Examination of 3-6 day disturbances over quatorial Indonesia based on boundary layer radar observations during 1996-1999 at Bukittinggi, Serpong and Biak

Abstract

Spectral features of lower tropospheric horizontal wind observed during 1996-1999 by Bukittinggi, Serpong and Biak boundary layer radars show 3-6 day periodicities in zonal and meridional components and longer period zonal wind oscillations. Using bandpass filtering analysis the 3-6 day modes show a westward phase speed of about 700 km day-1 and a zonal wavelength of about 3500 km, and propagate through the Indonesian maritime continent when the westerly wind is prevailing at Biak. © 2001, Meteorological Society of Japan.