Title Page
Abstract
Contents
Chapter 1. Introduction 18
1.1. Background and Motivation 18
1.2. Scientific Questions 20
1.3. Objectives of this study 24
Chapter 2. Measurements and analysis 28
2.1. Condensation particle counter (CPC) 28
2.2. Mobility particle size spectrometer (MPSS) 29
2.3. Cloud condensation nuclei (CCN) counter 30
2.4. Cyclostationary empirical orthogonal function (CSEOF) 30
Chapter 3. Characteristics of PNSD and NPF over Asian continental outflow 34
3.1. Spatial characterization of the NPF and PNSD over Korea 34
3.2. Evaluation of pandemic lockdown effect on the PNSD and NPF over Asian continental outflow 44
Chapter 4. Trend analysis of PNSD and NPF on the global scale 66
4.1. Elaboration the environmental characteristics from multi-year PNSD observation from in-Situ Aerosol Global Atmosphere Watch Network (SARGAN) 66
4.2. Global trend of PNSD and NPF 86
4.3. Influence of the global NPF change on the CCN-sized aerosols 94
Chapter 5. Summary and conclusions 102
References 108
국문 초록 126
Table 2.1. Descriptions for the instruments and measured parameters in the case study. 32
Table 3.1. Variations in NPF occurrence time (8-12 LST) surface meteorological factors during the LD period at three sites. Values in the... 59
Table 4.1. Comprehensive descriptions of 27 selected lowland sites. 72
Figure 3.1. FT NPF case (31 May, 2016): (a) The flight path in the BL and FT. NCN3-10 corresponding to the flight path is represented as color scale....[이미지참조] 36
Figure 3.2. The time series of SO₂ mixing ratio, sulfate concentration, NO₂ mixing ratio, and nitrate concentration during the FT NPF case (31 May,... 37
Figure 3.3. The scatter plot for sulfate-to-CO ratio versus (a) temperature and (b) relative humidity for DC-8 flight in FT over the YS... 40
Figure 3.4. The spatial distribution of SO₂ mixing ratio (left panel) and sulfate concentration (right panel) at 700 hPa simulated by GEOS-Chem... 40
Figure 3.5. (a) The vertical profile of NCN3-10 during the KORUS-AQ campaign. The red line and pink shading denote the average and 1-...[이미지참조] 43
Figure 3.6. 850-hPa wind vector (arrow) from January to May during the period of 2013-2019 and 2020. The spatial distribution of AOD is... 45
Figure 3.7. (a) Diurnal variation in mean PNSD and its standard deviation in three sites during the Pre-LD (left) and LD (right) periods.... 48
Figure 3.8. (a) Cyclostationary loading vector of first CSEOF mode (Mode 1 CSLVs) calculated from the PNSD obtained at the BRY, AMY, and BOS... 51
Figure 3.9. Averaged diurnal variation in PNSD during the classified strong- (left), weak- (middle), and non- (right) NPFs at the three sites. 52
Figure 3.10. (Upper) Monthly variation in PNSD measured at BRY in February, 2017. (Lower) Monthly variation in daytime-averaged (7-16... 54
Figure 3.11. (a) Frequency of strong- (black), weak- (gray), and non- (white) NPF events during the Pre-LD and LD periods at the BRY, AMY,... 56
Figure 3.12. Diurnal variation in H₂SO₄ proxy at the BRY, AMY, and BOS sites during the Pre-LD (green) and LD (red) periods. Diurnal variation... 63
Figure 4.1. The location of measurement stations with PNSD data. The shape and color of station markers indicated the range of total aerosol... 71
Figure 4.2. An example of NPF identification using observed PNSD in HYY during 8-14 May, 2018. (a) Observed PNSD during 8-14 May, 2018... 75
Figure 4.3. Yearly variation of frequency of strong- (green), weak- (yellow), and non-NPF events (black) in HYY from 1996 to 2020. 76
Figure 4.4. NPF frequencies estimated in 27 selected lowland sites based on the CSEOF technique. Strong-NPF frequencies are marked as... 78
Figure 4.5. Averaged FR (10 nm) and GR for all available data measured in each measurement sites. 80
Figure 4.6. Ntot arranged with the value (Left) and Nnuc ratio (Nnuc/(Nnuc+Nacc)) according to Ntot (Right). On the left figure, 1st and 3rd...[이미지참조] 82
Figure 4.7. PNSD for each environment. Lines with each light color represent the all-period average of PNSD for each sites, and lines with... 84
Figure 4.8. Scatter plot representing ratio of Nnuc (left), and Nacc (right) to Ntot in urban (red), rural (green), and remote (blue).[이미지참조] 85
Figure 4.9. Decadal trends of Nnuc estimated from linear regression (left) and Sen's slope (right). Solid lines were added to the statistically...[이미지참조] 87
Figure 4.10. Decadal trends of Nnuc estimated during local daytime (gray) and nighttime (black). Overall Nnuc trend is represented as color dot and...[이미지참조] 89
Figure 4.11. Decadal trends of NPF frequency estimated from linear regression (left) and Sen's slope (right) for strong-NPF (thin bar) and... 91
Figure 4.12. Scatter plot between NPF frequency trend and Nnuc trend for urban (red), rural (green), and remote (blue) sites. Horizontal and...[이미지참조] 93
Figure 4.13. Scatter plot for CCN number concentration at different supersaturation (SS) level (0.1%, 0.2%, 0.3%, 0.5%, and 1.0%) versus... 97
Figure 4.14. Scatter plot for CCN number concentration at different supersaturation level (0.1%, 0.2%, 0.4%, 0.7%, and 1.0%) versus CCN-... 98
Figure 4.15. Overall mean and standard deviation of N₅₀ during non-NPF and NPF in urban, rural, and remote environments. 99
Figure 4.16. Scatter plot between NPF frequency trend and N₅₀ trend for urban (red), rural (green), and remote (blue) sites. Horizontal and... 101