Spatial variability of long-term trends of significant wave heights in the Black Sea

2018 ◽  
Vol 79 ◽  
pp. 20-35 ◽  
Author(s):  
Burak Aydoğan ◽  
Berna Ayat
Keyword(s):  
Spatial Variability ◽  
Black Sea ◽  
The Black Sea ◽  
Significant Wave ◽  
Wave Heights ◽  
Long Term Trends ◽  
Significant Wave Heights

scholarly journals Long-Term Analysis of the Black Sea Weather Windows

2019 ◽  
Vol 7 (9) ◽  
pp. 303 ◽  
Author(s):  
Onea ◽  
Rusu
Keyword(s):  
Black Sea ◽  
The Black Sea ◽  
Time Interval ◽  
Significant Wave ◽  
Energy Projects ◽  
Wave Heights ◽  
Maritime Operations ◽  
Significant Wave Heights ◽  
The Waves

A particular aspect of the maritime operations involves available weather intervals, especially in the context of the emerging renewable energy projects. The Black Sea basin is considered for assessment in this work, by analyzing a total of 30-years (1987–2016) of high-resolution wind and wave data. Furthermore, using as reference, the operations thresholds of some installation vessels, some relevant case studies have been identified. The evaluation was made over the entire sea basin, but also for some specific sites located close to the major harbors. In general, the significant wave heights with values above 2.5 m present a maximum restriction of 6%, while for the western sector, a percentage value of 40% is associated to a significant wave height of 1 m. There are situations in which the persistence of a restriction reaches a maximum time interval of 96-h; this being the case of the sites Constanta, Sulina, Istanbul or Burgas. From a long-term perspective, it seems that there is a tendency of the waves to increase close to the Romanian, Bulgarian, and Turkish coastal environments—while an opposite trend is expected for the sites located on the eastern side.

scholarly journals Interannual Variability of the Wind-Wave Regime Parameters in the Black Sea

2020 ◽  
Vol 27 (4) ◽  
Author(s):  
B. V. Divinsky ◽  
A. A. Kubryakov ◽  
◽  
◽  
Keyword(s):  
Black Sea ◽  
Climatic Variability ◽  
The Black Sea ◽  
Storm Activity ◽  
Significant Wave ◽  
Wind Speeds ◽  
Climatic Trends ◽  
Average Wind ◽  
Wave Heights ◽  
Significant Wave Heights

Purpose. The paper is aimed at studying climatic trends in variability of the average annual and average monthly fields of significant wave heights of the mixed and wind seas, swell and the wind speeds in the Black Sea region. Methods and Results. Based on the MIKE 21 SW numerical model, the significant wave heights’ fields of the mixed and wind seas, and also swell were obtained for the period from 1979 to 2018. Long-term wind velocity changes were analyzed using the ERA-Interim reanalysis data for the same period. Linear climatic trends in the average annual and average monthly variability of the significant wave heights and the average wind speeds were evaluated by the statistical methods. Conclusions. The main feature of climatic variability of the significant wave height fields in the Black Sea is the pronounced spatial heterogeneity. In the western part of the sea, decrease in storm activity is observed. The eastern part is characterized by increase of the average significant wave heights. Statistically significant positive trends in fluctuations of the significant wave heights are observed in the coastal area from the Crimea southeast coast to the Georgia coast. Over the past 40 years, swell waves have intensified near the Turkish coast (to the east of Sinop) and near the Kerch Strait. The largest increase of the average monthly heights of mixed waves is observed in the eastern part of the sea in March and amounts 0.5–0.6 cm/year. This corresponds to increase of the average wind speeds by 0.025 m/s/year. In November, decrease of storm activity is observed in the western part of the sea that is expressed in diminution of the monthly average values of the significant wave heights by 0.8 cm/year. Decrease of the average annual wave heights by 0.08 cm/year is observed in the southwestern part of the Black Sea. On the contrary, the whole eastern part of the sea is subject to the increased storm activity accompanied by growth of the average annual wave heights in the fields of the mixed and wind seas by 0.10–0.15 cm/year. The above-mentioned features reflect climatic variability of the average wind speeds, which are characterized by wind weakening in the western part of the sea (0.010–0.015 m/s/year) and its amplification in the sea eastern part (0.015–0.020 m/s/year).

scholarly journals Long term trends in the sea surface temperature of the Black Sea

Ocean Science ◽  
2010 ◽  
Vol 6 (2) ◽  
pp. 491-501 ◽  
Author(s):  
G. I. Shapiro ◽  
D. L. Aleynik ◽  
L. D. Mee
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Black Sea ◽  
Sea Surface ◽  
The Black Sea ◽  
The North ◽  
Sst Variability ◽  
Long Term Trends ◽  
Cooling Trend

Abstract. There is growing understanding that recent deterioration of the Black Sea ecosystem was partly due to changes in the marine physical environment. This study uses high resolution 0.25° climatology to analyze sea surface temperature variability over the 20th century in two contrasting regions of the sea. Results show that the deep Black Sea was cooling during the first three quarters of the century and was warming in the last 15–20 years; on aggregate there was a statistically significant cooling trend. The SST variability over the Western shelf was more volatile and it does not show statistically significant trends. The cooling of the deep Black Sea is at variance with the general trend in the North Atlantic and may be related to the decrease of westerly winds over the Black Sea, and a greater influence of the Siberian anticyclone. The timing of the changeover from cooling to warming coincides with the regime shift in the Black Sea ecosystem.

scholarly journals Long term trends in the sea surface temperature of the Black Sea

2010 ◽  
Vol 7 (1) ◽  
pp. 91-119
Author(s):  
G. I. Shapiro ◽  
D. L. Aleynik ◽  
L. D. Mee
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Black Sea ◽  
Sea Surface ◽  
The Black Sea ◽  
The North ◽  
Sst Variability ◽  
Long Term Trends ◽  
Cooling Trend

Abstract. There is growing understanding that recent deterioration of the Black Sea ecosystem was partly due to changes in the marine physical environment. This study uses high resolution 0.25° climatology to analyze sea surface temperature variability over the 20th century in two contrasting regions of the sea. Results show that the deep Black Sea was cooling during the first three quarters of the century and was warming in the last 15–20 years; on aggregate there was a statistically significant cooling trend. The SST variability over the Western shelf was more volatile and it does not show statistically significant trends. The cooling of the deep Black Sea is at variance with the general trend in the North Atlantic and may be related to the decrease of westerly winds over the Black Sea, and a greater influence of the Siberian anticyclone. The timing of the changeover from cooling to warming coincides with the regime shift in the Black Sea ecosystem.

scholarly journals Modelling Short- and Long-Term Dependencies of Clustered High-Threshold Exceedances in Significant Wave Heights

Mathematics ◽  
2021 ◽  
Vol 9 (21) ◽  
pp. 2817
Author(s):  
Pushpa Dissanayake ◽  
Teresa Flock ◽  
Johanna Meier ◽  
Philipp Sibbertsen
Keyword(s):  
Time Series ◽  
Long Range ◽  
High Threshold ◽  
Peaks Over Threshold ◽  
Significant Wave ◽  
Wave Heights ◽  
Short And Long Term ◽  
Significant Wave Heights ◽  
Threshold Exceedances

The peaks-over-threshold (POT) method has a long tradition in modelling extremes in environmental variables. However, it has originally been introduced under the assumption of independently and identically distributed (iid) data. Since environmental data often exhibits a time series structure, this assumption is likely to be violated due to short- and long-term dependencies in practical settings, leading to clustering of high-threshold exceedances. In this paper, we first review popular approaches that either focus on modelling short- or long-range dynamics explicitly. In particular, we consider conditional POT variants and the Mittag–Leffler distribution modelling waiting times between exceedances. Further, we propose a new two-step approach capturing both short- and long-range correlations simultaneously. We suggest the autoregressive fractionally integrated moving average peaks-over-threshold (ARFIMA-POT) approach, which in a first step fits an ARFIMA model to the original series and then in a second step utilises a classical POT model for the residuals. Applying these models to an oceanographic time series of significant wave heights measured on the Sefton coast (UK), we find that neither solely modelling short- nor long-range dependencies satisfactorily explains the clustering of extremes. The ARFIMA-POT approach, however, provides a significant improvement in terms of model fit, underlining the need for models that jointly incorporate short- and long-range dependence to address extremal clustering, and their theoretical justification.

Oithona davisae: naturalization in the Black sea, inter-annual and seasonal dynamics, effect on the structure of the planktonic copepod community

2019 ◽  
Vol 59 (6) ◽  
pp. 1008-1015
Author(s):  
A. D. Gubanova ◽  
O. A. Garbazey ◽  
D. A. Altukhov ◽  
V. S. Mukhanov ◽  
E. V. Popova
Keyword(s):  
Black Sea ◽  
Coastal Waters ◽  
Native Species ◽  
Significant Decline ◽  
Acartia Tonsa ◽  
The Black Sea ◽  
Copepod Community ◽  
Oithona Davisae ◽  
Sevastopol Bay

Long-term (20032014) routine observations of zooplankton in Sevastopol Bay (the Black Sea) have allowed the naturalization of the invasive copepod Oithona davisae to be studied in the Black Sea coastal waters. Inter-annual and seasonal variability of the species and their impact on the native copepod community have been analyzed. The invasion of O. davisae and their undoubted dominance in terms of abundance were shown to alter the community structure but, at the same time, the abundances of the native species did not decrease, excepting the Black Sea earlier invader Acartia tonsa. A significant decline in A. tonsa numbers over the stages of O. davisae establishment and naturalization provided evidence of competition between the species. O. davisae have been demonstrated to gain competitive advantage over A. tonsa, that ensured their fast dispersal in the Black Sea, acclimatization in the new habitat and the successful competition over native species.

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