Person: AKPINAR, ADEM
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AKPINAR
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ADEM
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Publication 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; Bursa Uludağ Üniversitesi/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 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; Bursa Uludağ Üniversitesi/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 New wind-wave climate records in the Western Mediterranean Sea(Springer, 2021-11-03) Amarouche, Khalıd; Bingölbalı, Bilal; Akpınar, Adem; AMAROUCHE, KHALID; BİNGÖLBALİ, BİLAL; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü; 0000-0001-7983-4611; 0000-0002-9042-6851; AFR-7886-2022; AAB-4152-2020; AAC-6763-2019This study presents a detailed analysis of changes in wind and wave climate in the Western Mediterranean Sea (WMed), based on 41 years of accurate wind and wave hindcasts. The purpose of this research is to assess the magnitude of recent changes in wave climate and to locate the coastal areas most affected by these changes. Starting from the Theil-Sen slope estimator and the Mann Kendall test, trends in mean and Max significant wave heights (SWH) and wind speed (WS) are analysed simultaneously on seasonal and annual scales. Thus, the new wave records observed since 2010 have been located spatially and temporally using a simple spatial analysis method, while the increases in maximum wave heights over the last decade have been estimated and mapped. This work was motivated by evidence pointed out by several authors concerning the influence of global climate change on the local climate in the Mediterranean Sea and by the increase in the number and intensity of wave storm events over recent years. Several exceptional storms have recently been observed along the Mediterranean coasts, including storm Adrian in 2018 and storm Gloria in 2020, which resulted in enormous damage along the French and Spanish coasts. The results of the present study reflect a worrying situation in large part of the WMed coasts. Most of the WMed basin experiences a significant increasing trend in the annual Max of SWH and WS with evident inter-seasonal variability that underlines the importance of multi-scale analysis to assess wind and wave trends. Since 2013, about half of the WMed coastline has experienced records in wave climate, not recorded at least since 1979, and several areas have experienced three successive records. Several WMed coasts are experiencing a worrying evolution of the wave climate, which requires a serious mobilisation to prevent probable catastrophic wave storms and ensure sustainable and economic development.Publication Spatial characteristics of wind and wave parameters over the Sea of marmara(Elsevier, 2021-01-23) Kutupoğlu, Volkan; Bingölbalı, Bilal; Çalışır, Emre; Akpmar, Adem; Kutupoğlu, Volkan; BİNGÖLBALİ, BİLAL; Çalışır, Emre; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü; Bursa Uludağ Üniversitesi/İnegöl Meslek Yüksekokulu; 0000-0002-5422-0119; 0000-0003-4496-5974; 0000-0002-0440-1202; 0000-0002-9042-6851; AAB-4152-2020; AAC-6763-2019; JJU-1857-2023This study aims to determine long-term spatial variability of wind and wave characteristics over the Sea of Marmara. For this purpose, we produced four different wind and wave datasets for a period of 40 years (1979-2018) using the calibrated and default-setting SWAN models forced with both CFSR and ERA-Interim winds and inter-compared. The performance of these datasets is examined against the wave height measurements of 2015 at the Silivri buoy station and 27-year (1991-2018) satellites data (ENVISAT, ERS-1, ERS-2, JASON-1, JASON-2, JASON-3, SENTINEL-3A, SENTINEL-3B, TOPEX). Then, for wind and wave climate analysis, the spatial distributions of the wind and wave characteristics over the study area are determined in terms of seasonal and annual averages. 40-year averages of 95th and 99th percentile significant wave heights, probabilities of being larger than significant wave heights exceeding a critical value, and 40-year maximum significant wave heights are spatially analyzed. Finally, the calibrated SWAN model using CFSR winds presents the most accurate results. Therefore, the effects of different model inputs and settings on the model results are examined by creating spatial distributions of the biases of the other three model results and comparing them to those of the calibrated model results using CFSR winds. The CFSR forced and calibrated model predicts the largest average wind speed and average wave height in the central regions of the Sea of Marmara in comparison with the other three models. The shores of Kapidag Peninsula and Marmara Island are exposed to be with the highest wave conditions.Publication Downscaling wave energy converters for optimum performance in low-energy seas(Elsevier, 2021-05-01) Iglesias, Gregorio; Majidi, AjabGul; Bingolbali, Bilal; BİNGÖLBALİ, BİLAL; Akpinar, Adem; AKPINAR, ADEM; Jafali, Halid; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi.; 0000-0003-0006-5843; 0000-0003-4496-5974; 0000-0002-5422-0119; AAB-4152-2020; AAC-8011-2021; AAC-6763-2019As wave energy converters (WECs) are typically designed and optimized for ocean wave conditions, they struggle to perform in low-energy seas or bays, where wave conditions are very different. This work investigates the hypothesis that downscaled versions of WECs may well be more suited for such conditions. More specifically, fifteen downscaled WECs are considered for deployment in the Black Sea. The resizing (downscaling) of the WECs is based on Froude scaling law. Ten values are considered for the scaling factor (lambda(L) = 1/4 1.0, 0.9, 0.8 ... 0.1), and the value that yields the highest capacity factor is selected for downscaling the WEC. The downscaled WEC is then compared with the original (full-scale) WEC in terms of performance (capacity factor, full-load hours, and rated capacity). This analysis is carried out for fifteen WECs and 62 locations at different water depths (5, 25, 50, 75, and 100 m), distributed on 13 lines perpendicular to the shoreline along the south-western coast of the Black Sea. The highest capacity factor was obtained by Oyster, whereas the highest energy output was achieved by SSG and WaveDragon for the locations with 4-16 m depths. For deeper waters (25, 50, 75, and 100 m), the highest capacity factor was obtained by Oceantec. In terms of energy output, the best performers were WaveDragon (at 25 m water depth) and Pontoon (at 50, 75, and 100 m water depths). The interest of this approach, however, lies not only in that it enables a scaling factor to be determined for downscaling a WEC for a given site, but also and more generally in that it proves the initial hypothesis that downscaled WECs may provide a better alternative for low-energy seas than their full-scale counterparts.Publication Dimensionless normalized wave power in the hot -spot areas of the Black Sea(E D P Sciences, 2020-01-01) Majidi, Ajab Gul; Bingölbalı, Bilal; Akpınar, Adem; Rusu, Eugen; Kolhe, M. L.; Majidi, Ajab Gul; BİNGÖLBALİ, BİLAL; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; Kolhe, M. L.; 0000-0003-0006-5843; 0000-0003-4496-5974; 0000-0002-5422-0119; AAB-4152-2020 ; AAC-8011-2021; AAC-6763-2019The main objective of this study is to identify and compare wave power sources in the high potential areas in nearshore and shallow water regions of the Black Sea. To achieve the goal, 23 locations were selected on two parallel lines around 5 m (10 sites) and around 25 m (13 sites) depth along the shoreline. The data needed to do the required analyzes at these locations were produced by using the calibrated nested layered 31-year wave hindcast SWAN model, which is operated between 1979-2009 with CFSR winds. The wave data were collected at a 2-hour time resolution for the sub-grid domains (SD3, SD2, and SD1) developed for the vicinity of Karaburun, Filyos, and Sinop coasts. HeaveBuoy, Oyster, Seabased AB, WaveDragon, WaveStar, Oyster2, and SSG, the most common known wave energy converters, were evaluated in the analysis. To ensure a more comprehensive analysis of the geographic variation of the predicted electrical power for each considered wave energy converter system, dimensionless normalized wave power and efficiency index were calculated separately for each wave energy converter devices at each location. From the results, it is recognized that generally, all the WEC systems performances are decreasing from Karaburun to Sinop while FB1 (13 m depth) the lowest, and KA2 (25 m depth) has the highest wave power capability. The most and the least energetic years were 1998 and 1989, repectively.Publication Wave power performance of wave energy converters at high-energy areas of a semi-enclosed sea(Pergamon-Elsevier Science Ltd, 2021-01-02) Rusu, Eugen; Majidi, Ajab Gul; Bingolbali, Bilal; BİNGÖLBALİ, BİLAL; Akpinar, Adem; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi.; 0000-0003-0006-5843; 0000-0003-4496-5974; 0000-0002-5422-0119; 0000-0001-6899-8442; AAC-6763-2019; B-6766-2011; AAB-4152-2020; AAC-8011-2021The paper focuses on the performance and determination of optimal installation depths of wave energy converter systems (WECs) in less intensified wave energy locations. Therefore, the study aims to investigate the changes in wave power production performance of different WECs along the coastline of the south-western parts of the Black Sea, a semi-enclosed sea. For this purpose, the data needed was extracted from the dataset produced for the period 1979 to 2009 using a calibrated nested layered wave hindcast SWAN version 41.01AB model forced with CFSR winds. The discussion focuses on the most essential five statistical parameters (dimensionless normalized wave power, efficiency index, capacity factor, capture width and energy production per unit of rated power) that can present an easy and more precise idea about the power production performance of WECs at different depths. The results present that the wave energy resource intensity is generally decreasing gradually from Karaburun to Sinop in the study area; the most energy intensified location is line KA, and the Oceantec WECs shows the best performance in its installation depth range. At different locations and depths, different WECs are more suitable for installation.Publication Inter- and intra-annual wave energy resource assessment in the south-western black sea coast(Pergamon-Elsevier Science Ltd, 2021-01-22) Bingolbali, Bilal; BİNGÖLBALİ, BİLAL; Majidi, Ajab Gul; Akpinar, Adem; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi.; 0000-0003-4496-5974; 0000-0003-0006-5843; 0000-0002-5422-0119; AAB-4152-2020; AAC-6763-2019; AAC-8011-2021This study focuses on the inter- and intra-annual variation in theoretical wave power along the southwestern coast of the Black Sea. Long-term (1979-2009) hindcast developed using the calibrated three-layer nested SWAN model was used for a detailed assessment of wave energy resource. Annual change, monthly and seasonal wave power variability indices were evaluated, and the Optimal Hotspot Index (OHI) was calculated for 62 sites along the coast to rate the hotspot locations. The assessment shows the highest wave energy resources in western Karaburun with higher variability. However, the western Sinop sites have lower wave energy resources compared to western Karaburun sites, in spite of considering the lower variability, these sites are more appropriate for wave energy extraction. The location with the highest potential (KAS 100 m depth) has an average of 8.4 kW/m and a maximum of 1015 kW/m wave power capacity. The east sites of Sinop and Filyos are comparatively less dynamic. Moreover, it was found that the average peak values of wave heights are in February, and the lowest sea state was in June. 2003 was the most, and 1989 was the least energetic years in the 31-year period.Publication Wave climate simulation for the black sea basin(Iahr-int Assoc Hydro-environment Engineering Research, 2015-01-01) Van Vledder, Gerbrant Ph.; AKPINAR, ADEM; BİNGÖLBALİ, BİLAL; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/ İnşaat Mühendisliği Bölümü.; 0000-0002-5422-0119; 0000-0001-6314-9118; 0000-0003-4496-5974; AAC-6763-2019; AAB-4152-2020; ABE-8817-2020This study investigates long-term variability of wave characteristic trends in the Black Sea basin over a period of 31 years. The state-of-the art spectral wave model SWAN was applied to hindcast 31-year of wave conditions. The simulation results were used to assess the inter-annual variability and long-term changes in the wave climate of the Black Sea for the period 1979 to 2009. The model was forced with Climate Forecast System Reanalysis winds, which is determined as the best wind source in Van Vledder and Akpinar (2015). To obtain accurate and reliable results the wave model SWAN was calibrated and validated against all, but limited, available measurements at offshore and near-shore locations located in different regions of the Black Sea. In the calibration process, we focus on especially white-capping and wind input parameters and recently developed formulations. Thus, for the Black Sea basin the best setting and model with the best configuration for the source terms in the wind-wave modelling is obtained. The results of the wave hindcast were also validated against satellite data to assess the spatial variability of wave model quality. From the simulation results, the seasonal and spatial variability of the mean annual significant wave height and wave energy period is obtained and discussed.Publication 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; Bursa Uludağ Üniversitesi/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.