2 edition of Unstable jet flow along zonal ridge topography found in the catalog.
Unstable jet flow along zonal ridge topography
Donna Lynn Witter
Written in English
|Statement||by Donna Lynn Witter.|
|The Physical Object|
|Pagination||183 leaves, bound :|
|Number of Pages||183|
Atmospheric circulation is the large-scale movement of air and together with ocean circulation is the means by which thermal energy is redistributed on the surface of the Earth.. The Earth's atmospheric circulation varies from year to year, but the large-scale structure of its circulation remains fairly constant. Global Climate meets dynamics in the fluids laboratory Peter Rhines Barotropization of a two-layer zonal jet (Rhines The Sea ) upper layer lower layer large-scalePV field due to enabling unstable eddy/mean flow development and access of mean-flow energy
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And vorticity balances are considered as functions of along-stream variations in ridge height and width during the fully turbulent, statistically steady phase of numerical simulations.
Along-stream variations in topography steer the time-mean jet, induc-illg alollg-stream modulations in ambient potential vorticity gradient at the location of the jet.
Unstable jet flow along zonal ridge topography book Unstable jet flow along zonal ridge topography. effects of zonal ridge topography\ud on zonal oceanic jet flow are investigated. Unstable wave properties and the\ud dynamics of eddy-mean flow interaction are evaluated as a function of topographic\ud geometry using a 2-layer, quasigeostrophic, nonlinear, finite-difference, numerical\ud.
Unstable jet flow along zonal ridge topography book downstream of zonal modulations of ridge height or width. Unlike ﬂows over ﬂat-bottom topography, the zonal distribution of unstable mode growth rate.
The flow is said to be barotropically unstable, because even pure, non-meandering zonal flow, if perturbed just a little bit from its starting latitude, will respond by meandering north and south.
This north-south (meridional) oscillation of the west-to-east jet stream creates the wavy flow pattern we call a Rossby wave or a planetary wave. Unlike flows over flat-bottom topography, the zonal distribution of unstable mode growth rate is negatively correlated with velocity shear.
Analysis of area-averaged mean-to-eddy energy conversions shows that zonal modulations of topography modify the regime of flow by: As a result, the largest eddy energies occur downstream Unstable jet flow along zonal ridge topography book zonal modulations of ridge height or width.
Unlike flows over flat-bottom topography, the zonal distribution of unstable mode growth rate is negatively correlated with velocity shear. Transports of each of these flows is on the order of several Sverdrups. Farther from the equator, within 15–20° of the equator and above the topography of the mid-ocean ridges (above m), the intermediate and deep circulation remains dominantly zonal compared with flow.
Warm air pushing northwards delineates the high-pressure ridges. Cold air flooding southwards forms the low-pressure troughs. The two components to jet stream flow - west-east and north-south - are referred to as zonal and meridional flows respectively.
The straighter a Unstable jet flow along zonal ridge topography book line the jet stream takes, the more zonal it is said to be. The zonal topographic slopes of the ridge lead to the formation of a system of currents, consisting of mesoscale eddies, meridional currents over the ridge, and multiple zonal jets in the far field.
PDF | The interaction between an Antarctic Circumpolar Current-like channel flow and a continental shelf break is considered using eddy-permitting | Find, read and cite all the research you. respectively, as illustrated in Fig. The near-zonal solution is close in amplitude and spatial pattern to the forcing jet and is influenced very little by the topography, while the blocked solution is strongly affected by it.
In the blocked-flow solution, a ridge is located upstream of the “mountains”, similar to. On the f -plane, the interaction between the vortex and the equilibrated jet cannot be unambiguously detected by the dominant wavelength in the spectrum. In physical space, it is equally difficult to identify the formation of a heton south of the jet, because of the mesoscale activity due to baroclinic by: Mixing coefficient as a function of depth in an unstable jet in a channel (Treguier, ).
Eke is maximum at the surface Eddy effects on a zonal jet (6) Large scale topography Unstable jet flow along zonal ridge topography book has a very strong influence Top: flat-bottom channel In the presence of a large scale PV gradient, eddies tend to generate a flow along f/h contours (Rhines.
Blocked, continuously stratified, crest-controlled flows have hydraulically supercritical downslope flow in the lee of a ridge-like obstacle. The downslope flow separates from the obstacle and, depending on conditions further downstream, transitions to a subcritical state.
Physical Mechanisms of Nonlinear Equilibration of a Baroclinically Unstable Jet over Topographic Slope Behind the wave packet deep eddies form a nearly zonal circulation which stabilizes the jet. The main equilibration mechanism is homogenization ofthe lower layer potential vortic ity by deep eddies.
Ginis I., Frolov S.A. ( Author: G. Sutyrin, I. Ginis, S. Frolov. Zonal jets on a beta plane. The jet impinges on a ridge over which the depth d* decreases If order to track the width of the current as the jet passes over the topography, it is necessary to relate w to d.
This relation is given by (), which can be written as in the. The topography of this region is dominated by a single ridge (the Southeast Indian Ridge) with a zonal orientation. This region is often populated by a number of coherent eddies (Figure 3), but the zonal component of the mean flow is predominant over the meridional component ().Cited by: The wave amplitude is specified at some level beneath the mb African jet, whose instability is a plausible source of the wave.
The ascent is calculated using the quasigeostrophic potential vorticity and thermodynamic equations, and depends on the zonal wind separating the unstable jet. The streamfunction topography relationship given by eq. (54) shows that resonance between the zonal flow and topography will always occur provided h is composed of a range of topographic wavelengths.
The Gaussian ridge employed in the current study has this advantage over single-wavelength sinusoidal topography (e.g. Bell & Soward Cited by: Chapter 6 GENERAL WINDS The two most important weather, or weather related, elements affecting wildland fire behavior are wind and fuel moisture.
Of the two, wind is the most variable and the least predictable. Winds, particularly near the earth's surface, are strongly affected by the shape of the topography and by local heating and Size: 1MB.
gyres are divided by the ridge and have shorter zonal length than do those in the no-ridge case. These specific flow pat terns are observed in the Gulf Stream in the vicinity of the New England Seamount Chain and the Kuroshio over the Shatsky Rise.
Introduction The purpose of this paper is to study influences of a submarine ridge on a. Strong transport and mixing of deep water through the Southwest Indian Ridge. shear variance computed from velocity smoothed to m to represent the mean jet flow Nature Geoscience by: two criteria for source regions.
Because the atmosphere is heated chiefly from below and gains its moisture by evaporation from Earth's surface, the nature of the source region largely determines the initial characteristics of an air mass.
An ideal source region must meet two essential criteria. Landfalling cyclones and their attendant fronts significantly impact the structure of mesoscale wind and precipitation fields along the west coast of North America. This module focuses on the complex interaction of the wind field with topography and the resulting effects on nearshore winds and precipitation.
For example, prefrontal conditions may lead to flow blocking, development of a barrier. Rossby waves, also known as planetary waves, are a type of inertial wave naturally occurring in rotating fluids.
They were first identified by Carl-Gustaf Arvid are observed in the atmospheres and oceans of planets owing to the rotation of the planet.
Atmospheric Rossby waves on Earth are giant meanders in high-altitude winds that have a major influence on weather. Geostrophic zonal flow structure along 65°E computed from climatological temperature and salinity data relative to m. Contours every m/s. Light (dark) shaded correspond to the eastward SICC (westward SEC).
The SICC extends in the latitude band 20°–35°S, overlying the southward extension of the SEC at deep levels in the Cited by: River of high speed air in the upper atmosphere that flows along the polar front, middle latitudes rossby waves Undulations that develop in the polar front jet stream when significant temperature differences exist between tropical and polar air masses, isobars are in wave form.
Submesoscale Turbulence over a Topographic Slope. who demonstrated in numerical simulations of the California Current system and a baroclinically-unstable zonal flow respectively, The equilibrated structure of the jet depends on both winds and : Ayah Lazar, Qiong Zhang, Andrew F.
Thompson. The Atmospheric Circulation and Arctic Meteorology F. KENNETH HARE] In a sense this title contains a fallacy. Meteorology is the most global of all sciences in outlook, and it can be argued that there is no longer any such thing as arctic meteorology, at least in the.
If the ridge slopes equatorwards (sflow is subcritical, the solution over the ridge lies to the right of ΔLu along the Figure curve. As the subcritical jet climbs the topography its width increases and the flow becomes more subcritical.
If sNmax ridge crest is. An analytical model of long Rossby waves is developed for a continuously-stratified, planetary geostrophic ocean in the presence of arbitrary bottom topography under the assumption that the potential vorticity is a linear function of buoyancy.
The remaining dynamics are controlled by equations for material conservation of buoyancy along the sea surface and the sea by: 1. A zonal flow pattern indicates the winds are flowing primarily from west to east, nearly parallel to the lines of constant latitude (Figure a).
In this type of small amplitude flow pattern, cold air masses tend to stay towards the polar regions and the warm air remains to the south. SSH anomalies generating in the eastern North Pacific and strengthening during their westward propaga-tion. When the KE jet and recirculation gyre were in a weak mode during –, the regional eddy kinetic energy level was observed to be higher than when the jet and recirculation gyre were in.
the rate at which wind flow spreads apart along an axis oriented perpendicular to the flow in question Zonal flow west to east flow with littler or no transport of energy, move swiftly and little temp change.
Meridional diffusivity is assessed in this paper for a baroclinically unstable jet in a high-latitudeIdealized Circumpolar Current (ICC) using the Model for Prediction Across Scales-Ocean (MPAS-O) and the online Lagrangian In-situ Global High-performance particle Tracking (LIGHT) diagnostic via space-time dispersion of particle clusters over.
The trough / ridge pattern can be used to determine if the upper level winds are zonal (pretty much west to east flow, low pressures move quickly within a zonal flow) or meridional (atmospheric blocking and unusual cold and warm weather occur when the pattern is meridional).
Northern Hemisphere’s upper-air westerlies fowing through topographical ridges exhibit clockwise (an±cyclonic) curvature as seen From above. As shown in ²igure 1, the ridge axis line divides the ridge into two roughly symmetrical sectors.
Note that west oF the ridge axis, winds are From the southwest (a warm weather direc±on) and east oF the ridge axis, winds are From the northwest. current along the northern slope of Alaska (Spall et al. The boundary current is composed of low poten-tial vorticity water that is flowing eastward in a bottom-intensified jet over sloping topography (Fig.
This structure gives rise to a positive meridional gradient in potential vorticity at the core of the boundary current.
Jet Flow Field. The following is a typical jet velocity field distribution measured using the PIV. A total of instantaneous PIV velocity fields are ensemble-averaged in order to obtain this time-averaged flow field.
The time-averaged jet velocity at the exit of the nozzle is a uniform, top-hat profile. With mesoscale data from a high-resolution numerical model, this paper analyzes the impact of the complex mesoscale terrain at the eastern edge of the Tibetan Plateau on the formation and development of a local severe storm.
The result shows that the dynamic blocking effect of the Tibetan Plateau terrain affects the moisture transfer channel in this heavy rain scenario and brings about the Cited by:. As seen from a fine-resolution map of the sea floor topography near the pdf ridge (Fig. pdf, flow can be very complicated due to the rough topography associated with the newly formed seafloor on both sides of the mid-ocean ridge.
Fig. A zonal velocity section along °, from a high-resolution (1/4° x 1/6°) model with.The topography was found download pdf lead to the formation of bottom-trapped waves, as well as impacting the circulation at a level much higher than the top of the ridge.
This produced a unique flow structure when the drifting flow and the topography interacted in the form of an “interference” regime at low Taylor number, but forming an erratic. The ebook solution is close in ebook and spatial pattern to the forcing jet and is influenced very little by the topography, whereas the blocked solution is strongly affected by it.
In the blocked-flow solution, a high-amplitude ridge is located upstream of the “mountains,” similar to the situation during typical observed blocks Cited by: