scholarly journals Decadal-Scale Modulation of Atmospheric Circulation Change at the Onset of the Western North Pacific Summer Monsoon

SOLA ◽  
2013 ◽  
Vol 9 (0) ◽  
pp. 161-165 ◽  
Author(s):  
Tomohiko Tomita ◽  
Tsuyoshi Yamaura ◽  
Yuta Kuwazuru
Keyword(s):  
Atmospheric Circulation ◽  
Summer Monsoon ◽  
North Pacific ◽  
Western North Pacific ◽  
Circulation Change ◽  
Decadal Scale ◽  
Atmospheric Circulation Change

scholarly journals Change in Tropical Cyclone Activity during the Break of the Western North Pacific Summer Monsoon in Early August

2016 ◽  
Vol 29 (7) ◽  
pp. 2457-2469 ◽  
Author(s):  
Ke Xu ◽  
Riyu Lu
Keyword(s):  
Tropical Cyclone ◽  
Summer Monsoon ◽  
North Pacific ◽  
Western North Pacific ◽  
Cyclonic Circulation ◽  
Tropical Cyclone Activity ◽  
Upward Motion ◽  
Mariana Islands ◽  
Cyclone Activity

Abstract The modulation of tropical cyclone (TC) activity by the western North Pacific (WNP) monsoon break is investigated by analyzing the subseasonal evolution of TCs and corresponding circulations, based on 65 years of data from 1950 to 2014. The monsoon break has been identified as occurring over the WNP in early August. The present results show that TC occurrence decreases (increases) remarkably to the east of the Mariana Islands (southeast of Japan) during the monsoon break, which is closely related to local anomalous midtropospheric downward (upward) motion and lower-tropospheric anticyclonic (cyclonic) circulation, in comparison with the previous and subsequent convective periods in late July and mid-August. These changes of TC activity and the corresponding circulation during the monsoon break are more significant in typical monsoon break years when the monsoon break phenomenon is predominant. The reverse changes of TC activity to the east of the Mariana Islands and to the southeast of Japan during the monsoon break are closely associated with the out-of-phase subseasonal evolutions over these two regions from late July to mid-August, which are both contributed to greatly by 10–25-day oscillations. Finally, the roles of midlatitude and tropical disturbances on 10–25-day oscillations are also discussed.

scholarly journals Climatological Increased Precipitation from July to August in the Western North Pacific Region Simulated by CMIP6 Models

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 664
Author(s):  
Xiao Dong ◽  
Renping Lin
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Vertical Motion ◽  
Atmospheric Model ◽  
Coupled Models ◽  
Model Simulations ◽  
Observational Analysis ◽  
Budget Analysis ◽  
Circulation Change ◽  
Precipitation Increase

In this study, the climatological precipitation increase from July to August over the western North Pacific (WNP) region was investigated through observations and simulations in the Coupled Model Intercomparison Project Phase 6 (CMIP6), atmospheric model simulations and historical experiments. Firstly, observational analysis showed that the precipitation increase is associated with a decrease in the local sea surface temperature (SST), indicating that the precipitation increase is not driven by the change in SST. In addition, the pattern of precipitation increase is similar to the vertical motion change at 500-hPa, suggesting that the precipitation increase is related to the circulation change. Moisture budget analysis further confirmed this relation. In addition to the observational analysis, the outputs from 26 CMIP6 models were further evaluated. Compared with atmospheric model simulations, air–sea coupled models largely improve the simulation of the climatological precipitation increase from July to August. Furthermore, model simulations confirmed that the bias in the precipitation increase is intimately associated with the circulation change bias. Thus, two factors are responsible for the bias of the precipitation increase from July to August in climate models: air–sea coupling processes and the performance in vertical motion change.

scholarly journals Tropical cyclone-related socio-economic losses in the western North Pacific region

2013 ◽  
Vol 13 (1) ◽  
pp. 115-124 ◽  
Author(s):  
C. Welker ◽  
E. Faust
Keyword(s):  
Purchasing Power Parity ◽  
North Pacific ◽  
Western North Pacific ◽  
Economic Losses ◽  
Future Research ◽  
Northwest Pacific ◽  
Pacific Region ◽  
Power Parity ◽  
Decadal Scale ◽  
Loss Data

Abstract. The western North Pacific (WNP) is the area of the world most frequently affected by tropical cyclones (TCs). However, little is known about the socio-economic impacts of TCs in this region, probably because of the limited relevant loss data. Here, loss data from Munich RE's NatCatSERVICE database is used, a high-quality and widely consulted database of natural disasters. In the country-level loss normalisation technique we apply, the original loss data are normalised to present-day exposure levels by using the respective country's nominal gross domestic product at purchasing power parity as a proxy for wealth. The main focus of our study is on the question of whether the decadal-scale TC variability observed in the Northwest Pacific region in recent decades can be shown to manifest itself economically in an associated variability in losses. It is shown that since 1980 the frequency of TC-related loss events in the WNP exhibited, apart from seasonal and interannual variations, interdecadal variability with a period of about 22 yr – driven primarily by corresponding variations of Northwest Pacific TCs. Compared to the long-term mean, the number of loss events was found to be higher (lower) by 14% (9%) in the positive (negative) phase of the decadal-scale WNP TC frequency variability. This was identified for the period 1980–2008 by applying a wavelet analysis technique. It was also possible to demonstrate the same low-frequency variability in normalised direct economic losses from TCs in the WNP region. The identification of possible physical mechanisms responsible for the observed decadal-scale Northwest Pacific TC variability will be the subject of future research, even if suggestions have already been made in earlier studies.

scholarly journals Global Extratropical Response to Diabatic Heating Variability of the Asian Summer Monsoon

2009 ◽  
Vol 66 (9) ◽  
pp. 2697-2713 ◽  
Author(s):  
Hai Lin
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
North Pacific ◽  
Western North Pacific ◽  
Large Scale ◽  
Asian Summer Monsoon ◽  
Convective Activity ◽  
Mean Flow ◽  
Asian Summer ◽  
Circulation Anomalies

Abstract Global teleconnections associated with the Asian summer monsoon convective activities are investigated based on monthly data of 29 Northern Hemisphere summers defined as June–September (JJAS). Two distinct teleconnection patterns are identified that are associated respectively with variabilities of the Indian summer monsoon and the western North Pacific summer monsoon. The Indian summer monsoon convective activity is associated with a global pattern that has a far-reaching connection in both hemispheres, whereas the western North Pacific summer monsoon convective activity is connected to a Southern Hemisphere wave train that influences the high-latitude South Pacific and South America. A global primitive equation model is utilized to assess the cause of the global circulation anomalies. The model responses to anomalous heatings of both monsoon systems match the general features of the observed circulation anomalies well, and they are mainly controlled by linear processes. The response patterns are largely determined by the summertime large-scale background mean flow and the location of the heating anomaly relative to the upper easterly jet in the monsoon region.

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