The Odin satelliteThe Odin satellite• Swedish led mini-satellite. Cooperation with Canada, Finland, France.

• Launched in February 2001. Design lifetime: 2 years.

• Circular quasi-polar sun-synchronous orbit: ~600km altitude, 96min/orbit, 6h/18h equator crossing.

• Time sharing: 50% astronomy, 50% aeronomy 100% aeronomy since April 2007!

• Limb-sounding in aeronomy mode: ~45-65 scans/orbit, ~15 orbits per day.

• 2 instruments: SMR (Sub-Millimetre Radiometer), OSIRIS (Optical Spectrograph and InfraRed Imaging System)

• Science objectives: stratospheric and mesospheric processes

Odin long-lived tracer observations Odin long-lived tracer observations Nitrous oxide (N2O): 2-3 days / week

Stratosphere ~15-50km, Sources: tropospheric (transport through TTL),

Sinks: photo-dissociation (185-210 nm, ~90%), N2O+O(1D) (~10%)Lifetime: troposphere ~100 years, 30km ~1 years, 45km ~1 month

Carbon monoxide (CO): 2-3 days / month

Lower stratosphere to lower thermosphere ~18-100km,

Sources: CO2 photodissociation (mesosphere + thermosphere),minor chemical source: CH4 oxidation (stratosphere).

Chemical sinks: CO + OH → CO2 + H Lifetime: comparable or longer than typical transport timescales,

e.g. ~1 week around 50 km, longer above

Water vapour (H2O, H2O-18, H2O-17, HDO): 4-5 days / month

Upper troposphere to lower thermosphere: H2O ~11-100km; isotopologues: ~20-70km,Sources: troposphere (transport through TTL, “cold trap”), methane oxidation,

slow conversion from/to H2 in mesosphere.Sinks: photo-dissociation, reactions with O(1D), OHLifetime: relatively long-lived in stratosphere

Carbon monoxide inCarbon monoxide instratosphere and mesospherestratosphere and mesosphere

Strato-mesospheric carbon monoxideStrato-mesospheric carbon monoxide

Sources:Sources: COCO22 photolysis (mesosphere + thermosphere), photolysis (mesosphere + thermosphere),

minor chemical source: CHminor chemical source: CH44 oxidation (stratosphere). oxidation (stratosphere).

Chemical sinks:Chemical sinks: CO + OH → CO2 + H Lifetime:Lifetime: comparable or longer than typical transport comparable or longer than typical transport

timescales, e.g. ~ 1 week around 50 km timescales, e.g. ~ 1 week around 50 km

transport processes dominate the CO distribution in most of the middle atmosphere

tracer for global meridional circulation, coupling of troposphere-stratosphere-tracer for global meridional circulation, coupling of troposphere-stratosphere-mesosphere, … mesosphere, …

Global observations:Global observations:4.6 4.6 μμm IR emission:m IR emission: UARS/ISAMS (~6 month in 1991-92), Envisat/MIPAS (6/2002-3/04), … UARS/ISAMS (~6 month in 1991-92), Envisat/MIPAS (6/2002-3/04), …mm/sub-mm emission:mm/sub-mm emission: Odin/SMR (several days since Aug 2001), AURA/MLS (7/2004-). Odin/SMR (several days since Aug 2001), AURA/MLS (7/2004-).

CO data analysisCO data analysis Global measurements: Global measurements: CO (J=5CO (J=5→4) @ 576.268 GHz→4) @ 576.268 GHz

Strat-meso scan (7-110 km) Strat-meso scan (7-110 km) → → 7 Aug 2001, 18 Nov 2001, 18 Nov 2002,7 Aug 2001, 18 Nov 2001, 18 Nov 2002, ~1-3 days/month since Oct 2003~1-3 days/month since Oct 2003;;

Summer-meso scan (55-110 km) Summer-meso scan (55-110 km) →→ 2-14 July 2002, ...2-14 July 2002, ...

LO-failure of 572 GHz radiometerLO-failure of 572 GHz radiometer correction for frequency shift! correction for frequency shift!

Profile retrieval:Profile retrieval: altitude range ~20-110 km, resolution ~3 km, altitude range ~20-110 km, resolution ~3 km, single-profile precision 10-25 %. single-profile precision 10-25 %.

7 Aug 2001 – 3N/120W

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Global CO data: seasonal variationGlobal CO data: seasonal variation

CO 7-8 Aug 2001

CO18-19 Nov 2001

N2O24-25 Nov 2001

N2O5 Aug 2001

Seasonal variation: CO and N2O Seasonal variation: CO and N2O

2003, 2004:

N2O@502.3GHz

CO@576.3GHz

Chalmers-v2.1 data

CCM validationCCM validationOdin/SMR CO: profile comparison with ACE/FTS and CMAMOdin/SMR CO: profile comparison with ACE/FTS and CMAM

ACE-FTS: infrared (2-13 ACE-FTS: infrared (2-13 μμm) solar occultation m) solar occultation ((Bernath 2005Bernath 2005)) CMAM:CMAM: general circulation model general circulation model ( (Beagley et al. 1997 Beagley et al. 1997 ))

CMAM

ACE (4,0°S/42,3°E) SMR

(0,6°N/36,2°E)

Erreurs : 1σ

Tropics07/04/2004

CO mixing ratio

CMAM

ACE (79,5°N/9,9°E)

SMR (77,4°N/3,0°E)

Erreurs : 1σ

High latitudes05/03/2004

CO mixing ratio

[J. Jin, E. Dupuy et al., GRL, 2005]

Atmospheric circulation: Odin vs CMAMAtmospheric circulation: Odin vs CMAM

CMAM: Canadian Middle Atmospheric Model (CCM)[data from J.Jin, K. Semeniuk et al., York University, Toronto]

Jul

CO - SMR CO - CMAM

~10hPa~10hPa

N2O - SMR N2O - CMAM

Oct

low biaslow bias

~100hPa~100hPa

CMAMCMAM: small differences in polar descent, : small differences in polar descent, negative N2O bias in upper stratospherenegative N2O bias in upper stratosphere