Analysis of Record-High Temperature over Southeast Coastal China in Winter 2018/19: The Combined Effect of Mid- to High-Latitude Circulation Systems and SST Forcing over the North Atlantic and Tropical Western Pacific

2020 ◽  
Vol 33 (20) ◽  
pp. 8813-8831
Author(s):  
Yuntao Jian ◽  
Xiaoxia Lin ◽  
Wen Zhou ◽  
Maoqiu Jian ◽  
Marco Y. T. Leung ◽  
...  
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
East Asian ◽  
Western Pacific ◽  
Asian Winter Monsoon ◽  
The North ◽  
Tropical Western Pacific ◽  
Circulation Patterns ◽  
Coastal China ◽  
Sst Anomalies

AbstractIn winter 2018/19, southeastern coastal China experienced extreme warm temperatures that were due to a weak East Asian winter monsoon. On the basis of observations from 10 meteorological stations and reanalysis data, the large-scale circulation patterns associated with this extreme warm winter and the possible driving mechanism of its related sea surface temperature (SST) anomalies are investigated in this study. During this winter, many places in this region reached their highest winter mean temperature record and had more extreme warm days and fewer extreme cold days relative to climatology. According to the circulation patterns during winter 2018/19, several large-scale circulation conditions associated mainly with the weak East Asian winter monsoon are identified: the eastward shift of the Siberian high and a shallower East Asian trough, which is related to the low blocking frequency over the Aleutian region, are both unfavorable for cold-air intrusion southward. Meanwhile, strong low-level southerly wind anomalies over southeastern China are related mainly to the 2018/19 El Niño event. Furthermore, the possible role of SST anomalies over the North Atlantic and tropical western Pacific Oceans is examined by using an atmospheric general circulation model, suggesting that both the “tripole pattern” of North Atlantic SST and tropical western Pacific SST anomalies in winter 2018/19 played a role in influencing the East Asian trough. The combined effect of all of these factors seems to be responsible for this extreme warm winter over southeastern coastal China.

scholarly journals Regime-Dependent Nonstationary Relationship between the East Asian Winter Monsoon and North Pacific Oscillation

2014 ◽  
Vol 27 (21) ◽  
pp. 8185-8204 ◽  
Author(s):  
Gyundo Pak ◽  
Young-Hyang Park ◽  
Frederic Vivier ◽  
Young-Oh Kwon ◽  
Kyung-Il Chang
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
East Asian Winter Monsoon ◽  
East Asian ◽  
Winter Monsoon ◽  
North Pacific Oscillation ◽  
Asian Winter Monsoon ◽  
The North ◽  
Circulation Patterns ◽  
The North Pacific

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.

scholarly journals Distinguishing Interannual Variations of the Northern and Southern Modes of the East Asian Winter Monsoon

2014 ◽  
Vol 27 (2) ◽  
pp. 835-851 ◽  
Author(s):  
Zhang Chen ◽  
Renguang Wu ◽  
Wen Chen
Keyword(s):  
Surface Temperature ◽  
North Atlantic ◽  
High Latitude ◽  
East Asian Winter Monsoon ◽  
East Asian ◽  
Winter Monsoon ◽  
Interannual Variations ◽  
Asian Winter Monsoon ◽  
The North ◽  
The North Atlantic

Abstract The East Asian winter monsoon (EAWM)-related climate anomalies have shown large year-to-year variations in both the intensity and the meridional extent. The present study distinguishes the interannual variations of the low-latitude and mid- to high-latitude components of the EAWM to gain a better understanding of the characteristics and factors for the EAWM variability. Through composite analysis based on two indices representing the northern and southern components (modes) of the EAWM variability, the present study clearly reveals features unique to the northern and southern mode. The northern mode is associated with changes in the mid- to high-latitude circulation systems, including the Siberian high, the Aleutian low, the East Asian trough, and the East Asian westerly jet stream, whereas the southern mode is closely related to circulation changes over the global tropics, the North Atlantic, and North America. A strong northern mode is accompanied by positive, negative, and positive surface temperature anomalies in the Indochina Peninsula, midlatitude Asia, and northeast Russia, respectively. A strong southern mode features lower temperature over tropics and higher temperature over mid- to high-latitude Asia. While the southern mode is closely related to El Niño–Southern Oscillation (ENSO), the northern mode does not show an obvious relation to the tropical sea surface temperature (SST) change or to the North Atlantic Oscillation (NAO)/Arctic Oscillation (AO) on the interannual time scale. Distinct snow cover and sea ice changes appear as responses to wind and surface temperature changes associated with the two modes and their effects on the EAWM variability need to be investigated in the future.

North Atlantic Jet position induces latitudinal decouplings in forest productivity in Europe

2020 ◽  
Author(s):  
Isabel Dorado-Liñán ◽  
Valerie Trouet ◽  
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
European Beech ◽  
Forest Productivity ◽  
Atmospheric Circulation Patterns ◽  
Summer Climate ◽  
The North ◽  
Circulation Patterns ◽  
Latitudinal Position ◽  
The North Atlantic

<p>Dynamically-driven extreme weather events have large ecological, social and economic consequences including large tree-growth reductions and forest mortality. These events are likely to become globally more frequent and intense in the near future with increased anthropogenic forcing and associated changes in couple atmosphere-ocean circulation. The European continent is under the control of different atmospheric circulation patterns leading to geographical climatic gradients caused by their eventual position and strength, being the North Atlantic Oscillation (NAO) and the East Atlantic Pattern (EA) the main modes of North Atlantic climate variability (Barnston and Levezey 1987; Folland et al. 2009). Both, NAO and EA reflect jet stream changes as a consequence of variations in the eddy forcing, being the North Atlantic Jet (NAJ) the pattern connecting the large-scale atmospheric variability over the North Atlantic basin (Woollings, Hannachi, and Hoskins 2010). Thus, the identification and characterization of the links between forest productivity and the precursors of large-scale dynamics inducing extreme events may boost our capacity of assessing their predictability and enhancing forecasting skills.<br>Here, we scale forest response to climate to higher atmospheric levels by establishing the connection between extreme positive and negative anomalies in productivity of European forests to the latitudinal position of the NAJ. For that, we use a network of 344 European beech tree-ring chronologies extending from the Iberian Peninsula to the Carpathians and from Greece to northern UK.<br>Our results show a geographical gradient on tree growth across Europe explained either by the asymmetric forest response to homogeneous summer climate over Europe or to a distinct summer climate dipole leading to diverging climatic conditions in northeaster and southwestern Europe. In both cases, the continental-scale European-beech growth patterns are linked to the NAJ latitudinal position and its determinant influence on summer climate over Europe. The projected increase in the frequency of northward migrations of the NAJ for the next century may enhance the differences in forest productivity across Europe by inducing subcontinental-wide beech forest growth reduction.</p><p><br>Barnston, Anthony Gaston, and Robert E. Levezey. 1987. "Classification, seasonality and persistence of low-frequency atmospheric circulation patterns" Mon. Weather Rev. 115: 1083-1126.<br>Folland, Chris K, Jeff Knight, Hans W Linderholm, David Fereday, Sarah Ineson, and James W Hurrell. 2009. “The Summer North Atlantic Oscillation: Past, Present, and Future.” Journal of Climate 22 (5): 1082–1103. https://doi.org/10.1175/2008JCLI2459.1.<br>Woollings, Tim, Abdel Hannachi, and Brian Hoskins. 2010. “Variability of the North Atlantic Eddy-Driven Jet Stream.” Quarterly Journal of the Royal Meteorological Society 136 (649): 856–68. https://doi.org/10.1002/qj.625.</p><p> </p>

scholarly journals Impacts of Summer North Atlantic Sea Surface Temperature Anomalies on the East Asian Winter Monsoon Variability

2019 ◽  
Vol 32 (19) ◽  
pp. 6513-6532 ◽  
Author(s):  
Zhang Chen ◽  
Renguang Wu ◽  
Zhibiao Wang
Keyword(s):  
North Atlantic ◽  
Wave Train ◽  
Asian Winter Monsoon ◽  
The North ◽  
Atmospheric Wave ◽  
Anomaly Pattern ◽  
Dipole Pattern ◽  
Sst Anomaly ◽  
The North Atlantic ◽  
Sst Anomalies

Abstract The present study investigates the impacts of the North Atlantic sea surface temperature (SST) anomalies on the East Asian winter monsoon (EAWM) variability. It is found that the northern component of the EAWM variability is associated with a dipole pattern of preceding summer North Atlantic SST anomalies during 1979–2016. The processes linking preceding summer North Atlantic SST to EAWM include the North Atlantic air–sea interactions and atmospheric wave train triggered by the North Atlantic SST anomalies. Atmospheric wind anomalies in the preceding spring–summer result in the formation of a dipole SST anomaly pattern through surface heat flux changes. In turn, the induced SST anomalies provide a feedback on the atmosphere, modifying the location and intensity of anomalous winds over the North Atlantic. The associated surface heat flux anomalies switch the North Atlantic SST anomaly distribution from a dipole pattern in summer to a tripole pattern in the following winter. The North Atlantic tripole SST anomalies excite an atmospheric wave train extending from the North Atlantic through Eurasia to East Asia in winter, resulting in anomalous EAWM. However, the relationship of the northern component of EAWM to preceding summer North Atlantic SST anomalies is weak before the late 1970s. During 1956–76, due to weak air–sea interaction over the North Atlantic, no obvious tripole SST anomaly pattern is established in winter. The atmospheric wave train in winter is located at higher latitudes, leading to a weak connection between the northern component of EAWM and the preceding summer North Atlantic dipole SST anomaly pattern.

scholarly journals Relative Importance of the Austral Summer and Autumn SAM in Modulating Southern Hemisphere Extratropical Autumn SST*

2015 ◽  
Vol 28 (20) ◽  
pp. 8003-8020 ◽  
Author(s):  
Fei Zheng ◽  
Jianping Li ◽  
Juan Feng ◽  
Yanjie Li ◽  
Yang Li
Keyword(s):  
Southern Hemisphere ◽  
North Atlantic ◽  
Large Scale ◽  
Austral Summer ◽  
Relative Importance ◽  
Seasonal Influence ◽  
New Approach ◽  
The North ◽  
Sst Variability ◽  
Sst Anomalies

Abstract Sea surface temperature (SST) variability in the extratropical Southern Hemisphere is mainly determined by physical processes at the air–sea interface associated with the Southern Hemisphere annular mode (SAM). Both the austral summer [December–February (DJF)] and autumn [March–May (MAM)] SAM can imprint their signals on southern extratropical MAM SST. Here three approaches are employed to determine the relative importance of the DJF and MAM SAM in modulating southern extratropical MAM SST: a simple lead–lag correlation without SST decomposition, a decomposition method based on linear regression, and a new approach named the persistent signal decomposition (PSD). The results show that the DJF SAM plays a more important role than the MAM SAM in driving MAM large-scale southern extratropical SST anomalies, implying that MAM SST anomalies caused by the preceding DJF SAM would not be largely perturbed by the MAM SAM, and thus the DJF SAM can be regarded as an effective predictor for the following season’s climate. The PSD also provides an estimation of the contribution of atmospheric persistence and SST persistence toward cross-seasonal influence of the DJF SAM on MAM southern extratropical SST. The results show that this cross-seasonal influence is mainly caused by the SST persistence. The detection of the relative importance of the preceding and contemporaneous atmospheric signal in driving SSTA contributes to the understanding of air–sea interactions and helps to obtain better SST-based statistical predictions. The PSD has the potential to be employed in the North Atlantic and other extratropical oceans.

scholarly journals Multi-decadal trends in the tropical Pacific western boundary currents retrieved from historical hydrological observations

2021 ◽  
Author(s):  
Shijian Hu ◽  
Xi Lu ◽  
Shihan Li ◽  
Fan Wang ◽  
Cong Guan ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Ocean Circulation ◽  
Large Scale ◽  
Western Pacific ◽  
North Equatorial Current ◽  
Western Pacific Ocean ◽  
The North ◽  
Tropical Western Pacific ◽  
Decadal Trend ◽  
The Western Pacific

AbstractAs large-scale ocean circulation is a key regulator in the redistribution of oceanic energy, evaluating the multi-decadal trends in the western Pacific Ocean circulation under global warming is essential for not only understanding the basic physical processes but also predicting future climate change in the western Pacific. Employing the hydrological observations of World Ocean Atlas 2018 (WOA18) from 1955 to 2017, this study calculated the geostrophic currents, volume transport and multi-decadal trends for the North Equatorial Current (NEC), the North Equatorial Countercurrent (NECC), the Mindanao Current (MC), the Kuroshio Current (KC) in the origin and the New Guinea Coastal Undercurrent (NGCUC) within tropical western Pacific Ocean over multi-decades. Furthermore, this study examined the contributions of temperature and salinity variations. The results showed significant strengthening trends in NEC, MC and NGCUC over the past six decades, which is mainly contributed by temperature variations and consistent with the tendency in the dynamic height pattern. Zonal wind stress averaged over the western Pacific Ocean in the same latitude of each current represents the decadal variation and multi-decadal trends in corresponding ocean currents, indicating that the trade wind forcing plays an important role in the decadal trend in the tropical western Pacific circulation. Uncertainties in the observed hydrological data and trends in the currents over the tropical western Pacific are also discussed. Given that the WOA18 dataset covers most of the historical hydrological sampling data for the tropical western Pacific, this paper provides important observational information on the multi-decadal trend of the large-scale ocean circulation in the western Pacific.

scholarly journals Interdecadal Variations of the East Asian Winter Monsoon in CMIP5 Preindustrial Simulations

2020 ◽  
Vol 33 (2) ◽  
pp. 559-575 ◽  
Author(s):  
Jiapeng Miao ◽  
Tao Wang ◽  
Huijun Wang
Keyword(s):  
North Pacific ◽  
East Asian Winter Monsoon ◽  
East Asian ◽  
Winter Monsoon ◽  
Climate System ◽  
Asian Winter Monsoon ◽  
The North ◽  
The North Pacific ◽  
Sst Anomalies

AbstractIn this study, focusing on the interdecadal time scale, we investigate the internal variability of the East Asian winter monsoon (EAWM) using output from 19 coupled models’ long-term preindustrial control (piControl) simulations within phase 5 of the Coupled Model Intercomparison Program (CMIP5). In total, we identify 53 cases of significant interdecadal weakening of the EAWM from these 19 piControl simulations. In most weakening cases, both the Siberian high and the East Asian trough are significantly weakened. The East Asian jet stream in the upper troposphere shifts poleward. Southerly wind anomalies are evident over East Asia in the lower troposphere. At the same time, both the Arctic Oscillation (AO) and the North Pacific Oscillation are in their positive phases. Associated anomalous anticyclonic circulation can be found over the North Pacific. Additionally, the North Pacific shows negative Pacific decadal oscillation (PDO)-like sea surface temperature (SST) anomalies. In contrast, we also analyzed 49 cases of significant strengthening of the EAWM, and the atmospheric and oceanic anomalies show opposite signals with the weakening cases. This suggests that internal variabilities of the climate system can also cause interdecadal variations of the EAWM. In addition, the phase shifting of the AO is likely the main reason for the EAWM’s interdecadal variations in the unforced long-term simulations. Further numerical experiments using the Community Atmosphere Model, version 4 (CAM4), deny the causal relationship between the interdecadal variations of EAWM and PDO-like SST anomalies. This study also implies that the internal variabilities of the climate system could contribute to the observed interdecadal weakening of the EAWM around the mid-1980s.

scholarly journals Effect of the El Niño Decaying Pace on the East Asian Summer Monsoon Circulation Pattern during Post-El Niño Summers

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 140
Author(s):  
Wenping Jiang ◽  
Gen Li ◽  
Gongjie Wang
Keyword(s):  
El Niño ◽  
Asian Monsoon ◽  
East Asian Monsoon ◽  
El Nino ◽  
East Asian ◽  
Circulation Pattern ◽  
Northwest Pacific ◽  
Monsoon Circulation ◽  
Circulation Patterns ◽  
Sst Anomalies

El Niño events vary from case to case with different decaying paces. In this study, we demonstrate that the different El Niño decaying paces have distinct impacts on the East Asian monsoon circulation pattern during post-El Niño summers. For fast decaying (FD) El Niño summers, a large-scale anomalous anticyclone dominates over East Asia and the North Pacific from subtropical to mid-latitude; whereas, the East Asian monsoon circulation display a dipole pattern with anomalous northern cyclone and southern anticyclone for slow decaying (SD) El Niño summers. The difference in anomalous East Asian monsoon circulation patterns was closely associated with the sea surface temperature (SST) anomaly patterns in the tropics. In FD El Niño summers, the cold SST anomalies in the tropical central-eastern Pacific and warm SST anomalies in the Maritime Continent induce the anticyclone anomalies over the Northwest Pacific. In contrast, the warm Kelvin wave anchored over the tropical Indian Ocean during SD El Niño summers plays a crucial role in sustaining the anticyclone anomalies over the Northwest Pacific. In particular, the opposite atmospheric circulation anomaly patterns over Northeast Asia and the mid-latitude North Pacific are mainly modulated by the stationary Rossby wave trains triggered by the opposite SST anomalies in the tropical eastern Pacific during FD and SD El Niño summers. Finally, the effect of distinct summer monsoon circulation patterns associated with the El Niño decay pace on the summer climate over East Asia are also discussed.

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