Measurement of momentum flux using two meteor radars in Indonesia

Abstract. Two nearly identical meteor radars were operated at Koto Tabang (0.20° S, 100.32° E), West Sumatra, and Biak (1.17° S, 136.10° E), West Papua, in Indonesia, separated by approximately 4000 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 in v ′ w ′ were consistent between 86, 90, and 94 km altitudes at both sites. The climatological variation in 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 in 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, both of 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.