Meteorological tsunamis (“meteotsunamis”) are hazardous tsunami-like waves of atmospheric origin. They have typical periods from a few minutes to about 3 h and typical spatial scales from a few ...hundred meters to approximately 100–150 km. The waves have different local names in different regions of the world: “rissaga” in the Balearic Islands (Spain), “marrobbio” in Sicily (Italy), “šćiga” in the Adriatic Sea (Croatia), “milghuba” in Malta, and “abiki” in Japan. Meteotsunamis have markedly different generation mechanisms than storm surge or rogue waves, and are mainly produced by direct air pressure forcing. Several recent destructive meteotsunami events have attracted considerable attention to the phenomenon. The present paper is one of the first attempts to classify and overview the strongest events. A total of 51 selected events over the past 27 years are examined and described. Some of these events are well known (e.g. the events of 4 July 1992 Daytona Beach, Florida, 15 June 2006 Ciutadella Harbour, Spain, and 13 June 2013 East Coast of USA), while others have only been mentioned in the media and on the Internet. The list of events includes those that have occurred in the Mediterranean, the Black Sea, Japan, South Korea, Australia, the Great Lakes, South Africa, the USA, Canada, Brazil, the Netherlands and other countries and regions. All meteotsunami events are separated into four groups: “Good-weather harbour”, “Good-weather open-coast”, “Bad-weather harbour (storm seiches)” and “Bad-weather open-coast”. “Good-weather” meteotsunamis are most typical for the Mediterranean region, while “bad-weather” events mainly occur on the Atlantic coasts of the USA and Europe.
Two hazardous typhoons, Lionrock (August 2016) and Jebi (September 2018), destructively affected the coast of Japan and produced extreme sea level variations. The results of field surveys in the ...impacted regions showed that multiple deaths and extensive floods were caused by the combined effect of low-frequency sea level raise (storm surges) and intensive high-frequency (HF) tsunami-like waves (meteotsunamis). The data from ten tide gauges for the 2016 event and eight gauges for the 2018 event were used to examine the properties of the observed sea levels, to estimate the relative contribution of the two sea level components and to evaluate their statistical characteristics (maximum wave heights, amplitudes and periods of individual components, etc.). For the 2016 event, we found that the surge heights were from 12 to 35 cm and that the mean contribution of surges into the total observed sea level heights was ~ 39%; the meteotsunami amplitudes were from 22 to 92 cm, and they contributed 61% of the total height. For the 2018 event, storm surges were significantly stronger, from 46 to 170 cm, while HF amplitudes were from 38 to 130 cm; their relative inputs were 67% and 33%, respectively. Combined, they formed total flood heights of up to 120 cm (2016 event) and 288 cm (2018 event). Previously, the contribution of storm seiches (meteotsunamis) in coastal floods had been underestimated, but results of the present study demonstrate that they can play the principal role. What is even more important, they produce devastating currents: according to our estimates, current speeds were up to 3 knots (1.5 m/s) during the Lionrock event and more than 5 knots (2.6 m/s) during Jebi; these strong currents appear to be the main reason for the resulting damage of coastal infrastructure. The most important characteristic of the recorded meteotsunamis is their trough-to-crest maximum height. During the 2016 event, these heights at three stations were > 1 m: 171 cm at Erimo, 109 cm at Hachijojima and 102 cm at Ayukawa. The 2018 event was stronger; maximum meteotsunami wave heights were 257 cm at Gobo, 138 cm at Kushimoto, 137 cm at Kumano and 128 cm at Murotomisaki. The 2018 Gobo height of 257 cm is much larger than historical non-seismic seiche maxima for the Pacific coast of Japan (140–169 cm) estimated by Nakano and Unoki (1962) for the period of 1930–1956.
Typhoon Maysak (Julian in the Philippines) was a powerful tropical cyclone that strongly impacted coastal regions of the Sea of Japan on 2-4 September 2020. Destructive winds, violent storm waves, ...and intense rainfall occurred in Japan, on the Korean Peninsula, and in Far-Eastern Russia. Devastating coastal floods caused severe damage to coastal infrastructure and to ships and boats anchored in harbours and were responsible for numerous deaths. Our study indicates that the main reason for the destructive floods was the superposition of storm surge, extreme seiches (meteorological tsunamis), and surf beats. At various sites, different types of sea level oscillations prevailed depending on the atmospheric forcing, local topographic properties, and resonant shelf/coastal zone features. The principal forcing factors of these oscillations were atmospheric pressure and wind stress, but the exact generation mechanism of each specific type of oscillation was strongly site dependent. The uniqueness of the sea level response at each site is the main challenge in our understanding of the generation process and to the mitigation of the hazardous consequences of possible future events.
A series of tsunami-like waves of non-seismic origin struck several southern European countries during the period of 23 to 27 June 2014. The event caused considerable damage from Spain to Ukraine. ...Here, we show that these waves were long-period ocean oscillations known as meteorological tsunamis which are generated by intense small-scale air pressure disturbances. An unique atmospheric synoptic pattern was tracked propagating eastward over the Mediterranean and the Black seas in synchrony with onset times of observed tsunami waves. This pattern favoured generation and propagation of atmospheric gravity waves that induced pronounced tsunami-like waves through the Proudman resonance mechanism. This is the first documented case of a chain of destructive meteorological tsunamis occurring over a distance of thousands of kilometres. Our findings further demonstrate that these events represent potentially dangerous regional phenomena and should be included in tsunami warning systems.
Tsunami-like sea level oscillations recently recorded by tide gauges located along the coasts of British Columbia (Canada) and Washington State (USA) have been identified as
meteorological tsunamis
. ...Globally, such events can create hazardous conditions in coastal areas, including the possible loss of life, and need to be taken into account in any assessment of risk to nearshore infrastructure. On 1 November 2010, a significant meteotsunami occurred in the southern Strait of Georgia, British Columbia. To examine this event, we have used all available sea level and air pressure data, including 1-min records from five Canadian Hydrographic Service and five USA National Oceanic and Atmospheric Administration tide gauges, as well as high-resolution time series from two Ocean Network Canada VENUS bottom pressure recorders and from 132 air pressure sensors within the Victoria School-Based Weather Station Network of southern British Columbia. The oceanic responses to four well-defined atmospheric disturbances (labelled D1–D4) were selected for analysis. Disturbance D3, which propagated toward ~ 100° True (eastward) at a speed of ~ 20 m/s, appears to have been responsible for generating the meteotsunami observed in the southern Strait of Georgia, while disturbance D4 that moved toward ~ 55° True at a speed of 24 m/s appears to have produced the meteotsunami observed in Juan de Fuca Strait that separates Vancouver Island from Washington State. We used the physical parameters derived for the four disturbances to force numerical simulations of the events and compared the results to observations from selected tide gauge sites. The numerical experiments revealed strongly individual sea level responses at each site to changing air pressure disturbance speed, direction and intensity, such that each location has its own set of “site-specific” air pressure characteristics that produce the strongest sea level response. Differences in the local topography and coastline geometry appear to be responsible for the different responses among sites.
Tsunami-like intense sea-level oscillations, associated with atmospheric activity (meteorological tsunamis), are common in the Great Lakes and on the East Coast of the United States. They are ...generated by various types of atmospheric disturbances including hurricanes, frontal passages, tornados, trains of atmospheric gravity waves, and derechos. “Derecho” is a rapidly moving line of convectively induced intense thunder storm fronts producing widespread damaging winds and squalls. The derecho of June 29–30, 2012 devastatingly propagated from western Iowa to the Atlantic coast, passing more than 1,000 km and producing wind gusts up to 35 m/s. This derecho induced pronounced seiche oscillations in Lake Michigan, Chesapeake Bay, and along the US Atlantic coast. Sea-level records from the updated National Oceanic and Atmospheric Administration (NOAA) tide gauge network, together with the NOAA and automated surface-observing system air pressure and wind records, enabled us to examine physical properties and temporal/spatial variations of the generated waves. Our findings indicate that the generation mechanisms of extreme seiches in the basins under study are significantly different: energetic winds play the main role in seiche formation in Chesapeake Bay; atmospheric pressure disturbances are most important for the Atlantic coast; and the combined effect of pressure oscillations and wind is responsible for pronounced events in the Great Lakes. The “generation coefficient,” which is the ratio of the maximum observed sea-level height and the height of air pressure disturbance, was used to map the sea-level response and to identify “hot spots” for this particular event, i.e., harbors and bays with amplified seiche oscillations. The Froude number,
Fr
=
U/c
, where
U
is the speed of the atmospheric disturbance and
c
is the long-wave speed, is the key parameter influencing the water response to specific atmospheric disturbances; the maximum response was found for those regions and disturbance parameters for which
Fr
~1.0.
Abstract
From 12 to 16 October 2016, a series of three major low pressure systems, including the tail end of Typhoon Songda, crossed the coasts of British Columbia (BC) and the state of Washington ...(WA). Songda was generated on 2 October and, after traveling northward along the coast of Japan, turned eastward toward North America. Once there, it merged with two extratropical cyclones moving along the coast of Vancouver Island. The combined lows generated pronounced storm surges, seiches, and infragravity waves off southern BC and northern WA. Here, we examine the event in terms of sea levels measured by tide gauges and offshore bottom pressure recorders, together with reanalysis data, and high-resolution air pressure and wind measurements from 182 meteorological stations. Surge heights during the event typically exceeded 80 cm, with maximum heights of over 100 cm observed at La Push (WA) and New Westminster (BC). At Tofino, on the west coast of Vancouver Island, there was a sharp 40-cm increase in sea level on 14 October in response to a marked air pressure disturbance; slightly lower sea level peaks were also observed at other outer coast locations. In all cases, the sea level response was 1.5–2.5 times as great as that expected from the inverted barometer effect, consistent with local topographic amplification. The sea level oscillations at Tofino had the form of a forced solitary wave (“meteorological tsunami,” or meteotsunami), whereas those on the southwestern shelf off Vancouver Island are well described by classical standing-wave theory. A numerical model closely reproduces the observed meteotsunami peaks and standing-wave oscillations.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The major (
M
w
8.2) intraplate normal-fault earthquake of 8 September 2017 in the Gulf of Tehuantepec (Chiapas, Mexico) generated a strong tsunami that severely impacted the nearby coasts of Mexico ...and Central America. Tsunami waves in the near-field area were measured by seventeen high-resolution coastal tide gauges and by three open-ocean DART stations anchored offshore from the affected region. Data from these sites, together with those from four distant DARTs, were used for comprehensive analyses of the 2017 event. De-tided sea level time series were examined to determine the statistical and spectral characteristics of the 2017 tsunami waves along the Mexican and Central American coastline. The characteristics of the recorded waves from this near-field event were compared with those from two great far-field events: the 2010 Chile and the 2011 Tohoku tsunamis. Maximum trough-to-crest wave heights for the 2017 tsunami were recorded at Puerto Chiapas (351 cm), Salina Cruz (209 cm), Acapulco (160 cm), Huatulco (137 cm) and Acajutla, El Salvador (118 cm). While maximum 2010 and 2011 tsunami waves were observed at specific “hot spots” (sites with a high
Q-
factor and pronounced resonant properties, such as Manzanillo and Acapulco), the “strengths” of the recorded 2017 tsunami waves were mostly determined by distance from the source. Contrary to the maximum wave heights, the general spectral properties of the tsunami signals for all three events were highly similar at a given coastal site and mainly resemble the spectral structure of background oscillations at the same site. This similarity indicates that the frequency properties of the tsunami waveforms for a steady-state tsunami signal are mainly determined by local topographic features rather than by the source parameters. Estimates of the “colour” of an event (i.e., the open-ocean tsunami frequency content) show that the 2017 Chiapas tsunami was mostly “reddish” (long-period), with 68% (DART 43413) to 87% (DART 43412) of the total tsunami energy related to waves with periods > 35 min. In contrast, the 2010 and 2011 tsunamis were “reddish-blue”, with 48–57% associated with long-period waves (> 35 min) and 52–43% with short-period waves (2–35 min). The dominant periods of the tsunami waves were mostly linked to the shape, length, and width of the source region: the larger the source and the shallower its depth, the longer the periods of the generated tsunami waves. The complicated structure of the source explains the saturated and wide frequency-band character of the tsunami spectra. Our analysis also reveals an anisotropic nature to the 2017 tsunami waves; waves that propagated northeastward along the mainland coast of North America and southeastward along the Central American coast were significantly different from those that propagated southwestward, normal to the source orientation. This aspect of the wave field appears to be related to two distinct types of waves; “trapped (edge) waves” retained on the shelf (which plays the role of a “wave guide”), and “leaky waves” that radiate into the open ocean.
The Port of Klaipeda, situated in Klaipeda Strait that connects the southeastern Baltic Sea with the Curonian Lagoon, is prone to dangerous sea-level oscillations originating from various sources and ...possessing a wide range of physical characteristics. The present study investigates extreme seiches (meteotsunamis) in this basin spanning a five-year period (2017–2021), with a primary focus on determining their origin and specific factors triggering devastating events. On average, strong seiches result in over 60 days of hazardous situations, requiring the partial or complete halt of the port operations. We examined in detail two specific events: 23–24 December 2017 and 20 June 2020. The first event was forecasted, while the second event was not predicted according to the existing forecasting procedure. We found that for both events amplified seiche oscillations and associated intense currents were observed at two dominant periods: 26 and 14 min, which appear to be related to the primary Eigen modes of the port. Our findings emphasize the frequent presence of hazardous seiches in the Port of Klaipeda, highlighting the necessity to update and improve the forecasting methodology. A reliable forecasting system for the Port of Klaipeda should be based on the resonant properties of the port and relationships between weather patterns and induced long waves affecting the port.
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