How Well Are Tropical Cyclones Represented in Reanalysis Datasets?

Hodges, Kevin I.; Cobb, Alison; Vidale, Pier Luigi

doi:10.1175/jcli-d-16-0557.1

Cited by 232 publications

(329 citation statements)

References 72 publications

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“…Therefore, the increased number of detections using the OWZP detection scheme may be due to the more favorable large‐scale climate of the ACCESS model. The reduced number of detections in the reanalysis using the CSIRO scheme is due to a resolution‐dependent 10 m wind speed threshold, which causes an underestimation of TC numbers in the low‐resolution reanalysis data sets (Hodges et al, ; Murakami, ). The resolution‐dependent (CSIRO) TC tracking scheme has better performance in the high‐resolution ACCESS model compared to the lower resolution reanalysis; we speculate that the model has improved the simulation of TC intensity compared with the reanalysis.…”

Section: Resultsmentioning

confidence: 99%

“…Nevertheless, compared to the earlier reanalysis versions, the ERA-Interim has improved model physics and includes the use of four-dimensional variational data assimilation (Compo et al, 2011;Dee et al, 2011). Recent studies showed that TC intensity is underestimated in the ERA-Interim reanalysis compared to the observations (Hodges et al, 2017;Murakami, 2014).…”

Section: Observational and Era-interim Datamentioning

confidence: 99%

See 1 more Smart Citation

Sensitivity of Tropical Cyclone Formation to Resolution‐Dependent and Independent Tracking Schemes in High‐Resolution Climate Model Simulations

Raavi

Walsh

2020

Earth and Space Science

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In the present study, global tropical cyclone (TC) formation characteristics are estimated using two fundamentally different Commonwealth Scientific and Industrial Research Organisation (CSIRO) and Okubo‐Weiss zeta parameter (OWZP) tracking schemes in the reanalysis data and in a high‐resolution climate model with interannually varying sea surface temperatures. Both the schemes have a reasonable global geographical distribution of TC genesis locations with under simulation in the eastern North Atlantic and northwestern Australian regions. The mean annual TC frequency in the model is similar to observations using the CSIRO scheme but higher using the OWZP scheme, whereas the annual frequency in reanalysis using the OWZP scheme is similar to observations but halved using the CSIRO scheme. In the CSIRO scheme, both the resolution‐dependent thresholds and large‐scale climate may play a role for skilful TC formation statistics. In contrast, large‐scale climate leads to changes in OWZP TC detections. This highlights the importance of the large‐scale environment for TC detections in both the tracking schemes. The OWZP scheme can differentiate the monsoon lows from the actual TCs in the north Indian Ocean compared to the CSIRO scheme, which incorrectly detects them as TCs in the monsoon season. The distribution of TC lifetime in the model using the OWZP scheme is similar to observations. Conversely, the CSIRO scheme detected TCs have shorter lifetimes, perhaps due to intrinsic tracking scheme differences. Although the tracking schemes are fundamentally different, the study shows that there exist some similarities between them and for certain TC formation characteristics the OWZP scheme performs better compared to the CSIRO scheme.

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Section: Resultsmentioning

confidence: 99%

Section: Observational and Era-interim Datamentioning

confidence: 99%

Sensitivity of Tropical Cyclone Formation to Resolution‐Dependent and Independent Tracking Schemes in High‐Resolution Climate Model Simulations

Raavi

Walsh

2020

Earth and Space Science

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“…This is done using an objective feature tracking method that tracks all tropical systems through their full life cycles and then matches the tracks against those of IBTrACS to identify the identically same tropical cyclones (TCs); a full description of the tracking and matching methodology is given in Hodges et al . (). This has the benefit of identifying more of the TC life cycle, such as the part before the system is declared a TC and also after it is no longer followed by the operational observing centres.…”

Section: Methodsmentioning

confidence: 97%

Linking extreme precipitation in Southeast Asia to equatorial waves

Ferrett

Yang

Woolnough

et al. 2019

Quart J Royal Meteoro Soc

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Equatorially trapped waves, such as Kelvin Waves, Equatorial Rossby Waves and Westward‐moving Mixed Rossby–Gravity (WMRG) Waves, play a major role in organising tropical convection on synoptic to sub‐seasonal time‐scales. These waves have the potential to provide an important source of predictability for high‐impact weather in Southeast (SE) Asia and the Tropics more widely. To aid understanding of the role played in high‐impact weather by such waves, the observed statistical relationship between identified equatorial waves and heavy rainfall in SE Asia is examined for the period 1998–2016. Increases in the amount of precipitation and the likelihood of extreme precipitation in SE Asia are linked to all three types of waves that are included in analysis; Kelvin, equatorial Rossby and WMRG waves. There is both increased mean rainfall and increased probability of occurrence of heavy rainfall on days when high‐amplitude waves propagate over SE Asia. In particular, heavy precipitation can be up to three times more likely in regions of SE Asia during equatorial waves, including Malaysia, Indonesia and the Philippines. Kelvin waves have a large influence on heavy rainfall over Indonesia, WMRG and Kelvin waves impact Malaysia rainfall, and equatorial Rossby and WMRG waves are linked to increased rainfall over the Philippines. Based on this study it can be concluded that the probability of extreme precipitation in this region is dependent on equatorial wave activity. Therefore, the skill in probabilistic prediction of extreme precipitation in SE Asia would be expected to be conditional on the skill in equatorial wave prediction, and the modelled relationship between equatorial waves and convection.

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“…The tracking algorithm described by Hodges () was applied using a methodology based on Hodges et al (), who use TRACK to identify tropical cyclones, as well as their antecedent and subsequent phases as tropical lows and tropical depressions. This was deemed appropriate since the southern African tropical lows are similar in spatial extent and magnitude to tropical lows which transition into and out from tropical cyclones.…”

Section: Methodsmentioning

confidence: 99%

Tropical Lows in Southern Africa: Tracks, Rainfall Contributions, and the Role of ENSO

2019

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Southern African tropical lows are synoptic‐scale cyclonic vortices that propagate westward across southern Africa in the Austral summer. They strongly influence local rainfall and aggregate in the climatological December, January, and February mean to form the Angola Low. In this study, tropical lows are identified and tracked using an objective feature tracking method. The statistics of tropical low tracks over southern Africa are presented and compared across three reanalysis products. Findings are compared to the literature of tropical low‐pressure areas elsewhere in the world, where it is found that most tracking statistics compare well but that the tendency of tropical lows to become semistationary over Angola is unique to southern Africa. The hypothesis that tropical lows in Angola have a causal relationship with Tropical Temperate Troughs is tested, and a correlation between occurrence frequencies is found at interannual but not daily time scales. Precipitation is attributed to the tropical lows, and it is found that tropical lows are associated with 31% of rainfall across tropical southern Africa, based on gridded precipitation products. The interannual variability of the number of tropical lows that form per year (σ=6 events/year) is linked to El Niño–Southern Oscillation (ENSO) and the tropical easterly jet. The mean latitude of tropical lows is shifted northward during El Niño and southward during La Niña. Much of the interannual precipitation variability maximum in Angola is attributed to rainfall associated with tropical lows. These results provide insights into the southern African response to ENSO and into the mechanisms of rainfall in the southern African tropical edge.

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How Well Are Tropical Cyclones Represented in Reanalysis Datasets?

Cited by 232 publications

References 72 publications

Sensitivity of Tropical Cyclone Formation to Resolution‐Dependent and Independent Tracking Schemes in High‐Resolution Climate Model Simulations

Sensitivity of Tropical Cyclone Formation to Resolution‐Dependent and Independent Tracking Schemes in High‐Resolution Climate Model Simulations

Linking extreme precipitation in Southeast Asia to equatorial waves

Tropical Lows in Southern Africa: Tracks, Rainfall Contributions, and the Role of ENSO

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