Engineering topics

Smith, H. J. P.

Publications and source records attributed to Smith, H. J. P..

6 records

NASA NTRS1999

Mesospheric Odd Nitrogen Enhancements During Relativistic Electron Precipitation Events

The behavior of mesospheric odd nitrogen species during and following relativistic and diffuse auroral precipitation events is simulated, Below 75 km nitric oxide is enhanced in proportion to the ion pair production function associated with the electron precipitation and the length of the event. Nitrogen dioxide and nitric acid are also enhanced. At 65 km the percentage of odd nitrogen for N is 0.1%, HNO3 is 1.6%, NO2 is 15%, and NO is 83.3%. Between 75 and 85 km NO is depleted during particle events due to the faster destruction of NO by N relative to the production of NO by N reacting with O2. Recovery of NO depends on transport from the lower thermosphere, where NO is produced in abundant amounts during particle events.

Aikin, A. C.↗

NASA NTRS1989

An intercomparison of mesospheric ozone profiles determined by the UVSP and SAGE II solar occultation experiments

A comparison is made of individual UVSP and SAGE II mesospheric ozone profiles between 50 and 70 km altitude as determined by the solar occultation technique. The generally good agreement between the two data sets below about 57 km leads to the conclusion that they may be considered as complementary, thus extending the effective altitude range of both. Comparison of the long-term ozone trend at 55.5 km shows a systematic difference of a few percent between the two measurements.

Aikin, A. C.↗

NASA NTRS1986

Mesospheric ozone changes associated with 27-day solar ultraviolet flux variations

Solar ultraviolet flux changes associated with the 27-day solar rotational period cause corresponding variations in mesospheric ozone near the maximum of the 11-year sunspot cycle. This statement is based on a correlation and spectral analysis of ozone mixing ratios, deduced from Solar Mesospheric explorer satellite-based measurements of 1.27-micron O2 airglow emission and solar flux observations made from the same spacecraft in 1982. With the Lyman-alpha flux taken as an indicator of solar ultraviolet variability, spectral analysis shows a primary period of 27.1 days with a secondary period of 13.5 days. The 27.1-day period is observed in the ozone mixing ratio data together with other periods, including 13.5 days. Both a classical statistical analysis and a time series treatment show that, for 244 days, there is a correlation between ozone and solar flux near 50 km and between 65 and 70 km. Calculations predict a positive correlation over the entire mesosphere if there is no change in temperature accompanying the solar flux. Lack of correlation is temperature induced.

Aikin, A. C.↗

NASA NTRS1984

Equatorial ozone profiles from the Solar Maximum Mission - A comparison with theory

The UV spectrometer polarimeter on the Solar Maximum Mission has been utilized to measure mesospheric O3 altitude profiles by the technique of solar occultation. Sunset data are presented for 1980, during the fall equinoctal period within + or - 20 deg of the geographic equator. Mean O3 concentrations are (40, 16, 5.5, and 1.5) x 10 to the 9th/cu cm at 50, 55, 60, and 65 km, respectively. Some profiles exhibit altitude structure which is wavelike. The mean O3 profile is fit best with the results of a time-dependent model if the assumed water-vapor mixing ratio employed varies from 6 ppm at 65 km.

Aikin, A. C.↗

NASA NTRS1983

SMM-UVSP ozone profile inversion programs

The documentation and user manual for the software used to invert the UVSP aeronomy data taken by the SMM are provided. The programs are described together with their interfaces and what inputs are required from the user.

Smith, H. J. P.↗

NASA NTRS1982

Atmospheric ozone determination by solar occultation using the UV spectrometer on the Solar Maximum Mission

The UV spectrometer polarimeter instrument on the Solar Maximum Mission spacecraft has been used to measure ozone in the 53-75 km altitude interval by the technique of solar occultation. A 1 x 180 arcsec entrance aperture spectrometer with 0.04-A spectral resolution was employed. Resulting high-quality data are reduced by expressing measured UV attenuation as a Volterra integral equation. Solution of the equation is accomplished by expressing the integral in terms of a series representing the sum of ozone densities contained in concentric shells through tangent points separated by specified altitude increments. Sample ozone vs altitude profiles are presented for the equatorial region. These data show reproducibility to better than 10%. The density at 60 km is 7.3 + or - 0.15 x 10 to the 9th/cu cm for 2.5 deg latitude and longitudes between 81 and 105 deg west in September 1980. Density vs altitude profile exhibits changes in slope between 50 and 75 km.

Aikin, A. C.↗