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Trans-Pacific transport and evolution of aerosols and trace gases from Asia during the INTEX-B field campaign
1Center for Global and Regional Environmental Research, University of Iowa, Iowa City, IA 52242, USA
2Decision and Information Sciences Division, Argonne National Laboratory, Argonne, IL, USA
3NASA Langley Research Center, Hampton, VA, USA
4National Center for Atmospheric Research, Boulder, CO, USA
5Department of Chemistry, University of California, Irvine, CA, USA
6Department of Meteorology, Penn State University, University Park, PA, USA
7Department of Chemistry, University of California, Berkeley, CA, USA
8Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH, USA
9Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA
10School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
11United States Naval Academy, Annapolis, MD, USA
12NASA Ames Research Center, Moffett Field, CA, USA
13Department of Chemistry and Biochemistry, and CIRES, University of Colorado, Boulder, CO, USA
14California Institute of Technology, Pasadena, CA, USA
15Environmental Chemistry and Technology, College of Engineering, University of Wisconsin-Madison, Madison, WI, USA
16University of Washington, Bothell, WA 98011, USA
17Department of Atmospheric Sciences/University of Washington, Seattle, WA 98195, USA
*now at: School of Engineering, Kathmandu University, P.O. Box 6250, Dhulikhel, Nepal
**now at: NOAA/NCEP/EMC, Camp Springs, MD, USA
***now at: ARIANET Srl, Via Gilino, 20128, Milano, Italy
****now at: Universidad Andrés Bello, Department of Environmental Engineering, Santiago, Chile
*****now at: Advanced Satellite Products Branch, NOAA/NESDIS/STAR/CIMSS, Madison, WI, USA
******now at: NOAA Climate Program Office, Silver Spring, MD, USA
Abstract. The Sulfur Transport and dEposition Model (STEM) developed at the University of Iowa is applied to the analysis of observations obtained during the Intercontinental Chemical Transport Experiment-Phase B (INTEX-B), conducted over the Pacific Ocean during the 2006 North American spring season. This paper reports on the model performance of meteorological parameters, trace gases, aerosols and photolysis rate (J-values) predictions with the NASA DC-8 and NSF/NCAR C-130 airborne measurements along with observations from three surface sites Mt. Bachelor, Trinidad Head and Kathmandu, Nepal. In general the model shows appreciable skill in predicting many of the important aspects of the observed distributions. The major meteorological parameters driving long range transport are accurately predicted by the WRF simulations used in this study. Furthermore, the STEM model predicts aerosols and trace gases concentrations within a standard deviation of most of the observed mean values. The results also point towards areas where model improvements are needed; e.g., the STEM model underestimates CO (15% for the DC8 and 6% for the C-130), whereas it overpredicts PAN (by a factor of two for both aircraft). The errors in the model calculations are attributed to uncertainty in emissions estimates and uncertainty in the top and lateral boundary conditions. Results from a series of sensitivity simulations examining the impact of the growth of emissions in Asia from 2000 to 2006, the importance of biomass burning, the effect of using boundary conditions from different global models, and the role of heterogeneous chemistry on the predictions are also presented. The impacts of heterogeneous reactions at specific times during dust transport episodes can be significant, and in the presence of dust both sulfate and nitrate aerosol production is increased and gas phase nitric acid levels are reduced appreciably (~50%). The aging of the air masses during the long range transport over the Pacific and the impact of various sources (source regions as well as energy and biomass burning) on targeted observations are analyzed using back-trajectories and tagged CO-tracer analysis.
Discussion Paper (PDF, 22252 KB) Supplement (1064 KB) Interactive Discussion (Final Response, 4 Comments)
Citation: Adhikary, B., Carmichael, G. R., Kulkarni, S., Wei, C., Tang, Y., Dallura, A., Mena-Carrasco, M., Streets, D. G., Zhang, Q., Pierce, R. B., Al-Saadi, J. A., Emmons, L. K., Pfister, G. G., Avery, M. A., Barrick, J. D., Blake, D. R., Brune, W. H., Cohen, R. C., Dibb, J. E., Fried, A., Heikes, B. G., Huey, L. G., O'Sullivan, D. W., Sachse, G. W., Shetter, R. E., Singh, H. B., Campos, T. L., Cantrell, C. A., Flocke, F. M., Dunlea, E. J., Jimenez, J. L., Weinheimer, A. J., Crounse, J. D., Wennberg, P. O., Schauer, J. J., Stone, E. A., Jaffe, D. A., and Reidmiller, D. R.: Trans-Pacific transport and evolution of aerosols and trace gases from Asia during the INTEX-B field campaign, Atmos. Chem. Phys. Discuss., 9, 16381-16439, 2009. Bibtex EndNote Reference Manager
