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Convective distribution of tropospheric ozone and tracers in the Central American ITCZ region: Evidence from observations during TC4

ScholarsArchive at Oregon State University

Field Value
Title Convective distribution of tropospheric ozone and tracers in the Central American ITCZ region: Evidence from observations during TC4
Names Avery, Melody (creator)
Twohy, Cynthia (creator)
McCabe, David (creator)
Joiner, Joanna (creator)
Severance, Kurt (creator)
Atlas, Eliot (creator)
Blake, Donald (creator)
Bui, T. P. (creator)
Crounse, John (creator)
Dibb, Jack (creator)
Diskin, Glenn (creator)
Lawson, Paul (creator)
McGill, Matthew (creator)
Rogers, David (creator)
Sachse, Glen (creator)
Scheuer, Eric (creator)
Thompson, Anne M. (creator)
Trepte, Charles (creator)
Wennberg, Paul (creator)
Ziemke, Jerald (creator)
Date Issued 2010-10-13 (iso8601)
Abstract During the Tropical Composition, Clouds and Climate Coupling (TC4) experiment
that occurred in July and August of 2007, extensive sampling of active convection in the
ITCZ region near Central America was performed from multiple aircraft and satellite
sensors. As part of a sampling strategy designed to study cloud processes, the NASA ER‐2,
WB‐57 and DC‐8 flew in stacked “racetrack patterns” in convective cells. On July 24, 2007,
the ER‐2 and DC‐8 probed an actively developing storm and the DC‐8 was hit by
lightning. Case studies of this flight, and of convective outflow on August 5, 2007 reveal
a significant anti‐correlation between ozone and condensed cloud water content. With
little variability in the boundary layer and a vertical gradient, low ozone in the upper
troposphere indicates convective transport. Because of the large spatial and temporal
variability in surface CO and other pollutants in this region, low ozone is a better
convective indicator. Lower tropospheric tracers methyl hydrogen peroxide, total organic
bromine and calcium substantiate the ozone results. OMI measurements of mean upper
tropospheric ozone near convection show lower ozone in convective outflow. A mass
balance estimation of the amount of convective turnover below the tropical tropopause
transition layer (TTL) is 50%, with an altitude of maximum convective outflow located
between 10 and 11 km, 4 km below the cirrus anvil tops. It appears that convective lofting
in this region of the ITCZ is either a two‐stage or a rapid mixing process, because
undiluted boundary layer air is never sampled in the convective outflow.
Genre Article
Topic Tropospheric ozone
Identifier Avery, M., et al. (2010), Convective distribution of tropospheric ozone and tracers in the Central American ITCZ region: Evidence from observations during TC4, J. Geophys. Res., 115, D00J21, doi:10.1029/2009JD013450.

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