Aerosol distribution over the western Mediterranean basin during a Tramontane/Mistral event

Salameh, T.; Drobinski, P.; Menut, Laurent; Bessagnet, Bertrand; Flamant, Cyrille; Hodžić, Alma; Vautard, Robert

doi:10.5194/acpd-6-11913-2006

Cited by 3 publications

(2 citation statements)

References 17 publications

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“…Mistral and tramontane are northerly and northwesterly winds blowing in southeast France (Zechetto and De Biaso, 2007), channelled into the Rhone and Aude valleys ( Figure 1). They transport cold continental air over sea (Drobinski et al, 2001Guénard et al, 2005Guénard et al, , 2006Salameh et al, 2007) and induce both intense momentum and heat exchanges at the air-sea interface, and thus ocean mixed layer cooling and mixing (Lebeaupin Brossier and Drobinski, 2009;Small et al, 2012). HPEs often occur during fall when the air-sea thermal contrast is maximal.…”

Section: Introductionmentioning

confidence: 99%

Ocean memory effect on the dynamics of coastal heavy precipitation preceded by a mistral event in the northwestern Mediterranean

Brossier

Drobinski

Béranger

et al. 2012

Quart J Royal Meteoro Soc

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In this study, we examine the possible role of 3D oceanic circulation in 'connecting' a strong mistral windstorm in the northwestern Mediterranean with a heavy precipitating event in southern France in November 1999. These two events are both governed by intense air-sea exchanges and are only separated by a week. From an atmospheric point of view, these two events may be considered as fully uncorrelated and independent.However, using the MORCE regional coupled system with WRF atmospheric model and NEMO-MED12 ocean model, we show that the oceanic cyclonic circulation is a key feature, which can trap strong modifications of the ocean mixed layer over few days. In our specific situation, the mistral (5-9 November 1999) induces a rapid mixed-layer cooling. This cold anomaly is trapped in the cyclonic gyre in the Gulf of Lions and maintained over a week. This directly affects the following heavy precipitating event (12-13 November 1999) with less energy supplied where the cold anomaly is maintained and larger evaporation near the coast. This modulates the rainfall amounts over land, with an increase in the eastern part and a decrease in the western part compared to an uncoupled simulation. These simulations highlight the key role of the general ocean circulation, and especially of the dynamic of the cyclonic gyre in the Gulf of Lions on the ocean memory in the area. The ocean maintains the temperature anomaly over typical periods of a few days, which thus enables some indirect links between two weather systems in which air-sea interactions are significant.

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Section: Introductionmentioning

confidence: 99%

Ocean memory effect on the dynamics of coastal heavy precipitation preceded by a mistral event in the northwestern Mediterranean

Brossier

Drobinski

Béranger

et al. 2012

Quart J Royal Meteoro Soc

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“…However, little has been published on aerosol optical properties in the Western Mediterranean Basin (Mallet et al, 2003;Saha et al, 2008). As evidenced by a number of publications, the WMB undergoes severe pollution episodes affecting not only the coastal sites closest to the emission sources, but also the more elevated rural and remote areas inland due to thermally driven winds (Querol et al, 2007;Pérez et al, 2008a;Pey et al, 2009Pey et al, , 2010Salameh et al, 2006;Pandolfi et al, 2011). These studies were mainly dedicated to the study of the chemical composition and physical properties of the atmospheric aerosols.…”

Section: Introductionmentioning

confidence: 99%

Variability of aerosol optical properties in the Western Mediterranean Basin

et al. 2011

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Abstract. Aerosol light scattering, absorption and particulate matter (PM) concentrations were measured at Montseny, a regional background site in the Western Mediterranean Basin (WMB) which is part of the European Supersite for Atmospheric Aerosol Research (EUSAAR). Off line analyses of 24 h PM filters collected with Hi-Vol instruments were performed for the determination of the main chemical components of PM. Mean scattering and hemispheric backscattering coefficients (@ 635 nm) were 26.6±23.2 Mm −1 and 4.3±2.7 Mm −1 , respectively and the mean aerosol absorption coefficient (@ 637 nm) was 2.8±2.2 Mm −1 . Mean values of Single Scattering Albedo (SSA) andÅngström exponent (å) (calculated from 450 nm to 635 nm) at MSY were 0.90±0.05 and 1.3±0.5 respectively. A clear relationship was observed between the PM 1 /PM 10 and PM 2.5 /PM 10 ratios as a function of the calculatedÅngström exponents. Mass scattering cross sections (MSC) for fine mass and sulfate at 635 nm were 2.8±0.5 m 2 g −1 and 11.8±2.2 m 2 g −1 , respectively, while the mean aerosol absorption cross section (MAC) was 10.4±2.0 m 2 g −1 . The variability in aerosol optical properties in the WMB were largely explained by the origin and ageing of air masses over the measurement site. The MAC values appear dependent of particles aging: similar to the expected absorption cross-section for fresh emissions under Atlantic Advection episodes and higher under aerosol pollution episodes. The analysis of theÅngström exponent as a function of the origin the air masses revealed that polluted winter anticyclonic conditions and summer recirculation scenarios typical of the WMB led to an increase of fine particles in the atmosphere (å = 1.5±0.1) while the aerosol optical properties under Atlantic Advection episodes and Saharan dust outbreaks were clearly dominated by coarser particles (å = 1.0±0.4). The sea breeze played an important role Correspondence to: M. Pandolfi (marco.pandolfi@idaea.csic.es) in transporting pollutants from the developed WMB coastlines towards inland rural areas, changing the optical properties of aerosols. Aerosol scattering and backscattering coefficients increased by around 40 % in the afternoon when the sea breeze was fully developed while the absorption coefficient increased by more than 100 % as a consequence of the increase in the equivalent black carbon concentration (EBC) observed at MSY under sea breeze circulation.

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Variability of aerosol optical properties in the Western Mediterranean Basin

Pandolfi¹,

Cusack²,

Alástuey³

et al. 2011

Preprint

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Aerosol light scattering, black carbon (BC) and particulate matter (PM) concentrations were measured at Montseny, a regional background site in the Western Mediterranean Basin (WMB) which is part of the European Supersite for Atmospheric Aerosol Research (EUSAAR). Off line analyses of 24 h PM filters collected with Hi-Vol instruments were performed for the determination of the main chemical components of PM. Measurements of BC were used to calculate the light absorption properties of atmospheric particles. Single Scattering Albedo (SSA) at 635 nm was estimated starting from aerosol scattering and absorption measurements, while Ångström exponents were calculated by means of the three wavelengths (450 nm, 525 nm, 635 nm) aerosol light scattering measurements from Nephelometer. Mean scattering and hemispheric backscattering coefficients (@ 635 nm) were 26.8 ± 23.3 Mm−1 and 4.3 ± 2.7 Mm−1, respectively and the mean aerosol absorption coefficient was 2.8 ± 2.2 Mm−1. Mean values of Single Scattering Albedo (SSA) and Ångström exponent (calculated from 450 nm to 635 nm) at MSY were 0.90 ± 0.05 and 1.2 ± 0.6, respectively. A clear relationship was observed between the PM1/PM10 and PM2.5/PM10 ratios as a function of the calculated Ångström exponents. Mass scattering cross sections for fine mass and sulfate at 635 nm were calculated in 2.8 ± 0.5 m2 g−1 and 11.8 ± 2.2 m2 g−1 respectively, while the mean aerosol absorption cross section was estimated around 10.4 ± 2.0 m2 g−1. The variability in aerosol optical properties in the WMB were largely explained by the origin and ageing of air masses over the measurement site. The sea breeze played an important role in transporting pollutants from the developed WMB coastlines towards inland rural areas, changing the optical properties of aerosols. Aerosol scattering and backscattering coefficients increased by around 40 % in the afternoon when the sea breeze was fully developed while the absorption coefficient increased by more than 100 % as a consequence of the increase in BC concentration at MSY observed under sea breeze circulation. The analysis of the Ångström (Å) exponent as a function of the origin the air masses revealed that polluted winter anticyclonic conditions and summer recirculation scenarios typical of the WMB led to an increase of fine particles in the atmosphere (Å = 1.4 ± 0.1) while the aerosol optical properties under Atlantic Advection episodes and Saharan dust outbreaks were clearly dominated by coarser particles (Å = 0.7 ± 0.3)

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Aerosol distribution over the western Mediterranean basin during a Tramontane/Mistral event

Cited by 3 publications

References 17 publications

Ocean memory effect on the dynamics of coastal heavy precipitation preceded by a mistral event in the northwestern Mediterranean

Ocean memory effect on the dynamics of coastal heavy precipitation preceded by a mistral event in the northwestern Mediterranean

Variability of aerosol optical properties in the Western Mediterranean Basin

Variability of aerosol optical properties in the Western Mediterranean Basin

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