of the troposphere tide influence on the character of the longitudinal variations in the distribution of the equatorial plasma bubbles (EPBs) observed in the topside ionosphere. For this purpose, the obtained EPB longitudinal patterns were compared with the thermosphere and ionosphere characteristics having the prominent "wave-like" longitudinal structures with wave number 4, which are uniquely associated with the influence of the troposphere DE3 tides. The characteristics of the equatorial mass density anomaly (EMA), equatorial ionization anomaly (EIA), zonal wind and pre-reversal E × B drift enhancement (PRE) were used for comparison. The equinox seasons during high solar activity were under consideration. It was obtained that the longitudinal patterns of the EMA and zonal wind show the surprising similarity with the EPB distributions (R ≅ 0.8, R ≅ 0.72). On the other hand, the resemblance with the ionosphere characteristics (EIA, PRE) is rather faint (R ≅ 0.37, R ≅ 0.12). It was shown that the thermosphere zonal winds are the most possible transfer mediator of the troposphere DE3 tide influence. The most successful moment for the transfer of the troposphere DE3 tide energy takes place in the beginning of the EPB production, namely, during the seed perturbation development.

Uncertainties in shoreline position analysis: the role of run-up and tide in a gentle slope beach

Directory of Open Access Journals (Sweden)

G. Manno

2017-09-01

Full Text Available In recent decades in the Mediterranean Sea, high anthropic pressure from increasing economic and touristic development has affected several coastal areas. Today the erosion phenomena threaten human activities and existing structures, and interdisciplinary studies are needed to better understand actual coastal dynamics. Beach evolution analysis can be conducted using GIS methodologies, such as the well-known Digital Shoreline Analysis System (DSAS, in which error assessment based on shoreline positioning plays a significant role. In this study, a new approach is proposed to estimate the positioning errors due to tide and wave run-up influence. To improve the assessment of the wave run-up uncertainty, a spectral numerical model was used to propagate waves from deep to intermediate water and a Boussinesq-type model for intermediate water up to the swash zone. Tide effects on the uncertainty of shoreline position were evaluated using data collected by a nearby tide gauge. The proposed methodology was applied to an unprotected, dissipative Sicilian beach far from harbors and subjected to intense human activities over the last 20 years. The results show wave run-up and tide errors ranging from 0.12 to 4.5 m and from 1.20 to 1.39 m, respectively.

Sea level during storm surges as seen in tide-gauge records along the east coast of India

Digital Repository Service at National Institute of Oceanography (India)

Sundar, D.; Shankar, D.; Shetye, S.R.

and crossed the north Orissa coast later that day; it weakened and moved westward subsequent to landfall. Sea-level variations due to surges triggered by storm winds form a noise superimposed on the highly periodic tides, which have astronomical origins.... In the next section we describe the analysis used to 1326 CURRENT SCIENCE, VOL. 77, NO. 10, 25 NOVEMBER 1999 COMPUTATIONAL ENGINEERING SCIENCE Figure 1b. Astronomical tide and dehyphenminustided sea level during Event 1. The dark blue vertical lines...

Rising Tide II: Do Black Students Benefit as Grad Rates Increase?

Science.gov (United States)

Nichols, Andrew Howard; Eberle-Sudré, Kimberlee; Welch, Meredith

2016-01-01

"Rising Tide II: Do Black Students Benefit as Grad Rates Increase?" looks at a decade of graduation rates for African American students at four-year, public institutions that improved student success during the past decade. It shows that while a majority (almost 70 percent) of institutions we examined improved graduation rates for black…

Artificial radioactivity in tide washed pastures in south west Scotland

International Nuclear Information System (INIS)

McKay, W.A.; Bonnett, P.J.P.; Barr, H.M.; Howorth, J.M.

1991-01-01

A study has been carried out to determine the impact of Sellafield discharges on the levels of radioactivity in tide washed pastures in south west Scotland. The likely areas of tidal inundations along the Nith, Urr, Dee, Fleet and Cree (including nearby Bladnoch) rivers were assessed using maps and aerials photographs. These were then visited and gamma radiation measurements taken at regular intervals to enable the external dose from anthropogenic nuclides to be estimated. A further survey followed where soil cores were taken from the areas on each river where the external dose appeared highest and analysed for a range of artificial radionuclides. The levels of 137 Cs, 134 Cs, 238 Pu, 239+240 Pu and 241 Am found, although small, were clearly in excess of the background from other sources. A habit survey was carried out to provide site specific information of tide washed pasture usage, which, with the spatial radionuclide data was used to estimate doses to appropriate critical groups. The maximum annual dose calculated to arise was 60 μSv which is less than 6% of the ICRP principal dose limit of 1 mSv. (author)

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

Science.gov (United States)

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.

Linear and non-linear sea-level variations in the Adriatic Sea from tide gauge records (1872-2012

Directory of Open Access Journals (Sweden)

Gaia Galassi

2015-03-01

Full Text Available We have analyzed tide gauge data from the Adriatic Sea in order to assess the secular sea-level trend, its acceleration and the existence of possible cyclic variation. Analyzing the sea-level stack of all Adriatic tide gauges, we have obtained a trend of (1.25±0.04 mm yr-1, in agreement with that observed for the last century in the Mediterranean Sea, and an acceleration that is negligibile compared to the average global values. By means of the Ensemble Empirical Mode Decomposition technique, we have evidenced an energetic oscillation with a period of ∼20 years that we relate with the recurrence of opposite phases in the Atlantic Multi–decadal Oscillation and North Atlantic Oscillation indices. We suggest that anomalously high sea-level values observed at all the Adriatic tide gauges during 2010 and 2011 can be explained by the rising phase of this 20 years cycle.

Global distributions of diurnal and semi-diurnal tides: observations from HRDI-UARS of the MLT region

Directory of Open Access Journals (Sweden)

A. H. Manson

2002-11-01

Full Text Available HRDI (High Resolution Doppler Interferometer-UARS winds data have been analyzed in 4° latitude by 10° longitude cells at 96 km to obtain global contour maps of solar-tidal amplitudes and phases, and also mean winds. The solstices June–July (1993, December–January (1993–1994, and one equinox September–October (1994 are shown.  The 24-h diurnal tide that maximizes near the 20–25° latitude has significant seasonal changes with equinoctial maxima, and very clear longitudinal variability. Maxima are very clear over the oceans. In contrast, the 12-h semi-diurnal tides that maximize near the 40–55° latitude have very strong seasonal changes with winter maxima, and more modest longitudinal changes. The similarities with MLT (mesosphere-lower thermosphere radar observations (90 km and the GSWM (Global Scale Wave Model are very satisfactory. The mean winds are consistent with expectations and show clear poleward flow from summer to winter hemispheres in the solstices.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides Radio science (remote sensing

Source properties of the 1998 July 17 Papua New Guinea tsunami based on tide gauge records

Science.gov (United States)

Heidarzadeh, Mohammad; Satake, Kenji

2015-07-01

We analysed four newly retrieved tide gauge records of the 1998 July 17 Papua New Guinea (PNG) tsunami to study statistical and spectral properties of this tsunami. The four tide gauge records were from Lombrum (PNG), Rabaul (PNG), Malakal Island (Palau) and Yap Island (State of Yap) stations located 600-1450 km from the source. The tsunami registered a maximum trough-to-crest wave height of 3-9 cm at these gauges. Spectral analysis showed two dominant peaks at period bands of 2-4 and 6-20 min with a clear separation at the period of ˜5 min. We interpreted these peak periods as belonging to the landslide and earthquake sources of the PNG tsunami, respectively. Analysis of the tsunami waveforms revealed 12-17 min delay in landslide generation compared to the origin time of the main shock. Numerical simulations including this delay fairly reproduced the observed tide gauge records. This is the first direct evidence of the delayed landslide source of the 1998 PNG tsunami which was previously indirectly estimated from acoustic T-phase records.

Applying spatial analysis techniques to assess the suitability of multipurpose uses of spring water in the Jiaosi Hot Spring Region, Taiwan

Science.gov (United States)

Jang, Cheng-Shin

2016-04-01

The Jiaosi Hot Spring Region is located in northeastern Taiwan and is rich in geothermal springs. The geothermal development of the Jiaosi Hot Spring Region dates back to the 18th century and currently, the spring water is processed for various uses, including irrigation, aquaculture, swimming, bathing, foot spas, and recreational tourism. Because of the proximity of the Jiaosi Hot Spring Region to the metropolitan area of Taipei City, the hot spring resources in this region attract millions of tourists annually. Recently, the Taiwan government is paying more attention to surveying the spring water temperatures in the Jiaosi Hot Spring Region because of the severe spring water overexploitation, causing a significant decline in spring water temperatures. Furthermore, the temperature of spring water is a reliable indicator for exploring the occurrence and evolution of springs and strongly affects hydrochemical reactions, components, and magnitudes. The multipurpose uses of spring water can be dictated by the temperature of the water. Therefore, accurately estimating the temperature distribution of the spring water is critical in the Jiaosi Hot Spring Region to facilitate the sustainable development and management of the multipurpose uses of the hot spring resources. To evaluate the suitability of spring water for these various uses, this study spatially characterized the spring water temperatures of the Jiaosi Hot Spring Region by using ordinary kriging (OK), sequential Gaussian simulation (SGS), and geographical information system (GIS). First, variogram analyses were used to determine the spatial variability of spring water temperatures. Next, OK and SGS were adopted to model the spatial distributions and uncertainty of the spring water temperatures. Finally, the land use (i.e., agriculture, dwelling, public land, and recreation) was determined and combined with the estimated distributions of the spring water temperatures using GIS. A suitable development strategy

Spring Recipes A Problem-solution Approach

CERN Document Server

Long, Josh; Mak, Gary

2010-01-01

With over 3 Million users/developers, Spring Framework is the leading "out of the box" Java framework. Spring addresses and offers simple solutions for most aspects of your Java/Java EE application development, and guides you to use industry best practices to design and implement your applications. The release of Spring Framework 3 has ushered in many improvements and new features. Spring Recipes: A Problem-Solution Approach, Second Edition continues upon the bestselling success of the previous edition but focuses on the latest Spring 3 features for building enterprise Java applications.

Fish and logger summaries - Physical and biological effects of fish-friendly tide gates

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The purpose of this one-time stand-alone study is to evaluate how effective "fish-friendly" or self-regulating tide gates (SRTs) are at increasing connectivity for...

Numerical modelling of tides and tidal currents in the Gulf of Kutch

Digital Repository Service at National Institute of Oceanography (India)

Unnikrishnan, A.S.

An application of a two-dimensional tidal model to study the tidal regime in the Gulf of Kutch is made. This is with a view to synthesise various information on tides and currents that are available in the Gulf. A comparison of surface elevations...

THE RED-TIDE DINOFLAGELLATE, ALEXANDRIUM MONILATUM, SUPPRESSES GROWTH OF MIXED NATURAL PHYTOPLANKTON

Science.gov (United States)

Alexandrium monilatum is a large, chain-forming, autotrophic dinoflagellate associated with red-tides and fish kills along the US Gulf of Mexico coast. When cultured inocula of A. monilatum were added to nutrient-amended seawater samples, growth rates and biomass yields of the na...

Quarry geotechnical report for the Weldon Spring Site Remedial Action Project, Weldon Spring, Missouri

International Nuclear Information System (INIS)

1990-11-01

This report has been prepared for the United States Department of Energy's (DOE) Weldon Spring Site Remedial Action Project (WSSRAP) by the Project Management Contractor (PMC), which is MK-Ferguson Company (MK-Ferguson) with Jacobs Engineering Group (JEG) as its designated subcontractor. The Weldon Spring site (WSS) comprises the Weldon Spring quarry area and the Weldon Spring chemical plant and raffinate pit areas. This report presents the results of geotechnical investigations conducted during 1989--1990 at the proposed Weldon Spring quarry staging and water treatment facilities in the quarry area. The facilities are intended for treatment of water removed from the quarry area. An access road and a decontamination pad will be necessary for handling and transportation of bulk waste. Results of previous geotechnical investigations performed by other geoscience and environmental engineering firms in the quarry area, were reviewed, summarized and incorporated into this report. Well logging, stratigraphy data, piezometer data, elevations, and soil characteristics are also included

A Stylistic Analysis of the Dialogues in Pirates of the Caribbean: On Strange Tides%A Stylistic Analysis of the Dialogues in Pirates of the Caribbean:On Strange Tides

Institute of Scientific and Technical Information of China (English)

李冯茹

2017-01-01

Dialogues in classical films are always the concentrated scripts studied by scholars. This thesis performs a stylistic analysis of dialogues from Pirates of the Caribbean: On Strange Tides at the levels of phonology, lexicon, syntax, semantics and pragmatics to make a good attempt in the application of stylistic analysis.

Atmospheric tides and periodic variations in the precipitation field

International Nuclear Information System (INIS)

Cevolani, G.; Bacci, P.; Bonelli, P.; Isnardi, C.

1986-01-01

The analysis of daily precipitations data at many weather stations in Alpes and Po Valley gives evidence of a ''tidal'' influence from luni-solar gravitational fields. The tidal influence does not appear to be strictly constant with time, as the possible results of a modulation effect of luni-solar cycles having similar periods. Time variations of daily precipitation data as a function of some particular cycles show that gravitational tides effect heavy rainfalls more than mean precipitation values

Spring/dimple instrument tube restraint

International Nuclear Information System (INIS)

DeMario, E.E.; Lawson, C.N.

1993-01-01

A nuclear fuel assembly for a pressurized water nuclear reactor has a spring and dimple structure formed in a non-radioactive insert tube placed in the top of a sensor receiving instrumentation tube thimble disposed in the fuel assembly and attached at a top nozzle, a bottom nozzle, and intermediate grids. The instrumentation tube thimble is open at the top, where the sensor or its connection extends through the cooling water for coupling to a sensor signal processor. The spring and dimple insert tube is mounted within the instrumentation tube thimble and extends downwardly adjacent the top. The springs and dimples restrain the sensor and its connections against lateral displacement causing impact with the instrumentation tube thimble due to the strong axial flow of cooling water. The instrumentation tube has a stainless steel outer sleeve and a zirconium alloy inner sleeve below the insert tube adjacent the top. The insert tube is relatively non-radioactivated inconel alloy. The opposed springs and dimples are formed on diametrically opposite inner walls of the insert tube, the springs being formed as spaced axial cuts in the insert tube, with a web of the insert tube between the cuts bowed radially inwardly for forming the spring, and the dimples being formed as radially inward protrusions opposed to the springs. 7 figures

Evidences of Seasonal Variation in Altimetry Derived Ocean Tides in the Subarctic Ocean

Directory of Open Access Journals (Sweden)

Hok Sum Fok

2013-01-01

Full Text Available While the barotropic ocean tides in the deep ocean are well modeled to ~2 cm RMS, accurate tidal prediction in the ice-covered polar oceans and near coastal regions remain elusive. A notable reason is that the most accurate satellite altimeters (TOPEX/Jason-1/-2, whose orbits are optimized to minimize the tidal aliasing effect, have spatial coverage limited to largely outside of the polar ocean. Here, we update the assessment of tidal models using 7 contemporary global and regional models, and show that the altimetry sea surface height (SSH anomaly residual after tidal correction is 9 - 12 cm RMS in the Subarctic Ocean. We then address the hypothesis whether plausible evidence of variable tidal signals exist in the seasonally ice-covered Subarctic Ocean, where the sea ice cover is undergoing rapid thinning. We first found a difference in variance reduction for multi-mission altimeter SSH anomaly residuals during the summer and winter seasons, with the residual during winter season 15 - 30% larger than that during the summer season. Experimental seasonal ocean tide solutions derived from satellite altimetry reveals that the recovered winter and summer tidal constituents generally differ by a few cm in amplitude and tens of degrees in phase. Relatively larger seasonal tidal patterns, in particular for M2, S2 and K1 tides, have been identified in the Chukchi Sea study region near eastern Siberia, coincident with the seasonal presence and movement of sea ice.

Numerical modelling of the M2 tide on the northern Patagonian Shelf

Science.gov (United States)

Glorioso, P. D.; Simpson, J. H.

1994-02-01

The previously reported occurrence of tidal fronts on the Patagonian Shelf ( CARRETOet al., 1986 , Journal of Plankton Research, 8, 15-28; GLORIOSO, 1987 , Continental Shelf Research, 7, 27-34), motivated the application of a numerical model to solve the shallow-water equations with external forcing by the principal-lunar semidiurnal tide (M2) prescribed along the open boundary. The mean width of the Patagonian Shelf is comparable with a quarter wavelength of the semidiurnal tide, giving the conditions for standing wave resonance at that frequency ( WEBB, 1975 , Deep-Sea Research, 23, 1-15). The region is well recognized by its large tidal elevations and by the speed of the tidal wave changing phase very rapidly. Some of the results obtained from the modelling exercise include the mapping of the M2 tidal constants, the Simpson-Hunter stratification parameter, the mean sea surface elevation, and the distribution of tidal energy dissipation by bottom friction. These results agree qualitatively with the ship data available and with satellite infrared imagery.

Influence of internal tides on Antarctic Bottom Water propagation through abyssal channels

Science.gov (United States)

Morozov, Eugene

2010-05-01

Antarctic Bottom Water (AABW) propagates in the Atlantic Ocean from the Weddell Sea to the north through narrow passages in submarine ridges. Submarine ridges are regions of strong internal tide generation in the ocean that causes mixing and eventually AABW loses its distinguishing properties such as low temperature and salinity. The Vema Fracture Zone (11 N) and Romanche Fracture Zone (equator) in the Mid-Atlantic Ridge (MAR) are pathways for AABW to the Northeast Atlantic. The deep basin of the Northeast Atlantic (Canary Basin and Gambia Abyssal Plain) are filled with the bottom water propagating through the Vema FZ rather than through the equatorial fracture zones because strong internal tides and mixing over the slopes of the MAR near the equator cause warming of AABW and decrease of its density. Further propagation of AABW through the Kane Gap is low. Recent field measurements in the fracture zones confirm this concept based on modeling results. Results of recent cruises are presented.

[History of hot spring bath treatment in China].

Science.gov (United States)

Hao, Wanpeng; Wang, Xiaojun; Xiang, Yinghong; Gu Li, A Man; Li, Ming; Zhang, Xin

2011-07-01

As early as the 7th century B.C. (Western Zhou Dynasty), there is a recording as 'spring which contains sulfur could treat disease' on the Wentang Stele written by WANG Bao. Wenquan Fu written by ZHANG Heng in the Easten Han Dynasty also mentioned hot spring bath treatment. The distribution of hot springs in China has been summarized by LI Daoyuan in the Northern Wei Dynasty in his Shuijingzhu which recorded hot springs in 41 places and interpreted the definition of hot spring. Bencao Shiyi (by CHEN Cangqi, Tang Dynasty) discussed the formation of and indications for hot springs. HU Zai in the Song Dynasty pointed out distinguishing hot springs according to water quality in his book Yuyin Conghua. TANG Shenwei in the Song Dynasty noted in Jingshi Zhenglei Beiji Bencao that hot spring bath treatment should be combined with diet. Shiwu Bencao (Ming Dynasty) classified hot springs into sulfur springs, arsenicum springs, cinnabar springs, aluminite springs, etc. and pointed out their individual indications. Geologists did not start the work on distribution and water quality analysis of hot springs until the first half of the 20th century. There are 972 hot springs in Wenquan Jiyao (written by geologist ZHANG Hongzhao and published in 1956). In July 1982, the First National Geothermal Conference was held and it reported that there were more than 2600 hot springs in China. Since the second half of the 20th century, hot spring sanatoriums and rehabilitation centers have been established, which promoted the development of hot spring bath treatment.

Using barometric time series of the IMS infrasound network for a global analysis of thermally induced atmospheric tides

Science.gov (United States)

Hupe, Patrick; Ceranna, Lars; Pilger, Christoph

2018-04-01

The International Monitoring System (IMS) has been established to monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty and comprises four technologies, one of which is infrasound. When fully established, the IMS infrasound network consists of 60 sites uniformly distributed around the globe. Besides its primary purpose of determining explosions in the atmosphere, the recorded data reveal information on other anthropogenic and natural infrasound sources. Furthermore, the almost continuous multi-year recordings of differential and absolute air pressure allow for analysing the atmospheric conditions. In this paper, spectral analysis tools are applied to derive atmospheric dynamics from barometric time series. Based on the solar atmospheric tides, a methodology for performing geographic and temporal variability analyses is presented, which is supposed to serve for upcoming studies related to atmospheric dynamics. The surplus value of using the IMS infrasound network data for such purposes is demonstrated by comparing the findings on the thermal tides with previous studies and the Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2), which represents the solar tides well in its surface pressure fields. Absolute air pressure recordings reveal geographical characteristics of atmospheric tides related to the solar day and even to the lunar day. We therefore claim the chosen methodology of using the IMS infrasound network to be applicable for global and temporal studies on specific atmospheric dynamics. Given the accuracy and high temporal resolution of the barometric data from the IMS infrasound network, interactions with gravity waves and planetary waves can be examined in future for refining the knowledge of atmospheric dynamics, e.g. the origin of tidal harmonics up to 9 cycles per day as found in the barometric data sets. Data assimilation in empirical models of solar tides would be a valuable application of the IMS infrasound

Dynamic and Regression Modeling of Ocean Variability in the Tide-Gauge Record at Seasonal and Longer Periods

Science.gov (United States)

Hill, Emma M.; Ponte, Rui M.; Davis, James L.

2007-01-01

Comparison of monthly mean tide-gauge time series to corresponding model time series based on a static inverted barometer (IB) for pressure-driven fluctuations and a ocean general circulation model (OM) reveals that the combined model successfully reproduces seasonal and interannual changes in relative sea level at many stations. Removal of the OM and IB from the tide-gauge record produces residual time series with a mean global variance reduction of 53%. The OM is mis-scaled for certain regions, and 68% of the residual time series contain a significant seasonal variability after removal of the OM and IB from the tide-gauge data. Including OM admittance parameters and seasonal coefficients in a regression model for each station, with IB also removed, produces residual time series with mean global variance reduction of 71%. Examination of the regional improvement in variance caused by scaling the OM, including seasonal terms, or both, indicates weakness in the model at predicting sea-level variation for constricted ocean regions. The model is particularly effective at reproducing sea-level variation for stations in North America, Europe, and Japan. The RMS residual for many stations in these areas is 25-35 mm. The production of "cleaner" tide-gauge time series, with oceanographic variability removed, is important for future analysis of nonsecular and regionally differing sea-level variations. Understanding the ocean model's strengths and weaknesses will allow for future improvements of the model.

Severe fish mortality associated with 'red tide' observed in the sea off Cochin

Digital Repository Service at National Institute of Oceanography (India)

Naqvi, S.W.A.; George, M; Narvekar, P.V.; Jayakumar, D.A.; Shailaja, M; Sardessai, S.; Sarma, V.V.S.S.; Shenoy, D.M; Naik, H.; Maheswaran, P.A.; KrishnaKumari, L.; Rajesh, G.; Sudhir, A.K.; Binu, M

Severe fish mortality associated with the "red tide" phenomenon caused by Noctiluca blooms was observed in the sea off Cochin, Kerala, India at depths less than 40 m. The dead fish, almost entirely comprised of the threadfin bream (Nemipterus...

Internal tides and vertical mixing over the Kerguelen Plateau

Science.gov (United States)

Park, Young-Hyang; Fuda, Jean-Luc; Durand, Isabelle; Naveira Garabato, Alberto C.

2008-03-01

Within the context of the natural iron-fertilization study KEOPS, time series measurements of CTD and LADCP profiles at a site (50.6°S, 72°E; 528 m) coinciding with an annual phytoplankton bloom over the Kerguelen Plateau were made during the January-February 2005 KEOPS cruise. An important activity of highly nonlinear semidiurnal internal tides having peak-to-peak isopycnal displacements of up to 80 m is identified. These internal tides appear to be a principal agent for promoting elevated vertical mixing indispensable for upward transfer of iron within the seasonal thermocline. We estimate local vertical eddy diffusivities of the order of 4×10 -4 m 2 s -1 using a Thorpe scale analysis. Although this estimate is higher by an order of magnitude than the canonical value O (0.1×10 -4 m 2 s -1) in the open ocean away from boundaries, it is consistent with nonlinear internal wave/wave interaction theories, as verified by independent diffusivity estimates using the vertical wavenumber spectral methods for shear and strain. It is also suggested that the general ocean circulation may play an important role in preconditioning the bloom in that the relatively sluggish circulation over the shallow plateau (compared to the much more dynamic neighbouring deep ocean) may foster the bloom's observed annual recurrence over the plateau.

Landslide movement in southwest Colorado triggered by atmospheric tides

Science.gov (United States)

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.

A modeling study of the thermosphere-ionosphere interactions during the boreal winter and spring 2015-2016: Tidal and planetary-scale waves effect on the ionospheric structure.

Science.gov (United States)

Sassi, F.; McDonald, S. E.; McCormack, J. P.; Tate, J.; Liu, H.; Kuhl, D.

2017-12-01

The 2015-2016 boreal winter and spring is a dynamically very interesting time in the lower atmosphere: a minor high latitude stratospheric warming occurred in February 2016; an interrupted descent of the QBO was found in the tropical stratosphere; and a large warm ENSO took place in the tropical Pacific Ocean. The stratospheric warming, the QBO and ENSO are known to affect in different ways the meteorology of the upper atmosphere in different ways: low latitude solar tides and high latitude planetary-scale waves have potentially important implications on the structure of the ionosphere. In this study, we use global atmospheric analyses from a high-altitude version of the High-Altitude Navy Global Environmental Model (HA-NAVGEM) to constrain the meteorology of numerical simulations of the Specified Dynamics Whole Atmosphere Community Climate Model, extended version (SD-WACCM-X). We describe the large-scale behavior of tropical tides and mid-latitude planetary waves that emerge in the lower thermosphere. The effect on the ionosphere is captured by numerical simulations of the Navy Highly Integrated Thermosphere Ionosphere Demonstration System (Navy-HITIDES) that uses the meteorology generated by SD-WACCM-X to drive ionospheric simulations during this time period. We will analyze the impact of various dynamical fields on the zonal behavior of the ionosphere by selectively filtering the relevant dynamical modes.

Nuclear reactor spring strip grid spacer

International Nuclear Information System (INIS)

Patterson, J.F.; Flora, B.S.

1978-01-01

A bimetallic grid spacer is described comprising a grid structure of zircaloy formed by intersecting striplike members which define fuel element openings for receiving fuel elements and spring strips made of Inconel positioned within the grid structure for cooperating with the fuel elements to maintain them in their desired position. A plurality of these spring strips extend longitudinally between sides of the grid structure, being locked in position by the grid retaining strips. The fuel rods, which are disposed in the fuel openings formed in the grid structure, are positioned by means of the springs associated with the spring strips and a plurality of dimples which extend from the zircaloy grid structure into the openings. In one embodiment the strips are disposed in a plurality of arrays with those spring strip arrays situated in opposing diagonal quadrants of the grid structure extending in the same direction and adjacent spring strip arrays in each half of the spacer extending in relatively perpendicular directions. Other variations of the spring strip arrangements for a particular fuel design are disclosed herein

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

Science.gov (United States)

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.

Sepsis in Africa: practical steps to stem the tide | Otu | Pan African ...

African Journals Online (AJOL)

Sepsis in Africa: practical steps to stem the tide. Akaninyene Otu, James Elston, Emmanuel Nsutebu. Abstract. Pan African Medical Journal 2015; 21. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · AJOL African Journals Online. HOW TO USE AJOL.

Global Modeling of Internal Tides Within an Eddying Ocean General Circulation Model

Science.gov (United States)

2012-05-31

paper aooo not violate: any Oisclosur~,;·of trade• secrets or suggestions of outside individuals on::oncams whiCh have· beE !n communicated 1.o...fully three- dimensional global ocean circulation model, we will provide an internal tide capability everywhere, and allow nested models to include

On the choice of orbits for an altimetric satellite to study ocean circulation and tides

Science.gov (United States)

Parke, Michael E.; Stewart, Robert H.; Farless, David L.; Cartwright, David E.

1987-01-01

The choice of an orbit for satellite altimetric studies of the ocean's circulation and tides requires an understanding of the orbital characteristics that influence the accuracy of the satellite's measurements of sea level and the temporal and spatial distribution of the measurements. The orbital characteristics that influence accurate calculations of the satellite's position as a function of time are examined, and the pattern of ground tracks laid down on the ocean's surface as a function of the satellite's altitude and inclination is studied. The results are used to examine the aliases in the measurements of surface geostrophic currents and tides. Finally, these considerations are used to specify possible orbits that may be useful for the upcoming Topex/Poseidon mission.

Inhibitory activity of an extract from a marine bacterium Halomonas sp. HSB07 against the red-tide microalga Gymnodinium sp. (Pyrrophyta)

Science.gov (United States)

Liu, Juan; Li, Fuchao; Liu, Ling; Jiang, Peng; Liu, Zhaopu

2013-11-01

In recent years, red tides occurred frequently in coastal areas worldwide. Various methods based on the use of clay, copper sulfate, and bacteria have been successful in controlling red tides to some extent. As a new defensive agent, marine microorganisms are important sources of compounds with potent inhibitory bioactivities against red-tide microalgae, such as Gymnodinium sp. (Pyrrophyta). In this study, we isolated a marine bacterium, HSB07, from seawater collected from Hongsha Bay, Sanya, South China Sea. Based on its 16S rRNA gene sequence and biochemical characteristics, the isolated strain HSB07 was identified as a member of the genus Halomonas. A crude ethyl acetate extract of strain HSB07 showed moderate inhibition activity against Gymnodinium sp. in a bioactive prescreening experiment. The extract was further separated into fractions A, B, and C by silica gel column chromatography. Fractions B and C showed strong inhibition activities against Gymnodinium. This is the first report of inhibitory activity of secondary metabolites of a Halomonas bacterium against a red-tide-causing microalga.

Suffocating phytoplankton, suffocating waters - red tides and anoxia

Directory of Open Access Journals (Sweden)

Grant Colborne Pitcher

2016-09-01

Full Text Available The dynamics of O2 depletion in exceptional dinoflagellate blooms, often referred to as red tides or harmful algal blooms (HABs, was investigated in St Helena Bay in the southern Benguela upwelling system in 2013. The transition to bloom decay and anoxia was examined through determination of O2-based productivity and respiration rates. Changes in O2 concentrations in relation to bloom metabolism were tracked by fast response optical sensors following incubation of red tide waters in large volume light-and-dark polycarbonate carboys. Concurrent measurements of nutrients and nutrient uptake rates served to assess the role of nutrient stressors in community metabolism and bloom mortality. The estimates of community productivity and respiration are among the highest values recorded. Nutrient concentrations were found to be low and were unlikely to meet the demands of the bloom as dictated by the rates of nutrient uptake. Ratios of community respiration to gross production were particularly high ranging from 0.6 – 0.73 and are considered to be a function of the inherently high cellular respiration rates of dinoflagellates. Nighttime community respiration was shown to be capable of removing as much as 17.34 ml O2 l-1 from surface waters. These exceptional rates of O2 utilization are likely in some cases to exceed the rate of O2 replenishment via air-water exchange thereby leading overnight to conditions of anoxia. These conditions of nighttime anoxia and nutrient starvation are likely triggers of cell death and bloom mortality further fueling the microbial foodweb and consumption of O2.

75 FR 39241 - Hooper Springs Project

Science.gov (United States)

2010-07-08

... DEPARTMENT OF ENERGY Bonneville Power Administration Hooper Springs Project AGENCY: Bonneville... (collectively referred to as the Hooper Springs Project). The new BPA substation would be called Hooper Springs... proposed project would address voltage stability and reliability concerns of two of BPA's full requirements...

Comparison between geodetic and oceanographic approaches to estimate mean dynamic topography for vertical datum unification: evaluation at Australian tide gauges

Science.gov (United States)

Filmer, M. S.; Hughes, C. W.; Woodworth, P. L.; Featherstone, W. E.; Bingham, R. J.

2018-04-01

The direct method of vertical datum unification requires estimates of the ocean's mean dynamic topography (MDT) at tide gauges, which can be sourced from either geodetic or oceanographic approaches. To assess the suitability of different types of MDT for this purpose, we evaluate 13 physics-based numerical ocean models and six MDTs computed from observed geodetic and/or ocean data at 32 tide gauges around the Australian coast. We focus on the viability of numerical ocean models for vertical datum unification, classifying the 13 ocean models used as either independent (do not contain assimilated geodetic data) or non-independent (do contain assimilated geodetic data). We find that the independent and non-independent ocean models deliver similar results. Maximum differences among ocean models and geodetic MDTs reach >150 mm at several Australian tide gauges and are considered anomalous at the 99% confidence level. These differences appear to be of geodetic origin, but without additional independent information, or formal error estimates for each model, some of these errors remain inseparable. Our results imply that some ocean models have standard deviations of differences with other MDTs (using geodetic and/or ocean observations) at Australian tide gauges, and with levelling between some Australian tide gauges, of ˜ ± 50 mm . This indicates that they should be considered as an alternative to geodetic MDTs for the direct unification of vertical datums. They can also be used as diagnostics for errors in geodetic MDT in coastal zones, but the inseparability problem remains, where the error cannot be discriminated between the geoid model or altimeter-derived mean sea surface.

Activity and feeding of Dotilla fenestrata (Brachyura: Ocypodidae) in ...

African Journals Online (AJOL)

The activity of and consumption of organic material by the sand-bubbler crab Dotilla fenestrata was studied over neap and spring tides on a sheltered sand bank close to the mouth of the warm, temperate Kowie Estuary, South Africa. Crabs emerged from their burrows only after the tide receded, and it was light. Time to ...

Green and golden seaweed tides on the rise.

Science.gov (United States)

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.

Global distributions of diurnal and semi-diurnal tides: observations from HRDI-UARS of the MLT region

Directory of Open Access Journals (Sweden)

A. H. Manson

Full Text Available HRDI (High Resolution Doppler Interferometer-UARS winds data have been analyzed in 4° latitude by 10° longitude cells at 96 km to obtain global contour maps of solar-tidal amplitudes and phases, and also mean winds. The solstices June–July (1993, December–January (1993–1994, and one equinox September–October (1994 are shown. 

The 24-h diurnal tide that maximizes near the 20–25° latitude has significant seasonal changes with equinoctial maxima, and very clear longitudinal variability. Maxima are very clear over the oceans. In contrast, the 12-h semi-diurnal tides that maximize near the 40–55° latitude have very strong seasonal changes with winter maxima, and more modest longitudinal changes. The similarities with MLT (mesosphere-lower thermosphere radar observations (90 km and the GSWM (Global Scale Wave Model are very satisfactory. The mean winds are consistent with expectations and show clear poleward flow from summer to winter hemispheres in the solstices.

Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides Radio science (remote sensing

Sea level change along the Black Sea coast from satellite altimetry, tide gauge and GPS observations

Directory of Open Access Journals (Sweden)

Nevin B. Avsar

2016-01-01

Full Text Available Sea level change affects human living conditions, particularly ocean coasts. However, sea level change is still unclear along the Black Sea coast due to lack of in-situ measurements and low resolution satellite data. In this paper, sea level change along the Black Sea coast is investigated from joint satellite altimetry, tide gauge (TG and Global Positioning System (GPS observations. The linear trend and seasonal components of sea level change are estimated at 8 TG stations (Amasra, Igneada, Trabzon-II, Sinop, Sile, Poti, Tuapse, and Batumi located along the Black Sea coast, which are compared with Satellite Altimetry and GPS. At the tide gauge stations with long-term records such as Poti (about 21 years and Tuapse (about 19 years, the results obtained from the satellite altimetry and tide gauge observations show a remarkably good agreement. While some big differences are existed between Satellite Altimetry and TG at other stations, after adding vertical motion from GPS, correlation coefficients of the trend have been greatly improved from 0.37 to 0.99 at 3 co-located GPS and TG stations (Trabzon-II, Sinop and Sile.

Eutrophication and warming-driven green tides (Ulva rigida) are predicted to increase under future climate change scenarios.

Science.gov (United States)

Gao, Guang; Clare, Anthony S; Rose, Craig; Caldwell, Gary S

2017-01-15

The incidence and severity of extraordinary macroalgae blooms (green tides) are increasing. Here, climate change (ocean warming and acidification) impacts on life history and biochemical responses of a causative green tide species, Ulva rigida, were investigated under combinations of pH (7.95, 7.55, corresponding to lower and higher pCO 2 ), temperature (14, 18°C) and nitrate availability (6 and 150μmolL -1 ). The higher temperature accelerated the onset and magnitude of gamete settlement. Any two factor combination promoted germination and accelerated growth in young plants. The higher temperature increased reproduction, which increased further in combination with elevated pCO 2 or nitrate. Reproductive success was highest (64.4±5.1%) when the upper limits of all three variables were combined. Biochemically, more protein and lipid but less carbohydrate were synthesized under higher temperature and nitrate conditions. These results suggest that climate change may cause more severe green tides, particularly when eutrophication cannot be effectively controlled. Copyright © 2016 Elsevier Ltd. All rights reserved.

Software Test Description (STD) for the Globally Relocatable Navy Tide/Atmospheric Modeling System (PCTides)

National Research Council Canada - National Science Library

Posey, Pamela

2002-01-01

The purpose of this Software Test Description (STD) is to establish formal test cases to be used by personnel tasked with the installation and verification of the Globally Relocatable Navy Tide/Atmospheric Modeling System (PCTides...

Combined tide and storm influence on facies sedimentation of miocene Miri Formation, Sarawak

International Nuclear Information System (INIS)

Yuniarta Ulfa; Nasiman Sapari; Zuhar Zahir Tuan Harith

2011-01-01

This study was conducted on the sedimentary rocks belonging to the Miri Formation (Middle - Late Miocene). The primary objective of the present study is to provide additional interpretation on the stratigraphy of the Miri Formation in the Miri Field based on the new information gathered from new outcrops in the area. Five outcrops were examined in detail on sedimentology and stratigraphy. Based on lithology, sedimentary structures, bedding geometry and traces fossil, the sediments of the Miri Formation were grouped into fourteen lithofacies. Influence of tide and storm during the depositional processes of the formation were indicated by the group of two main facies associations which are: (i) tide-dominated estuary; and (ii) wave-and-storm dominated facies associations. The tide-dominated estuary system of the Miri Formation are includes variety of sub environments: estuary mouth or tidal channel and sand bars (characterized by trough cross-stratified sandstone with mud drapes facies), estuary channel or upper flow regime of sand flat (characterized by parallel stratified sandstone with mud-laminas facies), mixed-tidal flat (characterized by wavy and flaser bedded sandstone facies), and mud-tidal flat (characterized by rhythmic stratified sandstone-mudstone and lenticular bedding facies). The wave-and-storm dominated varied from lower to middle shore face (characterized by hummocky cross-stratified sandstone and rhythmic parallel stratified sandstone and laminated siltstone facies), upper shore face (characterized by swaley cross-stratified sandstone), lower shore face inter bedded to bioturbated sandstone and siltstone facies), and offshore transitional (characterized by bioturbated sandstone and mudstone inter bedding with parallel to hummocky cross-stratified sandstone facies). (author)

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

Science.gov (United States)

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. Copyright © 2013 Elsevier B.V. All rights reserved.

Predicting typhoon-induced storm surge tide with a two-dimensional hydrodynamic model and artificial neural network model

Science.gov (United States)

Chen, W.-B.; Liu, W.-C.; Hsu, M.-H.

2012-12-01

Precise predictions of storm surges during typhoon events have the necessity for disaster prevention in coastal seas. This paper explores an artificial neural network (ANN) model, including the back propagation neural network (BPNN) and adaptive neuro-fuzzy inference system (ANFIS) algorithms used to correct poor calculations with a two-dimensional hydrodynamic model in predicting storm surge height during typhoon events. The two-dimensional model has a fine horizontal resolution and considers the interaction between storm surges and astronomical tides, which can be applied for describing the complicated physical properties of storm surges along the east coast of Taiwan. The model is driven by the tidal elevation at the open boundaries using a global ocean tidal model and is forced by the meteorological conditions using a cyclone model. The simulated results of the hydrodynamic model indicate that this model fails to predict storm surge height during the model calibration and verification phases as typhoons approached the east coast of Taiwan. The BPNN model can reproduce the astronomical tide level but fails to modify the prediction of the storm surge tide level. The ANFIS model satisfactorily predicts both the astronomical tide level and the storm surge height during the training and verification phases and exhibits the lowest values of mean absolute error and root-mean-square error compared to the simulated results at the different stations using the hydrodynamic model and the BPNN model. Comparison results showed that the ANFIS techniques could be successfully applied in predicting water levels along the east coastal of Taiwan during typhoon events.

Developing bulk exchange spring magnets

Science.gov (United States)

Mccall, Scott K.; Kuntz, Joshua D.

2017-06-27

A method of making a bulk exchange spring magnet by providing a magnetically soft material, providing a hard magnetic material, and producing a composite of said magnetically soft material and said hard magnetic material to make the bulk exchange spring magnet. The step of producing a composite of magnetically soft material and hard magnetic material is accomplished by electrophoretic deposition of the magnetically soft material and the hard magnetic material to make the bulk exchange spring magnet.

Salt Intrusion in the Tweed Estuary

Science.gov (United States)

Uncles, R. J.; Stephens, J. A.

1996-09-01

Results are presented from a 2-week field programme in the Tweed Estuary, U.K. Maximum values of the empirically based Estuarine Richardson Number, Ri E, occurred during neap tides, and minimum values occurred during spring tides. Estimated values of Ri Evaried between 0·3 and 2·3, suggesting the occurrence of partially mixed to stratified conditions, depending on tidal state and freshwater inflow. These relatively large values of Ri Ewere consistent with both observed strong salinity stratification and large salt fluxes due to vertical shear transport. Low values (0·5) values in the halocline. A velocity maximum occurred within the halocline during the early flood. Wave-like spatial oscillations of the halocline occurred on the ebb. The oscillation troughs were situated above deep holes located just down-estuary of the rail and old road bridges. There was an indication that the constricted flow between the bridges' arches resulted in enhanced mixing of near-surface waters and a thickening of the halocline. It is also possible that these wave-like structures were stationary, near-critical internal lee waves, triggered by the deep holes. Trapping of high-salinity waters occurred on the ebb. Saline pools were isolated within a deep hole or deeper section of bed by the falling halocline. When the salt wedge moved further down-estuary, the ' trapped ' waters were subjected to strongly ebbing, overlying freshwater, and were subsequently entrained and flushed. The salinity intrusion was a strong function of spring-neap tidal state and a weaker function of freshwater inflow. The estimated salinity intrusion varied from about 4·7 to 7·6 km during the fieldwork period. The strong dependence on tidal range followed from the comparable lengths of the tidal excursion and salinity intrusion. Long excursion lengths were also partly responsible for the short residence (or flushing) times and their strong dependence on spring-neap tidal state. For typical summer freshwater

Near-bed observations of high-concentration sediment transport in the Changjiang Estuary

Science.gov (United States)

Zhou, Z.; Ge, J.; Ding, P.

2017-12-01

The North Passage, the core of turbidity maximum in the Changjiang Estuary, is now under the strong sedimentation due to the abundant sediment supply from the upstream Changjiang River and the river-tide interacted dynamics. Recent studies suggested that strong siltation could be attributed to bottom high-concentration sediment transport, which however is very difficult to be detected and observed by vessel-anchored survey methods. To better understand the mechanisms of sediment transport and deposition in the channel region of the North Passage and its adjacent areas, we conducted continuous field observations which covered spring and neap tide period in the wintertime of 2016, the summertime of 2015 and 2017, focusing on near-bottom sediment transport. Tripods mounted with multiple instruments, including up-looking and down-looking Acoustic Doppler Current Profilers(ADCP), Vector Current Meter(ADV), Optical Backscatter Sensor(OBS), ASM, ALEC and RBR were used to observe the near-bottom physical process and its induced sediment dynamics. Results of these observations clearly described the current-wave-sediment interaction, which produced different patterns of bottom mud suspension at different tripods. Both hydrodynamic features and suspended sediment showed variations between spring and neap tide. Taking data of 2016 as an example, averaged suspended sediment concentration(SSC) at two tripods was 1.52 g/L and 2.13 g/L during the neap tide, 4.51 g/L and 5.75 g/L with the peak value reaching 25 g/L during the spring tide. At the tripod which was closer to the channel region, three peaks of SSC during the spring tide occurred near the flood slack with notable salinity increase, indicating the impact of saltwater intrusion on the bottom hydrodynamics. The results showed the occurrence of high-concentration suspended sediment was probably related to combined effects of bottom salinity intrusion, turbulent kinetic energy(TKE) and local stratification due to density

Vibro-spring particle size distribution analyser

International Nuclear Information System (INIS)

Patel, Ketan Shantilal

2002-01-01

This thesis describes the design and development of an automated pre-production particle size distribution analyser for particles in the 20 - 2000 μm size range. This work is follow up to the vibro-spring particle sizer reported by Shaeri. In its most basic form, the instrument comprises a horizontally held closed coil helical spring that is partly filled with the test powder and sinusoidally vibrated in the transverse direction. Particle size distribution data are obtained by stretching the spring to known lengths and measuring the mass of the powder discharged from the spring's coils. The size of the particles on the other hand is determined from the spring 'intercoil' distance. The instrument developed by Shaeri had limited use due to its inability to measure sample mass directly. For the device reported here, modifications are made to the original configurations to establish means of direct sample mass measurement. The feasibility of techniques for measuring the mass of powder retained within the spring are investigated in detail. Initially, the measurement of mass is executed in-situ from the vibration characteristics based on the spring's first harmonic resonant frequency. This method is often erratic and unreliable due to the particle-particle-spring wall interactions and the spring bending. An much more successful alternative is found from a more complicated arrangement in which the spring forms part of a stiff cantilever system pivoted along its main axis. Here, the sample mass is determined in the 'static mode' by monitoring the cantilever beam's deflection following the wanton termination of vibration. The system performance has been optimised through the variations of the mechanical design of the key components and the operating procedure as well as taking into account the effect of changes in the ambient temperature on the system's response. The thesis also describes the design and development of the ancillary mechanisms. These include the pneumatic

Gravity waves, Tides and Planetary wave characteristics revealed by network of MLT radars over Indian region

Science.gov (United States)

Venkat Ratnam, Madineni; Karanam, Kishore Kumar; Sunkara, Eswaraiah; Vijaya Bhaskara Rao, S.; Subrahmanyam, K. V.; Ramanjaneyulu, L.

2016-07-01

Mesosphere and Lower Thermosphere (MLT) mean winds, gravity waves, tidal and planetary wave characteristics are investigated using two years (2013-2015) of advanced meteor radar installed at Tirupathi (13.63oN, 79.4oE), India. The observations reveal the presence of high frequency gravity waves (30-120 minutes), atmospheric tides (diurnal, semi-diurnal and terr-diurnal) along with long period oscillations in both zonal and meridional winds. Background mean zonal winds show clear semi-annual oscillation in the mesosphere, whereas meridional winds are characterized by annual oscillation as expected. Diurnal tide amplitudes are significantly larger (60-80 m/s) than semi-diurnal (10-20 m/s) and terr-diurnal (5-8 m/s) tides and larger in meridional than zonal winds. The measured meridional components are in good agreement with Global Scale Wave Model (GSWM-09) predictions than zonal up to ~90 km in all the seasons, except fall equinox. Diurnal tidal phase matches well than the amplitudes between observations and model predictions. However, no similarity is being found in the semi-diurnal tides between observations and model. The measurements are further compared with nearby Thumba meteor radar (8.5oN, 77oE) observations. Some differences do exist between the measurements from Tirupati and Thumba meteor radar and model outputs at greater heights and the possible reasons are discussed. SVU meteor radar observations clearly showed the dominance of well-known ultra-fast kelvin waves (3.5 days), 5-8 day, 16 day, 27 day, and 30-40 day oscillations. Due to higher meteor count extending up to 110 km, we could investigate the variability of these PWs and oscillations covering wider range (70-110 km) for the first time. Significant change above 100 km is noticed in all the above mentioned PW activity and oscillations. We also used ERA-Interim reanalysis data sets available at 0.125x0.125 degree grids for investigating the characteristics of these PW right from surface to 1 h

A protocol for measuring spatial variables in soft-sediment tide pools

Directory of Open Access Journals (Sweden)

Marina R. Brenha-Nunes

2016-01-01

Full Text Available ABSTRACT We present a protocol for measuring spatial variables in large (>50 m2 soft-sediment tide pool. Secondarily, we present the fish capture efficiency of a sampling protocol that based on such spatial variables to calculate relative abundances. The area of the pool is estimated by summing areas of basic geometric forms; the depth, by taken representative measurements of the depth variability of each pool's sector, previously determined according to its perimeter; and the volume, by considering the pool as a prism. These procedures were a trade-off between the acquisition of reliable estimates and the minimization of both the cost of operating and the time spent in field. The fish sampling protocol is based on two con secutive stages: 1 two people search for fishes under structures (e.g., rocks and litters on the pool and capture them with hand seines; 2 these structures are removed and then a beach-seine is hauled over the whole pool. Our method is cheaper than others and fast to operate considering the time in low tides. The method to sample fish is quite efficient resulting in a capture efficiency of 89%.

Optimizing the Performance of Solo Duck Wave Energy Converter in Tide

Directory of Open Access Journals (Sweden)

Jinming Wu

2017-02-01

Full Text Available The high efficiency performance of the Edinburgh Duck wave energy converter (WEC in 2D regular wave tests makes it a promising wave energy conversion scheme. A solo Duck WEC will be able to apply the point absorber effect to further enhance its performance. Since released degree of freedom will decrease the efficiency, a Duck WEC with fixed pitching axis will be a better option. However, for fixed supported WECs, tide is a non-ignorable consideration. In this paper, a movable mass method is utilized in the whole tidal range to not only balance the Duck to appropriate beak angles, but also follow the variation of hydrodynamic coefficients to keep cancelling the reactance of the system impedance so that complex conjugate control can be realized to optimize the power capture performance of the Duck WEC in tide. Results show that the beak angle should be adjusted to as large a value as possible so that the response amplitude of the Duck at maximum relative capture width will be reasonable small, and the lowest weight of the movable mass is found when its designed position locates at the center of the Duck profile.

Force delivery of Ni-Ti coil springs.

Science.gov (United States)

Manhartsberger, C; Seidenbusch, W

1996-01-01

Sentalloy springs (GAC, Central Islip, N.Y.) of the open and closed type were investigated with a special designed device. The closed coil springs were subjected to a tensile and the open coil springs to a compression test. After a first measurement, the springs were activated for a period of 4 weeks and then reinvestigated with the same procedure. It could be shown distinctly that, with the different coil springs, the force delivery given by the producer could be achieved only within certain limits. To remain in the martensitic plateau, changed activation ranges, and for the Sentalloy coil springs white and red of the open and closed type, also changed force deliveries had to be taken into account. There was a distinct decrease in force delivery between the first and second measurement. After considering the loading curves of all the Sentalloy coil springs and choosing the right activation range respective to the force delivery, it was found that the coil springs deliver a superior clinical behavior and open new treatment possibilities.

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

Science.gov (United States)

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 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.

Flow-induced vibration of helical coil compression springs

International Nuclear Information System (INIS)

Stokes, F.E.; King, R.A.

1983-01-01

Helical coil compression springs are used in some nuclear fuel assembly designs to maintain holddown and to accommodate thermal expansion. In the reactor environment, the springs are exposed to flowing water, elevated temperatures and pressures, and irradiation. Flow parallel to the longitudinal axis of the spring may excite the spring coils and cause vibration. The purpose of this investigation was to determine the flow-induced vibration (FIV) response characteristics of the helical coil compression springs. Experimental tests indicate that a helical coil spring responds like a single circular cylinder in cross-flow. Two FIV excitation mechanisms control spring vibration. Namely: 1) Turbulent Buffeting causes small amplitude vibration which increases as a function of velocity squared. 2) Vortex Shedding causes large amplitude vibration when the spring natural frequency and Strouhal frequency coincide. Several methods can be used to reduce or to prevent vortex shedding large amplitude vibrations. One method is compressing the spring to a coil pitch-to-diameter ratio of 2 thereby suppressing the vibration amplitude. Another involves modifying the spring geometry to alter its stiffness and frequency characteristics. These changes result in separation of the natural and Strouhal frequencies. With an understanding of how springs respond in the flowing water environment, the spring physical parameters can be designed to avoid large amplitude vibration. (orig.)

Marble Canyon spring sampling investigation

International Nuclear Information System (INIS)

McCulley, B.

1985-10-01

The Mississippian Leadville Limestone is the most permeable formation in the lower hydrostratigraphic unit underlying the salt beds of the Paradox Formation in Gibson Dome, Paradox Basin, Utah, which is being considered as a potential nuclear waste repository site. The closest downgradient outcrop of the Mississippian limestone is along the Colorado River in Marble Canyon, Arizona. This report describes the sampling and interpretation of springs in that area to assess the relative contribution of Gibson Dome-type Leadville Limestone ground water to that spring discharge. The high-volume (hundreds of liters per second or thousands of gallons per minute) springs discharging from fault zones in Marble Canyon are mixtures of water recharged west of the Colorado River on the Kaibab Plateau and east of the river in the Kaiparowits basin. No component of Gibson Dome-type Leadville Limestone ground water is evident in major and trace element chemistry or isotopic composition of the Marble Canyon Springs. A low-volume (0.3 liters per second or 5 gallons per minute) spring with some chemical and isotopic characteristics of Gibson Dome-type Leadville Limestone water diluted by Kaiparowits basin-type water issues from a travertine mound in the Bright Angel Shale on the Little Colorado River. However, the stable isotopic composition and bromide levels of that spring discharge, in addition to probable ground-water flow paths, contradict the dilution hypothesis

Open-Coil Retraction Spring

Directory of Open Access Journals (Sweden)

Pavankumar Janardan Vibhute

2011-01-01

Full Text Available Sliding mechanic has become a popular method for space closure with developments in preadjusted edgewise appliance. Furthermore, various space closing auxiliaries have been developed and evaluated extensively for their clinical efficiency. Their effectiveness enhanced with optimum force magnitude and low-load deflection rate (LDR/force decay. With the advent of NiTi springs in orthodontics, LDRs have been markedly reduced. For use of NiTi, clinician has to depend upon prefabricated closed coil springs. “Open Coil Retraction Spring (OCRS” is developed utilizing NiTi open-coil spring for orthodontic space closure. This paper describes fabrication and clinical application of OCRS which have number of advantages. It sustains low LDR with optimum force magnitude. Its design is adjustable for desired length and force level. It is fail-safe for both activation and deactivation (i.e., it cannot be over activated, and decompression limit of open coil is also controlled by the operator, resp.. A possibility to offset the OCRS away from mucosa helps to reduce its soft-tissue impingement.

A 82Br tracer study of coastal groundwater movement at Hat Head, NSW

International Nuclear Information System (INIS)

Hughes, C.; Stone, D.

2003-01-01

At Hat Head, NSW, on the eastern Australian coast, a radioisotope tracer study of groundwater flow in response to tidal forcing was conducted adjacent to a tidal creek. Using radiotracer, 82 Br, groundwater movement was tracked in-situ over 5 days on two occasions encompassing both neap and spring tide conditions. The tracer was injected into one borehole and gamma counts monitored from an adjacent borehole using NaI(Th) detectors. This technique maps the path of the slow moving tracer without sampling and allows the net groundwater movement to be distinguished from short term tidally driven fluxes. During the neap tide period net groundwater movement of 0.1 m/d was observed with horizontal tidal fluctuations in the order of 0.04 m. This contrasts with the tidally dominated spring tide period where net groundwater movement was negligible but tidally driven fluctuations of up to 0.13 m were observed

Outer grid strap protruding spring repair apparatus

International Nuclear Information System (INIS)

Widener, W.H.

1987-01-01

This patent describes a nuclear fuel assembly grid spring repair apparatus for repairing a spring formed on an outer strap of a fuel assembly grid and having a portion protruding outwardly beyond the strap, the apparatus comprising: (a) a support frame defining an opening and having means defining a guide channel extending along the opening in a first direction; (b) means mounted on the frame and being adjustable for attaching the frame to the outer strap of the support grid so that the frame opening is aligned with the outwardly protruding spring on the outer strap; (c) an outer slide having a passageway defined therethrough and being mounted in the guide channel for reciprocable movement along the frame opening in the first direction for aligning the passageway with the outwardly protruding portion of the spring on the outer strap. The outer slide also has means defining a guide way extending along the passageway in a second direction generally orthogonal to the first direction; (d) a spring reset mechanism being operable for resetting the protruding spring to a nonprotruding position relative to the outer strap when the mechanism is aligned with the protruding portion of the spring; and (e) an inner slide supporting the spring reset mechanism and being mounted to the guide way for reciprocable movement along the passageway of the outer slide in the second direction for aligning the spring reset mechanism with the protruding portion of the spring on the outer strap

Prediction of Spring Rate and Initial Failure Load due to Material Properties of Composite Leaf Spring

International Nuclear Information System (INIS)

Oh, Sung Ha; Choi, Bok Lok

2014-01-01

This paper presented analysis methods for adapting E-glass fiber/epoxy composite (GFRP) materials to an automotive leaf spring. It focused on the static behaviors of the leaf spring due to the material composition and its fiber orientation. The material properties of the GFRP composite were directly measured based on the ASTM standard test. A reverse implementation was performed to obtain the complete set of in-situ fiber and matrix properties from the ply test results. Next, the spring rates of the composite leaf spring were examined according to the variation of material parameters such as the fiber angles and resin contents of the composite material. Finally, progressive failure analysis was conducted to identify the initial failure load by means of an elastic stress analysis and specific damage criteria. As a result, it was found that damage first occurred along the edge of the leaf spring owing to the shear stresses

Influence of mantle anelasticity on the phase and amplitude of earth tides

Science.gov (United States)

Bodri, B.; Pedersen, G. P. H.

1980-05-01

The effect of the anelasticity of the mantle on the phase and amplitude of earth tides is calculated for recent models of the internal structure of the earth and its rheological characteristics. The anelastic properties of the mantle are modeled by the Maxwell and Knopoff-Lomnitz rheological bodies. For numerical calculations two different methods of solution are used. Results indicate that the effect of mantle anelasticity on tidal amplitudes is practically zero. For both types of rheological models the phase shifts of the functions characterizing solid tides are small, none of them exceeding values of some minutes of arc. These phase shifts have a very weak dependence on the variation of attenuation and viscosity within the mantle. The present study is closely related to an important problem: what proportion of the observed tidal friction arises not in the ocean but is due to the anelasticity of the mantle. The results suggest that dissipation by solid friction at present is an insignificant, almost negligible component of tidal energy sink.

Cross-shelf transport into nearshore waters due to shoaling internal tides in San Pedro Bay, CA

Science.gov (United States)

Noble, Marlene A.; Burt Jones,; Peter Hamilton,; Xu, Jingping; George Robertson,; Rosenfeld, Leslie; John Largier,

2009-01-01

In the summer of 2001, a coastal ocean measurement program in the southeastern portion of San Pedro Bay, CA, was designed and carried out. One aim of the program was to determine the strength and effectiveness of local cross-shelf transport processes. A particular objective was to assess the ability of semidiurnal internal tidal currents to move suspended material a net distance across the shelf. Hence, a dense array of moorings was deployed across the shelf to monitor the transport patterns associated with fluctuations in currents, temperature and salinity. An associated hydrographic program periodically monitored synoptic changes in the spatial patterns of temperature, salinity, nutrients and bacteria. This set of measurements show that a series of energetic internal tides can, but do not always, transport subthermocline water, dissolved and suspended material from the middle of the shelf into the surfzone. Effective cross-shelf transport occurs only when (1) internal tides at the shelf break are strong and (2) subtidal currents flow strongly downcoast. The subtidal downcoast flow causes isotherms to tilt upward toward the coast, which allows energetic, nonlinear internal tidal currents to carry subthermocline waters into the surfzone. During these events, which may last for several days, the transported water remains in the surfzone until the internal tidal current pulses and/or the downcoast subtidal currents disappear. This nonlinear internal tide cross-shelf transport process was capable of carrying water and the associated suspended or dissolved material from the mid-shelf into the surfzone, but there were no observation of transport from the shelf break into the surfzone. Dissolved nutrients and suspended particulates (such as phytoplankton) transported from the mid-shelf into the nearshore region by nonlinear internal tides may contribute to nearshore algal blooms, including harmful algal blooms that occur off local beaches.

The impact of future sea-level rise on the global tides

Science.gov (United States)

Pickering, M. D.; Horsburgh, K. J.; Blundell, J. R.; Hirschi, J. J.-M.; Nicholls, R. J.; Verlaan, M.; Wells, N. C.

2017-06-01

Tides are a key component in coastal extreme water levels. Possible changes in the tides caused by mean sea-level rise (SLR) are therefore of importance in the analysis of coastal flooding, as well as many other applications. We investigate the effect of future SLR on the tides globally using a fully global forward tidal model: OTISmpi. Statistical comparisons of the modelled and observed tidal solutions demonstrate the skill of the refined model setup with no reliance on data assimilation. We simulate the response of the four primary tidal constituents to various SLR scenarios. Particular attention is paid to future changes at the largest 136 coastal cities, where changes in water level would have the greatest impact. Spatially uniform SLR scenarios ranging from 0.5 to 10 m with fixed coastlines show that the tidal amplitudes in shelf seas globally respond strongly to SLR with spatially coherent areas of increase and decrease. Changes in the M2 and S2 constituents occur globally in most shelf seas, whereas changes in K1 and O1 are confined to Asian shelves. With higher SLR tidal changes are often not proportional to the SLR imposed and larger portions of mean high water (MHW) changes are above proportional. Changes in MHW exceed ±10% of the SLR at 10% of coastal cities. SLR scenarios allowing for coastal recession tend increasingly to result in a reduction in tidal range. The fact that the fixed and recession shoreline scenarios result mainly in changes of opposing sign is explained by the effect of the perturbations on the natural period of oscillation of the basin. Our results suggest that coastal management strategies could influence the sign of the tidal amplitude change. The effect of a spatially varying SLR, in this case fingerprints of the initial elastic response to ice mass loss, modestly alters the tidal response with the largest differences at high latitudes.

Pro Spring security

CERN Document Server

Scarioni, Carlo

2013-01-01

Security is a key element in the development of any non-trivial application. The Spring Security Framework provides a comprehensive set of functionalities to implement industry-standard authentication and authorization mechanisms for Java applications. Pro Spring Security will be a reference and advanced tutorial that will do the following: Guides you through the implementation of the security features for a Java web application by presenting consistent examples built from the ground-up. Demonstrates the different authentication and authorization methods to secure enterprise-level applications

1988 Hanford riverbank springs characterization report

International Nuclear Information System (INIS)

Dirkes, R.L.

1990-12-01

This reports presents the results of a special study undertaken to characterize the riverbank springs (i.e., ground-water seepage) entering the Columbia River along the Hanford Site. Radiological and nonradiological analyses were performed. River water samples were also analyzed from upstream and downstream of the Site as well as from the immediate vicinity of the springs. In addition, irrigation return water and spring water entering the river along the shoreline opposite Hanford were analyzed. Hanford-origin contaminants were detected in spring water entering the Columbia River along the Hanford Site. The type and concentrations of contaminants in the spring water were similar to those known to exist in the ground water near the river. The location and extent of the contaminated discharges compared favorably with recent ground-water reports and predictions. Spring discharge volumes remain very small relative to the flow of the Columbia. Downstream river sampling demonstrates the impact of ground-water discharges to be minimal, and negligible in most cases. Radionuclide concentrations were below US Department of Energy Derived Concentration Guides (DCGs) with the exception 90 Sr near the 100-N Area. Tritium, while below the DCG, was detected at concentrations above the US Environmental Protection Agency drinking water standards in several springs. All other radionuclide concentrations were below drinking water standards. Nonradiological contaminants were generally undetectable in the spring water. River water contaminant concentrations, outside of the immediate discharge zones, were below drinking water standards in all cases. 19 refs., 5 figs., 12 tabs

A springs actuated finger exoskeleton: From mechanical design to spring variables evaluation.

Science.gov (United States)

Bortoletto, Roberto; Mello, Ashley N; Piovesan, Davide

2017-07-01

In the context of post-stroke patients, suffering of hemiparesis of the hand, robot-aided neuro-motor rehabilitation allows for intensive rehabilitation treatments and quantitative evaluation of patients' progresses. This work presents the design and evaluation of a spring actuated finger exoskeleton. In particular, the spring variables and the interaction forces between the assembly and the hand were investigated, in order to assess the effectiveness of the proposed exoskeleton.

Portrait of a Geothermal Spring, Hunter's Hot Springs, Oregon.

Science.gov (United States)

Castenholz, Richard W

2015-01-27

Although alkaline Hunter's Hot Springs in southeastern Oregon has been studied extensively for over 40 years, most of these studies and the subsequent publications were before the advent of molecular methods. However, there are many field observations and laboratory experiments that reveal the major aspects of the phototrophic species composition within various physical and chemical gradients of these springs. Relatively constant temperature boundaries demark the upper boundary of the unicellular cyanobacterium, Synechococcus at 73-74 °C (the world-wide upper limit for photosynthesis), and 68-70 °C the upper limit for Chloroflexus. The upper limit for the cover of the filamentous cyanobacterium, Geitlerinema (Oscillatoria) is at 54-55 °C, and the in situ lower limit at 47-48 °C for all three of these phototrophs due to the upper temperature limit for the grazing ostracod, Thermopsis. The in situ upper limit for the cyanobacteria Pleurocapsa and Calothrix is at ~47-48 °C, which are more grazer-resistant and grazer dependent. All of these demarcations are easily visible in the field. In addition, there is a biosulfide production in some sections of the springs that have a large impact on the microbiology. Most of the temperature and chemical limits have been explained by field and laboratory experiments.

Tides in the Mandovi and Zuari estuaries, Goa, west coast of India

Indian Academy of Sciences (India)

Mandovi and Zuari are two estuaries located in Goa,west coast of India.Variation of water level in the estuaries was monitored for a month at 13 locations using tide-poles during March –April 2003.Analysis of this data has provided for the first time,characteristics of how tidal constituents vary in the narrow and shallow ...

Soft tissue modelling with conical springs.

Science.gov (United States)

Omar, Nadzeri; Zhong, Yongmin; Jazar, Reza N; Subic, Aleksandar; Smith, Julian; Shirinzadeh, Bijan

2015-01-01

This paper presents a new method for real-time modelling soft tissue deformation. It improves the traditional mass-spring model with conical springs to deal with nonlinear mechanical behaviours of soft tissues. A conical spring model is developed to predict soft tissue deformation with reference to deformation patterns. The model parameters are formulated according to tissue deformation patterns and the nonlinear behaviours of soft tissues are modelled with the stiffness variation of conical spring. Experimental results show that the proposed method can describe different tissue deformation patterns using one single equation and also exhibit the typical mechanical behaviours of soft tissues.

Tenofovir disoproxil fumarate monotherapy for nucleos(tide analogue-naïve and nucleos(tide analogue-experienced chronic hepatitis B patients

Directory of Open Access Journals (Sweden)

Sang Kyung Jung

2015-03-01

Full Text Available Background/AimsThis study investigated the antiviral effects of tenofovir disoproxil fumarate (TDF monotherapy in nucleos(tide analogue (NA-naive and NA-experienced chronic hepatitis B (CHB patients.MethodsCHB patients treated with TDF monotherapy (300 mg/day for ≥12 weeks between December 2012 and July 2014 at a single center were retrospectively enrolled. Clinical, biochemical, and virological parameters were assessed every 12 weeks.ResultsIn total, 136 patients (median age 49 years, 96 males, 94 HBeAg positive, and 51 with liver cirrhosis were included. Sixty-two patients were nucleos(tide (NA-naïve, and 74 patients had prior NA therapy (NA-exp group, and 31 patients in the NA-exp group had lamivudine (LAM-resistance (LAM-R group. The baseline serum hepatitis B virus (HBV DNA level was 4.9±2.3 log IU/mL (mean±SD, and was higher in the NA-naïve group than in the NA-exp and LAM-R groups (5.9±2.0 log IU/mL vs 3.9±2.0 log IU/mL vs 4.2±1.7 log IU/mL, P<0.01. The complete virological response (CVR rate at week 48 in the NA-naïve group (71.4% did not differ significantly from those in the NA-exp (71.3% and LAM-R (66.1% groups. In multivariate analysis, baseline serum HBV DNA was the only predictive factor for a CVR at week 48 (hazard ratio, 0.809; 95% confidence interval, 0.729-0.898, while the CVR rate did not differ with the NA experience.ConclusionsTDF monotherapy was effective for CHB treatment irrespective of prior NA treatment or LAM resistance. Baseline serum HBV DNA was the independent predictive factor for a CVR.

The 2004 Indian Ocean tsunami: Description of the event and estimation of length of the tsunami source region based on data from Indian tide gauge

Digital Repository Service at National Institute of Oceanography (India)

Suresh, I.; Neetu, S.; Shankar, D.; Shenoi, S.S.C.; Shetye, S.R.; Sundar, D.

. Column 2 gives the arrival time (AT, UTC), column 3 the amplitude of the first wave (residual) (FW, cm), and column 4 the maximum amplitude over the tide (residual) (Max, cm). Other acronyms are as follows: FW, first wave; HT, high tide; LT, low tide...) [4]. Station AT FW Max Remarks Gauge type Interval Paradip 0330 89 215 FW just after HT, max just before LT(also MWL) PT 6 Visakhapatnam 0340 65 159 FW around HT, max close to LT (also MWL) FT 5 Chennai 0335 64 190 FW around HT...

Isolators Including Main Spring Linear Guide Systems

Science.gov (United States)

Goold, Ryan (Inventor); Buchele, Paul (Inventor); Hindle, Timothy (Inventor); Ruebsamen, Dale Thomas (Inventor)

2017-01-01

Embodiments of isolators, such as three parameter isolators, including a main spring linear guide system are provided. In one embodiment, the isolator includes first and second opposing end portions, a main spring mechanically coupled between the first and second end portions, and a linear guide system extending from the first end portion, across the main spring, and toward the second end portion. The linear guide system expands and contracts in conjunction with deflection of the main spring along the working axis, while restricting displacement and rotation of the main spring along first and second axes orthogonal to the working axis.

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

Science.gov (United States)

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. Copyright © 2012 Elsevier Ltd. All rights reserved.

Decadal-scale variation in dune erosion and accretion rates: An investigation of the significance of changing storm tide frequency and magnitude on the Sefton coast, UK

Science.gov (United States)

Pye, K.; Blott, S. J.

2008-12-01

Monitoring of frontal dune erosion and accretion on the Sefton coast in northwest England over the past 50 years has revealed significant spatial and temporal variations. Previous work has shown that the spatial variations primarily reflect longshore differences in beach and nearshore morphology, energy regime and sediment budget, but the causes of temporal variations have not previously been studied in detail. This paper presents the results of work carried out to test the hypothesis that a major cause of temporal variation is changes in the frequency and magnitude of storms, surges and resulting high tides. Dune toe erosion/accretion records dating from 1958 have been compared with tide gauge records at Liverpool and Heysham. Relatively high dune erosion rates at Formby Point 1958-1968 were associated with a relatively large number of storm tides. Slower erosion at Formby, and relatively rapid accretion in areas to the north and south, occurred during the 1970's and 1980's when there were relatively few major storm tides. After 1990 rates of dune erosion at Formby increased again, and dunes to the north and south experienced slower accretion. During this period high storm tides have been more frequent, and the annual number of hours with water levels above the critical level for dune erosion has increased significantly. An increase in the rate of mean sea-level rise at both Liverpool and Heysham is evident since 1990, but we conclude that this factor is of less importance than the occurrence of extreme high tides and wave action associated with storms. The incidence of extreme high tides shows an identifiable relationship with the lunar nodal tidal cycle, but the evidence indicates that meteorological forcing has also had a significant effect. Storms and surges in the eastern Irish Sea are associated with Atlantic depressions whose direction and rate of movement have a strong influence on wind speeds, wave energy and the height of surge tides. However

Making Space for Red Tide: Discolored Water and the Early Twentieth Century Bayscape of Japanese Pearl Cultivation.

Science.gov (United States)

Ericson, Kjell

2017-05-01

"Red tide" has become a familiar shorthand for unusual changes in the color of ocean waters. It is intimately related both to blooms of creatures like dinoflagellates and to the devastating effects they pose to coastal fisheries. This essay tracks the early twentieth century emergence of discolored water as an aquacultural problem, known in Japan as akashio, and its trans-oceanic transformation into the terms and practices of "red tide" in the post-World War II United States. For Japan's "Pearl King" Mikimoto Kōkichi and his contacts in diverse marine scientific communities, the years-long cycle of guarding and cultivating a pearl oyster went together with the ascription of moral qualities to tiny creatures that posed a threat to farmed bayscapes of pearl monoculture. As akashio, discolored water went from curiosity to marine livestock pest, one that at times left dead pearl oysters in its wake. Red tide arose from the sustained study of the mechanisms by which changes in the biological and chemical composition of seawater might become deadly to exclusively-claimed shellfish along Japanese coastlines, but came to be seen as a way to understand aquatic manifestations of harm in other parts of the littoral world.

An objective frequency domain method for subsurface characterisation using Earth and atmospheric tides

Science.gov (United States)

Cuthbert, M. O.; Acworth, I. R.; Halloran, L. J. S.; Rau, G. C.; Bernadi, T. L.

2017-12-01

It has long been recognised that hydraulic properties can be derived from the response of piezometric heads to tidal loadings. However, there is a degree of subjectivity in existing graphical approaches most commonly used to calculate barometric efficiency leading to uncertainties in derived values of compressible storage. Here we demonstrate a novel approach to remove these uncertainties by objectively deriving the barometric efficiency from groundwater hydraulic head responses using a frequency domain method. We take advantage of the presence of worldwide and ubiquitous atmospheric tide fluctuations which occur at 2 cycles per day (cpd). First we use a Fourier transform to calculate the amplitudes of the 2 cpd signals from co-located atmospheric pressure and hydraulic head time series measurements. Next we show how the Earth tide response at the same frequency can be quantified and removed so that this effect does not interfere with the calculation of the barometric efficiency. Finally, the ratio of the amplitude of the response at 2 cpd of hydraulic head to atmospheric pressure is used to quantify the barometric efficiency. This new method allows an objective quantification using `passive' in situ monitoring rather than resorting to aquifer pumping or laboratory tests. The minimum data requirements are 15 days duration of 6-hourly hydraulic head and atmospheric pressure measurements, and modelled Earth tide records which are readily conducted using freely available software. The new approach allows for a rapid and cost-effective alternative to traditional methods of estimating aquifer compressible storage properties without the subjectivity of existing approaches, and will be of importance to improving the spatial coverage of subsurface characterisation for groundwater resource evaluation and land subsidence assessment.

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

Science.gov (United States)

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

2016-05-06

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.

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

Science.gov (United States)

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.

Virus Dynamics Are Influenced by Season, Tides and Advective Transport in Intertidal, Permeable Sediments.

Science.gov (United States)

Vandieken, Verona; Sabelhaus, Lara; Engelhardt, Tim

2017-01-01

Sandy surface sediments of tidal flats exhibit high microbial activity due to the fast and deep-reaching transport of oxygen and nutrients by porewater advection. On the other hand during low tide, limited transport results in nutrient and oxygen depletion concomitant to the accumulation of microbial metabolites. This study represents the first attempt to use flow-through reactors to investigate virus production, virus transport and the impact of tides and season in permeable sediments. The reactors were filled with intertidal sands of two sites (North beach site and backbarrier sand flat of Spiekeroog island in the German Wadden Sea) to best simulate advective porewater transport through the sediments. Virus and cell release along with oxygen consumption were measured in the effluents of reactors during continuous flow of water through the sediments as well as in tidal simulation experiments where alternating cycles with and without water flow (each for 6 h) were operated. The results showed net rates of virus production (0.3-13.2 × 10 6 viruses cm -3 h -1 ) and prokaryotic cell production (0.3-10.0 × 10 5 cells cm -3 h -1 ) as well as oxygen consumption rates (56-737 μmol l -1 h -1 ) to be linearly correlated reflecting differences in activity, season and location of the sediments. Calculations show that total virus turnover was fast with 2 to 4 days, whereas virus-mediated cell turnover was calculated to range between 5-13 or 33-91 days depending on the assumed burst sizes (number of viruses released upon cell lysis) of 14 or 100 viruses, respectively. During the experiments, the homogenized sediments in the reactors became vertically structured with decreasing microbial activities and increasing impact of viruses on prokaryotic mortality with depth. Tidal simulation clearly showed a strong accumulation of viruses and cells in the top sections of the reactors when the flow was halted indicating a consistently high virus production during low tide. In

Masters of the springs

DEFF Research Database (Denmark)

Laursen, Steffen

2010-01-01

flanked by villages that relied on these water recourses for agricultural production. The springs emerged in the zone separating the cemeteries from the settlements. The freshwater springs were actively incorporated into the religious landscape of the dead, by consistently erecting mounds of a particular...... for water - a process which perhaps also is evidenced by temple constructions at Barbar, Umm al-Sujur and Abu Zaydan....

Optical spring effect in nanoelectromechanical systems

International Nuclear Information System (INIS)

Tian, Feng; Zhou, Guangya; Du, Yu; Chau, Fook Siong; Deng, Jie