World Library  


Add to Book Shelf
Flag as Inappropriate
Email this Book

Medium-range Mid-tropospheric Transport of Ozone and Precursors Over Africa: Two Numerical Case-studies in Dry and Wet Seasons : Volume 7, Issue 2 (05/04/2007)

By Sauvage, B.

Click here to view

Book Id: WPLBN0003997940
Format Type: PDF Article :
File Size: Pages 31
Reproduction Date: 2015

Title: Medium-range Mid-tropospheric Transport of Ozone and Precursors Over Africa: Two Numerical Case-studies in Dry and Wet Seasons : Volume 7, Issue 2 (05/04/2007)  
Author: Sauvage, B.
Volume: Vol. 7, Issue 2
Language: English
Subject: Science, Atmospheric, Chemistry
Collections: Periodicals: Journal and Magazine Collection (Contemporary), Copernicus GmbH
Historic
Publication Date:
2007
Publisher: Copernicus Gmbh, Göttingen, Germany
Member Page: Copernicus Publications

Citation

APA MLA Chicago

Duron, J., Pont, V., Sauvage, B., Mari, C., Escobar, J., Mascart, P.,...Gheusi, F. (2007). Medium-range Mid-tropospheric Transport of Ozone and Precursors Over Africa: Two Numerical Case-studies in Dry and Wet Seasons : Volume 7, Issue 2 (05/04/2007). Retrieved from http://worldebooklibrary.com/


Description
Description: Laboratoire d'Aérologie, Toulouse, France. A meso-scale model was used to understand and describe the processes driving high ozone concentrations observed during both dry and monsoon seasons in monthly climatologies profiles over Lagos (Nigeria, 6.6° N, 3.3° E), obtained with the MOZAIC airborne measurements (ozone and carbon monoxide). This study focuses on ozone enhancements observed in the upper-part of the lower troposphere, around 3000 m. Two individual cases have been selected in the MOZAIC dataset as being representative of the climatological ozone enhancements, to be simulated and analyzed with on-line Lagrangian backtracking of airmasses.

This study points out the role of baroclinic low-level circulations present in the Inter Tropical Front (ITF) area. Two low-level thermal cells around a zonal axis and below 2000 m, in mirror symmetry to eachother with respect to equator, form near 20° E and around 5° N and 5° S during the (northern hemisphere) dry and wet seasons respectively. They are caused by surface gradients – the warm dry surface being located poleward of the ITF and the cooler wet surface equatorward of the ITF.

A convergence line exists between the poleward low-level branch of each thermal cell and the equatorward low-level branch of the Hadley cell. Our main conclusion is to point out this line as a preferred location for fire products – among them ozone precursors – to be uplifted and injected into the lower free troposphere.

The free tropospheric transport that occurs then depends on the hemisphere and season. In the NH dry season, the African Easterly Jet allows transport of ozone and precursors westward to Lagos. In the NH monsoon (wet) season, fire products are transported from the southern hemisphere to Lagos by the southeasterly trade that surmounts the monsoon layer. Additionally ozone precursors uplifted by wet convection in the Inter Tropical Convergence Zone can also mix to the ones uplifted by the baroclinic cell and be advected up to Lagos by the trade flow.


Summary
Medium-range mid-tropospheric transport of ozone and precursors over Africa: two numerical case-studies in dry and wet seasons

Excerpt
Marufu, L., Dentener, F., Lelieveld, J., Andreae, M., and Helas, G.: Photochemistry of the African troposphere: Influence of biomass-burning emissions, J. Geoph. Res., 105, 14 513–14 530, 2000.; Morcrette, J.-J.: Radiation and cloud radiative properties in the European Center for Medium range Weather Forcasts forecasting system, J. Geoph. Res., 96, 9121–9132, 1991.; Parker, D., Thorncroft, C., Burton, R., and Diongue-Niang, A.: Analysis of the African easterly jet, using aircraft observations from the JET2000 experiment, Quart. J. Roy. Meteor. Soc., 131, 1461–1482, 2005.; Peyrillé, P., Lafore, J.-P., and Redelsperger, J.-L.: An idealized framework to study the West African monsoon, Part I: Validation and key controlling factors, J. Atmos. Sci., in press, 2006.; Redelsperger, J.-L., Diongue, A., Diedhou, A., Ceron, J.-P., Diop, M., Gueremy, J.-F., and Lafore, J.-P.: Multi-scale description of a Sahelian synoptic weather system representative of the West African monsoon, Quart. J. Roy. Meteor. Soc., 128, 1229–1257, 2002.; Rowell, D., Folland, C., Maskell, K., and Ward, M.: Variability of summer rainfall over tropical North Africa, Quart. J. Roy. Meteor. Soc., 121, 669–704, 1995.; Andreae, M O.: The influence of tropical biomass burning on climate and the atmospheric environment, Biogeochemistry of Global Change: Radiatively Active Trace Gases, edited by: R. S. Oremland, 113–150, Chapman and Hall, New York, 1993.; Bougeault, P. and Lacarrère, P.: Parameterization of orography-induced turbulence in a meso-beta scale model, Mon. Wea. Rev., 117, 1870–1888, 1989.; Bechtold, P., Kain, J., Bazile, E., Mascart, P., and Richard, E.: A mass flux convection scheme for regional and global models, Quart. J. Roy. Meteor. Soc., 127, 869–886, 2001.; Sauvage, B., Thouret, V., Cammas, J., Gheusi, F., Athier, G., and N��ec, P.: Tropospheric ozone over Equatorial Africa: regional aspects from the MOZAIC data, Atmos. Chem. Phys., 5, 311–335, 2005.; Singh, H. B. e a.: Impact of biomass burning emissions on the composition of the South Atlantic troposphere: Reactive nitrogen and ozone, J. Geoph. Res., 101, 24 203–24 220, 1996.; Sperber, K. and Palmer, T.: Interannual tropical rainfall variability in general circulation model simulations associated with the Atmospheric Model Intercomparison Project, jc, 9, 2727–2750, 1996.; Thorncroft, C. and Blackburn, M.: Maintenance of the African easterly jet, Quart. J. Roy. Meteor. Soc., 125, 763–786, 1999.; Wang, G. and Eltahir, E.: Biosphere-atmosphere interactions over West Africa. II: Multiple climate equilibria, Quart. J. Roy. Meteor. Soc., 126, 1261–1280, 2000.; Burpee, R.: Some features of synoptic-scale waves based on a composing analysis at gate data, Mon. Wea. Rev., 103, 921–925, 1975.; Chatfield, R. and Delany, A.: Convection links biomass burning to increased tropical ozone: However, models will tend to overpredict O3, J. Geoph. Res., 95, 18 473–18 488, 1990.; Chou, C. and Neelin, J.: Mechanisms limiting the northward extent of the northern summer monsoons over North America, Asia, and Africa, jc ???, 16, 406–424, 2003.; Noilhan, J. and Planton, S.: A simple parametrization of land surface precessus for meteorological models, Mon. Wea. Rev., 117, 536–549, 1989.; Cuxart, J., Bougeault, P., and Redelsperger, J.-L.: A turbulence scheme allowing for mesoscale and large-eddy simulations, Quart. J. Roy. Meteor. Soc., 126, 1–30, 2000.; Edwards, D. P. e a.: Satellite-observed pollution from Southern Hemisphere biomass burning, J. Geophys. Res., 111, doi:10.1029/2005JD006 655, 2006.; Gal-Chen, T. and Sommerville, R.: On the use of a coordinate transformation for the solution of the Navier-Stokes equations, J. Comput. Phys., 17, 209–228, 1975.; Gheusi, F. and Stein, J.: Lagrangian description of air-flows using Eulerian pass

 

Click To View

Additional Books


  • Long-range Transport of Mineral Aerosols... (by )
  • Differences Between Ground Dobson, Brewe... (by )
  • Development of a High Temporal–spatial R... (by )
  • Global Cfc-11 (Cfcl3) and Cfc-12 (Cf2Cl2... (by )
  • Sulfuric Acid and Oh Concentrations in a... (by )
  • Novel Methods for Predicting Gas-particl... (by )
  • Will the Role of Intercontinental Transp... (by )
  • Influence of Transport and Mixing in Aut... (by )
  • Aerosol Physicochemical Properties and I... (by )
  • European Summer Surface Ozone 1990–2100 ... (by )
  • Asymmetricity of Ground-based Gps Slant ... (by )
  • How Small is a Small Cloud? : Volume 8, ... (by )
Scroll Left
Scroll Right

 



Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.