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Cyclone Formation (cyclone + formation)

Distribution by Scientific Domains
Earth and Environmental Science100%

Kinds of Cyclone Formation

  • tropical cyclone formation
    		•

    Selected Abstracts

    Environmental links to reduced tropical cyclogenesis over the south-east Caribbean

    INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 8 2007
    Alexandros P. Georgiadis
    Abstract Tropical cyclone formation over the Caribbean is not evenly distributed across the basin. Previous work identified the south-western sector as the area that dominates the hurricane activity of the whole basin. The south-eastern sector, in contrast, exhibits a distinct suppression in cyclogenesis. This study seeks to identify the restricting factors that differentiate the cyclogenesis climatology in the south-east Caribbean. It is based on statistical analysis of eight environmental variables using principal component analysis. The first three components are examined in detail. The first component, accounting for 31.7% of the variance within the data, differentiates the Caribbean from the rest of the subtropical Atlantic, primarily in terms of an increased thermodynamic potential for cyclogenesis and enhanced atmospheric humidity in the boundary layer. The second component, accounting for 31% of the variance, marks the south-west Caribbean as the only sub-region within the area of analysis where the easterlies curve southwards and the relative vorticity is cyclonic. The third component, accounting for 20.3% of the variance, differentiates the South Caribbean from the rest of the Atlantic, indicating it to be a region of increased spatial variation in the intensity of the easterlies and in absolute vorticity. The variance of cyclogenesis within the Caribbean is greatest along the second and third components. Thus, the genesis pattern in the basin is likely associated with the low-level wind-field and absolute vorticity. The divergence of the flow, when combined with the vorticity of the wind-field over the Caribbean, renders the background conditions of the eastern sector less prone to developing disturbances than is the case in the western Caribbean. Copyright © 2006 Royal Meteorological Society [source]

    Distribution and temporal variability of 500 hPa cyclone characteristics in the Southern Hemisphere

    INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 2 2002
    Murray Keable
    Abstract A 40 year period (1958,97) of US National Centers for Environmental Prediction reanalysis data has been used to diagnose the behaviour and variability of 500 hPa extratropical cyclones for the Southern Hemisphere using a Lagrangian perspective. The ,finding' and ,tracking' of these systems were performed using a fully automated scheme. Seasonal distributions of system density, cyclone formation (cyclogenesis), decay (cyclolysis), cyclone centre velocity and intensity/strength are presented. System density is shown to exhibit a maximum in the surface circumpolar trough region and over the Antarctic continent. A broad band of enhanced cyclone system density was evident across the South Pacific from southeast Australia to South America in all seasons, most markedly in winter. As this feature appears also at the surface level, strong vertical consistency of these cyclones in the low and middle troposphere is indicated. Velocities of cyclone centres were found to peak in the latitudes 50,55 °S, and 500 hPa systems appeared to move on average in a much more zonal (easterly) direction than their sea-level counterparts. The mean number of midlatitude cyclones per analysis has exhibited a significant downward trend over the record, with particularly low values observed in the early 1980s. Offsetting this trend have been increases in three measures of mean cyclone vigour. Three orographic features, in particular, are seen to influence the behaviour of 500 hPa cyclones: the mountains of New Zealand, the Antarctic Peninsula and the southern Andes. Over most of Antarctica the rate of cyclogenesis exceeds that of cyclolysis, indicating that many of the cyclones being formed in the vortex are actually exported out (i.e. to the north) of the continent. In the subtropics, considerable numbers of systems are formed in the Mozambique Sea region, but these tend to be quasi-stationary features. Copyright © 2002 Royal Meteorological Society. [source]

    Simulations of observed interannual variability of tropical cyclone formation east of Australia

    ATMOSPHERIC SCIENCE LETTERS, Issue 1-4 2003
    Kevin J.E. Walsh
    Abstract A modelling system comprising a regional climate model nested within a GCM is used to simulate the observed interannual variability of tropical cyclone formation off the east coast of Australia. The model's interannual variability of cyclone formation is weaker than that observed, with shortcomings in the model's simulation of vertical wind shear the likely cause. Copyright © 2003 Royal Meteorological Society. Published by Elsevier Ltd. All rights reserved. [source]

    A cloud-resolving regional simulation of tropical cyclone formation

    ATMOSPHERIC SCIENCE LETTERS, Issue 1 2002
    Jordan G. Powers
    Abstract The development of Tropical Cyclone Diana (1984) is simulated with a mesoscale model using 1.2 km grid spacing over a regional-scale (>1000 km) domain in the first known experiment of this kind. With only a synoptic-scale disturbance in the initial conditions, the model first develops a mesoscale convective system along a remnant frontal zone, which yields a mesoscale vortex. After a period of quiescence, banded convection organizes about the vortex from isolated, grid-resolved cells, with the system becoming warm-core and intensifying into Tropical Storm Diana. Copyright © 2002 Royal Meteorological Society. [source]