摘要:

Solar radiation pressure can cause rotational bursting and eventual elimination from the solar system of asymmetric dust particles by a windmill effect. The life span against this process for metallic particles with radii of 10−5to 10−2cm ranges from 10 to 10,000 years. The effects of magnetic spin damping have been considered in this estimate. This depletion mechanism works faster than the traditional Poynting‐Robertson effect by approximately one order of magnitude for metallic particles and about two orders of magnitude for nonmetallic part

ISSN:0094-8276    

DOI:10.1029/GL002i009p00365

年代:1975

数据来源: WILEY

摘要:

We present evidence to support the hypothesis that the fine‐grained, basaltic‐textured portions of rocks 60618 and 65785 were produced by impact melting of the coarse‐grained spinel‐olivine anorthosite (60618) and spinel troctolite (65785) portions, coupled with admixture of approximately 33% and 63%, respectively, material of alkalic high‐alumina basalt (KREEP) composition. The abundance of impact‐modified rocks at the Apollo 16 site with compositional similarities to the impact melts reported here, suggests that the relations observed in these rocks are indicative of widespread impact mixing with KREEP rocks of the luna

ISSN:0094-8276    

DOI:10.1029/GL002i009p00369

年代:1975

数据来源: WILEY

摘要:

The thermal anisotropies near the peaks of proton distributions are observed to vary characteristically across two simple high speed streams. Before the time of maximum velocity gradient T∥ of the core distribution is greater than T⊥ but afterwards, and persisting throughout the remainder of the high speed region, T∥

ISSN:0094-8276    

DOI:10.1029/GL002i009p00373

年代:1975

数据来源: WILEY

摘要:

A curve fitting procedure for mathematically representing the auroral oval is described. It is shown that the Feldstein ovals and quiet auroral ovals of the night side in DMSP photographs can be approximated by an offset circle, plus a small (≲ 1° magnitude) Fourier component in corrected geomagnetic coordinates. Parameters are introduced, Θ and (θo, ϕo), that indicate the dynamic motion of the auroral oval size and center location, respectively. Using the parameter Θ, an analysis of several DMSP photographs shows a strong correlation between the southward interplanetary magnetic field (−Bz) and the size of the auro

ISSN:0094-8276    

DOI:10.1029/GL002i009p00377

年代:1975

数据来源: WILEY

摘要:

We present some special steady state solutions of the nonlinear one‐dimensional set of equations describing the Rayleigh‐Taylor instability. This instability is believed to be one of the possible mechanisms responsible for equatorial spread F and we discuss the relevance of our results to some recent experimental observati

ISSN:0094-8276    

DOI:10.1029/GL002i009p00381

年代:1975

数据来源: WILEY

摘要:

Recently, atomic nitrogen densities of ∼5 × 107to 108cm−3were inferred in the daytime thermosphere from studies of the NI(²D−4S) 5200Å emission and from the photochemistry of various ion species using data measured by the Atmosphere Explorer‐C satellite. In this paper we use the photochemistry of NO+and O2+at night to determine nocturnal N(4S) densities in the thermosphere. We present evidence for a missing source of NO+and a missing sink for O2+at night and show that this can be adequately supplied by the reaction O2++ N → NO++ O if the N density at 200 km is ∼7 × 106cm−3. The atomic nitrogen has an important effect on studies of the 6300Å airglow. The omission of N in calculations of O(¹D) using ground‐based data results in an overestimate of the rate coefficient for que

ISSN:0094-8276    

DOI:10.1029/GL002i009p00385

年代:1975

数据来源: WILEY

摘要:

The atomic hydrogen distribution at 250 km during December 1974 solstice has been inferred, considering charge exchange equilibrium, from Atmosphere Explorer‐C measurements ofn(H+),n(O+), andn(O). An empirical model, derived from the observations by least square analysis in terms of spherical harmonics, has the following characteristics: (a)n(H) increases by as much as a factor of two between the summer and winter hemispheres, (b) then(H) diurnal variation is largest at the equator wherenmax/nmin = 3.2, the maximum occurring at 03hLT, and (c) the diurnal variation is larger in the winter hemisphere (nmax/nmin = 2.6 at +40°) than in the summer (nmax/nmin = 2.3 at −40°). Similar analysis of the gas temperature derived fromn(N2) measurements reveals that alln(H) and Tgspherical harmonic coefficients are anticorrelated. Both the diurnal and latitudinal (annual)n(H) and Tgamplitudes are in substantial agreement with the “zero flux condition,” in which exospheric flow dominates the hydrogen distribution. The observed diurnal phase lag ofn(H) with respect to Tgis about one hour, agreeing with theory. During the period of measurement the observed mean global values of Tgandn(H) were 800K and 3.6 × 105cm−3, respectively, the latter exceeding the Kockarts‐Nicolet model concentration by a

ISSN:0094-8276    

DOI:10.1029/GL002i009p00389

年代:1975

数据来源: WILEY

摘要:

Stratospheric air samples have been obtained at 17.7, 22.3, and 26.2 km using balloon borne sampling spheres launched from Laramie, Wyo. These samples have been analyzed for CFCl3, CF2Cl2and N2O, using electron capture detector gas chromatography. The concentrations of all three constituents are compared with theoretical models and found to be in excellent agreement. The dissociation products of N2O, CFCl3, and CF2Cl2(NO and chlorine atoms) catalytically destroy ozone in the stratosphere. A knowledge of the concentrations of these species in the stratosphere is therefore essential to an understanding of the ozone balance.

ISSN:0094-8276    

DOI:10.1029/GL002i009p00393

年代:1975

数据来源: WILEY

摘要:

Bleaching of paper pulp represents a major industrial use of chlorine and could provide an environmentally significant source of atmospheric halocarbons. The related global production of chloroform is estimated at 3 × 105ton yr−1and there could be additional production associated with atmospheric decomposition of perchloroethylene. Estimates are given for the production of methyl chloride, methyl bromide and methyl iodide, 5.2 × 106, 7.7 × 104, and 7.4 × 105ton yr−1respectively. The relative yields of CH3Cl, CH3Br and CH3I are consistent with the hypothesis of a marine biological source for these compounds. Concentrations of other halocarbons observed in the atmosphere appear to indicate industrial

ISSN:0094-8276    

DOI:10.1029/GL002i009p00397

年代:1975

数据来源: WILEY

摘要:

Satellite photographs for the period 13 August through 6 September 1973 show both north and south movement of ice floes off the east Greenland coast between 74° and 80°N. The paths of seven large (approximately 25 km diameter across) ice floes tracked through the entire period, and a number of smaller floes tracked through portions of the period, indicate the presence of anticyclonic surface eddies in the waters covering the coastal shelf are

ISSN:0094-8276    

DOI:10.1029/GL002i009p00400

年代:1975

数据来源: WILEY