Preface 



Up to the present time, no adequate book has existed from which a 

 meteorologist could readily obtain information as to findings in physical 

 oceanography that have bearing upon problems of the atmosphere. Nor 

 has any text been available that, besides describing the methods used in 

 physical oceanography, also contained a summary of our present knowl- 

 edge of the current systems of the oceans and of the processes that main- 

 tain the currents. It is to fill these needs that this book has been wTitten. 



The processes of the sea surface are of the most direct meteorological 

 significance. Consequently, the temperature, the salinity, the currents 

 of the upper layers of the oceans, and the factors that control the existing 

 conditions are the features which have been emphasized. Since these 

 cannot be fully understood without taking the subsurface conditions into 

 account, the deep-water circulation of the oceans has also been discussed. 

 The theories of the large-scale ocean currents and of the wind-driven 

 currents have been included, because in oceanography the application 

 of hydrodynamics is of fundamental importance and because the treat- 

 ment is similar to that of corresponding problems in the atmosphere. 

 Tides and tidal currents have not been discussed, because the tides have 

 not been shown to be of meteorological significance. Similarly, internal 

 waves in the oceans have not been dealt with, but wind waves have been 

 included. 



The theoretical discussion of the dynamics of the ocean currents and 

 the factual information from many ocean areas are as yet incomplete, and 

 therefore it may be premature to generalize. Nevertheless, it has been 

 attempted to overcome difficulties arising from differences in interpreta- 

 tion of incomplete data by placing emphasis on application of the equation 

 of continuity in the description of the ocean circulation. 



No references to original papers are given, but several standard works 

 are listed, some of which contain numerous references to meteorological 

 and oceanographic literature. 



I am much indebted to my colleagues, Messrs. Johnson and Fleming, 

 for their permission to make use of many parts of our common book, now 

 in press: The Oceans: Their Physics, Chemistry, and General Biology. I 

 am greatly obliged to Mr. John A. Fleming, Director of the Department 

 of Terrestrial Magnetism, Carnegie Institution of Washington, for allow- 



