SEOT. 2] LARGK-SCALE INTERACTIONS 89 



restless motion upon a rotating spheroidal planet. That the basic problems and 

 questions in the sciences of sea and air are so similar is thus, superficially, not 

 surprising. These are epitomized in two closely related basic puzzles : first, the 

 coexistence in each of many interacting scales of motion, from tiny eddy to 

 planetary gyre, supplying and removing energy from one another, coupled in 

 loops within loops of stable and unstable interaction, inseparable and non- 

 linear, where the whole is frequently spectacularly different from the sum of its 

 separate parts. Second, the streakiness of motion in each : restricted regions of 

 concentrated fast streams imbedded in surrounding stagnation, irrespective of 

 driving force, are characteristic of both sea and air, in systems ranging in size 

 from seaweed streaks in harbor waters, through long lines of cumulus clouds 

 and temperature striations in the Antarctic ocean "convergence", up to the 

 famous planetary jets of Gulf Stream and circumpolar westerlies, themselves 

 striated when "fine structure" is examined. 



These basic problems could be lumped into the broad category called "turbu- 

 lence", which, however, smears over the importance and fascination of mechan- 

 ism, and to some would imply a randomicity, where perhaps most significant 

 is the very opposite : an organized departure from purely random motion, an 

 organization with transport and release of energy as its guiding principle. 



That many interacting scales of motion and streakiness on all these scales 

 are basic features of rotating f)lanetary fluids has been beautifully demonstrated 

 by the recent model experiments [popularly referred to as "dishpan" studies 

 (see, for example, Fultz, 1951 ; Stommel, Arons and Faller, 1958)], used equally 

 by meteorologists and oceanographers to illuminate their problems and to 

 select, from a vast complexity, the important features of the fluid motion. These 

 rotating dishpan studies are only one example of the third major linkage be- 

 tween atmospheric and oceanic science, namely the common structure and 

 foundation of the tools of investigation, and the community and exchange 

 among the investigators. With the inception of nonlinear hydrodynamics and 

 the introduction simultaneously of the high-speed computers, both meteorology 

 and oceanograf)hy are graduating from the "linearized" age of science, whose 

 limitations almost always precluded fruitful discussion of energy transforma- 

 tions and thus of the fundamentals of heat-driven fluid-engines. These develop- 

 ments, plus some treatments of the fully turbulent hydrodynamic equations 

 (still restricted to simplified prototype models), offer hope that the emphasis 

 may now begin to shift from steady-state analyses of purely dynamic, linear 

 systems in which energy sources, sinks and transports are perforce ignored to 

 at least idealized cases of growing and decaying thermal circulations in which 

 conversions and transports are primary, giving hope at last of modelling the 

 most important interaction between sea and air, namely energy exchange. 



But theoretical models and analytical tools require critically made measure- 

 ments to test their predictions, to build and improve their foundations by 

 comparison with nature. Meteorology and oceanography are fundamentally 

 still observational sciences, with primary phenomena often difficult or im- 

 possible to scale in laboratory experiment or to analj'ze by differential 



