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Título: Space-time correlations and Taylor's hypothesis for rainfall
Autores: Potvin, Guy
Fecha: 1993
Publicador: McGill University - MCGILL
Fuente:
Tipo: Electronic Thesis or Dissertation
Tema: Physics, Atmospheric Science.
Descripción: A theoretical analysis of the space-time correlation function for rainfall and its relationship to Taylor's hypothesis is presented. The analysis assumes a homogeneous and stationary random field being advected past a fixed coordinate system with a constant velocity. Within the moving reference frame, the random field is assumed to possess quadrant symmetry. The concept of space-time isotropy is defined relative to a velocity. This is called the intrinsic velocity and represents a kinematic characteristic of the storm system apart from the advection velocity. A radial space-time correlation function is defined over a range of scales where the intrinsic velocity remains constant. The effect of the intrinsic velocity on Taylor's hypothesis is examined and an alternative is proposed. The effect of spatial resolution is evaluated theoretically on a model space-time correlation. The results from the theoretical calculation are compared with those obtained from two rain events. The radial space-time correlation functions of the rain events vary as expected with spatial resolution, but the intrinsic and advection velocities are inconclusive. The uncertainty for the intrinsic and advection velocities does not allow for a clear relationship with spatial resolution. Nor does it allow a clear determination of the effect of spatial resolution on the validity of Taylor's hypothesis. The intrinsic velocity may be approximated as constant over a certain range of time scales (15 to 70 min). Of the cases considered, the effect of the internal storm development on Taylor's hypothesis is slight. Therefore, a 'frozen turbulence' model for Taylor's hypothesis is still a good approximation.
Idioma: en