摘要:

The use of three‐wavelength transit‐time measurements is considered as a means of estimating space averages of total density and water vapor density along a path through the lower atmosphere. The effects of instrumental errors and of errors in estimating average path temperature are examined. The results indicate that, for what are considered reasonable path conditions in this context, instrumental errors account for about 1‐ppm accuracy in corrected range and about 0.5% in total density and water vapor density. Subsequent refinement of the dispersion measurements should permit reduction of the uncertainty in corrected range and total density to about 0.01 ppm and 0.005%, respectively. The accuracy of the integrated water vapor density is, however, at present limited about equally by dispersion errors and temperature interpolation e

ISSN:0148-0227    

DOI:10.1029/JB073i010p03097

年代:1968

数据来源: WILEY

摘要:

The kinetics of condensation in an expansion chamber was studied by high‐speed photography. The droplet size and the number of droplets were plotted against time during the expansion. Droplets begin to form right at the start of the expansion. A droplet of a few microns is formed within a few microseconds. It is concluded that under these conditions condensation occurs by a chain reaction type mechanism, whereas the mechanism postulated by the classical theory of nucleation and growth would apply to slow condensation on a wal

ISSN:0148-0227    

DOI:10.1029/JB073i010p03103

年代:1968

数据来源: WILEY

摘要:

This paper summarizes the findings of an extensive study of the phenomenon of absorption by oxygen of electromagnetic energy in the atmosphere. The purpose of the study was to make sufficient measurements in the oxygen absorption spectrum (50 to 70 GHz) to enable us to confirm or refine the existing theory as necessary. We have calculated new values for the Van Vleck line broadening coefficients, based on 1500 independent attenuation measurements made over a slant range from space to various altitudes in the atmosphere. These measurements were made over a frequency range of 53.4 to 56.4 GHz and an altitude range from zero to 14.75 km. The average relative error between the measured and the calculated attenuation is 8.6%. A similar comparison based on Meeks and Lilley's line broadening coefficients yielded an average relative error of 13%.

ISSN:0148-0227    

DOI:10.1029/JB073i010p03113

年代:1968

数据来源: WILEY

摘要:

A theoretical model of the shock wave from a lightning discharge ranging from the strong blast wave region out to the acoustic limit is given for the first time. The trajectory and overpressure of the strong shock wave are described by the well‐known equations for cylindrical blast waves. In the intermediate shock strength region (1.1

ISSN:0148-0227    

DOI:10.1029/JB073i010p03121

年代:1968

数据来源: WILEY

摘要:

Variations of the Ce141and Ce144activities in the ground‐level air were measured at Fayetteville (94°W, 36°N), Arkansas, for a period of about 3 months after the Chinese nuclear explosion of May 9, 1966. A cyclic pattern of variations was observed for both Ce141and single fallout particles. This cyclic pattern indicated that they were airborne for a long period and traveled far. Some of the particles may have circled the earth many ti

ISSN:0148-0227    

DOI:10.1029/JB073i010p03129

年代:1968

数据来源: WILEY

摘要:

The relative neutron yield of several targets of light elements exposed to monoenergetic ionized helium beams from the Argonne tandem accelerator was determined for alpha energies ranging from 4.8 to 8.8 Mev. Our ratio of the neutron yields for 5.3 Mev are in agreement with published data on thick target yields obtained with Po210α particles. The average (α,n) yield per α particle of the natural radioactive series for some elements and for different soil compositions was calculated from our results assuming an (α,n) yield of 75 neutrons per 108α particles of Po210α for aluminum. If 3 ppm U238and 11 ppm Th232are assumed as representative of the earth's upper crust, a production rate of 6.7 ± 0.7n/g/yr in sand and 13.5 ±1.3n/g/yr in granite is obtained. Additional 1.4n/g/yr will be generated because of the spontaneous fission of U238. As the production rate of neutrons through interactions of cosmic rays with the earth's surface at sea level is of the order of 800n/g/yr, these (α,n) reactions cannot be of any significance to exposure rates of human populations. They may be of some interest to geologists, however, and may be the main contributors to neutron fluxes in tunnels, deep caves, or mines, where cosmic‐ray background i

ISSN:0148-0227    

DOI:10.1029/JB073i010p03135

年代:1968

数据来源: WILEY

摘要:

The results of twenty‐eight seismic refraction profiles recorded in the various physiographic provinces of the Philippine Sea as part of the United States and Japan Science Cooperation Program are presented in four schematic structure sections. The basins of the Philippine Sea have fairly normal oceanic crust that includes, between the sea floor and layer 2, a layer of about 3.5‐km/sec velocity controlling the characteristic rough topography. Crustal thickening beneath the Nansei Shoto, Oki‐Daito, Kyushu‐Palau, and the Honshu‐Mariana ridges is associated mainly with an increase in thickness of the 3.5‐km/sec layer and a thick underlying section of material with a velocity between 5.5 and 6.0 km/sec. Beneath the Nansei Shoto trench and the Honshu‐Mariana trench, there is a tendency for layer 2 to increase and layer 3 to decrease in thickness as the trench is approached from the adjacent o

ISSN:0148-0227    

DOI:10.1029/JB073i010p03143

年代:1968

数据来源: WILEY

摘要:

A large region of high heat flow has recently been discovered in the northwest Pacific. The area extends from the Sea of Okhotsk in the north to the Philippine Sea in the south and may continue as far as the Fiji plateau. Two possible sources of the extra heat are volcanic intrusion into the crust and dissipative shear heating in the mantle. There are fundamental objections to both explanations, and, therefore, the origin of the high regional heat flow remains unknown. The high temperature gradient is of geological importance, since the crustal temperatures are sufficiently high to cause metamorphism.

ISSN:0148-0227    

DOI:10.1029/JB073i010p03173

年代:1968

数据来源: WILEY

摘要:

From March 5 to 15, 1965, Kilauea volcano erupted over 15 million cubic meters of tholeiitic basalt along the upper east rift zone between Makaopuhi and Kalalua craters. A pond of basalt 83 meters deep was left within the west pit of Makaopuhi crater. The eruption was preceded by inflation of the Kilauea summit and was accompanied by collapse of the summit. Observed horizontal, vertical, and tilt changes accompanying inflation of Kilauea before and after the eruption cannot fit any simple model for inflation of a single magma chamber. Data for the collapse are even farther from agreement with the draining of a single chamber. Seismic activity was exceptionally low in the months preceding the eruption and during the eruption. Amplitude of harmonic tremor correlates with the rate of fountaining during the eruption. Temperatures of the erupted lavas have been estimated at 1190°–1200°C by extrapolation of thermocouple data obtained in Makaopuhi lava lake. A comparison with temperatures of other Kilauea eruptions measured by optical pyrometer indicates that the best optical pyrometry yields temperatures 35°–75° lower than the true temperature of eruption. The erupted lavas were olivine‐poor tholeiitic basalts. Lavas erupted at successively later times down rift are shown to be differentiated from the lavas erupted at Makaopuhi crater by removal of olivine, clinopyroxene, and minor plagioclase during transport in the

ISSN:0148-0227    

DOI:10.1029/JB073i010p03181

年代:1968

数据来源: WILEY

摘要:

A survey of the Ni, Ga, Ge, and Ir contents of the disproportionately large number of coarse octahedrites discovered in Arizona shows that three falls are necessary to account for these objects. Two meteorites, Seligman and Southern Arizona, have unique compositions, whereas the remainder of the irons appear to be fragments of the Canyon Diablo fall. A survey of twenty‐three similar meteorites from other geographical locations reveals that none of these objects has the same composition as Canyon Diablo. The ranges of Ga, Ge, and Ir concentrations among fragments from this single large meteoroid are about equal to the associated experimental errors for these elements of 4, 4, and 12%, respectively. The Ni range, which is several times larger than the experimental error, may be related to the high proportion of inclusions in irons of this group. The scatter of Canyon Diablo specimens over distances as great as 360 km from the crater is believed to have resulted from human transpor

ISSN:0148-0227    

DOI:10.1029/JB073i010p03207

年代:1968

数据来源: WILEY