摘要:

An order‐of‐magnitude calculation of the characteristic time required for the homogeneous heteromolecular nucleation of new stratospheric particles involving the H2SO4‐HNO3‐H2O ternary system is presented. This characteristic time is compared with the characteristic time required for the homogeneous heteromolecular nucleation of sulfuric acid particles involving the H2SO4‐H2O binary system and with the characteristic time for the sulfuric acid vapor condensing on the preexisting particles. From the comparison of these characteristic times, we show that this formation of new particles involving H2SO4‐HNO3‐H2O may be the most favorable mechanism for the formation of “sulfuric acid particles” in

ISSN:0094-8276    

DOI:10.1029/GL002i002p00041

年代:1975

数据来源: WILEY

摘要:

During cruise No. 32 of RV “Meteor”, 6.Nov.–6.Dec. 1973 across the Atlantic at 15°N, samples of Aitken nuclei were taken and the chemical compsition determined by an X‐ray fluorescence technique. The samples consisted mainly of sulfur with concentration of 0.2 µg/m³ in pure Atlantic air and about double this value in air influenced by the Sahara. The concentrations of the elements chlorine, calcium and potassium were about one order of magnitude lower and suggest the absence of sea salt in the Aitken particle range. The elements vanadium, selenium and bromine were just below the positive detection limits but seemed to be present, since all values were higher than the blank values but within the error limits. The results show that in clean air conditions the dynamics of the Aitken particles are closely related to the su

ISSN:0094-8276    

DOI:10.1029/GL002i002p00045

年代:1975

数据来源: WILEY

摘要:

In order to explain the ionosphere of Io as observed by Pioneer 10, we propose a tenuous atmosphere of neon, which is ionized by solar radiation. Predicted plasma number densities and temperatures are presented and discussed.

ISSN:0094-8276    

DOI:10.1029/GL002i002p00049

年代:1975

数据来源: WILEY

摘要:

The intense electromagnetic radiation of near earth origin, observed by the OGO, IMP, and Hawkeye satellites, can be explained in terms of plasma oscillations near the upper hybrid frequency which are stimulated in the high latitude regions at distances within 5 earth radii (5RE). The wave energy is converted from the longitudinal electrostatic mode to the transverse electromagnetic mode as it travels in the slightly inhomogeneous magnetosphere, and it is reflected at the point where the wave frequency equals the local electron plasma frequency. This emission region is confined to radial distances less than about 4RE; the peak emission region occurs near 2RE. The original plasma oscillations are generated in the turbulent plasma produced by precipitating electrons associated with discrete auroral arcs. The mechanism has possible applications to studies of the irregular structure of the magnetospheric thermal plasma and to models for the decametric radiation from Jupiter.

ISSN:0094-8276    

DOI:10.1029/GL002i002p00052

年代:1975

数据来源: WILEY

摘要:

High gain portable seismographs have been operated at 22 sites along the San Miguel fault zone, Baja California, Mexico. We report results in terms of normalized rates of microearthquakes per day. Very high rates, exceeding 100 events/day, were observed near the southeast end of the San Miguel fault. Sixteen of the 22 sites recorded rates exceeding 20 events/day. The overall micro‐seismicity is higher than along most of the San Andreas fault in Southern California. At two sites, arrays were operated to obtain accurate locations. Locations near the southeast end of the San Miguel fault were very near the fault trace and at depths of 8 to 14 km. Relatively high microearthquake rates were observed at a site 70 km from Tijuana, suggesting that the northwestern San Miguel fault zone is active and might pose a significant seismic hazard to the cities of Tijuana and San Dieg

ISSN:0094-8276    

DOI:10.1029/GL002i002p00056

年代:1975

数据来源: WILEY

摘要:

An array of standard long period stations is applied to measure phase velocities of seismic surface waves by way of frequency‐wavenumber analysis. The number of interfering modes is reduced by windowing the signal for successive group velocity intervals. The method is powerful, even with relatively small arrays: up to 6 higher Rayleigh modes at periods between 20 and 100 sec. have been resolve

ISSN:0094-8276    

DOI:10.1029/GL002i002p00060

年代:1975

数据来源: WILEY

摘要:

Application of the method of Joint Hypocenter Determination (JHD) to carefully determined arrival time data from a small network of sensitive and well‐distributed local and teleseismic stations provides very precise locations of deep earthquakes. The precision of locations attained by this method—the relative locations are good to about 5 km—is limited mainly by the accuracy and precision of the measurements of arrival times. Application of the technique to a small and very active part of the deep earthquake zone of the Tonga island arc (depths near 600 km) reveals probable fault planes associated with the occurrence of deep earthquakes. The spatial distribution of precisely relocated hypocenters is closely related to the orientation of the focal mechanism solutions of two deep earthquakes. Hypocenters cluster in a plane parallel to one of the nodal planes for each of the two solutions examined. The planar features are yearly vertical and have linear dimensions of about 40 km. In one case the shocks defining the fault plane also tended to cluster in time near the occurrence of the largest event. These and other data suggest the existence of several distinct fault planes in the area studied. Our study is being extended to examine the structure of the entire Tonga deep seismic

ISSN:0094-8276    

DOI:10.1029/GL002i002p00063

年代:1975

数据来源: WILEY

摘要:

Fission‐track dating and K‐Ar dating indicate that the age of apatite from Cerro de Mercado, Mexico, is 30 m.y., in contradiction to previous corrected fission track ages of 40 and 57 m.y. by other works. Annealing data for the “plateau method” correction of fission‐track ages for the Cerro de Mercado apatite lead to corrections by a factor of sixty or more, which give geologically unreasonable ages. In addition, published data concerning the length of fission tracks and the annealing of minerals imply that the basic assumptions used in an alternative procedure, the length‐reduction‐correction method, are also invalid for many crystal types and must be approached with caution unless individually justified for a parti

ISSN:0094-8276    

DOI:10.1029/GL002i002p00067

年代:1975

数据来源: WILEY