Search NASA⌕ Search

Engineering topics

Watson, A. J.

Publications and source records attributed to Watson, A. J..

6 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

A deliberate tracer experiment in Santa Monica Basin

A tracer technique was developed for measurements of diffusion across oceanic density strata using SF6 and perfluorodecalin (PFD) tracers in the Santa Monica Basin. Fifty days after injection, the tracers were found to have mixed along the isopycnal surface to nearly every part of the basin. The diapycnal spreading of the tracer distributions yielded an apparent eddy diffusivity of 0.33 + or - 0.08 sq cm/s at the ambient density gradient of 4.0 + or - 0.5 x 10 to the -9th g/cm to the 4th.

Ledwell, J. R.↗
NASA NTRS1984

Temperatures in a runaway greenhouse on the evolving Venus Implications for water loss

Some aspects of the temperature structure of a runaway greenhouse on Venus are examined using one-dimensional radiative transfer techniques. It is found that there generally is a region high in the atmosphere where condensation and cloud formation can occur, while deep in the atmosphere the gas is strongly unsaturated with respect to water vapor. The necessity of including clouds introduces considerably uncertainty into the calculation of surface temperatures. Under reasonable assumptions concerning the clouds, temperatures deep in the atmosphere are high enough to produce a plastic or even molten surface, which may significantly ease the problem of explaining the loss of oxygen.

Watson, A. J.↗
NASA NTRS1982

Venus was wet - A measurement of the ratio of deuterium to hydrogen

The deuterium-hydrogen abundance ratio in the Venus atmosphere was measured while the inlets to the Pioneer Venus large probe mass spectrometer were coated with sulfuric acid from Venus' clouds. The ratio is 0.016 + or - 0.002. The hundredfold enrichment of deuterium means that at least 0.3 percent of a terrestrial ocean was outgassed on Venus, but is consistent with a much greater production.

Donahue, T. M.↗
NASA NTRS1981

The dynamics of a rapidly escaping atmosphere - Applications to the evolution of earth and Venus

A simple model for the rapid escape of a hydrogen thermosphere is presented in order to establish the energy-limited flux of escaping particles. The model assumes that the atmosphere is tightly bound by gravity at the lower boundary, that all the EUV is absorbed in a narrow region where the optical depth is unity, and that the main source of heating is solar EUV. The flux is limited by the amount of EUV energy absorbed, which is in turn controlled by the radial extent of the thermosphere. It is found that, regardless of the amount of hydrogen in the thermosphere, the low temperatures which accompany rapid escape limit its extent and thus constrain the flux. The results are applied to the earth and Venus, showing that the escape of hydrogen from these planets would have been energy-limiting if their primordial atmospheres contained total hydrogen mixing ratios exceeding only a few percent. This conclusion places a constraint on the theory of the origin and evolution of the planets.

Watson, A. J.↗
NASA NTRS1979

Oxides of nitrogen and the clouds of Venus

Nitric oxide may be produced in the atmosphere of Venus by lightning storms in the clouds. The paper suggests that the odd nitrogen thus formed may play an important part in the chemistry of the clouds. Specifically, production rates for NO2 in the limiting case of high NO concentrations are estimated. If the NO density is high, it is suggested that NO2 may catalyse the production of sulfuric acid aerosol from sulfur dioxide and water vapor, and may also form nitrogen-sulfur compounds such as nitrosyl sulfuric acid, NOHSO4. The large partricles seen by the Pioneer Venus sounder probe may contain considerable quantities of NOHSO4. If this is the case, odd nitrogen must be present in the atmosphere in at least a parts-per-million mixing ratio.

Watson, A. J.↗