The effect of shear instability on the transverse circulation in the atmosphere

• Main Author: Stewart, Homer Joseph
• Format: Others
• Published: 1940
• Online Access: https://thesis.library.caltech.edu/1931/1/Stewart_hj_1940.pdf; Stewart, Homer Joseph (1940) The effect of shear instability on the transverse circulation in the atmosphere. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/1FW3-YN51. https://resolver.caltech.edu/CaltechETD:etd-05222003-084939 <https://resolver.caltech.edu/CaltechETD:etd-05222003-084939>

In this paper it is shown that the shear fields on either side of the westerlies are dynamically unstable and will roll up to form discrete eddies. A study of the stable vortex systems into which these eddies might collect shows that a "vortex street" is stable for a certain range of the ratio of width to vortex spacing. It is also shown that a formation with vortices placed on the corners of a regular polygon is stable if the number of vortices is less than seven. This still holds if the effect of the shear field north of the westerlies is stimulated by a fixed polar cyclone. It further appears that with a strong general circulation, i.e. strong westerlies, only two or three high pressure cells should be found while the numbers, up to six, should be found with weaker circulations. This conclusion is verified by Northern Hemisphere mean pressure charts.