scholarly journals Pacific Meridional Mode‐Western North Pacific Tropical Cyclone Linkage Explained by Tropical Pacific Quasi‐Decadal Variability

2019 ◽  
Vol 46 (22) ◽  
pp. 13346-13354 ◽  
Author(s):  
Chao Liu ◽  
Wenjun Zhang ◽  
Malte F. Stuecker ◽  
Fei‐Fei Jin
Keyword(s):  
Tropical Cyclone ◽  
North Pacific ◽  
Western North Pacific ◽  
Decadal Variability ◽  
Tropical Pacific ◽  
Meridional Mode ◽  
Pacific Meridional Mode

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.

Does the Pacific meridional mode dominantly affect tropical cyclogenesis in the western North Pacific?

2020 ◽  
Vol 55 (11-12) ◽  
pp. 3469-3483
Author(s):  
Hongjie Zhang ◽  
Liang Wu ◽  
Ronghui Huang ◽  
Jau-Ming Chen ◽  
Tao Feng
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Tropical Cyclogenesis ◽  
The Pacific ◽  
Meridional Mode ◽  
Pacific Meridional Mode

scholarly journals Attribution of Decadal Variability in Tropical Cyclone Passage Frequency over the Western North Pacific: A New Approach Emphasizing the Genesis Location of Cyclones

2013 ◽  
Vol 26 (3) ◽  
pp. 973-987 ◽  
Author(s):  
Satoru Yokoi ◽  
Yukari N. Takayabu
Keyword(s):  
Tropical Cyclone ◽  
Time Scales ◽  
North Pacific ◽  
Western North Pacific ◽  
Decadal Variability ◽  
The Philippines ◽  
Ocean Basin ◽  
New Approach ◽  
Equal Degree ◽  
Analysis Application

Abstract Variability in tropical cyclone (TC) activity is a matter of direct concern for affected populations. On interannual and longer time scales, variability in TC passage frequency can be associated with total TC frequency over the concerned ocean basin [basinwide frequency (BF)], the spatial distribution of TC genesis in the basin [genesis distribution (GD)], and the preferable track (PT) that can be considered as a function of genesis locations. To facilitate investigation of mechanisms responsible for the variability, the authors propose an approach of decomposing anomalies in the passage frequency into contributions of variability in BF, GD, and PT, which is named the Integration of Statistics on TC Activity by Genesis Location (ISTAGL) analysis. Application of this approach to TC best track data in the western North Pacific (WNP) basin reveals that overall distribution of the passage frequency trends over the 1961–2010 period is mainly due to the PT trends. On decadal time scales, passage frequency variability in midlatitudes is primarily due to PT variability, while the BF and GD also play roles in the subtropics. The authors further discuss decadal variability over the East China Sea in detail. The authors demonstrate that northward shift of the PT for TCs generated around the Philippines Sea and westward shift for TCs generated in the eastern part of the WNP contribute the variability with almost equal degree. The relationships between these PT shifts and anomalies in environmental circulation fields are also discussed.

scholarly journals The Pacific Meridional Mode and the Occurrence of Tropical Cyclones in the Western North Pacific

2015 ◽  
Vol 29 (1) ◽  
pp. 381-398 ◽  
Author(s):  
W. Zhang ◽  
G. A. Vecchi ◽  
H. Murakami ◽  
G. Villarini ◽  
L. Jia
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Climate Model ◽  
Vertical Wind Shear ◽  
Northwestern Part ◽  
Geophysical Fluid Dynamics Laboratory ◽  
The Pacific ◽  
Cyclonic Flow ◽  
Meridional Mode ◽  
Pacific Meridional Mode

Abstract This study investigates the association between the Pacific meridional mode (PMM) and tropical cyclone (TC) activity in the western North Pacific (WNP). It is found that the positive PMM phase favors the occurrence of TCs in the WNP while the negative PMM phase inhibits the occurrence of TCs there. Observed relationships are consistent with those from a long-term preindustrial control experiment (1000 yr) of a high-resolution TC-resolving Geophysical Fluid Dynamics Laboratory (GFDL) Forecast-Oriented Low Ocean Resolution (FLOR) coupled climate model. The diagnostic relationship between the PMM and TCs in observations and the model is further supported by sensitivity experiments with FLOR. The modulation of TC genesis by the PMM is primarily through the anomalous zonal vertical wind shear (ZVWS) changes in the WNP, especially in the southeastern WNP. The anomalous ZVWS can be attributed to the responses of the atmosphere to the anomalous warming in the northwestern part of the PMM pattern during the positive PMM phase, which resembles a classic Matsuno–Gill pattern. Such influences on TC genesis are strengthened by a cyclonic flow over the WNP. The significant relationship between TCs and the PMM identified here may provide a useful reference for seasonal forecasting of TCs and interpreting changes in TC activity in the WNP.

Forced and Internal Variability of Tropical Cyclone Track Density in the Western North Pacific*

2014 ◽  
Vol 28 (1) ◽  
pp. 143-167 ◽  
Author(s):  
Wei Mei ◽  
Shang-Ping Xie ◽  
Ming Zhao ◽  
Yuqing Wang
Keyword(s):  
Tropical Cyclone ◽  
North Pacific ◽  
Western North Pacific ◽  
Decadal Variability ◽  
Function Analysis ◽  
Internal Variability ◽  
Atmospheric Model ◽  
Track Density ◽  
Dipole Mode ◽  
Central Pacific

Abstract Forced interannual-to-decadal variability of annual tropical cyclone (TC) track density in the western North Pacific between 1979 and 2008 is studied using TC tracks from observations and simulations by a 25-km-resolution version of the GFDL High-Resolution Atmospheric Model (HiRAM) that is forced by observed sea surface temperatures (SSTs). Two modes dominate the decadal variability: a nearly basinwide mode, and a dipole mode between the subtropics and lower latitudes. The former mode links to variations in TC number and is forced by SST variations over the off-equatorial tropical central North Pacific, whereas the latter might be associated with the Atlantic multidecadal oscillation. The interannual variability is also controlled by two modes: a basinwide mode driven by SST anomalies of opposite signs located in the tropical central Pacific and eastern Indian Ocean, and a southeast–northwest dipole mode connected to the conventional eastern Pacific ENSO. The seasonal evolution of the ENSO effect on TC activity is further explored via a joint empirical orthogonal function analysis using TC track density of consecutive seasons, and the analysis reveals that two types of ENSO are at work. Internal variability in TC track density is then examined using ensemble simulations from both HiRAM and a regional atmospheric model. It exhibits prominent spatial and seasonal patterns, and it is particularly strong in the South China Sea and along the coast of East Asia. This makes an accurate prediction and projection of TC landfall extremely challenging in these regions. In contrast, basin-integrated metrics (e.g., total TC counts and TC days) are more predictable.

scholarly journals A Far-Reaching Footprint of the Tropical Pacific Meridional Mode on the Summer Rainfall over the Yellow River Loop Valley

2011 ◽  
Vol 24 (10) ◽  
pp. 2585-2598 ◽  
Author(s):  
Chun Li ◽  
Lixin Wu ◽  
Ping Chang
Keyword(s):  
North Pacific ◽  
Yellow River ◽  
Summer Rainfall ◽  
Tropical Pacific ◽  
The Yellow River ◽  
Eastern Hemisphere ◽  
Meridional Mode ◽  
Tropical Pacific Meridional Mode ◽  
Pacific Meridional Mode ◽  
The Tropical Pacific

Abstract Over thousands of years, the vicissitudes of the Yellow River and surrounding geographic environment form a unique river loop in northwestern China, namely, the Yellow River Loop Valley. Results from both observations and a climate model indicate that the summer rainfall over the Yellow River Loop Valley region can be remotely controlled by sea surface temperature fluctuations in the eastern subtropical North Pacific. This far-reaching teleconnection is achieved by an atmospheric wave train emanating from the eastern subtropical North Pacific, with a long traveling journey from the western to the Eastern Hemisphere. Furthermore, it is found that the SST forcing pattern resembles the Tropical Pacific Meridional Mode, a mode characterized by an interhemispheric temperature gradient and shift of the intertropical convergence zone in the eastern tropical Pacific.

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