著者
Takeshi Enomoto
出版者
Meteorological Society of Japan
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
vol.15A, pp.66-71, 2019 (Released:2019-11-27)
参考文献数
20

The predictability of the Heavy Rain Event in July 2018 is examined by forecast experiments with an operational global atmospheric forecast model. Experiments from different initial times show that the overall rainfall distribution at the peak on 6 July can be predicted from 12 UTC, June 30, and later. In the successful forecasts, the track error of Typhoon Prapiroon against the best track is small. In the experiments with longer lead times, by contrast, the Baiu frontal zone has a northwared bias with less precipitation, and Prapiroon hardly develop and migrates westward. Poor track forecasts seem to be related to the limited vertical development of the vortex. Near surface equivalent potential tempeature and Q-vector analysis show that Prapiroon act to intensify the Baiu frontal zone. In conclusion, the correct track forecast is essential for Baiu frontogenesis and the formation of heavy precipitation in western Japan.
著者
Takeshi Enomoto
出版者
Meteorological Society of Japan
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
pp.15A-012, (Released:2019-10-25)

The predictability of the Heavy Rain Event in July 2018 is examined by forecast experiments with an operational global atmospheric forecast model. Experiments from different initial times show that the overall rainfall distribution at the peak on 6 July can be predicted from 12 UTC, June 30, and later. In the successful forecasts, the track error of Typhoon Prapiroon against the best track is small. In the experiments with longer lead times, by contrast, the Baiu frontal zone has a northwared bias with less precipitation, and Prapiroon hardly develop and migrates westward. Poor track forecasts seem to be related to the limited vertical development of the vortex. Near surface equivalent potential tempeature and Q-vector analysis show that Prapiroon act to intensify the Baiu frontal zone. In conclusion, the correct track forecast is essential for Baiu frontogenesis and the formation of heavy precipitation in western Japan.
著者
Miki Hattori Jun Matsumoto Shin-Ya Ogino Takeshi Enomoto Takemasa Miyoshi
出版者
(公社)日本気象学会
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
vol.12, pp.75-79, 2016 (Released:2016-03-08)
参考文献数
17
被引用文献数
5

The impact of additional radiosonde observations during the Vietnam-Philippines Rainfall Experiment 2010 (VPREX2010) was investigated by performing observing system experiments using the local ensemble transform Kalman filter (LETKF) and the atmospheric general circulation model for the Earth Simulator (AFES). During the experimental period from 15 September to 15 October, 2010, a westward-propagating disturbance was developed in the South China Sea and caused heavy rainfall on the east coast of Vietnam and Hainan Island. By assimilating the additional radiosondes, significant increases in wind speed, temperature and specific humidity were detected in the lower troposphere around the disturbance. In addition, the analysis ensemble spread for meridional wind decreased by 5-25% across the Indochina Peninsula, Philippines Sea and western Pacific to the south of Japan. Moreover, winds became stronger around the disturbance due to the additional observations, and the ensemble spread for wind speed became larger. The results show that the disturbance in an early stage of development was not well detected in the South China Sea without the use of additional radiosonde observations. Therefore, it is suggested that continuous and intensive radiosonde observations in Vietnam and the Philippines are essential for the improvement of the objective analysis of such disturbances.
著者
Yoshimi KAWAI Qoosaku MOTEKI Akira KUWANO-YOSHIDA Takeshi ENOMOTO Atsuyoshi MANDA Hisashi NAKAMURA
出版者
(公社)日本気象学会
雑誌
気象集誌. 第2輯 (ISSN:00261165)
巻号頁・発行日
vol.95, no.2, pp.71-90, 2017 (Released:2017-03-17)
参考文献数
31
被引用文献数
4

The present study investigated how impacts of the inclusion of radiosonde observations conducted locally in the early summer of 2012 over the Kuroshio and Kuroshio Extension (KE) can spread over time across the North Pacific basin to influence the predictability of synoptic and large-scale tropospheric circulation. For that purpose, observing system experiments (OSEs) were performed where each of two extra sets of radiosonde data, one obtained over the East China Sea in mid-May and the other over the KE in early July, was added to an atmospheric ensemble data assimilation system for comparison with the corresponding analyses without those data. The experiments show that the impact of the extra data assimilated propagates eastward mainly due to advection by the subtropical jet (STJ) in May and July. The strong STJ in May allows the upper-tropospheric impact to travel across the basin only within two days. Under the weaker STJ, the corresponding impact in July tends to remain within the western Pacific, until it eventually reaches the eastern portion of the basin. Assimilation of the extra radiosonde data over the Kuroshio or KE can lead to a decrease of pressure over the Gulf of Alaska in both May and July.  Additional forecast experiments based on the OSEs for May revealed that the pressure decrease over the Gulf of Alaska can be traced back to the west of the Alaska Peninsula and to the east of Japan over three days. The impacts that originate on different dates via different paths merge over the central North Pacific, reinforcing the cyclone over the Gulf of Alaska. This study presents examples where the impacts of atmospheric observations over the western boundary current can propagate across the ocean basin through the westerlies to influence the forecast skill in distant regions.
著者
Akira Yamazaki Takeshi Enomoto Takemasa Miyoshi Akira Kuwano-Yoshida Nobumasa Komori
出版者
(公社)日本気象学会
雑誌
SOLA (ISSN:13496476)
巻号頁・発行日
vol.13, pp.41-46, 2017 (Released:2017-03-25)
参考文献数
26
被引用文献数
3

The observation operators in the local ensemble transform Kalman filter (LETKF) were improved to enable use of observations in the vicinity of the poles in the data assimilation system composed of the atmospheric general circulation model for the Earth Simulator (AFES) and the LETKF. The improved observation operators allow to assimilate the observations located south (north) of southernmost (northernmost) Gaussian grid latitudes. An algorithm for searching the nearest observations from an analyzed grid for error covariance localization was also modified to efficiently assimilate observations near the poles.The new algorithms were incorporated into the LETKF, and the impacts of routine radiosonde observations at the South Pole during the periods of July 2012 and January 2013 were assessed. The radiosonde observations suppressed an artificial expansion of the analysis ensemble spread which occasionally caused numerical instability in the upper troposphere and the lower stratosphere over the Antarctic regions. The analysis was also improved in the Antarctic regions.
著者
Takeshi ENOMOTO Shozo YAMANE Wataru OHFUCHI
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.93, no.2, pp.199-213, 2015 (Released:2015-05-14)
参考文献数
31
被引用文献数
3 5

Simple methods are formulated using an ensemble forecast to identify the sensitive initial perturbations that grow in a specified region at the verification time. These methods do not require the tangent-linear or adjoint models, but use an ensemble forecast to obtain approximated solutions. Input to the sensitivity calculation can be any ensemble forecast integrated from initial conditions perturbed with the bred vector, singular vector, or ensemble Kalman filter methods. Two formulations are presented here to approximate the adjoint and singular vector methods using an ensemble forecast. The ensemble singular vector sensitivity, which has already been applied in previous studies, is obtained with a single eigenvector calculation. The ensemble adjoint sensitivity only requires an even simpler matrix-vector multiplication. To validate the formulations, ensemble-based sensitivity analysis has been conducted in a few cases. First, the two methods were applied to identify the sensitive initial perturbations that grow in the verification region over Japan in January and August 2003. The first singular vector mode indeed achieves the largest amplitude at the verification time, but that is not necessarily true after the verification time. Both methods can identify the sensitive regions more specifically than the regions with large ensemble spread in cases with a mid-latitude cyclone and with a tropical cyclone. The monthly-mean sensitivity in January 2003 indicates the effect of Rossby waves and synoptic disturbances in upstream sensitive regions over Siberia, Tibet, and a downstream sensitive region in the north-western Pacific; the sensitivity in August 2003 suggests the influence of the Asian summer monsoon. Next, for an August 2002 storm case in Europe, global 20-km resolution simulations were conducted from the initial conditions perturbed by the ensemble singular vector method to compare with the unperturbed simulation. In the perturbed simulation, the cyclone is deeper by a few hPa in its north-east sector with more precipitation north of the Alps more consistently with observations. These results indicate that reasonable sensitive regions can be identified with our methods.
著者
Kentaro Takai Takeshi Enomoto
出版者
The Pharmaceutical Society of Japan
雑誌
Chemical and Pharmaceutical Bulletin (ISSN:00092363)
巻号頁・発行日
vol.66, no.1, pp.37-44, 2018-01-01 (Released:2018-01-01)
参考文献数
67
被引用文献数
1

Among the muscarinic acetylcholine receptor (mAChR) subtypes, the M4 receptor has been investigated as a promising drug target for the treatment of schizophrenia. These investigations have been based on findings from M4-deficient mice studies as well as on the results of a clinical trial that used xanomeline, an M1/M4 mAChRs-preferring agonist. Both orthosteric agonists and positive allosteric modulators of M4 mAChR have been reported as promising ligands that not only have antipsychotic effects, but can also improve cognitive impairment and motor dysfunction. However, challenges remain due to the high homology of the orthosteric binding site among all muscarinic receptors. In this review, we summarize our approach to the identification of M4 mAChR activators, orthosteric agonists, and positive allosteric modulators based on M4 mAChR structural information and structure–activity relationship studies. These findings indicate that selective M4 mAChR activators are promising potential therapeutic agents for several central nervous system conditions.