Evaluation of the Circulation Patterns in the Black Sea Using Remotely Sensed and in Situ Measurements

Abstract

The objective of the present work is to provide an overview of the general circulation features in the Black Sea basin. In order to achieve this, 18 years (1993-2010) of satellite data coming from the Aviso website were analyzed. A descrip-tion of the general circulation patterns in the Black Sea is first presented. This is followed by statistical analyses of the satellite data in 20 points covering the entire area of the sea. The reference points were chosen as follows: 12 points along the Rim cyclonic current, 3 points inside the Rim cyclonic current, 4 points on the edge of two of the biggest an-ticyclonic gyres outside the Rim current and one point in the northwestern shelf area of the basin. Rose graphics were drawn for the reference points for winter and summer time. Finally, 9 years of in situ data obtained from the Gloria drilling platform were analyzed and compared with the satellite data. The present study shows that most of the reference points are sensitive to seasonal changes. The current velocities depend mostly on the points location: the points located on the Rim current and on the nearshore anticyclonic eddies present higher values than the ones located in or outside the general circulation features.

Full text

International Journal of Geosciences, 2013, 4, 1009-1017
http://dx.doi.org/10.4236/ijg.2013.47094
Published Online September 2013 (http://www.scirp.org/journal/ijg)
Evaluation of the Circulation Patterns in the Black Sea
Using Remotely Sensed and in Situ Measurements
Robert Toderascu, Eugen Rusu
Department of Applied Mechanics, “Dunarea de Jos” University of Galati, Galati, Romania
Email: Robert.Toderascu@ugal.ro
Received June 16, 2013; revised July 19, 2013; accepted August 15, 2013
Copyright © 2013 Robert Toderascu, Eugen Rusu. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
The objective of the present work is to provide an overview of the general circulation features in the Black Sea basin. In
order to achieve this, 18 years (1993-2010) of satellite data coming from the Aviso website were analyzed. A descrip-
tion of the general circulation patterns in the Black Sea is first presented. This is followed by statistical analyses of the
satellite data in 20 points covering the entire area of the sea. The reference points were chosen as follows: 12 points
along the Rim cyclonic current, 3 points inside the Rim cyclonic current, 4 points on the edge of two of the biggest an-
ticyclonic gyres outside the Rim current and one point in the northwestern shelf area of the basin. Rose graphics were
drawn for the reference points for winter and summer time. Finally, 9 years of in situ data obtained from the Gloria
drilling platform were analyzed and compared with the satellite data. The present study shows that most of the reference
points are sensitive to seasonal changes. The current velocities depend mostly on the points location: the points located
on the Rim current and on the nearshore anticyclonic eddies present higher values than the ones located in or outside the
general circulation features.
Keywords: Black Sea; Circulation Patterns; Statistical Analyses; Rose Graphics
1. Introduction
The Black Sea is an enclosed sea situated between
Europe, Anatolia and Caucasus, bounded by the 40.56˚N
and 46.33˚N latitude and 27.27˚E - 41.42˚E longitude. It
is the second enclosed sea on Earth after the Caspian Sea,
with a surface of 423,000 km
2
. The only connection
bounding the Black Sea to the Global Ocean is by the
Bosphorus strait, a 0.7 - 3.5 narrow channel with 31 km
in length and a depth that can vary from 39 to 100 m.
The sea contains three vertical water layers that do not
mix, the bottom one being the largest anoxic water body
on Earth. The surface layer is located on the sea surface,
spreading to 50 m depth and is the most active water
layer of the sea. It responds strongly to the seasonal
temperature variations and wind fields. The second layer
is the cold intermediate layer located at depths that vary
from 50 to 180 m. Its most significant characteristic fea-
ture is the fact that the temperature here is constant, be-
tween 6˚C and 8˚C, not being affected by the temperature
changes in the surface layer. The cold intermediate layer
is formed by the convective processes associated with the
winter cooling of the surface waters [1-3]. Below the
intermediate cold layer is the bottom layer where waters
are mostly stagnant showing small changes in properties,
except near boundaries. In the depths higher than 1700 m,
the bottom layer is subjected to geothermal heating from
the sea floor, the temperature being about 8.8˚C [4]. The
maximum depth of the Black Sea is of 2588 m. However,
these are isolated points located in the south and south-
east of the basin. The average maximum depth of the sea
is 2100 m.
The Black Sea’s salinity is lower than in the open seas
or in the oceans, due to the enclosed state and high river
discharges. The average salinity in the Black Sea is 18.2
PSU, but it can be much lower near the river discharges.
The bottom layer’s salinity, however, has increased val-
ues by an average of 21.8 PSU. This difference is main-
tained due to the fact that the surface and bottom waters
do not mix, and the lower layer is receiving more saline
waters from the Mediterranean Sea. Moreover, the sur-
face layer is exposed to rain, river discharges and dilu-
tion.
The cyclonic character of the Black Sea circulation
resulting from the cyclonic state of the wind field pat-
terns was first described by Knipovich [6] Later on
Filipov [7], Boguslavskiy et al. [8], Blatov et al. [9],
Stanev et al. [10], Stanev [11] and Eremeev et al. [12]
C
opyright © 2013 SciRes. IJG

R. TODERASCU, E. RUSU
1010
p
rovided valuable details regarding the sea circulation
patterns. However, the model proposed did not contribute
to a significant change to Knipovich’s classical circula-
tion model.
The northwestern shelf of the sea consists of a close to
200 km wide shelf that receives the fresh water input
from Danube, Dniestr and Dniepr rivers. The surface
circulation is characterized by a persistent cyclonic
coastal current referred to as the Rim current, with a
width of over 75 km and an average speed of 0.2 ms
−1
at
the surface [13]. Between the Rim current and the coast,
a number of seasonal anticyclonic eddies are formed.
While the Rim current meanders eastward along the
Anatolian coast, it forms two anticyclonic coastal eddies
that were identified and labeled by Oguz et al. [14] as the
Sinop and Kizilirmak eddies. In the eastern area of the
basin, the Batumi eddy is formed. The Rim current flows
along the Caucasian coast to the narrow continental slope,
meandering in the form of backward curling. The jet
separates three cyclonic eddies of the eastern basin that
constitute the multiple cells of the Eastern Basin Cyc-
lonic Gyre [13]. In the coastal side of the offshore jet, a
small anticyclonic eddy is formed, called the Caucasian
eddy. The Rim current continues to meander to the south
of the Crimean Peninsula between two larger coastal
anticyclonic eddies and two cyclonic eddies located in
the central part of the basin. The anticyclonic eddies lo-
cated on the northern side are referred as the Crimean
Eddy and Sevastopol Eddy, respectively [13].
While it proceeds southwest towards the Bosphorus
area, the Rim current creates the Bosphorus eddy. A
small anticyclonic eddy is formed in the western area of
the Black Sea basin, between Sevastopol and Bosphorus
eddies, labeled as Kali-Akra. Its basin-wide circulation is
closed with the Sakarya eddy, situated in the southwest
area.
Among the above mentioned eddies, Batumi and Se-
vastopol are the most permanent and largest mesoscale
structures [15,16]. Figure 1 presents a scheme of the
Black Sea surface circulation as discussed above. The
solid lines indicate the recurrent features of the general
circulation.
2. Statistical Analysis of the Circulation
Patterns Using Satellite Data
In order to achieve a better understanding of the current
fields in the Black Sea basin and of their time and space
variations, 18 years of satellite data were analyzed, cov-
ering the time period 1993-2010. The satellite data were
obtained from Aviso website [17] and contains daily
measurements of the U and V components of the currents
with a spatial resolution of approximately 10 km on the
horizontal and of 13 km on the vertical.
20 reference points were considered in the present
analysis, as shown in Figure 2. The first 12 points (P1,
P2, … P12) were considered on the Rim current (with
red), points P13-P15 were located inside the Rim cyc-
lonic current (with purple), points P16, P17 at the edge of
the Batumi eddy, P18, P19 at the edge of the Sinop eddy
(with green) and point P20 was located on the north-
western shelf area of the Black Sea basin (with orange).
In Table 1 the coordinates of the reference points are
presented, along with the monthly averaged values of
current velocities. Table 2 shows the statistical analyses
for the reference points considering the following pa-
rameters: minimum, maximum, mean and median values,
standard deviation, skewness and kurtosis. In Table 3,
percentile analyses regarding the 50th and 95th percen-
tiles are presented for the reference points considered,
grouped in winter and summer time, respectively where
winter time is the six month period from October to
March and summer from April to September.
Figure 1. Schematic of the Black Sea surface circulation. The solid lines indicate recurrent features of the general circulation.
Copyright © 2013 SciRes. IJG

R. TODERASCU, E. RUSU
1011
Figure 2. The bathymetric map of the Black Sea with the location of the 20 reference points as follows: red—points located on
the Rim cyclonic current, purple—points located inside the Rim current, green—points located at the edge of the anticyclonic
eddies, orange—point located in the northwestern shelf area of the sea.
Table 1. Monthly averaged values of the current velocity (ms
−1
) for the reference points (P1, P2, … P20) for the period 1993-2010.
Month
Points (coordinates)
Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.
P1(44.4N, 30.43E) 0.075 0.074 0.073 0.079 0.079 0.075 0.066 0.063 0.056 0.057 0.062 0.069
P2 (43.18N, 29.43E) 0.106 0.119 0.133 0.125 0.112 0.111 0.087 0.108 0.111 0.107 0.100 0.113
P3 (41.58N, 29E) 0.133 0.125 0.126 0.106 0.096 0.095 0.108 0.119 0.110 0.096 0.110 0.102
P4 (41.36N, 29.58E) 0.078 0.082 0.083 0.093 0.074 0.074 0.073 0.077 0.085 0.078 0.082 0.087
P5 (42.7N, 31.59E) 0.061 0.056 0.059 0.067 0.067 0.061 0.059 0.052 0.058 0.076 0.078 0.070
P6 (42.21N, 34.2E) 0.076 0.080 0.077 0.070 0.077 0.074 0.071 0.076 0.069 0.069 0.072 0.068
P7 (41.32N, 36.59E) 0.068 0.097 0.083 0.081 0.064 0.063 0.069 0.073 0.081 0.078 0.077 0.082
P8 (42.1N, 39.3E) 0.143 0.097 0.098 0.097 0.095 0.106 0.122 0.134 0.128 0.115 0.121 0.131
P9 (43.32N, 39.14E) 0.127 0.115 0.111 0.110 0.116 0.103 0.101 0.126 0.119 0.110 0.125 0.122
P10 (44.38N, 36.49E) 0.155 0.145 0.137 0.133 0.105 0.108 0.134 0.126 0.145 0.149 0.133 0.135
P11 (43.59N, 33.59E) 0.080 0.075 0.068 0.071 0.069 0.071 0.064 0.063 0.079 0.078 0.078 0.073
P12 (44N, 32E) 0.149 0.137 0.162
0.179 0.168 0.159 0.152 0.125 0.128 0.139 0.124 0.139
P13 (43N, 30.59E) 0.070 0.091 0.080 0.076 0.084 0.083 0.074 0.074 0.082 0.088 0.096 0.081
P14 (43.1N, 32.58E) 0.066 0.059 0.073 0.075 0.064 0.069 0.064 0.072 0.061 0.071 0.065 0.068
P15 (42.59N, 36E) 0.081 0.082 0.083 0.076 0.068 0.079 0.085 0.090 0.087 0.091 0.092 0.081
P16 (41.23N, 40.4E) 0.108 0.101 0.106 0.105 0.112 0.121 0.113 0.108 0.108 0.108 0.097 0.112
P17 (43.32N, 39.57E) 0.117 0.083 0.094 0.089 0.102 0.088 0.091 0.095 0.107 0.137 0.144 0.125
P18 (44.37N, 33E) 0.116 0.123 0.122 0.097 0.103 0.097 0.102 0.089 0.116 0.116 0.101 0.119
P19 (44.4N, 31.46E) 0.181 0.181 0.183 0.169 0.161 0.176 0.174 0.144 0.137 0.128 0.137 0.158
P20 (45.21N, 31E) 0.071 0.075 0.068 0.057 0.064 0.058 0.062 0.073 0.069 0.076 0.080 0.069
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R. TODERASCU, E. RUSU
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Table 2. Current velocity statistics for the reference points (P1, P2, … P20) in the Black Sea basin.
Nr of points = 6672 Minimum (ms
−1
) Maximum (ms
−1
) Mean (ms
−1
)Median (ms
−1
) St. Dev (ms
−1
) Skewness Kurtosis
P1 0.001 0.342 0.069 0.062 0.041 1.184 5.455
P2 0.001 0.454 0.111 0.094 0.071 1.207 4.609
P3 0.001 0.463 0.110 0.097 0.068 1.255 5.357
P4 0.001 0.293 0.080 0.071 0.048 1.076 4.339
P5 0.000 0.438 0.063 0.056 0.040 1.633 10.307
P6 0.000 0.227 0.073 0.068 0.040 0.742 3.420
P7 0.000 0.313 0.076 0.070 0.045 1.158 5.266
P8 0.002 0.429 0.117 0.105 0.067 1.024 4.360
P9 0.003 0.429 0.116 0.103 0.070 0.980 3.898
P10 0.001 0.417 0.133 0.119 0.077 0.870 3.500
P11 0.001 0.365 0.072 0.066 0.041 1.215 6.219
P12 0.002 0.558 0.146 0.131 0.083 0.992 4.410
P13 0.001 0.354 0.081 0.070 0.054 1.598 6.570
P14 0.001 0.308 0.068 0.063 0.037 1.040 5.278
P15 0.001 0.370 0.082 0.072 0.049 1.199 5.154
P16 0.002 0.427 0.109 0.100 0.059 0.949 4.285
P17 0.001 0.626 0.106 0.094 0.068 1.699 8.971
P18 0.001 0.396 0.108 0.098 0.064
0.849 3.668
P19 0.003 0.588 0.160 0.151 0.083 0.635 3.388
P20 0.001 0.293 0.069 0.063 0.039 0.992 4.577
Table 3. Percentile analysis for the reference points (P1, P2, … P20) in the Black Sea for summer and winter time, respec-
tively the second quartile and the 95th percentile.
Point Time period Data points
50th percentile
(ms
−1
)
95th percentile
(ms
−1
)
Point Time period Data points
50th percentile
(ms
−1
)
95th percentile
(ms
−1
)
Summer 3294 0.059 0.140 Summer 3294 0.062 0.141
P1
Winter 3110 0.064 0.153
P11
Winter 3110 0.069 0.154
Summer 3294 0.087 0.244 Summer 3294 0.136 0.298
P2
Winter 3110 0.101 0.273
P12
Winter 3110 0.128 0.303
Summer 3294 0.091 0.227 Summer 3294 0.068 0.181
P3
Winter 3110 0.099 0.245
P13
Winter 3110 0.071 0.192
Summer 3294 0.070 0.167 Summer 3294 0.061 0.135
P4
Winter 3110 0.074 0.187
P14
Winter 3110 0.064 0.134
Summer 3294 0.053 0.134 Summer 3294 0.069 0.182
P5
Winter 3110 0.059 0.138
P15
Winter 3110 0.074 0.177
Summer 3294 0.068 0.144 Summer 3294 0.104 0.211
P6
Winter 3110 0.067 0.153
P16
Winter 3110 0.095 0.225
Summer 3294 0.067 0.136 Summer 3294 0.089 0.205
P7
Winter 3110 0.072 0.166
P17
Winter 3110 0.099 0.249
Summer 3294 0.104 0.233 Summer 3294 0.093 0.209
P8
Winter 3110 0.106 0.256
P18
Winter 3110
0.099 0.242
Summer 3294 0.099 0.244 Summer 3294 0.148 0.301
P9
Winter 3110 0.104 0.253
P19
Winter 3110 0.157 0.320
Summer 3294 0.110 0.274 Summer 3294 0.061 0.131
P10
Winter 3110 0.131 0.290
P20
Winter 3110 0.064 0.149
Copyright © 2013 SciRes. IJG

R. TODERASCU, E. RUSU
Copyright © 2013 SciRes. IJG
1013
In statistical analysis, the standard deviation measures
the data dispersion from the mean value as in Equation
(1):

2
,Std E X






(1)
with


EX

 representing the mean value, where E
is the expectation operator. X represents a discrete ran-
dom variable with the probability mass function p(x).
Then the expected value will be:


.
ii
EX xpx

(2)
In probability theory and statistics, skewness is a
measure of the symmetry distribution in a certain data set.
The skewness value can be positive, negative or unde-
fined. The skewness of a variable X is defined as the
third standardized moment:
3
3
Skew ,


 (3)
where
3

is the third moment above the mean and the
k
th
moment about the mean is defined as:


.
k
k
EXEX









(4)
Kurtosis represents the relative concentration of the
data in the centre versus in the tails of a frequency dis-
tribution when is compared with the normal distribution
(which has a kurtosis value of 3). This is equal to the
fourth moment around the mean divided by the square of
the variance (or the fourth power of the standard devia-
tion) of the distribution minus 3.
4
4
3.Kurt


 (5)
Moreover, analyses regarding the 50th and 95th per-
centiles were performed for all the points, grouped by
summer time and winter time.
Percentiles are generally used in order to characterize
a frequency distribution. In special the 50th and the 95th
percentiles are often considered to identify the median
values and the maximum data distributions being unaf-
fected by outward values which are distant from the rest
of the data. Percentiles (p
i
) are computed as follows:
0.5
100 ,
i
i
p
n


(6)
where i represents the position inside the dataset that
marks the percentile to be calculated and n is the total
number of the values in the distribution.
A first conclusion that can be drawn from
Table 1 is
that the average current velocity values in the Black Sea
are in general small. There are usually small variations
between summer and winter periods. The most stable
points regarding velocity variations appear to be P1, P2,
P3, P4, P5 and P6. As expected, the points P1-P12 have
higher current velocities than the rest, due to their coor-
dinates located on the Rim current. The points P13, P14
and P15, located inside the curve described by the Rim
current, have smaller velocities than the ones situated on
the Rim or on the two anticyclonic eddies. The smallest
velocity values are the ones recorded for the point P20,
situated in the northwestern shelf zone, an area with
mostly calm waters where no significant circulation fea-
ture was observed.
3. Directional Distributions of the Current
Velocity
The rose type graphics are used to give a more compre-
hensive picture of how current speeds and directions are
distributed in a particular point. Using a polar coordinate
system for gridding the frequency of the currents over the
time period is plotted by current direction, with color
bands showing current velocity ranges. The direction of
the longest spoke shows the current direction with the
greatest frequency. Each concentric circle represents a
different frequency, starting from zero at the center with
increasing frequencies at the outer circles. In
Figures 3
and
4 rose graphics were drawn for the 20 reference
points.
Figure 3 presents rose graphics for the winter
time, where winter is considered the time frame from
October to March, while
Figure 4 presents the rose
graphics for the summer time (April to September).
By comparing
Figure 3 and Figure 4, it can be observed
that there are significant changes between winter and
summer time in current orientation, however these changes
do not apply to all the points. P1, P5, P6, P11 and P13
present mostly the same structures for both time frames.
4. Comparisons against in Situ Data
For the Black Sea some current measurements were
available for the time period 2002-2009 and they were
compared against the corresponding satellite data pro-
vided by Aviso. The measurements were taken at the
Gloria drilling platform located on the western side of the
Black Sea, near the Romanian coasts at 44
˚31'N, 29˚34'E,
every six hours. The data were then computed to a daily
average, to fit the satellite data profile. The comparison
between the satellite data and the measurements at the
Gloria drilling platform in the Black Sea shows that the
in situ measured current velocity values are usually
higher than the satellite data with a bias of 0.077
ms
−1
.
Table 4 presents some statistical parameters as mean
values, bias, RMS error, SI (scatter index) and r (correla-
tion coefficient).
With X
i
representing the measured values at the Gloria
drilling platform, Y
i
the corresponding satellite data
values and n the number of ata points considered, the d

R. TODERASCU, E. RUSU
1014
Figure 3. Current velocity roses for the reference points, winter time.
Figure 4. Current velocity roses for the reference points, summer time.
Table 4. Comparison between in situ measurements at the
Gloria drilling platform and satellite data for the period
2002-2009.
Point X
med
(ms
−1
) Y
med
(ms
−1
)
Bias (ms
−1
) RMSE SI R
G 0.195 0.077 0.117 0.147 0.75 −0.025
statistical evaluated are defined by the following rela-
tionships:
1
med
,
n
i
i
X
XX
n




(7)
Copyright © 2013 SciRes. IJG

R. TODERASCU, E. RUSU
1015

1
Bias ,
n
ii
i
X
Y
n




(8)

2
1
RMSE ,
n
ii
i
XY
n




(9)
RMSE
SI ,
X


(10)


1
1
2
22
11
r. (11)
n
ii
i
nn
ii
ii
XXYY
XX YY












5. Discussions
According to satellite data the maximum current velocity
is of 0.626 ms
−1
and it belongs to P17, the point located
at the edge of the Batumi eddy, closely followed by P19
with 0.588 ms
−1
situated at the edge of the Sevastopol
eddy, and P12 with 0.558 ms
−1
, situated on the Rim cur-
rent. Except for the points P4 and P6, the current veloci-
ties recorded on the Rim current are higher than the ones
recorded inside. The minimum values are close to zero
for all the points, while the mean values vary from 0.068
ms
−1
for P14 to 0.160 ms
−1
for P19. The median values
ranges from 0.056 ms
−1
for P5 to 0.151 ms
−1
for P19.
Higher values for the standard deviation suggest that the
data is spread out compared to the mean values. A zero
value for the skewness suggests that the values are rela-
tively evenly distributed on both sides of the mean value
while a positive skew indicates that the tail on the right
side of the probability density function is longer than the
left side and the bulk of values lie to the left of the mean,
this being the case here where the skewness values range
from 0.742 (P6) to 0.699 (P17). Kurtosis represents the
relative concentration of the data in the center versus the
tails of the frequency distribution when is compared to
the normal distribution that has a kurtosis value of 3. In
the present work the values of the kurtosis vary from
3.420 to 10.306.
For the winter time the point P1 is oriented towards
south-west, feature that is preserved for the summer time,
with a small peak added oriented towards north-east.
Point P2 in the winter time shows also a south-west clear
orientation, while for the summer this decreases, a peak
oriented north-west being also added. Regarding P3,
strong differences between winter and summer time can
be observed. While in the winter is showing a strong
south-east orientation, for the summer time this changes
to north-west. P4 is showing a small north-east orienta-
tion for the winter time, while for summer is difficult to
pinpoint a definite direction, with two small peaks ori-
ented west and east. P5 shows little differences in current
orientation between summer and winter, also with no
definite direction. The same case applies also for P6
where is also difficult to identify a direction, with the
observation that while in the summer time it presents a
stable radial structure, small peaks in all directions can
be observed in the winter. P7 presents 5 peaks clearly
oriented north-west in the winter time, while in the
summer there is also no definite direction. As well as for
P3, P8 presents major differences between winter and
summer time. While in the winter is oriented towards
south, this changes drastically in the summer time, when
a strong north-east component appear, accompanied by a
small peak oriented towards south. For the point P9 is
difficult to pinpoint a clear orientation in the winter: it
appears to be oriented towards east, but there’s no clear
direction. For the summer time most of the peaks are
oriented south. Major differences can also be observed
for P10: in the winter time there is a clear west orienta-
tion, fact that changes in the summer when an east orien-
tation appear, with small reminiscences from the winter
feature. P11 point seems to preserve most of its features
between the seasons, although in the winter there is a
small north-east component that in the summer disap-
pears. Regarding the P12 point, major differences can be
observed: in the winter there is a strong component ori-
ented north-east, while in the summer the general direc-
tion is split in two: a south-south-west component and a
west one. Due to their position inside the Rim current, it
wasn’t expected to see important changes between sum-
mer and winter time for the points P13, P14 and P15,
however there are small differences, especially for P15
located at the edge of the Eastern Gyre. Points P16, P17,
P18 and P19 are located at the edge of the Batumi (P16,
P17) and Sevostok (P18, P19) eddies. These are two of
the biggest nearshore anticyclonic eddies present in the
Black Sea, and are characterized by high velocities and
strong seasonal differences, fact confirmed by the present
analysis. In the winter time P16 is split into multiple di-
rections, mostly oriented east, while in the summer there
is a definite west orientation, with high peaks. P17 pre-
sents a higher turbulence for the winter time, with no
definite direction, but mostly oriented north, east and
west. This feature changes for the summer time when a
north-east component appears, along with a smaller one
towards north-west. For P18 in the winter a strong north-
west orientation can be observed, while in the summer
this changes towards south-east. Also P19 presents im-
portant differences between seasons with a strong com-
ponent oriented south-west in the winter that changes to a
north-east in the summer time. Seasonal variations can
also be observed in P20, the point located outside the
general features of the Black Sea, in the northwestern
Copyright © 2013 SciRes. IJG

R. TODERASCU, E. RUSU
1016
sh
elf area. While in the winter two dominant directions
are present: north and south, for the summer there is a
general orientation south.
5. Conclusions
As expected, most of the points located on the Rim cyc-
lonic current and on the nearshore anticyclonic eddies
have higher velocities than the ones located in the central
gyres or northwestern shelf area. Also, they are described
by a higher instability regarding current speed and direc-
tion on the seasonal changes.
Higher value for kurtosis as the ones registered at
points P5 (10.307), P17 (8.979), P13 (6.570) and P11
(6.219) means that in these cases there is a strong possi-
bility that higher velocities than usual will appear.
A similar study with the emphasis on the anticyclonic
and cyclonic eddies, was treated in [18]. The implemen-
tation of a global circulation modeling system for the
Black Sea basin was presented by Toderascu and Rusu in
[19]. Also, the subject of modeling of wave-current in-
teractions at the Danube mouths was treated by Rusu in
[20]. Another work that needs to be mentioned here is the
work of Rusu and Macuta regarding the numerical mod-
eling of long shore currents in marine environment [21],
as well as the work of L. Rusu regarding the application
of numerical models to evaluate oil spills propagation in
the coastal environment of the Black Sea [22].
6. Acknowledgements
The work of the first author has been made in the scope
of the project EFICIENT (Management System for the
Fellowships Granted to the Ph.D. Students) supported by
the Project SOP HRD-EFICIENT 61445/2009. The al-
timeter products were produced by Ssalto/Duacs and
distributed by Aviso with support from Cnes.
This work was also supported by a grant of the Roma-
nian Ministry of National Education, CNCS
—UEFISCDI
PN-II-ID-PCE-2012-4-0089 (project DAMWAVE).
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