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Brice Barret , Philippe Ricaud, Jean-Luc Attié, Eric Leflochmoën Laboratoire d’Aérologie, 

Projets autour de l’sssimilation multi-capteurs spatiaux au LA pour l’étude des processus physico-chimiques dans l’UTLS. Brice Barret , Philippe Ricaud, Jean-Luc Attié, Eric Leflochmoën Laboratoire d’Aérologie,  Observatoire Midi-Pyrénées, Toulouse, France. Collaborations: CNRM, CERFACS.

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Brice Barret , Philippe Ricaud, Jean-Luc Attié, Eric Leflochmoën Laboratoire d’Aérologie, 

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  1. Projets autour de l’sssimilation multi-capteurs spatiaux au LA pour l’étude des processus physico-chimiques dans l’UTLS Brice Barret, Philippe Ricaud, Jean-Luc Attié, Eric Leflochmoën Laboratoire d’Aérologie,  Observatoire Midi-Pyrénées, Toulouse, France Collaborations:CNRM, CERFACS Atelier ADOMOCA 13-15 décembre 2005

  2. Problématique Processus dynamiques et chimiques dans l’UTLS Chimie de l’ozone stratosphérique Impact radiatif (ozone, vapeur d’eau) Processus de déshydratation dans la TTL Augmentation de la vapeur d’eau stratosphérique Peu d’information à l’échelle globale (satellites) • Plan • Instruments spatiaux impliqués • Validation croisée Odin/SMR vs. Aura/MLS • SMR/CO dans la basse stratosphère • Comparaison avec MOPITT • Impact de la circulation atmosphérique sur la distribution des gaz • Stratosphère: Brewer-Dobson • Troposphère : Hadley, Walker • Echanges troposphère-stratosphère • Conclusions et perspectives Atelier ADOMOCA 13-15 décembre 2005

  3. Les missions spatiales impliquées Odin/SMR, Aura/MLS… Sondage de la stratosphère couche d’ozone Metop/IASI, Terra/MOPITT, Aqua/AIRS… Sondage de la troposphère pollution, climat MTG, GeoTROPE, TRAQ…? Sondage de la troposphère pollutions locales et régionales Atelier ADOMOCA 13-15 décembre 2005

  4. Cross-Validation Odin/SMR vs. Aura/MLS O3 • Good agreement from 100 to 1 hPa • MLS > SMR ~ 20% from 30 to 1 hPa at high lat. • MLS < SMR up to 40% above 20 hPa in the tropics and at mid. Lat. • MLS > SMR below ~ 30 hPa at all latitudes • R > 0.8 from 68.1 to 6.8 hPa Consistent with MLS comparisons with SAGEII and ACE (Froidevaux et al., 2005) Atelier ADOMOCA 13-15 décembre 2005

  5. Cross-Validation Odin/SMR vs. Aura/MLS N2O • Excellent agreement from 68.1 to 1 hPa • MLS > SMR in the LS  bias up to 60% at 147 hPa at high north. lat. • MLS < SMR above 68.1 hPa  10-15% • SMR noisier than MLS High bias from MLS (up to 60 ppbv) in the LS polar vortices (Froidevaux et al., 2005) Atelier ADOMOCA 13-15 décembre 2005

  6. Cross-Validation Odin/SMR vs. Aura/MLS CO • Good agreement from 14.6 to 0.1 hPa • MLS > SMR above 0.1 hPa • MLS profiles are strongly oscillating • MLS has permanent negative values in the tropics and high north. lat. • High correlations in the upper stratosphere (around 6.8 hPa) Atelier ADOMOCA 13-15 décembre 2005

  7. CO in the Lower Stratosphere SMR Zonal means January 2004 February2004 High CO concentrations in the LS in the winter at high latitudes September 2004 July 2004 Artifact ? A priori effect ? Atelier ADOMOCA 13-15 décembre 2005

  8. CO in the Lower Stratosphere Northern Hemisphere SMR at 18 km MOPITT at 150 hPa Atelier ADOMOCA 13-15 décembre 2005

  9. CO in the Lower Stratosphere Southern Hemisphere SMR at 18 km MOPITT at 150 hPa Atelier ADOMOCA 13-15 décembre 2005

  10. Stratospheric circulation HALOE CH4 • Brewer/Dobson diabatic circulation • Braking of Gravity/Planetary waves • Mesosphere: summer to winter pole • Stratosphere: tropics to winter pole • Tropical/vortex barriers • Surf zone (isentropic mixing) NH Winter SH Winter Atelier ADOMOCA 13-15 décembre 2005

  11. Tropospheric meridional circulation • Seasonal variations: • Shift in the location of the maximum tropical heating • Single North/South Hadley cell in January/July • Dual North/South Hadley cells symmetric/Equator in April/October • The Hadley Cells: • Energy imbalance between the tropics and the pole • Convective rising of warm moist tropical air in the tropics (ITCZ) • Return of the diverging upper-level cool dry air to the surface poleward of the Equator • Movement of air towards the convergence zone at the Equator (Trade Winds) Waliser et al., Climate Dynamics, 1999 Atelier ADOMOCA 13-15 décembre 2005

  12. Tropospheric meridional circulation Impact on the distribution of tropospheric trace gases ? • MOPITT • Meridional/Vertical transport of CO • Seasonal variability: mixture between • Sources: biomass burning • Hadley cells • MOCAGE-Climat/MOPITT • MOPITT low vertical resolution • MOCAGE-Climat sources ? • Further work: • Meteorological context • MOCAGE sources • Convolution of MOCAGE with MOPITT averaging kernels • Assimilated MOPITT CO within MOCAGE Atelier ADOMOCA 13-15 décembre 2005

  13. Walker circulation / ENSO • Normal conditions: • Western Pacific 3 to 8° warmer than Eastern Pacific • Trade winds bring warm moist air towards Indonesia • Rises over warm seas (clouds, rain) • Travels Eastward and sinks over Eastern Pacific (clear, dry) • El Niño conditions: • Central or Eastern Pacific as warm or warmer than Western Pacific… SOI close to zero SOI SOI strongly negative Atelier ADOMOCA 13-15 décembre 2005

  14. Africa Indonesia South America Walker circulation / ENSO Impact on the distribution of tropospheric trace gases ? • O3: • ENSO : strong impact on STE • El Niño (October 1997): strong increase of O3 over western Pacific and decrease over the eastern Pacific (TOMS data) • CO: • Longitudianal/Vertical transport • Evidence of 3 main cells from MOPITT data in non el Niño conditions • No data in el Niño conditions Zeng and Pyle, GRL, 2005 Atelier ADOMOCA 13-15 décembre 2005

  15. Overworld Tropical Transition Layer Lowermost stratosphere Free Troposphere ABL Stratosphere Troposphere Exchange • Slow ascent in the tropics and descent in polar regions • Isentropic transport between the tropical free troposphere and the extratroical lowermost stratosphere • Deep stratospheric intrusions • Warm conveyor belts… Stohl et al., BAMS, 2003 Atelier ADOMOCA 13-15 décembre 2005

  16. Multi-sensor coupling SH Winter • Limb Stratospheric Sounder: • Odin/SMR, Aura/MLS, Envisat/MIPAS… • High vertical resolution (2-4 km) • Low horizontal sampling (> 100 km) • Low sensitivity in the UTLS SMR UTLS ~12-18 km • Nadir Tropospheric Sounder: • Terra/MOPITT, Aqua/AIRS, Metop/IASI… • Low vertical resolution (> 6 km) • High horizontal sampling and resolution • Low sensitivity in the UTLS MOPITT Coupling of data from a Stratospheric and a Tropospheric sounder in MOCAGE via the assimilation coupler PALM  information in the UTLS Atelier ADOMOCA 13-15 décembre 2005

  17. Conclusions • MLS vs. SMR • O3 and N2O: good agreement • CO: MLS V1.5 displays strong oscillations • SMR CO in the lower stratosphere • Increase of CO at high latitudes in winter ? • Atmospheric circulation • Stratosphere : general features seen by all the limb sounders with long-lived tracers • Troposphere: • Mean meridional circulation not directly evident from MOPITT • Walker circulation: evidence from MOPITT • Stratosphere-Troposphere exchanges • Nadir viewing instruments: low vertical resolution • Limb sounders: low sensitivity in the UTLS/TTL • Need to couple both type of observations via assimilation (PALM/MOCAGE) Atelier ADOMOCA 13-15 décembre 2005

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