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2003, the overall trend (F
2
Trend, 1
) is significant at D = 0.05 level (critical
F
2
0.995, 1
= 3.84). This result indicates an overall drying trend of monsoon
rainfall (
Z
= - 0.38) without any significant spatial and seasonal heterogeneity.
For the second time frame (1960-2003), however, the seasonal heterogeneity
(F
2
Season,
p
-1
) is found to be significant at D = 0.05 level (critical F
2
0.995, 3
= 7.81). Based on the results of tests for heterogeneity among the seasons, the
June and September months of the monsoon season are found to be significantly
heterogeneous with F
2
-values of 20.22 and 7.85, respectively. It can be inferred
that the June month exhibited a significant wetting trend (
Z
s
=
1.24), and the
September month exhibited a significant drying trend (
Z
s
=
- 0.78) for the
second time frame. Higher frequency of drying trend in monsoon rainfall time
series of Orissa in the present study, and the future occurrence of extreme
weather events with probable severe droughts reported by Ghosh and Majumdar
(2007) necessitates a more detailed future research.
11.4.3 Trends in Temperature Time Series
The basic statistics of mean monthly maximum temperature (
T
max
) and mean
monthly minimum temperature (
T
min
) for 16 stations of the study area are
presented in Table 11.3. The standard deviation values of the temperatures are
relatively lesser for coastal belt (Balasore, Chandbali, Paradeep, Cuttack, Puri,
Bhubaneswar, Gopalpur) compared to the non-coastal region, which indicates
a stable
T
max
and
T
min
in coastal belt. Although the coastal region is densely
populated, the mean
T
max
of the non-coastal region is more than that of the
coastal region. However, the average
T
min
of the non-coastal region is less
than that of the coastal region. Most of the stations exhibit positive skewness
for
T
max
and negative skewness (
S
k
) for
T
min
. This indicates that unusually
high and low temperatures influenced the distribution of
T
max
and
T
min
,
respectively. The topographic features, location of the station from the coast,
and the anthropogenic interventions are the plausible factors for the spatial
difference of the temperature pattern. The coal-based industrial regions such
as ANG, JRG, TTG and SNG show higher temperatures as obvious from the
location parameters.
Figure 11.4 shows the cumulative frequency distribution of MK and SR
trend test results of 192 temperature time series (12 seasons for each of the 16
stations) for the
T
max
and
T
min
, respectively. The cumulative frequency
distribution of
T
max
shown in Fig. 11.4(a) exhibits a pronounced warming
trend as 99% of the season-stations show positive trends for both the MK and
SR trend test. However, the cumulative frequency distribution of
T
min
experiences a cooling trend as 93% and 94% of the season-stations show
negative trends for the MK and SR trend test, respectively [Fig. 11.4(b
)
].
Higher cases of positive trends of the MTR [Fig. 11.4(c)] are also observed,
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