著者

STEVENS Bjorn ACQUISTAPACE Claudia HANSEN Akio HEINZE Rieke KLINGER Carolin KLOCKE Daniel RYBKA Harald SCHUBOTZ Wiebke WINDMILLER Julia ADAMIDIS Panagiotis ARKA Ioanna BARLAKAS Vasileios BIERCAMP Joachim BRUECK Matthias BRUNE Sebastian BUEHLER Stefan A. BURKHARDT Ulrike CIONI Guido COSTA-SURÓS Montserrat CREWELL Susanne CRÜGER Traute DENEKE Hartwig FRIEDERICHS Petra HENKEN Cintia Carbajal HOHENEGGER Cathy JACOB Marek JAKUB Fabian KALTHOFF Norbert KÖHLER Martin LAAR Thirza W. van LI Puxi LÖHNERT Ulrich MACKE Andreas MADENACH Nils MAYER Bernhard NAM Christine NAUMANN Ann Kristin PETERS Karsten POLL Stefan QUAAS Johannes RÖBER Niklas ROCHETIN Nicolas SCHECK Leonhard SCHEMANN Vera SCHNITT Sabrina SEIFERT Axel SENF Fabian SHAPKALIJEVSKI Metodija SIMMER Clemens SINGH Shweta SOURDEVAL Odran SPICKERMANN Dela STRANDGREN Johan TESSIOT Octave VERCAUTEREN Nikki VIAL Jessica VOIGT Aiko ZÄNGL Günter

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2020-021, (Released:2020-01-28)

被引用文献数

85

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More than one hundred days were simulated over very large domains with fine (0.156 km to 2.5 km) grid spacing for realistic conditions to test the hypothesis that storm (kilometer) and large-eddy (hectometer) resolving simulations would provide an improved representation of clouds and precipitation in atmospheric simulations. At scales that resolve convective storms (storm-resolving for short) scales, the vertical velocity variance becomes resolved and a better physical basis is achieved for representing clouds and precipitation. Similar to past studies we find an improved representation of precipitation at kilometer scales, as compared to models with parameterised convection. The main precipitation features (location, diurnal cycle and spatial propagation) are well captured already at kilometer scales, and refining resolution to hectometer scales does not substantially change the simulations in these respects. It does, however, lead to a reduction in the precipitation on the time-scales considered – most notably over the Tropical ocean. Changes in the distribution of precipitation, with less frequent extremes are also found in simulations incorporating hecto-meter scales. Hectometer scales appear more important for the representation of clouds, and make it possible to capture many important aspects of the cloud field, from the vertical distribution of cloud cover, to the distribution of cloud sizes, to the diel (daily) cycle. Qualitative improvements, particularly in the ability to differentiate cumulus from stratiform clouds, are seen when reducing the grid spacing from kilometer to hectometer scales. At the hectometer scale new challenges arise, but the similarity of observed and simulated scales, and the more direct connection between the circulation and the unconstrained degrees of freedom make these challenges less daunting. This quality, combined with an already improved simulation as compared to more parameterised models, underpins our conviction that the use and further development of storm-resolving models offers exciting opportunities for advancing understanding of climate and climate change.

著者

Tetsuya Takemi Takashi Unuma

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15A, pp.60-65, 2019 (Released:2019-09-19)

参考文献数

32

被引用文献数

25

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This study documented the environmental properties of precipitation systems that produced the July 2018 Heavy Rainfall event in Japan. The gridded analysis data were used to diagnose the potential for the development of convective systems in terms of thermodynamic environmental indices. Precipitable water vapor was extremely larger than that seen in the climatology of warm-season quasi-stationary convective clusters (QSCCs). Such an extreme moisture content was realized by very humid conditions at the middle-levels. In contrast, temperature lapse rate in a convectively unstable layer was not so significant in comparison to the QSCC climatology. Among the environmental indices, K Index was shown to describe the potential for the rainfall development. Based on the analysis, the roles of moisture content and profile on the convection development were discussed. It was suggested that the middle-level high humidity contributes to the occurrence of the present heavy rainfall by minimizing negative effects of environmental mixing and by decreasing vertical displacements to reach levels of free convection. In regions where heavy rainfall occurred, an automated algorithm detected the development of QSCCs, which were mostly categorized as a linear type.

著者

Yusuke Goto Naoki Sato

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2022-002, (Released:2021-12-21)

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The horizontal movement vectors of the maximum rainfall area associated with local heavy rainfall around Tokyo in the afternoon of high-temperature summer days were analyzed using a numerical algorithm in order to investigate their relationship to the wind vectors in the free atmosphere. First, the movement vectors were objectively identified every 10 minutes from radar echo intensity data, and their time average from the onset to the termination of a heavy rainfall event was calculated. The results show that the maximum areas of localized heavy rainfall around Tokyo most frequently move to the east-southeast and southeast. Moreover, the direction of movement is shifted to the right relative to the mean direction of the free atmospheric winds in most cases. It is also implied that water vapor supply from the south in the boundary layer plays a role in the rightward movement.

著者

KAWABATA Yasuhiro YAMAGUCHI Munehiko

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2020-042, (Released:2020-05-18)

被引用文献数

2 3

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The effectiveness of the probability ellipse for tropical cyclone (TC) track forecasts is investigated with multiple ensembles from the Japan Meteorological Agency (JMA), the European Centre for Medium-Range Weather Forecasts, the U.S. National Centers for Environmental Prediction, and the Met Office in the United Kingdom. All TCs during the 3 years from 2016 to 2018 are included in the verification. We show that the multiple ensembles composed of these four global ensembles are capable of predicting the situation-dependent uncertainties of TC track forecasts appropriately in both the along-track and cross-track directions. The use of a probability circle involves the implicit assumption of an isotropic error distribution, whereas the introduction of the probability ellipse makes it possible to provide information as to which is more uncertain; the direction or the speed of TC movement. Compared to the probability circle adopted operationally at JMA, the probability ellipse can potentially reduce the area by 16, 15, and 24 %, on average, at forecast times of 3, 4, and 5 days, respectively. This indicates that narrowing warning areas of TC track forecasts by the probability ellipse enables us to enhance disaster prevention/mitigation measures.

著者

KATO Teruyuki

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2020-029, (Released:2020-03-24)

被引用文献数

49

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In Japan, localized heavy rainfall events producing accumulated three-hour precipitation amounts larger than 200 mm are often observed to cause severe landslides and floods. Such events are mainly brought by quasi-stationary band-shaped precipitation systems, named “senjo-kousuitai” in Japanese. Senjo-kousuitai is defined as a band-shaped heavy rainfall area with a length of 50-300 km and a width of 20-50 km, produced by successively formed and developed convective cells, lining up to organize multi-cell clusters, and passing or stagnating at almost the same place for a few hours. The formation processes of senjo-kousuitai are categorized mainly into two types; the broken line type in which convective cells simultaneously form on a quasi-stationary local front by the inflow of warm and humid air, and the back building type in which new convective cells successively forming on the upstream side of low-level winds linearly organize with pre-existing cells. In this study, previous studies of band-shaped precipitation systems are reviewed, and the numerical reproducibility of senjo-kousuitai events and the favorable conditions for their occurrence are examined. In a case of Hiroshima heavy rainfall observed in western Japan on 20 August 2014, the reproduction of the senjo-kousuitai requires a horizontal resolution of at least 2 km, which is sufficient to roughly resolve the formation and development processes of convective cells, while a resolution of 250-500 m is necessary to accurately reproduce their inner core structures. The 2-km model quantitatively reproduced the Hiroshima case when initial conditions 10 hours before the event were used, but the predicted amounts of maximum accumulated precipitation were considerably reduced as the initial time became closer to the occurrence time of the senjo-kousuitai. This reduction was brought from the excessive inflow of low-level dry air that shifted occurrence areas of new multi-cell clusters.  Six favorable occurrence conditions of senjo-kousuitai events for their diagnostic forecasts were statistically constructed from environmental atmospheric fields in previous localized heavy rainfall events. Two conditions of (1) large water vapor flux amounts (> 150 g m−2 s−1) and (2) short distances to the level of free convection (< 1000 m) were chosen representatively for the low-level water vapor field that is judged based on 500-m height data. Four other favorable conditions are selected; (3) high relative humidity at midlevels (> 60 % at 500 hPa and 700 hPa), (4) large vertical shear estimated from the storm relative environmental helicity (> 100 m2 s−2), (5) synoptic-scale ascending areas (400 km mean field at 700 hPa), and (6) the exclusion of warm air advection frequently appearing at 700-850 hPa and inhibiting the development of convection (i.e., an equilibrium level > 3000 m).

著者

Axel GABRIEL Dieter PETERS

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.86, no.5, pp.613-631, 2008 (Released:2008-11-13)

参考文献数

16

被引用文献数

41 42 26

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The long-term behavior of Rossby wave breaking (RWB) events is investigated by a diagnosis separating in different asymmetric types of RWB, i.e., cyclonically sheared waves breaking predominantly pole-ward (P1) or equatorward (LC2) and anticyclonically sheared waves breaking predominantly poleward (P2) or equatorward (LC1). Generally, RWB can be identified by meridional overturning of potential vorticity (PV) on specific isentropes, but a separation in poleward or equatorward asymmetry is too difficult based on PV maps alone. For this paper, we use that northward or southward direction of the meridional wave flux component for quasi-stationary Rossby waves indicates cyclonically or anticyclonically sheared RWB. We demonstrate that the magnitude of the meridional wave fluxes gives a reliable measure of the asymmetric types of RWB when combining with PV diagnostics as well as with the geometry of large-scale diffluent/ confluent flow. Based on 45 winter periods of ECMWF Reanalysis (ERA-40), we found two pronounced regions for P1- and LC2-type events, over the northern North Pacific and the northern North Atlantic, and two extended belts of P2- and LC1-type RWB events, over the North Pacific/North America region and the North Atlantic/European-West Asian region. The results reveal that the long-term mean occurrence of poleward RWB is generally as large as that of equatorward RWB with local differences. Since poleward or equatorward RWB events influence different regions efficiently, e.g., by associated cut-off cyclones or anticyclones, the proposed diagnosis gives an important tool for interpreting long-term general circulation patterns and large-scale weather regimes.

著者

Seiji Yukimoto Kunihiko Kodera Rémi Thiéblemont

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.13, pp.53-58, 2017 (Released:2017-04-04)

参考文献数

29

被引用文献数

8

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A delayed response of the winter North Atlantic oscillation (NAO) to the 11-year solar cycle has been observed and modeled in recent studies. However, the mechanisms creating this 2-4-year delay to the solar cycle have still not been well-understood. This study examines the effects of the 11-year solar cycle and the resulting modulation in the strength of the winter stratospheric polar vortex. A coupled atmosphere–ocean general circulation model is used to simulate these effects by introducing a mechanistic forcing in the stratosphere. The intensified stratospheric polar vortex is shown to induce positive and negative ocean temperature anomalies in the North Atlantic Ocean. The positive ocean temperature anomaly migrated northward and was amplified when it approached an oceanic frontal zone approximately 3 years after the forcing became maximum. This delayed ocean response is similar to that observed. The result of this study supports a previous hypothesis that suggests that the 11-year solar cycle signals on the Earth's surface are produced through a downward penetration of the changes in the stratospheric circulation. Furthermore, the spatial structure of the signal is modulated by its interaction with the ocean circulation.

著者

Tetsuya Takemi Toshiya Yoshida Shota Yamasaki Kentaro Hase

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.22-27, 2019 (Released:2019-02-06)

参考文献数

27

被引用文献数

25

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An intense tropical cyclone, Typhoon Jebi (2018), landed the central part of Japan and caused severe damages. Quantitative assessment of strong winds in urban districts under typhoon conditions is important to understand the underlying risks. As a preliminary study, we investigate the influences of densely built urban environments on the occurrence of wind gusts in an urban district of Osaka City during Typhoon Jebi by merging mesoscale meteorological and building-resolving large-eddy simulations (LES). With the successful reproduction of the track and intensity of the typhoon in meteorological simulations, the simulated winds at the boundary-layer top of the LES model are used to quantitatively estimate the wind gusts in the urban district. The maximum wind gust in the analysis area of Osaka was estimated as 60-70 m s−1, which is comparable to the wind speed at the height of about 300 m.

著者

SAITO Kazuo KUNII Masaru ARAKI Kentaro

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2018-027, (Released:2018-02-11)

被引用文献数

10

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Local heavy rainfall of about 100 mm h-1 occurred in Tokyo and Kanagawa Prefecture on 26 August 2011. This rain was brought by a mesoscale convective system (MCS) that developed near a stationary front that slowly moved southward. In an analysis using geostationary multi-purpose satellite rapid scan images and dense automated weather station networks, development of the MCS occurred after the merging of sea breezes from the east (Kashima-nada) and the south (Tokyo Bay). Numerical experiments by the Japan Meteorological Agency (JMA) nonhydrostatic model (NHM) with horizontal resolutions of 10 km and 2 km using mesoscale 4D-VAR analysis of JMA for initial conditions tended to predict the position of intense rainfall areas west of observed positions. In the mesoscale ensemble forecast using perturbations from JMA’s one-week global ensemble prediction system (EPS) forecast, some ensemble members showed enhanced precipitation around Tokyo, but false precipitation areas appeared north of the Kanto and Hokuriku Districts. As an attempt to improve the model forecast, we modified the model, reducing the lower limit of subgrid deviation of water vapor condensation to diagnose the cloudiness for radiation. In the modified model simulation, surface temperatures around Tokyo increased by about 1°C and the position of the intense precipitation was improved, but the false precipitation areas in the Hokuriku District were also enhanced in the ensemble member which brought a better forecast than the control run. We also conducted ensemble prediction using a singular vector method based on NHM. One of the ensemble members unstabilized the lower atmosphere on the windward side of the Kanto District and suppressed the false precipitation in the Hokuriku District, and observed characteristics of the local heavy rainfall were well reproduced by NHM with a horizontal resolution of 2 km. A conceptual model of the initiation of deep convection by the formation of a low-level convergence zone succeeding merging of the two sea breezes from the east and south is proposed based on observations, previous studies, and numerical simulation results. In this event, the northerly ambient wind played an important role on the occurrence of the local heavy rainfall around Tokyo by suppressing the northward intrusion of the sea breeze from the south.

著者

Udai Shimada Munehiko Yamaguchi Shuuji Nishimura

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.16, pp.1-5, 2020 (Released:2020-01-28)

参考文献数

42

被引用文献数

6 8

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Japan Meteorological Agency (JMA) best track data indicate that the number of rapid intensification (RI) tropical cyclone events in the western North Pacific increased from 1987 to 2018. To clarify whether this increase is due to climatological changes or qualitative changes in the data, the long-term trend of RI events in JMA operational Dvorak data, which have been used as the first guess for best track analysis, was investigated. Because the JMA Dvorak analysis procedure has remained almost unchanged since 1987, the temporal homogeneity of the Dvorak data is expected to be much better than that of the best track data. The results showed no discernable trend in Dvorak-based RI events over the 32 years. Although the frequency distribution of 24-h intensity changes changed slightly in the Dvorak analysis, that of the best track data changed significantly; as a result, the frequency of best track-based RI events increased after 2006. JMA started using microwave satellite imagery for best track analysis in 2006. This change likely affected the temporal homogeneity of the best track data. These results suggest that the increase in best track-based RI events was due mainly to qualitative changes related to advances in observational techniques.

著者

GOTO Daisuke UCHIDA Junya

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2022-010, (Released:2021-10-26)

被引用文献数

3

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The process of aerosol rainout in wet deposition induces large uncertainties among atmospheric aerosol simulations, especially for particles in the fine mode. In this study, we performed an intercomparison study of four different rainout schemes on the model (the nonhydrostatic icosahedral atmospheric model or NICAM) to simulate particulate Cs-137 in the emission scenario of the March 2011 accident at the Fukushima Dai-ichi Nuclear Power Plant. The schemes include global climate models (GCMs) approach with a simple tuning parameter to determine the scavenging coefficient, and another optimized for cloud resolving models (CRMs) to account for prognostic precipitation and realistic vertical transport. The third approach was the conventional method under the assumption of a pseudo-first-order approximation based on the surface precipitation flux. The fourth approach was involved in offline chemical transport models (CTMs) with a simplified parametric analysis approach to clouds and precipitation flux. In most experiments, statistical metrics of the Cs-137 concentrations using in-situ measurements were calculated to be within ±30 % (bias), 0.6-0.9 (correlation), 67-112 Bq m−3 (uncertainty), and < 40 % (precision within a factor of 10). The CRM-type method yielded the best results but required a lower limit of tuning parameters to compensate for the results. Both the GCM-type and the conventional methods were also useful by setting proper tuning parameters. The CTM-type yielded better correlation and lower uncertainty but larger negative bias. These analyses suggest overestimation of the conversion rate from cloud droplets into raindrops by the NICAM. However, this cannot be resolved by simply interchanging cloud microphysics schemes. It was found that the sensitivity of the rainout scheme has a stronger influence on the Cs-137 concentration than the different treatments of cloud microphysics. Therefore, to replicate the observed Cs-137 distribution, it is essential to have a better meteorological field as well as a proper rainout scheme.

著者

Akira Kuwano-Yoshida

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.10, pp.199-203, 2014 (Released:2014-12-06)

参考文献数

29

被引用文献数

9 18

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The “Local deepening rate (LDR)”, the local surface pressure tendency, which is normalized by the sine of latitude and similar to the definition of an explosive cyclone, is introduced to extratropical cyclone activity analysis. The LDR has the advantage of being much simpler than conventional methods such as cyclone tracking and time filtering. The time average of positive LDR, which implies cyclone deepening, captures not only individual explosive cyclone's deepening but also the mid-latitude storm track climatology. The probability of explosive deepening, defined as LDR ≥ 1 hPa h-1 and based on ensemble forecasts, accurately represents the deepening potential and provides information regarding the influence area of storms—analogous to the strong wind area used in typhoon forecasts. The LDR can also be used to assess the quality of storm tracks in reanalyses products. In the 20th century reanalysis, the storm track activity, calculated from ensemble mean surface pressure, is too weak before 1910 in the North Pacific, and in the South Pacific low activity is observed up to the end of the 20th century, because of large ensemble spread due to few surface pressure observations.

著者

Nawo Eguchi Kunihiko Kodera

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.6, pp.137-140, 2010 (Released:2010-10-22)

参考文献数

18

被引用文献数

10 24

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The impact of stratospheric sudden warming event in September 2007 on the tropics was investigated based on satellite data (CALIOP, MLS and TRMM PR). Equatorial temperature and water vapor at 100 hPa decreased by about 1 K and 1 ppmv within 10 days, respectively. Changes in tropical clouds are observed together with the occurrence of the SSW as i) frequent formation of higher-level cirrus clouds over the Maritime Continent, to where water vapor was transported from Asian Monsoon and where the lowest temperature occurred, ii) intensification of deep convective activity in the TTL over African continent, and iii) southward shift of the convective clouds over South American continent.

著者

Akihiko Shimpo Kazuto Takemura Shunya Wakamatsu Hiroki Togawa Yasushi Mochizuki Motoaki Takekawa Shotaro Tanaka Kazuya Yamashita Shuhei Maeda Ryuta Kurora Hirokazu Murai Naoko Kitabatake Hiroshige Tsuguti Hitoshi Mukougawa Toshiki Iwasaki Ryuichi Kawamura Masahide Kimoto Izuru Takayabu Yukari N. Takayabu Youichi Tanimoto Toshihiko Hirooka Yukio Masumoto Masahiro Watanabe Kazuhisa Tsuboki Hisashi Nakamura

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15A, pp.13-18, 2019 (Released:2019-06-15)

参考文献数

22

被引用文献数

80

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An extreme rainfall event occurred over western Japan and the adjacent Tokai region mainly in early July, named “the Heavy Rain Event of July 2018”, which caused widespread havoc. It was followed by heat wave that persisted in many regions over Japan in setting the highest temperature on record since 1946 over eastern Japan as the July and summertime means. The rain event was attributable to two extremely moist airflows of tropical origins confluent persistently into western Japan and large-scale ascent along the stationary Baiu front. The heat wave was attributable to the enhanced surface North Pacific Subtropical High and upper-tropospheric Tibetan High, with a prominent barotropic anticyclonic anomaly around the Korean Peninsula. The consecutive occurrence of these extreme events was related to persistent meandering of the upper-level subtropical jet, indicating remote influence from the upstream. The heat wave can also be influenced by enhanced summertime convective activity around the Philippines and possibly by extremely anomalous warmth over the Northern Hemisphere midlatitude in July 2018. The global warming can also influence not only the heat wave but also the rain event, consistent with a long-term increasing trend in intensity of extreme precipitation observed over Japan.

著者

Meiji Honda Akira Yamazaki Akira Kuwano-Yoshida Yusuke Kimura Katsushi Iwamoto

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.12, pp.259-264, 2016 (Released:2016-09-22)

参考文献数

17

被引用文献数

8

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Synoptic conditions causing an extreme snowfall event in the Kanto-Koshin district occurred on 14-15 February 2014 are investigated through a reanalysis data set. Associated with a developing cyclone passing the south coast of Japan, persistent snowfall exceeding more than 24 hours over the Kofu-Basin resulted in 112 cm snowfall at Kofu. Slow progress of the south-coast cyclone also contributed to the long snowfall duration. An anticyclone developed over the northern Japan (∼1032 hPa) also contributed to this extreme snowfall. This anticyclone brought warm and moist air inflow by southeasterlies forming moisture flux convergence over the Kanto-Koshin district on the morning of 14th when snowfall started in the Koshin district in spite that the south-coast cyclone was located to the south of Kyushu. Further, ageostrophic cold northerlies with high pressure extension from the anticyclone by “cold-air damming (CAD)” would suppress warming with the approaching south-coast cyclone and keep snowfall until the morning of 15th. In other four heavy snowfall events at Kofu, snowfall durations were almost 12 hours. Although anticyclone to the north and CAD were identified in each case, the moisture transport from the southeast was not evident and moisture flux convergence was not formed earlier.

著者

Yuta Goto Masaki Satoh

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.18A-003, (Released:2022-03-24)

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

Fumiaki Fujibe Jun Matsumoto

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.17, pp.220-223, 2021 (Released:2021-12-14)

参考文献数

24

被引用文献数

4

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Using vital statistics data from 1995 to 2019, the relationships among interannual variations of total mortality, heat-stroke mortality, and temperature in summer were assessed in an attempt to estimate excess deaths in hot summer years in Japan. The number of deaths in July and August increased by 1.1% for each 1°C increment of summer mean temperature over Japan, with an eight-fold larger range of interannual variation than the more narrowly defined heat-stroke deaths. This fact implies that excess deaths due to heat are about eight times more prevalent than heat-stroke deaths and can be on the order of 10,000 in a hot summer year. Analyses by age group and cause of death indicated that excess deaths are largely associated with cardiovascular and respiratory diseases among elderly people.

著者

Fumiaki Fujibe

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.16, pp.175-179, 2020 (Released:2020-09-29)

参考文献数

21

被引用文献数

8

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Japan underwent a nationwide self-restraint of human activities in spring 2020 to prevent the spread of the COVID-19 infection. In order to evaluate the effect of suppressed human activities on temperature in the Tokyo Metropolitan area, a statistical analysis was made for temperature anomalies during the self-restraint period using hourly data on the AMeDAS network. The temperature anomaly was defined by the departure from the value that would have been observed without self-restraint, estimated from regression analysis for temperatures at surrounding non-urban stations. It was found that the temperature in central Tokyo (Kitanomaru Park) had a negative anomaly of −0.49°C with a 95% confidence range of ±0.19°C on the average over the strong self-restraint period from April to May. The anomaly was larger in the nighttime than in the daytime, and was found in an area spreading for several tens of kilometers, with a decreasing magnitude according to the distance from Tokyo. These facts indicate a possibility that the reduction of anthropogenic heat release during the self-restraint period resulted in substantial decrease of temperature in the Tokyo Metropolitan area.

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

被引用文献数

9

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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)

被引用文献数

9

---

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.