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James, T. C.

Publications and source records attributed to James, T. C..

10 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

The cryogenic limb array etalon spectrometer (CLAES) on UARS - Experiment description and performance

The design and the performance of the cryogenic limb array spectrometer (CLAES) aboard the NASA Upper Atmosphere Research Satellite are discussed. CLAES measures altitude profiles of temperature, pressure, O3, H2O, CH4, N2O, NO, NO2, N2O5, HNO3, ClONO2, HCl, CFC 11, CFC 12, and aerosol absorption coefficients for atmospheric layer between 10 and 60 km. Examples of atmospheric spectral emission profiles for a number of constituents are presented as well as responsivity and noise parameters.

Roche, A. E.↗
NASA NTRS1989

Model calculations of spectral transmission for the CLAES etalons

This paper describes models for calculating spectral transmission for the Cryogenic-Limb-Array-Etalon-Spectrometer (CLAES) etalons. These models involve a convolution of the Airy function for a given thickness with the distribution of surface thicknesses, the effect of absorption in the substrate, and the field of view broadening as a function of etalon tilt angle. A comparison of model calculations with experimental transmission data for CLAES etalons centered at 3.52, 5.72, 8.0, and 11.86 microns showed that these models are able to provide a good description of the CLAES etalons.

James, T. C.↗
NASA NTRS1988

Concept for Geostationary Experimental Temperature and Moisture Sounder (GETMS)

The concept of the Geostationary Experimental Temperature and Moisture Sounder (GETMS) is described, with special attention given to the system constraints and its performance characteristics. The GETMS concept supports operation in a high-resolution 'nominal experimental mode' that could achieve spectral resolution of the order 0.2/cm in the 4.2-micron region with signal/noise sufficient to achieve temperature profile retrievals with vertical resolution of the order 1 to 2 km and accuracy to 1 K or less. The concept includes a cryogenic module to provide cryogenic cooling of the focal plane. The GETMS functional diagram and diagrams of the GETMS spectrometer and of the cryogenics module are included.

Kumer, J. B.↗
NASA NTRS1986

CLAES blocker filter rejection requirements

Some details of the calculations of out-of-band spectral rejection requirements for the CLAES blocker filters are described. For a particular blocker centered within an etalon bandpass, the signal to be expected when a particular etalon transmission peak is centered at the central wavelength of the blocker filter is calculated. This signal is compared with the total signal arising from all other transmission peaks within the etalon bandpass and all of the radiation from the entire spectrum outside of the etalon bandpass. The results for a few of the blocker filters are listed, and the design goals are compared with theoretical design results.

James, T. C.↗
NASA NTRS1982

Non-LTE calculation of HCL earthlimb emission and implication for detection of HCl in the atmosphere

Calculation results are presented for the contribution of the non-Local Thermodynamic Equilibrium process of resonant scattering of sunlight in the 1-0 band of HCl to the earthlimb radiance, for the case of tangent altitudes from 20 to 90 km. It is established that the mechanism in question is a significant contributor to radiance at altitudes as low as 20 km, and that it becomes greater than the Local Thermodynamic Equilibrium contribution above 40 km. Attention is given to the prospects for detection of HCl at altitudes approaching 80 km, by means of the Cryogenic Limb Array Etalon Spectrometer scheduled for deployment by the NASA Upper Atmospheric Research Satellite.

Kumer, J. B.↗
NASA NTRS1971

Transition moments, Franck-Condon factors, and lifetimes of forbidden transitions - Calculation of the intensity of the Cameron system of CO.

Discussion of the factors affecting the intensity of forbidden transitions in diatomic molecules. It is shown that using Franck-Condon factors to predict relative band intensities is less reliable for forbidden transitions than it is for allowed transitions. The intensity of the 0,0 and 1,0 bands of the a super 3 pi-super 1 sigma Cameron system of CO are calculated using perturbation theory. The intensity arises from spin-orbit mixing of the A super 1 pi state with the a super 3 pi state. From the known spin-orbit coupling constant of the a super 1 pi state and the known intensity of the fourth positive A super 1 pi-super 1 sigma transition, the oscillator strengths of the 0,0 and 1,0 bands are calculated to be 1.63 x 10 to the minus 7th power and 1.99 x 10 to the minus 7th power. Lifetimes of various rotational levels are shown to range from 2.9 to several hundred milliseconds.-

James, T. C.↗