ACP Atmospheric Chemistry and Physics ACP Atmos. Chem. Phys. 1680-7324 Copernicus Publications Göttingen, Germany 10.5194/acp-9-9187-2009 On the distribution of formaldehyde in the western Po-Valley, Italy, during FORMAT 2002/2003 Junkermann W. 1 Karlsruhe Institut of Technology, Institute for Meteorology and Climate Research, IMK-IFU, Kreuzeckbahnstr. 19, 82467 Garmisch-Partenkirchen, Germany 07 12 2009 9 23 9187 9196 Copyright: © 2009 W. Junkermann 2009 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/9/9187/2009/acp-9-9187-2009.html The full text article is available as a PDF file from https://acp.copernicus.org/articles/9/9187/2009/acp-9-9187-2009.pdf

Formaldehyde was measured in the area of Milano, Italy, during the 2002 and 2003 FORMAT campaigns at three ground field sites and from an ultralight aircraft. The horizontal distributions show a strong impact of local emissions at a site in the centre of Milano and more photochemically driven diurnal patterns in the remote locations north and south of the city. The mixing ratios in the agricultural areas upwind of Milano were comparable to those downwind indicating the importance of biogenic emissions and anthropogenic agricultural activities. The vertical distributions were dominated by transport processes with advection of CH<sub>2</sub>O above the planetary boundary layer by cloud venting. Comparison to previously published model calculations, based on part of the data set, show discrepancies both, in the diurnal patterns and in the regional distribution which allude to uncertainties in emission inventories.

 References Environ International Corporation: Environ User's Guide: Comprehensive Air Quality Model With Extensions (CAMx), version 4.10, Novato, CA, <a href="www.camx.com">www.camx.com</a>, 2004. Eom, I.-Y., Li, Q., and Dasgupta, P.: Robust hybrid flow analyzer for formaldehyde, Env. Sci. Technol., 42, 1221–1226, 2008. Fuentes, J. D., Wang, D., Bowling, D. R., Potosnak, M., Monson, R. K., Goliff, W. S., and Stockwell, W. R.: Biogenic Hydrocarbon Chemistry within and Above a Mixed Deciduous Forest, J. Atmos. Chem., 56, 165–185, 2007. Garcia, A. R., Volkamer, R., Molina, L. T., Molina, M. J., Samuelson, J., Mellqvist, J., Galle, B., Herndon S. C., and Kolb, C. E.: Separation of emitted and photochemical formaldehyde in Mexico City using a statistical analysis and a new pair of gas-phase tracers, Atmos. Chem. Phys., 6, 4545–4557, 2006. de Gouw, J. A., Welsh-Bon, D., Warneke, C., Kuster, W. C., Alexander, L., Baker, A. K., Beyersdorf, A. J., Blake, D. R., Canagaratna, M., Celada, A. T., Huey, L. G., Junkermann, W., Onasch, T. B., Salcido, A., Sjostedt, S. J., Sullivan, A. P., Tanner, D. J., Vargas, O., Weber, R. J., Worsnop, D. R., Yu, X. Y., and Zaveri, R.: Emission and chemistry of organic carbon in the gas and aerosol phase at a sub-urban site near Mexico City in March 2006 during the MILAGRO study, Atmos. Chem. Phys., 9, 3425–3442, 2009. Hak, C., Pundt, I., Trick, S., Kern, C., Platt, U., Dommen, J., Ordóñez, C., Prévôt, A. S. H., Junkermann, W., Astorga-Lloréns, C., Larsen, B., Mellqvist, J., Strandberg, A., Yu, Y., Galle, B., Kleffmann, J., Lörzer, J. C., Braathen, G. O., and Volkamer, R., Intercomparison of four different in-situ techniques for ambient formaldehyde measurements in urban air, Atmos. Chem. Phys., 5, 2881–2900, 2005. Heckel, A., Richter, A., Tarsu, T., Wittrock, F., Hak, C., Pundt, I., Junkermann, W., and Burrows, J. P., MAX-DOAS measurements of formaldehyde in the Po-Valley, Atmos. Chem. Phys., 5, 909–918, 2005. Junkermann, W.: An ultralight aircraft as platform for research in the lower troposphere: system performance and first results from radiation transfer studies in stratiform aerosol layers and broken cloud conditions, J. Ocean.& Atm. Techn., 18, 934–946, 2001. Junkermann, W. and Stockwell, W. R.: On the budget of photooxidants in the marine boundary layer of the tropical South Atlantic, J. Geophys. Res., 104, 8039–8046, 1999. Junkermann, W. and Burger, J. M.: A new portable instrument for continuous measurement of formaldehyde in ambient air, J. Atmos. Ocean. Technol., 23, 38–45, 2006. Junkermann, W., Hacker, J. M. H., Lyons, T., and Nair, U.: Land use change suppresses precipitation, Atmos. Chem. Phys.,&nbsp;9,&nbsp;6531–6539,&nbsp;2009. Kormann, R., Fischer, H., de Reus, M., Lawrence, M., Brühl, C., von Kuhlmann, R. Holzinger, R., Williams, J., Lelieveld, J., Warneke, C., de Gouw, J., Heland, J., Ziereis, H., and Schlager, H.: Formaldehyde over the eastern Mediterranean during MINOS: Comparison of airborne in-situ measurements with 3D-model results, Atmos. Chem. Phys., 3, 851–861, 2003. Lei, W., Zavala, M., deFoy, B., Volkamer, R., Molina, M. J., and Molina, L. T.: Impact of primary formaldehyde on air pollution in the Mexico City Metropolitan Area, Atmos. Chem. Phys., 9, 2607–2618, 2009. Lelieveld, J. and Crutzen, P. J.: Influences of cloud photochemical processes on tropospheric ozone, Nature, 343, 227–233, https://doi.org/10.1038/343227a0, 1990. Lin, C.-Y., Chen, F., Huang, J. C., Chen, W. C., Liou, Y. A., Chen, W. N., and Liu, S. C.: Urban heat island effect and its impact on boundary layer development and land–sea circulation over northern Taiwan, Atmos. Environ., 42, 5635–5649, 2008. Liu, L.,Andreani-Aksoyoglu, S., Keller, J., Ordóñez, C., Junkermann, W., Hak, C., Braathen, G. O., Reimann, S., Astorga-llorens, C., Schultz, M., Prévôt, A. S. H. and Isaksen, I. S. A., A photochemical modelling study of ozone and formaldehyde generation and budget in the Po basin, J. Geophys. Res., VOL. 112, D22303, https://doi.org/10.1029/2006JD008172, 2007a. Liu, L., Flatøy, F., Ordóñez, C., Braathen, G. O., Hak, C., Junkermann, W., Andreani-Aksoyoglu, S., Mellqvist, J., Galle, B., Prévôt, A. S. H., and Isaksen, I. S. A.: Photochemical modelling in the Po basin with focus on formaldehyde and ozone, Atmos. Chem. Phys., 7, 121–137, 2007b. Neftel, A., Spirig, C., Prévôt, A. S. H., Furger, M., Stutz, J., Vogel, B., and Hjorth, J.: Sensitivity of photooxidant production in the Milan Basin: An overview of results from a EUROTRAC-2 Limitation of Oxidant Production field experiment, J. Geophys. Res., 107(D22), 8188, https://doi.org/10.1029/2001JD001263, 2002. Possanzini, M., Di Palo, V., and Ceccinato, A.: Sources and photodecomposition of formaldehyde and acetaldehyde in Rome ambient air, Atmos. Environ., 36, 3195–3201, 2002 Rao, X. and Collett, J. L.: Environ. Sci. Technol., 29, 1023–1031, https://doi.org/10.1021/es00004a024, 1995. Slemr, J., Junkermann, W., and Volz-Thomas, A.: Temporal variations of Tropospheric CH<sub>2</sub>O at a Rural site in Southern Germany, Atmos. Environ., 30, 3667–3676, 1996. Steinbacher, M., Dommen, J., Ordonez, C., Reimann, S., Grübler, F. C., Staehelin, J., and Prevot, A. S. H.: Volatile Organic Compounds in the Po Basin. Part A: Anthropogenic VOCs, J. Atmos. Chem., 51, 271–291, https://doi.org/10.1007/s10874-005-3576-1, 2005a. Steinbacher, M., Dommen, J., Ordonez, C., Reimann, S., Grübler, F. C., Staehelin, J., Andreani-Aksoyoglu, S., and Prevot, A. S. H.: Volatile Organic Compounds in the Po Basin. Part B: Biogenic VOCs, J. Atmos. Chem., 51, 293–315, https://doi.org/10.1007/s10874-005-3577-0, 2005b. Wang, P., Richter, A., Bruns, W., Burrows, J. P., Heue, K.-P., Wagner, T., Platt, U., Pundt, I., and Junkermann, W.: Airborne multi-axis DOAS measurements of tropospheric SO<sub>2</sub> plumes in the Po-valley, Italy, Atmos. Chem. Phys., 5, 2017–2045, 2005. Weissmann, M., Braun, F. J., Gantner, L., Mayr, G. J., Rahm, S., and Reitebuch, O.: The Alpine Mountain–Plain Circulation: Airborne Doppler Lidar Measurements and Numerical Simulations, Mon. Weather Rev., 133, 3095–3109, 2005. Wiegner, M., Emeis, S., Freudenthaler, V., Heese, B., Junkermann, W., Münkel, C., Schäfer, K., Seefeldner, M., and Vogt, S.: Mixing layer height over Munich, Germany: Variability and comparisons of different methodologies, J. Geophys. Res., 111, D13201, https://doi.org/10.1029/2005JD006593, 2006. Wisthaler, A., Apel, E. C., Bossmeyer, J., Hansel, A., Junkermann, W., Koppmann, R., Meier, R., Müller, K., Solomon, S. J., Steinbrecher, R., Tillmann, R., and Brauers, T.: Technical Note: Intercomparison of formaldehyde measurements at the atmosphere simulation chamber SAPHIR, Atmos. Chem. Phys., 8, 2189–2200, 2008.