Source contributions to 2012 summertime aerosols in the Euro-Mediterranean region

International audienceIn the Mediterranean area, aerosols may originate from anthropogenic or natural emissions (biogenic, mineral dust, fire and sea salt) before undergoing complex chemistry. In case of a huge pollution event, it is important to know whether European pollution limits are exceeded and, if so, whether the pollution is due to anthropogenic or natural sources. In this study, the relative contribution of emissions to surface PM10, surface PM2.5 and total aerosol optical depth (AOD) is quantified. For Europe and the Mediterranean regions and during the summer of 2012, the WRF and CHIMERE models are used to perform a sensitivity analysis on a 50 km resolution domain (from −10° W to 40° E and from 30° N to 55° N): one simulation with all sources (reference) and all others with one source removed. The reference simulation is compared to data from the AirBase network and two ChArMEx stations, and from the AERONET network and the MODIS satellite instrument, to quantify the ability of the model to reproduce the observations. It is shown that the correlation ranges from 0.19 to 0.57 for surface particulate matter and from 0.35 to 0.75 for AOD. For the summer of 2012, the model shows that the region is mainly influenced by aerosols due to mineral dust and anthropogenic emissions (62 and 19 %, respectively, of total surface PM10 and 17 and 52 % of total surface PM2.5). The western part of the Mediterranean is strongly influenced by mineral dust emissions (86 % for surface PM10 and 44 % for PM2.5), while anthropogenic emissions dominate in the northern Mediterranean basin (up to 75 % for PM2.5). Fire emissions are more sporadic but may represent 20 % of surface PM2.5, on average, during the period near local sources. Sea salt mainly contributes for coastal sites (up to 29 %) and biogenic emissions mainly in central Europe (up to 20 %)

Aerosol forecast over the Mediterranean area during July 2013 (ADRIMED/CHARMEX)

International audienceThe ADRIMED (Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) project was dedicated to study the atmospheric composition during the summer 2013 in the European Mediterranean region. During its campaign experiment part, the WRF (Weather Research and Forecast Model) and CHIMERE models were used in the forecast mode in order to decide whether intensive observation periods should be triggered. Each day, a simulation of 4 days was performed, corresponding to (D-1) to (D+2) forecast leads. The goal of this study was to determine whether the model forecast spread is lower or greater than the model biases compared to observations. It is shown that the differences between observations and the model are always higher than those between the forecasts. Among all forcing types used in the chemistry-transport model, it is shown that the strong bias and other related low forecast scores are mainly due to the forecast accuracy of the wind speed, which is used both for the mineral dust emissions (a threshold process) and for the long-range transport of aerosol: the surface wind speed forecast spread can reach 50%, leading to mineral dust emission forecast spread of up to 30%. These variations are responsible for a moderate forecast spread of the surface PM10 (a few percentage points) and for a large spread (more than 50%) in the mineral dust concentration at higher altitudes, leading to a mean AOD (aerosol optical depth) forecast spread of ±10%

Impact of the New South Wales fires during October 2013 on regional air quality in eastern Australia

International audienceSmoke plumes from fires contain atmospheric pollutants that can be transported to populated areas and effect regional air quality. In this paper, the characteristics and impact of the fire plumes from a major fire event that occurred in October 2013 (17–26) in the New South Wales (NSW) in Australia, near the populated areas of Sydney and Wollongong, are studied. Measurements from the Fourier Transform InfraRed (FTIR) spectrometer located at the University of Wollongong allowed a calculation of specific emission factors (EFs) in terms of grams per kilogram of dry fuel burned: 1640 g kg−1 of carbon dioxide; 107 g kg−1 of carbon monoxide; 7.8 g kg−1 of methane; and 0.16 g kg−1 of nitrous oxide. These EFs have then been used to calculate daily fire emissions for the NSW fire event using the APIFLAME emissions' model, leading to an increase of 54% of CO emitted compared to calculations with EFs from Akagi et al. (2011), widely used in the literature

Ozone and aerosol tropospheric concentrations variability analyzed using the ADRIMED measurements and the WRF and CHIMERE models

International audienceDuring the months of June and July 2013, over the Euro–Mediterranean area, the ADRIMED (Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) project was dedicated to characterize the ozone and aerosol concentrations in the troposphere. It is first shown that this period was not highly polluted compared to previous summers in this region, with a moderate ozone production, no significant vegetation fire events and several precipitation periods scavenging the aerosol. The period is modeled with the WRF (Weather Research and Forecasting) and CHIMERE models, and their ability to quantify the observed pollution transport events is presented. The CHIMERE model simulating all kinds of sources (anthropogenic, biogenic, mineral dust, vegetation fires); the aerosol speciation, not available with the measurements, is presented: during the whole period, the aerosol was mainly constituted by mineral dust, sea salt and sulfates close to the surface and mainly by mineral dust in the troposphere. Compared to the AERONET (Aerosol Robotic Network) size distribution, it is shown that the model underestimates the coarse mode near mineral dust sources and overestimates the fine mode in the Mediterranean area, highlighting the need to improve the model representation of the aerosol size distribution both during emissions, long-range transport and deposition

Measurements of Urban, Marine and Biogenic Air (MUMBA): characterisation of trace gases and aerosol at the urban, marine and biogenic interface in summer in Wollongong, Australia

The Measurements of Urban, Marine and Biogenic Air (MUMBA) campaign took place in Wollongong, New South Wales (a small coastal city approximately 80 km south of Sydney, Australia), from 21st December 2012 to 15th February 2013. Instruments were deployed during MUMBA to measure the gaseous and aerosol composition of the atmosphere with the aim of providing a detailed characterisation of the complex environment of the ocean/forest/urban interface that could be used to test the skill of atmospheric models. Gases measured included ozone, oxides of nitrogen, carbon monoxide, carbon dioxide, methane and many of the most abundant volatile organic compounds. Aerosol characterisation included total particle counts above 3 nm, total cloud condensation nuclei counts; mass concentration of PM2.5, number concentration size distribution, aerosol chemical analyses and elemental analysis. Meteorological measurements and LIDAR measurements were also performed. The campaign captured varied meteorological conditions, including two extreme heat events, providing a potentially valuable test for models of future air quality in a warmer climate. There was also an episode when the site sampled clean marine air for many hours, providing a useful additional measure of background concentrations of these trace gases within this poorly sampled region of the globe. Here we present the observations recorded at the MUMBA site during the campaign, as well as radon and air quality data from nearby sites. These records can be used for testing chemical transport models

Interactions aérosols- rayonnement-climat en région méditerranéenne Impact de l'effet radiatif direct sur le cycle de l'eau

International audienceAn experimental campaign, coupled with three-dimensional modeling, was conducted in the western Mediterranean during the summer of 2013 to study the impact of aerosols on the radiative balance and climate of this region. In situ observations were obtained on the ground, aboard two research aircraft and balloons to characterize the physico-chemical and optical properties of particles and their vertical stratification. This campaign was mainly characterized by moderate events of desert aerosols. During these episodes, strong vertical stratification was observed and the measurements of the optical properties reveal moderate absorbing particles in the visible spectrum. Climate simulations indicate a significant impact of aerosols in particular by changing the surface temperature of the sea, the ocean-atmosphere fluxes and consequently seasonal precipitation.Une grande campagne expérimentale a été réalisée en Méditerranée occidentale pendant l'été 2013 afin d'étudier l'impact des aérosols sur le bilan radiatif et le climat régional. Les observations obtenues dans plusieurs stations de surface, à bord de deux avions de recherche, sous ballons sondes plafonnants et par satellite ont documenté la distribution et les propriétés physicochimiques et optiques des particules. Cette campagne a vu se succéder des transports d'aérosols désertiques d'intensité modérée, absorbant modérément le rayonnement solaire et stratifiés verticalement. Les premières simulations climatiques indiquent un impact significatif des aérosols notamment sur la température de surface de la mer, les flux océan-atmosphère et les précipitations saisonnières

Histone deacetylase inhibitors and genomic instability.

International audienceHistone deacetylase inhibitors (HDACIs) are a promising new class of anticancer drugs. However, their mechanism of action has not been fully elucidated. Most studies have investigated the effect of HDACIs on the regulation of gene transcription. HDAC inhibition also leads to genomic instability by a variety of mechanisms. This phenomenon, which has been largely overlooked, may contribute to the cytotoxic effects of these drugs. Indeed, HDACIs sensitize DNA to exogenous genotoxic damage and induce the generation of reactive oxygen species. Moreover, HDACIs target mitosis resulting in chromosome segregation defects. Here, we review the effects of HDACI treatment on DNA damage and repair, and chromosome segregation control