A Preliminary Report on Radiosonde Observations of the Equatorial Atmosphere Dynamics over Indonesia

Abstract

Observations of the equatorial atmosphere dynamics by means of radiosondes were conducted, as a collaborative project between Japan and Indonesia, at the Watukosek observatory in East Jawa, Indonesia, for 25 days from 27 February to 22 March, 1990. Profiles of the wind velocity, temperature, pressure and humidity were obtained at 0-3 km altitude with time and height resolutions of 5-7 hours and 150 m, respectively. This paper gives an outline of the experiment and the background conditions of the atmosphere during the campaign period. The structure of the zonal mean winds at 10-25 km was basically explained by QBO, showing westward winds of about 15 m/s, while the meridional winds were fairly weak in the entire height range. The mean temperature profile indicated the tropopause to be at 17-18 km altitude, with a minimum temperature of about 190 K. Both wind velocity and temperature fluctuations were large indicating the manifestation of various wave activities. The relative humidity was fairly high in the lower troposphere, showing periodic fluctuations with time scales of 3-5 days in addition to the diurnal cycle. © 1992, Society of Geomagnetism and Earth, Planetary and Space Sciences. All rights reserved.