Dispersion of tracers in the atmosphere and ocean: Survey and comparison of experimental data

Abstract

Experimental data on the dispersion of clouds of inert tracers in the atmosphere are presented as a function of time after injection for a variety of altitudes from the planetary boundary layer to the turbopause, and for times ranging from minutes to months, extending the compilation of Hage (1964). The results on horizontal dispersion are compared with similar data for the upper ocean (depths less than 60 m) compiled by Okubo (1971). All the data show a strong scale dependence of the effective eddy diffusivity. Within the wide range of variability of the data in the lower atmosphere (0–30 km) there is no explicit altitude dependence of the effective mean eddy diffusivity at a given length scale σn, and all the data (for lower atmosphere, upper atmosphere, and ocean) show a scale‐dependent horizontal eddy diffusivity with a similar dependence on cloud size σn. Absolute differences between atmospheric and oceanic diffusivities are related to a variation in mean values of the turbulent dissipation rate e, and comparison is made with the classical analysis of Richardson (1926).

A Note on Water-Vapor Wind Tracking Using VAS Data on McIDAs

“…The lifetime depends on their dissipation by atmospheric turbulence, and is therefore a function of the size of the tracer and the eddy diffusivity of the atmosphere. Bauer (1974) in a review of experimental data on the horizontal spreading of inert tracers shows that a tracer with 100km width will have, on the average, a lifetime of one day. However, depending on the eddy diffusivity this feature can have a lifetime from three hours to more than three days.…”

Vertical dispersion of Lagrangian tracers in fully developed stably stratified turbulence

“…Mixing in stratified turbulence has been largely studied from an Eulerian point of view [19][20][21][22][23][24], but Lagrangian measurements with floaters are also common in the present, specially in oceanic measurements of waves and turbulence [2], where they are relevant to understand the transport of nutrients with applications for the fishing industry. Vertical dispersion is also important in the atmosphere [25], and particle dispersion has also been studied recently in atmospheric flows for forecasting purposes using Lagrangian models [26].…”

Turbulence structure of sea breeze front and its implication in air pollution transport ? Application of k-? turbulence model ?

“…However, as the first step of applying k--E turbulence model to sea breeze phenomena, the constant numbers are used here as described above. In view of the anisotropy of large-size eddy in the atmosphere and relative uniformity with altitude of observation-derived horizontal eddy diffusivity (Bauer, 1974), the horizontal edd tively fixed at a constant value of 1000 m*sy diffusivity KH was tenta-. The number is consistent with the cloud size of diffusing material of about 2 km in horizontalwidth in the atmosphere (Bauer, 1974); horizontal grid size used in the present numerical calculation, i.e., 2 km, is taken for the diameter of diffusing material cloud.…”