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.

Department

Earth Sciences, Earth Systems Research Center

Publication Date

5-27-2010

Journal Title

Journal of Geophysical Research

Publisher

American Geophysical Union Publications

Digital Object Identifier (DOI)

10.1029/2009JD013450

Document Type

Article

Rights

Copyright 2010 by the American Geophysical Union.

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