Chapter I
Climatological data for the study area
11
Statistical analysis of offshore wind speed allowed us to define some values represented in Table
I-5
Table I-5 Wind speed.
Wave heights
Value (m)
í µí± í µí±
í µí°´verage height
5.53
í µí± í µí±
Average of the top 1/3 of the record
9.35
í µí± í µí±í µí±í µí± Minimum value of the record
0.20
í µí± í µí±í µí±í µí±¥ Maximum value of the record
25.60
The database of the study area allowed us to determine the plots annual and seasonal wind roses
and the frequency of wind occurrence by direction represented in Table I-6.
Table I-6 Annual and seasonal occurrence of offshore winds by direction.
Annual (%)
Winter (%)
Spring (%) Summer (%)
Autumn
(%)
N (0°)
5.80
5.25
5.94
6.72
5.55
NE (45°)
15.07
7.49
15.26
24.95
13.08
E (90°)
21.67
11.84
21.25
33.86
20.53
SE (135°)
7.13
7.05
7.52
6.29
8.01
S (180°)
8.04
11.99
6.95
4.28
9.41
SW (225°)
14.09
20.59
14.72
6.19
15.63
W (270°)
19.37
27.20
20.03
10.69
20.59
NW (315°)
7.70
8.58
8.34
7.02
7.21
From the annual wind rose, illustrated in Figure I-10, we can clearly observe the dominance of
two directions: East and West, which account for nearly 40% of all winds blowing off Algiers
Bay. The highest peak speed recorded reach more than 25,6 m/s from the West sector.
• East direction: This wind direction represents approximately 21% of the annual time.
Interestingly, it exhibits a higher frequency of occurrence during summer (33%)
compared to winter (11%). This indicates that during the summer months, there is a
greater likelihood of winds blowing from the East.
• West direction: Constituting around 19% of the annual duration, the West direction
shows a higher frequency of occurrence in winter (27%) compared to summer (10%).
Thus, during winter, there is a heightened probability of winds originating from the West.
Furthermore, an examination of the monthly wind roses (Figure I-11) uncovers additional
insights:
• Calm winds: During the summer months, wind speeds do not exceed 18 m/s.
• Stronger winds: In contrast, the winter months experience more vigorous winds, with
speeds exceeding 18 m/s.
Climatological data for the study area
11
Statistical analysis of offshore wind speed allowed us to define some values represented in Table
I-5
Table I-5 Wind speed.
Wave heights
Value (m)
í µí± í µí±
í µí°´verage height
5.53
í µí± í µí±
Average of the top 1/3 of the record
9.35
í µí± í µí±í µí±í µí± Minimum value of the record
0.20
í µí± í µí±í µí±í µí±¥ Maximum value of the record
25.60
The database of the study area allowed us to determine the plots annual and seasonal wind roses
and the frequency of wind occurrence by direction represented in Table I-6.
Table I-6 Annual and seasonal occurrence of offshore winds by direction.
Annual (%)
Winter (%)
Spring (%) Summer (%)
Autumn
(%)
N (0°)
5.80
5.25
5.94
6.72
5.55
NE (45°)
15.07
7.49
15.26
24.95
13.08
E (90°)
21.67
11.84
21.25
33.86
20.53
SE (135°)
7.13
7.05
7.52
6.29
8.01
S (180°)
8.04
11.99
6.95
4.28
9.41
SW (225°)
14.09
20.59
14.72
6.19
15.63
W (270°)
19.37
27.20
20.03
10.69
20.59
NW (315°)
7.70
8.58
8.34
7.02
7.21
From the annual wind rose, illustrated in Figure I-10, we can clearly observe the dominance of
two directions: East and West, which account for nearly 40% of all winds blowing off Algiers
Bay. The highest peak speed recorded reach more than 25,6 m/s from the West sector.
• East direction: This wind direction represents approximately 21% of the annual time.
Interestingly, it exhibits a higher frequency of occurrence during summer (33%)
compared to winter (11%). This indicates that during the summer months, there is a
greater likelihood of winds blowing from the East.
• West direction: Constituting around 19% of the annual duration, the West direction
shows a higher frequency of occurrence in winter (27%) compared to summer (10%).
Thus, during winter, there is a heightened probability of winds originating from the West.
Furthermore, an examination of the monthly wind roses (Figure I-11) uncovers additional
insights:
• Calm winds: During the summer months, wind speeds do not exceed 18 m/s.
• Stronger winds: In contrast, the winter months experience more vigorous winds, with
speeds exceeding 18 m/s.