scholarly journals Influence of the Pacific Decadal Oscillation on the Relationship between El Niño and the Northeast Asian Summer Monsoon

2010 ◽  
Vol 23 (17) ◽  
pp. 4525-4537 ◽  
Author(s):  
Jinhee Yoon ◽  
Sang-Wook Yeh
Keyword(s):  
Pacific Decadal Oscillation ◽  
El Niño ◽  
El Nino ◽  
Asian Summer Monsoon ◽  
Northeast Asia ◽  
Summer Rainfall ◽  
The Pacific ◽  
Asian Summer ◽  
Northeast Asian ◽  
The Relationship

Abstract The influence of the Pacific decadal oscillation (PDO) on the relationship between El Niño and the northeast Asian summer monsoon (NEASM) is examined using observational datasets for the period of 1979–2007. When El Niño occurs during the boreal winter (December–February), the amount of rainfall over northeast Asia is usually above normal during the following summer (June–August). This relationship between El Niño and the NEASM is intensified when El Niño and the PDO are in phase during the previous winter. However, when El Niño and the PDO are out of phase, the relationship is weakened. The authors argue that the PDO can constructively or destructively interfere with the summer rainfall response over northeast Asia to El Niño. They follow the hypothesis that the summer rainfall over northeast Asia could be separated into two components, that is, the tropics-related component and the extratropics-related component. Then they argue that the PDO could modulate the relationship between El Niño and the NEASM through changes in the extratropics-related rainfall, which is associated with the atmospheric circulation, such as the Eurasian pattern. The conditional composites show that when El Niño and the PDO are in phase, the Eurasian-like pattern acts to enhance the extratropics-related rainfall over northeast Asia, resulting in the strengthening of the NEASM. In contrast, the Eurasian-like pattern acts to reduce the extratropics-related rainfall when El Niño and the PDO are out of phase, resulting in the weakening of the NEASM.

scholarly journals Remote Connection of the Northeast Asian Summer Rainfall Variation Revealed by a Newly Defined Monsoon Index

2005 ◽  
Vol 18 (21) ◽  
pp. 4381-4393 ◽  
Author(s):  
Eun-Jeong Lee ◽  
Jong-Ghap Jhun ◽  
Chung-Kyu Park
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Asian Summer Monsoon ◽  
Northeast Asia ◽  
Summer Precipitation ◽  
Summer Rainfall ◽  
Rainfall Variation ◽  
Monsoon Index ◽  
Asian Summer ◽  
Northeast Asian

Abstract A new northeast Asian summer monsoon index is introduced to investigate the characteristics of the northeast Asian summer rainfall variation, including Korea, Japan, and northeast China, and its possible connection to the tropical and midlatitude circulations. The summer precipitation over northeast Asia is separated into two components associated with tropical forcing and midlatitude dynamics using this monsoon index. The connection between the northeast Asian summer rainfall and ENSO is clearly identified by separating the Tropics-related component from the northeast Asian summer rainfall. That is, the Tropics-related precipitation over northeast Asia tends to be enhanced after the mature phase of El Niño. On the other hand, it is revealed that the extratropics-related component of summer precipitation is connected to the Eurasian wave pattern with no significant lag correlation. The intensity of the western North Pacific anticyclone modulated by ENSO is a key factor in the variation of the northeast Asian summer precipitation. It is found that the warm SST over the tropical eastern Pacific plays an important role in establishing the western North Pacific anticyclone during the preceding winter of strong northeast Asian summer monsoon years, whereas convective activities over the Bay of Bengal are contributed to the modulation of the anticyclonic circulation in the summer. The warming over the Indian Ocean in the summer of strong monsoon years induces the development of the anticyclone over the western North Pacific and the suppressed convection over the western Pacific tends to enhance the northeast Asian summer rainfall through the Pacific–Japan or East Asia–Pacific teleconnections.

scholarly journals Two Types of Strong Northeast Asian Summer Monsoon

2009 ◽  
Vol 22 (16) ◽  
pp. 4406-4417 ◽  
Author(s):  
Jung-Eun Kim ◽  
Sang-Wook Yeh ◽  
Song-You Hong
Keyword(s):  
Indian Ocean ◽  
Summer Monsoon ◽  
El Niño ◽  
El Nino ◽  
Asian Summer Monsoon ◽  
Striking Difference ◽  
Convective System ◽  
Asian Summer ◽  
Northeast Asian ◽  
Preceding Winter

Abstract The characteristics of a strong northeast Asian summer monsoon (NEASM) with and without (A and B type, respectively) a basinwide warming in the Indian Ocean during the preceding winter are examined for the period of 1979–2006. In the case of the A type, strong El Niño–like sea surface temperature (SST) decays very rapidly from the preceding winter (December–February) to the following summer (June–August), which may be due to a feedback process of the warm Indian Ocean. In addition, the A-type strong NEASM is more associated with a weak western North Pacific summer monsoon than the B-type strong NEASM. On the other hand, for the B type an El Niño–like SST during the preceding winter is a persistent influence into the following summer. A striking difference can be found in the atmospheric teleconnection pattern from the tropics to the midlatitudes over the Indo-Pacific region, that is, the Pacific–Japan-like pattern versus a pronounced Rossby wave train pattern. This may result from the difference in location of the maximum center of rainfall anomalies over the tropical northwestern Pacific between the two types of strong NEASM. The authors argue that Indian Ocean basin warming plays a role in modifying the convective system over the subtropical western Pacific, resulting in changes in atmospheric teleconnections between the two types of strong NEASM. The weak NEASM, in which the anomalous rainfall pattern resembles that of the A-type strong NEASM except for the sign, is also discussed.

scholarly journals Revisiting the relationship between the South Asian summer monsoon drought and El Niño warming pattern

2017 ◽  
Vol 18 (4) ◽  
pp. 175-182 ◽  
Author(s):  
Fangxing Fan ◽  
Xiao Dong ◽  
Xianghui Fang ◽  
Feng Xue ◽  
Fei Zheng ◽  
...  
Keyword(s):  
South Asian ◽  
Summer Monsoon ◽  
El Niño ◽  
El Nino ◽  
Asian Summer Monsoon ◽  
South Asian Summer Monsoon ◽  
The South ◽  
Warming Pattern ◽  
Asian Summer ◽  
The Relationship

scholarly journals Structure, dynamics, and trace gases variability within the Asian summer monsoon anticyclone in extreme El Niño of 2015–16

2020 ◽  
Author(s):  
Saginela Ravindra Babu ◽  
Madineni Venkat Ratnam ◽  
Ghouse Basha ◽  
Shantanu Kumar Pani ◽  
Neng-Huei Lin
Keyword(s):  
Summer Monsoon ◽  
El Niño ◽  
El Nino ◽  
Asian Summer Monsoon ◽  
Trace Gases ◽  
Northeastern Asia ◽  
Structure Dynamics ◽  
Asian Summer ◽  
Extreme El Niño

Abstract. In this work, the detailed changes in the structure, dynamics and trace gases within the Asian summer monsoon anticyclone (ASMA) during extreme El Niño of 2015–16 is delineated by using Aura Microwave Limb Sounder (MLS) measurements, COSMIC Radio Occultation (RO) temperature, and NCEP reanalysis products. We have considered the individual months of July and August 2015 for the present study. The results show that the ASMA structure was quite different in 2015 as compared to the long-term (2005–2014) mean. In July, the spatial extension of the ASMA shows larger than the long-term mean in all the regions except over northeastern Asia, where, it exhibits a strong southward shift in its position. The ASMA splits into two and western Pacific mode is evident in August. Interestingly, the subtropical westerly jet (STJ) shifted southward from its normal position over northeastern Asia as resulted mid latitude air moved southward in 2015. Intense Rossby wave breaking events along with STJ are also found in July 2015. Due to these dynamical changes in the ASMA, pronounced changes in the ASMA tracers are noticed in 2015 compared to the long-term mean. A 30 % (20 %) decrease in carbon monoxide (water vapor) at 100 hPa is observed in July over most of the ASMA region, whereas in August the drop is strongly concentrated in the edges of the ASMA. Prominent increase of O3 (> 40 %) at 100 hPa is clearly evident within the ASMA in July, whereas in August the increase is strongly located (even at 121 hPa) over the western edges of the ASMA. Further, the temperature around the tropopause shows significant positive anomalies (~ 5 K) within the ASMA in 2015. Overall, warming of the tropopause region due to the increased O3 weakens the anticyclone and further supported the weaker ASMA in 2015 reported by previous studies.

scholarly journals A 241-Year Cryptomeria fortune Tree-Ring Chronology in Humid Subtropical China and Its Linkages with the Pacific Decadal Oscillation

Atmosphere ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 247
Author(s):  
Zhipeng Dong ◽  
Dai Chen ◽  
Jianhua Du ◽  
Guang Yang ◽  
Maowei Bai ◽  
...  
Keyword(s):  
Tree Ring ◽  
Tree Rings ◽  
Pacific Decadal Oscillation ◽  
Asian Summer Monsoon ◽  
Growing Season ◽  
Subtropical China ◽  
Tree Ring Chronology ◽  
The Pacific ◽  
The World ◽  
Asian Summer

Humid subtropical China is an “oasis” relative to other dry subtropics of the world due to the prevailing of the East Asian summer monsoon (EASM). Although many long climate sensitive tree-rings have been published to understand the historical climate change over various regions in China, long tree-ring chronologies in humid subtropical China are rare due to the difficulty to find old growth trees. This study established a tree-ring chronology spanning from 1776 to 2016 from Cryptomeria fortunei Hooibrenk ex Otto et Dietr in Liancheng area of humid subtropical China, which is also currently the longest chronology in Fujian province. Similar to the climate-growth relationships in neighboring regions, our tree-ring chronology is limited by cold temperature in winter and spring and drought in summer. In addition, a drought stress before the growing season also played a role in limiting the growth of our tree rings. Our climate sensitive tree rings showed different correlations with the Pacific Decadal Oscillation (PDO) in different periods, possibly via modulation of the EASM.

scholarly journals Variation in the Asian monsoon intensity and dry–wet conditions since the Little Ice Age in central China revealed by an aragonite stalagmite

2014 ◽  
Vol 10 (5) ◽  
pp. 1803-1816 ◽  
Author(s):  
J.-J. Yin ◽  
D.-X. Yuan ◽  
H.-C. Li ◽  
H. Cheng ◽  
T.-Y. Li ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
El Niño ◽  
El Nino ◽  
Asian Summer Monsoon ◽  
Eastern China ◽  
Central China ◽  
Solar Irradiation ◽  
Mountain Area ◽  
Monsoon Intensity ◽  
Asian Summer

Abstract. This paper focuses on the climate variability in central China since AD 1300, involving: (1) a well-dated, 1.5-year resolution stalagmite δ18O record from Lianhua Cave, central China (2) links of the δ18O record with regional dry–wet conditions, monsoon intensity, and temperature over eastern China (3) correlations among drought events in the Lianhua record, solar irradiation, and ENSO (El Niño–Southern Oscillation) variation. We present a highly precise, 230Th / U-dated, 1.5-year resolution δ18O record of an aragonite stalagmite (LHD1) collected from Lianhua Cave in the Wuling Mountain area of central China. The comparison of the δ18O record with the local instrumental record and historical documents indicates that (1) the stalagmite δ18O record reveals variations in the summer monsoon intensity and dry–wet conditions in the Wuling Mountain area. (2) A stronger East Asian summer monsoon (EASM) enhances the tropical monsoon trough controlled by ITCZ (Intertropical Convergence Zone), which produces higher spring quarter rainfall and isotopically light monsoonal moisture in the central China. (3) The summer quarter/spring quarter rainfall ratio in central China can be a potential indicator of the EASM strength: a lower ratio corresponds to stronger EASM and higher spring rainfall. The ratio changed from <1 to >1 after 1950, reflecting that the summer quarter rainfall of the study area became dominant under stronger influence of the Northwestern Pacific High. Eastern China temperatures varied with the solar activity, showing higher temperatures under stronger solar irradiation, which produced stronger summer monsoons. During Maunder, Dalton and 1900 sunspot minima, more severe drought events occurred, indicating a weakening of the summer monsoon when solar activity decreased on decadal timescales. On an interannual timescale, dry conditions in the study area prevailed under El Niño conditions, which is also supported by the spectrum analysis. Hence, our record illustrates the linkage of Asian summer monsoon precipitation to solar irradiation and ENSO: wetter conditions in the study area under stronger summer monsoon during warm periods, and vice versa. During cold periods, the Walker Circulation will shift toward the central Pacific under El Niño conditions, resulting in a further weakening of Asian summer monsoons.

scholarly journals Estudo da Influência da Oscilação Decadal do Pacífico no Nordeste do Brasil (Study of the Influence of Pacific Decadal Oscillation in Northeast of Brazil)

2011 ◽  
Vol 4 (4) ◽  
pp. 665 ◽  
Author(s):  
Djane Fonseca Da Silva ◽  
Josicleda Domiciano Galvíncio
Keyword(s):  
Pacific Decadal Oscillation ◽  
El Niño ◽  
Temporal Variability ◽  
El Nino ◽  
Rainfall Variability ◽  
Northeastern Brazil ◽  
Simultaneous Occurrence ◽  
Precipitation Data ◽  
The Pacific ◽  
Dominant Peak

 Pretende-se nesse trabalho investigar como a ODP exerce influência sobre a variabilidade pluviométrica da sub-bacia hidrográfica do Baixo São Francisco, situada na região Nordeste do Brasil. Foram utilizados dados de precipitação de 17 localidades para o período de dados de 1911-1993 obtidos através da Agência Nacional das Águas (ANA) pelo site www.ana.gov.br/hidroweb. O pico dominante para a variabilidade temporal do BSF é da escala de 20,2-22 anos e pico secundário, significativo, ocorre na escala de 11 anos. Durante a ocorrência simultânea de ENOS e ODP negativa, as anomalias positivas aumentaram consideravelmente. O que parece é que a ODP negativa incrementa os valores das anomalias de chuva, tanto durante El Niño, quanto La Niña.Palavras-chave: Oscilação Decadal do Pacífico, Baixo São Francisco, Análise de Ondeletas  Study of the Influence of the Pacific Decadal Oscillation in the Northeast of Brazil  ABSTRACT It is intended this work to investigate how the PDO influence on rainfall variability in the sub-basin of the Lower São Francisco, located in northeastern Brazil. We used precipitation data from 17 sites for the period 1911-1993 data obtained through the National Water Agency (ANA) by the site www.ana.gov.br / hidroweb. The dominant peak for the temporal variability of BSF is the range of 20.2 to 22 years and secondary peak, significantly, occurs in the range of 11 years. During the simultaneous occurrence of ENSO and PDO negative, the positive anomalies have increased considerably. It turns out that the PDO increases the negative values of abnormal rainfall, both during El Niño, and La Niña. Keywords: Pacific Decadal Oscillation, Low São Francisco, Wavelet Analysis

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