Latitudinal and Topographical Variabilities of Free Atmospheric Turbulence From High- Resolution Radiosonde Data Sets

摘要

This study aims to determine the latitudinal and topographical dependencies of turbulent flow by applying Thorpe analysis to abundant high-resolution radiosonde data sets. Results show that turbulent energy dissipation rates are lognormally distributed with average central values of 2.7 × 10~(-4) and 2.9 × 10~(-4) m~2/s~3 in the troposphere and stratosphere, respectively. Moreover, they exhibit similar vertical variations at different latitudes from the lower free troposphere up to the tropopause region. Dissipation rates are quantitatively comparable at all latitudes but do exhibit significant seasonal variability. Thus, these rates have apparent seasonal cycles at middle latitudes but weak cycles at low and high latitudes. The influence of terrain is an important feature of turbulent motions. Turbulent activities over mountainous topographies exhibit larger variances than those over flat terrains in the lower troposphere and more outstanding enhancements in the tropopause region. In general, these results are comparable with those of radars in terms of magnitude, and the differences between them can be related to different measurement principles.