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Characteristics of Atmospheric Turbulence Retrieved From High Vertical‐Resolution Radiosonde Data in the United States
Author(s) -
Ko H.C.,
Chun H.Y.,
Wilson R.,
Geller M. A.
Publication year - 2019
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2019jd030287
Subject(s) - radiosonde , stratosphere , troposphere , tropopause , atmospheric sciences , environmental science , atmosphere (unit) , lapse rate , climatology , altitude (triangle) , turbulence , clear air turbulence , meteorology , geology , geography , mathematics , geometry
Abstract In this study, we estimate atmospheric turbulence in the free atmosphere in terms of the Thorpe scale ( L T ) 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 m 2 /s 3 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 L T multiplied by the cube of the Brunt‐Väisälä frequency ( N ), the regions of large ε are matched with large L T 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.