Intercomparison of Dvorak Parameters in the Tropical Cyclone Datasets over the Western North Pacific

Nakazawa, Tetsuo; Hoshino, Shunsuke

doi:10.2151/sola.2009-009

Cited by 42 publications

(51 citation statements)

References 8 publications

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“…In a second step, we derive wind speed from CI numbers by applying the original Dvorak conversion table (Dvorak 1984) used in JTWC (hereafter DT conversion). It is possible that the Koba conversion table was applied only to intensity records starting in 1991 and previous years were not updated to the new procedures (Nakazawa and Hoshino 2009). However, the remapping method using the Koba conversion table was applied for the complete analysis.…”

Section: Methodsmentioning

confidence: 99%

“…In the early 2000s CI discrepancies are still higher, especially for categories 4-5. Two periods of the strongest CI discrepancies were also identified by Nakazawa and Hoshino (2009) The reasons for changes in time of CI discrepancies can be related to separately evolving practices and usage of different information sources by operational centers. JMA reports geostationary satellites to be the principal source of TC localization and intensity estimation.…”

Section: Can the Reasons For Discrepancies Between Btdmentioning

confidence: 97%

“…As the provided TC reconstruction may be also biased due to the 10-km horizontal resolution, this can complicate the evaluation of BTD. On the other hand, the JTWC report (Joint Typhoon Warning Center 2009) Nakazawa and Hoshino (2009) also noticed differences in operational (CI and T) numbers among various BTD, both for intensification and weakening phases. Differing weakening ratios, after reaching TC maximum intensity in BTDs, indicate that there may be differences between definitions for allowable intensity change (in the form of CI and T parameters).…”

Section: F Accuracy Of Intensity Estimations Given By Btdsmentioning

confidence: 99%

“…Knaff and Sampson (2006) considered any detected intensity trend questionable before reanalyses employing datasets of TC intensity estimated with alternative techniques are incorporated. Others attempted to identify the reasons for the differences between BTD that affect TC activity trends (Kamahori et al 2006;Nakazawa and Hoshino 2009;Song et al 2010). Many studies highlighted the different operational procedures used by the individual meteorological agencies to estimate TC intensity as a main cause for differing TC activity results.…”

Section: Introductionmentioning

confidence: 99%

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Usability of Best Track Data in Climate Statistics in the Western North Pacific

Barcikowska

Feser

Storch

2012

Monthly Weather Review

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Tropical cyclone (TC) activity for the last three decades shows strong discrepancies, deduced from different best track datasets (BTD) for the western North Pacific (WNP). This study analyzes the reliability of BTDs in deriving climate statistics for the WNP. Therefore, TC lifetime, operational parameters [current intensity (CI) number], and tracks are compared (for TCs identified concurrently) in BTD provided by the Joint Typhoon Warning Center (JTWC), the Japan Meteorological Agency (JMA), and the China Meteorological Administration (CMA).The differences between the BTD are caused by varying algorithms used in weather services to estimate TC intensity. Available methods for minimizing these discrepancies are not sufficient. Only if intensity categories 2-5 are considered as a whole, do trends for annually accumulated TC days show a similar behavior. The reasons for remaining discrepancies point to extensive and not regular usage of supplementary sources in JTWC. These are added to improve the accuracy of TC intensity and center position estimates. Track and CI differences among BTDs coincide with a strong increase in the number of intense TC days in JTWC. These differences are very strong in the period of intensive improvement of spatiotemporal satellite coverage .Scatterometer-based data used as a reference show that for the tropical storm phase JMA provides more reliable TC intensities than JTWC. Comparisons with aircraft observations indicate that not only homogeneity, but also a harmonization and refinement of operational rules controlling intensity estimations, should be implemented in all agencies providing BTD.

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Section: Methodsmentioning

confidence: 99%

Section: Can the Reasons For Discrepancies Between Btdmentioning

confidence: 97%

Section: F Accuracy Of Intensity Estimations Given By Btdsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Usability of Best Track Data in Climate Statistics in the Western North Pacific

Barcikowska

Feser

Storch

2012

Monthly Weather Review

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“…Subsequent studies have also pointed out related problems such as a different wind-pressure relationship in different periods (Emanuel 2007;Knaff & Zehr 2007) or performed sub-sampling to estimate the actual frequency of intense TCs (Chang & Guo 2007;. Kamahori et al (2006), Wu et al (2006) and Nakazawa & Hoshino (2009) have also pointed out the differences in intensity estimates in the western North Pacific (WNP) among different warning centres after the termination of aircraft reconnaissance. It is decided that the 'official' best-track datasets will be used for the present study instead of 'modifying' the best-track datasets based on the results from these subsequent studies for the following reasons.…”

Section: Data and Methodology (A) Datamentioning

confidence: 99%

Thermodynamic control on the climate of intense tropical cyclones

Chan

2009

Proc. R. Soc. A.

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How thermodynamic factors control the climate of intense tropical cyclones (TCs) is investigated by examining the relationship between the seasonally averaged maximum potential intensity (MPI, used as a representative index of the thermodynamic forcing) over an ocean basin where TCs form and the seasonal frequency of occurrence of intense TCs. It is found that only in the Atlantic does the MPI have a statistically significant relationship with the number of intense TCs, explaining about 40 per cent of the variance. In other ocean basins, there is either no correlation or the correlation is not statistically significant. In other words, only in the Atlantic are thermodynamic factors responsible, but still only to a certain extent, for the climate variations of intense TCs. In other ocean basins, it appears that the dynamic factors are much more dominant. Such a conclusion has important implications in considering whether global warming may influence the future climate of intense TCs for the following reason. Although it has been generally accepted that the thermodynamic energy available in the atmosphere is likely to increase under global warming, the results from this study suggest that such an increase does not necessarily imply a concomitant increase in the number of intense TCs, because how the dynamic factors will vary are still not clear. Until we can demonstrate that the dynamic factors will also become more favourable for TC intensification, it remains uncertain whether the frequency of occurrence of intense TCs will increase under a global warming scenario.

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Interagency discrepancies in tropical cyclone intensity estimates over the western North Pacific in recent years

Bai

Tang

et al. 2022

Atmospheric Science Letters

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This study investigates interagency discrepancies among best‐track estimates of tropical cyclone (TC) intensity in the western North Pacific, provided by the Joint Typhoon Warning Center (JTWC), the China Meteorological Administration (CMA), and the Regional Specialized Meteorological Center (RSMC) Tokyo during 2013 to 2019. The results reveal evident differences in maximum wind speed (MSW) estimates, where linear systematic differences are significant. However, the Dvorak parameter (CI) numbers derived from the MSWs reported by the three agencies are internally consistent. Further analysis suggests that the remained CI discrepancies are related to differences in the estimation of intensity trends, initial intensities, and TC positions among these datasets. In addition, the CI estimates provided by the JTWC for TCs over the open ocean are generally higher than those reported by the CMA and RSMC. However, the estimates from CMA and RSMC tend to give higher TC intensities for the TCs in the mainland and coastal areas of China and Japan, respectively, than those over the open ocean with the same intensity in JTWC dataset. This pattern potentially reflects the extensive use of surface observations by these two agencies for landfalling and offshore TCs. These results may help the research community to get more accurate details about the TCs in WNP from the best track datasets of different agencies.

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Intercomparison of Dvorak Parameters in the Tropical Cyclone Datasets over the Western North Pacific

Cited by 42 publications

References 8 publications

Usability of Best Track Data in Climate Statistics in the Western North Pacific

Usability of Best Track Data in Climate Statistics in the Western North Pacific

Thermodynamic control on the climate of intense tropical cyclones

Interagency discrepancies in tropical cyclone intensity estimates over the western North Pacific in recent years

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