Environmental Engineering Reference
In-Depth Information
Fig. 5.7
Simulation of an
initially circular oil spill
advected for 72h with
modelled ocean currents and
a
5% of wind velocity
(provided by the atmospheric
numerical model at 10 m
above the sea level).
Black
is
initial spill location and the
red
is final distribution.
Blue
line
is the real drifter
trajectory for the same period
ʳ
=
0
.
Fig. 5.8
RMSE (units in
km) obtained for several
wind drag values computed
for the same initial cloud and
period of study in relation to
a real drifter
Normalized RMSE vs Wind drag
70
60
50
40
30
20
10
0
0
0.5
1
1.5
2
2.5
3
3.5
4
Wind drag [%]
where
N
p
is the number of particles deployed, and
d
n
is the spherical distance (the
arc-length over the Earth surface) between the virtual particle
n
and the real drifter
after 72h, defined as the haversine formula:
R
T
2arcsin
sin
2
ʔ
2
sin
2
ʔ
2
d
n
=
R
T
ʱ
=
+
cos
(ˆ
n
)
cos
(ˆ
d
)
,
where R
T
is the average Earth radius (6371km) and
ʱ
is an angle; for a particle and
(ʻ
n
,ˆ
n
)
(ʻ
d
,ˆ
d
)
ʔ
ʔ
ˆ
=
ˆ
d
−
ˆ
n
and
a drifter with positions
and
,the
terms are
ʔ
ʻ
=
ʻ
d
−
ʻ
n
.
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