Paralic parasequences associated with Eocene sea-level oscillations in an active margin setting: Trihueco Formation of the Arauco Basin, Chile

Storm surges and wind waves are ones of the most important hydrological characteristics, which determine dynamics of the Sea of Azov. Extreme storm surges in Taganrog Bay and flooding in the Don Delta can be formed under the effect of strong western winds. In this work the sea level oscillations and wind waves in the Taganrog Bay were simulated by means of the coupled SWAN+ADCIRC numerical model, taking into account the flooding and drying mechanisms. The calculations were carried out on an unstructured mesh with high resolution. The wind and atmospheric pressure fields for the extreme storm from 20 to 28 of September, 2014 obtained from WRF regional atmospheric model were used as forcing. The analysis of simulation results showed the following. The western and northern parts of the Don Delta were the most flood-prone during the storm. The size of the flooded area of the Don Delta exceeded 50%. Interaction of storm surge and wind wave accelerated the flooding process, increased the size of the flooded area and led to the intensification of wind waves in the upper of Taganrog Bay due to the general rise of the sea level.

Download Full-text

Estimating contribution of high-frequency sea-level oscillations to the extreme sea levels in the Adriatic Sea

10.5194/egusphere-egu21-4602 ◽

2021 ◽

Author(s):

Krešimir Ruić ◽

Jadranka Šepić ◽

Maja Karlović ◽

Iva Međugorac

Keyword(s):

Time Series ◽

Sea Level ◽

High Frequency ◽

Adriatic Sea ◽

Tide Gauge ◽

Data Series ◽

Sea Levels ◽

Short Period ◽

Extreme Sea Levels ◽

Sea Level Oscillations

Extreme sea levels are known to hit the Adriatic Sea and to occasionally cause floods that produce severe material damage. Whereas the contribution of longer-period (T > 2 h) sea-level oscillations to the phenomena has been well researched, the contribution of the shorter period (T <&#160;2 h) oscillations is yet to be determined. With this aim, data of 1-min sampling resolution were collected for 20 tide gauges, 10 located at the Italian (north and west) and 10 at the Croatian (east) Adriatic coast. Analyses were done on time series of 3 to 15 years length, with the latest data coming from 2020, and with longer data series available for the Croatian coast. Sea level data were thoroughly checked, and spurious data were removed.&#160;For each station, extreme sea levels were defined as events during which sea level surpasses its 99.9 percentile value. The contribution of short-period oscillations to extremes was then estimated from corresponding high-frequency (T < 2 h) series. Additionally, for four Croatian tide gauge stations (Rovinj, Bakar, Split, and Dubrovnik), for period of 1956-2004, extreme sea levels were also determined from the hourly sea level time series, with the contribution of short-period oscillations visually estimated from the original tide gauge charts.&#160;&#160;Spatial and temporal distribution of contribution of short-period sea-level oscillations to the extreme sea level in the Adriatic were estimated. It was shown that short-period sea-level oscillation can significantly contribute to the overall extremes and should be considered when estimating flooding levels.&#160;

Download Full-text

Analysis of the eastern Adriatic sea-level extremes

10.5194/egusphere-egu21-5676 ◽

2021 ◽

Author(s):

Marija Pervan ◽

Jadranka Šepić

Keyword(s):

Sea Level ◽

Adriatic Sea ◽

Hot Spot ◽

Storm Surges ◽

Low Pressure ◽

Long Period ◽

Short Period ◽

Sea Level Oscillations ◽

Low Pass ◽

Level Height

The Adriatic Sea is known to be under a high flooding risk due to both storm surges and meteorological tsunamis, with the latter defined as short-period sea-level oscillations alike to tsunamis but generated by atmospheric processes. In June 2017, a tide-gauge station with a 1-min sampling resolution has been installed at Stari Grad (middle Adriatic Sea), the well-known meteotsunami hot-spot, which is, also, often hit by storm surges.&#160;Three years of corresponding sea-level measurements were analyzed, and 10 strongest episodes of each of the following extreme types were extracted from the residual series: (1) positive long-period (T > 210 min) extremes; (2) negative long-period (T > 210 min) extremes; (3) short-period (T < 210) extremes. Long-period extremes were defined as situations during which sea level surpasses (is lower than) 99.7 (i.e. 2) percentile of sea level height, and short-period extremes as situations during which variance of short-period sea-level oscillations is higher than 99.4 percentile of total variance[J1]&#160; of short-period series. A strong seasonal signal was detected for all extremes, with most of the positive long-period extremes appearing during November to February, and most of the negative long-period extremes during January to February. As for the short-period extremes, these appear evenly throughout the year, but strongest events seem to appear during May to July.All events were associated to characteristic atmospheric situations, using both local measurements of the atmospheric variables, and ERA5 Reanalysis dataset. It was shown that positive low-pass extremes commonly appear during presence of low pressure over the Adriatic associated with strong SE winds (&#8220;sirocco&#8221;), and negative low-pass extremes are associated to the high atmospheric pressure over the area associated with either strong NE winds (&#8220;bora&#8221;), or no winds at all. On the other hand, high-pass sea level extremes are noticed during two distinct types of atmospheric situations corresponding to both &#8220;bad&#8221; (low pressure, strong SE wind) and &#8220;nice&#8221; (high pressure, no wind) weather.It is particularly interesting that short-period extremes, of which strongest are meteotsunamis, are occasionally coincident with positive long-period extremes contributing with up to 50 percent to total sea level height &#8211; thus implying existence of a double danger phenomena (meteotsunami + storm surge).&#160;

Download Full-text

Water circulation around Britomart Reef, Great Barrier Reef, during July 1979

Marine and Freshwater Research ◽

10.1071/mf9800415 ◽

1980 ◽

Vol 31 (4) ◽

pp. 415 ◽

Cited By ~ 13

Author(s):

E Wolanski ◽

M Jones

Keyword(s):

Great Barrier Reef ◽

Sea Level ◽

Central Region ◽

Reef Flat ◽

Water Circulation ◽

Barrier Reef ◽

Trade Winds ◽

Sea Breezes ◽

Coral Sea ◽

Sea Level Oscillations

Weather and currents at eight sites were measured and drogue trajectories obtained in July 1979 at Britomart Reef, a middle reef located at 18�16'S.,146� 38'E. in the central region of the Great Barrier Reef province. The longest current records (3 weeks) were obtained at two sites in passes between the Coral Sea and the Great Barrier Reef Lagoon where westerly currents modulated by tides were observed. Analysis of residuals also showed the importance of wind-driven secondary circulation. Non-tidal sea-level oscillations were very small. Shorter current records (1-10 days) at six sites in the lagoon and on the reef flat showed a predominant northerly flow, also modulated by tides and wind. A residual anticlockwise water circulation existed in the lagoon where flushing was controlled more by winds than by tides. The rise in sea level over the reef flat as a result of waves breaking was negligible. Temperature differences between air and water accounted for the cooling of the water column during the expedition. Constant south-east trade winds were experienced at the reef, while on land the wind was weaker. more variable, and often dominated by land-sea breezes.

Download Full-text