In this study, we estimate atmospheric turbulence in the free atmosphere in terms of the Thorpe scale (LT) and eddy dissipation rate (ε) using U.S. high vertical-resolution radiosonde data over 4 years (September 2012 to August 2016) at 68 operational stations. In addition, same calculations are conducted for 12 years (October 2005 to September 2017) at four stations among the 68 stations. These high vertical-resolution radiosonde data have a vertical resolution of approximately 5 m and extend to an altitude of approximately 33 km, and thus, turbulence can be retrieved in the entire troposphere and lower stratosphere. There are thicker and stronger turbulent layers in the troposphere than in the stratosphere, with mean ε values of 1.84 × 10−4 and 1.37 × 10−4 m2/s3 in the troposphere and stratosphere, respectively. The vertical structure of ε exhibits strong seasonal variations, especially in the upper troposphere and lower stratosphere, with the largest ε values in summer and the smallest in winter. In the horizontal distribution of ε, large ε is seen mainly above the mountainous region in the troposphere, but this pattern is not seen in the stratosphere. Although ε is estimated by the square of LT multiplied by the cube of the Brunt-Väisälä frequency (N), the regions of large ε are matched with large LT regions where N is relatively small. For the time series of ε near the tropopause for 12 years at four stations, an annual variation is prominent at all stations without significant interannual variations. There is, however, a slightly increasing trend of ε at two stations.
Bibliographical noteFunding Information:
The authors thank three anonymous reviewers for many helpful comments and suggestions. This research was supported by the Korea Meteorological Administration Research and Development Program under Grant KMIPA KMI2018-07810. The radiosonde data were downloaded from the Stratosphere-troposphere Processes And their Role in Climate (SPARC) Data Centre at Stony Brook University, NY, USA (available online at http://www.sparc-climate.org/data-center/data-access/us-radiosonde) and the National Oceanic and Atmospheric Administration (NOAA) at 1401 Constitution Avenue NW, Washington, DC, USA (available online at ftp://ftp.ncdc.noaa.gov/pub/data/ua/rrs-data/). We also acknowledge using software that was generously given to us by Dr. Peter Love of the University of Tasmania.
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All Science Journal Classification (ASJC) codes
- Atmospheric Science
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science