Evaluation of the MOCAGE chemistry transport model during the ICARTT/ITOP experiment

Abstract

[1] Intercontinental Transport of Ozone and Precursors (ITOP), part of International Consortium for Atmospheric Research on Transport and Transformation (ICARTT), was a large experimental campaign designed to improve our understanding of the chemical transformations within plumes during long-range transport (LRT) of pollution from North America to Europe. This campaign took place in July and August 2004, when a strong fire season occurred in North America. Burning by-products were transported over large distances, sometimes reaching Europe. A chemical transport model, Modélisation de la Chimie Atmosphérique Grande Echelle (MOCAGE), with a high grid resolution (0.5°Â 0.5°) over the North Atlantic area and a daily inventory of biomass burning emissions over the United States, has been used to simulate the period. By comparing our results with available aircraft in situ measurements and satellite data (MOPITT CO and SCIAMACHY NO 2 ), we show that MOCAGE is capable of representing the main characteristics of the tropospheric ozone-NO x -hydrocarbon chemistry during the ITOP experiment. In particular, high resolution allows the accurate representation of the pathway of exported pollution over the Atlantic, where plumes were transported preferentially at 6 km altitude. The model overestimates OH mixing ratios up to a factor of 2 in the lower troposphere, which results in a global overestimation of hydrocarbons oxidation by-products (PAN and ketones) and an excess of O 3 (30-50 ppbv) in the planetary boundary layer (PBL) over the continental United States. Sensitivity study revealed that lightning NO emissions contributed significantly to the NO x budget in the upper troposphere of northeast America during the summer 2004.

Comparison of OMI NO<sub>2</sub> tropospheric columns with an ensemble of global and European regional air quality models

“…This coupled system delivers daily forecasts for reactive trace gases. The models MOCAGE (Josse et al, 2004;Bousserez et al, 2007) and TM5 (Krol et al, 2005) have been running in an offline mode and in experimental phase in a forecast mode coupled to IFS.…”

Importance of using ensemble estimated background error covariances for the quality of atmospheric ozone analyses

“…Using its nested domains, it routinely provides the Météo-France operational chemical weather forecasts (Dufour et al, 2004). In its global version, it has been recently validated using a large number of measurements during the Intercontinental Transport of Ozone and Precursors (ICARTT/ITOP) campaign (Bousserez et al, 2007). Its climate version has also been validated over several years by Teyssèdre et al (2007).…”

Validity of satellite measurements used for the monitoring of UV radiation risk on health

“…Surface processes (emissions, dry deposition), turbulent and convective transport, as well as scavenging are explicitly described in the model. See (Bousserez et al, 2007) for more general information on the MOCAGE CTM.…”

“…MOCAGE has been used in a range of research studies with over 50 papers in the literature, from air quality (Dufour et al, 2004), to the interpretation of field campaigns (Bousserez et al, 2007) and, for instance, the study of chemistry and climate interactions (Teyssèdre et al, 2007). MOCAGE is also used operationally at Météo-France, in particular in the context of the French Air Quality Platform Prév'Air and of the setting-up of Global Monitoring for Environment and Security (GMES) services for atmospheric composition (Hollingsworth et al, 2008).…”