Effects of water-control structures on hydrologic and water-quality characteristics in selected agricultural drainage canals in eastern North Carolina

USGS Publications Warehouse

Treece, M.W.; Jaynes, M.L.

1994-01-01

November of water into and out of tidally affected canals in eastern North Carolina was documented before and after the installation of water-control structures. Water levels in five of the canals downstream from the water-control structures were controlled primarily by water-level fluctuations in estuarine receiving waters. Water-control structures also altered upstream water levels in all canals. Water levels were lowered upstream from tide gates, but increased upstream from flashboard risers. Both types of water-control structures attenuated the release of runoff following rainfall events, but in slightly different ways. Tide gates appeared to reduce peak discharge rates associated with rainfall, and flashboard risers lengthened the duration of runoff release. Tide gates had no apparent effect on pH, dissolved oxygen, suspended-sediment, or total phosphorus concentrations downstream from the structures. Specific conductance measured from composite samples collected with automatic samples increased downstream of tide gates after installation. Median concentrations of nitrite plus nitrate nitrogen were near the minimum detection level throughout the study; however, the number of observations of concentrations exceeding 0.1 milligram per liter dropped significantly after tide gates were installed. Following tide-gate installation, instantaneous loadings of nitrite plus nitrate nitrogen were significantly reduced at one test site, but this reduction was not observed at the other test site. Loadings of other nutrient species and suspended sediment did not change at the tide-gate test sites after tide-gate installation. Specific conductance was lower in the Beaufort County canals than in the Hyde County canals. Although there was a slight increase in median values at the flashboard-riser sites, the mean and maximum values declined substantially downstream from the risers following installation. This decline of specific conductance in the canals occurred despite a large increase of specific conductance in the tidal creek. Flashboard risers had no significant effect on concentrations of dissolved oxygen, suspended sediment, total ammonia plus organic nitrogen, or phosphorus. Maximum concentrations of ammonia nitrogen were smaller at both test sites after riser installation. In addition, concentrations of nitrite plus nitrate nitrogen exceeding 1.0 milligram per liter rarely occurred at the flashboard-riser test sites following installation of the risers. Median loadings of nitrite plus nitrate nitrogen and total nitrogen decreased at one riser test site following flashboard-riser installation. Tide gates and flashboard risers were associated with reductions in concentrations and export of nitrite plus nitrate nitrogen; however, these changes should be interpreted cautiously because reductions were not observed consistently at every site. The hydrology and baseline water-quality characteristics of the two study areas differ, making comparisons of the effectiveness of the two types of water-control structures difficult to interpret. The effects of water-control structures on the hydrology of the drainage canals are more meaningful than the changes in water quality. Tide gates and flashboard risers altered the hydrologic characteristics of the drainage canals and created an environment favorable for nutrient loss or transformation. Both structures retained agricultural drainage upstream, which increased potential storage for infiltration and reduced the potential for surface runoff, sediment, and nutrient transport, and higher peak outflow rates.

ISEA (International geodetic project in SouthEastern Alaska) for rapid uplifting caused by glacial retreat: (4) Gravity tide observation

NASA Astrophysics Data System (ADS)

Sato, T.; Miura, S.; Sun, W.; Kaufman, A. M.; Cross, R.; Freymueller, J. T.; Heavner, M.

2006-12-01

The southeastern Alaska shows a large uplift rate as 30 mm/yr at most, which is considered to be closely related to the glacial isostatic adjustment (GIA) including two effects of the past and present-day ice melting (Larsen et al., 2004). So, this area is important to improve our knowledge of the viscoelastic property of the earth and to consider the global changes. Combing the displacement and gravity observations is useful to constrain the model computation results for GIA (Sato et al., 2006). In order to progress the previous work by the group of Univ. Alaska, Fairbanks (UAF), an observation project by Japan and USA groups was started in 2005 (Miura et al., this meeting). Under this project, June 2006, the continuous GPS measurements started (M. Kufman et al., this meeting) and the absolute gravity (AG) measurements were conducted (W. Sun et al., this meeting). Precise correction for the effect of ocean tide loading is one of the key to increase the observation accuracy of the GPS and gravity observations, especially for the AG measurement. Thanks for the satellite sea surface altimeters such as TOPEX/Poseidon and Jason-1, the accuracy of global ocean tide models based on these data has been much improved, and its accuracy is estimated at a level better than 1.3 cm as a RMS error of the vector differences of the 8 main tidal waves (Matsumoto et al., 2006). However, on the other hand, it is known that the southeastern Alaska is a place that shows a large discrepancy among the proposed global ocean tide models mainly due to a complex topography and bathymetry of the fjord area. In order to improve the accuracy of the ocean tide correction, we started the gravity tide observation at Juneau from June 2006. Two kinds of gravimeters are used for the observation. Sampling interval of the data is at every 1 min. We analyzed the 1 month data from the beginning of the observation and compared the tidal analysis results with the model tide including both effects of the solid and ocean tides. For this computation, we used the Love numbers and the loading Green function for the PREM earth model (Dziewonski & Anderson, 1981) and a global ocean tide model by Schwiderski (1980). Our comparison clearly indicates that a possibility to improve the accuracy of the model prediction by taking into account the actual tidal harmonics observed in the southeastern Alaska.

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

NASA Astrophysics Data System (ADS)

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 case without tides, after the occurrence of long-term SSEs. These results suggest that stress perturbation by earth tides makes SSEs more episodic even in the situation that the loading in the surrounding area tends to cause temporal stable sliding.

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

NASA Technical Reports Server (NTRS)

Estes, R. H.

1977-01-01

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

Stratification and loading of fecal indicator bacteria (FIB) in a tidally muted urban salt marsh.

PubMed

Johnston, Karina K; Dorsey, John H; Saez, Jose A

2015-03-01

Stratification and loading of fecal indicator bacteria (FIB) were assessed in the main tidal channel of the Ballona Wetlands, an urban salt marsh receiving muted tidal flows, to (1) determine FIB concentration versus loading within the water column at differing tidal flows, (2) identify associations of FIB with other water quality parameters, and (3) compare wetland FIB concentrations to the adjacent estuary. Sampling was conducted four times during spring-tide events; samples were analyzed for FIB and turbidity (NTU) four times over a tidal cycle at pre-allocated depths, depending on the water level. Additional water quality parameters measured included temperature, salinity, oxygen, and pH. Loadings were calculated by integrating the stratified FIB concentrations with water column cross-sectional volumes corresponding to each depth. Enterococci and Escherichia coli were stratified both by concentration and loading, although these variables portrayed different patterns over a tidal cycle. Greatest concentrations occurred in surface to mid-strata levels, during flood tides when contaminated water flowed in from the estuary, and during ebb flows when sediments were suspended. Loading was greatest during flood flows and diminished during low tide periods. FIB concentrations within the estuary often were significantly greater than those within the wetland tide channel, supporting previous studies that the wetlands act as a sink for FIB. For public health water quality monitoring, these results indicate that more accurate estimates of FIB concentrations would be obtained by sampling a number of points within a water column rather than relying only on single surface samples.

Is the alkaline tide a signal to activate metabolic or ionoregulatory enzymes in the dogfish shark (Squalus acanthias)?

PubMed

Wood, Chris M; Kajimura, Makiko; Mommsen, Thomas P; Walsh, Patrick J

2008-01-01

Experimental metabolic alkalosis is known to stimulate whole-animal urea production and active ion secretion by the rectal gland in the dogfish shark. Furthermore, recent evidence indicates that a marked alkaline tide (systemic metabolic alkalosis) follows feeding in this species and that the activities of the enzymes of the ornithine-urea cycle (OUC) for urea synthesis in skeletal muscle and liver and of energy metabolism and ion transport in the rectal gland are increased at this time. We therefore evaluated whether alkalosis and/or NaCl/volume loading (which also occurs with feeding) could serve as a signal for activation of these enzymes independent of nutrient loading. Fasted dogfish were infused for 20 h with either 500 mmol L(-1) NaHCO3 (alkalosis + volume expansion) or 500 mmol L(-1) NaCl (volume expansion alone), both isosmotic to dogfish plasma, at a rate of 3 mL kg(-1) h(-1). NaHCO3 infusion progressively raised arterial pH to 8.28 (control = 7.85) and plasma [HCO3-] to 20.8 mmol L(-1) (control = 4.5 mmol L(-1)) at 20 h, with unchanged arterial P(CO2), whereas NaCl/volume loading had no effect on blood acid-base status. Rectal gland Na+,K+-ATPase activity was increased 50% by NaCl loading and more than 100% by NaHCO3 loading, indicating stimulatory effects of both volume expansion and alkalosis. Rectal gland lactate dehydrogenase activity was elevated 25% by both treatments, indicating volume expansion effects only, whereas neither treatment increased the activities of the aerobic enzymes citrate synthase, NADP-isocitrate dehydrogenase, or the ketone body-utilizing enzyme beta-hydroxybutyrate dehydrogenase in the rectal gland or liver. The activity of ornithine-citrulline transcarbamoylase in skeletal muscle was doubled by NaHCO3 infusion, but neither treatment altered the activities of other OUC-related enzymes (glutamine synthetase, carbamoylphosphate synthetase III). We conclude that both the alkaline tide and salt loading/volume expansion act as signals to activate some but not all of the elevated metabolic pathways and ionoregulatory mechanisms needed during processing of a meal.

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

NASA Technical Reports Server (NTRS)

Baker, T. F.

1978-01-01

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

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

NASA Technical Reports Server (NTRS)

Estes, R. H.

1977-01-01

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

Tidal triggering of earthquakes in the Ning'er area of Yunnan Province, China

NASA Astrophysics Data System (ADS)

Xie, Chaodi; Lei, Xinglin; Zhao, Xiaoyan; Ma, Qingbo; Yang, Simeng; Wang, Yingnan

2017-05-01

To investigate the potential effect of tidal modulation on the seismicity in the Ning'er area, a seismically and geothermally active zone in Yunnan Province, China, we studied the correlation between Earth tides and the occurrence of M ≥ 6.0 earthquakes dating back to 1970, as well as their aftershock sequences, using theoretically calculated tidal stresses and a statistical test. The results show a significant correlation between Earth tides and the occurrence of earthquakes. Six of seven main events occurred when the Earth tide increased the Coulomb failure stress on the source fault. Four main events occurred in a narrow range of phase angle corresponding to the maximum loading rate of tidal stress. Furthermore, the histories of the aftershock sequence as a function of the tidal phases demonstrate clear tidal modulation with a high significance. Thus, we conclude that Earth tides have a clear role in triggering (or modulating) the rupture of the fault systems in the Ning'er area.

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

NASA Astrophysics Data System (ADS)

Marderwald, Eric; Richter, Andreas; Horwath, Martin; Hormaechea, Jose Luis; Groh, Andreas

2016-04-01

In Patagonia, the glacial-isostatic adjustment (GIA) to past ice-mass changes (Ivins & James 2004; Klemann et al. 2007) is of particular interest in the context of the determination of the complex regional rheology related to plate subduction in a triple-junction constellation. To further complicate the situation, GIA is overlaid with load deformation not only due to present ice mass changes but also due to water-level changes in the lakes surrounding the icefields and the ocean surrounding Patagonia. These elastic deformations affect the determination of glacial-isostatic uplift rates from GPS observations (Dietrich et al. 2010; Lange et al. 2014). Observations of lake tides and their comparison with the theoretical tidal signal have been used previously to validate predictions of ocean tidal loading and have revealed regional deviations from conventional global elastic earth models (Richter et al. 2009). In this work we investigate the tides and lake-level variations in Lago Argentino, Lago Viedma, Lago San Martín/O'Higgins and Lago Buenos Aires/General Carrera. This allows us to test, among other things, the validity of tidal loading models. We present pressure tide-gauge records from two sites in Lago Argentino extending over 2.5 years (Richter et al. 2015). These observations are complemented by lake-level records provided by the Argentine National Hydrometeorological Network. Based on these lake-level time series the principal processes affecting the lake level are identified and quantified. Lake-level changes reflecting variations in lake volume are dominated by a seasonal cycle exceeding 1 m in amplitude. Lake-volume changes occur in addition with a daily period in response to melt water influx from surrounding glaciers. In Lago Argentino sporadic lake-volume jumps are caused by bursting of the ice dam of Perito Moreno glacier. Water movements in these lakes are dominated by surface seiches reaching 20 cm in amplitude. A harmonic tidal analysis of the lake-level time series from Lagos Argentino and Viedma yields the amplitudes and phases of the lake tides for the four major tidal constituents M2, S2, O1 and K1. The maximum amplitude, corresponding to the semi-diurnal moon tide M2 in Lago Argentino, amounts to 3 mm. For the four lakes under investigation the theoretical amplitudes and phases of seven constituents (Q1, O1, P1, K1, N2, M2 and S2) are modelled accounting for the contributions of both the solid earth's body tides and the ocean tidal loading (Marderwald 2014). Both contributions involve a deformation of the earth surface and of the equipotential surfaces of the gravity field. For the load tide computation the global ocean tide model EOT11a (Savcenko and Bosch, 2012) and the Gutenberg-Bullen A earth model (Farrell, 1972) was applied and the conservation of water volume is taken into account. The comparison of the tidal signal extracted from the lake-level observations in Lagos Argentino and Viedma with the lake tide models indicates a phase shift which is most likely explained by an 1 hour phase lag of the employed global ocean tide model in the region of the highly fragmented Pacific coast. REFERENCES: Farrell, W. E., (1972). Deformation of the Earth by Surface Loads. Rev. Geophy. Space Phy., 10(3):761-797. Ivins, E., James, T., 2004. Bedrock response to Llanquihue Holocene and present-day glaciation in southernmost South America. Geophys. Res. Lett. 31 (L24613). Doi:10.1029/2004GL021500. Klemann, V., E. R. Ivins, Z. Martinec, and D. Wolf (2007), Models of active glacial isostasy roofing warm subduction: Case of the South Patagonian Ice Field, J. Geophys. Res., 112, B09405, doi: 10.1029/2006JB004818. Lange, H., Casassa, G., Ivins, E. R., Schröder, L., Fritsche, M., Richter, A., Groh, A., Dietrich, R., (2014). Observed crustal uplift near the Southern Patagonian Icefield constrains improved viscoelastic Earth models. Geophysical Research Letters, DOI: 10.1002/2013GL058419. Marderwald ER, 2014. Modelado de las mareas de grandes lagos patagónicos. Licenciatura thesis, Universidad Nacional de La Plata, Argentina. Richter, A., Marderwald, E., Hormaechea, J.L., Mendoza, L., Perdomo, R., Connon, G., Scheinert, M., Horwath, M., Dietrich, R. (2015): Lake-level variations and tides in Lago Argentino, Patagonia: insights from pressure tide gauge records. Journal of Limnology (accepted), doi:10.4081/jlimnol.2015.1189. Richter A, Hormaechea JL, Dietrich R, Perdomo R, Fritsche M, Del Cogliano D, Liebsch G, Mendoza L, 2009. Anomalous ocean load tide signal observed in lake-level variations in Tierra del Fuego. Geophys. Res. Lett. 36:L05305. Savcenko, R., and W. Bosch (2012), EOT11a - Empirical Ocean Tide Model from Multi-Mission Satellite Altimetry. Deutsches Geodätisches Forschungsinstitut (DGFI), Munich, Report Number 89.

Ocean tides for satellite geodesy

NASA Technical Reports Server (NTRS)

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.

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

NASA Technical Reports Server (NTRS)

Wahr, John

1993-01-01

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

Tides at the east coast of Lanzarote Island

NASA Astrophysics Data System (ADS)

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

2012-04-01

The main goal of this work is the study of the ocean tides at the east coast of Lanzarote (Canary Islands). We have analyzed time series of tide gauge and bottom pressure observations available in the region and we have made a further comparative validation with recent global and local ocean tide models. Lanzarote island shows singular features, with regard its volcanic structure and geomorphological properties and, also, concerning the characteristics of the ocean tides in the surrounding waters. For this reason, this region experiences a great interest in Geodesy and Geodynamics. Particularly, an accurate modelization of the ocean tides is of great importance to correct with high accuracy the effect of the ocean over the multiple geodetic measurements that are being carried out in the Geodynamic Laboratory of Lanzarote, LGL (Vieira et al., 1991; 2006). Furthermore, the analysis of tide gauge and bottom pressure records in this area is of great importance to investigate sea level variations, to evaluate and quantify the causes of these changes and the possible correlation with vertical movements of the Earth's crust. The time series of sea level and bottom pressure data considered in this work are obtained at two different locations of the island and, in each of them, using several sensors at different periods of time. First location is Jameos del Agua (JA) station, which belongs to the LGL. This station is placed in the open ocean, 200 meters distant from the northeastern coast of the island and at 8 meters depth. The observations have been carried out using 3 bottom pressure sensors (Aanderaa WLR7, SAIV TD301A and Aqualogger 210PT) at different periods of time (spanning a total of six years). Second location is Arrecife (AR) station, which is 23 km south of JA station. In this case, the sea level data come from a float tide gauge belonging to the Instituto Español de Oceanografía, installed at the beginning of the loading bay, and a radar tide gauge from the REDMAR network of Puertos del Estado placed at the end of the same loading bay. Results obtained from the time series analysis at both locations, amplitude and phase of the main diurnal and semi-diurnal tidal waves, are compared with the most recent global ocean tide models, as TPXO7.2, EOT11a, HAMTIDE, FES2004, GOT4.7 and AG2006, and also with the high resolution regional ocean tide model for the Canaries CIAM2 (Arnoso et al., 2006, Benavent, 2011). Comparison of simulated harmonic constant (from global and local ocean tide model) with those obtained from tidal stations is done by means of the direct comparison between amplitudes and phase for each tidal wave and the root mean square (rms) of the differences in the complex plane. Finally the root sum square (rss) of residuals over all harmonic constituents considered is calculated.

M2, S2, K1 models of the global ocean tide

NASA Technical Reports Server (NTRS)

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

1979-01-01

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

Tilt observations using borehole tiltmeters: 2. Analysis of data from Yellowstone National Park

NASA Astrophysics Data System (ADS)

Meertens, Charles; Levine, Judah; Busby, Robert

1989-01-01

We have installed borehole tiltmeters at five sites in Yellowstone National Park, Wyoming, and have used these instruments to measure the spatial variation of the amplitude and phase of the principal semidiurnal tide. The measured tides vary both with position and azimuth and differ from the sum of the body tide and the ocean load by up to 50%. The difference predicted by a finite element model constructed from seismic, refraction, and gravity data has a maximum value of only 12%, although the discrepancy between our observations and the model is only marginally significant at some sites. The disagreement between the model and our observations is much larger than we observed using the same instruments at other sites and cannot be attributed to an instrumental effect. We have been unable to modify the model to explain our results while keeping it consistent with the previous observations.

Review: Moisture loading—the hidden information in groundwater observation well records

NASA Astrophysics Data System (ADS)

van der Kamp, Garth; Schmidt, Randy

2017-12-01

Changes of total moisture mass above an aquifer such as snow accumulation, soil moisture, and storage at the water table, represent changes of mechanical load acting on the aquifer. The resulting moisture-loading effects occur in all observation well records for confined aquifers. Deep observation wells therefore act as large-scale geological weighing lysimeters, referred to as "geolysimeters". Barometric pressure effects on groundwater levels are a similar response to surface loading and are familiar to every hydrogeologist dealing with the "barometric efficiency" of observation wells. Moisture-loading effects are small and generally not recognized because they are obscured by hydraulic head fluctuations due to other causes, primarily barometric pressure changes. For semiconfined aquifers, long-term moisture-loading effects may be dissipated and obscured by transient flow through overlying aquitards. Removal of barometric and earth tide effects from observation well records allows identification of moisture loading and comparison with hydrological observations, and also comparison with the results of numerical models that can account for transient groundwater flow.

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

NASA Astrophysics Data System (ADS)

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 not observed at low tide) presumably also are deposited on the up estuary side during flooding tides but these deposits are destroyed by ebb flows. The implication of these sediment transport processes on the stratification of the bedforms is considered.

The Global S$_1$ Ocean Tide

NASA Technical Reports Server (NTRS)

Ray, Richard D.; Egbert, G. D.

2003-01-01

The small S$_1$ ocean tide is caused primarily by diurnal atmospheric pressure loading. Its excitation is therefore unlike any other diurnal tide. The global character of $S-1$ is here determined by numerical modeling and by analysis of Topex/Poseidon satellite altimeter data. The two approaches yield reasonably consistent results, and large ( $ greater than $l\\cm) amplitudes in several regions are further confirmed by comparison with coastal tide gauges. Notwithstanding their excitation differences, S$-1$ and other diurnal tides are found to share several common features, such as relatively large amplitudes in the Arabian Sea, the Sea of Okhotsk, and the Gulf of Alaska. The most noticeable difference is the lack of an S$-1$ Antarctic Kelvin wave. These similarities and differences can be explained in terms of the coherences between near-diurnal oceanic normal modes and the underlying tidal forcings. While gravitational diurnal tidal forces excite primarily a 28-hour Antarctic-Pacific mode, the S$_1$ air tide excites several other near-diurnal modes, none of which has large amplitudes near Antarctica.

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

USGS Publications Warehouse

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

2003-01-01

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

Submarine groundwater discharge and nutrient loadings in Tolo Harbor, Hong Kong using multiple geotracer-based models, and their implications of red tide outbreaks.

PubMed

Luo, Xin; Jiao, Jiu Jimmy

2016-10-01

Multiple tracers, including radium quartet, (222)Rn and silica are used to quantify submarine groundwater discharge (SGD) into Tolo Harbor, Hong Kong in 2005 and 2011. Five geotracer models based on the end member model of (228)Ra and salinity and mass balance models of (226)Ra, (228)Ra, (222)Rn, and silica were established and all the models lead to an estimate of the SGD rate of the same order of magnitude. In 2005 and 2011, respectively, the averaged SGD based on these models is estimated to be ≈ 5.42 cm d(-1) and ≈2.66 cm d(-1), the SGD derived DIN loadings to be 3.5 × 10(5) mol d(-1) and 1.5 × 10(5) mol d(-1), and DIP loadings to be 6.2 × 10(3) mol d(-1) and 1.1 × 10(3) mol d(-1). Groundwater borne nutrients are 1-2 orders of magnitude larger than other nutrient sources and the interannual variation of nutrient concentration in the embayment is more influenced by the SGD derived loadings. Annual DIP concentrations in the harbor water is positively correlated with the precipitation and annual mean tidal range, and negatively correlated with evapotranspiration from 2000 to 2013. Climatologically driven SGD variability alters the SGD derived DIP loadings in this phosphate limited environment and may be the causative factor of interannual variability of red tide outbreaks from 2000 to 2013. Finally, a conceptual model is proposed to characterize the response of red tide outbreaks to climatological factors linked by SGD. The findings from this study shed light on the prediction of red tide outbreaks and coastal management of Tolo Harbor and similar coastal embayments elsewhere. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

NASA Astrophysics Data System (ADS)

Cutillo, P. A.; Ge, S.

2004-12-01

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

Modelling Suspended Sediment Transport in Monsoon Season: A Case Study of Pahang River Estuary, Pahang, Malaysia

NASA Astrophysics Data System (ADS)

Zakariya, Razak; Ahmad, Zuhairi; Saad, Shahbudin; Yaakop, Rosnan

2013-04-01

Sediment transport based on 2-dimensional real time model was applied to Pahang River estuary, Pahang, Malaysia and has been evaluated and verified with time series of tidal elevation, flow and suspended sediment load. Period of modelling was during highest high tide and lowest low tide in Northeast Monsoon (NE) which happened in December 2010 and Southwest Monsoon (SW) in July 2011. Simulated model outputs has been verify using Pearson's coefficient and has showed high accuracy. The validated model was used to simulate hydrodynamic and sediment transport of extreme conditions during both monsoon seasons. Based on field measurement and model simulation, tidal elevation and flow velocity, freshwater discharge of Pahang River were found to be higher during NE Monsoon. Based on the fluxes, the estuary also showed 'ebb-dominant' characteristic during highest high tide and lowest low tide in NE monsoon and normal ebbing-flooding characteristics during SW monsoon. In the Pahang River estuary, inflow and outflow patterns were perpendicular to the open boundary with circular flow formed at the shallow area in the middle of estuary during both monsoons. Referring to sea water intrusion from the river mouth, both seasons show penetration of more than 9 km (upstream input boundary) during higher high water tide. During higher lower water tide, the water intrusion stated varies which 5.6km during NE monsoon and 7.8km during SW monsoon. Regarding to the times lap during high tide, the sea water takes 2.8 hours to reach 9km upstream during NE monsoon compared to 1.9 hour during SW monsoon. The averages of suspended sediment concentration and suspended sediment load were higher during Northeast monsoon which increased the sedimentation potentials.Total of suspended sediment load discharged to the South China Sea yearly from Pahang River is approximately 96727.5 tonnes/day or 3.33 tonnes/km2/day which 442.6 tonnes/day during Northeast Monsoon and 25.3 tonnes/day during Southwest Monsoon. Thus, Pahang River estuary found to be directly affected by the monsoon factors especially due to high amount of river discharge and surface erosion from catchment areas. This study provides several useful understanding on the hydrodynamic and sediment transport of Pahang River estuary and catchment area. Keywords: Pahang River Estuary, hydrodynamic, sediment transport, MIKE21 MT

Ocean dynamics during the passage of Xynthia storm recorded by GPS

NASA Astrophysics Data System (ADS)

Nicolas, Joëlle; Ferenc, Marcell; Li, Zhao; van Dam, Tonie; Polidori, Laurent

2014-05-01

When computing the effect of atmospheric loading on geodetic coordinates, we must assign the response of the ocean to pressure loading. A pure inverted barometer and a solid Earth ocean response to pressure loading define the extremes of the response. At periods longer than a few days, the inverted barometer response is sufficient (Wunsch and Stammer, 1997). However, how does the ocean respond to fast moving storms? In this study we investigate the effect of a violent storm that progressed over Western Europe between the 27th of February and the 1st of March 2010 on sub-daily vertical GPS (Global Positioning System) position time series of the French GNSS permanent network (RGP). Xynthia was a huge low-pressure system (pressure drop of 40 mbar and a storm surge of 1.4 m (at La Rochelle tide gauge)) that crossed France from the southwest to the northeast over the course of about 20 hours. We study the different behaviour of the coastal and inland sites based on the comparison of the estimated 6-hourly stand-alone GPS position time series (GINS-PC software) with the local pressure and the predicted atmospheric pressure loading time series derived from the high resolution Modern-Era Retrospective Analysis for Research and Applications (NASA MERRA) and also the European Centre for Medium-Range Weather Forecasts (ECMWF) global dataset. We model the predicted displacements using the inverse barometer (IB) and the non-IB ocean response cases as endpoints. Predicted loading effects due to the atmospheric pressure and IB ocean reach up to 1.0, 1.3 and 13.7 mm for the east, north and up components, respectively. Then we attempt to use the GPS vertical surface displacements, the surface pressure, and tide gauge data (SONEL) to identify the true ocean dynamics on the continental shelf during the passage of this fast moving system. Keywords: GPS, GINS-PC, Xynthia, ocean dynamics, atmospheric pressure loading, deformation

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

NASA Technical Reports Server (NTRS)

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.

River delta network hydraulic residence time distributions and their role in coastal nutrient biogeochemistry

NASA Astrophysics Data System (ADS)

Hiatt, M. R.; Castaneda, E.; Twilley, R.; Hodges, B. R.; Passalacqua, P.

2015-12-01

River deltas have the potential to mitigate increased nutrient loading to coastal waters by acting as biofilters that reduce the impact of nutrient enrichment on downstream ecosystems. Hydraulic residence time (HRT) is known to be a major control on biogeochemical processes and deltaic floodplains are hypothesized to have relatively long HRTs. Hydrological connectivity and delta floodplain inundation induced by riverine forces, tides, and winds likely alter surface water flow patterns and HRTs. Since deltaic floodplains are important elements of delta networks and receive significant fluxes of water, sediment, and nutrients from distributary channels, biogeochemical transformations occurring within these zones could significantly reduce nutrient loading to coastal receiving waters. However, network-scale estimates of HRT in river deltas are lacking and little is known about the effects of tides, wind, and the riverine input on the HRT distribution. Subsequently, there lacks a benchmark for evaluating the impact of engineered river diversions on coastal nutrient ecology. In this study, we estimate the HRT of a coastal river delta by using hydrodynamic modeling supported by field data and relate the HRT to spatial and temporal patterns in nitrate levels measured at discrete stations inside a delta island at Wax Lake Delta. We highlight the control of the degree of hydrological connectivity between distributary channels and interdistributary islands on the network HRT distribution and address the roles of tides and wind on altering the shape of the distribution. We compare the observed nitrate concentrations to patterns of channel-floodplain hydrological connectivity and find this connectivity to play a significant role in the nutrient removal. Our results provide insight into the potential role of deltaic wetlands in reducing the nutrient loading to near-shore waters in response to large-scale river diversions.

[Applications of three-dimensional fluorescence spectrum of dissolved organic matter to identification of red tide algae].

PubMed

Lü, Gui-Cai; Zhao, Wei-Hong; Wang, Jiang-Tao

2011-01-01

The identification techniques for 10 species of red tide algae often found in the coastal areas of China were developed by combining the three-dimensional fluorescence spectra of fluorescence dissolved organic matter (FDOM) from the cultured red tide algae with principal component analysis. Based on the results of principal component analysis, the first principal component loading spectrum of three-dimensional fluorescence spectrum was chosen as the identification characteristic spectrum for red tide algae, and the phytoplankton fluorescence characteristic spectrum band was established. Then the 10 algae species were tested using Bayesian discriminant analysis with a correct identification rate of more than 92% for Pyrrophyta on the level of species, and that of more than 75% for Bacillariophyta on the level of genus in which the correct identification rates were more than 90% for the phaeodactylum and chaetoceros. The results showed that the identification techniques for 10 species of red tide algae based on the three-dimensional fluorescence spectra of FDOM from the cultured red tide algae and principal component analysis could work well.

Global estimation of ocean tides in deep and shallow waters from TOPEX/POSEIDON and numerical models with applications to geophysics, oceanography, and precision altimetry

NASA Astrophysics Data System (ADS)

Tierney, Craig Cristy

Presented here are several investigations of ocean tides derived from TOPEX/POSEIDON (T/P) altimetry and numerical models. The purpose of these investigations is to study the short wavelength features in the T/P data and to preserve these wavelengths in global ocean tide models that are accurate in shallow and deep waters. With these new estimates, effects of the tides on loading, Earth's rotation, and tidal energetics are studied. To preserve tidal structure, tides have been estimated along the ground track of T/P by the harmonic and response methods using 4.5 years of data. Results show the two along-track (AT) estimates agree with each other and with other tide models for those components with minimal aliasing problems. Comparisons to global models show that there is tidal structure in the T/P data that is not preserved with current gridding methods. Error estimates suggest there is accurate information in the T/P data from shallow waters that can be used to improve tidal models. It has been shown by Ray and Mitchum (1996) that the first mode baroclinic tide can be separated from AT tide estimates by filtering. This method has been used to estimate the first mode semidiurnal baroclinic tides globally. Estimates for M2 show good correlation with known regions of baroclinic tide generation. Using gridded, filtered AT estimates, a lower bound on the energy contained in the M2 baroclinic tide is 50 PJ. Inspired by the structure found in the AT estimates, a gridding method is presented that preserves tidal structure in the T/P data. These estimates are assimilated into a nonlinear, finite difference, global barotropic tidal model. Results from the 8 major tidal constituents show the model performs equivalently to other models in the deep waters, and is significantly better in the shallow waters. Crossover variance is reduced from 14 cm to 10 cm in the shallow waters. Comparisons to Earth rotation show good agreement to results from VLBI data. Tidal energetics computed from the models show good agreement with previous results. PE/KE ratios and quality factors are more consistent in each frequency band than in previous results.

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

NASA Astrophysics Data System (ADS)

Abdulkade, A.

2015-12-01

Cobble bedforms, c. 1m high with lengths of several metres and 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 not observed at low tide) presumably also are deposited on the up estuary side during flooding tides but these deposits are destroyed by ebb flows. The implication of these sediment transport processes on the stratification of the bedforms is considered.

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

NASA Astrophysics Data System (ADS)

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.

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

NASA Astrophysics Data System (ADS)

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.

Utilizing the algicidal activity of aminoclay as a practical treatment for toxic red tides

PubMed Central

Lee, Young-Chul; Jin, EonSeon; Jung, Seung Won; Kim, Yeon-Mi; Chang, Kwang Suk; Yang, Ji-Won; Kim, Si-Wouk; Kim, Young-Ok; Shin, Hyun-Jae

2013-01-01

In recent decades, harmful algal blooms (HABs) – commonly known as red tides – have increasingly impacted human health, caused significant economic losses to fisheries and damaged coastal environments and ecosystems. Here, we demonstrate a method to control and suppress HABs through selective algal lysis. The approach harnesses the algicidal effects of aminoclays, which are comprised of a high density of primary amine groups covalently bonded by metal cation backbones. Positively charged colloidals of aminoclays induce cell lysis in HABs within several minutes exposure but have negligible impact on non-harmful phytoplankton, zooplankton and farmed fish. This selective lysis is due to the ammonium characteristics of the aminoclay and the electrostatic attraction between the clay nanoparticles and the algal cells. In contrast, yellow loess clay, a recognized treatment for HABs, causes algal flocs with little cell lysis. Thus, the aminoclay loading can be effective for the mitigation of HABs. PMID:23416422

Utilizing the algicidal activity of aminoclay as a practical treatment for toxic red tides.

PubMed

Lee, Young-Chul; Jin, EonSeon; Jung, Seung Won; Kim, Yeon-Mi; Chang, Kwang Suk; Yang, Ji-Won; Kim, Si-Wouk; Kim, Young-Ok; Shin, Hyun-Jae

2013-01-01

In recent decades, harmful algal blooms (HABs) - commonly known as red tides - have increasingly impacted human health, caused significant economic losses to fisheries and damaged coastal environments and ecosystems. Here, we demonstrate a method to control and suppress HABs through selective algal lysis. The approach harnesses the algicidal effects of aminoclays, which are comprised of a high density of primary amine groups covalently bonded by metal cation backbones. Positively charged colloidals of aminoclays induce cell lysis in HABs within several minutes exposure but have negligible impact on non-harmful phytoplankton, zooplankton and farmed fish. This selective lysis is due to the ammonium characteristics of the aminoclay and the electrostatic attraction between the clay nanoparticles and the algal cells. In contrast, yellow loess clay, a recognized treatment for HABs, causes algal flocs with little cell lysis. Thus, the aminoclay loading can be effective for the mitigation of HABs.

Premonitory slip and tidal triggering of earthquakes

USGS Publications Warehouse

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

1999-01-01

We have conducted a series of laboratory simulations of earthquakes using granite cylinders containing precut bare fault surfaces at 50 MPa confining pressure. Axial shortening rates between 10-4 and 10-6 mm/s were imposed to simulate tectonic loading. Average loading rate was then modulated by the addition of a small-amplitude sine wave to simulate periodic loading due to Earth tides or other sources. The period of the modulating signal ranged from 10 to 10,000 s. For each combination of amplitude and period of the modulating signal, multiple stick-slip events were recorded to determine the degree of correlation between the timing of simulated earthquakes and the imposed periodic loading function. Over the range of parameters studied, the degree of correlation of earthquakes was most sensitive to the amplitude of the periodic loading, with weaker dependence on the period of oscillations and the average loading rate. Accelerating premonitory slip was observed in these experiments and is a controlling factor in determining the conditions under which correlated events occur. In fact, some form of delayed failure is necessary to produce the observed correlations between simulated earthquake timing and characteristics of the periodic loading function. The transition from strongly correlated to weakly correlated model earthquake populations occurred when the amplitude of the periodic loading was approximately 0.05 to 0.1 MPa shear stress (0.03 to 0.06 MPa Coulomb failure function). Lower-amplitude oscillations produced progressively lower correlation levels. Correlations between static stress increases and earthquake aftershocks are found to degrade at similar stress levels. Typical stress variations due to Earth tides are only 0.001 to 0.004 MPa, so that the lack of correlation between Earth tides and earthquakes is also consistent with our findings. A simple extrapolation of our results suggests that approximately 1% of midcrustal earthquakes should be correlated with Earth tides. Triggered seismicity has been reported resulting from the passage of surface waves excited by the Landers earthquake. These transient waves had measured amplitudes in excess of 0.1 MPa at frequencies of 0.05 to 0.2 Hz in regions of notable seismicity increase. Similar stress oscillations in our laboratory experiments produced strongly correlated stick-slip events. We suggest that seemingly inconsistent natural observations of triggered seismicity and absence of tidal triggering indicate that failure is amplitude and frequency dependent. This is the expected result if, as in our laboratory experiments, the rheology of the Earth's crust permits delayed failure.

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

USGS Publications Warehouse

Merritt, Michael L.

2004-01-01

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

A dinoflagellate Cochlodinium geminatum bloom in the Zhujiang (Pearl) River estuary in autumn 2009

NASA Astrophysics Data System (ADS)

Ke, Zhixin; Huang, Liangmin; Tan, Yehui; Song, Xingyu

2012-05-01

A severe Cochlodinium geminatum red tide (>300 km2) was observed in the Zhujiang (Pearl) River estuary, South China Sea in autumn 2009. We evaluated the environmental conditions and phytoplankton community structure during the outbreak. The red tide water mass had significantly higher dissolved inorganic phosphate (DIP), ammonia, and temperature, but significantly lower nitrite, nitrate, dissolved inorganic nitrogen (DIN), and DIN/DIP relative to the non-red-tide zones. The phytoplankton assemblage was dominated by dinoflagellates and diatoms during the red tide. C. geminatum was the most abundant species, with a peak density of 4.13×107 cell/L, accounting for >65% of the total phytoplankton density. The DIN/DIP ratio was the most important predictor of species, accounting for 12.45% of the total variation in the phytoplankton community. Heavy phosphorus loading, low precipitation, and severe saline intrusion were likely responsible for the bloom of C. geminatum.

Influence of Tidal Forces on the Triggering of Seismic Events

NASA Astrophysics Data System (ADS)

Varga, Péter; Grafarend, Erik

2018-05-01

Tidal stresses are generated in any three-dimensional body influenced by an external inhomogeneous gravity field of rotating planets or moons. In this paper, as a special case, stresses caused within the solid Earth by the body tides are discussed from viewpoint of their influence on seismic activity. The earthquake triggering effects of the Moon and Sun are usually investigated by statistical comparison of tidal variations and temporal distribution of earthquake activity, or with the use of mathematical or experimental modelling of physical processes in earthquake prone structures. In this study, the magnitude of the lunisolar stress tensor in terms of its components along the latitude of the spherical surface of the Earth as well as inside the Earth (up to the core-mantle boundary) were calculated for the PREM (Dziewonski and Anderson in Phys Earth Planet Inter 25(4):297-356, 1981). Results of calculations prove that stress increases as a function of depth reaching a value around some kPa at the depth of 900-1500 km, well below the zone of deep earthquakes. At the depth of the overwhelming part of seismic energy accumulation (around 50 km) the stresses of lunisolar origin are only (0.0-1.0)·103 Pa. Despite the fact that these values are much smaller than the earthquake stress drops (1-30 MPa) (Kanamori in Annu Rev Earth Planet Sci 22:207-237, 1994) this does not exclude the possibility of an impact of tidal forces on outbreak of seismic events. Since the tidal potential and its derivatives are coordinate dependent and the zonal, tesseral and sectorial tides have different distributions from the surface down to the CMB, the lunisolar stress cannot influence the break-out of every seismological event in the same degree. The influencing lunisolar effect of the solid earth tides on earthquake occurrences is connected first of all with stress components acting parallel to the surface of the Earth. The influence of load tides is limited to the loaded area and its immediate vicinity.

Influence of Tidal Forces on the Triggering of Seismic Events

NASA Astrophysics Data System (ADS)

Varga, Péter; Grafarend, Erik

2017-05-01

Tidal stresses are generated in any three-dimensional body influenced by an external inhomogeneous gravity field of rotating planets or moons. In this paper, as a special case, stresses caused within the solid Earth by the body tides are discussed from viewpoint of their influence on seismic activity. The earthquake triggering effects of the Moon and Sun are usually investigated by statistical comparison of tidal variations and temporal distribution of earthquake activity, or with the use of mathematical or experimental modelling of physical processes in earthquake prone structures. In this study, the magnitude of the lunisolar stress tensor in terms of its components along the latitude of the spherical surface of the Earth as well as inside the Earth (up to the core-mantle boundary) were calculated for the PREM (Dziewonski and Anderson in Phys Earth Planet Inter 25(4):297-356, 1981). Results of calculations prove that stress increases as a function of depth reaching a value around some kPa at the depth of 900-1500 km, well below the zone of deep earthquakes. At the depth of the overwhelming part of seismic energy accumulation (around 50 km) the stresses of lunisolar origin are only (0.0-1.0)·103 Pa. Despite the fact that these values are much smaller than the earthquake stress drops (1-30 MPa) (Kanamori in Annu Rev Earth Planet Sci 22:207-237, 1994) this does not exclude the possibility of an impact of tidal forces on outbreak of seismic events. Since the tidal potential and its derivatives are coordinate dependent and the zonal, tesseral and sectorial tides have different distributions from the surface down to the CMB, the lunisolar stress cannot influence the break-out of every seismological event in the same degree. The influencing lunisolar effect of the solid earth tides on earthquake occurrences is connected first of all with stress components acting parallel to the surface of the Earth. The influence of load tides is limited to the loaded area and its immediate vicinity.

Is earthquake rate in south Iceland modified by seasonal loading?

NASA Astrophysics Data System (ADS)

Jonsson, S.; Aoki, Y.; Drouin, V.

2017-12-01

Several temporarily varying processes have the potential of modifying the rate of earthquakes in the south Iceland seismic zone, one of the two most active seismic zones in Iceland. These include solid earth tides, seasonal meteorological effects and influence from passing weather systems, and variations in snow and glacier loads. In this study we investigate the influence these processes may have on crustal stresses and stressing rates in the seismic zone and assess whether they appear to be influencing the earthquake rate. While historical earthquakes in the south Iceland have preferentially occurred in early summer, this tendency is less clear for small earthquakes. The local earthquake catalogue (going back to 1991, magnitude of completeness < 1.0) has indeed more earthquakes in summer than in winter. However, this pattern is strongly influenced by aftershock sequences of the largest M6+ earthquakes, which occurred in June 2000 and May 2008. Standard Reasenberg earthquake declustering or more involved model independent stochastic declustering algorithms are not capable of fully eliminating the aftershocks from the catalogue. We therefore inspected the catalogue for the time period before 2000 and it shows limited seasonal tendency in earthquake occurrence. Our preliminary results show no clear correlation between earthquake rates and short-term stressing variations induced from solid earth tides or passing storms. Seasonal meteorological effects also appear to be too small to influence the earthquake activity. Snow and glacier load variations induce significant vertical motions in the area with peak loading occurring in Spring (April-May) and maximum unloading in Fall (Sept.-Oct.). Early summer occurrence of historical earthquakes therefore correlates with early unloading rather than with the peak unloading or unloading rate, which appears to indicate limited influence of this seasonal process on the earthquake activity.

A finite element model for tides and resonance along the north coast of British Columbia

NASA Astrophysics Data System (ADS)

Foreman, M. G. G.; Henry, R. F.; Walters, R. A.; Ballantyne, V. A.

1993-02-01

A finite element, barotropic, tidal model is developed for the north coast of British Columbia. The model is run with eight tidal constituents and the results are compared with the Flather (1987) finite difference model, and with extensive tide gauge and current meter observations. Although the tidal potential, Earth tide, and loading tide are included in the forcing, their inclusion is shown to change the largest M2 amplitudes by only 2.5% and the largest K1 amplitudes by less than 1%. Root mean square differences between observed and calculated sea level amplitudes and phases are within 1.9 cm and 2.9° for all but one constituent, but the model currents do not in general, compare as favourably. The barotropic currents observed in Hecate Strait are reproduced well, but elsewhere evidence is shown that model inaccuracies are due to baroclinic effects. Tidal residual currents calculated by the model suggest the existence of eddies off the tip of Cape St. James, Cape Chacon, and around Goose Island and Learmonth Banks. The shallow water constituents in Hecate Strait are shown to have significant contributions from the constructive interference of signals propagating into Dixon Entrance and Queen Charlotte Sound. Using the model, the longest resonant period of the system is estimated to be 7.6 hours with an energy dissipation parameter, Q, of 9.5.

Nucleation and triggering of earthquake slip: effect of periodic stresses

USGS Publications Warehouse

Dieterich, J.H.

1987-01-01

Results of stability analyses for spring and slider systems, with state variable constitutive properties, are applied to slip on embedded fault patches. Unstable slip may nucleate only if the slipping patch exceeds some minimum size. Subsequent to the onset of instability the earthquake slip may propagate well beyond the patch. It is proposed that the seismicity of a volume of the earth's crust is determined by the distribution of initial conditions on the population of fault patches that nucleate earthquake slip, and the loading history acting upon the volume. Patches with constitutive properties inferred from laboratory experiments are characterized by an interval of self-driven accelerating slip prior to instability, if initial stress exceeds a minimum threshold. This delayed instability of the patches provides an explanation for the occurrence of aftershocks and foreshocks including decay of earthquake rates by time-1. A population of patches subjected to loading with a periodic component results in periodic variation of the rate of occurrence of instabilities. The change of the rate of seismicity for a sinusoidal load is proportional to the amplitude of the periodic stress component and inversely proportional to both the normal stress acting on the fault patches and the constitutive parameter, A1, that controls the direct velocity dependence of fault slip. Values of A1 representative of laboratory experiments indicate that in a homogeneous crust, correlation of earthquake rates with earth tides should not be detectable at normal stresses in excess of about 8 MPa. Correlation of earthquakes with tides at higher normal stresses can be explained if there exist inhomogeneities that locally amplify the magnitude of the tidal stresses. Such amplification might occur near magma chambers or other soft inclusions in the crust and possibly near the ends of creeping fault segments if the creep or afterslip rates vary in response to tides. Observations of seismicity rate variations associated with seasonal fluctuations of reservoir levels appear to be consistent with the model. ?? 1987.

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

NASA Astrophysics Data System (ADS)

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

2012-09-01

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

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

NASA Technical Reports Server (NTRS)

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.

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

NASA Astrophysics Data System (ADS)

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.

Strainmeters and tiltmeters in geophysics

NASA Technical Reports Server (NTRS)

Goulty, N. R.

1976-01-01

Several types of sensitive strainmeters and tiltmeters have been developed, and it is now becoming clear which geophysical applications are most suitable for these instruments. In general, strainmeters and tiltmeters are used for observing ground deformation at periods of minutes to days. Small-scale lateral inhomogeneities at the instrument sites distort signals by a few percent, although the effects of large structures can be calculated. In earth tide work these lateral inhomogeneities and unknown ocean loading signals prevent accurate values of the regional tide from being obtained. This limits tidal investigations to looking for temporal variations, possibly associated with pre-earthquake dilatancy, and spatial variations caused by gross elasticity contrasts in the local geological structure. Strainmeters and tiltmeters are well suited for observing long-period seismic waves, seismic slip events on faults and volcano tumescence, where small site-induced distortions in the measured signals are seldom important.

An objective frequency domain method for subsurface characterisation using Earth and atmospheric tides

NASA Astrophysics Data System (ADS)

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.

Insights into aquifer vulnerability and potential recharge zones from the borehole response to barometric pressure changes

NASA Astrophysics Data System (ADS)

El Araby, Mahmoud; Odling, Noelle; Clark, Roger; West, Jared

2010-05-01

Borehole water levels fluctuate in response to deformation of the surrounding aquifer caused by surface loading due to barometric pressure or strain caused by Earth and ocean tides. The magnitude and nature of this response mainly depend on the hydraulic properties of the aquifer and overlying units and borehole design. Thus water level responses reflect the effectiveness of a confining unit as a protective layer against aquifer contamination (and therefore groundwater vulnerability) and to potential aquifer recharge/discharge zones. In this study, time series of borehole water levels and barometric pressure are being investigated using time series analysis and signal processing techniques with the aim of developing a methodology for assessing recharge/discharge distribution and groundwater vulnerability in the confined/semi-confined part of the Chalk aquifer in East Yorkshire, UK. The chalk aquifer in East Yorkshire is an important source for industrial and domestic water supply. The aquifer water quality is threatened by surface pollution particularly by nitrates from agricultural fertilizers. The confined/semi-confined part of this aquifer is covered by various types of superficial deposits resulting in a wide range of the aquifer's degree of confinement. A number of boreholes have been selected for monitoring to cover all these various types of confining units. Automatic pressure transducers are installed to record water levels and barometric pressure measurements at each borehole on 15 minutes recording intervals. In strictly confined aquifers, borehole water level response to barometric pressure is an un-drained instantaneous response and is a constant fraction of the barometric pressure changes. This static confined constant is called the barometric efficiency which can be estimated simply by the slope of a regression plot of water levels versus barometric pressure. However, in the semi confined aquifer case this response is lagged due to water movement between the aquifer and the confining layer. In this case the static constant barometric efficiency is not applicable and the response is represented by a barometric response function which reflects the timing and frequency of the barometric pressure loading. In this study, the barometric response function is estimated using de-convolution techniques both in the time domain (least squares regression de-convolution) and in the frequency domain (discrete Fourier transform de-convolution). In order to estimate the barometric response function, borehole water level fluctuations due to factors other than barometric pressure should be removed (de-trended) as otherwise they will mask the response relation of interest. It is shown from the collected borehole data records that the main four factors other than barometric pressure contribute to borehole water level fluctuations. These are the rainfall recharge, Earth tides, sea tides and pumping activities close to the borehole location. Due to the highly variable nature of the UK weather, rainfall recharge shows a wide variation throughout the winter and summer seasons. This gives a complicated recharge signal over a wide range of frequencies which must be de-trended from the borehole water level data in order to estimate the barometric response function. Methods for removing this recharge signal are developed and discussed. Earth tides are calculated theoretically at each borehole location taking into account oceanic loading effects. Ocean tide effects on water levels fluctuations are clear for the boreholes located close to the coast. A Matlab code has been designed to calculate and de-trend the periodic fluctuations in borehole water levels due to Earth and ocean tides using the least squares regression technique based on a sum of sine and cosine fitting model functions. The program results have been confirmed using spectral analysis techniques.

Dynamic ocean-tide effects on Earth's rotation

NASA Technical Reports Server (NTRS)

Dickman, S. R.

1993-01-01

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

1990-05-10

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

DELAWARE ESTUARY PCB MODEL

EPA Science Inventory

The Delaware River Basin Commission recently completed the first phase of a program to develop and implement Total Maximum Daily Loads (TMDLs) for toxic pollutants for the Delaware Estuary. This complex body of water extends from the head of tide at Trenton, NJ (River Mile 133.2...

Overview of aerosolized Florida red tide toxins: exposures and effects.

PubMed

Fleming, Lora E; Backer, Lorraine C; Baden, Daniel G

2005-05-01

Florida red tide is caused by Karenia brevis, a dinoflagellate that periodically blooms, releasing its potent neurotoxin, brevetoxin, into the surrounding waters and air along the coast of the Gulf of Mexico. Exposure to Florida red tide toxins has been associated with adverse human health effects and massive fish and marine mammal deaths. The articles in this mini-monograph describe the ongoing interdisciplinary and interagency research program that characterizes the exposures and health effects of aerosolized Florida red tide toxins (brevetoxins). The interdisciplinary research program uses animal models and laboratory studies to develop hypotheses and apply these findings to in situ human exposures. Our ultimate goal is to develop appropriate prevention measures and medical interventions to mitigate or prevent adverse health effects from exposure to complex mixtures of aerosolized red tide toxins.

Geodynamic Effects of Ocean Tides: Progress and Problems

NASA Technical Reports Server (NTRS)

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.

Optimal Operation of Variable Speed Pumping System in China's Eastern Route Project of S-to-N Water Diversion Project

NASA Astrophysics Data System (ADS)

Cheng, Jilin; Zhang, Lihua; Zhang, Rentian; Gong, Yi; Zhu, Honggeng; Deng, Dongsheng; Feng, Xuesong; Qiu, Jinxian

2010-06-01

A dynamic planning model for optimizing operation of variable speed pumping system, aiming at minimum power consumption, was proposed to achieve economic operation. The No. 4 Jiangdu Pumping Station, a source pumping station in China's Eastern Route of South-to-North Water Diversion Project, is taken as a study case. Since the sump water level of Jiangdu Pumping Station is affected by the tide of Yangtze River, the daily-average heads of the pumping system varies yearly from 3.8m to 7.8m and the tide level difference in one day up to 1.2m. Comparisons of operation electricity cost between optimized variable speed and fixed speed operations of pumping system were made. When the full load operation mode is adopted, whether or not electricity prices in peak-valley periods are considered, the benefits of variable speed operation cannot compensate the energy consumption of the VFD. And when the pumping system operates in part load and the peak-valley electricity prices are considered, the pumping system should cease operation or lower its rotational speed in peak load hours since the electricity price are much higher, and to the contrary the pumping system should raise its rotational speed in valley load hours to pump more water. The computed results show that if the pumping system operates in 80% or 60% loads, the energy consumption cost of specified volume of water will save 14.01% and 26.69% averagely by means of optimal variable speed operation, and the investment on VFD will be paid back in 2 or 3 years. However, if the pumping system operates in 80% or 60% loads and the energy cost is calculated in non peak-valley electricity price, the repayment will be lengthened up to 18 years. In China's S-to-N Water Diversion Project, when the market operation and peak-valley electricity prices are taken into effect to supply water and regulate water levels in regulation reservoirs as Hongzehu Lake, Luomahu Lake, etc. the economic operation of water-diversion pumping stations will be vital, and the adoption of VFDs to achieve optimal operation may be a good choice.

Slow-slip events on the Whillans Ice Plain, Antarctica, described using rate-and-state friction as an ice stream sliding law

NASA Astrophysics Data System (ADS)

Lipovsky, Bradley Paul; Dunham, Eric M.

2017-04-01

The Whillans Ice Plain (WIP), Antarctica, experiences twice daily tidally modulated stick-slip cycles. Slip events last about 30 min, have sliding velocities as high as ˜0.5 mm/s (15 km/yr), and have total slip ˜0.5 m. Slip events tend to occur during falling ocean tide: just after high tide and just before low tide. To reproduce these characteristics, we use rate-and-state friction, which is commonly used to simulate tectonic faulting, as an ice stream sliding law. This framework describes the evolving strength of the ice-bed interface throughout stick-slip cycles. We present simulations that resolve the cross-stream dimension using a depth-integrated treatment of an elastic ice layer loaded by tides and steady ice inflow. Steady sliding with rate-weakening friction is conditionally stable with steady sliding occurring for sufficiently narrow ice streams relative to a nucleation length. Stick-slip cycles occur when the ice stream is wider than the nucleation length or, equivalently, when effective pressures exceed a critical value. Ice streams barely wider than the nucleation length experience slow-slip events, and our simulations suggest that the WIP is in this slow-slip regime. Slip events on the WIP show a sense of propagation, and we reproduce this behavior by introducing a rate-strengthening region in the center of the otherwise rate-weakening ice stream. If pore pressures are raised above a critical value, our simulations predict that the WIP would exhibit quasi-steady tidally modulated sliding as observed on other ice streams. This study validates rate-and-state friction as a sliding law to describe ice stream sliding styles.

Overview of Aerosolized Florida Red Tide Toxins: Exposures and Effects

PubMed Central

Fleming, Lora E.; Backer, Lorraine C.; Baden, Daniel G.

2005-01-01

Florida red tide is caused by Karenia brevis, a dinoflagellate that periodically blooms, releasing its potent neurotoxin, brevetoxin, into the surrounding waters and air along the coast of the Gulf of Mexico. Exposure to Florida red tide toxins has been associated with adverse human health effects and massive fish and marine mammal deaths. The articles in this mini-monograph describe the ongoing interdisciplinary and interagency research program that characterizes the exposures and health effects of aerosolized Florida red tide toxins (brevetoxins). The interdisciplinary research program uses animal models and laboratory studies to develop hypotheses and apply these findings to in situ human exposures. Our ultimate goal is to develop appropriate prevention measures and medical interventions to mitigate or prevent adverse health effects from exposure to complex mixtures of aerosolized red tide toxins. PMID:15866773

Modelling the influence of tides on ice-shelf melt rates in the Amundsen Sea, Antarctica.

NASA Astrophysics Data System (ADS)

Jourdain, Nicolas C.; Molines, Jean-Marc; Le Sommer, Julien; Mathiot, Pierre; Chanut, Jérome; Madec, Gurvan

2017-04-01

Variations in melt beneath ice- shelves may trigger ice-sheet instabilities, in particular in West Antarctica. Therefore, improving the understanding and modelling of ice-shelf basal melt rates has been a major focus over the last decades. In this presentation, we provide further insight into the role of tides on basal melt rates, and we assess several methods to account for tides in models that do not include an explicit representation of tides. First, we use an explicit representation of tides in a regional configuration of the NEMO-3.6 model deployed over the Amundsen Sea. We show that most of the tidal influence on ice-shelf melt is explained by four tidal constituents. Tides enhance melt by more than 30% in some cavities like Abbot, Cosgrove and Dotson, but by less than 10% in others like Thwaites and Pine Island. Over the entire Amundsen Sea sector, tides enhance melt by 92 Gt/yr, which is mostly induced by tidal velocities along ice drafts (+148 Gt/yr), partly compensated by tide-induced change in thermal forcing (-31 Gt/yr) and co-variations between tidal velocities and thermal forcing (-26 Gt/yr). In the second part of this presentation, we show that using uniform tidal velocities to account for tides effects in ocean models with no explicit tides produces large biases in melt rates. By contrast, prescribing non-uniform tidal velocities allows an accurate representation of the dynamical effects of tides on melt rates.

Providing long-term trend and gravimetric factor at Chandler period from superconducting gravimeter records by using Singular Spectrum Analysis along with its multivariate extension

NASA Astrophysics Data System (ADS)

Gruszczynska, M.; Rosat, S.; Klos, A.; Bogusz, J.

2017-12-01

In this study, Singular Spectrum Analysis (SSA) along with its multivariate extension MSSA (Multichannel SSA) were used to estimate long-term trend and gravimetric factor at the Chandler wobble frequency from superconducting gravimeter (SG) records. We have used data from seven stations located worldwide and contributing to the International Geodynamics and Earth Tides Service (IGETS). The timespan ranged from 15 to 19 years. Before applying SSA and MSSA, we had removed local tides, atmospheric (ECMWF data), hydrological (MERRA2 products) loadings and non-tidal ocean loading (ECCO2 products) effects. In the first part of analysis, we used the SSA approach in order to estimate the long-term trends from SG observations. We use the technique based on the classical Karhunen-Loève spectral decomposition of time series into long-term trend, oscillations and noise. In the second part, we present the determination of common time-varying pole tide (annual and Chandler wobble) to estimate gravimetric factor from SG time series using the MSSA approach. The presented method takes advantage over traditional methods like Least Squares Estimation by determining common modes of variability which reflect common geophysical field. We adopted a 6-year lag-window as the optimal length to extract common seasonal signals and the Chandler components of the Earth polar motion. The signals characterized by annual and Chandler wobble account for approximately 62% of the total variance of residual SG data. Then, we estimated the amplitude factors and phase lags of Chandler wobble with respect to the IERS (International Earth Rotation and Reference Systems Service) polar motion observations. The resulting gravimetric factors at the Chandler Wobble period are finally compared with previously estimates. A robust estimate of the gravimetric Earth response to the Chandlerian component of the polar motion is required to better constrain the mantle anelasticity at this frequency and hence the attenuation models of the Earth interior.

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

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

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

NASA Astrophysics Data System (ADS)

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.

Hydrologic and water-quality data in selected agricultural drainages in Beaufort and Hyde Counties, North Carolina, 1990-92

USGS Publications Warehouse

Treece, M.W.

1993-01-01

An investigation was begun in 1988 to: (1) quantify nutrient, sediment, and freshwater loadings in canals that collect drainage from cropland field ditches; (2) determine the effects of tide gates and flashboard risers on these loadings and on receiving water quality; and (3) characterize the effects of drainage on the salinity regime of a tidal creek. Data were collected in three canals in Hyde County, two canals in Beaufort County, and in Campbell Creek, which receives drainage directly from the Beaufort County canals. A tide gate was placed in one of the Hyde County canals near the beginning of the investigation. In August 1990 following more than 2 years of data collection, control structures were placed in the remaining two Hyde County canals. Flashboard risers were installed in the Beaufort County canals in April 1991. Hydrologic and water quality data are presented for each of the study sites for the period of October 1990 through May 1992. Following a description of the study sites and data collection methods, data are presented for the five drainage canals and Campbell Creek. The data collected included: (1) daily values of accumulated precipitation; (2) water level statistics; (3) daily mean values of discharge in the canals; (4) biweekly water quality measurements and sample analyses; (5) storm-event water quality measurements and sample analyses; (6) continuous records of specific conductance in the canals; (7) vertical profiles of salinity in Campbell Creek; and (8) daily mean values of salinity at five sites at Campbell Creek.

A two-dimensional analytical model for groundwater flow in a leaky aquifer extending finite distance under the estuary

NASA Astrophysics Data System (ADS)

Chuang, Mo-Hsiung; Hung, Chi-Tung; -Yen Lin, Wen; Ma, Kuo-chen

2017-04-01

In recent years, cities and industries in the vicinity of the estuarine region have developed rapidly, resulting in a sharp increase in the population concerned. The increasing demand for human activities, agriculture irrigation, and aquaculture relies on massive pumping of water in estuarine area. Since the 1950s, numerous studies have focused on the effects of tidal fluctuations on groundwater flow in the estuarine area. Tide-induced head fluctuation in a two-dimensional estuarine aquifer system is complicated and rather important in dealing with many groundwater management or remediation problems. The conceptual model of the aquifer system considered is multi-layered with estuarine bank and the leaky aquifer extend finite distance under the estuary. The solution of the model describing the groundwater head distribution in such an estuarine aquifer system and subject to the tidal fluctuation effects from estuarine river is developed based on the method of separation of variables along with river boundary. The solutions by Sun (Sun H. A two-dimensional analytical solution of groundwater response to tidal loading in an estuary, Water Resour. Res. 1997; 33:1429-35) as well as Tang and Jiao (Tang Z. and J. J. Jiao, A two-dimensional analytical solution for groundwater flow in a leaky confined aquifer system near open tidal water, Hydrological Processes, 2001; 15: 573-585) can be shown to be special cases of the present solution. On the basis of the analytical solution, the groundwater head distribution in response to estuarine boundary is examined and the influences of leakage, hydraulic parameters, and loading effect on the groundwater head fluctuation due to tide are investigated and discussed. KEYWORDS: analytical model, estuarine river, groundwater fluctuation, leaky aquifer.

Impact of sea level rise on tide gate function.

PubMed

Walsh, Sean; Miskewitz, Robert

2013-01-01

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

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

NASA Technical Reports Server (NTRS)

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.

Late Quaternary variations in relative sea level due to glacial cycle polar wander

USGS Publications Warehouse

Bills, B.G.; James, T.S.

1996-01-01

Growth and decay of continental ice sheets can excite significant motion of the Earth's rotation pole and cause a complex spatio-temporal pattern of changes in relative sea level. These two effects have generally been considered separately, but may interact in important ways. In particular, a simple model of the melting of the Laurentide ice sheet causes a uniform eustatic sea level rise of 55 m, and also induces a motion of the rotation pole by 0.1 to 1 degree, depending on viscosity structure in the mantle. This motion produces a secular pole tide, which is a spherical harmonic degree 2, order 1 component of the relative sea level pattern, with peak-to-peak amplitude of 20 to 40 m. The maximum effect is along the great circle passing through the path of the pole and at latitudes of ??45??. This secular pole tide has been ignored in most previous attempts to estimate ice sheet loading history and mantle viscosity from global patterns of relative sea level change. It has a large influence along the East coast of North America and the West coast of South America, and significantly contributes to present day rates of relative sea level change.

The recognition of ocean red tide with hyper-spectral-image based on EMD

NASA Astrophysics Data System (ADS)

Zhao, Wencang; Wei, Hongli; Shi, Changjiang; Ji, Guangrong

2008-05-01

A new technique is introduced in this paper regarding red tide recognition with remotely sensed hyper-spectral images based on empirical mode decomposition (EMD), from an artificial red tide experiment in the East China Sea in 2002. A set of characteristic parameters that describe absorbing crest and reflecting crest of the red tide and its recognition methods are put forward based on general picture data, with which the spectral information of certain non-dominant alga species of a red tide occurrence is analyzed for establishing the foundation to estimate the species. Comparative experiments have proved that the method is effective. Meanwhile, the transitional area between red-tide zone and non-red-tide zone can be detected with the information of thickness of algae influence, with which a red tide can be forecast.

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

NASA Technical Reports Server (NTRS)

Nam, Young; Dickman, S. R.

1990-01-01

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

Research on High Accuracy Detection of Red Tide Hyperspecrral Based on Deep Learning Cnn

NASA Astrophysics Data System (ADS)

Hu, Y.; Ma, Y.; An, J.

2018-04-01

Increasing frequency in red tide outbreaks has been reported around the world. It is of great concern due to not only their adverse effects on human health and marine organisms, but also their impacts on the economy of the affected areas. this paper put forward a high accuracy detection method based on a fully-connected deep CNN detection model with 8-layers to monitor red tide in hyperspectral remote sensing images, then make a discussion of the glint suppression method for improving the accuracy of red tide detection. The results show that the proposed CNN hyperspectral detection model can detect red tide accurately and effectively. The red tide detection accuracy of the proposed CNN model based on original image and filter-image is 95.58 % and 97.45 %, respectively, and compared with the SVM method, the CNN detection accuracy is increased by 7.52 % and 2.25 %. Compared with SVM method base on original image, the red tide CNN detection accuracy based on filter-image increased by 8.62 % and 6.37 %. It also indicates that the image glint affects the accuracy of red tide detection seriously.

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

NASA Technical Reports Server (NTRS)

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

2003-01-01

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

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

NASA Astrophysics Data System (ADS)

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 observed. While fortnightly inversion in the tidal duration asymmetry is explained by the presence of channels and sandbanks, at the same time, the tidal velocity asymmetry acts as a positive feedback mechanism for bank formation and sediment retention.

Effects of the oceans on polar motion: Extended investigations

NASA Technical Reports Server (NTRS)

Dickman, Steven R.

1986-01-01

A method was found for expressing the tide current velocities in terms of the tide height (with all variables expanded in spherical harmonics). All time equations were then combined into a single, nondifferential matrix equation involving only the unknown tide height. The pole tide was constrained so that no tidewater flows across continental boundaries. The constraint was derived for the case of turbulent oceans; with the tide velocities expressed in terms of the tide height. The two matrix equations were combined. Simple matrix inversion then yielded the constrained solution. Programs to construct and invert the matrix equations were written. Preliminary results were obtained and are discussed.

Direct and Indirect Effects of Tides on Ecosystem-Scale CO2 Exchange in a Brackish Tidal Marsh in Northern California

NASA Astrophysics Data System (ADS)

Knox, S. H.; Windham-Myers, L.; Anderson, F.; Sturtevant, C.; Bergamaschi, B.

2018-03-01

We investigated the direct and indirect influence of tides on net ecosystem exchange (NEE) of carbon dioxide (CO2) in a temperate brackish tidal marsh. NEE displayed a tidally driven pattern with obvious characteristics at the multiday scale, with greater net CO2 uptake during spring tides than neap tides. Based on the relative mutual information between NEE and biophysical variables, this was driven by a combination of higher water table depth (WTD), cooler air temperature, and lower vapor pressure deficit (VPD) during spring tides relative to neap tides, as the fortnightly tidal cycle not only influenced water levels but also strongly modulated water and air temperature and VPD. Tides also influenced NEE at shorter timescales, with a reduction in nighttime fluxes during growing season spring tides when the higher of the two semidiurnal tides caused inundation at the site. WTD significantly influenced ecosystem respiration (Reco), with lower Reco during spring tides than neap tides. While WTD did not appear to affect ecosystem photosynthesis (gross ecosystem production, GPP) directly, the impact of tides on temperature and VPD influenced GPP, with higher daily light-use efficiency and photosynthetic activity during spring tides than neap tides when temperature and VPD were lower. The strong direct and indirect influence of tides on NEE across the diel and multiday timescales has important implications for modeling NEE in tidal wetlands and can help inform the timing and frequency of chamber measurements as annual or seasonal net CO2 uptake may be underestimated if measurements are only taken during nonflooded periods.

Ecological traps in shallow coastal waters-Potential effect of heat-waves in tropical and temperate organisms.

PubMed

Vinagre, Catarina; Mendonça, Vanessa; Cereja, Rui; Abreu-Afonso, Francisca; Dias, Marta; Mizrahi, Damián; Flores, Augusto A V

2018-01-01

Mortality of fish has been reported in tide pools during warm days. That means that tide pools are potential ecological traps for coastal organisms, which happen when environmental changes cause maladaptive habitat selection. Heat-waves are predicted to increase in intensity, duration and frequency, making it relevant to investigate the role of tide pools as traps for coastal organisms. However, heat waves can also lead to acclimatization. If organisms undergo acclimatization prior to being trapped in tide pools, their survival chances may increase. Common tide pool species (46 species in total) were collected at a tropical and a temperate area and their upper thermal limits estimated. They were maintained for 10 days at their mean summer sea surface temperature +3°C, mimicking a heat-wave. Their upper thermal limits were estimated again, after this acclimation period, to calculate each species' acclimation response. The upper thermal limits of the organisms were compared to the temperatures attained by tide pool waters to investigate if 1) tide pools could be considered ecological traps and 2) if the increase in upper thermal limits elicited by the acclimation period could make the organisms less vulnerable to this threat. Tropical tide pools were found to be ecological traps for an important number of common coastal species, given that they can attain temperatures higher than the upper thermal limits of most of those species. Tide pools are not ecological traps in temperate zones. Tropical species have higher thermal limits than temperate species, but lower acclimation response, that does not allow them to survive the maximum habitat temperature of tropical tide pools. This way, tropical coastal organisms seem to be, not only more vulnerable to climate warming per se, but also to an increase in the ecological trap effect of tide pools.

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

NASA Astrophysics Data System (ADS)

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.

Staging of the Acoustic Response at Laboratory Modelling of Tidal Influence upon Seismicity

NASA Astrophysics Data System (ADS)

Saltykov, Vadim; Patonin, Andrey; Kugaenko, Yulia

2010-05-01

INTRODUCTION The seismic radiation is varied through the wide range of seismic energy from seismic emission (high-frequency seismic noise, HFSN) to earthquakes. Some features of external influence response on the different scales allow to consider the medium as a single whole seismoactive object. Earth tide is a bright example of external excited field. Tidal topic has long history in seismology. Results obtained by different scientists are contradictory and ambiguous often. We denoted instability of tidal effect manifestation as possible reason of this situation. In view of the aforesaid it is significant, that tidal effects in weak seismicity and HFSN prove more strongly in the stage of large earthquake preparation [Rykunov et al., 1998, Saltykov et al., 2004, 2007]. It is presumed that the metastable medium has more high tidal sensitivity. For example, sources of prepared earthquakes and extensive near-surface zones of micro-fissuring and dilatancy, which appear during source formation and stretch far enough. [Alekseev et all., 2001, Goldin, 2004, 2005]. Common features of observed effects allow to suggest existence of tidal modulation mechanism, which is similar (may be single) for different seismic scales. Modelling of these processes can improve our understanding of tidal effect nature. LABORATORY EXPERIMENT Results of rock sample destruction experiments under controlling are presented. Acoustic emission (AE) pulses act as analogue of seismic events. Tides are simulated by weak long-period variations added to quasi-stationary subcritical loading. The results of tidal modeling confirmed AE intensity synchronization with external periodic influence with large (5-10%) variations of loading are known [Lockner, Beeler, 1999, Ponomarev et al., 2007]. But real (in nature) tidal strain&stress variations are much less and equal to splits of percent. Therefore, investigation of weak modulation influence upon deformed rock is one of main proposed purposes. Used software-programmable electro-hydraulic system INOVA [Patonin, 2006], can provide various procedures of experiment, among them programmable modulatory action. Axial deformation with stable strain rate and additional action of meander with specified period and amplitude was chosen as mode of operation. The relation between background and periodic strains reaches three orders, which corresponds to real relation between maximal tectonic and tidal strains. RESULTS For detection of periodic loading modulation of AE we used procedure based on Rayleigh criteria of uniformity and considered uniformity of AE impulses distribution on time interval, multiple to period of loading. Moreover, the predominant phase of periodical loading, corresponding to maximal AE activity, was calculated in sliding time window. In all experiments we observed instability of modulation effects. So the following stages were distinguished: - synchronization of AE and periodic loading at the initial part of test; - absence of synchronization at the elastic stage; - resumption of synchronization during plastic deformation. Stability of phase corresponding to maximal AE activity was discovered within the initial part and plastic deformation stage. Absolute values of phase for initial loading and during plastic deformation are different. CONCLUSION Now we regard revealed staging of AE response to weak periodical loading as our main result of these experiments. Different stages of AE response are connected with different state of rock samples during loading and destruction. Observed effects of synchronization can be considered as analogue of tidal modulation of HFSN and appearance of "tidal" seismicity in source zone of prepared large earthquake. This investigation was supported by RFBR, grant 08-05-00692.

Methyl mercury dynamics in a tidal wetland quantified using in situ optical measurements

USGS Publications Warehouse

Bergamaschi, B.A.; Fleck, J.A.; Downing, B.D.; Boss, E.; Pellerin, B.; Ganju, N.K.; Schoellhamer, D.H.; Byington, A.A.; Heim, W.A.; Stephenson, M.; Fujii, R.

2011-01-01

We assessed monomethylmercury (MeHg) dynamics in a tidal wetland over three seasons using a novel method that employs a combination of in situ optical measurements as concentration proxies. MeHg concentrations measured over a single spring tide were extended to a concentration time series using in situ optical measurements. Tidal fluxes were calculated using modeled concentrations and bi-directional velocities obtained acoustically. The magnitude of the flux was the result of complex interactions of tides, geomorphic features, particle sorption, and random episodic events such as wind storms and precipitation. Correlation of dissolved organic matter quality measurements with timing of MeHg release suggests that MeHg is produced in areas of fluctuating redox and not limited by buildup of sulfide. The wetland was a net source of MeHg to the estuary in all seasons, with particulate flux being much higher than dissolved flux, even though dissolved concentrations were commonly higher. Estimated total MeHg yields out of the wetland were approximately 2.5 μg m−2 yr−1—4–40 times previously published yields—representing a potential loading to the estuary of 80 g yr−1, equivalent to 3% of the river loading. Thus, export from tidal wetlands should be included in mass balance estimates for MeHg loading to estuaries. Also, adequate estimation of loads and the interactions between physical and biogeochemical processes in tidal wetlands might not be possible without long-term, high-frequency in situ measurements.

Influence of Solar and Lunar Tides on the Mesopause Region as Observed in Polar Mesosphere Summer Echoes Characteristics

NASA Astrophysics Data System (ADS)

Dalin, P.; Kirkwood, S.; Pertsev, N.; Perminov, V.

2017-10-01

Long-term observations of polar mesosphere summer echoes (PMSE) from 2002 to 2012 are investigated with the aim to statistically study the effects of solar thermal migrating and lunar gravitational tides on aerosol layers and their environment at altitudes 80-90 km. The solar and lunar tidal periodicities are clearly present in PMSE data. For the first time, both amplitudes and phases of solar and lunar tides are estimated using PMSE data from the ESRAD radar located at Esrange (Sweden). The diurnal, semidiurnal, and terdiurnal solar migrating tides show pronounced periodicities in the PMSE strength and wind velocity components. Lunar tides demonstrate clear oscillations in the PMSE strength and wind velocities as well. "canonical" lunar gravitational tides, corresponding to the lunar gravitational potential, produce rather large amplitudes and are comparable to the solar thermal tides, whereas "noncanonical" lunar oscillations have minor effects on PMSE layers, but are still statistically significant. The influence of diurnal/semidiurnal tides and monthly/semimonthly tidal components is studied separately. Our estimations of solar thermal and lunar tidal amplitudes are in good agreement with those of previous model and experimental studies. A new mechanism of quadratic demodulation of the solar semidiurnal and lunar semidiurnal tides is shown to be valid at the summer mesopause and can explain periodical PMSE oscillations due to the lunar synodic semimonthly tide with period of 14.77 days. Two harmonics with periods of 27.0 and 13.5 days supposedly representing the solar rotation cycle are also clearly present in PMSE data.

The comparison of heavy metals (Pb and Cd) in the water and sediment during spring and neap tide tidal periods in Popoh Bay, Indonesia

NASA Astrophysics Data System (ADS)

Yona, D.; Febriana, R.; Handayani, M.

2018-04-01

This study attempted to investigate different concentration of lead (Pb) dan cadmium (Cd) in the water and sediment during spring and neap tidal periods in the Popoh Bay, Indonesia. Water and sediment samples were taken during spring and neap tides from eight sampling stations in the study area. The result shows higher concentration of Pb than the concentration of Cd in both spring and neap tides due to higher input of Pb from the oil pollution by boat and fisheries activities. Pb concentrations were doubled during neap tide in both water and sediments with the value of 0.51 and 0.28 ml/L in the water during neap and spring tide, respectively; and 0.27 ppm and 0.16 mg/kg in the sediment during neap and spring tide, respectively. On the other hand, Cd concentrations in the water were found in almost similar values between spring and neap tide (0.159 and 0.165 ml/L in spring tide and neap tide, respectively), but in the sediment, the concentration was a little higher during spring tide (0.09 and 0.05 mg/kg during spring and neap tide, respectively). This study shows that water movement during spring and neap tides has significant effect on the distribution of heavy metals.

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

NASA Astrophysics Data System (ADS)

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.

Preliminary Study on Coupling Wave-Tide-Storm Surges Prediction System

NASA Astrophysics Data System (ADS)

You, S.; Park, S.; Seo, J.; Kim, K.

2008-12-01

The Korean Peninsula is surrounded by the Yellow Sea, East China Sea, and East Sea. This complex oceanographic system includes large tides in the Yellow Sea and seasonally varying monsoon and typhoon events. For Korea's coastal regions, floods caused by wave and storm surges are among the most serious threats. To predict more accurate wave and storm surge, the development of coupling wave-tide-storm surges prediction system is essential. For the time being, wave and storm surges predictions are still made separately in KMA (Korea Meteorological Administration) and most operational institute. However, many researchers have emphasized the effects of tides and storm surges on wind waves and recommended further investigations into the effects of wave-tide-storm surges interactions and coupling module on wave heights. However, tidal height and current give a great effect on the wave prediction in the Yellow sea where is very high tide and related research is not enough. At present, KMA has operated the wave (RWAM : Regional Wave Model) and storm surges/tide prediction system (RTSM : Regional Tide/Storm Surges Model) for ocean forecasting. The RWAM is WAVEWATCH III which is a third generation wave model developed by Tolman (1989). The RTSM is based on POM (Princeton Ocean Model, Blumberg and Mellor, 1987). The RWAM and RTSM cover the northwestern Pacific Ocean from 115°E to 150°E and from 20°N to 52°N. The horizontal grid intervals are 1/12° in both latitudinal and longitudinal directions. The development, testing and application of a coupling module in which wave-tide-storm surges are incorporated within the frame of KMA Ocean prediction system, has been considered as a step forward in respect of ocean forecasting. In addition, advanced wave prediction model will be applicable to the effect of ocean in the weather forecasting system. The main purpose of this study is to show how the coupling module developed and to report on a series of experiments dealing with the sensitivities and real case prediction of coupling wave-tide-storm surges prediction system.

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

PubMed

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

2014-02-01

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

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

PubMed Central

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

2013-01-01

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

Tidal asymmetry in a tidal creek with mixed mainly semidiurnal tide, Bushehr Port, Persian Gulf

NASA Astrophysics Data System (ADS)

Hosseini, Seyed Taleb; Chegini, Vahid; Sadrinasab, Masoud; Siadatmousavi, Seyed Mostafa; Yari, Sadegh

2016-03-01

This study investigated the tidal asymmetry imposed by both the interaction of principal tides and the higher harmonics generated by distortions within a tidal creek network with mixed mainly semidiurnal tide in the Bushehr Port, Persian Gulf. Since velocity and water-level imposed by principal triad tides K1-O1-M2 are in quadrature, duration asymmetries during a tidal period in this short, shallow inverse estuary should be manifest as skewed velocities. The principal tides produce periodic asymmetries including a strong ebb-dominance and a weak flood-dominance condition during spring and neap tides respectively. The higher harmonics induced by nonlinearities engender a flood-dominance condition where the convergence effects are higher than frictional effects, and an ebbdominance condition where intertidal storage are extended. Since the triad K1-O1-M2 driven asymmetry is not overcome by higher harmonics close to the mouth, the periodic asymmetry dominates within the creek in which higher harmonics reinforce the weak flood-dominance (strong ebb-dominance) condition in the convergent channel (divergent area). Also, the maximum flood and the maximum ebb from all harmonic constituents occurred close to high water slack time during both spring and neap tides in this short creek. Since occational wetting of intertidal areas happened close to the high water (HW) time during spring tide, the water level flooded slowly close to the HW time of the spring tide.

CHEMODYNAMIC EVOLUTION OF DWARF GALAXIES IN TIDAL FIELDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williamson, David; Martel, Hugo; Romeo, Alessandro B., E-mail: david-john.williamson.1@ulaval.ca

The mass–metallicity relation shows that the galaxies with the lowest mass have the lowest metallicities. As most dwarf galaxies are in group environments, interaction effects such as tides could contribute to this trend. We perform a series of smoothed particle hydrodynamics simulations of dwarf galaxies in external tidal fields to examine the effects of tides on their metallicities and metallicity gradients. In our simulated galaxies, gravitational instabilities drive gas inwards and produce centralized star formation and a significant metallicity gradient. Strong tides can contribute to these instabilities, but their primary effect is to strip the outer low-metallicity gas, producing amore » truncated gas disk with a large metallicity. This suggests that the effect of tides on the mass–metallicity relation is to move dwarf galaxies to higher metallicities.« less

Effects of the oceans on polar motion: Extended investigations

NASA Technical Reports Server (NTRS)

Dickman, Steven R.

1987-01-01

Matrix formulation of the tide equations (pole tide in nonglobal oceans); matrix formulation of the associated boundary conditions (constraints on the tide velocity at coastlines); and FORTRAN encoding of the tide equations excluding boundary conditions were completed. The need for supercomputer facilities was evident. Large versions of the programs were successfully run on the CYBER, submitting the jobs from SUNY through the BITNET network. The code was also restructured to include boundary constraints.

The effect of wind waves on spring-neap variations in sediment transport in two meso-tidal estuarine basins with contrasting fetch

NASA Astrophysics Data System (ADS)

Hunt, Stephen; Bryan, Karin R.; Mullarney, Julia C.

2017-03-01

Higher-energy episodic wind-waves can substantially modify estuarine morphology over short timescales which are superimposed on lower-energy but long-term tidal asymmetry effects. Theoretically, wind waves and tidal currents change the morphology through their combined influence on the asymmetry between bed shear stress, τmax, on the flood and ebb tide, although the relative contribution of such wind-wave events in shaping the long-term morphological evolution in real estuaries is not well known. If the rising tide reaches sufficiently high water depths, τmax decreases as water depth increases because of the depth attenuation of wave orbital velocities. However, this effect is opposed by the increase in τmax associated with the longer fetch occurring at high tide, which allows the generation of larger waves. Additionally, these effects are superimposed on the spring-neap variations in current associated with changes to tidal range. By comparing two mesotidal basins in the same dendritic estuary, one with a large fetch aligned with the prevailing wind direction and one with only a small fetch, we show that for a sufficiently large fetch even the small and frequently occurring wind events are able to create waves that are capable of changing the morphology ('morphologically significant'). Conversely, in the basin with reduced fetch, these waves are generated less frequently and therefore are of reduced morphological significance. Here, we find that although tidal current should be stronger during spring tides and alter morphology more, on average the reduced fetch and increased water depth during spring tides mean that the basin-averaged intertidal τmax is similar during both spring and neap tides. Moreover, in the presence of wind waves, the duration of slack water is reduced during neap tides relative to spring tides, resulting in a reduced chance for accretion during neap tides. Finally, τmax is lower in the subtidal channels during neaps than springs but of a similar magnitude over the intertidal areas, and so sediment is more likely to be advected from the intertidal regions during neap tides rather than springs. This spring-neap cycle in sediment transport potential is in sharp contrast to that found previously in microtidal wave-dominated environments, where spring tides are expected to enhance erosion.

Lunar tides in the Thermosphere-Ionosphere-Electrodynamics General Circulation Model

NASA Astrophysics Data System (ADS)

Stening, R. J.; Richmond, A. D.; Roble, R. G.

1999-01-01

Lunar semidiurnal tides are introduced at the lower boundary of the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM). The tides are derived from the model of Vial and Forbes [1994] and interesting properties of these tides are found when they are subjected to Hough decomposition; there is considerable hemispherical antisymmetry in the September tides, and the March and September modal compositions are significantly different. A differencing method is used to isolate the lunar tidal effects in the TIEGCM, and these are compared with lunar tidal analyses of ionospheric data. The model reproduces the broad features of the lunar tide in foF2 (maximum frequency of the F region) with phase changes around 7° magnetic dip latitude during daytime. The model and data analysis both give variations of the amplitude and phase of the lunar tide with local time. Near the equator the variation of phase with local time changes with latitude as the equatorial anomaly develops during the day. Comparison between the model predictions and analyses of data at observatories at midlatitudes produces mixed results. Here the effects of the lunar components of both electrodynamic drifts and of neutral winds need to be taken into account. Several cases of day to night changes in the phase of the lunar tide in foF2 are noted. Large nighttime amplitudes of the lunar tide in hmF2 (height of the maximum density), more than 4 km, seem to be due to inphase action of the electrodynamic and neutral wind effects while during daytime they are out of phase. The lunar tide in the ratio of oxygen to nitrogen density [O]/[N2] is estimated and found to be of relatively minor importance. Amplitudes of the lunar tide in foF2 may be measured at more than 0.4 MHz at some local times, but the model values are less than this. Comparison is also made with ion drift measurements made by the San Marco D satellite. The several uncertainties which underlie this work are discussed in detail.

Tides and Trends in Higher Education.

ERIC Educational Resources Information Center

Fincher, Cameron

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

Mapping Hurricane Rita inland storm tide

USGS Publications Warehouse

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

2009-01-01

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

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

PubMed Central

2009-01-01

Abstract Collaborative care models for depression in primary care are effective and cost-effective, but difficult to spread to new sites. Translating Initiatives for Depression into Effective Solutions (TIDES) is an initiative to promote evidence-based collaborative care in the U.S. Veterans Health Administration (VHA). Social marketing applies marketing techniques to promote positive behavior change. Described in this paper, TIDES used a social marketing approach to foster national spread of collaborative care models. TIDES social marketing approach The approach relied on a sequential model of behavior change and explicit attention to audience segmentation. Segments included VHA national leadership, Veterans Integrated Service Network (VISN) regional leadership, facility managers, frontline providers, and veterans. TIDES communications, materials and messages targeted each segment, guided by an overall marketing plan. Results Depression collaborative care based on the TIDES model was adopted by VHA as part of the new Primary Care Mental Health Initiative and associated policies. It is currently in use in more than 50 primary care practices across the United States, and continues to spread, suggesting success for its social marketing-based dissemination strategy. Discussion and conclusion Development, execution and evaluation of the TIDES marketing effort shows that social marketing is a promising approach for promoting implementation of evidence-based interventions in integrated healthcare systems. PMID:19785754

Effect of tidal fluctuations on transient dispersion of simulated contaminant concentrations in coastal aquifers

USGS Publications Warehouse

La Licata, Ivana; Langevin, Christian D.; Dausman, Alyssa M.; Alberti, Luca

2011-01-01

Variable-density groundwater models require extensive computational resources, particularly for simulations representing short-term hydrologic variability such as tidal fluctuations. Saltwater-intrusion models usually neglect tidal fluctuations and this may introduce errors in simulated concentrations. The effects of tides on simulated concentrations in a coastal aquifer were assessed. Three analyses are reported: in the first, simulations with and without tides were compared for three different dispersivity values. Tides do not significantly affect the transfer of a hypothetical contaminant into the ocean; however, the concentration difference between tidal and non-tidal simulations could be as much as 15%. In the second analysis, the dispersivity value for the model without tides was increased in a zone near the ocean boundary. By slightly increasing dispersivity in this zone, the maximum concentration difference between the simulations with and without tides was reduced to as low as 7%. In the last analysis, an apparent dispersivity value was calculated for each model cell using the simulated velocity variations from the model with tides. Use of apparent dispersivity values in models with a constant ocean boundary seems to provide a reasonable approach for approximating tidal effects in simulations where explicit representation of tidal fluctuations is not feasible.

Effect of tidal fluctuations on transient dispersion of simulated contaminant concentrations in coastal aquifers

USGS Publications Warehouse

La Licata, Ivana; Langevin, Christian D.; Dausman, Alyssa M.; Alberti, Luca

2013-01-01

Variable-density groundwater models require extensive computational resources, particularly for simulations representing short-term hydrologic variability such as tidal fluctuations. Saltwater-intrusion models usually neglect tidal fluctuations and this may introduce errors in simulated concentrations. The effects of tides on simulated concentrations in a coastal aquifer were assessed. Three analyses are reported: in the first, simulations with and without tides were compared for three different dispersivity values. Tides do not significantly affect the transfer of a hypothetical contaminant into the ocean; however, the concentration difference between tidal and non-tidal simulations could be as much as 15%. In the second analysis, the dispersivity value for the model without tides was increased in a zone near the ocean boundary. By slightly increasing dispersivity in this zone, the maximum concentration difference between the simulations with and without tides was reduced to as low as 7%. In the last analysis, an apparent dispersivity value was calculated for each model cell using the simulated velocity variations from the model with tides. Use of apparent dispersivity values in models with a constant ocean boundary seems to provide a reasonable approach for approximating tidal effects in simulations where explicit representation of tidal fluctuations is not feasible.

Florida Red Tide Perception: Residents versus Tourists

PubMed Central

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

2010-01-01

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

Florida Red Tide Perception: Residents versus Tourists.

PubMed

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

2010-09-01

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

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

NASA Astrophysics Data System (ADS)

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.

Gastrointestinal Emergency Room Admissions and Florida Red Tide Blooms.

PubMed

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

2010-01-01

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

Gastrointestinal Emergency Room Admissions and Florida Red Tide Blooms

PubMed Central

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

2009-01-01

Human exposure to brevetoxins during Florida red tide blooms formed by Karenia brevis has been documented to cause acute gastrointestinal, neurologic, and respiratory health effects.. Traditionally, the routes of brevetoxin exposure have been through the consumption of contaminated bivalve shellfish and the inhalation of contaminated aerosols. However, recent studies using more sensitive methods have demonstrated the presence of brevetoxins in many components of the aquatic food web which may indicate potential alternative routes for human exposure. This study examined whether the presence of a Florida red tide bloom affected the rates of admission for a gastrointestinal diagnosis to a hospital emergency room in Sarasota, FL. The rates of gastrointestinal diagnoses admissions were compared for a 3-month time period in 2001 when Florida red tide bloom was present onshore to the same 3-month period in 2002 when no Florida red tide bloom occurred. A significant 40% increase in the total number of gastrointestinal emergency room admissions for the Florida red tide bloom period was found compared to the non red tide period. These results suggest that the healthcare community may experience a significant and unrecognized impact from patients needing emergency medical care for gastrointestinal illnesses during Florida red tide blooms. Thus, additional studies characterizing the potential sources of exposure to the toxins, as well as the dose/effect relationship of brevetoxin exposure, should be undertaken. PMID:20161425

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

PubMed

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

2013-03-15

A multi-nested prediction system for the Yellow Sea using drifter trajectory simulations was developed to predict the movements of an oil spill after the MV Hebei Spirit accident. The speeds of the oil spill trajectories predicted by the model without tidal forcing were substantially faster than the observations; however, predictions taking into account the tides, including both tidal cycle and subtidal periods, were satisfactorily improved. Subtidal flow in the simulation without tides was stronger than in that with tides because of reduced frictional effects. Friction induced by tidal stress decelerated the southward subtidal flows driven by northwesterly winter winds along the Korean coast of the Yellow Sea. These results strongly suggest that in order to produce accurate predictions of oil spill trajectories, simulations must include tidal effects, such as variations within a tidal cycle and advections over longer time scales in tide-dominated areas. Copyright © 2012 Elsevier Ltd. All rights reserved.

Observations and simulations of the ionospheric lunar tide: Seasonal variability

NASA Astrophysics Data System (ADS)

Pedatella, N. M.

2014-07-01

The seasonal variability of the ionospheric lunar tide is investigated using a combination of Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) observations and thermosphere-ionosphere-mesosphere electrodynamics general circulation model (TIME-GCM) simulations. The present study focuses on the seasonal variability of the lunar tide in the ionosphere and its potential connection to the occurrence of stratosphere sudden warmings (SSWs). COSMIC maximum F region electron density (NmF2) and total electron content observations reveal a primarily annual variation of the ionospheric lunar tide, with maximum amplitudes occurring at low latitudes during December-February. Simulations of the lunar tide climatology in TIME-GCM display a similar annual variability as the COSMIC observations. This leads to the conclusion that the annual variability of the lunar tide in the ionosphere is not solely due to the occurrence of SSWs. Rather, the annual variability of the lunar tide in the ionosphere is generated by the seasonal variability of the lunar tide at E region altitudes. However, compared to the observations, the ionospheric lunar tide annual variability is weaker in the climatological simulations which is attributed to the occurrence of SSWs during the majority of the years included in the observations. Introducing a SSW into the TIME-GCM simulation leads to an additional enhancement of the lunar tide during Northern Hemisphere winter, increasing the lunar tide annual variability and resulting in an annual variability that is more consistent with the observations. The occurrence of SSWs can therefore potentially bias lunar tide climatologies, and it is important to consider these effects in studies of the lunar tide in the atmosphere and ionosphere.

Characterization of Iberian turbid plumes by means of synoptic patterns obtained through MODIS imagery

NASA Astrophysics Data System (ADS)

Fernández-Nóvoa, D.; deCastro, M.; Des, M.; Costoya, X.; Mendes, R.; Gómez-Gesteira, M.

2017-08-01

Turbid plumes formed by the main Iberian rivers were analyzed and compared in order to determine similarities and differences among them. Five Atlantic rivers (Minho, Douro, Tagus, Guadiana and Guadalquivir) and one Mediterranean river (Ebro) were considered. Plume extension and turbidity were evaluated through synoptic patterns obtained by means of MODIS imagery over the period 2003-2014. River discharge showed to be the main forcing. In fact, the dependence of plume extension on runoff is moderate or high for all rivers, except for Ebro. In addition, most of river plumes adjust immediately to runoff fluctuations. Only the extension of Tagus and Guadalquivir plumes is lagged with respect to river runoff, due to the high residence time generated by their large estuaries. Wind is a secondary forcing, being only noticeable under high discharges. Actually, the dependence of plume extension on wind is moderate or high for all rivers, except Guadalquivir and Ebro. All the Atlantic rivers show the maximum (minimum) near- field plume extension under landward (oceanward) cross-shore winds. The opposite situation was observed for Ebro River. Tide is also a secondary forcing although less important than wind. Actually, the dependence of plume extension on tide is only high for Guadiana River. Nevertheless, all Atlantic river plumes still have some dependence on semidiurnal tidal cycle, they increase under low tides and decrease under high tides. In addition, Tagus River plume also depends on the fortnightly tidal cycle being larger during spring tides than during neap tides. This is due to particular shape of the estuary, where the river debouches into a semi-enclosed embayment connected to the Atlantic Ocean through a strait. Ebro River constitutes a particular case since it has a low dependence on runoff and wind and a negligible dependence on tide. In fact, its plume is mainly driven by the Liguro-Provençal coastal current. Guadalquivir River also shows some unique features due to its high sediment load. It generates the largest Iberian plume in terms of turbid signal and extension even being the second smallest river in terms of discharge.

Joint use of long water pipe tiltmeters and sea level gauges for monitoring ground deformation at Campi Flegrei caldera

NASA Astrophysics Data System (ADS)

Scarpa, Roberto; Capuano, Paolo; Tammaro, Umberto; Bilham, Roger

2014-05-01

The Campi Flegrei caldera, located in the Campanian Plain, Southern Italy, 15 km west of the city of Naples, is a nested, resurgent, and restless structure in the densely inhabited Neapolitan area. The main caldera at Campi Flegrei is 12 - 15 km across and its rim is thought to have been formed during the catastrophic eruption, occurred 39 ky ago ca., which produced a deposit referred to as the Campanian Ignimbrite. The volcanic hazards posed by this caldera and the related risk are extremely high, because of its explosive character and the about 1.5 million people living within the caldera. Campi Flegrei area periodically experiences significant unrest episodes which include ground deformations, the so-called 'bradisismo'. Following the last eruption (Monte Nuovo, 1538) a general subsidence has been interrupted by episodes of uplift, the most recent of which occurred in 1970-72 and 1982-84. Since 1950 the caldera is showing signs of unrest with ground uplift, seismicity, and composition variation of fumarole fluids. In particular, subsidence has been replaced by intermittent episodes of inflation with short time duration and various maximum amplitude. They occurred in 1989, 1994, 2000, 2005-06, 2008-09 and 2011-2014 with duration of few months and maximum amplitude ranging between 3 and 18 cm., approximately. In the last years an array of water-pipe tiltmeters with lengths between 28 m and 278 m in tunnels on the flanks of the region of maximum inflation has been installed to avoid problems common to the traditional tiltmeters. The tiltmeters record inflation episodes upon which are superimposed local load tides and the effects of the seiches in the Bay of Naples and in the Tyrrhenian sea. We use data recorded by three tide gauges in the Bay of Pozzuoli (Pozzuoli, Miseno, Nisida) to compare water pipe data with sea level to extract astronomical tidal components (diurnal and semidiurnal) and seiches periods (particularly between 20 minutes and 56 minutes) that could constitute local loading frequencies recorded clearly by tide gauges and tiltmeters. We perform an analysis of the amplitude stability of seiches amplitudes. After the removal of the tides and seiches component we compare tilt residual and sea level trend for the same periods of time. The comparison between these two kind of data enables a more sensitive definition of the low level uplift with an accuracy of 1% for nanoradiant tilts in the period range 10 minutes to 10 hours with a long term tilt stability of approximately 0.1 microradiant/yr.

Observation model and parameter partials for the JPL VLBI parameter estimation software MODEST, 19 94

NASA Technical Reports Server (NTRS)

Sovers, O. J.; Jacobs, C. S.

1994-01-01

This report is a revision of the document Observation Model and Parameter Partials for the JPL VLBI Parameter Estimation Software 'MODEST'---1991, dated August 1, 1991. It supersedes that document and its four previous versions (1983, 1985, 1986, and 1987). A number of aspects of the very long baseline interferometry (VLBI) model were improved from 1991 to 1994. Treatment of tidal effects is extended to model the effects of ocean tides on universal time and polar motion (UTPM), including a default model for nearly diurnal and semidiurnal ocean tidal UTPM variations, and partial derivatives for all (solid and ocean) tidal UTPM amplitudes. The time-honored 'K(sub 1) correction' for solid earth tides has been extended to include analogous frequency-dependent response of five tidal components. Partials of ocean loading amplitudes are now supplied. The Zhu-Mathews-Oceans-Anisotropy (ZMOA) 1990-2 and Kinoshita-Souchay models of nutation are now two of the modeling choices to replace the increasingly inadequate 1980 International Astronomical Union (IAU) nutation series. A rudimentary model of antenna thermal expansion is provided. Two more troposphere mapping functions have been added to the repertoire. Finally, corrections among VLBI observations via the model of Treuhaft and lanyi improve modeling of the dynamic troposphere. A number of minor misprints in Rev. 4 have been corrected.

Ecological traps in shallow coastal waters—Potential effect of heat-waves in tropical and temperate organisms

PubMed Central

Mendonça, Vanessa; Cereja, Rui; Abreu-Afonso, Francisca; Dias, Marta; Mizrahi, Damián; Flores, Augusto A. V.

2018-01-01

Mortality of fish has been reported in tide pools during warm days. That means that tide pools are potential ecological traps for coastal organisms, which happen when environmental changes cause maladaptive habitat selection. Heat-waves are predicted to increase in intensity, duration and frequency, making it relevant to investigate the role of tide pools as traps for coastal organisms. However, heat waves can also lead to acclimatization. If organisms undergo acclimatization prior to being trapped in tide pools, their survival chances may increase. Common tide pool species (46 species in total) were collected at a tropical and a temperate area and their upper thermal limits estimated. They were maintained for 10 days at their mean summer sea surface temperature +3°C, mimicking a heat-wave. Their upper thermal limits were estimated again, after this acclimation period, to calculate each species’ acclimation response. The upper thermal limits of the organisms were compared to the temperatures attained by tide pool waters to investigate if 1) tide pools could be considered ecological traps and 2) if the increase in upper thermal limits elicited by the acclimation period could make the organisms less vulnerable to this threat. Tropical tide pools were found to be ecological traps for an important number of common coastal species, given that they can attain temperatures higher than the upper thermal limits of most of those species. Tide pools are not ecological traps in temperate zones. Tropical species have higher thermal limits than temperate species, but lower acclimation response, that does not allow them to survive the maximum habitat temperature of tropical tide pools. This way, tropical coastal organisms seem to be, not only more vulnerable to climate warming per se, but also to an increase in the ecological trap effect of tide pools. PMID:29420657

Tide-related seismic velocity changes across the English Channel

NASA Astrophysics Data System (ADS)

de Ridder, S.; Valova, V.; Curtis, A.

2016-12-01

Temporal changes in the seismic velocities in the Earth's subsurface are known to occur due to a range of phenomena including seasonal variations, magmatic activity, nonlinear healing after strong ground motion, and glacial loading and unloading. Our goal is to extend observations of small velocity changes towards shorter timescales. Earth tides caused by the gravitational attraction between the Earth and the Moon might affect seismic properties. If tidal velocity variations can be recovered from long range cross-correlations, and can also be coupled to stress-strain induced variations in the elastic properties, that would pave the way for systematic imaging of rheological properties of the upper crust. With this long-term goal, we studied data recorded between January 2010 and December 2015 by four broad-band instruments from the British Geological Survey network. One station is located in Cornwall, two in Devon, and one across the English Channel on the island of Jersey. Continuous seismic recordings of the vertical components of particle velocity were divided into one hour intervals, bandpass filtered between 0.02 and 0.11 Hz, spectrally whitened, and cross-correlated between station pairs. The resulting cross-correlations were stacked into bins corresponding to the average water levels observed at nearby ports resulting in cross-correlation traces as a function of water level, for each station pair. To detect temporal changes, a multi-window time-shift analysis is applied to these inter-station traces. We find a stretch factor that best translates one trace into another: this stretch is indicative of changes in average seismic velocities between the pair of tidal phases. We detected systematic seismic velocity variations as a function of water level. We find that increasing water level coincided with decreasing seismic velocities. Separating the data according to up- and down-going tidal tracts reveals that the observed velocity changes exhibit a time-lag, assuming that tide-induced strain is the dominant controlling factor. We discuss potential mechanisms for the observed seismic velocity dependency on water level including the effect of a thicker water layer on the dispersion characteristics of seismic velocities, and tidal loading related changes in the elastic properties of the subsurface.

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

NASA Astrophysics Data System (ADS)

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.

Laboratory triggering of stick-slip events by oscillatory loading in the presence of pore fluid with implications for physics of tectonic tremor

USGS Publications Warehouse

Bartlow, Noel M.; Lockner, David A.; Beeler, Nicholas M.

2012-01-01

The physical mechanism by which the low-frequency earthquakes (LFEs) that make up portions of tectonic (also called non-volcanic) tremor are created is poorly understood. In many areas of the world, tectonic tremor and LFEs appear to be strongly tidally modulated, whereas ordinary earthquakes are not. Anomalous seismic wave speeds, interpreted as high pore fluid pressure, have been observed in regions that generate tremor. Here we build upon previous laboratory studies that investigated the response of stick-slip on artificial faults to oscillatory, tide-like loading. These previous experiments were carried out using room-dry samples of Westerly granite, at one effective stress. Here we augment these results with new experiments on Westerly granite, with the addition of varying effective stress using pore fluid at two pressures. We find that raising pore pressure, thereby lowering effective stress can significantly increase the degree of correlation of stick-slip to oscillatory loading. We also find other pore fluid effects that become important at higher frequencies, when the period of oscillation is comparable to the diffusion time of pore fluid into the fault. These results help constrain the conditions at depth that give rise to tidally modulated LFEs, providing confirmation of the effective pressure law for triggering and insights into why tremor is tidally modulated while earthquakes are at best only weakly modulated.

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

PubMed Central

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

Tidal atmospheric and ocean loading in VLBI analysis

NASA Astrophysics Data System (ADS)

Girdiuk, Anastasiia; Schindelegger, Michael; Böhm, Johannes

2016-04-01

In VLBI (Very Long Baseline Interferometry) analysis, reductions for tidal atmospheric and ocean loading are commonly used according to the IERS Conventions. In this presentation we examine such loading corrections from contemporary geophysical models within routine VLBI processing and discuss the internal consistency of the applied corrections for various effects. In detail, two gravitational ocean tide models, FES2004 and the recent FES2012 atlas with a much finer horizontal resolution and an improved description of hydrodynamic processes, are employed. Moreover, the contribution of atmospheric tidal loading is also re-considered based on data taken from two providers of station displacements, Goddard Space Flight Center and the TU Wien group. Those two models differ in terms of the underlying meteorological data, which can be a reason for inconsistency of VLBI reductions and may lead to systematics in the VLBI products at tidal frequencies. We validate this assumption in terms of Earth rotation parameters, by a tidal analysis of diurnal and semi-diurnal universal time and semi-diurnal polar motion variations as determined with the Vienna VLBI Software. Applying the loading models in a consistent way still leads to unexplained residuals at about 4-5 μas in the diurnal polar motion band, thus limiting the possibility of assessing geophysical models at this particular frequency.

Storm surge and tide interaction: a complete paradigm

NASA Astrophysics Data System (ADS)

Horsburgh, Kevin; Williams, Jane; Proctor, Robert

2014-05-01

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

Storm Surge and Tide Interaction: A Complete Paradigm

NASA Astrophysics Data System (ADS)

Horsburgh, K.

2014-12-01

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

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

PubMed

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.

Oscillating load-induced acoustic emission in laboratory experiment

USGS Publications Warehouse

Ponomarev, Alexander; Lockner, David A.; Stroganova, S.; Stanchits, S.; Smirnov, Vladmir

2010-01-01

Spatial and temporal patterns of acoustic emission (AE) were studied. A pre-fractured cylinder of granite was loaded in a triaxial machine at 160 MPa confining pressure until stick-slip events occurred. The experiments were conducted at a constant strain rate of 10−7 s−1 that was modulated by small-amplitude sinusoidal oscillations with periods of 175 and 570 seconds. Amplitude of the oscillations was a few percent of the total load and was intended to simulate periodic loading observed in nature (e.g., earth tides or other sources). An ultrasonic acquisition system with 13 piezosensors recorded acoustic emissions that were generated during deformation of the sample. We observed a correlation between AE response and sinusoidal loading. The effect was more pronounced for higher frequency of the modulating force. A time-space spectral analysis for a “point” process was used to investigate details of the periodic AE components. The main result of the study was the correlation of oscillations of acoustic activity synchronized with the applied oscillating load. The intensity of the correlated AE activity was most pronounced in the “aftershock” sequences that followed large-amplitude AE events. We suggest that this is due to the higher strain-sensitivity of the failure area when the sample is in a transient, unstable mode. We also found that the synchronization of AE activity with the oscillating external load nearly disappeared in the period immediately after the stick-slip events and gradually recovered with further loading.

The importance of weightlessness and tides in teaching gravitation

NASA Astrophysics Data System (ADS)

Galili, I.; Lehavi, Y.

2003-11-01

We examine the presentation of the weight, weightlessness, and tides in university-level physics textbooks. Introductory textbooks often do not discuss tidal forces even though their understanding would be useful for understanding weightlessness. The explanations of tides often miss the free gravitational motion of both interacting objects, which is essential for the symmetry of tidal deformation. The shortcomings in the explanations of weightlessness and tides as provided by students and teachers are compared to textbook discussions. We suggest that an explicit discussion of the different definitions of weight and a synergetic presentation of weightlessness and tides might lead to a better understanding of gravitation. Our approach is illustrated by examples of tidal effects appropriate for introductory courses.

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

NASA Astrophysics Data System (ADS)

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.

Impacts of nutrients and related environmental factors on distribution and size structure of Noctiluca scintillans populations of the eutrophic Tha Chin estuary, Thailand.

PubMed

Chuenniyom, Wansiri; Meksumpun, Charumas; Meksumpun, Shettapong

2012-01-01

This study aimed to analyze the impacts of nutrients and related aquatic factors on changes in the Noctiluca population of the Tha Chin estuary, a nutrient-rich estuary located in the inner Gulf of Thailand. Field surveys were carried out at 30 stations during November 2009 to August 2010. The results indicated high levels of dissolved inorganic nitrogen (DIN; 13.89-46.99 μmol/L) and PO(4)(3-)-P (0.20-3.05 μmol/L) where the Noctiluca red tide occurred, particularly during the high-loading period. Dense populations were usually found in the outer part of the estuary with comparatively high salinity (25-29 psu). The highest Noctiluca density was 72,333 cells L(-1) and the cell diameters ranged between 360 and 460 μm. Proportions of small-sized cells (P(s); less than 300 μm) varied over time. In this study, P(s) showed a positive correlation with levels of PO(4)(3-)-P, while the total population density was significantly affected by levels of NH(4)(+)-N and DIN (p < 0.05). Overall, PO(4)(3-)-P influenced the development of the Noctiluca red tide, with the limitation of PO(4)(3-)-P levels to below 1 μmol/L suggested for controlling Noctiluca red tide outbreaks at their origin. To support environmental conservation and maintain sustainable production in the estuary, the levels of PO(4)(3-)-P should be considered for the further effective development of water quality standards in estuarine zones.

Tidal parameters derived from the perturbations in the orbital inclinations of the BE-C, GEOS-1 and GEOS-2 satellites

NASA Technical Reports Server (NTRS)

Rubincam, D. P.

1976-01-01

Effective tidal Love numbers and phase angles for the O sub one, K sub one, M sub two, K sub two, P sub one, and S sub two, tides are recovered. The effective tidal phase angles tend to be on the order of a few degrees. The effective tidal Love numbers are generally less than the solid earth Love number K sub two, of about 0.30. This supports the contention that the ocean tides give an apparent depression of the solid earth Love number. Ocean tide amplitudes and phases are calculated for the above tides assuming K sub two = 0.30 and the solid earth lag angle O sub two = 0. The results show good agreement on GEOS-1 but not on GEOS-II.

HPLC pigment analysis of marine phytoplankton during a red tide occurrence in Tolo Harbour, Hong Kong.

PubMed

Wong, C Kwan; Wong, C Kim

2003-09-01

A red tide was detected in the inner parts of Tolo Harbour, Hong Kong, in November 2000. Water samples were collected from a fixed station at the centre of the red tide patch for microscopic analysis of phytoplankton community composition and high performance liquid chromatography (HPLC) analysis of phytoplankton pigments. At the peak of the red tide on 24 November 2000, phytoplankton was dominated by the dinoflagellate Scrippsiella trochoidea. The red tide began to decline at the end of November and, by 1 December 2000, the phytoplankton was dominated by diatoms. Chlorophylls and carotenoids in water samples were analysed using HPLC pigment separation technique. Dinoflagellates were indicated by the signature pigment peridinin. Significant correlation (r=0.999) was found between the peridinin concentration and dinoflagellate density. A decrease in peridinin and an increase in fucoxanthin, a major carotenoid in diatoms, marked the shift in phytoplankton composition at the end of the red tide. HPLC analysis also revealed the occurrence of minor phytoplankton groups that are difficult to identify by light microscopy. Red tide monitoring and study of red tide dynamics in Hong Kong have been based on cell counting and spectrophotometric or fluorometric measurement of chlorophyll a. HPLC pigment analysis provides an effective alternative for investigating phytoplankton dynamics during red tide and other algal blooms.

Tides and Decadal Variability

NASA Technical Reports Server (NTRS)

Ray, Richard D.

2003-01-01

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

Quantifying and Projecting Relative Sea-Level Rise in The Deltaic Regions

NASA Astrophysics Data System (ADS)

Shum, C. K.; Chung-Yen, K.; Calmant, S.; Yang, T. Y.; Guo, Q.; Jia, Y.; Ballu, V.; Guo, J.; Karptychev, M.; Krien, Y.; Kusche, J.; Tseng, K. H.; Wan, J.; Uebbing, B.

2017-12-01

Half of the world's population lives within 200 km of coastlines. Accelerated sea-level rise, compounded by effects of population growth, severe land subsidence due to fluvial sediment compaction/load, and anthropogenic oil and natural gas and ground water extraction, tectonic motion, and the increasing threat of more intense and more frequent cyclone-driven storm surges, have exacerbated the vulnerability of many of world's deltaic regions, including the Bangladesh and the Mississippi River Deltas. At present, understanding and quantifying the natural and anthropogenic processes governing these solid Earth vertical motion processes remain elusive to enable addressing coastal vulnerability due to current and future projection of relative sea-level rise for deltaic regions at the regional scales. Bangladesh, a low-lying and one of the most densely populated countries in the world located at the Bay of Bengal, is prone to transboundary monsoonal flooding, and is believed to be aggravated by more frequent and intensified cyclones resulting from anthropogenic climate change. The Mississippi River Deltaic region has been severely subsiding due primarily to fluvial sediment compaction and load during the last 10 centuries, oil/gas and groundwater extractions, and commercial developments, making it vulnerable to sea-level rise hazards. Here we present results of global geocentric sea-level rise, 1950-2016, separating vertical land motion at global tide gauge datum, by integrating tide gauge and radar altimeter records in a novel sea-level reconstruction scheme, focusing on the Mississippi River and the Bangladesh Deltas. We then integrate the resulting sea level estimates with historic imageries, GPS and InSAR data, as well as sediment isostatic and load model predicted present-day land subsidence, to constrain the 3D land motion to study the impacts of various scenarios of future relative sea level projections on the Bangladesh Delta to the end of the 21st Century and beyond.

Future Change to Tide-Influenced Deltas

NASA Astrophysics Data System (ADS)

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.

Development and Application of an Acoustic System for Harmful Algal Blooms (HABs, Red Tide) Detection using an Ultrasonic Digital Sensor

NASA Astrophysics Data System (ADS)

Kim, Hansoo; Kang, Donhyug; Jung, Seung Won

2018-03-01

The overgrowth of phytoplankton leads to negative effects such as harmful algal blooms (HABs, also called red tides) in marine environments. The HAB species Cochlodinium polykrikoides ( C. polykrikoides) appears frequently in Korea during summer. In this study, we developed a real-time acoustic detection and remote-control system to detect red tides using an ultrasonic digital sensor. In the laboratory, the acoustic signals increased as the number of cells increased. At the same time, for field application, we deployed the system near the southern coast of Korea, where red tides frequently occurred in summer seasons 2013-2015. The system developed here detected red tides in situ, with a good correlation between the acoustic signals and C. polykrikoides populations. These results suggest that it may be useful for early detection of red tides.

Orthogonal stack of global tide gauge sea level data

NASA Technical Reports Server (NTRS)

Trupin, A.; Wahr, J.

1990-01-01

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

Tide-surge Interaction Intensified by the Taiwan Strait

NASA Astrophysics Data System (ADS)

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.

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

NASA Astrophysics Data System (ADS)

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.

Effect of Tide Elevation on Extratropical Storm Surge in Northwest Europe

NASA Astrophysics Data System (ADS)

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.

Comparing models of seasonal deformation to horizontal and vertical PBO GPS data

NASA Astrophysics Data System (ADS)

Bartlow, N. M.; Fialko, Y. A.; van Dam, T. M.

2015-12-01

GPS monuments around the world exhibit seasonal displacements in both the horizontal and vertical direction with amplitudes on the order of centimeters. For analysis of tectonic signals, researchers typically fit and remove a sine function with an annual period, and sometimes an additional sine function with a semiannual period. As interest grows in analyzing small-amplitude, long-period deformation signals it becomes more important to accurately correct for seasonal variations. It is well established that the vertical component of seasonal GPS signals is largely due to continental water storage cycles (e.g. van Dam et al., GRL, 2001). Other recognized sources of seasonal loading include atmospheric pressure loading and oceanic loading due to non-steric changes in ocean height (e.g. van Dam et al., J. Geodesy, 2012). Here we attempt to build a complete physical model of seasonal loading by considering all of these sources (continental water storage, atmospheric pressure, and oceanic loading) and comparing our model to horizontal and vertical GPS data in the Western US. Atmospheric loading effects are computed from the National Center for Environmental Prediction 6-hourly global reanalysis surface pressure fields; the terrestrial water loading and ocean loading models are generated using SPOTL (Some Programs for Ocean Tide Loading; Agnew, SIO Technical Report, 2012) and parameters from NASA's Land Data Assimilation Systems and the Estimating the Circulation and Climate of the Ocean model, version 4. We find that with a few exceptions, our seasonal loading model predicts the correct phases but underestimates the amplitudes of vertical seasonal loads, and is a generally poor fit to the observed horizontal seasonal signals. This implies that our understanding of the driving mechanisms behind seasonal variations in the GPS data is still incomplete and needs to be improved before physics-based models can be used as an effective correction tool for the GPS timeseries.

Environmental exposures to Florida red tides: Effects on emergency room respiratory diagnoses admissions.

PubMed

Kirkpatrick, Barbara; Fleming, Lora E; Backer, Lorraine C; Bean, Judy A; Tamer, Robert; Kirkpatrick, Gary; Kane, Terrance; Wanner, Adam; Dalpra, Dana; Reich, Andrew; Baden, Daniel G

2006-10-01

Human exposure to Florida red tides formed by Karenia brevis, occurs from eating contaminated shellfish and inhaling aerosolized brevetoxins. Recent studies have documented acute symptom changes and pulmonary function responses after inhalation of the toxic aerosols, particularly among asthmatics. These findings suggest that there are increases in medical care facility visits for respiratory complaints and for exacerbations of underlying respiratory diseases associated with the occurrence of Florida red tides.This study examined whether the presence of a Florida red tide affected the rates of admission with a respiratory diagnosis to a hospital emergency room in Sarasota, FL. The rate of respiratory diagnoses admissions were compared for a 3-month time period when there was an onshore red tide in 2001 (red tide period) and during the same 3-month period in 2002 when no red tide bloom occurred (non-red tide period). There was no significant increase in the total number of respiratory admissions between the two time periods. However, there was a 19% increase in the rate of pneumonia cases diagnosed during the red tide period compared with the non-red tide period. We categorized home residence zip codes as coastal (within 1.6 km from the shore) or inland (>1.6 km from shore). Compared with the non-red tide period, the coastal residents had a significantly higher (54%) rate of respiratory diagnoses admissions than during the red tide period. We then divided the diagnoses into subcategories (i.e. pneumonia, bronchitis, asthma, and upper airway disease). When compared with the non-red tide period, the coastal zip codes had increases in the rates of admission of each of the subcategories during the red tide period (i.e. 31, 56, 44, and 64%, respectively). This increase was not observed seen in the inland zip codes.These results suggest that the healthcare community has a significant burden from patients, particularly those who live along the coast, needing emergency medical care for both acute and potentially chronic respiratory illnesses during red tide blooms.

Spin evolution of Earth-sized exoplanets, including atmospheric tides and core-mantle friction

NASA Astrophysics Data System (ADS)

Cunha, Diana; Correia, Alexandre C. M.; Laskar, Jacques

2015-04-01

Planets with masses between 0.1 and 10 M ⊕ are believed to host dense atmospheres. These atmospheres can play an important role on the planet's spin evolution, since thermal atmospheric tides, driven by the host star, may counterbalance gravitational tides. In this work, we study the long-term spin evolution of Earth-sized exoplanets. We generalize previous works by including the effect of eccentric orbits and obliquity. We show that under the effect of tides and core-mantle friction, the obliquity of the planets evolves either to 0° or 180°. The rotation of these planets is also expected to evolve into a very restricted number of equilibrium configurations. In general, none of these equilibria is synchronous with the orbital mean motion. The role of thermal atmospheric tides becomes more important for Earth-sized planets in the habitable zones of their systems; so they cannot be neglected when we search for their potential habitability.

Changes in Work Habits of Lifeguards in Relation to Florida Red Tide.

PubMed

Nierenberg, Kate; Kirner, Karen; Hoagland, Porter; Ullmann, Steven; Leblanc, William G; Kirkpatrick, Gary; Fleming, Lora E; Kirkpatrick, Barbara

2010-05-01

The marine dinoflagellate, Karenia brevis, is responsible for Florida red tides. Brevetoxins, the neurotoxins produced by K. brevis blooms, can cause fish kills, contaminate shellfish, and lead to respiratory illness in humans. Although several studies have assessed different economic impacts from Florida red tide blooms, no studies to date have considered the impact on beach lifeguard work performance. Sarasota County experiences frequent Florida red tides and staffs lifeguards at its beaches 365 days a year. This study examined lifeguard attendance records during the time periods of March 1 to September 30 in 2004 (no bloom) and March 1 to September 30 in 2005 (bloom). The lifeguard attendance data demonstrated statistically significant absenteeism during a Florida red tide bloom. The potential economic costs resulting from red tide blooms were comprised of both lifeguard absenteeism and presenteeism. Our estimate of the costs of absenteeism due to the 2005 red tide in Sarasota County is about $3,000. On average, the capitalized costs of lifeguard absenteeism in Sarasota County may be on the order of $100,000 at Sarasota County beaches alone. When surveyed, lifeguards reported not only that they experienced adverse health effects of exposure to Florida red tide but also that their attentiveness and abilities to take preventative actions decrease when they worked during a bloom, implying presenteeism effects. The costs of presenteeism, which imply increased risks to beachgoers, arguably could exceed those of absenteeism by an order of magnitude. Due to the lack of data, however, we are unable to provide credible estimates of the costs of presenteeism or the potential increased risks to bathers.

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

USGS Publications Warehouse

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

1998-01-01

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

Jason 1 Investigation: Altimetric Studies of Ocean Tidal Dynamics

NASA Technical Reports Server (NTRS)

Egbert, Gary D.

2004-01-01

Two papers on tidal dissipation were completed and published. The first of these extended our earlier work, which focused on the dominant M2 constituent, to include 7 additional constituents. In addition to confirming a total deep water dissipation total very close to 1 TW, this study demonstrated significant differences in the distribution of dissipation between diurnal and semi-diurnal constituents. The second paper involved an extensive modeling study of tides in the present day and the last glacial maximum. In this study we showed that accuracy of tidal solutions for the present day Ocean were significantly improved by including a parameterization of internal tide drag over rough topography in the deep ocean. It was also demonstrated that a complete self-consistent treatment of Ocean self attraction and tidal loading was required for accurate solutions.

Fortnightly Ocean Tides, Earth Rotation, and Mantle Anelasticity

NASA Technical Reports Server (NTRS)

Ray, Richard; Egbert, Gary

2012-01-01

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

Tidal distortion caused by the resonance of sexta-diurnal tides in a micromesotidal embayment

NASA Astrophysics Data System (ADS)

Song, Dehai; Yan, Yuhan; Wu, Wen; Diao, Xiliang; Ding, Yang; Bao, Xianwen

2016-10-01

Double high water and double-peak flood current were observed in Daya Bay (DYB), China, which is a shallow, mixed, mainly semidiurnal-tide dominated bay with a micro to mesotidal range. Harmonic analysis reveals that the quarter and especially the sexta-diurnal constituents are getting much stronger as tides propagating into the bay. The astronomical tides-induced tidal asymmetry is yet dominant at the bay entrance but overtaken by the sexta-diurnal tides at the end of the bay. Both the M4 and M6 tide meet the requirement proposed in previous studies but still unable to produce a double high water alone. Therefore, the conditions to produce a double high water between a fundamental tide and its higher harmonics need to be revisited. Analytical solutions were obtained in this paper, which fit the numerical solutions very well. Modeling result indicates M6 alone with M2 can produce the double high water in DYB but limited in some regions, while the combination of M2, M4, and M6 tides would enhance the capability. The amplification of sexta-diurnal tides in DYB is dominated by resonance and followed by shoaling effect. Bottom friction damped M6 a lot and largely confined its amplification. However, the quadratic friction and other nonlinear processes are just responsible for about 10% of the total M6 increase.

Effect of tidal fluctuations on contaminant transfer to the ocean

USGS Publications Warehouse

Licata, I.L.; Langevin, C.D.; Dausman, A.M.

2007-01-01

Variable-density groundwater flow was simulated to examine the effects that tide has on the coastward migration of a contaminant through a freshwater/saltwater interface and toward a coastal ocean boundary. Simulated ocean tides did not significantly affect the total contaminant mass input to the ocean; however, the difference in tidal and non-tidal simulated concentrations could be as much as 15%. It may be possible to numerically approximate the tidal-driven hydraulic transients in transport models that do not explicitly include tides by locally increasing dispersivity. Copyright ?? 2007 IAHS Press.

River discharge controlling a tidal delta: the interplay between monsoon input and tidal reworking in SW Bangladesh

NASA Astrophysics Data System (ADS)

Hale, R. P.; Goodbred, S. L., Jr.; Bain, R. L.; Wilson, C.; Best, J.; Reed, M. J.

2015-12-01

The Ganges-Brahmaputra-Meghna River system (GBM) is among the world's largest in terms of both annual water and sediment discharge. The subaerial delta (110,000 km2) is home to ~160 million people, in addition to the ecologically and economically critical Sundarbans National Forest (SNF). Recent sediment budgets suggest that ~15% of the 1 x 109 t yr-1 sediment load carried by the GBM is subsequently advected along shore and inland via tidal activity, to the otherwise-abandoned SW portion of the delta. A unit-scale estimate based on observed offshore suspended sediment concentrations (SSC) >1.0 g L-1 suggests that sufficient sediment is available in the system to maintain the elevation of the subaerial delta plain, even under current relative sea-level-rise rates. Recent work measuring sedimentation within SNF corroborates this finding, and understanding these sediment delivery dynamics will be critical for protecting the future of nearby regions that are heavily populated, but drastically altered by human activities. Cross-channel hydrodynamic surveys were conducted to estimate what fraction of the water (and sediment) is diverted from the major tidal channels toward the SNF interior. Measurements including profiles of velocity and SSC were collected on spring and neap tides during the dry and monsoon seasons, along transects bracketing major conduit channels into the SNF. During the dry season, we observe water flux at the southern end of the study area to be in approximate equilibrium regardless of tidal range, with SSC <0.3 g L-1 during neap tides, and <1.0 g L-1 during spring tides. North of the SNF conduit channels, we observe equilibrium water discharge and similarly low SSC during neap tides, but a modest ebb dominance and surface SSC >1.0 g L-1 during spring tides. This suggests the possibility of additional inputs of water and sediment from an adjacent tidal channel, as well as a potential source for the deposition observed on the Sundarbans platform during spring-tide flooding. Within channels in SNF, near-bed SSC increase by >5x from neap to spring tides, to a peak of ~1.0 g L-1. Sediment grab samples collected in a distributary channel show a moderate fining trend with distance from the major conduit, which has implications for the sedimentation rates observed on the tidal delta plain.

The self-consistent dynamic pole tide in global oceans

NASA Technical Reports Server (NTRS)

Dickman, S. R.

1985-01-01

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

Development of Operational Wave-Tide-Storm surges Coupling Prediction System

NASA Astrophysics Data System (ADS)

You, S. H.; Park, S. W.; Kim, J. S.; Kim, K. L.

2009-04-01

The Korean Peninsula is surrounded by the Yellow Sea, East China Sea, and East Sea. This complex oceanographic system includes large tides in the Yellow Sea and seasonally varying monsoon and typhoon events. For Korea's coastal regions, floods caused by wave and storm surges are among the most serious threats. To predict more accurate wave and storm surges, the development of coupling wave-tide-storm surges prediction system is essential. For the time being, wave and storm surges predictions are still made separately in KMA (Korea Meteorological Administration) and most operational institute. However, many researchers have emphasized the effects of tides and storm surges on wind waves and recommended further investigations into the effects of wave-tide-storm surges interactions and coupling module. In Korea, especially, tidal height and current give a great effect on the wave prediction in the Yellow sea where is very high tide and related research is not enough. At present, KMA has operated the wave (RWAM : Regional Wave Model) and storm surges/tide prediction system (STORM : Storm Surges/Tide Operational Model) for ocean forecasting. The RWAM is WAVEWATCH III which is a third generation wave model developed by Tolman (1989). The STORM is based on POM (Princeton Ocean Model, Blumberg and Mellor, 1987). The RWAM and STORM cover the northwestern Pacific Ocean from 115°E to 150°E and from 20°N to 52°N. The horizontal grid intervals are 1/12° in both latitudinal and longitudinal directions. These two operational models are coupled to simulate wave heights for typhoon case. The sea level and current simulated by storm surge model are used for the input of wave model with 3 hour interval. The coupling simulation between wave and storm surge model carried out for Typhoon Nabi (0514), Shanshan(0613) and Nari (0711) which were effected on Korea directly. We simulated significant wave height simulated by wave model and coupling model and compared difference between uncoupling and coupling cases for each typhoon. When the typhoon Nabi hit at southern coast of Kyushu, predicted significant wave height reached over 10 m. The difference of significant wave height between wave and wave-tide-storm surges model represents large variation at the southwestern coast of Korea with about 0.5 m. Other typhoon cases also show similar results with typhoon Nabi case. For typhoon Shanshan case the difference of significant wave height reached up to 0.3 m. When the typhoon Nari was affected in the southern coast of Korea, predicted significant wave height was about 5m. The typhoon Nari case also shows the difference of significant wave height similar with other typhoon cases. Using the observation from ocean buoy operated by KMA, we compared wave information simulated by wave and wave-storm surges coupling model. The significant wave height simulated by wave-tide-storm surges model shows the tidal modulation features in the western and southern coast of Korea. And the difference of significant wave height between two models reached up to 0.5 m. The coupling effect also can be identified in the wave direction, wave period and wave length. In addition, wave spectrum is also changeable due to coupling effect of wave-tide-storm surges model. The development, testing and application of a coupling module in which wave-tide-storm surges are incorporated within the frame of KMA Ocean prediction system, has been considered as a step forward in respect of ocean forecasting. In addition, advanced wave prediction model will be applicable to the effect of ocean in the weather forecasting system. The main purpose of this study is to show how the coupling module developed and to report on a series of experiments dealing with the sensitivities and real case prediction of coupling wave-tide-storm surges prediction system.

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

NASA Technical Reports Server (NTRS)

Gross, Richard S.

1993-01-01

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

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

USGS Publications Warehouse

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.

Reduction of fecal indicator bacteria (FIB) in the Ballona Wetlands saltwater marsh (Los Angeles County, California, USA) with implications for restoration actions.

PubMed

Dorsey, John H; Carter, Patrick M; Bergquist, Sean; Sagarin, Rafe

2010-08-01

A benefit of wetland preservation and restoration is the ecosystem service of improving water quality, typically assessed based on bacterial loading. The Ballona Wetlands, a degraded salt marsh of approximately 100 ac located on the southern border of Marina Del Rey (Los Angeles County, California, USA) are currently the focus of publicly funded restoration planning. The wetlands receive tidal water, usually contaminated with fecal indicator bacteria (FIB: total and fecal coliforms, Escherichia coli, enterococci) from the adjacent Ballona Creek and Estuary. During the summer of 2007, two 24-h studies were conducted to determine FIB tidal dynamics within the wetland. Measurements of water flow and mean FIB concentrations (n = 3) were measured every 1.5 h to determine total FIB load estimates. FIB loading rates (MPN/s) were greatest during flood tides as water entered the wetlands, and then again during spring tide conditions when sediments were resuspended during swifter spring ebb flows. During daylight hours, the wetland acted as a sink for these bacteria as loads diminished, presumably by sunlight and other processes. Conversely, during late afternoon and night, the wetlands shifted to being a source as excess FIB departed on ebb flows. Therefore, the wetlands act as both a source and sink for FIB depending on tidal conditions and exposure to sunlight. Future restoration actions would result in a tradeoff - increased tidal channels offer a greater surface area for FIB inactivation, but also would result in a greater volume of FIB-contaminated resuspended sediments carried out of the wetlands on stronger ebb flows. As levels of FIB in Ballona Creek and Estuary diminish through recently established regulatory actions, the wetlands could shift into a greater sink for FIB. (c) 2010 Elsevier Ltd. All rights reserved.

GTOOLS: an Interactive Computer Program to Process Gravity Data for High-Resolution Applications

NASA Astrophysics Data System (ADS)

Battaglia, M.; Poland, M. P.; Kauahikaua, J. P.

2012-12-01

An interactive computer program, GTOOLS, has been developed to process gravity data acquired by the Scintrex CG-5 and LaCoste & Romberg EG, G and D gravity meters. The aim of GTOOLS is to provide a validated methodology for computing relative gravity values in a consistent way accounting for as many environmental factors as possible (e.g., tides, ocean loading, solar constraints, etc.), as well as instrument drift. The program has a modular architecture. Each processing step is implemented in a tool (function) that can be either run independently or within an automated task. The tools allow the user to (a) read the gravity data acquired during field surveys completed using different types of gravity meters; (b) compute Earth tides using an improved version of Longman's (1959) model; (c) compute ocean loading using the HARDISP code by Petit and Luzum (2010) and ocean loading harmonics from the TPXO7.2 ocean tide model; (d) estimate the instrument drift using linear functions as appropriate; and (e) compute the weighted least-square-adjusted gravity values and their errors. The corrections are performed up to microGal ( μGal) precision, in accordance with the specifications of high-resolution surveys. The program has the ability to incorporate calibration factors that allow for surveys done using different gravimeters to be compared. Two additional tools (functions) allow the user to (1) estimate the instrument calibration factor by processing data collected by a gravimeter on a calibration range; (2) plot gravity time-series at a chosen benchmark. The interactive procedures and the program output (jpeg plots and text files) have been designed to ease data handling and archiving, to provide useful information for future data interpretation or modeling, and facilitate comparison of gravity surveys conducted at different times. All formulas have been checked for typographical errors in the original reference. GTOOLS, developed using Matlab, is open source and machine independent. We will demonstrate program use and utility with data from multiple microgravity surveys at Kilauea volcano, Hawai'i.

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

NASA Astrophysics Data System (ADS)

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

2016-11-01

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

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

NASA Astrophysics Data System (ADS)

Gong, Wenping; Schuttelaars, Henk; Zhang, Heng

2016-05-01

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 results show that the FDA exhibits a predominant tendency of shorter duration of low water slack, favoring the landward transport of fine sediment. The FVA demonstrates prevailing ebb dominance in the study period, favoring the seaward transport of coarse sediment. This ebb dominance is primarily induced by the interaction among the residual flow and the tidal constituents. The external TDA in the ocean experiences distinct cyclic variations with positive asymmetry when semidiurnal tides dominate and negative asymmetry during the periods when diurnal tides dominate. The funnel shape of the HE is advantageous for the development of positive tidal asymmetry as the semidiurnal tides are more amplified than the diurnal tides. The effect of river flow can enhance the ebb dominance, while the baroclinic effect is more complex. The existence of channel and shoals favors the development of residual pattern with seaward flow (ebb dominance) in the channel and landward flow (flood dominance) at the shoal when the tides are strong (semidiurnal tides dominate) and the residual pattern with landward flow (flood dominance) in the channel and seaward flow (ebb dominance) at the shoal when the baroclinic effect is dominant (diurnal tides dominate).

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

NASA Technical Reports Server (NTRS)

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.

[Removal efficiency of red tide organisms by modified clay and its impacts on cultured organisms].

PubMed

Cao, Xi-hua; Song, Xiu-xian; Yu, Zhi-ming

2004-09-01

Removal efficiencies of Prorocentrum donghaiense (Prorocentrum dentatum) by Hexadecyltrimethylammonium (HDTMA) bromide and organo-clay modified by HDTMA were identified. Moreover the toxicity of the unbound HDTMA and HDTMA plus clay to aquacultural organisms, Penaeus japonicus, was also tested. The results suggested that (1) The unbound HDTMA had an excellent ability to remove the red tide organisms. However, its strong toxicity to Penaeus japonicus would restrict its practical use in red tide control. (2) The toxicity of HDTMA could be remarkably decreased by addition of clay and the organo-clay complex had a good ability to removal red tide organisms. At the same time the availability of organo-clay to remove the red tide of P. donghaiense and Heterosigma akashiwo in the lab-imitated cultures were studied. The results indicated that the organo-clay complex could remove 100% P. donghaiense at the dosage of 0.03 g/L and effectively control H. akashiwo at 0.09 g/L while the survival rate of Penaeus japonicus larvae, which were cultured in the red tide seawater, is kept 100%. According to the results in laboratory, the mesocosm tests (CEPEX) in East China Sea were conducted in April and May of 2003. The removal efficiencies of original clay, organic clay and inorganic clay were compared during the CEPEX tests. The results revealed that both inorganic clay and organic clay could remove red tide organisms more effectively than the original clay.

Propagation Velocity of Solid Earth Tides

NASA Astrophysics Data System (ADS)

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.

Occupational exposure to aerosolized brevetoxins during Florida red tide events: effects on a healthy worker population.

PubMed

Backer, Lorraine C; Kirkpatrick, Barbara; Fleming, Lora E; Cheng, Yung Sung; Pierce, Richard; Bean, Judy A; Clark, Richard; Johnson, David; Wanner, Adam; Tamer, Robert; Zhou, Yue; Baden, Daniel G

2005-05-01

Karenia brevis (formerly Gymnodinium breve) is a marine dinoflagellate responsible for red tides that form in the Gulf of Mexico. K. brevis produces brevetoxins, the potent toxins that cause neurotoxic shellfish poisoning. There is also limited information describing human health effects from environmental exposures to brevetoxins. Our objective was to examine the impact of inhaling aerosolized brevetoxins during red tide events on self-reported symptoms and pulmonary function. We recruited a group of 28 healthy lifeguards who are occupationally exposed to red tide toxins during their daily work-related activities. They performed spirometry tests and reported symptoms before and after their 8-hr shifts during a time when there was no red tide (unexposed period) and again when there was a red tide (exposed period). We also examined how mild exercise affected the reported symptoms and spirometry tests during unexposed and exposed periods with a subgroup of the same lifeguards. Environmental sampling (K. brevis cell concentrations in seawater and brevetoxin concentrations in seawater and air) was used to confirm unexposed/exposed status. Compared with unexposed periods, the group of lifeguards reported more upper respiratory symptoms during the exposed periods. We did not observe any impact of exposure to aerosolized brevetoxins, with or without mild exercise, on pulmonary function.

The role of the kidney in compensating the alkaline tide, electrolyte load, and fluid balance disturbance associated with feeding in the freshwater rainbow trout, Oncorhynchus mykiss.

PubMed

Bucking, Carol; Landman, Michael J; Wood, Chris M

2010-05-01

The effect in freshwater rainbow trout of digesting a commercial pellet meal on the renal handling of water, ions and acid-base equivalents was investigated through urine collection over a 48 h period following meal ingestion. The glomerular filtration rate (GFR) and urine flow rate (UFR) were reduced in fed fish between 12 and 24h following the meal, likely reflecting a loss of endogenous water across the gastric epithelium as a result of ingesting dry, ion-rich food pellets. The kidney was also responsible for the excretion of some excess dietary Ca(2+), and, to a much lesser extent, Na(+) and Cl(-), while the urinary excretion of K(+) was unaffected. The most dramatic effect of feeding was the elevation of renal Mg(2+) excretion, with the kidney transitioning from net Mg(2+) reabsorption to net Mg(2+) secretion during digestion. The renal handling of dietary ions accounted for 3-27% of the total ions absorbed from the diet, indicating that a majority of the ions are excreted extra-renally or incorporated into growth. However this does highlight the underestimation of renal ion handling when using unfed fish models. The metabolic alkalosis created by digestion (the alkaline tide) resulted in an increase in urine pH as well as a transition from net acidic equivalent excretion in the urine to net basic equivalent excretion. This was due to a decrease in the titratable acidity minus bicarbonate component of urine as well as a decrease in ammonia secretion. Additionally, the experimental separation of the urinary component of acid-base excretion from that of the gills highlighted the substantially larger contribution of the latter. During the alkaline tide, renal excretion accounted for approximately 5% of the total basic equivalent excretion to the external water. Copyright 2009 Elsevier Inc. All rights reserved.

[Relationships between pollutants discharge and red tide occurrence in Shenzhen eastern coast].

PubMed

Jiang, Tian-jiu; Niu, Tao; Ying, Wen-ye

2007-05-01

The study on the effects of pollutants discharge on red tide occurrence in eastern sea area of Shenzhen showed that the occurrence frequency of dinoflagellate red tide had significant positive correlations with the net discharge of total nitrogen (TN) and total phosphorous (TP) as well as the N/P ratio of the discharge. The thresholds of net discharged TN and TP were estimated to be 3.917 x 10(3) t and 2.123 x 10(4) t, respectively. No significant correlation was observed between diatom red tide and alongshore pollutants discharge. An example was given to illustrate the means of pollutants discharge control.

Mapping hurricane rita inland storm tide

USGS Publications Warehouse

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

2009-01-01

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

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

NASA Technical Reports Server (NTRS)

De Vries, Dan; Wahr, John M.

1991-01-01

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

Contribution of TIGA reprocessing to the ITRF densification

NASA Astrophysics Data System (ADS)

Rudenko, S.; Dähnn, M.; Gendt, G.; Brandt, A.; Nischan, T.

2009-04-01

Analysis of tide gauge measurements with the purpose of sea level change investigations requires a well defined reference frame. Such reference frame can be realized through precise positions of GPS stations located at or near tide gauges (TIGA stations) and analyzed within the IGS GPS Tide Gauge Benchmark Monitoring Pilot Project (TIGA). To tie this reference frame to the International Terrestrial Reference Frame (ITRF), one should process simultaneously GPS data from TIGA and IGS stations included in the ITRF. A time series of GPS station positions has been recently derived by reprocessing GPS data from about 400 GPS stations globally distributed covering totally time span from 1998 till 2008 using EPOS-Potsdam software developed at GFZ and improved in the recent years. The analysis is based on the use of IERS Conventions 2003, ITRF2005 as a priori reference frame, FES2004 ocean tide loading model, absolute phase centre variations for GPS satellite transmit and ground receive antennae and other models. About 220 stations of the solution are IGS ones and about 180 are TIGA GPS stations that are not IGS ones. The solution includes weekly coordinates of GPS stations, daily values of the Earth rotation parameters and their rates, as well as satellite antenna offsets. On the other hand, our new solution can contribute to the ITRF densification by providing positions of about 200 stations being not present in ITRF2005. The solution can be also used for the integration of regional frames. The paper presents the results of the analysis and the comparison of our solution with ITRF2005 and the solutions of other TIGA and IGS Analysis Centres.

Influence of fortnightly earth tides at Kilauea Volcano, Hawaii

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dzurisin, D.

1980-11-01

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

Influence of fortnightly earth tides at Kilauea Volcano, Hawaii.

USGS Publications Warehouse

Dzurisin, D.

1980-01-01

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

The relative importance of oceanic nutrient inputs for Bass Harbor Marsh Estuary at Acadia National Park, Maine

USGS Publications Warehouse

Huntington, Thomas G.; Culbertson, Charles W.; Fuller, Christopher; Glibert, Patricia; Sturtevant, Luke

2014-01-01

The U.S. Geological Survey and Acadia National Park (ANP) collaborated on a study of nutrient inputs into Bass Harbor Marsh Estuary on Mount Desert Island, Maine, to better understand ongoing eutrophication, oceanic nutrient inputs, and potential management solutions. This report includes the estimation of loads of nitrate, ammonia, total dissolved nitrogen, and total dissolved phosphorus to the estuary derived from runoff within the watershed and oceanic inputs during summers 2011 and 2012. Nutrient outputs from the estuary were also monitored, and nutrient inputs in direct precipitation to the estuary were calculated. Specific conductance, water temperature, and turbidity were monitored at the estuary outlet. This report presents a first-order analysis of the potential effects of projected sea-level rise on the inundated area and estuary volume. Historical aerial photographs were used to investigate the possibility of widening of the estuary channel over time. The scope of this report also includes analysis of sediment cores collected from the estuary and fringing marsh surfaces to assess the sediment mass accumulation rate. Median concentrations of nitrate, ammonium, and total dissolved phosphorus on the flood tide were approximately 25 percent higher than on the ebb tide during the 2011 and 2012 summer seasons. Higher concentrations on the flood tide suggest net assimilation of these nutrients in biota within the estuary. The dissolved organic nitrogen fraction dominated the dissolved nitrogen fraction in all tributaries. The median concentration of dissolved organic nitrogen was about twice as high on the on the ebb tide than the flood tide, indicating net export of dissolved organic nitrogen from the estuary. The weekly total oceanic inputs of nitrate, ammonium, and total dissolved phosphorus to the estuary were usually much larger than inputs from runoff or direct precipitation. The estuary was a net sink for nitrate and ammonium in most weeks during both years. Oceanic inputs of nitrate and ammonium were an important source of inorganic nitrogen to the estuary in both years. In both years, the total seasonal inputs of ammonium to the estuary in flood tides were much larger than the inputs from watershed runoff or direct precipitation. In 2011, the total seasonal input of nitrate from flood tides to the estuary was more than twice as large the inputs from watershed runoff and precipitation, but in 2012, the inputs from flood tides were only marginally larger than the inputs from watershed runoff and precipitation. Turbidity was measured intermittently in 2012, and the pattern that emerged from the measurements indicated that the estuary was a source of particulate matter to the ocean rather than the ocean being a source to the estuary. From the nutrient budgets determined for the estuary it is evident that oceanic sources of nitrate and ammonium are an important part of the supply of nutrients that are contributing to the growth of macroalgae in the estuary. The relative importance of these oceanic nutrients compared with sources within the watershed typically increases as the summer progresses and runoff decreases. It is likely that rising sea levels, estimated by the National Oceanic and Atmospheric Administration to be 11 centimeters from 1950 through 2006 in nearby Bar Harbor, have resulted in an increase in oceanic inputs (tidal volume and nutrients derived from oceanic sources).

Perigean Spring Tides and Apogean Neap Tides in History

NASA Astrophysics Data System (ADS)

Olson, Donald W.

2012-01-01

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

Absolute Sea-level Monitoring and Altimeter Calibration Facility at Gavdos, Crete, Greece

NASA Astrophysics Data System (ADS)

Pavlis, E. C.

2002-12-01

We introduce the recently instrumented mean sea level (MSL) monitoring facility on western Crete and the isle of Gavdos. We will focus on the altimeter calibration aspect of the facility, in particular, its application to the JASON mission. The Eastern Mediterranean area is one of great interest for its intense tectonic activity as well as for its regional oceanography. Recent observations have convincingly demonstrated the importance of that area for the regional meteorological and climatologic changes. Tide-gauge monitoring with continuous GPS has gained importance lately since tectonics contaminate the inferred sea level variations, and a global network of tide-gauges with long historical records can be used as satellite altimeter calibration sites (e.g. TOPEX/POSEIDON, GFO, JASON-1, ENVISAT, etc.). This is at present a common IOC-GLOSS-IGS effort, already underway (TIGA), and our facility is part of it. Crete hosts two of the oldest tide-gauges in the regional network and our project will further expand it to the south with a new site on the isle of Gavdos, the southernmost European parcel of land. One component of our "GAVDOS" project is the repeated occupation of two already in existence tide-gauge sites at Souda Bay and Heraklion, and their tie to the new facility. We show here initial results from positioning of these sites and some of the available tidal records. Gavdos is situated under a ground-track crossing point of the original T/P and present JASON-1 orbits. It is an ideal calibration site if the tectonic motions are monitored precisely and continuously. The facility hosts in addition to the tide gauges: GPS and DORIS beacons for positioning, transponders for direct calibration, water vapor radiometers and solar spectrometers, GPS-loaded buoys, airborne surveys with gravimeters and laser profiling lidars, transportable laser ranging systems, etc., to ensure the best possible and most reliable results.

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

NASA Astrophysics Data System (ADS)

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

2016-05-01

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

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

PubMed

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.

Nutrient loading and consumers: Agents of change in open-coast macrophyte assemblages

PubMed Central

Nielsen, Karina J.

2003-01-01

Human activities are significantly altering nutrient regimes and the abundance of consumers in coastal ecosystems. A field experiment in an open-coast, upwelling ecosystem showed that small increases in nutrients increased the biomass and evenness of tide pool macrophytes where consumer abundance and nutrient loading rates were low. Consumers, when abundant, had negative effects on the diversity and biomass of macrophytes. Nutrient loading increases and consumers are less abundant and efficient as wave exposure increases along open coastlines. Experimentally reversing the natural state of nutrient supply and consumer pressure at a wave-protected site to match wave-exposed sites caused the structure of the macrophyte assemblage to converge on that found naturally in wave-exposed pools. The increases in evenness and abundance were driven by increases in structurally complex functional groups. In contrast, increased nutrient loading in semienclosed marine or estuarine ecosystems is typically associated with declines in macrophyte diversity because of increases in structurally simple and opportunistic functional groups. If nutrient concentration of upwelled waters changes with climatic warming or increasing frequency of El Niños, as predicted by some climate models, these results suggest that macrophyte abundance and evenness along wave-swept open-coasts will also change. Macrophytes represent a significant fraction of continental shelf production and provide important habitat for many marine species. The combined effects of shifting nutrient regimes and overexploitation of consumers may have unexpected consequences for the structure and functioning of open-coast communities. PMID:12796509

Nutrient loading and consumers: agents of change in open-coast macrophyte assemblages.

PubMed

Nielsen, Karina J

2003-06-24

Human activities are significantly altering nutrient regimes and the abundance of consumers in coastal ecosystems. A field experiment in an open-coast, upwelling ecosystem showed that small increases in nutrients increased the biomass and evenness of tide pool macrophytes where consumer abundance and nutrient loading rates were low. Consumers, when abundant, had negative effects on the diversity and biomass of macrophytes. Nutrient loading increases and consumers are less abundant and efficient as wave exposure increases along open coastlines. Experimentally reversing the natural state of nutrient supply and consumer pressure at a wave-protected site to match wave-exposed sites caused the structure of the macrophyte assemblage to converge on that found naturally in wave-exposed pools. The increases in evenness and abundance were driven by increases in structurally complex functional groups. In contrast, increased nutrient loading in semienclosed marine or estuarine ecosystems is typically associated with declines in macrophyte diversity because of increases in structurally simple and opportunistic functional groups. If nutrient concentration of upwelled waters changes with climatic warming or increasing frequency of El Niños, as predicted by some climate models, these results suggest that macrophyte abundance and evenness along wave-swept open-coasts will also change. Macrophytes represent a significant fraction of continental shelf production and provide important habitat for many marine species. The combined effects of shifting nutrient regimes and overexploitation of consumers may have unexpected consequences for the structure and functioning of open-coast communities.

Review of Florida Red Tide and Human Health Effects

PubMed Central

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

Review of Florida Red Tide and Human Health Effects.

PubMed

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

2011-01-01

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

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

PubMed Central

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

2005-01-01

Florida red tides annually occur in the Gulf of Mexico, resulting from blooms of the marine dinoflagellate Karenia brevis. K. brevis produces highly potent natural polyether toxins, known as brevetoxins, that activate voltage-sensitive sodium channels. In experimental animals, brevetoxins cause significant bronchoconstriction. A study of persons who visited the beach recreationally found a significant increase in self-reported respiratory symptoms after exposure to aerosolized Florida red tides. Anecdotal reports indicate that persons with underlying respiratory diseases may be particularly susceptible to adverse health effects from these aerosolized toxins. Fifty-nine persons with physician-diagnosed asthma were evaluated for 1 hr before and after going to the beach on days with and without Florida red tide. Study participants were evaluated with a brief symptom questionnaire, nose and throat swabs, and spirometry approved by the National Institute for Occupational Safety and Health. Environmental monitoring, water and air sampling (i.e., K. brevis, brevetoxins, and particulate size distribution), and personal monitoring (for toxins) were performed. Brevetoxin concentrations were measured by liquid chromatography mass spectrometry, high-performance liquid chromatography, and a newly developed brevetoxin enzyme-linked immunosorbent assay. Participants were significantly more likely to report respiratory symptoms after Florida red tide exposure. Participants demonstrated small but statistically significant decreases in forced expiratory volume in 1 sec, forced expiratory flow between 25 and 75%, and peak expiratory flow after exposure, particularly those regularly using asthma medications. Similar evaluation during nonexposure periods did not significantly differ. This is the first study to show objectively measurable adverse health effects from exposure to aerosolized Florida red tide toxins in persons with asthma. Future studies will examine the possible chronic effects of these toxins among persons with asthma and other chronic respiratory impairment. PMID:15866779

Initial evaluation of the effects of aerosolized Florida red tide toxins (brevetoxins) in persons with asthma.

PubMed

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

2005-05-01

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

Influence of parameterized small-scale gravity waves on the migrating diurnal tide in Earth's thermosphere

NASA Astrophysics Data System (ADS)

Yiǧit, Erdal; Medvedev, Alexander S.

2017-04-01

Effects of subgrid-scale gravity waves (GWs) on the diurnal migrating tides are investigated from the mesosphere to the upper thermosphere for September equinox conditions, using a general circulation model coupled with the extended spectral nonlinear GW parameterization of Yiğit et al. (). Simulations with GW effects cut off above the turbopause and included in the entire thermosphere have been conducted. GWs appreciably impact the mean circulation and cool the thermosphere down by up to 12-18%. GWs significantly affect the winds modulated by the diurnal migrating tide, in particular, in the low-latitude mesosphere and lower thermosphere and in the high-latitude thermosphere. These effects depend on the mutual correlation of the diurnal phases of the GW forcing and tides: GWs can either enhance or reduce the tidal amplitude. In the low-latitude MLT, the correlation between the direction of the deposited GW momentum and the tidal phase is positive due to propagation of a broad spectrum of GW harmonics through the alternating winds. In the Northern Hemisphere high-latitude thermosphere, GWs act against the tide due to an anticorrelation of tidal wind and GW momentum, while in the Southern high-latitudes they weakly enhance the tidal amplitude via a combination of a partial correlation of phases and GW-induced changes of the circulation. The variable nature of GW effects on the thermal tide can be captured in GCMs provided that a GW parameterization (1) considers a broad spectrum of harmonics, (2) properly describes their propagation, and (3) correctly accounts for the physics of wave breaking/saturation.

Effect of Ocean Tide Models on the Precise Orbit Determination of Geodetic Satellites

NASA Astrophysics Data System (ADS)

Kubo-Oka, T.; Matsumoto, K.; Otsubo, T.; Gotoh, T.

2005-12-01

Several ocean tide models are tested with precise observation data of satellite laser ranging to geodetic satellites, Starlette and Stella. Four ocean models, NAO.99b, CSR 3.0 (standard model in IERS Conventions 2003), CSR 4.0, and GOT99.2b were implemented in our orbit analysis software "concerto ver. 4". NAO.99b model was developed by assimilating tidal solutions from TOPEX/POSEIDON altimeter data into hydrodynamical model. Eight constituents (M2, S2, K1, O1, N2, P1, K2, Q1) were taken into account in each ocean tide model. Moreover, eight additional constituents (M1, J1, OO1, 2N2, Mu2, Nu2, L2, T2) can be included in NAO.99b model. Effect of ocean tides on geopotential coefficients were computed to 20th order. SLR data to Starlette and Stella were divided into arcs of 7 days length and 52 arcs (Jan. 2 - Dec. 30, 2004) were analyzed. Using different ocean tide model, orbits of these satellites were determined and weighted rms of postfit residuals are compared. We found that the NAO.99b model with 16 constituents can reduce weighted rms of postfit residuals using to the level of about 6.0 cm (Starlette) and 9.6 cm (Stella). These values are about 3-5 % smaller compared to other ocean tide models.

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

NASA Astrophysics Data System (ADS)

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).

Limits on Lorentz violation in gravity from worldwide superconducting gravimeters

NASA Astrophysics Data System (ADS)

Shao, Cheng-Gang; Chen, Ya-Fen; Sun, Rong; Cao, Lu-Shuai; Zhou, Min-Kang; Hu, Zhong-Kun; Yu, Chenghui; Müller, Holger

2018-01-01

We have investigated Lorentz violation through analyzing tides-subtracted gravity data measured by superconducting gravimeters. At the level of precision of superconducting gravimeters, we have brought up and resolved an existing issue of accuracy due to unaccounted local tidal effects in previous solid-earth tidal model used. Specifically, we have taken local tides into account with a brand new first-principles tidal model with ocean tides included, as well as removed potential bias from local tides by using a worldwide array of 12 superconducting gravimeters. Compared with previous test with local gravimeters, a more accurate and competitive bound on space-space components of gravitational Lorentz violation has been achieved up to the order of 10-10.

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

NASA Astrophysics Data System (ADS)

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.

Effects of environmental stressors on lymphocyte proliferation in Florida manatees, Trichechus manatus latirostris.

PubMed

Walsh, Cathy J; Luer, Carl A; Noyes, David R

2005-02-10

The health of many Florida manatees (Trichechus manatus latirostris) is adversely affected each year by exposure to cold weather or harmful algal blooms (red tide; Karenia brevis). Exposures can be sublethal, resulting in stressed animals that are rescued and taken to authorized facilities for rehabilitation, or lethal if exposures are prolonged or unusually severe. To investigate whether sublethal environmental exposures can impair immune function in manatees, rendering animals vulnerable to disease or death, mitogen-induced proliferation was assessed in lymphocytes from manatees exposed to cold temperatures (N=20) or red tide (N=19) in the wild, and compared to lymphocyte responses from healthy free-ranging manatees (N=32). All animals sampled for this study were adults. Lymphocytes were stimulated in vitro with either concanavalin A (ConA) or phytohemagglutinin (PHA) and proliferation was assessed after 96 h using incorporation of the thymidine analog, bromodeoxyuridine (BrdU), into newly synthesized DNA. Proliferation of lymphocytes from manatees rescued from exposure to red tide or cold-stress was approximately one-third that of lymphocytes from healthy free-ranging manatees. To examine the direct effects of red tide toxins on lymphocyte function, mitogen-induced proliferation was assessed following co-culture of lymphocytes with K. brevis toxin extracts. Stimulation indices decreased with increasing toxin concentration, with a significant decrease in proliferation occurring in the presence of 400 ng red tide toxins/ml. When lymphocytes from cold-stressed manatees were co-cultured with red tide toxin extracts, proliferative responses were reduced even further, suggesting multiple stressors may have synergistic effects on immune function in manatees.

Dependence of Lunar Tide of the Equatorial Electrojet on the Wintertime Polar Vortex, Solar Flux, and QBO

NASA Astrophysics Data System (ADS)

Siddiqui, T. A.; Yamazaki, Y.; Stolle, C.; Lühr, H.; Matzka, J.; Maute, A.; Pedatella, N.

2018-05-01

The lower atmospheric forcing effects on the ionosphere are particularly evident during extreme meteorological events known as sudden stratospheric warmings (SSWs). During SSWs, the polar stratosphere and ionosphere, two distant atmospheric regions, are coupled through the SSW-induced modulation of atmospheric migrating and nonmigrating tides. The changes in the migrating semidiurnal solar and lunar tides are the major source of ionospheric variabilities during SSWs. In this study, we use 55 years of ground-magnetometer observations to investigate the composite characteristics of the lunar tide of the equatorial electrojet (EEJ) during SSWs. These long-term observations allow us to capture the EEJ lunar tidal response to the SSWs in a statistical sense. Further, we examine the influence of solar flux conditions and the phases of quasi-biennial oscillation (QBO) on the lunar tide and find that the QBO phases and solar flux conditions modulate the EEJ lunar tidal response during SSWs in a similar way as they modulate the wintertime Arctic polar vortex. This work provides first evidence of modulation of the EEJ lunar tide due to QBO.

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

NASA Technical Reports Server (NTRS)

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.

Coastal Storm Hazards from Virginia to Maine

DTIC Science & Technology

2015-11-01

study, storm surge, tide, waves, wind, atmospheric pressure, and currents were the dominant storm responses computed. The effect of sea level change on...coastal storm hazards and vulnerability nationally (USACE 2015). NACCS goals also included evaluating the effect of future sea level change (SLC) on...the computed high-fidelity responses included storm surge, astronomical tide, waves, wave effects on water levels, storm duration, wind, currents

Fortnightly Earth Rotation, Ocean Tides, and Mantle Anelasticity

NASA Technical Reports Server (NTRS)

Ray, Richard D.; Egbert, Gary D.

2011-01-01

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

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

PubMed Central

Murillo, Laurence; Randon, Marine; Lebot, Clément

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 favourable nursery grounds for all the studied species, with species-specific effects related to macroalgal density. PMID:28125605

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

PubMed

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 favourable nursery grounds for all the studied species, with species-specific effects related to macroalgal density.

Site-specific probabilistic ecological risk assessment of a volatile chlorinated hydrocarbon-contaminated tidal estuary.

PubMed

Hunt, James; Birch, Gavin; Warne, Michael St J

2010-05-01

Groundwater contaminated with volatile chlorinated hydrocarbons (VCHs) was identified as discharging to Penrhyn Estuary, an intertidal embayment of Botany Bay, New South Wales, Australia. A screening-level hazard assessment of surface water in Penrhyn Estuary identified an unacceptable hazard to marine organisms posed by VCHs. Given the limitations of hazard assessments, the present study conducted a higher-tier, quantitative probabilistic risk assessment using the joint probability curve (JPC) method that accounted for variability in exposure and toxicity profiles to quantify risk (delta). Risk was assessed for 24 scenarios, including four areas of the estuary based on three exposure scenarios (low tide, high tide, and both low and high tides) and two toxicity scenarios (chronic no-observed-effect concentrations [NOEC] and 50% effect concentrations [EC50]). Risk (delta) was greater at low tide than at high tide and varied throughout the tidal cycle. Spatial distributions of risk in the estuary were similar using both NOEC and EC50 data. The exposure scenario including data combined from both tides was considered the most accurate representation of the ecological risk in the estuary. When assessing risk using data across both tides, the greatest risk was identified in the Springvale tributary (delta=25%)-closest to the source area-followed by the inner estuary (delta=4%) and the Floodvale tributary (delta=2%), with the lowest risk in the outer estuary (delta=0.1%), farthest from the source area. Going from the screening level ecological risk assessment (ERA) to the probabilistic ERA changed the risk from unacceptable to acceptable in 50% of exposure scenarios in two of the four areas within the estuary. The probabilistic ERA provided a more realistic assessment of risk than the screening-level hazard assessment. Copyright (c) 2010 SETAC.

Orbital Evolution of Planetesimals by the Galactic Tide

NASA Astrophysics Data System (ADS)

Higuchi, A.; Kokubo, E.; Mukai, T.

2005-05-01

The Oort cloud is a spherical comet reservoir surrounding the solar system. There is general agreement that the Oort cloud comets are the residual planetesimals of planet formation. The standard scenario of the Oort cloud formation consists of two dynamical stages: (1) giant planets raise the aphelia of planetesimals to the outer region of the solar system and (2) the galactic tide, passing stars, and giant molecular clouds pull up their perihelia out of the planetary region. Here we show the orbital evolution of planetesimals by the galactic tide. Planetesimals with large aphelion distances change their perihelion distances toward the outside of the planetary region by the galactic tide and become members of the Oort cloud. The effect of the galactic tide on the planetesimals with semimajor axes of ˜ 104AU is about 10-3 of the solar gravity. The timescale of the orbital evolution is ˜ 108 years. We consider only the vertical component of the galactic tide. Under the axisymmetric potential, some planetesimals may show the librations around ω (argument of perihelion)=π /2 and 3π /2 (the Kozai mechanism). The alternate increases of eccentricity and inclination of the Kozai mechanism are effective to form the Oort cloud. The secular perturbation theory demonstrates the Kozai mechanism and we can understand the motion of the planetesimals analytically. We apply the Kozai mechanism to the galactic tide and discuss the property of the Oort cloud formed by the Kozai mechanizm. This work was supported by the 21st Century COE Program Origin and Evolution of Planetary Systems of the Ministry of Education, Culture, Sports, Science, and Technology, Japan, and JSPS Research Fellowship for Young Scientists.

Poro-elastic Properties of Whillan's Ice Stream Till: Implications for Basal Stick-Slip

NASA Astrophysics Data System (ADS)

Leeman, J.; Valdez, R. D.; Alley, R. B.; Anandakrishnan, S.; Saffer, D. M.

2016-12-01

Whillans ice stream, West Antarctica, flows rapidly from the West Antarctic ice sheet into the Ross Ice Shelf. Regions of highly compacted till, termed sticky-spots, pin the ice in place. Upstream ice flow increases driving stress, until minor changes in buttressing stresses from tides affecting the ice shelf cause the main sticky-spot to fail, triggering diurnal or semidiurnal stick-slip events. The mechanical and hydrological properties of the till partially control the basal conditions, generation and persistence of the sticky spots, and thus the dynamics of the rupture and healing processes. Here we present laboratory tests on core samples of the till beneath Whillan's Ice Stream collected in the 1989-1993 field seasons. Two types of tests were performed on till cores: stepped loading and cyclic loading. In the stepped loading test, the effective stress was increased from 0.1 to 10 MPa in a series of steps, and the permeability measured at each step. Cyclic loading tests consisted of a series of effective stress oscillations with 24 h period lasting 5-10 d each, increasing in amplitude from 20-150 kPa. The permeability was measured after each set of oscillations to investigate the role of cyclic loading in driving enhanced compaction. Compressional wave velocity (Vp) was also measured during both test sequences. We observe sample initial porosities of 30% and permeabilities of 3x10-17 m2. During stepped loading tests, porosity is reduced to 20% and permeability to 8x10-18 m2. Vp ranged from 2.2-2.95 km s-1 and was well fit by an effective medium model. Application of this model to Vp obtained by field seismic surveys is consistent with low ( 50 kPa) effective vertical stresses in the uppermost till. Cyclic loading sequences reduced porosity by 4% and permeability by an order of magnitude. A transient numerical model based on our data shows that over the tidal timescale, a layer of stiffened till 10 cm thick should develop. We suggest that this provides one mechanism to generate and maintain sticky spots and modify the stiffness of the system.

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

NASA Astrophysics Data System (ADS)

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.

Transient groundwater dynamics in a coastal aquifer: The effects of tides, the lunar cycle, and the beach profile

NASA Astrophysics Data System (ADS)

Abarca, Elena; Karam, Hanan; Hemond, Harold F.; Harvey, Charles F.

2013-05-01

Detailed field measurements are combined with a numerical modeling to characterize the groundwater dynamics beneath the discharge zone at Waquoit Bay, Massachusetts. Groundwater salinity values revealed a saline circulation cell that overlaid the discharging freshwater and grew and disappeared with the lunar cycle. The cell was initiated by a greater bay water infiltration during the new moon when high tides overtopped the mean high-tide mark, flooding the flatter beach berm and inundating a larger area of the beach. The dynamics of this cell were further characterized by a tracer test and by constructing a density-dependent flow model constrained to salinity and head data. The numerical model captured the growing and diminishing behavior of the circulation cell and provided the estimates of freshwater and saline water fluxes and travel times. Furthermore, the model enabled quantification of the relationship between the characteristics of the observed tidal cycle (maximum, minimum, and mean tidal elevations) and the different components of the groundwater circulation (freshwater discharge, intertidal saline cycling, and deep saline cycling). We found that (1) recharge to the intertidal saline cell is largely controlled by the high-tide elevation; (2) freshwater discharge is positively correlated to the low-tide elevation, whereas deep saline discharge from below the discharging freshwater is negatively correlated to the low-tide elevation. So, when the low-tide elevation is relatively high, more freshwater discharges and less deep saltwater discharges. In contrast when low tides are very low, less freshwater discharges and more deep salt water discharges; (3) offshore inflow of saline water is largely insensitive to tides and the lunar cycle.

Applicability of Hydrogen Peroxide in Brown Tide Control – Culture and Microcosm Studies

PubMed Central

Randhawa, Varunpreet; Thakkar, Megha; Wei, Liping

2012-01-01

Brown tide algal blooms, caused by the excessive growth of Aureococcus anophagefferens, recur in several northeastern US coastal bays. Direct bloom control could alleviate the ecological and economic damage associated with bloom outbreak. This paper explored the effectiveness and safety of natural chemical biocide hydrogen peroxide (H2O2) for brown tide bloom control. Culture studies showed that H2O2 at 1.6 mg L−1 effectively eradicated high density A. anophagefferens within 24-hr, but caused no significant growth inhibition in the diatoms, prymnesiophytes, green algae and dinoflagellates of >2–3 μm cell sizes among 12 phytoplankton species tested over 1-week observation. When applied to brown tide bloom prone natural seawater in a microcosm study, this treatment effectively removed the developing brown tide bloom, while the rest of phytoplankton assemblage (quantified via HPLC based marker pigment analyses), particularly the diatoms and green algae, experienced only transient suppression then recovered with total chlorophyll a exceeding that in the controls within 72-hr; cyanobacteria was not eradicated but was still reduced about 50% at 72-hr, as compared to the controls. The action of H2O2 against phytoplankton as a function of cell size and cell wall structure, and a realistic scenario of H2O2 application were discussed. PMID:23082223

Florida Red Tide Toxins (Brevetoxins) and Longitudinal Respiratory Effects in Asthmatics.

PubMed

Bean, Judy A; Fleming, Lora E; Kirkpatrick, Barbara; Backer, Lorraine C; Nierenberg, Kate; Reich, Andrew; Cheng, Yung Sung; Wanner, Adam; Benson, Janet; Naar, Jerome; Pierce, Richard; Abraham, William M; Kirkpatrick, Gary; Hollenbeck, Julie; Zaias, Julia; Mendes, Eliana; Baden, Daniel G

2011-09-01

Having demonstrated significant and persistent adverse changes in pulmonary function for asthmatics after 1 hour exposure to brevetoxins in Florida red tide (Karenia brevis bloom) aerosols, we assessed the possible longer term health effects in asthmatics from intermittent environmental exposure to brevetoxins over 7 years. 125 asthmatic subjects were assessed for their pulmonary function and reported symptoms before and after 1 hour of environmental exposure to Florida red tide aerosols for upto 11 studies over seven years. As a group, the asthmatics came to the studies with normal standardized percent predicted pulmonary function values. The 38 asthmatics who participated in only one exposure study were more reactive compared to the 36 asthmatics who participated in ≥4 exposure studies. The 36 asthmatics participating in ≥4 exposure studies demonstrated no significant change in their standardized percent predicted pre-exposure pulmonary function over the 7 years of the study. These results indicate that stable asthmatics living in areas with intermittent Florida red tides do not exhibit chronic respiratory effects from intermittent environmental exposure to aerosolized brevetoxins over a 7 year period.

Differential results integrated with continuous and discrete gravity measurements between nearby stations

NASA Astrophysics Data System (ADS)

Xu, Weimin; Chen, Shi; Lu, Hongyan

2016-04-01

Integrated gravity is an efficient way in studying spatial and temporal characteristics of the dynamics and tectonics. Differential measurements based on the continuous and discrete gravity observations shows highly competitive in terms of both efficiency and precision with single result. The differential continuous gravity variation between the nearby stations, which is based on the observation of Scintrex g-Phone relative gravimeters in every single station. It is combined with the repeated mobile relative measurements or absolute results to study the regional integrated gravity changes. Firstly we preprocess the continuous records by Tsoft software, and calculate the theoretical earth tides and ocean tides by "MT80TW" program through high precision tidal parameters from "WPARICET". The atmospheric loading effects and complex drift are strictly considered in the procedure. Through above steps we get the continuous gravity in every station and we can calculate the continuous gravity variation between nearby stations, which is called the differential continuous gravity changes. Then the differential results between related stations is calculated based on the repeated gravity measurements, which are carried out once or twice every year surrounding the gravity stations. Hence we get the discrete gravity results between the nearby stations. Finally, the continuous and discrete gravity results are combined in the same related stations, including the absolute gravity results if necessary, to get the regional integrated gravity changes. This differential gravity results is more accurate and effective in dynamical monitoring, regional hydrologic effects studying, tectonic activity and other geodynamical researches. The time-frequency characteristics of continuous gravity results are discussed to insure the accuracy and efficiency in the procedure.

Absolute Sea Level Monitoring and Altimeter Calibration At Gavdos, Crete, Greece

NASA Astrophysics Data System (ADS)

Pavlis, E. C.; Gavdos Team

We present the mean sea level (MSL) monitoring aspect of the altimeter calibration fa- cility under deployment on western Crete and the isle of Gavdos. The Eastern Mediter- ranean area is one of great interest for its intense tectonic activity as well as for its regional oceanography. Recent observations have convincingly demonstrated the im- portance of that area for the regional meteorological and climatological changes. Tide- gauge monitoring with GPS has gained importance lately since tectonics contaminate the inferred sea level variations, and a global network of tide-gauges with long his- torical records can be used as satellite altimeter calibration sites for current and fu- ture missions (e.g. TOPEX/POSEIDON, GFO, JASON-1, ENVISAT, etc.). This is at present a common IOC-GLOSS-IGS effort, already underway (TIGA). Crete hosts two of the oldest tide-gauges in the regional network and our project will further ex- pand it to the south of the island with a new site on the isle of Gavdos, the southernmost European parcel of land. One component of our "GAVDOS" project is the repeated occupation of two already in existence tide-gauge sites at Souda Bay and Heraklion, and their tie to the new facility. We show here initial results from positioning of these sites and some of the available tidal records. Gavdos is situated under a ground-track crossing point of the present T/P and JASON-1 orbits. It is an ideal calibration site if the tectonic motions are monitored precisely and continuously. Our plans include the deployment of additional instrumentation at this site: GPS and DORIS beacons for positioning, transponders for direct calibration, water vapor radiometers, GPS-loaded buoys, airborne surveys with gravimeters and laser profiling lidars, etc., to ensure the best possible and most reliable results.

On the rate and causes of twentieth century sea-level rise.

PubMed

Miller, Laury; Douglas, Bruce C

2006-04-15

Both the rate and causes of twentieth century global sea-level rise (GSLR) have been controversial. Estimates from tide-gauges range from less than one, to more than two millimetre yr(-1). In contrast, values based on the processes mostly responsible for GSLR-mass increase (from mountain glaciers and the great high latitude ice masses) and volume increase (expansion due to ocean warming)-fall below this range. Either the gauge estimates are too high, or one (or both) of the component estimates is too low. Gauge estimates of GSLR have been in dispute for several decades because of vertical land movements, especially due to glacial isostatic adjustment (GIA). More recently, the possibility has been raised that coastal tide-gauges measure exaggerated rates of sea-level rise because of localized ocean warming. Presented here are two approaches to a resolution of these problems. The first is morphological, based on the limiting values of observed trends of twentieth century relative sea-level rise as a function of distance from the centres of the ice loads at last glacial maximum. This observational approach, which does not depend on a geophysical model of GIA, supports values of GSLR near 2 mm yr(-1). The second approach involves an analysis of long records of tide-gauge and hydrographic (in situ temperature and salinity) observations in the Pacific and Atlantic Oceans. It was found that sea-level trends from tide-gauges, which reflect both mass and volume change, are 2-3 times higher than rates based on hydrographic data which reveal only volume change. These results support those studies that put the twentieth century rate near 2 mm yr(-1), thereby indicating that mass increase plays a much larger role than ocean warming in twentieth century GSLR.

Mean relative sea level rise along the coasts of the China Seas from mid-20th to 21st centuries

NASA Astrophysics Data System (ADS)

Chen, Nan; Han, Guoqi; Yang, Jingsong

2018-01-01

Mean relative sea level (MRSL) rise has caused more frequent flooding in many parts of the world. The MRSL rise varies substantially from place to place. Here we use tide-gauge data and satellite measurements to examine past MRSL trends for the coasts of the China Seas. We then combine climate model output and satellite observations to provide MRSL projections in the 21st century. The MRSL trend based on tide-gauge data shows substantial regional variations, from 1 to 5 mm/yr. The vertical land motion (VLM) based on altimetry and tide-gauge (ATG) data indicates large land subsidence at some tide-gauge locations, consistent with the Global Positioning Systems (GPS)-based VLM but different significantly from small uplift estimated by a Glacial Isostatic Adjustment (GIA) model, which suggests other important factors causing the VLM instead of the GIA process. When GPS- or ATG-based VLM estimates are used, the projected MRSL rise between 1986-2005 and 2081-2100 at tide-gauge sites varies from 60 to 130 cm under the Representative Concentration Pathway 8.5 (RCP8.5) scenario of the Intergovernmental Panel on Climate Change (IPCC). Our projections are significantly larger than those of IPCC and other literature, as a result of accounting for the land subsidence derived from observations. Steric and dynamic ocean effects and land-ice melt effects are comparable (about 30 cm each) and do not vary much over the tide-gauge locations. The VLM effect varies from -10 to 60 cm. The projections between 1986-2005 and 2081-2100 under RCP4.5 show a similar spatial distribution to that under RCP8.5, with a smaller amount of rise by 18 cm on average for this region.

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

NASA Technical Reports Server (NTRS)

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

1996-01-01

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

Assessing the Contribution of Superconducting Gravimetry and GPS to Lunar Laser Ranging at Apache Point Observatory, New Mexico

NASA Astrophysics Data System (ADS)

Crossley, D. J.; Murphy, T.; Borsa, A. A.; Boy, J. P.

2016-12-01

Lunar laser ranging (LLR) is one of the main techniques used to test fundamental aspects of theories of the general relativity by monitoring the Earth-Moon distance to high accuracy. A current limitation of the APO processing is knowledge of the deformation of the telescope orientation at the sub-cm level in response to local loading and attraction effects. To this end in 2009 a superconducting gravimeter was installed at the Apache Point Observatory (APO), close to one of the Plate Boundary Observatory (PBO) GPS sites at the Sunspot solar observatory. APO is also visited regularly for AG measurements by the NGA. We present a comprehensive analysis of the 7 years of gravity data from APO, and the height variations from GPS, to give accurate estimates of the local elastic parameters and vertical variations common to both sites. By including the full spectrum (e.g. from tides, polar motion, and hydrology) of known loading and surface mass variability effects on gravity and GPS, we assess the vertical control that such geodetic techniques can bring to LLR measurements, and by extension, to other astronomical installations.

Modeling Storm-Influenced Suspended Particulate Matter Flocculation Using a Tide-Wave-Combined Biomineral Model.

PubMed

Chen, Peihung; Yu, Jason C S; Fettweis, Michael

2018-03-01

  Flocculation of suspended particulate matter (SPM) in marine and estuarine environments is a complex process that is influenced by physical, biological, and chemical mechanisms. The flocculation model of Maggi (2009) was adapted to simulate flocculation under various weather conditions and during different seasons. The adaptation incorporated the effect of tide-wave-combined turbulence on floc dynamics. The model was validated using in situ measurements of floc size and SPM concentration from the southern North Sea during both calm and storm conditions. The results show that tide-wave-combined turbulence needs to be incorporated when simulating flocculation in a tide-wave-dominated environment. The observed seasonal variations in floc size (Fettweis et al., 2014) were reproduced using varying values for various floc strengths in different seasons. The results revealed that the biological effect on floc strength, which enhances aggregation, is stronger during summer, indicating that floc strength in the model should be varied seasonally.

Computational modeling of unsteady loads in tidal boundary layers

NASA Astrophysics Data System (ADS)

Alexander, Spencer R.

As ocean current turbines move from the design stage into production and installation, a better understanding of oceanic turbulent flows and localized loading is required to more accurately predict turbine performance and durability. In the present study, large eddy simulations (LES) are used to measure the unsteady loads and bending moments that would be experienced by an ocean current turbine placed in a tidal channel. The LES model captures currents due to winds, waves, thermal convection, and tides, thereby providing a high degree of physical realism. Probability density functions, means, and variances of unsteady loads are calculated, and further statistical measures of the turbulent environment are also examined, including vertical profiles of Reynolds stresses, two-point correlations, and velocity structure functions. The simulations show that waves and tidal velocity had the largest impact on the strength of off-axis turbine loads. By contrast, boundary layer stability and wind speeds were shown to have minimal impact on the strength of off- axis turbine loads. It is shown both analytically and using simulation results that either transverse velocity structure functions or two-point transverse velocity spatial correlations are good predictors of unsteady loading in tidal channels.

Tidal effects on stratospheric temperature series derived from successive advanced microwave sounding units

PubMed Central

Keckhut, P; Funatsu, B M; Claud, C; Hauchecorne, A

2015-01-01

Stratospheric temperature series derived from the Advanced Microwave Sounding Unit (AMSU) on board successive NOAA satellites reveal, during periods of overlap, some bias and drifts. Part of the reason for these discrepancies could be atmospheric tides as the orbits of these satellites drifted, inducing large changes in the actual times of measurement. NOAA 15 and 16, which exhibit a long period of overlap, allow deriving diurnal tides that can correct such temperature drifts. The characteristics of the derived diurnal tides during summer periods is in good agreement with those calculated with the Global Scale Wave Model, indicating that most of the observed drifts are likely due to the atmospheric tides. Cooling can be biased by a factor of 2, if times of measurement are not considered. When diurnal tides are considered, trends derived from temperature lidar series are in good agreement with AMSU series. Future adjustments of temperature time series based on successive AMSU instruments will require considering corrections associated with the local times of measurement. PMID:26300563

Tidal effects on stratospheric temperature series derived from successive advanced microwave sounding units.

PubMed

Keckhut, P; Funatsu, B M; Claud, C; Hauchecorne, A

2015-01-01

Stratospheric temperature series derived from the Advanced Microwave Sounding Unit (AMSU) on board successive NOAA satellites reveal, during periods of overlap, some bias and drifts. Part of the reason for these discrepancies could be atmospheric tides as the orbits of these satellites drifted, inducing large changes in the actual times of measurement. NOAA 15 and 16, which exhibit a long period of overlap, allow deriving diurnal tides that can correct such temperature drifts. The characteristics of the derived diurnal tides during summer periods is in good agreement with those calculated with the Global Scale Wave Model, indicating that most of the observed drifts are likely due to the atmospheric tides. Cooling can be biased by a factor of 2, if times of measurement are not considered. When diurnal tides are considered, trends derived from temperature lidar series are in good agreement with AMSU series. Future adjustments of temperature time series based on successive AMSU instruments will require considering corrections associated with the local times of measurement.

Kingdom of the Tides.

ERIC Educational Resources Information Center

Carter, Samuel, III

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

The K1 internal tide simulated by a 1/10° OGCM

NASA Astrophysics Data System (ADS)

Li, Zhuhua; von Storch, Jin-Song; Müller, Malte

2017-05-01

This paper quantifies the K1 internal tide simulated by the 1/10° STORMTIDE model, which simultaneously resolves the eddying general circulation and tides. An evident feature of the K1 internal tide is the critical latitude φc at 30°, which in the STORMTIDE model is characterized by variations from a high energy level equatorward of 30° to a low energy level poleward of 30°. This critical latitude separates the internal tide dynamics into bottom-trapped (at latitudes |φ| > |φc|) and freely propagating (at |φ| < |φc|) motions, respectively. Both types of motions are examined. The bottom-trapping process reveals a gradual vertical decrease of wave energy away from the bottom. The vertical scale, over which the wave energy decrease occurs, is smaller in shallow than in deep water regions. For the freely propagating K1 internal tides, the STORMTIDE model is able to simulate the first three low modes, with the wavelengths ranging from 200-400 km, 100-200 km, to 60-120 km. These wavelength distributions reveal not only a zonal asymmetry but also a poleward increase up to φc, in particular in the Pacific. Such distributions indicate the impact of stratification N and the Coriolis frequency f on the wavelengths. The large wavelength gradient near φc is caused by the wavelength increase from finite values at subcritical latitudes to infinity at φc. Compared to the M2 internal tide, the lower K1 tidal frequency leads to a stronger role of f, hence a weaker effect of N, for the K1 internal tide.

Ocean Tide Influences on the Antarctic and Greenland Ice Sheets

NASA Astrophysics Data System (ADS)

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.

Report on Results of Borehole Tilt Measurements from the Charlevoix Observatory, Quebec

DTIC Science & Technology

1986-11-30

with long baseline tiltmeters ; any mechanical in- " _____,_ stability in the sensor or of the instrument/rock 3 ,.w ,-- interface produces...KEY WORDS (Continue on reverse side if necessary and identify by block number) ’Earth tides, tiltmeters , tidal loading, seismic activity, linear and...Water Table, Variations in a Seismically Active Region ip Quebec, Canada’ b iH-J. Kiimpel, J.A. Peters, and D.R. Bower. The array of three tiltmeters is

Atmospheric parameters in the mesosphere and lower thermosphere estimated using the Platteville, CO (40°N, 105°W) interferometric meteor radars

NASA Astrophysics Data System (ADS)

de La Pena, Santiago

Two interferometric meteor radars operating at different frequencies have been collecting data for several years at the Platteville Atmospheric Observatory. Meteor decay rates measured by the two systems have been analyzed with the purpose of comparing estimates of the ambipolar diffusion in meteors made with the radars. Ambipolar diffusion is the main dispersion process for meteors. Due to its dependence on atmospheric conditions, it has been used in recent studies to estimate meteor height, and atmospheric temperature and pressure. The results of the comparison made shed light on the conditions under which meteor decay rates can be used to estimate ambipolar diffusion. The response of the two systems to sporadic and shower meteor activity was analyzed and discussed. The radars show similar temporal distributions of the echoes detected from meteor trails, but present some differences in the spatial distribution. The Statistics of the data collected by the radars present differences in the meteor echo spatial distribution between sporadic meteor activity and meteor shower events. Observations of a strong 2001 Leonid meteor storm were presented. A difference in the maximum altitude at which the radars detect meteors was seen. This limit in height is caused by a geophysical effect commonly known as meteor echo ceiling. Six years of horizontal wind estimates near the mesopause obtained from the meteor radars have been analyzed with the objective of studying the spatial and seasonal variability of the main tidal components identified in the wind structure. Interferometric capabilities allowed the estimation of the location of the detected meteor echoes, effectively providing vertical profiles of horizontal wind estimates. Spectral and harmonic analyses were made on the horizontal wind averages, and the main tidal components were identified. Diurnal and semidiurnal oscillations were found persistently, and six, 8, and 48 hour oscillations were more intermittent, but still present. A monthly climatology of the diurnal and semidiurnal tides is presented. Vertical profiles provide insight on the source and propagation characteristics of the different tides. Monthly averages of the 12 and 24 hour tides amplitudes and phases were analyzed. An 8-hour tide and a 2-day wave were analyzed when present. A linear interaction of the diurnal and semidiurnal tides was suggested as a possible cause of an 8-hour oscillation. Tidal observations were compared with the National Center for Atmospheric Research's Global Scale Wave Model (GSWM). Good agreement was found for the diurnal tide phase progression below 85-90 km. The observed diurnal tide amplitude is significantly smaller than the model predictions, especially in the meridional direction, suggesting smaller non-migrating tides. The observed semidiurnal tide amplitudes are similar to the model predictions for fall and winter, although strong amplitudes are observed during the summer months, when almost no semidiurnal tide is predicted. The observed semidiurnal tide phase progression appears irregular at times, suggesting the presence of non-migrating semidiurnal tides.

Geochemical and geophysical examination of submarine groundwater discharge and associated nutrient loading estimates into Lynch Cove, Hood Canal, WA

USGS Publications Warehouse

Swarzenski, P.W.; Simonds, F.W.; Paulson, A.J.; Kruse, S.; Reich, C.

2007-01-01

Geochemical tracer data (i.e., 222Rn and four naturally occurring Ra isotopes), electromagnetic (EM) seepage meter results, and high-resolution, stationary electrical resistivity images were used to examine the bi-directional (i.e., submarine groundwater discharge and recharge) exchange of a coastal aquifer with seawater. Our study site for these experiments was Lynch Cove, the terminus of Hood Canal, WA, where fjord-like conditions dramatically limit water column circulation that can lead to recurring summer-time hypoxic events. In such a system a precise nutrient budget may be particularly sensitive to groundwater-derived nutrient loading. Shore-perpendicular time-series subsurface resistivity profiles show clear, decimeter-scale tidal modulation of the coastal aquifer in response to large, regional hydraulic gradients, hydrologically transmissive glacial terrain, and large (4-5 m) tidal amplitudes. A 5-day 222Rn time-series shows a strong inverse covariance between 222Rn activities (0.5−29 dpm L-1) and water level fluctuations, and provides compelling evidence for tidally modulated exchange of groundwater across the sediment/water interface. Mean Rn-derived submarine groundwater discharge (SGD) rates of 85 ± 84 cm d-1 agree closely in the timing and magnitude with EM seepage meter results that showed discharge during low tide and recharge during high tide events. To evaluate the importance of fresh versus saline SGD, Rn-derived SGD rates (as a proxy of total SGD) were compared to excess 226Ra-derived SGD rates (as a proxy for the saline contribution of SGD). The calculated SGD rates, which include a significant (>80%) component of recycled seawater, are used to estimate associated nutrient (NH4+, Si, PO43-, NO3 + NO2, TDN) loads to Lynch Cove. The dissolved inorganic nitrogen (DIN = NH4 + NO2 + NO3) SGD loading estimate of 5.9 × 104 mol d-1 is 1−2 orders of magnitude larger than similar estimates derived from atmospheric deposition and surface water runoff, respectively.

How Tidal Forces Cause Ocean Tides in the Equilibrium Theory

ERIC Educational Resources Information Center

Ng, Chiu-king

2015-01-01

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

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

EPA Science Inventory

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

Numerical simulations of river discharges, nutrient flux and nutrient dispersal in Jakarta Bay, Indonesia.

PubMed

van der Wulp, Simon A; Damar, Ario; Ladwig, Norbert; Hesse, Karl-J

2016-09-30

The present application of numerical modelling techniques provides an overview of river discharges, nutrient flux and nutrient dispersal in Jakarta Bay. A hydrological model simulated river discharges with a total of 90 to 377m(3)s(-1) entering Jakarta Bay. Daily total nitrogen and total phosphorus loads ranged from 40 to 174tons and 14 to 60tons, respectively. Flow model results indicate that nutrient gradients are subject to turbulent mixing by tides and advective transport through circulation driven by wind, barotropic and baroclinic pressure gradients. The bulk of nutrient loads originate from the Citarum and Cisadane rivers flowing through predominantly rural areas. Despite lower nutrient loads, river discharges from the urban area of Jakarta exhibit the highest impact of nutrient concentrations in the near shore area of Jakarta Bay and show that nutrient concentrations were not only regulated by nutrient loads but were strongly regulated by initial river concentrations and local flow characteristics. Copyright © 2016 Elsevier Ltd. All rights reserved.

The IERS Special Bureau for Tides

NASA Technical Reports Server (NTRS)

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

2002-01-01

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

Formation of Tidal Captures and Gravitational Wave Inspirals in Binary-single Interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samsing, Johan; MacLeod, Morgan; Ramirez-Ruiz, Enrico

We perform the first systematic study of how dynamical stellar tides and general relativistic (GR) effects affect the dynamics and outcomes of binary-single interactions. For this, we have constructed an N -body code that includes tides in the affine approximation, where stars are modeled as self-similar ellipsoidal polytropes, and GR corrections using the commonly used post-Newtonian formalism. Using this numerical formalism, we are able resolve the leading effect from tides and GR across several orders of magnitude in both stellar radius and initial target binary separation. We find that the main effect from tides is the formation of two-body tidalmore » captures that form during the chaotic and resonant evolution of the triple system. The two stars undergoing the capture spiral in and merge. The inclusion of tides can thus lead to an increase in the stellar coalescence rate. We also develop an analytical framework for calculating the cross section of tidal inspirals between any pair of objects with similar mass. From our analytical and numerical estimates, we find that the rate of tidal inspirals relative to collisions increases as the initial semimajor axis of the target binary increases and the radius of the interacting tidal objects decreases. The largest effect is therefore found for triple systems hosting white dwarfs and neutron stars (NSs). In this case, we find the rate of highly eccentric white dwarf—NS mergers to likely be dominated by tidal inspirals. While tidal inspirals occur rarely, we note that they can give rise to a plethora of thermonuclear transients, such as Ca-rich transients.« less

Computer algorithm for analyzing and processing borehole strainmeter data

USGS Publications Warehouse

Langbein, John O.

2010-01-01

The newly installed Plate Boundary Observatory (PBO) strainmeters record signals from tectonic activity, Earth tides, and atmospheric pressure. Important information about tectonic processes may occur at amplitudes at and below tidal strains and pressure loading. If incorrect assumptions are made regarding the background noise in the strain data, then the estimates of tectonic signal amplitudes may be incorrect. Furthermore, the use of simplifying assumptions that data are uncorrelated can lead to incorrect results and pressure loading and tides may not be completely removed from the raw data. Instead, any algorithm used to process strainmeter data must incorporate the strong temporal correlations that are inherent with these data. The technique described here uses least squares but employs data covariance that describes the temporal correlation of strainmeter data. There are several advantages to this method since many parameters are estimated simultaneously. These parameters include: (1) functional terms that describe the underlying error model, (2) the tidal terms, (3) the pressure loading term(s), (4) amplitudes of offsets, either those from earthquakes or from the instrument, (5) rate and changes in rate, and (6) the amplitudes and time constants of either logarithmic or exponential curves that can characterize postseismic deformation or diffusion of fluids near the strainmeter. With the proper error model, realistic estimates of the standard errors of the various parameters are obtained; this is especially critical in determining the statistical significance of a suspected, tectonic strain signal. The program also provides a method of tracking the various adjustments required to process strainmeter data. In addition, the program provides several plots to assist with identifying either tectonic signals or other signals that may need to be removed before any geophysical signal can be identified.

Sediment concentrations and loads in the Loxahatchee River estuary, Florida, 1980-82

USGS Publications Warehouse

Sonntag, Wayne H.; McPherson, Benjamin F.

1984-01-01

This study was conducted to estimate the magnitude of sediment loads and the general spatial and temporal patterns of sediment transport in the Loxahatchee River estuary, Florida. Mean concentrations of suspended sediment generally were higher in the Jupiter Inlet area than in the remainder of the embayment area. Concentrations of suspended sediment varied with season and weather conditions. Concentrations in selected tributaries following Tropical Storm Dennis in August 1981 immediately increased as much as 16 times over concentrations before the storm. Suspended-sediment loads from the tributaries were also highly seasonal and storm related. During a 61-day period of above-average rainfall that included Tropical Storm Dennis, 5 major tributaries discharged 926 tons (short) of suspended sediment to the estuary, accounting for 74 percent of the input for the 1981 water year and 49 percent of the input for the 20-month study period. Suspended-sediment loads at Jupiter Inlet and at the mouth of the estuary embayment on both incoming and outgoing tides far exceeded tributary loads, but the direction of long-term, net tidal transport was not determined. (USGS)

Wavelet filter analysis of local atmospheric pressure effects in the long-period tidal bands

NASA Astrophysics Data System (ADS)

Hu, X.-G.; Liu, L. T.; Ducarme, B.; Hsu, H. T.; Sun, H.-P.

2006-11-01

It is well known that local atmospheric pressure variations obviously affect the observation of short-period Earth tides, such as diurnal tides, semi-diurnal tides and ter-diurnal tides, but local atmospheric pressure effects on the long-period Earth tides have not been studied in detail. This is because the local atmospheric pressure is believed not to be sufficient for an effective pressure correction in long-period tidal bands, and there are no efficient methods to investigate local atmospheric effects in these bands. The usual tidal analysis software package, such as ETERNA, Baytap-G and VAV, cannot provide detailed pressure admittances for long-period tidal bands. We propose a wavelet method to investigate local atmospheric effects on gravity variations in long-period tidal bands. This method constructs efficient orthogonal filter bank with Daubechies wavelets of high vanishing moments. The main advantage of the wavelet filter bank is that it has excellent low frequency response and efficiently suppresses instrumental drift of superconducting gravimeters (SGs) without using any mathematical model. Applying the wavelet method to the 13-year continuous gravity observations from SG T003 in Brussels, Belgium, we filtered 12 long-period tidal groups into eight narrow frequency bands. Wavelet method demonstrates that local atmospheric pressure fluctuations are highly correlated with the noise of SG measurements in the period band 4-40 days with correlation coefficients higher than 0.95 and local atmospheric pressure variations are the main error source for the determination of the tidal parameters in these bands. We show the significant improvement of long-period tidal parameters provided by wavelet method in term of precision.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valsecchi, F.; Farr, W. M.; Willems, B.

2013-08-10

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.more » 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 {beta} 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.« less

Numerical assessment of factors affecting nonlinear internal waves in the South China Sea

NASA Astrophysics Data System (ADS)

Li, Qiang

2014-02-01

Nonlinear internal waves in the South China Sea exhibit diverse characteristics, which are associated with the complex conditions in Luzon Strait, such as the double ridge topography, the Earth’s rotation, variations in stratification and the background current induced by the Kuroshio. These effects are individually assessed using the MITgcm. The performance of the model is first validated through comparison with field observations. Because of in-phased ray interaction, the western ridge in Luzon Strait intensifies the semidiurnal internal tides generated from the eastern ridge, thus reinforcing the formation of nonlinear internal waves. However, the ray interaction for K1 forcing becomes anti-phased so that the K1 internal tide generation is reduced by the western ridge. Not only does the rotational dispersion suppress internal tide generation, it also inhibits nonlinear steepening and consequent internal solitary wave formation. As a joint effect, the double ridges and the rotational dispersion result in a paradoxical phenomenon: diurnal barotropic tidal forcing is dominant in Luzon Strait, but semidiurnal internal tides prevail in the deep basin of the South China Sea. The seasonal variation of the Kuroshio is consistent with the seasonal appearance of nonlinear internal waves in the South China Sea. The model results show that the westward inflow due to the Kuroshio intrusion reduces the amplitude of internal tides in the South China Sea, causing the weakening or absence of internal solitary waves. Winter stratification cannot account for the significant reduction of nonlinear internal waves, because the amplitude growth of internal tides due to increased thermocline tilting counteracts the reduced nonlinearity caused by thermocline deepening.

The harmonic development of the Earth tide generating potential due to the direct effect of the planets

NASA Astrophysics Data System (ADS)

Hartmann, Torsten; Wenzel, Hans-Georg

1994-09-01

The time-harmonic development of the Earth tide generating potential due to the direct effect of the planets Venus, Jupiter, Mars, Mercury and Saturn has been computed. The catalog of the fully normalized potential coefficients contains 1483 waves. It is based on the DE102 numerical ephemeris of the planets between years 1900 and 2200. Gravity tides due to the planets computed from the catalog at the surface of the Earth have an accuracy of about 0.027 pm/sq s (1 pm/sq s = 10(exp -12) m/sq s = 0.1 ngal) rms and 0.160 / 0.008 pm/sq s at maximum in time / frequency domain using the new benchmark tidal gravity series (Wenzel 1994).

Response of well aquifer systems to Earth tides: Problem revisited

USGS Publications Warehouse

Hsieh, Paul A.; Bredehoeft, John D.; Rojstaczer, Stuart

1988-01-01

Two recent works cause us to reexamine Bredehoeft's (1967) analysis of earthtide response of water wells. Narasimhan et al. (1984) raise several questions regarding Bredehoeft's (1967) analysis and suggest that the analysis is internally inconsistent. They argue that one cannot directly estimate the specific storage, which characterizes the drained behavior of a porous medium, from earth tide response, which is an undrained phenomenon. We resolve the questions raised by Narasimhan et al. (1984) and show that Bredehoeft's analysis is internally consistent. In addition, we show that it is possible to determine the specific storage from undrained loading. While Bredehoeft's analysis is somewhat heuristic and neglects grain compressibility, Van der Kamp and Gale (1983) present a more rigorous analysis that is based on Biot's (1941) constitutive relationships and accounts for grain compressibility. However, their results reduce to Bredehoeft's results when grains are assumed incompressible. This suggests that Bredehoeft's analysis has incorporated all the essential features of Biot's relationships except for grain compressibility. Upon reexamining Bredehoeft's analysis we find that this is indeed the case.

Tide-related variability of TAG hydrothermal activity observed by deep-sea monitoring system and OBSH

NASA Astrophysics Data System (ADS)

Fujioka, Kantaro; Kobayashi, Kazuo; Kato, Kazuhiro; Aoki, Misumi; Mitsuzawa, Kyohiko; Kinoshita, Masataka; Nishizawa, Azusa

1997-12-01

Hydrothermal activities were monitored by an ocean bottom seismometer with hydrophone (OBSH) and a composite measuring system (Manatee) including CTD, current meter, transmission meter and cameras at a small depression on the TAG hydrothermal mound in the Mid-Atlantic Ridge. Low-frequency pressure pulses detected by the hydrophone with semi-diurnal periodicity seem to correspond to cycles of hydrothermal upflow from a small and short-lived smoker vent close to the observing site. The peaks of pressure pulses are synchronous with the maximum gradient of areal strain decrease due to tidal load release. Microearthquakes with very near epicenters occur sporadically and do not appear to be directly correlatable to hydrothermal venting. Temporal variations in bottom water temperature also have semi-diurnal periodicity but are more complicated than the pressure events. Temperatures may be affected both by upwelling of hot water and by lateral flow of the bottom current changing its directions with ocean tide.

In search of periodic signatures in IGS REPRO1 solution

NASA Astrophysics Data System (ADS)

Mtamakaya, J. D.; Santos, M. C.; Craymer, M. R.

2010-12-01

We have been looking for periodic signatures in the REPRO1 solution recently released by the IGS. At this stage, a selected sub-set of IGS station time series in position and residual domain are under harmonic analysis. We can learn different things from this analysis. From the position domain, we can learn more about actual station motions. From the residual domain, we can learn more about mis-modelled or un-modelled errors. As far as error sources are concerned, we have investigated effects that may be due to tides, atmospheric loading, definition of the position of the figure axis and GPS constellation geometry. This poster presents and discusses our findings and presents insights on errors that need to be modelled or have their models improved.

Applying spectral data analysis techniques to aquifer monitoring data in Belvoir Ranch, Wyoming

NASA Astrophysics Data System (ADS)

Gao, F.; He, S.; Zhang, Y.

2017-12-01

This study uses spectral data analysis techniques to estimate the hydraulic parameters from water level fluctuation due to tide effect and barometric effect. All water level data used in this study are collected in Belvoir Ranch, Wyoming. Tide effect can be not only observed in coastal areas, but also in inland confined aquifers. The force caused by changing positions of sun and moon affects not only ocean but also solid earth. The tide effect has an oscillatory pumping or injection sequence to the aquifer, and can be observed from dense water level monitoring. Belvoir Ranch data are collected once per hour, thus is dense enough to capture the tide effect. First, transforming de-trended data from temporal domain to frequency domain with Fourier transform method. Then, the storage coefficient can be estimated using Bredehoeft-Jacob model. After this, analyze the gain function, which expresses the amplification and attenuation of the output signal, and derive barometric efficiency. Next, find effective porosity with storage coefficient and barometric efficiency with Jacob's model. Finally, estimate aquifer transmissivity and hydraulic conductivity using Paul Hsieh's method. The estimated hydraulic parameters are compared with those from traditional pumping data estimation. This study proves that hydraulic parameter can be estimated by only analyze water level data in frequency domain. It has the advantages of low cost and environmental friendly, thus should be considered for future use of hydraulic parameter estimations.

Numerical modeling of short-term slow slip events in the Shikoku region considering the effect of earth tides and plate configuration

NASA Astrophysics Data System (ADS)

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

2016-12-01

Several studies reported that occurrence of slow slip events (SSEs) in the Nankai region is affected by earth tides (e.g., Nakata et al., 2008; Ide and Tanaka, 2014; Yabe et al., 2015). The tidal effect on the SSEs is also examined by numerical studies (e.g., Hawthorne and Rubin, 2013). In our previous study, repeating SSEs in the Shikoku region are numerically reproduced, incorporating the actual plate configuration (Matsuzawa et al., 2013). In this study, we examined the behavior of SSEs in the Shikoku region, considering stress perturbation by earth tides. Our numerical model is similar to our previous study (Matsuzawa et al., 2013). A plate interface is expressed by small triangular elements. A rate- and state-dependent friction law (RS-law) with cutoff velocities is adopted as the friction law on each element. We assumed that (a-b) value in the RS-law is negative within the short-term SSE region, and positive outside the region. 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 short-term SSEs. Calculating stress change by earth tides as in Yabe et al., (2015), we assume that the stress change is represented by periods of 10 major tides. Incorporating this stress perturbation, we calculate the evolution of slip on the plate interface. In the numerical result, repeating short-term SSEs are reproduced in the short-term SSE region. Recurrent intervals of SSEs at an isolated patch (e.g., northeastern Shikoku) have small fluctuation. Introducing tidal effect, peak velocity becomes faster than that in the case without tidal effect. On the other hand, the difference of peak velocities is not clear between the cases with and without tidal effect at widely connected SSE region (e.g., western Shikoku), as the intervals and peak velocities of SSEs are largely fluctuated in both cases. Hirahara (2016) suggested that the recurrence interval of events is synchronized to the period of external force, when these two periods are close. In our result, recurrence intervals of SSEs at the isolated patch seem to be less fluctuated in the case with tides, and perhaps, may be attracted to the period of integer multiple of the long period tides (e.g., Mf), although further examination is required to confirm this interpretation.

Sea-level rise impacts on the tides of the European Shelf

NASA Astrophysics Data System (ADS)

Idier, Déborah; Paris, François; Cozannet, Gonéri Le; Boulahya, Faiza; Dumas, Franck

2017-04-01

Sea-level rise (SLR) can modify not only total water levels, but also tidal dynamics. Several studies have investigated the effects of SLR on the tides of the western European continental shelf (mainly the M2 component). We further investigate this issue using a modelling-based approach, considering uniform SLR scenarios from -0.25 m to +10 m above present-day sea level. Assuming that coastal defenses are constructed along present-day shorelines, the patterns of change in high tide levels (annual maximum water level) are spatially similar, regardless of the magnitude of sea-level rise (i.e., the sign of the change remains the same, regardless of the SLR scenario) over most of the area (70%). Notable increases in high tide levels occur especially in the northern Irish Sea, the southern part of the North Sea and the German Bight, and decreases occur mainly in the western English Channel. These changes are generally proportional to SLR, as long as SLR remains smaller than 2 m. Depending on the location, they can account for +/-15% of regional SLR. High tide levels and the M2 component exhibit slightly different patterns. Analysis of the 12 largest tidal components highlights the need to take into account at least the M2, S2, N2, M4, MS4 and MN4 components when investigating the effects of SLR on tides. Changes in high tide levels are much less proportional to SLR when flooding is allowed, in particular in the German Bight. However, some areas (e.g., the English Channel) are not very sensitive to this option, meaning that the effects of SLR would be predictable in these areas, even if future coastal defense strategies are ignored. Physically, SLR-induced tidal changes result from the competition between reductions in bed friction damping, changes in resonance properties and increased reflection at the coast, i.e., local and non-local processes. A preliminary estimate of tidal changes by 2100 under a plausible non-uniform SLR scenario (using the RCP4.5 scenario) is provided. Though the changes display similar patterns, the high water levels appear to be sensitive to the non-uniformity of SLR.

TIDE TOOL: Open-Source Sea-Level Monitoring Software for Tsunami Warning Systems

NASA Astrophysics Data System (ADS)

Weinstein, S. A.; Kong, L. S.; Becker, N. C.; Wang, D.

2012-12-01

A tsunami warning center (TWC) typically decides to issue a tsunami warning bulletin when initial estimates of earthquake source parameters suggest it may be capable of generating a tsunami. A TWC, however, relies on sea-level data to provide prima facie evidence for the existence or non-existence of destructive tsunami waves and to constrain tsunami wave height forecast models. In the aftermath of the 2004 Sumatra disaster, the International Tsunami Information Center asked the Pacific Tsunami Warning Center (PTWC) to develop a platform-independent, easy-to-use software package to give nascent TWCs the ability to process WMO Global Telecommunications System (GTS) sea-level messages and to analyze the resulting sea-level curves (marigrams). In response PTWC developed TIDE TOOL that has since steadily grown in sophistication to become PTWC's operational sea-level processing system. TIDE TOOL has two main parts: a decoder that reads GTS sea-level message logs, and a graphical user interface (GUI) written in the open-source platform-independent graphical toolkit scripting language Tcl/Tk. This GUI consists of dynamic map-based clients that allow the user to select and analyze a single station or groups of stations by displaying their marigams in strip-chart or screen-tiled forms. TIDE TOOL also includes detail maps of each station to show each station's geographical context and reverse tsunami travel time contours to each station. TIDE TOOL can also be coupled to the GEOWARE™ TTT program to plot tsunami travel times and to indicate the expected tsunami arrival time on the marigrams. Because sea-level messages are structured in a rich variety of formats TIDE TOOL includes a metadata file, COMP_META, that contains all of the information needed by TIDE TOOL to decode sea-level data as well as basic information such as the geographical coordinates of each station. TIDE TOOL can therefore continuously decode theses sea-level messages in real-time and display the time-series data in the GUI as well. This GUI also includes mouse-clickable functions such as zooming or expanding the time-series display, measuring tsunami signal characteristics (arrival time, wave period and amplitude, etc.), and removing the tide signal from the time-series data. De-tiding of the time series is necessary to obtain accurate measurements of tsunami wave parameters and to maintain accurate historical tsunami databases. With TIDE TOOL, de-tiding is accomplished with a set of tide harmonic coefficients routinely computed and updated at PTWC for many of the stations in PTWC's inventory (~570). PTWC also uses the decoded time series files (previous 3-5 days' worth) to compute on-the-fly tide coefficients. The latter is useful in cases where the station is new and a long-term stable set of tide coefficients are not available or cannot be easily obtained due to various non-astronomical effects. The international tsunami warning system is coordinated globally by the UNESCO IOC, and a number of countries in the Pacific and Indian Ocean, and Caribbean depend on Tide Tool to monitor tsunamis in real time.

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

NASA Technical Reports Server (NTRS)

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.

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

PubMed

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.

Study on Interaction Between Diurnal Tide and Atmospheric Aerosols Observed by Mars Climate Sounder

NASA Astrophysics Data System (ADS)

Wu, Z.; Li, T.

2016-12-01

The increased local time coverage observed by Mars Climate Sounder (MCS) on board Mars Reconnaissance Orbiter (MRO) can enable direct extraction of thermal tides in Mars middle atmosphere with reduced aliasing. Using temperature profiles from Mars year (MY) 30 to 32, we study the latitudinal and seasonal variations of tides and stationary planetary waves with zonal wave numbers s = 1-3. The amplitude of the migrating diurnal tide (DW1) has strong semiannual variations both in the equatorial region and in the Southern Hemisphere (SH) middle latitudes. Aerosols widely distributed in the atmosphere of Mars, namely, dust and water ice also show apparent diurnal variations, which may be caused by a dynamical process of tidal vertical wind. Tidal response in dust abundance indicates an annual variation with maximum amplitude in aphelion seasons while the background abundance of dust peaks in perihelion seasons when global dust storm occurs frequently, which suggests that extremely large abundance of dust may restrain its own tidal response. Water ice abundance in the middle latitudes has a semiannual variation which is similar to the thermal diurnal tide. In addition, the diurnal heating rate of aerosols is calculated and Hough decomposition is performed to estimate the radiative effect of aerosols on diurnal tide.

QBO Generated Inter-annual Variations of the Diurnal Tide in the Mesosphere

NASA Technical Reports Server (NTRS)

Mayr, Hans G.; Mengel, John G.

2004-01-01

We report results from a study with the Numerical Spectral Model (NSM), which produces in the d i d tide significant inter-annual variations. Applying Hines' Doppler Spread Parameterization (DPS), small-scale gravity waves (GW) drive the Quasi-biennial Oscillation (QBO) and Semi-annual Oscillation (SAO). With a GW source that peaks at the equator and is taken to be isotropic and independent of season, the NSM generates a QBO with variable periods around 27 months and zonal wind amplitudes close to 20 m/s at 30 lan, As reported earlier, the NSM reproduces the observed equinoctial maxima in the diurnal tide at altitudes around 95 km. In the present paper it is shown that the QBO modulates the tide such that the seasonal amplitude maxima can vary from one year to another by as much as 30%. Since the period of the QBO is variable, its phase relative to the seasonal cycle changes. The magnitude of the QBO modulation of the tide thus varies considerably as our long-term model simulation shows. To shed light on the underlying mechanisms, we discuss (a) the relative importance of the linearized advection terms that involve the meridional and vertical winds of the diurnal tide and (b) the effects momentum deposition from GWs filtered by the QBO.

The District: A History of the Philadelphia District, U.S. Army Corps of Engineers, 1866-1971

DTIC Science & Technology

1974-01-01

events with the irresistible momentum of a juggernaut. With his partners, Erskine Hazard and George Hauto, White organized the Lehigh Navigation...within 3 years. White and Hazard explored and surveyed the river from Stoddartsville to Easton in the Spring of 1818, on foot and using levels 36...loaded. There were places where ships could ground in the Delaware channel without benefit of a full tide. One such hazard was at Schooner Ledge

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

EPA Science Inventory

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

EFFECTS OF RED TIDE (KARENIA BREVIS) ON PISCIVOROUS BIRDS IN SARASOTA BAY, FLORIDA

EPA Science Inventory

Red tide will cause changes in the abundance and distribution of fishes, which will be accompanied by changes in the patterns of habitat use by birds. Birds will be affected by exposure to brevetoxin via their prey and they will also face decreased availability of prey during...

Hydrology of Fritchie Marsh, coastal Louisiana

USGS Publications Warehouse

Kuniansky, E.L.

1985-01-01

Fritchie Marsh, near Slidell, Louisiana, is being considered as a disposal site for sewage effluent. A two-dimensional, finite element, surface water modeling systems was used to solve the shallow water equations for flow. Factors affecting flow patterns are channel locations, inlets, outlets, islands, marsh vegetation, marsh geometry, stage of the West Pearl River, flooding over the lower Pearl River basin, gravity tides, wind-induced currents, and sewage discharge to the marsh. Four steady-state simulations were performed for two hydrologic events at two rates of sewage discharge. The events, near tide with no wind or rain and neap tide with a tide differential across the marsh, were selected as worst-case events for sewage effluent dispersion and were assumed as steady state events. Because inflows and outflows to the marsh are tidally affected, steady state simulations cannot fully define the hydraulic characteristics of the marsh for all hydrologic events. Model results and field data indicate that, during near tide with little or no rain, large parts of the marsh are stagnant; and sewage effluent, at existing and projected flows, has minimal effect on marsh flows. (USGS)

Evidence for Excitation of Polar Motion by Fortnightly Ocean Tides

NASA Technical Reports Server (NTRS)

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.

Identification of Individual Efficiency for Barometric Pressure and Ocean Tide Load Simultaneously Acted on Deep Aquifers Adjacent to the West Pacific Ocean

NASA Astrophysics Data System (ADS)

Shih, David Ching-Fang

2018-06-01

Groundwater fluctuation usually reflects the property of aquifer in nature. Actually, water level change can be caused not only by barometric pressure changes resulted from atmospheric motion, but also by the tidal effect from nearby marine system or water body. In confined aquifer, an increase in barometric pressure usually will cause a decrease in water level in well to an amount described by the barometric efficiency. The barometric efficiency can be also used as a correction factor to remove barometric effects on water levels in wells during an aquifer test. With the rise of the tidal sea on the coastal aquifer, it indicates that there will be compensating increases of water pressure and stress in the skeleton of aquifer. External forcing on groundwater level in the coastal aquifer, such as barometric effect and tidal sea, usually affect the water level to fluctuate with different phases to some extent. An adaptive adjustment to remove the combination of barometric and oceanic tidal efficiency is presented in this study. This research suggests that the presented formula can simultaneously identify the individual efficiency for barometric effect and load of tidal sea considering their combined observation of groundwater level in aquifer system. An innovative application has been demonstrated for the deep aquifers adjacent to the West Pacific Ocean.

The Data Base of the International Geodynamics and Earth Tide Service (IGETS)

NASA Astrophysics Data System (ADS)

Voigt, Christian; Förste, Christoph; Wziontek, Hartmut; Crossley, David; Meurers, Bruno; Pálinkáš, Vojtech; Hinderer, Jacques; Boy, Jean-Paul; Barriot, Jean-Pierre; Sun, Heping

2017-04-01

The International Geodynamics and Earth Tide Service (IGETS) was established in 2015 by the International Association of Geodesy (IAG). IGETS continues the activities of the Global Geodynamics Project (GGP, 1997-2015) to provide support to geodetic and geophysical research activities using superconducting gravimeter data within the context of an international network. The primary objective of IGETS is to provide a service for continuous ground based measurements to monitor temporal variations of the Earth's gravity field and deformation of the Earth's surface by long term records from ground gravimeters, tiltmeters, strainmeters and other geodynamic sensors. IGETS also continues the activities of the International Center for Earth Tides (ICET), in particular, in collecting, archiving and distributing Earth tide records from long series of the various geodynamic sensors. This presentation introduces the IGETS data base hosted by GFZ and accessible via http://igets.gfz-potsdam.de to the geodetic and geodynamics community as well as to all other interested data producers and users. At present, records from superconducting gravimeters at 34 stations worldwide are available. Level 1 products are raw gravity and local pressure records decimated at 1 minute samples. As a new feature, records with 1 or 2 seconds samples are already provided for a few stations. Level 2 products consist of gravity and pressure data corrected for instrumental perturbations and ready for tidal analysis, which are derived from Level 1 datasets and computed by the University of French Polynesia (Tahiti, French Polynesia). Gravity residuals after particular geophysical corrections (including solid Earth tides, polar motion, tidal and non-tidal loading effects) considered as Level 3 products are derived from Level 2 datasets and computed by EOST (Ecole et Observatoire des Sciences de la Terre, Strasbourg, France). The IGETS data sets are stored by GFZ on a FTP server and are freely available after a compulsory user registration. A major benefit of IGETS is the provision of digital object identifiers (DOI) by the research repository of GFZ Data Services for the data sets of every station. This ensures a long term storage and an increased visibility as part of an international network but also a proper data citation. At present, the IGETS data base is supported by 24 data producers providing records to almost 100 registered users. All relevant information on the data base, i.e., data availability and access, stations and sensors, conventional data formats, etc. are compiled in a specific scientific technical report (see http://doi.org/10.2312/GFZ.b103-16087). As IGETS is seeking for providing all kinds of long-term geodynamic time series, interested station operators are cordially invited to provide their data sets to the IGETS data base and, in return, benefit from being part of the IAG service IGETS.

Tides and deltaic morphodynamics

NASA Astrophysics Data System (ADS)

Plink-Bjorklund, Piret

2016-04-01

Tide-dominated and tide-influenced deltas are not widely recognized in the ancient record, despite the numerous modern and Holocene examples, including eight of the twelve modern largest deltas in the world, like the Ganges-Brahmaputra, Amazon, Chang Jiang, and Irrawadi. Furthermore, tide-dominated or tide-influenced deltas are suggested to be more common in inner-shelf or embayment settings rather than close to or at a shelf edge, primarily because wave energy is expected to be higher and tidal energy lower in outer shelf and shelf-edge areas. Thus, most shelf-edge deltas are suggested to be fluvial or wave dominated. However, there are ancient examples of tide-influenced shelf-edge deltas, indicating that the controls on tidal morphodynamics in deltas are not yet well understood. This paper asks the following questions: (1) How do tides influence delta deposition, beyond creating recognizable tidal facies? (2) Does tidal reworking create specific geometries in delta clinoforms? (3) Does tidal reworking change progradation rates of deltas? (4) Is significant tidal reworking of deltas restricted to inner-shelf deltas only? (5) What are the conditions at which deltas may be tidally influenced or tide-dominated in outer-shelf areas or at the shelf edge? (6) What are the main morphodynamic controls on the degree of tidal reworking of deltas? The paper utilizes a dataset of multiple ancient and modern deltas, situated both on the shelf and shelf edge. We show that beyond the commonly recognized shore-perpendicular morphological features and the recognizable tidal facies, the main effects of tidal reworking of deltas are associated with delta clinoform morphology, morphodynamics of delta lobe switching, delta front progradation rates, and the nature of the delta plain. Strong tidal influence is here documented to promote subaqueous, rapid progradation of deltas, by efficiently removing sediment from river mouth and thus reducing mouth bar aggradation and fluvial delta plain construction rates. Such subaqueous progradation of the delta front is decoupled from shoreline progradation. The delta plain of such tide-dominated deltas consists of a few distributary channels and tidal flats on top of the emerged tidal bars. The delta front clinoforms become gentler and longer, as ebb tidal currents together with river effluent efficiently transport sediment to the basin. Tide-dominated deltas tend to maintain a funnel shape and show low lobe switching rates, compared to fluvial-dominated and tide-influenced deltas. The funnel and thus river mouth position is further stabilized by fine-grained sediment accumulation on marginal tidal flats due to the flood current sediment transport. However, all these effect weaken as the deltas prograde to the shelf edge, due to the loss of vertical (and lateral) restriction and tidal amplification. Here significant tidal reworking tends to be restricted to topographic irregularities, caused by incision, delta-lobe or mouth bar deposition and avulsions, or tectonic processes. The role of such topographic restrictions is twofold, by reducing wave energy and amplifying tidal energy.

Monitoring and Deformation Analysis of Groynes Using Tls at the River Elbe

NASA Astrophysics Data System (ADS)

Tschirschwitz, F.; Mechelke, K.; Jansch, H.; Kersten, T. P.

2016-06-01

To enter the Port of Hamburg, one of Europe's busiest ports all vessels need to navigate around 145 km along the Elbe river, a tide influenced navigation channel. To protect the Elbe shoreline from erosion and to channel the waterway groynes (rigid hydraulic structures) have been built along the river. In the past years since ca. 2001 there has been a large increase in damage of groynes structural integrity at parts of the German waterways. The reason for this was determined in the ever growing size of container vessels passing by and inducing long periodical primary waves which have such a force that they erode the groynes rock structure. To analyse and improve the groynes structural resistance for vessel-induced long periodical wave loads an in-situ study is carried out at Juelssand, located at the Elbe river estuary. Over a period of two years the change of the geometrical structure of two different groyne shapes is monitored automatically by utilising two terrestrial laser scanners mounted in protective housings, located each on a 12 m high platform. The self-contained monitoring systems perform scanning of the two groynes one to two times a day at low tide, as the structures are fully submerged at high tide. The long-periodical wave loads are also determined using pressure sensors in each groyne. To correlate the captured data with vessel events and analyse the effects, vessel related parameters are recorded utilizing the Automatic Identification System (AIS). This paper describes the automated processes for the data acquisition and focusses on the deformation that is calculated using current, extended and new algorithms of the Point Cloud Library. It shows the process chain from the acquisition of raw scan files from an elevated station to the filtering of point cloud, the registration, the calculation of pointwise changes and the aggregation to a grid for later correlation with ship parameters. When working outdoor in all kinds of weather conditions, the processes and equipment need to be robust and account for various cases and situations. This is especially applicable for the algorithms, which need to be adaptable to different scenarios like wet surfaces or snow and unwelcome objects ranging from flotsam to birds sitting on the groyne. At the current stage of the research, deformation in the magnitude of a couple of decimetres is observable. The orientation and location of the deformation is on the seaward side and corresponds to the lower distance of vessels leaving the harbour.

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

PubMed

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

2015-09-01

Green tides are large growths or accumulations of green seaweeds that have been increasing in magnitude and frequency around the world. Because green tides consist of vast biomasses of algae in a limited area and are often seasonal or episodic, they go through periods of rapid growth in which they take up large amounts of nutrients and dissolved gases and generate bioactive natural products that may be stored in the plants, released into the environment, or broken down during decomposition. As a result of the use and production of inorganic and organic compounds, the algae in these blooms can have detrimental impacts on other organisms. Here, we review some of the effects that green tides have on the chemistry of seawater and the effects of the natural products that they produce. As blooms are developing and expanding, algae in green tides take up inorganic nutrients, such as nitrate and ortho-phosphate, which can limit their availability to other photosynthetic organisms. Their uptake of dissolved inorganic carbon for use in photosynthesis can cause localized spikes in the pH of seawater during the day with concomitant drops in the pH at night when the algae are respiring. Many of the algae that form green-tide blooms produce allelopathic compounds, which are metabolites that affect other species. The best documented allelopathic compounds include dimethylsulfoniopropionate (DMSP), dopamine, and reactive oxygen species (ROS) and their breakdown products. DMSP and dopamine are involved in defenses against herbivores. Dopamine and ROS are released into seawater where they can be allelopathic or toxic to other organisms. Thus, these macroalgal blooms can have harmful effects on nearby organisms by altering concentrations of nutrients and dissolved gas in seawater and by producing and releasing allelopathic or toxic compounds. © The Author 2015. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

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

NASA Astrophysics Data System (ADS)

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 that full coupling of normal modes, rather than group coupling, is necessary for accurate predictions of the body tide response.

POET: Planetary Orbital Evolution due to Tides

NASA Astrophysics Data System (ADS)

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.

Kinetic Mechanism and Rate-Limiting Steps of Focal Adhesion Kinase-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schneck, Jessica L.; Briand, Jacques; Chen, Stephanie

2010-12-07

Steady-state kinetic analysis of focal adhesion kinase-1 (FAK1) was performed using radiometric measurement of phosphorylation of a synthetic peptide substrate (Ac-RRRRRRSETDDYAEIID-NH{sub 2}, FAK-tide) which corresponds to the sequence of an autophosphorylation site in FAK1. Initial velocity studies were consistent with a sequential kinetic mechanism, for which apparent kinetic values k{sub cat} (0.052 {+-} 0.001 s{sup -1}), K{sub MgATP} (1.2 {+-} 0.1 {micro}M), K{sub iMgATP} (1.3 {+-} 0.2 {micro}M), K{sub FAK-tide} (5.6 {+-} 0.4 {micro}M), and K{sub iFAK-tide} (6.1 {+-} 1.1 {micro}M) were obtained. Product and dead-end inhibition data indicated that enzymatic phosphorylation of FAK-tide by FAK1 was best described bymore » a random bi bi kinetic mechanism, for which both E-MgADP-FAK-tide and E-MgATP-P-FAK-tide dead-end complexes form. FAK1 catalyzed the {beta}{gamma}-bridge:{beta}-nonbridge positional oxygen exchange of [{gamma}-{sup 18}O{sub 4}]ATP in the presence of 1 mM [{gamma}-{sup 18}O{sub 4}]ATP and 1.5 mM FAK-tide with a progressive time course which was commensurate with catalysis, resulting in a rate of exchange to catalysis of k{sub x}/k{sub cat} = 0.14 {+-} 0.01. These results indicate that phosphoryl transfer is reversible and that a slow kinetic step follows formation of the E-MgADP-P-FAK-tide complex. Further kinetic studies performed in the presence of the microscopic viscosogen sucrose revealed that solvent viscosity had no effect on k{sub cat}/K{sub FAK-tide}, while k{sub cat} and k{sub cat}/K{sub MgATP} were both decreased linearly at increasing solvent viscosity. Crystallographic characterization of inactive versus AMP-PNP-liganded structures of FAK1 showed that a large conformational motion of the activation loop upon ATP binding may be an essential step during catalysis and would explain the viscosity effect observed on k{sub cat}/K{sub m} for MgATP but not on k{sub cat}/K{sub m} for FAK-tide. From the positional isotope exchange, viscosity, and structural data it may be concluded that enzyme turnover (k{sub cat}) is rate-limited by both reversible phosphoryl group transfer (k{sub forward} {approx} 0.2 s{sup -1} and k{sub reverse} {approx} 0.04 s{sup -1}) and a slow step (k{sub conf} {approx} 0.1 s{sup -1}) which is probably the opening of the activation loop after phosphoryl group transfer but preceding product release.« less

[Influences of tide on silicon and nitrogen contents in soil and porewater in the Minjiang Ri-ver estuary, Southeast China].

PubMed

Hou, Guan Yun; Zhai, Shui Jing; Le, Xiao Qing; Tong, Chuan

2017-01-01

Taking Shanyuntan wetland in the Minjiang River estuary as test object, the dissolved silicates (DSi) and inorganic nitrogen contents in porewater and the biogenic silica (BSi) and total nitrogen contents in surface soil of the Phragmites australis wetland, Cyperus malaccensis wetland and Spartina alterniflora wetland were measured in October 2014 (spring tide month) and April 2015 (neap tide month), respectively, to illuminate the influence of tide on silicon and nitrogen contents in soil and porewater of estuarine wetland. Results showed that the DSi content in porewater and the BSi content in surface soil in spring tide month were slightly higher than those in neap tide month, with the highest being observed on neap tide day and the lowest occurring on spring tide day. In contrast, the BSi content in surface soil on spring tide day showed an opposite trend with that on neap tide day. The contents of NH 4 + -N and NO 3 - -N in porewater of different wetland soils in spring tide month were higher than those in neap tide month, while the content of NH 4 + -N on spring tide day was significantly higher than that on neap tide day (P<0.05). The study found that hydrological conditions such as flooding duration and drying-wetting alternation caused by tide had great influences on silicon and nitrogen contents in porewater and surface soil, and vegetation types also showed great influences on their distributions in intertidal wetland of the Minjiang River estuary.

Triggering Factor of Strong Earthquakes and Its Prediction Verification

NASA Astrophysics Data System (ADS)

Ren, Z. Q.; Ren, S. H.

After 30 yearsS research, we have found that great earthquakes are triggered by tide- generation force of the moon. ItSs not the tide-generation force in classical view- points, but is a non-classical viewpoint tide-generation force. We call it as TGFR (Tide-Generation ForcesS Resonance). TGFR strongly depends on the tide-generation force at time of the strange astronomical points (SAP). The SAP mostly are when the moon and another celestial body are arranged with the earth along a straight line (with the same apparent right ascension or 180o difference), the other SAP are the turning points of the moonSs relatively motion to the earth. Moreover, TGFR have four different types effective areas. Our study indicates that a majority of earthquakes are triggering by the rare superimposition of TGFRsS effective areas. In China the great earthquakes in the plain area of Hebei Province, Taiwan, Yunnan Province and Sichuan province are trigger by the decompression TGFR; Other earthquakes are trig- gered by compression TGFR which are in Gansu Province, Ningxia Provinces and northwest direction of Beijing. The great earthquakes in Japan, California, southeast of Europe also are triggered by compression of the TGFR. and in the other part of the world like in Philippines, Central America countries, and West Asia, great earthquakes are triggered by decompression TGFR. We have carried out examinational immediate prediction cooperate TGFR method with other earthquake impending signals such as suggested by Professor Li Junzhi. The successful ratio is about 40%(from our fore- cast reports to the China Seismological Administration). Thus we could say the great earthquake can be predicted (include immediate earthquake prediction). Key words: imminent prediction; triggering factor; TGFR (Tide-Generation ForcesS Resonance); TGFR compression; TGFR compression zone; TGFR decompression; TGFR decom- pression zone

On the generation and evolution of internal solitary waves in the southern Red Sea

NASA Astrophysics Data System (ADS)

Guo, Daquan; Zhan, Peng; Kartadikaria, Aditya; Akylas, Triantaphyllos; Hoteit, Ibrahim

2015-04-01

Satellite observations recently revealed the existence of trains of internal solitary waves in the southern Red Sea between 16.0°N and 16.5°N, propagating from the centre of the domain toward the continental shelf [Da silva et al., 2012]. Given the relatively weak tidal velocity in this area and their generation in the central of the domain, Da Silva suggested three possible mechanisms behind the generation of the waves, namely Resonance and disintegration of interfacial tides, Generation of interfacial tides by impinging, remotely generated internal tidal beams and for geometrically focused and amplified internal tidal beams. Tide analysis based on tide stations data and barotropic tide model in the Red Sea shows that tide is indeed very weak in the centre part of the Red Sea, but it is relatively strong in the northern and southern parts (reaching up to 66 cm/s). Together with extreme steep slopes along the deep trench, it provides favourable conditions for the generation of internal solitary in the southern Red Sea. To investigate the generation mechanisms and study the evolution of the internal waves in the off-shelf region of the southern Red Sea we have implemented a 2-D, high-resolution and non-hydrostatic configuration of the MIT general circulation model (MITgcm). Our simulations reproduce well that the generation process of the internal solitary waves. Analysis of the model's output suggests that the interaction between the topography and tidal flow with the nonlinear effect is the main mechanism behind the generation of the internal solitary waves. Sensitivity experiments suggest that neither tidal beam nor the resonance effect of the topography is important factor in this process.

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

USGS Publications Warehouse

Goodwin, Carl R.

1991-01-01

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

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

NASA Astrophysics Data System (ADS)

Bilgera, P. H. T.

2015-12-01

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

Modelling the 2013 Typhoon Haiyan Storm Surge: Effect of Waves, Offshore Winds, Tide Phase, and Translation Speed

NASA Astrophysics Data System (ADS)

Bilgera, P. H. T.; Villanoy, C.; Cabrera, O.

2016-02-01

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

Earth's surface loading study using InSAR

NASA Astrophysics Data System (ADS)

Amelung, F.; Zhao, W.; Doin, M. P.

2014-12-01

Earth's surface loading/unloading such as glacier retreat, lake water level change, ocean tide, cause measurable (centimeter to millimeter) surface deformation from Synthetic Aperture Radar Interferometry (InSAR). Such seasonal or decadal deformation signals are useful for the estimation of the amount of load and the parameterization of crust and upper mantle - typically under an elastic or a visco-elastic mechanism. Since 2010, we established a study of surface loading using small baseline InSAR time-series analysis. Four sites are included in this study, which are Vatnajokull ice cap, Lake Yamzho Yumco, Petermann glacier, and Barnes ice cap using different satellites such as ERS1/2, Envisat, Radarsat-2, TerraSAR-X. We present results that mainly answer three questions: 1) Is InSAR time-series capable for the detection of millimeter level deformation due to surface loading; 2) When the Earth's rheology is known, how much load change occured; 3) When the surface loading is known, what are the Earth's parameters such as Young's modulus, viscosity. For glacier retreat problem, we introduce a new model for the ice mass loss estimation considering the spatial distribution of ice loss. For lake unloading problem, modeled elastic parameters are useful for the comparison to other 1-D models, e.g. the model based on seismic data.

Synthesis and biological evaluation of 6-substituted-5-fluorouridine ProTides.

PubMed

Slusarczyk, Magdalena; Ferla, Salvatore; Brancale, Andrea; McGuigan, Christopher

2018-02-01

A new family of thirteen phosphoramidate prodrugs (ProTides) of different 6-substituted-5-fluorouridine nucleoside analogues were synthesized and evaluated as potential anticancer agents. In addition, antiviral activity against Chikungunya (CHIKV) virus was evaluated using a cytopathic effect inhibition assay. Although a carboxypeptidase Y assay supported a putative mechanism of activation of ProTides built on 5-fluorouridine with such C6-modifications, the Hint docking studies revealed a compromised substrate-activity for the Hint phosphoramidase-type enzyme that is likely responsible for phosphoramidate bioactivation through P-N bond cleavage and free nucleoside 5'-monophosphate delivery. Our observations may support and explain to some extent the poor in vitro biological activity generally demonstrated by the series of 6-substituted-5-fluorouridine phosphoramidates (ProTides) and will be of guidance for the design of novel phosphoramidate prodrugs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Habitability of extrasolar planets and tidal spin evolution.

PubMed

Heller, René; Barnes, Rory; Leconte, Jérémy

2011-12-01

Stellar radiation has conservatively been used as the key constraint to planetary habitability. We review here the effects of tides, exerted by the host star on the planet, on the evolution of the planetary spin. Tides initially drive the rotation period and the orientation of the rotation axis into an equilibrium state but do not necessarily lead to synchronous rotation. As tides also circularize the orbit, eventually the rotation period does equal the orbital period and one hemisphere will be permanently irradiated by the star. Furthermore, the rotational axis will become perpendicular to the orbit, i.e. the planetary surface will not experience seasonal variations of the insolation. We illustrate here how tides alter the spins of planets in the traditional habitable zone. As an example, we show that, neglecting perturbations due to other companions, the Super-Earth Gl581d performs two rotations per orbit and that any primordial obliquity has been eroded.

Assessing the Impact of Vertical Land Motion on Twentieth Century Global Mean Sea Level Estimates

NASA Technical Reports Server (NTRS)

Hamlington, B. D.; Thompson, P.; Hammond, W. C.; Blewitt, G.; Ray, R. D.

2016-01-01

Near-global and continuous measurements from satellite altimetry have provided accurate estimates of global mean sea level in the past two decades. Extending these estimates further into the past is a challenge using the historical tide gauge records. Not only is sampling nonuniform in both space and time, but tide gauges are also affected by vertical land motion (VLM) that creates a relative sea level change not representative of ocean variability. To allow for comparisons to the satellite altimetry estimated global mean sea level (GMSL), typically the tide gauges are corrected using glacial isostatic adjustment (GIA) models. This approach, however, does not correct other sources of VLM that remain in the tide gauge record. Here we compare Global Positioning System (GPS) VLM estimates at the tide gauge locations to VLM estimates from GIA models, and assess the influence of non-GIA-related VLM on GMSL estimates. We find that the tide gauges, on average, are experiencing positive VLM (i.e., uplift) after removing the known effect of GIA, resulting in an increase of 0.2460.08 mm yr21 in GMSL trend estimates from 1900 to present when using GPS-based corrections. While this result is likely dependent on the subset of tide gauges used and the actual corrections used, it does suggest that non-GIA VLM plays a significant role in twentieth century estimates of GMSL. Given the relatively short GPS records used to obtain these VLM estimates, we also estimate the uncertainty in the GMSL trend that results from limited knowledge of non-GIA-related VLM.

Comparative study of the germination of Ulva prolifera gametes on various substrates

NASA Astrophysics Data System (ADS)

Geng, Huixia; Yan, Tian; Zhou, Mingjiang; Liu, Qing

2015-09-01

Since 2007, massive green tides have occurred every summer in the southern Yellow Sea (YS), China. They have caused severe ecological consequences and huge economic losses. Ulva prolifera originated from Subei Shoal of the YS was confirmed as causative species of the green tides. The Porphyra yezoensis aquaculture rafts in the Subei Shoal have been highly suspected to be the "seed bed" of the green tides, because U. prolifera abundantly fouled the Porphyra yezoensis aquaculture facilities. Besides, various habitats of aquaculture ponds along the Jiangsu coastline and mudflat in the Subei Shoal were proposed to be possible sources of green tides. To understand the "seed" of the green tides in the southern YS and mitigate the original biomass of the green tide, various materials used as substrates for the germination of U. prolifera gametes were tested in this study. Culture experiments showed the following: 1) materials used in the P. yezoensis rafts (plastic, bamboo, jute rope, plastic rope, nylon netting, and plastic netting) displayed a significantly higher germination rate than those associated with mudflats and aquaculture ponds (mud, sand and rock); 2) plastics were the best substrates for the germination of U. prolifera gametes; 3) poor germination was found on old fronds of U. prolifera,, and rubber showed inhibitory effect on germination. The success in germination on P. yezoensis rafts related materials supports the notion that these mariculture structures may be involved in acting as a seed bed for green tide macroalgae. The lack of germination on rubber surfaces may suggest one way to limit the proliferation of early stages of U. prolifera.

Aerosolized red-tide toxins (brevetoxins) and asthma.

PubMed

Fleming, Lora E; Kirkpatrick, Barbara; Backer, Lorraine C; Bean, Judy A; Wanner, Adam; Reich, Andrew; Zaias, Julia; Cheng, Yung Sung; Pierce, Richard; Naar, Jerome; Abraham, William M; Baden, Daniel G

2007-01-01

With the increasing incidence of asthma, there is increasing concern over environmental exposures that may trigger asthma exacerbations. Blooms of the marine microalgae, Karenia brevis, cause red tides (or harmful algal blooms) annually throughout the Gulf of Mexico. K brevis produces highly potent natural polyether toxins, called brevetoxins, which are sodium channel blockers, and possibly histamine activators. In experimental animals, brevetoxins cause significant bronchoconstriction. In humans, a significant increase in self-reported respiratory symptoms has been described after recreational and occupational exposures to Florida red-tide aerosols, particularly among individuals with asthma. Before and after 1 h spent on beaches with and without an active K brevis red-tide exposure, 97 persons >or= 12 years of age with physician-diagnosed asthma were evaluated by questionnaire and spirometry. Concomitant environmental monitoring, water and air sampling, and personal monitoring for brevetoxins were performed. Participants were significantly more likely to report respiratory symptoms after K brevis red-tide aerosol exposure than before exposure. Participants demonstrated small, but statistically significant, decreases in FEV(1), midexpiratory phase of forced expiratory flow, and peak expiratory flow after exposure, particularly among those participants regularly using asthma medications. No significant differences were detected when there was no Florida red tide (ie, during nonexposure periods). This study demonstrated objectively measurable adverse changes in lung function from exposure to aerosolized Florida red-tide toxins in asthmatic subjects, particularly among those requiring regular therapy with asthma medications. Future studies will assess these susceptible subpopulations in more depth, as well as the possible long-term effects of these toxins.

Aerosolized Red-Tide Toxins (Brevetoxins) and Asthma

PubMed Central

Fleming, Lora E.; Kirkpatrick, Barbara; Backer, Lorraine C.; Bean, Judy A.; Wanner, Adam; Reich, Andrew; Zaias, Julia; Cheng, Yung Sung; Pierce, Richard; Naar, Jerome; Abraham, William M.; Baden, Daniel G.

2009-01-01

Background With the increasing incidence of asthma, there is increasing concern over environmental exposures that may trigger asthma exacerbations. Blooms of the marine microalgae, Karenia brevis, cause red tides (or harmful algal blooms) annually throughout the Gulf of Mexico. K brevis produces highly potent natural polyether toxins, called brevetoxins, which are sodium channel blockers, and possibly histamine activators. In experimental animals, brevetoxins cause significant bronchoconstriction. In humans, a significant increase in self-reported respiratory symptoms has been described after recreational and occupational exposures to Florida red-tide aerosols, particularly among individuals with asthma. Methods Before and after 1 h spent on beaches with and without an active K brevis red-tide exposure, 97 persons ≥ 12 years of age with physician-diagnosed asthma were evaluated by questionnaire and spirometry. Concomitant environmental monitoring, water and air sampling, and personal monitoring for brevetoxins were performed. Results Participants were significantly more likely to report respiratory symptoms after K brevis red-tide aerosol exposure than before exposure. Participants demonstrated small, but statistically significant, decreases in FEV1, midexpiratory phase of forced expiratory flow, and peak expiratory flow after exposure, particularly among those participants regularly using asthma medications. No significant differences were detected when there was no Florida red tide (ie, during nonexposure periods). Conclusions This study demonstrated objectively measurable adverse changes in lung function from exposure to aerosolized Florida red-tide toxins in asthmatic subjects, particularly among those requiring regular therapy with asthma medications. Future studies will assess these susceptible subpopulations in more depth, as well as the possible long-term effects of these toxins. PMID:17218574

Simulation and video animation of canal flushing created by a tide gate

USGS Publications Warehouse

Schoellhamer, David H.

1988-01-01

A tide-gate algorithm was added to a one-dimensional unsteady flow model that was calibrated, verified, and used to determine the locations of as many as five tide gates that would maximize flushing in two canal systems. Results from the flow model were used to run a branched Lagrangian transport model to simulate the flushing of a conservative constituent from the canal systems both with and without tide gates. A tide gate produces a part-time riverine flow through the canal system that improves flushing along the flow path created by the tide gate. Flushing with no tide gates and with a single optimally located tide gate are shown with a video animation.

What can we learn from the self-attraction and loading fingerprints about pre-GRACE mass-loss acceleration from Greenland and Antarctica?

NASA Astrophysics Data System (ADS)

Davis, J. L.; Vinogradova, N. T.

2017-12-01

Tide-gauge records from the North Atlantic reveal significant acceleration in sea level starting in the late 20th century. We have analyzed the tide-gauge data using a model in which the accelerations are assumed to be zero prior to 1990. The estimated accelerations range from -1 to +3 m cy-2 and exhibit a systematic spatial variability. Davis and Vinogradova [2017] demonstrated that to model this variability in sea-level acceleration requires contributions from several distinct physical processes: accelerated mass loss from the Greenland and Antarctic Ice Sheets and acceleration associated with ocean circulation and heat uptake. Atmospheric pressure also contributes to the observed changes in sea level, at a much smaller amplitude. Because we are focusing on sea-level accelerations (i.e., sea-level rate changes), the contribution from Glacial Isostatic Adjustment (GIA) is negligible. Modeling of observed sea-level acceleration is achieved using external constraints for the important physical processes. Using GRACE results, we can calculate the sea-level "fingerprints" for Greenland and Antarctica associated with mass loading and gravitational perturbations. For the North Atlantic, Greenland induces a significant spatial variation in sea-level change—dominated by the solid-Earth response to the mass loss—whereas Antarctica contributes a spatially constant acceleration. The observations prefer a scaling of the solid-Earth/gravitational response, and we present the implications of this result for ice-mass changes prior to the onset of GRACE observations (2002-3).

The inverse problem: Ocean tides derived from earth tide observations

NASA Technical Reports Server (NTRS)

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.

Environmental extremes and biotic interactions facilitate depredation of endangered California Ridgway’s rail in a San Francisco Bay tidal marsh

USGS Publications Warehouse

Overton, Cory T.; Bobzien, Steven; Grefsrud, Marcia

2016-01-01

On 23 December 2015 while performing a high tide population survey for endangered Ridgway’s rails (Rallus obsoletus obsoletus; formerly known as the California clapper rail) and other rail species at Arrowhead Marsh, Martin Luther King Jr. Regional Shoreline, Oakland, California, the authors observed a series of species interactions resulting in the predation of a Ridgway’s rail by an adult female peregrine falcon (Falco peregrinus). High tide surveys are performed during the highest tides of the year when tidal marsh vegetation at Arrowhead Marsh becomes inundated, concentrating the tidal marsh obligate species into the limited area of emergent vegetation remaining as refuge cover. Annual mean tide level (elevation referenced relative to mean lower low water) at Arrowhead Marsh is 1.10 m, mean higher high water is 2.04 m (NOAA National Ocean Service 2014) and the average elevation of the marsh surface is 1.60 m (Overton et al. 2014). Tidal conditions on the day of the survey were predicted to be 2.42 m. Observed tides at the nearby Alameda Island tide gauge were 8 cm higher than predicted due to a regional low-pressure system and warmer than average sea surface temperatures (NOAA National Ocean Service 2014). The approximately 80 cm deep inundation of the marsh plain was sufficient to completely submerge tidal marsh vegetation and effectively remove 90% of refugia habitats.

Brevenal is a natural inhibitor of brevetoxin action in sodium channel receptor binding assays.

PubMed

Bourdelais, Andrea J; Campbell, Susan; Jacocks, Henry; Naar, Jerome; Wright, Jeffery L C; Carsi, Jigani; Baden, Daniel G

2004-08-01

1. Florida red tides produce profound neurotoxicity that is evidenced by massive fish kills, neurotoxic shellfish poisoning, and respiratory distress. Red tides vary in potency, potency that is not totally governed by toxin concentration. The purpose of the study was to understand the variable potency of red tides by evaluating the potential for other natural pharmacological agents which could modulate or otherwise reduce the potency of these lethal environmental events. 2. A synaptosome binding preparation with 3-fold higher specific brevetoxin binding was developed to detect small changes in toxin binding in the presence of potential antagonists. Rodent brain labeled in vitro with tritiated brevetoxin shows high specific binding in the cerebellum as evidenced by autoradiography. Synaptosome binding assays employing cerebellum-derived synaptosomes illustrate 3-fold increased specific binding. 3. A new polyether natural product from Florida's red tide dinoflagellate Karenia brevis, has been isolated and characterized. Brevenal, as the nontoxic natural product is known, competes with tritiated brevetoxin for site 5 associated with the voltage-sensitive sodium channel (VSSC). Brevenal displacement of specific brevetoxin binding is purely competitive in nature. 4. Brevenal, obtained from either laboratory cultures or field collections during a red tide, protects fish from the neurotoxic effects of brevetoxin exposure. 5. Brevenal may serve as a model compound for the development of therapeutics to prevent or reverse intoxication in red tide exposures.

Ocean tides

NASA Technical Reports Server (NTRS)

Hendershott, M. C.

1975-01-01

A review of recent developments in the study of ocean tides and related phenomena is presented. Topics briefly discussed include: the mechanism by which tidal dissipation occurs; continental shelf, marginal sea, and baroclinic tides; estimation of the amount of energy stored in the tide; the distribution of energy over the ocean; the resonant frequencies and Q factors of oceanic normal modes; the relationship of earth tides and ocean tides; and numerical global tidal models.

Discharge, water-quality characteristics, and nutrient loads from McKay Bay, Delaney Creek, and East Bay, Tampa, Florida, 1991-1993

USGS Publications Warehouse

Stoker, Y.E.; Levesque, V.A.; Fritz, E.M.

1996-01-01

Nutrient enrichment in Tampa Bay has caused a decline in water quality in the estuary. Efforts to reduce the nutrient loading to Tampa Bay have resulted in improvement in water quality from 1981 to 1991. However, Tampa Bay still is onsidered enriched with nutrients. Water quality in East Bay (located at the northeastern part of Hillsborough Bay, which is an embayment in Tampa Bay) is not improving at the same rate as the rest of the bay. East Bay is the center of shipping activity in Tampa Bay and the seventh largest port in the United States. One of the primary cargoes is phosphate ore and related products such as fertilizer. The potential for nutrient loading to East Bay from shipping activities is high and has not previously been measured. Nitrogen and phosphorus loads from East Bay to Hillsborough Bay were measured during selected time periods during June 1992 through May 1993; these data were used to estimate seasonal and annual loads. These loads were evaluated to determine whether the loss of fertilizer products from shipping activities resulted in increased nutrient loading to Hillsborough Bay. Discharge was measured, and water-quality samples were collected at the head of East Bay (exiting McKay Bay), and at the mouth of East Bay. Discharge and nitrogen and phosphorus concentrations for the period June 1992 through May 1993 were used to compute loads. Discharges from McKay Bay, Delaney Creek, and East Bay are highly variable because of the effect of tide. Flow patterns during discharge measurements generally were unidirectional in McKay Bay and Delaney Creek, but more complex, bidirectional patterns were observed at the mouth of East Bay. Tidally affected discharge data were digitally filtered with the Godin filter to remove the effects of tide so that residual, or net, discharge could be determined. Daily mean discharge from McKay Bay ranged from -1,900 to 2,420 cubic feet per second; from Delaney Creek, -3.8 to 162 cubic feet per second; and from East Bay, -437 to 3,780 cubic feet per second. Water quality in McKay Bay, Delaney Creek, and East Bay varies vertically, areally, and seasonally. Specific conductance and concentrations of phosphorus and ammonia nitrogen were greater near the bottom than near the surface at the head and mouth of East Bay. Concentrations of total nitrogen and ammonia plus organic nitrogen generally were greater at the head of East Bay than at the mouth, indicating that McKay Bay is the primary source of nitrogen to East Bay. Concentrations of total ammonia nitrogen, nitrite plus nitrate nitrogen, phosphorus, orthophosphorus, and suspended solids and values of turbidity and specific conductance generally were greater at the mouth of East Bay than at the head. The greatest concentrations of nitrogen and phosphorus were measured in Delaney Creek. In East Bay and McKay Bay, the greatest concentrations of nitrogen, phosphorus, and ammonia plus organic nitrogen occurred in summer, whereas turbidity, specific conductance, and concentrations of suspended solids were greater in winter. The greatest daily mean loads from McKay Bay and East Bay occurred in late June 1992 and April and May 1993 and coincided with periods of daily mean discharge greater than about 2,000 cubic feet per second. Although concentrations of nitrogen and phosphorus were greater in Delaney Creek than in McKay Bay and East Bay, loads were minimal because of minimal discharges from Delaney Creek. Monthly loads of total nitrogen ranged from about 20 tons to about 83 tons at McKay Bay; from about 1 ton to 4.2 tons at Delaney Creek; and from about 17 tons to 76 tons at the mouth of East Bay. Monthly loads of phosphorus ranged from about 11 tons to about 45 tons at McKay Bay; from about 0.62 ton to 2.6 tons at Delaney Creek; and from about 10 tons to about 45 tons at the mouth of East Bay. The results of this study indicate that nitrogen and phosphorus loads from the basin draining directly to East Bay (excluding loads from the McKa

Continuous Tidal Streamflow and Gage-Height Data for Bass and Cinder Creeks on Kiawah Island, South Carolina, September 2007

USGS Publications Warehouse

Conrads, Paul; Erbland, John W.

2009-01-01

A three-dimensional model of Bass and Cinder Creeks on Kiawah Island, South Carolina, was developed to evaluate methodologies for determining fecal coliform total maximum daily loads for shellfish waters. To calibrate the model, two index-velocity sites on the creeks were instrumented with continuous acoustic velocity meters and water-level sensors to compute a 21-day continuous record of tidal streamflows. In addition to monitoring tidal cycles, streamflow measurements were made at the index-velocity sites, and tidal-cycle streamflow measurements were made at the mouth of Bass Creek and on the Stono River to characterize the streamflow dynamics near the ocean boundary of the three-dimensional model at the beginning, September 6, 2007, and end, September 26, 2007, of the index-velocity meter deployment. The maximum floodtide and ebbtide measured on the Stono River by the mouth of Bass Creek for the two measurements were -155,000 and 170,000 cubic feet per second (ft3/s). At the mouth of Bass Creek, the maximum floodtide and ebbtide measurements during the 2 measurement days were +/-10,200 ft3/s. Tidal streamflows for the 21-day deployment on Bass Creek ranged from -2,510 ft3/s for an incoming tide to 4,360 ft3/s for an outgoing tide. On Cinder Creek, the incoming and outgoing tide varied from -2,180 to 2,400 ft3/s during the same period.

The rising tide of ocean diseases: Unsolved problems and research priorities

USGS Publications Warehouse

Harvell, Drew; Aronson, Richard; Baron, Nancy; Connell, Joseph; Dobson, Andrew P.; Ellner, Steve; Gerber, Leah R.; Kim, Kiho; Kuris, Armand M.; McCallum, Hamish; Lafferty, Kevin D.; McKay, Bruce; Porter, James; Pascual, Mercedes; Smith, Garriett; Sutherland, Katherine; Ward, Jessica

2004-01-01

New studies have detected a rising number of reports of diseases in marine organisms such as corals, molluscs, turtles, mammals, and echinoderms over the past three decades. Despite the increasing disease load, microbiological, molecular, and theoretical tools for managing disease in the world's oceans are under-developed. Review of the new developments in the study of these diseases identifies five major unsolved problems and priorities for future research: (1) detecting origins and reservoirs for marine diseases and tracing the flow of some new pathogens from land to sea; (2) documenting the longevity and host range of infectious stages; (3) evaluating the effect of greater taxonomic diversity of marine relative to terrestrial hosts and pathogens; (4) pinpointing the facilitating role of anthropogenic agents as incubators and conveyors of marine pathogens; (5) adapting epidemiological models to analysis of marine disease.

Tidal impacts on the subtidal flow division at the main bifurcation in the Yangtze River Delta

NASA Astrophysics Data System (ADS)

Zhang, Wei; Feng, Haochuan; Hoitink, A. J. F.; Zhu, Yuliang; Gong, Fei; Zheng, Jinhai

2017-09-01

Flow division at bifurcations in the Yangtze Estuary has received ample attention, since it may control the pathways of terrestrial sediments over downstream river branches including the 12.5 m Deepwater Navigation channel. While some efforts have been made to interpret flow division at the bifurcations of the Yangtze Estuary, little attention has been paid to the role of tides. Flow division at estuarine bifurcations is made complicated by tides that propagate from the outlet of the tidal channels into the delta. To quantify the tidal influence on the distribution of river discharge, and more generally, to understand the mechanisms governing the subtidal flow division at the tidally affected bifurcation in the Yangtze River Delta, a two-dimensional hydrodynamic model is employed. In this model, the landward boundary is chosen beyond the tidal limit, where the tidal motion has faded out entirely. The seaward boundary is chosen such that the river discharge does not influence the water level. Subtidal discharges are decomposed using the method of factor separation, to distinguish between the effects of tides, river discharge and river-tide interactions on the subtidal flow division. Results indicate that tides modify the river discharge distribution over distributary channels in the Yangtze River Delta, particularly in the dry season. A significant difference in the subtidal flow division during spring tide and neap tide shows that the tidally averaged flow division over the distributaries in the delta greatly depends on tidal amplitude. By varying the river discharge at the landward boundary and amplitudes and phases of the principal tidal constituents at the seaward boundary of the established model, the sensitivities of the subtidal flow division to the river discharge and tidal amplitude variation were investigated in detail. Generally, the tidal impacts on the subtidal flow division are around 12% to 22%, with river discharge varying from 30,000 m3s-1 to 20,000 m3s-1. This effect on the flow distribution can even overwhelm the effects induced by river discharge based on geometry only, when the flow discharge is lowest. Furthermore, the fortnightly tidal cycle plays an important role in enhancing the inequality of the subtidal flow division caused by the M2 tidal component solely at the tidal bifurcation in the Yangtze River Delta during low flow.

Microbial Methane Oxidation Rates in Guandu Wetland of northern Taiwan

NASA Astrophysics Data System (ADS)

Yu, Zih-Huei; Wang, Pei-Ling; Lin, Li-Hung

2016-04-01

Wetland is one of the major sources of atmospheric methane. The exact magnitude of methane emission is essentially controlled by microbial processes. Besides of methanogenesis, methanotrophy oxidizes methane with the reduction of various electron acceptors under oxic or anoxic conditions. The interplay of these microbial activities determines the final methane flux under different circumstances. In a tidal wetland, the cyclic flooding and recession of tide render oxygen and sulfate the dominant electron acceptors for methane oxidation. However, the details have not been fully examined, especially for the linkage between potential methane oxidation rates and in situ condition. In this study, a sub-tropical wetland in northern Taiwan, Guandu, was chosen to examine the tidal effect on microbial methane regulation. Several sediment cores were retrieved during high tide and low tide period and their geochemical profiles were characterized to demonstrate in situ microbial activities. Incubation experiments were conducted to estimate potential aerobic and anaerobic methane oxidation rates in surface and core sediments. Sediment cores collected in high tide and low tide period showed different geochemical characteristics, owning to tidal inundation. Chloride and sulfate concentration were lower during low tide period. A spike of enhanced sulfate at middle depth intervals was sandwiched by two sulfate depleted zones above and underneath. Methane was accumulated significantly with two methane depletion zones nearly mirroring the sulfate spike zone identified. During the high tide period, sulfate decreased slightly with depth with methane production inhibited at shallow depths. However, a methane consumption zone still occurred near the surface. Potential aerobic methane oxidation rates were estimated between 0.7 to 1.1 μmole/g/d, showing no difference between the samples collected at high tide or low tide period. However, a lag phase was widely observed and the lag phase lasted over a longer period of time for the samples collected in high tide period. It seems that aerobic methanotrophs needed a longer period of time to recovery and/or had low activities, since they had been suppressed by low oxygen concentration during high tide period. The rates of anaerobic methane oxidation ranged between 1.5 and 4.0 nmole/g/d for samples collected at high tide period, whereas lower rates ranging from 0.2 to 2.0 nmole/g/d were observed for samples at low tide period. The addition of basal salt solution apparently stimulated methane consumption significantly. Based on the field observation and laboratory incubations, our results indicated a dynamic shift of metabolic zonation in tidally influenced wetlands. Aerobic methanotrophy appears to outpace anaerobic methanotrophy by orders of magnitude regardless of tidal inundation. This together with methanogenesis regulated by the availability of sulfate and organic degradation plays a major role in controlling methane emission. While anaerobic methanotrophy is relatively minor in methane cycling, its linkage with the sulfate availability modulates the coupling of carbon and sulfur turnover under anoxic conditions.

Orbit Mechanics about Small Asteroids

NASA Technical Reports Server (NTRS)

Scheeres, D. J.

2007-01-01

Space missions to small solar system bodies must deal with multiple perturbations acting on the spacecraft. These include strong perturbations from the gravity field and solar tide, but for small bodies the most important perturbations may arise from solar radiation pressure (SRP) acting on the spacecraft. Previous research has generally investigated the effect of the gravity field, solar tide, and SRP acting on a spacecraft trajectory about an asteroid in isolation and has not considered their joint effect. In this paper a more general theoretical discussion of the joint effects of these forces is given.

Barometric Tides from ECMWF Operational Analyses

NASA Technical Reports Server (NTRS)

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

2003-01-01

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

Analyses of the solid earth and ocean tidal perturbations on the orbits of the Geos 1 and Geos 2 satellites

NASA Technical Reports Server (NTRS)

Felsentreger, T. L.; Marsh, J. G.; Agreen, R. W.

1976-01-01

Perturbations in the inclination of the Geos 1 and Geos 2 satellite orbits have been analyzed for the solid earth and ocean tide contributions. Precision reduced camera and Tranet Doppler observations spanning periods of over 600 days for each satellite were used to derive mean orbital elements. Perturbations due to the earth's gravity field, solar radiation pressure, and atmospheric drag were modeled, and the resulting inclination residuals were analyzed for tidal effects. The amplitudes of the observed total tidal effects were about 1.2 arc sec (36 m) in the inclination of Geos 1 and 4.5 arc sec (135 m) for Geos 2. The solid earth tides were then modeled by using the Love number 0.30. The resulting inclination residuals were then analyzed for ocean tide spherical harmonic parameters.

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

NASA Astrophysics Data System (ADS)

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, preliminary analysis has indicated only a modest relationship between dune erosion/accretion rates and the North Atlantic Oscillation index.

Exposure and effect assessment of aerosolized red tide toxins (brevetoxins) and asthma.

PubMed

Fleming, Lora E; Bean, Judy A; Kirkpatrick, Barbara; Cheng, Yung Sung; Pierce, Richard; Naar, Jerome; Nierenberg, Kate; Backer, Lorraine C; Wanner, Adam; Reich, Andrew; Zhou, Yue; Watkins, Sharon; Henry, Mike; Zaias, Julia; Abraham, William M; Benson, Janet; Cassedy, Amy; Hollenbeck, Julie; Kirkpatrick, Gary; Clarke, Tainya; Baden, Daniel G

2009-07-01

In previous studies we demonstrated statistically significant changes in reported symptoms for lifeguards, general beach goers, and persons with asthma, as well as statistically significant changes in pulmonary function tests (PFTs) in asthmatics, after exposure to brevetoxins in Florida red tide (Karenia brevis bloom) aerosols. In this study we explored the use of different methods of intensive ambient and personal air monitoring to characterize these exposures to predict self-reported health effects in our asthmatic study population. We evaluated health effects in 87 subjects with asthma before and after 1 hr of exposure to Florida red tide aerosols and assessed for aerosolized brevetoxin exposure using personal and ambient samplers. After only 1 hr of exposure to Florida red tide aerosols containing brevetoxin concentrations > 57 ng/m(3), asthmatics had statistically significant increases in self-reported respiratory symptoms and total symptom scores. However, we did not see the expected corresponding changes in PFT results. Significant increases in self-reported symptoms were also observed for those not using asthma medication and those living >/= 1 mile from the coast. These results provide additional evidence of health effects in asthmatics from ambient exposure to aerosols containing very low concentrations of brevetoxins, possibly at the lower threshold for inducing a biologic response (i.e., toxicity). Consistent with the literature describing self-reported symptoms as an accurate measure of asthmatic distress, our results suggest that self-reported symptoms are a valuable measure of the extent of health effects from exposure to aerosolized brevetoxins in asthmatic populations.

Pesticides, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls in transport in two Atlantic coastal plain tributaries and loadings to Chesapeake Bay

USGS Publications Warehouse

Foster, G.D.; Miller, C.V.; Huff, T.B.; Roberts, E.

2003-01-01

Concentrations of current-use pesticides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine (OC) insecticides were determined above the reach of tide in the Chesterville Branch and Nanticoke River on the eastern shore of Chesapeake Bay during base-flow and storm-flow hydrologic regimes to evaluate mass transport to Chesapeake Bay. The two rivers monitored showed relatively high concentrations of atrazine, simazine, alachlor, and metolachlor in comparison to previously investigated western shore tributaries, and reflected the predominant agricultural land use in the eastern shore watersheds. The four current use pesticides showed the greatest seasonal contribution to annual loadings to tidal waters of Chesapeake Bay from the two rivers, and the relative order of annual loadings for the other contaminant classes was PAHs > PCBs > OC insecticides. Annual loadings normalized to the landscape areas of selected Chesapeake Bay watersheds showed correlations to identifiable source areas, with the highest pesticide yields (g/km2/yr) occurring in eastern shore agricultural landscapes, and the highest PAH yields derived from urban regions.

New results on the apsidal-motion test to stellar structure and evolution including the effects of dynamic tides

NASA Astrophysics Data System (ADS)

Claret, A.; Willems, B.

2002-06-01

We revised the current status of the apsidal-motion test to stellar structure and evolution. The observational sample was increased by about 50% in comparison to previous studies. Classical and relativistic systems were analyzed simultaneously and only systems with accurate absolute dimensions were considered. New interior models incorporating recent opacity tables, stellar rotation, mass loss, and moderate core overshooting were used as theoretical tools to compare the predicted with the observed shifts of the position of the periastron. The stellar models were computed for the precise observed masses and the adopted chemical compositions are consistent with the corresponding tables of opacities to avoid the inherent problems of interpolation in mass and in (X, Z). The derived chemical composition for each individual system was used to infer the primordial helium content as well as a law of enrichment. The values found are in good agreement with those obtained from various independent sources. For the first time, the effects of dynamic tides are taken into account systematically to determine the contribution of the tidal distortion to the predicted apsidal-motion rate. The deviations between the apsidal-motion rates resulting from the classical formula and those determined by taking into account the effects of dynamic tides are presented as a function of the level of synchronism. For systems close to synchronisation, dynamic tides cause deviations with respect to the classical apsidal-motion formula due to the effects of the compressibility of the stellar fluid. For systems with higher rotational angular velocities, additional deviations due to resonances arise when the forcing frequencies of the dynamic tides come into the range of the free oscillation modes of the component stars. The resulting comparison shows a good agreement between the observed and theoretical apsidal-motion rates. No systematic effects in the sense that models are less mass concentrated than real stars and no correlations with the evolutionary status of the systems were detected.

Effect of short-term subaerial exposure on the cauliflower coral, Pocillopora damicornis, during a simulated extreme low-tide event

NASA Astrophysics Data System (ADS)

Castrillón-Cifuentes, Ana Lucia; Lozano-Cortés, Diego F.; Zapata, Fernando A.

2017-06-01

There is increased interest in understanding how stress reduces coral resistance to disturbances and how acclimatization increases the ability of corals to resist future stress. Most extreme low tides at Gorgona Island, which expose reef flats to air, do not appear to negatively affect corals because corals usually do not undergo lethal bleaching during such events. However, coral physiology and fitness may be impacted by this phenomenon. The aim of this study was to evaluate whether corals exposed to air have modified biological functions to resist bleaching. To test this, an extreme low-tide event was simulated in the field. Colonies of Pocillopora damicornis were exposed to air for 15 or 40 min over the course of one, two, or three consecutive days. This procedure was repeated for one to three months. Colonies of P. damicornis exposed to air had reduced fecundity, decreased zooxanthellae density, and changed color from darker to lighter. However, the growth rate of exposed corals was similar to that of non-exposed colonies. We conclude that short periods of subaerial exposure during extreme low tides are not lethal to P. damicornis, but negatively affect sexual reproduction, which might have deleterious effects at the population level. The periodic occurrence of extreme low tides in the tropical eastern Pacific may be one factor responsible for the high rate of asexual reproduction (e.g., fragmentation) in pocilloporid corals of this region.

Mesosphere Dynamics with Gravity Wave Forcing. 1; Diurnal and Semi-Diurnal Tides

NASA Technical Reports Server (NTRS)

Mayr, H. G.; Mengel, J. G.; Chan, K. L.; Porter, H. S.; Einaudi, Franco (Technical Monitor)

2000-01-01

We present results from a nonlinear, 3D, time dependent numerical spectral model (NSM), which extends from the ground up into the thermosphere and incorporates Hines' Doppler Spread Parameterization for small-scale gravity waves (GW). Our focal point is the mesosphere that is dominated by wave interactions. We discuss diurnal and semi-diurnal tides ill the present paper (Part 1) and planetary waves in the companion paper (Part 2). To provide an understanding of the seasonal variations of tides, in particular with regard to gravity wave processes, numerical experiments are performed that lead to the following conclusions: 1. The large semiannual variations in tile diurnal tide (DT), with peak amplitudes observed around equinox, are produced primarily by GW interactions that involve, in part, planetary waves. 2. The DT, like planetary waves, tends to be amplified by GW momentum deposition, which reduces also the vertical wavelength. 3.Variations in eddy viscosity associated with GW interactions tend to peak in late spring and early fall and call also influence the DT. 4. The semidiurnal semidiurnal tide (SDT), and its phase in particular, is strongly influenced by the mean zonal circulation. 5. The SDT, individually, is amplified by GW's. But the DT filters out GW's such that the wave interaction effectively reduces the amplitude of the SDT, effectively producing a strong nonlinear interaction between the DT and SDT. 6.) Planetary waves generated internally by baroclinic instability and GW interaction produce large amplitude modulations of the DT and SDT.

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

USGS Publications Warehouse

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

1977-01-01

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

Evolution of Tides and Tidal Dissipation Over the Past 26,000 Years Using a Multi-Scale Model of Global Barotropic Tides

NASA Astrophysics Data System (ADS)

Salehipour, H.; Peltier, W. R.

2014-12-01

In this paper we will describe the results obtained through integration of a further refined version of the truly global barotropic tidal model of Salehipour et al. (Ocean Modell., 69, 2013) using the most recent reconstruction of ice-age bathymetric conditions as embodied in the recently constructed ICE-6G_C (VM5a) model of Peltier et al. (JGR-Solid Earth, in press, 2014). Our interest is in the spatial and temporal evolution of tidal amplitude, phase and dissipation from the Last Glacial Maximum (LGM) 26,000 years ago until the present. The state-of-the-art higher order nonlinear tidal model of Salehipour et al. (2013) includes a highly parallelized multi-scale framework in which an unstructured tessellation of the global ocean enables extensive local refinement around regions of interest such as the Hawaiian Ridge, the Brazil Basin and the Southern Ocean. At LGM, features such as the Patagonian Shelf were fully exposed land which during the deglaciation process would have been flooded leading to significant changes of tidal range along the evolving coastline. In the further development of this model we have included the fully iterated treatment of the influence of gravitational self-attraction and loading as in, e.g. Egbert et al. (JGR-Oceans, 109, 2004). The treatment of the dissipation of the barotropic tide through dissipation of the internal tide has also been significantly improved. Our paleobathymetry and coastline data sets extend from LGM to present at 500 year intervals and constitute a significant refinement of the widely employed ICE-5G (VM2) model of Peltier (Annu. Rev. Earth Planet. Sci., 32, 2004). Our results will be compared with those recently published by Green & Nycander (JPO, 43, 2013) and Wilmes & Green (JGR-Oceans, 119, 2014) as well as with the earlier results of Griffiths & Peltier (GRL, 35, 2008; J. Clim., 22, 2009).

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

PubMed

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

2006-08-01

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

The origin of neap-spring tidal cycles

USGS Publications Warehouse

Kvale, E.P.

2006-01-01

The origin of oceanic tides is a basic concept taught in most introductory college-level sedimentology/geology, oceanography, and astronomy courses. Tides are typically explained in the context of the equilibrium tidal theory model. Yet this model does not take into account real tides in many parts of the world. Not only does the equilibrium tidal model fail to explicate amphidromic circulation, it also does not explain diurnal tides in low latitude positions. It likewise fails to explain the existence of tide-dominated areas where neap-spring cycles are synchronized with the 27.32-day orbital cycle of the Moon (tropical month), rather than with the more familiar 29.52-day cycle of lunar phases (synodic month). Both types of neap-spring cycles can be recognized in the rock record. A complete explanation of the origin of tides should include a discussion of dynamic tidal theory. In the dynamic tidal model, tides resulting from the motions of the Moon in its orbit around the Earth and the Earth in its orbit around the Sun are modeled as products of the combined effects of a series of phantom satellites. The movement of each of these satellites, relative to the Earth's equator, creates its own tidal wave that moves around an amphidromic point. Each of these waves is referred to as a tidal constituent. The geometries of the ocean basins determine which of these constituents are amplified. Thus, the tide-raising potential for any locality on Earth can be conceptualized as the result of a series of tidal constituents specific to that region. A better understanding of tidal cycles opens up remarkable opportunities for research on tidal deposits with implications for, among other things, a more complete understanding of the tidal dynamics responsible for sediment transport and deposition, changes in Earth-Moon distance through time, and the possible influences tidal cycles may exert on organisms. ?? 2006 Elsevier B.V. All rights reserved.

Occurrence of Organic Compounds and Trace Elements in the Upper Passaic and Elizabeth Rivers and Their Tributaries in New Jersey, July 2003 to February 2004: Phase II of the New Jersey Toxics Reduction Workplan for New York-New Jersey Harbor

USGS Publications Warehouse

Wilson, Timothy P.; Bonin, Jennifer L.

2008-01-01

Samples of surface water and suspended sediment were collected from the Passaic and Elizabeth Rivers and their tributaries in New Jersey from July 2003 to February 2004 to determine the concentrations of selected chlorinated organic and inorganic constituents. This sampling and analysis was conducted as Phase II of the New York-New Jersey Harbor Estuary Workplan?Contaminant Assessment and Reduction Program (CARP), which is overseen by the New Jersey Department of Environmental Protection. Phase II of the New Jersey Workplan was conducted to define upstream tributary and point sources of contaminants in those rivers sampled during Phase I work, with special emphasis on the Passaic and Elizabeth Rivers. Samples were collected from three groups of tributaries: (1) the Second, Third, and Saddle Rivers; (2) the Pompton and upper Passaic Rivers; and (3) the West Branch and main stem of the Elizabeth River. The Second, Third, and Saddle Rivers were sampled near their confluence with the tidal Passaic River, but at locations not affected by tidal flooding. The Pompton and upper Passaic Rivers were sampled immediately upstream from their confluence at Two Bridges, N.J. The West Branch and the main stem of the Elizabeth River were sampled just upstream from their confluence at Hillside, N.J. All tributaries were sampled during low-flow discharge conditions using the protocols and analytical methods for organic constituents used in low-flow sampling in Phase I. Grab samples of streamflow also were collected at each site and were analyzed for trace elements (mercury, methylmercury, cadmium, and lead) and for suspended sediment, particulate organic carbon, and dissolved organic carbon. The measured concentrations and available historical suspended-sediment and stream-discharge data (where available) were used to estimate average annual loads of suspended sediment and organic compounds in these rivers. Total suspended-sediment loads for 1975?2000 were estimated using rating curves developed from historical U.S. Geological Survey (USGS) suspended-sediment and discharge data, where available. Average annual loads of suspended sediment, in millions of kilograms per year (Mkg/yr), were estimated to be 0.190 for the Second River, 0.23 for the Third River, 1.00 for the Saddle River, 1.76 for the Pompton River, and 7.40 for the upper Passaic River. On the basis of the available discharge records, the upper Passaic River was estimated to provide approximately 60 percent of the water and 80 percent of the total suspended-sediment load at the Passaic River head-of-tide, whereas the Pompton River provided roughly 20 percent of the total suspended-sediment load estimated at the head-of-tide. The combined suspended-sediment loads of the upper Passaic and Pompton Rivers (9.2 Mkg/yr), however, represent only 40 percent of the average annual suspended-sediment load estimated for the head-of-tide (23 Mkg/yr) at Little Falls, N.J. The difference between the combined suspended-sediment loads of the tributaries and the estimated load at Little Falls represents either sediment trapped upriver from the dam at Little Falls, additional inputs of suspended sediment downstream from the tributary confluence, or uncertainty in the suspended-sediment and discharge data that were used. The concentrations of total suspended sediment-bound polychlorinated biphenyls (PCBs) in the tributaries to the Passaic River were 194 ng/g (nanograms per gram) in the Second River, 575 ng/g in the Third River, 2,320 ng/g in the Saddle River, 200 ng/g in the Pompton River, and 87 ng/g in the upper Passic River. The dissolved PCB concentrations in the tributaries were 563 pg/L (picograms per liter) in the Second River, 2,510 pg/L in the Third River, 2,270 pg/L in the Saddle River, 887 pg/L in the Pompton River, and 1,000 pg/L in the upper Passaic River. Combined with the sediment loads and discharge, these concentrations resulted in annual loads of suspended sediment-bound PCBs, i

Winds and Waves (4 Min - 11 Yrs) in the Upper Middle Atmosphere (60-110 Km) at Saskatoon, Canada (52 Deg N, 107 Deg W): MF Radar (2.2 Mhz) Soundings 1973 - 1983

NASA Technical Reports Server (NTRS)

Manson, A. H.; Meek, C. E.; Gregory, J. B.

1984-01-01

Examples of gravity waves (GW), tides, planetary waves (PW), and circulation effects in the upper middle atmosphere are presented. Energy densities of GW, tides, and PW are compared. Fourier and spectral analyses are applied to the data.

Assessing the importance of internal tide scattering in the deep ocean

NASA Astrophysics Data System (ADS)

Haji, Maha; Peacock, Thomas; Carter, Glenn; Johnston, T. M. Shaun

2014-11-01

Tides are one of the main sources of energy input to the deep ocean, and the pathways of energy transfer from barotropic tides to turbulent mixing scales via internal tides are not well understood. Large-scale (low-mode) internal tides account for the bulk of energy extracted from barotropic tides and have been observed to propagate over 1000 km from their generation sites. We seek to examine the fate of these large-scale internal tides and the processes by which their energy is transferred, or ``scattered,'' to small-scale (high-mode) internal tides, which dissipate locally and are responsible for internal tide driven mixing. The EXperiment on Internal Tide Scattering (EXITS) field study conducted in 2010-2011 sought to examine the role of topographic scattering at the Line Islands Ridge. The scattering process was examined via data from three moorings equipped with moored profilers, spanning total depths of 3000--5000 m. The results of our field data analysis are rationalized via comparison to data from two- and three-dimensional numerical models and a two-dimensional analytical model based on Green function theory.

The influence of tide on sea surface temperature in the marginal sea of northwest Pacific Ocean

NASA Astrophysics Data System (ADS)

Huang, Shih-Jen; Tsai, Yun-Chan; Ho, Chung-Ru; Lo, Yao-Tsai; Kuo, Nan-Jung

2017-10-01

Tide gauge data provided by the University of Hawaii Sea Level Center and daily sea surface temperature (SST) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) product are used in this study to analyze the influence of tide on the SST in the seas of Northwestern Pacific. In the marginal region, the climatology SST is lower in the northwestern area than that in the southeastern area. In the coastal region, the SST at spring tide is higher than that at neap tide in winter, but it is lower in other seasons. In the adjacent waters of East China Sea and Yellow Sea, the SST at spring tide is higher than that at neap tide in winter and summer but it is lower in spring and autumn. In the open ocean region, the SST at spring tide is higher than that at neap tide in winter, but it is lower in other seasons. In conclusion, not only the river discharge and topography, but also tides could influence the SST variations, especially in the open ocean region.

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

PubMed

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

2013-02-15

In 2001, a hurricane moved a large sand dune, blocking the sole outlet channel of a mangrove. In the absence of daily tidal flow, the two ponds containing the mangrove vegetation evaporated, the secondary drainage channels were lost, and a salt crust formed on the bed of the ponds. The mangrove lost most of its trees and the remaining suffered from osmotic shock that led to defoliation. Restoration involved creating a knickpoint retreat (waterfall retreat effect) and tidal flow as a dredging mechanism to restore the outlet and form secondary channels in the ponds. During a very low tide, we deepened the mouth of the outlet channel by 1 m below high tide level to form a small waterfall when high tides receded. During successive tides, this one-step knickpoint deteriorated and formed a series of low rapids. With a steep gradient, the rapids retreated upstream into the ponds, first reopening the outlet channel and then carving new secondary channels in the pond mud flat. The excavation process of the outlet channel was repeated three times and was sufficient to effectively improve the hydrology of the entire pond system; allowing adequate flooding and draining of the mangrove ponds. Hydrology analysis tested by the Engelund-Hansen sediment transport formula established that the output of sediment from the ecosystem is greater than the input of sand into the mangroves. This is keeping the main channel continuously open. After eight years, tidal flow continues to keep the channels open; the salt crust has disappeared; the trees have recovered, and a large area of new vegetation has emerged. Copyright © 2012 Elsevier Ltd. All rights reserved.

Fish sound production in the presence of harmful algal blooms in the eastern Gulf of Mexico.

PubMed

Wall, Carrie C; Lembke, Chad; Hu, Chuanmin; Mann, David A

2014-01-01

This paper presents the first known research to examine sound production by fishes during harmful algal blooms (HABs). Most fish sound production is species-specific and repetitive, enabling passive acoustic monitoring to identify the distribution and behavior of soniferous species. Autonomous gliders that collect passive acoustic data and environmental data concurrently can be used to establish the oceanographic conditions surrounding sound-producing organisms. Three passive acoustic glider missions were conducted off west-central Florida in October 2011, and September and October 2012. The deployment period for two missions was dictated by the presence of red tide events with the glider path specifically set to encounter toxic Karenia brevis blooms (a.k.a red tides). Oceanographic conditions measured by the glider were significantly correlated to the variation in sounds from six known or suspected species of fish across the three missions with depth consistently being the most significant factor. At the time and space scales of this study, there was no detectable effect of red tide on sound production. Sounds were still recorded within red tide-affected waters from species with overlapping depth ranges. These results suggest that the fishes studied here did not alter their sound production nor migrate out of red tide-affected areas. Although these results are preliminary because of the limited measurements, the data and methods presented here provide a proof of principle and could serve as protocol for future studies on the effects of algal blooms on the behavior of soniferous fishes. To fully capture the effects of episodic events, we suggest that stationary or vertically profiling acoustic recorders and environmental sampling be used as a complement to glider measurements.

Fish Sound Production in the Presence of Harmful Algal Blooms in the Eastern Gulf of Mexico

PubMed Central

Wall, Carrie C.; Lembke, Chad; Hu, Chuanmin; Mann, David A.

2014-01-01

This paper presents the first known research to examine sound production by fishes during harmful algal blooms (HABs). Most fish sound production is species-specific and repetitive, enabling passive acoustic monitoring to identify the distribution and behavior of soniferous species. Autonomous gliders that collect passive acoustic data and environmental data concurrently can be used to establish the oceanographic conditions surrounding sound-producing organisms. Three passive acoustic glider missions were conducted off west-central Florida in October 2011, and September and October 2012. The deployment period for two missions was dictated by the presence of red tide events with the glider path specifically set to encounter toxic Karenia brevis blooms (a.k.a red tides). Oceanographic conditions measured by the glider were significantly correlated to the variation in sounds from six known or suspected species of fish across the three missions with depth consistently being the most significant factor. At the time and space scales of this study, there was no detectable effect of red tide on sound production. Sounds were still recorded within red tide-affected waters from species with overlapping depth ranges. These results suggest that the fishes studied here did not alter their sound production nor migrate out of red tide-affected areas. Although these results are preliminary because of the limited measurements, the data and methods presented here provide a proof of principle and could serve as protocol for future studies on the effects of algal blooms on the behavior of soniferous fishes. To fully capture the effects of episodic events, we suggest that stationary or vertically profiling acoustic recorders and environmental sampling be used as a complement to glider measurements. PMID:25551564

Monitoring storm tide and flooding from Hurricane Isaac along the Gulf Coast of the United States, August 2012

USGS Publications Warehouse

McCallum, Brian E.; McGee, Benton D.; Kimbrow, Dustin R.; Runner, Michael S.; Painter, Jaime A.; Frantz, Eric R.; Gotvald, Anthony J.

2012-01-01

The U.S. Geological Survey (USGS) deployed a temporary monitoring network of water-level and barometric pressure sensors at 127 locations along the gulf coast from Alabama to Louisiana to record the timing, areal extent, and magnitude of hurricane storm tide and coastal flooding generated by Hurricane Isaac. This deployment was undertaken as part of a coordinated federal emergency response as outlined by the Stafford Act under a directed mission assignment by the Federal Emergency Management Agency. Storm tide, as defined by National Oceanic and Atmospheric Administration (NOAA; National Oceanic and Atmospheric Administration, 2008), is the water-level rise generated by a combination of storm surge and astronomical tide during a coastal storm. Hurricane Isaac initially made landfall on the coast of Louisiana in Plaquemines Parish on August 28, 2012, as a Category 1 hurricane on the Saffir–Simpson Hurricane Wind Scale (National Weather Service, 1974) and then stalled over southern Louisiana for several days, causing prolonged storm-tide impacts. A total of 188 water-level and wave-height sensors were deployed at 127 locations during August 27–28 prior to landfall. More than 90 percent of the sensors and all high-water marks (HWMs) were recovered and surveyed to North American Vertical Datum of 1988 (NAVD 88) within 7 days of the Isaac landfall. Only a handful of sensors in the Plaquemines Parish area of Louisiana could not be retrieved until weeks later due to prolonged flooding in the area. Data collected from this event can be used to 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.

Combined effects of tides, evaporation and rainfall on the soil conditions in an intertidal creek-marsh system

NASA Astrophysics Data System (ADS)

Xin, Pei; Zhou, Tingzhang; Lu, Chunhui; Shen, Chengji; Zhang, Chenming; D'Alpaos, Andrea; Li, Ling

2017-05-01

Salt marshes, distributed globally at the land-ocean interface, are a highly productive eco-system with valuable ecological functions. While salt marshes are affected by various eco-geo-hydrological processes and factors, soil moisture and salinity affect plant growth and play a key role in determining the structure and functions of the marsh ecosystem. To examine the variations of both soil parameters, we simulated pore-water flow and salt transport in a creek-marsh system subjected to spring-neap tides, evaporation and rainfall. The results demonstrated that within a sandy-loam marsh, the tide-induced pore-water circulation averted salt build-up due to evaporation in the near-creek area. In the marsh interior where the horizontal drainage was weak, density-driven flow was responsible for dissipating salt accumulation in the shallow soil layer. In the sandy-loam marsh, the combined influences of spring-neap tides, rainfall and evaporation led to the formation of three characteristic zones, c.f., a near-creek zone with low soil water saturation (i.e., well-aerated) and low pore-water salinity as affected by the semi-diurnal spring tides, a less well-aerated zone with increased salinity where drainage occurred during the neap tides, and an interior zone where evaporation and rainfall infiltration regulated the soil conditions. These characteristics, however, varied with the soil type. In low-permeability silt-loam and clay-loam marshes, the tide-induced drainage weakened and the soil conditions over a large area became dominated by evaporation and rainfall. Sea level rise was found to worsen the soil aeration condition but inhibit salt accumulation due to evaporation. These findings shed lights on the soil conditions underpinned by various hydrogeological processes, and have important implications for further investigations on marsh plant growth and ecosystem functions.

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

NASA Astrophysics Data System (ADS)

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.

A one-dimensional diffusion analogy model for estimation of tide heights in selected tidal marshes in Connecticut

USGS Publications Warehouse

Bjerklie, David M.; O’Brien, Kevin; Rozsa, Ron

2013-01-01

A one-dimensional diffusion analogy model for estimating tide heights in coastal marshes was developed and calibrated by using data from previous tidal-marsh studies. The method is simpler to use than other one- and two-dimensional hydrodynamic models because it does not require marsh depth and tidal prism information; however, the one-dimensional diffusion analogy model cannot be used to estimate tide heights, flow velocities, and tide arrival times for tide conditions other than the highest tide for which it is calibrated. Limited validation of the method indicates that it has an accuracy within 0.3 feet. The method can be applied with limited calibration information that is based entirely on remote sensing or geographic information system data layers. The method can be used to estimate high-tide heights in tidal wetlands drained by tide gates where tide levels cannot be observed directly by opening the gates without risk of flooding properties and structures. A geographic information system application of the method is demonstrated for Sybil Creek marsh in Branford, Connecticut. The tidal flux into this marsh is controlled by two tide gates that prevent full tidal inundation of the marsh. The method application shows reasonable tide heights for the gates-closed condition (the normal condition) and the one-gate-open condition on the basis of comparison with observed heights. The condition with all tide gates open (two gates) was simulated with the model; results indicate where several structures would be flooded if the gates were removed as part of restoration efforts or if the tide gates were to fail.

[Analysis on characteristics of red tide in Fujian coastal waters during the last 10 years].

PubMed

Li, Xue-Ding

2012-07-01

There were 161 red tide events collected during the last 10 years from 2001 to 2010 in Fujian coastal waters. Comprehensive analysis was performed using statistical methods and the results indicated the following characteristics of the temporal and spatial distribution of red tide in Fujian coastal waters: (1) Outbreaks of red tide often occurred between April and September, and the peak period was in May and June. Most red tide events lasted for 2 to 4 days, and the affected area was below 50 square kilometers. The first outbreak of red tide tended to occur earlier in recent years, and the lasting time became longer. (2) There were 20 species of organisms causing the red tides in Fujian coastal waters, among which 10 species were Bacillariophyta, 9 species were Dinophyta and 1 species was Protozoa. Prorocentrum donghaiense was the most frequent cause of red tides, followed by Noctiluca scintillans, Skeletonema costatum and Chaetoceros sp.. The species caused red tides obeyed the succession law and there were always new species involved. (2) In terms of spatial distribution, outbreaks of red tides mainly occurred in the coastal waters of Ningde, Fuzhou and Xiamen. The species causing red tides were Prorocentrum donghaiense and Noctiluca in the coastal waters in the north of Pingtan, Fujian Province, Skeletonema costatum and Chaetoceros in the coastal waters in the south of Pingtan, Fujian Province. The comprehensive analysis of the characteristics of red tides during the last 10 years is expected to provide scientific and reasonable basis for the prevention, reduction and forecast of red tides in Fujian coastal waters.

Influence of the atmospheric opacity cycle on the near surface environment of Gale Crater on Mars

NASA Astrophysics Data System (ADS)

de la Torre Juarez, Manuel; Gomez-Elvira, Javier; Guzewich, Scott David; Lemmon, Mark T.; Martinez, German; Mason, Emily; Navarro, Sara; Newman, Claire E.; Smith, Michael D.; Retortillo, Alvaro de Vicente

2016-10-01

The Mars atmospheric dust changes the capacity of the atmosphere to absorb solar radiation or release outgoing thermal infrared radiation. This alters the atmospheric heat exchange fluxes and can interfere with the global circulation. The response of near surface pressure, temperature and winds has been characterized at the higher northern latitudes of 45 degree N at the Viking landing sites. The Rover Environmental Monitoring Station (REMS) on Curiosity allows a similar characterization at near-equatorial latitudes of 4.5 degree S. Using MCAM-880 nm opacities as a measure of local atmospheric dust load, we analyze the response of changes in surface variables measured by REMS and compare to those observed by Viking. As on Viking, diurnal and semidiurnal pressure tide amplitudes track very closely the atmospheric opacity and the mean daily pressure shows the increased wave activity. Temperature tides show a more complex response that combines its sensitivity to changes in dust and cloud opacities. Differences in UV opacities for the REMS set of finite spectral windows are explored during the dust and clear seasons.

[Temporal and spatial distribution of red tide in Yangtze River Estuary and adjacent waters].

PubMed

Liu, Lu-San; Li, Zi-Cheng; Zhou, Juan; Zheng, Bing-Hui; Tang, Jing-Liang

2011-09-01

The events of red tide were collected in Yangtze River Estuary and adjacent waters from 1972 to 2009. Based on geographic information system (GIS) analysis on the temporal and spatial distribution of red tide, the distribution map was generated accordingly. The results show: (1) There are three red tide-prone areas, which are outside the Yangtze River estuary and the eastern of Sheshan, Huaniaoshan-Shengshan-Gouqi, Zhoushan and the eastern of Zhujiajian. The red tide occurred 174 times in total, in which there were 25 times covered the area was larger than 1 000 km2. After 2000, the frequency of red tide were significantly increasing; (2) The frequent occurrence of red tide was in May (51% of total occurrence) and June (20% of total occurrence); (3) In all of the red tide plankton, the dominant species were Prorocentrum danghaiense, Skeletonema costatum, Prorocentrum dantatum, Nactiluca scientillans. The red tides caused by these species were 38, 35, 15, 10 times separately.

Hydrologic aspects of Hurricane Hugo in South Carolina, September 1989

USGS Publications Warehouse

Schuck-Kolben, R. E.; Cherry, R.N.

1995-01-01

Hurricane Hugo, with winds in excess of 135 miles per hour(mi/h), made landfall near Charleston, S.C., early on the morning of September 22, 1989. It was the most destructive hurricane ever experienced in South Carolina. The storm caused 35 deaths and $7 billion in property damage in South Carolina (Purvis, 1990).This report documents some hydrologic effects of Hurricane Hugo along the South Carolina coast. The report includes maps showing storm-tide stage and profiles of the maximum storm-tide stages along the outer coast. Storm-tide stage frequency information is presented and changes in beach morphology and water quality of coastal streams resulting from the storm are described.

Comparison of observation level versus 24-hour average atmospheric loading corrections in VLBI analysis

NASA Astrophysics Data System (ADS)

MacMillan, D. S.; van Dam, T. M.

2009-04-01

Variations in the horizontal distribution of atmospheric mass induce displacements of the Earth's surface. Theoretical estimates of the amplitude of the surface displacement indicate that the predicted surface displacement is often large enough to be detected by current geodetic techniques. In fact, the effects of atmospheric pressure loading have been detected in Global Positioning System (GPS) coordinate time series [van Dam et al., 1994; Dong et al., 2002; Scherneck et al., 2003; Zerbini et al., 2004] and very long baseline interferometery (VLBI) coordinates [Rabble and Schuh, 1986; Manabe et al., 1991; van Dam and Herring, 1994; Schuh et al., 2003; MacMillan and Gipson, 1994; and Petrov and Boy, 2004]. Some of these studies applied the atmospheric displacement at the observation level and in other studies, the predicted atmospheric and observed geodetic surface displacements have been averaged over 24 hours. A direct comparison of observation level and 24 hour corrections has not been carried out for VLBI to determine if one or the other approach is superior. In this presentation, we address the following questions: 1) Is it better to correct geodetic data at the observation level rather than applying corrections averaged over 24 hours to estimated geodetic coordinates a posteriori? 2) At the sub-daily periods, the atmospheric mass signal is composed of two components: a tidal component and a non-tidal component. If observation level corrections reduce the scatter of VLBI data more than a posteriori correction, is it sufficient to only model the atmospheric tides or must the entire atmospheric load signal be incorporated into the corrections? 3) When solutions from different geodetic techniques (or analysis centers within a technique) are combined (e.g., for ITRF2008), not all solutions may have applied atmospheric loading corrections. Are any systematic effects on the estimated TRF introduced when atmospheric loading is applied?

Tides in the Black Sea: Observations and Numerical Modelling

NASA Astrophysics Data System (ADS)

Medvedev, Igor P.

2018-05-01

Longterm hourly data from 28 tide gauges were used to examine the main features of tides in the Black Sea. The tides in this basin are directly caused by tide-generating forces and the semidiurnal tides prevail over diurnal tides. Based on the Princeton Ocean Model (POM), a numerical model of tides in the Black Sea and adjacent Sea of Azov was developed and found to be in good agreement with tide gauge observations. Detailed tidal charts for amplitudes and phase lags of the major tidal harmonics in these two seas were constructed. The results of the numerical modelling and observations reveal for the semidiurnal tides the presence of an amphidromy with clockwise rotation and another one with counterclockwise rotation for the diurnal tides, both located in the central part of the sea near the Crimean Peninsula. Therefore, for this part of the sea the amplitudes of harmonics M 2 and K 1 are less than 0.1 cm. Relatively larger M 2 amplitudes are observed on the east and west coasts of the sea (2-3 cm). The maximum amplitude of the harmonic M 2 was found at Karkinit Bay—up to 4.5 cm—while the maximum tidal range varies from 1 cm near the Crimean Peninsula to 18-19 cm in the Dnieper-Bug Estuary and Karkinit Bay. Radiational tides, initiated mainly by sea breezes, make an important contribution to the formation of tidal oscillations in the Dnieper-Bug Estuary.

The atypical hydrodynamics of the Mayotte Lagoon (Indian Ocean): Effects on water age and potential impact on plankton productivity

NASA Astrophysics Data System (ADS)

Chevalier, C.; Devenon, J. L.; Pagano, M.; Rougier, G.; Blanchot, J.; Arfi, R.

2017-09-01

In mesotidal lagoons of the Indian Ocean, the coral reef barrier may be temporarily submerged at high tide and partially exposed at low tide, and this may cause unusual lagoon dynamics. A field measurement campaign was conducted in the north-east Mayotte Lagoon in order to understand these processes. An experimental approach was used, combining measurements taken by 1) a side-mounted Acoustic Doppler Current Profiler (ADCP) on a moving boat along transects through the reef passages (17 transects) and 2) by more conventional high-resolution moored ADCP measurements. A specific tidal analysis methodology was used to determine the spatial variability of the velocity. The tidal hydrodynamics within the lagoon were determined using a numerical model and then analyzed. The tide acted as a quasi-progressive forced wave in the lagoon: at low tide, water entered through the south passage, over the reef and left the lagoon through the north passage. This flow was reversed at high tide. The tide-driven quasi-progressive wave created a specific lagoon dynamics. Contrary to most other channel lagoons, the flow over the reef was mainly outward. This increases the inflow through the passages, which renews the water in the lagoon as shown by the indicators of age and origin of the water inside the lagoon. This study also showed the importance of these indicators for better understanding the variations and levels of plankton biomass (with chlorophyll concentration as proxy) which is quite high in this lagoon.

A classification of U.S. estuaries based on physical and hydrologic attributes

USGS Publications Warehouse

Engle, V.D.; Kurtz, J.C.; Smith, L.M.; Chancy, C.; Bourgeois, P.

2007-01-01

A classification of U.S. estuaries is presented based on estuarine characteristics that have been identified as important for quantifying stressor-response relationships in coastal systems. Estuaries within a class have similar physical and hydrologic characteristics and would be expected to demonstrate similar biological responses to stressor loads from the adjacent watersheds. Nine classes of estuaries were identified by applying cluster analysis to a database for 138 U.S. estuarine drainage areas. The database included physical measures of estuarine areas, depth and volume, as well as hydrologic parameters (i.e., tide height, tidal prism volume, freshwater inflow rates, salinity, and temperature). The ability of an estuary to dilute or flush pollutants can be estimated using physical and hydrologic properties such as volume, bathymetry, freshwater inflow and tidal exchange rates which influence residence time and affect pollutant loading rates. Thus, physical and hydrologic characteristics can be used to estimate the susceptibility of estuaries to pollutant effects. This classification of estuaries can be used by natural resource managers to describe and inventory coastal systems, understand stressor impacts, predict which systems are most sensitive to stressors, and manage and protect coastal resources. ?? Springer Science+Business Media B.V. 2007.

Tidal Effect in Small-Scale Sound Propagation Experiment

NASA Astrophysics Data System (ADS)

Kamimura, Seiji; Ogasawara, Hanako; Mori, Kazuyoshi; Nakamura, Toshiaki

2012-07-01

A sound propagation experiment in very shallow water was conducted at Hashirimizu port in 2009. We transmitted 5 kHz sinusoidal waves with M-sequence modulation. As a result, we found that the travel time concentrated in two time frames. When comparing the travel time with the tide level, the travel time was dependent on the tide level. In terms of the wave patterns, most of the wave patterns have two peaks. As the tide level changed, the biggest peak switched within two peaks. To discuss this, numerical simulation by finite difference time domain (FDTD) method was carried out. The result agreed with the experimental result. Finally, we changed the material of the quay wall in the FDTD simulation and concluded that the first peak is a multireflected combination wave and the effect of its reflected wave at a quay wall has superiority in the second peak.

Improving the detection of tectonic transients in Japan by accounting for Earth's deformation response to surface mass loading

NASA Astrophysics Data System (ADS)

Martens, H. R.; Simons, M.; Moore, A. W.; Owen, S. E.; Rivera, L. A.

2016-12-01

We explore the contributions of oceanic, atmospheric, and hydrologic mass loading to Global Navigation Satellite System (GNSS)-inferred observations of surface displacements in Japan. Surface mass loading (SML) generates mm- to cm-level deformation of the solid Earth on time scales of hours to years, which exceeds the measurement uncertainties of most GNSS position estimates. By improving the efficiency and accuracy of the prediction and empirical estimation of SML response, we aim to reduce the variance of GNSS time series and therefore enhance the ability to resolve subtle tectonic signals, such as aseismic transients associated with subduction zone processes. Using the GIPSY software in precise point positioning mode, we estimate time series of sub-daily receiver positions for the GNSS Earth Observation Network System (GEONET) in Japan. We also model the Earth's elastic deformation response to a variety of surface mass loads, including loads of atmospheric (e.g., ECMWF) and oceanic (e.g., TPXO8-Atlas, ECCO2) origin. We extract periodic signals, such as the ocean tides and seasonal variations in hydrological loading, using harmonic analysis. Deformation caused by non-periodic loads, such as non-tidal oceanic and atmospheric loads, can be predicted and removed to further reduce the variance. We seek to streamline the workflow for estimating SML-induced surface displacements from a variety of sources in order to account for loading signals in routine GNSS data processing, thereby improving the ability to assess the mechanics of plate boundaries.

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

NASA Astrophysics Data System (ADS)

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.

Estimated discharge and chemical-constituent loading from the upper Floridan aquifer to the lower St John's River, northeastern Florida, 1990-91

USGS Publications Warehouse

Spechler, R.M.

1995-01-01

The lower St. Johns River, a 101-mile long segment of the St. Johns River, begins at the confluence of the Ocklawaha River and ends where the river discharges into the Atlantic Ocean at Mayport. The St. Johns River is affected by tides as far upstream as Lake George, 106 miles from the mouth. Saltwater from the ocean advances inland during each incoming tide and recedes during each outgoing tide. The chemical quality of the lower St. Johns River is highly variable primarily because of the inflow of saltwater from the ocean, and in some areas, from the discharge of mineralized ground water. Three hydrogeologic units are present in the study area: the surficial aquifer system, the intermediate confining unit, and the Floridan aquifer system. The surficial aquifer system overlies the intermediate confining unit and consists of deposits containing sand, clay, shell, and some limestone and dolomite. The intermediate confining unit underlies all of the study area and retards the vertical movement of water between the surficial aquifer system and the Floridan aquifer system. The intermediate confining unit consists of beds of relatively low permeability sediments that vary in thickness and areal extent and can be breached by sinkholes, fractures, and other openings. The Floridan aquifer system primarily consists of limestone and dolomite. The quality of water in the Upper Floridan aquifer varies throughout the study area. Dissolved solids in water range from about 100 to more than 5,000 milligrams per liter. Chloride and sulfate concentrations in water from the Upper Floridan aquifer range from about 4 to 3,700 milligrams per liter and from 1 to 1,300 milligrams per liter, respectively. The rate of leakage through the intermediate confining unit is controlled by the leakance coefficient of the intermediate confining unit and by the head difference between the Upper Floridan aquifer and the surficial aquifer system. The total ground-water discharge from the Upper Floridan aquifer to the St. Johns River within the lower St. Johns River drainage basin, based on the potentiometric surface of the Upper Floridan aquifer in September 1990, was estimated to be 86 cubic feet per second. Total estimated ground-water discharge to the lower St. Johns River in September 1991, when heads in the Upper Floridan aquifer averaged about 4 feet higher than in 1990, was 133 cubic feet per second. The load of dissolved-solids that discharged from the Upper Floridan aquifer into the lower St. Johns River on the basis of September 1990 heads is estimated to be 47,000 tons per year. Estimated chloride and sulfate loads are 18,000 and 9,500 tons per year, respectively. Dissolved-solids, chloride, and sulfate loads discharging into the lower St. Johns River are estimated to be 81,000, 39,000, and 15,000 tons per year, respectively, on the basis of September 1991 heads.

Effects of Spartina alterniflora invasion on soil respiration in the Yangtze River estuary, China.

PubMed

Bu, Naishun; Qu, Junfeng; Li, Zhaolei; Li, Gang; Zhao, Hua; Zhao, Bin; Li, Bo; Chen, Jiakuan; Fang, Changming

2015-01-01

Many studies have found that plant invasion can enhance soil organic carbon (SOC) pools, by increasing net primary production (NPP) and/or decreased soil respiration. While most studies have focused on C input, little attention has been paid to plant invasion effects on soil respiration, especially in wetland ecosystems. Our study examined the effects of Spartina alterniflora invasion on soil respiration and C dynamics in the Yangtze River estuary. The estuary was originally occupied by two native plant species: Phragmites australis in the high tide zone and Scirpus mariqueter in the low tide zone. Mean soil respiration rates were 185.8 and 142.3 mg CO2 m(-2) h(-1) in S. alterniflora and P. australis stands in the high tide zone, and 159.7 and 112.0 mg CO2 m(-2) h(-1) in S. alterniflora and S. mariqueter stands in the low tide zone, respectively. Aboveground NPP (ANPP), SOC, and microbial biomass were also significantly higher in the S. alterniflora stands than in the two native plant stands. S. alterniflora invasion did not significantly change soil inorganic carbon or pH. Our results indicated that enhanced ANPP by S. alterniflora exceeded invasion-induced C loss through soil respiration. This suggests that S. alterniflora invasion into the Yangtze River estuary could strengthen the net C sink of wetlands in the context of global climate change.

Effects of Spartina alterniflora Invasion on Soil Respiration in the Yangtze River Estuary, China

PubMed Central

Bu, Naishun; Qu, Junfeng; Li, Zhaolei; Li, Gang; Zhao, Hua; Zhao, Bin; Li, Bo; Chen, Jiakuan; Fang, Changming

2015-01-01

Many studies have found that plant invasion can enhance soil organic carbon (SOC) pools, by increasing net primary production (NPP) and/or decreased soil respiration. While most studies have focused on C input, little attention has been paid to plant invasion effects on soil respiration, especially in wetland ecosystems. Our study examined the effects of Spartina alterniflora invasion on soil respiration and C dynamics in the Yangtze River estuary. The estuary was originally occupied by two native plant species: Phragmites australis in the high tide zone and Scirpus mariqueter in the low tide zone. Mean soil respiration rates were 185.8 and 142.3 mg CO2 m−2 h−1 in S. alterniflora and P. australis stands in the high tide zone, and 159.7 and 112.0 mg CO2 m−2 h−1 in S. alterniflora and S. mariqueter stands in the low tide zone, respectively. Aboveground NPP (ANPP), SOC, and microbial biomass were also significantly higher in the S. alterniflora stands than in the two native plant stands. S. alterniflora invasion did not significantly change soil inorganic carbon or pH. Our results indicated that enhanced ANPP by S. alterniflora exceeded invasion-induced C loss through soil respiration. This suggests that S. alterniflora invasion into the Yangtze River estuary could strengthen the net C sink of wetlands in the context of global climate change. PMID:25799512

Monitoring red tide with satellite imagery and numerical models: a case study in the Arabian Gulf.

PubMed

Zhao, Jun; Ghedira, Hosni

2014-02-15

A red tide event that occurred in August 2008 in the Arabian Gulf was monitored and assessed using satellite observations and numerical models. Satellite observations revealed the bloom extent and evolution from August 2008 to August 2009. Flow patterns of the bloom patch were confirmed by results from a HYCOM model. HYCOM data and satellite-derived sea surface temperature data further suggested that the bloom could have been initiated offshore and advected onshore by bottom Ekman layer. Analysis indicated that nutrient sources supporting the bloom included upwelling, Trichodesmium, and dust deposition while other potential sources of nutrient supply should also be considered. In order to monitor and detect red tide effectively and provide insights into its initiation and maintenance mechanisms, the integration of multiple platforms is required. The case study presented here demonstrated the benefit of combing satellite observations and numerical models for studying red tide outbreaks and dynamics. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

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

NASA Astrophysics Data System (ADS)

Familkhalili, R.; Talke, S. A.

2016-09-01

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

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

NASA Technical Reports Server (NTRS)

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.

Direct measurement of sub-surface mass change using the variable-baseline gravity gradient method

USGS Publications Warehouse

Kennedy, Jeffrey; Ferré, Ty P.A.; Güntner, Andreas; Abe, Maiko; Creutzfeldt, Benjamin

2014-01-01

Time-lapse gravity data provide a direct, non-destructive method to monitor mass changes at scales from cm to km. But, the effectively infinite spatial sensitivity of gravity measurements can make it difficult to isolate the signal of interest. The variable-baseline gravity gradient method, based on the difference of measurements between two gravimeters, is an alternative to the conventional approach of individually modeling all sources of mass and elevation change. This approach can improve the signal-to-noise ratio for many applications by removing the contributions of Earth tides, loading, and other signals that have the same effect on both gravimeters. At the same time, this approach can focus the support volume within a relatively small user-defined region of the subsurface. The method is demonstrated using paired superconducting gravimeters to make for the first time a large-scale, non-invasive measurement of infiltration wetting front velocity and change in water content above the wetting front.

Improved water-level forecasting for the Northwest European Shelf and North Sea through direct modelling of tide, surge and non-linear interaction

NASA Astrophysics Data System (ADS)

Zijl, Firmijn; Verlaan, Martin; Gerritsen, Herman

2013-07-01

In real-time operational coastal forecasting systems for the northwest European shelf, the representation accuracy of tide-surge models commonly suffers from insufficiently accurate tidal representation, especially in shallow near-shore areas with complex bathymetry and geometry. Therefore, in conventional operational systems, the surge component from numerical model simulations is used, while the harmonically predicted tide, accurately known from harmonic analysis of tide gauge measurements, is added to forecast the full water-level signal at tide gauge locations. Although there are errors associated with this so-called astronomical correction (e.g. because of the assumption of linearity of tide and surge), for current operational models, astronomical correction has nevertheless been shown to increase the representation accuracy of the full water-level signal. The simulated modulation of the surge through non-linear tide-surge interaction is affected by the poor representation of the tide signal in the tide-surge model, which astronomical correction does not improve. Furthermore, astronomical correction can only be applied to locations where the astronomic tide is known through a harmonic analysis of in situ measurements at tide gauge stations. This provides a strong motivation to improve both tide and surge representation of numerical models used in forecasting. In the present paper, we propose a new generation tide-surge model for the northwest European Shelf (DCSMv6). This is the first application on this scale in which the tidal representation is such that astronomical correction no longer improves the accuracy of the total water-level representation and where, consequently, the straightforward direct model forecasting of total water levels is better. The methodology applied to improve both tide and surge representation of the model is discussed, with emphasis on the use of satellite altimeter data and data assimilation techniques for reducing parameter uncertainty. Historic DCSMv6 model simulations are compared against shelf wide observations for a full calendar year. For a selection of stations, these results are compared to those with astronomical correction, which confirms that the tide representation in coastal regions has sufficient accuracy, and that forecasting total water levels directly yields superior results.

Numerical Modelling of Tertiary Tides

NASA Astrophysics Data System (ADS)

Gao, Yan; Correia, Alexandre C. M.; Eggleton, Peter P.; Han, Zhanwen

2018-06-01

Stellar systems consisting of multiple stars tend to undergo tidal interactions when the separations between the stars are short. While tidal phenomena have been extensively studied, a certain tidal effect exclusive to hierarchical triples (triples in which one component star has a much wider orbit than the others) has hardly received any attention, mainly due to its complexity and consequent resistance to being modelled. This tidal effect is the tidal perturbation of the tertiary by the inner binary, which in turn depletes orbital energy from the inner binary, causing the inner binary separation to shrink. In this paper, we develop a fully numerical simulation of these "tertiary tides" by modifying established tidal models. We also provide general insight as to how close a hierarchical triple needs to be in order for such an effect to take place, and demonstrate that our simulations can effectively retrieve the orbital evolution for such systems. We conclude that tertiary tides are a significant factor in the evolution of close hierarchical triples, and strongly influence at least ˜1% of all multiple star systems.

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

NASA Technical Reports Server (NTRS)

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 Effects Of Tides And Waves On Water-Table Elevations In Coastal Zones

NASA Astrophysics Data System (ADS)

Turner, Ian L.; Coates, Bruce P.; Acworth, R. Ian

1996-02-01

A resurgence of interest in the literature about coastal zones has highlighted the fact that ocean processes can have a significant influence on unconfined coastal aquifers, resulting in a net super-elevation of the water table at the land-ocean boundary to groundwater discharge. This theoretical and experimental notion appears to be less well recognized in the field of groundwater investigation, where it is more usual to assume that the coastal boundary is equivalent to mean sea level. Coastal over-height is due to the ability of a sloping beach face to `fill' (vertical infiltration) at a greater rate than it can `drain' (horizontal seepage). The results of a three-month monitoring of the groundwater profile within a narrow coastal aquifer at New South Wales, Australia, confirms the significance of tide and wave processes to groundwater elevation. The mean height of the water table on the upper beach face was about 1.2 m above mean sea level, rising to 2.0 m during a period of coincident spring tides, storm waves, and rainfall. This elevation was sufficient to temporarily reverse the direction of groundwater flow. Fourier analysis and cross-correlation are used to help distinguish the role of tides in maintaining groundwater super-elevation from the role of storm waves in further raising the coastal water table for periods of two to three days. The results of a simple numerical simulation demonstrate that estimated rates of groundwater discharge at the study site were halved when the effect of tides and waves was incorporated in the definition of the ocean boundary.

Energetics of global ocean tides from Geosat altimetry

NASA Technical Reports Server (NTRS)

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.

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

NASA Technical Reports Server (NTRS)

Herring, Thomas A.; Dong, Danan

1994-01-01

We discuss the determination of diurnal and semidiurnal variations in the rotation rate and the direction of rotation axis of Earth from the analysis of 8 years of very long baseline interferometry (VLBI) data. This analysis clearly show that these variations are largely periodic and tidally driven; that is, the periods of the variations correspond to the periods of the largest lunar and solar tides. For rotation rate variations, expressed in terms of changes in universal time (UT), the tidal lines with the largest observed signals are O1 (amplitude 23.5 microseconds in time (microseconds), period 25.82 solar hours); KL (18.9 microseconds, 23.93 hours); M2 (17.9 microseconds, 12.54 hours); and S2 (8.6 microseconds, 12.00 hours). For variations in the direction of the rotation axis (polar motion), significant signals exist in the retrograde semidiurnal band at the M2 and S2 tides (amplitudes 265 and 119 microarc seconds (microarc seconds, respectively); the prograde diurnal band at the O1, K1, and P1 tides (amplitudes 199, 152, and 60 microarc seconds, respectively); and the prograde semidiurnal band at the M2 and K2 tides (amplitudes 58 and 39 microarc seconds, respectively). Variations in the retrograde diurnal band are represented by corrections with previous estimates except that a previously noted discrepancy in the 13.66-day nutation (corresponding to the O1 tide) is largely removed in this new analysis. We estimate that the standard deviations of these estimates are 1.0 microseconds for the UT1 variations and 14-16 microarc seconds for the polar motion terms. These uncertainties correspond to surface displacements of approximately 0.5 mm. From the analysis of atmospheric angular momentum data we conclude that variations in UT1 excited by the atmosphere with subdaily periods are small (approximately 1 microsecond). We find that the average radial tidal displacements of the VLBI sites in the diurnal band are largely consistent with known deficiencies in current tidal models, i.e., deficiencies of up to 0.9 mm in the treatment of the free core nutation resonance. In the semidiurnal band, our analysis yields estimates of the second-degree harmonic radial Love number h(sub 2) at the M2 tide of 0.604 + i0.005 +/- 0.002. The most likely explanation for the rotational variations are the effects of ocean tides, but there may also be some contributions from atmospheric tides, the effects of triaxiality of Earth, and the equatorial second-degree-harmonic components of the core- mantle boundary.

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

NASA Astrophysics Data System (ADS)

Manno, Giorgio; Lo Re, Carlo; Ciraolo, Giuseppe

2017-09-01

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.

Rapid response of tidal channel networks to sea-level variations (Venice Lagoon, Italy)

NASA Astrophysics Data System (ADS)

Rizzetto, Federica; Tosi, Luigi

2012-07-01

The aim of the present paper is to examine the effects of long- and short-term sea-level fluctuations (i.e. relative sea-level rise and tides) on the geomorphologic evolution of modern tidal channels through the joint interpretation of channel modifications, the 1938-2010 yearly time series of relative sea-level rise, and the variations of strength and frequency of high tides which occurred in the same period. We analyzed a salt marsh area not particularly modified by human interventions, located in the northern Venice Lagoon, Italy. The availability of a long historical record of high-resolution aerial photographs provided us the opportunity to reconstruct in detail the evolution of the drainage patterns from 1938 to the present. Results from our analyses gave us information about the degree of control of long- and short-term sea-level fluctuations on planimetric development of tidal channels and provided demonstration of the rapid response of the drainage network to these oscillations. We found that both relative sea-level rise and high tide frequency greatly influenced salt marsh margin shift and meander evolution of tidal channels in the long term, but short-term sinuosity changes of creeks were often also closely related to tide variations. Channels nearer the marsh margin were more exposed to the action of the increasing tides.

The Water Level and Transport Regimes of the Lower Columbia River

NASA Astrophysics Data System (ADS)

Jay, D. A.

2011-12-01

Tidal rivers are vital, spatially extensive conduits of material from land to sea. Yet the tidal-fluvial regime remains poorly understood relative to the bordering fluvial and estuarine/coastal regimes with which it interacts. The 235km-long Lower Columbia River (LCR) consists of five zones defined by topographic constrictions: a 5km-long ocean-entrance, the lower estuary (15km), an energy-minimum (67km), the tidal river (142km), and a landslide zone (5km). Buoyant plume lift-off occurs within the entrance zone, which is dominated by tidal and wave energy. The lower estuary is strongly tidally, amplifies the semidiurnal tide, and has highly variable salinity intrusion. Tidal and fluvial influences are balanced in the wide energy-minimum, into which salinity intrudes during low-flow periods. It has a turbidity maximum and a dissipation minimum at its lower end, but a water-level variance minimum at its landward end. The tidal river shows a large increase in the ratio of fluvial-to-tidal energy in the landward direction and strong seasonal variations in tidal properties. Because tidal monthly water level variations are large, low waters are higher on spring than neap tides. The steep landslide zone has only weak tides and is the site of the most seaward hydropower dam. Like many dammed systems, the LCR has pseudo-tides: daily and weakly hydropower peaking waves that propagate seaward. Tidal constituent ratios vary in the alongchannel direction due to frictional non-linearities, the changing balance of dissipation vs. propagation, and power peaking. Long-term changes to the system have occurred due to climate change and direct human manipulation. Flood control, hydropower regulation, and diversion have reduced peak flows, total load and sand transport by ~45, 50 and 80%, respectively, causing a blue-shift in the flow and water level power spectra. Overbank flows have been largely eliminated through a redundant combination of diking and flow regulation. Export of sand to the ocean now occurs mainly through dredging, though fine sediment export may be higher than natural levels. Reduced sediment input and navigational development have reduced water levels in the upper tidal river by ~0.4/1.5m during low/high flow periods, impacting both navigation and shallow-water habitat availability. Tidal amplitudes have increased due both to increased coastal tides and reduced friction. This exacerbates difficulties with low-waters during fall neap tides. Climate-induced changes have so far had much less influence on system properties than human modifications. At present, regional sea level (RSL) rise and tectonic change are in balance, yielding no net sea level rise.

Water-surface elevations for the high tide of December 15, 1977, in the Puget Sound region, Washington

USGS Publications Warehouse

Nelson, L.M.

1985-01-01

An unusually high oceanic tide on December 15, 1977, caused flooding of lowlying, nearshore parts of western Washington, including several areas in the Puget Sound region. At Seattle, the December 15 high tide of 14.8 feet above MLLW (mean lower low water datum; 8.55 feet above the National Geodetic Vertical Daltum of 1929, or NGVD) was 0.1 foot higher than the 100-year high tide. At Neah Bay, near the western end of the Straits of Juan de Fuca, however, the high tide of 8.77 feet MLLW (4.55 feet NGVD) on that date was 3.2 feet lower than the 100-year high tide. This study has identified the observed December 15 high-tide elevations at many locations in the Puget Sound region. The observed high tide then was much higher than predicted in most of the Puget Sound region, primarily as the result of a very low barametric pressure. Little damage from wind waves was reported. Elevation profiles for the predicted and observed high tides on December 15 and for several other selected tide levels indicate an increase in the maximum height in the inland direction, except near Port Angeles, and show abrupt changes in tidal elevations at three constrictions - Admiralty Inlet, Tacoma Narrows, and Deception Pass. (USGS)

Consumers control diversity and functioning of a natural marine ecosystem.

PubMed

Altieri, Andrew H; Trussell, Geoffrey C; Ewanchuk, Patrick J; Bernatchez, Genevieve; Bracken, Matthew E S

2009-01-01

Our understanding of the functional consequences of changes in biodiversity has been hampered by several limitations of previous work, including limited attention to trophic interactions, a focus on species richness rather than evenness, and the use of artificially assembled communities. In this study, we manipulated the density of an herbivorous snail in natural tide pools and allowed seaweed communities to assemble in an ecologically relevant and non-random manner. Seaweed species evenness and biomass-specific primary productivity (mg O(2) h(-1) g(-1)) were higher in tide pools with snails because snails preferentially consumed an otherwise dominant seaweed species that can reduce biomass-specific productivity rates of algal assemblages. Although snails reduced overall seaweed biomass in tide pools, they did not affect gross primary productivity at the scale of tide pools (mg O(2) h(-1) pool(-1) or mg O(2) h(-1) m(-2)) because of the enhanced biomass-specific productivity associated with grazer-mediated increases in algal evenness. Our results suggest that increased attention to trophic interactions, diversity measures other than richness, and particularly the effects of consumers on evenness and primary productivity, will improve our understanding of the relationship between diversity and ecosystem functioning and allow more effective links between experimental results and real-world changes in biodiversity.

Consumers Control Diversity and Functioning of a Natural Marine Ecosystem

PubMed Central

Altieri, Andrew H.; Trussell, Geoffrey C.; Ewanchuk, Patrick J.; Bernatchez, Genevieve; Bracken, Matthew E. S.

2009-01-01

Background Our understanding of the functional consequences of changes in biodiversity has been hampered by several limitations of previous work, including limited attention to trophic interactions, a focus on species richness rather than evenness, and the use of artificially assembled communities. Methodology and Principal Findings In this study, we manipulated the density of an herbivorous snail in natural tide pools and allowed seaweed communities to assemble in an ecologically relevant and non-random manner. Seaweed species evenness and biomass-specific primary productivity (mg O2 h−1 g−1) were higher in tide pools with snails because snails preferentially consumed an otherwise dominant seaweed species that can reduce biomass-specific productivity rates of algal assemblages. Although snails reduced overall seaweed biomass in tide pools, they did not affect gross primary productivity at the scale of tide pools (mg O2 h−1 pool−1 or mg O2 h−1 m−2) because of the enhanced biomass-specific productivity associated with grazer-mediated increases in algal evenness. Significance Our results suggest that increased attention to trophic interactions, diversity measures other than richness, and particularly the effects of consumers on evenness and primary productivity, will improve our understanding of the relationship between diversity and ecosystem functioning and allow more effective links between experimental results and real-world changes in biodiversity. PMID:19384410

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

PubMed

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

2011-01-01

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

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

PubMed Central

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

2010-01-01

Blooms of the toxic dinoflagellate, Karenia brevis, produce potent neurotoxins in marine aerosols. Recent studies have demonstrated acute changes in both symptoms and pulmonary function in asthmatics after only 1 hour of beach exposure to these aerosols. This study investigated if there were latent and/or sustained effects in asthmatics in the days following the initial beach exposure during periods with and without an active Florida red tide. Symptom data and spirometry data were collected before and after 1 hour of beach exposure. Subjects kept daily symptom diaries and measured their peak flow each morning for 5 days following beach exposure. During non-exposure periods, there were no significant changes in symptoms or pulmonary function either acutely or over 5 days of follow-up. After the beach exposure during an active Florida red tide, subjects had elevated mean symptoms which did not return to the pre-exposure baseline for at least 4 days. The peak flow measurements decreased after the initial beach exposure, decreased further within 24 hours, and continued to be suppressed even after 5 days. Asthmatics may continue to have increased symptoms and delayed respiratory function suppression for several days after 1 hour of exposure to the Florida red tide toxin aerosols. PMID:21499552

Fingerprints of Sea Level Rise on Changing Tides in the Chesapeake and Delaware Bays

NASA Astrophysics Data System (ADS)

Ross, Andrew C.; Najjar, Raymond G.; Li, Ming; Lee, Serena Blyth; Zhang, Fan; Liu, Wei

2017-10-01

Secular tidal trends are present in many tide gauge records, but their causes are often unclear. This study examines trends in tides over the last century in the Chesapeake and Delaware Bays. Statistical models show negative M2 amplitude trends at the mouths of both bays, while some upstream locations have insignificant or positive trends. To determine whether sea level rise is responsible for these trends, we include a term for mean sea level in the statistical models and compare the results with predictions from numerical and analytical models. The observed and predicted sensitivities of M2 amplitude and phase to mean sea level are similar, although the numerical model amplitude is less sensitive to sea level. The sensitivity occurs as a result of strengthening and shifting of the amphidromic system in the Chesapeake Bay and decreasing frictional effects and increasing convergence in the Delaware Bay. After accounting for the effect of sea level, significant negative background M2 and S2 amplitude trends are present; these trends may be related to other factors such as dredging, tide gauge errors, or river discharge. Projected changes in tidal amplitudes due to sea level rise over the 21st century are substantial in some areas, but depend significantly on modeling assumptions.

The double high tide at Port Ellen: Doodson's criterion revisited

NASA Astrophysics Data System (ADS)

Byrne, Hannah A. M.; Mattias Green, J. A.; Bowers, David G.

2017-07-01

Doodson proposed a minimum criterion to predict the occurrence of double high (or double low) waters when a higher-frequency tidal harmonic is added to the semi-diurnal tide. If the phasing of the harmonic is optimal, the condition for a double high water can be written bn2/a > 1 where b is the amplitude of the higher harmonic, a is the amplitude of the semi-diurnal tide, and n is the ratio of their frequencies. Here we expand this criterion to allow for (i) a phase difference ϕ between the semi-diurnal tide and the harmonic and (ii) the fact that the double high water will disappear in the event that b/a becomes large enough for the higher harmonic to be the dominant component of the tide. This can happen, for example, at places or times where the semi-diurnal tide is very small. The revised parameter is br2/a, where r is a number generally less than n, although equal to n when ϕ = 0. The theory predicts that a double high tide will form when this parameter exceeds 1 and then disappear when it exceeds a value of order n2 and the higher harmonic becomes dominant. We test these predictions against observations at Port Ellen in the Inner Hebrides of Scotland. For most of the data set, the largest harmonic of the semi-diurnal tide is the sixth diurnal component, for which n = 3. The principal lunar and solar semi-diurnal tides are about equal at Port Ellen and so the semi-diurnal tide becomes very small twice a month at neap tides (here defined as the smallest fortnightly tidal range). A double high water forms when br2/a first exceeds a minimum value of about 1.5 as neap tides are approached and then disappears as br2/a then exceeds a second limiting value of about 10 at neap tides in agreement with the revised criterion.

Recruitment of fish larvae and juveniles into two estuarine nursery areas with evidence of ebb tide use

NASA Astrophysics Data System (ADS)

Pattrick, Paula; Strydom, Nadine

2014-08-01

Recruitment of larvae and early juveniles, against the ebb tide in the shallower, slower-flowing marginal areas of two permanently open estuaries in the Eastern Cape, South Africa was observed. To determine tidal, diel and seasonal variations of larval and juvenile fish recruitment, fyke nets were used during a 24-hour cycle over two years from December 2010 to October 2012. On either side of each estuary bank, two fyke nets with mouth openings facing opposite directions (i.e. one net facing the incoming or outgoing tide and the other facing the opposing direction) were used to sample fishes. The aims of this study were to determine if 1) on the flood tide, were the nets facing the incoming tide collecting more larvae and early juveniles recruiting into the estuarine nursery area, than the nets facing the opposing direction and 2) on the ebb tide, were the nets facing the sea, and hence the opposing direction of the outgoing ebb tide, collecting more fishes recruiting into the nursery against the ebb tide, than the nets facing the outgoing ebb tide? Larval and juvenile fish CPUE, species diversity and richness varied seasonally between estuarine systems and between diel and tidal conditions. Highest catches were recorded on the flood tide, which coincided with sunrise in the Swartkops Estuary. Greatest catches of larvae and early juveniles were observed during the ebb tide at night in the Sundays Estuary. On the ebb tide, higher catches of several dominant species and several commercially important fishery species, occurred in the fyke nets which faced the sea, indicating the early developmental stages of these fish species are not necessarily being lost from the nursery. These larvae and juveniles are actively swimming against the ebb tide in the shallower, slower-flowing marginal areas facilitating recruitment against ebb flow.

Inquiry-based Instruction with Archived, Online Data: An Intervention Study with Preservice Teachers

NASA Astrophysics Data System (ADS)

Ucar, Sedat; Trundle, Kathy Cabe; Krissek, Lawrence

2011-03-01

This mixed methods study described preservice teachers' conceptions of tides and explored the efficacy of integrating online data into inquiry-based instruction. Data sources included a multiple-choice assessment and in-depth interviews. A total of 79 participants in secondary, middle, and early childhood teacher education programs completed the multiple-choice assessment of their baseline knowledge of tides-related concepts. A sub-group of 29 participants also was interviewed to explore their understanding of tides in more detail before instruction. Eighteen of those 29 teachers participated in the instruction, were interviewed again after the instruction, and completed the multiple-choice assessment as a posttest. The interview data sets were analyzed via a constant comparative method in order to produce profiles of each participant's pre- and post-instruction conceptual understandings of tides. Additional quantitative analysis consisted of a paired-sample t-test, which investigated the changes in scores before and after the instructional intervention. Before instruction, all participants held alternative or alternative fragments as their conceptual understandings of tides. After completing the inquiry-based instruction that integrated online tidal data, participants were more likely to hold a scientific conceptual understanding. After instruction, some preservice teachers continued to hold on to the conception that the rotation of the moon around the Earth during one 24-hour period causes the tides to move with the moon. The quantitative results, however, indicated that pre- to post-instruction gains were significant. The findings of this study provide evidence that integrating Web-based archived data into inquiry-based instruction can be used to effectively promote conceptual change among preservice teachers.

A tide prediction and tide height control system for laboratory mesocosms

PubMed Central

Long, Jeremy D.

2015-01-01

Experimental mesocosm studies of rocky shore and estuarine intertidal systems may benefit from the application of natural tide cycles to better replicate variation in immersion time, water depth, and attendant fluctuations in abiotic and edaphic conditions. Here we describe a stand-alone microcontroller tide prediction open-source software program, coupled with a mechanical tidal elevation control system, which allows continuous adjustment of aquarium water depths in synchrony with local tide cycles. We used this system to monitor the growth of Spartina foliosa marsh cordgrass and scale insect herbivores at three simulated shore elevations in laboratory mesocosms. Plant growth decreased with increasing shore elevation, while scale insect population growth on the plants was not strongly affected by immersion time. This system shows promise for a range of laboratory mesocosm studies where natural tide cycling could impact organism performance or behavior, while the tide prediction system could additionally be utilized in field experiments where treatments need to be applied at certain stages of the tide cycle. PMID:26623195

Mapping the nonstationary internal tide with satellite altimetry

NASA Astrophysics Data System (ADS)

Zaron, Edward D.

2017-01-01

Temporal variability of the internal tide has been inferred from the 23 year long combined records of the TOPEX/Poseidon, Jason-1, and Jason-2 satellite altimeters by combining harmonic analysis with an analysis of along-track wavenumber spectra of sea-surface height (SSH). Conventional harmonic analysis is first applied to estimate and remove the stationary components of the tide at each point along the reference ground tracks. The wavenumber spectrum of the residual SSH is then computed, and the variance in a neighborhood around the wavenumber of the mode-1 baroclinic M2 tide is interpreted as the sum of noise, broadband nontidal processes, and the nonstationary tide. At many sites a bump in the spectrum associated with the internal tide is noted, and an empirical model for the noise and nontidal processes is used to estimate the nonstationary semidiurnal tidal variance. The results indicate a spatially inhomogeneous pattern of tidal variability. Nonstationary tides are larger than stationary tides throughout much of the equatorial Pacific and Indian Oceans.

Some dinophycean red tide plankton species generate a superoxide scavenging substance.

PubMed

Sato, Emiko; Niwano, Yoshimi; Matsuyama, Yukihiko; Kim, Daekyung; Nakashima, Takuji; Oda, Tatsuya; Kohno, Masahiro

2007-03-01

Recent studies indicate that some raphidophycean red tide flagellates produce substances able to scavenge superoxide, whereas there have been no reports on superoxide scavenger production by dinophycean red tide flagellates. In this study, we examined the superoxide-scavenging activity of aqueous extracts from dinophycean red tide flagellates, Gymnodinium spp., Scrippsiella trochoidea, and Karenia sp., by a luminol analog L-012-dependent chemiluminescence (CL) method and an electron spin resonance (ESR)-spin trapping method, and compared the activity to that of raphidophycean red tide flagellates, Chattonella spp., Heterosigma akashiwo, and Fibrocapsa japonica. In the experiment applying the L-012-dependent CL method, only the aqueous extracts from raphidophycean red tide flagellates showed superoxide-scavenging activity. On the other hand, applying the ESR-spin trapping method, we found that the aqueous extracts from dinophycean red tide flagellates also showed superoxide-scavenging activity. This is the first report on the production of a superoxide-scavenger by dinophycean red tide flagellates.

Global ocean tide models on the eve of Topex/Poseidon

NASA Technical Reports Server (NTRS)

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.

New Miscellaneous Results in Tides from Topex/Poseidon

NASA Technical Reports Server (NTRS)

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

2000-01-01

This paper describes a variety of new results concerning ocean tides that have been derived from Topex/Poseidon satellite altimeter data. Most of these results are based on new tidal solutions employing nearly 8 years of data. The topics covered include internal tides and long-period tides.

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

NASA Astrophysics Data System (ADS)

Lühr, H.; Manoj, C.

2013-08-01

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 strong dependence on solar flux level with increasing amplitudes towards solar maximum. We are not aware of any previous studies mentioning this behaviour of SW3. The main focus of this study is to present the observed EEJ spectrum and its relation to tidal driving. For several of the identified spectral components we cannot offer convincing explanations for the generation mechanisms.

The role of extreme floods in estuary-coastal behaviour: contrasts between river- and tide-dominated microtidal estuaries

NASA Astrophysics Data System (ADS)

Cooper, J. A. G.

2002-06-01

Contrasting modes of sedimentation and facies arrangement in tide- and river-dominated microtidal estuaries arise from the degree to which river or tidal discharge and sediment supply influences an estuary. A distinct facies gradation exists in tide-dominated systems from sandy, barrier/tidal delta-associated environments at the coast through deep mud-dominated middle reaches to fluvial sediment in the upper reaches. In river-dominated systems, fluvial sediment extends to the barrier and flood-tidal deltas are poorly developed or absent from the estuary. A number of independent observations during extreme floods on the South African coast indicate that these types of estuary respond differently to extreme river floods and that the mode of response corresponds to estuary type. Tide-dominated systems exhibit preferential erosion of noncohesive barrier and tidal delta sediments during river floods while the middle reaches remain little modified. River-dominated systems experience consistent erosion throughout their channel length during extreme floods. The increased cohesion of riverine sediments and stabilisation of bars by vegetation in river-dominated channels means that higher magnitude floods are necessary to effect significant morphological change. Barrier erosion, including the tidal delta, results in deposition of an ephemeral delta composed almost entirely of sands from these deposits in tide-dominated estuaries. In river-dominated systems, eroded channel sediments and material from the river catchment may augment barrier sediments in the ephemeral delta deposit. Post-flood, wave-reworking of ephemeral delta sediments acts to restore barriers to pre-flood morphology within a few years; however, in river-dominated systems, the additional sediment volume may produce significant coastal progradation that requires several years or decades to redistribute. These different modes of flood response mediated by the nature of the estuary have implications for coastal behaviour at the time scale of months to several decades. Estuary-coastal behaviour at river-dominated estuaries may be influenced for several decades by post-flood morphological adjustment. Tide-dominated estuaries, however, respond more rapidly in reworking flood-eroded sediment and are typically fully adjusted to modal wave and tidal conditions within a few months to a few years. In addition, the facies arrangement within the two estuary types renders tide-dominated estuaries more responsive to minor floods, while river-dominated estuaries, by virtue of more cohesive channel sediments, require greater discharges to effect significant morphological change.

Exhaustive testing of recent oceanic and Earth tidal models using combination of tide gravity data from GGP and ICET data banks

NASA Astrophysics Data System (ADS)

Kopaev, A.; Ducarme, B.

2003-04-01

We have used the most recent oceanic tidal models e.g. FES’99/02, GOT’00, CSR’4, NAO’99 and TPXO’5/6 for tidal gravity loading computations using LOAD’97 software. Resulting loading vectors were compared against each other in different regions located at different distances from the sea coast. Results indicate good coincidence for majority of models at the distances larger than 100-200 km, excluding some regions where mostly CSR’4 and TPXO have problems. Outlying models were rejected for this regions and mean loading vectors have been calculated for more than 200 tidal gravity stations from GGP and ICET data banks, representing state of the art of tidal loading correction. Corresponding errors in d-factors and phase lags are generally smaller than 0.1 % resp. 0.05o, that means that we do not have the real troubles with loading corrections and more attention should be applied to the calibration values and phase lag determination accuracies. Corrected values agree with DDW model values very well (within 0.2 %) for majority of GGP stations, whereas some of very good (Chinese network mainly) ICET tidal gravity stations clearly demonstrate statistically significant (up to 0.5 %) anomalies that seems not connected either with calibration troubles or loading problems. Various possible reasons including instrumental and geophysical will be presented and discussed.

A comparative study of the mechanisms of migrating diurnal tidal variability due to interaction with propagating planetary waves

NASA Astrophysics Data System (ADS)

Chang, Loren; Palo, Scott; Liu, Hanli

The migrating diurnal tide is one of the dominant dynamical features of the Earth's Mesosphere and Lower Thermosphere (MLT) region, particularly at low latitudes. As an actively forced disturbance with a period of 24 hours and westward zonal wave number 1, the migrating diurnal tide represents the atmospheric response to the largest component of solar forcing, propagating upwards from excitation regions in the lower atmosphere. While the seasonal evolution of the migrating diurnal tide has been well explored, ground-based observations of the tide have exhibited a modulation of tidal amplitudes at periods related to those of propagating planetary waves generally present in the region, as well as a decrease in tidal amplitudes during large planetary wave events. Past studies have attributed tidal amplitude modulation to the presence of child waves generated as a byproduct of nonlinear wave-tide interactions. The resulting child waves have frequencies and wavenumbers that are the sum and difference of those of the parent waves. Many questions still remain about the nature and physical drivers responsible for such interactions. The conditions under which various planetary waves may or may not interact with the atmospheric tides, the overall effect on the tidal response, as well as the physical mechanisms coupling the planetary wave and the tide interaction, which has not clearly been determined. These questions are addressed in a recent modeling study, by examining two general categories of planetary waves that are known to attain significant amplitudes in the low latitude and equa-torial region where the migrating diurnal tide is dominant. These are the eastward propagating class of ultra fast Kelvin (UFK) waves with periods near three days which attain their largest amplitudes in the temperature and zonal wind fields of the equatorial lower thermosphere. The second wave examined is the quasi-two day wave (QTDW) which is a westward propagating Rossby wave and can amplify raplidly due to a nonlinear interaction with the mean flow and attain large amplitudes in both components of the wind field and the temperature field in the summer hemisphere over a period of a few days during post-solstice periods. The NCAR Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIME-GCM) and Whole Atmosphere Community Climate Model (WACCM) are both state of the art general circulation models and are utilized to simulate the aforementioned planetary waves. The goal of this study is to identify specific changes in the structure of the migrat-ing diurnal tide due to interaction with these planetary waves and to understand the driving processes. The physical mechanisms that serve to couple the tide and the planetary waves are identified through analysis of the tidal momentum tendencies, the background atmosphere, as well as changes in tidal propagation. Results showing the impact of these planetary waves on the structure and evolution of the migrating diurnal tide will be presented.

Cross-shelf transport into nearshore waters due to shoaling internal tides in San Pedro Bay, CA

USGS Publications Warehouse

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.

Assessment of radar altimetry correction slopes for marine gravity recovery: A case study of Jason-1 GM data

NASA Astrophysics Data System (ADS)

Zhang, Shengjun; Li, Jiancheng; Jin, Taoyong; Che, Defu

2018-04-01

Marine gravity anomaly derived from satellite altimetry can be computed using either sea surface height or sea surface slope measurements. Here we consider the slope method and evaluate the errors in the slope of the corrections supplied with the Jason-1 geodetic mission data. The slope corrections are divided into three groups based on whether they are small, comparable, or large with respect to the 1 microradian error in the current sea surface slope models. (1) The small and thus negligible corrections include dry tropospheric correction, inverted barometer correction, solid earth tide and geocentric pole tide. (2) The moderately important corrections include wet tropospheric correction, dual-frequency ionospheric correction and sea state bias. The radiometer measurements are more preferred than model values in the geophysical data records for constraining wet tropospheric effect owing to the highly variable water-vapor structure in atmosphere. The items of dual-frequency ionospheric correction and sea state bias should better not be directly added to range observations for obtaining sea surface slopes since their inherent errors may cause abnormal sea surface slopes and along-track smoothing with uniform distribution weight in certain width is an effective strategy for avoiding introducing extra noises. The slopes calculated from radiometer wet tropospheric corrections, and along-track smoothed dual-frequency ionospheric corrections, sea state bias are generally within ±0.5 microradians and no larger than 1 microradians. (3) Ocean tide has the largest influence on obtaining sea surface slopes while most of ocean tide slopes distribute within ±3 microradians. Larger ocean tide slopes mostly occur over marginal and island-surrounding seas, and extra tidal models with better precision or with extending process (e.g. Got-e) are strongly recommended for updating corrections in geophysical data records.

ENSO effects on MLT diurnal tides: A 21 year reanalysis data-driven GAIA model simulation

NASA Astrophysics Data System (ADS)

Liu, Huixin; Sun, Yang-Yi; Miyoshi, Yasunobu; Jin, Hidekatsu

2017-05-01

Tidal responses to El Niño-Southern Oscillation (ENSO) in the mesosphere and lower thermosphere (MLT) are investigated for the first time using reanalysis data-driven simulations covering 21 years. The simulation is carried out with the Ground-to-topside Atmosphere-Ionosphere model for Aeronomy (GAIA) during 1996-2016, which covers nine ENSO events. ENSO impacts on diurnal tides at 100 km altitude are analyzed and cross-compared among temperature (T), zonal wind (U), and meridional wind (V), which reveals the following salient features: (1) Tidal response can differ significantly among T, U, and V in terms of magnitude and latitudinal structure, making detection of ENSO effects sensitive to the parameter used and the location of a ground station; (2) the nonmigrating DE3 tide in T and U shows a prominent hemisphere asymmetric response to La Niña, with an increase between 0° and 30°N and a decrease between 30° and 0°S. In contrast, DE3 in V exhibits no significant response; (3) the migrating DW1 enhances during El Niño in equatorial regions for T and U but in off-equatorial regions for V. As the first ENSO study based on reanalysis-driven simulations, GAIA's full set of tidal responses in T, U, and V provides us with a necessary global context to better understand and cross-compare observations during ENSO events. Comparisons with observations during the 1997-98 El Niño and 2010-11 La Niña reveal good agreement in both magnitude and timing. Comparisons with "free-run" WACCM simulations (T) show consistent results in nonmigrating tides DE2 and DE3 but differences in the migrating DW1 tide.

Responses of water environment to tidal flat reduction in Xiangshan Bay: Part I hydrodynamics

NASA Astrophysics Data System (ADS)

Li, Li; Guan, Weibing; Hu, Jianyu; Cheng, Peng; Wang, Xiao Hua

2018-06-01

Xiangshan Bay consists of a deep tidal channel and three shallow inlets. A large-scale tidal flat has been utilized through coastal construction. To ascertain the accumulate influences of these engineering projects upon the tidal dynamics of the channel-inlets system, this study uses FVCOM to investigate the tides and flow asymmetries of the bay, and numerically simulate the long-term variations of tidal dynamics caused by the loss of tidal flats. It was found that the reduction of tidal flat areas from 1963 to 2010 slightly dampened M2 tidal amplitudes (0.1 m, ∼6%) and advanced its phases by reducing shoaling effects, while amplified M4 tidal amplitudes (0.09 m, ∼27%) and advanced its phases by reducing bottom friction, in the inner bay. Consequently, the ebb dominance was dampened indicated by reduced absolute value of elevation skewness (∼20%) in the bay. The tides and tidal asymmetry were impacted by the locations, areas and slopes of the tidal flats through changing tidal prism, shoaling effect and bottom friction, and consequently impacted tidal duration asymmetry in the bay. Tides and tidal asymmetry were more sensitive to the tidal flat at the head of the bay than the side bank. Reduced/increased tidal flat slopes around the Tie inlet dampened the ebb dominance. Tidal flat had a role in dissipating the M4 tide rather than generating it, while the advection only play a secondary role in generating the M4 tide. The full-length tidal flats reclamation would trigger the reverse of ebb to flood dominance in the bay. This study would be applicable for similar narrow bays worldwide.

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

NASA Technical Reports Server (NTRS)

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

2001-01-01

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

Can Satellite Geodesy Disentangle Holocene Rebound and Present-Day Glacier Balance Signatures?

NASA Technical Reports Server (NTRS)

Irvins, E.; James, T.; Yoder, C.

1995-01-01

The secular drift of the precession of the ascending node of the LAGOES -1 satellite is apparently linked to the Earth s paleoclimate through the slow viscous response of the mantle to ice sheet/ocean mass transfer during the last great continental deglaciation . The secular node acceleration is particularly sensitive to the longest wavelengths of the paleo -surface loading that have been memorized by the mantle glacio -isostatic flow. Tide gauge records for the last 130 years show a post-glacial rebound-corrected sea-level rise of 2.4 n 0.9 mm yr-1.

Non-linear motions in reprocessed GPS station position time series

NASA Astrophysics Data System (ADS)

Rudenko, Sergei; Gendt, Gerd

2010-05-01

Global Positioning System (GPS) data of about 400 globally distributed stations obtained at time span from 1998 till 2007 were reprocessed using GFZ Potsdam EPOS (Earth Parameter and Orbit System) software within International GNSS Service (IGS) Tide Gauge Benchmark Monitoring (TIGA) Pilot Project and IGS Data Reprocessing Campaign with the purpose to determine weekly precise coordinates of GPS stations located at or near tide gauges. Vertical motions of these stations are used to correct the vertical motions of tide gauges for local motions and to tie tide gauge measurements to the geocentric reference frame. Other estimated parameters include daily values of the Earth rotation parameters and their rates, as well as satellite antenna offsets. The solution GT1 derived is based on using absolute phase center variation model, ITRF2005 as a priori reference frame, and other new models. The solution contributed also to ITRF2008. The time series of station positions are analyzed to identify non-linear motions caused by different effects. The paper presents the time series of GPS station coordinates and investigates apparent non-linear motions and their influence on GPS station height rates.

Frontiers in Outreach and Education: The Florida Red Tide Experience.

PubMed

Nierenberg, Kate; Hollenbeck, Julie; Fleming, Lora E; Stephan, Wendy; Reich, Andrew; Backer, Lorraine C; Currier, Robert; Kirkpatrick, Barbara

2011-05-01

To enhance information sharing and garner increased support from the public for scientific research, funding agencies now typically require that research groups receiving support convey their work to stakeholders. The National Institute of Environmental Health Sciences-(NIEHS) funded Aerosolized Florida Red Tide P01 research group (Florida Red Tide Research Group) has employed a variety of outreach strategies to meet this requirement. Messages developed from this project began a decade ago and have evolved from basic print material (fliers and posters) to an interactive website, to the use of video and social networking technologies, such as Facebook and Twitter. The group was able to track dissemination of these information products; however, evaluation of their effectiveness presented much larger challenges. The primary lesson learned by the Florida Red Tide Research Group is that the best ways to reach specific stakeholders is to develop unique products or services to address specific stakeholders needs, such as the Beach Conditions Reporting System. Based on the experience of the Group, the most productive messaging products result when scientific community engages potential stakeholders and outreach experts during the very initial phases of a project.

Human factors and tidal influences on water quality of an urban river in Can Tho, a major city of the Mekong Delta, Vietnam.

PubMed

Ozaki, Hirokazu; Co, Thi Kinh; Le, Anh Kha; Pham, Viet Nu; Nguyen, Van Be; Tarao, Mitsunori; Nguyen, Huu Chiem; Le, Viet Dung; Nguyen, Hieu Trung; Sagehashi, Masaki; Ninomiya-Lim, Sachi; Gomi, Takashi; Hosomi, Masaaki; Takada, Hideshige

2014-02-01

In this study, we focused on water quality in an urban canal and the Mekong River in the city of Can Tho, a central municipality of the Mekong Delta region, southern Vietnam. Water temperature, pH, electrical conductivity, BOD5, CODCr, Na(+), Cl(-), NH4 (+)-N, SO4 (2-)-S, NO3 (-)-N, and NO2 (-)-N for both canal and river, and tide level of the urban canal, were monitored once per month from May 2010 to April 2012. The urban canal is subject to severe anthropogenic contamination, owing to poor sewage treatment. In general, water quality in the canal exhibited strong tidal variation, poorer at lower tides and better at higher tides. Some anomalies were observed, with degraded water quality under some high-tide conditions. These were associated with flow from the upstream residential area. Therefore, it was concluded that water quality in the urban canal changed with a balance between dilution effects and extent of contaminant supply, both driven by tidal fluctuations in the Mekong River.

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

PubMed

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.

[Retrieve of red tide distributions from MODIS data based on the characteristics of water spectrum].

PubMed

Qiu, Zhong-Feng; Cui, Ting-Wei; He, Yi-Jun

2011-08-01

After comparing the spectral differences between red tide water and normal water, we developed a method to retrieve red tide distributions from MODIS data based on the characteristics of red tide water spectrum. The authors used the 119 series of in situ observations to validate the method and found that only one observation has not been detected correctly. The authors then applied this method to MODIS data on April 4, 2005. In the research areas three locations of red tide water were apparently detected with the total areas about 2 000 km2. The retrieved red tide distributions are in good agreement with the distributions of high chlorophyll a concentrations. The research suggests that the method is available to eliminating the influence of suspended sediments and can be used to retrieve the locations and areas of red tide water.

Lunar tidal acceleration obtained from satellite-derived ocean tide parameters

NASA Technical Reports Server (NTRS)

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.

Herbivores, tidal elevation, and species richness simultaneously mediate nitrate uptake by seaweed assemblages.

PubMed

Bracken, Matthew E S; Jones, Emily; Williams, Susan L

2011-05-01

In order for research into the consequences of biodiversity changes to be more applicable to real-world ecosystems, experiments must be conducted in the field, where a variety of factors other than diversity can affect the rates of key biogeochemical and physiological processes. Here, we experimentally evaluate the effects of two factors known to affect the diversity and composition of intertidal seaweed assemblages--tidal elevation and herbivory--on nitrate uptake by those assemblages. Based on surveys of community composition at the end of a 1.5-year press experiment, we found that both tide height and herbivores affected seaweed community structure. Not surprisingly, seaweed species richness was greater at lower tidal elevations. Herbivores did not affect richness, but they altered the types of species that were present; seaweed species characterized by higher rates of nitrate uptake were more abundant in herbivore-removal plots. Both tide height and herbivores affected nitrate uptake by seaweed assemblages. Individual seaweed species, as well as entire seaweed assemblages, living higher on the shore had greater rates of biomass-specific nitrate uptake, particularly at high ambient nitrate concentrations. Grazed seaweed assemblages exhibited reduced nitrate uptake, but only at low nitrate concentrations. We evaluated the effect of seaweed richness on nitrate uptake, both alone and after accounting for effects of tidal elevation and herbivores. When only richness was considered, we found no effect on uptake. However, when simultaneous effects of richness, tide height, and herbivores on uptake were evaluated, we found that all three had relatively large and comparable effects on nitrate uptake coefficients and that there was a negative relationship between seaweed richness and nitrate uptake. Particularly because effects of richness on uptake were not apparent unless the effects of tide height and herbivory were also considered, these results highlight the importance of considering the effects of environmental context when evaluating the consequences of biodiversity change in more realistic systems.

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

Treesearch

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...

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

NASA Astrophysics Data System (ADS)

Andersen, Ole B.; Egbert, Gary D.; Erofeeva, Svetlana Y.; Ray, Richard D.

2006-12-01

Overtides and compound tides are generated by nonlinear mechanisms operative primarily in shallow waters. Their presence complicates tidal analysis owing to the multitude of new constituents and their possible frequency overlap with astronomical tides. The science of nonlinear tides was greatly 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 to regions with fewer in situ measurements will require improved understanding of error covariance models because these control the tradeoffs between fitting hydrodynamics and data, a delicate issue in coastal regions. While M_4 can now be robustly determined along the Topex/Poseidon satellite ground tracks, many other compound tides face serious aliasing problems.

Modeling influence of tide stages on forecasts of the 2010 Chilean tsunami

NASA Astrophysics Data System (ADS)

Uslu, B. U.; Chamberlin, C.; Walsh, D.; Eble, M. C.

2010-12-01

The impact of the 2010 Chilean tsunami is studied using the NOAA high-resolution tsunami forecast model augmented to include modeled tide heights in addition to deep-water tsunami propagation as boundary-condition input. The Chilean tsunami was observed at the Los Angeles tide station at mean low water, Hilo at low, Pago Pago at mid tide and Wake Island near high tide. Because the tsunami arrived at coastal communities at a representative variety of tide stages, 2010 Chile tsunami provides opportunity to study the tsunami impacts at different tide levels to different communities. The current forecast models are computed with a constant tidal stage, and this study evaluates techniques for adding an additional varying predicted tidal component in a forecasting context. Computed wave amplitudes, wave currents and flooding are compared at locations around the Pacific, and the difference in tsunami impact due to tidal stage is studied. This study focuses on how tsunami impacts vary with different tide levels, and helps us understand how the inclusion of tidal components can improve real-time forecast accuracy.

Impact of tides in a baroclinic circulation model of the Adriatic Sea

NASA Astrophysics Data System (ADS)

Guarnieri, A.; Pinardi, N.; Oddo, P.; Bortoluzzi, G.; Ravaioli, M.

2013-01-01