The purpose of this session was to examine the accomplishments of the ACP, focusing on the many field studies that the program has participated in over the past several years. Accomplishments can be thought of in many contexts. Of primary importance is the scientific understanding that has been developed as a consequence of the activities of the program. Accordingly the session participants attempted to list the major scientific findings of the program over the last five years. However, the consensus of the session participants was that the accomplishments of the ACP extend beyond a listing of scientific findings. Specifically, the group decided that contributions the Program has made in the development and implementation measurement technologies deserve to be included as accomplishments. The rationale is that our understanding of atmospheric chemistry is limited by our ability to measure the concentrations of key species and that development or implementation of techniques to measure new species, or to measure species with higher sensitivity or time response, contributes substantially to the Program and to the science. In addition, the session participants decided to include as accomplishments the collaborations that have developed within ACP among the DOE national laboratories, between the laboratories and the university community, as well as collaborations ACP has developed with other national and international programs that have similar goals. The rationale here was that collaborations within ACP make the program stronger by enabling us to bring to bear a collective set of resources in field programs which makes the activity "a whole greater than the sum of its parts." Collaboration with external programs has allowed access to resources that the program would not otherwise have and has given the program prominence and a place in both the national and international scientific communities.
Accomplishment of ACP are listed below. They focus on ACP field studies and specifically do not attempt to include ACP accomplishments in laboratory studies or modeling. Further, the session participants do not represent the following as an exhaustive list of accomplishments. Other ACP scientists may wish to add to this list.
1. Scientific Findings
1.1 Oxidant Chemistry
1.1.1 Urban and Power Plant Plumes
Demonstrated differences in O3 production efficiencies and rates and NOx and NOy lifetimes in urban and power plant plumes
Demonstrated the insensitivity of O3 in urban plumes to changes in NOx and HC emissions
Established that background O3 concentrations in the rural SE are almost entirely controlled by the availability of NOx
Measured for the first time the vertical distribution and horizontal gradient of organic acids aloft with a tandem mass spectrometer
1.1.2 Peroxides
Showed that organic peroxides constitute a significant fraction of total peroxides under some circumstances. This has implications when evaluating model results, such as by comparison with measurements of the indicator ratio HNO3/H2O2.
Peroxide measurements during a number of field programs confirm our understanding of atmospheric photochemistry:
diurnal profiles at the surface are consistent with photochemical production and nighttime losses
regions of high NOx (plumes) have depleted H2O2
peroxides persist in layers isolated from surface deposition.
Demonstrated the importance of biogenic hydrocarbons for O3 production in the eastern US.
Numerical solutions with a transport-chemistry model that were driven by an estimated strong surface emission of isoprene predicted low isoprene concentrations in the middle and upper Atmospheric Boundary Layer (ABL) above a deciduous forest similar to concentrations measured from the Battelle G-1 aircraft. It was concluded that little isoprene escapes from the ABL
Chemical oxidation by O3 and OH in the middle and upper ABL consumes isoprene and influences the vertical flux in that layer. Chemical consumption has little effect on the fluxes of isoprene near isoprene sources.
1.1.4 Chlorine Chemistry
Measured molecular chlorine in surface air at levels higher than predicted by known halogen reaction mechanisms.
Proposed a new source of Cl2 by reaction of O3 with sea-salt.
1.1.5 Miscellaneous
Made airborne mass spectrometer measurements of DMS over the western North Atlantic Ocean that suggest DMS levels aloft are correlated with sea surface temperature.
1.2 Atmospheric Dynamics and Oxidants
Found that elevated layers of high O3 can be produced by:
downward transport by synoptic-scale processes of O3 of stratospheric origin at locations upwind of the point of observation.
Found that entrainment of elevated layers of high O3 and its precursors into the growing daytime convective boundary layer leads to a degradation of surface air quality (high O3).
Demonstrated that convective mixing and synoptic-scale vertical transport makes back trajectories a poor tool for defining source regions for O3 and its precursors.
Observed the effect of an internal gravity wave on the horizontal distribution of O3 measured from an aircraft.
Showed how the growth of the depth of the convective boundary layer produced changes in chemistry aloft:
ozone increased at the surface when elevated layers of high O3 mixed downward
slope of NOy/O3 correlation aloft decreased when the mixed layer depth reached measurement altitude.
Showed that advection of O3 and its precursors by cyclonic systems can transport large quantities of O3 from North America into the North Atlantic and even to Europe.
Characterized the diel evolution of the boundary layer and the transport and circulation patterns in the Mexico City Valley and their influences on pollutant transport.
1.3 Aerosols
Found evidence for rapid new particle formation and nanoparticle growth in the remote troposphere through ternary nucleation (H2SO4 - NH3 - H2O).
Characterized the temporal and spatial variability of fine particle concentrations in the Mexico City Valley and made inferences regarding the importance of secondary aerosol formation and the relative contribution of local and regional sources.
1.4 Dry Air-Surface Exchange
Eddy correlation measurements of the vertical flux of NO2 and O3 at 5 m and 10 m above short maize indicated that the molar rate of O3 destruction seemed to exceed the molar production rate of NO2 suggesting that reactions involving NO, NO2, and O3 were insufficient to describe the destruction rate of O3.
A deposition velocity of 0.13 ± 0.08 cm-1 for PAN was measured above grassland vegetation. Theoretical calculations indicate that leaf stomata rather than the plant cuticular membrane control the uptake of PAN.
2. Development and/or Implementation of Methodology.
Developed and implemented a technique to separately measure organic and hydrogen peroxides.
Modified and used a tandem mass spectrometer for airborne measurements of trace species.
Developed of a technique for measurement of formaldehyde and other oxygenated hydrocarbons with 2-min time resolution.
Developed and implemented a wet scrubbing technique for measurement of nitric acid.
Implemented a technique for in-situ airborne measurements of gaseous hydrocarbons.
Developed a sensitive and rapid method for airborne measurement of PAN and NO2 with 2 min time resolution.
Implemented a high sensitivity technique for measurement of speciated NOy compounds.
Developed and implemented a technique for the airborne measurement of nanoparticle size spectra.
Developed a technique for airborne real time measurement of radon concentrations.
Implemented a technique for the airborne measurement of elemental and organic carbon fractions of aerosol particles.
3. Integration with other groups and programs
For a variety of reasons ACP has found it useful to establish connections
with other programs and groups pursuing similar goals. Such collaborations
are sought because of the utility of collaboration on scientific issues
and because of the need for resource sharing. Programs that we have collaborated
with since 1983 are shown in the table that follows.
| Program | Participating ACP Groups | Collaborating Organizations |
| NARE 1992-1993, 1997 | BNL, PNNL, BCL,
SUNY Old Westbury, University of Minnesota |
AES Canada,
NOAA Aeronomy Laboratory, Dalhousie University, NCAR, State of Maine, National Park Service, AEROCE, York University, British Met Office, University of Michigan |
| Southern Oxidants Study
(Nashville 1995) |
BNL, ANL, PNNL
SUNY Old Westbury |
NOAA Aeronomy Lab,
NOAA ETL, North Carolina State University, University of Alabama, Western Michigan University, Purdue University, Georgia Tech, NASA, EPA |
| NARSTO/NE 1995-1996 | BNL, ANL, PNNL
SUNY Old Westbury |
University of Maryland,
Sonoma Technology, NESCAUM, EPRI |
| Mexico City (1996) | ANL, PNNL | DRI, IMP, NOAA, DDF, PEMEX, EPA, University of Denver, University of
Utah, NCAR, Carnegie Mellon,
University of Illinois, LANL |
| MLOPEX 1995 | BNL | NCAR and numerous universities |
4. Internal Collaborations (Collaborations within the ACP Community)
One of the strengths of the ACP program is the extensive collaboration that has taken place between the DOE laboratories, and between the laboratories and university researchers that are funded by ACP. These collaborations have taken the form of joint planning, sharing of measurement technologies and measurement data, joint data interpretation and multi-organization publications. Examples of such internal ACP collaborations are given below.
4.1 NARE 1993
Collaborators included BNL, PNNL, SUNY Old Westbury and the University of Minnesota. Joint publications include:
Daum, P. H., L. I. Kleinman, L. Newman, W. T. Luke, J. Weinstein-Lloyd, C. M. Berkowitz, and K. M. Busness, Chemical and physical properties of plumes of anthropogenic pollutants transported over the North Atlantic During NARE, J. Geophys. Res., 101, 29,029-29,042, 1996.
Weinstein-Lloyd, J. B., and J. H. Lee, Analysis of hydrogen peroxide
by fluorescence spectroscopy,
J. Chem. Educ., 72, 1053-1055, 1995.
Weinstein-Lloyd, J. B., P. H. Daum, L. J. Nunnermacker, J. H. Lee, and L. I. Kleinman, Measurement of peroxides and related species in the 1993 North Atlantic Regional Experiment, J. Geophys. Res., 101, 29,081-29,090, 1996.
Zaucker, F., P. H. Daum, U. Wetterauer, C. M. Berkowitz, B. Kromer, and W. S. Broeker, Atmsopheric 222Rn measurements during the 1993 NARE intensive, J. Geophys. Res., 101, 29,149-29,164, 1996.
Collaborators included ANL, BNL, PNNL and SUNY Old Westbury. Joint publications include:
Nunnermacker, L. J., D.Imre, P. H. Daum, L. Kleinman, Y-N Lee, J. H. Lee, S. R. Springston, L. Newman, J. Weinstein-Lloyd, W. T. Luke, R. Banta, R. Alvarez, S. Sillman, M. Holdren, G. W. Keigley, and X. Zhou, Characterization of the Nashville urban plume on July 3 and July 18, 1995: I. O3 production Efficiency, kinetic analysis, and hydrocarbon apportionment, J. Geophys. Res. (in press).
Sillman, S., D. He, M. Pippen, P. H. Daum, J. H. Lee, L. I. Kleinman, and J. Weinstein-Lloyd, Model correlations for ozone, reactive nitrogen and peroxides for Nashville in comparison with measurements: Implications for O3-NOx-hydrocarbon chemistry, J. Geophys. Res. (in press).
Sillman, S., K. I. Al-Wali, F. J. Marsik, P. Nowacki, P. J. Samson, M. O. Rodgers, L. J. Garland, J. E. Martinez, C. Stoneking, R. Imhoff, J. H. Lee, L. Newman, J. Weinstein-Lloyd, and V. P. Aneja, Photochemistry of ozone formation in Atlanta, GA: Models and measurements, Atmos. Environ., 21, 3055-3066, 1995.
Weinstein-Lloyd, J., J. H. Lee, P. H. Daum, L. I. Kleinman, L. J. Nunnermacker, S. R. Springston, L. and Newman, Measurements of peroxides and related species during the 1995 summer intensive of the Southern Oxidants Study in Nashville, TN, J. Geophys. Res. (in press).
Joint publications include:
Hildemann, L. M., W. R. Rogge, G. R. Cass, M. A. Mazurek, and B. R. T. Simoneit, Contribution of primary aerosol emissions from vegetation-derived sources to fine particle concentrations in Los Angeles, J. Geophys. Res., 101, 19,541-19,549, 1996.
Weber, R. J., and P. H. McMurry, Fine particle size distributions at the Mauna Loa Observatory, Hawaii, J. Geophys. Res., 101, 14767-14775, 1996.
Weber, R. J., P.H. McMurry, F. L. Eisele, and D. J. Tanner, Measurement of expected nucleation precursor species and 3-500-nm diameter particles at Mauna Loa Observatory, Hawaii, J. Atmos. Sci., 52, 2242-2257, 1995.
Weber, R. J., J. Marti, P. H. McMurry, F. L. Eisele, D. J. Tanner, and A. Jefferson, Measured atmospheric new particle formation rates: implications for nucleation mechanisms, Chem. Eng. Comm., 151, 53-64, 1996.