Wind waves in the Black Sea: results of a hindcast study (original) (raw)

Wind waves on the Black Sea: results of a hindcast study

Natural Hazards and Earth System Sciences Discussions, 2014

In this study we describe the wind waves fields on the Black Sea. The general aims of the work were the estimation of statistical wave parameters and the assessment of interannual and seasonal storm variability. The domain of this study was the entire Black Sea. Wave parameters were calculated by means of the SWAN wave model on a 5 km × 5 km rectangular grid. Initial conditions (wind speed and direction) for the period between 1948 and 2010 were derived from the NCEP/NCAR reanalysis. In our calculations the average significant wave height on the Black Sea does not exceed 0.7 m. Areas of most significant storminess are the southwestern and the northeastern corners as expressed in the spatial distribution of wave heights, wave lengths and periods. Besides that, long-term annual variations of storminess were estimated. Thus, linear trends of the annual total duration of storms and of their quantity are nearly stable over the reanalysis period. However, an intensification of storm activity is observed in the 1960s-1970s.

Wind and wave modelling in the Black Sea

Proceedings of the Institute of Marine Engineering, Science, and Technology. Journal of operational oceanography

The performance of a wind-wave modelling system applied to the Black Sea basin is evaluated. The models considered are WRF (Weather Research and Forecasting) for wind and SWAN (Simulating Waves Nearshore) for waves. Model system simulations are carried out for a four-month period at the beginning of 2002. The accuracy of the predictions is further assessed by comparing the main modelled wind and wave parameters with both in-situ and remotely sensed measurements. In statistical terms, the performance of the modelling system is, in general, in line with the results obtained by other studies made in similar environments. Janssen's formulation for the wind-wave generation, recently improved in SWAN, makes this approach the most effective in the Black Sea from the point of view of the numerical accuracy. Subsequently, the geographical variability of the model predictions is assessed together with an evaluation of the wave model results in the spectral space.

A Comparative Analysis of the Wind and Wave Climate in the Black Sea Along the Shipping Routes

Water, 2018

The aim of the present work is to assess the wind and wave climate in the Black Sea while considering various data sources. A special attention is given to the areas with higher navigation traffic. Thus, the results are analyzed for the sites located close to the main harbors and also along the major trading routes. The wind conditions were evaluated considering two different data sets, the reanalysis data provided by NCEP-CFSR (U.S. National Centers for Environmental Prediction-Climate Forecast System Reanalysis) and the hindcast results given by a Regional Climate Model (RCM) that were retrieved from EURO-CORDEX (European Domain-Coordinated Regional Climate Downscaling Experiment). For the waves, there were considered the results coming from simulations with the SWAN (Simulating Wave Nearshore) model, forced with the above-mentioned two different wind fields. Based on these results, it can be mentioned that the offshore sites seem to show the best correlation between the two datas...

Quality of the Wind Wave Forecast in the Black Sea Including Storm Wave Analysis

Sustainability

This paper presents the results of wind wave forecasts for the Black Sea. Three different versions utilized were utilized: the WAVEWATCH III model with GFS 0.25 forcing on a regular grid, the WAVEWATCH III model with COSMO-RU07 forcing on a regular grid, and the SWAN model with COSMO-RU07 forcing on an unstructured grid. AltiKa satellite altimeter data were used to assess the quality of wind and wave forecasts for the period from 1 April to 31 December 2017. Wave height and wind speed forecast data were obtained with a lead time of up to 72 h. The presented models provide an adequate forecast in terms of modern wave modeling (a correlation coefficient of 0.8–0.9 and an RMSE of 0.25–0.3 m) when all statistics were analyzed. A clear improvement in the wave forecast quality with the high-resolution wind forecast COSMO-RU07 was not registered. The bias error did not exceed 0.5 m in an SWH range from 0 to 3 m. However, the bias sharply increased to −2 or −3 m for an SWH range of 3–4 m. W...

Evaluation of extreme storm waves in the Black Sea

Journal of Operational Oceanography, 2020

The objective of the present study is to give a contribution to the extreme wave climate assessment in the Black Sea, as studies of extreme storm waves are of great interest for coastal protection and maritime traffic. High resolution wind wave data sets are used to investigate trends and variability of the characteristics of extreme storm waves. Two different methodologies (Eulerian and Lagrangean) are applied to 30 years of wave hindcast from 1987 to 2016, over the Black Sea to identify extreme storm waves and also to assess the extreme wave climate. Using the Eulerian methodology, it is observed that extreme storm waves are seasonal, being more frequent during the winter and almost non-existent during the summer. Also, that some areas, as the southeastern region of the Black Sea more prone to storm generation, in particular, during winter and autumn. For the seven locations near the coast, a considerable inter-annual variability is found in extreme values, but not so much in the mean. Statistical significance in trend adjustment was only found in two locations in the northwestern coast, for extreme values. Using a Lagrangean methodology, an inter-annual variability in all storm characteristics that is found, more marked in the annual number of wave storms, maximum area affected by storm waves and maximum length, and less marked for maximum Hs in the storm waves and storm lifetime.

Wave Climate Simulation for the Black Sea Basin

This 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 Akpınar (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.

An assessment of the wind re-analyses in the modelling of an extreme sea state in the Black Sea.

This study aims at an assessment of wind re-analyses for modelling storms in the Black Sea. A wind-wave modelling system (Simulating WAve Nearshore, SWAN) is applied to the Black Sea basin and calibrated with buoy data for three recent re-analysis wind sources, namely the European Centre for Medium-Range Weather Forecasts Reanalysis-Interim (ERA-Interim), Climate Forecast System Reanalysis (CFSR), and Modern Era Retrospective Analysis for Research and Applications (MERRA) during an extreme wave condition that occurred in the north eastern part of the Black Sea. The SWAN model simulations are carried out for default and tuning settings for deep water source terms, especially whitecapping. Performances of the best model configurations based on calibration with buoy data are discussed using data from the JASON2, TOPEX-Poseidon, ENVISAT and GFO satellites. The SWAN model calibration shows that the best configuration is obtained with Janssen and Komen formulations with whitecapping coefficient (C ds ) equal to 1.8e−5 for wave generation by wind and whitecapping dissipation using ERA-Interim. In addition, from the collocated SWAN results against the satellite records, the best configuration is determined to be the SWAN using the CFSR winds. Numerical results, thus show that the accuracy of a wave forecast will depend on the quality of the wind field and the ability of the SWAN model to simulate the waves under extreme wind conditions in fetch limited wave conditions.

Evaluation of the Wave Climate Over the Black Sea: Field Observations and Modeling

Coastal Engineering Proceedings

The knowledge of the wave climate is one of the most important data for application of coastal engineering, which includes coastal structure design, sediment transport, coastal erosion and so on. Due to the lack of measurements in many region and high cost of wave measurements, coastal engineers have to estimate wave characteristics using a variety of methods, which comprise empirical and numerical solutions. A variety of empirical and numerical methods have been developed and used for determining wave characteristics. In this study, in order to determine wave climate over the Black Sea, it was used third generation Mike 21 spectral wave model. For this purpose, a series of numerical models were conducted in a way to cover the 13-year period between 1996 and 2008. The obtained results from numerical models were compared to the results of Wind and Deep Water Wave Atlas for Turkish Coasts. It was concluded that the results were highly consistent each other.

Characteristics of the frequency spectra of wind-waves in Eastern Black Sea

Ocean Dynamics, 2014

Spectral information for wind-waves in the Black Sea is extremely limited. Knowledge on spectral characteristics of wind-waves would contribute to scientific, engineering, and operational coastal and marine activities in the Black Sea, and would allow a better understanding of the nature of the waves occurring in this enclosed basin. Frequency spectra obtained from the directional buoys deployed offshore Sinop and Hopa in Turkey, and Gelendzhik in Russia were utilized as the three sets of data to investigate characteristics of windwaves frequency spectra for the Eastern Black Sea. Records were firstly analyzed to identify them as uni-modal or multimodal spectra. Single-peaked spectra were then identified as belonging to fully arisen or developing sea states. Parameters of the JONSWAP and PM model spectra were estimated for the corresponding sea state by using a least square error method. Finally, the records of developing seas were further analyzed to select the ones belonging to stable wind conditions. ECMWF analysis wind fields were utilized as the wind information corresponding to the wave records. Fetch dependencies of non-dimensional spectral variables (variance and peak frequency) and α parameter of the JONSWAP model spectrum were investigated for this data subset .

Review of the Black Sea Wave Spectrum

2006

This paper is focused on the improvement of the SWAN (Simulation of Waves Nearshore) numerical model in order to be better adapted to the specific conditions of the Black Sea Littoral. As coupling conditions - for North, East and South, excepting West boundaries which are represented by land - were used data from the Gloria Meteorological Station. The ALADIN wind field generated by the National Meteorological Administration was used on the southern parts of the Romanian littoral. The first SWAN simulations were performed with SWAN theoretical spectra: JONSWAP and Pierson-Moskowitz. After that, a previously built one-dimensional Black Sea wave spectrum was introduced into the model. Since the numerical model uses a directional 2D spectrum, a methodology proposed by the CERC Shore Protection Manual was applied to transform the initial frequency spectrum into a directional one. This one constructs the two-dimensional spectrum starting from the directional spreading cosine method. By co...