References

ACP

Atmospheric Chemistry and Physics

ACP

Atmos. Chem. Phys.

1680-7324

Copernicus Publications

Göttingen, Germany

10.5194/acp-12-11003-2012

Thunderstorms and upper troposphere chemistry during the early stages of the 2006 North American Monsoon

Barth

M. C.

¹ Lee

¹ Hodzic

¹ Pfister

¹ Skamarock

W. C.

¹ Worden

² Wong

³ Noone

National Center for Atmospheric Research, Boulder, Colorado, USA

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA

Department of Atmospheric and Oceanic Sciences and Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA

21 11 2012

12 22 11003 11026

2012

This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/

This article is available from https://acp.copernicus.org/articles/12/11003/2012/acp-12-11003-2012.html

The full text article is available as a PDF file from https://acp.copernicus.org/articles/12/11003/2012/acp-12-11003-2012.pdf

To study the meteorology and chemistry that is associated with the early stages of the North American Monsoon, the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) is applied for the first time at high resolution (4 km grid spacing, allowing for explicit representation of convection) over a large region (continental US and northern Mexico) for a multi-week (15 July to 7 August 2006) integration. Evaluation of model results shows that WRF-Chem reasonably represents the large-scale meteorology and strong convective storms, but tends to overestimate weak convection. In the upper troposphere, the WRF-Chem model predicts ozone (O3) and carbon monoxide (CO) to within 10–20% of aircraft and sonde measurements. Comparison of UT O3 and CO frequency distributions between WRF-Chem and satellite data indicates that WRF-Chem is lofting CO too frequently from the boundary layer (BL). This excessive lofting should also cause biases in the WRF-Chem ozone frequency distribution; however it agrees well with satellite data suggesting that either the chemical production of O3 in the model is overpredicted or there is too much stratosphere to troposphere transport in the model. Analysis of different geographic regions (West Coast, Rocky Mountains, Central Plains, Midwest, and Gulf Coast) reveals that much of the convective transport occurs in the Rocky Mountains, while much of the UT ozone chemical production occurs over the Gulf Coast and Midwest regions where both CO and volatile organic compounds (VOCs) are abundant in the upper troposphere and promote the production of peroxy radicals. In all regions most of the ozone chemical production occurs within 24 h of the air being lofted from the boundary layer. In addition, analysis of the anticyclone and adjacent air indicates that ozone mixing ratios within the anticyclone region associated with the North American Monsoon and just outside the anticyclone are similar. Increases of O3 within the anticyclone are strongly coincident with entrainment of stratospheric air into the anticyclone, but also are from in situ O3 chemical production. In situ O3 production is up to 17% greater within the anticyclone than just outside the anticyclone when the anticyclone is over the southern US indicating that the enhancement of O3 is most pronounced over regions with abundant VOCs.

References 1

Ackermann, I. J., Hass, H., Memmesheimer, M., Ebel, A., Binkowski, F. S., and Shankar, U.: Modal aerosol dynamics model for Europe: Development and first applications, Atmos. Environ., 32, 2981–2999, 1998.

Allen, D., Pickering, K., Duncan, B., and Damon, M: Impact of lightning NO emissions on North American photochemistry as determined using the Global Modeling Initiative (GMI) model, J. Geophys. Res., 115, D22301, <a href="http://dx.doi.org/10.1029/2010JD014062">https://doi.org/10.1029/2010JD014062</a>, 2010.

Allen, D. J., Pickering, K. E., Pinder, R. W., Henderson, B. H., Appel, K. W., and Prados, A.: Impact of lightning-NO on eastern United States photochemistry during the summer of 2006 as determined using the CMAQ model, Atmos. Chem. Phys., 12, 1737–1758, <a href="http://dx.doi.org/10.5194/acp-12-1737-2012">https://doi.org/10.5194/acp-12-1737-2012</a>, 2012.

Baughcum, S., Tritz, T., Henderson, S., and Pickett, D.: Scheduled Civil Aircraft Emission Inventories for 1992: Database Development and Analysis, NASA Contractor Report 4700, available at: <a href="http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19960038445 1996060751.pdf">http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19960038445 1996060751.pdf</a>, (last access: August 2007), 1996.

Baughcum, S., Henderson, S., and Sutkus, D.: Scheduled Civil Aircraft Emission Inventories Projected for 2015: Database Development and Analysis, NASA/CR-1998-207638, available at: <a href="http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980055200 1998120133.pdf">http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980055200 1998120133.pdf</a>, (last access: August 2007), 1998.

Binkowski, F. S. and Shankar, U.: The regional particulate matter model, 1. Model description and preliminary results, J. Geophys. Res., 100, 26191–26209, 1995.

Boccippio, D. J., Cummins, K. L. Christian, H. J., and Goodman, S. J.: Combined satellite- and surface-based estimation of the intracloud-cloud-to-ground lightning ratio over the continental United States, Mon. Weather Rev., 129, 108–122, 2001.

Cavallo, S. M., Dudhia, J., and Snyder, C.: A multilayer upper-boundary condition for longwave radiative flux to correct temperature biases in a mesoscale model, Mon. Weather Rev., 139, 1952–1959, 2011.

Chapman, E. G., Gustafson Jr., W. I., Easter, R. C., Barnard, J. C., Ghan, S. J., Pekour, M. S., and Fast, J. D.: Coupling aerosol-cloud-radiative processes in the WRF-Chem model: Investigating the radiative impact of elevated point sources, Atmos. Chem. Phys., 9, 945–964, <a href="http://dx.doi.org/10.5194/acp-9-945-2009">https://doi.org/10.5194/acp-9-945-2009</a>, 2009.

Chatfield, R. B. and Crutzen, P. J.: Sulfur dioxide in remote oceanic air: Cloud transport of reactive precursors, J. Geophys. Res., 89, 7111–7132, 1984.

Chen, F. and Dudhia, J.: Coupling an advanced land-surface/ hydrology model with the Penn State/NCAR MM5 modeling system, Part I: Model description and implementation. Mon. Weather Rev., 129, 569–585, 2001.

Choi, Y., Kim, J., Eldering, A., Osterman, G., Yung, Y. L., Gu, Y., and Liou, K. N.: Lightning and anthropogenic NOx sources over the United States and the western North Atlantic Ocean: Impact on OLR and radiative effects, Geophys. Res. Lett., 36, L17806, <a href="http://dx.doi.org/10.1029/2009GL039381">https://doi.org/10.1029/2009GL039381</a>, 2009.

Chou M.-D. and Suarez, M. J.: An efficient thermal infrared radiation parameterization for use in general circulation models, NASA Tech. Memo. 104606, 3, 85 pp. 1994.

Cooper, O. R., Trainer, M., Thompson, A. M., Witte, J. C., Oltmans, S. J., Morris, G., Pickering, K. E., Crawford, J. H., Chen, G., Cohen, R. C., Bertram, T. H., Wooldridge, P., Perring, A., Brune, W. H., Merrill, J., Moody, J. L., Tarasick, D., Nédélec, P., Forbes, G., Newchurch, M. J., Schmidlin, F. J., Johnson, B. J., Turquety, S., Baughcum, S. L., Ren, X., Fehsenfeld, F. C., Meagher, J. F., Spichtinger, N., Brown, C. C., McKeen, S. A., McDermid, I. S., and Leblanc, T.: Large upper tropospheric ozone enhancements above midlatitude North America during summer: In situ evidence from the IONS and MOZAIC ozone measurement network, J. Geophys. Res., 111, D24S05, <a href="http://dx.doi.org/10.1029/2006JD007306">https://doi.org/10.1029/2006JD007306</a>, 2006.

Cooper, O. R., Trainer, M., Thompson, A. M., Oltmans, S. J., Tarasick, D., Witte, J. C., Stohl, A., Eckhardt, S., Lelieveld, J., Newchurch, M. J., Johnson, B. J., Portmann, R. W., Kalnajs, L., Dubey, M. K., Leblanc, T., McDermid, I. S., Forbes, G., Wolfe, D., Carey-Smith, T., Morris, G. A., Lefer, B., Rappenglück, B., Joseph, E., Schmidlin, F. J., Meagher, J. F., Fehsenfeld, F. C., Keating, T. J., Van Curen, R. A., and Minschwaner, K.: Evidence for a recurring eastern North America upper tropospheric ozone maximum during summer, J. Geophys. Res., 112, D23304, <a href="http://dx.doi.org/10.1029/2007JD008710">https://doi.org/10.1029/2007JD008710</a>, 2007.

Cooper, O. R., Eckhardt, S., Crawford, J. H., Brown, C. C., Cohen, R. C., Bertram, T. H., Wooldridge, P., Perring, A., Brune, W. H., Ren, X., Brunner, D., and Baughcum, S. L.: Summertime buildup and decay of lightning NOx and aged thunderstorm outflow above North America, J. Geophys. Res., 114, D01101, <a href="http://dx.doi.org/10.1029/2008JD010293">https://doi.org/10.1029/2008JD010293</a>, 2009.

DeCaria, A. J., Pickering, K. E., Stenchikov, G. L., and Ott, L. E.: Lightning-generated NOx and its impact on tropospheric ozone production: A three-dimensional modeling study of a Stratosphere-Troposphere Experiment: Radiation, Aerosols and Ozone (STERAO-A) thunderstorm, J. Geophys. Res., 110, D14303, <a href="http://dx.doi.org/10.1029/2004JD005556">https://doi.org/10.1029/2004JD005556</a>, 2005.

Dickerson, R. R., Huffman, G. J., Luke, W. T., Nunnermacker, L. J., Pickering, K. E., Leslie, A. C. D., Lindsey, C. G., Slinn, W. G. N., Kelly, T. J., Daum, P. H., Delany, A. C., Greenberg, J. P., Zimmerman, P. R., Boatman, J. F., Ray, J. D., and Stedman, D. H.: Thunderstorms: An important mechanism in the transport of air pollutants, Science, 235, 460–465, 1987.

Easter R. C., Ghan, S. J., Zhang, Y., Saylor, R. D., Chapman, E. G., Laulainen, N. S., Abdul-Razzak, H., Leung, L. R., Bian, X., and Zaveri, R. A.: MIRAGE: Model description and evaluation of aerosols and trace gases, J. Geophys. Res., 109, D20210, <a href="http://dx.doi.org/10.1029/2004JD004571">https://doi.org/10.1029/2004JD004571</a>, 2004.

Emmons, L. K., Hess, P. G., Lamarque, J.-F., and Pfister, G. G.: Tagged ozone mechanism for MOZART-4, CAM-chem, and other chemical transport models, Geosci. Model Dev. Discuss., 5, 1949–1985, <a href="http://dx.doi.org/10.5194/gmdd-5-1949-2012">https://doi.org/10.5194/gmdd-5-1949-2012</a>, 2012.

Fast J. D., Gustafson Jr., W. I., Easter, R. C., Zaveri, R. A., Barnard, J. C., Chapman, E. G., and Grell, G. A.: Evolution of ozone, particulates, and aerosol direct forcing in an urban area using a new fully-coupled meteorology, chemistry, and aerosol model, J. Geophys. Res., 111, D21305, <a href="http://dx.doi.org/10.1029/2005JD006721">https://doi.org/10.1029/2005JD006721</a>, 2006.

Fast, J., Aiken, A. C., Allan, J., Alexander, L., Campos, T., Canagaratna, M. R., Chapman, E., DeCarlo, P. F., de Foy, B., Gaffney, J., de Gouw, J., Doran, J. C., Emmons, L., Hodzic, A., Herndon, S. C., Huey, G., Jayne, J. T., Jimenez, J. L., Kleinman, L., Kuster, W., Marley, N., Russell, L., Ochoa, C., Onasch, T. B., Pekour, M., Song, C., Ulbrich, I. M., Warneke, C., Welsh-Bon, D., Wiedinmyer, C., Worsnop, D. R., Yu, X.-Y., and Zaveri, R.: Evaluating simulated primary anthropogenic and biomass burning organic aerosols during MILAGRO: implications for assessing treatments of secondary organic aerosols, Atmos. Chem. Phys., 9, 6191–6215, <a href="http://dx.doi.org/10.5194/acp-9-6191-2009">https://doi.org/10.5194/acp-9-6191-2009</a>, 2009.

Freitas, S. R., Longo, K. M., Diasb, M. A. F. S., Diasb, P. L. S., Chatfield, R., Prins, E., Artaxo, P., Grell, G. A., and Recuero, F. S.: Monitoring the transport of biomass burning emissions in South America, Environ. Fluid Mech., 5, 135–167, <a href="http://dx.doi.org/10.1007/s10652-005-0243-7">https://doi.org/10.1007/s10652-005-0243-7</a>, 2005.

Freitas, S. R., Longo, K. M., Alonso, M. F., Pirre, M., Marecal, V., Grell, G., Stockler, R., Mello, R. F., and Sánchez Gácita, M.: PREP-CHEM-SRC – 1.0: a preprocessor of trace gas and aerosol emission fields for regional and global atmospheric chemistry models, Geosci. Model Dev., 4, 419–433, <a href="http://dx.doi.org/10.5194/gmd-4-419-2011">https://doi.org/10.5194/gmd-4-419-2011</a>, 2011.

Grell, G. A. and Devenyi, D.: A generalized approach to parameterizing convection combining ensemble and data assimilation techniques, Geophys. Res. Lett., 29, 1693, <a href="http://dx.doi.org/10.1029/2002GL015311">https://doi.org/10.1029/2002GL015311</a>, 2002.

Grell G. A., Peckham, S. E., Schmitz, R., McKeen, S. A., Frost, G., Skamarock, W. C., and Eder, B.: Fully coupled "online" chemistry in the WRF model, Atmos. Environ., 39, 6957–6976, 2005.

Guenther, A., Karl, T., Harley, P., Wiedinmyer, C., Palmer, P. I., and Geron, C.: Estimates of global terrestrial isoprene emissions using MEGAN (Model of Emissions of Gases and Aerosols from Nature), Atmos. Chem. Phys., 6, 3181–3210, <a href="http://dx.doi.org/10.5194/acp-6-3181-2006">https://doi.org/10.5194/acp-6-3181-2006</a>, 2006.

Hodzic, A., Jimenez, J. L., Madronich, S., Canagaratna, M. R., DeCarlo, P. F., Kleinman, L., and Fast, J.: Modeling organic aerosols in a megacity: potential contribution of semi-volatile and intermediate volatility primary organic compounds to secondary organic aerosol formation, Atmos. Chem. Phys., 10, 5491–5514, <a href="http://dx.doi.org/10.5194/acp-10-5491-2010">https://doi.org/10.5194/acp-10-5491-2010</a>, 2010.

Janjic, Z. I.: Nonsingular implementation of the Mellor-Yamada Level 2.5 scheme in the NCEP meso model, NCEP Office Note, No. 437, 61 pp., 2002.

Jourdain, L., Kulawik, S. S., Worden, H. M., Pickering, K. E., Worden, J., and Thompson, A. M.: Lightning NOx emissions over the USA constrained by TES ozone observations and the GEOS-Chem model, Atmos. Chem. Phys., 10, 107–119, <a href="http://dx.doi.org/10.5194/acp-10-107-2010">https://doi.org/10.5194/acp-10-107-2010</a>, 2010.

Lamarque, J.-F., Emmons, L. K., Hess, P. G., Kinnison, D. E., Tilmes, S., Vitt, F., Heald, C. L., Holland, E. A., Lauritzen, P. H., Neu, J., Orlando, J. J., Rasch, P. J., and Tyndall, G. K.: CAM-chem: description and evaluation of interactive atmospheric chemistry in the Community Earth System Model, Geosci. Model Dev., 5, 369–411, <a href="http://dx.doi.org/10.5194/gmd-5-369-2012">https://doi.org/10.5194/gmd-5-369-2012</a>, 2012.

Lawrence, M. G., von Kuhlmann, R., Salzmann, M., and Rasch, P. J.: The balance of effects of deep convective mixing on tropospheric ozone, Geophys. Res. Lett., 30, 1940, <a href="http://dx.doi.org/10.1029/2003GL017644">https://doi.org/10.1029/2003GL017644</a>, 2003.

Lelieveld, J. and Crutzen, P. J.: Role of deep cloud convection in the ozone budget of the troposphere, Science, 264, 1759–1761, 1994.

Li, Q., Jacob, D. J., Park, R., Wang, Y., Heald, C. L., Hudman, R., Yantosca, R. M., Martin, R. V., and Evans, M.: North American pollution outflow and the trapping of convectively lifted pollution by upper-level anticyclone, J. Geophys. Res., 110, D10301, <a href="http://dx.doi.org/10.1029/2004JD005039">https://doi.org/10.1029/2004JD005039</a>, 2005.

Lin, Y.-L., Farley, R. D., and Orville, H. D.: Bulk parameterization of the snow field in a cloud model, J. Clim. Appl. Meteorol., 22, 1065–1092, 1983.

Marenco, A., Thouret, V., Nedelec, P., Smit, H., Helten, M., Kley, D., Karcher, F., Simon, P., Law, K., Pyle, J., Poschmann, G., Von Wrede, R., Hume, C., and Cook, T.: Measurement of ozone and water vapor by Airbus in-service aircraft: The MOZAIC airborne program, An overview, J. Geophys. Res., 103, 25631–25642, <a href="http://dx.doi.org/10.1029/98JD00977">https://doi.org/10.1029/98JD00977</a>, 1998.

Mlawer, E. J., Taubman, S. J., Brown, P. D., Iacono, M. J., and Clough, S. A.: Radiative transfer for inhomogeneous atmosphere: RRTM, a validated correlated-k model for the long- wave, J. Geophys. Res., 102, 16663–16682, 1997.

Mortlock, A. and Alstyne, R. V.: Military, Charter, Unreported Domestic Traffic and General Aviation: 1976, 1984, 1992, and 2015 Emission Scenarios, NASA CR-1998-207639, available at: <a href="http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980047346 1998120131.pdf">http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980047346 1998120131.pdf</a> (last access: August 2007), 1998.

Park, R. J., Pickering, K. E., Allen, D. J., Stenchikov, G. L., and Fox-Rabinovitz, M. S.: Global simulation of tropospheric ozone using the University of Maryland Chemical Transport Model (UMD-CTM): 2. Regional transport and chemistry over the central United States using a stretched grid, J. Geophys. Res., 109, D09303, <a href="http://dx.doi.org/10.1029/2003JD004269">https://doi.org/10.1029/2003JD004269</a>, 2004.

Price, C. and Rind, D.: A Simple Lightning Parameterization for Calculating Global Lightning Distributions, J. Geophys. Res., 97, 9919–9933, <a href="http://dx.doi.org/10.1029/92JD00719">https://doi.org/10.1029/92JD00719</a>, 1992.

Roelofs, G.-J. and Lelieveld, J.: Model study of the influence of cross- tropopause O3 transports on tropospheric O3 levels, Tellus B, 49, 38–55, 1997.

Sandu, A. and Sander, R.: Technical note: Simulating chemical systems in Fortran90 and Matlab with the Kinetic PreProcessor KPP-2.1, Atmos. Chem. Phys., 6, 187–195, <a href="http://dx.doi.org/10.5194/acp-6-187-2006">https://doi.org/10.5194/acp-6-187-2006</a>, 2006.

Saxena, P., Hudeschewskyj, A. B., Seigneur, C., and Seinfeld, J. H.: A comparative study of equilibrium approaches to the chemical characterization of secondary aerosols, Atmos. Environ., 20, 1471–1483, 1986.

Seifert, A. and Weisman, M.: A comparison of bulk microphysical schemes for cloud resolving numerical weather prediction, WRF Users' Workshop, <a href="http://www.mmm.ucar.edu/wrf/users/workshops/WS2005/abstracts/Session6/2-Seifert.pdf">http://www.mmm.ucar.edu/wrf/users/workshops/WS2005/abstracts/Session6/2-Seifert.pdf</a>, 2005.

Shaw, W., Allwine, K. J., Fritz, B. G., Rutz, F. C., Rishel, J. P., and Chapman, E. G.: An evaluation of the wind erosion module in DUSTRAN, Atmos. Environ., 42, 1907–1921, 2008.

Snow, J. A., Heikes, B. G., Shen, H., O'Sullivan, D. W., Fried, A., and Walega, J.: Hydrogen peroxide, methyl hydroperoxide, and formaldehyde over North America and the North Atlantic, J. Geophys. Res., 112, D12S07, <a href="http://dx.doi.org/10.1029/2006JD007746">https://doi.org/10.1029/2006JD007746</a>, 2007.

Skamarock, W. C., Klemp, J. B., Dudhia, J., Gill, D. O., Barker, D. M., Duda, M. G., Huang, X.-Y., Wang, W., and Powers, J. G: A description of the advanced research WRF version 3, NCAR Technical Note, NCAR/TN-475+STR, 125 pp., 2008.

Stephens, S., Madronich, S., Wu, F., Olson, J. B., Ramos, R., Retama, A., and Muñoz, R.: Weekly patterns of México City's surface concentrations of CO, NOx, PM10 and O3 during 1986–2007, Atmos. Chem. Phys., 8, 5313–5325, <a href="http://dx.doi.org/10.5194/acp-8-5313-2008">https://doi.org/10.5194/acp-8-5313-2008</a>, 2008.

Stockwell, W. R., Kirchner, F., Kuhn, M., and Seefeld, S.: A new mechanism for regional atmospheric chemistry modeling, J. Geophys. Res., 102, 25847–25879, 1997.

Sutkus, D., Baughcum, S., and DuBois, D.: Scheduled Civil Aircraft Emission Inventories for 1999: Database Development and Analysis, NASA/CR-2001-211216, available at: <a href="http://hdl.handle.net/2060/20020012699">http://hdl.handle.net/2060/20020012699</a> (last access: August 2007), 2001.

Thompson, A. M., Yorks, J. E., Miller, S. K., Witte, J. C., Dougherty, K. M., Morris, G. A., Baumgardner, D., Ladino, L., and Rappenglück, B.: Tropospheric ozone sources and wave activity over Mexico City and Houston during MILAGRO/Intercontinental Transport Experiment (INTEX-B) Ozonesonde Network Study, 2006 (IONS-06), Atmos. Chem. Phys., 8, 5113–5125, <a href="http://dx.doi.org/10.5194/acp-8-5113-2008">https://doi.org/10.5194/acp-8-5113-2008</a>,

Tie, X., Madronich, S., Walters, S., Zhang, R., Rasch, P., and Collins, W.: Effect of clouds on photolysis and oxidants in the troposphere, J. Geophys. Res., 108, 4642, <a href="http://dx.doi.org/10.1029/2003JD003659">https://doi.org/10.1029/2003JD003659</a>, 2003.

Wang, H., Skamarock, W. C., and Feingold, G.: Evaluation of scalar advection schemes in the advanced research WRF model using large-eddy simulations of aerosol-cloud interaction, Mon. Weather Rev., 137, 2547–2558, <a href="http://dx.doi.org/10.1175/2009MWR2820.1">https://doi.org/10.1175/2009MWR2820.1</a>, 2009.

Wang, Y., Jacob, D. J., and Logan, J. A.: Global simulation of tropospheric O3-NOx-hydrocarbon chemistry, 3, Origin of tropospheric ozone and effects of nonmethane hydrocarbons, J. Geophys. Res., 103, 10757–10767, 1998.

Wesely, M.: Parameterization of surface resistances to gaseous dry deposition in regional-scale numerical models, Atmos. Environ., 23, 1293–1304, 1989.

Wiedinmyer, C., Quayle, B. Geron, C. Belote, A. McKenzie, D. Zhang, X., O'Neill, S., and Klos Wynne, K.: Estimating emissions from fires in North America for air quality modeling, Atmos. Environ., 40, 3419–3432, 2006.

Wong, J., Barth, M. C., and Noone, D.: Evaluating a lightning parameterization based on cloud-top height for mesoscale numerical model simulations, Geosci. Model Dev. Discuss., 5, 3493–3531, https://doi.org/10.5194/gmdd-5-3493-2012, 2012.

Worden J. R., Bowman, K. W., and Jones, D. B.: Two-dimensional characterization of atmospheric profile retrievals from limb sounding observations, J. Quant. Spectrosc. Ra., 86, 45–71, 2004.

Zhang, R. Y., Tie, X. X., and Bond, D. W.: Impacts of anthropogenic and natural NOx sources over the US on tropospheric chemistry, P. Natl. Acad. Sci. USA, 100, 1505–1509, <a href="http://dx.doi.org/10.1073/pnas.252763799">https://doi.org/10.1073/pnas.252763799</a>, 2003.

Zhao, C., Wang, Y., Choi, Y., and Zeng, T.: Summertime impact of convective transport and lightning NOx production over North America: modeling dependence on meteorological simulations, Atmos. Chem. Phys., 9, 4315–4327, <a href="http://dx.doi.org/10.5194/acp-9-4315-2009">https://doi.org/10.5194/acp-9-4315-2009</a>, 2009.