摘要:

The American Geophysical Onion was established in 1919 as the American Committee of the International Union of Geodesy and Geophysics, and its Executive Committee is the Committee on Geophysics of the National Research Council. The objects of the Union are to promote the study of problems concerned with the figure and physics of the Earth, to initiate and coordinate researches which depend upon international and national cooperation, and to provide for their scientific discussion and publication. In the accomplishment of these objects, the Union is divided into sections following the plan of organization of the International Union of Geodesy and Geophysics. There are now seven sections, namely, (a) Geodesy, (b) Seismology, (c) Meteorology, (d) Terrestrial Magnetism and Electricity, (e) Oceanography, (f) Volcanology, and (g) Hydrology. A Section of Geophysical Chemistry was discontinued May 31, 1924, as the International Union had failed to provide such a Section; the Section of Hydrology was established November 15, 1930—matters pertaining to scientific hydrology referred to the American Geophysical Union had been previously looked after by special committees on Hydrolog

ISSN:0002-8606    

DOI:10.1029/TR016i001p00003

年代:1935

数据来源: WILEY

摘要:

As stated in its first report to the fourteenth annual meeting in 1933, the Committee has attempted to promote:(1) The application of geophysical methods to the study of oceanic basins and submerged continental margins, including the modification, perfection and invention of new apparatus and techniques.(2) The application of geophysical methods to the study of oceanic basins and submerged continental margins, including the modification, perfection. and invention of new apparatus and techniques. The discussion and organization of such oceanographic projects as appear to be of particular importance to the advancement ofgeodesyandgeology.It is expected that there will be complete cooperation between this Committee and the recently organized Committee on Geophysical and Geological Study of Continents, and it is to be noted that there are a number of reasons why this cooperation should develop naturally and rapidly, including:(1) The natural desire on the part of geodesists and geologists to make the greatest possible use of geophysicists and geophysical methods.(2) The common desire to procure fundamental geological data concerning the drowned continental margins, especially of North America, where they form the seaward extension of the great structural features commonly referred to as “geosynclines.”(3) The necessity of comparing the composition and structure of the rocks which underlie the oceanic basins and continents.(4) The geological importance of the study of the major island‐arcs, including the fore‐deeps.(5) The comparative study of contemporaneous and ancient marine se

ISSN:0002-8606    

DOI:10.1029/TR016i001p00006

年代:1935

数据来源: WILEY

摘要:

With the advent of acoustic methods in navigation and in hydrographic surveying, the field of accurate hydrographic surveying has been extended to several hundred miles off the coast, and many details of the ocean‐bottom now can be obtained and charted with far greater fidelity than was possible in the past. The discovery of submarine valleys at the edges of the continental shelves, and the development of the details and configuration of the ocean‐bottom in greater depths as aids to navigation, are opening up a wealth of information for the use of geologists and oceanographers. This paper has been prepared in answer to repeated inquiries as to the accuracy of soundings, that is, the probable errors of soundings both in depth and in position. In order that the soundings of various hydrographic surveys may be interpreted with complete understanding of their weights, some knowledge of the methods used in making such surveys is desirable. A brief description of the various methods is given for that purp

ISSN:0002-8606    

DOI:10.1029/TR016i001p00009

年代:1935

数据来源: WILEY

摘要:

The value of a better chart of this character than now exists is so well established that for the present purpose no argument regarding the desirability of the project need be advanced. Perhaps, however, the project needs to be defined. I conceive it to be the first pioneering step in an effort to secure a more accurate and more detailed knowledge of the configuration of the ocean‐basins. The accumulation of that knowledge will be a long and difficult process. We will never have it in adequate form until the maritime nations of the world have executed special surveying projects for its collection. It is useless to hope that the nations will undertake such projects at this time: in fact, the time when they will do so cannot now be visione

ISSN:0002-8606    

DOI:10.1029/TR016i001p00014

年代:1935

数据来源: WILEY

摘要:

About two years ago, at the request of the United States Hydrographic Office, work was begun by the Coast and Geodetic Survey on some special tables to take account of the indirect or Bowie effect in the isostatic reduction of gravity‐stations. The purpose of the tables was to make it possible to apply a correction at each gravity‐station for the difference in elevation between the actual geoid and the mathematical spheroid on which the gravity‐formula is based. The neglect of this effect has a tendency to produce systematic errors of opposite sign in the isostatic anomalies for land‐ and sea‐stations.The tables have now been completed and have been used to compute the indirect effect at about 1000 land‐ and sea‐stations. A fairly large part of the discrepancy between land‐ and sea‐anomalies has been eliminated by the use of this correction. Photographic copies of the tables have been sent to geodetic organizations in other countries and it is anticipated that the isostatic anomalies at many additional stations will be corrected in this manner within a short time. It is understood that Dr. Meinesz plans to compute this correction for all his sea‐stations except those in the West Indies for which the Coast and Geodetic Survey has already derived the

ISSN:0002-8606    

DOI:10.1029/TR016i001p00016-2

年代:1935

数据来源: WILEY

摘要:

The Special Committee on Geophysical and Geological Study of Continents was established because of the Executive Committee's conviction that the cooperative and “simultaneous application of geophysics and geology in an attack upon the major problems of Earth composition and evolution cannot fail to lead to great advances in Earth science”—a restatement of the conviction of all closely in touch with geophysics that the intimate blending of physics and geology will induce as profound a broadening and advance in Earth science as was wrought in chemistry some two decades ago, when physics and chemistry were blended—to the transformation of both.The Committee has accepted the responsibility thus given it to aid in this new wedding of the sciences, with a deep appreciation of the opportunity offered, and with a full enthusiasm for the work to be undertaken. The problems to be attacked are of great magnitude and of great importance, and the successful execution of this attack obviously will call not only for close team‐work within the American Geophysical Union but also will call for a broad, cordial, and interesting cooperation with other units of the National Research Council, and especially with its Division of Geology and Geography and the component unit

ISSN:0002-8606    

DOI:10.1029/TR016i001p00017

年代:1935

数据来源: WILEY

摘要:

The Committee—consisting of the chairmen of the seven sections—appointed to consider the possibilities of establishing a Journal of Geophysics finds that there is a great need for additional facilities for the publication at geophysical papers, especially in the fields of hydrology and seismology, and that, all told, the amount of material available seems to be sufficient for from 1000 to 2500 printed pages annually. Inasmuch as the cost per copy, where the number of copies is relatively small, is more or less inversely proportional to the number, first consideration was given to the possibility of securing a substantial number of subscriptions outside the membership of the Union. If the various geophysical organizations of the country, excluding those interested primarily from a commercial standpoint, would each subscribe for its membership, this would furnish a nucleus of a few thousand subscribers and would justify a detailed study of a procedure for financing, printing by the usual process, and distributing a monthly journal. Furthermore, by adopting a well‐selected format and pooling the contract for printing, distribution, and the handling of cash subscriptions with that of other societies using the same format, a substantial saving in these items could be effected. Accordingly, the American Meteorological Society and the Seismological Society of America were approached with the view to getting them to discontinue their publications and contribute what they are now putting into these publications in return for subscriptions to a Journal of Geophysics for their members. However, the American Meteorological Society replied promptly that they did not wish to give up their publication, and after several months the Seismological Society gave a similar

ISSN:0002-8606    

DOI:10.1029/TR016i001p00018-2

年代:1935

数据来源: WILEY

摘要:

The development of the experimental technique of radio measurements of upper atmospheric ionization during the past few years has greatly enhanced our knowledge of this region of the Earth's atmosphere. This region is now commonly termed the ionosphere. The radio methods of observation are based upon the phenomenon of refraction of electromagnetic waves in a medium containing free charges. The index of refraction of such a medium to the electromagnetic wave is dependent upon the number of charges in the medium, their mass, and the frequency of the propagated wave. The medium is therefore dispersive, and the higher frequencies, which are less deflected, are more penetrating. If the angle of incidence at the medium and the total deflection of the wave is known, the numbers of charges of any given mass required to give this deviation can be calculated, and a numerical value of ionization can be thus obtained. This number is usually expressed in equivalent numbers of electrons, although it must be understood that if particles of greater mass are present, a greater number of such particles will give, in general, similar effects. If the motions of the particles in the Earth's magnetic field are considered, however, a limiting ratio of electrons to heavier particles can be determined. In this way it is also possible to ascertain information concerning the strength of the Earth's magnetic field in the ionized region.

ISSN:0002-8606    

DOI:10.1029/TR016i001p00020-2

年代:1935

数据来源: WILEY

摘要:

Short‐wave radio character‐figure—It appears that, in order to get a character‐figure for short‐wave radio transmission, which is representative for the day, data must be taken over the whole 24 hours. Since the New York to London short‐wave telephone‐circuits are in practically continual use, suitable data may be obtained from them.It has been found that the field‐strengths of the received s1gnals taken at regular intervals do not furnish the best indication of the overall character of the day. If, however, the ratio at uncommercial time to total time, or the percentage of time lost to traffic is taken, a fairly good daily character‐f

ISSN:0002-8606    

DOI:10.1029/TR016i001p00026

年代:1935

数据来源: WILEY

摘要:

The atmosphere above about 180 km is heated by the absorption by molecular oxygen of the spectral region from 1200Å to 1800Å of sunlight. Calculation Indicates that the temperature of the atmosphere from 180 km to 300 km may increase 50° per hour In the daytime, which causes molecular oxygen, and possibly nitrogen, to dissociate into atoms. Due to the heating and dissociation there is a marked daily expansion, and nightly contraction, of these outlying leve

ISSN:0002-8606    

DOI:10.1029/TR016i001p00031

年代:1935

数据来源: WILEY