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  • 1
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    Validation of the Aura Microwave Limb Sounder HNO3 Measurements (2008)
    American Geophysical Union
    Details
    Publication Date: 2017-04-03
    Description: We assess the quality of the version 2.2 (v2.2) HNO3 measurements from the Microwave Limb Sounder (MLS) on the Earth Observing System Aura satellite. The MLS HNO3 product has been greatly improved over that in the previous version (v1.5), with smoother profiles, much more realistic behavior at the lowest retrieval levels, and correction of a high bias caused by an error in one of the spectroscopy files used in v1.5 processing. The v2.2 HNO3 data are scientifically useful over the range 215 to 3.2 hPa, with single-profile precision of 0.7 ppbv throughout. Vertical resolution is 3–4 km in the upper troposphere and lower stratosphere, degrading to 5 km in the middle and upper stratosphere. The impact of various sources of systematic uncertainty has been quantified through a comprehensive set of retrieval simulations. In aggregate, systematic uncertainties are estimated to induce in the v2.2 HNO3 measurements biases that vary with altitude between ±0.5 and ±2 ppbv and multiplicative errors of ±5–15% throughout the stratosphere, rising to ±30% at 215 hPa. Consistent with this uncertainty analysis, comparisons with correlative data sets show that relative to HNO3 measurements from ground-based, balloon-borne, and satellite instruments operating in both the infrared and microwave regions of the spectrum, MLS v2.2 HNO3 mixing ratios are uniformly low by 10–30% throughout most of the stratosphere. Comparisons with in situ measurements made from the DC-8 and WB-57 aircraft in the upper troposphere and lowermost stratosphere indicate that the MLS HNO3 values are low in this region as well, but are useful for scientific studies (with appropriate averaging).
    Description: Published
    Description: D24S40
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: JCR Journal
    Description: reserved
    Keywords: satellite validation ; stratospheric HNO3 ; 01. Atmosphere::01.01. Atmosphere::01.01.01. Composition and Structure
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Validation of Aura Microwave Limb Sounder Ozone by ozonesonde and Lidar Measurements (2007)
    In:  EPIC3Journal of Geophysical Research, 112, D24S34
    Details
    Publication Date: 2019-12-03
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 3
    Electronic Resource
    Electronic Resource
    Microwave spectra, density functional theory calculations and molecular structure of acetylenemethyldioxorhenium (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 7891-7900 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The molecular structure for acetylenemethyldioxorhenium, (C2H2)(CH3)ReO2, was obtained by measuring and analyzing the rotational spectra for 14 isotopomers. This appears to be the first gas-phase measurement for a rhenium metallacyclopropene, and the first structural data on this compound. This complex is closely related to reaction intermediates in methyltrioxorhenium and osmium tetroxide catalyzed oxidation reactions, which are important in industrial chemical production and syntheses of chiral products. The microwave spectra were measured in the 4–11 GHz range using a Flygare–Balle-type pulsed-beam microwave spectrometer. The structural parameters obtained using the 42 measured rotational constants are in very good agreement with results from the new density functional theory calculations. The structure of the acetylene ligand is modified through interaction with the metal atom, and exhibits partial sp2 hybridization in the complex. The C–C bond length is increased by 0.09 Å to 1.29 Å. The H–C–C interbond angles are reduced from 180° to 146°, and 147°. The measured rhenium, methyl–carbon bond length is 2.116(2) Å, and rhenium–acetylene carbon bond lengths are 2.043(2) Å and 2.067(2) Å. Large quadrupole splitting patterns arising from the two rhenium isotopes [χcc(185 Re)=812.62 MHz, and χcc(187 Re)=769.023 MHz], with large off-diagonal components [|χab(185 Re)|=725.40 MHz, and (|χab(187 Re)|=686.384 MHz] caused some initial difficulty in assigning transitions. When the assignments and analysis were completed, the systematic changes in the measured quadrupole coupling tensor components due to rotations of the principal inertial axes on isotopic substitution were obtained, and helped to confirm assignments for the various isotopomers. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1315611
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  • 4
    Electronic Resource
    Electronic Resource
    Microwave measurements of rhenium quadrupole coupling in cyclopentadienyl rhenium tricarbonyl (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 8878-8883 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Microwave measurements of rotational transitions for cyclopentadienyl rhenium tricarbonyl were performed in the gas phase using pulsed beam Fourier transform microwave spectroscopy. One hundred and sixty five transitions were assigned to two isotopomers of rhenium. The location of the rhenium atom near the center of mass produced significant overlap between the spectra of the two isotopomers. The data were accurately fit using a symmetric top, rigid rotor Hamiltonian that included nuclear quadrupole coupling and centrifugal distortion constants. The rotational constants obtained were B(187Re) = 724.9794(2), B(185Re) = 724.9795(2). The quadrupole coupling constants obtained were eQq(187Re) = 614.464(12) and eQq(185Re) = 649.273(14) MHz. The successful fitting of the measured spectra to a symmetric top Hamiltonian indicates that the cyclopentadienyl group retains C5v symmetry, and the Re(CO)3 group C3v symmetry in the gas phase. The measured rotational constants are in reasonable agreement with those calculated from the structural parameters obtained in the earlier x-ray work. The Re quadrupole coupling constants obtained are compared with values for other complexes. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.476334
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  • 5
    Electronic Resource
    Electronic Resource
    Measurements of the structure of methyltrioxorhenium using microwave spectroscopy (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 2187-2192 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rotational spectra for six isotopomers of methyltrioxorhenium (MTO) were measured in the 6–14 GHz range using a Flygare–Balle-type pulsed-beam microwave spectrometer. The measured transition frequencies were analyzed to obtain rotational constants and quadrupole coupling strengths. Rotational constants from the new measurements were used, along with previous results for the normal and 13C isotopomers, to determine the complete, three-dimensional structure for MTO. The bond lengths obtained are r(Re–C)=2.074(4) Å, r(Re–O)=1.703(2) Å, and r(C–H)=1.088(7) Å. The interbond angles are (angle)Re–C–H=108.9(2)° and (angle)C–Re–O=106.4(4)°. This complex appears to have C3v symmetry in the gas phase, unlike the solid-state structure. Structural parameters are compared with neutron-diffraction, electron-diffraction, and density functional theory results. Spectra for the asymmetric-top isotopomers were much more difficult to analyze due to effects of off-diagonal quadrupole coupling terms and possible internal rotation. The Re quadrupole coupling strength is increased by 1.4% for CD3ReO3 compared with CH3ReO3, illustrating a secondary isotope effect. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474618
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  • 6
    Electronic Resource
    Electronic Resource
    Determination of structural parameters for the half-sandwich compounds cyclopentadienyl thallium and cyclopentadienyl indium and indium quadrupole coupling for cyclopentadienyl indium using microwave spectroscopy (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 3766-3773 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Microwave rotational transitions for J′←J=2←1 and 3←2 were measured in the 7–11 GHz range for three isotopomers of (C5H5)In. Similar transitions (up to J′←J=5←4) for eight isotopomers of (C5H5)Tl were measured in the 5–15 GHz range. The rotational constants of the most abundant isotopomers are B(Cp 203Tl)=1467.9730(11) MHz, B(Cp 205Tl) =1465.0723(14) MHz, B(Cp 113In)=1809.9785(30) MHz, and B(Cp 115In)=1800.8199(18) MHz (Cp=C5H5). The quadrupole coupling strengths for the indium compounds are eQq(Cp 113In)=−118.397(69) MHz and eQq(Cp 115In)=−119.981(31) MHz. Spectra for single-substitution 13C isotopomers were seen in natural abundance. Deuterated samples of CpTl were prepared to obtain spectra for deuterium-substituted isotopomers. Analysis of the spectra allowed the determination of the following structural parameters; for (C5H5)Tl, r(Tl–C5)=2.413(3) Å, r(C–C)=1.421(10) Å, r(C–H)=1.082(9) Å and (angle)C5–H=0.9(2)° (C5 represents the planar, 5-carbon ring of C5H5), and for (C5H5)In, r(In–C5)=2.314(4) Å and r(C–C)=1.426(6) Å. A Kraitchman analysis was performed on the available isotopomers for comparison of r0 and rs values. Both structural analyses indicate that the hydrogen atoms in (C5H5)Tl are bent slightly out of the carbon plane away from the coordinated metal atom. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474734
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  • 7
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    Validation of the Aura Microwave Limb Sounder Temperature and Geopotential Height Measurements (2008)
    AGU (American Geophysical Union)
    In:  Journal of Geophysical Research: Atmospheres, 113 . D15S11.
    Details
    Publication Date: 2018-02-06
    Description: Global satellite observations of temperature and geopotential height (GPH) from the Microwave Limb Sounder (MLS) on the EOS Aura spacecraft are discussed. The precision, resolution, and accuracy of the data produced by the MLS version 2.2 processing algorithms are quantified, and recommendations for data screening are made. Temperature precision is 1 K or better from 316 hPa to 3.16 hPa, degrading to ∼3 K at 0.001 hPa. The vertical resolution is 3 km at 31.6 hPa, degrading to 6 km at 316 hPa and to ∼13 km at 0.001 hPa. Comparisons with analyses (Goddard Earth Observing System version 5.0.1 (GEOS-5), European Centre for Medium-range Weather Forecasts (ECMWF), Met Office (MetO)) and other observations (CHAllenging Minisatellite Payload (CHAMP), Atmospheric Infrared Sounder/Advanced Microwave Sounder Unit (AIRS/AMSU), Sounding of the Atmosphere using Broadband Radiometry (SABER), Halogen Occultation Experiment (HALOE), Atmospheric Chemistry Experiment (ACE), radiosondes) indicate that MLS temperature has persistent, pressure-dependent biases which are between −2.5 K and +1 K between 316 hPa and 10 hPa. The 100-hPa MLS v2.2 GPH surface has a bias of ∼150 m relative to the GEOS-5 values. These biases are compared to modeled systematic uncertainties. GPH biases relative to correlative measurements generally increase with height owing to an overall cold bias in MLS temperature relative to correlative temperature measurements in the upper stratosphere and mesosphere.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1029/2007JD008783
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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