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CO signatures in subtropical convective clouds and anvils during CRYSTAL-FACE:...

Lopez, J. P., A. M. Fridlind, H. Jost, M. Loewenstein, A. S. Ackerman, T. Campos, E. Weinstock, D. Sayres, J. B. Smith, J. V. Pittman, A. G. Hallar, L. Avallone, S. Davis, and R. L. Herman (2006), CO signatures in subtropical convective clouds and anvils during CRYSTAL-FACE: An analysis of convective transport and entrainment using observations and a cloud-resolving model, J. Geophys. Res., 111, D09305, doi:10.1029/2005JD006104.

Convective systems are an important mechanism in the transport of boundary layer air into the upper troposphere. The Cirrus Regional Study of Tropical Anvils and Cirrus Layers–Florida Area Cirrus Experiment (CRYSTAL-FACE) campaign, in July 2002, was developed as a comprehensive atmospheric mission to improve knowledge of subtropical cirrus systems and their roles in regional and global climate. In situ measurements of carbon monoxide (CO), water vapor (H2Ov), and total water (H2Ot) aboard NASA’s WB-57F aircraft and CO aboard the U.S. Navy’s Twin Otter aircraft were obtained to study the role of convective transport. Three flights sampled convective outflow on 11, 16 and 29 July found varying degrees of CO enhancement relative to the free troposphere. A cloud-resolving model used the in situ observations and meteorological fields to study these three systems. Several methods of filtering the observations were devised here using ice water content, relative humidity with respect to ice, and particle number concentration as a means to statistically sample the model results to represent the flight tracks. A weighted histogram based on ice water content observations was then used to sample the simulations for the three flights. In addition, because the observations occurred in the convective outflow cirrus and not in the storm cores, the model was used to estimate the maximum CO within the convective systems. In general, anvil-level air parcels contained an estimated 20–40% boundary layer air in the analyzed storms.

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Radiation Science Program (RSP)