Title Page
Contents
ABSTRACT 12
Ⅰ. Introduction 15
1.1. Study Purpose and Need 15
1.2. Literature Review 17
1.2.1. Changes in Regional Precipitation Distribution 18
1.2.2. Changes in Precipitation Trends 20
1.2.3. Changes in Extreme Precipitation Trends 21
1.2.4. Relationships of Atmospheric Circulation with Precipitation and Extreme Precipitation 23
Ⅱ. Data and Methodology 27
2.1. Data and Study Region 27
2.2. Methodology 35
Ⅲ. Changes in Seasonal Precipitation 39
3.1. Changes in Mean Seasonal Precipitation between 1961-1990 and 1991-2020 39
3.2. Changes in Seasonal Precipitation 41
Ⅳ. Changes in Seasonal Extreme Precipitation 46
4.1. Changes in the Frequency of Seasonal Extreme Precipitation 46
4.2. Changes in the Intensity of Seasonal Extreme Precipitation 56
Ⅴ. Connections of Atmospheric Circulations with Seasonal and Extreme Precipitation 64
5.1 Impacts of Relationship between Atmospheric Indices and Seasonal Precipitation 64
5.2. Impacts of Relationship between Atmospheric Indices and Seasonal Extreme Precipitation 76
Ⅵ. Discussion 87
Ⅶ. Summary and Conclusions 96
References 99
국문초록 117
Table 2.1. Acronyms and descriptions of the atmospheric indices used in this study. 34
Table 2.2. Acronyms and Definitions of the five precipitation indices used in this study. 37
Table 3.1. Changing trends of seasonal precipitation over Pakistan between 1961-1990 and 1991-2020. 45
Table 4.1. Changing trends of consecutive wet days during pre-monsoon, summer monsoon, post-monsoon, and winter monsoon between 1961-1990... 48
Table 4.2. Changing trends of very wet days during pre-monsoon, summer monsoon, post-monsoon, and winter monsoon between 1961-1990 and 1991-2020. 54
Table 4.3. Changing trends of extremely wet days during pre-monsoon, summer monsoon, post-monsoon, and winter monsoon between 1961-1990... 55
Table 4.4. Changing trends of total precipitation on wet days during pre-monsoon, summer monsoon, post-monsoon, and winter monsoon between... 58
Table 4.5. Changing trends of simple daily intensity index during pre-monsoon, summer monsoon, post-monsoon, and winter monsoon between... 61
Table 5.1. Relationship between atmospheric indices and extreme precipitation of different precipitation regions during the pre-monsoon season from 1961-1990. 80
Table 5.2. Relationship between atmospheric indices and extreme precipitation of different precipitation regions during the pre-monsoon season from 1991-2020. 80
Table 5.3. Relationship between atmospheric indices and extreme precipitation of different precipitation regions during the summer monsoon season from 1961-1990. 81
Table 5.4. Relationship between atmospheric indices and extreme precipitation of different precipitation regions during the summer monsoon season from 1991-2020. 81
Table 5.5. Relationship between atmospheric indices and extreme precipitation of different precipitation regions during the post-monsoon season from 1961-1990. 84
Table 5.6. Relationship between atmospheric indices and extreme precipitation of different precipitation regions during the post-monsoon season from 1991-2020. 84
Table 5.7. Relationship between atmospheric indices and extreme precipitation of different precipitation regions during the winter season from 1961-1990. 85
Table 5.8. Relationship between atmospheric indices and extreme precipitation of different precipitation regions during the winter season from 1991-2020. 85
Figure 2.1. The geographical location and topography of Pakistan. 28
Figure 2.2. (a) Mean annual precipitation (mm) and (b) mean annual temperature (℃) in Pakistan during the period of 1991-2020. 30
Figure 2.3. Location of the weather stations over various regions of Pakistan. 32
Figure 2.4. Research flow chart of this study. 36
Figure 3.1. Differences of the seasonal precipitation between 1961-1990 and 1991-2020 (a) Pre-monsoon (b) Summer monsoon (c) Post monsoon... 40
Figure 3.2. Changes in the pre-monsoon precipitation trends (a) 1961-1990 (b) 1991-2020. Red (blue) shaded area indicates positive (negative)... 42
Figure 3.3. Same as Figure 3.2 but for the summer monsoon precipitation. 43
Figure 3.4. Same as Figure 3.2 but for the post-monsoon precipitation. 43
Figure 3.5. Same as Figure 3.2 but for winter monsoon. 44
Figure 4.1. Changes in Consecutive Wet Days for the period 1961-1990 and 1991-2020 during Pre-monsoon (a,b), summer monsoon (c,d), post-... 47
Figure 4.2. Same as Figure 4.1, but for very wet days. 51
Figure 4.3. Same as Figure 4.1, but for extremely wet days. 52
Figure 4.4. Same as Figure 4.1, but for total precipitation on wet days. 57
Figure 4.5. Same as Figure 4.1, but for a simple daily intensity index. 60
Figure 5.1. Relationship of atmospheric indices with seasonal precipitation over different regions from 1961-1990 and 1991-2020 during the pre-... 65
Figure 5.2. Same as Figure 5.1 but for the summer monsoon season. 68
Figure 5.3. Same as Figure 5.1 but for the post-monsoon season. 73
Figure 5.4. Same as Figure 5.1 but for winter season. 76
Figure 6.1. indicated the comparison between current and previous studies and analyzed the main contribution in monsoonal precipitation studies. 89
Figure 6.2. Changes of trends of extreme precipitation indices between 1961-1990 and 1991-2020 during the summer monsoon season; (a)... 92
Figure 6.3. Same as Figure 6.2, but for the winter season. 94
Figure 6.4. indicated the comparison between current and previous studies and examined the main contribution in monsoonal extreme precipitation studies. 96