Heterodyne detection of CO2 emission lines and wind velocities in the atmosphere of Venus

Betz, Albert; Johnson, M. A.; McLaren, R.; Sutton, E. C.

doi:10.1086/182251

Cited by 65 publications

(10 citation statements)

References 5 publications

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“…We have already noted that the motions deduced in this way are predominantly zonal with speeds of about 100 m/ s; mean meridional motions are poleward with speeds of several meters per second. Ground-based measurements, using spectroscopic and heterodyne techniques, have provided estimates of the zonal wind in the region at and above the clouds Carleton, 1975, 1979;Betz et al, 1976Betz et al, , 1977. Both the spectroscopic and the heterodyne observations have yielded 100 m/s retrograde zonal winds at cloud heights, in agreement with the spacecraft observations.…”

Section: Wind Velocities Inferred From Radio Interferometric Trackingmentioning

confidence: 99%

Structure and circulation of the Venus atmosphere

Schubert¹,

Covey²,

Genio³

et al. 1980

J. Geophys. Res.

188

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Pioneer Venus has revealed important new features of the structure and the circulation of Venus' atmosphere. The temperature decreases from nearly 750 K at the surface to about 180 K at about 100 km. Above 100 km, there is a marked contrast between the day‐side and the night‐side thermal structures. On the day side there is a thermosphere in which temperatures increase with height to an exospheric temperature of about 300 K. On the night side there is a ‘cryosphere’ in which temperatures decrease with height to an exospheric temperature of about 100 K. The atmosphere is stably stratified from the highest altitudes down to about 28 km except for a layer in the clouds, between about 50 and 55 km, which is nearly adiabatic. Between about 20 and 28 km, the lapse rate is also nearly adiabatic while there is evidence for stable stratification between about 10 and 20 km. Horizontal thermal contrasts are of the order of 1–2% in the deep atmosphere and 100% in the upper atmosphere. At and below the clouds, temperatures generally decrease with latitude on constant pressure surfaces; above the clouds, between about 70 and 90 km, there is a reversed zonally averaged latitudinal temperature gradient. The dominant circulation of the atmosphere above the lowest one or two scale heights is a zonal retrograde motion with 100 m/s winds at 60 km altitude. There is also a superrotation of the atmosphere at altitudes of 150 km and above. Low latitude height profiles of the zonal wind have alternating layers of high and low shear which correlate with structure in the vertical profiles of static stability. Advection of heat by the large zonal winds helps maintain the relatively small longitudinal thermal contrasts throughout the atmosphere below the clouds. Latitudinal temperature and pressure contrasts are consistent with a zonally rotating atmosphere in approximate cyclostrophic balance. Meridional winds below 60 km vary in speed from a few to about 10 m/s; the winds are poleward at the cloud tops. A cloud level Hadley cell driven by solar heating combines with the zonal circulation to produce a cloud top polar vortex. Eddies in the form of convective cells, small‐scale gravity waves, and planetary scale waves are found throughout the atmosphere. Eddies, as well as mean meridional circulations, may be important in the transport of energy and momentum. Venus' atmospheric circulation is not steady despite the planet's small obliquity and nearly circular orbit.

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Section: Wind Velocities Inferred From Radio Interferometric Trackingmentioning

confidence: 99%

Structure and circulation of the Venus atmosphere

Schubert¹,

Covey²,

Genio³

et al. 1980

J. Geophys. Res.

188

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“…Over the past 30 years IR heterodyne spectroscopy has proven to be a powerful tool for astrophysical studies and much useful information has been gathered from measurements of the Earth's atmosphere as well as the atmospheres of other planets of the solar system (Kostiuk 1983;Betz et al 1976;Kostiuk et al 1996Kostiuk et al , 2001). To achieve high spectral resolution and sensitivity with compact instrumentation heterodyne systems are advantageous over direct-detection methods.…”

Section: Introductionmentioning

confidence: 99%

“…By analyzing the shape of emission or absorption lines various information on the physical parameters of the gas can be retrieved. A particularly interesting phenomenon is the non-LTE CO 2 emission from the atmospheres of Mars and Venus (Betz et al 1976;Deming et al 1983;Mumma et al 1981). While first observed in the mid 1970ies the process of its formation is still a subject of theoretical and observational investigation (Roldán et al 2000;Kutepov et al 2003).…”

Section: Introductionmentioning

confidence: 99%

High-resolution observations of Martian non-thermal CO₂emission near 10 $\mathsf{\mu}$m with a new tuneable heterodyne receiver

Sonnabend¹,

Wirtz

Vetterle

et al. 2005

A&A

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Abstract. We present first observations with the Tuneable Heterodyne Infrared Spectrometer (THIS). This instrument developed at University of Cologne has the potential to cover the mid-infrared from 7 to 19 µm. By using heterodyne techniques and an acousto optical spectrometer (AOS) as a back-end the frequency resolution achieved is better than 10 7 at 10 µm. A tuneable quantum-cascade laser (QCL) is used as a local-oscillator (LO) and the instantaneous bandwidth supplied by the mercurycadmium-telluride (MCT) detector and the AOS is 1.4 GHz. The system operates within a factor of two of the quantum limit. During December 2003 THIS was installed at the 1.5 m McMath-Pierce solar telescope on Kitt Peak/Arizona. Observations of molecular line features from the atmosphere of Mars were carried out. We present measurements of narrow non-LTE CO 2 emission from the Martian atmosphere observed with a never before achieved frequency resolution of 1 MHz. The first analysis suggests zonal winds in the mesosphere of Mars in good agreement with model predictions.

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“…Solar scans at each observed Venusian line were also made as a measure of the amount of telluric attenuation. We see that higher J transitions in the P branch in Venus have weaker or negligible emission cores and may be used to deconvolve the pressure-and temperature-profiles of the lower atmosphere Lower J transitions in the P branch have sizeable emission cores and are probes of the mesosphere and upper atmosphere (Betz et al 1976).…”

mentioning

confidence: 94%

A 10 Micron Heterodyne Receiver for Ultra High Resolution Astronomical Spectroscopy

Bühl¹,

Chin²,

Faris³

et al. 1980

Symp. - Int. Astron. Union

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Infrared heterodyne spectroscopy is extremely useful in determining by precise measurements of atomic and molecular infrared line spectra the molecular abundances, velocity structure, and excitation conditions of the interstellar medium, and the temperature-and pressure-profiles of planetary atmospheres (cf. Kostiuk et al. 1977, Betz et al. 1976, Abbas et al. 1978).Heterodyne detection is achieved by combining infrared source radiation with a coherent laser local oscillator output at a non-linear detector -e.g. HgCdTe photo-mixer. The difference frequency or inter mediate-frequency (IF) recovers the spectral characteristics of the source radiation and may be measured by radio frequency techniques to an arbitrarily high resolving power.Our present C0 2 laser heterodyne spectrometer (Fig. 1) includes several improvements over our first generation system described by Mumma et al. 1978 andKostiuk et al. 1977: the present system uses reflective optics to eliminate re-focusing at different wavelengths, and the local oscillator is a line-center-stabilized isotopic CO2 laser built at GSFC. Easy and rapid selection of over 50 transitions per isotope of C0 2 is made possible by a tunable diffraction grating. A GSFC built visible and infrared star-tracker can be used for automatic guiding on astrononomical sources. The IF (0-1.6 GHz) from the HgCdTe photomixer is analysed by a 128-channel filter bank. A tunable bank of 64 5-MHz filters and a fixed set of 64 25-MHz RF filters provide resolving powers of VL0 6 -10 7 and velocity resolution of 50-250 m/sec. The output of the 128 filters is synchronously detected, integrated, multiplexed and stored as signal (S) and reference (R) in a buffer memory for the desired inte gration period. The result is presented as (S-R)/R, and stored on floppy disks for subsequent data reduction. A CRT graphics terminal provides on-line display with the printer and hard-copy unit providing more permanent records (Fig. 2).The observations were taken on the main telescope of the McMath

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Heterodyne detection of CO2 emission lines and wind velocities in the atmosphere of Venus

Cited by 65 publications

References 5 publications

Structure and circulation of the Venus atmosphere

Structure and circulation of the Venus atmosphere

High-resolution observations of Martian non-thermal CO₂emission near 10 $\mathsf{\mu}$m with a new tuneable heterodyne receiver

A 10 Micron Heterodyne Receiver for Ultra High Resolution Astronomical Spectroscopy

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Heterodyne detection of CO2 emission lines and wind velocities in the atmosphere of Venus

Cited by 65 publications

References 5 publications

Structure and circulation of the Venus atmosphere

Structure and circulation of the Venus atmosphere

High-resolution observations of Martian non-thermal CO2emission near 10 $\mathsf{\mu}$m with a new tuneable heterodyne receiver

A 10 Micron Heterodyne Receiver for Ultra High Resolution Astronomical Spectroscopy

Contact Info

Product

Resources

About

High-resolution observations of Martian non-thermal CO₂emission near 10 $\mathsf{\mu}$m with a new tuneable heterodyne receiver