Chapter 6 Scientific Limitations 



The panel finds that we are at an early stage in 

 the development of a scientific capability for 

 "ocean enyironmental prediction." 



Until the start of World War II, predictions of 

 ocean parameters were essentially Umited to those 

 periodic phenomena with well-understood physical 

 mechanisms: tides as well as the motion of easily 

 observed physical singularities such as icebergs. 

 Tidal predictions are still imperfect; improvements 

 are under way to take account of nonlinear effects 

 and transients caused by surface winds and local 

 pressure changes. Iceberg forecasting has improved 

 because of the improved data available. Since the 

 end of World War II (and, in at least one of the 

 cases, stimulated by war-time research) methods 

 have been developed for:' 



—Surface-wave prediction based on observations 

 and predictions of surface winds 



—Warnings of tsunamis produced by earthquakes, 

 detectable at great distances. 



Further, at the Navy's Fleet Numerical Weather 

 Central, Monterey, California, computer programs 

 have been developed to provide surface wave 

 predictions. Other forecast parameters describe the 

 temperature structure of the oceans for sound 

 propagation prediction. This program is based on 

 an empirical approach and additional effort is 

 required to establish a firmer scientific basis. 

 Further improvement in wave prediction is tied 

 closely to the prediction of the wind field in the 

 lower layers of the atmosphere, for which more 

 observations of the atmosphere over the oceans are 

 required. Similarly, prediction of the near-surface 

 thermal structure is strongly related to the ex- 

 change of heat between atmosphere and ocean. 



A wide range of time-dependent phenomena 

 occur in the ocean; there is really no reason why 

 ocean "weather" is not as varied and complex as 

 the weather in the atmosphere.^ Internal gravity 

 waves, inertial motions associated with the earth's 

 rotation, turbulence, meanders in the Gulf Stream 



Panel on Oceanography, President's Science Ad- 

 visory Committee, Effective Use of the Sea, The White 

 House, Washington, D.C. (June 1966). 



'^Ibid. 



and other currents, and fluctuations in surface 

 temperature over large areas are all examples of 

 time-dependent fluctuations. These phenomena 

 are not yet adequately observed nor their dy- 

 namics understood; they therefore cannot be 

 accurately predicted. 



I. SEA-AIR INTERACTION 



Research on the interactions between the at- 

 mosphere and the oceans is necessary for progress 

 in ocean and weather forecasting. A successful 

 research program in this field could lead not only 

 to improved weather forecasting, but also, since 

 the upper layer of the ocean and the atmosphere 

 are both part of the same physical system, to the 

 abUity to forecast conditions in the upper layer of 

 the ocean. 



A theoretical upper limit for predicting the 

 behavior of individual mid-latitude weather details 

 is estimated to be:' 



about two weeks in winter and somewhat longer in 

 summer; the practical upper limit is now about 

 three or four days . . . . A reasonable estimate for 

 the practical limit in the foreseeable future seems 

 to be about one week, with the possibility that 

 some trends for temperature and precipitation 

 could be predicted for the second week. 



For these time intervals the fluxes of energy, 

 momentum, and water vapor to and from the 

 atmosphere, neglected for short-range forecasting, 

 become significant. Because these exchanges occur 

 on scales of motion very much smaller than the 

 scale of any existing or economically-feasible 

 observing system, a major goal of air-sea inter- 

 action research is to relate these fluxes to data 

 collected on a much larger scale. 



Boundary-flux estimates representative of areas 

 of about 250,000 square kilometers and time 

 intervals of 3 to 12 hours may be required."* 



Committee on Oceanography, National Academy of 

 Sciences - National Research Council, Oceanography 

 1966 -Achievements and Opportunities, NAS-NRC, Wash- 

 ington, D.C. p. 112. 



Panel on International Meteorological Cooperation, 

 National Academy of Sciences— National Research Council, 

 The Feasibility of a Global Observation and Prediction 

 Experiment, NAS-NRC, Washington, D.C. (1966). 



11-47 



