62
5.2 Change in temperature pattern
5.2.1 Chiang Rai
The monthly variation of Tmax, Tmin and mean T during hot weather season March to May and cold weather season Dec to Feb is shown in
Figure 5.19
and
Figure 5.20
respectively for Chiang Rai.
Figure 5.19. Monthly mean temperature variation during hot weather season March to May from 1980 to 2008 over Chiang Rai. a Maximum temperature, b Minimum Temperature and c Mean
Temperature. The linear trend line for April is plotted Source: Thailand Meteorological Dept. and Analysis
63
Figure 5.20. Monthly mean temperature variation during cold weather season December to February from 1980 to 2008 over Chiang Rai. a Maximum temperature, b Minimum Temperature and c Mean
Temperature. The linear trend line for December is plotted Source: Thailand Meteorological Dept. and Analysis
64 It is seen from Figure 5.19 and Figure 5.20 that the maximum temperature in summer March
to May is decreasing but the minimum temperature in summer is increasing. On the other hand during the winter season all the three temperatures Tmax, Tmin and mean T are
indicating increasing trend. Thus, summer nights and winters are becoming more warmer and a clear indication of climate change in recent time. The same pattern is also reflected with
highest Tmax in summer April and lowest Tmin in winter Dec as shown in Figure 5.21.
15 20
25 30
35 40
45
198 198
2 198
4 198
6 198
8 199
199 2
199 4
199 6
199 8
200 200
2 200
4 200
6 200
8
Year E
x tre
m e T
m ax
A p
r
5 10
15
E xt
rem e T
m in
D ec
Apr Ext. Tmax Dec Ext. Tmin
Linear Apr Ext. Tmax Linear Dec Ext. Tmin
Figure 5.21. Monthly mean extreme maximum temperature highest Tmax variation during April and monthly mean extreme minimum temperature lowest Tmin during December over Chiang Rai Source:
Thailand Meteorological Dept. and Analysis
5.2.2 Udon Thani
The trend of Tmax, Tmin and mean T during summer and winter is shown in Figure 5.22 and Figure 5.23 respectively. The trend in Tmax during summmer Mar-May and Tmin during
winter Dec-Feb shows increasing trend over Udan Thani as shown in Figure 5.22a and Figure 5.23b respectively. It is also seen from Figure 5.23a and Figure 5.23c that the Tmax
during winter and also the mean temperature during winter is increasing. Thus, summer days and winters days nights are becoming more warmer and a clear indication of climate
change in recent time and have the potential of increasing heat wave frequency. The same pattern is also reflected with highest Tmax in summer April and lowest Tmin in winter
Dec
65
Figure 5.22. Monthly mean temperature variation during hot weather season March to May from 1980 to 2008 over Udon Thani. a Maximum temperature, b Minimum Temperature and c Mean
Temperature. The linear trend line for April is plotted Source: Thailand Meteorological Dept. and Analysis
66
Figure 5.23. Monthly mean temperature variation during cold weather season December to February from 1980 to 2008 over Udon Thani. a Maximum temperature, b Minimum Temperature and c
Mean Temperature. The linear trend line for December is plotted Source: Thailand Meteorological Dept. and Analysis
67
5.2.3 Hat Yai