Study of atmospheric waves in the mesosphere-lower thermosphere (MLT) region with a radar network

2015 Fiscal Year Final Research Report

• Project/Area Number: 22253006
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 海外学術
• Research Field: Space and upper atmospheric physics
• Research Institution: Kyoto University
• Principal Investigator: Tsuda Toshitaka 京都大学, 生存圏研究所, 教授 (30115886)
• Co-Investigator(Kenkyū-buntansha): HAYASHI Hiroo 京都大学, 生存圏研究所, 准教授 (70447936) ; HASHIGUCHI Noriko 京都大学, 生存圏研究所, 研究員 (70452480) ; SHINBORI Atsuki 京都大学, 生存圏研究所, 研究員 (30555678)
• Project Period (FY): 2010-04-01 – 2016-03-31
• Keywords: 中間圏・下部熱圏領域 / 大気圏上下結合過程 / 赤道大気 / 大気重力波 / 波動・平均流相互作用 / 流星レーダー / 中波帯(MF)レーダー

Outline of Final Research Achievements

We studied the behavior of atmospheric waves as well as long-term variations of the monthly mean winds in the Mesosphere-Lower Thermosphere (MLT) region at 60-150 km altitude, focusing on the coupling processes between different atmospheric layers due to upward propagating waves. We utilized archived data-sets (IUGONET) collected by a number of meteor and medium frequency (MF) radars operated continuously for many years since 1990’s at low latitudes in Asia and Pacific regions. We investigated seasonal variations of the atmospheric gravity activity in the tropics, and found its relation with cloud convection in the lower atmosphere. Monthly mean zonal and meridional winds exhibited peculiar variations with semi-annual (SAO), annual, quasi-biennial (QBO), and intra-seasonal periods. Our analysis suggested importance of interaction of atmospheric waves with the mean flow to drive these regular and irregular variations. The mean meridional winds showed a trend with a decadal time scale.

Free Research Field

地球惑星科学