We present a theory of zonal flow drift wave dynamics. Zonal flows are generated by modulational instability of a drift wave spectrum, and are damped by collisions. Drift waves undergo random shearing-induced refraction, resulting in increased mean square radial wavenumber. Drift waves and zonal flows together form a simple dynamical system, which has a single stable fixed point. In this state,...

Zonal flows, which means azimuthally symmetric band-like shear flows, are ubiquitous phenomena in nature and the laboratory. It is now widely recognized that zonal flows are a key constituent in virtually all cases and regimes of drift wave turbulence, indeed, so much so that this classic problem is now frequently referred to as “drift wave-zonal flow turbulence.” In this review, new viewpoints...

[1] We present nightside observations of tropospheric carbon monoxide in the southern hemisphere near the 35 km height level, the first from Venus Express/Visible and Infrared Thermal Imaging Spectrometer (VIRTIS)-M-IR. VIRTIS-M data from 2.18 to 2.50 mm, with a spectral resolution of 10 nm, were used in the analysis. Spectra were binned, with widths ranging from 5 to 30 spatial pixels, to incr...

Abstract The latitudinal precipitation distribution shows a secondary peak in midlatitudes and minimum the subtropics. This is widely attributed to descending branch of Eulerian Hadley cell. study however that aligns more closely with transformed mean (TEM) vertical motion. In Northern Hemisphere winter, maximum TEM descent (ascent) (maximum) are collocated at ~20°N (~40°N). subtropical mostly ...

High resolution simulations are used to map out the detailed structure of two long-lived stable belts of asteroid orbits in the inner Solar system. The Vulcanoid belt extends from 0.09 to 0.20 astronomical units (au), though with a gaps at 0.15 and 0.18 au corresponding to de-stabilising mean motion resonances with Mercury and Venus. As collisional evolution proceeds slower at larger heliocentr...

GTC gyrokinetic particle simulations of DIII-D discharge #142111 near 525ms find a radial localization of toroidal Alfven eigenmode (TAE) due to the modification of the MHD mode structure, i.e., nonperturbative contribution by energetic particles (EP). The EP-driven TAE has a radial mode width much smaller than that predicted by the MHD theory. The TAE radial position peaks at and moves with th...

By using a hsp70-Ubx fusion gene, we have ectopically expressed a Ubx product in the embryonic head primordia and studied the developmental effects on the larval head. We find that after high and persistent levels of Ubx product, the head is replaced by three (C1, C2 and C3) abdominal-like denticle belts. The C2 and C3 belts are the homeotic transformations of parasegments 1 and 2, respectively...

BACKGROUND AND AIMS The formation of zonal communities may be attributed to differences in germination across the community and to timing of germination of seeds present in the seed bank. Our goals were two-fold: (1) to assess the annual germination pattern of Spergularia marina; and (2) to determine whether germination of S. marina differed across zonal communities. METHODS Fresh seeds were ...