Predictability of fluid motions

Articles included in this volume range over a wide variety of topics. Many of the papers concern atmospheric predictability and are based upon direct observations, numerical circulation modeling and analyses of operational forecast skill. A topic of particular concern is predictability of atmospheric mesoscale phenomena. Traditional measures of predictability such as skill indices or the kinetic energy of the difference wind field between two flow phenomena are described including atmospheric blocking, the occurrence of persistent isolated vortices and the propagation of solitary waves. Efforts to diagnose predictability in the presence of such flows suggest concepts such as conditional predictability. Approaches to predictability based upon turbulence theory are described along with application of predictability concepts to turbulence phenomena. While loss of predictability is often associated with turbulence, and sometimes serves to define turbulence, similar loss of predictability can be effected by wave-wave interaction. Examples are seen in surface gravity wave and equatorial wave phenomena. For cases of quasigeostrophic dynamics, methods of functional analysis are used to establish rigorous bounds on predictability. Onset of chaos and loss of predictability are examined in spectrally truncated models with only a few degrees of freedom. One such study considers almost intransitivity and the role ofmore » eddy noise. Transitions to aperiodic motion are reported from various laboratory experiments.« less