235
1 INTRODUCTION
Metocean data combines meteorological and
oceanographic factors, which are then used in the
design and optimization of equipment that use
renewable energy, both in coastal and offshore areas.
These data are monitored for local winds, wind-driven
values, peak values, surface currents, and deep water
currents dependent on topography and water
circulation in the study location basin.
This paper presents wind statistics for metocean
analytics on a Galata platform, near Varna, Bulgaria, in
offshore area of the Black Sea basin [1].
1.1 Characteristics of studied location
The Black Sea is a body of water and marginal sea of
the Atlantic Ocean between Eastern Europe, the
Caucasus, and Western Asia. It is supplied by a
number of major rivers, such as the Danube, Dnieper,
Southern Bug, Dniester, Don, and the Rioni, along with
the watersheds of neighbouring countries [2].
Some specific characteristics of Black Sea basin
must presented [3]: geographical limits, total shoreline
(4340 km), water surface (432 000 km
2
), river inflow
(340.6 km
3
), water volume (547 000 km
3
), maximal
depth (2212 m), salinity (of the surface waters is about
17 ... 18 parts per thousand), average fresh water
balance (3.7… 441 km
3
), the temperature (in winter
from ( 0.5 ◦C) in the N-E, to about 9 … 10 ◦C in the S-E
and to depths of 50 …100 m is about 6.5 … 8 ◦C; in
summer, the surface layer is warmed to 23 … 26 ◦C and
at depths of 50 … 75 m, a cold layer remains at 7 ◦C),
specific organisms, etc. (Figure 1) [3] [4] .
Experimental Research for Metocean Data and Risks
in the Vicinity of Platforms in the Black Sea
I. Voicu
1
, M. Panaitescu
1
, F.V. Panaitescu
1
& F.A. Vasilica
2
1
Constanta Maritime University, Constanta, Romania
2
Politehnica University of Bucharest, Bucharest, Romania
ABSTRACT: The knowledge of the metocean data is important for the design and construction of different
equipment in offshore area. The paper presents an analysis of environmental factors in different conditions in the
location of study, GALATA platform, Bulgaria. The results of the analysis (wind statistics, wind distribution rose,
wind speed extreme, monthly mean vertical profile of wind speed) cover the period 2008-2023. To analyse correct
design of floating wind turbines must establish wind speed extreme. The data sets obtained were validated using
the CFS3D wind database. To study the risks in vicinity of platforms we used tools of NEAT+ software which
provides the opportunity to make informed decisions and implement appropriate preventive and corrective
measures to protect the environment. The results of the experimental research indicate a favourable general state
of the environment in the Black Sea vicinity of platforms area.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 19
Number 1
March 2025
DOI: 10.12716/1001.19.01.27
236
Figure 1. Map of the Black Sea Basin [3]
The topography and environmental factors of the
Black Sea basin require the development of new tools
for obtaining and processing monitoring data from
space [5], [6].
The location of study useful for the installation of an
offshore wind turbine is in vicinity of Galata platform
(Figure 2): Latitude 28◦11’35”E, Longitude 43◦2’40”N,
depth of water-34 m .
Figure 2. Location of the analysis
Obtaining metocean data implies knowing the
conditions of the data processing tools [7].
Geographical analysis will furnish valuable
information for the study that will be needed before the
deployment of the equipment at the final location. The
seabed structure is very important in area of Galata
platform. Wave parameters and sea currents are
evaluated for the deployment and maintenance of the
wind farm. Wind resource assessment based on local
measurement is key to fully optimise the design of the
structures. In addition, it will provide important data
for future replications in the area as local
measurements are requested by investors and lenders
for an accurate assessment of energy production of
future commercial wind farms. Furthermore, on the
technical side, maximum wind speed will notably be
important for dimensioning the mooring system and
waves, and surface sea currents measurement are
notably used to properly define the operation and
maintenance plan. The paper presents the description
of the methodology that is the basis of obtaining
metocean data.
2 MEASUREMENTS AND METHODOLOGY
2.1 Wind measurements
Wind data collected from different sources during
period 2008 to 2022 (wind speed and direction) were
used for wind statistics in the study location. It was
used as Leosphere WindCube Lidar system, which is
mobile and was mounted on the Galata platform
(Figure 3). For measurements with remote WindCube
sensors, the volume of standard measured data
assumes the homogeneity of the measurement flow. In
the field, this assumption is no longer valid
measurements become inaccurate. The specialized
literature [7] has developed a method to capture the in
homogeneous flow of measurements of the wind
characteristics and render them as precise
measurements depending on the complex conditions
that appear on the flow.
Figure 3. WindCube - assembly at the Galata platform
To obtain the wind speed field, the average value of
the horizontal component of the speed is chosen every
10 minutes and the standard deviation for the same
time interval.
These quantities are statistical values relative to a
point and do not reflect the sequence of velocity values.
All the fluctuations that appear in time under 10
minutes represent rapid changes in the wind
dynamics, therefore, implicitly in the operation of the
wind turbines that we are going to install in that area
for the studied flow. To highlight the fluctuations,
points are chosen and the corresponding wind
statistics are studied.
The following data were used from sources ERA5,
Galata platform, EuxRo01, EuxRo03 and CG Meteo
sensors: coordinates of point, period, height, spatial
resolution, temporal resolution, variables (Table
1)(Figure 4)[8].
Table 1. Data collected from different sources
Sources
ERA5
GALATA
EuxRO01
EuxRO03
CGMETEO
Coordinates
43.2°N
28.2°E
43.04°N
28.19°E
44.7°N
30.779°E
43.98°N
29.936°E
43.802°N
28.605°E
Period
2008-2022
2008
2019-2021
2019-2021
2019-2021
Height [m]
100
300
-
-
-
Spatial
resolution
[km]
300 km
grid
Punctual
Punctual
Punctual
Punctual
Temporal
resolution
Hourly
2
minutes
Hourly
Hourly
15 minutes
Variables
Wind
speed
Wind
direction
Temp.
Pressure
Wind
speed
Wind
direction
-
-
Wind
speed
Wind
direction
Temp.
Pressure
Wind
speed
Wind
direction
Temp.
Pressure
Wind
speed
Wind
direction
Temp.
Pressure
237
Figure 4 Location of the point with available wind data
2.2 Methodology for Metocean Analytics
A preliminary data report is generated for the location
of the study point (#25071) based on a statistical
analysis provided by several sources for a given period
(Table 1). The wind dataset is based on the hourly
Global Climate Forecast System (CFS), which is
composed of two databases: 1) Climate Forecast
System Reanalysis (CFSR) and 2) CFSv2. CFSR
includes numerous data assimilations from 1979 to the
end of 2010 with a spatial resolution of 38 km (0.3◦ ) and
a time step of one hour for the atmospheric model.
CFSv2 is a recent climatological database covering the
period from 2008 to the end of 2022, with new
assimilated data, with a time step of one hour for the
atmospheric model and with a spatial resolution of
0.2◦ [8].
3 RESULTS AND INTERPRETATIONS
3.1 Data processing and the results obtained
In order to ensure an efficient design of the floating
wind turbine structure, a statistical wind analysis must
be done, considering an average of the final results
between the reference data provided by the sources
and the data provided by the WindCube system.
3.1.1 Wind rose and wind direction distribution
This also involves comparing the data with the data
from the specialized literature for the study location.
First, we take into consideration as the reference data
those provided by ERA5 and we check them with the
data obtained from point measurements to validate the
consistency with the data from ERA5 (e.g. wind data
statistics for a month)(Table 2).
After this step followed wind distribution rose and
wind direction distribution at point of study (Figure 5,
Figure 6)[8].
Table 2. Wind distribution rose for February, 2023 [8]
Occurrence probability [%]
Wind
directions [
o
]
Wind
directions
[
o
]
Wind
directions
[
o
]
Wind
speed
[m/s]
[0, 2.5[
Wind
speed
[m/s]
[2.5, 5[
All
magnitudes
>15
Minim
Centre
Maxim
348.75
0
11.25
0.39
1.82
15.03
78.75
90
101.25
0.53
1.25
2.99
168.75
180
191.25
0.56
2.13
5.92
258.75
270
281.75
0.55
1.75
4.14
281.25
292.5
303.75
0.50
1.79
5.27
303.75
315
326.25
0.50
1.63
5.28
Figure 5. Wind rose over the offshore area of study [8]
Figure 6. Wind direction distribution
The main wind direction observed are the Northern
sector (from 315° to 75°) and from the Southern sector
(from 165° to 235°).The highest wind speeds are
distributed over all those wind directions [8].
3.1.2 Wind velocity distribution
The wind speed measured at GALATA platform is
5.5 m/s at 30m during the year 2008.The wind speed for
the period 2008-2022 is evaluated by the measurements
made at the GALATA platform and by the data of the
ERA5 source at the value of 5.7 m/s at 30 m depth and
at 6.5 m/s at 100 m depth. The probabilistic wind
distribution at 100m at GALATA platform is presented
in Figure 7:
Figure 7. Wind speed distribution at GALATA platform at
100m for the long-term period 2008-2022
238
3.1.3 Wind speed extreme
To analyse correct design of floating wind turbines
must establish wind speed extreme (Figure 8).
Figure 8. Wind speed extreme
The information of wind speed from ERA5 data
from 1996 to 2022 are used, corrected to compute 6.5
m/s over the GALATA area at 100m. Over this 27 years
period, the maximum wind speed value in a 1-hour
resolution is 23 m/s.
3.2 Validation of datasets
The datasets obtained were validated using the CFS3D
wind database, which is based on the global hourly
Climate Forecast System (CFS). With its help the
isobaric surfaces (1000 mb and 850 mb , mb- millibar)
and 10m high above ground winds have been
interpolated at each time step (keeping the 1h*
temporal resolution of the CFS original system) and at
each location of the *CFS grids (0.2◦ /0.3◦ ), to produce
a 3D fixed levels (10m, 25m, 50m, 75m, 100m, 125m,
150m, 175m and 200m) dataset.
The results were also compare with the same
categories of data from other scientific publications for
Black Sea metocean analytics [11], [12], [13],[14].
4 THE RISKS IN VICINITY OF GALATA
PLATFORM
Natural resource extraction activities in the Black Sea,
such as those in the marine platforms area (GALATA),
can lead to a number of ecological and operational
hazards, affecting both the marine environment and
industrial infrastructure. Among the most significant
dangers are: oil or natural gas spills, storms and
extreme weather conditions, toxic substances and
heavy metals, changes in the current regime, seismic
risks and geological instability, etc.
In area of GALATA Platform, scientific research
and ecological monitoring are essential for risk
assessment and protection of the marine environment.
These activities are often regulated by european and
national legislation, which imposes strict
environmental standards.
In the present study, the risk assessment was
carried out with the help of the NEAT+ software
(Nexus Environmental Assessment Tool)[15], [16].
For Good Environmental Status (GES) factors such
as: water, air, soil quality, biodiversity, the human
factor, geological and hydrological risks, climate
changes for 1 year and 5 years were evaluated, after
which the risk matrix was drawn up (Figure 9,Figure
10, Figure 11).
Figure 9. The GPS location of study- GALATA Platform
Figure 10. Determination of the GALATA area characteristics
Figure 11. Analysis results based on NEAT+ software
Using results of NEAT+ software, the sensitivity
statements severity summary is presented in Figure 12.
239
Figure 12. Sensitivity statements severity summary
In the case of the Galata Platform, SEB emphasizes
some similar challenges, but also differences related to
the specifics of the extraction activities and the
ecological regime of the area.
5 CONCLUSIONS
Finally, for wind datasets we can conclude:
− The main wind direction observed are the Northern
sector (from 315° to 75°) and from the Southern
sector (from 165° to 235°).
− The long-term wind speed over a 15 years period
2008-2022 is evaluated with GALATA in situ data
and ERA5 data at 5.7 m/s at 30m a.s.l. and at 6.5 m/s
at 100m a.s.l.( wind speed is the rate of the
movement of air flow in distance per unit of time).
− The extreme wind speed is evaluated at 21.4 m/s for
a 10 years period and 23.6 m/s for a 100 years
period.
− In this context, this paper focused on how NEAT
contributes to the assessment, monitoring and
management of risks in the Black Sea, as well as
promoting the sustainable conservation and
protection of this wonderful corner of nature. By
using this advanced platform, new opportunities
are opening up for the conservation of this
remarkable ecosystem and its protection from
environmental threats so that it can be enjoyed by
current and future generations.
In the risk analysis of the Galata Platform area, we
can conclude:
1. Water quality: Industrial activities can affect water
quality by polluting hydrocarbons and hazardous
chemicals. Continuous monitoring and the use of
protective technologies are essential to control these
risks.
2. Biodiversity and marine habitats: The study points
out that the platform affects sensitive marine
habitats and biodiversity around it. Projects to
restore marine habitats and protect vulnerable
species are recommended to counteract negative
effects on marine ecosystems.
3. Ecological and physical risks: The risks of coastal
erosion and changes in the current regime are more
pronounced in this area, which can affect both the
marine environment and the infrastructure of the
platform.
4. Prevention and management measures: GES
proposes a series of measures to reduce risks,
including investments in advanced technologies for
monitoring and preventing ecological accidents.
Greater collaboration between national and
international authorities for environmental
protection is recommended.
Environmental Impact Assessment (EIA) studies
emphasize the importance of implementing pollution
prevention measures, continuous monitoring of water
quality and biodiversity, and managing ecological and
seismic risks. In addition, marine habitat protection
and ecological restoration measures are needed to
minimize the negative effects of industrial activities on
the environment.
ACKNOWLEDGEMENTS
Authors gratefully acknowledge to this material support
path received projects Maximizing the renewable energy
hosting capacity of distribution networks (MAREHC), PNRR
760111 / 23.05.2023, CF 48/14.11.2022 and Black Sea fLoating
Offshore Wind (BLOW), HORIZON-CL5-2021-D3-03, Ref.
101084323- 19.10.2022 of the Constanta Maritime University,
Romania.
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