Asymmetric Inner Core Convection Leading to Tropical Cyclone Intensification
ABSTRACT: One of the predictors used to forecast the rapid intensification of Tropical Cyclones (RI) is the symmetry of inner core convection which used infrared (IR) satellite imagery in the determination of this structure. This has led Forecasters and Researchers to conclude the symmetry of inner...
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| Format: | Article |
| Language: | English |
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KeAi Communications Co., Ltd.
2017-09-01
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| Series: | Tropical Cyclone Research and Review |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2225603218301553 |
| _version_ | 1818450297031229440 |
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| author | Jeff Callaghan |
| author_facet | Jeff Callaghan |
| author_sort | Jeff Callaghan |
| collection | DOAJ |
| description | ABSTRACT: One of the predictors used to forecast the rapid intensification of Tropical Cyclones (RI) is the symmetry of inner core convection which used infrared (IR) satellite imagery in the determination of this structure. This has led Forecasters and Researchers to conclude the symmetry of inner core convection was an important factor in RI. However we showed here using examples of RI that IR satellite imagery was not always a good guide to determine symmetry of inner core convection especially in the early stages of RI. However it has been previously shown that the heat released in these highly asymmetric convective bands may be transformed into the kinetic energy of the quasi-symmetric wind field and the available potential energy associated with the warm core. One of the most rapid RI cases had asymmetric inner core convection early in a six hour period where the Central Pressure dropped 29hPa and the sustained wind speed increased by 55knots(28.3ms−1). In other cases, where there was available inner core data, the inner core convection developed in a region where microwave imagery indicated asymmetric inner core convection. The convection was located where Dropsonde winds and Doppler radar winds from reconnaissance aircraft indicated a warm air advection pattern in that the winds turned anticyclonically with height in the lowest 5km of the atmosphere. Updrafts from this strong convection near the eye become upward extending centres of cyclonic vorticity and may also produce warming in the eye with adjacent broad subsiding currents. It was shown that models could not forecast the RI of severe tropical cyclone Marcia as recently as February 2015. In this case convection was formed more vigorously on the western flank under the influence of a warm air advection wind pattern and convection remained mostly on this western side as RI proceeded. This process needs to be understood on its influence on the models failing to forecast RI. Rare Doppler wind of Hurricane Hermine showed the wind structure as a band a convection on the storm’s eastern flank rapidly transformed into circular bands of convection as warm air advection winds increased around the inner core. Keywords: cyclone, intensification, asymmetry |
| first_indexed | 2024-12-14T20:49:03Z |
| format | Article |
| id | doaj.art-8fb1185a622c48809acf5fe4cb83fc5c |
| institution | Directory Open Access Journal |
| issn | 2225-6032 |
| language | English |
| last_indexed | 2024-12-14T20:49:03Z |
| publishDate | 2017-09-01 |
| publisher | KeAi Communications Co., Ltd. |
| record_format | Article |
| series | Tropical Cyclone Research and Review |
| spelling | doaj.art-8fb1185a622c48809acf5fe4cb83fc5c2022-12-21T22:47:53ZengKeAi Communications Co., Ltd.Tropical Cyclone Research and Review2225-60322017-09-01635566Asymmetric Inner Core Convection Leading to Tropical Cyclone IntensificationJeff Callaghan0Corresponding author address: Jeff Callaghan, Retired Bureau of Meteorology, Brisbane, Australia.; Retired Bureau of Meteorology, Brisbane, AustraliaABSTRACT: One of the predictors used to forecast the rapid intensification of Tropical Cyclones (RI) is the symmetry of inner core convection which used infrared (IR) satellite imagery in the determination of this structure. This has led Forecasters and Researchers to conclude the symmetry of inner core convection was an important factor in RI. However we showed here using examples of RI that IR satellite imagery was not always a good guide to determine symmetry of inner core convection especially in the early stages of RI. However it has been previously shown that the heat released in these highly asymmetric convective bands may be transformed into the kinetic energy of the quasi-symmetric wind field and the available potential energy associated with the warm core. One of the most rapid RI cases had asymmetric inner core convection early in a six hour period where the Central Pressure dropped 29hPa and the sustained wind speed increased by 55knots(28.3ms−1). In other cases, where there was available inner core data, the inner core convection developed in a region where microwave imagery indicated asymmetric inner core convection. The convection was located where Dropsonde winds and Doppler radar winds from reconnaissance aircraft indicated a warm air advection pattern in that the winds turned anticyclonically with height in the lowest 5km of the atmosphere. Updrafts from this strong convection near the eye become upward extending centres of cyclonic vorticity and may also produce warming in the eye with adjacent broad subsiding currents. It was shown that models could not forecast the RI of severe tropical cyclone Marcia as recently as February 2015. In this case convection was formed more vigorously on the western flank under the influence of a warm air advection wind pattern and convection remained mostly on this western side as RI proceeded. This process needs to be understood on its influence on the models failing to forecast RI. Rare Doppler wind of Hurricane Hermine showed the wind structure as a band a convection on the storm’s eastern flank rapidly transformed into circular bands of convection as warm air advection winds increased around the inner core. Keywords: cyclone, intensification, asymmetryhttp://www.sciencedirect.com/science/article/pii/S2225603218301553 |
| spellingShingle | Jeff Callaghan Asymmetric Inner Core Convection Leading to Tropical Cyclone Intensification Tropical Cyclone Research and Review |
| title | Asymmetric Inner Core Convection Leading to Tropical Cyclone Intensification |
| title_full | Asymmetric Inner Core Convection Leading to Tropical Cyclone Intensification |
| title_fullStr | Asymmetric Inner Core Convection Leading to Tropical Cyclone Intensification |
| title_full_unstemmed | Asymmetric Inner Core Convection Leading to Tropical Cyclone Intensification |
| title_short | Asymmetric Inner Core Convection Leading to Tropical Cyclone Intensification |
| title_sort | asymmetric inner core convection leading to tropical cyclone intensification |
| url | http://www.sciencedirect.com/science/article/pii/S2225603218301553 |
| work_keys_str_mv | AT jeffcallaghan asymmetricinnercoreconvectionleadingtotropicalcycloneintensification |