Stratospheric sounding by infrared heterodyne spectroscopy

Intensity profiles of infrared spectral lines of stratospheric constituents can be fully resolved with a heterodyne spectrometer of sufficiently high resolution. The constituents' vertical distributions can then be evaluated accurately by analytic inversion of the measured line profiles. Estimates of the detection sensitivity of a heterodyne receiver are given in terms of minimum detectable volume mixing ratios of stratospheric constituents, indicating a large number of minor constituents which can be studied. Stratospheric spectral line shapes, and the resolution required to measure them are discussed in light of calculated synthetic line profiles for some stratospheric molecules in a model atmosphere. The inversion technique for evaluation of gas concentration profiles is briefly described and applications to synthetic lines of O3, CO2, CH4 and N2O are given

The tropospheric gas composition of Jupiter's north equatorial belt (NH3, PH3, CH3D, GeH4, H2O) and the Jovian D/H isotropic ratio

The gas composition of the troposphere of Jupiter in the clearest regions of the North Equatorial Belt (NEB) was derived from the Voyager 1 IRIS data. The infrared spectrum for this homogeneous cloud free region was modeled to infer altitude profiles for NH3, PH3, GeH4 and H2O. The Profiles for NH3 and PH3 were found to be depleted in the upper troposphere but otherwise in agreement with their solar values at the 1 bar level. The mole fraction for CH3D was determined to be 3.5(+1.0 or -1.3) x 10 to the minus 7th power. The GeH4 mole fraction of 7+ or -2 x 10 to the minus 10th power at the 2 to 3 bar level is a factor of 10 lower than the solar value. The H2O mole fraction is approximately 1 x 0.00001 at the 2.5 bar level and is increasing to approximately 3 x 0.00001 at 4 bars where it is a factor of 30 lower than solar. Using IRIS infrared values for the mole fractions of CH3D and CH4 a value of D/H = 3.6(+1.0 or -1.4)x 0.00001 is derived. Assuming this Jovian D/H ratio is representative of the protosolar nebula, and correcting for chemical galactic evolution, yields a value of 5.5 - 9.0 x 0.00001 for the primordial D/H ratio and an upper limit of 1.8 to 2.4 x 10 to the minus 31st power cu cm for the present day baryon density

The Atmospheres of Titan and Saturn in the Infrared from Cassini: The Interplay Between Observation and Laboratory Studies

The Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft has been recording spectra of Saturn and Titan since its arrival in the Saturn system in 2004. CIRS, a Fourier transform spectrometer, observes the thermal infrared spectrum of both atmospheres from 10 to 1500/cm with resolutions up to 0.5/cm (Flasar et al. 2004). From these data CIRS provides global coverage of the molecular composition of the stratosphere and troposphere, as well as maps of temperature and winds. From such studies CIRS helps reveal the chemistry and evolutionary history of Saturn and Titan and their relationships to other Solar System bodies. The Cassini mission is continuing until 2017, permitting CIRS to search for atmospheric changes during more than a Saturnian season. By combining with results from Voyager (1980, 1981) the baseline becomes more than one Saturnian year (Coustenis et al. 2011). CIRS spectroscopy of the atmospheres of Saturn and Titan has raised a variety of questions that require new laboratory studies. A complete understanding of the CIRS high-resolution atmospheric spectra cannot be fully achieved without new or improved line positions and intensities for some trace molecules (e.g., Nixon et al. 2009). Isotopic variants of some of the more abundant species often need improved line parameters in order to derive isotopic ratios (e.g., Coustenis et al. 2008 and Fletcher et a!. 2009). Isotopic ratios contain information about the history of an atmosphere if experimental fractionation rates are available (Jennings et al. 2009). Some aerosol and haze features continue to defy identification and will not be explained without better knowledge of how these materials are formed and until we obtain their laboratory spectra. The interaction between CIRS investigations and laboratory research has been productive and has already led to new discoveries

The infrared interferometer spectrometer experiment for the Mars Mariner 1971 orbital mission

Infrared interferometer spectrometer for Mariner spacecraft in Mars orbi

Beable trajectories for revealing quantum control mechanisms

The dynamics induced while controlling quantum systems by optimally shaped laser pulses have often been difficult to understand in detail. A method is presented for quantifying the importance of specific sequences of quantum transitions involved in the control process. The method is based on a ``beable'' formulation of quantum mechanics due to John Bell that rigorously maps the quantum evolution onto an ensemble of stochastic trajectories over a classical state space. Detailed mechanism identification is illustrated with a model 7-level system. A general procedure is presented to extract mechanism information directly from closed-loop control experiments. Application to simulated experimental data for the model system proves robust with up to 25% noise.Comment: Latex, 20 pages, 13 figure

CO_2 on Titan

A sharp stratospheric emission feature at 667 cm^(−1) in the Voyager infrared spectra of Titan is associated with the ν_2 Q branch of CO_2. A coupling of photochemical and radiative transfer theory yields an average mole fraction above the 110 mbar level of ƒCO_2 = 1.5 ± ^(1.5)_(0.8) x 10^(-9), with most of the uncertainty being due to imprecise knowledge of the vertical distribution. CO_2 is found to be in a steady state, with its abundance being regulated principally by the ∼72 K cold trap near the tropopause and secondarily by the rate at which water-bearing meteoritic material enters the top of the atmosphere. An influx of water about 0.4 times that at the top of the terrestrial atmosphere is consistent with a combination of the observed CO_2 abundance and a steady state CO mole fraction of 1.1×10^(−4); the theoretical value for CO is close to the value observed by Lutz et al. (1983), although there are large margins for error in both numbers. If steady state conditions for CO prevail, little information is available regarding the evolution of Titan's atmosphere