Person: AKPINAR, ADEM
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AKPINAR
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ADEM
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Publication Trend detection by innovative polygon trend analysis for winds and waves(Frontiers Media Sa, 2022-08-10) Akcay, Fatma; Bingölbali, Bilal; BİNGÖLBALİ, BİLAL; Akpınar, Adem; AKPINAR, ADEM; Kankal, Murat; KANKAL, MURAT; İnegöl Meslek Yüksekokulu; İnşaat Mühendisliği Bölümü; 0000-0003-4496-5974; 0000-0002-9042-6851; 0000-0003-0897-4742; AAZ-6851-2020; AAC-6763-2019It is known that densely populated coastal areas may be adversely affected as a result of the climate change effects. In this respect, for coastal protection, utilization, and management it is critical to understand the changes in wind speed (WS) and significant wave height (SWH) in coastal areas. Innovative approaches, which are one of the trend analysis methods used as an effective way to examine these changes, have started to be used very frequently in many fields in recent years, although not in coastal and marine engineering. The Innovative Polygon Trend Analysis (IPTA) method provides to observe the one-year behavior of the time series by representing the changes between consecutive months as well as determining the trends in each individual month. It is not also affected by constraints such as data length, distribution type or serial correlation. Therefore, the main objective of this study is to investigate whether using innovative trend methods compared to the traditional methods makes a difference in trends of the climatological variables. For this goal, trends of mean and maximum WS and SWH series for each month at 33 coastal locations in Black Sea coasts were evaluated. Wind and wave parameters WS and SWH were obtained from 42-year long-term wave simulations using Simulating Waves Nearshore (SWAN) model forced by the Climate Forecast System Reanalysis (CFSR). Monthly mean and maximum WS and SWH were calculated at all locations and then trend analyses using both traditional and innovative methods were performed. Low occurrence of trends were detected for mean SWH, maximum SWH, mean WS, and maximum WS according to the Mann-Kendall test in the studied months. The IPTA method detected more trends, such as the decreasing trend of the mean SWH at most locations in May, July and November December. The lowest (highest) values were seen in summer (winter), according to a one-year cycle on the IPTA template for all variables. According to both methods, most of the months showed a decreasing trend for the mean WS at some locations in the inner continental shelf of the southwestern and southeastern Black Sea. The IPTA method can capture most of the trends detected by the Mann-Kendall method, and more missed by the latter method.Publication Spatial calibration of wavewatch iii model against satellite observations using different input and dissipation parameterizations in the black sea(Pergamon-elsevier Science Ltd, 2022-06-01) Akpınar, Adem; AKPINAR, ADEM; Soran, Mehmet Burak; Amarouche, Khalid; AMAROUCHE, KHALID; Mühendislik Fakültesi; İnşaat Mühendisliği Bölümü; 0000-0001-7983-4611; 0000-0002-9042-6851; AFR-7886-2022; AAC-6763-2019The quality of the third generation wave model WAVEWATCH III, referred WW3, using the different source term packages is investigated in the context of wave growth and dissipation in a semi-closed sea, Black Sea. Accuracy in wave height hindcast is tested for five different source term parameterizations ST1, ST2, ST3, ST4, and ST6 in WW3 against the 2020-year multi-mission satellite observations over the entire sea. The aims are to determine the most appropriate formulation and optimum tuneable coefficients for wind waves modelling in the Black Sea. For this purpose, significant wave heights (Hm0) are produced using five different source term packages implemented in the WW3 model. A sensitivity test was applied to define the tuneable parameters that contributes to the accuracy of the models, and subsequently the coefficient values of each parameters was turned to calibrate the WW3 models. The tuneable parameter allowing to obtain the most accurate result in each package are defined for each source term package. Comparing between model results and satellite observations, we found that the default WW3 model with all source terms as well as the calibrated ST2 model underestimate Hm0 in the entire domain and mainly in the eastern Black Sea region and are not suitable physical source term for the Black Sea. In the Black sea, the calibrated ST1, ST3 and ST4 forced with ERA5 wind are recommended for long term wave climate simulation, and the calibrated ST6 is recommended for extreme wave simulation.Publication Increasing trends in spectral peak energy and period in a semi-closed sea(Pergamon-elsevier Science Ltd, 2023-02-13) Acar, Emine; Akpınar, Adem; AKPINAR, ADEM; Kankal, Murat; KANKAL, MURAT; Amarouche, Khalid; AMAROUCHE, KHALID; Mühendislik Fakültesi; İnşaat Mühendisliği Bölümü; 0000-0002-9042-6851; 0000-0003-0897-4742; 0000-0001-7983-4611; JTU-9268-2023; AAC-6763-2019; AAZ-6851-2020; AFR-7886-2022This study aims to investigate long-term trends in the Black Sea's spectral wave peak energy and periods. Improved Visualization of the Innovative Trend Analysis and the Mann-Kendal methods was applied to the maximum and mean spectral peak energies and peak periods between 1979 and 2020. Long-term spectral data are obtained from the ERA5 reanalysis and two spectral wave models, SWAN and WWIII. The innovative trend analysis method has the particularity to examine trends in higher and lower value categories. Studies of long-term changes in spectral wave characteristics are rare, and trends in spectral peak parameters are evaluated in this study for the first time in the Black Sea. It was detected that both spectral peak energies and peak periods tend to increase predominantly over most of the time scales. Furthermore, while the change rates for peak en-ergies do not exceed 40% annually and seasonally, change rates exceeding 100% are observed on a monthly basis. Besides, the change rates of the peak periods vary in the +/- 5% band and usually do not exceed 15%. Moreover, despite a few differences, trend analysis results obtained using SWAN and WWIII models were close to the global ERA5 results. The results may provide insight into the design and durable development of coastal and marine structures as well as the evaluation of wave climate change based on spectral wave data.Publication Editorial: Advances in sea state modeling and climate change impacts(Frontiers Media Sa, 2023-03-03) Besio, Giovanni; Kamranzad, Bahareh; Akpınar, Adem; AKPINAR, ADEM; Mühendislik Fakültesi; İnşaat Mühendisliği Bölümü; AAC-6763-2019Publication Wave power trends over the mediterranean sea based on innovative methods and 60-year ERA5 reanalysis(Mdpi, 2023-05-22) Acar, Emine; Akpınar, Adem; Kankal, Murat; Amarouche, Khalid; Acar, Emine; AKPINAR, ADEM; KANKAL, MURAT; AMAROUCHE, KHALID; Mühendislik Fakültesi; İnşaat Mühendisliği Bölümü; 0000-0002-9042-6851; 0000-0003-0897-4742; 0000-0001-7983-4611; AAZ-6851-2020; AAC-6763-2019; ABG-2101-2020; JTU-9268-2023; AFR-7886-2022The present study aims to evaluate long-term wave power (P-wave) trends over the Mediterranean Sea using innovative and classical trend analysis techniques, considering the annual and seasonal means. For this purpose, the data were selected for the ERA5 reanalysis with 0.5 degrees x 0.5 degrees spatial resolution and 1 h temporal resolution during 60 years between 1962 and 2021. Spatial assessment of the annual and seasonal trends was first performed using the innovative trend analysis (ITA) and Mann-Kendall (MK) test. To obtain more detailed information, innovative polygon trend analysis (IPTA), improved visualization of innovative trend analysis (IV-ITA), and star graph methods were applied to annual, seasonal, and monthly mean Pwave at 12 stations selected. The results allow us to identify an increasing trend above the 10% change rate with the innovative method and above the 95% confidence level with the Mann-Kendall test in mean wave power in the Levantine basin and the Libyan Sea at all timescales. The use of various innovative methods offered similar results in certain respects and complemented each other.Publication Comparative performance analysis of different wind fields in the southern and north-western coastal areas of the black sea(Natl Centre Marine Research, 2019-01-01) Çakmak, Recep Emre; Akpınar, Adem; Van Vledder, Gerbrant Ph; ÇAKMAK, RECEP EMRE; AKPINAR, ADEM; Mühendislik Fakültesi; İnşaat Mühendisliği Bölümü; 0000-0002-5422-0119; 0000-0001-6314-9118; JAO-0761-2023; ABE-8817-2020; AAC-6763-2019; AAG-8624-2021This study determines the qualities of atmospheric wind field data in comparison with wind measurements at five locations along the Black Sea coast. For this purpose, four different wind fields were obtained from three different weather centers (NCEP, NASA, and ECMWF). Three of these are reanalyzed winds (Climate Forecast System Reanalysis CFSR, Modern-Era Retrospective-analysis for Research and Applications MERRA. ECMWF reanalyses ERA-Interim), and one is an operational dataset (ECMWF operational). Their performances were determined using the wind measurements from 2000 to 2014 at five coastal locations along the southern coastline of the Black Sea (Kumkoy, Amasra, Sinop, Giresun, Hopa) and from 2006 to 2009 at the offshore location (Gloria) off the coast of Romania. The performances of these wind fields were determined based on statistical characteristics (mean, standard deviation and variation coefficient, etc.), the statistical error analysis for all data and for different wind speed intervals, the wind roses and the probability distributions. Additionally, long-term variations of the yearly error values (SI and bias) of wind speeds from wind data sources during 2000 - 2014 were discussed. Finally, it was concluded that the CFSR wids give the best performance at most stations. The ECMWF datasets yield better results along the western side but the CFSR wind fields have shown better performances along the eastern side of the Black Sea coast and at the Gloria offshore location.Publication Editorial: Offshore wind and wave energy and climate change impacts(Frontiers Media Sa, 2022-09-01) Rosa-Santos, Paulo Jorge; Carvalho, David; Akpinar, Adem; AKPINAR, ADEM; Mühendislik Fakültesi; İnşaat Mühendisliği Bölümü; AAC-6763-2019Publication Quality of the ERA5 and CFS winds and their contribution to wave modelling performance in a semi-closed sea(Taylor & Francis, 2021-03-12) Çalışır, Emre; Soran, Mehmet Burak; Akpınar, Adem; Çalışır, Emre; Soran, Mehmet Burak; AKPINAR, ADEM; Mühendislik Fakültesi; İnşaat Mühendisliği Bölümü; 0000-0002-5422-0119; AAC-6763-2019; JJU-1857-2023; GCE-1854-2022This study aims to investigate the quality of ERA5, a recent reanalysis wind product, and its contribution to wave modelling performance in a semi-closed sea, the Black Sea. This investigation includes a comparison of ERA5 surface wind fields with the ones from the CFSR to assess if this latest reanalysis improved the representation of the surface winds. Wind speeds from both reanalyses were validated with measurements at Gloria, the only sea wind measurement station on the Black Sea. Validations were also conducted using altimeter and scatterometer satellite data after which results were later compared against each other. The second aim of this study investigates whether a wave hindcast model forced with the ERA5 wind fields has improved prediction of wave parameters. A SWAN model with default settings was used to compare the results under the same conditions. Performance analyzes of the default SWAN wave estimates with both ERA5 and CFSR winds were conducted using three offshore buoy measurements and altimeter data of satellites over the Black Sea. Results show that ERA5 winds are more biased compared to CFSR winds at Gloria location. Both CFSR and ERA5 underestimate wind speeds. ERA5 performs better than the CFSR in lower wind speeds and worse in higher wind speeds. However, ERA5 winds have less bias and are more scattered than the CFSR winds against the satellite data. SWAN driven by CFSR winds performs better than the one driven by ERA5 winds against both buoy and satellite data.Publication Performance based assessment of a small-scale artificially nourished beach(Elsevier, 2023-08-30) Karasu, Servet; Marangoz, Hasan Oğulcan; Gülkaya, Enes; Akpınar, Adem; Ceylan, Yusuf; Yılmaz, Enver; AKPINAR, ADEM; Mühendislik Fakültesi; İnşaat Mühendisliği Bölümü; AAC-6763-2019In coastal engineering studies, coastal protection procedures can be provided by hard and soft methods. Soft methods applied using the right techniques and methods are not only long-lasting but also adapt to the natural structure of the coast. This study aims to present monitoring the development of a small-scale artificial nourished beach between the groins for 15 months and analyze its performance. For this purpose, field studies were carried out with land and sea observations taken once before nourishment and at 8 different times after nourishment. The seabed and profile variations observed at different sections were analyzed after processing field data. For determining the characteristics of the natural beach and borrow area before nourishment a sieve analysis was done for sediment samples taken from the shoreline, beach face, and 1-m depth on the nourished area. Sediment transportation of nourished material was observed by monitoring the amount of material remaining in 3 subregions (a nearshore region between the groins - A, a region representing the seaward end of the groins - B, and a region offshore of the groins - C) in the nourished region over time. The relationship between this behavior and waves was examined by considering the wave roses and time series of wave parameters produced as a result of wave simulations performed with the third-generation wave hindcast model SWAN. Lastly, as well as the variation of the mean layer thickness, the retreat of coastline, and mean beach width on the nourished area by the time were extracted for 8 different surveys. The results show that artificial beach nourishment materials were eroded in less than five months and the beach width returned to its initial position. The nourished material transported out groin-protected area moved eastward due to north-west dominated waves and the eastward longshore transport.Publication Wave storm events in the western mediterranean sea over four decades(Elsevier, 2022-01-14) Amarouche, Khalid; Akpınar, Adem; Semedo, Alvaro; AMAROUCHE, KHALID; AKPINAR, ADEM; Mühendislik Fakültesi; İnşaat Mühendisliği Bölümü; 0000-0001-7983-4611; AAC-6763-2019; AFR-7886-2022The rising intensity and recurrence of wave storm events can seriously impact navigation and coastal and offshore structures in the Western Mediterranean Sea. Therefore, the present study is focused on wave storm events in the Western Mediterranean Sea, over the last four decades. The spatial decadal variations of wave storm events are shown, considering variations in the parameters that characterise wave storms, such as significant wave height (SWH), wave storm duration, and wave storm direction. Additionally, the decadal variation in wave storm intensities is evaluated through the storm power index (SPI) and the total storm wave energy (TSWE). The study is based on a wave hindcast, developed using a calibrated SWAN model. The wave storm events are obtained based on the SWH time series for 24 325 locations, distributed over an unstructured grid, covering the entire Western Mediterranean Sea. The decadal variation in the number of wave storm events, maximum and mean wave storm duration, SPI, and TSWE were observed in large parts of the West Mediterranean Sea during the last four decades. However, variations in mean SWH during these storms are low, and do not show a real implication in the decadal changes in the wave storm intensity (SPI and TSWE). Locations of significant increasing changes in SPI and TSWE show a dependence on changes in the wave storm duration. They may be related to variations in wave storm direction in some areas. Increases in wave storm duration are mainly responsible for increases in wave storm intensities over the last decade.
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