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2D modeling with Méso-NH over West Africa

2D modeling with Méso-NH over West Africa. Marielle SAUNOIS, Céline MARI, Valérie THOURET, Jean-Pierre CAMMAS,.. Laboratoire d’Aérologie, Toulouse. Méso-NH model configuration.

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2D modeling with Méso-NH over West Africa

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  1. 2D modeling with Méso-NH over West Africa Marielle SAUNOIS, Céline MARI, Valérie THOURET, Jean-Pierre CAMMAS,.. Laboratoire d’Aérologie, Toulouse AMMA WP4.1.3 meeting at Service d'Aéronomie, Jussieu, Paris 2-3 July 2007

  2. Méso-NH model configuration • Built to provide a latitudinal representation of the monsoon and the associated circulation between 10°W and 10°E(Peyrillé et al, 2007) • Domain : 30°S-40°N , surface - 20 km altitude • Resolution : 70 km • African continent : flat between 5°N and 30°N • 30 days of simulation (perpetual day – 15 july) • Lightning parametrization (Mari et al, 2006) • Chemistry scheme ReLACs • Sets of surface emissions (biogenic) (function of latitude, taken from POET/GEIA) x y AMMA WP4.1.3 meeting at Service d'Aéronomie, Jussieu, Paris 2-3 July 2007

  3. Upper troposphere study Motivation : analysis of measurements performed on board of MOZAIC flights over West Africa showing a meridional gradient of ozone What are the relative contribution between photochemical ozone production and transport ? Between surface and lightning sources ? Saunois et al, 2007, paper in revision in JGR Ozone (ppbv) RH (%) V(m/s) AMMA WP4.1.3 meeting at Service d'Aéronomie, Jussieu, Paris 2-3 July 2007

  4. Results Instantaneous latitude-altitudecross sections between -10°S et 40°N and 0 - 18 km • Precusors emitted on surface: • - Convective transport • - Meridional transport • (Hadley cells) • LiNOx impact: • - NOx addition in the upper and mid troposphere • - O3 production enhanced • - O3 minimum more pronounced Without LiNOx With LiNOx NOx O3 AMMA WP4.1.3 meeting at Service d'Aéronomie, Jussieu, Paris 2-3 July 2007

  5. Results – tendencies and gradients Without LiNOx With LiNOx • Convection : O3-poor air masses source for the UT • Chemical tendency : max where NOx max • Ozone chemical production ↑ with LiNOx • ITCZ : convection balance the high chemical production => minimum • Both sides of the ITCZ : weak convection, high chemical production => N and S gradients • Gradients values higher with LiNOx (to the North: pb with the cell expand and O3 accumulation around 25°N) AMMA WP4.1.3 meeting at Service d'Aéronomie, Jussieu, Paris 2-3 July 2007

  6. Lower troposphere study (coll. with C. Reeves) Motivation: analysis of measurements performed on the BAe board in July-August 2006 (ozone, isoprene, NOx, CO, ….) What are the processes controlling the ozone distribution and levels in the boundary layer over West Africa ? What is the budget of ozone source and sinks as a function of latitude ? Sea Trees Courtesy C. Reeves Bare soil AMMA WP4.1.3 meeting at Service d'Aéronomie, Jussieu, Paris 2-3 July 2007

  7. 1700 1500 1300 1100 900 700 500 300 100 50 45 40 35 30 25 20 0.50 0.20 0.10 0.05 0.02 0.01 Results • Ozone: • sharp increase around 13°N • mixing ratios > 45ppb around 17°N • order of magnitude ~ BAe • NOx: • meridional distribution controlled by the soils emissions (maxima at 13-17°N) • Biogenics: • Close to the source (short life time) • Diurnal cycle for emissions => diurnal cycle marked also for mixing ratios (not shown) Instantaneous latitude-altitudecross sections between 0°N et 25°N and 0 - 6 km, day time Ozone (ppbv) Biogenics (pptv) NOx (ppbv) AMMA WP4.1.3 meeting at Service d'Aéronomie, Jussieu, Paris 2-3 July 2007

  8. 0.4 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 0.4 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 Results – tendencies and profiles Ozone, chemistry (ppbv/h) Ozone, turbulence (ppbv/h) Day time Convection: thin lines (+/- 1 ppbv/h) • Near surface: • Convection >0: O3 rich air source (downdrafts) • Turbulence <0: deposition over trees • Chemistry >0: ozone production (0 during night time) • Over ocean, below 700 m:<0 (chemical destruction) • Over trees, below 700 m: >0 weak, chemical production balanced by deposition • Over bare soils , below 700 m : >0 strong, chemical production AMMA WP4.1.3 meeting at Service d'Aéronomie, Jussieu, Paris 2-3 July 2007

  9. Air Namibia (MOZAIC) Cotonou Windhoek Profiles analysis- observations available soon Cotonou: ozone soundings (SHADOZ), WARNING!! undergoing re-processing Study in progress: Characterization of air masses over Cotonou during the West African monsoon (biomass burning plume intrusion from the southern hemisphere, influence of JEA position, meteorological situation …) Air Namibia: daily flight between Europe and Windhoek since Dec. 2005 Studies in progress: Climatology of ozone, CO, RH, and winds vertical profiles over Windhoek during 2006. Characterization of air masses over Windhoek. Climatology of ozone, CO, RH, and winds meridional prodiles in the W. African upper troposphere. => meridional transect AMMA WP4.1.3 meeting at Service d'Aéronomie, Jussieu, Paris 2-3 July 2007

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