Chris Cantrell

Senior Scientist
TIIMES - ACD
UTLS

Contact Information:
PO Box 3000, Boulder, CO 80307-3000
Office: FL0-3534
Telephone: 303-497-1479
Email: cantrell@ucar.edu
Windows to the Universe Home Page

Project Summary:

Click on picture to view the entire figure.

Figure 1. From the MIRAGE study, the concentrations of HO2+RO2 (black), HO2 (blue), and RO2 (gray) versus the concentrations of NOx as observed from the NSF/NCAR C-130 aircraft platform (points) and calculated from a photochemical box model constrained by observations of the controlling variables (lines). Measure and model results have been binned by the corresponding range of NOx concentrations.

The fast photochemical processes taking place in the troposphere are central to understanding the removal of trace gases.  One important pathway is the reaction of free radicals with hydrocarbons, sulfur- and nitrogen-containing compounds, carbon monoxide and other species.  Our research focuses on the development, improvement and deployment of mass spectrometric-based instrumentation for measurement of hydroxyl (OH), hydroperoxy (HO2) and organic peroxy radicals (RO2) (and other species), and interpretation of the data from those deployments.  In early 2006, we deployed our instrumentation during the Megacities Impact on Regional & Global Environment (MIRAGE, Mexico - movie clips from Dirk Richter, EOL) and the Intercontinental Chemical Transport Experiment (INTEX-B, northeast US) campaigns.  In the summer of 2007, we made measurements near Christmas Island as part of Pacific Atmospheric Sulfur Experiment (PASE - UCAR Staff Notes, Christmas in August).

Click on picture to view the entire figure.

INTEX-B: Research is continuous aboard the C-130 after take-off. This is a picture of the CIMS instrument in action.

Additional Photos from INTEX-B from Dirk Richter, EOL.

The data from the 2006 campaigns has been fully processed, quality assured and submitted to the corresponding archives.  We have made significant progress toward understanding the role of free radicals in the oxidation chemistry of the Mexico City urban plume with particular attention to the formation of ozone and the comparisons between observed radical concentrations those estimated from constrained photochemical box models.  One major finding is the systematic and dramatic under-prediction of peroxy radical amounts by models at higher amounts of NOx (NO+NO2).  This is shown in Figure 1 where measured and modeled mixing ratios of HO2+RO2, HO2 and RO2 versus NOx mixing ratios are shown.  The data have been binned by the NOx.  Note that for NOx amounts less than about 1000 pptv, the agreements between the observations and the model estimates are reasonable (within the 35% measurement and 40% model uncertainty).  At larger NOx amounts, the measurement-model differences increase.  The measured values are more than a factor of 10 greater than the model values at the NOx.  These differences cannot be explained by measurement and model uncertainties, and point to processes that are not represented in the model.

Click on picture to view the entire figure.

INTEX-B: While the plane is on the ground the inlets need to be protected from the environment.

Analysis will continue on the data from MIRAGE and INTEX-B campaigns as we also prepare the data from PASE study and submit it to data archive in the required format. 

Preparation of documentation for a potential future campaign continued this year.  The Deep Convective Clouds & Chemistry Experiment (DC3 - dee-cee three) study is designed to improve understanding of the role of deep convection in modifying the composition of upper troposphere and lower stratosphere.  The PI team consists of Mary Barth (MMM/ACD), Chris Cantrell (ACD), Bill Brune (Pennsylvania State), and Steve Rutledge (Colorado State) who, along with a scientific steering committee composed of university and national laboratory scientists, are leading the planning of a community-wide comprehensive study that will utilize ground-based radars, mesonets, fully configured aircraft platforms and satellite data to address several important scientific questions.  An important upcoming step in this process is the submittal of the Scientific and Experimental Overview documents to the National Science Foundation.

Windows to the Universe Postcards from the Field from Chris Cantrell:

• First local C-130 flight from Veracruz
• Another C-130 flight over Mexico
• Instrument comparison in flight
• Ruins at Zempoala
  

Community Service:

• Associate Editor - Journal of Geophysical Research - Atmospheres

Presentations:

• Characterization of a Dilution Modulation CIMS-Based Method for Measuring Tropospheric Peroxy Radical Concentrations, Acapulco MEX, May 2007
• CIMS-Based HOx, RO2, and H2SO4 during OASIS, Boulder USA, July 2007
• HO2 and RO2 Measurements during PASE, Boulder USA, February 2007
• HOx Behavior as Observed Aboard the C-130 during MILAGRO, Mexico City MEX, May 2007
• Three Steps to Understanding the Fast Photochemistry Dance, Boulder USA, March 2007

TIIMES External Collaborators:

Joan Alexander, NorthWest Research Associates
Timothy Bertram, University of California, Berkeley
Wiliam Brune, Pennsylvania State University
Tony Clarke, University of Hawaii
Ron Cohen, University of California, Berkeley
Owen Cooper, University of Colorado
James Crawford, Langley Research Center (LARC) - NASA
Joost deGouw, National Oceanic & Atmospheric Administration (NOAA) - ERL
Timothy Dunkerton, NorthWest Research Associates
Steve Gahn, Pacific Northwest National Laboratory
Tim Garrett, University of Utah
George Grell, University of Colorado
John Helsdon, South Dakota School of Mines & Technology (SDSMT)
Steve Howell, University of Hawaii
Greg Huey, Georgia Institute of Technology
Jose-Luis Jimenez, University of Colorado
Si-Wan Kim, National Oceanic & Atmospheric Administration (NOAA) - ESRL, University of Colorado
Paul Krehbiel, New Mexico Institute of Technology
Timothy Lang, Colorado State University
Andy Langford, National Oceanic & Atmospheric Administration (NOAA) - ESRL
Don MacGorman, National Oceanic & Atmospheric Administration (NOAA) - NSSL
Peter McMurry, University of Minnesota
Gretchen Mullendore, University of California, Los Angeles
Walter Petersen, University of Alabama, Huntsville
Kenneth Pickering, Goddard Space Flight Center (GSFC) - NASA
Steven Rutledge, Colorado State University
Darin Toohey, University of Colorado
Wen-wen Tung, Purdue University
Pao Wang, University of Wisconsin
Charles Wilson, University of Denver
Mark Zondlo, Southwest Sciences