Atmospheric Photochemistry (OCN 643)

Barry Huebert

Time and Location
Class meets Tuesdays and Thursdays. Since I will be traveling during a few scheduled class periods, several classes will have to be moved. I generally put those on Wednesdays, but we check all our schedules on the first class day to find the optimum replacement times.
Content
This course focuses on the gas-phase chemistry of the atmosphere, which is driven to a large extent by photochemical processes. We start by discussing the principles of photochemistry and kinetics, experimental reaction-rate determinations, surface reactions, and atmospheric measurements. Then we examine the detailed chemistry of carbon-containing compounds, ozone and oxidants, nitrogen oxides, sulfur species, halogens, and stratospheric compounds. The course emphasizes the differences between polluted and natural atmospheric processes, with a greater emphasis on the cleaner regions. Since models are essential to determining the effects of dozens of simultaneous reactions, students exercise a simple model to test the impact of changes in reaction rates and chemical composition.
Readings
The assigned readings will be from either the literature or the class text, Finlayson-Pitts and Pitts, Atmospheric Chemistry, Wiley and Sons, 1986. The published papers are collected into a xeroxed set for the class. In order to ensure that the reading is completed prior to the class discussion, any person in the room may be randomly selected to lead a discussion of any of the reading. (Papers from the literature are generally be handled this way, but some text discussions will also be student-led.) Twenty percent of the grade is based on your discussions.
Modeling
Each student is given an assignment to perform using a simple photochemical model. The procedure used and results obtained are then described in a short report (several pages and several figures) on the activity.
Exams
Two exams are be given, a midterm and a final. Approximately two potential exam questions will be handed out each class period. The exams will be drawn from these or similar questions, so it is important that each student know how to work the problems or find the answers.
Grading
- 20% Class discussions of papers
- 20% Modeling & report
- 25% Mid-term exam
- 35% Comprehensive final exam

Syllabus for 1996 course

Date	Subject	Preliminary Readings & Due Dates
11 Jan Thurs	Intro & Overview Photochemistry	FPP 59-66
16 Jan Tues	Photochemistry & Spectroscopy	FPP 66-91
18 Jan Thurs	Fundamentals of Kinetics	FPP 209-235
23 Jan Tues	Solar radiation and extinction	FPP 93-128
24 Jan Wed	Photolysis; species' absorption spectra and photochemistry	FPP 129-157 Each student will describe one compound's behavior to the class
25 Jan Thurs	Species' absorption spectra and photochem	FPP 158-199 Each student will describe one compound's behavior to the class
30 Jan Tues	Experimental methods	FPP 235-265
1 Feb Thurs	Relative rates, Rxns in solution	FPP 265-284
6 Feb Tues	Surface rxns, Adsorption isotherms	FPP 284-298
7 Feb Wed	Measurement methods	FPP 305-337
8 Feb Thurs	Measurements, Intercomparisons	FPP 337-370 [Gregory et al., 1993]
13 Feb Tues	Alkane & alkene photochem	FPP 405-420, 425-426, 431-434, 441-443, 469-472, 485
15 Feb Thurs	CH4 and global carbon	[Khalil and Rasmussen, 1990a] [Khalil and Rasmussen, 1990b] ??Logan CO??
20 Feb Tues	CH4 and remote ozone production	FPP 973-993 [Zimmermann and Poppe, 1993]
22 Feb Thurs	Remote FT photochemistry	[Liu et al., 1992]
27 Feb Tues	Midterm Exam	*
29 Feb Thurs	Oxidized nitrogen	FPP 522-548 and 693-699
5 Mar Tues	NOy and MLOPEX	[Atlas et al., 1992] SLINN, DOE, 4/93, pp 12-20
6 Mar Wed	PAN & Organic N	FPP 548-555 and 571-579 [Ridley, 1991]
7 Mar Thurs	NOx budget Sources	[Logan, 1983] pp 10,785-10,795
12 Mar Tues	NOx budget Sinks	Logan, 1983, pp 10,795-10,802 [DucFPP 589-600 and 961-973^M SLINN, DOE, 1/93, pp 2-8e, 1986] pp 497-510
14 Mar Thurs	Tropospheric ozone	FPP 589-600 and 961-973 SLINN, DOE, 1/93, pp 2-8
19 Mar Tues	Anthropogenic ozone^M control	NRC, 1991, pp 163-175 and 351-377
21 Mar Thurs	Modeling	FPP 602-624
25-29 Mar	SPRING BREAK	*
1 Apr Tues	Pollution SO2 and sulfate	FPP 645-693
4 Apr Thurs	DMS & "conventional wisdom" sulfur budget	FPP 993-999; [Yin et al., 1990]
9 Apr Tues	\DMS - other views	[Huebert et al., 1993];[Huebert et al., 1996]
11 Apr Thurs	Halogens in the troposphere	FPP 999-1001; [Keene et al., 1990]
25 Apr Thurs	Stratospheric ozone - The Early Years	FPP 1011-1027, [Johnston, 1971]; [Molina and Rowland, 1974]
30 Apr Tues	Ozone hole	[Zurer, 1993] SLINN, DOE, 6/93
2 May Thurs	Heterogeneous Stratospheric chemistry	[Rodriguez et al., 1991]; [Drdla et al., 1993]
6-10 May	FINAL EXAM	*

Atlas, E.L., B.A. Ridley, G. H｜ler, M.A. Carroll, D.D. Montzka, B. Huebert, R.B. Norton, J. Walega, F. Grahek, and S. Schauffler, Partitioning and Budget of NOy Species During MLOPEX, J. Geophys. Res., 97 (D10), 10,449-10,462, 1992.
Drdla, K., R.P. Turco, and S. Elliott, Heterogeneous Chemistry on Antarctic Polar Stratospheric Clouds: A Microphysical Estimate of the Extent of Chemical Processing, J. Geophys. Res., 98 (D5), 8965-8982, 1993.
Duce, R.A., The Impact of Atmospheric Nitrogen, Phosphorous, and Iron Species on Marine Biological Productivity, in The Role of Air-Sea Exchange in Geochemical Cycling, edited by P. Buat-Menard, pp. 497-529, D. Reidel, 1986.
Gregory, G.L., L.S. Warren, D.D. Davis, M.O. Andreae, A.R. Bandy, R.J. Ferek, J.E. Johnson, E.S. Saltzman, and D.J. Cooper, An Intercomparison of instrumentation for tropospheric measurements of dimethyl sulfide: Aircraft results for concentrations at the parts-per-trillion level, J. Geophys. Res., 98 (D12), 23,373-23,388, 1993.
Huebert, B.J., S. Howell, P. Laj, J.E. Johnson, T.S. Bates, P.K. Quinn, V. Yegorov, A.D. Clarke, and J.N. Porter, Observations of the Atmospheric Sulfur Cycle on SAGA 3, J. Geophys. Res., 98 (D9), 16,985-16,995, 1993.
Huebert, B.J., D.J. Wylie, L. Zhuang, and J.A. Heath, Production and loss of methanesulfonate and non-sea salt sulfate in the equatorial Pacific marine boundary layer, Geophys. Res. Letts. (April), 1996.
Johnston, H.S., Reduction of Stratospheric ozone by nitrogen oxide catalysts from supersonic transport exhaust, Science, 173, 517, 1971.
Keene, W.C., A.A.P. Pszenny, D.J. Jacob, R.A. Duce, J.N. Galloway, J.J. Schultz-Tokos, H. Sievering, and J.F. Boatman, The geochemical cycling of reactive chlorine through the marine atmosphere, Global Biogeochemical Cycles, 4, 407-430, 1990.
Khalil, M.A.K., and R.A. Rasmussen, Constraints on the Global Sources of Methane and an Analysis of Recent Budgets, Tellus, 42B (3), 229-236, 1990a.
Khalil, M.A.K., and R.A. Rasmussen, The Global Cycle of Carbon Monoxide: Trends and Mass Balance, Chemosphere, 20 (1-2), 227-242, 1990b.
Liu, S.C., M. Trainer, M.A. Carroll, G. H｜ler, D.D. Montzka, R.B. Norton, B.A. Ridley, J.G. Walega, E.L. Atlas, B.G. Heikes, B.J. Huebert, and W. Warren, A Study of the Photochemistry During MLOPEX, 1988, J. Geophys. Res., 97, 10,463-10,471, 1992.
Logan, J.A., Nitrogen Oxides in the Troposphere: Global and Regional Budgets, JGR, 88 (C15), 10,785-10,807, 1983.
Molina, M.J., and F.S. Rowland, Stratospheric sink for chlorofluoromethanes: Chlorine atom catalyzed destruction of ozone, Nature, 249, 810, 1974.
Ridley, B.A., Recent Measurements of Oxidized Nitrogen Compounds in the Troposphere, AE, 25A (9), 1905-1926, 1991.
Rodriguez, J.M., M.K.W. Ko, and N.D. Sze, Role of heterogeneous conversion of N2O5 on sulfate aerosols in global ozone loss, Nature, 352, 134-137, 1991.
Yin, F., D. Grosjean, and J.H. Seinfeld, Photooxidation of DMS and DMDS. I: Mechanism Development, J. Atmos. Chem., 11, 309-364, 1990.
Zimmermann, J., and D. Poppe, Nonlinear Chemical Couplings in the Tropospheric NOx-OHx Gas Phase Chemistry, J. Atmos. Chem., 17 (2), 141-156, 1993.
Zurer, P.S., Ozone Depletion's Recurring Surprises Challenge Atmospheric Scientists, Chem. & Eng. News (24 May), 8-18, 1993.

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