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Jennifer C. Wei, Laura L. Pan, Eric Maddy, Jasna V. Pittman, Murty Divarkarla, Xiaozhen Xiong, and Chris Barnet


Motivated by a significant potential for retrieving atmospheric ozone profile information from advanced satellite infrared sounders, this study investigates various methods to optimize ozone retrievals. A set of retrieval experiments has been performed to assess the impact of different background states (or the a priori states) and retrieval algorithms on the retrieved ozone profiles in the upper troposphere and lower stratosphere (UTLS) using Atmospheric Infrared Sounder (AIRS) measurements. A new tropopause-based ozone climatology, using publicly available global ozonesonde data to construct the a priori state, is described. Comparisons are made with the AIRS version 5 (v5) ozone climatology. The authors also present the result of a newly implemented optimal estimation (OE) algorithm and compare it to the current AIRS science team (AST) algorithm used in version 5. The ozone climatology using tropopause-referenced coordinates better preserves the shape and the magnitude of the ozone gradient across the tropopause, especially in the extratropical region. The results of the retrieval experiments indicate that the tropopause-referenced climatology not only helps to optimize the use of instrument sensitivity in the UTLS region, but it also provides better constraints to the OE algorithm.

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Laura L. Pan, Kenneth P. Bowman, Elliot L. Atlas, Steve C. Wofsy, Fuqing Zhang, James F. Bresch, Brian A. Ridley, Jasna V. Pittman, Cameron R. Homeyer, Pavel Romashkin, and William A. Cooper

The Stratosphere–Troposphere Analyses of Regional Transport 2008 (START08) experiment investigated a number of important processes in the extratropical upper troposphere and lower stratosphere (UTLS) using the National Science Foundation (NSF)–NCAR Gulfstream V (GV) research aircraft. The main objective was to examine the chemical structure of the extratropical UTLS in relation to dynamical processes spanning a range of scales. The campaign was conducted during April–June 2008 from Broomfield, Colorado. A total of 18 research flights sampled an extensive geographical region of North America (25°–65°N, 80°–120°W) and a wide range of meteorological conditions. The airborne in situ instruments measured a comprehensive suite of chemical constituents and microphysical variables from the boundary layer to the lower stratosphere, with flights specifically designed to target key transport processes in the extratropical UTLS. The flights successfully investigated stratosphere–troposphere exchange (STE) processes, including the intrusion of tropospheric air into the stratosphere in association with the secondary tropopause and the intrusion of stratospheric air deep into the troposphere. The flights also sampled the influence of convective transport and lightning on the upper troposphere as well as the distribution of gravity waves associated with multiple sources, including fronts and topography. The aircraft observations are complemented by satellite observations and modeling. The measurements will be used to improve the representation of UTLS chemical gradients and transport in Chemistry–Climate models (CCMs). This article provides an overview of the experiment design and selected observational highlights.

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A Field Campaign Overview Including Observational Highlights

Vanda Grubišić, James D. Doyle, Joachim Kuettner, Stephen Mobbs, Ronald B. Smith, C. David Whiteman, Richard Dirks, Stanley Czyzyk, Stephen A. Cohn, Simon Vosper, Martin Weissmann, Samuel Haimov, Stephan F. J. De Wekker, Laura L. Pan, and Fotini Katopodes Chow

The Terrain-Induced Rotor Experiment (T-REX) is a coordinated international project, composed of an observational field campaign and a research program, focused on the investigation of atmospheric rotors and closely related phenomena in complex terrain. The T-REX field campaign took place during March and April 2006 in the lee of the southern Sierra Nevada in eastern California. Atmospheric rotors have been traditionally defined as quasi-two-dimensional atmospheric vortices that form parallel to and downwind of a mountain ridge under conditions conducive to the generation of large-amplitude mountain waves. Intermittency, high levels of turbulence, and complex small-scale internal structure characterize rotors, which are known hazards to general aviation. The objective of the T-REX field campaign was to provide an unprecedented comprehensive set of in situ and remotely sensed meteorological observations from the ground to UTLS altitudes for the documentation of the spatiotemporal characteristics and internal structure of a tightly coupled system consisting of an atmospheric rotor, terrain-induced internal gravity waves, and a complex terrain boundary layer. In addition, T-REX had several ancillary objectives including the studies of UTLS chemical distribution in the presence of mountain waves and complex-terrain boundary layer in the absence of waves and rotors. This overview provides a background of the project including the information on its science objectives, experimental design, and observational systems, along with highlights of key observations obtained during the field campaign.

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Mary C. Barth, Christopher A. Cantrell, William H. Brune, Steven A. Rutledge, James H. Crawford, Heidi Huntrieser, Lawrence D. Carey, Donald MacGorman, Morris Weisman, Kenneth E. Pickering, Eric Bruning, Bruce Anderson, Eric Apel, Michael Biggerstaff, Teresa Campos, Pedro Campuzano-Jost, Ronald Cohen, John Crounse, Douglas A. Day, Glenn Diskin, Frank Flocke, Alan Fried, Charity Garland, Brian Heikes, Shawn Honomichl, Rebecca Hornbrook, L. Gregory Huey, Jose L. Jimenez, Timothy Lang, Michael Lichtenstern, Tomas Mikoviny, Benjamin Nault, Daniel O’Sullivan, Laura L. Pan, Jeff Peischl, Ilana Pollack, Dirk Richter, Daniel Riemer, Thomas Ryerson, Hans Schlager, Jason St. Clair, James Walega, Petter Weibring, Andrew Weinheimer, Paul Wennberg, Armin Wisthaler, Paul J. Wooldridge, and Conrad Ziegler


The Deep Convective Clouds and Chemistry (DC3) field experiment produced an exceptional dataset on thunderstorms, including their dynamical, physical, and electrical structures and their impact on the chemical composition of the troposphere. The field experiment gathered detailed information on the chemical composition of the inflow and outflow regions of midlatitude thunderstorms in northeast Colorado, west Texas to central Oklahoma, and northern Alabama. A unique aspect of the DC3 strategy was to locate and sample the convective outflow a day after active convection in order to measure the chemical transformations within the upper-tropospheric convective plume. These data are being analyzed to investigate transport and dynamics of the storms, scavenging of soluble trace gases and aerosols, production of nitrogen oxides by lightning, relationships between lightning flash rates and storm parameters, chemistry in the upper troposphere that is affected by the convection, and related source characterization of the three sampling regions. DC3 also documented biomass-burning plumes and the interactions of these plumes with deep convection.

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