Phase transition of the Pacific decadal oscillation and decadal variation of the East Asian summer monsoon in the 20th century

The effects of urbanization over eastern China on the East Asian summer monsoon (EASM) under different sea surface temperature background are compared using a Community Atmosphere Model (CAM5.1). Experiments of urbanization investigated by comparing two climate simulations with and without urban land cover under both positive and negative phases of Pacific Decadal Oscillation (PDO) show the spatial distribution of precipitation with ‘southern flood and northern drought’ and weakening status of EASM. The climate effect of urbanization in eastern China is significantly different from north to south. Anomalous vertical ascending motion due to the role of urbanization in the south of 30° N have induced an increase in convective available potential energy (CAPE) and precipitation increase over southern China. At the same time, the downward vertical motion occurs in the north of 30° N which cause warming over northern China. Due to the anti-cyclonic anomalies in the upper and lower layers of the north, the monsoon circulation is weakened which can reduce the precipitation. However, urbanization impact under various phases of PDO show different effect. In the 1956–1970 urbanization experiments of negative PDO phase, the downward vertical motion and anti-cyclonic anomalies in the north of 30° N are also weaker than that of positive phase of PDO in 1982–1996. In terms of this situation, the urbanization experiments of negative phase of PDO reveal that the range of the warming area over the north of 40° N is small, and the warming intensity is weak, but the precipitation change is more obvious compared with the background of positive phase of PDO.

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The Crucial Role of Internal Variability in Modulating the Decadal Variation of the East Asian Summer Monsoon–ENSO Relationship during the Twentieth Century

Journal of Climate ◽

10.1175/jcli-d-14-00783.1 ◽

2015 ◽

Vol 28 (18) ◽

pp. 7093-7107 ◽

Cited By ~ 27

Author(s):

Fengfei Song ◽

Tianjun Zhou

Keyword(s):

Twentieth Century ◽

Summer Monsoon ◽

East Asian Summer Monsoon ◽

Crucial Role ◽

Asian Summer Monsoon ◽

East Asian ◽

Internal Variability ◽

Decadal Variation ◽

Asian Summer

Abstract This study investigates the role of internal variability in modulating the East Asian summer monsoon (EASM)–ENSO relationship using Twentieth-Century Reanalysis (20CR) data and simulations from phase 5 of CMIP (CMIP5). Analysis of 20CR data reveals an unstable EASM–ENSO relationship during the twentieth century. During the high-correlation periods of 1892–1912 and 1979–99, an evident western Pacific anticyclone (WPAC) and dipole sea level pressure (SLP) pattern are present in the decaying El Niño summer, accompanied by Indian Ocean warming and a tropospheric temperature Matsuno–Gill pattern. However, these are weaker or absent during low-correlation periods (1914–34 and 1958–78). After removing the external forcings based on historical simulations from 15 CMIP5 models, all the above features remain almost unchanged, suggesting the crucial role of internal variability. In a 501-yr preindustrial control (piControl) simulation without external forcing variation from CCSM4, the EASM–ENSO relationship also shows significant decadal variation, with a magnitude comparable to the 20CR data. The analysis demonstrates that the EASM–ENSO relationship’s variation is modulated by the interdecadal Pacific oscillation (IPO). Compared to negative IPO phases, the warmer East China Sea in positive IPO phases weakens the western North Pacific subtropical high (WNPSH), inducing more precipitation. Thus, the Kelvin wave–induced interannual divergence suppresses more mean-state precipitation and leads to a stronger WPAC. Hence, the IPO modulates the EASM–ENSO relationship through the WNPSH, which is evident in both 20CR and the piControl simulation.

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Decadal Variations of the East Asian Summer Monsoon Forced by the 11-Year Insolation Cycle

Journal of Climate ◽

10.1175/jcli-d-18-0288.1 ◽

2019 ◽

Vol 32 (10) ◽

pp. 2735-2745 ◽

Cited By ~ 4

Author(s):

Chunhan Jin ◽

Jian Liu ◽

Bin Wang ◽

Mi Yan ◽

Liang Ning

Keyword(s):

Solar Activity ◽

Solar Cycle ◽

Summer Monsoon ◽

North Pacific ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

Decadal Variation ◽

Solar Forcing ◽

Asian Summer

Statistical evidence suggests that solar activity may affect the atmospheric circulation over East Asia (EA), but the way in which the 11-yr solar radiation cycle affects the East Asian summer monsoon (EASM) remains unexplained. Based on one control experiment and four solar-only forcing experiments performed during the Community Earth System Model–Last Millennium Ensemble (CESM-LME) model project, we explore the potential impacts of the 11-yr solar cycle on EASM variability and the physical processes through which solar forcing influences EASM decadal variability. The model results show that the warm season [May–September (MJJAS)] mean precipitation over EA exhibits significant decadal variation with a “northern wet–southern dry” pattern during peak years in the strong 11-yr solar cycle epoch (AD 900–1285), which is in contrast to the absence of decadal signals during the weak 11-yr solar cycle epoch (AD 1400–1535). For the four-member ensemble averaged solar-only forcing experiment, the summer mean precipitation over northern EA is significantly correlated with the solar forcing ( r = 0.414, n = 68, p < 0.05) on a decadal time scale during the strong cycle epoch, whereas there is no statistical link between the EASM and solar activity during the weak cycle epoch ( r = 0.002, n = 24). A strong, 11-yr solar cycle is also shown to excite an anomalous sea surface temperature (SST) pattern that resembles a cool Pacific decadal oscillation (PDO) phase, which has a significant 11-yr periodicity. The associated anomalous North Pacific anticyclone dominates the entire extratropical North Pacific and enhances the southerly monsoon over EA, which results in abundant rainfall over northern EA. We argue that the 11-yr solar cycle affects the EASM decadal variation through excitation of a coupled decadal mode in the Asia–North Pacific region.

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Natural interdecadal weakening of East Asian summer monsoon in the late 20th century

Chinese Science Bulletin ◽

10.1360/982005-36 ◽

2005 ◽

Vol 50 (17) ◽

pp. 1923 ◽

Cited By ~ 57

Author(s):

Dabang JIANG

Keyword(s):

20Th Century ◽

Summer Monsoon ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

Late 20Th Century ◽

Asian Summer

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Seasonal precipitation in the south-central Helan Mountain region, China, reconstructed from tree-ring width for the past 224 years

Canadian Journal of Forest Research ◽

10.1139/x05-168 ◽

2005 ◽

Vol 35 (10) ◽

pp. 2403-2412 ◽

Cited By ~ 67

Author(s):

Yu Liu ◽

Qiufang Cai ◽

Jiangfeng Shi ◽

M K Hughes ◽

J E Kutzbach ◽

...

Keyword(s):

20Th Century ◽

Summer Monsoon ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

Early Summer ◽

Climatic Conditions ◽

Mountain Region ◽

Asian Summer ◽

Helan Mountain

Chinese pine (Pinus tabulaeformis Carr.) trees from the Helan Mountain range in central China have been used to reconstruct total JanuaryJuly precipitation from AD 1775 to 1998. For the calibration period R2adj = 0.52. Narrow rings are associated with below-average precipitation from March through August. Wide rings are produced in years when the East Asian summer monsoon front arrives early. We use local historical writings over the last 300 years about extreme climatic conditions between spring and early summer to verify the extreme years. Most of the extreme dry years could be identified in local historical documents. Another East Asian summer monsoon front related precipitation reconstruction from northern Helan Mountain is also used to verify this reconstruction. They are well correlated from year to year, with a correlation coefficient of 0.52 (N = 218), and the wet or dry extreme events are well matched in many cases. This comparison could indicate a spatial and temporal connection of spring to early summer climatic conditions for the southern to northern portion of the Helan Mountain region. The sustained wet period before the 20th century lasts from the 1850s to the 1890s, and the longest dry period before the 20th century is in the 1830s and 1840s, largely coinciding with a springsummer drought in Kashmir. Overall, multiyear fluctuations, such as the spectacular large-scale drought of the late 1920s and droughts in the 1830s1840s and the 1970s, are well captured in this reconstruction, but only the 1970s drought is in the instrumental period. The reconstruction shows increasing variance from the 18th to the late 20th century.

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Impacts of the Atlantic Multidecadal Oscillation on the Relationship of the Spring Arctic Oscillation and the Following East Asian Summer Monsoon

Journal of Climate ◽

10.1175/jcli-d-19-0978.1 ◽

2020 ◽

Vol 33 (15) ◽

pp. 6651-6672

Author(s):

Shangfeng Chen ◽

Wen Chen ◽

Renguang Wu ◽

Linye Song

Keyword(s):

Summer Monsoon ◽

North Pacific ◽

East Asian Summer Monsoon ◽

Arctic Oscillation ◽

Asian Summer Monsoon ◽

East Asian ◽

Atlantic Multidecadal Oscillation ◽

The Pacific ◽

Anomaly Pattern ◽

Asian Summer

AbstractPrevious studies indicated that spring Arctic Oscillation (AO) can influence the following East Asian summer monsoon (EASM). This study reveals that the Atlantic multidecadal oscillation (AMO) has a pronounced modulation of the spring AO–EASM connection. Spring AO has a close relation with the EASM during the negative AMO (−AMO) phase. However, during the positive AMO (+AMO) phase, the spring AO–EASM connection is weak. During the −AMO phase, a marked dipole atmospheric anomaly pattern (with an anticyclonic anomaly over the midlatitudes and a cyclonic anomaly over the subtropics) and a pronounced tripole sea surface temperature (SST) anomaly pattern is formed in the North Pacific during positive spring AO years. The cyclonic anomaly, SST, and precipitation anomalies over the subtropical western North Pacific (WNP) maintain and propagate southwestward in the following summer via a positive air–sea feedback, which further impacts the EASM variation. During the +AMO phase, the Pacific center of the spring AO (i.e., the anticyclonic anomaly over the midlatitudes) is weak. As such, the cyclonic anomaly cannot be induced over the subtropical WNP by the spring AO via wave–mean flow interaction. Hence, the spring AO–EASM connection disappears during the +AMO phase. The AMO impacts the Pacific center of the spring AO via modulating the Aleutian low intensity and North Pacific storm track intensity. The observed AMO modulation of the spring AO–EASM connection and Pacific center of the spring AO can be captured by the long historical simulation in a coupled global climate model.

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Tropical cyclone and extreme rainfall trends in East Asian summer monsoon since mid-20th century

Geophysical Research Letters ◽

10.1029/2012gl052945 ◽

2012 ◽

Vol 39 (18) ◽

Cited By ~ 46

Author(s):

Chih-Pei Chang ◽

Yonghui Lei ◽

Chung-Hisung Sui ◽

Xiaohong Lin ◽

Fumin Ren

Keyword(s):

Tropical Cyclone ◽

20Th Century ◽

Summer Monsoon ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

Extreme Rainfall ◽

Rainfall Trends ◽

Asian Summer

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Weakening Relationship between East Asian Summer Monsoon and Asian-Pacific Oscillation after 1990s

Advances in Meteorology ◽

10.1155/2019/6012301 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9

Author(s):

Wei Hua ◽

Zouxin Lin ◽

Xin Wang ◽

Guangzhou Fan

Keyword(s):

Summer Monsoon ◽

North Pacific ◽

East Asian Summer Monsoon ◽

Large Scale ◽

Asian Summer Monsoon ◽

East Asian ◽

Thermal Contrast ◽

The Pacific ◽

Asian Summer ◽

Asian Pacific

The East Asian summer monsoon (EASM), which is an important influencing summer climate of East Asia, is associated with large-scale change of the land-sea thermal contrast. The Asian-Pacific Oscillation (APO) can modulate the EASM because it not only represents the upper-tropospheric zonal land-sea thermal contrast over Asia and the Pacific region, but it also affects the sea surface temperature (SST) over the North Pacific, which can tune the land-sea thermal contrast for the EASM. This study revealed weakening of the APO-EASM relationship since the 1990s. It was found that the relationship between the APO and the EASM during 1948–1990 (1991–2016) was statistically significant (insignificant). Further study indicated that the APO was concurrent with significant positive SST in the central North Pacific and subtropical central-western Pacific during 1948–1990, which contributed to the shift of the Pacific Decadal Oscillation (PDO) from its cold to warm phase and led to a weakened EASM. The APO-related SST and atmospheric circulation anomalies were found statistically to be insignificant during 1991–2016, which indicates a weakening of influence of the APO on shift of the PDO, and even a weaker link to the EASM.

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