Impacts of the East Asian winter monsoon on winter precipitation variability over East Asia-western North Pacific

2022 ◽  
Author(s):  
Zhenzhen Wang ◽  
Renguang Wu ◽  
Yuqi Wang
2014 ◽  
Vol 27 (21) ◽  
pp. 8185-8204 ◽  
Author(s):  
Gyundo Pak ◽  
Young-Hyang Park ◽  
Frederic Vivier ◽  
Young-Oh Kwon ◽  
Kyung-Il Chang

Abstract The East Asian winter monsoon (EAWM) and the North Pacific Oscillation (NPO) constitute two outstanding surface atmospheric circulation patterns affecting the winter sea surface temperature (SST) variability in the western North Pacific. The present analyses show the relationship between the EAWM and NPO and their impact on the SST are nonstationary and regime-dependent with a sudden change around 1988. These surface circulation patterns are tightly linked to the upper-level Ural and Kamchatka blockings, respectively. During the 1973–87 strong winter monsoon epoch, the EAWM and NPO were significantly correlated to each other, but their correlation practically vanishes during the 1988–2002 weak winter monsoon epoch. This nonstationary relationship is related to the pronounced decadal weakening of the Siberian high system over the Eurasian continent after the 1988 regime shift as well as the concomitant positive NPO-like dipole change and its eastward migration in tropospheric circulation over the North Pacific. There is a tight tropical–extratropical teleconnection in the western North Pacific in the strong monsoon epoch, which disappears in the weak monsoon epoch when there is a significant eastward shift of tropical influence and enhanced storm tracks into the eastern North Pacific. A tentative mechanism of the nonstationary relationship between the EAWM and NPO is proposed, stressing the pivotal role played in the above teleconnection by a decadal shift of the East Asian trough resulting from the abrupt decline of the EAWM since the late 1980s.


2009 ◽  
Vol 22 (3) ◽  
pp. 600-614 ◽  
Author(s):  
Lin Wang ◽  
Wen Chen ◽  
Wen Zhou ◽  
Ronghui Huang

Abstract Interannual variations of the East Asian trough (EAT) axis at 500 hPa are studied with the European Centre for Medium-Range Weather Forecasts 40-yr reanalysis data. The associated circulation pattern and pathway of the East Asian winter monsoon (EAWM) with the EAT axis tilt are specially investigated with a trough axis index, which is closely related to the midlatitude baroclinic process and mainly represents the intensity of the eddy-driven jet over the East Asia–North Pacific sector. When the tilt of EAT is smaller than normal, the EAWM prefers to take the southern pathway and less cold air moves to the central North Pacific. However, the EAWM prefers the eastern pathway and brings more cold air to the North Pacific when the tilt of EAT is larger than normal. These differences induce pronounced changes in both the precipitation and the surface air temperature over East and Southeast Asia. Furthermore, the tilt status of the EAT has a significant modulation effect on the regional climate anomalies related to the intensity of the EAWM. The findings suggest an increase in the temperature anomaly associated with the EAWM intensity and a clear northward–southward shift in its pattern in anomalous tilt phase of the EAT. In addition, the modulation tends to be confined mainly to East Asia and expanded to a larger area during the weak and the strong EAWM winters, respectively. The possible reasons for interannual variations of the EAT tilt are discussed, and it is speculated that the midlatitude air–sea interaction in the North Pacific plays a dominant role. This study on the EAT tilt may enrich knowledge of the East Asian winter monsoon beyond the conventional intensity index and may be helpful to improve regional climate prediction in East Asia.


2020 ◽  
Vol 33 (24) ◽  
pp. 10671-10690
Author(s):  
Tianjiao Ma ◽  
Wen Chen ◽  
Hans-F. Graf ◽  
Shuoyi Ding ◽  
Peiqiang Xu ◽  
...  

AbstractThe present study investigates different impacts of the East Asian winter monsoon (EAWM) on surface air temperature (Ts) in North America (NA) during ENSO and neutral ENSO episodes. In neutral ENSO years, the EAWM shows a direct impact on the Ts anomalies in NA on an interannual time scale. Two Rossby wave packets appear over the Eurasian–western Pacific (upstream) and North Pacific–NA (downstream) regions associated with a strong EAWM. Further analysis suggests that the downstream wave packet is caused by reflection of the upstream wave packet over the subtropical western Pacific and amplified over the North Pacific. Also, the East Asian subtropical westerly jet stream (EAJS) is intensified in the central and downstream region over the central North Pacific. Hence, increased barotropic kinetic energy conversion and the interaction between transient eddies and the EAJS tend to maintain the circulation anomaly over the North Pacific. Therefore, a strong EAWM tends to result in warm Ts anomalies in northwestern NA via the downstream wave packet emanating from the central North Pacific toward NA. A weak EAWM tends to induce cold Ts anomalies in western-central NA with a smaller magnitude. However, in ENSO years, an anomalous EAJS is mainly confined over East Asia and does not extend into the central North Pacific. The results confirm that the EAWM has an indirect impact on the Ts anomalies in NA via a modulation of the tropical convection anomalies associated with ENSO. Our results indicate that, for seasonal prediction of Ts anomalies in NA, the influence of the EAWM should be taken into account. It produces different responses in neutral ENSO and in ENSO years.


2009 ◽  
Vol 5 (2) ◽  
pp. 1215-1229
Author(s):  
H. F. Zhu ◽  
X. Q. Fang ◽  
X. M. Shao ◽  
Z. Y. Yin

Abstract. Long-term climatic records are scarce in the northeast Asia for understanding the behavior of the East Asian Winter Monsoon. Here we describe a 250-year February–April temperature reconstruction (TCBM) based on tree-ring widths of Korean Pines from the Changbai Mountain area, Northeast China. The reconstruction can account for 45.7% of the temperature variance in the instrumental period (1953 to 2001). Four cold events including 1784–1815, 1827–1851, 1878–1889 and 1911–1945, and two warm events of 1750–1783 and 1855–1877 were identified before the instrumental period. Four regime shifts were also detected at 1781, 1857, 1878 and 1989. Good agreements between TCBM and other temperature records of East Asia suggest that the reconstruction is of good reliability and captures the regional cold/warm events of East Asia. Moreover, TCBM shows negative correlations with the instrumental or proxy-based EAWM intensity records. The known weakening of the EAWM in the late 1980s is in agreement with the regime shift at 1989 in TCBM. These comparisons suggest that the February–April temperature reconstruction may be a good indicator of the EAWM intensity.


2020 ◽  
Vol 33 (6) ◽  
pp. 2389-2406
Author(s):  
Yu-heng Tseng ◽  
Ruiqiang Ding ◽  
Sen Zhao ◽  
Yi-chun Kuo ◽  
Yu-chiao Liang

AbstractThis study investigates the modulation of North Pacific Oscillation (NPO) variability upon initiation of the East Asian winter monsoon (EAWM). The data show that the initiation of EAWM in the Philippine Sea strongly connects to the southern lobe variability of the NPO in January followed by a basin-scale oceanic Victoria mode pattern. No apparent connection was found for the northern lobe of the NPO when the ENSO signals are removed. The strengthening of the EAWM in November interacts with the Kuroshio front and generates a low-level heating source in the Philippine Sea. Significant Rossby wave sources are then formed in the lower to midtroposphere. Wave ray tracing analyses confirm the atmospheric teleconnection established by the Rossby wave propagation in the mid- to upper troposphere. Analyses of the origin of wave trajectories from the Philippine Sea show a clear eastward propagating pathway that affects the southern lobe of the NPO from the southern lobe of the western Pacific pattern at 500 hPa and above on the time scale of 20 days. No ray trajectories from the lower troposphere can propagate eastward to influence the central-eastern subtropical Pacific. The wave propagation process is further supported by the coupled model experiments.


Sign in / Sign up

Export Citation Format

Share Document