P5.5
Zonal asymmetry in the methane and hydrogen fluoride distribution in the equatorial stratosphere observed by satellites
Hyesun Choi, School of Earth and Environmental Sciences, Seoul National University, Seoul, South Korea; and W. Choi
Relationships between the quasi-biennial oscillation (QBO) in the equatorial zonal wind and the zonal distributions of observed methane and hydrogen fluoride are examined by using Halogen Occultation Experiment and Michelson Interferometer for Passive Atmospheric Sounding data. Zonal wind at 10 hPa during the wintertime based on ECMWF ERA-40 data shows different levels of zonal asymmetry dependent on the phase of the QBO and the season. Large and small asymmetries of zonal wind are observed in the westerly and easterly phase of the QBO, respectively. Observed tracers show different levels of zonal asymmetry dependent on both QBO phase and the observing latitude. Among tracer distributions close to the equator, the zonal asymmetry is the strongest at Northern low latitude. The zonal variations of the observed tracers at 10°N from January to March are large when the equatorial westerly is prevailing, but those are fairly small when zonal wind is easterly. The correlation between zonal asymmetries of the equatorial and the Southern low-latitude tracer and the equatorial QBO phase seems to be small. Possible mechanisms for theses correlations between the zonal asymmetry of tracer distributions and the equatorial QBO are discussed.
Poster Session 5, Tropical/Extratropical Interactions
Wednesday, 22 August 2007, 1:30 PM-3:30 PM, Holladay
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