ISPRS Archives XXXVIII-8/W3 Workshop Proceedings: Impact of Climate Change on Agriculture
CLIMATE VARIABILITY OVER GUJARAT, INDIA
Kamaljit Ray∗, Manorama Mohanty and J.R. Chincholikar
Meteorological Centre, India Meteorological Department, Ahmedabad–380 012, India
KEYWORDS: Climate Variability, Temperature, Rainfall, Extreme Events, Gujarat
ABSTRACT:
Climate variability and occurrence of extreme weather events are the major concerns linked to global warming. In this paper past 40 years
data of all IMD observatories in Gujarat state of India has been analyzed. Moving averages of Maximum Temperature during summer
season and minimum temperature during winter season have been analysed and a significant increasing trend has been observed. Similarly
for rainfall, some significant results have been obtained. There was a significant trend in case of various extreme weather events like cold
wave conditions, heat wave conditions and heavy rainfall instances. In addition to above IMD’s gridded data for Gujarat state for
Maximum, Minimum and Mean temperature showed a significant steady increasing trend in the past 40 years.
conditions, cold wave conditions and heavy rainfall instances in the
past 40 years have also been studied decade wise.
1. INTRODUCTION
Meteorological data compiled over the past century suggests that
the earth is warming, but there are significant differences at
regional level (Rupa Kumar, 2003). Most of the studies during the
last four decades have clearly pointed out that the monsoon rainfall
is trend less, particularly on an all India Scale (Parthasarthy, 1984),
but Rupa Kumar et al (1992) have shown regional monsoon
rainfall trends in the past century. Rupa Kumar et al. (1994) also
showed that there was an asymmetry in the temperature trends in
terms of daytime and night time temperatures over India. The
observed warming was predominantly due to an increase in
maximum temperature, while the minimum temperature remained
practically constant during the past century. In this study the results
obtained for Gujarat State showed a significant increase in
minimum temperature during winter season as compared to day
temperatures in summer. The increase in night temperatures was
found to be significant enough to have lowered the cold wave
conditions during winters for most of the districts. Dhorde et al
(2009) also found out that some of the metropolitan cities in India
recorded significant increase in minimum temperature during
winter. Hingane et al. (1895) had prepared an all-India mean series
of seasonal and annual surface air temperature for a long term trend
studies, using data for 1901-82. The analysis indicates a significant
warming of 0.4°C per hundred years in mean annual temperatures
of the country as a whole. There are large areas showing significant
warming trends along the west coast and adjoining areas. Another
study by Srivastava et al. (1992) on decadal trends of temperature
over India also confirms the increasing temperature trends in India.
They have shown that 1901-1940 was the cooler regime whereas
there was a warmer regime from the end of 5th decade (1940-1950)
to (1980—1990).In this paper ,attempt has been made to study the
variability in various temperature parameters for various
observatories of Gujarat and compare the results with the gridded
temperature prepared by IMD fro 1965 to 2005. Seasonal rainfall
data has also been analyzed during the above period for various
observatories. Extreme weather conditions like heat wave
2. DATA AND METHODOLOGY
2.1 Study Area
Gujarat is in the extreme West of India (Figure 1). It has tropical
climate, namely sub humid, arid and semi arid spread over different
region of the state. North Gujarat region comprising of Kutch, part
of Banaskantha, Mehsana and North Western part of Saurashtra
have arid climate while the South Gujarat sub humid climate and in
the rest of the state, semi arid climate. Temperature varies from 6 to
450Celsius.Annual rainfall varies from 250 mm in the North West
and to more than1500 mm in South Gujarat. Out of 225 talukas, 56
talukas are drought prone.
Figure 1. Map of Gujarat State of India
∗
kamaljit_ray@rediffmail.com
38
ISPRS Archives XXXVIII-8/W3 Workshop Proceedings: Impact of Climate Change on Agriculture
2.2 Data Used
Moving average of mean minimum temperature during
winter months of Ahmedabad
Daily Maximum temperature, daily minimum temperature and
rainfall data for 18 full time and part time IMD observatories of
Gujarat state of India, for the period 1965-2008 has been utilized
for the analysis. Gridded data for Gujarat state, prepared by IMD
for the period 1965-2005 has also been utilized.
14.8
14.6
14.4
14.2
DEG
2.3 Analysis
14
13.8
13.6
Thirty years and ten years moving normals at one-year gap have
been calculated for all parameters in order obtain the climatological
rise in the past forty years. Extreme Weather conditions have been
computed season wise using the following definitions.
¾
Heat wave in summer: Monthly Average of Maximum
Temperature (40 years) +5ºC
¾
Cold wave in winter: Monthly Average of Minimum
Temperature (40 Years) -5ºC
19
69
19 -19
71 7 8
19 -19
73 8 0
19 -19
75 8 2
19 -19
77 8 4
19 -19
79 8 6
19 -19
81 8 8
19 -19
83 9 0
19 -19
85 9 2
19 -19
87 9 4
19 -19
89 9 6
19 -19
91 9 8
19 -20
93 0 0
19 -20
95 0 2
19 -20
97 0 4
19 -20
99 0 6
-2
00
8
13.4
YEARS
Moving averages of mean minimum temperature during winter
season of Baroda
15.2
15
¾
Heavy Rainfall: >70 mm
14.8
14.6
DEG
3. RESULT AND DISCUSSIONS
14.4
14.2
3.1 Minimum Temperature
14
13.8
30 years moving averages of mean minimum temperature during
winter season (November, December, January, February) have
been prepared for the various IMD observatories of Gujarat state.
Most of the observatories showed a steady increasing trend in mean
minimum temperature during winter season.. The normals were
seen to increase by 1.2°C in Bhuj, followed by 0.7°C in Veraval
and Bhavnagar, 0.6 °C in Naliya and 0.5°C in Rajkot (Fig 2). The
rise of temperature normals was steady and highly linear.The
averages were more or less stable in, Okha and Ahmedabad and
decrease of 0.3 °C was noticed in Deesa. The instances of cold
wave were seen to be highest in Bhuj in the past 40 years (412) i.e.
on an average 10 per year (Table 1). The maximum number of cold
waves was recorded in the month of February for all places and 0.2°C was the lowest temperature in the state recorded in Bhuj on
28th Jan 1977. The decadal instances of cold wave conditions in
Bhuj showed a considerable decrease of cold wave conditions in
the decade 1999-2008. As compared to earlier decades having
more than 100 cold waves conditions, only 10 cold waves were
recorded in the last decade. Similarly the cold wave instances over
Veraval have decreased to less then 10 in the decade 1999-2008 as
compared to earlier decades, similarly for Bhavnagar, Naliya,
Rajkot and Baroda. In general, except for Ahmedabad, Surat and
Deesa, the cold wave conditions have decreased considerably in
various districts of Gujarat, thus indicating an increase in night
temperatures during winters over the state. The IMD gridded data
of minimum temperature over Gujarat with 1x1 grid intervals have
also been analyzed for the period 1969-2005 and the results
showed an increasing trend in the past 40 Years (Fig 3). The
normals had increased by 0.107ºC. The trend again showed a
steady increase over the years. In case of moving averages of 10
years the increase was 0.25 ºC. Analysis was performed for north
and South Gujarat region separately but not much difference was
obtained in case of gridded data. In general the temperature rise
was found to be highest in Saurashtra and Kutch as compared to
North and central Gujarat region.
19
69
19 -19
71 78
19 -19
73 80
19 -19
75 82
19 -19
77 84
19 -19
79 86
19 -19
81 88
19 -19
83 90
19 -19
85 92
19 -19
87 94
19 -19
89 96
19 -19
91 98
19 -20
93 00
19 -20
95 02
19 -20
97 04
-2
00
6
13.6
YEARS
Moving averages of mean minimum temperature during
winter months of Deesa
10 years
30 years
13
Linear (10 years)
Linear (30 years)
12.8
12.6
12.4
DEG
12.2
12
11.8
11.6
11.4
11.2
19
69
19 197
71 8
19 198
73 0
19 198
75 2
19 198
77 4
19 198
79 6
19 198
81 8
19 199
83 0
19 19
85 92
-1
19
9
87 94
19 199
89 6
19 199
91 8
-2
19
0
93 00
19 200
95 2
19 200
97 4
19 200
99 6
-2
00
8
11
YEARS
Moving Averages of mean minimum temperature during winter season
of Bhavnagar
16.5
DEG
16
15.5
15
14.5
19
69
19 -1 9
71 78
19 -1 9
73 80
19 -1 9
75 82
19 -1 9
77 84
19 -1 9
79 86
19 -1 9
81 88
19 -1 9
83 90
19 -1 9
85 92
19 -1 9
87 94
19 -1 9
89 96
19 -1 9
91 98
19 -2 0
93 00
19 -2 0
95 02
19 -2 0
97 04
19 -2 0
99 06
-2
00
8
14
YEARS
39
ISPRS Archives XXXVIII-8/W3 Workshop Proceedings: Impact of Climate Change on Agriculture
in temperature ranges from 0.2 to 0.4 °C for Saurashtra, where as
for Gujarat region they were more or less stable. The heat wave
conditions have increased in the last decade over most of the
districts as shown in the Table 2, except for, Ahmedabad, Bhuj and
Okha. The number of heat waves recorded along the coastal
districts of the state was highest in the last decade as compared to
earlier three decades. Veraval recorded 72 cold waves in the last
decade, amounting to an average of 7 cold wave conditions each
year. Similarly Naliya recorded 52 heat wave conditions in the last
decade with an average of 5 heat waves each year.
Moving averages of mean minimum temperature during
winter season of Bhuj
16
15
DEG
14
13
12
R2 = 0.4563
R2 = 0.9751
11
19
69
19 -1
71 97
19 -1 8
73 98
19 -1 0
75 98
19 -19 2
77 8
19 -1 4
79 98
19 -19 6
81 8
19 -1 8
83 99
19 -19 0
85 9
19 -1 2
87 99
19 -1 4
89 99
19 -1 6
91 99
19 -20 8
93 0
19 -20 0
95 0
19 -2 2
97 00
19 -2 4
99 00
-2 6
00
8
10
Moving averages of mean maximum temperature during summer season
for Bhuj
YEARS
Figure 2. Station Wise Moving Averages of 10 and 30-year
Period for Mean Minimum Temperature During Winter Months
38.6
10 years
38.4
30 years
38.2
1979198919991988
1998
2008
72
35
46
47
22
6
32
15
47
111
144
10
33
10
21
43
21
4
33
19
27
3
4
2
25
0
62
50
8
5
of Cold Wave Conditions in
37.8
37.6
37.4
37.2
19
69
19 -1 9
71 78
19 1 98
73 0
19 -1 9
75 82
19 -1 9
77 84
19 -1 9
79 86
19 -1 9
81 88
19 1 99
83 0
19 -1 9
85 92
19 1 99
87 4
19 -1 9
89 96
19 -1 9
91 98
19 -2 0
93 00
19 -2 0
95 02
19 -2 0
97 04
19 -2 0
99 06
-2
00
8
37
YEARS
19
69
Tmin
10 years
Moving averages of annual mean minimum
temperature of Gujarat
30 years
20.6
2
20.5
R = 0.7235
20.4 R2 = 0.9407
20.3
20.2
20.1
20
19 - 1 9
71 78
19 - 1 9
73 80
19 - 1 9
75 82
19 - 1 9
77 84
19 - 1 9
79 86
19 - 1 9
81 88
19 - 1 9
83 90
19 - 1 9
85 92
19 - 1 9
87 94
19 - 1 9
89 96
19 - 1 9
91 98
19 - 2 0
93 00
19 - 2 0
95 02
19 - 2 0
97 04
19 - 2 0
99 06
-2
00
8
Moving averages of mean maximum temperature during summer months of
Rajkot
39
10
years
38.8
38.6
30 years
38.4
38.2
38
37.8
37.6
37.4
37.2
37
36.8
DEG
19691978
Ahmedabad
52
Baroda
67
Deesa
60
Bhuj
146
Rajkot
95
Veraval
54
Naliya
107
Okha
4
Surat
48
Bhavnagar
116
Table 1: Decadal Frequency
Selected Stations
DEG
38
Station\Period
YEARS
78 81 84 87 90 93 96 99 02 05
19 -19 -19 -19 -19 -19 -19 -19 -20 -20
69 72 7 5 78 81 84 87 90 93 96
19 1 9 19 19 1 9 19 19 19 19 19
time period
Moving averages of mean maximum temperature during summer months of
Veraval
33
10 years
Figure 3. Variation of Annual Mean Minimum Temperature
Over Gujarat State Using IMD grid Data
DE G
32.5
3.2 Maximum Temperature
30 years
32
31.5
30 years moving averages of mean maximum temperature during
summer season (March, April, and May) were prepared for various
observatories placed in Gujarat. The mean maximum temperature
in summer was found to have increased over Naliya, Okha,
Veraval and Rajkot and decreased by 1°C over Bhuj (Fig 4). The
mean maximum temperatures have remained more or less stable in
Deesa, Baroda, Ahmedabad and Surat in the past 40 years. The rise
31
19
69
19 1 9 7
71 8
19 1 9 8
73 0
19 1 9 8
75 2
19 1 9 8
77 4
19 1 9 8
79 6
19 1 9 8
81 8
19 1 9 9
83 0
-1
19 9 9
85 2
19 1 9 9
87 4
19 1 9 9
89 6
-1
19 9 9
91 8
19 2 0 0
93 0
19 2 0 0
95 2
19 2 0 0
97 4
19 2 0 0
99 6
-2
00
8
30.5
YEARS
40
ISPRS Archives XXXVIII-8/W3 Workshop Proceedings: Impact of Climate Change on Agriculture
Moving averages for mean maximum temperature
of Gujarat
39.6
1 0 y e ar s
39.4
30 y ears
39.2
39
30 years
33.1
33
32.9
32.8 R2 = 0.9544
32.7
32.6
32.5
32.4
32.3
Tmax
DEG
M o v in g av e rag e o f me an maximu m te mp e ratu re d u rin g
su mme r mo n th s o f Ah me d ab ad
38.8
38.6
38.4
2
R = 0.7132
10 years
Period
19
69
19 -1 9
72 78
19 -1 9
75 81
19 -1 9
78 84
19 -1 9
81 87
19 -1 9
84 90
19 -1 9
87 93
19 -1 9
90 96
19 -1 9
93 99
19 -2 0
96 02
-2
00
5
8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8
9 7 98 98 98 98 98 9 9 9 9 99 9 9 99 00 00 0 0 0 0 0 0
-1 - 1 - 1 -1 -1 -1 -1 -1 - 1 -1 -1 -2 -2 -2 -2 -2
69 9 7 1 9 7 3 9 75 9 77 9 79 9 81 9 83 9 8 5 9 8 7 9 89 9 91 9 9 3 9 95 9 97 9 9 9
9
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
YE A R S
Moving Averages of mean Maximum Temperature during Summer months of Naliya
10 years
30 years
Li
(10
35
)
34.8
34.6
DEG
34.4
R2 = 0.5491
R2 = 0.8631
34.2
34
33.8
33.6
33.4
19
69
19 197
71 8
19 198
73 0
-1
19 98
75 2
19 198
77 4
19 198
79 6
-1
19 98
81 8
19 199
83 0
19 199
85 2
-1
19 99
87 4
19 199
89 6
19 199
91 8
-2
19 00
93 0
19 200
95 2
19 200
97 4
19 200
99 6
-2
00
8
33.2
YEARS
Figures 4. Station Wise Moving Averages of 10 and 30-year
Period for Mean Maximum Temperature During Summer
Months
Figure 5. Variation of Annual Mean Maximum and Mean
Temperature over Gujarat State Using IMD Gridded Data
3.3 Rainfall
The heat waves and cold waves had decreased considerably over
Bhuj in the last decade indicating a general rise in night
temperatures and fall in day temperatures. The IMD gridded data
of maximum temperature over Gujarat with 1x1 grid intervals have
also been analyzed for the period 1969-2005 and the results
showed an increasing trend in the past 40 Years (Fig 5). The annual
mean maximum temperature normal were found to have increased
by 0.11°C.The rise was again very steady and highly linear. The 10
years moving averages showed an increase of 0.5°C in the past 40
years. The increase has been stable and significant for both
maximum and minimum temperature. The analysis was carried out
for North Gujarat and South Gujarat region separately and same
trend was observed, with higher increase in Saurashtra and South
Gujarat region as compared to the other regions. The rise in
normals of annual mean temperatures over Gujarat state was
0.07ºC and 10 years averages showed a rise of 0.3ºC(fig 5).
19791988
4
12
5
27
1
52
35
1
43
19891998
17
9
10
42
14
34
30
2
25
19992008
13
28
29
16
22
72
52
1
32
Moving Averages for average seasonal rainfall for
Bhuj
Rainfall in mm
Ahmedabad
Baroda
Deesa
Bhuj
Rajkot
Veraval
Naliya
Okha
Surat
19691978
20
16
20
31
9
53
17
5
54
340
330
320
310
300
290
280
270
19
69
-1
19 99
70 9
-2
19 00
71 0
-2
19 00
72 1
-2
19 00
73 2
-2
19 00
74 3
-2
19 00
75 4
-2
19 00
76 5
-2
19 00
77 6
-2
19 00
78 7
-2
19 00
79 8
-2
00
9
Station\Period
Seasonal rainfall for all observatories for the 40 years period (19692008) was analyzed. 30 years moving averages of seasonal rainfall
indicate an increase in rainfall normals for all the stations.
Maximum rise of seasonal rainfall normals was found to be in
Saurashtra (Bhavnagar,60mm) and South Gujarat region (Surat
,100mm) (Fig 6). Year to year variation was found to be highly
variable for all stations and standard deviations of seasonal rainfall
over the past 40 years ranged from 250mm to 500mm. Therefore
the analysis was done for 30 years moving averages only .The
seasonal rainfall normals varied from 300mm in Bhuj to 1100 mm
in Surat,.Inspite of high year to year variation and high interstate
variation the seasonal rainfall normals showed a increasing trend.
The heavy rainfall events (>70mm) were found to have increased
in all stations in the last decade as compared to earlier decades
(Table 3). Surat recoded 106 heavy rainfall days in the past decade.
In Bhuj , Ahmedabad and Naliya the events had remained more or
less same.
Table 2: Decadal Frequency of Heat Wave Conditions in
Selected Stations
Time period
41
ISPRS Archives XXXVIII-8/W3 Workshop Proceedings: Impact of Climate Change on Agriculture
CONCLUSION
Moving Averages of Seasonal Rainfall for
Bhavnagar
¾
The gridded 30 years moving averages of mean maximum
temperature over Gujarat state indicate an increase by
0.11°C in past 40 years (1969-2005). The station wise
analysis (1969-2008) further indicates that the increase is
more over Saurashtra region as compared to that of the
remaining parts.
¾
30 years of moving averages of the gridded mean
minimum temperature over Gujarat state indicate an
increasing trend with a increase of 0.107ºC in the past 40
years (1969-2005). The station wise analysis further
indicates higher increase in night temperature over
Saurashtra and Kutch as compared to other parts of the
state.
¾
The gridded 30 years moving averages of mean
temperature over Gujarat state indicate an increase by
0.07°C in past 40 years (1969-2005). The station wise
analysis (1969-2008) further indicates that the increase is
more over Coastal Saurashtra region as compared to that
of the remaining parts.
¾
Cold wave conditions have decreased considerably over
the past decade indicating an increase in night temperature.
As compared to an average of 103 cold wave conditions in
Saurashtra and Kutch region in the decade 1969-1978 ,the
average cold wave conditions recorded in the past decade
(1999-2008) were only 13. The rise in normal mean
minimum temperature during winter season was found to
0.3ºC as compared to the annual mean minimum rise of
0.107ºC. The maximum rise in minimum temperature was
found to be in winter months in comparison to other
months of the year.
¾
Heat wave conditions have increased in southern part of
the Gujarat, while they have decreased in northern
parts.Rise was appreciable along Coastal stations of
Saurashtra.
¾
Mean seasonal rainfall has increased over Saurashtra and
south Gujarat region (along west coast) and has remained
more or less same over north Gujarat region and adjoining
Kutch.
¾
Rainfall extremes have also increased in the past decade
for south Gujarat region and Saurashtra. The difference is
not much in the past 4 decades for north Gujarat and
Kutch.
19
69
19 -19
70 99
19 -20
71 00
19 -20
72 01
19 -20
73 02
19 -20
74 03
19 -20
75 04
19 -20
76 05
19 -20
77 06
19 -20
78 07
19 -20
79 08
-2
00
9
Rainfall in mm
610
600
590
580
570
560
550
540
530
520
Time period
790
780
770
760
750
740
730
720
710
700
19
69
-1
19 999
70
-2
19 000
71
-2
19 001
72
-2
19 002
73
-2
19 003
74
-2
19 004
75
-2
19 005
76
-2
19 006
77
-2
19 007
78
-2
19 008
79
-2
00
9
Rainfall in mm
Moving Averages of Seasonal Rainfall for Ahmedabad
Time Period
Moving Averages for average seasonal Rainfall of Surat
09
08
-2
0
19
79
-2
0
78
19
19
77
-2
0
07
06
05
-2
0
76
19
19
75
-2
0
74
19
73
-2
0
04
03
02
-2
0
01
-2
0
72
19
71
-2
0
19
70
19
19
19
69
-1
9
-2
0
99
00
1160
1140
1120
1100
1080
1060
1040
1020
1000
Figure 6. Station Wise Moving Averages of 30 Year Period for
Seasonal Monsoon Rainfall
Station\Period
Ahmedabad
Baroda
Deesa
Bhuj
Rajkot
Veraval
Naliya
Porbandar
Surat
Bhavnagar
19691978
42
21
13
5
13
21
10
16
92
13
19791988
39
14
7
10
18
27
13
25
88
10
19891998
50
17
21
12
15
26
10
19
39
13
19992008
50
34
25
10
21
33
11
22
101
17
From the above result it is clear that majority of the trends, both
seasonal as well as annual showed increasing tendency in
temperature and rainfall during past 40 years. The annual mean
temperature of Gujarat as a whole has also increased. The rise in
minimum temperature during winter season was found to be higher
than the rise in maximum temperature in summer season.
Table 3: Decadal Frequency of Heavy Rainfall Events in
Selected Stations
42
ISPRS Archives XXXVIII-8/W3 Workshop Proceedings: Impact of Climate Change on Agriculture
Rupa Kumar, K., Krishna Kumar, K.,Prasanna, V., Kamala, K.,
Despand N.R., Parmardhan, S.K., Pant, G.B., 2003, Future
climate Scenarios, In Climate change of India. Vulnerability
Assessment and Adaptation. (Ed: Shukla, P.R., Sharma,
Subodh, K. et al.)
ACKNOWLEDGEMENT
The work was carried out at Met centre, Ahmedabad. The authors
are grateful to DDGM, RMC Mumbai and DGM, IMD for all the
facilities and data provided for the study.
Rupa Kumar, K., Pant, G.B., Parth Sarthy, B., and Sontakke,
N.A., 1992. Spatial and sub seasonal patterns of the long term
trends of Indian summer monsoon rainfall. International Journal
of Climatology, 12, 257–268.
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