VARIATION WITH LONGITUDE OF THE QUASI-BIENNIAL OSCILLATION

Abstract

Daily data at 16 stations along five latitudes from 13°N. to 33°S. were carefully examined at the 50-, 100-, and 500-mb. levels for evidence of longitudinal phase progression of the quasi-biennial oscillation (QBO). At 50 mb. there is evidence of west to east progression although there are many irregularities and much uncertainty. The phase dates differ by days at low latitudes. At 100 and 500 mb., it appears that the QBO originates in tropical America and progresses both eastward and westward, occurring last in the Indian Ocean. The progression time ranges from 1 to 2 yr. At 500 and 100 mb., however, a cellular phase progression in possible due to the difficulty of identifying corresponding waves with a very meager network. It appears now that the QBO may not be simultaneous in longitude and that its speed and even direction of propagation, like its other properties, may very from cycle to cycle. The analysis is being expanded to other levels and latitudes to obtain better continuity in following each wave.