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Breaker, L.C.; Murty, T.S., and Carroll, D., 2014. A frequency domain approach for predicting the signal strength of tsunamis at coastal tide gauges. A method for predicting the signal strength of a tsunami at coastal tide gauges once the event is underway is presented. It is based on the calculation of a transfer function for a linear system whose input is obtained from Deep-ocean Assessment and Reporting of Tsunamis (DART) bottom pressure recorders (BPRs) and the output from coastal tide gauges. To perform the calculations, a data window for the input and output signals must initially be chosen that requires a compromise between signal purity and resolution. Limited experience suggests that windows in the range of 6–12 hours duration are a reasonable choice for 1-minute data. The method is illustrated with three examples, the first two taken from the tsunami generated by the Great Tōhoku Earthquake of 2011 and the third from the tsunami generated by the Chilean earthquake of 2010. Magnitude spe...

A review of the present status of the global warming science is presented in this paper. The term global warming is now popularly used to refer to the recent reported increase in the mean surface temperature of the earth; this increase being attributed to increasing human activity and in particular to the increased concentration of greenhouse gases (carbon dioxide, methane and nitrous oxide) in the atmosphere. Since the mid to late 1980s there has been an intense and often emotional debate on this topic. The various climate change reports (1996, 2001) prepared by the IPCC (Intergovernmental Panel on Climate Change), have provided the scientific framework that ultimately led to the Kyoto protocol on the reduction of greenhouse gas emissions (particularly carbon dioxide) due to the burning of fossil fuels. Numerous peer-reviewed studies reported in recent literature have attempted to verify several of the projections on climate change that have been detailed by the IPCC reports. The global warming debate as presented by the media usually focuses on the increasing mean temperature of the earth, associated extreme weather events and future climate projections of increasing frequency of extreme weather events worldwide. In reality, the climate change issue is considerably more complex than an increase in the earth's mean temperature and in extreme weather events. Several recent studies have questioned many of the projections of climate change made by the IPCC reports and at present there is an emerging dissenting view of the global warming science which is at odds with the IPCC view of the cause and consequence of global warming. Our review suggests that the dissenting view offered by the skeptics or opponents of global warming appears substantially more credible than the supporting view put forth by the proponents of global warming. Further, the projections of future climate change over the next fifty to one hundred years is based on insufficiently verified climate models and are therefore not considered reliable at this point in time.

This is a review of sea level data performed at three selected stations (Quebec-Lauzon, Harrington Harbour,and Halifax) in eastern Canada in order to investigate the seasonal trends and other long-term and short-term changes which occurred since the beginning of the 20th century. Stations situated in riverine or estuarine regions (e.g., Quebec-Lauzon) are significantly affected by freshwater flow in their annual cycle of sea level changes and exhibit a definite maximum in spring and minimum in autumn-winter. Other stations situated in the eastern half of the Gulf of St. Lawrence (e.g., Harrington Harbour) or near the open Atlantic coast (Halifax) mainly follow the general cycle of subarctic regions, with lows in spring-summer and highs in autumn-winter. Such seasonal variations appear to be related to the atmospheric pressure and baroclinic current variations. Secular trends in mean sea level in eastern Canadian waterbodies show a mean rise of about 2.56 mm/yr -1 due to tectonic motions, that is, land sub...

There has been extensive loss of life and damage associated with severe tropical cyclones in the South Asian region. The Bay of Bengal and the Arabian Sea are the two marginal seas of the North Indian Ocean and have given rise to storm surges during the pre-monsoon (April-May) and the post- monsoon period (October-December). Table 1 lists the events where the loss of lives were 1000 or more.

Interannual variations of sea level along the Bangladesh coast are quite pronounced and often dominate the long-term sea level trends that are taking place. The El Nino/Southern Oscillation (ENSO) induced variation is an important component of interannual mode of variations. The present article deals with the relationship between the sea level variations along the Bangladesh coast and the Southern Oscillation phenomenon. The mean tide level data of monsoon season (June to September) pertaining to Hiron Point (in Sundarbans) and Char Changa (on the mouth of Meghna River) have been analyzed and correlated to the Southern Oscillation Index (SOI). The annual variation of mean tide level in the coastal areas of Bangladesh reveals that the tide level reaches its peak during the monsoon season. The maximum tide level during the calendar year is recorded in August. Thus, it is not surprising that the inundation of the coastal belt of Bangladesh due to the floods is most common during the summer monsoon season, es...

Hourly sea level records from three stations in eastern Canada (Quebec-Lauzon, Harrington-Harbour and Halifax) are analyzed both in frequency domain from 1970 to 1979 and in time domain during 1973. At the three stations, the deterministic model explains 90 to 96% of the total variability of sea level. The semidiurnal and diurnal tides contribute largely to its variations. The residual series, less than 10% of the initial variations of sea level, contain irregular values including extreme values of seiches and storm surges. Such random variations are analyzed and modeled following the method described by Box and Jenkins (1976). The long period variations (2 to 30 days) can be attributed to meteorological forcing (atmospheric pressure and winds). The short period variations (some hours to one day) can be attributed to longitudinal seiches, semidiurnal and diurnal atmospheric tides, and inertial oscillations. The water discharge from the St. Lawrence River contributes 29% of the monthly residual sea level a...

A three-dimensional non-linear hydrodynamical numerical model has been used to study the water movement in the shallow Gulf of Suez at the northern end of the Red Sea. The computational grid used to schematize the Gulf has a horizontal resolution of 3×3 km and levels at 5, 15, 30 and 60 m in the vertical. The simulations were carried out separately for tidal forcing and wind forcing. Further, in each case, stratified conditions were considered to represent the state of the Gulf during late summer periods. In the case of wind-induced circulations, a uniform wind speed of 5 m s−1was applied over the Gulf, blowing from NW, N and NE directions. The results suggest that the dynamics of the Gulf of Suez are governed by the interaction of wind and density forcing. Only occasionally, for instance in the vicinity of headlands and islands, tidal residuals are of similar importance. For the overall residual currents, it was found that the typical (quasi) baroclinic two-layered inverse-estuarine circulation observed in the Gulf of Suez can be produced under the combined action of M2-tide and winds blowing steadily from the north-eastern direction. North-western and northern winds produced the reverse pattern.

Tropical Cyclones which develop in the Andaman Sea and the Bay of Bengal during the inter monsoon months (April-May, October-December), move either westwards affecting the east coast of India or recurve to the north or northeast and eventually cross the coast of Bangladesh or Myanmar. Extensive damage is caused to the life and property by the storm surge as much of the coastal land around the Bay of Bengal is densely populated. The damage caused by a cyclone induced surge depends to a considerable extent on whether the surge peaks at or close to high tide. The main purpose of the present study was to develop a combined time-surge model for the off-shore waters in the Meghna estuary. It seems clear that the strong, predominantly southward current measured at Site A, south of Sandwip Island, has substantial magnifying and delaying effect on tidal elevation and current. But the areal extent of this modification of the tide is unknown at present. Further, it is impossible to say whether the fast southward current forms a narrow jet or a broad current many kilometers wide, but it is important to know which is the case before the effect can be modelled satisfactorily.

The present activities of the National Tidal Facility (NTF) consist not only of producing tidal predictions for Australia, but also include two major programs of monitoring sea levels around Australia and in the South Pacific Forum region through the use of some 27 high precision gauges. The NTF also operates the Southern Ocean Sea Level Centre, as well as providing consultancy services through a variety of numerical modelling activities, education and training in marine sciences.

Trends in monthly precipitation, temperature, water equivalent of the snowpack, and streamflow are investigated for stations in three local areas in interior British Columbia of interest for hatching of salmon on the Adams River, Fraser River near Prince George, and Skeena River near Babine Lake. In general, since the 1960s, cold season (October and January) precipitation has been decreasing, temperatures have been rising, snow water equivalents have been diminishing, and streamflows have been going down. However, the results may not necessarily be part of a global warming but may rather be an amplification of the common Pacific/North American pattern.

The output from the modified version of a hydrodynamical numerical model developped earlier by El-Sabh and Murty (1988) has been used to hindcast the movement and dispersion of oil slicks in the Arabian Gulf during part of the period of January to March 1991. While other studies on numerical simulations of this event pertain mainly to the Al-Ahmadi spill, the present study simultaneously examines the movement of oil from not only this source but also from Mina Al-bakr and clearly delineates the impact of oil from each of these sources.

The International Tsunami‐93 Symposium was sponsored jointly by the Tsunami Commission of the International Union of Geodesy and Geophysics and the International Coordination Group of the Intergovernmental Oceanographic Commission of UNESCO. It was organized by the Japan Society of Civil Engineers and was held in Wakayama, Japan, August 23–25, 1993. This review is based on the proceedings of the Conference, which were jointly edited by Professors Yoshito Tsuchiya and Nobuo Shuto. In total about 142 participants from 19 countries attended the symposium. They presented some 65 papers in 12 sessions dealing with various topics. Selected papers from the conference are briefly reviewed and highlights of the conference are noted.

A vertically integrated two‐dimensional (2‐D) and a five‐layer three‐dimensional (3‐D) numerical models were developed to compute the tides in the Gulf of Suez, Egypt. The computational grid used to schematize the Gulf has a horizontal resolution of 3 × 3 km and consists of a lattice of 23 × 100 points in the 2‐D model and five such lattices in the 3‐D model. Both 2‐D and 3‐D simulations clearly revealed the Kelvin wave nature of the tide with partial reflection. The M2 simulations also showed a strong tidal signature in the southern sector as compared to the northern part. For the 3‐D simulations, the horizontal and vertical eddy viscosity coefficients and the coefficient of bottom friction were respectively set to 3 × 106 cm2/s, 200 cm2/s, and 0.001. The tidal range decreases from the entrance of the Gulf of Suez toward the Bank of Tor where it reaches a small value and then increases again to about 1.5 m at Suez. A difference of six hours exists between the times of high water at the southern and north...

A two‐dimensional, nonlinear, vertically integrated model for the Gulf of Suez, Egypt, was used to simulate the interaction between tides and the surge heights resulting from a 15 m/s storm blowing from the northwestern direction for 24 hours. The results show that the predominant surges as well as the envelope of the tide plus surge curve are all negative throughout the whole area of the Gulf of Suez and increasing northward. It was shown that, although in principle, the shallow Gulf of Suez can support and propagate positive storm surges, they do not occur, mainly because the winds from the prevailing weather systems are conducive to generate negative surges. Since the tidal range in the Gulf of Suez is small, even the combined water level from the surge and tide remains mostly negative.

The explosion of the ammunition ship Mont Blanc in Halifax Harbor produced a strong tsunami locally. There was not an operational tide gauge at the time to document the changes in sea level, but there are several narrative reports of extreme high and low water. In this study we examine the tsunami by looking at integrating three different aspects. We have collected narrative reports to see what quantitative information might be obtained from them. We have estimated the height of the initial mound of water that would be produced from an explosion of 2.9 kilotons in the harbor narrows where the Mont Blanc grounded. Finally, we have formulated a numerical model to follow the progress of the wave through the harbor, into Bedford Basin and out toward the Atlantic Ocean. Various analytical, empirical, and numerical models on explosion‐generated waves provide an estimate for the tsunami amplitude as a function of the explosive charge and limited by the water depth. For the Halifax explosion, the tsunami...

A two‐dimensional time‐dependent nonlinear tidal model was developed for the St. Lawrence estuary, with two open boundaries. This model is a substantial improvement over two earlier models which did not include the nonlinear terms. The model is run simultaneously, to hindcast the tide on any particular day, using as boundary conditions real data for the five important constituents, namely M2, S2, N2, K1, and O1. Coamplitude and cophase diagrams were constructed and compared with known shore‐based gauge observation. This comparison revealed that the model performs quite satisfactory. Further calibration was then carried out by adjusting the bottom friction coefficient. Such a calibration is necessary before the model can be used to simulate tsunami generation and propagation in the estuary. The total water level during the occurrence of a tsunami should include not only the tsunami amplitude, but also the interaction of the tsunami with the tide.

An earthquake occurred off the west coast of Nicaragua at 18 h 16 m on September 1, 1992. Despite a relatively modest magnitude (Ms = 7.0 Mw = 7.6), the earthquake generated a significant tsunami, which strongly impacted the coast of Nicaragua and was felt at several remote stations. In an attempt to better understand the tsunami propagation and coastal impact, we conducted a field survey on November 2–7, 1992, i.e., roughly 2 months after the event. We emphasized the observation of run‐up and inundation, but also collected a limited number of sand samples and mud cores. A total of 12 sites were surveyed, with multiple stations per site. This article presents the results of the survey, including a detailed discussion of the observation methods and data processing strategies. Observed run‐ups (relative to MSL) were typically in the 4–7 m range, with a maximum run‐up of 9.1 m at San Martin, an open coast site with a steep beach slope. Inundation extents were relatively modest, typically of the orde...

Numerical models of the hydrodynamics of Howe Sound and of the transport and deposition of suspended sediment from the Squamish River entering Howe Sound are described. Two different versions of a three‐dimensional hydrodynamic model of Howe Sound have been developed. One is a fine‐grid model employing a 390‐m grid size, the other a coarse‐grid model with a 1.95‐km grid size. In the present implementation, both models have 9 layers in the vertical, and calculate the three components of the velocity field as well as the time‐varying density field. The models are forced at their open boundaries by a larger three‐dimensional model of the Strait of Georgia, by surface wind stress and by the Squamish River flow. The coarse‐grid model is computationally less demanding and is used for long‐term simulations, whereas the fine‐grid model is used for detailed simulations for shorter time periods. The sediment model derives its velocity field from the coarse grid three‐dimensional hydrodynamic model. Sedimen...

Sea level records from nine stations in eastern Canada have been analyzed in order to investigate the seasonal trends and other long‐term changes that have occurred since the beginning of this century. The four stations situated in riverine or estuarine regions are significantly affected by freshwater flow in their annual cycle of sea level changes and exhibit a definite maximum in spring and minimum in autumnwinter. Other stations situated in the eastern half of the Gulf of St. Lawrence or near the open Atlantic coast follow the general cycle of subarctic regions, with a low in spring‐summer and a high in autumn‐winter. Such seasonal variations appear to be related to the atmospheric pressure and baroclinic current variations. Secular trends in mean sea level show a mean rise of about 25.6 cm/century along the Atlantic coast of Canada. The monthly mean sea level series are subjected to Fourier spectral analysis in an attempt to identify the major long‐period cycles present in the records. The sp...

A vertically integrated tidal model of Barkley Sound has been developed as the first phase of a study of circulation and its interaction with juvenile salmon moving through Alberni Inlet and Barkley Sound to the Pacific Ocean. This model is an implementation of the three‐dimensional baroclinic model GF8 using a single layer, with a horizontal grid size of 400 m. Elevations and velocity boundary condition data for this model were obtained from an irregular grid finite element model of the west coast of Vancouver Island. The resulting barotropic tidal model was found to be stable, and produced tidal elevations in close agreement with observations. Modeled tidal currents at the location of a current meter morred in Imperial Eagle Channel agreed well with observations, to the extent that barotropic currents could be deduced in a simple manner from observations containing both barotropic and baroclinic modes. The next phase in the modeling program was the development of an upper layer baroclinic model...

In the past, sea level changes in the Indian Ocean received much less attention than those in the Atlantic and Pacific oceans. Here the sea level variation in the western part of the Indian Ocean has been considered. Rather than concentrating on the yet unproven, slow, and gradual sea level rise due to the so‐called greenhouse warming, attention is paid to the much more dramatic sea level variations that can occur within a few hours due to storm surges and tsunamis. In that part of the western Indian Ocean that is considered here, the storm surges are generated from the sea level atmospheric pressure fields and tangential surface wind stresses associated with travelling weather systems such as tropical cyclones. One can adapt the results from tsunami runup studies to storm surges since both phenomena fall into the classification of long gravity waves.

Precipitation chemistry in southwestern British Columbia has been examined to determine if the shutdown of the ASARCO smelter in Tacoma, Washington in March of 1985 had a significant effect.

Marine positioning is relevant for several aspects of tsunami research, observation, and prediction. These include accurate positioning of instruments on the ocean bottom for determining the deep‐water signature of the tsunami, seismic observational setups to measure the earthquake parameters, equipment to determine the tsunami characteristics during the propagation phase, and instruments to map the vertical uplift and subsidence that occurs during a dip‐slip earthquake. In the accurate calculation of coastal tsunami run‐up through numerical models, accurate bathymetry is needed, not only near the coast (for tsunami run‐up) but also in the deep ocean (for tsunami generation and propagation). If the bathymetry is wrong in the source region, errors will accumulate and will render the numerical calculations inaccurate. Without correct and detailed run‐up values on the various coastlines, tsunami prediction for actual events will lead to false alarms and loss of public confidence.

Canada has increased the number of tsunami warning stations on the Pacific Coast from two to three. The last gauge was installed at the north end of Vancouver Island, thereby filling a large gap previously existing and providing full coverage along the coast. The record of gauges at two of the three locations is accessible either by telephone or by means of meteor burst communication, alleviating the difficulties experienced during the tsunami threat of May 6, 1986, when telephone communications were disrupted by heavy use. The gauge at Langara Island will be relocated in a more accessible and also a more tsunami‐responsive location at Rennell Sound in the Queen Charlotte Islands. All tsunami gauges also serve as tide gauges, recording the water level every 15 min. In the event of a tsunami, the recording interval can be altered to every 60 s. Suggestions have been made that Canada attempt deep‐sea recording of tsunamis off its Pacific Coast. Although this would be of great scientific value, no s...

The changes in normal precipitation amounts from 1931–60 to 1951–80 are examined for stations in Eastern Canada. The area covered comprises the Maritime Provinces and those parts of Ontario and Quebec south of a line approximately 200 km north of Lakes Erie and Ontario and the St Lawrence River. Changes are computed for each of the four seasons and for the entire year. On the whole, precipitation has increased, especially in winter and summer. However, there is considerable variation throughout the area, with precipitation decreasing in some regions. General circulation models that simulate the effect of doubling atmospheric CO2 also show an increase in precipitation.

Some past tsunamis in various regions of Canada have been reviewed. These tsunamis have occurred from a variety of sources: under-ocean earthquakes, sub-marine landslides and human-made inadvertent large chemical explosions. Resonance amplification of the tsunami has been identified as important in the Alberni Inlet on the Vancouver Island, British Columbia, and also in the Burin Inlet in Newfoundland. The results of the various numerical models for tsunami generation, propagation onto the shelf, and into the coastal inlets that formed the scientific basis for the British Columbia tsunami warning system have been briefly discussed.