[P-EM03] Mesosphere-Thermosphere-Ionosphere Coupling in the Earth's Atmosphere

[PEM03-P05] Measurement of momentum flux Using two meteor radars in Indonesia

Naoki Matsumoto¹, Atsuki Shinbori¹, Dennis M Riggin², *Toshitaka Tsuda¹ (1.Research Institute for Sustainable Humanosphere (RISH), Kyoto University, 2.GATS, Inc.)

Keywords:Meteor radar, Momentum flux, Mesosphere and lower thermosphere, Hocking method, Equator, Semi-annual variation

Two nearly identical meteor radars were operated at Koto Tabang (0.20^oS, 100.32^oE), western Sumatra, and Biak (1.17^oS, 136,10^oE), western Papua in Indonesia, separated by approximately 4,000 km in longitude on the equator. The zonal and meridional momentum flux, u’w’ and v’w’ , where u, v and w are the eastward, northward and vertical wind velocity components, respectively, were estimated at 86 to 94 km altitudes using the meteor radar data by applying a method proposed by Hocking [2005]. The observed u’w’ at the two sites agreed reasonably well at 86, 90 and 94 km during the observation periods when the data acquisition rate was sufficiently large enough. Variations of v’w’ was consistent between 86, 90 and 94 km altitudes at both sites. The climatological variation of the monthly averaged u’w’ and v’w’ was investigated using the long-term radar data at Koto Tabang from November 2002 to November 2013. The seasonal variations of u’w’ and v’w’ showed a repeatable semiannual and annual cycles, respectively. u’w’ showed eastward values in February-April and July-September, and v’w’ was northward in June to August at 90-94 km, which were generally anti-phase with the mean zonal and meridional winds, having the same periodicity. Our results suggest the usefulness of the Hocking method.