scholarly journals Has the Western Pacific Subtropical High Extended Westward since the Late 1970s?

2015 ◽  
Vol 28 (13) ◽  
pp. 5406-5413 ◽  
Author(s):  
Liguang Wu ◽  
Chao Wang
Keyword(s):  
Tropical Cyclone ◽  
North Pacific ◽  
Geopotential Height ◽  
Western North Pacific ◽  
Western Pacific Subtropical High ◽  
Summer Rainfall ◽  
Western Pacific ◽  
Subtropical High ◽  
Global Trend ◽  
Summer Rainfall Over China

Abstract Previous studies reported that the summer western Pacific subtropical high (WPSH) has extended westward since the late 1970s and the change has affected summer rainfall over China and tropical cyclone prevailing tracks in the western North Pacific. The authors show that the 500-hPa geopotential height in the midlatitudes of the Northern Hemisphere has trended upward in the warming climate and the westward extension of the WPSH quantified with the 500-hPa geopotential height is mainly a manifestation of the global rising trend. That is, the summer 500-hPa WPSH has not remarkably extended westward since the late 1970s when the global trend is removed. It is suggested that the index that indicates the west–east shift of the summer 500-hPa WPSH should be redefined and that further investigation is needed to understand the observed climate change in the summer rainfall over China and tropical cyclone prevailing tracks in the western North Pacific.

scholarly journals Accumulated Effect of Intra-Seasonal Oscillation Convections over the Tropical Western North Pacific on the Meridional Location of Western Pacific Subtropical High

2020 ◽  
Vol 8 ◽  
Author(s):  
Zongci Huang ◽  
Wenjun Zhang ◽  
Xin Geng ◽  
Pang-Chi Hsu
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Late Summer ◽  
Western Pacific Subtropical High ◽  
Western Pacific ◽  
Subtropical High ◽  
Boreal Summer ◽  
Seasonal Oscillation ◽  
Tropical Western North Pacific ◽  
Sst Anomalies

An extreme northward displacement of the western Pacific subtropical high (WPSH) was detected during the boreal mid-late summer (July-August) of 2018, bringing record-breaking heat waves over northern East Asia. Negative sea surface temperature (SST) anomalies in the northern India Ocean (NIO) are usually accompanied with a northward shift of the WPSH. However, no prominent NIO SST anomalies were observed during the 2018 boreal summer. It is found that this extreme northward-shifted WPSH event is largely attributed to the accumulated effect of intra-seasonal oscillation (ISO) convection anomalies over the tropical western North Pacific (WNP). The accumulated effect on the WPSH meridional location is further supported by their significant correlation based on the data since 1979. While the relationship between the NIO SST anomalies and WPSH meridional location has substantially weakened since the late 1990s, the accumulated effect of the tropical WNP ISO convections keeps playing a crucial role in modulating the WPSH meridional displacement. The active WNP ISO activities can stimulates a poleward propagating Rossby wave train, which favors a northward shift of the WPSH. Our results suggest that the accumulated effect of the tropical WNP ISO convections should be considered when predicting the WPSH during the boreal mid-late summer season.

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 Using eddy geopotential height to measure the western North Pacific subtropical high in a warming climate

2016 ◽  
Vol 131 (1-2) ◽  
pp. 681-691 ◽  
Author(s):  
Chao He ◽  
Ailan Lin ◽  
Dejun Gu ◽  
Chunhui Li ◽  
Bin Zheng ◽  
...  
Keyword(s):  
North Pacific ◽  
Geopotential Height ◽  
Western North Pacific ◽  
Subtropical High ◽  
Warming Climate

scholarly journals Forecasting Summer Rainfall and Streamflow over the Yangtze River Valley Using Western Pacific Subtropical High Feature

Water ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 2580
Author(s):  
Ranran He ◽  
Yuanfang Chen ◽  
Qin Huang ◽  
Wenpeng Wang ◽  
Guofang Li
Keyword(s):  
Yangtze River ◽  
Western Pacific Subtropical High ◽  
Summer Rainfall ◽  
Yangtze River Valley ◽  
River Valley ◽  
Western Pacific ◽  
Subtropical High ◽  
Exceedance Probability ◽  
The Yangtze River ◽  
Extreme Flood

The western Pacific subtropical high (WPSH) is one of the key systems affecting the summer rainfall over the Yangtze River Valley in China. In this study, the forecasting capacity of the WPSH for summer rainfall and streamflow is evaluated based on the WPSH index (WPSHI) derived from the NCEP/NCAR reanalysis dataset. It has been found that WPSHI can identify extreme flood years with a higher skill than normal wet years. Specifically, exceedance probability forecasting based on WPSHI has higher skills for higher thresholds of rainfall. For streamflow, adding WPSHI as a predictor only enhances the skill for higher thresholds of streamflow relative to models based on antecedent streamflow. Under the same framework, performances of two postprocessing approaches for dynamical forecasts, i.e., the model output statistics (MOS) approach and the reanalysis-based (RAN) approach are compared. Hindcasts from Climate Forecast System version 2 from the National Center for Environmental Prediction (CFSv2) are used to calculate WPSHI, which is used as the predictor for rainfall and streamflow. The result shows that the RAN approach performs better than the MOS approach. This study emphasizes the fact that the forecasting skill of exceedance probability would largely depend on the selected threshold of the predictand, and this fact should be noticed in future studies in the long-term forecasting field.

scholarly journals Tropical Cloud Cluster Environments and Their Importance for Tropical Cyclone Formation

2019 ◽  
Vol 32 (13) ◽  
pp. 4069-4088 ◽  
Author(s):  
Hsu-Feng Teng ◽  
Cheng-Shang Lee ◽  
Huang-Hsiung Hsu ◽  
James M. Done ◽  
Greg J. Holland
Keyword(s):  
Tropical Cyclone ◽  
Environmental Conditions ◽  
North Pacific ◽  
Western North Pacific ◽  
Subtropical High ◽  
Low Latitude ◽  
Brightness Temperatures ◽  
Cloud Cluster ◽  
Potential Index ◽  
Circulation Patterns

Abstract This study uses a nonhierarchical cluster analysis to identify the major environmental circulation patterns associated with tropical cloud cluster (TCC) formation in the western North Pacific. All TCCs that formed in July–October 1981–2009 are examined based on their 850-hPa wind field around TCC centers. Eight types of environmental circulation patterns are identified. Of these, four are related to monsoon systems (trough, confluence, north of trough, and south of trough), three are related to easterly systems (low-latitude zone, west of subtropical high, and southwest of subtropical high), and one is associated with low-latitude cross-equatorial flow. The genesis potential index (GPI) is analyzed to compare how favorable the environmental conditions are for tropical cyclone (TC) formation when TCCs form. Excluding three cluster types with the GPI lower than the climatology of all samples, TCCs formed in monsoon environments have larger sizes, lower brightness temperatures, longer lifetimes, and higher GPIs than those of TCCs formed in easterly environments. However, for TCCs formed in easterly environments, the average GPI for those TCCs that later develop into TCs (developing TCCs) is higher than that for other TCCs (nondeveloping TCCs). This difference is nonsignificant for TCCs formed in monsoon environments. Conversely, the average magnitudes of GPI are similar for developing TCCs, regardless of whether TCCs form in easterly or monsoon environments. In summary, the probability of a TCC to develop into a TC is more sensitive to the environmental conditions for TCCs formed in easterly environments than those formed in monsoon environments.

The western Pacific subtropical high and tropical cyclone landfall: Seasonal forecasts using the Met Office GloSea5 system

2019 ◽  
Vol 145 (718) ◽  
pp. 105-116 ◽  
Author(s):  
Joanne Camp ◽  
Malcolm J. Roberts ◽  
Ruth E. Comer ◽  
Peili Wu ◽  
Craig MacLachlan ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Western Pacific Subtropical High ◽  
Western Pacific ◽  
Subtropical High ◽  
Seasonal Forecasts ◽  
The Western Pacific ◽  
Tropical Cyclone Landfall
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