A study of ozone variability and its connection with meridional transport in the northern Pacific lower stratosphere during summer 2002

Thierry Leblanc (1) , I. Stuart Mcdermid (1) , Alain Hauchecorne (2)

1 JPL - Jet Propulsion Laboratory
2 SA - Service d'aéronomie

A preliminary study of the impact of the north-central Pacific circulation in the subtropical stratosphere on ozone variability locally observed by lidar is presented. The results from the upper tropospheric and stratospheric ozone measurements of the Jet Propulsion Laboratory lidars located at Mauna Loa Observatory (MLO), Hawaii, and Table Mountain Facility (TMF), California, during summer 2002 were compared to isentropic potential vorticity (IPV) advected on 54 levels from 320 to 1500 K by the high-resolution model MIMOSA. The correlation between ozone measured by lidar, and the origin of the 10-day backward trajectories of the air parcels sampled, was also investigated. Near the tropopause, strong positive correlation between ozone mixing ratio and IPV was observed at both MLO and TMF lidar sites. The largest fluctuations were centered near 350 K and are associated with the meridional displacement of the tropopause by Rossby waves north or south of the observing sites. These large displacements were occasionally accompanied by Rossby wave breaking (RWB), as was identified several times during the summer in the vicinity of the Hawaiian Islands. Using IPV maps, a case study of the 13 July event is briefly presented. This event appears to be typical of breaking events previously investigated at midlatitudes, including the southward intrusion of high-PV air originating in the high-latitude lower stratosphere. This time the intrusion was observed to extend deep in the subtropics. Strong positive ozone anomalies were simultaneously measured by the MLO lidar. Positive correlation between ozone and the equivalent latitude averaged along the parcels' trajectories was seen up to 475 K in the stratosphere. At and above 750 K, negative correlation was calculated for both TMF and MLO. For TMF the altitude dependence of the correlation is similar to that already observed for summer and winter midlatitudes For MLO the observed negative correlation was found to be the result of opposite seasonal and interannual tendencies in ozone and equivalent latitude throughout the summer. All other correlations are associated with a higher intraseasonal variability of both ozone and the parcels' origin, as compared to their seasonal tendencies.

Mots clés: ozone transport; lower stratosphere; tropopause

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]

Thierry Leblanc, I. Stuart Mcdermid, Alain Hauchecorne. A study of ozone variability and its connection with meridional transport in the northern Pacific lower stratosphere during summer 2002. Journal of Geophysical Research: Atmospheres, 2004, 109 (D11), pp.D11105. ⟨10.1029/2003JD004027⟩. ⟨hal-01654906⟩