Title Page
Abstract
Contents
1. Overview 27
2. Regional differences in raindrop size distribution observed from disdrometers in South Korea and their possible causes 30
2.1. Introduction 30
2.2. Data and methodology 33
2.2.1. Disdrometer data and RSD parameters 33
2.2.2. Rain-type classification 41
2.2.3. Reanalysis data 43
2.3. Result and discussion 44
2.3.1. Regional differences in precipitation and RSD characteristics 44
2.3.2. RSD characteristics according to the rain rate and rain type and their regional differences 52
2.3.3. Reginal differences in thermodynamic and cloud characteristics 63
2.3.4. Implications for quantitative precipitation estimations and cloud microphysics parameterizations 66
3. Diagnostic relations for the intercept parameter of exponential raindrop size distribution according to rain types derived from disdrometer data and their impacts on precipitation prediction 72
3.1. Introduction 72
3.2. Diagnostic relations for the intercept parameter N₀ 78
3.2.1. Disdrometer data 78
3.2.2. Review of the derivation methods of diagnostic relations 82
3.2.3. Evaluation of the derived relation 87
3.3. Impacts of the derived diagnostic relation on precipitation prediction 95
3.3.1. Model description and simulation setup 95
3.3.2. Evaluation of the simulations with different methods of applying the diagnostic relation 98
3.3.3. Impacts of the diagnostic relation on cloud microphysical characteristics 102
4. Raindrop size distributions simulated using a bin microphysics scheme: Different biases in stratiform and convective rain from an extratropical cyclone 119
4.1. Introduction 119
4.2. Data and method 124
4.2.1. Case description 124
4.2.2. Model description and simulation setup 126
4.2.3. RSDs from the disdrometer and the bin microphysics scheme 128
4.3. Results and discussion 132
4.3.1. Evaluation of simulated raindrop size distribution 132
4.3.2. Possible sources of the biases in RSD prediction 143
5. Impacts of aerosols on precipitation and raindrop size distribution in an extratropical cyclone system 158
5.1. Introduction 158
5.2. Simulation setup and methodology 159
5.2.1. Simulation setup 159
5.2.2. Rain-type classification 160
5.3. Results and discussion 161
5.3.1. General characteristics of simulated precipitation 161
5.3.2. Response of convective rain to increasing Na[이미지참조] 166
5.3.3. Response of stratiform rain to increasing Na[이미지참조] 175
6. Summary and conclusions 180
References 189
초록 208
Table 2.1. Mean and standard deviation (in parentheses) values of RSD parameters for each site. The units of Nt, Z, W, R, Dm, and Nw are...[이미지참조] 51
Table 3.1. Coefficients αi and βi in the derived diagnostic relations for total, stratiform, mixed, and convective rain[이미지참조] 88
Figure 2.1. (a) Topographic map of South Korea and its surrounding regions and (b) zoomed area with locations of the three disdrometers (red circles). 34
Figure 2.2. Scatter plots of hourly accumulated rainfall amount observed by the disdrometers and rain gauges in (a) Seoul, (b) Chuncheon, and (c) Jincheon. 42
Figure 2.3. (a) Accumulated rainfall amount and duration and (b) box plot of rain rate for rainfall events at each site. The upper boundary, centerline, and... 45
Figure 2.4. (a) Raindrop size distribution and (b) normalized R(D) at each site. 47
Figure 2.5. Probability density functions of (a) log₁₀Nt, (b) Z, (c) log₁₀W, (d) log₁₀R, (e) Dm, and (f) log₁₀Nw for each site.[이미지참조] 50
Figure 2.6. Density scatter plots of the mass-weighted diameter and the logarithm of generalized intercept parameter for (a) Seoul, (b) Chuncheon,... 54
Figure 2.7. Probability density functions of (a,c,e) the mass-weighted mean diameter and (b,d,f) the logarithm of generalized intercept parameter for (a,b)... 58
Figure 2.8. (a) Mass-weighted mean diameter and (b) logarithm of generalized intercept parameter averaged over RSD data in each rain rate category at each site. 61
Figure 2.9. Box plots of (a) convective available potential energy, (b) cloud- top height, and (c) cloud-base height at each site. The upper boundary,... 65
Figure 2.10. Scatte r plot of the rain rate R and the radar reflectivity Z for (a) the total, (b) stratiform rain, (c) mixed rain, and (d) convective rain. The black,... 68
Figure 2.11. Scatter plot of the slope parameter Λ and the shape parameter μ. The black, red, and blue lines represent the second-order polynomial fits for... 70
Figure 3.1. Locations of four disdrometers (red circles) on the topographic map of South Korea and surrounding regions (shaded). 79
Figure 3.2. Box plots of the intercept parameter N₀ estimated from the disdrometer data at the four sites and the total data for four seasons. The lower... 81
Figure 3.3. Density scatter plots of the intercept parameter N₀ and the rainwater content W estimated from the disdrometer data for (a) total, (b)... 89
Figure 3.4. Density scatter plots of the intercept parameter estimated from the disdrometer data, N₀,estimated, and the intercept parameter diagnosed from the...[이미지참조] 93
Figure 3.5. Model domain configuration. The shades represent the terrain height. 96
Figure 3.6. Seven-day accumulated precipitation amount (a) observed at 561 rain gauge stations (marked with black dots in (a)) and predicted in the (b)... 100
Figure 3.7. Equitable threat scores for (a) daily precipitation amounts and (b) hourly precipitation amounts in the WSM6-O, WSM6-E, and WSM6-L simulations. 103
Figure 3.8. Probability density functions (PDFs) for (a, b) the logarithm of the intercept parameter N₀ and (c, d) the slope parameter Λ estimated from the... 105
Figure 3.9. Vertical profiles of (a) the logarithm of the intercept parameter N₀ and (b) the slope parameter Λ. N₀ and Λ are time- and domain-averaged. 107
Figure 3.10. Time- and domain-averaged vertical profiles of hydrometeor mixing ratios obtained from the (a) WSM6-O and (b) WSM6-L simulations... 108
Figure 3.11. Time- and domain-averaged vertical profiles of microphysical conversion rates related to rainwater (PRAUT: autoconversion of cloud water... 111
Figure 3.12. Differences in the horizontal fields at (a) z=4 km and (b) z=1 km and (c) vertical profiles of virtual potential temperature θv between the...[이미지참조] 114
Figure 3.13. 24-h accumulated precipitation amount (a) observed at rain gauge stations (marked with black dots in (a)) and predicted in the (b) WSM6-O and... 116
Figure 3.14. As in Fig. 3.8, but for the precipitation case on 2-3 April 2021. 117
Figure 4.1. Fields of (a, b) 500-hPa and (c, d) 850-hPa geopotential height (green lines) and horizontal wind vectors (arrows) at (a, c) 0900 and (b, d)... 125
Figure 4.2. Model domain configuration with topography (shaded). The red star in domain 3 indicates the disdrometer site in Seoul. 127
Figure 4.3. Spatial distributions of (a, c, e) observed and (b, d, f) simulated average rain rates for the periods of (a, b) 0830-1230 LST, (c, d) 1030-1230... 133
Figure 4.4. (a) Time series of rain rate in the rain gauge observation and simulation averaged over the locations of 110 rain gauges in the Seoul... 135
Figure 4.5. Simulated and observed raindrop size distributions at the disdrometer site averaged over the period of 0830-1400 LST. 137
Figure 4.6. Time series of the logarithm of raindrop number concentration (shaded) in the (a) disdrometer observation and (b) simulation at the... 139
Figure 4.7. Simulated and observed raindrop size distributions at the disdrometer site in (a) Phase 1 (P1) and (b) Phase 2 (P2). 140
Figure 4.8. Mean values (filled circles) and ±1 standard deviation (whiskers) of mass-weighted mean diameter Dm and the logarithm of generalized...[이미지참조] 142
Figure 4.9. Time-height plot of mixing ratios of liquid-phase (shaded) and ice- phase (contoured) hydrometeors at the disdrometer site. The contours are in... 145
Figure 4.10. Simulated raindrop size distributions at different levels at the disdrometer site in (a) P1 and (b) P2. Vertical distributions of the logarithm... 146
Figure 4.11. Vertical profiles of simulated (a) hydrometeor mixing ratios and (b) microphysical conversion rates at the disdrometer site in P1. 149
Figure 4.12. Simulated snow size distributions at different levels at the disdrometer site in P1. Vertical distribution of the logarithm of snow number... 151
Figure 4.13. As in Fig. 4.11, but for P2. 154
Figure 4.14. Scatter plots of (a) Dm and (b) log₁₀Nw versus rain rate at the disdrometer site in P2. Red and black dots indicate the simulation and...[이미지참조] 156
Figure 5.1. 12-h accumulated precipitation amounts in the simulations with initial aerosol number concentrations of Na=(a) 100, (b) 900, (c) 2700, (d)...[이미지참조] 163
Figure 5.2. Time series of rain rates (solid lines) and accumulated rain amounts (dashed lines) in the simulations with different initial aerosol number... 164
Figure 5.3. (a,d,g) Accumulated rain amount, (b,e,h) ratio of rain area to total area, and (c,f,i) rain rate averaged over the analysis area for (a,b,c) the total,... 165
Figure 5.4. Vertical profiles of time- and area-averaged (a) number concentration and (b) mass-weighted diameter (Dm) for cloud droplets, and...[이미지참조] 167
Figure 5.5. Vertical profiles of time- and area-averaged conversion rates of (a) nucleation, (b) condensation, (c) evaporation, (d) autoconversion, (e)... 168
Figure 5.6. Vertical profiles of (a) latent heat, (b) supersaturation, (c) vertical velocity larger than 0.1 m s¯¹, and (d) vertical velocity larger than 1.5 m s¯¹. 170
Figure 5.7. Snow water path (contoured) in the simulations with (a) Na=100 cm¯³ and (b) Na=24300 cm¯³ at 0600 LST. The shaded area represents the...[이미지참조] 172
Figure 5.8. Time-height plots for mixing ratios for liquid and ice hydrometeors in the simulations with (a) Na=100 cm¯³ and (b) Na=24300 cm¯³ at Seoul site.[이미지참조] 173
Figure 5.9. (a) Raindrop size distributions for convective rain and (b) their ratios to the raindrop size distributions in the simulation with Na=100 cm¯³.[이미지참조] 174
Figure 5.10. Vertical profiles of time- and area-averaged mixing ratios for (a) cloud water, (b) rainwater, (c) cloud ice, (d) snow, (e) graupel, and (f) hail. 176
Figure 5.11. As in Fig. 5.5, but for stratiform rain. 177
Figure 5.12. As in Fig. 5.9, but for stratiform rain. 179