May 22 - July 30
Relationships Between Atmospheric Stability and Near-Storm Turbulence
Johnathan D. Heaton, Stacey Hitchcock, and Cole Hartman
What is already known:
- Turbulence poses significant hazards to aircraft and contributes to substantial operational costs for airlines.
- Many turbulence encounters occur near the tropopause while the plane is at cruise altitude and these encounters are often linked to thunderstorm activity.
- The risk of encountering moderate or greater convectively induced turbulence extends well beyond the visible boundaries of a thunderstorm.
- Static stability and wind shear are known to influence the development of turbulence.
What this study adds:
- This study explores atmospheric stability near turbulence reports and evaluates how static stability varies across turbulence events with respect to horizontal and vertical distance from convection.
- As a function of stability, relative risk of turbulence encounters decreases at large vertical distances and increases at small vertical separation distances from a thunderstorm.
- In regions of stronger static stability, moderate or greater turbulence generated by a thunderstorm can be encountered at greater horizontal and vertical distances from the storm itself.
Abstract:
Turbulence poses significant hazards to aircraft and contributes to substantial operational costs for commercial airlines. A substantial number of encounters occur near the tropopause while the plane is at cruise altitude (8-12 km), where the encounters are often linked to thunderstorm activity in the form of convectively induced turbulence (CIT). At this level, wind shear and static stability are the primary environmental characteristics that drive turbulence near thunderstorms. While the role of wind shear has been explored, the influence of atmospheric stability in the modulation of vertical and horizontal displacement of CIT remains less understood. This study gives particular attention to how turbulence in environments with different stability characteristics extends vertically above storm tops and horizontally by matching aircraft-based turbulence reports at cruise altitude with co-located ERA5 reanalysis dθ/dz grids from 2009 – 2014. The results from this study suggest that the increase of stability amplifies the distance over which the relative risk of encountering moderate or greater (MoG) turbulence remains elevated, especially below the tropopause.