A51G-01 INVITED 08:00h

Tropospheric Photochemistry Reflected in Ambient Measurements of Carbonyls and Alkyl Nitrates.

* Trainer, M (Michael.K.Trainer@noaa.gov) , NOAA, Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305 United States
Atlas, E (eatlas@rsmas.miami.edu) , University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149 United States
De Gouw, J (Joost.deGouw@noaa.gov) , NOAA, Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305 United States
De Gouw, J (Joost.deGouw@noaa.gov) , CIRES, University of Colorado, 216 UCB, Boulder, CO 80309 United States
Flocke, F (ffl@ucar.edu) , NCAR, 1850 Table Mesa Drive, Boulder, CO 80305 United States
Fried, A (fried@ucar.edu) , NCAR, 1850 Table Mesa Drive, Boulder, CO 80305 United States
Goldan, P (Paul.D.Goldan@noaa.gov) , NOAA, Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305 United States
Holloway, J (John.S.Holloway@noaa.gov) , NOAA, Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305 United States
Holloway, J (John.S.Holloway@noaa.gov) , CIRES, University of Colorado, 216 UCB, Boulder, CO 80309 United States
Huey, G (greg.huey@eas.gatech.edu) , Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332 United States
Kuster, W (William.C.Kuster@noaa.gov) , NOAA, Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305 United States
Neuman, A (Andy.Neuman@noaa.gov) , NOAA, Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305 United States
Neuman, A (Andy.Neuman@noaa.gov) , CIRES, University of Colorado, 216 UCB, Boulder, CO 80309 United States
Parrish, D (David.D.Parrish@noaa.gov) , NOAA, Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305 United States
Roberts, J (James.M.Roberts@noaa.gov) , NOAA, Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305 United States
Ryerson, T (Thomas.B.Ryerson@noaa.gov) , NOAA, Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305 United States
Stroud, C (cstroud@ucar.edu) , NCAR, 1850 Table Mesa Drive, Boulder, CO 80305 United States
Warneke, C (Carsten.Warneke@noaa.gov) , NOAA, Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305 United States
Warneke, C (Carsten.Warneke@noaa.gov) , CIRES, University of Colorado, 216 UCB, Boulder, CO 80309 United States

The oxidation of volatile organic compounds (VOCs) in the presence of nitrogen oxides leads to the formation of ozone in the troposphere. Besides ozone, other secondary species such as carbonyls and organic nitrates are formed that are characteristic of the parent VOC species. Ambient measurements of secondary species reflect the integrated effect of emissions, photochemical production and loss, as well as other removal processes. Analysis of ambient measurements of select secondary species that were made during recent field experiments are used here to evaluate the understanding of tropospheric photochemistry.

A51G-02 08:30h

A Comparative Study of Ozone Production in 5 U.S. Metropolitan Areas

* Kleinman, L I (kleinman@bnl.gov) , Brookhaven National Laboratory, Atmospheric Sciences Divisions, Upton, NY 11973 United States
Daum, P H (phdaum@bnl.gov) , Brookhaven National Laboratory, Atmospheric Sciences Divisions, Upton, NY 11973 United States
Lee, Y (ynlee@bnl.gov) , Brookhaven National Laboratory, Atmospheric Sciences Divisions, Upton, NY 11973 United States
Nunnermacker, L J (lindan@bnl.gov) , Brookhaven National Laboratory, Atmospheric Sciences Divisions, Upton, NY 11973 United States
Springston, S R (srs@bnl.gov) , Brookhaven National Laboratory, Atmospheric Sciences Divisions, Upton, NY 11973 United States
Weinstein-Lloyd, J (jlloyd@bnl.gov) , SUNY/Old Westbury, Chemistry/Physics Department, Old Westbury, NY 11568 United States

We present observations of O$_{3}$ and O$_{3}$ precursors measured at mid boundary layer altitude during field campaigns in Nashville, TN (1995), New York City, NY (1996), Phoenix, AZ (1998), Philadelphia, PA (1999), and Houston, TX (2000). Ozone production rates, P(O$_{3}$) and their sensitivity to NO$_{x}$ and VOCs, are calculated using observed concentrations as inputs to a steady state box model. City to city comparisons are made to illustrate common features of urban photochemistry and features that are unique to specific cities. Ozone production rates vary from nearly zero to 155 ppb h$^{-1}$. Differences in P(O$_{3}$) depend on precursor concentrations; namely, radical sources, NO$_{x}$ and VOCs. Under conditions where P(O$_{3}$) is greater than 25 ppb h$^{-1}$, there is a potential to produce enough same-day O$_{3}$ to transform a typical regional background into a severe O$_{3}$ episode. Six such cases were observed, in Nashville, Philadelphia, and Houston, with elevated O$_{3}$ concentrations in the afternoon (130-211 ppb) following a morning in which P(O$_{3}$) was 25 - 140 ppb h$^{-1}$. High P(O$_{3}$) occurs when NO$_{x}$ concentrations are 5 to 25 ppb and OH-VOC reactivity is above 5 s$^{-1}$. These conditions are infrequent and aside from a common dependence on calm winds reasons vary from city to city.

A51G-03 08:45h

The Budget of Ozone and its Precursors as Calculated by the Global Modeling Initiative

* Rodriguez, J M (jrodriguez@rsmas.miami.edu) , Rosenstiel School of Marine and Atmospheric Science, University of Miami 4600 Rickenbacker Causeway, Miami, FL 33149 United States
Duncan, B N (duncan@hyperion.gsfc.nasa.gov) , Goddard Earth Science and Technology Center, University of Maryland, Baltimore County/NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
Logan, J A (jal@io.harvard.edu) , Harvard University, 29 Oxford Street, Cambridge, MA 02138 United States
Das, B (bdas@nccs.gsfc.nasa.gov) , Advanced Management Technology, Inc., NASA/Goddard Space Flight Center, Greenbelt, MD 20771 United States
Kouatchou, J (kouatchou@gsfc.nasa.gov) , Computer Sciences Corporation, Inc., NASA/Goddard Space Flight Center, Greenbelt, MD 20771 United States
Strahan, S E (strahan@prometheus.gsfc.nasa.gov) , Goddard Earth Science and Technology Center, University of Maryland, Baltimore County/NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States

Simulations of tropospheric ozone and its precursors have been carried out by the Global Modeling Initative (GMI) chemical-transport model (CTM). The simulations incorporate meteorological fields obtained from the Community Climate Model (CCM), Goddard Institute for Space Studies (GISS), and the NASA/Goddard's Global Modeling and Analysis Office (GMAO). All other model components are the same across simulations with different meteorological fields. Incorporation of new kinetic data for O(1D) reactions improves the model-calculated lifetime of methyl chloroform. The performance of the model utilizing the different meteorological fields is also evaluated by statistical comparison to measurements from ozone sondes, surface CO and ozone measurements, and other measurements The model results are used to diagnose the relative importance of different chemical and meteorological processes that determine concentrations of ozone and its precursors at regional and global scales, and how the characteristics of different meteorological fields influence these diagnosed budgets.

A51G-04 09:00h

Interpretation of unexpected high daytime values of nitrous acid (HONO) and its implications for the OH budget in daytime urban environments

* Trick, S (strick@atmos.ucla.edu) , University of California Los Angeles, Department of Atmospheric and Oceanic Sciences, 7127 Math Sciences Bldg., 405 Hilgard Avenue, Box 951565, Los Angeles, CA 90095-1565 United States
* Trick, S (strick@atmos.ucla.edu) , Ruprecht - Karls Universit\"{a}t Heidelberg, Institut f\"{u}r Umweltphysik, Im Neuenheimer Feld 229, Heidelberg, D - 69120 Germany
Geyer, A (andreas@atmos.ucla.edu) , University of California Los Angeles, Department of Atmospheric and Oceanic Sciences, 7127 Math Sciences Bldg., 405 Hilgard Avenue, Box 951565, Los Angeles, CA 90095-1565 United States
Platt, U (ulrich.platt@iup.uni-heidelberg.de) , Ruprecht - Karls Universit\"{a}t Heidelberg, Institut f\"{u}r Umweltphysik, Im Neuenheimer Feld 229, Heidelberg, D - 69120 Germany
Stutz, J (jochen@atmos.ucla.edu) , University of California Los Angeles, Department of Atmospheric and Oceanic Sciences, 7127 Math Sciences Bldg., 405 Hilgard Avenue, Box 951565, Los Angeles, CA 90095-1565 United States

For decades, the photolysis of nitrous acid (HONO) has been considered to be an important net source of OH radicals only in the early morning hours. The impact of HONO photolysis on the HO$_{x}$ budget was considered to be of minor impor-tance, compared to the photolysis of O$_{3}$ and HCHO, since HONO levels were generally reported to be close to their photostationary state with OH and NO. Recent field measurements by Differential Optical Absorption Spectroscopy (DOAS) at various urban and suburban locations found that under certain circumstances HONO mixing ratios could significantly exceed this photostationary state, reaching $\sim$ 200 ppt at noon. Thus far, these high levels of HONO could not be explained by any model calculations. Consequently, the contribution of HONO to the daytime OH budget in urban environments could not be quantified satisfactorily. Here, we present an analysis of the daytime HONO observations using a 1-dimensional chemical-transport model. Urban scenarios in the model include, for the first time, chemical interactions of trace gases with the urban canopy. Our study shows that the heterogeneous conversion of NO$_{2}$ on the ground, building walls and roofs has a significant impact on daytime HONO levels. Aerosols were found to be of minor importance under all circumstances. In addition, direct emis-sions of HONO also have to be considered. The model results give further evidence that HONO photolysis can act as an important OH source in urban boundary layer throughout the entire day.

A51G-05 09:15h

Long-Range Transport of Smoke From 2004 Forest Fires in Alaska and Western Canada

* de Gouw, J A (Joost.deGouw@noaa.gov) , Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 United States
* de Gouw, J A (Joost.deGouw@noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States
Warneke, C (cwarneke@al.noaa.gov) , Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 United States
Warneke, C (cwarneke@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States
Stohl, A (astohl@al.noaa.gov) , Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 United States
Stohl, A (astohl@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States
Cooper, O R (ocooper@al.noaa.gov) , Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 United States
Cooper, O R (ocooper@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States
Hudson, P K (phudson@al.noaa.gov) , Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 United States
Hudson, P K (phudson@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States
Murphy, D M (murphyd@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States
Brock, C A (cbrock@al.noaa.gov) , Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 United States
Brock, C A (cbrock@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States
Flocke, F (ffl@ucar.edu) , NCAR - ACD, 1850 Table Mesa, Boulder, CO 80305 United States
Fehsenfeld, F C (fcf@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States
Holloway, J S (holloway@al.noaa.gov) , Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 United States
Holloway, J S (holloway@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States
Matthew, B (bmatthew@al.noaa.gov) , Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 United States
Matthew, B (bmatthew@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States
Middlebrook, A M (amiddlebrook@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States
Neuman, A (aneuman@al.noaa.gov) , Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 United States
Neuman, A (aneuman@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States
Nowak, J B (jnowak@al.noaa.gov) , Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 United States
Nowak, J B (jnowak@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States
Peltier, R (rpeltier@eas.gatech.edu) , School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332 United States
Roberts, J M (jr@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States
Ryerson, T B (tryerson@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States
Swanson, A (aswanson@ucar.edu) , Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 United States
Swanson, A (aswanson@ucar.edu) , NCAR - ACD, 1850 Table Mesa, Boulder, CO 80305 United States
Trainer, M (trainer@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States
Weber, R J (rweber@eas.gatech.edu) , School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332 United States
Wollny, A (awollny@al.noaa.gov) , Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 United States
Wollny, A (awollny@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway R/AL7, Boulder, CO 80305 United States

In the summer of 2004 extensive forest fires were burning in Alaska and western Canada. The outflow of gas-phase and aerosol species was observed over the northeastern U.S. and southeastern Canada during multiple research flights of the NOAA WP-3D aircraft. Various satellite products and chemical forecasts were used to design the flight tracks prior to take off, and images from the GOES satellite at 1 km resolution were used during flights to target the plumes using near real-time information. The approach was highly successful in localizing the forest fire plumes. In-situ measurements of acetonitrile (CH$_{3}$CN) using PTR-MS (Proton Transfer Reaction Mass Spectrometry) and of individual particles containing both potassium and carbon using PALMS (Particle Analysis by Laser Mass Spectrometry) clearly distinguished the forest fire plumes from other (urban and industrial) sources of pollution. Different intercepts of the plume showed a varying degree of photochemical processing of the forest fire emissions. In addition forest fire smoke was observed close to the surface during a nighttime flight around Boston, with a clear impact on the regional air quality for a limited period.

A51G-06 09:30h

Understanding the Impact of North American Outflow on Tropospheric O$_{3}$ over the North Atlantic Ocean: A Case Study During ICARTT 2004

* Mao, H (hmao@typhoon.sr.unh.edu) , Institute for the Study of Earth, Oceans, and Space, Morse Hall, University of New Hampshire, Durham, NH 03824 United States
Talbot, R (robert.talbot@unh.edu) , Institute for the Study of Earth, Oceans, and Space, Morse Hall, University of New Hampshire, Durham, NH 03824 United States
Troop, D (don.troop@unh.edu) , Institute for the Study of Earth, Oceans, and Space, Morse Hall, University of New Hampshire, Durham, NH 03824 United States
Businger, S (businger@hawaii.edu) , Department of Meteorology, University of Hawaii, Honolulu, HI 96822 United States
Johnson, R (randy.johnson@noaa.gov) , NOAA Air Resources Laboratory, Field Research Division, Idaho Falls, ID 83402 United States

The objective of this study was to investigate the mechanisms contributing to the temporal and spatial variations of ozone (O$_{3}$) levels in North American continental outflow over the North Atlantic Ocean during a high O$_{3}$ episode on July 17 - 25, 2004. An observational data analysis was carried out for this time period to document variations in O$_{3}$ mixing ratios in urban plumes traveling over the North Atlantic using measurements obtained from the NOAA smart balloon Lagrangian Flight \#2. Flight \#2 started from Long Island, New York and landed near Prince Edward Island, Nova Scotia. This analysis was complemented by model simulations of the distributions of O$_{3}$ and its precursors using an air quality modeling system (i.e. MM5, SMOKE, and CMAQ). The models were rigorously evaluated using the meteorological and chemical measurements from ground and mobile platforms employed in the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) field campaign. The balloon O$_{3}$ measurements exhibited large variations in O$_{3}$ levels in the North American outflow at fairly constant altitudes of 400 - 600 m with the peak value of 195 ppbv observed on the night of July 20. It is hypothesized that local convection, {\it in situ} chemistry and strong detrainment/entrainment could be the primary causes for such large horizontal gradients. Our model results suggest that such enhanced levels of O$_{3}$ can potentially have a great impact on the chemical environments of the remote North Atlantic region.

A51G-07 09:45h

Regional Chemical Forecast for ICARTT Field Experiment: Evaluation of the Performance

* Carmichael, G R (gcarmich@engineering.uiowa.edu) , Center for Global and Regional Environmental Research, University of Iowa, Iowa City, IA 52242 United States
Tang, Y (ytang@cgrer.uiowa.edu) , Center for Global and Regional Environmental Research, University of Iowa, Iowa City, IA 52242 United States
Chai, T (tchai@cgrer.uiowa.edu) , Center for Global and Regional Environmental Research, University of Iowa, Iowa City, IA 52242 United States
Thongboonchoo, N (nthongbo@cgrer.uiowa.edu) , Center for Global and Regional Environmental Research, University of Iowa, Iowa City, IA 52242 United States
Horowitz, L W (larry.horowitz@noaa.gov) , NOAA Geophysical Fluid Dynamics Laboratory, Princeton University, Princeton, NJ 08542 United States
Levy, H (hl@gfdl.gov) , NOAA Geophysical Fluid Dynamics Laboratory, Princeton University, Princeton, NJ 08542 United States
Sandu, A (asandu@cs.vt.edu) , Department of Computer Science, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 United States
Mena, M M (mamena@cgrer.uiowa.edu) , Center for Global and Regional Environmental Research, University of Iowa, Iowa City, IA 52242 United States
Adhikary, B (adhikary@cgrer.uiowa.edu) , Center for Global and Regional Environmental Research, University of Iowa, Iowa City, IA 52242 United States
Avery, M A (m.a.avery@larc.nasa.gov) , NASA Langley Research Center, MS 483, Hampton, VA 23681 United States
Ryerson, T B (tryerson@al.noaa.gov) , NOAA Aeronomy Laboratory, 325 Broadway, Boulder, CO 80303 United States
Thompson, A M (anne.m.thompson@nasa.gov) , NASA Goddard Space Flight Center, MC 916, Greenbelt, MD 20771

The ICARTT (International Consortium for Atmospheric Research on Transport and Transformation) field experiment was performed in July and August, 2004. For this campaign, we designed a regional chemical forecast system including two domains for tracer forecasting and 3 nested full-chemical forecasts (60km, 12km and 4km horizontal resolutions). In this forecast activity, we implemented real-time coupling with MOZART global chemical forecast through the lateral and top boundary conditions. Model forecasts were extensively compared to aircraft, satellite, surface and ship measurements. The 12km nested forecast also participated in real-time model inter-comparisons for NOAA AIRMAP surface observations. Forecasts source-tagged CO tracers provided further insights into airmass origin and characteristics. The multi-scale forecasts showed different results, and this forecast difference reflects the variations caused by the performances of meteorological model, emissions and photochemical behaviors in different scales. The forecast over surface site near strong sources, such as power plants, shows the most obvious sensitivity to model resolution. Several case studies illustrated the model performance under different scenarios and corresponding influencing factors. In addition 4dVar assimilation techniques were developed and used during the experiment. Results showing the effect of data assimilation of surface, aircraft and ozonesonde data on the prediction skill are also presented.

Author(s) (2004), Title, Eos Trans. AGU, 85(47), Fall Meet. Suppl., Abstract #####-##.