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Employing daily wind data from the ECMWF, we perform passive particleadvection to estimate the Lagrangian velocity correlation functions (LVCF)associated with the midlatitude tropospheric flow. In particular we decomposethe velocity field into time mean and transient (or eddy) components to betterunderstand the nature of the LVCF's. A closely related quantity, the absolutedispersion (AD) is also examined.  Given the anisotropy of the flow, meridional and zonal characteristics areconsidered separately. The zonal LVCF is seen to be non-exponential. In fact,for intermediate timescales it can either be interpreted as a power law of theform $\tau^{-\alpha}$ with $ 0<\alpha<1$ or as the sum of exponentials withdiffering timescales - both interpretations being equivalent. More importantlythe long time correlations in the zonal flow result in a superdiffusive zonalAD regime. On the other hand, the meridional LVCF decays rapidly to zero.Before approaching zero the meridional LVCF shows a region of negativecorrelation - a consequence of the presence of planetary scale Rossby waves. Asa result the meridional AD, apart from showing the classical asymptoticballistic and diffusive regimes, displays transient subdiffusive behaviour.Comment: Revised version. Submitted to JA

Lagrangian Velocity Correlations and Absolute Dispersion in the Midlatitude Troposphere