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1.
Residual Exchange Flows in Subtropical Estuaries   总被引：1，自引：0，他引：1  
Observations of residual exchange flows at the entrance to four subtropical estuaries, two of them semiarid, indicate that these flows are mainly tidally driven, as they compare favorably with theoretical patterns of tidal residual flows. In every estuary examined, the tidal behavior was that of a standing or near-standing wave, i.e., tidal elevation and tidal currents were nearly in quadrature. The pattern of exchange flow that persisted at every estuary exhibited inflow in the channel and outflow over the shoals. Curiously, but also fortuitously, this pattern coincides with the exchange pattern driven by density gradients in other estuaries. The tidal stresses and the residual elevation slopes should be the dominant mechanisms that drive such tidal residual pattern because the Stokes transport mechanism is negligible for standing or near-standing waves. Time series measurements from the semiarid estuaries showed fortnightly modulation of the residual flow by tidal forcing in such a way that the strongest net exchange flows developed with the largest tidal distortions, i.e., during spring tides. This modulation is opposite to the modulation that typically results in temperate estuaries, where the strongest net exchange flows tend to develop during neap tides. The fortnightly modulation on tidal residual currents could be inferred from previous theoretical results because residual currents arise from tidal distortions but is made explicit in this study. The findings advanced herein should allow the drawing of generalities about exchange flow patterns in subtropical estuaries where residual flows are mainly driven by tides.  相似文献   

2.
This research investigates the dynamics of the axial tidal flow and residual circulation at the lower Guadiana Estuary, south Portugal, a narrow mesotidal estuary with low freshwater inputs. Current data were collected near the deepest part of the channel for 21 months and across the channel during two (spring and neap) tidal cycles. Results indicate that at the deep channel, depth-averaged currents are stronger and longer during the ebb at spring and during the flood at neap, resulting in opposite water transport directions at a fortnightly time scale. The net water transport across the entire channel is up-estuary at spring and down-estuary at neap, i.e., opposite to the one at the deep channel. At spring tide, when the estuary is considered to be well mixed, the observed pattern of circulation (outflow in the deep channel, inflow over the shoals) results from the combination of the Stokes transport and compensating return flow, which varies laterally with the bathymetry. At neap tide (in particular for those of lowest amplitude each month), inflows at the deep channel are consistently associated with the development of gravitational circulation. Comparisons with previous studies suggest that the baroclinic pressure gradient (rather than internal tidal asymmetries) is the main driver of the residual water transport. Our observations also indicate that the flushing out of the water accumulated up-estuary (at spring) may also produce strong unidirectional barotropic outflow across the entire channel around neap tide.  相似文献   

3.
The rise of total water levels at the coast is caused primarily by three factors that encompass storm surges, tides and wind waves. The accuracy of total water elevation (TWE) forecast depends not only on the cyclonic track and its intensity, but also on the spatial distribution of winds which include its speed and direction. In the present study, the cyclonic winds are validated using buoy winds for the recent cyclones formed in the Bay of Bengal since 2010 using Jelesnianski wind scheme. It is found that the cyclonic winds computed from the scheme show an underestimate in the magnitude and also a mismatch in its direction. Hence, the wind scheme is suitably modified based on the buoy observations available at different locations using a power law which reduces the exponential decay of winds by about 30%. Moreover, the cyclonic wind direction is also corrected by suitably modifying its inflow angle. The significance of modified exponential factor and inflow angle in the computation cyclonic winds is highlighted using statistical analysis. A hydrodynamic finite element-based Advanced Circulation 2D depth integrated (ADCIRC-2DDI) model is used here to compute TWE as a response to combined effect of cyclonic winds and astronomical tides. As contribution of wave setup plays an important role near the coast, a coupled ADCIRC + SWAN is used to perceive the contribution of wind waves on the TWE. The experiments are performed to validate computed surge residuals with available tide gauge data. On comparison of observed surge residuals with the simulations using modified winds from the uncoupled and coupled models, it is found that the simulated surge residuals are better compared, especially with the inclusion of wave effect through the coupled model.  相似文献   

4.
2011年12月至2012年1月长江口的现场观测资料表明,大潮和大潮后中潮期间,北港的淡水向北支口门和下段扩展,减小了北支下段的盐度,而小潮及其后的中潮期间无此现象。为了确证淡水的来源,采用验证良好的三维数值模式再现了上述观测现象,并通过数值试验和淡水通量机制分解方法分析其动力成因。数值试验结果表明,大潮及其后的中潮期间,北港主槽流经北港北汊及其周围浅滩的水体是北支淡水的主要来源,拉格朗日余流输送是其向北支扩展的主要动力机制。北港北汊的增深增加了进入北支的淡水通量,减弱了北支的盐水入侵。偏北风风速的增加抑制了北港淡水向北支的扩展,增加了北支的盐水入侵。  相似文献   

5.
The turbulent flow structure, suspended sediment dynamics and deposits of experimental sustained turbidity currents exiting a channel across a break in slope into a wide tank are documented. The data shed light on the flow evolution and deposit geometry of analogous natural channel‐fed submarine fans. Flows generated in a 0·3 m wide, sloping (0°, 6°, 9° or 20°) channel crossed an angular slope break and spread onto a horizontal tank floor. Flow development comprised: (i) channelized phase (unsteady channel flow developing into steady channel flow); (ii) initial lateral expansion phase (unsteady‐spreading wall jet phase); (iii) constant lateral expansion phase (steady‐spreading wall jet phase); and (iv) rapid waning phase. Phases (i) and (iv) are similar to laterally constrained turbidity currents, but phases (ii) and (iii) are considerably different from such two‐dimensional currents. Steeper channel slopes produced greater flow velocities and turbulence intensities, but these effects diminished markedly with distance from the channel mouth. Flow velocity vectors in the tank had similar patterns for all channel slopes, with a central core of faster velocity and narrow vector dispersion and slower flow with larger dispersion at the jet margins. Suspended sediment concentrations were higher within flow heads and dense basal layers in flow bodies. Time‐averaged acoustic backscatter data showed vertical concentration gradients, confirmed by siphon samples. The deposits comprised a thick central ridge, of similar order width to the channel mouth, with abrupt margins and a surrounding, very thin, fan‐like sheet. The ridge was coarser grained and better sorted than the original sediment, with grain‐size fining downstream, particularly over the fan‐like sheet. The formation of a central ridge suggests that, in the tank, vertical turbulent momentum exchange is more significant for sediment dynamics than spanwise momentum exchange due to lateral expansion. The streamwise elongate geometry of the ridge contrasts with conventional fan‐like geometry found with surge‐type turbidity flows, a result that has widespread stratigraphic and economic implications.  相似文献   

6.
Field data of tidal current speeds collected January 9–31, 1990, in Sebastian Inlet, which connects the Atlantic Ocean and the Indian River Lagoon on the east coast of central Florida, show that the average Eulerian and Stokes residual currents are both lagoonward. This pattern can be used to explain the long-term trend of accumulations of marine sediments on the flood tidal delta adjacent to the lagoon end of the inlet. Numerical model results indicate that the long-term Stokes residual current is mainly determined by the tidal characteristics of the lagoon and ocean, and subsequently, are less variable. The long-term lagoonward Eulerian current, on the other hand, is interrupted by episodic weather events such as frontal storms. Storms can cause the abrupt superelevation of instantaneous water-levels on the lagoon side of the inlet. The short-lived pulses of freshwater inflow into the lagoon associated with storms could be discharged through the inlet instantaneously. Both the instantaneous superelevation of lagoon water levels and freshwater outflow can cause temporary reversal of Eulerian residual current in the inlet. Therefore, the general residual flow pattern in Sebastian Inlet is not only determined by the tidal characteristics of the Atlantic Ocean and Indian River Lagoon but also by the wind and precipitation associated with episodic storms, and by the long-term mean sea-level difference between the lagoon and the ocean.  相似文献   

7.
Systematic morphological changes of the coastline of the outer Yangtze River mouth in response to storms versus calm weather were documented by daily surveys of tidal marshes and flats between April 1999 and May 2001 and by boat surveys offshore during this and earlier periods. The largest single event during 1999 to 2001 was Typhoon Paibaian, which eroded the unvegetated tidal flat and lower marsh and led to accretion on the middle-to-upper marsh and in the subtidal channel. The greatest erosion of 21 cm occurred at the border between the marsh and the unvegetated flat due to the landward retreat of the marsh edge during the storm. Strong waves on the flats increased suspended sediment concentration by 10–20 times. On the upper marsh, where the frequency of submergence by astronomical tides is only 3%, Typhoon Paibian led to 4 cm of accretion, accounting for 57% of the net accretion observed over the 2-yr study. Typhoon Paibian led to 4 cm of accretion, accounting for 57% of the net accretion observed over the 2-yr study. Typhoon Paibian and other large storms in the 1990s caused over 50 cm of accretion along the deep axis of the river mouth outlet channel. During calm weather, when hydrodynamic energy was dominated by tides, deposition was centered on the unvegetated flats and lower, marsh with little deposition on the high marsh and erosion in the subtidal channel. Depositional recovery of the tidal flat from typhoon-induced erosion took only several days, whereas recovery of the subtidal channel by erosion took several weeks. A conceptual model for the morphological responses of tidal marshes, flats, and subtidal channels to storms and calm weather is proposed such that sediment continually moves from regions of highest near-bed energy towards areas of lower energy.  相似文献   

8.
A radioisotope tracer (82Br) was injected into a sand aquifer adjacent to a tidal creek at Hat Head, New South Wales, Australia. The injection was timed to coincide with the falling limb of a spring tide in August 2001 and was repeated in July 2002 during a period of neap tides. The tracer movement was detected using gamma logging and fixed gamma detectors in a bore 0.9 m from an injection bore and in a line approximately perpendicular to the creek. Movement of the tracer was detected by comparing measured gamma activity with calibrated activities determined under laboratory conditions. Net movement of the tracer indicated approximately 0.001 m/day laterally towards the creek and 0.07 m/day vertically upward during spring tide conditions. This pattern is reversed during neap tide conditions with little net vertical movement but horizontal movement of 0.15 m/day. The measurements indicated an oscillatory motion coinciding with the tide but lagging the tide by approximately 4.5–6.5 h. The vertical flow during spring tides indicates that vertical movement of the saline interface occurs and results in mixing of different water types beneath the banks of the creek.  相似文献   

9.
Spatial gradients in the flow over an estuarine channel   总被引：3，自引：0，他引：3  
Acoustic Doppler current profiles were measured for a twelve-hour period on February 21, 1997 across Thimble Shoal channel, lower Chesapeake Bay, for the purpose of determining bathymetrically-induced spatial gradients in the flow and their implications for the lateral momentum balance in estuaries. A least-squares fit to semidiurnal and quarter-diurnal harmonics was used to separate the tidal and subtidal contributions to the observed flow. The period of observation was characterized by onshore winds and subtidal inflow everywhere along the transect sampled but strongest in the channel. Spatial gradients in both the tidal and subtidal horizontal flows showed that the greatest lateral shears and convergences were found where the bathymetric changes were sharpest, i.e., on the shoulders of the channel. The ratio of the quarter-diurnal to the semidiurnal tidal amplitudes was greatest over the channel shoulders, for both the along- and across-estuary flow components, and indicated the importance of non-linear effects there. The nonlinear term caused by across-estuary divergence was larger than the Coriolis term over the channel shoulders. The nonlinear contribution was comparable to the Coriolis acceleration in the subtidal and tidal lateral momentum balances. For the tidal balance, the local accelerations were also as important as the Coriolis accelerations. Equivalent results in the momentum balances were obtained with another data set of October 1993. Contrary to the customary assumption, the across-estuary momentum balance in this area was ageostrophic.  相似文献   

10.
Influences of tides, freshwater discharge, and winds on water properties in the St. Jones River estuary (USA), a Delaware National Estuarine Research Reserve, were investigated using multiyear records of sea level, salinity, and turbidity, supplemented by a current profiler time series in 2007. Results demonstrate that instantaneous properties fluctuate with semidiurnal tides and resonant overtides, whereas tidal mean variations are forced by seasonal freshwater inflow and offshore winds. Mean sea level and salinity are highest in summer and vary with seasonal water temperature and rainfall, whereas sea level variability and turbidity are highest in winter on account of storm effects. Salinity and discharge modeling suggest that much (43–65%) of the freshwater resident in the estuary is derived from non-point sources below the head of tide. This diffuse freshwater inflow produces a seaward surface slope and weak mean current, which temporarily reverses under the influence of storm–wind setup within Delaware Bay.  相似文献   

11.
A statistical procedure for estimating the risk of strong winds from hurricanes, known as the Hurricane Risk Calculator, is demonstrated and applied to several major cities in Louisiana. The procedure provides an estimate of wind risk over different length periods and can be applied to any location experiencing this hazard. Results show that an area 100 km around the city of New Orleans can expect to see hurricane winds blowing at 49 ms?1 (44.3–53.7) [90 % confidence interval (CI)] or stronger, on average, once every 20 years. In comparison, for the same time period, the capital city of Baton Rouge and the surrounding area can expect to see hurricane winds of 43 ms?1 (38.2–47.8) (90 % CI) or stronger. Hurricane track direction is also analyzed at the cities of interest. For Morgan City, Lafayette, Lake Charles, and Alexandria, tropical cyclones with winds at least 18 ms?1 travel from the southeast to northwest. New Orleans and Baton Rouge tropical cyclones have a greater tendency to turn toward the east while within 100 km of the city, historically giving them a southwesterly approach. Tropical cyclones within 350 km off the south-central Louisiana coast occur most often in September, and the most extreme of these events are becoming stronger through time as shown with quantile regression.  相似文献   

12.
The residual (time-average) salinity and circulation in a numerical ocean model of the Tampa Bay estuary are shown to experience significant temporal variation under realistic forcing conditions. A version of the Estuarine Coastal Ocean Model developed for Tampa Bay with 70 by 100 horizontal grid points and 11 sigma levels is examined for the years 2001–2003. Model output variables are averaged over the entire time of the simulation to generate long-term residual fields. The residual axial current is found to be dominated by the buoyancy-driven baroclinic circulation with an outflow (southwestward) at the surface and to the sides of the shipping channel, and an inflow (northeastward) usually occurring subsurface within or above the shipping channel. Averages over 30 d are used to examine variations in the residual fields. During the simulation the average surface salinity near the head of Tampa Bay varies with the freshwater inflow, from 12‰ to 33%. At the bay mouth salinity varies from 30%. to 36%.. A localized measure of the baroclinic circulation in the shipping channel indicates the residual circulation can vary strongly, attaining a magnitude triple the long-term mean value. The baroclinic circulation can be disrupted, going to near zero or even reversing, when the buoyancy-driven flow is weak and the surface winds are to the northeast. Three time periods, representing different environmental conditions, are chosen to examine these results in detail. A scaling argument indicates the relative strength of buoyancy versus wind as ΔρgH2(LC Dω2)−1, where δρ is head-to-mouth density difference across the bay,g is gravitational acceleration,H is depth,L is bay length,C D is the surface wind drag coefficient, andw is wind speed. Tampa Bay is usually in the buoyancy dominated regime. The importance of winds in the weak-buoyancy case is demonstrated in an additional simulation without wind stress.  相似文献   

13.
Salt marsh elevation and geomorphic stability depends on mineral sedimentation. Many Mediterranean-climate salt marshes along southern California, USA coast import sediment during El Niño storm events, but sediment fluxes and mechanisms during dry weather are potentially important for marsh stability. We calculated tidal creek sediment fluxes within a highly modified, sediment-starved, 1.5-km2 salt marsh (Seal Beach) and a less modified 1-km2 marsh (Mugu) with fluvial sediment supply. We measured salt marsh plain suspended sediment concentration and vertical accretion using single stage samplers and marker horizons. At Seal Beach, a 2014 storm yielded 39 and 28 g/s mean sediment fluxes and imported 12,000 and 8800 kg in a western and eastern channel. Western channel storm imports offset 8700 kg exported during 2 months of dry weather, while eastern channel storm imports augmented 9200 kg imported during dry weather. During the storm at Mugu, suspended sediment concentrations on the marsh plain increased by a factor of four; accretion was 1–2 mm near creek levees. An exceptionally high tide sequence yielded 4.4 g/s mean sediment flux, importing 1700 kg: 20 % of Mugu’s dry weather fluxes. Overall, low sediment fluxes were observed, suggesting that these salt marshes are geomorphically stable during dry weather conditions. Results suggest storms and high lunar tides may play large roles, importing sediment and maintaining dry weather sediment flux balances for southern California salt marshes. However, under future climate change and sea level rise scenarios, results suggest that balanced sediment fluxes lead to marsh elevational instability based on estimated mineral sediment deficits.  相似文献   

14.
Mohanty  Sachiko  Rao  A. D.  Pradhan  Himansu 《Natural Hazards》2017,87(2):1109-1124

The influence of seasonal and cyclonic winds is studied on the characteristics of internal waves (IWs) over the western Bay of Bengal (BoB) by using MITgcm model. As the BoB experiences reversal of seasonal winds and also tropical cyclones during pre-monsoon and post-monsoon months, its effect is seen through the computation of spectral estimates of the IWs. It is seen that the peak estimate is associated with the semidiurnal frequency at all the depths and is found higher in May compared to November. This is attributed to the presence of shallow mixed layer depth and deep thermocline due to the upwelling favorable winds. The computation of isopycnal displacement infers that the internal tides are present from 40 to 120 m depth in case of upwelling favorable winds of May, whereas, the presence of internal tides is restricted between 90 and 120 m for the downwelling favorable winds of November. During May, the available potential energy is also seen in a narrow coastal stretch, whilst it is absent in November. During the Hudhud cyclone period of October 7–14, 2014, it is noticed from the spectral estimates that the IWs of tidal frequency are replaced by inertial frequency with a periodicity of about 2 days as a consequence of strong cyclonic winds. The progressive vector diagram shows the mean current is initially westward up to October 17, 2014 and then northeastward with well-defined clockwise circulation. The maximum radius of inertial oscillation of 15 km is observed. After the cyclone ceases, the estimate associated with inertial frequency slowly diminishes and enhances the estimates related to internal tides. The simulations also suggest that the internal tides are absent for about 6 weeks as a response of the cyclonic winds.

  相似文献   

15.
Umbrella structure is a newly recognized sedimentary structure associated with large platy clasts in resedimented boulder-bearing pebble conglomerate with a sandy matrix. It consists of a sand rim that lacks pebbles on parts or the entire underside of platy boulders, whereas on the upper side, pebbles are in direct contact with the boulders. The depositing processes were high- to hyper-concentrated sediment gravity flows in a submarine channel or canyon on the Cambrian continental slope of North America bordering the Iapetus Ocean. The structure occurs predominantly where clasts dip moderately in the down-current direction. Based on the association of the structure with slightly forward dipping slabs, it is proposed that these down-current dipping slabs may have been in the process of counter-clockwise rotation that was aborted and may have generated a pressure shadow on the underside enabling the inrush of fluid and the infiltration of sand into the anomalous low-pressure zone. The structure has implications for particle support mechanisms in high- to hyper-concentrated sedimentary gravity flows, in that it redirects attention to the much debated mechanism of dispersive pressure and alternatives. It provides an observable sediment structure that supports dispersive pressure which so far depended on experimental evidence and theoretical arguments alone. Vrolijk and Southard’s (1997) concept of a ‘laminar sheared layer’ is here for the first time interpreted as having an upward-moving ‘free-surface’ layer effect during deposition from hyper-concentrated flows. Channel-wall stoping involves unlithified turbiditic spillover sand in the levee sediment of the canyon wall that was washed out by the upper diluted parts of the high-concentration flows coming down the channel and leaving a niche in the wall that was filled with coarser channel-axis facies by the same flow (or later flows) when its aggradation reached the level of the niche. The contact between turbidite and pebble conglomerate occurs now more than 2 m laterally into the exposed channel wall. Channel-wall stoping tracks turbulence development in hyper-concentrated gravity flows.  相似文献   

16.
Time series of current velocity profiles and thermistor chains were obtained throughout a cross-bay transect for ~90 days for the purpose of comparing observed wind-driven stratified flows to theory. This study concentrates on the synoptic scale wind and its influence on the bay’s circulation. The maximum water column stratification was 3–4 °C/m throughout the deployment and influenced wind-driven flows. Low-pass filtered flows showed more complicated structures than those expected from theory: a depth-dependent recirculating structure with the along-bay flow over one half of the transect moving in opposite direction to the other half. Analysis of complex empirical orthogonal functions indicated that the first six modes explained 80 % of the flow variability. Therefore, there was no predominantly energetic mode of variability. All modes exhibited a rich spatial structure with vertical and lateral variations. For all modes there was vertically sheared bidirectional flow, as expected from theory, with the largest eigenvector (mode value) asymmetrically influenced by Earth’s rotation and advection of momentum.  相似文献   

17.
The paper presents comprehensive statistical analyses of winds and water levels in Mobile Bay, Alabama, based on long-term meteorological and tidal observations at several locations. A procedure has been developed to select the most probable parent distribution function from a list of candidate distributions. The theoretical functions that fit the data best enable us to predict the extreme values of winds and water levels at different return periods. We have demonstrated the importance of dividing the winds into hurricane and nonhurricane seasons and separating astronomical tides from weather-driven water level changes. The statistical analysis suggests that the wind speed averaged over 8 min at Dauphin Island, Alabama, at the 100-year return period would be 48.9 m/s, which is equivalent to a sustained 1-min wind of 205 km/h, a very strong category 3 hurricane on the Saffir-Simpson scale. The probability distribution models predict that the 100-year maximum water level would be 3.23 m above the mean lower low water (MLLW) level at the bay entrance and 3.41 m above the MLLW level near the head of the bay, respectively. Extremely low water levels important to navigation are also found. Application of the predicted extreme winds and surges is illustrated through the development of a storm wave atlas in the estuary. It is expected that the methodology and results presented in this paper will benefit the management and preservation of the ecosystems and habitats in Mobile Bay.  相似文献   

18.
One of the steepest depositional coasts of western James Bay is found along the west shores of Akimiski Strait, north of the mouth of the Ekwan River. This shore receives considerable amounts of sediment during the spring break-up of the rivers. The sediments are stored on the steep narrow tidal flats and marshes, and in thinner (up to 80 cm) drapes on till-cored shoals that parallel and protect the coast. The low areas between the shoals and the mainland are swept and reworked by relatively powerful (2 m s?1) reversing currents due to flooding and ebbing of tides into the strait.A series of distinct environments and sedimentary facies develop on this western coast and its antecedent longshore shoal. The outer part of the shoal is characterized by tidal bedding, Macoma balthica burrows and considerable ice scour. The inner part of the shoal has winnowed sand, the greatest abundance of Macoma, and well-developed flaser bedding. The longshore tidal channel separating the shoal from the mainland has coarse sand lags in the shallower parts and silty sand in deeper protected areas. The steep tidal flats develop laminated silty sands locally saturated and slumping toward the channel. The high saturation of the sediments inhibits colonization of the flats by Macoma. The narrow marshes have characteristic vegetation zonation, with Puccinellia phryganodes colonizing the lower marsh. The sedimentary sequence of the marsh displays irregular, bioturbated laminated sequences of silt, silty sand and organic matter.  相似文献   

19.
The Scheldt is a tidal river that originates in France and flows through Belgium and the Netherlands. The tides create significant flood risks in both the Flemish region in Belgium and the Netherlands. Due to sea level rise and economic development, flood risks will increase during this century. This is the main reason for the Flemish government to update its flood risk management plan. For this purpose, the Flemish government requested a cost-benefit analysis of flood protection measures, considering long-term developments. Measures evaluated include a storm surge barrier, dyke heightening and additional floodplains with or without the development of wetlands. Some of these measures affect the flood risk in both countries. As policies concerning the limitation of flood risk differ significantly between the Netherlands and Flanders, distinctive methodologies were used to estimate the impacts of measures on flood risk. A risk-based approach was applied for Flanders by calculating the impacts of flood damage at different levels of recurrence, for the base year (2000) and in case of a sea level rise of 60 cm by 2100. Policy within the Netherlands stipulates a required minimal protection level along the Scheldt against storms with a recurrence period of 1 in 4,000 years. It was estimated how flood protection measures would delay further dyke heightening, which is foreseen as protection levels are presently decreasing due to rising sea levels. Impacts of measures (safety benefits) consist of delays in further dyke heightening. The results illustrate the importance of sea level rise. Flood risks increased fivefolds when a sea level rise of 60 cm was applied. Although more drastic measures such as a storm surge barrier near Antwerp offer more protection for very extreme storms, a combination of dykes and floodplains can offer higher benefits at lower costs.  相似文献   

20.
Analysis of 20-year time series of water levels in the northeastern Gulf of Mexico has revealed that meteotsunamis are ubiquitous in this region. On average, 1–3 meteotsunamis with wave heights >0.5 m occur each year in this area. The probability of meteotsunami occurrence is highest during March–April and June–August. Meteotsunamis in the northeastern Gulf of Mexico can be triggered by winter and summer extra-tropical storms and by tropical cyclones. In northwestern Florida most of the events are triggered by winter storms, while in west and southwest Florida they appear both in winter and summer. Atmospheric pressure and wind anomalies (periods <6 h) associated with the passage of squalls originated the majority of the observed meteotsunami events. The most intense meteotsunamigenic periods took place during El Niño periods (1997–1998, 2009–2010 and 2015–2016). Meteotsunamis were also active in 2005, a year characterized by exceptionally intense tropical cyclone activity. Meteotsunami incidence varied yearly and at periods between 2 and 5 years. Results from cross-wavelet analysis suggested that El Niño and meteotsunami activity are correlated at annual and longer-period bands.  相似文献   

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