著者

Yoshimitsu CHIKAMOTO Masahide KIMOTO Masayoshi ISHII Masahiro WATANABE Toru NOZAWA Takashi MOCHIZUKI Hiroaki TATEBE Takashi T. SAKAMOTO Yoshiki KOMURO Hideo SHIOGAMA Masato MORI Sayaka YASUNAKA Yukiko IMADA Hiroshi KOYAMA Masato NOZU Fei-fei JIN

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.90A, pp.1-21, 2012 (Released:2012-06-07)

参考文献数

52

被引用文献数

14 24

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Sea surface temperature (SST) predictability in the Pacific on decadal timescales is examined in hindcast experiments using the coupled atmosphere-ocean model MIROC with low, medium, and high resolutions. In these hindcast experiments, initial conditions are obtained from an anomaly assimilation procedure using the observed oceanic temperature and salinity while prescribing natural and anthropogenic forcing based on the IPCC concentration scenarios. Our hindcast experiments show the predictability of SST in the western subtropical Pacific, the Indian Ocean, and the tropics to the North Atlantic. Previous studies have examined the SST predictability in the Indian Ocean and the Atlantic, but SST predictability in the western subtropical Pacific has not been evaluated. In the western Pacific, the observed SST anomalies in the subtropics of both hemispheres increased rapidly from the early 1990s to the early 2000s. While this SST warming in the western subtropical Pacific is partly explained by global warming signals, the predictions of our model initialized in 1995 or 1996 tend to simulate the pattern of the SST increase and the associated precipitation changes. This large climate change around the late 1990s may be related to phenomena such as the recent increase in the typhoon frequency in Taiwan and the weakened East Asian monsoon reported by recent studies.

著者

吉野 正敏

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.38, no.1, pp.27-46, 1960-12-26 (Released:2007-10-19)

参考文献数

31

被引用文献数

4 3

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According to official observation, the maximum rainfall recorded in Japan is 55.9mm in 10 minutes, 87.9mm in 30 minutes, 157.0mm in 1 hour, 415.3mm in 6 hours, 844.5mm in 10 hours, 1, 109mm in 24 hours, 3, 462mm in 1 month and 10, 21.6mm in 1 year, Comparing these amounts with the world records reported by Jennings (1950), it is noticed that maximum rainfall in Japan is comparable only to world figures in the 1∼0 to 24 hour duration. This is thought to be because polar fronts or tropical cyclones in Japan and adjacent areas are stronger in that time period, while convectional rain, such as thunderstorms of short duration, or continuous rain, such as orographic rainfall under monsoonal conditions, are weaker than in another parts of the world. In addition, distribution maps of observed maximum rainfall within 10 minutes, 1 hour, 6 hours and 24 hours were drawn, and the distribution patterns were considered in connection with their causes.The constants, k and n, for an experimental equation of the depth-duration curve, R=ktn, where t is time (in minutes) and R, rainfall amount (in mm), were then calculated. As for the rainfall amount, R, the mean values obtained from the 1 st to the 5 th ranking in the official records of the Japan Meteorological Agency from 1941 to 1950, as observed every 10, 20 and 30 minutes and every 1, 3, 6, 18, 24, and 36 hours for each of the 109 stations in Japan, were used. Separating the time periods into those between 10 minutes and 1 hour and those between 6 and 36 hours, it was shown that the k and n values exhibited a wide range according to geographical regions and the above-mentioned time periods. These facts are shown in the accompanying figures and tables.Finally, the constants, b, k, and n, for an experimental equation for the intensityduration curve, i=k/(t+b)n, where t is time (in minutes) and i, the rainfall intensity (in mm per minute) were obtained by calculating the intensity values by the same method as is described above for the mean rainfall values. The distribution of b, k, and n values revealed marked localization as is shown in the figures attached. The values decrease with distance from the sea coast in central Japan, and are generally smaller on mountain tops than at the bottoms.

著者

秋山 孝子

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.53, no.5, pp.304-316, 1975 (Released:2007-10-19)

参考文献数

6

被引用文献数

31 48

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豪雨期間を含む1972年6月29日から7月14日に至る16日間について,日本列島近傍の水蒸気流束分布•水蒸気収束の状況を解析した.その結果は下記のごとくに要約される.(1)豪雨域の下層(700mb∼地上)で,強い水蒸気流束の収束がみられる.この収束は,下層の水蒸気sink(負のδq/δt,つまり降水)をもたらすと同時に.上向きのωqを通して,上層でのsinkをひきおこす.(2)稠密な雨量観測点から求めた面積平均雨量と,収支計算から求めた降水量は,よい一致を示している.(3)降水量の多寡によって,解析期間を"light","heavy"および"extremely heavy"rainfall periodに分類すると,その各々について,極めて特徴的な水蒸気流束分布が得られた.(4)heavy rainfall periodでは,南西諸島海域からSW-風によって,日本列島上のcloud zoneに流入する水蒸気流束の収束が特徴的である.またこのSW-水蒸気流束は,南西諸島海域で,太平洋上からの湿潤なSE-風によって強化されたものである.(5)extremely heavy rainfall periodでは, cloud zoneによる水蒸気の輸送量は減少し,日本列島の南方から,直接豪雨帯に向うSE-風による, transversalな水蒸気流束がいちじるしく増大し,その収束が,豪雨域内の主な水蒸気sinkとなる.(6)豪雨期間,降雨の水蒸気sourceは,太平洋高気圧によっておおわれている,雲のない亜熱帯海域であることが結論される.

著者

村上 多喜雄 松本 淳

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.72, no.5, pp.719-745, 1994-10-25 (Released:2008-01-31)

参考文献数

38

被引用文献数

151 267

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西部北太平洋における夏のモンスーン(WNPM)は、8月中ごろの最盛期には、東南アジアモンスーン(SEAM)と同程度かそれ以上に活発になる。これら2つの夏のモンスーン地域の境界は、OLRが190Wm-2以下になる両モンスーンの上昇域の間にあって、OLRが230Wm-2以上と比較的高く、相対的な好天域である南シナ海にある。主要な下降域は中部北太平洋にあり、そこでは太平洋高気圧の発散域の上層に、熱帯上部対流圏トラフの収束域が位置している。すなわち、29℃を超える世界でもっとも高い海水温域にあるWNPMの中心地域(北緯10-20度、東経130-150度)では、活発な対流活動が生じ、東経110度付近の南シナ海と、西経140度付近の中部北太平洋との間に、顕著な東西循環が起こっている。この東西循環の鉛直構造は、北緯10-20度付近ではバロクリニックで、東経150度以東では下層が偏東風、上層が偏西風となっており、以西ではこの逆となる。WNPMは、北緯10度から20度付近における海水温の東西コントラストと、北緯20-30度付近における、大陸-海洋間の東西の熱的コントラストの複合作用の結果として生じていると考えられる。WNPM域の極側には大きな大陸がないため、南北の熱的コントラストの影響は、二義的なものとなる。一方SEAMは、主に南北の海陸熱的コントラストによって駆動される、南北循環によって生じている。SEAMは10月初め以前に後退するのに対し、WNPMは29℃を超える高海水温が維持されているため、11月初めまで持続する。

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

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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

KUJI Makoto MURASAKI Atsumi HORI Masahiro SHIOBARA Masataka

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.2018-025, (Released:2018-02-05)

被引用文献数

9

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Cloud fractions were observed during research cruises onboard the research vessel (R/V) Shirase between Japan and Antarctica using a whole-sky camera and a ceilometer. The cruises, Japanese Antarctic Research Expeditions (JARE) 55 and 56, took place from November 2013 to April 2014 and November 2014 to April 2015, respectively. Cloud fractions were estimated from the whole-sky camera based on the sky brightness and spectral characteristics, while the ceilometer recorded the cloud occurrence frequency. According to the comparison of daily-averaged cloud fractions from the whole-sky camera with the ceilometer observations over the open ocean between Japan and Antarctica, the correlation coefficients were 0.87 and 0.93 for JARE 55 and 56, respectively. Overall, the results from both observation methods were consistent over the open ocean. Nevertheless, it was necessary to take surface conditions into consideration, particularly for the estimated cloud fractions from the whole-sky camera, because the contrast in brightness and spectral properties between cloudy and clear skies was lower over the sea ice region, owing to the higher surface albedo. Hence, the classification parameter was expressed as a function of sun elevation over the sea ice region in this study. This parameter was determined from part of the data over the sea ice region during JARE 55 and then applied to JARE 56 as well as to remaining data from JARE 55. As a result, the daily-averaged cloud fractions over the sea ice region were approximately 84% and 57% from JARE 55 and 56, respectively. The daily-averaged cloud fractions estimated from the whole-sky camera were also consistent with the ceilometer observations where the correlation coefficients with the sea ice region were 0.93 and 0.96 for JARE 55 and 56, respectively.

著者

Jing XU Yuqing WANG

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.2018-014, (Released:2017-12-26)

被引用文献数

29

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The dependence of intensification rate (IR) of a tropical cyclone (TC) on its initial structure, including the radius of maximum wind (RMW) and the radial decay rate of tangential wind outside the RMW, is examined based on ensemble of simulations using a nonhydrostatic axisymmetric cloud-resolving model. It is shown that the initial spinup period is shorter and the subsequent IR is larger for the storm with the initially smaller RMW or with the initially more rapid radial decay of tangential wind outside the RMW. The results show that the longevity of the initial spinup period is determined by how quickly the inner-core region becomes nearly saturated in the middle and lower troposphere and thus deep convection near the RMW is initiated and organized. Because of the larger volume and weaker Ekman pumping, the inner-core of the initially larger vortex takes longer time to become saturated and thus experiences a longer initial spinup period. The vortex initially with the larger RMW (with the slower radial decay of tangential wind outside the RMW) has lower inertial stability inside the RMW (higher inertial stability outside the RMW) develops more active convection in the outer-core region and weaker boundary-layer inflow in the inner-core region and thus experiences lower IR during the primary intensification stage.

著者

Guanghua CHEN Ke WANG

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.96, no.2, pp.97-110, 2018 (Released:2018-03-23)

参考文献数

38

被引用文献数

8

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Although both the tropical cyclone (TC) peak seasons in 2016 and 1998 are in the decaying stage of a super El Niño, TC activities over the western North Pacific (WNP) exhibit vast differences. The TCs in 2016 were greater in number and intensity and had distinct monthly variations in TC activity in contrast to those in 1998. The detailed comparison shows that the warm sea surface temperature anomaly over the WNP in 2016 had higher magnitude and a more eastward extension than that in 1998. In August, coincident with the enhanced Madden–Julian oscillation westerly phase, more TCs clustered within the eastward-extending convective belt caused by the southwesterly surge. The mean longitude of TC genesis in 2016 shifted more eastward, which is favorable for the longer lifetime and greater intensity of the TCs. In terms of the extratropical influences, the cyclonic circulation anomaly associated with the Silk Road Pattern from the middle latitude penetrated southward and split the WNP subtropical high (WNPSH) into two components in August of 2016, thus causing deep-tropospheric southerly steering flows in between and TC northward-prone tracks. During the boreal autumn in 2016, the WNPSH strengthened and stretched westward, producing the robust easterly steering flows that led to successive TCs affecting the coastal areas of East Asia.

著者

Yuhei YAMAMOTO Hirohiko ISHIKAWA Yuichiro OKU Zeyong HU

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.96B, pp.59-76, 2018 (Released:2018-03-16)

参考文献数

53

被引用文献数

28

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This paper presents a method for estimating the land surface temperature (LST) from Himawari-8 data. The Advanced Himawari Imager onboard Himawari-8 has three thermal infrared bands in the spectral range of 10-12.5 μm. We developed a nonlinear three-band algorithm (NTB) that makes the best use of these bands to estimate the LST. The formula of the algorithm includes 10 coefficients. The optimum values of these coefficients were derived using a statistical regression method from the simulated data, as obtained by a radiative transfer model. The simulated data sets correspond to a variety of values of LST, as well as surface emissivity, type and season of temperature and water vapor profiles. Viewing zenith angles (VZAs) from 0° to 60° were considered. For the coefficients obtained in this way, we verified the root-mean-square error (RMSE) in terms of the VZA, LST and precipitable water dependence. We showed that the NTB can accurately estimate the LST with an RMSE less than 0.9 K compared with the nonlinear split-window algorithm developed by Sobrino and Romaguera (2004). Moreover, we evaluated the sensitivities of the LST algorithms to the uncertainties in input data by using the dataset independent of the dataset used to obtain coefficients. Consequently, we showed that the NTB has the highest robustness against the uncertainties in input data. Finally, the stepwise LST retrieval method was constructed. This method includes a simple cloud mask procedure and the land surface emissivity estimation. The LST product was evaluated using in-situ data over the Tibetan Plateau, and the validity was confirmed.

著者

Yuhei YAMAMOTO Hirohiko ISHIKAWA

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.96B, pp.43-58, 2018 (Released:2018-03-16)

参考文献数

32

被引用文献数

20

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Land surface emissivity (LSE) in the thermal infrared (TIR) is an essential parameter in the retrieving land surface temperature (LST) from space. This paper describes the LSE maps in three TIR bands (centered at 10.4, 11.2 and 12.4 μm) used for retrieving the LST from Himawari-8. Himawari-8, a next-generation geostationary satellite has high spatial and temporal resolutions compared to previous geostationary satellites. Because of these improvements, the Himawari-8 LST product is expected to contribute to the observation of small-scale environments in high-frequency. In this study, the LSE is estimated by a semi-empirical method, which is a combination of the classification based method and the normalized difference vegetation index (NDVI) thresholds method. The land cover classification information is taken from the Global Land Cover by National Mapping Organizations version3 (GLCNMO 2013). Material emissivities of soil, vegetation and others are taken from the MODIS UCSB emissivity library and the ASTER spectral library. This method basically follows the semi-empirical methods developed by the previous studies, but advanced considerations are added. These considerations are the phenology of vegetation, flooding of paddy fields, snow/ice coverage, and internal reflections (cavity effect) in urban areas. The average cavity effect on LSE in urban canopies is approximately 0.01, but it reaches 0.02 in built-up areas. The sensitivity analysis shows that the total LSE errors for the three bands are less than 0.02. The LSE estimation is especially stable at the vegetation area, where the error is less than 0.01.

著者

Ryo OYAMA Masahiro SAWADA Kazuki SHIMOJI

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.96B, pp.3-26, 2018 (Released:2018-03-16)

参考文献数

56

被引用文献数

9

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The high temporal and spatial resolutions of geostationary satellite observations achieved by recent technological advancements have facilitated the derivation of atmospheric motion vectors (AMVs), even in a tropical cyclone (TC) wherein the winds abruptly change. This study used TCs in the western North Pacific basin to investigate the ability of upper tropospheric AMVs to estimate the TC intensity and structure. We first examined the relationships between the cloud-top wind fields captured by 6-hourly upper tropospheric AMVs derived from images of the Multi-functional Transport Satellite (MTSAT) and the surface maximum sustained wind (MSW) of the Japan Meteorological Agency's best-track data for 44 TCs during 2011-2014. The correlation between the maximum tangential winds of the upper tropospheric AMVs (UMaxWinds) and MSWs was high, approximately 0.73, suggesting that the cyclonic circulation near the cloud top was intensified by the upward transport of absolute angular momentum within the TC inner core. The upper tropospheric AMVs also revealed that the mean radii of UMaxWinds and the maximum radial outflows shifted inward as the TC intensification rate became large, implying that the low-level inflow was strong for TCs undergoing rapid intensification. We further examined the possibility of estimating the MSW using 30-min-interval UMaxWinds derived from Himawari-8 target observations, which have been used to track TCs throughout their lifetimes. A case study considering Typhoon Lionrock (1610) showed that the UMaxWinds captured the changes in the cyclonic circulation near the cloud top within the inner core on a timescale shorter than 1 day. It was apparent that the increase in the UMaxWind was associated with the intensification of the TC warm core and the shrinkage of UMaxWind radius. These results suggest that Himawari-8 AMVs include useful information about TC intensification and related structural changes to support the TC intensity analysis and structure monitoring.

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.96, no.1, pp.1-2, 2018 (Released:2018-02-28)

参考文献数

6

著者

Woosub ROH Masaki SATOH

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.96, no.1, pp.55-63, 2018 (Released:2018-02-08)

参考文献数

34

被引用文献数

10

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As an alternative approach to previous multisensor satellite evaluations for cloud system resolving models (CSRMs), a technique for precipitation clouds over the ocean of CSRMs is presented using combined infrared and microwave channels. This method quantitatively analyzes precipitation clouds using cloud-top temperatures and ice scatterings from infrared 11 μm and high frequency microwave (89.0 GHz) brightness temperatures (TBs). The TB threshold at low frequencies (18.7 GHz) is used to identify precipitation regions. This method extends a previous approach based on tropical rainfall measuring mission (TRMM) precipitation radar which uses a narrow coverage, by incorporating a wide passive microwave sensor swath and ice cloud sensitivity.  The numerical results of the non-hydrostatic icosahedral atmospheric model, NICAM, with two cloud microphysics schemes were evaluated over the tropical open ocean using this method. The scattering intensities in both simulations at 89.0 GHz were different due to the parameterizations of the snow and graupel size distributions. A bimodal snow size distribution improved the TB underestimation at 89.0 GHz. These results exhibited similar structures to the joint histograms of cloud-top temperatures and precipitation-top heights generated using the previous method; the frequencies of overestimated scattering intensities in this study and the frequencies of high precipitation-top heights above 12 km in the previous study. It was observed that the change in the snow size distribution in the cloud microphysics scheme can lead to better agreements of simulated TBs at 89.0 GHz. Furthermore, we investigated the impacts of nonspherical snow assumptions using a satellite simulator. The effect of a nonspherical snow shape in the radiative transfer model caused a smaller change in TBs at 89.0 GHz compared to the difference between the TBs of the two simulations without nonspherical assumptions.

著者

Katsuyuki V. Ooyama

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

vol.60, no.1, pp.369-380, 1982 (Released:2007-10-19)

参考文献数

23

被引用文献数

48 225

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航空機観測の進歩に伴ない,台風の一般構造およびエネルギー収支については,1960年代の初めごろまでに.かなりよくわかってきた。しかし,これらの知識を力学的に統一して台風の生成発達を説明する理論は容易に生れなかった。現在の台風理解の因となった最初の発達理論が出るためには,力学的問題としての台風の認識,特に種々の要因の相対的重要度,を再考する必要があった。雲のパラメータ化が成功の原因のように云われるが,実は,問題認識上の変化がそのような雲の扱いを一応許されるものとした。雲のパラメータ化を技術的にのみ応用すると,その後の種々の線型理論(いわゆるCISK)に見られるような物理的混乱を引きおこす。一方,台風の理解のためには,線型理論は不充分であり,理論の概念としての妥当性および限度は非線型数値モデルによる実験によってのみ評価されることとなった。数値モデルの進歩により,台風成生の理解のためには,雲のパラメータ化を取り除く必要があることもわかってきた。この論文は,歴史を逆転するかの如く見える最近の発展の裏にある真の進歩を概念的に解明することを目的とする。

著者

Michio Yanai Chengfeng Li Zhengshan Song

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

vol.70, no.1B, pp.319-351, 1992-02-25 (Released:2009-03-31)

参考文献数

127

被引用文献数

170 754

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客観解析したFGGE II-b高層観測データを用いて、1978年12月から1979年8月までの9ヶ月間のチベット高原及びその周辺領域の大規模循環場と熱・水蒸気収支の解析を行った。客観解析には、FGGEデータに加えて1979年5月-8月に中国が行った「チベット高原特別気象観測」データも用いた。夏季アジアモンスーンの始まりにつながる冬から夏にかけての顕著な季節変化を同定するために、大規模循環、温度、外向き長波放射(OLR)および鉛直循環の時間的発展を記述した。チベット高原は、熱的に駆動された大規模垂直循環を維持しているが、この循環は地球規模のモンスーン循環とはもともとは別なものである。上昇流は冬には西部高原だけに限られているが、季節の進行とともに高原全域に広がる。アジアモンスーンの始まりは高原が誘導する循環と、北上する主要な降雨帯に伴う循環との相互作用によってもたらされる。冬の期間、高原は冷源となっているが、周囲はさらに強い冷源域となっている。春には高原は熱源となるが、周辺域は引続き冷源である。高原上での主要な熱源は地表からの顕熱輸送である。しかし、その他に凝結熱の貢献も、西部高原では年間を通して、更にもっと重要なことには東部高原ではとりわけ夏に観測されている。持ち上げられた高原表面の顕熱加熱と周辺域の放射冷却によって水平温度傾度が維持され、それが熱的直接循環を生じている。夏季アジアモンスーンへの2つの移行期間-5月の東南アジアのモンスーンの始まりと6月のインドモンスーンの始まり-の上部対流圏の昇温過程を詳しく調べた。その結果、最初のオンセット時の東部高原での気温上昇は、主に、非断熱加熱の結果であるが、次のオンセット時直前のイラン-アフガニスタン-西部高原の気温上昇は、強い下降流によってもたらされていることがわかった。高原上の境界層や垂直循環には大きな日変化が存在する。地表からの加熱によって、高原上では夕方(1200 UTC)に温位がほぼ一様な深い混合層がみられる。このことは熱の垂直輸送に果たす熱対流の役割の重要性を示唆している。しかし、水蒸気は垂直方向にあまり混合しておらず、また、境界層には大きな水平温度傾度がある。晩春から夏にかけて、境界層は乾燥対流に対してより安定となる。一方、晩春以降の相当温位の垂直分布は、下層の水蒸気量の増加に伴って、湿潤対流に対して条件付き不安定な成層を示す。

出版者

Meteorological Society of Japan

雑誌

Journal of the Meteorological Society of Japan. Ser. II (ISSN:21869057)

巻号頁・発行日

pp.2018-005, (Released:2017-11-24)

被引用文献数

28

著者

石田 雅生

出版者

METEOROLOGICAL SOCIETY OF JAPAN

雑誌

氣象集誌. 第1輯 (ISSN:00261165)

巻号頁・発行日

vol.31, no.7, pp.203-210, 1912

著者

SU Shih-Hao KUO Hung-Chi HSU Li-Huan YANG Yi-Ting

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.90, no.5, pp.721-736, 2012

被引用文献数

57

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We studied the temporal and spatial characteristics of extreme typhoon rainfall in Taiwan using Central Weather Bureau hourly precipitation data from 21 surface stations during the past 51 years (1960-2010). Extreme rainfall is defined as 95th percentile intensity of total rain events, or equivalently, rain events greater than 9 mm hr^-1 which contribute 40% to the total rain amount in Taiwan. It was found that approximately 70% (20%) of extreme rain is in the typhoon season (Mei-Yu) from July to October (from May to June). There are significant variations of typhoon extreme rainfall over the annual and decadal time scales, with larger extreme rainfall values and events in the periods of 1960-1976 and 1994-2010, and less in the 1977-1993 period. The recent 1994-2009 period has the most extreme rainfall and events, as well as, inter-annual variability. In contrast, there are strong inter-annual variations of Mei-Yu extreme rainfall, but no significant decadal variations. The averaged typhoon rain intensity, however, is about the same, being 19 mm hr^-1 in all these three periods. Our analysis indicates that the typhoon extreme rainfall spatial pattern is phased locked with the Central Mountain Range, Taiwan. In general, the amount of extreme rainfall was related to the typhoon translation speed and duration time, but not typhoon intensity. Slower speeds and longer duration time lead to larger extreme rainfall values. Our analysis also indicate that the mean duration time of Taiwan landfall typhoons with northern tracks (tracks north of 23 degrees latitude) is about 3 hours longer than that of southern track typhoons in the last 51 years, and is more likely to produce three times as much extreme rainfall. The interactions of summer or winter monsoons with typhoons are also important factors that may contribute to the extreme rainfall in Taiwan. Examples of extreme rainfall due to typhoon circulation interaction with summer and winter monsoon flows are presented. Monsoon water vapor supply, typhoon slow translation speed, and mesoscale convection due to typhoon-monsoon flow interactions are the key factors in extreme precipitation events.

著者

朝倉 慶吉

出版者

METEOROLOGICAL SOCIETY OF JAPAN

雑誌

氣象集誌. 第1輯 (ISSN:00261165)

巻号頁・発行日

vol.16, no.4, pp.178-184, 1897

著者

和田 雄治

出版者

METEOROLOGICAL SOCIETY OF JAPAN

雑誌

氣象集誌. 第1輯 (ISSN:00261165)

巻号頁・発行日

vol.31, no.8, pp.261-277, 1912