Rapid Intensification of Typhoon Rammasun (2014) with Strong Vertical Wind Shear
From a traditional point of view, the growth of a tropical cyclone (TC) requires that the vertical wind shear (VWS) should be weak. However, Typhoon Rammasun (2014) underwent a rapid intensification (RI) even in the presence of a strong VWS background. This study investigates the counterintuive phen...
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MDPI AG
2025-03-01
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| author | Weiyu Lu X. San Liang |
| author_facet | Weiyu Lu X. San Liang |
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| description | From a traditional point of view, the growth of a tropical cyclone (TC) requires that the vertical wind shear (VWS) should be weak. However, Typhoon Rammasun (2014) underwent a rapid intensification (RI) even in the presence of a strong VWS background. This study investigates the counterintuive phenomenon, using the multiscale window transform (MWT) and the theory of canonical transfer. For the first time, the diagnostic results show that the strong VWS provided additional available potential energy (APE) to the mid-to-upper troposphere through baroclinic instability. This APE was converted into kinetic energy (KE) via buoyancy conversion and transported to the lower troposphere by pressure gradient, increasing the lower-troposphere wind speed. The strong VWS facilitated the RI in two main ways. First, it was via baroclinic instability. Strong VWS facilitated the transfer of APE from the background flow window to the typhoon scale window, supplying additional APE to the mid-to-upper troposphere, hence enhancing the warm-core structure. Second, the VWS direction shifted from an east-west orientation to a north-south orientation. This directional change put the typhoon’s vertical alignment from a westward tilt back to a straighter one. This effectively suppressed the destructive effects of the asymmetric circulation, and promoted the conversion of APE into KE via buoyancy conversion, hence contributed to the RI. |
| format | Article |
| id | doaj-art-a0ddbe60cf1d4e0b84424181cea813ce |
| institution | DOAJ |
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| language | English |
| publishDate | 2025-03-01 |
| publisher | MDPI AG |
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| spelling | doaj-art-a0ddbe60cf1d4e0b84424181cea813ce2025-08-20T02:42:38ZengMDPI AGAtmosphere2073-44332025-03-0116329710.3390/atmos16030297Rapid Intensification of Typhoon Rammasun (2014) with Strong Vertical Wind ShearWeiyu Lu0X. San Liang1CMA-FDU Joint Laboratory of Marine Meteorology, Department of Atmospheric and Oceanic Sciences, Fudan University, Shanghai 200438, ChinaCMA-FDU Joint Laboratory of Marine Meteorology, Department of Atmospheric and Oceanic Sciences, Fudan University, Shanghai 200438, ChinaFrom a traditional point of view, the growth of a tropical cyclone (TC) requires that the vertical wind shear (VWS) should be weak. However, Typhoon Rammasun (2014) underwent a rapid intensification (RI) even in the presence of a strong VWS background. This study investigates the counterintuive phenomenon, using the multiscale window transform (MWT) and the theory of canonical transfer. For the first time, the diagnostic results show that the strong VWS provided additional available potential energy (APE) to the mid-to-upper troposphere through baroclinic instability. This APE was converted into kinetic energy (KE) via buoyancy conversion and transported to the lower troposphere by pressure gradient, increasing the lower-troposphere wind speed. The strong VWS facilitated the RI in two main ways. First, it was via baroclinic instability. Strong VWS facilitated the transfer of APE from the background flow window to the typhoon scale window, supplying additional APE to the mid-to-upper troposphere, hence enhancing the warm-core structure. Second, the VWS direction shifted from an east-west orientation to a north-south orientation. This directional change put the typhoon’s vertical alignment from a westward tilt back to a straighter one. This effectively suppressed the destructive effects of the asymmetric circulation, and promoted the conversion of APE into KE via buoyancy conversion, hence contributed to the RI.https://www.mdpi.com/2073-4433/16/3/297rapid intensification (RI)strong vertical wind shear (VWS)baroclinic canonical transfermultiscale window transform |
| spellingShingle | Weiyu Lu X. San Liang Rapid Intensification of Typhoon Rammasun (2014) with Strong Vertical Wind Shear Atmosphere rapid intensification (RI) strong vertical wind shear (VWS) baroclinic canonical transfer multiscale window transform |
| title | Rapid Intensification of Typhoon Rammasun (2014) with Strong Vertical Wind Shear |
| title_full | Rapid Intensification of Typhoon Rammasun (2014) with Strong Vertical Wind Shear |
| title_fullStr | Rapid Intensification of Typhoon Rammasun (2014) with Strong Vertical Wind Shear |
| title_full_unstemmed | Rapid Intensification of Typhoon Rammasun (2014) with Strong Vertical Wind Shear |
| title_short | Rapid Intensification of Typhoon Rammasun (2014) with Strong Vertical Wind Shear |
| title_sort | rapid intensification of typhoon rammasun 2014 with strong vertical wind shear |
| topic | rapid intensification (RI) strong vertical wind shear (VWS) baroclinic canonical transfer multiscale window transform |
| url | https://www.mdpi.com/2073-4433/16/3/297 |
| work_keys_str_mv | AT weiyulu rapidintensificationoftyphoonrammasun2014withstrongverticalwindshear AT xsanliang rapidintensificationoftyphoonrammasun2014withstrongverticalwindshear |