Engineering topics

Prinn, R. G.

Publications and source records attributed to Prinn, R. G..

At least 37 records · Page 2

NASA NTRS1979

Venus winds are zonal and retrograde below the clouds

Winds in the lower atmosphere of Venus, inferred from three-dimensional radio interferometric tracking of the descents of the Pioneer day and north probes, are predominantly easterly with speeds of about 1 M/sec near the surface, 50 at the bottom of the clouds, and more than 200 within the densest, middle cloud layer. Between about 25 and 55 km altitude the average flow was slanted equatorward, with superimposed wavelike motions and alternating layers of high and low shear

Counselman, C. C., III↗

NASA NTRS1978

Photochemistry and dynamics of the ozone layer

The paper presents a broad review of the photochemical and dynamic theories of the ozone layer. The two theories are combined into the MIT three-dimensional dynamic-chemical quasi-geostrophic model with 26 levels in the vertical spaced in logarithmic pressure coordinates between the ground and 72-km altitude. The chemical scheme incorporates the important odd nitrogen, odd hydrogen, and odd oxygen chemistry, but is simplified in the sense that it requires specification of the distributions of NO2, OH and HO2. The prognostic equations are the vorticity equation, the perturbation thermodynamic equation, and the global mean and perturbation continuity equations for ozone; diagnostic equations include the hydrostatic equation, the balance condition, and the mass continuity equation. The model is applied to the investigation of the impact of supersonic aircraft on the ozone layer.

Prinn, R. G.↗

NASA NTRS1977

Carbon monoxide on Jupiter and implications for atmospheric convection

A study of the equilibrium and disequilibrium thermochemistry of the recently discovered carbon monoxide on Jupiter suggests that the presence of this gas in the visible atmosphere is a direct result of very rapid upward mixing from levels in the deep atmosphere where the temperature is about 1100 K and where carbon monoxide is thermodynamically much more stable. As a consequence the observed carbon monoxide mixing ratio is a sensitive function of the vertical eddy mixing coefficient. We infer a value for this latter coefficient which is about three to four orders of magnitude greater than that in the earth's troposphere. This result directly supports existing structural and dynamical theories implying very rapid convection in the deep Jovian atmosphere, driven by an internal heat source.

Prinn, R. G.↗

NASA NTRS1977

Mars - Photodesorption from mineral surfaces and its effects on atmospheric stability

Kinetic constraints are employed to identify the reactive chemisorbed complexes, to describe the mechanism of UV-accelerated desorption from Fe (+2) on mineral surfaces, and to estimate the photodesorption rate on Mars. In particular, it is proposed that gases such as O2, CO2, CO, H2O and N2 undergo an adsorption-desorption process at octahedrally coordinated Fe (+2) surface sites to produce seven-coordinate transition-state complexes. The ligand field stabilization energy acquired by these complexes lies between 16 and 18 kcal per mole. Published photocatalysis data are used to assess the role of photodesorption in Martian atmospheric chemistry and stability.

Huguenin, R. L.↗

NASA NTRS1977

On the radiative damping of atmospheric waves

General expressions for computing time constants for radiative decay of harmonic temperature perturbations in planetary atmospheres are developed. Four spatial scales are shown to be generally important: the scale height of the atmospheric absorber, the absorption mean free path for thermal radiation, the altitude above the planetary surface, and the wavelength of the temperature perturbation. Atmospheric inhomogeneity is particularly important when the radiation mean free path and the vertical wavelength divided by 2 pi both exceed the absorber scale height. The surface is very important for wave decay at altitudes less than a few radiation mean free paths, and its effect depends on a comparison of the surface response time and the lifetime of the atmospheric perturbation. The surface response time depends on the conducting and emitting properties of the surface material and on the strength of turbulence in the planetary boundary layer. The additional influence of chemical reactions and phase changes on radiative damping is discussed, and several assumptions inherent in the development of the general expressions for time constants are evaluated. Terrestrial examples are used for purposes of illustration, but the development is kept sufficiently general so that the results remain applicable to most situations on other planets.

Prinn, R. G.↗

NASA NTRS1977

Relative effects on atmospheric ozone of latitude and altitude of supersonic flight

Three calculations are reported of the potential depletion of ozone by supersonic aircraft. These calculations utilized a two-dimensional model and a three-dimensional photochemical-dynamical model of the atmosphere in which ozone and the dynamical variables of the atmosphere were derived simultaneously. All calculations were based on a continuous atmospheric injection of 1.8 million tons/yr of NO2. Injections of 45 deg N and 20 km, at equilibrium, resulted in a 36% increase in total odd nitrogen between 8 and 38 km and in global ozone depletion of approximately 12%. Injection at 45 deg N and 17 km produced a 27% increase in odd nitrogen, but, because much of this increase occurred below 20 km, the ozone depletion amounted to only 6%. Injection at 10 deg N and 29 km resulted in a 55% increase of odd nitrogen; however, although there was more depletion above 20 km altitude, there was less below that altitude, and the ozone depletion was only 12.5%. In all three calculations, at least half as much ozone depletion occurred in the Southern Hemisphere as in the Northern Hemisphere.

Cunnold, D. M.↗

NASA NTRS1976

The impact of stratospheric variability on measurement programs for minor constituents

The scales of temporal and spatial variations in stratospheric minor species concentrations and dynamical quantities are briefly reviewed. Despite the fact that the stratosphere is often considered to be a very quiescent region of the atmosphere, it exhibits transient and generally unpredictable episodes of intense activity. The resultant necessity for some degree of coordination between different observers in their choice of locations and times for measurements of minor constituents is emphasized. A specific suggestion is provided for one or more short 'International Stratospheric Periods' whose duration would depend upon the time of year. During these short periods, as many observers as possible would perform an integrated series of observations designed to optimize the usefulness of their data to atmospheric scientists.

Prinn, R. G.↗

NASA NTRS1976

Three-dimensional dynamical and chemical modelling of the upper atmosphere

Progress in coding a 3-D upper atmospheric model and in modeling the ozone perturbation resulting from the shuttle booster exhaust is reported. A time-dependent version of a 2-D model was studied and the sulfur cycle in the stratosphere was investigated. The role of meteorology in influencing stratospheric composition measurements was also studied.

Prinn, R. G.↗

NASA NTRS1976

Chemistry and spectroscopy of the Jovian atmosphere

A comprehensive review is given of the chemistry and spectroscopic studies of the Jovian atmosphere. Thermochemical equilibrium models for determining atmospheric composition are considered along with possible disequilibrating processes, and studies of the photochemistry of H2, CH4, NH3, H2S, and PH3 using the modeling methods are summarized. It is shown that photodissociation and advection are the major disequilibrating processes in Jupiter's atmosphere, that lightning and charged-particle bombardment are relatively minor factors in the planet's bulk chemistry, and that the existence of living organisms on the planet is highly improbable. Spectroscopic investigations of Jupiter are discussed, emphasizing recent observations of absorption bands due to CH4, NH3, H2, He, and D. Spectroscopic abundance determinations are examined for H2, HD, CH4, CH3D, NH3, C2H6, C2H2, and PH3. Upper limits are given for the abundances of several unobserved gases in the visible atmosphere, including H2S, HCl, SiH4, benzene, purines, pyrimidines, and their derivatives.

Prinn, R. G.↗

NASA NTRS1975

Stratospheric distributions of odd nitrogen and odd hydrogen in a two-dimensional model

A two-dimensional pole-to-pole chemical model of the stratosphere is developed which extends from 8 to 38 km in altitude. Atmospheric motions are simulated by mean vertical and meridional winds and eddy diffusion coefficients. Seasonally averaged distributions of important odd nitrogen (NO, NO2, and HNO3) and odd hydrogen (H, OH, HO2, H2O2) compounds are computed. Photodissociation of N2O leads to production of odd nitrogen in the stratosphere, and the odd nitrogen is ultimately removed by downward transport into the troposphere and by rain-out (modeled by a rain-out lifetime of 30 days below 8-km altitude). Results are presented for a quasi-steady state in which seasonal cycles repeat themselves. These results show significant latitudinal as well as vertical variations in the predicted species which emphasize the need for at least two dimensions in accurate stratospheric modeling. Computed concentrations are compared with observations when they exist.

Prinn, R. G.↗

NASA NTRS1975

Phosphine on Jupiter and implications for the Great Red Spot

A study of the chemistry and photochemistry of the recently discovered phosphine in the atmosphere of Jupiter suggests that the red colorations on this planet result from photochemical production of red phosphorus particles. Chemical-dynamical models of this red phosphorus haze imply that the intensity of the red coloration is a strong function of the strength of vertical turbulent mixing in the atmosphere. If the Jovian Great Red Spot is a region of considerable dynamical activity our model provides a self-consistent explanation for the redness of this region in comparison to the rest of the planet.

Prinn, R. G.↗

NASA NTRS1975

Venus - Chemical and dynamical processes in the stratosphere and mesosphere

Photochemical models for the Venus clouds are presented and discussed. We illustrate models for sulfuric acid density as a function of altitude based on a proposed photochemical scheme. Emphasis is placed on two competing removal mechanisms for sulfur atoms above the visible clouds: S + O2 yields SO + O, and S + COS yields S2 + CO. The first reaction (which forms the major oxygen sink in the visible cloud region) requires reasonable O2 concentrations and leads to sulfuric acid production. The second reaction occurs in regions where O2 is severely depleted and leads to elemental sulfur production. Quantitative estimates of the balance between these two competing processes are presented together with a discussion of the complete sulfur and oxygen cycles on the planet. We propose that the dark regions in the ultraviolet of Venus are oxygen-depleted regions where a significant amount of ultraviolet-absorbing sulfur is being produced. We also discuss observations of particle densities on Venus and their implications for vertical mixing rates.

Prinn, R. G.↗

NASA NTRS1975

Stratospheric ozone destruction by aircraft-induced nitrogen oxides

The preliminary results from a three-dimensional dynamic-chemical model applied to the SST-NOx (NO + NO2) problem are reported. Simulations indicate that a depletion of about 12 per cent in total stratospheric O3 would be realized for a continuous NOx injection rate of 1.8 x 10 to the sixth power metric tons per year from a hypothetical fleet of SST's flying at an altitude of 20 km in the midlatitudes of the Northern Hemisphere. Sixteen per cent of the existing O3 would be destroyed on an annual basis. The model assumes a fleet of about 500 aircraft of the now-canceled American Boeing 2707 type; if only present Anglo-French and Russian SST models, which fly at lower, less harmful altitudes, are built, it will take a fleet of a few thousand such craft to attain an effective injection rate equal to the one above.

Alyea, F. N.↗

NASA NTRS1974

Venus - Vertical transport rates in the visible atmosphere

The cloud particles on Venus are sufficiently small for their vertical distribution to be strongly affected by atmospheric turbulence. Reasonably firm estimates of the vertical distribution of cloud particles can be made from current interpretations of refraction, polarization, and absorption band data. These enable very firm upper limits to be placed on average vertical mass diffusion coefficients in the visible atmosphere. These upper limits are independent of the cloud particle composition or mode of formation, and of changes in the particle size distribution with altitude.

Prinn, R. G.↗

NASA NTRS1974

The distributions of odd nitrogen and odd hydrogen in the natural and perturbed stratosphere

In order to quantitatively illustrate the effects of quasi-horizontal transport of certain gases and of the reactions influencing their concentrations, a vertical-meridional pole-to-pole stratospheric model is presented which explicitly predicts concentrations of odd nitrogen and odd hydrogen compounds in the natural stratosphere and also in a perturbed stratosphere incorporating artificial injection of nitrogen oxides by an SST fleet. The northern hemisphere SST operations clearly have a very large local effect on the nitrogen oxide distribution and also have a significant effect on the southern hemisphere. The largest changes are seen at the point of injection of the nitrogen oxides. Results are in agreement with previous one-dimensional models.

Prinn, R. G.↗

NASA NTRS1974

First results of a general circulation model applied to the SST-NOx problem

Results of model runs, one using two-dimensional distribution of NO2 in the unperturbed stratosphere and another including an additional localized source of NO2 to approximate the effect of SSTs, are reported. The general circulation model and chemical reactions are described, and corrections in the previous latitudinal and seasonal gradients of total columnar ozone and the diffusion coefficient in the neighborhood of the tropopause are noted. Excellent agreement with previous observations was obtained. Global distributions of ozone and NO2 are described and represented in graphs. Results indicate ozone reduction of approximately 16% in the Northern Hemisphere and approximately 8% in the Southern Hemisphere, with the mid-latitude source of NO2 apparently having a blocking effect on the horizontal transport of ozone, resulting in larger reductions of ozone at high latitudes than at low ones.

Cunnold, D. M.↗

NASA NTRS1974

A general circulation model of stratospheric ozone

The paper reports on a general circulation model being developed with the ultimate objective of assessing the effect of SST operations on the atmospheric ozone distribution. The model variables are represented in the spectral domain using 79 spherical harmonics and 26 vertical levels between the ground and 70 km. Initial calculations have attempted to simulate the seasonal variations of the unperturbed global ozone distribution. The model shows the presence of a westerly stratospheric jet in the winter hemisphere with amplitudes similar to those observed in the polar night jet. Easterlies dominate in the summer hemisphere. The model also shows ozone to be transported polewards and downwards. Furthermore the annual cycle in ozone concentrations at mid-latitudes has been simulated. Preliminary comparisons are also made with other features of the dynamics and the ozone distribution in the stratosphere.

Cunnold, D. M.↗

NASA NTRS1973

Venus - Composition and structure of the visible clouds

It is proposed that the visible cloud deck on Venus is composed of droplets of sulfuric acid. These are formed by the very rapid photooxidation of carbonyl sulfide in the upper atmosphere. The clouds are best described as an extensive haze since the predicted particulate scale height probably exceeds the gas scale height within the layer. The predicted mixing ratio for water is .000001 (lower limit), and for both carbonyl sulfide and sulfur dioxide it is .0000001 (upper limit); these are in good agreement with observations. Gaps in the layer are not possible unless the planetary scale dynamics produce cloud turnover times of less than a few days. Under these conditions, the water mixing ratio could approach .0001, and the formation of a thin hydrochloric acid haze at high altitude above the main cloud is possible.

Prinn, R. G.↗