Multi-decadal variations of ENSO, the Pacific Decadal Oscillation and tropical cyclones in the western North Pacific

2012 ◽  
Vol 105 ◽  
pp. 67-80 ◽  
Author(s):  
Han Soo Lee ◽  
Takao Yamashita ◽  
Toyoaki Mishima
Keyword(s):  
Tropical Cyclones ◽  
Pacific Decadal Oscillation ◽  
North Pacific ◽  
Western North Pacific ◽  
The Pacific ◽  
Decadal Variations

scholarly journals Strong Modulation of the Pacific Meridional Mode on the Occurrence of Intense Tropical Cyclones over the Western North Pacific

2018 ◽  
Vol 31 (19) ◽  
pp. 7739-7749 ◽  
Author(s):  
Si Gao ◽  
Langfeng Zhu ◽  
Wei Zhang ◽  
Zhifan Chen
Keyword(s):  
Tropical Cyclones ◽  
North Pacific ◽  
Western North Pacific ◽  
Vertical Wind Shear ◽  
Low Level ◽  
The Pacific ◽  
Main Development ◽  
Development Region ◽  
Meridional Mode ◽  
Pacific Meridional Mode

This study finds a significant positive correlation between the Pacific meridional mode (PMM) index and the frequency of intense tropical cyclones (TCs) over the western North Pacific (WNP) during the peak TC season (June–November). The PMM influences the occurrence of intense TCs mainly by modulating large-scale dynamical conditions over the main development region. During the positive PMM phase, anomalous off-equatorial heating in the eastern Pacific induces anomalous low-level westerlies (and cyclonic flow) and upper-level easterlies (and anticyclonic flow) over a large portion of the main development region through a Matsuno–Gill-type Rossby wave response. The resulting weaker vertical wind shear and larger low-level relative vorticity favor the genesis of intense TCs over the southeastern part of the WNP and their subsequent intensification over the main development region. The PMM index would therefore be a valuable predictor for the frequency of intense TCs over the WNP.

scholarly journals The Influence of ENSO on Decadal Variations in the Relationship between the East Asian and Western North Pacific Summer Monsoons

2008 ◽  
Vol 21 (13) ◽  
pp. 3165-3179 ◽  
Author(s):  
So-Young Yim ◽  
Sang-Wook Yeh ◽  
Renguang Wu ◽  
Jong-Ghap Jhun
Keyword(s):  
Summer Monsoon ◽  
North Pacific ◽  
Western North Pacific ◽  
Model Simulation ◽  
East Asian ◽  
Precipitation Variability ◽  
Large Variability ◽  
The Pacific ◽  
Decadal Variations ◽  
The Relationship

Abstract A recent study suggested that the relationship between the East Asian summer monsoon (EASM) and the western North Pacific summer monsoon (WNPSM) experienced a decadal change around 1993–94. Based on a longer-term integration of a hybrid coupled model, the present study investigates decadal variations in the relationship between the EASM and the WNPSM. Apparent decadal variations in the above relationship have been identified in the model simulation. The authors have analyzed the spatial pattern and variability during strong and weak EASM–WNPSM correlation periods. The purpose of this study is to understand potential reasons for decadal variations in the relationship between the two submonsoons. It is found that the precipitation variability associated with the WNPSM (ENSO) is enhanced over the East Asia and western North Pacific regions during periods when the EASM–WNPSM relationship is strong (weak). The large variability in precipitation associated with the WNPSM during strong periods strengthens the Pacific–Japan-like atmospheric teleconnection from the tropical western Pacific. In contrast, the Pacific–Japan-like pattern is not significant during weak periods. On the other hand, the large ENSO amplitude during weak periods results in an enhanced precipitation variability associated with ENSO. The results suggest that ENSO can destructively interfere with the relationship between the EASM and the WNPSM.

scholarly journals What Caused The Increase of Tropical Cyclones In The Western North Pacific During The Period of 2011-2020?

2021 ◽  
Author(s):  
Haili Wang ◽  
Chunzai Wang
Keyword(s):  
Tropical Cyclones ◽  
North Pacific ◽  
High Frequency ◽  
Western North Pacific ◽  
Large Scale ◽  
Low Frequency ◽  
Vertical Wind Shear ◽  
Significant Negative Correlation ◽  
Relative Vorticity ◽  
The Pacific

Abstract Based on satellite era data after 1979, we find that the tropical cyclone (TC) variations in the Western North Pacific (WNP) can be divided into three-periods: a high-frequency period from 1979-1997 (P1), a low-frequency period from 1998-2010 (P2), and a high-frequency period from 2011-2020 (P3). Previous studies have focused on WNP TC activity during P1 and P2. Here we use observational data to study the WNP TC variation and its possible mechanisms during P3. Compared with P2, more TCs during P3 are due to the large-scale atmospheric environmental conditions of positive relative vorticity, negative vertical velocity and weak vertical wind shear. Warmer SST is found during P3, which is favorable for TC genesis. The correlation between the WNP TC frequency and SST shows a significant positive correlation around the equator and a significant negative correlation around 36°N, which is similar to the warm phase of the Pacific Decadal Oscillation (PDO). The correlation coefficient between the PDO and TC frequency is 0.71, significant at 99% confidence level. The results indicate that the increase of the WNP TC frequency during 2011-2020 is associated with the phase transition of the PDO and warmer SST. Therefore, more attention should be given to the warmer SST and PDO phase when predicting WNP TC activity.

scholarly journals The Footprint of Atlantic Multidecadal Oscillation on the Intensity of Tropical Cyclones Over the Western North Pacific

2020 ◽  
Vol 8 ◽  
Author(s):  
Cheng Sun ◽  
Yusen Liu ◽  
Zhanqiu Gong ◽  
Fred Kucharski ◽  
Jianping Li ◽  
...  
Keyword(s):  
Tropical Cyclones ◽  
North Pacific ◽  
Western North Pacific ◽  
Deep Convection ◽  
Convective Available Potential Energy ◽  
Atlantic Multidecadal Oscillation ◽  
Average Intensity ◽  
Decadal Variations ◽  
Primary Driver ◽  
Sst Warming

Sea surface temperature (SST) over the western North Pacific (WNP) exhibits strong decadal to multidecadal variability and in this region, warm waters fuel the tropical cyclones (TCs). Observational records show pronounced decadal variations in WNP TC metrics during 1950–2018. Statistical analysis of the various TC metrics suggests that the annual average intensity of WNP TCs is closely linked to the AMO (r = 0.86 at decadal timescales, p < 0.05). Observations and coupled atmosphere-ocean simulations show that the decadal WNP SST variations regarded as the primary driver of TC intensity, are remotely controlled by the AMO. Corresponding to the WNP SST warming, the local SLP gets lower and the tropospheric air becomes warmer and moister, enhancing atmospheric instability and the generation of convective available potential energy. These favorable changes in the background environment provide more “fuel” to the development of deep convection and intensify the WNP TCs. The footprints of AMO in WNP SST and atmospheric states through trans-basin interaction eventually exert a significant impact on the TC intensity over the WNP region.

scholarly journals Climatic Variation of Maximum Intensification Rate for Major Tropical Cyclones over the Western North Pacific

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 494
Author(s):  
Xiangbai Wu ◽  
Xiao-Hai Yan ◽  
Yan Li ◽  
Huan Mei ◽  
Yuei-An Liou ◽  
...  
Keyword(s):  
Tropical Cyclones ◽  
Environmental Conditions ◽  
North Pacific ◽  
Western North Pacific ◽  
Southern Oscillation ◽  
Heat Content ◽  
Vertical Wind Shear ◽  
Maximum Acceleration ◽  
The Pacific ◽  
Scale Category

To analyze the dependence of intensification rates of tropical cyclones (TCs) on the variation of environmental conditions, an index is proposed here to measure the lifetime maximum intensification rates (LMIRs) for the Saffir–Simpson scale category 4–5 TCs over the western North Pacific. To quantitatively describe the intensification rate of major TCs, the LMIR is defined as the maximum acceleration in the sustained-wind-speed over a 24-h period of an overwater TC. This new index, LMIR, is generally independent of the indices for RI frequency. The results show that the Pacific Decadal Oscillation (PDO) modulates the inter-annual relationship between the LMIR and El Niño/Southern Oscillation (ENSO). The PDO’s modulation on the ENSO’s effect on the LMIR is explored here by considering the relationship between the LMIR and the environmental conditions in different PDO phases. While the ENSO’s effect on the LMIR for the warm PDO phase is generally by affecting the variations of upper ocean heat content, ENSO mainly influences the variations of zonal wind and vertical wind shear for the cold PDO phase. Our results suggest that fast translating TCs tend to attain strong intensification during the warm PDO phase, while a warm subsurface condition may permit slow-translating TCs also to become strongly intensified during the cooling PDO phase. These findings have an important implication for both prediction of RI and the long-term projection of TC activities in the western North Pacific.

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