Climatological Analysis of Tropical Cyclone Intensity Changes under Moderate Vertical Wind Shear

Although infrequent, tropical cyclones (TCs) can intensify under moderate vertical wind shear (VWS). A potential hypothesis is that other factors—associated with both the TC and its environment—can help offset the effects of VWS and aid intensification. This hypothesis was tested with a large datase...

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Bibliographic Details
Published in:Monthly weather review Vol. 145; no. 5; pp. 1717 - 1738
Main Authors: Rios-Berrios, Rosimar, Torn, Ryan D.
Format: Journal Article
Language:English
Published: Washington American Meteorological Society 01.05.2017
Subjects:
Climatic analysis
Climatology
Cyclones
Data points
Datasets
Dry air
Environmental science
Equator
Equatorial regions
Heat flux
Heat transfer
Hurricanes
Hypotheses
Kinematics
Latent heat
Rain
Rainfall
Sea surface
Sea surface temperature
Shear
Storms
Studies
Surface temperature
Temperature (air-sea)
Temporal variability
Temporal variations
Tropical climate
Tropical cyclones
Variability
Vertical wind shear
Vortices
Water vapor
Water vapour
Wind
Wind profiles
Wind shear
ISSN:0027-0644, 1520-0493
Online Access:Get full text
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Summary:Although infrequent, tropical cyclones (TCs) can intensify under moderate vertical wind shear (VWS). A potential hypothesis is that other factors—associated with both the TC and its environment—can help offset the effects of VWS and aid intensification. This hypothesis was tested with a large dataset of 6-hourly best tracks and environmental diagnostics for global TCs between 1982 and 2014. Moderate VWS was objectively defined as 4.5–11.0 m s−1, which represents the 25th–75th percentiles of the global distribution of 200–850-hPa VWS magnitude around TCs. Intensifying events (i.e., unique 6-hourly data points) were compared against steady-state events to determine which TC and environmental characteristics favored intensification under moderate VWS. This comparison showed that intensifying events were significantly stronger, closer to the equator, larger, and moving with a more westward motion than steady-state events. Furthermore, intensifying events moved within environments characterized by warmer sea surface temperatures, greater midtropospheric water vapor, and more easterly VWS than steady-state events. Storm-relative, shear-relative composites suggested that the coupling between water vapor, surface latent heat fluxes, and storm-relative flow asymmetries was conducive for less dry air intrusions and more symmetric rainfall in intensifying events. Last, the comparison showed no systematic differences between environmental wind profiles possibly due to the large temporal variability of VWS.
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ISSN:0027-0644
1520-0493
DOI:10.1175/MWR-D-16-0350.1