摘要:

Inventories of Sr90in the earth's environment have been made for a series of dates between August 1961 and March 1965. On every date tested these inventories are found to be deficient when compared with the amount of Sr90expected to be present, on the basis of nuclear weapons tests conducted in the atmosphere. The major portion of this deficiency is attributed to a 33% error in the inventory of Sr90deposited on the earth's surface that is caused by assuming that the observed fallout on land is equivalent to that on the oceans, per unit area. It is suggested that water bodies collect fallout 1.5 times more efficiently than land. Applying this factor to the worldwide Sr90deposition inventory results in good agreement between stratospheric depletion and worldwide deposition, in addition to accounting for the apparent budget deficiency.

ISSN:0148-0227    

DOI:10.1029/JZ071i006p01515

年代:1966

数据来源: WILEY

摘要:

Thunderstorm weather and individual cells were observed and their RF radiations recorded for frequencies with approximately decade spacings from 10 khz to 1000 Mhz. Antennas were nondirectional, but positive results were obtained for the three cases in the summer of 1964 when only single cells were detectable in the vicinity of the observation station. Correlated increases of RF noise were noted in each case, and these increases preceded the first lightning strokes by 10, 12, and 15 minutes. Absence of local corona was ensured by monitoring an electric field mill, and other interfering cells were avoided by radar observation. No theory is presented to explain these radiations, but they are assumed to be caused by minor streamer processes in the cloud due to charge density fluctuations.

ISSN:0148-0227    

DOI:10.1029/JZ071i006p01519

年代:1966

数据来源: WILEY

摘要:

The concentration changes of the short‐lived daughter products of Rn222in air due to washout have been computed according to a three‐phase (gas‐aerosol‐raindrop) model for a wide range of values of the system parameters. It is shown that the ratio of Pb214to Bi214concentrations is a sensitive measure of the relative washout efficiences of free atoms and of aerosol particles by rain. Preliminary experimental results which give the measured values of this ratio for rainy days are pr

ISSN:0148-0227    

DOI:10.1029/JZ071i006p01525

年代:1966

数据来源: WILEY

摘要:

Simultaneous experiments have been conducted with ultrasensitive radars at 3.2‐, 10.7‐, and 71.5‐cm wavelengths to observe ‘angel’ echoes from apparently clear air and to diagnose the scattering mechanism. Two types of echo layers have been found. Type I echo layers appear incoherent at long ranges or with wide beams but are seen to be composed of discrete coherent echoes when viewed with high resolution. The cross sections of the discrete targets vary roughly between the inverse first and second power of wavelength between 3 and 10 cm and between the inverse third and fourth power between 10 and 71 cm. Both the magnitude of the cross sections and the wavelength dependence are consistent with the hypothesis that the targets are large insects. Type II echo layers are composed of incoherent echoes at all ranges, show little or no wavelength dependence, and are generally undetectable at 3 cm. This type of layer is attributed to refractive index fluctuations which are maximized near stable layers—layers of maximum gradient in refractivity. Their reflectivities are consistent with mean‐square fluctuations in refractivity measured directly in similar layers and with that deduced from forward‐scatt

ISSN:0148-0227    

DOI:10.1029/JZ071i006p01537

年代:1966

数据来源: WILEY

摘要:

Analytical techniques were developed for the simultaneous quantitative measurement of two tracers, zinc sulfide and fluorescein, for atmospheric dispersion experiments. The zinc sulfide was determined by counting phosphorescence or fluorescence emission, and the solution fluorescence of fluorescein was measured. The method permitted simultaneous release of the tracers and collection on molecular air filters. Excellent results were obtained when certain experimental controls were placed on fluorescein generation. The physical behavior in the atmosphere of the resulting tracer materials was very similar. With the ability to disperse and analyze two tracers from different physical positions and expect them to behave the same, one can critically investigate certain atmospheric diffusion parameters.

ISSN:0148-0227    

DOI:10.1029/JZ071i006p01553

年代:1966

数据来源: WILEY

摘要:

A method is described for radar mapping of the surface of a planet. It is based on the use of a bistatic, continuous‐wave mode of radar operation between the earth and a spacecraft orbiting or flying by the planet. The interference pattern resulting from a plane wave illuminating the planet and the fields scattered by the planet is analyzed. It is shown that the power in this pattern contains components corresponding to a linear superposition of the elementary wavelets scattered by the surface, multiplied by a phasor. The conditions under which the elementary wavelets may be recovered from a measurement of the interference pattern are given. Matched filter detection is then used to recover the amplitude of the local currents on the surface associated with each wavelet. The response to a point scatterer is calculated. Resolutions of a few wavelengths in range and azimuth can theoretically be obtained. Analogous applications to other geophysical problems are suggeste

ISSN:0148-0227    

DOI:10.1029/JZ071i006p01559

年代:1966

数据来源: WILEY

摘要:

Experiments show that corpuscular radiation such as solar wind can sinter fine dust by producing displaced atoms which diffuse toward the surface of the grain. The estimated rate of churning of the topmost layer of lunar dust excludes sintering through sputtering. It follows that the dust is probably not loose but is partly coherent (0.5 dyne per particle), which increases its mechanical strength and decreases its mobility. Lower layers of dust are compacted by meteorite bombardment, and a close‐packed density is probably reached at a depth of a meter or so. Loads that will not commence to sink in loose and in sintered dust are calculate

ISSN:0148-0227    

DOI:10.1029/JZ071i006p01569

年代:1966

数据来源: WILEY

摘要:

Several parameters of water samples collected from Grand Bahama Bank in June 1962 and in June 1963 were measured. They include the partial pressure of CO2, the total dissolved inorganic CO2, the C14/C12ratio in the inorganic CO2, and the CaCO3saturation (by the Weyl saturometer). From these results absolute residence times of water on the bank up to 250 days have been computed. An average CaCO3precipitation rate of 50 mg/cm2yr is estimated. The rate of CaCO3deposition is proportional to the degree of supersaturation. By elimination of 0.6 mole of CO2for each mole of CaCO3precipitated, the bank water maintains a nearly constant CO2partial pressure. Combining measurements made with the Weyl saturometer with estimates of the observed activity product made it possible to estimate an activity product for aragonite of 0.80×10−8. This agrees satisfactorily with the value calculated from the free energies of the CO32−ion, Ca2+ion, and aragonite solid. The waters come onto the bank with an activity product of 1.68×10−8. The value falls to about 0.9×10−8for those samples residing longest on the bank. C14measurements on material centrifuged from ‘whitings’ indicate that their turbidity results from resuspension of sediment rather than in situ precipitation. The methods used here should have broad application to problems involving shallow‐water

ISSN:0148-0227    

DOI:10.1029/JZ071i006p01575

年代:1966

数据来源: WILEY

摘要:

The origin of the cold water that forms a layer at intermediate depths in the Gulf of St. Lawrence has been examined. Bathythermograph data were used for the period 1952–1962 and hydrographic station data for the period 1956–1962. The geographic distribution of temperature of the core of the layer shows that the cold water does not enter the gulf through Cabot Strait. The correlation of average winter air temperatures and cold layer temperatures indicates that in situ winter cooling is the dominant mechanism which produces the cold layer. The only external source is an inflow of Labrador water through Belle Isle Strait, indicated by current data and summer and autumn modifications to the layer. This source accounts for only 14% of the volume of the cold layer at the end of the cooling sea

ISSN:0148-0227    

DOI:10.1029/JZ071i006p01603

年代:1966

数据来源: WILEY

摘要:

The sediment distribution in the South Atlantic Ocean between 18 and 40°S is described from seismic reflection profiler and piston corer results. Three sedimentary provinces are recognized, each related to a dominant sedimentation process. Results of cores and earlier profiler traverses over the northern and equatorial mid‐Atlantic ridge are also presented. It is concluded that, although the late Cenozoic has been an active tectonic age for the northern and equatorial mid‐Atlantic ridge, there is no reason to believe that significant continental drift or expansion occurred during this time. The major phase of uplift of the Walvis ridge and Rio Grande rise is early Pliocene and is contemporaneous with the intense tectonic activity over the northern and equatorial mid‐Atlantic ridge. In contrast, the basins have been tectonically quiet during the time required to deposit the whole sedimentary sequence. The only major element still missing for reconstructing the history of the Atlantic Ocean, is the total geologic time represented by the sedimentary column in the

ISSN:0148-0227    

DOI:10.1029/JZ071i006p01611

年代:1966

数据来源: WILEY