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Heath, D. F.

Publications and source records attributed to Heath, D. F..

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

The Nimbus-4 backscatter ultraviolet /BUV/ atmospheric ozone experiment Two years' operation.

Review of some of the procedures and results of the double monochromator and colinear photometer Nimbus-4 satellite experiment that measures ultraviolet terrestrial radiance, Lambert reflectivity of the lower boundary of the scattering atmosphere, and extraterrestrial solar irradiance. The experiment has produced nearly three years of almost continuous data which are being used to infer the high-level ozone distribution and total ozone on a global basis. The high-level ozone data have been verified by independent coincident rocket ozone soundings, and the total ozone values show good agreement with Dobson spectrophotometer determinations. An increase has been observed in equatorial radiance at 2550 A relative to 2900 A, which seems to indicate that the amount of ozone in the upper stratosphere is related to the eleven-year solar cycle.

Heath, D. F.↗
NASA NTRS1973

Variations in the stratospheric ozone field inferred from Nimbus satellite observations.

The ultraviolet earth radiance data from the backscatter ultraviolet experiment on Nimbus 4 have been inverted to infer ozone profiles using a single Rayleigh scattering model. Two methods of solution give essentially the same results. Comparison of these profiles with simultaneous rocket sounding data shows satisfactory agreement at low and middle latitudes. Vertical cross-sections of ozone mixing ratio along the orbital tracks indicate that while the gross characteristics of the ozone field above 10 mb are under photochemical control, the influence of atmospheric motions can be found up to the 4 mb level.

Krueger, A. J.↗
NASA NTRS1972

An extreme ultraviolet photometer for solar observations from the Atmosphere Explorer satellites

A broadband photometer experiment is being fabricated for the Atmosphere Explorer C, D and E missions to record the solar irradiance in the 40 to 1250 A region with seven distinct passbands. The experiment consists principally of four spinal electron multipliers located behind a moving eight position filter wheel. Six metallic filters are used to spectrally isolate the solar irradiance. In addition three Al2O3 diodes, two with filters, are being used to record the solar irradiance over the range of orbital altitudes from perigee through apogee. A principal goal of the experiment will be to measure time dependence of the solar irradiance with respect to a storage ring synchrotron light source which has been calibrated in terms of the best currently available standards of irradiance.

Heath, D. F.↗
NASA NTRS1972

Observations of the sun, an ultraviolet variable star

The uncertainty as to whether or not the sun is a variable star in that region of the ultraviolet which is absorbed in the mesosphere and stratosphere led to an experiment with acronym MUSE, Monitor of Ultraviolet Solar Energy. The experiment was first flown on an Aerobee rocket in August 1966 and subsequently on Nimbus 3 and 4 in April 1969 and April 1970 respectively. The basic philosophy behind the design of the experiment was to provide an instrument which would not require a solar pointing mechanism and at the same time would be capable of high radiometric accuracy for long periods in space.

Heath, D. F.↗
NASA NTRS1972

Observations on degradation of UV systems on Nimbus spacecraft

Broad band photometer experiments in the 1200 to 3000 A have been operating on Nimbus 3 and 4 since April 1969 for the purpose of determining the nature of variations in the UV solar irradiance. An Ebert-Fastie double monochromator has been measuring the solar irradiance and earth radiance from 2500 to 3400 A for the determination of global atmospheric ozone distributions since April 1970. From prelaunch testing and an evaluation of the flight data it is concluded that the principal source of degradation is probably the spacecraft. The degradation produces a characteristic signal loss and change in angular response of the system which might be explained by micron sized droplets becoming a permanent residue under the influence of solar UV radiation.

Heath, D. F.↗
NASA NTRS1972

Space observations of the variability of solar irradiance in the near and far ultraviolet

Satellite observations of the ultraviolet solar irradiance in selected wavelength bands between 1200 and 3000 a were made continuously by photometers consisting of broad-band sensors operated on Numbus 3 and 4 which were launched in April 1969 and 1970. In addition, spectrophotometer measurements of the solar irradiance were made with a dispersive instrument at 12 selected wavelengths from 2550 to 3400 a with a 10 a bandpass on Nimbus 4. Variations of the solar irradiance associated with the solar rotational period were observed since the launch of Nimbus 3. These variations are apparently associated with two source regions separated by about 180 deg in solar longitude. The change in irradiance with solar rotation was found to increase with decreasing wavelengths. Different types of the observed variations in uv solar irradiance can be classified in accordance with characteristics times, e.g. in the order of increasing periods as follows: (1)flare associated enhancements (2) 27-day variations due to solar rotation; (3) a possible biennial effect; and (4) long term variations associated with the 11-year solar cycle.

Heath, D. F.↗
NASA NTRS1972

Variations in the stratospheric ozone field inferred from Nimbus satellite observations

The ultraviolet earth radiance data from the Backscatter Ultraviolet Experiment on Nimbus 4 have been inverted to infer ozone profiles using a single Rayleigh scattering model. Two methods of solution give essentially the same results. Comparisons of these profiles with simultaneous rocket sounding data shows satisfactory agreement at low and middle latitudes. Vertical cross sections of ozone mixing ratio along the orbital tracks indicate that while the gross characteristics of the ozone field above 10 mb are under photochemical control, the influence of atmospheric motions can be found up to the 4 mb level.

Krueger, A. J.↗
NASA NTRS1971

Estimation of total ozone from satellite measurements of backscattered ultraviolet earth radiance.

Total ozone is estimated from Nimbus IV satellite measurements of the attenuation of backscattered radiances at wavelengths between 3100 and 3400 A. A measurement of the backscattered radiance at 3800 A, outside the ozone absorption band, is used to determine an equivalent Lambert albedo for the cloud-ground-haze surface viewed by the instrument. The measured relative attenuation at two wavelengths is compared with such values precomputed for a series of standard ozone profiles and corrected for the equivalent Lambert albedo. Total ozone is obtained by interpolation. Two alternative methods are used to assign an equivalent Lambert albedo at the absorbing wavelengths. Total ozone values estimated by these methods are compared with the Dobson (ground-truth) data by linear regression. The available evidence suggests that the true standard error of the satellite data may be 0.015 atm-cm or less for solar zenith angles smaller than 60 deg.

Mateer, C. L.↗