Model Evaluation and Sensitivity Studies for Determining Aircraft Effects on the Global Atmosphere

This project, started in July 1995 and ending in July 1996, related: to evaluation of the possible importance of soot and sulfur dioxide emissions from subsonic and supersonic aircraft; to research contributions and special responsibilities for NASA AEAP assessments of subsonic aircraft and High Speed Civil Transport aircraft; and to science team responsibilities supporting the development of the three-dimensional atmospheric chemistry model of the Global Modeling Initiative

Accomplishments in Support of NASA ACMAP Under NRA-97-MTPE-07

Over the past three years, the primary foci of our research have been on studies of stratospheric processes and the potential effects of natural perturbations and human related activities on global stratospheric ozone, on interactions between atmospheric chemistry, atmospheric composition and concerns about climate change, and, to a lesser degree, on studies of tropospheric processes. Published research articles are listed

Tackling Strategies for Thriving Geoscience Departments

Special sessions on thriving geosciences departments and on cyberinfrastructure in the geosciences highlighted the recent 5th AGU Meeting of Heads and Chairs of Earth and Space Science Departments. The meeting was held in conjunction with the 14th meeting of the Heads and Chairs of Programs in Atmospheric, Oceanic, Hydrologic and Related Sciences, sponsored by the American Meteorological Society (AMS),and the University Corporation for Atmospheric Research (UCAR). “From Surviving to Thriving: Strategies for Advancing University Geoscience Programs in Times of Change” was a topic that drew intense interest. This panel discussion, led by Don Wuebbles (University of Illinois), included panelists Eric Betterton (University of Arizona), Judy Curry (Georgia Institute of Technology), Heather MacDonald (College of William and Mary), and Jim Kirkpatrick (University of Illinois)

Impact of supersonic and subsonic aircraft on ozone: Including heterogeneous chemical reaction mechanisms

Preliminary calculations suggest that heterogeneous reactions are important in calculating the impact on ozone from emissions of trace gases from aircraft fleets. In this study, three heterogeneous chemical processes that occur on background sulfuric acid aerosols are included and their effects on O3, NO(x), Cl(x), HCl, N2O5, ClONO2 are calculated

Parametric Analyses of Potential Effects on Upper Tropospheric/Lower Stratospheric Ozone Chemistry by a Future Fleet of High Speed Civil Transport (HSCT) Type Aircraft

This report analyzed the potential impact of projected fleets of HSCT aircraft (currently not under development) through a series of parametric analyses that examine the envelope of potential effects on ozone over a range of total fuel burns, emission indices of nitrogen oxides, and cruise altitudes

Analyses of Scenarios for Past and Possible Future Aircraft Emissions

This project contains several components to work with the NASA AEAP program in better definition of scenarios for aircraft emissions and in determining the sensitivity of the atmosphere to such emissions. Under this project, Don Wuebbles continues as chair of the Operations and Emissions Scenarios Committee for AEAP. We are also coordinating with the International Civil Aviation Organization (ICAO) to ensure the highest quality possible in the emissions scenarios promoted by the Emissions Scenarios committee. We continue to help coordination of NASA AEAP with international activities. This includes work with ICAO towards international analysis of aircraft emissions inventories; performing analyses to compare and evaluate databases of aircraft emissions developed for NASA and by various international groups and from these analyses, develop guidelines for future emissions scenarios development. Special sensitivity analyses, using our two-dimensional chemical-transport model of the global troposphere and stratosphere, have been used to determine potential sensitivity of further enhancements that could be made to emissions scenarios development. The latter studies are to be used in prioritizing further emissions scenario development

Ozone depletion and chlorine loading potentials

The recognition of the roles of chlorine and bromine compounds in ozone depletion has led to the regulation or their source gases. Some source gases are expected to be more damaging to the ozone layer than others, so that scientific guidance regarding their relative impacts is needed for regulatory purposes. Parameters used for this purpose include the steady-state and time-dependent chlorine loading potential (CLP) and the ozone depletion potential (ODP). Chlorine loading potentials depend upon the estimated value and accuracy of atmospheric lifetimes and are subject to significant (approximately 20-50 percent) uncertainties for many gases. Ozone depletion potentials depend on the same factors, as well as the evaluation of the release of reactive chlorine and bromine from each source gas and corresponding ozone destruction within the stratosphere

Effects of Planetary Wave-breaking on the Seasonal Variation of Total Column Ozone

The effects of planetary wave breaking on the seasonal variation of total column ozone are investigated using a zonally averaged chemical-radiative-transport model of the atmosphere. The planetary wave breaking effects of zonal wavenumbers k=1 and k=2 are significant in the middle latitude stratosphere during Northern Hemisphere (NH) winter, whereas only wave k=1 is important during Southern Hemisphere (SH) winter. The mixing and induced meridional circulation due to the planetary wave breaking increases the seasonal variation of total column ozone in NH (SH) middle latitudes by ∼20% (∼10%)