A study on quasi-biweekly oscillation around Himalaya, Assam and Bangladesh regions

喜马拉雅、阿萨姆邦和孟加拉国地区准双周振荡研究

• 批准号: 22340137
• 负责人: YASUNARI Tetsuzo
• 金额: $ 11.9万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2010
• 资助国家: 日本
• 起止时间: 2010 至 2012
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-22340137/
• 关键词: アジアモンスーン; 降水; 季節内変動; 準 2 週間周期変動; 気候; 降水変動; 準2週間変動; 準2週間変動(QBW); バングラデシュ; アッサム; 日周期変動; 経年変動; 準2週間周期変動(QBW)

This study elucidated a process of distinct rainfall fluctuation related to quasi-biweekly Oscillation (QBW) over Himalaya-Assam-Bangladesh (HAB) region, where one of the heaviest rainfall is observed in the world, by means of data analysis and a numerical simulation. QBW in rainfall became a dominant mode of intraseasonal oscillation since 1980s around Bangladesh. QBW in rainfall over HAB region is most active, especially in Meghalaya plateau and the western coast of Myanmar, in land areas of Asian monsoon. In active (break) phase of rainfall in QBW in the HAB region, a low-level westerly/southwesterly (easterly/southeasterly) is dominated there. The large zonal wind fluctuation is induced by westward propagating n=1 equatorial Rossby wave with a wave length of ~6000 km. Rainfall in active phase of QBW often shows a remarkable diurnal variation around the Meghalaya plateau.The variation is caused by diurnal variation of low-level jet around 900 hPa. Thestrong low-level flow transports abundant moisture to the southern slope of the Meghalaya Plateau during the active period, which triggers forced lifting and brings orographic rainfall. However, low-level wind during the inactive period is too weak to induce orographic rainfall. Thus, the distinct QBW in HAB region is strongly enhanced locally (~500Km) by the topographical features although atmospheric circulation causing the ISO has horizontal scale of ~6000 Km.

这项研究阐明了与喜马拉雅山 - 阿萨姆 - 邦格拉德什（HAB）地区的准周期振荡（QBW）相关的明显降雨波动的过程，在世界范围内通过数据分析和数值模拟观察到世界上最大的降雨之一。自1980年代以来，降雨中的QBW成为季节内振荡的主要模式。 HAB地区降雨的QBW最活跃，尤其是在亚洲季风的陆地地区，尤其是在梅加拉亚邦高原和缅甸的西海岸。在HAB地区QBW降雨的主动（中断）中，那里的低水平西南/西南（东南/东南）在那里占据了主导地位。向西传播n = 1赤道rossby波，波长约为6000 km，从而引起了较大的区域风波动。 QBW活动阶段的降雨通常显示出梅加拉亚邦高原周围的显着昼夜变化。这种变化是由900 hPa左右的低级喷气机的昼夜变化引起的。在活动期间，Thestrong的低水平流动将大量的水分传递到梅加拉亚高原的南坡上，这会触发强迫提升并带来图形降雨。但是，在不活动期间的低水平风太弱，无法诱发地形降雨。因此，尽管大气环流导致ISO的水平尺度为〜6000 km，但HAB区域中的独特QBW在本地（〜500 km）强烈增强。

项目成果

Verification of Downscaling Framework for Interannual Variation of Tropical Cyclone in Western North Pacific

• DOI: 10.2151/sola.2011-043
• 发表时间: 2011-11
• 期刊: Sola
• 影响因子: 1.9
• 作者: Tomonori Sato;Akira Juri;Kei Masuyama;Eiji Imakita;M. Kimoto

Diurnal Rainfall Pattern Observed by TRMM-PR around the Indochina Peninsula

TRMM-PR 观测到的中南半岛周边日降雨量模式

• 发表时间: 2010
• 期刊: J.Geophys.Res.
• 作者: Hiroshi;G.Takahashi;H.Fujinami;T.Yasunari;J.Matsumoto
• 通讯作者: J.Matsumoto

インド亜大陸北東部に卓越する降水の変動周期について

关于印度次大陆东北部降水波动周期

• 发表时间: 2012
• 作者: 梶川藍;林 泰一
• 通讯作者: 林 泰一

Seasonal and Intraseasonal Variations of Surface Meteorological Factors, and Their Effect on Diarreheal Diseases

地面气象因素的季节和季节内变化及其对腹泻病的影响

• 发表时间: 2010
• 作者: Hayashi;T.;A. Teshima;Y. Wagatsuma;T. Terao;A. S. G. Faruque
• 通讯作者: A. S. G. Faruque

Characteristic intraseasonal oscillation of rainfall and its effects of interannual variability over Bangladesh during boreal summer

北半球夏季孟加拉国降雨的特征季节内振荡及其年际变化的影响

• 发表时间: 2011
• 期刊: Int. J. Climtol
• 作者: Fujinami;H.,D.Hatsuzuka;T.Yasunari;T. Hayashi;T. Terao;F.Murata;M. Kuguchi;Y. Yamane;J. Matsumoto;Md. N. Islam and A .Habib
• 通讯作者: Md. N. Islam and A .Habib