The persistence of the southern annular mode (SAM) is studied during austral winter (June–September) and summer (December–March) using observations of the three-dimensional vorticity budget. Analysis of the relative vorticity tendency equation shows that convergence of eddy vorticity flux in the upper troposphere, coupled with a secondary circulation, constitutes a positive eddy feedback that a...

abstract: this paper presents the results of pullout tests on uniaxial geogrid embedded in silica sand under monotonic and cyclic pullout forces. the new testing device as a recently developed automated pullout test device for soil-geogrid strength and deformation behavior investigation is capable of applying load/displacement controlled monotonic/cyclic forces at different rates/frequencies an...

Circulation in the nearshore region, which is critical for material transport along coast and between surf zone inner shelf, includes strong vortical motions. The horizontal length scales vertical structure associated with motions are not well documented on alongshore-variable beaches. Here, a three-dimensional phase-resolving numerical model, Simulating WAves till SHore (SWASH), compared surfz...

in order to determine the synoptic pattern of heavy and extreme precipitations on the southern coast of the caspian sea, precipitation characteristics of the caspian region were investigated by the use of eight synoptic stations data. considering the percentage thresholds, the days with heavy and extreme precipitations were determined for a 10 year period (1994-2003). since more than 75% of day...

we prove the existence of steady 2-dimensional flows, containing a bounded vortex, and approaching a uniform flow at infinity. the data prescribed is the rearrangement class of the vorticity field. the corresponding stream function satisfies a semilinear elliptic partial differential equation. the result is proved by maximizing the kinetic energy over all flows whose vorticity fields are rearra...

A probabilistic clustering method is used to describe various aspects of tropical cyclone (TC) tracks in the Southern Hemisphere, for the period 1969–2008. A total of 7 clusters are examined: three in the South Indian Ocean, three in the Australian Region, and one in the South Pacific Ocean. Large-scale environmental variables related to TC genesis in each cluster are explored, including sea su...

An attempt is made to explain the mechanism of a hook-echo formation on the southwestern cdgc of an eastward-moving cumulonimbus cell. The conditions necessary for originating a hook-echo circulation through this proposed mechanism are: significant absolute vorticity within the subcloud layer, intcn,se updraft to bring the low-level moist air into the cloud, and a vertical wind shear which stee...

− Vertical coupling between shallow and deep mesoscale eddy processes in the southwestern Japan/East Sea is investigated using acoustic travel-time and bottom pressure measurements from a two-year deployment of an array of pressure-gauge-equipped inverted echo sounders. Canonical correlation analysis is applied to the simultaneously measured data to extract the coupled modes. The upper layer ex...

A mesoscale climate model (MCM) is developed from the Pennsylvania State University/ National Center for Atmospheric Research (PSU/ NCAR) MM5 model to simulate the West African summer monsoon. Results from the MCM are compared to observations, a reanalysis, and GCM output to show that the MCM reasonably simulates the West African monsoon climate and its variability, and improves on many shortco...