scholarly journals Interannual Variability of the Tropical Cyclone Landfall Frequency over the Southern and Northern Regions of East Asia in Autumn

2019 ◽  
Vol 32 (24) ◽  
pp. 8677-8686 ◽  
Author(s):  
Xingyan Zhou ◽  
Riyu Lu
Keyword(s):  
Tropical Cyclone ◽  
East Asia ◽  
Interannual Variability ◽  
North Pacific ◽  
Western North Pacific ◽  
Southern Oscillation ◽  
Northern Region ◽  
Teleconnection Pattern ◽  
Wave Source ◽  
Steering Flow

Abstract This study focused on the interannual variability of tropical cyclone (TC) activity over the western North Pacific in autumn. The results show that the frequencies of TC landfalls in the southern and northern coastal regions of East Asia are roughly independent, implying that they are affected by different factors and should be studied separately. Further analysis indicates that the frequency of TC landfall in the southern region is closely related to El Niño–Southern Oscillation, which affects both the upper- and lower-tropospheric circulation over the western North Pacific and East Asia and induces changes in the steering flow. By contrast, the frequency of TC landfall over the northern region has a close connection with a teleconnection pattern in the upper troposphere over the Eurasian continent, which seems to be triggered by an anomalous Rossby wave source over the North Atlantic. This teleconnection pattern leads to anomalous meridional winds over the western North Pacific and East Asia and induces significant changes in the steering flow.

scholarly journals Interannual and interdecadal impact of Western North Pacific Subtropical High on tropical cyclone activity

2020 ◽  
Vol 54 (3-4) ◽  
pp. 2237-2248 ◽  
Author(s):  
Qiong Wu ◽  
Xiaochun Wang ◽  
Li Tao
Keyword(s):  
Tropical Cyclone ◽  
North Pacific ◽  
Western North Pacific ◽  
Southern Oscillation ◽  
Subtropical High ◽  
Interdecadal Change ◽  
Steering Flow ◽  
The Pacific ◽  
Sea Surface Temperature Anomalies ◽  
Peak Phase

AbstractIn this study, we analyzed the impacts of Western North Pacific Subtropical High (WNPSH) on tropical cyclone (TC) activity on both interannual and interdecadal timescales. Based on a clustering analysis method, we grouped TCs in the Western North Pacific into three clusters according to their track patterns. We mainly focus on Cluster 1 (C1) TCs in this work, which is characterized by forming north of 15° N and moving northward. On interannual timescale, the number of C1 TCs is influenced by the intensity variability of the WNPSH, which is represented by the first Empirical Orthogonal Function (EOF) of 850 hPa geopotential height of the region. The WNPSH itself is modulated by the El Niño–Southern Oscillation at its peak phase in the previous winter, as well as Indian and Atlantic Ocean sea surface temperature anomalies in following seasons. The second EOF mode shows the interdecadal change of WNPSH intensity. The interdecadal variability of WNPSH intensity related to the Pacific climate regime shift could cause anomalies of the steering flow, and lead to the longitudinal shift of C1 TC track. Negative phases of interdecadal Pacific oscillation are associated with easterly anomaly of steering flow, westward shift of C1 TC track, and large TC impact on the East Asia coastal area.

scholarly journals Interannual Variability of Summer Tropical Cyclone Rainfall in the Western North Pacific Depicted by CFSR and Associated Large-Scale Processes and ISO Modulations

2018 ◽  
Vol 31 (5) ◽  
pp. 1771-1787 ◽  
Author(s):  
Jau-Ming Chen ◽  
Pei-Hua Tan ◽  
Liang Wu ◽  
Hui-Shan Chen ◽  
Jin-Shuen Liu ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Interannual Variability ◽  
El Niño ◽  
North Pacific ◽  
Western North Pacific ◽  
Large Scale ◽  
El Nino ◽  
Southern Oscillation ◽  
Monsoon Trough ◽  
Tropical Eastern Pacific

This study examines the interannual variability of summer tropical cyclone (TC) rainfall (TCR) in the western North Pacific (WNP) depicted by the Climate Forecast System Reanalysis (CFSR). This interannual variability exhibits a maximum region near Taiwan (19°–28°N, 120°–128°E). Significantly increased TCR in this region is modulated by El Niño–Southern Oscillation (ENSO)-related large-scale processes. They feature elongated sea surface temperature warming in the tropical eastern Pacific and a southeastward-intensified monsoon trough. Increased TC movements are facilitated by interannual southerly/southeasterly flows in the northeastern periphery of the intensified monsoon trough to move from the tropical WNP toward the region near Taiwan, resulting in increased TCR. The coherent dynamic relations between interannual variability of summer TCR and large-scale environmental processes justify CFSR as being able to reasonably depict interannual characteristics of summer TCR in the WNP. For intraseasonal oscillation (ISO) modulations, TCs tend to cluster around the center of a 10–24-day cyclonic anomaly and follow its northwestward propagation from the tropical WNP toward the region near Taiwan. The above TC movements are subject to favorable background conditions provided by a northwest–southeasterly extending 30–60-day cyclonic anomaly. Summer TCR tends to increase (decrease) during El Niño (La Niña) years and strong (weak) ISO years. By comparing composite TCR anomalies and correlations with TCR variability, it is found that ENSO is more influential than ISO in modulating the interannual variability of summer TCR in the WNP.

scholarly journals Contributions of SST Anomalies in the Indo-Pacific Ocean to the Interannual Variability of Tropical Cyclone Genesis Frequency over the Western North Pacific

2019 ◽  
Vol 32 (11) ◽  
pp. 3357-3372 ◽  
Author(s):  
Ruifen Zhan ◽  
Yuqing Wang ◽  
Jiuwei Zhao
Keyword(s):  
Pacific Ocean ◽  
Tropical Cyclone ◽  
Statistical Model ◽  
Interannual Variability ◽  
North Pacific ◽  
Western North Pacific ◽  
Southern Oscillation ◽  
Typhoon Season ◽  
Genesis Frequency ◽  
Sst Anomalies

Abstract This study attempts to evaluate quantitatively the contributions of sea surface temperature (SST) anomalies in the Indo-Pacific Ocean to the interannual variability of tropical cyclone (TC) genesis frequency (TCGF) over the western North Pacific (WNP). Three SST factors in the Indo-Pacific Ocean are found to play key roles in modulating the interannual variability of WNP TCGF. They are summer SST anomaly in the east Indian Ocean (EIO), the summer El Niño–Southern Oscillation Modoki index (EMI), and the spring SST gradient (SSTG) between the southwestern Pacific and the western Pacific warm pool. Results show that the three factors together can explain 72% of the total variance of WNP TCGF in the typhoon season for the period 1980–2015. Among them, the spring SSTG and the summer EIO contribute predominantly to the interannual variability of TCGF, followed by the summer EMI, with respective contributions being 39%, 38%, and 23%. Further analysis shows that the summer EMI was affected significantly by the spring SSTG and thus had a relatively lower contribution to the TCGF than the spring SSTG. In addition, a statistical model is constructed to predict the WNP TCGF in the typhoon season by a combination of the May EIO and the spring SSTG. The new model can reproduce well the observed WNP TCGF and shows an overall better skill than the ECMWF Seasonal Forecasting System 5 (SEAS5) hindcasts. This statistical model provides a good tool for seasonal prediction of WNP TCGF.

Interannual Variability of the Basinwide Translation Speed of Tropical Cyclones in the Western North Pacific

2020 ◽  
Vol 33 (20) ◽  
pp. 8641-8650
Author(s):  
Chao Wang ◽  
Liguang Wu ◽  
Jun Lu ◽  
Qingyuan Liu ◽  
Haikun Zhao ◽  
...  
Keyword(s):  
Interannual Variability ◽  
North Pacific ◽  
Western North Pacific ◽  
Large Scale ◽  
Southern Oscillation ◽  
Temporal Variations ◽  
Vital Role ◽  
Translation Speed ◽  
Late Season ◽  
Steering Flow

AbstractUnderstanding variations in tropical cyclone (TC) translation speed (TCS) is of great importance for islands and coastal regions since it is an important factor in determining TC-induced local damages. Investigating the long-term change in TCS was usually subject to substantial limitations in the quality of historical TC records, but here we investigated the interannual variability in TCS over the western North Pacific (WNP) Ocean by using reliable satellite TC records. It was found that both temporal changes in large-scale steering flow and TC track greatly contributed to interannual variability in the WNP TCS. In the peak season (July–September), TCS changes were closely related to temporal variations in large-scale steering flow, which was linked to the intensity of the western North Pacific subtropical high. However, for the late season (October–December), changes in TC track played a vital role in interannual variability in TCS while the impacts of temporal variations in large-scale steering were weak. The changes in TC track were mainly contributed by the El Niño–Southern Oscillation (ENSO)-induced zonal migrations in TC genesis locations, which make more or fewer TCs move to the subtropical WNP, thus leading to notable changes in the basinwide TCS because of the much greater large-scale steering in the subtropical WNP. The increased influence of TC track change on TCS in the late season was linked to the greater contrast between the subtropical and the tropical large-scale steering in the late season. These results have important implications for understanding current and future variations in TCS.

scholarly journals Association of the Poleward Shift of East Asian Subtropical Upper-Level Jet with Frequent Tropical Cyclone Activities over the Western North Pacific in Summer

2017 ◽  
Vol 30 (14) ◽  
pp. 5597-5603 ◽  
Author(s):  
Xian Chen ◽  
Zhong Zhong ◽  
Wei Lu
Keyword(s):  
Tropical Cyclone ◽  
North Pacific ◽  
Western North Pacific ◽  
Large Scale ◽  
East Asian ◽  
Teleconnection Pattern ◽  
Reanalysis Dataset ◽  
Poleward Shift ◽  
Upper Level ◽  
Upper Level Jet

The NCEP–NCAR reanalysis dataset and the tropical cyclone (TC) best-track dataset from the Regional Specialized Meteorological Center (RSMC) Tokyo Typhoon Center were employed in the present study to investigate the possible linkage of the meridional displacement of the East Asian subtropical upper-level jet (EASJ) with the TC activity over the western North Pacific (WNP). Results indicate that summertime frequent TC activities would create the poleward shift of the EASJ through a stimulated Pacific–Japan (PJ) teleconnection pattern as well as the changed large-scale meridional temperature gradient. On the contrary, in the inactive TC years, the EASJ is often located more southward than normal with an enhanced intensity. Therefore, TC activities over the WNP are closely related to the location and intensity of the EASJ in summer at the interannual time scale.

scholarly journals Future Change in Tropical Cyclone Activity over the Western North Pacific in CORDEX-East Asia Multi-RCMs Forced by HadGEM2-AO

2019 ◽  
Vol 32 (16) ◽  
pp. 5053-5067 ◽  
Author(s):  
Hyeonjae Lee ◽  
Chun-Sil Jin ◽  
Dong-Hyun Cha ◽  
Minkyu Lee ◽  
Dong-Kyou Lee ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
East Asia ◽  
North Pacific ◽  
Western North Pacific ◽  
Climate Models ◽  
Regional Climate ◽  
Vertical Wind Shear ◽  
Coastal Regions ◽  
The Future ◽  
Cordex East Asia

AbstractFuture changes in tropical cyclone (TC) activity over the western North Pacific (WNP) are analyzed using four regional climate models (RCMs) within the Coordinated Regional Climate Downscaling Experiment (CORDEX) for East Asia. All RCMs are forced by the HadGEM2-AO under the historical and representative concentration pathway (RCP) 8.5 scenarios, and are performed at about 50-km resolution over the CORDEX-East Asia domain. In the historical simulations (1980–2005), multi-RCM ensembles yield realistic climatology for TC tracks and genesis frequency during the TC season (June–November), although they show somewhat systematic biases in simulating TC activity. The future (2024–49) projections indicate an insignificant increase in the total number of TC genesis (+5%), but a significant increase in track density over East Asia coastal regions (+17%). The enhanced TC activity over the East Asia coastal regions is mainly related to vertical wind shear weakened by reduced meridional temperature gradient and increased sea surface temperature (SST) at midlatitudes. The future accumulated cyclone energy (ACE) of total TCs increases significantly (+19%) because individual TCs have a longer lifetime (+6.6%) and stronger maximum wind speed (+4.1%) compared to those in the historical run. In particular, the ACE of TCs passing through 25°N increases by 45.9% in the future climate, indicating that the destructiveness of TCs can be significantly enhanced in the midlatitudes despite the total number of TCs not changing greatly.

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

2019 ◽  
Vol 32 (23) ◽  
pp. 8021-8045 ◽  
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.

Evaluation of climatological tropical cyclone activity over the western North Pacific in the CORDEX-East Asia multi-RCM simulations

2015 ◽  
Vol 47 (3-4) ◽  
pp. 765-778 ◽  
Author(s):  
Chun-Sil Jin ◽  
Dong-Hyun Cha ◽  
Dong-Kyou Lee ◽  
Myoung-Seok Suh ◽  
Song-You Hong ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
East Asia ◽  
North Pacific ◽  
Western North Pacific ◽  
Tropical Cyclone Activity ◽  
Cyclone Activity ◽  
Cordex East Asia
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