Baroclinic instability

Ghomiak, J. and Zhou, G., A numerical study of large amplitude baroclinic instabilities of flames, Twenty-Sixth Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, pp. 883-889,1996. 

A large long-living anticydonic eddy centered at 43°N and 34°E, in the area between the western and eastern cyclonic gyres (approximately abeam the southern extreme of the Crimea), was detected by the hydrographic survey of 1984 [6]. It was formed in September 1984 as a result of coalescence of two other anticyclones formed owing to baroclinic instability of the RC and to detachment of its meanders in the north (from the Crimean coast) and in the south (from the Turkish coast near Sinop). Its diameter exceeded 100 km, the maximum of the orbital geostrophic velocity was 25-45 cm/s, and the rate of the westward displacement was about 1 cm/s. Density and salinity anomalies related to this eddy were traced down to a depth of 1000 m and temperature anomalies were followed down to 300 m. 

In conclusion, this energetics analysis of the general circulation has illustrated the fundamental manner in which the midlatitude atmosphere responds to the sun s radiative forcing. The fundamental conservative principles of energy, mass, and potential vorticity have been combined with the quasi-geostrophic approximation and the theoretical concept of baroclinic instability to yield an explanation of many observed atmospheric phenomena. 

FIGURE 21.3 Baroclinic stability and instability (a) gently undulating upper airflow (b) meanders form in jetstream (c) strong waves form in upper airflow (d) return to a period of flatter flow aloft. 

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