P5.7
Ozone QBO from SHADOZ tropical ozonesondes
Jacquelyn C. Witte, SSAI, Greenbelt, MD; and M. Schoeberl, A. R. Douglass, and A. M. Thompson
We present observations of ozone in the tropical stratosphere using 1998-2006 Southern Hemisphere Additional Ozonesondes (SHADOZ) ozonesonde data. The ozone perturbation field from nine tropical stations within 10 degrees of the equator shows clear signals of four QBO cycles above 20 km and nine annual cycles below associated with the Brewer-Dobson Circulation (BDC). Alternating patterns of high and low ozone mixing ratio anomalies above 20 km correlate well with the alternating easterly and westerly QBO wind shear regimes (Singapore wind record), with a mean periodicity of 26 months and a lag of one to two months. The annual variations in BDC is in phase with the QBO during the northern hemispheric winter when stratospheric wave driving enhances vertical advection. In this case, high ozone anomalies descend during the westerly phase of the QBO wind shear down to tropopause heights (~ 16 km). When the QBO wind shear is in it's easterly phase the BDC upwelling of high ozone values are capped at around 20 km. The annually varying BDC signal in the ozone and temperature perturbations fields maintain a thumbprint structure of high anomalies between 16 - 20 km that weaken rapidly below the tropopause implying that convective lofting is not a prominant mechanism for producing the high ozone we observe at those levels. In the tropics, the zonal wind shear and temperature fields are in thermal balance, allowing us to derive the length scales above 20 km at 26 and 12 months associated with the QBO and BDC, respectively. QBO length scales are in agreement with previous studies at around ~ 1100 km, on average. Noteworthy, are estimates of the BDC length scales ranging between 900 and 1100 km derived from observations.
Poster Session 5, Tropical/Extratropical Interactions
Wednesday, 22 August 2007, 1:30 PM-3:30 PM, Holladay
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