Journal
NONLINEAR PROCESSES IN GEOPHYSICS
Volume 27, Issue 1, Pages 147-173Publisher
COPERNICUS GESELLSCHAFT MBH
DOI: 10.5194/npg-27-147-2020
Keywords
-
Categories
Funding
- UK Science and Technology Research Council [ST/K502236/1, ST/K00106X/1, ST/I001948/1]
- UK Engineering and Physics Sciences Research Council [EP/K029428/1]
- UK Natural Environment Research Council
- UK Met Office
- EPSRC [EP/K029428/1] Funding Source: UKRI
- STFC [ST/S000461/1, ST/K00106X/1, ST/I001948/1, ST/N00082X/1] Funding Source: UKRI
Ask authors/readers for more resources
Baroclinic and barotropic instabilities are well known as the mechanisms responsible for the production of the dominant energy-containing eddies in the atmospheres of Earth and several other planets, as well as Earth's oceans. Here we consider insights provided by both linear and non-linear instability theories into the conditions under which such instabilities may occur, with reference to forced and dissipative flows obtainable in the laboratory, in simplified numerical atmospheric circulation models and in the planets of our solar system. The equilibration of such instabilities is also of great importance in understanding the structure and energetics of the observable circulation of atmospheres and oceans. Various ideas have been proposed concerning the ways in which baroclinic and barotropic instabilities grow to a large amplitude and saturate whilst also modifying their background flow and environment. This remains an area that continues to challenge theoreticians and observers, though some progress has been made. The notion that such instabilities may act under some conditions to adjust the background flow towards a critical state is explored here in the context of both laboratory systems and planetary atmospheres. Evidence for such adjustment processes is found relating to baroclinic instabilities under a range of conditions where the efficiency of eddy and zonal-mean heat transport may mutually compensate in maintaining a nearly invariant thermal structure in the zonal mean. In other systems, barotropic instabilities may efficiently mix potential vorticity to result in a flow configuration that is found to approach a marginally unstable state with respect to Arnol'd's second stability theorem. We discuss the implications of these findings and identify some outstanding open questions.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available