Developing a new sinuosity index for cyclone tracks in the tropical South Pacific

Terry, James P.; Gienko, Gennady

doi:10.1007/s11069-011-9827-3

Cited by 18 publications

(36 citation statements)

References 24 publications

(23 reference statements)

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“…While noting the imbalance in the number of El Niñ o and La Niñ a years, the tracks show a noticeable displacement toward the southwest during La Niñ a events compared to El Niñ o events, in agreement with previous studies (Evans and Allan 1992;Basher and Zheng 1995;Terry 2007;Kuleshov et al 2008). The influence of ENSO on TC activity is examined in more detail in this section, including the spatial characteristics of TC transport, system density, intensity, and temporal changes in intensity and genesis regions.…”

Section: Resultssupporting

confidence: 92%

“…In the SPO the area of highest TC density is located in the latitudinal belt between about 108 and 208S, and falls away sharply toward 308S and over Australia. The decline as one moves south relates to both a tendency for systems to weaken as they move toward the less favorable subtropics, and also the generally fast rate of movement, while noting that track sinuosity generally decreases in a poleward direction (Terry and Gienko 2011). The extratropical transition of TCs (e.g., Sinclair 2002) is not a focus of this study, and characteristics of this change toward baroclinic forcing are not examined here.…”

Section: B Tc Densitymentioning

confidence: 98%

“…They also concluded that the primary influence on TC incidence west of 1708E was the local oceanic conditions, while to the east of 1708E it was the eastward extent of favorable atmospheric conditions, as indicated by the SOI or Tahiti mean sea level pressure. Terry (2007) presented a TC climatology in the SPO and found that January and February, when the South Pacific convergence zone (SPCZ) moves to its most southerly average position, was the most likely period for TC occurrences. That study also showed that the interannual variability in TC numbers is mostly related to ENSO events, confirming earlier results.…”

Section: Introductionmentioning

confidence: 99%

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Tropical Cyclone Climatology of the South Pacific Ocean and Its Relationship to El Niño–Southern Oscillation

Dowdy

Jones

et al. 2012

Journal of Climate

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Climatological features of tropical cyclones in the South Pacific Ocean have been analyzed based on a new archive for the Southern Hemisphere. A vortex tracking and statistics package is used to examine features such as climatological maps of system intensity and the change in intensity with time, average tropical cyclone system movement, and system density. An examination is presented of the spatial variability of these features, as well as changes in relation to phase changes of the El Niñ o-Southern Oscillation phenomenon. A critical line is defined in this study based on maps of cyclone intensity to describe the statistical geographic boundary for cyclone intensification. During El Niñ o events, the critical line shifts equatorward, while during La Niñ a events the critical line is generally displaced poleward. Regional variability in tropical cyclone activity associated with El Niñ o-Southern Oscillation phases is examined in relation to the variability of large-scale atmospheric or oceanic variables associated with tropical cyclone activity. Maps of the difference fields between different phases of El Niñ o-Southern Oscillation are examined for sea surface temperature, vertical wind shear, lower-tropospheric vorticity, and midtropospheric relative humidity. Results are also examined in relation to the South Pacific convergence zone. The common region where each of the large-scale variables showed favorable conditions for cyclogenesis coincided with the location of maximum observed cyclogenesis for El Niñ o events as well as for La Niñ a years.

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Section: Resultssupporting

confidence: 92%

Section: B Tc Densitymentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Tropical Cyclone Climatology of the South Pacific Ocean and Its Relationship to El Niño–Southern Oscillation

Dowdy

Jones

et al. 2012

Journal of Climate

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“…In contrast, polynomial curve‐fitting or calculating mass moments, which are other favoured methods (Camargo et al , , , ; Nakamura et al , ; Kossin et al , ) are more challenging tasks when dealing with complex line shapes. Finally, difference testing demonstrates that the current sinuosity dataset for tropical storms in the NA basin bears a close statistical resemblance to sinuosity datasets extracted in a similar manner for typhoons and cyclones in the Pacific and South Indian Ocean (see Terry and Feng, ; Terry and Gienko, ; Terry et al , 2013). Crucially, this finding establishes the transferability of our sinuosity‐based system for track morphometry between ocean basins where tropical storms originate, and is therefore not restricted by geographical boundaries.…”

Section: Track Morphometry: Results and Discussionmentioning

confidence: 81%

“…After normalization, data analysis using parametric statistics is better justified, for example if testing whether or not there are relationships between sinuosity and other fundamental parameters of tropical storms such as maximum intensity and storm longevity is desired. Here, normalization was achieved using a data transformation procedure based on a combination of cube‐root and data shift, as implemented in earlier work on track sinuosity datasets for tropical cyclones in both the South Pacific and South West Indian Ocean basins (Terry and Gienko, ; Terry et al , 2013). Original source measurements for track sinuosity are normalized by applying the formula below:

SI =^{3} \sqrt (S - 1) \times 10

…”

Section: Track Morphometry: Results and Discussionmentioning

confidence: 99%

Morphometric analysis of tropical storm and hurricane tracks in the North Atlantic basin using a sinuosity‐based approach

Terry

Kim

2014

Intl Journal of Climatology

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Quantitative analysis is carried on the shape of over 420 tropical storm and hurricane tracks in the North Atlantic basin for the period 1965–2011. A sinuosity metric is used as the basis for track morphometry, applied to best‐track data accessed from the IBTrACs archive maintained by NOAA. GIS tools, track mapping according to sinuosity category, and various statistical analyses permit temporal and spatial patterns in track shape to be identified and investigated. Temporal analysis reveals no underlying long‐term trend in track sinuosity over the past 4.5 decades, implying an absence of climatic‐change forcing on storm migration behaviour at the basin scale. Instead, large inter‐annual variability dominates, although it is possible to observe episodes of notable cyclic swings in average sinuosity towards straighter or more sinuous tracks. Seasonality in track behaviour is pronounced, as similarly reported for other ocean basins. Predictable straight and quasi‐straight track types are more common (64–100%) during the early months (May to July) of the hurricane season, with this reversing at the peak and later phase of the season (September, November) to a predominance for quasi‐sinuous and sinuous tracks (58–70%). In spatial terms, track morphometric analysis according to 10° longitudinal zone of cyclogenesis is valuable, revealing that storm origin is reasonably indicative of likely track shape over the subsequent lifespan. Thus, while 62–68% of storms spawned west of 80°W in the Caribbean Sea – Gulf of Mexico region show a tendency to follow straighter tracks, 67–72% of storms formed east of 40°W in the central‐eastern North Atlantic subsequently describe more sinuous tracks. Overall, these patterns are seen to influence the geographic potential of storm landfall. This is important for societal vulnerability on coastlines at risk, since storms exhibiting higher track sinuosity generally prove to survive longer, migrate farther and therefore display greater potential for inflicting damage over wider areas.

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Variability of southwest Pacific tropical cyclone track geometry over the last 70 years

Sharma

Magee

Verdon‐Kidd

2020

Intl Journal of Climatology

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Variability in tropical cyclone (TC) track morphology, as it evolves post genesis, presents continued challenges in accurately forecasting TC movement. Therefore, an improved understanding of TC track climatology is essential, given that TCs are one of the most critical natural hazards in the southwest Pacific (SWP) region. We examine the historical variability of TC tracks within the SWP over the last 70 years (1948-2017) using 6-hourly track data obtained from the South Pacific Enhanced Archive of Tropical Cyclones (SPEArTC) database. A probabilistic clustering technique is applied to separate TC tracks into distinct groups in order to assess the primary cyclone trajectories for the region and its relationship with the El Niño-Southern Oscillation (ENSO). TC tracks are also classified into four sinuosity categories: straight, recurving, sinuous and highly sinuous; and their spatial and temporal characteristics subsequently analysed. The results of the cluster analysis identified five optimal groups of TC tracks, four of which exhibited southeast propagation, except for the southwest moving tracks in Cluster 5. Temporally, significant trends were observed over the last seven decades, with Clusters 1, 3 and 4 becoming less frequent with a substantial increase in the occurrence of Cluster 2 tracks (representing TCs east of dateline), a geometry favoured by El Niño conditions. Further, the sinuosity analysis revealed continued dominance of straight TCs within the eastern SWP with a tendency of encountering TCs of other morphology types. Conversely, the western SWP region is typically exposed to highly sinuous tracks. We also observed a significant decrease (increase) in TCs with straight and quasi-straight (highly sinuous) tracks, particularly during the last decade. These findings suggest that combined cluster analysis and TC track sinuosity analysis is an important tool in generalising the TC track regimes, refining predicted trajectories and understanding impacts on SWP island nations.

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Developing a new sinuosity index for cyclone tracks in the tropical South Pacific

Cited by 18 publications

References 24 publications

Tropical Cyclone Climatology of the South Pacific Ocean and Its Relationship to El Niño–Southern Oscillation

Tropical Cyclone Climatology of the South Pacific Ocean and Its Relationship to El Niño–Southern Oscillation

Morphometric analysis of tropical storm and hurricane tracks in the North Atlantic basin using a sinuosity‐based approach

Variability of southwest Pacific tropical cyclone track geometry over the last 70 years

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