Grantee Research Project Results

1999 Progress Report: Development of Lightweight Instrumentation for Measurement of Long-Lived Trace Gases

EPA Grant Number: R825222
Title: Development of Lightweight Instrumentation for Measurement of Long-Lived Trace Gases
Investigators: Avallone, Linnea M.
Institution: University of Colorado at Boulder
EPA Project Officer: Hahn, Intaek
Project Period: December 1, 1996 through November 30, 2001
Project Period Covered by this Report: December 1, 1998 through November 30, 1999
Project Amount: $466,074
RFA: Exploratory Research - Early Career Awards (1996) RFA Text |  Recipients Lists
Research Category: Early Career Awards

Objective:

The primary goal of this research is the development, test, and deployment of a prototype, lightweight gas chromatograph (GC) system, based on micro-GC technology. As originally conceived, this GC system would be integrated into a suite of sensors (the rest of which are funded through a grant from the National Aeronautics and Space Administration Atmospheric Effects of Aviation Program [AEAP]) to be flown on a commercial airliner. The aim of this larger project is to obtain extensive measurements of several key trace species (O3, CO2, H2O, and C2Cl4) in the upper troposphere (8?12 km). This data set can be used for a variety of purposes, including testing of global three-dimensional chemical transport models and models of ozone precursor emissions and ambient air quality, and the assessment of the effects of subsonic aviation on upper tropospheric and lower stratospheric ozone distributions.

Progress Summary:

Tremendous progress has been made on the development of the instrument package, culminating in the participation of a major NASA airborne campaign this winter. At the time of the last progress report, the "go-ahead" to continue development of the prototype package to meet commercial airline standards had just been received. In January 1999, this course was diverted to package the instrumentation such that it could fly on NASA's DC-8 airborne laboratory. Achieving flight readiness by the beginning of November 1999, has been the goal throughout the 1999 calendar year.
A post-doctorate whose focus has been the development of the gas chromatograph for this instrument package began working on the project part-time in January and full-time in April. He is an expert in the measurement of trace atmospheric constituents by gas chromatography. He designed and built a laboratory calibration and test facility, and contributed extensively to the final design of the flight GC.

In contrast to the original plans, based on capillary chromatography, it was found that traditional packed columns worked better for the purposes of this project. Custom ovens were designed and built for the pre- and analytical columns, a compact gas-handling system was built, and commercial Valco multiport switching valves and Hewlett-Packard micro-ECDs and control electronics were incorporated. The instrument developed was somewhat larger and heavier than originally planned, but it was able to measure seven halocarbons (CFCs -11, -12, -113, Halon 1211, CHCl3, CH3CCl3, and CCl4) every 4 minutes, rather than just a single species (C2Cl4). This suite of gases will provide an estimate of total organic chlorine (CCly), a useful quantity in determining the extent of chlorine activation following exposure of air to polar stratospheric clouds. In addition, extensive analysis of transport based on the widely varying lifetimes of the species measured is planned. In addition to the completion of the gas chromatograph (see photograph), a carbon dioxide analyzer and an ozone sensor also were finished this year. Each of those instruments was flown during an airborne mission in spring 1999: CO2 on NASA's Atmospheric Chemistry of Combustion Emissions Near the Tropopause (ACCENT) campaign, to assess the effects of aircraft and rocket emissions on the lower stratosphere and upper troposphere; and O3 on an interagency project known as the CO2 Budget and Recertification Airborne Study (COBRA), which studies the uptake of carbon dioxide in the boundary layer. Both experiments were successful and have provided interesting data that are being analyzed and incorporated into future dissertations.

Side view of the gas chromatograph developed under this project. Electron capture detectors are in the foreground; GC ovens are the white cylinders in the rear.

Although there is still an interest in flying this suite of sensors on commercial aircraft as originally proposed, this has continued to be a difficult goal to achieve. The AEAP program, which has funded much of the instrument development, has undergone a considerable change of focus and will no longer support this project financially. While there is considerable enthusiasm for such a program of measurements among the scientific community, it is seemingly not shared by the airline personnel who have been contacted for this project. This goal will still be pursued, but will now be viewed as a long-term prospect at best. Meanwhile, other flight opportunities on research aircraft will be sought, so the instruments will most certainly be used to gather meaningful observations for the analysis of tropospheric chemistry and transport.

Future Activities:

The entire suite of instruments will be flown on the NASA DC-8 during the SAGE III Ozone Loss and Validation Experiment (SOLVE) from late November 1999 through March 2000. The goals of the mission are to gain further understanding of the processes causing ozone loss in the northern hemisphere during winter and to provide correlative data for the SAGE III satellite instruments. Other flight opportunities for the coming summer are being sought, perhaps including participation in the second phase of COBRA, based out of Grand Forks, ND, and other continental U.S. sites. With continued funding from this EPA grant, further minimizing the size and weight of the GC is planned, as is exploring the measurement of additional halocarbons.

Journal Articles:

No journal articles submitted with this report: View all 17 publications for this project

Supplemental Keywords:

atmosphere, ozone, stratospheric ozone, chemical transport, chlorofluorocarbons., RFA, Scientific Discipline, Air, Environmental Chemistry, tropospheric ozone, Atmospheric Sciences, air toxics, climate change, Ecology and Ecosystems, trace gas measurement, convective boundary layer, gas chromatography, three dimensional model, measurement methods , atmospheric monitoring, chemical composition, monitoring, climate variability, lightweight instrumentation, ambient ozone data, chemical kinetics, field measurements, chemical transport model, ozone occurrence, diode laser spectrometer, atmospheric chemical cycles

Relevant Websites:

http://cloud1.arc.nasa.gov/solve/

Progress and Final Reports:

Original Abstract

1997 Progress Report

1998 Progress Report

2000 Progress Report

Final