著者

Le Duc Takuya Kawabata Kazuo Saito Tsutao Oizumi

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.17, pp.41-47, 2021 (Released:2021-03-08)

参考文献数

21

被引用文献数

8 15

---

Forecast performances of the July 2020 Kyushu heavy rain have been revisited with the aim of improving the forecasts for this event. While the Japan Meteorological Agency's (JMA) deterministic forecasts were relatively good, the JMA's ensemble forecasts somehow missed this event. Our approach is to introduce flow-dependence into assimilation by running a 1000-member local ensemble transform Kalman filter (LETKF1000) to extract more information from observations and to better quantify forecast uncertainties. To save computational costs, vertical localization is removed in running LETKF1000. Qualitative and quantitative verifications show that the LETKF1000 forecasts outperform the operational forecasts both in deterministic and probabilistic forecasts.Rather than a trick to save computational costs, removal of vertical localization is shown to be the main contribution to the outperformance of LETKF1000. If vertical localization is removed, forecasts with similar performances can be obtained with 100 ensemble members. We hypothesize that running ensemble Kalman filters with around 1000 ensemble members is more effective if vertical localization is removed at the same time. Since this study examines only one case, to assess benefit of removing vertical localization rigorously when the number of ensemble members is around 1000, a larger set of cases needs to be considered in future.

著者

Kazuo Saito

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.222-227, 2019 (Released:2019-11-12)

参考文献数

27

被引用文献数

8

---

It is well known that northward winds are often observed at southern coastal areas of Japan when a developed tropical cyclone is located off the south coast of Japan. These northward winds have been frequently referred to the northward emission of warm and humid air from the typhoon which cause pre-typhoon rainfalls, but their mechanism has not been clarified. In this paper, we show that the northward wind can be explained by the ageostrophic wind components dynamically induced by acceleration vector round the tropical cyclone. On 7 October 2009, when a developed typhoon (T0918 Melor) approached Japan, distinct northward winds were observed at aerological observations over western Japan. Using numerical simulations with the Japan Meteorological Agency nonhydrostatic model, we reproduced the observed northward wind and their mechanism were examined by numerical experiments. The origin of the northward winds is explained by the ageostrophic winds dynamically induced by the acceleration vectors. When a typhoon approaches a baroclinic zone from south, northeastward ageostrophic winds are induced by southeastward acceleration vectors. Other possible causes (diabatic heating and orographic effect) are examined by sensitivity experiments. Diabatic heating by moist process acts to enhance the ageostrophic winds but the role is not primary. Orography has little effect on the observed ageostrophic wind. Non-axisymmetric features of the upper level divergence flow of a tropical cyclone near a baroclinic zone can also be elucidated by the similar mechanism of the ageostrophic winds.

著者

Kazuo Saito

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2019-040, (Released:2019-10-10)

被引用文献数

8

---

It is well known that northward winds are often observed at southern coastal areas of Japan when a developed tropical cyclone is located off the south coast of Japan. These northward winds have been frequently referred to the northward emission of warm and humid air from the typhoon which cause pre-typhoon rainfalls, but their mechanism has not been clarified. In this paper, we show that the northward wind can be explained by the ageostrophic wind components dynamically induced by acceleration vector round the tropical cyclone.On 7th October 2009, when a developed typhoon (T0918 Melor) approached Japan, distinct northward winds were observed at aerological observations over western Japan. Using numerical simulations with the Japan Meteorological Agency nonhydrostatic model, we reproduced the observed northward wind and their mechanism were examined by numerical experiments.The origin of the northward winds is explained by the ageostrophic winds dynamically induced by the acceleration vectors. When a typhoon approaches a baroclinic zone from south, northeastward ageostrophic winds are induced by southeastward acceleration vectors. Other possible causes (diabatic heating and orographic effect) are examined by sensitivity experiments. Diabatic heating by moist process acts to enhance the ageostrophic winds but the role is not primary. Orography has little effect on the observed ageostrophic wind.Non-axisymmetric features of the upper level divergence flow of a tropical cyclone near a baroclinic zone can also be elucidated by the similar mechanism of the ageostrophic winds.

著者

Kazuo Saito Takumi Matsunobu Tsutao Oizumi

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.18, pp.81-87, 2022 (Released:2022-04-25)

参考文献数

26

被引用文献数

3

---

As a complement work to the authors' previous studies, we examined the pre-typhoon rainfalls (PRE) ahead of typhoon T0918 (Melor) in October 2009. The influence of moistening in the upper atmosphere induced by the northward ageostrophic winds on PRE precipitation was examined by a sensitivity experiment using a cloud resolving model with a horizontal resolution of 2 km. The cloud resolving simulation showed a large impact of the water vapor in the upper atmosphere on the precipitation over western Japan. In the sensitivity experiment where the moisture in the middle and upper layers was reduced over the area off the south coast of western Japan, the water vapor reduction area was advected northward, and the snow in the middle and upper layers and the cloud ice in the upper layer decreased, reducing the rain below the melting level. The intrusion of drying air into the upper atmosphere reduced the thickness of the moist absolutely unstable layer (MAUL), and the maximum intensity of convective updrafts decreased by about 10% in the test experiment. In this case, the increase of rain in PRE was primarily caused by the deep northward water vapor transport which yielded a large amount of condensation in the middle and upper layers, and change of moist instability in the upper atmosphere subsidiarily enhanced the convective updrafts.

著者

Kazuo Saito Takumi Matsunobu Tsutao Oizumi

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2022-014, (Released:2022-04-06)

被引用文献数

3

---

As a complement work to the authors' previous studies, we examined the pre-typhoon rainfalls (PRE) ahead of typhoon T0918 (Melor) in October 2009. The influence of moistening in the upper atmosphere induced by the northward ageostrophic winds on PRE precipitation was examined by a sensitivity experiment using a cloud resolving model with a horizontal resolution of 2 km. The cloud resolving simulation showed a large impact of the water vapor in the upper atmosphere on the precipitation over western Japan. In the sensitivity experiment where the moisture in the middle and upper layers was reduced over the area off the south coast of western Japan, the water vapor reduction area was advected northward, and the snow in the middle and upper layers and the cloud ice in the upper layer decreased, reducing the rain below the melting level. The intrusion of drying air into the upper atmosphere reduced the thickness of the moist absolutely unstable layer (MAUL), and the maximum intensity of convective updrafts decreased by about 10% in the test experiment. In this case, the increase of rain in PRE was primarily caused by the deep northward water vapor transport which yielded a large amount of condensation in the middle and upper layers, and change of moist instability in the upper atmosphere subsidiarily enhanced the convective updrafts.

著者

Kazuo Saito Takumi Matsunobu

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.16, pp.198-205, 2020 (Released:2020-11-04)

参考文献数

25

被引用文献数

5

---

Heavy rainfalls often occur when a tropical cyclone (TC) exists on the sea off the south coast. These pre-typhoon rainfalls (PRE) is associated with the northward moisture transport ahead of the TC. In this paper, we examine the northward moisture transport by the ageostrophic winds associated with typhoon T0918 (Melor) and its impact on PRE. According to a numerical simulation conducted in the previous study (Saito 2019), we analyzed the northward moisture fluxes by reproduced geostrophic and ageostrophic winds. Although the southerly ageostrophic winds are dominant mainly in the upper levels, the ageostrophic winds contribute to enhance the poleward water vapor transport for the upper and middle levels above 3 km. To see the impact of the ageostrophic moisture transport on PRE, we conducted a sensitivity experiment where the model moisture in middle and upper levels over the sea off the south coast of western Japan was reduced. Precipitation over western Japan was decreased about 30% when the contributions in moisture fluxes by ageostrophic winds were removed. This result suggests that the northward ageostrophic winds associated with a TC enhance PRE by moistening the middle and upper atmosphere.

著者

Kazuo Saito Takumi Matsunobu

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2020-034, (Released:2020-09-11)

被引用文献数

5

---

Heavy rainfalls often occur when a tropical cyclone (TC) exists on the sea off the south coast. These pre-typhoon rainfalls (PRE) is associated with the northward moisture transport ahead of the TC. In this paper, we examine the northward moisture transport by the ageostrophic winds associated with typhoon T0918 (Melor) and its impact on PRE. According to a numerical simulation conducted in the previous study (Saito 2019), we analyzed the northward moisture fluxes by reproduced geostrophic and ageostrophic winds. Although the southerly ageostrophic winds are dominant mainly in the upper levels, the ageostrophic winds contribute to enhance the poleward water vapor transport for the upper and middle levels above 3 km.To see the impact of the ageostrophic moisture transport on PRE, we conducted a sensitivity experiment where the model moisture in middle and upper levels over the sea off the south coast of western Japan was reduced. Precipitation over western Japan was decreased about 30% when the contributions in moisture fluxes by ageostrophic winds were removed. This result suggests that the northward ageostrophic winds associated with a TC enhance PRE by moistening the middle and upper atmosphere.

著者

Tsutao OIZUMI Kazuo SAITO Junshi ITO Thoru KURODA Le DUC

出版者

Meteorological Society of Japan

雑誌

Journal of the Meteorological Society of Japan. Ser. II (ISSN:00261165)

巻号頁・発行日

pp.2018-006, (Released:2017-11-30)

被引用文献数

9

---

An intense rainband associated with Typhoon 1326 (Wipha) induced a fatal debris flow on Izu Oshima, Japan, on October 15-16, 2013. This rainband formed along a local front between the southeasterly humid warm air around the typhoon and the northeasterly cold air from the Kanto Plain. In this paper, the Japan Meteorological Agency Nonhydrostatic Model was optimized for the “K computer,” and ultra-high-resolution (500-250 m grid spacing) numerical simulations of the rainband with a large domain were conducted. Two of main factors that affect a numerical weather prediction (NWP) model, (1) grid spacing and (2) planetary boundary layer (PBL) schemes [Mellor–Yamada–Nakanishi–Niino (MYNN) and Deardorff (DD)], were investigated. Experiments with DD (Exps_DD: grid spacings of 2 km, 500 m, and 250 m) showed better reproducibility of the rainband position than experiments with MYNN (Exps_MYNN: grid spacings of 5 km, 2 km, and 500 m). Exps_DD simulated distinct convective-scale up/downdraft pairs on the southeast/northwest sides of the front, whereas those of Exps_MYNN were not clear. Exps_DD yielded stronger cold pools near the surface than did Exps_MYNN. These differences in the boundary layer structures likely had a large impact on the position of the front and the associated rainband. Exps_DD with the 500-m grid spacing showed the best precipitation performance according to the Fractions Skill Score. To check other factors of the precipitation forecast, model domain sizes, lateral boundary conditions in nesting simulations, and terrain representations were investigated. In the small domain experiments, the rainband shapes were very different from the observations. In the experiment using a nesting procedure, the deterioration of the forecast performance was acceptably reduced. The model with fine terrains better reproduced the intense rain over the island. These results demonstrate that the ultra-high-resolution NWP model with a large domain has the possibility to improve predictions of heavy rain.

著者

Kazuo Saito Maki Koyama Atsuko Ishida Toshiko Futaki

出版者

Japanese Association of Occupational Therapists

雑誌

Asian Journal of Occupational Therapy (ISSN:13473476)

巻号頁・発行日

vol.17, no.1, pp.31-35, 2021 (Released:2021-04-23)

参考文献数

10

被引用文献数

1

---

Purpose: The objectives of this study were to quantitatively analyze the reaction patterns of ataxia and Parkinson's disease cases that are cognitively harmless and to examine the characteristics of pathological reactions, such as ataxia, rigidity, and motor control, compared to the patterns of a healthy subject.Methods: An eye–hand coordination pointing with pencil test (EHCPPT) app was developed that requires patients to tap a bullseye target with a pencil for screening testing. This app is intended to be used during regular check-ups of the elderly to help them maintain their home lifestyle through self-management of health. The EHCPPT consists of two tasks, both of which require the patient to tap a bullseye target as a test of eye–hand coordination in response to a stimulus sound. In one task, the sound is repeated rhythmically; in the other, it is generated irregularly and infrequently. The EHCPPT app is based on the “oddball paradigm” experimental design and can be administered in just a few minutes to measure the time lag between the sounds and taps as well as the distance between the target and tapped locations automatically.Results: The data generated when the app was used by a healthy subject, an ataxia patient, and a patient with Parkinson's disease were analyzed. In each case, the data exhibited a distinctive pattern.Conclusion: The EHCPPT app is simple and fast and shows potential as a screening test.

著者

Le Duc Takuya Kawabata Kazuo Saito Tsutao Oizumi

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2021-007, (Released:2021-01-29)

被引用文献数

15

---

Forecast performances of the July 2020 Kyushu heavy rain have been revisited with the aim of improving the forecasts for this event. While the Japan Meteorological Agency's (JMA) deterministic forecasts were relatively good, the JMA's ensemble forecasts somehow missed this event. Our approach is to introduce flow-dependence into assimilation by running a 1000-member local ensemble transform Kalman filter (LETKF1000) to extract more information from observations and to better quantify forecast uncertainties. To save computational costs, vertical localization is removed in running LETKF1000. Qualitative and quantitative verifications show that the LETKF1000 forecasts outperform the operational forecasts both in deterministic and probabilistic forecasts.Rather than a trick to save computational costs, removal of vertical localization is shown to be the main contribution to the outperformance of LETKF1000. If vertical localization is removed, forecasts with similar performances can be obtained with 100 ensemble members. We hypothesize that running ensemble Kalman filters with around 1000 ensemble members is more effective if vertical localization is removed at the same time. Since this study examines only one case, to assess benefit of removing vertical localization rigorously when the number of ensemble members is around 1000, a larger set of cases needs to be considered in future.

著者

Hiromu Seko Kazuo Saito Masaru Kunii Masayuki Kyouda

出版者

(公社)日本気象学会

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.5, pp.57-60, 2009 (Released:2009-04-15)

参考文献数

11

被引用文献数

2 6 4

---

Energy Helicity Index (EHI), defined by the product of Convective Available Potential Energy (CAPE) and Storm Relative Environmental Helicity (SREH), is one of potential parameters to diagnose the possibility of tornado outbreak. In this study, probabilities that EHI exceed some criteria were examined with a mesoscale ensemble prediction system, whose grid interval was 15 km, in two tornado events in Japan (Nobeoka and Saroma tornado events). High probability regions (HPR, hereafter) of large SREH existed in the northeastern quadrants of a typhoon or a low-pressure system, while HPRs of large CAPE extended along the warm humid airflow from the Pacific Ocean. In the two events, the tornados were formed near HPRs of large EHI, where HPRs of large SREH and CAPE were overlapped. This result indicates the possibility of the probability forecast of the potential parameter for tornado outbreak.

著者

Kazuo Saito Hitoshi Kihara

出版者

Japanese Association of Occupational Therapists

雑誌

Asian Journal of Occupational Therapy (ISSN:13473476)

巻号頁・発行日

vol.12, no.1, pp.23-28, 2016 (Released:2016-09-04)

参考文献数

15

被引用文献数

1 1

---

In the present study, we report two cases of splinting therapy where favorable results were obtained using splinting of two types, consisting of a first step of fixation at PIP joint extension position and DIP joint extension position, followed by a second step of further fixation at DIP joint extension position, followed thereafter by hand therapy on mallet finger. As the first splint flexes the PIP joint, and, further, as the DIP joint is taken as the hyperextension position, it is thought that the ruptured tendon ends sufficiently entwined more than with the conventional splint at the DIP joint extension position. The splinting therapy we used, with its two-type splinting, is thought to have enabled fixation and ROM acquisition that were in tandem with the tendon healing process. This treatment hints at the effectiveness of conservative therapy in the treatment of swan neck deformities and bony mallet finger.

著者

齋藤 一雄 Kazuo Saito

出版者

上越教育大学特別支援教育実践研究センター

雑誌

上越教育大学特別支援教育実践研究センター紀要 (ISSN:13497944)

巻号頁・発行日

vol.19, pp.41-43, 2013-03

著者

斎藤 和夫 サイトウ カズオ Kazuo SAITO

雑誌

札幌大学女子短期大学部紀要<サッポロ ダイガク ジョシ タンキ ダイガクブ キヨウ>. -- (AN00074536)1号 (昭58.2)- = = 通巻21号 (昭58.2)-. -- 札幌 : 札幌大学, 1983.2- 注記: "Sapporo University Women's Junior College journal"のタイトル の種類変更: 裏表紙タイトル(-32・33合併号 (平10.11))→並列タイトル(No . 34 (1999.9)-) ; 表紙の責任表示"札幌大学"は32・33合併号 (平10.11)ま で ; 奥付に表示の編集者: 札幌大学女子短期大学部紀要委員 (-32・33合併 号 (平10.11)) ; 大きさ変更: 26cm (-32・33合併号 (平10.11))→21cm (No . 34 (1999.9)-) ; 出版者: 札幌大学女子短期大学部 (<No. 34 (1999.9)>- ) ISSN: 02888211 別タイトル: Sapporo University Women's Junior College journal 継続前誌: <a href = "/cgi-bin/shsproc?id=AA11395336">札幌大学教養部女子短期大学部紀要. [B]

巻号頁・発行日

vol.38, pp.33-86, 2001-09-28

著者

Augusto José PEREIRA FILHO Felipe VEMADO Kazuo SAITO Hiromu SEKO José Luis FLORES ROJAS Hugo Abi KARAM

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.96A, pp.247-263, 2018 (Released:2018-05-17)

参考文献数

54

被引用文献数

5

---

The Tokyo Metropolitan Area Convection Study (TOMACS) for extreme-weather-resilient cities is a research and development project (RDP) of the World Weather Research Programme (WWRP). TOMACS provided a multiplatform and high spatiotemporal resolution dataset for the present research on three episodes of deep convection in the Tokyo Metropolitan Area (TMA) under its heat island effect and sea breeze circulations. Heavy rainfall episodes of August 26, 2011, and July 23 and August 12, 2013, were simulated with (and without) the tropical town energy budget (T-TEB) model coupled with the advanced regional prediction system (ARPS). The T-TEB/ARPS system used initial and boundary conditions from the Japan Meteorological Agency (JMA) mesoscale analysis data for 24-hour integration runs at 5-km resolution over Japan and at 1-km resolution over TOMACS area. The 1-km resolution hourly rainfall field simulations were verified against the respective automated meteorological data acquisition system (AMeDAS) rain gauge network measurements. Statistics of the Contingency tables were obtained to estimate the critical success index (CSI), probability of detection (POD), and false alarm rate (FAR) as well as the root mean square error (RMSE). The T-TEB/ARPS simulations improved the south and east sea breeze circulations of TMA and its urban heat island effect. The time evolution of CSI scores improved within the advective time scale, whereas dissipation (phase) errors on precipitation RMSE increased with the integration time and were larger than the dispersion (amplitude) errors. The initial and boundary conditions of JMA greatly improved the simulations as compared to the previous ones performed with the outputs of NCEP's global forecast system as indicated by the TOMACS datasets. Thus, the results represent the temporal and spatial evolutions of the atmospheric conditions leading to the development of a deep convection within TOMACS region. Furthermore, TMA is a good testbed to evaluate the urban surface schemes, such as T-TEB in this study.

著者

齋藤 一雄 Kazuo Saito

出版者

上越教育大学特別支援教育実践研究センター

雑誌

上越教育大学特別支援教育実践研究センター紀要 (ISSN:13497944)

巻号頁・発行日

pp.47-48, 2010-03

著者

Takuya Kawabata Kosuke Ito Kazuo Saito

出版者

(公社)日本気象学会

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.10, pp.145-149, 2014 (Released:2014-10-04)

参考文献数

27

被引用文献数

2 5

---

A new 4-dimensional variational data assimilation system with 0.5-km grid spacing (NHM-4DVAR.v3) was developed by integrating the nonhydrostatic storm-scale 4D-Var (NHM-4DVAR.v2) and the Japan Meteorological Agency (JMA) nonhydrostatic model (NHM) based Variational Data Assimilation System (JNoVA). Both systems are based on the JMANHM, but horizontal resolutions, their formulations, adjoint models of physical processes, and observation operators are different. NHM-4DVAR.v3 comprises advantages of both systems: a penalty term, optimization of lateral boundary conditions, and observation operators for advanced observations. This development aimed at improving the forecast accuracy of hazardous weather at meso-γ-scales (5∼20 km). In this paper, the characteristics of NHM-4DVAR.v3 and some results, including the integrated formulations, are presented. An assimilation experiment of actual observations using NHM-4DVAR.v3 with 2-km grid spacing was found to show improvement over NHM-4DVAR.v2 at the same resolution. As a final goal, NHM-4DVAR.v3 was applied with a 0.5-km resolution. The comparison between assimilation results by NHM-4DVAR.v3 with 0.5- and 2-km horizontal resolutions indicates that analyses with super high resolutions can reproduce more detailed atmospheric features such as convective clouds.