Aerosol modelling and validation during ESCOMPTE 2001

Abstract

The ESCOMPTE 2001 programme (Atmospheric Research. 69(3-4) ( 2004) 241) has resulted in an exhaustive set of dynamical, radiative, gas and aerosol observations (surface and aircraft measurements). A previous paper (Atmospheric Research. (2004) in press) has dealt with dynamics and gas-phase chemistry. The present paper is an extension to aerosol formation, transport and evolution. To account for important loadings of primary and secondary aerosols and their transformation processes in the ESCOMPTE domain, the ORISAM aerosol module (Atmospheric Environment. 35 ( 2001) 4751) was implemented on-line in the air-quality M eso-NH-C model. Additional developments have been introduced in ORganic and Inorganic Spectral Aerosol M odule (ORISAM ) to improve the comparison between simulations and experimental surface and aircraft field data. This paper discusses this comparison for a simulation performed during one selected day, 24 June 2001, during the Intensive Observation Period IOP2b. Our work relies on BC and OCp emission inventories specifically developed for ESCOM PTE. This study confirms the need for a fine resolution aerosol inventory with spectral chemical speciation. BC levels are satisfactorily reproduced, thus validating our emission inventory and its processing through M eso-NH-C. However, comparisons for reactive species generally denote an underestimation of concentrations. Organic aerosol levels are rather well simulated though with a trend to underestimation in the afternoon. Inorganic aerosol species are underestimated for several reasons, some of them have been identified. For sulphates, primary emissions were introduced. Improvement was obtained too for modelled nitrate and ammonium levels after introducing heterogeneous chemistry. However, no modelling of terrigeneous particles is probably a major cause for nitrates and ammonium underestimations. Particle numbers and size distributions are well reproduced, but only in the submicrometer range. Our work points out to the need of introducing coarse dust particles to further improve the simulation of PM-10 concentrations and more accurate modelling of gas-particle interactions.

Aerosol chemical and optical properties over the Paris area within ESQUIF project

“…Differences between observed and simulated concentrations are obviously due to the absence of a coarse nitrate net formation processes in the model. The coarse-mode nitrate has been observed several times during measurement campaigns as reported by Putaud et al (2004); Cousin et al (2005) over the Mediterranean area during the ESCOMPTE and MINATROC projects, or at an alpine-site (Henning et al, 2003).…”

“…The most likely reason is that the homogeneous sulfate production which prevails during dry anticyclonic conditions is too slow in the model. Moreover, an additional reason for the model negative bias could also be the absence of the primary sulfate emissions (Cousin et al, 2005 and references in there). Indeed, to account for a sub-grid formation of sulfates in industrial and car exhaust plumes it should be assumed that a small fraction (2%, Tan et al, 2003) of total SO 2 emissions are directly emitted as sulfate.…”

“…Several intensive field observations that inter-relate the chemical, physical and optical properties of aerosols have been carried out in urban areas (e.g., Hering et al, 1997;Han et al, 2002;Baertsch-Ritter et al, 2003;Cousin et al, 2005). However, the results of simultaneous model evaluations for these aerosol properties have rarely been reported, especially over a large urban area such as Paris city.…”

Updated African biomass burning emission inventories in the framework of the AMMA-IDAF program, with an evaluation of combustion aerosols

“…The first mode has a mass diameter of 0.23 µm while the second mode (only including 20% of OC emissions) has a mass diameter of 2.5 µm (Cousin et al, 2005). BC and OC emissions are partitioned into hydrophobic and hydrophilic fractions.…”

A global emission inventory of carbonaceous aerosol from historic records of fossil fuel and biofuel consumption for the period 1860–1997

“…The inventory presented here can incorporate easily new information concerning fuel usage as it becomes available by making changes to the average EF per country and sector. The results are tested for consistency with ambient measurements using a variety of dispersion models such as MesoNH (Cousin et al, 2005), RegCM (Solmon et al, 2006) and ORISAM-TM4 (Guillaume et al, 2007).…”