95 



Expedition in 1920. In contrast, exploration has continued principally by air 

 as witness Byrd, Wilkins and others. 



These remarks are the preface to emphasize that the designed measure- 

 ments -- quantitative phase is all important; yet, I assure you, in the planning 

 of expeditions even now, the exploration -- inspection--qualitative point of view 

 often rises to threaten the real objectives of an expedition. Quantitative meas- 

 urements necessarily mean a correctly engineered vehicle, instruments and 

 techniques and qualified investigators. 



Sea Ice - Water System to System Interchange - A very considerable amount of 

 data has been gathered on the sea water phase beneath the ice. Obviously, the 

 sea water phase is influenced by the heat and salt exchange features of the ice 

 system. The observation techniques and sampling instruments are the same as 

 those for the conventional non-ice sea, except for the changes in actual handling 

 which result from cold weather and loss of mobility, and have been discussed in 

 the paper. The cost per datum is much higher for the ice covered than for the 

 non-ice sea in manpower, horsepower and dollars because of the vehicle -- ice- 

 breaker, submarine or aircraft -- that must be used; and because of the plain 

 hardship of the work. The loss of surface ship maneuverability, of course, 

 negates the customary procedures for underway devices, e.g. the GEK, or sound 

 propagation nneasurements. 



Sea Ice Equation of State - Methodology for study of the sea- ice phase, the 

 boundary layer itself, cannot be dismissed by borrowing from the oceanography 

 of non-ice seas. The physics of sea ice has no apparent direct parallel in other 

 geophysical problems to which we can turn, except for the observation techniques 

 of glaciology. 



Sea ice confounds description in that it is a mixture of many phases, 

 principally water crystals, sodiunn sulfate and sodiunn chloride crystals, brine 

 and air bubbles. The phases are always under action of heat flow from the sea 

 beneath to the atmosphere with resulting variable temperature gradient and are 

 also effectively influenced by the gravitational force field. It is a transient 

 phenomienon of irreversible processes, the true equilibrium states being the end 

 points of no ice before and after the freezing-melting process. 



Laboratory studies beginning with Ringer in 1907, and others since, are 

 studies in closed systems at one temperature giving equilibrium states of sea 

 ice. These plus the field measurements of Malmgren during the Maud Expedi- 

 tion provide the bulk parameters, heat conductivity, density, salt content, etc. 

 which permit calculation of interchange between the sea and the sea ice taken as 

 a system. 



Measurements have not been made of the structure within the sea ice sys- 

 tem. We cannot write down functions describing spatial distributions of the 

 phases within this mixture, nor the migration constants for any phase; for ex- 

 ample, brine cells or air bubbles. Cross-sections and corings have been taken 

 in the field which give single distribution patterns, but of course these observa- 

 tions are singularities because the functions describing the controlling parame- 

 ters fronn initial freezing to time of coring are unknown. Moreover, the obser- 

 vations procedure so disturbs the sample that subsequent study of the sample 

 will not give the in situ conditions. 



It is likely only lack of inaagination, but further field observations of sys- 

 tem properties as density, heat conductivity , tenaperature gradient, etc., seem 

 unwarranted until laboratory studies begin to give models of the internal mechan- 



