Ozonesonde profiles from the West Pacific Warm Pool: Measurements and validation

Comparison with aircraft measurements allows validation of the measured ozone profiles and confirms that for well-characterized sondes (background current ~ 50 nA) a constant background current could be assumed throughout the profile, equal to the minimum value measured during preparation just before launch. From this set of 34 ozonesondes, the minimum reproducible ozone concentration measured in the TTL was 12-13 ppbv; no examples of ozone concentrations  <  5 ppbv, as reported by other recent papers, were measured.

The lowest ozone concentrations coincided with outflow from extensive deep convection to the east of Manus, consistent with uplift of ozone-poor air from the boundary layer. However, these minima were lower than the ozone concentration measured through most of the boundary layer, and were matched only by measurements at the surface in Manus.