A model study of ozone in the eastern Mediterranean free troposphere during MINOS (August 2001)

Abstract

Abstract.A coupled tropospheric chemistry-climate model is used to analyze tropospheric ozone distributions observed during the MINOS campaign in the eastern Mediterranean region (August, 2001). Modeled ozone profiles are generally in good agreement with the observations. Our analysis shows that the atmospheric dynamics in the region are strongly influenced by the occurrence of an upper tropospheric anti-cyclone, associated with the Asian summer monsoon and centered over the Tibetan Plateau. The anti-cyclone affects the chemical composition of the upper troposphere, where ozone concentrations of about 50 ppbv were measured, through advection of boundary layer air from South-East Asia. A layer between 4-6 km thickness was present beneath, containing up to 120 ppbv of ozone with substantial contributions by transport from the stratosphere and through lightning NO x . Additionally, pollutant ozone from North America was mixed in. Ozone in the lower troposphere originated mainly from the European continent. The stratospheric influence may be overestimated due to too strong vertical diffusion associated with the relatively coarse vertical resolution. The estimated tropospheric ozone column over the eastern Mediterranean is ∼50 DU in summer, to which ozone from recent stratospheric origin contributes about 30%, ozone from lightning 13%, and from South-East Asia, North America and Europe about 7%, 8% and 14%, respectively, adding to a longterm hemispheric background of 25% of the column.

Modelling constraints on the emission inventory and on vertical dispersion for CO and SO<sub>2</sub> in the Mexico City Metropolitan Area using Solar FTIR and zenith sky UV spectroscopy

“…Improvements in the specification of the vertical diffusion coefficients were suggested but evaluation was limited due to the lack of measurements of the vertical concentration profiles. Biswas and Rao (2001) report substantial differences between different models adding to uncertainties in ozone simulations and Roelofs et al (2003) suggest that coarse vertical resolution may lead to excessive dispersion. Brandt et al (1998) analysed different vertical dispersion schemes and found that the simplest scheme of high vertical dispersion yielded the best results, suggesting that non-local dispersion is an important factor.…”

Atmospheric pollution over the eastern Mediterranean during summer – a review

“…Numerous researchers have identified the EM as a "hot spot" of summertime tropospheric ozone (e.g., Stohl et al, 2001;Roelofs et al, 2003;Zbinden et al, 2013;Zanis et al, 2014;Doche et al, 2014;Safieddine et al, 2014). Zbinden et al (2013) derived the climatological profiles and column contents of tropospheric O 3 from the Measurement of Ozone by Airbus in-service Aircraft program (MOZAIC) over the mid-northern latitudes (24 to 50 • N) over the 1994-2009 period.…”

“…Given the observed ratio of SO 4 to total S of 40-90 % in the region (Matvev et al, 2002;Sciare et al, 2003), the annual flux of SO 4 based on field measurements is 0.024-0.054 Tg yr −1 . Rudich et al (2008) used satellite data to estimate the pollution transport toward the EM. MODIS Terraand Aqua-derived estimates of the annual SO 4 flux along the same transect are 0.038 and 0.040 Tg yr −1 , respectively, in the middle of the range obtained from field observations.…”

“…Therefore, air pollutants emitted from upwind sources to the west of the EM will reach the EM and will be added to those emitted locally. Indeed, numerous observational and modeling studies have confirmed that the EM is affected by the long-range transport of air pollutants originating from Europe (e.g., Dayan, 1986;Luria et al, 1996;Wanger et al, 2000;Erel et al, 2002Erel et al, , 2007Erel et al, , 2013Matvev et al, 2002;Rudich et al, 2008;Drori et al, 2012). To get insight into the LRT over the EM, the Air Resources Laboratory's trajectory model (GAMBIT -Gridded Atmospheric Multi-Level Backward Isobaric Trajectories; Harris, 1982) was applied over 1978-1982(Dayan, 1986.…”

Intercomparison of tropospheric ozone models: Ozone transport in a complex tropopause folding event

“…Hence these disturbances are a mechanism for mixing stratospheric air into the troposphere and for intercontinental transport of pollutants. The latter is widely studied at present through campaigns such as NARE and MINOS, and through model studies (e.g., Fehsenfeld et al [1996] (see also International Global Atmospheric Chemistry project (IGAC), IGACtivities, issue 24, 2001, at http://www.igac.unh.edu), Lelieveld et al [2002], Stohl and Trickl [1999], Jacob et al [1999], Roelofs et al [2003], and Trickl et al [2003]). …”