Passage Of Storm Research Articles

Coastal storm deposition: Salt-marsh response to a severe extratropical storm, March 1993, west-central Florida

On March 12–13, 1993, the passage of a severe extratropical storm, popularly referred to as the “Storm of the Century,” resulted in the deposition of storm-suspended sediments along Florida' west-central coastline. In Waccasassa Bay, surge waters near 3 m in height inundated the coast and transported resuspended, nearshore sediments onto the open-marine marshes rimming the embayment. The thickness of the resulting storm deposit reached 12 cm on the levees and up to 2 cm on the marsh surface, and visible sedimentation occurred several hundred metres from the creek banks into the marsh interior. The tan to gray storm layer was composed of mixed clays, silt to very fine sand–sized quartz, and marine biogenic sediments, all similar to those of the underlying marsh sediments. Despite the evidence for severe storm conditions, this event was characterized further by the absence of shoreline erosion along the marsh coast. This condition contrasts with sandy coasts, where strong storms often result in shoreline erosion. As compared to sandy shorelines, the stability of this marsh-fronted coast is enhanced by the cohesive nature of the fine-grained marsh muds, baffling by the marsh-grass canopy, and sediment binding by plant-root matrices. Locally, the Waccasassa Bay coastal system has developed under sediment-poor, sand-starved, and low-energy conditions, and large-scale storm events may be an important component in sediment-transport processes and marsh-surface accumulation. The response of the Waccasassa Bay system to this event offers a different view of storm-related shoreline effects and, in particular, the role that storms may play in long-term shoreline stability.

Storm waves in the Canadian Atlantic: A numerical simulation

The Grand Banks and the Scotian Shelf regions of the Canadian Atlantic often experience strong winds and high waves associated with the passage of intense storms during the winter months of December to March. These storm waves are identified as a major hazard to shipping, offshore exploration and other marine activities in eastern Canada.

Interactions between Topographic Airflow and Cloud/Precipitation Development during the Passage of a Winter Storm in Arizona

Abstract A case study showing comparisons between observations and numerical simulations of the passage of a winter storm over complex terrain is presented. The interactions between the mesoscale and cloud environments and the microphysical and dynamical processes are addressed using both observations and numerical simulations. A three-dimensional, time-dependent nested grid model was used to conduct numerical simulations of the three-dimensional airflow and cloud evolution over the Mogollon Rim and adjacent terrain in Arizona. The modeling results indicated that the flow patterns and cloud liquid water (CLW) were closely linked to the topography. To a large extent, gravity waves excited by the flow over the mountains determine the distribution of clouds and precipitation. The waves extend through deep layers of the atmosphere with substantial updrafts and downdrafts, at times exceeding 5 m s−1. The simulated vertical velocities and horizontal wavelengths of about 20 km were in good agreement with the air...

Ambient noise characteristics of the northwestern Barents Sea

In support of the 1988–1989 CEAREX drift experiment three ANMET ambient noise buoys were inserted on ice floes in a triangular pattern approximately 120 km on a side about 200 km north of Svalbard in mid-September 1988. The buoys drifted southward passing to the east of Svalbard providing hourly measurements of the noise field from 5–4000 Hz for 2–4 months. Extensive environmental data were available with which to examine the effect of wind stress and ice motion on the noise field. The median spectra from these three buoys were quite similar with differences of about 3 dB being observed, the larger differences being at the higher frequencies where local noise effects dominate. The spectra were comparable to those found in the Eurasian Basin in winter. A 12-h periodicity was noted in both the noise and ice speed data, the result of forcing by tidal or inertial oscillations. A 52-h periodicity was noted at one buoy which lasted through the winter and was subjected to recurring synoptic scale storms. For frequencies below 100 Hz the temporal coherency was about 15 h. At low frequencies wind stress was the most important noise correlate, followed closely by ice speed. The noise field responded rapidly to the passage of storms generated by the Icelandic Low which migrated over the northern Barents Sea with the arrival of the noise peak being associated with the time of passage of the storm front past each buoy.

Lime-mud layers in high-energy tidal channels: A record of hurricane deposition

Research Article| July 01, 1993 Lime-mud layers in high-energy tidal channels: A record of hurricane deposition Eugene A. Shinn; Eugene A. Shinn 1U.S. Geological Survey Coastal Center, 600 4th Street South, St. Petersburg, Florida 33701 Florida 33701 Search for other works by this author on: GSW Google Scholar Randolph P. Steinen; Randolph P. Steinen 2Department of Geology, University of Connecticut, Storrs, Connecticut 06268 Search for other works by this author on: GSW Google Scholar Robert F. Dill; Robert F. Dill 3GeoMarine Inc., San Diego, California 92106 Search for other works by this author on: GSW Google Scholar Richard Major Richard Major 4Bureau of Economic Geology, University of Texas, Austin, Texas 78713 Search for other works by this author on: GSW Google Scholar Geology (1993) 21 (7): 603–606. https://doi.org/10.1130/0091-7613(1993)021<0603:LMLIHE>2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Eugene A. Shinn, Randolph P. Steinen, Robert F. Dill, Richard Major; Lime-mud layers in high-energy tidal channels: A record of hurricane deposition. Geology 1993;; 21 (7): 603–606. doi: https://doi.org/10.1130/0091-7613(1993)021<0603:LMLIHE>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract During or immediately following the transit of Hurricane Andrew (August 23-24, 1992) across the northern part of the Great Bahama Bank, thin laminated beds of carbonate mud were deposited in high-energy subtidal channels (4 m depth) through the ooid shoals of south Cat Cay and Joulters Cays. During our reconnaissance seven weeks later, we observed lime-mud beds exposed in the troughs of submarine oolite dunes and ripples. The mud layers were underlain and locally covered by ooid sand. The mud beds were lenticular and up to 5 cm thick. Their bases cast the underlying rippled surface. The layers were composed of soft silt- and sand-sized pellets and peloids and in some areas contained freshly preserved Thalassia blades and other organic debris along planes of lamination. The beds had a gelatinous consistency and locally had been penetrated by burrowers and plants. Layers of lime mud had also settled on bioturbated, plant-stabilized flats and in lagoonal settings but were quickly reworked and made unrecognizable by the burrowing of organisms. Thicker, more cohesive (and therefore older) mud beds and angular mud fragments associated with ooids from Joulters Cays have similar characteristics but lack fresh plant fragments. We infer that these older beds were similarly deposited and thus record the passage of previous hurricanes or tropical storms. Storm layers are preserved within channel sediments because migrating ooids prevent attack by the burrowing activity off organisms. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Upper ocean response to Hurricane Gilbert

The evolving upper ocean response excited by the passage of hurricane Gilbert (September 14–19, 1988) was investigated using current and temperature observations acquired from the deployment of 79 airborne expendable current profilers (AXCPs) and 51 airborne expendable bathythermographs from the National Oceanic and Atmospheric Administration WP‐3D aircraft in the western Gulf of Mexico. The sea surface temperatures (SSTs), mixed layer depths, and bulk Richardson numbers were objectively analyzed to examine the spatial variability of the upper ocean response to Gilbert. Net decreases of the SSTs of 3°–4°C were observed by the profilers as well as by the airborne infrared thermometer (AIRT) along the flight tracks and advanced very high resolution radiometer (AVHRR) imagery. The AXCPs indicated a marked cooling from 29°C to about 25.5°C on September 17, 1988, which was about 1.2 inertial periods (IP) following storm passage. This pool of cooler water (3.5°) was located further downstream in the hurricane wake by September 19 (2.7 IP following the storm) as a result of the near‐inertial currents in the mixed layer. While there was a bias of about 0.6°C and 1.7°C between the in situ and AVHRR‐derived SSTs, respectively, both the AVHRR images and the objectively analyzed fields indicated a rightward bias in the upper ocean cooling that extended from the storm track to about 4Rmax (where Rmax, the radius of maximum winds, is equal to 50 km). The larger SST offset of 1.7°C was due to the difference between the time of the AVHRR image and the time of the aircraft experiment on September 19. The SSTs derived from the AVHRR images and the AIRT also indicated large gradients between the cold wake and the warm eddy in the central Gulf of Mexico. The mixed layer deepened by about 30–35 m on the right side of the track during the storm and 1.2 IP later, with little evidence of continued deepening afterward. The mixed layer current vectors demonstrate that a strong, near‐inertially rotating current was excited by the passage of Gilbert, with maxima of about 1–1.4 m s−1. The currents, observed during and subsequent to (1.2 IP) the storm, diverged from the storm track, whereas the mixed layer current vectors 2.7 IP after storm passage converged toward the track, with relative maxima of 0.8–1 m s−1. This alternating pattern of convergence and divergence of the mixed layer current was associated with the upwelling and downwelling cycles of the baroclinic response. Considerable current shear existed between the mixed layer and the thermocline currents in the cool wake between the storm track and the 4Rmax. Estimates of the bulk Richardson numbers ranged between 0.2 and 1.0 during Gilbert and at 1.2 IP, which suggests that enhanced current shears were responsible for some of the mixed layer deepening.

Modeling the seasonal variability of a coupled Arctic ice‐ocean system

Results from modeling studies of the ice‐ocean system in the Arctic Basin and in the Norwegian‐Greenland‐Barents seas are presented. We used a three‐dimensional coupled ice‐ocean model developed at Princeton University. The ocean model applies the primitive equations and a second moment turbulence closure for turbulent mixing. The snow‐ice model uses a three‐level thermodynamic scheme which resembles Semtner's (1976a) model. Our conclusions based on the seasonal simulations are as follows. (1) Using monthly climatological surface heat flux and wind stress, the seasonal variability of the ice cover is quite realistic in that the thickest ice is located north of Greenland and the average ice thickness is about 3 m. The largest deviation between the simulated and observed ice cover is in the Greenland Sea where oceanic conditions determine the ice edge. Basically, the monthly climatological forcing does not result in strong enough mixing to bring sufficient heat from the deep ocean to keep the central Greenland Sea gyre ice free. The results improve for both the ice cover and ocean by invoking daily wind forcing for which we first chose year 1987. In the ocean model, the large mixing events associated with storm passages are resolved, and as a result, the overall oceanic structure in the Greenland Sea appears to be more realistic. However, no deep convection takes place in the model during 1987 which is likely the result of diminished storm activity in the northern part of the Greenland Sea. The ice thickness field appears to be very anomalous 1987, so an experiment with 1986 daily wind forcing was also done, which resulted in an ice thickness field similar to some reported from other ice models. (2) Both monthly and daily surface forcing result in a similar behavior of the Atlantic waters in the Arctic Basin. The Atlantic waters circulate at about the observed level, between 400 and 600 m. The survival of the Atlantic waters in the basin depends strongly on the heat loss through the ice cover, and it appears that too much heat is lost on the Eurasian side through the ice because the simulated Atlantic waters are too cool by about 0.2–0.5°C. (3) For the monthly climatology case, a large amount of cold and salty water enters the Eurasia Basin from the Kara and Laptev seas area and finds its way toward the Canada Basin. This water mass appears to result from ice formation in the Kara and Laptev seas. When applying the daily forcing, this deep salinity maximum disappears due to increased mixing on the shelves. Nevertheless, this suggests a mechanism within the Arctic Ocean as to why the deep Canada Basin is much saltier than the Eurasia Basin.

Observing the advection of sea ice in the Weddell Sea using buoy and satellite passive microwave data

This study examines the progress and behavior of an area of sea ice as it drifts from the southwestern Weddell Sea by using data from four buoys tracked by Nimbus 6 and concurrent ice concentrations retrieved from Nimbus 7 scanning multichannel microwave radiometer data. It covers the entire growth season of 1980. The overall drift characteristics, and their relationship to ice edge displacement, are examined within the framework of four zones. Three phases are identified in the large‐scale behavior of the Weddell sea ice cover, namely, a rapid equatorward and eastward advance, a quasi‐equilibrium phase, and a period of rapid recession. A broad division is made between the sectors to the east and west of 35°–40°W in terms of the nature of ice edge advance. Transient departures from the mean northward advection are linked to the passage of cyclones; certain such events may be significant in terms of the formation and maintenance of the region of highly consolidated perennial ice observed in the western Weddell Sea. Mean daily drift rates (up to 0.9 m s−1) from within the central‐western Weddell pack are high in 1980, particularly early in the growth season and when compared with rates to the west of 50°W. Outbreaks of cold continental air alternate with incursions of relatively warm air from the north; warm conditions are recorded as far as 1200 km in from the ice edge in winter. Closed loops in the buoy trajectories, which are clockwise to the south of 63°S, reverse to become anticlockwise to the north. Mid‐ocean islands impede the eastward progress of the ice. A coherence is noted in the response of the buoys to the passage of storms, even though the buoys separated by a distance of over 100 km.

On the response of the ocean upper layer to synoptic variability of the atmosphere

The response of the ocean upper layer to synoptic atmosphere variability is examined using a nonlocal integral model of the subtropical gyre. Our main goal is the analysis of the nonlinear, nonlocal oceanic response to two typical atmospheric disturbances, which were postulated to be of the same intensity but of opposite sign. Thus, we study the nonlinear effects in the response of a horizontally inhomogeneous ocean to synoptic disturbances in the subtropical gyre. It was shown that synoptic atmospheric variability generates an oceanic response which may have climatic consequences. Synoptic upper mixed layer (UML) thermal anomalies reach about 1–2°C over an area of more than 1000 km × 1000 km, and influence directly the large-scale atmosphere-ocean interaction. This influence is comparatively short term. On the other hand, a series of storms may influence the thermal regime of the whole baroclinic layer. This leads to long-term consequences. Therefore, the simulation of such fluctuations in large-scale models of atmosphere-ocean interaction is necessary. Oceanic horizontal inhomogeneity is most important in the integral heat, momentum and kinetic energy turbulence (KET) balances of the UML after the passage of storms. The effect of oceanic inhomogeneity is at a maximum in the storm-induced frontal zone and is shown particularly in the advective h variations ( h is the UML thickness), which are of the same order as the local h variations, as well as in generation of the gradient currents/gradient advection, which are of the same order as the drift currents/drift advection (but slightly less). Obviously, drift advection is the main effect of the UML horizontal inhomogeneity. During the action of strong winds, the heat, momentum and KET balances of the mid-ocean UML are approximately one-dimensional for most of the storm track. During this period, the synoptic vertical motions at the base of the UML must also be considered. Vertical thermal storm-induced advection in the main thermocline exceeds the vertical diffusion by one and a half orders, and may strongly influence the thermal regime of the main thermocline if there are several storms of the same sign and trajectory.

The influence of hydrodynamical processes on sediment transport in the northern Gulf of St Lawrence

Sediment transport on continental shelves occurs in response to a wide spectrum of hydrodynamical factors each acting at particular temporal scales. We document in this study one such factor, namely the quasi-periodic passage of large-scale meteorological storms over a region at synoptic frequencies (3–20 days). Our case study focuses on the geological evolution of the Natashquan river delta on the northern Gulf of St Lawrence shelf in relation to nearshore currents. Airgun seismic measurements show that the main deltaic lobe has migrated towards the west in a series of transient events. Time-series analysis of current measurements in the region reveals the presence of energetic current fluctuations occurring at synoptic frequencies; predominantly oriented alongshore and towards the west. These fluctuations are coherent with the large-scale winds, and the highest coherence is found around 15 days. Their amplitudes usually exceed 0.4 m s −1, and are thus capable of transporting the sediments found in the region. Tidal currents are less energetic (0.15-0.2 m s −1), are mainly semi-diurnal in nature and their amplitudes are modulated at the Mm periodicity (27.55 days). It is suspected that the Natashquan marine delta progressed towards the west mainly as a result of the transport of sediments by wind-driven current transients that occur during the progression of intense extra-tropical cyclones along the eastern boundary of the Gulf of St Lawrence.

Identification of Ancient Storm Events in Buried Gulf Coast Sediments

ABSTRACT Within the past 100 years, 25 hurricanes have struck the coast of the Gulf of Mexico in the area from the mouth of the Mississippi River to Apalachicola, Florida. During the passage of the storms, marginal coastal lowlands were often flooded, passes from coastal estuaries to the sea were heavily eroded, and the size and position of offshore barrier islands suffered significant modification. Not generally observed, however, were changes that took place in the submarine environment. These changes, from a geological standpoint, were equally impressive. Investigations have now confirmed that the passage of Hurricane Elena near Apalachicola Bay, Florida, in 1985, caused severe scouring of the bottom of the bay and also the resuspension and removal of over 80 million tons of sediment from the bay in a period of some 8 to 10 hours. Mobile Bay, similarly, was impacted by Hurricane Frederic, in 1979. The passage of this storm caused an overall deepening of the bay of approximately 1.5 feet and the removal of nearly 290 million tons of sediment in a period of 7 hours. This is especially striking when it is realized that this amount of sediment is nearly equivalent to that delivered by the Mississippi River to the Gulf of Mexico during one entire year! Obviously, such events also must have taken place in the geological past. While no unequivocal means probably exists to identify positively storm events in ancient sediments, detailed examination of sediment cores from Apalachicola Bay, Florida, strongly suggests that passage of major storms does leave a discernible imprint. Abrupt changes in particle median diameters, sorting coefficients, and percentages of sand-sized sediment, when viewed simultaneously, may offer such a possibility. When these parameters are determined and plotted for closely spaced samples from cores, and the cores are laid side-by-side, the simultaneous occurrence of abrupt changes in median diameter, sorting, and sand percent is strongly suspicious of a storm event. While such changes also might be explained by other causes, the likelihood of these is significantly lower than changes caused by major hurricanes, given the frequency of occurrence of storms in the Gulf's historical past.

The genesis and character of benthic turbid events, Northern Hatteras Abyssal plain

Benthic turbid events, with particle concentrations of up to 1.5 mg l −1, occupy about 20% of a two-year record of near-bottom light attenuation made above the Northern Hatteras Abyssal Plain. Theyare most often associated with deep-sea mesocle eddies, although rare events occur during periods when southward contour flow predominates. In a temporal sense, the presence of deep-sea mesoscale eddies corresponds strongly to periods when cold-core Gulf Stream rings propagate through surface waters of the study area. Additionaly, over half of the benthic turbid events observed are initiated within a day of the passage of atmospheric storms with propagation speeds in excess of 800 km day −1.

Observations on thermospheric and mesospheric density disturbances caused by typhoons and convective storms

Atmospheric parameter observations have been conducted during the passage of typhoons and tropical storms, from the troposphere to the middle atmosphere, and thence to the thermosphere, using the VHF radar and HF Doppler sounder at an observation site in Taiwan. The density perturbations caused by the propagation of gravity waves due to the typhoons and tropical storms were calculated on the basis of these observations. The short-term middle atmospheric and thermospheric density changes are significant factors in spacecraft launches. The successful remote measurement of three-dimensional winds, gravity waves, and density perturbations is demonstrated for this subtropical site.

Fine‐scale measurements of the vertical ambient noise field

The fine‐scale structure of the directional ambient noise field is investigated utilizing a large‐aperture (900‐m) vertical array. Frequency and directional spectral estimates are calculated during the passage of a local storm, providing a detailed study of the ambient noise field temporal and spatial characteristics at low frequencies (15–130 Hz) as wind speed increases from 2 to 12 m/s over a 21‐h period. Spectral levels of horizontal beams reflect the variability of discrete distant sources. Spectral levels of beams directed toward the surface and the bottom display a threshold‐type behavior, suggesting the abrupt onset of a source mechanism such as breaking waves.

Synergism of Riverine and Winter Storm-Related Sediment Transport Processes in Louisiana's Coastal Wetlands: ABSTRACT

ABSTRACT The roles of various mechanisms that supply sediments from major sources, including rivers and nearshore shelf, to coastal Louisiana are not well understood or quantified, temporally or spatially. Recent studies reveal that an important association between riverine sediment input and the cyclic passage of winter storms results in a periodic supply of suspended sediments to coastal marshlands. The fact that these two mechanisms coincide in winter and early spring maximizes the availability of particulate matter for counteracting coastal land loss by enhancing substrate accretion and plant productivity. Identification of these optimum periods of suspended sediment activity, when overbank sedimentation, riverine concentrations, flood processes, and cold front passages are synergistic, can maximize the performance of wetland restoration efforts, because mineral matter and nutrients are critical for marsh vitality. When mitigation of coastal land loss is planned, it would be advantageous for weekend restoration to consider this timing when both sediment availability and constructive processes of sediment transport are optimal.

Vertical directionality of low‐frequency wind‐induced noise

The fine‐scale structure of the directional ambient noise field is revealed using a large aperture (900 m) vertical array. Frequency and spatial spectral estimates are calculated during the passage of a local storm, providing a detailed study of ambient noise levels at low frequencies (15–130 Hz) as wind speed increases from 2 to 12 m/s over a 21‐h period. Spectral levels of beams directed horizontally show the time and spatial variability of distant sources. Spectral levels of beams directed toward the surface reflect local noise sources and display a threshold type behavior with level changes up to 5 dB, suggesting the abrupt onset of a source mechanism such as breaking waves. Subsequent thresholds may indicate a change in source mechanism such as the conversion from spilling breakers to plunging breakers. [Work supported by ONT.]

Hurricane‐generated currents on the outer continental shelf: 1. Model formulation and verification

A numerical model is developed to simulate currents generated by hurricanes on the outer continental shelf and slope. Emphasis is on the mixed‐layer response within a few hours of storm passage; however, some attention is given to the lower layer and shelf wave responses. The model is based on a layered, explicit, finite difference formulation using the nonlinear primitive equations including conservation of heat. The problem of topography intersecting the model layer is resolved by introducing artificial steps of the order of 100 m where the layer intersects the slope. Model comparisons are presented for three Gulf of Mexico hurricanes using a 0.2° grid. For two of the storms, the model reproduces better than 80% of the observed velocity variance with correlation coefficients of greater than 0.8 for the mixed layer. Discrepancies in the comparisons are traced to unresolved local topography and nonstorm forcing such as warm‐core rings. Further model simulations reveal that (1) substantial shelf waves were generated with phase speeds of 4 to 10 m s−1, (2) the response is primarily baroclinic even in water as shallow as 200 m, (3) an entrainment law which scales with the velocity difference between the mixed layer and upper thermocline yields markedly better comparisons than one which scales with the wind stress, and (4) deviations from a straight‐line storm path can significantly alter the response.

Effect of the open sea boundary conditions on storm surge simulations

The effect of two types of open sea boundary conditions (viz. the zero surge condition and the radiation condition) on surge histories in ocean shelf regions with constant depth and linearly varying depth subjected to uniform atmospheric forcing is examined. Results show that the frequently observed high surges along the east coast of India can only be explained by the two-dimensional surge simulation model with the zero surge condition along the open sea boundary. This model is also observed to be capable of predicting the resurgence phenomenon, i.e. the oscillation of shelf waters after the passage of storms.

Results from the Genesis of Atlantic Lows Experiment physical oceanographic studies: Introduction

The Genesis of Atlantic Lows Experiment (GALE) was conducted during early 1986 to investigate the rapidly developing, extratropical winter cyclones that travel across eastern North America and out over the northwestern Atlantic Ocean. Until only recently, these storms have been difficult to predict accurately [Sanders, 1986a, b], and they are well known for the devastating weather they sometimes bring to the eastern seaboard [Bosart, 1981; Kocin and Uccellini, 1984]. Such storms frequently produce “crippling” ice, heavy snow, and gale force winds, and they may batter the east coast from the Carolinas northward, often causing property damage and loss of life. The strong winds that accompany such a storm, as well as the cold, dry, continental air that often flows out over the Atlantic during the cold air outbreak stage of the storm's passage, are responsible for some of the most vigorous air‐sea exchanges of momentum, heat, and moisture in this part of the world [Budyko, 1974; Bunker and Worthington, 1976].

Eine Untersuchung der durch tropische Zyklone verursachten Zirkulation im nordwestlichen Schelfgebiet Australiens anhand eines dreidimensionalen Modells

A three-dimensional numerical model of circulation on the continental shelf has been developed and applied to study the response of the waters of the North-West Shelf (NWS) of Australia to tropical cyclones. During the passage of a tropical cyclone storm across the shelf the oceanic response is characterised by several phenomena. In the deep water sea-level responds primarily to the atmospheric pressure, while the currents are driven by the wind. For cyclones which make landfall, a coastal surge develops in response to the onshore winds, while, a strong coastal longshore current is generated by the combined action of longshore winds and a longshore oceanic pressure gradient. After the passage of the storm there is a relaxation phase, during which sea-levels, and currents adjust geostrophically, causing the generation of topographic gyres which appear to be the beginnings of freely propagating continental shelf waves. Under the direct influence of a storm, the vertical current structure varies considerably over the period between the storm onset and its departure. Strong currents flowing in the direction of the wind are confined to a surface layer of depth 0 (2vR/U c )1/2 wherev is the coefficient of eddy viscosity,R the storm radius andU c its propagation speed. The model results are compared with observations taken during the period of several tropical cyclones. Some features of the observed response are reasonably accurately predicted, and the study highlights the sensitivity of the model results to the detailed wind-field specification.