Impact of West African Monsoon convective transport and lightning NO&amp;lt;sub&amp;gt;x&amp;lt;/sub&amp;gt; production upon the upper tropospheric composition: a multi-model study

Barret, Brice; Williams, J. E.; Bouarar, Idir; Yang, Xin; Josse, B.; Law, Kathy S.; Pham, Mai Khanh; Flochmoën, É. Le; Liousse, Catherine; Peuch, Vincent-Henri; Carver, G. D.; Pyle, J. A.; Sauvage, Bastien; Velthoven, P. van; Schläger, Hans; Mari, C.; Cammas, Jean‐Pierre

doi:10.5194/acpd-10-2245-2010

Cited by 11 publications

(12 citation statements)

References 86 publications

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“…(c) Above 500 hPa, the ozone mixing ratios rapidly increased with a range of 60 to nearly 100 ppb in the 400-300 hPa layer which is most likely linked to production of LNO X over West Africa and transported westward towards Cape Verde. The production of LNO X leading to an increase in downstream O 3 mixing ratios over the tropical Atlantic is consistent with Global Chemical Transport Model (GCTM) results [Barret et al, 2010].…”

Section: Discussionsupporting

confidence: 87%

The influence of the SAL and lightning on tropospheric ozone variability over the Northern Tropical Atlantic: Results from Cape Verde during 2010

Jenkins

Robjhon

Smith

et al. 2012

Geophysical Research Letters

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[1] We present results for multiple Saharan Air Layer (SAL) events and their relationship to tropospheric ozone mixing ratios that were observed in the Eastern Atlantic during the summer of 2010 using ozonesondes. In particular, 5 SAL events are sampled during 2010 in Cape Verde indicting a reduction of ozone mixing ratios throughout much of the SAL layer, except near the base of the SAL. In this layer of enhanced ozone mixing ratio, we find increases of 20-30 ppb in some cases between non-SAL and SAL conditions. In addition, ozone concentrations are enhanced above the SAL layer, with trajectories suggesting enhancements by lightning from the middle/upper troposphere with outflow from Africa. Additional aircraft measurements are required to examine the chemical and aerosol distributions from the Marine Boundary Layer (MBL) through the upper troposphere to determine the heterogeneous chemical processes related to reduced ozone mixing ratio, and further quantify elevated ozone mixing ratios at the base of the SAL and above the SAL.

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Section: Discussionsupporting

confidence: 87%

The influence of the SAL and lightning on tropospheric ozone variability over the Northern Tropical Atlantic: Results from Cape Verde during 2010

Jenkins

Robjhon

Smith

et al. 2012

Geophysical Research Letters

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“…missed fires, cloud cover that can mask the detection of fires under the cloud fields, all causing underestimation of the emissions (Pereira et al, 2009). In fact, other studies reported that GFED2 inventory might underestimate CO emissions (van der Werf et al, 2006;Jones et al, 2009;Turquety et al, 2009;Barret et al, 2010). Recent versions of the model from v-01-02 and later accept GFED3 updated inventory, which might have solved this issue.…”

Section: Integration Of Geos-chem Model Results With Previous Analysesmentioning

confidence: 99%

Analysis of tropospheric ozone and carbon monoxide profiles over South America based on MOZAIC/IAGOS database and model simulations

Yamasoe¹,

Sauvage²,

Thouret³

et al. 2015

Tellus B: Chemical and Physical Meteorology

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For ozone, results showed a clean atmosphere over Caracas presenting the highest seasonal mean in March, April and May. Backward trajectory analyses with FLEXPART, of case studies for which the measured concentrations were high, showed that contributions from local, Central and North America, the Caribbean and Africa either from anthropogenic emissions, biomass burning or lightning were possible. Satellite products as fire counts from MODIS, lightning flash rates from LIS, and CO and O 3 from Infrared Atmospheric Sounding Interferometer and wind maps at different levels helped corroborate previous findings. Sensitivity studies performed with the chemical transport model GEOS-Chem captured the effect of anthropogenic emissions but underestimated the influence of biomass burning, which could be due to an underestimation of GFEDv2 emission inventory. The model detected the contribution of lightning from Africa in JJA and SON and from South America in DJF, possibly from the northeast of Brazil. Over Sa˜o Paulo and Rio de Janeiro, GEOS-Chem captured the seasonal variability of lightning produced in South America and attributed this source as the most important in this region, except in JJA, when anthropogenic emissions were addressed as the more impacting source of ozone precursors. However, comparison with the measurements indicated that the model overestimated ozone formation, which could be due to the convective parameterisation or the stratospheric influence. The highest ozone concentration was observed during September to November, but the model attributed only a small influence of biomass burning from South America, with no contribution of long-range transport from Africa.

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“…This run used the boundary layer mixing scheme of of Holtslag and Boville (1993), and is therefore very similar to run TOMCAT R2. In pTOMCAT-tropical, the original implementation of the convective scheme used in p-TOMCAT has been updated to increase convective transport to the mid and upper troposphere (Barret et al, 2010). The entrainment rate is set to be half the value suggested by Tiedtke (1989).…”

Section: Ptomcat Ctmmentioning

confidence: 99%

Tropical deep convection and its impact on composition in global and mesoscale models – Part 2: Tracer transport

Hoyle¹,

Marécal²,

Russo³

et al. 2010

Preprint

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The tropical transport processes of 14 different models or model versions were compared, within the framework of the SCOUT-O3 (Stratospheric-Climate Links with Emphasis on the Upper Troposphere and Lower Stratosphere) project. The tested models range from the regional to the global scale, and include numerical weather prediction (NWP), chemistry transport, and climate chemistry models. Idealised tracers were used in order to prevent the model's chemistry schemes from influencing the results substantially, so that the effects of modelled transport could be isolated. We find large differences in the vertical transport of very short lived tracers (with a lifetime of 6 hours) within the tropical troposphere. Peak convective outflow altitudes range from around 300 hPa to almost 100 hPa among the different models, and the upper tropospheric tracer mixing ratios differ by up to an order of magnitude. The timing of convective events is found to differ between the models, even among those which source their forcing data from the same NWP model (ECMWF). The differences are less pronounced for longer lived tracers, however they could have implications for the modelling of the halogen burden of the lowermost stratosphere through species such as bromoform, or for the transport of short lived hydrocarbons into the lowermost stratosphere. The modelled tracer profiles are found to be strongly influenced by the convective transport parameterisations, and boundary layer mixing parameterisations of the models. The location of rapid transport into the upper troposphere is similar among the models, and is mostly concentrated over the western Pacific, the Maritime Continent and the Indian Ocean. In contrast, none of the models indicates significant enhancement in upward transport over western Africa. The mean mixing ratios of an idealised CO like tracer in the upper tropical troposphere are found to be sensitive to the surface CO mixing ratios in the regions with the most active convection, revealing the importance of correctly modelling both the location of convective transport and the geographical pollutant emission patterns

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Impact of West African Monsoon convective transport and lightning NO<sub>x</sub> production upon the upper tropospheric composition: a multi-model study

Cited by 11 publications

References 86 publications

The influence of the SAL and lightning on tropospheric ozone variability over the Northern Tropical Atlantic: Results from Cape Verde during 2010

The influence of the SAL and lightning on tropospheric ozone variability over the Northern Tropical Atlantic: Results from Cape Verde during 2010

Analysis of tropospheric ozone and carbon monoxide profiles over South America based on MOZAIC/IAGOS database and model simulations

Tropical deep convection and its impact on composition in global and mesoscale models – Part 2: Tracer transport

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