Search Results

You are looking at 1 - 10 of 25 items for :

  • Jets and Annular Structures in Geophysical Fluids (Jets) x
  • All content x
Clear All
Keiichi Ishioka, Jitsuko Hasegawa, and Shigeo Yoden

1. Introduction Spontaneous zonal jet formation is a well-known significant feature in two-dimensional β -plane turbulence ( Rhines 1975 ; Vallis and Maltrud 1993 ). The formation itself is considered due to the upward cascade of energy that favors a zonal structure because of the β term. Vallis and Maltrud (1993) found asymmetry between eastward and westward jet profiles that emerged from turbulent states in the forced-dissipative numerical experiments. That is, eastward jets are

Full access
Peter L. Read, Yasuhiro H. Yamazaki, Stephen R. Lewis, Paul D. Williams, Robin Wordsworth, Kuniko Miki-Yamazaki, Joël Sommeria, and Henri Didelle

1. Introduction The banded organization of clouds and zonal winds in the atmospheres of the outer planets has long fascinated atmosphere and ocean dynamicists and planetologists, especially with regard to the stability and persistence of these patterns. This banded organization, mainly apparent in clouds thought to be of ammonia and NH 4 SH ice, is one of the most striking features of the atmosphere of Jupiter. The cloud bands are associated with multiple zonal jets of alternating sign with

Full access
P. B. Rhines

1. Introduction and potential vorticity background Solar radiation bathes the earth, varying smoothly with latitude, and yet the circulations it produces are filled with small-scale transient eddies, jet streams, and boundary currents. Zonal jet stream generation occurs with thermally forced circulations on a simple, smooth globe. Instability of zonally symmetric, baroclinic circulations is often given as a primary reason for these synoptic-scale features, which are amplified or generated ab

Full access
Cegeon J. Chan, R. Alan Plumb, and Ivana Cerovecki

1. Introduction In this paper, we describe some characteristics of zonal jets in a model of a zonally reentrant ocean, bounded by zonal walls at the equator and 50°S, driven by a steady eastward wind stress that peaks in middle latitudes. The model simulation was run as a test bed for ideas on eddy transport, and its major, climatological, characteristics are described elsewhere (Cerovecki et al. 2007, manuscript submitted to J. Phys. Oceanogr. , hereafter CPH). Here we focus on the time

Full access
Yohai Kaspi and Glenn R. Flierl

1. Introduction Strong zonal winds dominate the atmospheres of the four big outer planets of the solar system. All four planets exhibit latitudinal banding and strong jet streams, where the wind velocities on Saturn are the strongest reaching more than 400 m s −1 near the equator, and Jupiter has the most structure with at least six alternating bands of east–west winds in each hemisphere ( Ingersoll 1990 ; Porco et al. 2003 ). Unlike Earth, the solid centers are small fractions of the giant

Full access
D. G. Dritschel and M. E. McIntyre

stratified, rotating systems, are three interrelated phenomena on which this review will focus: first the spatial inhomogeneity of PV mixing by layerwise-two-dimensional turbulence, second the common occurrence of “antifrictional” or upgradient horizontal stresses , and third the spontaneous creation and self-sharpening, or narrowing, of jets. The three phenomena are all illustrated by the typical jet-sharpening scenario sketched in Fig. 1 . The sketch was originally made to help understand the

Full access
Shin Takehiro, Michio Yamada, and Yoshi-Yuki Hayashi

numerical experiments of decaying turbulence on a rotating sphere with full spherical geometry. They investigated the statistical tendency for the development of a flow field from a random set of initial states and found that a banded structure of zonal flows emerges and that there was a tendency for circumpolar flows to be easterly jets. However, especially in cases when the rotation rate is large, their initial fields are in a state of “wave turbulence”; that is, the initial kinetic energy spectrum is

Full access
Yoshi-Yuki Hayashi, Seiya Nishizawa, Shin-ichi Takehiro, Michio Yamada, Keiichi Ishioka, and Shigeo Yoden

mean flows and recognized its persistent characteristics. A peculiar feature found by Yoden and Yamada (1993) is that, in addition to the appearance of the banded structure of zonal mean flows, intense easterly (retrograde) circumpolar jets tend to emerge especially at large rotation rate. The appearance of an easterly circumpolar jet has been confirmed as a robust feature in decaying turbulence, while in forced turbulence, its appearance seems to depend on the forcing scale. When the forcing

Full access
Yuji Kitamura and Keiichi Ishioka

fundamentals for examining large-scale structures of atmospheric motions. Two-dimensional turbulence and its rotational effects have been studied to investigate the nonlinear dynamics in the atmosphere and ocean by many authors. Rhines (1975) first found that a zonal structure spontaneously becomes dominant in 2D turbulence on a β plane. The meridional scale of the zonal jet is characterized by the scale L β = 2 U 0 / β ( U 0 stands for a representative velocity), which is called the Rhines scale

Full access
Francis Codron

Solomon 2002 ), the observed Southern Hemisphere response to El Niño ( Seager et al. 2003 ; L’Heureux and Thompson 2006 ), as well as the modeled response to greenhouse gas increase ( Kushner et al. 2001 ) or ozone depletion ( Gillett and Thompson 2003 ; Arblaster and Meehl 2006 ). From the physical point of view, annular modes have been studied in association with the dynamics of zonally averaged wind fluctuations. The variability of a zonal eddy-driven jet is dominated by a dipolar, equivalent

Full access