著者
KUSAKA Hiroyuki NAKAMURA Yusuke ASANO Yuki
出版者
公益社団法人 日本気象学会
雑誌
気象集誌. 第2輯 (ISSN:00261165)
巻号頁・発行日
pp.2022-035, (Released:2022-05-13)
被引用文献数
1

Ultra Violet (UV) parasols are a reasonable countermeasure against heat stress as they are portable and inexpensive. This study compared the heat stress mitigation effect of a UV parasol with that of street trees and dry-mist spraying on a hot and humid summer day in Japan. We observed meteorological elements and calculated the universal thermal climate index (UTCI) and wet-bulb globe temperature (WBGT) under UV parasol, street trees, dry-mist spraying, and direct sunlight. The observed UTCI and WBGT under the UV parasol were lower than those in direct sunlight by 4.4 and 1.3°C, respectively, because of the decrease in black globe temperature caused by the reduced downward shortwave radiation. This demonstrated that UV parasol reduced heatstroke risk by one level. The effect of the UV parasol was equal to or greater than 75 % of that of the street trees from the perspective of UTCI. The street trees reduced the UTCI and WBGT by 5.9 and 1.9°C, respectively, compared to those in direct sunlight, resulting in the reduction of heatstroke risk by one level. In contrast, dry-mist spraying did not mitigate heat stress in conditions with moderate winds. Although the results of this study were obtained from observations on a single day, comparison with earlier studies confirms that the values observed in this study are representative results on summer days in Japan.
著者
Sho Kawazoe Masaru Inatsu
出版者
公益社団法人 日本気象学会
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
pp.2022-024, (Released:2022-06-08)
被引用文献数
2

We investigated the sub-seasonal predictability of heavy snowfall events in Iwamizawa, Hokkaido, using the Japan Meteorological Agency's 1-month ensemble predictions. First, the self-organizing map (SOM) technique was applied to the Japanese 55-year Reanalysis sea-level pressure anomalies to identify weather patterns resulting in heavy snowfall. It revealed that heavy snowfall developed in SOM nodes (weather patterns) with low-pressure centers to the east/northeast of Hokkaido and Siberian high to the west, resulting in westerly to northwesterly monsoon winds traversing the Sea of Japan towards western Hokkaido. Next, ensemble forecasts were projected onto the SOM map to determine the predictability of weather patterns up to a month in advance. For winter 2019, there was relatively low probability of projecting a high number of ensembles in SOM nodes to those observed in the reanalysis. In contrast, much higher probability was seen in 2020 to ∼10 forecast days. When considering multiple SOM nodes that contribute to heavy snowfall in the forecast, both winters saw more ensemble members predicting heavy snowfall to ∼10 forecast days. We also saw a higher probability of heavy snowfall beyond 10-days in 2020. These results highlight the potential benefit of incorporating multiple weather patterns to forecast heavy snowfall.
著者
Inovasita Alifdini Teruhisa Shimada
出版者
公益社団法人 日本気象学会
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
pp.2022-025, (Released:2022-06-15)
被引用文献数
2

This study investigates the diurnal variation of surface wind divergence in the seas of the Maritime Continent by using satellite scatterometer observations and atmospheric reanalysis data. This is the first study to demonstrate the distribution and seasonal variation of the diurnally varying surface winds in the Maritime Continent in terms of wind divergence. Wind divergence develops from the coasts of the islands toward the center of the seas and dominates during the afternoon and evening hours. Wind convergence dominates over the seas during the nighttime and morning hours. The offshore extensions of the wind divergence and convergence from the coast differ regionally and thus show the asymmetric patterns with respect to the center of the seas. In particular, strong wind divergence develops from the southern coasts of the Java Sea and the Arafura Sea to extend northward beyond the center of the seas. The diurnal amplitudes of wind divergence vary seasonally and reach a peak in September in most of the seas. The switching times between wind divergence and convergence are almost fixed throughout the year regardless of the monsoon reversal.
著者
Yoshio Kawatani Takeshi Horinouchi Naoki Sato
出版者
公益社団法人 日本気象学会
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
pp.2022-020, (Released:2022-05-19)
被引用文献数
1

Climate changes around Japan associated with upper troposphere and stratosphere responses of global warming during December-January-February were investigated using the storyline approach and the Coupled Model Intercomparison Project 5 dataset. Climate change was calculated by subtracting the 1959-1990 mean in historical simulations from the 2068-2099 mean in the Representative Concentration Pathways 8.5. Four storylines in plausible future climates were discussed by considering two remote indices representing tropical amplification (tropical upper tropospheric temperature changes) and stratospheric vortex strength. Stratosphere-troposphere connections in terms of zonal wind responses are most pronounced in the storyline of high tropical amplification with strong stratospheric vortex in which the subtropical jet shifts substantially northward. The multimodel mean displays more (less) precipitation in the northern (southern) parts of Japan, while the storyline of high (low) tropical amplification with strong (weak) stratospheric vortex shows increasing (decreasing) precipitation in most parts of Japan. Projected precipitation changes around Japan depend heavily on the storyline adopted and the degree of global warming in these two storylines. Alternatively, precipitation changes depend mostly on the overall strength of global warming with minor influences from storylines in the case of low (high) tropical amplification with strong (weak) stratospheric vortex.
著者
Yuta Goto Masaki Satoh
出版者
公益社団法人 日本気象学会
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
vol.18A, no.Special_Edition, pp.15-20, 2022 (Released:2022-04-28)
参考文献数
31
被引用文献数
3

We statistically investigate characteristics of “senjo-kousuitai”, quasi-stationary linear precipitation systems, in East Asia using high-resolution satellite precipitation and reanalysis data to understand whether these events are common there. We define an elongated precipitation system in the satellite precipitation data as a senjo-kousuitai event.Our results show that the contribution of senjo-kousuitai to heavy rainfall is high in western Japan, especially in Kyushu, the Nansei Islands, and the East China Sea. Among the environmental factors favorable for the occurrence of senjo-kousuitai, low-level water vapor flux and vertical wind shear are essential to the development of senjo-kousuitai. As a typical case, we examine large-scale circulations associated with senjo-kousuitai events in Kyushu in the Baiu season (June to July), and found that they are generally characterized by the intensified Pacific High over the south of Kyushu and pressure trough to the north of Kyushu. This circulation pattern results in a stronger pressure gradient and higher low-level wind speeds over Kyushu. With respect to the previously noted importance of water vapor and wind speed for better prediction of senjo-kousuitai, we show that not water vapor but higher wind speeds are the main factor for the enhancement of low-level water vapor flux.
著者
川畑 幸夫 藤戸 誠
出版者
公益社団法人 日本気象学会
雑誌
気象集誌. 第2輯
巻号頁・発行日
vol.29, no.2, pp.37-44, 1951

本報文は,單に實用的見地から,台風接近の際に起る海面の上昇量と,最高水位の時刻を手輕に豫報せんとするもので,第5圖に示す如く,上昇量は大體其の季節の標準氣壓と台風の経路中の最低氣壓の差に比例し,同時に又台風が最も接近した時刻の距岸距離に逆比例する.それらを推定することにより豫報は量的に可成り正確に出來る.最高水位の時刻は本文中の表に示す如く,其の港で最低氣壓が起るときと殆んど同時と考えてよい.尤も距岸距離が著しく近く,&gamma;&rarr;0の場合には,單に圖からは上昇量が無限大となることになるが,丁度うまい場合の資料がまだないのでよくわからない.最高水位の時刻は外洋に面した港では上述の如くなるが,大阪灣,東京灣等の如く灣口の狭い灣の奥では最低氣壓の起時より10數時間早いこともあり,おそいこともある.<br>災害の面から見ると,暴風に伴う風浪が亦極めて大切なものであるが,このような短周期の波を自記せしめる測器は現在まだないので,やむを得ず檢潮儀り記録を資料とした.このため上の結果には風浪が一切除外されている.換言すれば風津浪の高さの最低限を與えてあることになり,實際には,いつでも第5圖の高さ以上の波が押寄せるわけである.<br>台風又は低氣壓に伴う海面の上昇量は,台風が洋上遙が遠方にある場合,或はそれらの中心示度が弱い場合には主として靜水力學的吸上げの影響として量的に殆んど完全に説明せられ,風の影響は全く認められない.ビユ〓フォ〓ト階級4以下の風が何日間吹き續いても影響は殆んどない.台風が接近し風力がビユーフォート階級5以上になると風による吹寄せは急速に増大し,遂に吸上げの効果を遙かに上廻るようになる.最高水位の場合の風向は第4圖に示した.<br>然しながら長週期の海面の昇降に關しては,之等の台風の場合と違ひ,風の影響は決して無視出來ないものゝようであり,これについては別途に報告したい.
著者
Naoko Kosaka Yusuke Umemiya Naoto Endou Tsuneko Kura Hiroshi Matsubara Masaki Hisada Akinori Murata Satoshi Mitarai
出版者
公益社団法人 日本気象学会
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
vol.19, pp.116-125, 2023 (Released:2023-07-04)
参考文献数
35

This paper presents experimental observations to improve typhoon prediction accuracy and to understand interactions between atmosphere and ocean directly under typhoons. Two unmanned surface vehicles (Wave Gliders (WGs)) equipped with interchangeable sensors were sailed toward the path of an approaching Category 5 typhoon (Hinnamnor), which began on 29 August 2022 and subsided on 6 September, reaching a minimum pressure of 920 hPa and a maximum wind speed of 55 m/s (105 knots). Sensors on WGs measured atmospheric pressure, wind speed, atmospheric and seawater temperature, wave height, currents, salinity, and chlorophyll-a concentrations in different parts of the typhoon. These observations made it possible to clarify changes in various phenomena as the typhoon approached and to compare differences in storm characteristics measured by the two WGs. Sea surface pressure in the core of a typhoon is useful as an initial predictor of its intensity. Data assimilation into numerical models and other observations are expected to improve prediction accuracy of typhoon phenomena. Furthermore, simultaneous observations of atmosphere and ocean will also be useful for modeling interactions.
著者
DUC Le SAWADA Yohei
出版者
公益社団法人 日本気象学会
雑誌
気象集誌. 第2輯 (ISSN:00261165)
巻号頁・発行日
pp.2024-003, (Released:2023-09-19)

It is well-known in rainfall ensemble forecasts that ensemble means suffer substantially from the diffusion effect resulting from the averaging operator. Therefore, ensemble means are rarely used in practice. The use of the arithmetic average to compute ensemble means is equivalent to the definition of ensemble means as centers of mass or barycenters of all ensemble members where each ensemble member is considered as a point in a high-dimensional Euclidean space. This study uses the limitation of ensemble means as evidence to support the viewpoint that the geometry of rainfall distributions is not the familiar Euclidean space, but a different space. The rigorously mathematical theory underlying this space has already been developed in the theory of optimal transport (OT) with various applications in data science. In the theory of OT, all distributions are required to have the same total mass. This requirement is rarely satisfied in rainfall ensemble forecasts. We, therefore, develop the geometry of rainfall distributions from an extension of OT called unbalanced OT. This geometry is associated with the Gaussian-Hellinger (GH) distance, defined as the optimal cost to push a source distribution to a destination distribution with penalties on the mass discrepancy between mass transportation and original mass distributions. Applications of the new geometry of rainfall distributions in practice are enabled by the fast and scalable Sinkhorn-Knopp algorithms, in which GH distances or GH barycenters can be approximated in real-time. In the new geometry, ensemble means are identified with GH barycenters, and the diffusion effect, as in the case of arithmetic means, is avoided. New ensemble means being placed side-by-side with deterministic forecasts provide useful information for forecasters in decision-making.
著者
Takashi Unuma Hiroshi Yamauchi Akihito Umehara Teruyuki Kato
出版者
公益社団法人 日本気象学会
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
vol.19, pp.150-156, 2023 (Released:2023-07-22)
参考文献数
28

We investigated the microphysical mechanisms for the enhancement of rainfall in a precipitating system that spawned heavy rainfall over the central part of the Kanto Plain in eastern Japan on 12 July 2022. Optical disdrometer observations confirmed the existence of an equilibrium state in the raindrop size distribution, especially when the precipitation intensity was high (e.g., 20 mm hr−1). As the raindrop size distribution approached equilibrium, raindrop sizes centered around 1.5 mm were observed initially, and then the number concentration of smaller and larger size raindrops increased simultaneously. The raindrop size distribution was closely related to the vertical profile of the parameters of raindrop size distribution that were estimated from polarimetric radar observations. These results suggest that the formation of equilibrium raindrop size distributions is important to produce substantial rainfall in the midlatitude as well as in the tropics.
著者
Takuto Sato Hiroyuki Kusaka
出版者
公益社団法人 日本気象学会
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
vol.19, pp.165-172, 2023 (Released:2023-08-11)
参考文献数
18

In this study, synthetic inflow turbulence generation methods developed in computational fluid dynamics (CFD) and meteorological fields were applied to thermally driven convective boundary layer (CBL) simulations. Methods developed in the CFD field include the Reynolds stress Cholesky decomposition and digital filter-based method (DF method), and the cell perturbation method (CPM) is a method developed in the meteorological field. Intercomparison results show that both methods can reproduce turbulence in thermally driven CBLs when a proper driver region is ensured. The turbulence reproduced using the DF method in a thermally driven CBL has a shorter driver region than that reproduced using CPM. However, CPM can be applied to a simulation without limiting the inflow boundary, although it requires a longer driver region than the DF method. Therefore, it was confirmed that both methods have unique merits that can be useful for downscaling from meteorological mesoscale models to microscale large-eddy simulation models.
著者
後藤 恵津子 岩崎 博之
出版者
公益社団法人 日本気象学会
雑誌
天気 (ISSN:05460921)
巻号頁・発行日
vol.70, no.3, pp.107-116, 2023 (Released:2023-04-30)
参考文献数
58

本論文では,北関東の雷神社の祈願目的と夏期の雷撃密度・雨量との関係を定量的に示す.雷を恐れの対象と見なす雷除雷神社と恵みをもたらす対象と見なす雨乞雷神社の計62社に注目して,それらの分布と12年間(2009-2020年)の夏期の雷撃密度とレーダ雨量の分布とを比較した.その結果,全神社数に対する雷除雷神社の割合は雷撃密度と有意な正の相関が認められた.一方,雨乞雷神社の割合は,雷撃密度と無相関であったが,夏期雨量とは有意な負の相関が認められた.これまで定性的に説明されていた雷神社と気象要素との関係が定量的に示された. また,雨乞雷神社が期待される地域でありながら雨乞雷神社が存在しない3つの地域について,雨乞雷神社が重視されなかった理由を考察した.
著者
REN Suling FANG Xiang NIU Ning SONG Wanjiao
出版者
公益社団法人 日本気象学会
雑誌
気象集誌. 第2輯 (ISSN:00261165)
巻号頁・発行日
pp.2023-021, (Released:2023-05-16)

Based on the vertical atmospheric sounding system carried by the FY-3D meteorological satellite (FY-3D/VASS) and the new wind radar instrument carried by the FY-3E meteorological satellite (FY-3E/WindRAD), a study of the potential application of research on the changes of temperature, humidity, and ocean wind vector (OWV) during the onset of the South China Sea summer monsoon (SCSSM) was carried out. The applications of these satellite datasets in SCSSM monitoring was evaluated, and the SCSSM onset process in 2022 was analyzed. The results showed that the mean bias of the FY-3D/VASS temperature and specific humidity at 850 hPa, compared with that of the fifth-generation ECMWF reanalysis, were −0.6 K and −0.53 g kg−1, respectively, and the pseudo-equivalent potential temperature (θse) was slightly lower, by 1-2 K; the distribution of θse was consistent with the seasonal advancement of the SCSSM. Compared with Metop-C/ASCAT, the mean bias of FY-3E/WindRAD zonal wind was positive and that of meridional wind was negative. The correlation coefficient, mean bias, mean absolute error, and root-mean-square error of the wind speed were 0.79, −0.45 m s−1, 1.56 m s−1, and 2.03 m s−1, respectively. The distributions of OWV were consistent, and the region and intensity of strong wind speed were close to each other. The temperature, humidity, and wind reversal during the onset of the SCSSM in 2022 were well-monitored by the FY-3D/E-derived θse and OWV dual indices, which are consistent with the SCSSM onset date, the third pentad in May, issued officially by the National Climate Center, China Meteorological Administration. Before the SCSSM onset in 2022, the tropical storms' pumping effect in early May increased the westerly wind over the tropical ocean north of the equator. After the storm weakened, the southwesterly wind passed across the Indochina Peninsula and reached South China Sea, causing the SCSSM onset.
著者
Nanami Naka Tetsuya Takemi
出版者
公益社団法人 日本気象学会
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
pp.19A-002, (Released:2023-06-05)
被引用文献数
2

Using mesoscale gridded analysis data and radar/raingauge-analyzed precipitation products, this study investigated the environmental conditions for the occurrence of extremely heavy rain events that occurred in northern Kyushu during the warm season in recent years. In all cases, the environmental conditions were not particularly unstable but were almost saturated in the deep layer of the troposphere. The existence of moist absolutely unstable layers (MAULs) was confirmed in and around the rainfall areas. A positive correlation was found between the volume of deep MAULs and the area total rainfall. A large convergence of the water vapor flux is observed in the lower troposphere, which appears to maintain very humid conditions and MAULs. The moisture convergence in the lower troposphere and the presence of deep MAULs is considered to enhance the heavy rainfall in the preceding hours. Humid conditions form deep MAULs that appear to precede the heavy rainfalls.
著者
Keita Fujiwara Tetsuya Takemi Nobuhito Mori
出版者
公益社団法人 日本気象学会
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
pp.2023-019, (Released:2023-06-03)

To investigate the effects of global warming on Typhoon Jebi (2018), we performed high-resolution pseudo-global 2-K and 4-K warming simulations with initial time ensembles using a regional atmospheric model. The pseudo-global warming experiments demonstrated the further facilitation of Jebi's development with a higher rise in the temperature. The intensity over the ocean to the south of Japan increased by 8% (20%) in the climate warmed 2-K (4-K) to the current climate. Typhoon Jebi, in the 4-K warming simulations, maintained a robust inner-core characterized by a compact and deep eyewall and well-developed primary and secondary circulations even immediately before landfall, in contrast to the result in the 2-K warming simulations. The sustained robust axisymmetric structure immediately before landfall in the 4-K warming runs was strongly associated with the enhanced ocean warming around Japan, notable moistening of the lower-to-middle troposphere in the vicinity of Typhoon Jebi, and a significant decrease in vertical wind shear under the extremely warmed future climate. The nonlinear responses of Typhoon Jebi to the tropospheric temperature rise are attributable to the drastic changes in the midlatitude's thermodynamic and dynamic environments under climate changes resulting from 2-K to 4-K global warming.
著者
Reiji Kimura Masao Moriyama Levent Saylan
出版者
公益社団法人 日本気象学会
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
vol.19, pp.94-100, 2023 (Released:2023-05-26)
参考文献数
39

Simulations of future climate indicate that the Mediterranean countries will see increasing temperatures, and decreasing precipitation. In Türkiye, which has a semi-arid and dry sub-humid climate, the coupled effect of warming and drought is expected to lead to a general increase in aridity. We applied indices derived from satellite data to provide continuous monitoring for drought hazards and evaluated recent trends in aridification and drought. Annual averaged temperatures showed a statistically significant rise, although annual rainfall showed no nationwide trend despite strong fluctuations over Türkiye. Significant increasing (decreasing) trends of vegetation (aridification) could be found in the northern, western, and southern regions, despite the rising temperatures and fluctuations in rainfall. One cause of these trends is presumed to be an increase in the nation's proportion of forest, orchard trees, and irrigated farmland. Although decreasing trend of aridification over Türkiye, drought has recurred throughout the 22-year study period in the central and eastern regions. These areas in which the annual averaged satellite-based aridity index exceeds a threshold value correspond closely to regions vulnerable to drought. Satellite-based indices may show particular promise for the major agricultural or pasture areas in central and eastern Türkiye, which are at heightened risk of future drought.
著者
Yoshihiro Tomikawa Masashi Kohma Masanori Takeda Kaoru Sato
出版者
公益社団法人 日本気象学会
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
vol.19, pp.86-93, 2023 (Released:2023-05-23)
参考文献数
31
被引用文献数
1

An intensive balloon-borne observation was performed at Syowa Station in the Antarctic (69.0°S, 39.6°E) in July 2016 using Cryogenic Frostpoint Hygrometers (CFH) and Electrochemical Concentration Cell (ECC) ozonesondes. High water vapor concentration was observed in the upper troposphere in two out of five observations. Trajectory analysis and atmospheric reanalysis data showed that moist air was transported into the upper troposphere due to the upwelling in front of a trough. While only isentropic transport was dominant in one case, both the isentropic transport and diabatic heating contributed to the upward transport in the other case. In another case where the air parcels came over the Antarctic continent, the water vapor concentration in the upper troposphere was lower than in the other cases. These results suggest that transport of air parcels with different origins by synoptic-scale disturbances controls water vapor concentration in the Antarctic upper troposphere.
著者
Naoki Sato Takeshi Horinouchi Yoshio Kawatani
出版者
公益社団法人 日本気象学会
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
vol.19, pp.78-85, 2023 (Released:2023-05-16)
参考文献数
24

Large-scale trends related to the precipitation in central Japan were investigated in the Coupled Model Intercomparison Project 5 dataset. In the Representative Concentration Pathways 4.5 projections, surface temperature over central Japan increases by 1 to 4 K during the 21st century in most models. Focusing on the trend of surface-air temperature and precipitation in central Japan, these models were categorized into two groups: The precipitation significantly increases in 11 models (group A). On the other hand, the trends of precipitation are small in the remaining 20 models (group B). Analyses of high-frequency components based on daily data revealed that the difference in the precipitation prediction is associated with that in the storm activity around Japan. Relatively enhanced meridional surface-air temperature gradient in the subpolar region may contribute to reinforced storm activity. On the other hand, the zonal surface pressure gradient associated with the Siberian high and the Aleutian low is not strengthened in group A. The climatological wintertime monsoon does not appear to contribute to the difference of precipitation trend in central Japan between the two groups. Moreover, the influence of any other planetary-scale variations is not implied.
著者
ISHIOKA Keiichi
出版者
公益社団法人 日本気象学会
雑誌
気象集誌. 第2輯 (ISSN:00261165)
巻号頁・発行日
pp.2023-008, (Released:2022-11-17)
被引用文献数
1

Inspired by the detection of the Pekeris mode of atmospheric free oscillations by a recent study, high-accuracy numerical calculations of the problem of determining the equivalent depth of atmospheric free oscillations are performed. Here, the computational method is largely based on a previous study, but with modifications to improve the accuracy of the calculation. Two equivalent depths are found, with values of 9.9 km and 6.6 km. The former corresponds to the Lamb mode and the latter corresponds to the Pekeris mode. These values deviate from those obtained in the previous study, especially for the Pekeris mode. The causes of this discrepancy is discussed, as well as the correspondence between the equivalent depths obtained in this study and that of the Pekeris mode detected in the recent study.
著者
Yu Matsumoto Minrui Wang Yousuke Sato Takashi Y. Nakajima
出版者
公益社団法人 日本気象学会
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
vol.19, pp.63-69, 2023 (Released:2023-04-15)
参考文献数
38

This paper shows the CFODD of the regional dependence of cloud growth processes in low-level clouds obtained by the combined use of the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua satellite and the Cloud Profiling Radar (CPR) on the CloudSat satellite. This enabled the evaluation of the cloud growth process based on the cloud optical thickness (τ) and the effective radius of cloud particle (Re), similar to previous studies that performed statical analysis on low-level clouds over the globe. Our targets were regions in East Asian, Californian, and Peruvian. In all analysis areas, our results showed that the internal structure of clouds changed as Re increased, indicating cloud growth. In the East Asian region, the maximum τ remained relatively constant even when cloud droplet size grew. In contrast, in the regions of Californian and Peruvian, the maximum τ increased with Re during the condensation growth process and then decreased as drizzle particles transformed into rain. It was also found that Re was smaller in the East Asian region unlike in Californian and Peruvian. This indicates that there are more aerosols in the East Asian region, which is consistent with its geographical characteristics.