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 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 Coupling Modes of Climatological Intraseasonal Oscillation in the East Asian Summer Monsoon

2016 ◽  
Vol 29 (17) ◽  
pp. 6363-6382 ◽  
Author(s):  
Zehao Song ◽  
Congwen Zhu ◽  
Jingzhi Su ◽  
Boqi Liu
Keyword(s):  
East Asia ◽  
North Pacific ◽  
East Asian Summer Monsoon ◽  
Western North Pacific ◽  
Diabatic Heating ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Intraseasonal Oscillation ◽  
Rainfall Anomaly ◽  
Asian Summer

Abstract The present study used harmonic and multivariate empirical orthogonal function (MV-EOF) analyses to identify the existence of climatological intraseasonal oscillation (CISO) in the diabatic heating, precipitation, and circulation of the East Asian summer monsoon (EASM). The strongest CISO signals are found in the north of the western North Pacific, possibly because of the horizontal gradient of diabatic heating induced by the seasonal land–sea thermal contrast. Further, the phase relationship between the diabatic heating components maintains the EASM CISO. The first two coupling modes of EASM CISO in the circulation are robust during May through August, with a period of 40–80 days, and exhibit phase locking to the stepwise establishment of the EASM, which reveals the coaction of the Mongolian cyclone (MC) around Lake Baikal at 850 hPa, the western North Pacific subtropical high (WNPSH) at 500 hPa, and the South Asian high (SAH) over the Tibetan Plateau (TP) at 200 hPa. The first mode shows that the jointly enhanced MC, WNPSH, and SAH correspond to a tripole rainfall anomaly with strong mei-yu and baiu fronts over East Asia. The second mode, however, indicates the eastward and northwestward propagation of MC and WNPSH, respectively, with suppressed SAH, as well as a dipole rainfall anomaly over East Asia. Both the observations and numerical simulation verify the importance of daily diabatic heating and SST in maintaining the CISO modes over the WNP, where the condensation heating related to atmospheric forcing determines the local intraseasonal air–sea interaction.

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.

Spring Arctic Oscillation-East Asian summer monsoon connection through circulation changes over the western North Pacific

2011 ◽  
Vol 37 (11-12) ◽  
pp. 2199-2216 ◽  
Author(s):  
Dao-Yi Gong ◽  
Jing Yang ◽  
Seong-Joong Kim ◽  
Yongqi Gao ◽  
Dong Guo ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
North Pacific ◽  
East Asian Summer Monsoon ◽  
Western North Pacific ◽  
Arctic Oscillation ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Asian Summer ◽  
Circulation Changes

Moisture Source-to-Receptor Network for East Asian Summer Monsoon and the Associated Atmospheric Bridges

2020 ◽  
Author(s):  
Tat Fan Cheng ◽  
Mengqian Lu
Keyword(s):  
Pacific Ocean ◽  
River Basin ◽  
North Pacific ◽  
East Asian Summer Monsoon ◽  
Western North Pacific ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Intraseasonal Variation ◽  
The Pacific ◽  
Asian Summer

<p>There has been growing interest in studying precipitation recycling and identifying relationships between moisture sources and receptors. The network built upon the relationships is crucial for the knowledge of the atmospheric water cycle, weather prediction, and adaptation to hydroclimatic disasters. This study aims to provide an interesting perspective of a Source-to-Receptor (SR) network to study the dynamics of the East Asian Summer Monsoon (EASM). By prescribing 24 sources and 6 EASM subregions, the SR network during the wet season is quantified using the two-dimensional physically-based Dynamical Recycling Model (DRM). Results reveal that in addition to oceanic sources, land sources including the often-overlooked plateau regions play an important role in supplying moisture to most EASM subregions. A seesaw relationship of the Indian Ocean/South Asia sector from April to June and the Pacific Ocean/East Asia sector from July to September is evidenced in the intraseasonal variation of the SR network for EASM subregions including South China coast and Taiwan, Yangtze River basin, South Japan and Korean Peninsula. Conversely, weaker intraseasonal variation is seen in the SR network for the Yellow River basin and North China. During heavy rainfall days, the zonal oscillation of western North Pacific Subtropical High (WNPSH) is deemed crucial to modulate the SR network through enhanced contributions from Bay of Bengal, Indochina, Indian subcontinent and Southwest China (the Philippine Sea and western North Pacific) during the positive (negative) phase. Coupled circulations such as two distinct pressure dipoles and coherent upper-level wave trains from mid-latitudes are responsible for bridging the moisture routes. Lastly, preceding winter/springtime El Niño is likely associated with the enhanced (weakened) moisture supply from the southwesterly (Pacific Ocean) sources. Longer-term variabilities such as the Pacific Decadal Oscillation is also considered influential to the SR network. We believe that the attributable atmospheric bridges and the SR network itself can offer insights to the current understanding of EASM and model simulations of the monsoon systems and the water cycles.</p>

scholarly journals Impact of the Southeast Asian summer monsoon strength on the outflow of aerosols from South Asia

2010 ◽  
Vol 28 (1) ◽  
pp. 277-287 ◽  
Author(s):  
L. Zhang ◽  
H. Liao ◽  
J. Li
Keyword(s):  
South Asia ◽  
Summer Monsoon ◽  
North Pacific ◽  
Western North Pacific ◽  
Southern China ◽  
Asian Summer Monsoon ◽  
Southeast Asian ◽  
The South ◽  
Asian Summer ◽  
Monsoon Strength

Abstract. We chose a relatively weak Southeast Asian summer monsoon (SEASM) year (1998) and a relatively strong year (2002) to examine the impact of the monsoon strength on the transport of organic carbon (OC) aerosol emitted from the South Asia (75°–105° E, 10°–25° N) by using the global 3-D chemical transport model GEOS-Chem driven by the assimilated meteorological fields. Simulated surface layer concentrations and column burdens of OC indicate that OC levels are much higher in the weak SEASM year 1998 than in the strong SEASM year 2002. The sensitivity experiments with global OC emissions turned off except those over the South Asia show that OC aerosol emitted from South Asia contributes to 50–70% of OC mass over southern China and 20–50% of OC over the western North Pacific between 850 hPa and 400 hPa in 1998. The outflow of OC from the South Asia is larger in 1998 than in 2002. Three factors contribute to the larger buildup of summer time OC in the weak SEASM year of 1998. The first is the weakened summer monsoon rainfall over the Southeast Asia that leads to less wet deposition and higher OC concentrations. The second is the enhancement of deep convection in the western Indian continent and the weakened upward lifting over the western North Pacific. The last and the most important factor is the abnormal circulation in the lower and middle troposphere that contributes to the long-range transport of OC from South Asia to Southern China and the western North Pacific.

scholarly journals Break of the Western North Pacific Summer Monsoon in Early August

2015 ◽  
Vol 28 (8) ◽  
pp. 3420-3434 ◽  
Author(s):  
Ke Xu ◽  
Riyu Lu
Keyword(s):  
Summer Monsoon ◽  
North Pacific ◽  
Western North Pacific ◽  
Asian Summer Monsoon ◽  
The Other ◽  
South Asian Summer Monsoon ◽  
Close Link ◽  
Rainfall Reduction ◽  
Asian Summer ◽  
Asian Monsoons

Abstract Although the monsoon break is a well-known phenomenon for the South Asian summer monsoon, it has not been well documented for the other monsoons, for instance, the western North Pacific (WNP) summer monsoon. This study identified a distinct monsoon break over the WNP by analyzing the subseasonal evolution of atmospheric convection and precipitation. This WNP monsoon break occurs climatologically in early August (3–8 August), but shows a strong variation, in either intensity or timing, from year to year. For about 30% of years, the rainfall amount reduces by more than 10 mm day−1 over the northeast WNP (10°–20°N, 140°–160°E) in early August, and is even less than that before the monsoon onset. However, for the other 30% of years, the subseasonal evolution of rainfall tends to be out of phase with the climatology, and rainfall reduction appears in mid-August. Furthermore, the 10–25-day oscillations, which originate at the equatorial western Pacific and propagate northwestward, are found to play a crucial role in forming the monsoon break. The 10–25-day oscillations exhibit a strong interannual variation, associated with the WNP monsoon trough during the period from late July to mid-August, and contribute greatly to the year-to-year variation in both the timing and intensity of the monsoon break. Considering the close link in subseasonal evolution between the WNP and East Asian monsoons, the present results indicate the necessity to investigate the possible role of the WNP monsoon break on the weather and climate over East Asia.

Deficiencies and possibilities for long-lead coupled climate prediction of the Western North Pacific-East Asian summer monsoon

2010 ◽  
Vol 36 (5-6) ◽  
pp. 1173-1188 ◽  
Author(s):  
Sun-Seon Lee ◽  
June-Yi Lee ◽  
Kyung-Ja Ha ◽  
Bin Wang ◽  
Jae Kyung E. Schemm
Keyword(s):  
Summer Monsoon ◽  
North Pacific ◽  
East Asian Summer Monsoon ◽  
Western North Pacific ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Climate Prediction ◽  
Asian Summer
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