Search NASA⌕ Search

Engineering topics

Drayson, S. R.

Publications and source records attributed to Drayson, S. R..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

The Halogen Occultation Experiment

The Halogen Occultation Experiment (HALOE) uses solar occultation to measure vertical profiles of O3, HCl, HF, CH4, H2O, NO, NO2, aerosol extinction, and temperature versus pressure with an instantaneous vertical field of view of 1.6 km at the earth limb. Latitudinal coverage is from 80 deg S to 80 deg N over the course of 1 year and includes extensive observations of the Antarctic region during spring. The altitude range of the measurements extends from about 15 km to about 60-130 km, depending on channel. Experiment operations have been essentially flawless, and all performance criteria either meet or exceed specifications. Internal data consistency checks, comparisons with correlative measurements, and qualitative comparisons with 1985 atmospheric trace molecule spectroscopy (ATMOS) results are in good agreement. Examples of pressure versus latitude cross sections and a global orthographic projection for the September 21 to October 15, 1992, period show the utility of CH4, HF, and H2O as tracers, the occurrence of dehydration in the Antarctic lower stratosphere, the presence of the water vapor hygropause in the tropics, evidence of Antarctic air in the tropics, the influence of Hadley tropical upwelling, and the first global distribution of HCl, HF, and NO throughout the stratosphere. Nitric oxide measurements extend through the lower thermosphere.

Russell, James M., III↗
NASA NTRS1993

Observations of aerosol by the HALOE experiment onboard UARS - A preliminary validation

The HALOE experiment measures vertical profiles of aerosol extinction at five infrared wavelengths. Four of these observations are obtained using a combination of gas filter and broadband radiometer measurements in bands of HF, HCl, CH4, and NO centered at wavelengths of 2.45, 3.40, 3.45, and 5.26 microns, respectively. The fifth is obtained using broadband radiometer measurements of CO2 transmission at 2.79 microns. Error analysis shows that the random extinction uncertainties are generally less than 10 percent in the aerosol layer, increasing to over 20 percent at the profile tops. HALOE spectral extinction measurements are shown to be consistent with predicted spectral extinction for stratospheric sulfate aerosol. Profile comparisons between HALOE and independent sources result in generally good agreement in the shape and magnitude of peak extinction and the altitude where the peak extinction occurs. In addition, global aerosol distributions obtained from the data are consistent with expected aerosol morphology. Although the validation is preliminary, the HALOE aerosol data appear to be of excellent quality and to accurately represent optical characteristics and distribution of the aerosols.

Hervig, Mark E.↗
NASA NTRS1993

HALOE Antarctic observations in the spring of 1991

HALOE observations of O3, CH4, HF, H2O, NO, NO2, and HCl collected during the October 1991 Antarctic spring period are reported. The data show a constant CH4 mixing ratio of about 0.25 ppmv for the altitude range from 65 km down to about 25 km at the position of minimum wind speed in the vortex: i.e., the vortex center, and depressions in pressure versus longitude contours of NO, NO2, HF, and HCl in this same region. Water vapor, HF, and HCl enhancement are also observed in the vortex center region above about 25 km. Between 10 and 20 km, the expected mixing ratio signatures exist within the vortex, i.e., low ozone and dehydration. The water vapor increased by 50 percent, and the ozone level doubled inside the vortex between October 11 and 24 in the 15-20 km layer. These changes imply a time constant for recovery from ozone hole conditions of 19 and 30 days for O3 and H2O, respectively. The data further show the presence of air inside the vortex between 3 and 30 mb which has mixing ratios characteristic of midlatitudes.

Russell, James M., III↗
NASA NTRS1991

Rapid computation of the radiative absorption rate in the nu3 mode of mesospheric and lower thermospheric ozone

An algorithm has been developed to calculate rapidly and accurately the rate at which the ozone nu3 fundamental band absorbs IR radiation in the terrestrial upper mesosphere and lower thermosphere. Accurate knowledge of this rate is essential for studies of non-LTE processes in ozone and for estimating ozone concentrations from measurements of non-LTE IR emission from the middle atmosphere. In the algorithm, the 1252 ozone nu3 fundamental lines that govern radiative absorption are divided into 13 groups according to line strength. The absorption rate due to a single line representative of the mean line strength of each group is then calculated. The total absorption rate is obtained by multiplying the absorption rate for each mean line by the total number of lines within each group and adding the resultant products for all 13 groups.

Mlynczak, Martin G.↗
NASA NTRS1985

Radiative processes

Solar radiation and the processes that control its deposition in the Earth atmosphere are considered. The published data obtained since 1978 define a reference solar spectral irradiance for use in atmospheric chemical and dynamical studies, while long term satellite measurements are now providing information on variations in the output of the Sun over a range of time scales. As concerns absorption of solar radiation in the atmosphere, new cross section data for molecular oxygen and ozone are now available. Line-by-line calculations used to predict infrared flux divergences, both as regards assumptions made in radiative transfer calculations and in the spectroscopic parameters used as inputs are examined. Also examined are the influence of radiative processes on planetary scale wave activity, photochemical acceleration of radiative damping, and the breakdown of local thermodynamic equilibrium at mesospheric altitudes.

Frederick, J. E.↗
NASA NTRS1984

Validation of nitrogen dioxide results measured by the limb infrared monitor of the stratosphere (LIMS) experiment on NIMBUS 7

The validation of results from the nitrogen dioxide channel and the quality of the data are examined in connection with the LIMS experiment which ran from late October 1978 to late May 1979. Factors studied include: channel characteristics, experiment errors due to instrument and spacecraft effects, predicted and measured precision, predicted accuracy, and comparisons with correlative measurements made in a series of balloon underflights. Features such as profile shape and slope of the mixing ratio altitude distribution are in good agreement. The LIMS data also fall within the range of previous mixing ratio measurements and are consistent with model estimates. The calculated on-orbit precision is about 0.3 ppbv and the estimated accuracy from simulations is about 2 ppbv over the 3-10-mbar range. Accuracy is less at higher and lower pressure levels. These results provide the first day-night set of nitrogen dioxide measurements from space.

Russell, J. M., III↗
NASA NTRS1984

Validation of water vapor results measured by the Limb Infrared Monitor of the Stratosphere experiment on Nimbus 7

In the LIMS experiment using thermal IR limb scanning to sound the composition and structure of the upper atmosphere, one of the LIMS channels was spectrally centered at 6.9 micrometers to measure the vertical profile and global distribution of stratospheric water vapor. This channel's characteristics, the data from it, and the steps taken to validate results are described. The mean difference between the LIMS measurements and data from 13 balloon underflights is about 0.6 ppmv with LIMS mixing ratios biased high; this difference is of about the same order as estimated LIMS accuracy and less than the sum of the errors for LIMS and the balloon techniques. In-orbit precision is 0.2-0.3 ppmv and accuracy is estimated at 20-30 percent from 50 mbar to the stratopause. An unexplained diurnal variation exists in the vertical profile data which is largest at the 1-mbar level and virtually nonexistent at 10 mbar; day values are higher than night. More confidence is placed in zonal mean distributions averaged over several days than in single profiles. A zonal mean pressure-latitude cross section is described for January 5-9, 1979.

Russell, J. M., III↗
NASA NTRS1984

Spectroscopy and transmittances for the LIMS experiment

The Limb Infrared Monitor of the Stratosphere (LIMS) instrument on the Nimbus 7 spacecraft sensed limb emission profiles for 7 months, starting in October 1979. Vertical temperature profiles are inferred from measurements in two CO2 channels, and constituent profiles are obtained form the O3, HNO3, NO2, and water vapor channels. The line parameters used to calculate transmittances in the retrieval algorithm are presented. Their adequacy for LIMS and for other applications are assessed, and recommendations for future investigations are outlined.

Drayson, S. R.↗
NASA NTRS1979

Pressure sensing of the atmosphere by solar occultation using broadband CO2 absorption

A technique for obtaining pressure at the tangent point in an IR solar occulation experiment is described. By measuring IR absorption in bands of atmospheric CO2 (e.g., 2.0, 2.7, or 4.3 microns), mean pressure values for each tangent point layer (vertical thickness 2 km or less) of the atmosphere can be obtained with rms errors of less than 3%. The simultaneous retrieval of pressure and gas concentration in a remote-sensing experiment will increase the accuracy of inverted gas concentrations and minimize the dependence of the experiment on pressure or mass path error resulting from use of climatological pressure data, satellite ephemeris, and instrument pointing accuracy.

Park, J. H.↗
NASA NTRS1978

Pressure sensing of the atmosphere by solar occultation - An application to remote sensing of atmospheric minor gases

The simultaneous inference of pressure and gas concentration in a remote-sensing experiment will increase the accuracy of inverted gas concentrations and minimize the dependence of the experiment on pressure or mass-path error resulting from use of climatological pressure data, satellite ephemeris, and instrument pointing accuracy. A technique for obtaining tangent-point pressure information needed for inversion of gas concentration in an IR solar occultation experiment is described. By measuring IR absorption in bands of atmospheric CO2 (e.g., 2.0, 2.7, or 4.3 microns) pressure values for each layer (2 km or less in the vertical) of the atmosphere can be obtained with rms errors of less than 3%.

Park, J. H.↗
NASA NTRS1976

Rapid computation of the Voigt profile

Computational procedures for evaluating the Voigt profile function with maximum relative error about one part in ten thousand are discussed. The computational region is split up into four subregions, each of which is worked on with a different computational technique (Chebyshev expansion, continued fraction expansion, 2-point Gauss-Hermite quadrature, and 4-point Gauss-Hermite quadrature). The overall procedure is designed for line-by-line transmittance calculations and similar applications, and an efficient FORTRAN IV subprogram is outlined in an appendix.

Drayson, S. R.↗
NASA NTRS1975

Transmissivity of carbon monoxide in the 2.3 microns band region

Line strengths and self and nitrogen broadened half-widths have been determined from high resolution spectroscopic measurements of selected lines in the 2.3 micrometer band region of CO. The CO 0-2 total band strength is estimated to be 2.086 + or - 0.146 cm/1 (ATM-cm)/1 STP which is higher than most previously reported values. The line half-widths are also generally higher than those in the literature.

Drayson, S. R.↗
NASA NTRS1973

A listing of wavenumbers and intensities of carbon dioxide absorption lines between 12 and 20 micrometers

A listing is given of the wavenumber, intensities at 300, 275, 250, 225, 200 and 175 k and energy of the lower state of CO2 absorption lines between 12 and 20 microns. They are ordered by wave-number and include 19 bands of C-12(O-16)2, 4 bands of C-13(O-16)2, 2 bands of C-12-O-16-O-18 and 1 band of C-12-O-16-O-17. The vibrational and rotational constants and the band intensities used to calculate the line parameters are tabulated.

Drayson, S. R.↗
NASA NTRS1973

The inference of atmospheric ozone using satellite nadir measurements in the 1042/cm band

A description and detailed analysis of a technique for inferring atmospheric ozone information from satellite nadir measurements in the 1042 cm band are presented. A method is formulated for computing the emission from the lower boundary under the satellite which circumvents the difficult analytical problems caused by the presence of atmospheric clouds and the watervapor continuum absorption. The inversion equations are expanded in terms of the eigenvectors and eigenvalues of a least-squares-solution matrix, and an analysis is performed to determine the information content of the radiance measurements. Under favorable conditions there are only two pieces of independent information available from the measurements: (1) the total ozone and (2) the altitude of the primary maximum in the ozone profile.

Russell, J. M., III↗
NASA NTRS1973

Transmissivity of carbon monoxide

The line strengths and self- and nitrogen-broadened half widths for selected lines of the 4.6 micron fundamental band of carbon monoxide were determined. The band strength determined at stp. is higher than previously reported measurements. The half widths agree well with other measurements and calculations.

Drayson, S. R.↗
NASA NTRS1972

The inference of atmospheric ozone using satellite horizon measurements in the 1042 per cm band.

Description of a method for inferring atmospheric ozone information using infrared horizon radiance measurements in the 1042 per cm band. An analysis based on this method proves the feasibility of the horizon experiment for determining ozone information and shows that the ozone partial pressure can be determined in the altitude range from 50 down to 25 km. A comprehensive error study is conducted which considers effects of individual errors as well as the effect of all error sources acting simultaneously. The results show that in the absence of a temperature profile bias error, it should be possible to determine the ozone partial pressure to within an rms value of 15 to 20%. It may be possible to reduce this rms error to 5% by smoothing the solution profile. These results would be seriously degraded by an atmospheric temperature bias error of only 3 K; thus, great care should be taken to minimize this source of error in an experiment. It is probable, in view of recent technological developments, that these errors will be much smaller in future flight experiments and the altitude range will widen to include from about 60 km down to the tropopause region.

Russell, J. M., III↗