3 0 0 0 OA Insurance Loss Dependence on Typhoon Maximum Wind speed, Translation Speed and Size over Japan
- 著者
- Yuta Tamaki Sosuke Okubo Kei Horie
- 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.2022-039, (Released:2022-10-14)
We examined forty-five typhoons associated with insurance losses in Japan to explicitly describe typhoon-related variables that explain insurance-loss variations. Multiple regression analysis revealed that the combination of maximum wind speed and translation speed explained more of the variation in insurance-loss size than what the regression model with maximum wind speed alone did. Using maximum wind speed and gale-area radius as explanatory variables also slightly improved the explained variance, but it was less stable than the multiple regression model combining maximum wind speed and translation speed. The translation speed suggested an inland expansion of the strong-wind area associated with wind-speed asymmetry, while considering the exposure led to similar conclusions. Our regression model can be applied to estimate changes in the damage and uncertainty by adjusting the typhoon characteristics under multiple climate-change scenarios.
- 著者
- Amane Nakamura Tsubasa Kohyama
- 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.2022-038, (Released:2022-10-04)
Analysis of the El Ninño-Southern Oscillation (ENSO) phenomena has conventionally been performed using deviations from the mean. However, the question remains as to whether the mean is appropriate as the reference state, since it is sensitive to the existence of a few extreme events. In this study, the validity of the mean and mode as a reference is compared using an idealized simulation model. We show that the mode is not affected by the asymmetry of El Ninño and La Ninña and is more stable as a reference than the mean. Then, this result is also demonstrated using observed data. Observations also show that the relationship between the ENSO amplitude and the zonal shifts of the ENSO anomalies is more emphasized if the mode is employed. For the variables in the ocean interior, differences between the mode-based and mean-based methods appear throughout all seasons.
3 0 0 0 OA Contribution of Anomalous Circulation to the Early Onset of Baiu in Western Japan in 2021
- 著者
- Kazuto Takemura Yoshihiro Nakae Yoshihisa Fujihara Hirotaka Sato Hitoshi Sato Atsushi Goto Hiroaki Naoe
- 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.21-26, 2022 (Released:2022-09-21)
- 参考文献数
- 17
- 被引用文献数
- 1
Several regions in western Japan experienced a record-breaking early onset of the rainy season called Baiu in mid-May 2021, which is attributed to the northward movement and enhancement of the Baiu frontal zone. This study investigates large-scale atmospheric circulation that contributes to the early onset of Baiu. Diagnostic and statistical analyses based on reanalysis datasets reveal that both enhanced convection over the western Indian Ocean associated with the Madden–Julian oscillation and a blocking high near western Russia promote the excitation of Rossby waves to propagate downstream along the upper-tropospheric jet, and thus contributing to the northward movement of the Baiu frontal zone. The anomalous convection over the western Indian Ocean and the subtropical western North Pacific also may affect anticyclonic circulation anomalies to the northeast of the Philippines in the lower troposphere, which promotes moisture inflow toward western Japan and consequently intensifies the Baiu frontal zone. Numerical and quantitative analyses of the circulation anomalies near Japan based on a linear baroclinic model confirm the aforementioned results. The results indicate that the anomalous convection over the Asian monsoon region and the blocking high near western Russia are the primary factors contributing to the early onset of Baiu.
- 著者
- Tetsuya Kawano Ryuichi Kawamura
- 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.18, pp.205-210, 2022 (Released:2022-09-28)
- 参考文献数
- 29
- 被引用文献数
- 1
In this study, we investigated the remote effect of warm sea surface temperatures (SSTs) in the Kuroshio region of the East China Sea (ECS) on heavy rainfall that occurred in southern Kyushu, Japan, on 3 July 2020 using the Weather Research and Forecasting model. To examine the effect, a simulation with realistic SSTs and two simulations with reduced SSTs in the ECS Kuroshio region were performed. Backward- and forward-trajectory analyses showed that low-level parcels in the simulation with warmer SSTs in the ECS Kuroshio region possessed larger amounts of water vapor than those in the reduced-SST experiments. The difference in the water-vapor amounts of low-level parcels between the simulations with warmer and colder SSTs remained until the parcels started to ascend in the heavy rainfall area. In addition, there were many more parcels with extremely large amounts of water vapor in the simulation with warmer SSTs. Such an increase in low-level water-vapor amounts under warmer SST conditions in the ECS Kuroshio region led not only to enhancement of the precipitation source but also to atmospheric destabilization, resulting in the production of a large amount of precipitation.
- 著者
- Chultem Batbold Keiya Yumimoto Sonomdagva Chonokhuu Batdelger Byambaa Batdavaa Avirmed Shuukhaaz Ganbat Naoki Kaneyasu Yutaka Matsumi Teppei J. Yasunari Kenji Taniguchi Noriko Hasebe Keisuke Fukushi Atsushi Matsuki
- 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.2022-036, (Released:2022-09-06)
- 被引用文献数
- 1
In Mongolia, combined with the dry and windy climate during spring and autumn, the exposed sediment of mine tailings pond becomes an additional source of anthropogenic windblown dust and poses potential threats to the surrounding environment and human health. In this study, we reported on our first attempt to derive the spatiotemporal distribution of dust originating from the tailings pond of the Erdenet mine using a combination of ground-based in-situ measurements and Himawari-8 geostationary satellite remote sensing. Temporal evolution of the dust plume visualized by the RGB imagery corresponded well with the in-situ particle concentration measured on the ground. Under relatively cloud-free conditions, the dust RGB imagery from Himawari-8 clearly showed the spatial extent of the white dust plume originating from the tailings pond, in the range of 2,040-2,748 km2. Therefore, the dust RGB imagery by Himawari-8 is demonstrated to be sensitive enough to resolve the highly localized anthropogenic dust, even from a point source as small as the tailings pond, and is effective in studying susceptible areas subject to associated heavy metal deposition and contamination.
- 著者
- Kazuaki Nishii Bunmei Taguchi Masato Mori Yu Kosaka Hisashi Nakamura
- 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.18, pp.199-204, 2022 (Released:2022-09-12)
- 参考文献数
- 23
Anomalous coldness was observed over midlatitude Eurasia in December 2020 and over subpolar Eurasia in January 2021. The former was accompanied by the Warm Arctic and Cold Eurasia (WACE) pattern, while the latter by the negative phase of the Arctic Oscillation (AO). A set of large ensemble experiments with an atmospheric general circulation model suggests a contribution of reduced Arctic Sea ice to the midlatitude cooling and WACE pattern in December 2020. The tropical and extratropical sea surface temperature (SST) anomalies, however, contribute to warming over midlatitude Eurasia. In January 2021, neither the sea ice nor SST anomalies can explain the subpolar Eurasian cooling and the negative AO in our experiments.
- 著者
- Zuowei Xie Zelun Cheng Cholaw Bueh Mei Yong Chenglai Wu Purevjav Gomboluudev
- 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.18, pp.159-166, 2022 (Released:2022-07-25)
- 参考文献数
- 23
- 被引用文献数
- 1
This study examines the pattern transition of dust events identified based on dust RGB images from the Himawari-8 satellite, along with associated key circulations and dynamic features, during spring 2016-2020. The dust RGB images are ordered onto a 4 × 3 topological map according to the spatial similarity of the dust distribution using self-organizing maps. In this topological map, the dust distribution exhibits mainly an eastward displacement or amplification from the Taklimakan Desert to the Gobi Desert. The key circulation triggering the transition of dust pattern is the large-scale tilted ridge from Xinjiang to Siberia. Such a northeast–southwest-oriented ridge conveys cold air into Tibet and causes the near-surface Siberian high extending southward from the Sayan mountains to central China. Consequently, dust intrudes from the Gobi Desert into northern China. In contrast, a zonal “+ − +” wave train in the upper troposphere confines the near-surface high over western Siberia and induces the near-surface cyclogenesis over Mongolia and northern China. As a result, the dust is mainly concentrated over the Taklimakan Desert, with weak influence over Mongolia and northern China.
- 著者
- Saat Mubarrok Chan Joo Jang
- 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.2022-030, (Released:2022-08-03)
- 被引用文献数
- 2
Extreme rainfall (ER) in Indonesia frequently leads to floods and landslides, disrupting economic activity and impacting human lives. Here, we investigate ER variability in association with climate teleconnection patterns (CTP) including the El Niño Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), and Madden-Julian Oscillation (MJO), using extreme value analysis based on daily rainfall data from 32 stations for 30 years (1985-2014). By fitting a generalized extreme value distribution, a significant association between the annual maximum rainfall (AMR) and CTP was found in 12 of 32 stations. The sensitivity test of location parameter showed that the AMR-CTP interconnection was spatially inhomogeneous. The positive (negative) significant association of ENSO and IOD to AMR was noticeable in south-western (eastern) Indonesia. Additionally, MJO positive (negative) association was detected at 4 (3) stations mostly located in Sumatra (Java) Island. Furthermore, the return level analysis shows that the 20-year ER intensity waiting time will be shorter and longer when CTP indexes strengthen and weaken, suggesting a potential increase and decrease in the likelihood of future ER occurrences, respectively. These results are relevant for understanding the relationship between ER and CTP that should be considered in the adaptation and mitigation plans to minimize the ER impacts.
- 著者
- Tetsuya Kawano Ryuichi Kawamura
- 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.2022-033, (Released:2022-08-05)
- 被引用文献数
- 1
In this study, we investigated the remote effect of warm sea surface temperatures (SSTs) in the Kuroshio region of the East China Sea (ECS) on heavy rainfall that occurred in southern Kyushu, Japan on 3 July 2020 using the Weather Research and Forecasting model. To examine the effect, a simulation with realistic SSTs and two simulations with reduced SSTs in the ECS Kuroshio region were performed. Backward- and forward-trajectory analyses showed that low-level parcels in the simulation with warmer SSTs in the ECS Kuroshio region possessed larger amounts of water vapor than those in the reduced-SST experiments. The difference in the water-vapor amounts of low-level parcels between the simulations with warmer and colder SSTs remained until the parcels started to ascend in the heavy rainfall area. In addition, there were many more parcels with extremely large amounts of water vapor in the simulation with warmer SSTs. Such an increase in low-level water-vapor amounts under warmer SST conditions in the ECS Kuroshio region led not only to enhancement of the precipitation source but also to atmospheric destabilization, resulting in the production of a large amount of precipitation.
3 0 0 0 OA Contribution of Anomalous Circulation to the Early Onset of Baiu in Western Japan in 2021
- 著者
- Kazuto Takemura Yoshihiro Nakae Yoshihisa Fujihara Hirotaka Sato Hitoshi Sato Atsushi Goto Hiroaki Naoe
- 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.18A-004, (Released:2022-08-18)
- 被引用文献数
- 1
Several regions in western Japan experienced a record-breaking early onset of the rainy season called Baiu in mid-May 2021, which is attributed to the northward movement and enhancement of the Baiu frontal zone. This study investigates large-scale atmospheric circulation that contributes to the early onset of Baiu. Diagnostic and statistical analyses based on reanalysis datasets reveal that both enhanced convection over the western Indian Ocean associated with the Madden–Julian oscillation and a blocking high near western Russia promotes the excitation of Rossby waves to propagate downstream along the upper-tropospheric jet, and thus contributing to the northward movement of the Baiu frontal zone. The anomalous convection over the western Indian Ocean and the subtropical western North Pacific also may affect anticyclonic circulation anomalies to the northeast of the Philippines in the lower troposphere, which promotes moisture inflow toward western Japan and consequently intensifies the Baiu frontal zone. Numerical and quantitative analyses of the circulation anomalies near Japan based on a linear baroclinic model confirms the aforementioned results. The results indicate that the anomalous convection over the Asian monsoon region and the blocking high near western Russia are the primary factors contributing to the early onset of Baiu.
- 著者
- Jae-yong Lee Seung-Min Lee Seung-Jae Lee
- 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.18, pp.173-180, 2022 (Released:2022-08-31)
- 参考文献数
- 33
- 被引用文献数
- 1
This study performed 4-day numerical integration in 1-hour intervals using the Weather Research and Forecasting (WRF) model for four major cases of heavy snowfall that occurred from 2020 to 2021. The model-predicted snow depth data were compared with the ground-observed snow depth and the satellite-observed snow cover data and then were statistically verified. The scalar verification results for ground data from the four cases showed a root–mean–square error of 2.55-16.67 cm and a correlation coefficient of 0.48-0.80, whereas the verification results with satellite data showed the correlation coefficients of 0.38-0.60. For categorical verification, using a threshold value of a snow depth exceeding 5 cm, the proportion correct was 90% or higher for ground observations of each case. In addition, in the satellite categorical verification, when the threshold value of the Snow Cover Fraction (SCF) exceeds 0.5, the proportion correct was 50% or more. These results are meaningful because the model snow depth verification methods were devised strategically for the first time using both the snow depth data of the mesoscale ground observation networks and ultra-high-resolution Sentinel-2 satellite data currently available in Korea. The findings of this study will contribute to the development of a high-resolution numerical prediction model and its verification methodology for snowfalls in the Korean Peninsula, eventually leading to increased prediction accuracy and reduced snow damage.
- 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
- vol.18, pp.154-158, 2022 (Released:2022-07-17)
- 参考文献数
- 23
- 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
- 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
- vol.18, pp.147-153, 2022 (Released:2022-07-17)
- 参考文献数
- 23
- 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
- Jae-yong Lee Seung-Min Lee Seung-Jae Lee
- 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.2022-028, (Released:2022-07-19)
- 被引用文献数
- 1
This study performed 4-day numerical integration in 1-hour intervals using the Weather Research and Forecasting (WRF) model for four major cases of heavy snowfall that occurred from 2020 to 2021. The model-predicted snow depth data were compared with the ground-observed snow depth and the satellite-observed snow cover data and then were statistically verified. The scalar verification results for ground data from the four cases showed a root–mean–square error of 2.55-16.67 cm and a correlation coefficient of 0.48-0.80, whereas the verification results with satellite data showed the correlation coefficients of 0.38-0.60. For categorical verification, using a threshold value of a snow depth exceeding 5 cm, the proportion correct was 90% or higher for ground observations of each case. In addition, in the satellite categorical verification, when the threshold value of the Snow Cover Fraction (SCF) exceeds 0.5, the proportion correct was 50% or more. These results are meaningful because the model snow depth verification methods were devised strategically for the first time using both the snow depth data of the mesoscale ground observation networks and ultra-high-resolution Sentinel-2 satellite data currently available in Korea. The findings of this study will contribute to the development of a high-resolution numerical prediction model and its verification methodology for snowfalls in the Korean Peninsula, eventually leading to increased prediction accuracy and reduced snow damage.
- 著者
- Yiming Sun Qizhong Wu Lanning Wang Baogang Zhang Pingzhong Yan Lingling Wang Huaqiong Cheng Mengfei Lv Nan Wang Shuangliang Ma
- 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.18, pp.135-139, 2022 (Released:2022-07-06)
- 参考文献数
- 17
- 被引用文献数
- 1
The numbers of heavy air pollution events per year in Beijing have decreased significantly since 2017. To find out the reasons and how meteorology and emissions control have played a role in this change, we used the WRF-SMOKE-CMAQ modeling system to reconstruct the characteristics of the fine particulate matter (PM2.5) concentrations from 2013 to 2019. The model system performed well, and the correlation coefficients (R) between the simulated and observed daily PM2.5 concentrations were all above 0.64. The model results also show that the meteorology contributed approximately ±5 g/m3 to the annual average PM2.5 concentrations. More interestingly, the coincidence degrees of the simulated PM2.5 concentrations to the heavy pollution (daily PM2.5 concentration > 150 g/m3) dates decreased significantly after 2016. Meteorology plays an important role in reducing the number of heavy pollution days. According to the model results under the same emission scenarios, the average numbers of heavy pollution days from 2017 to 2019 decreased by 33% compared to the period from 2013 to 2016, while the numbers of good days changed by less than 1%. These results also indicate that meteorology made a significant contribution to decreasing the number of heavily polluted days after 2016.
- 著者
- Zuowei Xie Zelun Cheng Cholaw Bueh Mei Yong Chenglai Wu Purevjav Gomboluudev
- 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.2022-026, (Released:2022-07-01)
- 被引用文献数
- 1
This study examines the pattern transition of dust events identified based on dust RGB images from the Himawari-8 satellite, along with associated key circulations and dynamic features, during spring 2016-2020. The dust RGB images are ordered onto a 4 × 3 topological map according to the spatial similarity of the dust distribution using self-organizing maps. In this topological map, the dust distribution exhibits mainly an eastward displacement or amplification from the Taklimakan Desert to the Gobi Desert. The key circulation triggering the transition of dust pattern is the large-scale tilted ridge from Xinjiang to Siberia. Such a northeast–southwest-oriented ridge conveys cold air into Tibet and causes the near-surface Siberian high extending southward from the Sayan mountains to central China. Consequently, dust intrudes from the Gobi Desert into northern China. In contrast, a zonal “+ – +” wave train in the upper troposphere confines the near-surface high over western Siberia and induces the near-surface cyclogenesis over Mongolia and northern China. As a result, the dust is mainly concentrated over the Taklimakan Desert, with weak influence over Mongolia and northern China.
- 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.