Since the territory of the Republic of Azerbaijan has a high height contrast, its relief has a complex structure. The Greater Caucasus Mountains located in the north of the territory handicap cold and humid air masses from the north to pass through to the south (Safarov et al 2022). In such cases, the fast winds move over the sea along the coast towards the Absheron peninsula because of air masses converge along the northern foothills. Due to such a synoptic regime throughout the year and the relief of the area, rainfall is distributed differently from the coastal areas to the highlands (Abdullayev 2015). The zone differs from other regions due to the characteristics of the precipitation regime. Thus, there are two maximum precipitation zones in this zone. Hence, the annual amount of precipitation in the coastal plains of the Caspian Sea is 300 mm. As the altitude increases, the amount of precipitation increases up to the upper parts of the low mountains (800-1000 metres), even though the precipitation decreases again and begins to increase again at a certain height. This situation continues to increase up to 700 mm in the parts of the highlands up to 3000 metres. However, precipitation starts to decrease above the indicated zone. In the southern foothills of those mountains, orographic conditions prevail in the formation of the precipitation regime. As evaporation accelerates in the first half of the day in the plains and lowlands, the air masses cool and produce precipitation as they rise up the foothills of the mountains. 53% of the precipitation in the area falls in the warm period of the year or in late spring, summer, and early autumn.
Table 1. Distribution of precipitation in the territory of Azerbaijan for the years from 1961 to 2020, millimetres
№
|
Station
|
Height, m
|
1891–1965
|
1961–2020
|
Winter
|
Spring
|
Summer
|
Autumn
|
Mild
|
Cold
|
1
|
Khachmaz
|
27
|
334
|
311
|
82
|
76
|
44
|
109
|
39
|
61
|
2
|
Guba
|
550
|
571
|
513
|
102
|
129
|
108
|
173
|
46
|
54
|
3
|
Khaltan
|
1104
|
-
|
516
|
90
|
152
|
117
|
157
|
52
|
48
|
4
|
Altiaghach
|
1099
|
-
|
518
|
91
|
172
|
112
|
143
|
55
|
45
|
5
|
Giriz
|
2071
|
580
|
547
|
65
|
180
|
179
|
124
|
66
|
34
|
6
|
Baku
|
2
|
247
|
272
|
94
|
62
|
19
|
98
|
30
|
70
|
7
|
Sumgait
|
-20
|
200
|
227
|
70
|
56
|
20
|
81
|
33
|
67
|
8
|
Mashtagha
|
27
|
311
|
283
|
95
|
62
|
18
|
108
|
28
|
72
|
9
|
Pirallahi
|
-25
|
198
|
196
|
64
|
51
|
13
|
68
|
32
|
68
|
10
|
Chilov
|
-17
|
197
|
153
|
52
|
42
|
9
|
51
|
33
|
67
|
11
|
Oil Rocks
|
-17
|
130
|
132
|
43
|
37
|
8
|
44
|
34
|
66
|
12
|
Alibey
|
1540
|
1394
|
1266
|
139
|
386
|
405
|
337
|
62
|
38
|
13
|
Zagatala
|
487
|
1036
|
951
|
121
|
308
|
273
|
248
|
61
|
39
|
14
|
Shaki
|
639
|
803
|
784
|
114
|
250
|
212
|
208
|
59
|
41
|
15
|
Gabala
|
679
|
1128
|
964
|
154
|
305
|
229
|
277
|
55
|
45
|
16
|
Oghuz
|
582
|
1027
|
886
|
139
|
281
|
214
|
252
|
56
|
44
|
17
|
Shamakhi
|
750
|
591
|
592
|
124
|
188
|
106
|
174
|
50
|
50
|
18
|
Maraza
|
775
|
379
|
364
|
72
|
120
|
71
|
101
|
52
|
48
|
19
|
Jeyranchol
|
419
|
-
|
309
|
44
|
102
|
93
|
69
|
63
|
37
|
20
|
Mingachevir
|
93
|
359
|
335
|
61
|
108
|
75
|
90
|
55
|
45
|
21
|
Yevlakh
|
13
|
323
|
301
|
53
|
95
|
71
|
82
|
55
|
45
|
22
|
Goychay
|
107
|
503
|
419
|
92
|
138
|
74
|
116
|
50
|
50
|
23
|
Zardab
|
-5
|
-
|
291
|
62
|
92
|
47
|
90
|
48
|
52
|
24
|
Kurdamir
|
2
|
360
|
345
|
79
|
106
|
53
|
107
|
46
|
54
|
25
|
Hajigabul
|
-7
|
254
|
241
|
64
|
78
|
26
|
72
|
44
|
56
|
26
|
Jafarkhan
|
-16
|
293
|
285
|
77
|
90
|
33
|
86
|
43
|
57
|
27
|
Imishli
|
-1
|
-
|
281
|
66
|
89
|
38
|
87
|
45
|
55
|
28
|
Beylagan
|
62
|
312
|
297
|
65
|
101
|
48
|
83
|
50
|
50
|
29
|
Bilasuvar
|
75
|
321
|
324
|
94
|
97
|
28
|
105
|
39
|
61
|
30
|
Neftchala
|
-24
|
-
|
288
|
84
|
77
|
17
|
110
|
33
|
67
|
31
|
Salyan
|
-21
|
283
|
261
|
75
|
77
|
25
|
83
|
39
|
61
|
32
|
Aghstafa
|
331
|
402
|
355
|
52
|
120
|
101
|
82
|
62
|
38
|
33
|
Shamkir
|
404
|
389
|
327
|
49
|
106
|
100
|
72
|
63
|
37
|
34
|
Ganja
|
312
|
282
|
271
|
37
|
91
|
79
|
65
|
63
|
37
|
35
|
Dashkasan
|
1655
|
622
|
635
|
85
|
216
|
201
|
133
|
66
|
34
|
36
|
Gadabay
|
1480
|
696
|
699
|
78
|
229
|
249
|
143
|
68
|
32
|
37
|
Goytapa
|
2
|
633
|
597
|
177
|
134
|
53
|
233
|
31
|
69
|
38
|
Lankaran
|
-20
|
1402
|
1183
|
293
|
194
|
104
|
591
|
25
|
75
|
39
|
Astara
|
-23
|
1398
|
1261
|
290
|
211
|
144
|
617
|
28
|
72
|
40
|
Yardimli
|
730
|
645
|
629
|
122
|
166
|
101
|
240
|
42
|
58
|
41
|
Kalvaz
|
1567
|
-
|
330
|
86
|
114
|
37
|
94
|
46
|
54
|
42
|
Sharur
|
812
|
-
|
267
|
58
|
112
|
41
|
55
|
58
|
42
|
43
|
Shahbuz
|
1205
|
444
|
343
|
79
|
146
|
52
|
66
|
58
|
42
|
44
|
Nakhchivan
|
875
|
271
|
254
|
56
|
108
|
38
|
52
|
58
|
42
|
45
|
Ordubad
|
861
|
307
|
264
|
60
|
110
|
38
|
56
|
56
|
44
|
*Source: National Hydrometeorological Service, Ministry of Ecology and the Natural Resources Republic of Azerbaijan |
Air masses moving along the northeastern foothills of the Greater Caucasus Mountains have a great influence on the Absheron Peninsula. These conditions continue throughout the year, and therefore windy weather prevails here 250 days a year (Abdullayev 2015, Safarov et al 2020 ). Cold air masses from the north, semi-arid and arid climate type and proximity to the sea are the fundamental natural factors influencing the precipitation regime of the peninsula. In recent years, the transformation of the peninsula into a large urban agglomeration has culminated in the increase in the anthropogenic influence on the formation of precipitation. Since there is no hypsometric unit in the peninsula, the precipitation difference in the area is not large. Thus, during the year, 250 mm of precipitation falls on the peninsula, and 160 mm on the surrounding islands of Pirallahi, Chilov and Neft Dashlari (Oil Rocks). About two-thirds of the precipitation in the area fall during the cold period of autumn, winter, and early spring. Therefore, a semi-desert dry steppe climate type with dry summer is typical in all parts of the aquatorium (Table 1).
There is a different precipitation regime in the listed areas on the southern slopes of the Greater Caucasus Mountains (Safarov et al 2022). Thus, as 950 mm of precipitation falls from the lowlands to higher altitudes along the slope, the amount of precipitation increases to 1400 mm up to the height of 2000–2500 metres of the middle mountains, but continues to decrease at higher altitudes. The amount of perennial precipitation decreases slightly in the southeastern part of the southern slope. So, this indicator commences from 500 mm in the foothills. The permanent glaciers, which are the essential water resources of the country, locate in the highlands. However, in recent years, global climate change has led to a sharp decrease in their areas. Generally speaking, the climatic snow line in the country starts from 3000 metres. The annual amount of precipitation in the highest parts of the Greater Caucasus Mountains is 1100 mm and falls in the form of frozen precipitation (sleet, snow and ice crystals). 57% of the region's precipitation falls in the hot season. Less precipitation is observed in late autumn, winter and partly early spring.
The Kura-Araz lowland is a plain located along the foothills of the Lesser Caucasus Mountains, starting from the southern foothills of the Greater Caucasus Mountains (Pashayev 2018). There are almost no large orographic units in the plain. This is the essential underlying reason for the distribution of the precipitation regime with small differences over a wide area. Here, the difference in precipitation between the coastal areas and the more western regions is not high. Nevertheless, temperature differences reach 1-20C. The amount of perennial precipitation on the plain is 310 mm. In this region, more precipitation falls in the western and lowland border regions of the area, and less precipitation falls in the coastal areas. In the area, more precipitation falls in the cold season (52%) than in the warm season. Thus, the main part of the annual precipitation falls in late autumn, winter and early spring. The Lesser Caucasus Mountains rise along the southwest of the Kura-Araz lowland and cause a sharp change in the climate regime of the area. Thus, the amount of precipitation in the foothills of the Murov range, in the Jeyranchol plain and along the coast of the Kura river is 300 mm. In the 2000–2500 m height zone of the Lesser Caucasus, it reaches the zone where the maximum precipitation falls in the interval of 700–800 mm. In the higher parts, the precipitation becomes less and less. The area is the zone where more thunderstorm processes occur in the country. The reason for this is the transition from the plain area to the sharp mountainous zone. 64% of the precipitation in this zone falls in the warm season. There are some differences in the amount of precipitation along the Karabakh range of the Lesser Caucasus Mountains. Thus, the amount of precipitation in the foothills of the area is 500 mm, and this indicator reaches 800 mm in the 3000 m altitude zone. Precipitation decreases gradually in the higher zone. The southern part of this mountainous province is the Zangazur-Daralayaz ridges. In the low-mountain plateaus (Sharur-Ordubad plain) at the southern foothill of these ridges, the annual rainfall is close to 300 mm. As the slope increases, the amount of precipitation reaches 900 mm in the highlands. The essential part of the precipitation in the region falls in the warm period, namely in late autumn, winter and spring. The average annual precipitation in the region is 330 mm.
The precipitation regime of the Talysh Mountains, which run parallel to the coast of the Caspian Sea, is completely different from other areas of the country (Huseynov 2020). Hence, in this zone, the amount of precipitation decreases from the coast to the highlands. Although this indicator is 1200 mm in the Lankaran plain, 250 mm of precipitation is observed at a height of 2000–2500 mm. As the area has a fertile climate regime, the subtropical climate type is typical in wider coastal areas. 66% of the annual precipitation fall in the cold period. Despite the fact that less precipitation falls in the summer months, the amount of precipitation is plentiful from late autumn to mid-spring. The amount of perennial precipitation in the region is 770 mm.
In order to visually observe the results of the research on the territory, and to detect feasible regularities, a contemporary precipitation map was compiled by the authors in ArcGIS software. The precipitation map was compiled by the classification module on the DEM (Digital Elevation Model) file (3D) taken by a stationary satellite placed in the space around the earth from a height of 30 m above the earth's surface in GIS. At this time, the pre-obtained results and DEM-type images are divided into 9 gradations by height. As a result, according to the height, the amount of precipitation was determined. Using cartographic methods, it is possible to indicate that the amount of precipitation increases from the plains to the mountains, while less precipitation falls on the coast and islands (Fig. 1).
Climate change. Changes in the amount of precipitation in the country in 1961–2020 compared to 1891–1965 are of great interest [10]. The analyses indicate that precipitation decreased in most stations during 1961–2020. The decrease in the amount of precipitation in the country is 7% in the lowland areas consisting mainly of plains, 8% in the middle highlands at a height of 1500–2000 meters, and 11% in the area of the middle highlands with a height of 1500–2000 m. In addition to this, during the research period, the central and northern parts of the Absheron peninsula had an increase in precipitation of about 11%. A slight increase (1–2%) in neft dashlari (Rock Oils), Neftchala and Bilasuvar are not statistically significant. Average annual temperature indicators in 1961–2020 also increased compared to 1881–1960 [10]. Thus, in the territory of the country, the temperature increase was equal to 0,80C in the plains surrounding the coastal plains of the Caspian Sea, Kura-Araz plain, Absheron peninsula, the plain areas covering Jeyranchol plain, 1,00C in the 500–1000 m area of the foothills of large mountain ranges, and 0,70C in all parts of the highlands.
As opposed to 1961-1990, the temperature indicators in 1991-2020 changed by 0,80C in the country. At the same time, the primary rise was 0,9-1,00C, being in the upper parts of the lowlands (500-1000 m) and in the upper parts of the middle highlands (1500-2000 m). However, in plain zones, this indicator is 0,80C. Thus, during this period, the amount of precipitation decreased by 7% in the 0-500 m altitude area where the plateau, lowland and coastal plains are located. The amount of precipitation decreased by 9% in the lowland zone of 500-1000 metres. A further decrease in precipitation is around 10% in the 1000-1500 m zone of the highlands. Although the decrease of precipitation occurred less in the higher parts of the lowlands, this fluctuation was 13% in the lower parts of the middle highlands.
During a far-reaching study of climate changes, supposed that we look at the trend of perennial average temperature and precipitation for every decade, it can be seen that the amount of precipitation across the country has a decreasing trend, and the temperature has an increasing tendency. From 1961 to 2020, the average annual temperature of the Republic of Azerbaijan has increased. During this period, more precipitation fell on the territory of the country between 1961 and 1970. During this period, as less precipitation fell from 1991 to 2020, the dry areas in the area expanded. Over the past 3 decades, precipitation has been steadily decreasing. Provided that we look at the histograms, it is feasible to observe that the amount of precipitation decreases with temperature (Figure 2).
The statistical significance of the results obtained during the research period was evaluated as well. For this purpose, temperature and precipitation series were checked according to the Student criteria.
According to the results, the temperature anomaly is not homogeneous and statistically significant at the 5% level of the Student criteria. Among the precipitation anomalies, Baku, Maraza, Chilov, Oil Rocks and Goychay stations are not homogeneous. This confirms that the obtained results are statistically significant (Table 2).
Table 2. Fluctuations of temperature and precipitation in several periods within the territory of Azerbaijan
№
|
Station
|
Height, m
|
1961–2020
|
1991–2020
|
Student, 5% (2.01)
|
t,0C
|
p, %
|
t,0C
|
p, %
|
t
|
p
|
1
|
Sumgait
|
-20
|
1,1
|
13
|
0,7
|
2
|
3,8
|
0,24
|
2
|
Baku
|
2
|
0,5
|
10
|
0,3
|
32
|
2,27
|
3,64
|
3
|
Mashtagha
|
27
|
1,0
|
-9
|
0,9
|
4
|
5,15
|
0,56
|
4
|
Pirallahi
|
-25
|
0,8
|
-1
|
0,8
|
2
|
4,52
|
-
|
5
|
Chilov
|
-17
|
0,7
|
-22
|
0,7
|
-21
|
4,07
|
2,69
|
6
|
Oil Rocks
|
-17
|
0,8
|
1
|
0,7
|
-30
|
4,42
|
3,33
|
7
|
Alat
|
-18
|
-
|
-
|
0,4
|
-16
|
-
|
-
|
8
|
Khachmaz
|
27
|
0,7
|
-7
|
0,9
|
3
|
4,97
|
0,48
|
9
|
Guba
|
550
|
1,1
|
-10
|
1,1
|
-4
|
5,53
|
0,84
|
10
|
Altiaghaj
|
1099
|
0,9
|
-
|
0,8
|
-11
|
3,49
|
2,07
|
11
|
Giriz
|
2071
|
0,6
|
-6
|
0,8
|
-13
|
3,9
|
2,75
|
12
|
Zagatala
|
487
|
0,8
|
-8
|
0,9
|
-2
|
4,9
|
0,34
|
13
|
Alibey
|
1540
|
0,7
|
-9
|
0,9
|
4
|
-
|
-
|
14
|
Shaki
|
639
|
0,6
|
-2
|
0,9
|
-6
|
4,36
|
1,37
|
15
|
Gabala
|
679
|
1,1
|
-15
|
1,2
|
-7
|
5,5
|
1,48
|
16
|
Oghuz
|
582
|
-
|
-14
|
1,1
|
-7
|
10,7
|
1,38
|
17
|
Maraza
|
775
|
0,6
|
-4
|
0,8
|
-27
|
3,99
|
4,84
|
18
|
Jeyranchol
|
419
|
-
|
-
|
0,7
|
-27
|
-
|
-
|
19
|
Mingachevir
|
93
|
0,7
|
-7
|
0,9
|
-8
|
4,34
|
1,28
|
20
|
Yevlakh
|
13
|
0,7
|
-7
|
0,8
|
-15
|
4,45
|
-
|
21
|
Tartar
|
160
|
-
|
-
|
0,9
|
-6
|
-
|
-
|
22
|
Goychay
|
107
|
0,9
|
-17
|
1,0
|
-20
|
5,44
|
3,38
|
23
|
Kurdamir
|
2
|
0,8
|
-4
|
1,0
|
-3
|
5,49
|
-
|
24
|
Zardab
|
-5
|
0,9
|
-
|
0,8
|
-9
|
4,58
|
-
|
25
|
Beylagan
|
62
|
0,7
|
-5
|
0,8
|
6
|
4,24
|
-
|
26
|
Imishli
|
-1
|
-
|
-
|
0,9
|
-8
|
-
|
-
|
27
|
Jafarkhan
|
-16
|
0,7
|
-3
|
0,7
|
-11
|
4,8
|
1,76
|
28
|
Hajigabul
|
-7
|
1,0
|
-5
|
0,8
|
-6
|
3,89
|
-
|
29
|
Bilasuvar
|
75
|
0,8
|
1
|
0,8
|
-7
|
3,87
|
-
|
30
|
Salyan
|
-21
|
-
|
-8
|
0,8
|
-17
|
-
|
-
|
31
|
Neftchala
|
-24
|
0,8
|
-
|
0,8
|
-7
|
3,62
|
-
|
32
|
Ganja
|
312
|
0,7
|
-4
|
1,0
|
-11
|
6,31
|
-
|
33
|
Aghstafa
|
331
|
1,0
|
-12
|
1,0
|
-5
|
4,4
|
0,6
|
34
|
Shamkir
|
404
|
1,3
|
-16
|
0,9
|
-12
|
5,48
|
1,44
|
35
|
Gadabay
|
1480
|
0,8
|
0
|
0,8
|
3
|
3,45
|
0,22
|
36
|
Dashkasan
|
1655
|
-
|
2
|
1,1
|
-7
|
|
-
|
37
|
Astara
|
-23
|
-
|
-10
|
0,9
|
-8
|
|
1,71
|
38
|
Lankaran
|
-20
|
0,5
|
-16
|
0,9
|
-4
|
5,22
|
0,79
|
39
|
Goytapa
|
2
|
-
|
-6
|
1,0
|
-2
|
|
-
|
40
|
Yardimli
|
730
|
-
|
-2
|
0,4
|
-9
|
1,57
|
1,94
|
41
|
Kalvaz
|
1567
|
-
|
-
|
-
|
4
|
|
-
|
42
|
Sharur
|
812
|
-
|
-
|
0,9
|
-12
|
|
-
|
43
|
Ordubad
|
861
|
2,3
|
-14
|
0,8
|
-9
|
3,44
|
1,4
|
44
|
Nakhchivan
|
875
|
0,0
|
-6
|
0,8
|
-1
|
3,36
|
-
|
45
|
Shahbuz
|
1205
|
0,5
|
-23
|
0,3
|
-23
|
1,23
|
-
|
*Source: National Hydrometeorological Service, Ministry of Ecology and the Natural Resources Republic of Azerbaijan |