OBSERVATION OF AN ULTRASLOW LARGE-SCALE WAVE NEAR THE TROPICAL TROPOPAUSE

An analysis is made of very high resolution radiosonde data taken at s even western Pacific island stations during TOGA-COARE (Tropical Ocean -Global Atmosphere and Coupled Ocean-Atmosphere Response Experiment). Evidence is found for a wave near the tropopause with periods similar to 30-40 days and with very slow (similar to 3 m s(-1)) eastward propa gation. This oscillation appears quite coherent across the region cons idered (a 37 degrees longitude spread). The oscillation has a short ve rtical wavelength (similar to 3 km) and is strongly attenuated above t he tropopause and thus would be very hard to observe in either satelli te data or conventional meteorological analyses.