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Eddy Length Scale Response to Static Stability Change in an Idealized Dry Atmosphere: A Linear Response Function Approach
  • Pak Wah Chan,
  • Pedram Hassanzadeh,
  • Zhiming Kuang
Pak Wah Chan
Harvard University

Corresponding Author:pchan@g.harvard.edu

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Pedram Hassanzadeh
Rice University
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Zhiming Kuang
Harvard University
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The response of mid-latitude equilibrated eddies’ length scale to static stability has long been questioned but not investigated in well-controlled experiments with unchanged mean zonal wind and meridional temperature gradient. With iterative use of the linear response function of an idealized dry atmosphere, we obtain a time-invariant and zonally-uniform forcing to decrease the near-surface temperature by over 2 K while keeping the change in zonal wind negligible (within 0.2 m/s). In such experiments of increased static stability, energy-containing zonal scale decreases by 3-4%, which matches with Rhines scale decrease near the jet core. Changes in Rossby radius (+2%), maximum baroclinic growth scale (-1%) and Kuo scale (0%) fail to match this change in zonal scale. These findings and well-controlled experiments help with better understanding of eddy-mean flow interactions and hence the mid-latitude circulation and its response to climate change.
27 May 2021Published in Journal of the Atmospheric Sciences. 10.1175/JAS-D-21-0044.1