Dynamically Derived Tropical Cyclone Intensity Changes over the Western North Pacific

Wu, Liguang; Zhao, Haikun

doi:10.1175/2011jcli4139.1

Cited by 71 publications

(75 citation statements)

References 26 publications

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“…The landfall rarity of intense North Indian Ocean hurricanes means the data are too noisy for analysis. For the western North Pacific the trend is very weak and slightly negative, which we attribute to a general eastward and equatorward movement of the main genesis location in recent decades (Wu and Zhao 2012). This promotes the development of a higher proportion of intense hurricanes, but also means that fewer of them will make landfall.…”

Section: Analysis Issuesmentioning

confidence: 75%

“…The weaker trend may be attributed to two factors: the automated Dvorak analysis used by Kossin may underestimate the most intense storms, or there may be an artificial analysis trend in the archived data. On a regional basis, Wu and Zhao (2012) applied the Emanuel (2008) dynamical downscaling approach to reanalysis data for the western North Pacific and found a significant increase in the frequency of Cat 4-5 hurricanes ( Table 1) that is similar to that in Fig. 4b after taking proportions, but at around half the rate.…”

Section: Analysis Issuesmentioning

confidence: 93%

“…We further compare the observed changes to recent climate simulations with the dynamical downscaling results of Bender et al (2010), Done et al (2012), and Wu and Zhao (2012).…”

Section: Datamentioning

confidence: 97%

“…Varying approaches to converting the Dvorak analysis to intensity has resulted in a divergence of intensity trends amongst the centers, with the JTWC data containing an increasing intensity trend and the HKO and RSMC a decreasing one (Wu et al 2006;Song et al 2010). Wu and Zhao (2012) examined these discrepancies using the Emanuel (2008) statistical-dynamical downscaling technique. They found an increasing intensity trend that also is supported by observed relationships with SST and vertical shear, and is in broad agreement with the observed increasing tendency for equatorial developments and longer time spent in favorable conditions.…”

Section: Datamentioning

confidence: 99%

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Recent intense hurricane response to global climate change

2013

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An Anthropogenic Climate Change Index (ACCI) is developed and used to investigate the potential global warming contribution to current tropical cyclone activity. The ACCI is defined as the difference between the means of ensembles of climate simulations with and without anthropogenic gases and aerosols. This index indicates that the bulk of the current anthropogenic warming has occurred in the past four decades, which enables improved confidence in assessing hurricane changes as it removes many of the data issues from previous eras. We find no anthropogenic signal in annual global tropical cyclone or hurricane frequencies. But a strong signal is found in proportions of both weaker and stronger hurricanes: the proportion of Category 4 and 5 hurricanes has increased at a rate of *25-30 % per°C of global warming after accounting for analysis and observing system changes. This has been balanced by a similar decrease in Category 1 and 2 hurricane proportions, leading to development of a distinctly bimodal intensity distribution, with the secondary maximum at Category 4 hurricanes. This global signal is reproduced in all ocean basins. The observed increase in Category 4-5 hurricanes may not continue at the same rate with future global warming. The analysis suggests that following an initial climate increase in intense hurricane proportions a saturation level will be reached beyond which any further global warming will have little effect.

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Section: Analysis Issuesmentioning

confidence: 75%

Section: Analysis Issuesmentioning

confidence: 93%

“…We further compare the observed changes to recent climate simulations with the dynamical downscaling results of Bender et al (2010), Done et al (2012), and Wu and Zhao (2012).…”

Section: Datamentioning

confidence: 97%

Section: Datamentioning

confidence: 99%

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Recent intense hurricane response to global climate change

2013

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“…Recent studies (Wu and Zhao 2012; suggested that the frequency of intense TCs (categories 4 and 5 on the Saffir-Simpson scale) and the lifetime maximum intensity are more sensitive to large-scale environmental conditions and changes. Thereby, the two metrics are employed to investigate the inter-annual variability of TC intensity.…”

Section: Comparison Of Tc Simulations Using the Two Types Of Ensemblementioning

confidence: 99%

Simulation of tropical cyclone activity over the western North Pacific based on CMIP5 models

Han

Zhou

Zhao

2017

Theor Appl Climatol

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Based on the Coupled Model Inter-comparison Project 5 (CMIP5) models, the tropical cyclone (TC) activity in the summers of 1965-2005 over the western North Pacific (WNP) is simulated by a TC dynamically downscaling system. In consideration of diversity among climate models, Bayesian model averaging (BMA) and equal-weighed model averaging (EMA) methods are applied to produce the ensemble large-scale environmental factors of the CMIP5 model outputs. The environmental factors generated by BMA and EMA methods are compared, as well as the corresponding TC simulations by the downscaling system. Results indicate that BMA method shows a significant advantage over the EMA. In addition, impacts of model selections on BMA method are examined. To each factor, ten models with better performance are selected from 30 CMIP5 models and then conduct BMA, respectively. As a consequence, the ensemble environmental factors and simulated TC activity are similar with the results from the 30 models' BMA, which verifies the BMA method can afford corresponding weight for each model in the ensemble based on the model's predictive skill. Thereby, the existence of poor performance models will not particularly affect the BMA effectiveness and the ensemble outcomes are improved. Finally, based upon the BMA method and downscaling system, we analyze the sensitivity of TC activity to three important environmental factors, i.e., sea surface temperature (SST), large-scale steering flow, and vertical wind shear. Among three factors, SST and large-scale steering flow greatly affect TC tracks, while average intensity distribution is sensitive to all three environmental factors. Moreover, SST and vertical wind shear jointly play a critical role in the inter-annual variability of TC lifetime maximum intensity and frequency of intense TCs.

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Exploratory analysis of extremely low tropical cyclone activity during the late‐season of 2010 and 1998 over the western North Pacific and the South China Sea

Zhao

Chu

Hsu

et al. 2014

J Adv Model Earth Syst

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This study attempts to understand why the tropical cyclone (TC) frequency over the western North Pacific and the South China Sea was so low in 2010 and 1998 even though a strong La Niña signal occurred in both years. We found that the TC frequency during the late-season (October to December), not in the peak season (July to September), makes 2010 a record low year; the next lowest year is 1998. Specifically, four TCs were observed over the South China Sea (SCS) in the late-season of 1998, but no TCs occurred over the SCS in the same season during 2010. The genesis potential index is used to help diagnose changes in environmental conditions for TC genesis frequency. Results indicate that the decreased low-level vorticity makes the largest contribution to the decreased TC formation over the SCS. The second largest contribution comes from the enhanced vertical wind shear, with relatively small contributions from the negative anomaly in potential intensity and reduction in midlevel relative humidity. These observational results are consistent with numerical simulations using a state of the art model from the Meteorological Research Institute (MRI-AGCM 3.2 Model). Numerical experiments show that the unfavorable conditions for sharply decreased TC formation during the late-season over the SCS in 2010 mainly results from the sea surface temperature anomaly over the western North Pacific basin. This effect is partly offset by the sea surface temperature anomaly in the South Indian Ocean and Northern Indian Ocean basins.

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Dynamically Derived Tropical Cyclone Intensity Changes over the Western North Pacific

Cited by 71 publications

References 26 publications

Recent intense hurricane response to global climate change

Recent intense hurricane response to global climate change

Simulation of tropical cyclone activity over the western North Pacific based on CMIP5 models

Exploratory analysis of extremely low tropical cyclone activity during the late‐season of 2010 and 1998 over the western North Pacific and the South China Sea

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