摘要:

A theory of self‐focusing of intense electromagnetic waves in ducts with parabolic and saturating nonlinearity has been developed. The relative effects of inhomogeneity in the refractive index of the medium, parabolic nonlinearity due to small electrical polarization of the medium, and saturating nonlinearity due to considerable electrical polarization on self‐focusing have been stud

ISSN:0048-6604    

DOI:10.1029/RS007i007p00691

年代:1972

数据来源: WILEY

摘要:

The upper and lower boundary conditions are important in theoretically modeling the height distributions of minor neutral constituent concentrations in the upper atmosphere by solving continuity equations. This paper discusses the effects of such boundary conditions on their concentrations. It is shown that the upper boundary condition of no diffusive flux at 150 km does not affect seriously the minor constituent density distributions except for H and HO2above ∼120 km, where the escape flux of H reduces their concentratibns substantially. It is also shown that our previous model calculations have used the condition of constant flux with height at the lower boundary. It is suggested that reliable measurements of minor constituents in the upper stratosphere may be useful in improving the lower boundary condition for the mesosphere models and in simplyfying the modeling procedure

ISSN:0048-6604    

DOI:10.1029/RS007i007p00695

年代:1972

数据来源: WILEY

摘要:

As a step in determining the behavior of theD‐region ionization at sunrise, the development of atomic oxygen and ozone over sunrise has been investigated taking into account the absorption of solar ultraviolet radiation by the time‐varying, nonuniform ozone distribution over the mesosphere at sunrise. The dissociation rates of ozone and molecular oxygen are calculated and used to determine the time variations in the O and O3densities at sunrise for a model considering only the oxygen allotropes. Transport processes were neglected in the sunrise calculations because chemical time constants are shorter than those for transport. However, the assumed initial presunrise atomic oxygen and ozone distributions, based on an average of theoretical and experimental results, do include the effects of transport. It was found that at altitudes from 60 to 80 km there is a delay in the ozone sunrise, and thus a delay in the development of the atomic oxygen density. [O]/[O3] was computed during sunrise, and a similar delay in its sunrise increase was observed. The production of metastable oxygen O2(1Δg,) by the photodissociation of ozone in the Hartley band at sunrise was also investigated. A simplified chemical scheme for O2(1Δ) is presented, from which a closed‐form solution for the O2(1Δ) densities over sunrise was obtained. O2(1Δ) may be important in the ion chemistry at sunrise, and can contribute to the early appearance of electrons in th

ISSN:0048-6604    

DOI:10.1029/RS007i007p00703

年代:1972

数据来源: WILEY

摘要:

The photodetachment rates of several negative ions believed to be present in theDregion are estimated for sunrise conditions. The photodetachment cross sections of O−and O2−which have been measured in the visible and infrared wavelength ranges are used. Since the photodetachment cross sections of NO2−and NO3−are not yet known, the behavior of their rates could only be estimated. Infrared band absorption by H2O and CO2is included in the calculations. For atoms and molecules with large electron affinities the ozone ultraviolet absorption is important. The effects of photodetachment onD‐region behavior are discussed and found to be relatively un

ISSN:0048-6604    

DOI:10.1029/RS007i007p00717

年代:1972

数据来源: WILEY

摘要:

The growth over sunrise of theCandDlayers of the ionosphere is investigated for a model which includes: the negative ion species O−, O2−, O3−, O4−, NO2−, NO3−, CO3−, and CO4−; ion‐pair production by galactic cosmic rays, precipitated electrons, photoionization of NO by scattered Lyman‐α radiation, and the photoionization of NO and O2(1Δ) by direct solar radiation; the photodetachment of most of the negative ions; and the time variations of all these parameters. It is found that the inclusion of the reaction NO3−+ O → NO2+ O2−with a rate constant of 5×10−14cm3sec−1in combination with fast electron‐ion recombination (α ∼ 10−5cm3sec−1) can accurately reproduce both the development of theClayer at sunrise and the correct magnitude and form for theD‐layer development. The photodetachment of NO3−is not a suitable alternate source of sunrise electrons because of the large electron affinity of NO3. The photodetachment of lower‐affinity negative ions, such as hydrated species, could replace the NO3−+ O → NO2+ O2−reaction if indeed the presunrise mesospheric ions are predominantly hydrated. The dominant ions in the present scheme are NO3−, CO4−, and CO3−. Atomic oxygen greatly limits the quantity of negative ions above 75 km at all times of the day by associative detachment and is responsible for the nighttimeD‐layer ledge of electron density. The 98 and 94° VLF radio

ISSN:0048-6604    

DOI:10.1029/RS007i007p00725

年代:1972

数据来源: WILEY

摘要:

Continuous measurements of electron temperature and electron concentration were made at Jicamarca from 0700 to 0830 LT and from 1130 to 2000 LT during the great magnetic storm of March 8, 1970, when theF2peak rose as high as 800 km. Continuous measurements of the vertical component of E×B drift were made from 1130 to 1730 LT. A synthesis of the observed electron concentrations was made using a model that solved the time‐dependent electron‐ion continuity equation for O+and the molecular ions; the latter chemistry was included to improve the solutions at lower heights. It was found, using the observed values of vertical drift, that most of the observed features of theF2‐region ionosphere were synthesized by the model. An interpretation of the synthesis that emphasizes the importance of horizontal diffusion at the equator is given. Observations are presented for March 7, 8, and 9, 1970, including the Huancayo magnetograms, which display a close correlation with the drift measur

ISSN:0048-6604    

DOI:10.1029/RS007i007p00739

年代:1972

数据来源: WILEY

摘要:

This paper announces the operational status of an auroral‐zone incoherent‐scatter radar. The Stanford Research Institute 1290‐MHz incoherent‐scatter radar, which was moved to Chatanika, Alaska (L= 5.7), an auroral‐zone location near Fairbanks, is now producing interesting new results. The siting of the radar is such thatD‐,E‐, andF‐region incoherentscatter measurements can be made without ground‐clutter interference. Although coherent auroral‐clutter echoes can at times be seen at relatively low elevation angles in the north, auroral echoes are sufficiently weak at 1290 MHz in the sidelobes of the antenna that they are not detectable during normal incoherent‐scatter measurements. The capabilities of the radar system are outlined, and samples are presented of the type of incoherent‐scatter

ISSN:0048-6604    

DOI:10.1029/RS007i007p00747

年代:1972

数据来源: WILEY

摘要:

This paper presents a computer technique for synthesizing an array pattern for the practical problem in which only the magnitude of the far‐field pattern is specified. The general design problem is one in which both the currents and the spacings of the elements are allowed to be variables. The synthesis is based on a procedure which minimizes the norm of the difference between the Fourier coefficients of the desired and actual patterns. This criterion is very useful from practical design considerations since it allows one to determine a priori the highest order Fourier coefficient that can be approximated if the maximum array size is specified. Also, if no array size is specified, the procedure gives the array size necessary to obtain a given degree of approximation in the patter

ISSN:0048-6604    

DOI:10.1029/RS007i007p00757

年代:1972

数据来源: WILEY

摘要:

Pulse‐compression techniques are now being used successfully in incoherent observations at Arecibo. In most observations a 13‐bit Barker code and 6‐μsec baud length are used, giving a compression ratio of 13 to 1 with very low range sidelobes and an altitude resolution of 0.9 km. A few of the first measurements with this technique are presented here and include observations of (a) theEregion and sporadicElayers, (b) theD‐region ledge near 80 km, and (c) narrow enhanced echoes associated with HF heating of the io

ISSN:0048-6604    

DOI:10.1029/RS007i007p00763

年代:1972

数据来源: WILEY

ISSN:0048-6604    

DOI:10.1029/RS007i007p00767

年代:1972

数据来源: WILEY