Estimations from geostrophic trajectories of horizontal diffusivity in the mid‐latitude troposphere and lower stratosphere
作者:
R. J. Murgatroyd,
期刊:
Quarterly Journal of the Royal Meteorological Society
(WILEY Available online 1969)
卷期:
Volume 95,
issue 403
页码: 40-62
ISSN:0035-9009
年代: 1969
DOI:10.1002/qj.49709540304
出版商: John Wiley&Sons, Ltd
数据来源: WILEY
摘要:
AbstractZonal and meridional diffusivitiesKxxandKyyhave been found at mid‐latitudes from the spreads of sets of geostrophic trajectories at levels between 700 mb and 30 mb during each season of 1965. Values have been calculated using the relationshipR = e−PTcosqrfor the form of the corresponding Lagrangian autocorrelograms. In addition a similar set of Eulerian data has been analysed to obtain autocorrelograms and by comparison with the trajectory data Eulerian‐Lagrangian scale relationships have been obtained.The results show values ofKxxranging from 0·2.106to about 20.106andKyyfrom 0·2. 106to about 6.106m2sec−1. In both cases the lowest values are found in the summer stratosphere and the highest in the spring stratosphere and in the upper troposphere in winter. Their distributions principally follow that of the wind variances. Integral time scales are mainly between 5 and 30 hours meridionally and 10 and 50 hours zonally and are greatest in the stratosphere and lowest in the mid‐troposphere. The contributions of damping and harmonic effects to these time scales are discussed. Comparison of the Lagrangian and Eulerian time scales indicates a mean value β of about 0·6 for their ratio with the meridional values smaller than the
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