Mars Mesospheric Wind around Northern Spring Equinox from ... · Slide: 11 Motivation Instrument & Method Observation Results & Outlook MARS ATMOSPHERE: MODELING AND OBSERVATIONS

MARS ATMOSPHERE: MODELING AND OBSERVATIONSWilliamsburg, Va, November 10th 2008

Universität zu KölnI. Physikalisches Institut Slide: 1

Mars Mesospheric Wind around Northern Spring Equinox from

High Resolution IR spectroscopy of CO2

Manuela Sornig1, Guido Sonnabend1, Peter Krötz1, Dušan Stupar1, Rudolf Schieder1,

1I. Physikalisches Institut, Universität zu Köln

Slide: 2

Motivation Instrument & Method Observation Results & Outlook


Universität zu KölnI. Physikalisches Institut

Overview:

•Motivation•Technique

- THIS - Tunable Heterodyne Infrared Spectrometer- Doppler winds from high resolution spectroscopy

of CO2

•Observations - LS=335 (2005), LS=357 (2007), LS=42 (2008)

•Results & Comparison to MCD

Slide: 3




Motivation:

- GCMs predict upper atmosphere zonal winds... but observations are few

- Mid-IR spectroscopy of CO2 non-LTE emission @ 10µm ideal tool to probe mesospheric zonal winds

- Ultra-high heterodyne resolution provides Doppler-winds down to 10 m/s precision

- Higher spatial resolution compared to sub-mm

- Circulation changes around LS=0 from northern to southern hemisphere jet

Slide: 4




THIS - Tuneable Heterodyne Infrared Spectrometer

wavelength: 7-13µmresolution: up to 107 @ 10µm

bandwidth: 3 GHzframe dim.: 60x80x45 cm

weight: 80 kgF/#: adjustable

Instrument:

Slide: 5




Methode of Wind Measurements:

• precise frequency determination of non-LTE emission line of CO

2 at 10 µm

• Doppler shift provides information about "line of sight" velocity

• Altitude of emission features determined from TES observations

inte

nsity

frequencyin

tens

ity

frequency

inte

nsity

frequency

Slide: 6




Observations:Nov 2005 (LS=335)McMath/Kitt Peak Nov 2007 (LS=357)

McMath/Kitt Peak

Mar 2008 (LS=42)IRTF/Mauna Kea

Mars:9” FOV:0.8”Mars:16” FOV:1.7”

Mars:15” FOV:1.7”

Slide: 7




CO2 Spectrum from Mars Atmosphere:

200 300 400 500 600 700 800 900 1000 110025

30

35

40

45

50

55

60

65

isotopic CO2 feature

continuum leveldetermined by Marssurface temperature

mesospheric CO2

non-LTE emission

inte

nsi

ty [erg

cm

-2 s

-1 S

r-1/c

m-1]

i.f. [MHz]

broad CO2 absorptionfrom lower atmosphere

Slide: 8




2005 Observations:(LS=335)

Slide: 9




2007 Observations:

(LS=357)

Slide: 11




2008 Observations:

(LS=42)

Slide: 12




Temporal variations:

~25 m/s wind velocity change from MUT5 to MUT10 in agreement with MCD

Slide: 13




Conclusion and Outlook:

• Observations are in reasonable agreement with MCD predictions

• High latitudes winds tend to be stronger than predicted• Short term variations observed

• Improved coverage needed• Seasonal extension• Altitude extraction from data



Thank you!

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KP05 LS332 KP07 LS354 IRTF 08 LS42



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Documents

Mars Mesospheric Wind around Northern Spring Equinox from ... · Slide: 11 Motivation Instrument & Method Observation Results & Outlook MARS ATMOSPHERE: MODELING AND OBSERVATIONS