Relation between variations in the intensity of the zonal circulation of the atmosphere and the displacements of the semi-permanent centers of action

Abstract

This paper attempts to interpret, from a single point of view, several at first sight independent phenomena brought into focus through the synoptic investigations carried on at the M assachusetts Institute of T echnology during the last few years. Since this interpretation is very largely based on a consideration of the changes in vorticity which must occur in vertical air columns which are displaced from one latitude to another and since such vorticity changes play a fundamental role also in Ek.man's general ocean current theory (1932), the results would appear to be of enough interest to physical oceanographers to warrant their publication in this journal. The particular phenomena brought out in the course of our studies are listed below. * This paper contains a preliminary report on certain phases of an investigation carried on at the M assachusetts Institute of T echnology in cooperation with the U. S. D epartment of Agricul ture, t he objective being t he development of adequate methods for weekly weather forecasts. The synoptic phases of this proj ct, involving the prepara ti on of da ily weather charts fo r the North rn H emisphere, is under the direc tion of Dr. H. C. Willett wi th the cooperation of Messrs. J. H olmboe and J. Namias. The statistical phases are under the direction of fr. L. P age with the cooperation of Mr. R. Allen, both of the Bureau of Agri ul tural Economics.

Eddy–Zonal Flow Feedback in the Southern Hemisphere

“…The variability of the zonal-mean state of the atmosphere has been a topic of research for a long time (Rossby 1939;Willett 1948;Namias 1950). Recently, as more reliable data became available, interest has shifted to the zonal-mean variability in the Southern Hemisphere (Trenberth 1979).…”

Data Assimilation

“…, which is the expression for phase-speed found by Rossby (1939). The Rossby or Rossby-Haurwitz waves are, to the first approximation, non-divergent waves which travel westward, the phase speed being greatest for the waves of largest scale.…”

Zonal Flow Regime Changes in a GCM and in a Simple Quasigeostrophic Model: The Role of Stratospheric Dynamics

“…Koo et al (2002) found that the two regimes are maintained by transient eddy forcing against surface friction. Attempts to explain variations in zonal flow intensity and zonal jet shifts in the NH (Rossby et al 1939;Namias 1950;Kravtsov et al 2006), as well as in the SH (see references above), have used two-or threelayer quasigeostrophic channel models [for an f-plane geometry, see Lorenz (1963); for b-plane studies, see Koo and Ghil (2002); Kravtsov et al (2005), and references therein] and primitive equation models with various degrees of vertical resolution (e.g., Yu and Hartmann 1993;Akahori and Yoden 1997).…”