摘要:

Data from approximately 300 meteorological rocket soundings were analyzed to determine the seasonal and geographical variations in the general atmospheric acoustic structure. Data are confined mainly to midlatitude and subpolar categories, and a lesser amount to low latitude areas. Seasonal periods are defined according to the direction of flow in the upper stratosphere, between the spring and fall reversal periods. Results of this analysis show that the mean acoustic structure of the troposphere and stratosphere varies significantly in time and in space. The variations from winter to summer are significant for all latitudinal areas studied. Variations with longitude appear more significant as latitude increases. These deviations are adequate to permit large variations in atmospheric propagation of acoustic disturbances.

ISSN:0148-0227    

DOI:10.1029/JZ070i002p00249

年代:1965

数据来源: WILEY

摘要:

The problem of describing the pressure wave detected by an observer on the ground a few thousand kilometers from a low‐altitude nuclear explosion is formulated. To avoid numerical complications, the atmosphere is assumed to have an isothermal temperature distribution. With this simplification a Green's function for the problem is developed as an expansion in Legendre polynomials. This representation yields a time‐dependent pressure function which satisfies the condition of causality but which converges far too slowly to be useful. An alternative scheme, which is entirely equivalent, makes use of a Watson transformation and requires the determination of the set of Regge poles. The behavior of the complete Green's function is then shown to be dominated by the so‐called gravity wave mode, and the form of this approximate solution is deve

ISSN:0148-0227    

DOI:10.1029/JZ070i002p00257

年代:1965

数据来源: WILEY

摘要:

The Green's function of part 1 makes it possible to determine the time‐dependent pressure function at the observer's position in terms of the pressure generated by a nuclear explosion. It is convenient to treat the blast by using a surface, rather than a point source representation. This configuration permits the determination of the relationship between the energy of the explosion and the amplitude of the theoretical pressure pulse. The final step involves the performing of an inverse transformation to determine the time variation of the pressure wave trai

ISSN:0148-0227    

DOI:10.1029/JZ070i002p00271

年代:1965

数据来源: WILEY

摘要:

The optical continua of several lightning strokes are presented. In general, the continuum intensity of lightning increases toward the short wavelengths in the wavelength region from 5900 A to 3900 A. There appear to be no significant differences between the form of the intense streaks of continuum and the form of the dim continuum. The plots of continuum intensity versus wavelength have too great a curvature for the continuum to be due to either blackbody radiation or bremsstrahlung emitted at constant temperature. Possible explanations for the observed form of the continuum are advanced. The lightning continuum is found to be similar in form to the continuum of a long laboratory spark in air.

ISSN:0148-0227    

DOI:10.1029/JZ070i002p00279

年代:1965

数据来源: WILEY

摘要:

This study covers sea‐surface temperature anomalies at 27 Atlantic coast stations from Eastport, Maine, to Key West, Florida, for the years 1873–1961. The anomalies were computed using as a common base period the years 1950–1959. A secular warming trend peaking in the early 1950's is demonstrated. This trend was strongest in the north and diminished progressively toward the south, where a slight cooling trend was present at Key West. Seasonal differences in the trends are also pointed out. A comparison between the east and west coasts of the United States, and between the English Channel and the east coast of the United States, shows that a partial negative correlation exists between the anomalies of the east and west sides of the oceans. This negative correlation is greatest between northern stations and becomes less toward the south, where a positive correlation may exist at times. A short review is given of previous work on climatic change in the North Atlantic, and of work on the differences between the two sides of an ocean and their c

ISSN:0148-0227    

DOI:10.1029/JZ070i002p00283

年代:1965

数据来源: WILEY

摘要:

During the Equalant I program in 1963, the shipExplorerof the U. S. Coast and Geodetic Survey obtained measurements in the region of the Atlantic equatorial undercurrent between 15°W and 14°W. The average speed of the current as derived from drogue tracking at a depth of 50 m during phase I of the operation was 80 cm/sec and during phase II 75 cm/sec. Near the equator, observations of the undercurrent indicate meanders with a meridional amplitude of as much as 3 miles. Temperature and salinity sections across the undercurrent show clearly the spreading of the thermocline and the high‐salinity core, respectively, associated with this curr

ISSN:0148-0227    

DOI:10.1029/JZ070i002p00297

年代:1965

数据来源: WILEY

摘要:

A method is outlined whereby marker cans are used in colored sand columns to measure the ejecta and ground movements in the vicinity of a crater from a 20‐ton surface burst TNT detonation. It is shown that the use of marker cans greatly increases the data obtained from the sand columns, with comparatively little increase in the cost of the operation. Also, data are obtained in the form of displacement vectors which may be compared with the velocity vector field predicted by hydrodynamic theor

ISSN:0148-0227    

DOI:10.1029/JZ070i002p00305

年代:1965

数据来源: WILEY

摘要:

During September 1963, an experimental program of oceanographic observations was conducted 2200 km northeast of Hawaii (39°N, 148°W). One of the programs attempted was monitoring of hydroacoustic signals with hydrophones suspended from floats attached to Flip, a floating instrument platform. By comparing the arrival times of these events with those recorded on Sofar‐type hydrophones of the Pacific missile range network and at Point Sur, California, epicenters were established for 22 transients. Of these, two were identified as earthquakeTphases, two as acoustic arrivals from known underwater shots near the Aleutians, and 18 from underwater shots of unknown origin off Hokkaido, Japan. All the events came from the margins of the Pacific Ocean basin. No seaquakes from the Mendocino escarpment were recor

ISSN:0148-0227    

DOI:10.1029/JZ070i002p00311

年代:1965

数据来源: WILEY

摘要:

Results of twenty‐two seismic refraction stations over the northern mid‐Atlantic ridge are combined with earlier data to obtain a better definition of the gross features of the ridge. The seismic crustal structure is found to be the same at equal water depths. The crust on the flanks is an uplifted ocean basin crust which does not thicken when water depth decreases. The relation between water depth,wkm, and crustal thickness,Ckm, derived from the data isC= 0.80w+ 1.20. It indicates that in the absence of a compensating mass within the mantle one would expect a positive gravity anomaly of 120 mgal per km of height of the ridge above the basin floor. In the axial zone, a 5.8‐km/sec layer overlies a 7.3‐km/sec ‘upper mantle.’ Three different areas in the North Atlantic Ocean are compared with the east Pacific rise section and a genetic relationship is inferred from these comparisons. The northern mid‐Atlantic ridge is assumed to be in a later stage of evolution, the thickness and velocity of the basement layers being considered the best indicators of the degree of maturation of the mid

ISSN:0148-0227    

DOI:10.1029/JZ070i002p00319

年代:1965

数据来源: WILEY

摘要:

Seismic results have demonstrated that the crust under the mid‐ocean ridges is not thicker than under the ocean basins. Seismic results also show that the velocity in the mantle immediately under the ridge flanks is normal but that it is low under the axial zones, indicating an ‘anomalous mantle.’ The free‐air gravity anomaly over the entire ridge is close to 0 (within ±50 mgal), and consequently the gradients in the Bouguer anomaly are steep (sometimes approaching 1 mgal/km). In order for gravity and seismic results to agree, the anomalous mantle, which provides compensation in the axial zone of the ridge, is postulated to extend to the flanks below the normal mantle observed by seismic refraction measurements. A model computed on the basis of continuous gravity measurements over the mid‐Atlantic ridge and the seismic refraction results given in part 1 is presented. Alternative models that provide compensation at greater depth under the ridge flanks are ruled out by the steep gradients in the Bouguer anomaly. It is shown that a similar model can explain the seismic and gravity data obtained over the east Pacific rise but that a deeper compensation is not impossible because of the smaller gradients in the topography and Bouguer anomaly curves. A lack of correlation between the sharp east Pacific rise heat‐flow anomalies and the magnetic and gravity anomalies i

ISSN:0148-0227    

DOI:10.1029/JZ070i002p00341

年代:1965

数据来源: WILEY