Spatial and Temporal Variations in Precipitation and Aridity Index Series of Turkey
203
In order to assess the nature and magnitude of the observed persistence in
variations of precipitation anomaly series, Tiirke~ (1998a) computed the lag-one serial
correlation (L-ISC) coefficient, r 1 , for 91 stations and rainfall regions of Turkey.
However, only station-based results are given here. The L-I SC is positive at most of
the stations in winter, except at the stations of the BLS region. There is a significant
persistence in winter precipitation variations from year to year at 31 stations, 8 of
Table 1. Number of the stations indicating a significant trend and/or serial correlation in the
normalized precipitation series at the 5 or I per cent level, according to the Mann-Kendall (M-K)
and lag-one serial correlation (L-I SC) tests (Ttirke~, 1998a). (+): upward trend from the M-Ktest
and positive correlation coefficient from the L-I SC test; (- ): downward trend from the M-K test
and negative correlation coefficient from the L-I SC test.
Winter
Spring
Summer
Autumn
Annual
- - - - - -
Rainfall
M-K
L-ISC
M-K
L-ISC
M-K
L-ISC
L-ISC
M-K
L-ISC
Region
+
-
+
+
-
-
+
+ -
+
-+
-
+
BLS
1
I
2
1
I
MRT
6
I
I
1
2
MED
8
8
I
4
I
I 2
1
1
6
4
I
- -t-----~
CMED I I 3
5
I
4
4
I I ! I
I I 2
MEDT
I
I
,
I
I
2
I
CCAN
I
I
6
6
2
I I I
2 4 !
I
6
2
ill
i
!
CEAN
1 i
5
1
I
I I I
Total
16
31
4
18
7
9
4
17
17
which are in the stations with winter-maximum Mediterranean type rainfall regime
(Table I). Annual precipitation series of 17 stations also depict a significant positive
correlation. However, the L-I SCs are negative at almost all stations in spring, 18 of
which are statistically significant. This statistic indicates that spring precipitation
series contains a high-frequency oscillation. Both negative and positive L-ISCs are
found for summer rainfall series, in which only 9 of them differ significantly from
zero. Majority of autumn precipitation series seems to be statistically random against
the serial correlation.
A simple Markov type persistence is found approximately in winter precipitation
anomaly series of II stations, when the exponential relationships are that of r 2 '" r l
2
and r3 '" r l 3 are considered. The Markov persistence is the dominant characteristic
particularly in those winter precipitation series of the stations, which exist over the
colder and more continental north-eastern part of the CEAN region. Desired
203
In order to assess the nature and magnitude of the observed persistence in
variations of precipitation anomaly series, Tiirke~ (1998a) computed the lag-one serial
correlation (L-ISC) coefficient, r 1 , for 91 stations and rainfall regions of Turkey.
However, only station-based results are given here. The L-I SC is positive at most of
the stations in winter, except at the stations of the BLS region. There is a significant
persistence in winter precipitation variations from year to year at 31 stations, 8 of
Table 1. Number of the stations indicating a significant trend and/or serial correlation in the
normalized precipitation series at the 5 or I per cent level, according to the Mann-Kendall (M-K)
and lag-one serial correlation (L-I SC) tests (Ttirke~, 1998a). (+): upward trend from the M-Ktest
and positive correlation coefficient from the L-I SC test; (- ): downward trend from the M-K test
and negative correlation coefficient from the L-I SC test.
Winter
Spring
Summer
Autumn
Annual
- - - - - -
Rainfall
M-K
L-ISC
M-K
L-ISC
M-K
L-ISC
L-ISC
M-K
L-ISC
Region
+
-
+
+
-
-
+
+ -
+
-+
-
+
BLS
1
I
2
1
I
MRT
6
I
I
1
2
MED
8
8
I
4
I
I 2
1
1
6
4
I
- -t-----~
CMED I I 3
5
I
4
4
I I ! I
I I 2
MEDT
I
I
,
I
I
2
I
CCAN
I
I
6
6
2
I I I
2 4 !
I
6
2
ill
i
!
CEAN
1 i
5
1
I
I I I
Total
16
31
4
18
7
9
4
17
17
which are in the stations with winter-maximum Mediterranean type rainfall regime
(Table I). Annual precipitation series of 17 stations also depict a significant positive
correlation. However, the L-I SCs are negative at almost all stations in spring, 18 of
which are statistically significant. This statistic indicates that spring precipitation
series contains a high-frequency oscillation. Both negative and positive L-ISCs are
found for summer rainfall series, in which only 9 of them differ significantly from
zero. Majority of autumn precipitation series seems to be statistically random against
the serial correlation.
A simple Markov type persistence is found approximately in winter precipitation
anomaly series of II stations, when the exponential relationships are that of r 2 '" r l
2
and r3 '" r l 3 are considered. The Markov persistence is the dominant characteristic
particularly in those winter precipitation series of the stations, which exist over the
colder and more continental north-eastern part of the CEAN region. Desired