Assessment of East and South Asian Summer Monsoon using a High-Resolution AGCM
- Abstract
- In the present thesis, a high-resolution (40-km) Atmospheric General Circulation Model (AGCM) has been used for the present-day climate simulation and future climate projection to assess the East and South Asian Summer Monsoon (EASM and SASM) characteristics as well as investigated the teleconnections between EASM and SASM. First, to verify the importance of horizontal resolution, we have evaluated the response of horizontal resolution using 25 Coupled Model Intercomparison Project phase 5 (CMIP5)/AGCMs for EASM main diagnostics like (1) climatological summer monsoon precipitation and circulation, (2) seasonal march and (3) interannual variability. Results of Various statistical measures of CMIP5 models have shown that the high-resolution models are consistent top performer and highlighted the beneficial impact of horizontal resolutions on EASM.
Based on this evaluation, we have performed the present-day climate simulation and future projection for EASM and SASM with a high-resolution AGCM (GME) based on the two Representative Concentration Pathway (RCP) Scenarios (RCP4.5 and RCP8.5). Results for present-day climate simulation shows that the GME well captured the high and low rain belts along with the onset and withdrawal of monsoon over East and South Asia both. The projection of JJA (June-August) precipitation over East Asia show a gradual increase (3-5%) and a large increase is found over the Korea (7-12%) from mid- to far-futures especially under RCP8.5. This can be attributed to the projected more humidity (5%) over the eastern coast of China, Korea and northeast China and northwestward strengthening of West North Pacific Subtropical High (WNPSH). In the projection for SASM, model projected an increased precipitation over Northwest India (NWI) and South Peninsular India (SPI) and a decreased precipitation over Northeast India (NEI) and north-central India. This is attributed to the westward shift of Monsoon Trough (MT) and expansion and intensification of Mascarene High (MH) and Tibetan High (TH).
Based on the projected change in precipitation characteristics, we have also investigated the future pattern of teleconnection between EASM and SASM precipitation with the both RCP scenarios as well as examined the possible factors responsible for these teleconnection. The projected teleconnection between South and East Asian summer precipitation shows similar pattern of out-of-phase relationship as noticed during current climate. An additional study of regional relationships of East Asia with the South Asian precipitation shows in-phase relationship with North China and out-of-phase relationships with Korea-Japan and Southern China. The CC patterns between precipitation over Korea-Japan and wind at 850 hPa shows a large amount of moisture enters Korea-Japan (well developed cyclonic circulation) along the western edge of WNPSH and anticyclonic circulation over the Western Pacific causes less rainfall over South Asia (explains out-of-phase relationship). The CCs between precipitation over North China and wind at 850 hPa shows strong southwesterlies flow over South Asia (India) and bring moistures from lower latitudes to North China (explain the in-phase relationship). The examination of CC patterns of precipitation between South and East Asian block for three time-slices in future shows stronger teleconnection during near- and far-future as compared to the mid-future and it is well supported by the CC patterns of large scale circulation systems.
- Issued Date
- 2017
- Awarded Date
- 2017. 8
- Type
- Dissertation
- Publisher
- 부경대학교
- Affiliation
- 부경대학교 대학원
- Department
- 대학원 환경대기과학과
- Advisor
- 오재호
- Table Of Contents
- List of Figures v
List of Tables xvi
Abstract xvii
Chapter 1 Introduction 1
1.1 Climate Change 1
1.2 East and South Asian Summer Monsoon 2
1.3 Teleconnection between EASM and SASM 3
1.4 A high-resolution Atmospheric Global Circulation Model 4
1.5 Overview of the thesis 6
Chapter 2 Response of Horizontal Resolutions to the East Asian Summer Monsoon Precipitation Simulated with CMIP5/AGCMs 8
2.1 Introduction 8
2.2 Details of models, observations and methodology 12
2.2.1 Details of models 12
2.2.2 Observations 15
2.2.3 Methodology 15
2.3 Results and discussions 18
2.3.1 Climatological mean monsoon precipitation and circulation 18
2.3.2 Seasonal march 29
2.3.3 Interannual variability 37
2.4 General evaluation of EASM 49
2.5 Summary 54
Chapter 3 Present-day Climate Simulation and Future Projection for East Asian Summer Monsoon with a High-Resolution AGCM based on RCP Scenarios 56
3.1 Introduction 56
3.2 Description of GME model, observed data and simulation details 61
3.2.1 GME model 61
3.2.2 Experiment design 62
3.2.3 Observed data 64
3.2.4 CMIP5 models for GME evaluation 65
3.3 Evaluation of present-day climate simulations 67
3.3.1 Global seasonal-mean climatologies 67
3.3.2 Seasonal summer monsoon precipitation and circulations 72
3.3.3 Annual cycle in zonal precipitation 79
3.4 Projection of future climate change and extreme events 83
3.4.1 Annual temperature and precipitation 83
3.4.2 Seasonal summer monsoon precipitation and circulations 87
3.4.3 Annual cycle 91
3.4.4 Seasonal summer monsoon relative humidity 93
3.4.5 Seasonal summer monsoon geopotential height 97
3.4.6 Seasonal summer monsoon extreme precipitation events 102
3.5 Summary 111
Chapter 4 Application of a High-Resolution AGCM on another Asian Monsoon System: South Asian Summer Monsoon 113
4.1 Introduction 113
4.2 Data and methodology 116
4.3 Evaluation of present-day climate simulations 117
4.3.1 Seasonal precipitation 117
4.3.2 Wind analysis 124
4.3.3 Annual cycle in zonal precipitation 126
4.4 Projection of future climate change and extreme events 129
4.4.1 Annual temperature and precipitation 129
4.4.2 Seasonal summer monsoon precipitation 131
4.4.3 Seasonal circulations 135
4.4.4 Large scale monsoon circulation systems 138
4.4.5 Seasonal summer monsoon extreme precipitation events 144
4.5 Summary 150
Chapter 5 Possible Teleconnection between South and East Asian Summer Monsoon in Projected Future Climate Change 152
5.1 Introduction 152
5.2 Data and methodology 155
5.3 Interannual variabilities and statistical relationships of South and East Asian summer monsoon precipitation 156
5.4 Future projected trend in Asian summer monsoon precipitation 160
5.4.1 Projected trend in regional EASM precipitation 162
5.5 Projected future teleconnection between South and East Asian monsoon precipitation and plausible factors 165
5.5.1 Details of future changes in relationships between East and South Asian summer precipitation 166
5.5.2 Mean sea level pressure 169
5.5.3 Wind at 850 hPa 174
5.5.4 Sliding CCs between South Asia and regional EASM precipitation 178
5.6 Summary 183
Chapter 6 Conclusions 185
References 190
Appendix A Abbreviations 211
Appendix B GME model description 214
Abstract (Korean) 224
List of Publications 227
Acknowledgements 229
- Degree
- Doctor
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