228
P. Maheras and C. Anagnostopoulou
4.3 Frequencies of The Circulation Types and Their Relationship With
Precipitation
The mean monthly and annual frequencies of the 14 circulation types at 12 UT are
given in Figure 17 and in Table 1. The annual cumulative frequency of the six
anticyclonic types is 47.8%. Similarly, the annual cumulative frequency of the eight
cyclonic types is 52.2%. The cyclonic type C sw appears the highest frequency
(13.1%), with the next most frequent type the anticyclonic type Asw (11.3%). For
both types, the anomaly centres are located to the southwest of the Greek area. With
respect to annual precipitation totals, the cyclonic types are responsible for 90.5% of
the total precipitation over the Greek area, while the anticyclonic types are
responsible for only 9.5%.
For the rainy period (October to March), the contribution of the anticyclonic
types to total precipitation is 8.2%, while the cyclonic types contribute 91.8% (Table
2). The cyclonic type C sw presents the highest individual percentage contribution to
total precipitation (30.8%), followed by the cyclonic type C (28.8%). In terms of
average precipitation per type of circulation the highest values (6.8mmJday) are
Tablel. Monthly relative frequency of circulation types
M Anw Ane A
Asw Ase Ae
C
Cs
Csw Cnw Cne Cse Cn
Cw
J
1.4
3.5 3.5 16
7.6
3.1
7.7
9.8 22.3
3.1 13
1.7
1
6.5
F
4.7 . 2.8 9.2
7.2
6.2
3 i 13.4 9.6 18.7 4.5 12.5
2
0.9 5.4
M
3.9
4.2 4.2 10.3 10.8
2.2 10.6 12.5 16.9
5.2
9.6
3.5
0.7 5.5
A
9.8
3.8 7.8
5.3
9.8
2
13.3 10.9 13.6
8.6
9.1
1.8
1.3 3
M
7.6
5.3 8.3 10.4 4.4
8.5 15.2 5.8 13.6
3.6 11.6 2.7
0.6 2.3
J
17.4
7.1 7.8
5.5
9.3
8.5 12.2 5.7
7.8
5.1 10.8
1.1
0.3
1.6
;
J
13
10
12.8 II
11.8
5.5 13.5
3.4
6.4
2.4
9
0.3
0.1
0.9
A
10.2
7.4 15.2 18.2 12.9
5
13.5
2.6
6.7
3.2
4.2
0
0.4 0.4
S
9.7
5.6 11.3 20.3 12.7
5.6 12.3 4
8.7
2.2
6
0.3
0.3
1.3
0
6.3 11.5 12.2 12.3
9.6
4.3 12.2 4
10.9
2.1 11
1.1
0.2 2.3
N
10.7
1.1 12.5 9.1
4.8
1.7 14.4 7.8 15
7.7
8.7
1.3
0.3 5.1
D
5.5
7.4 5.1 10.1
4.6
4.7 12.2 7.9 16.1
5
15
1.5 0.2 4.7
y
8.3
5.8 9.2 11.3
8.7
4.5 12.5
7
13.1
4.4 10
1.4
0.5 3.2
P. Maheras and C. Anagnostopoulou
4.3 Frequencies of The Circulation Types and Their Relationship With
Precipitation
The mean monthly and annual frequencies of the 14 circulation types at 12 UT are
given in Figure 17 and in Table 1. The annual cumulative frequency of the six
anticyclonic types is 47.8%. Similarly, the annual cumulative frequency of the eight
cyclonic types is 52.2%. The cyclonic type C sw appears the highest frequency
(13.1%), with the next most frequent type the anticyclonic type Asw (11.3%). For
both types, the anomaly centres are located to the southwest of the Greek area. With
respect to annual precipitation totals, the cyclonic types are responsible for 90.5% of
the total precipitation over the Greek area, while the anticyclonic types are
responsible for only 9.5%.
For the rainy period (October to March), the contribution of the anticyclonic
types to total precipitation is 8.2%, while the cyclonic types contribute 91.8% (Table
2). The cyclonic type C sw presents the highest individual percentage contribution to
total precipitation (30.8%), followed by the cyclonic type C (28.8%). In terms of
average precipitation per type of circulation the highest values (6.8mmJday) are
Tablel. Monthly relative frequency of circulation types
M Anw Ane A
Asw Ase Ae
C
Cs
Csw Cnw Cne Cse Cn
Cw
J
1.4
3.5 3.5 16
7.6
3.1
7.7
9.8 22.3
3.1 13
1.7
1
6.5
F
4.7 . 2.8 9.2
7.2
6.2
3 i 13.4 9.6 18.7 4.5 12.5
2
0.9 5.4
M
3.9
4.2 4.2 10.3 10.8
2.2 10.6 12.5 16.9
5.2
9.6
3.5
0.7 5.5
A
9.8
3.8 7.8
5.3
9.8
2
13.3 10.9 13.6
8.6
9.1
1.8
1.3 3
M
7.6
5.3 8.3 10.4 4.4
8.5 15.2 5.8 13.6
3.6 11.6 2.7
0.6 2.3
J
17.4
7.1 7.8
5.5
9.3
8.5 12.2 5.7
7.8
5.1 10.8
1.1
0.3
1.6
;
J
13
10
12.8 II
11.8
5.5 13.5
3.4
6.4
2.4
9
0.3
0.1
0.9
A
10.2
7.4 15.2 18.2 12.9
5
13.5
2.6
6.7
3.2
4.2
0
0.4 0.4
S
9.7
5.6 11.3 20.3 12.7
5.6 12.3 4
8.7
2.2
6
0.3
0.3
1.3
0
6.3 11.5 12.2 12.3
9.6
4.3 12.2 4
10.9
2.1 11
1.1
0.2 2.3
N
10.7
1.1 12.5 9.1
4.8
1.7 14.4 7.8 15
7.7
8.7
1.3
0.3 5.1
D
5.5
7.4 5.1 10.1
4.6
4.7 12.2 7.9 16.1
5
15
1.5 0.2 4.7
y
8.3
5.8 9.2 11.3
8.7
4.5 12.5
7
13.1
4.4 10
1.4
0.5 3.2