Revisiting the Relationship Between Tropical Cyclone Size and Intensity Over the Western North Pacific

The relationship between ocean subsurface temperature and tropical cyclone (TC) over the western North Pacific (WNP) is studied based on the TC best-track data and global reanalysis data during the period of 1948–2012. Here the TC frequency (TCF), lifespan, and genesis position of TCs are analysed. A distinctive negative correlation between subsurface water temperature and TCF is observed, especially the TCF in the southeastern quadrant of the WNP (0–15°N, 150–180°E). According to the detrended subsurface temperature anomalies of the 125 m depth layer in the main TC genesis area (0–30°N, 100–180°E), we selected the subsurface cold and warm years. During the subsurface cold years, TCs tend to have a longer mean lifespan and a more southeastern genesis position than the subsurface warm years in general. To further investigate the causes of this characteristic, the TC genesis potential indexes (GPI) are used to analyse the contributions of environmental factors to TC activities. The results indicate that the negative correlation between subsurface water temperature and TCF is mainly caused by the variation of TCF in the southeastern quadrant of the WNP, where the oceanic and atmospheric environments are related to ocean subsurface conditions. Specifically, compared with the subsurface warm years, there are larger relative vorticity, higher relative humidity, smaller vertical wind shear, weaker net longwave radiation, and higher ocean mixed layer temperature in the southeastern quadrant during cold years, which are all favorable for genesis and development of TC.

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Seasonality and El Niño Diversity in the Relationship between ENSO and Western North Pacific Tropical Cyclone Activity

Journal of Climate ◽

10.1175/jcli-d-18-0736.1 ◽

2019 ◽

Vol 32 (23) ◽

pp. 8021-8045 ◽

Cited By ~ 2

Author(s):

Yumi Choi ◽

Kyung-Ja Ha ◽

Fei-Fei Jin

Keyword(s):

Tropical Cyclone ◽

Seasonal Change ◽

El Niño ◽

North Pacific ◽

Western North Pacific ◽

El Nino ◽

Southern Oscillation ◽

Central Pacific ◽

Southeastern Part ◽

The Relationship

Abstract Both the impacts of two types of El Niño on the western North Pacific (WNP) tropical cyclone (TC) activity and the seasonality in the relationship between genesis potential index (GPI) and El Niño–Southern Oscillation (ENSO) are investigated. The ENSO-induced GPI change over the northwestern (southeastern) part of the WNP is mostly attributed to the relative humidity (absolute vorticity) term, revealing a distinct meridional and zonal asymmetry in summer and fall, respectively. The seasonal change in ENSO (background states) from summer to fall is responsible for the seasonal change in GPI anomalies south of 20°N (over the northeastern part of the WNP). The downdraft induced by the strong upper-level convergence in the eastern Pacific (EP)-type El Niño and both the northwestward-shifted relative vorticity and northward-extended convection over the southeastern part of the WNP in the central Pacific (CP)-type El Niño lead to distinct TC impacts over East Asia (EA). The southward movement of genesis location of TCs and increased westward-moving TCs account for the enhanced strong typhoon activity for the EP-type El Niño in summer. In fall the downdraft and anomalous anticyclonic steering flows over the western part of the WNP remarkably decrease TC impacts over EA. The enhanced moist static energy and midlevel upward motion over the eastern part of the WNP under the northern off-equatorial sea surface temperature warming as well as longer passage of TCs toward EA are responsible for the enhanced typhoon activity for the CP-type El Niño. It is thus important to consider the seasonality and El Niño pattern diversity to explore the El Niño–induced TC impacts over EA.

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Implications of the Observed Relationship between Tropical Cyclone Size and Intensity over the Western North Pacific

Journal of Climate ◽

10.1175/jcli-d-15-0628.1 ◽

2015 ◽

Vol 28 (24) ◽

pp. 9501-9506 ◽

Cited By ~ 22

Author(s):

Liguang Wu ◽

Wei Tian ◽

Qingyuan Liu ◽

Jian Cao ◽

John A. Knaff

Keyword(s):

Numerical Simulation ◽

Tropical Cyclone ◽

Numerical Simulations ◽

North Pacific ◽

Western North Pacific ◽

Horizontal Resolution ◽

Wind Damage ◽

Nonlinear Relationship ◽

Rainfall Distribution ◽

The Relationship

Abstract Tropical cyclone (TC) size, usually measured with the radius of gale force wind (34 kt or 17 m s−1), is an important parameter for estimating TC risks such as wind damage, rainfall distribution, and storm surge. Previous studies have reported that there is a very weak relationship between TC size and TC intensity. A close examination presented here using satellite-based wind analyses suggests that the relationship between TC size and intensity is nonlinear. TC size generally increases with increasing TC maximum sustained wind before a maximum of 2.50° latitude at an intensity of 103 kt or 53.0 m s−1 and then slowly decreases as the TC intensity further increases. The observed relationship between TC size and intensity is compared to the relationships produced by an 11-yr seasonal numerical simulation of TC activity. The numerical simulations were able to produce neither the observed maximum sustained winds nor the observed nonlinear relationship between TC size and intensity. This finding suggests that TC size cannot reasonably be simulated with 9-km horizontal resolution and increased resolution is needed to study TC size variations using numerical simulations.

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The relationship of frequent tropical cyclone activities over the western North Pacific and hot summer days in central-eastern China

Theoretical and Applied Climatology ◽

10.1007/s00704-019-02908-7 ◽

2019 ◽

Vol 138 (3-4) ◽

pp. 1395-1404 ◽

Cited By ~ 1

Author(s):

Zhong Zhong ◽

Xian Chen ◽

Xiu-Qun Yang ◽

Yao Ha ◽

Yuan Sun

Keyword(s):

Tropical Cyclone ◽

North Pacific ◽

Western North Pacific ◽

Eastern China ◽

Central Eastern ◽

Relationship Of ◽

The Relationship

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Statistical Analysis of the Relationship between Upper Tropospheric Cold Lows and Tropical Cyclone Genesis over the Western North Pacific

Journal of the Meteorological Society of Japan Ser II ◽

10.2151/jmsj.2019-025 ◽

2019 ◽

Vol 97 (2) ◽

pp. 439-451 ◽

Cited By ~ 3

Author(s):

Hironori FUDEYASU ◽

Ryuji YOSHIDA

Keyword(s):

Statistical Analysis ◽

Tropical Cyclone ◽

North Pacific ◽

Western North Pacific ◽

Tropical Cyclone Genesis ◽

Cyclone Genesis ◽

The Relationship

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A Statistical Analysis of the Relationship between Upper-Tropospheric Cold Low and Tropical Cyclone Track and Intensity Change over the Western North Pacific

Monthly Weather Review ◽

10.1175/mwr-d-15-0370.1 ◽

2016 ◽

Vol 144 (5) ◽

pp. 1805-1822 ◽

Cited By ~ 6

Author(s):

Na Wei ◽

Ying Li ◽

Da-Lin Zhang ◽

Zi Mai ◽

Shi-Qi Yang

Keyword(s):

Tropical Cyclone ◽

North Pacific ◽

Western North Pacific ◽

Reanalysis Data ◽

Intensity Change ◽

Cyclone Track ◽

Cutoff Distance ◽

The Impact ◽

The Relationship ◽

Early Late

The geographical and temporal characteristics of upper-tropospheric cold low (UTCL) and their relationship to tropical cyclone (TC) track and intensity change over the western North Pacific (WNP) during 2000–12 are examined using the TC best track and global meteorological reanalysis data. An analysis of the two datasets shows that 73% of 346 TCs coexist with 345 UTCLs, and 21% of the latter coexist with TCs within an initial cutoff distance of 15°. By selecting those coexisted systems within this distance, the possible influences of UTCL on TC track and intensity change are found, depending on their relative distance and on the sectors of UTCLs where TCs are located. Results show that the impact of UTCLs on TC directional changes are statistically insignificant when averaged within the 15° radius. However, left-turning TCs within 5° distance from the UTCL center exhibit large deviated directional changes from the WNP climatology, due to the presence of highly frequent abrupt left turnings in the eastern semicircle of UTCL. The abrupt turnings of TCs are often accompanied by their slow-down movements. Results also show that TCs seem more (less) prone to intensify at early (late) development stages when interacting with UTCLs compared to the WNP climatology. Intensifying (weakening) TCs are more distributed in the southern (northern) sectors of UTCLs, with less hostile conditions for weakening within 9°–13° radial range. In addition, rapid intensifying TCs take place in the south-southwest and east-southeast sectors of UTCLs, whereas rapid weakening cases appear in the western semicircle of UTCLs due to their frequent proximity to mainland coastal regions.

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Interbasin Differences in the Relationship between SST and Tropical Cyclone Intensification

Monthly Weather Review ◽

10.1175/mwr-d-17-0155.1 ◽

2018 ◽

Vol 146 (3) ◽

pp. 853-870 ◽

Cited By ~ 9

Author(s):

Gregory R. Foltz ◽

Karthik Balaguru ◽

Samson Hagos

Keyword(s):

Tropical Cyclone ◽

North Pacific ◽

Western North Pacific ◽

Vertical Wind Shear ◽

Western Pacific ◽

Eastern Pacific ◽

Sst Cooling ◽

The Pacific ◽

The Relationship ◽

The Western Pacific

Sea surface temperature (SST) is one of the most important parameters for tropical cyclone (TC) intensification. Here, it is shown that the relationship between SST and TC intensification varies considerably from basin to basin, with SST explaining less than 4% of the variance in TC intensification rates in the Atlantic, 12% in the western North Pacific, and 23% in the eastern Pacific. Several factors are shown to be responsible for these interbasin differences. First, variability of SST along TCs’ tracks is lower in the Atlantic. This is due to smaller horizontal SST gradients in the Atlantic, compared to the Pacific, and stronger damping of prestorm SST’s contribution to TC intensification by the storm-induced cold SST wake in the Atlantic. The damping occurs because SST tends to vary in phase with TC-induced SST cooling: in the Gulf of Mexico and northwestern Atlantic, where SSTs are highest, TCs tend to be strongest and their translations slowest, resulting in the strongest storm-induced cooling. The tendency for TCs to be more intense over the warmest SST in the Atlantic also limits the usefulness of SST as a predictor since stronger storms are less likely to experience intensification. Finally, SST tends to vary out of phase with vertical wind shear and outflow temperature in the western Pacific. This strengthens the relationship between SST and TC intensification more in the western Pacific than in the eastern Pacific or Atlantic. Combined, these factors explain why prestorm SST is such a poor predictor of TC intensification in the Atlantic, compared to the eastern and western North Pacific.

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