Climatology of Upper-Tropospheric / Lower-Stratospheric Turbulence From Aircraft Measurements of Eddy Dissipation Rate

Oral Presentation 

Climatological studies of atmospheric turbulence have become increasingly achievable since the 
introduction of automated turbulence reports from commercial aircraft. Turbulence intensity is 
measured as the cube root of the eddy dissipation rate (EDR), which is derived from spectral analysis 
of the vertical wind.

The NOAA AMDAR (Aircraft Meteorological Data Reports) archive as a central access point of the 
data comprises EDR measurements from the end of 2016 until today and is constantly updated. The 
flight routes of the airlines that contribute to the data set cover mainly the Northern Hemisphere, 
with measurements in the lower and middle troposphere during takeoffs and landings near airports, 
and a more area-wide coverage of the upper troposphere / lower stratosphere (UTLS) at cruising 
altitudes around 10 kilometers.

We present a multi-year analysis of the geographic and vertical occurrence frequency distribution of 
atmospheric turbulence in the northern hemispheric extratropical UTLS. The tropopause as the 
conceptual separation layer between the troposphere and the stratosphere makes for a natural 
reference layer for such an analysis, due to the distinct differences in turbulence frequency between 
the two atmospheric layers. The results of the study validate this approach, highlighting the 
importance of the distance from the tropopause as well as the tropopause variability associated with 
the seasonality of the large-scale dynamics in different regions. The quasi-horizontal analysis relative 
to the tropopause over the contiguous USA as one of the busiest aviation regions shows a 
dominating zonal gradient in occurrence frequencies, with a more complex multipole signal in the 
seasonality.