摘要:

This numerical study of dynamical effects on the global distribution of atomic oxygen in the thermosphere makes use of a three‐component model of upper atmospheric dynamics which treats the gases N2, O2, and O coupled together by collisions. This model simultaneously treats diurnal and seasonal variations of the distributions of these gases. Specific comparisons of hydrostatic computations with those taking into account wind‐induced departures from hydrostatic equilibrium show that none of these gases can be considered to be in hydrostatic equilibrium below ∼200 km. Global scale winds are shown to cause the observed winter enhancement of atomic oxygen in the lower thermosphere. Comparison of the model results with observational data shows generally good agre

ISSN:0148-0227    

DOI:10.1029/JA084iA04p01241

年代:1979

数据来源: WILEY

摘要:

Earthquake‐generated Rayleigh waves excite shock waves at the surface of the earth which propagate upward nearly vertically through the atmosphere as infrasound. The HF Doppler sounder is a sensitive tool for detecting and recording these infrasounds at ionospheric heights. By constructing electron density distributions from ionograms the propagation ray paths and delay times for the long‐period waves can be determined. By using these data the dispersion curves for oceanic Rayleigh waves have been deduced. These curves are within 5% of the expected curve synthesized from data obtained from seismograms. Application of these data to the 1969 Kurile Island earthquake shows that it had a single source, while application to the 1968 Tokachi‐Oki earthquake shows the existence of several so

ISSN:0148-0227    

DOI:10.1029/JA084iA04p01253

年代:1979

数据来源: WILEY

摘要:

Gravity waves are the product of Joule heating, the auroral electrojet during geomagnetic substorms, the equatorial electrojet in the thermosphere, severe thunderstorms, tornadoes, and hurricanes in the troposphere, etc. A thorough understanding of sources and sinks of gravity waves can greatly advance our knowledge concerning atmosphere‐ionosphere‐magnetosphere couplings. We have limited ourselves in this paper to discussions of couplings between the ionosphere and the troposphere during the time periods of isolated tornadoes on the stormy day of November 20, 1973. Identification of the location of wave sources for waves detected at F region ionospheric heights was attempted by using the observed characteristics of wave propagation in ray‐tracing computations. Computed locations of wave sources were then compared with conventional meteorological data. The results show that the sources of the gravity waves associated with tornadoes were always on the squall lines and near the tornado touchdown locations. The results also suggest that ionosphere‐troposphere coupling studies can contribute to our understanding of the dynamical development of severe

ISSN:0148-0227    

DOI:10.1029/JA084iA04p01261

年代:1979

数据来源: WILEY

摘要:

A one‐dimensional, time‐dependent model has been developed to investigate seasonal variations in ozone density in the Martian atmosphere. The model utilizes data for atmospheric temperature, pressure, and water vapor abundance observed by Viking. The results indicate that a high ozone density is not produced near the winter solstice but is in rather late winter, when the amount of water vapor is still small and the solar radiation can penetrate more deeply. A similar condition met in early winter does not necessarily produce a high ozone density because of the predicted higher HO2density. Seasonal variations in ozone abundance are discussed in terms of the abundances of H2O and H2and the seasonal variations in their reaction products H2O2and HOx. The roles of transport, the effects of ozone loss to the surface, and the differences between northern and southern hemisphere ozone distributions are also discus

ISSN:0148-0227    

DOI:10.1029/JA084iA04p01269

年代:1979

数据来源: WILEY

摘要:

Atmospheric transmittances integrated over wavelength intervals corresponding approximately to the (15–0) through (4–0) Schumann‐Runge bands of O2have been determined from EUV solar spectra (1768 Å<λ<1948 Å) photographed at seven altitudes between 102 and 76 km with a rocket‐borne spectrograph having a resolution of 0.07 Å. The observed transmittances are compared with atmospheric transmittances predicted from three models of the O2absorption cross section. The predicted transmittances have also been used to derive column densities of atmospheric O2from the observations. The results are compared with values calculated from the U.S. Standard Atmosphere (1976) and with oxygen column densities determined by Prinz and Brueckner (1977) from EUV solar spectra of the Schumann‐Runge continuum (λ<1750 Å) and of the H‐Lyman alpha line (1216 Å) recorded on the same films used in the present research. The comparisons test the utility of the models for studies of atmospheric photochemistry, suggest which models may be best for this purpose, and indicate how the mode

ISSN:0148-0227    

DOI:10.1029/JA084iA04p01277

年代:1979

数据来源: WILEY

摘要:

Ultraviolet spectra between 2000 and 2800 Å of an IBC II+aurora were obtained by a rocket‐borne Ebert‐Fastie monochromator at 15‐Å resolution over Fort Churchill, Manitoba. The υ′=0–8 progressions of the N2Vegard‐Kaplan system, the Δυ=8 sequence of the Lyman‐Birge‐Hopfield system, and a progression attributed to the Herman‐Kaplan system were identified by a synthetic spectrum analysis. Relative populations of the first eight vibrational levels of theA³Σu+state at high altitude were obtained from the theoretically generated spectra, and quenching rate coefficients were derived for these eight levels by using an atomic oxygen concentration derived from data from another experiment on board. For υ=0 the quenching rate coefficient was found to be 2.0 × 10−10cm³ s−1and was not found to increase for higher vibrational levels. The intensity of the (0, 2) band of the Herman‐Kaplan (E³Σg+→A³Σu+) system was found to be ∼5 times the theoretically predicted value, but even so, the cascade fromE³Σg+provid

ISSN:0148-0227    

DOI:10.1029/JA084iA04p01287

年代:1979

数据来源: WILEY

摘要:

Analysis of the Ogo 6 OI green line nightglow photometer experiment has been carried out for eight cases when the alignment of the spacecraft was such that local emission rates could be determined below the altitude of maximum emission and down to about 80 km. The results obtained show that the vertical gradient of the emission rate between 95 and 80 km alternates between regions of very rapid variation and very slow variation spaced on a scale of 5–10 degrees of latitude. Maps showing isoemissivity contours and isodensity contours for [O] in vertical meridional planes are presented. The densities are computed under three assumptions concerning excitation mechanisms. Comparisons of the vertical variations of oxygen density with the results of a time dependent theory suggest the regions of strong downward transport alternate in latitude with regions of weak transport near 90 km. In the first case, conversion of O to O3at night appears to be overwhelmed by downward transport of

ISSN:0148-0227    

DOI:10.1029/JA084iA04p01297

年代:1979

数据来源: WILEY

摘要:

The physical processes which couple the mid‐latitude ionosphere and protonosphere are complicated during the postsunset period when temperatures are rapidly changing. We have studied these processes with incoherent scatter measurements of the electron densities and proton and O+vertical velocities in the topside ionosphere with 10‐min time resolution. Large velocity differences between the H+and O+ions in the topside ionosphere occur at times. The two vertical fluxes follow similar temporal trends at high altitudes, where the species have diffusive equilibrium profiles, both of which simply contract after sunset as the ionosphere cools. At lower altitudes, however, the charge exchange reactions can destroy the similarity in the temporal behavior of the two fluxes and can lead to ion counterstreaming at times. Therefore there is no simple relationship between theF2region O+flux and the total ion transport between the ionosphere and the protonosph

ISSN:0148-0227    

DOI:10.1029/JA084iA04p01310

年代:1979

数据来源: WILEY

摘要:

Quenching of N(²P) by atomic O has been included in the calculations used to estimate changes in mean emission heights of auroral forms previously studied by Vallance Jones and Gattinger (1978). Recent estimates of the production efficiency for N(²P) in electron impact dissociation of N2permit a cross check on the estimated height from the intensity of the 1.04‐µ m [N I] multiplet. Satisfactory agreement is obtained if the atomic O concentration in the 110‐ to 120‐km region was about half that of the Jacchia (1971) model for a N(²P)‐O quenching rate coefficient of 1

ISSN:0148-0227    

DOI:10.1029/JA084iA04p01315

年代:1979

数据来源: WILEY

摘要:

It is shown that an ordinary electromagnetic wave can excite parametric instability by scattering off electrostatic ion cyclotron waves. Application of our result in the European auroral zone of the ionosphere is discussed.

ISSN:0148-0227    

DOI:10.1029/JA084iA04p01317

年代:1979

数据来源: WILEY