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

slide2

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

slide3

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

slide4

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

slide5

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

slide6

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

co in the lower stratosphere
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

co in the lower stratosphere1
CO in the Lower Stratosphere

Northern Hemisphere

SMR at 18 km

MOPITT at 150 hPa

Atelier ADOMOCA 13-15 décembre 2005

co in the lower stratosphere2
CO in the Lower Stratosphere

Southern Hemisphere

SMR at 18 km

MOPITT at 150 hPa

Atelier ADOMOCA 13-15 décembre 2005

stratospheric circulation
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

tropospheric meridional circulation
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

tropospheric meridional circulation1
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

walker circulation enso
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

walker circulation enso1

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

slide15

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

multi sensor coupling
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

conclusions
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