Recent Progress in the Fundamental Understanding of Tropical Cyclone Motion

Ito, Kosuke; Wu, Chueh‐Yu; Chan, Kelvin T. F.; Toumi, Ralf; Davis, C. A.

doi:10.2151/jmsj.2020-001

Cited by 18 publications

(9 citation statements)

References 42 publications

(39 reference statements)

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“…The complex structures, interactions with the surrounding environment, and associated uncertainty in TC movements cause difficulties in predicting which will cause the greatest damage to human life and property, especially in coastal areas. Ongoing vast advancements in understanding the physical processes that govern the motion of TCs (Elsberry, 1995; Chan, 2005; 2010; Ito et al ., 2020) could limit such forecasting errors and effectively inform mitigation strategies accordingly.…”

Section: Introductionmentioning

confidence: 99%

Recurvature and movement processes of tropical cyclones over the Bay of Bengal

Akter

Tsuboki

2021

Quart J Royal Meteoro Soc

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Active bimodal tropical cyclones (TCs) are embedded in nonuniform flows over the Bay of Bengal (BoB). More than half of the TCs that occurred from 1990 to 2019 recurved from their original path due to the influence of 500–300 hPa steering flows. Premonsoon TCs have a tendency to turn right and make landfall on the right‐side coastal areas of the BoB. On the other hand, most of the TCs that occurred in the postmonsoon season crossed the left coast or east coast of India, despite being left or right from their path. The simulation shows that Cyclone Roanu (2016) was driven by a warm, moist, unstable southwesterly that was blocked and diverted by the hot, dry stable air masses of northerlies and northwesterlies. As a result, the TC moved along the dry–moist boundary, keeping a constant distance of ∼400 km between the eye and dryline. Conversely, the combined steering of moist southeasterly and southward‐moving upper‐level westerly jets controlled the track of postmonsoon Cyclone Madi (2013), encompassing a left turn of ∼150°. In addition to the primary steering mechanism, TC vortex propagation can be explained by the strong vertical shear (>30 m·s−1) offered by the dryline during the premonsoon period and near the monsoon trough in the postmonsoon period. This vertical shear causes the upper‐level anticyclone to tilt downshear, resulting in the forward motion of the TC vortex. The deep convection and associated mesovortices, especially those that are more prominent along the dryline, additionally influence asymmetric diabatic heating, contributing to the advection of TC potential vorticity.

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Section: Introductionmentioning

confidence: 99%

Recurvature and movement processes of tropical cyclones over the Bay of Bengal

Akter

Tsuboki

2021

Quart J Royal Meteoro Soc

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“…The accuracy of operational tropical cyclone (TC) track forecasts has significantly improved over the last few decades (e.g., Heming et al 2019) due to better understanding of its dynamics (e.g., Ito et al 2019) and improvement in numerical weather predictions (e.g., Yamaguchi et al 2017, Magnusson et al 2019. However, progress seems to be slow in the treatment of forecast uncertainty associated with TC tracks although previous studies show the value of dynamical ensemble forecasts to estimate the uncertainties associated with TC track forecasts (e.g., Yamaguchi et al 2009, Dupont et al 2011, Zhang and Yu 2017.…”

Section: Introductionmentioning

confidence: 99%

Determining 70 Percent Probability-Circle Radii of Tropical Cyclone Track Forecasts with Multiple Ensembles

Fukuda

Yamaguchi

2019

SOLA

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The effectiveness of multiple ensembles to determine 70% probability-circle radii of operational tropical cyclone (TC) track forecasts in the Japan Meteorological Agency (JMA) is investigated. The ensembles used in this study are global ensembles from JMA, the European Centre for Medium-Range Weather Forecasts (ECMWF), the National Centers for Environmental Prediction (NCEP) and the Met Office in the United Kingdom (UKMO). The verification for all TCs from 2016 to 2018 reveals that the multiple ensemble-based method has stronger correlation with operational TC track forecast errors and the clearer degree of separation among confidence levels derived from the ensemble spreads than the conventional statistical and single ensemble-based methods. It indicates that the multiple ensemble method provides situation-dependent forecast uncertainty most appropriately. As the effectiveness of the multiple ensemble method has been confirmed, JMA started to operate the multiple ensemble-based 70% probability-circle radii for its operational TC track forecasts for all forecast times up to 120 hours in June 2019. The radii are based solely on confidence levels derived from cumulative ensemble spreads of the multiple ensemble from the 4 centers. This is a good example of successful research to operation transfer of The International Grand Global Ensemble (TIGGE) project.

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“…Particularly, the steering flow and TC translation speed are significantly correlated ( r = 0.46, p < 0.01) during 1979–2019. The relatively low correlation coefficient may root in the influence of topography (Ito et al., 2020) and the small sample size of landfalling TCs. However, the decadal slowdown of TC translation speed can be reasonably captured by the changes in large‐scale steering flow with a change point in 1997 based on the Lepage test (Figure 2a).…”

Section: Role Of Steering Flow and The Driving Mechanismmentioning

confidence: 99%

Slowdown in Landfalling Tropical Cyclone Motion in South China

Wang

et al. 2022

Geophysical Research Letters

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Understanding changes in tropical cyclone (TC) translation speed is of great social and scientific concerns due to the enormous TC-induced disasters (Zhang et al., 2009). From a view of a specific site, slower TC motion indicates a longer linger time and thus greater TC-induced disasters. Kossin (2018) found that TC translation speed experiences a notable slowdown by 10% globally over the past seven decades, which is arguably attributed to the deceleration of TC embedded steering flow that is linked to the anthropogenic warming-induced weakening in tropical circulation Vecchi et al., 2006). However, the result was challenged by Moon et al. (2019) and Lanzante (2019) in term of the relatively low data reliability for the pre-satellite era. The slowdown in TC motion disappears when only the data for the post-satellite era are used (K.

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Recent Progress in the Fundamental Understanding of Tropical Cyclone Motion

Cited by 18 publications

References 42 publications

Recurvature and movement processes of tropical cyclones over the Bay of Bengal

Recurvature and movement processes of tropical cyclones over the Bay of Bengal

Determining 70 Percent Probability-Circle Radii of Tropical Cyclone Track Forecasts with Multiple Ensembles

Slowdown in Landfalling Tropical Cyclone Motion in South China

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