A study on vortex-type low pressure systems around the Meghalaya, Bangladesh and Myanmar region

2017 Fiscal Year Final Research Report

• Project/Area Number: 26400465
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: Nagoya University
• Principal Investigator: FUJINAMI HATSUKI 名古屋大学, 宇宙地球環境研究所, 講師 (60402559)
• Co-Investigator(Renkei-kenkyūsha): YASUNARI TETSUZO 総合地球環境学研究所, 所長 (80115956) ; TSUBOKI KAZUHISA 名古屋大学, 宇宙地球環境研究所, 教授 (90222140) ; HIROSE MASAFUMI 名城大学, 理工学部, 准教授 (40392807)
• Research Collaborator: HATSUZUKA DAISUKE 名古屋大学, 環境学研究科, 大学院生 ; KATO MASAYA 名古屋大学, 宇宙地球環境研究所, 研究員 (00648272) ; KANAMORI HIRONARI 名古屋大学, 宇宙地球環境研究所, 研究員 (50422803) ; HIRATA HIDETAKA 名古屋大学, 宇宙地球環境研究所, 研究員 (30808499)
• Project Period (FY): 2014-04-01 – 2018-03-31
• Keywords: 渦状低気圧 / モンスーン / バングラデシュ / メガラヤ高原 / ミャンマー / 降水 / 季節内振動 / 日変化

Outline of Final Research Achievements

Vortex-type low pressure systems (LPSs) often appear around Bangladesh and cause heavy rainfall during boreal summer. This study examined the three dimensional structure of the LPSs including precipitation systems and atmospheric environment for the genesis and development of the LPSs. They have horizontal scale of about 600 km and vertical scale of about 9 km. The thermal structure shows clearly a cold core in the lower troposphere and a warm core in the upper levels. There are spiral rainbands with tall cumulus convections in the LPSs in the early stage of the development. Precipitation varies on 10-20 day period around Bangladesh. About 60% of active peaks of rainfall are related to the LPSs. Strong cyclonic shear in the lower troposphere and weak vertical wind shear throughout the troposphere, which fluctuate on intraseasonal timescales, help to induce the genesis of vortex-type LPSs. Latent heating due to condensation causes the rapid development of the LPSs.

Free Research Field

気候学・気象学