scholarly journals A Modeling Study on Tropical Cyclone Structural Changes in Response to Ambient Moisture Variations

2012 ◽  
Vol 90 (5) ◽  
pp. 755-770 ◽  
Author(s):  
Yue YING ◽  
Qinghong ZHANG
Keyword(s):  
Tropical Cyclone ◽  
Structural Changes ◽  
Modeling Study

scholarly journals Measuring Radial and Tangential Changes in Tropical Cyclone Rain Fields Using Metrics of Dispersion and Closure

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Corene Matyas ◽  
Jingyin Tang
Keyword(s):  
Tropical Cyclone ◽  
Structural Changes ◽  
Spatial Information ◽  
Vertical Wind Shear ◽  
Tangential Component ◽  
Rapid Intensification ◽  
Storm Intensity ◽  
Surrounding Environment ◽  
Spatial Configurations ◽  
Future Work

Although tropical cyclone (TC) rain fields assume varying spatial configurations, many studies only use areal coverage to compare TCs. To provide additional spatial information, this study calculates metrics of closure, or the tangential completeness of reflectivity regions surrounding the circulation center, and dispersion, or the spread of reflectivity outwards from the storm center. Two hurricanes that encountered different conditions after landfall are compared. Humberto (2007) experienced rapid intensification (RI), stronger vertical wind shear, and more moisture than Jeanne (2004), which was more intense, weakened gradually, and became extratropical. A GIS framework was used to convert radar reflectivity regions into polygons and measure their area, closure, and dispersion. Closure corresponded most closely to storm intensity, as the eye became exposed when both TCs weakened to tropical storm intensity. Dispersion increased by 10 km·hr−1 as both TCs developed precipitation along frontal boundaries. As closure tended to change earlier than dispersion and area, closure may be most sensitive to subtle changes in environmental conditions, particularly as the storm’s core experiences the entrainment of dry air and erodes. Displacement provided a combined radial and tangential component to the location of the rainfall regions to confirm placement along the frontal boundaries. Examining area alone cannot reveal these patterns. The spatial metrics reveal changes in TC structure, such as the lag between onset of RI and maximum closure, which should be generalizable to TCs experiencing similar conditions. Future work will calculate these metrics for additional TCs to quantify structural changes in response to their surrounding environment.

On the dynamics of tropical cyclone structural changes

1984 ◽  
Vol 110 (465) ◽  
pp. 723-745 ◽  
Author(s):  
Greg. J. Holland ◽  
Robert T. Merrill
Keyword(s):  
Tropical Cyclone ◽  
Structural Changes

scholarly journals Analysis of the Wind Field Evolution Associated with the Extratropical Transition of Bonnie (1998)

2008 ◽  
Vol 136 (6) ◽  
pp. 2047-2065 ◽  
Author(s):  
Clark Evans ◽  
Robert E. Hart
Keyword(s):  
Tropical Cyclone ◽  
Wind Field ◽  
Structural Changes ◽  
Outer Core ◽  
Balance Model ◽  
Extratropical Transition ◽  
Wind Maximum ◽  
Outer Periphery ◽  
Conveyor Belts ◽  
Work Done

Abstract Extratropical transition brings about a number of environmentally induced structural changes within a transitioning tropical cyclone. Of particular interest among these changes is the acceleration of the wind field away from the cyclone’s center of circulation along with the outward movement of the radial wind maximum, together termed wind field expansion. Previous informal hypotheses aimed at understanding this evolution do not entirely capture the observed expansion, while a review of the literature shows no formal work done upon the topic beyond analyzing its occurrence. This study seeks to analyze the physical and dynamical mechanisms behind the wind field expansion using model simulations of a representative transition case, North Atlantic Tropical Cyclone Bonnie of 1998. The acceleration of the wind field along the outer periphery of the cyclone is found to be a function of the net import of absolute angular momentum within the cyclone’s environment along inflowing trajectories. This evolution is shown to be a natural outgrowth of the development of isentropic conveyor belts and asymmetries associated with extratropical cyclones. Asymmetries in the outer-core wind field manifest themselves via the tightening and development of height and temperature gradients within the cyclone’s environment. Outward movement of the radial wind maximum occurs coincident with integrated net cooling found inside the radius of maximum winds. Tests using a secondary circulation balance model show the radial wind maximum evolution to be similar yet opposite to the response noted for intensifying tropical cyclones with contracting eyewalls.

The Tropical Cyclone Diurnal Cycle of Mature Hurricanes

2014 ◽  
Vol 142 (10) ◽  
pp. 3900-3919 ◽  
Author(s):  
Jason P. Dunion ◽  
Christopher D. Thorncroft ◽  
Christopher S. Velden
Keyword(s):  
Tropical Cyclone ◽  
Diurnal Cycle ◽  
Structural Changes ◽  
Inner Core ◽  
Satellite Image ◽  
Intensity Change ◽  
Ongoing Research ◽  
Image Differencing ◽  
A New Technique ◽  
Cloud Tops

Abstract The diurnal cycle of tropical convection and the tropical cyclone (TC) cirrus canopy has been described extensively in previous studies. However, a complete understanding of the TC diurnal cycle remains elusive and is an area of ongoing research. This work describes a new technique that uses infrared satellite image differencing to examine the evolution of the TC diurnal cycle for all North Atlantic major hurricanes from 2001 to 2010. The imagery reveals cyclical pulses in the infrared cloud field that regularly propagate radially outward from the storm. These diurnal pulses begin forming in the storm’s inner core near the time of sunset each day and continue to move away from the storm overnight, reaching areas several hundreds of kilometers from the circulation center by the following afternoon. A marked warming of the cloud tops occurs behind this propagating feature and there can be pronounced structural changes to a storm as it moves away from the inner core. This suggests that the TC diurnal cycle may be an important element of TC dynamics and may have relevance to TC structure and intensity change. Evidence is also presented showing the existence of statistically significant diurnal signals in TC wind radii and objective Dvorak satellite-based intensity estimates for the 10-yr hurricane dataset that was examined. Findings indicate that TC diurnal pulses are a distinguishing characteristic of the TC diurnal cycle and the repeatability of TC diurnal pulsing in time and space suggests that it may be an unrealized, yet fundamental TC process.

scholarly journals Tropical Cyclone Climatology in a 10-km Global Atmospheric GCM: Toward Weather-Resolving Climate Modeling

2012 ◽  
Vol 25 (11) ◽  
pp. 3867-3893 ◽  
Author(s):  
Julia V. Manganello ◽  
Kevin I. Hodges ◽  
James L. Kinter ◽  
Benjamin A. Cash ◽  
Lawrence Marx ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
North Atlantic ◽  
Large Scale ◽  
Structural Changes ◽  
Global Climate ◽  
Surface Wind ◽  
Cumulus Parameterization ◽  
Future Climate Change ◽  
Model Errors ◽  
The North

Northern Hemisphere tropical cyclone (TC) activity is investigated in multiyear global climate simulations with the ECMWF Integrated Forecast System (IFS) at 10-km resolution forced by the observed records of sea surface temperature and sea ice. The results are compared to analogous simulations with the 16-, 39-, and 125-km versions of the model as well as observations. In the North Atlantic, mean TC frequency in the 10-km model is comparable to the observed frequency, whereas it is too low in the other versions. While spatial distributions of the genesis and track densities improve systematically with increasing resolution, the 10-km model displays qualitatively more realistic simulation of the track density in the western subtropical North Atlantic. In the North Pacific, the TC count tends to be too high in the west and too low in the east for all resolutions. These model errors appear to be associated with the errors in the large-scale environmental conditions that are fairly similar in this region for all model versions. The largest benefits of the 10-km simulation are the dramatically more accurate representation of the TC intensity distribution and the structure of the most intense storms. The model can generate a supertyphoon with a maximum surface wind speed of 68.4 m s−1. The life cycle of an intense TC comprises intensity fluctuations that occur in apparent connection with the variations of the eyewall/rainband structure. These findings suggest that a hydrostatic model with cumulus parameterization and of high enough resolution could be efficiently used to simulate the TC intensity response (and the associated structural changes) to future climate change.

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