Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 2 5 2002 10.5194/acpd-2-1545-2002 http://www.atmos-chem-phys-discuss.net/2/1545/2002/ http://www.atmos-chem-phys-discuss.net/2/1545/2002/acpd-2-1545-2002.html http://www.atmos-chem-phys-discuss.net/2/1545/2002/acpd-2-1545-2002.pdf 1545 1597 2002-10-15 Global chemical weather forecasts for field campaign planning: predictions and observations of large-scale features during MINOS, CONTRACE, and INDOEX M. G. Lawrence P. J. Rasch R. von Kuhlmann J. Williams H. Fischer M. de Reus J. Lelieveld P. J. Crutzen M. Schultz P. Stier H. Huntrieser J. Heland A. Stohl C. Forster H. Elbern H. Jakobs R. R. Dickerson Max-Planck-Institut für Chemie, Postfach 3060, 55020 Mainz, Germany National Center for Atmospheric Research, Boulder, Colorado, USA Max-Planck-Institut für Meteorologie, Hamburg, Germany Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, Germany Technische Universität München, München, Germany Institut für Geophysik und Meteorologie, Universität zu Köln, Köln, Germany Department of Meteorology, University of Maryland, College Park, Maryland, USA The first global tropospheric forecasts of O<sub>3</sub> and its precursors have been used in the daily flight planning of field measurement campaigns. The 3-D chemistry-transport model MATCH-MPIC is driven by meteorological data from a weather center (NCEP) to produce daily 3-day forecasts of the global distributions of O<sub>3</sub> and related gases, as well as regional CO tracers. This paper describes the forecast system and its use in three field campaigns, MINOS, CONTRACE and INDOEX. An overview is given of the forecasts by MATCH-MPIC and by three other chemical weather forecast models (EURAD, ECHAM, and FLEXPART), focusing on O<sub>3</sub> and CO. Total CO and regional CO tracers were found to be the most valuable gases for flight planning, due to their relatively well-defined anthropogenic source regions and lifetimes of one to a few months. CO was in good agreement with the observations on nearly all the flights (generally&nbsp; r &gt; 0.7, RMS&nbsp; &lt; 20%). In every case in which the chemical weather forecasts were primarily responsible for the flight plans, the targeted features were observed. Two forecasted phenomena are discussed in detail: outflow from Asia observed in the Mediterranean upper troposphere during MINOS, and outflow from North America observed in the middle troposphere over northern Europe during CONTRACE. It is shown that although such pollution plumes occur repeatedly during the months around the campaigns, their frequency is sufficiently low (~10--30% of the time) that global chemical weather forecasts are important for enabling them to be observed during limited-duration field campaigns. The MATCH-MPIC chemical weather forecasts, including an interface for making customized figures from the output, are available for community use via&nbsp; <a href="http://www.mpch-mainz.mpg.de/~lawrence/forecasts.html">http://www.mpch-mainz.mpg.de/~lawrence/forecasts.html</a> .