scholarly journals Spontaneous inertia‐gravity wave emission from a nonlinear critical layer in the stratosphere

2020 ◽  
Vol 146 (728) ◽  
pp. 1516-1528 ◽  
Author(s):  
Inna Polichtchouk ◽  
Richard K. Scott
Keyword(s):  
Gravity Wave ◽  
Critical Layer ◽  
Wave Emission

scholarly journals Gravity Wave Emission by Shear Instability

2019 ◽  
Vol 49 (9) ◽  
pp. 2393-2406 ◽  
Author(s):  
Carsten Eden ◽  
Manita Chouksey ◽  
Dirk Olbers
Keyword(s):  
Gravity Wave ◽  
Single Layer ◽  
Internal Gravity Waves ◽  
Shear Instability ◽  
Vertical Shear ◽  
Wave Signal ◽  
Wave Emission ◽  
Balanced Flow ◽  
Single Layer Model

AbstractGravity wave emission by geostrophically balanced flow is diagnosed in numerical simulations of lateral and vertical shear instabilities. The diagnostic method in use allows for a separation of balanced flow and residual wave signal up to fourth order in the Rossby number (Ro). While evidence is found for a small but finite gravity wave emission from balanced flow in a single-layer model with large lateral shear and large Ro, a vertically resolved model with moderate velocity amplitudes appropriate to the interior ocean hardly shows any wave emission. Only when static instabilities generated by the shear instability of the balanced flow are allowed can a gravity wave signal similar to the ones reported in earlier studies be detected in the vertically resolved case. This result suggests a relatively small role of spontaneous wave emission in the classical sense of Lighthill radiation, and emphasizes the role of convective or symmetric instabilities during frontogenesis for the generation of internal gravity waves in the ocean and atmosphere.

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