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Using ERA5 reanalysis data, this study explores the interannual variability of the occurrence frequency of the stronger Kunming quasi‐stationary front during in winter over the period 1980–2021 and the main causes of the variability. The results indicate that the occurrence frequency is significantly modulated on interannual timescales by southwesterly anomalies over the warmer region west of 103° E and northeasterly anomalies over the colder region east of 106° E. When the stronger southwesterly anomalies over the warmer region are comparable with stronger northeasterly anomalies over the colder region, the inhomogeneities of horizontal convergence and diabatic heating are strengthened near the frontal zone. This anomalous circulation causes a higher‐than‐normal occurrence frequency of the stronger Kunming quasi‐stationary front in winter. The East Asian winter monsoon (EAWM) and circumglobal teleconnection (CGT) are the two most important controls on the interannual variability of the occurrence frequency of the stronger Kunming quasi‐stationary front. Both the CGT and EAWM modulate the inhomogeneities of horizontal convergence and diabatic heating on the west flank of the front, and the EAWM further regulates diabatic heating over the east flank of the front. [ABSTRACT FROM AUTHOR]

The atmospheric activity on Kalimantan Island (KI) is important for regulating regional weather and climate. This study investigates the effect of autumn soil moisture over KI on following winter precipitation over southern China (SC) during 1968–2014. The results show that the autumn soil moisture over the KI has a significant negative correlation with subsequent winter precipitation over SC. The correlation remains statistically significant when using partial correlation to filter out the concurrent influences of El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) signals. The soil moisture anomalies over KI, which initiate in the autumn and persist into the winter, lead to changes in local thermal conditions and atmospheric temperature. Negative soil moisture anomalies over KI will result in positive heating anomalies of the atmosphere above the land surface. This atmospheric heating causes ascending motion, which creates a semi‐closed vertical circulation from KI to the tropical northwest Pacific. This vertical circulation would strengthen the northwest Pacific anticyclone and weaken the East Asian winter monsoon (EAWM). Consequently, southwesterly water vapour flux prevails in the SC as well as the South China Sea (SCS), facilitating the transportation of more water vapour into the SC. Simultaneously, water vapour convergence in the SC. Collectively, these contribute to an addition of precipitation over SC. [ABSTRACT FROM AUTHOR]

It is widely recognized that the East Asian winter monsoon (EAWM) has independent northern and southern modes. This study evaluated the capability of 18 Coupled Model Intercomparison Project Phase 6 models in simulating the relationship between the EAWM and El Niño–Southern Oscillation (ENSO), together with possible causes of inter-model bias. Simulations generated by 12 good-performing models demonstrate that the close relationship between the EAWM southern mode and ENSO depends on the position of the ENSO-related tripolar pattern of sea surface temperature (SST) anomalies in the tropical Indian and Pacific oceans. The positive feedback of anomalous Philippine anticyclones/cyclones with the ENSO-related east–west SST gradient over the Maritime Continent favors anomalous southerly/northerly winds in southeastern China. In contrast, the strength of the Philippine anticyclone, which is influenced by the intensity of ENSO variability, partly affects the ability of models to simulate the relationship between the EAWM northern mode and ENSO. Strong Philippine anticyclonic/cyclonic anomalies extend anomalous southerly/northerly winds from low to mid-high latitudes in East Asia. Another crucial factor in the relationship between the EAWM northern mode and ENSO is the ENSO-related Indian Ocean and South China Sea SST anomalies, which induce a poleward wave train through anomalous latent heating and subsequently generate Kuroshio anticyclonic/cyclonic anomalies. [ABSTRACT FROM AUTHOR]

This study analyzed systematic biases in surface air temperature (SAT) within Far East Asia during the boreal winter using the SNURCM and WRF regional climate models (RCMs) from the Coordinated Regional Downscaling Experiment (CORDEX)-East Asia phase II. The SAT biases were examined in relation to the East Asian winter monsoon (EAWM). The models consistently simulated lower winter temperatures over East Asia, particularly in the Manchuria (MC) region, compared to the observation, showing a positive correlation with the EAWM. This study assessed the models' ability to capture EAWM variability and revealed relationships between SAT biases and discrepancies in low-level and near-surface EAWM conditions. The findings emphasized the value of analyzing extreme monsoon years, with the RCMs exhibiting larger cold SAT biases during strong EAWM years. Systematic biases in sea-level pressure contrast and lower-level winds over the MC region were evident during years with a robust monsoon. The overestimation of low-level winds during strong EAWM years contributed to increased cold advection, affecting the MC region. These systematic errors are influenced by the internal factors of the model, such as the physics parameterization schemes, rather than large-scale circulation forced by the reanalysis data (perfect boundary condition). These results provide insights for model improvements, understanding EAWM dynamics, and call for investigation of processes in the planetary boundary layer and coupled air-sea interaction. [ABSTRACT FROM AUTHOR]

Dust storms occur frequently in northern China and greatly influence the regional ecology/environment, human health, and security, as well as the global climate, and this is especially true regarding the occurrence of mega dust storms. Many archives reveal dramatic strengthening of China’s dust storms (CDS) between 1850 and 1900, but the reason remains poorly understood. By comparing the episode of dramatic strengthening of CDS to the well-established history of anthropogenic activity and climatic change, this study revealed that the episode occurred precisely in the 1850s and was caused mainly by climate change related to atmospheric circulation anomalies, especially a substantially strengthened East Asian winter monsoon (EAWM); anthropogenic factors acted only to exacerbate the effects of the underlying climatic factors. Under a scenario of continuous warming, the occurrence probability of mega dust storms in China is anticipated to diminish due to the future weakening of the EAWM and an increase in precipitation in the potential sources of Asian mineral dust. [ABSTRACT FROM AUTHOR]

Recent change in the daily temperature variation (DTV) for March in East Asia is investigated. For this purpose, the effects of atmospheric circulation and global warming on the DTV in the region are analyzed using Japanese 55-year reanalysis data. Among the high-frequency variations in surface air temperature (SAT) during spring, the DTV in March showed a significant, increasing trend in East Asia during the four decades from 1979 to 2020. Composite analysis shows that the above-normal March DTV is associated with the anomalous anticyclonic circulation in the North Pacific and the anomalous cyclonic circulation over Russia. These atmospheric circulation anomalies lead to a greater meridional SAT gradient and tend to cause more mid-latitude pressure systems to pass over East Asia. Ultimately, the SAT in March becomes more variable due to enhanced thermal advection over East Asia. In addition, this pattern of circulation anomalies associated with a large March DTV includes features of a weak East Asian winter monsoon (EAWM) system. Meanwhile, regression analysis results using the EAWM and long-term global warming trend indices suggest that both the large-scale atmospheric circulation and global warming contribute significantly to the March DTV change in East Asia. In particular, heterogeneous warming rates and localized soil drying in East Asia during the study period likely explain the role of global warming on East Asian DTV in March. [ABSTRACT FROM AUTHOR]

The Kuroshio intrusion (KI) is a northwestward‐flowing branch of the Kuroshio Current, which enters the South China Sea (SCS) and regulates its temperature, salinity, and water mass exchanges. However, limited direct observations hinder our understanding of KI's mechanisms and responses to climate change. Here, we present a 60‐year bi‐monthly resolved coral oxygen isotope (δ18Oc) record from Dongsha Atoll, the northern SCS. The dry‐season (December–March) δ18Oc record reveals interannual to decadal variabilities of the KI. The impact of the East Asian winter monsoon (EAWM) on Dongsha δ18Oc was more pronounced during the 1970s and 1980s and after the early 2000s, while the influence of the El Niño‐Southern Oscillation (ENSO) on Dongsha δ18Oc was higher between the 1980s and 1990s. The Pacific Decadal Oscillation (PDO) may have a relatively minor effect on KI strength or may indirectly modulate KI strength through its influence on ENSO activities. Our Dongsha δ18Oc record highlight the importance of the EAWM, ENSO, and PDO in predicting future KI changes. Plain Language Summary: The Kuroshio intrusion is a branch of the Kuroshio Current. It flows into the South China Sea and affects its temperature, salinity, and water movement. We however know very little how the Kuroshio intrusion responds to climate changes. Here we present a study on the chemical composition of a coral core from Dongsha Atoll in the northern South China Sea. Our study shows that the intrusion varies markedly over the past 60 years and is connected to changes in sea surface salinity. Stronger intrusions align with stronger East Asian winter monsoon intensity and El Niño events. Understanding how the Kuroshio intrusion reacts to climate change is important for effectively managing the potential impacts of global warming on the marine ecosystem. Key Points: A 60‐year‐long coral oxygen isotope record from Dongsha Atoll, South China Sea reveals interannual to decadal variations in the Kuroshio intrusionStrong Kuroshio intrusion, corresponding to high sea surface salinity, is identifiable over the past 60 yearsThe Kuroshio intrusion variations are primarily driven by East Asian winter monsoon changes and also influenced by El Niño‐Southern Oscillation [ABSTRACT FROM AUTHOR]

The climate response of tropical Southeast Asia to abrupt climate change originating from high northern latitudes remains poorly understood. Here, marine sediments recovered from the Northwest Borneo Trough are analyzed to trace variations in terrigenous material composition associated with sea level and palaeoflood activities over the past 40 ka. We describe for the first time the influence of sea level change on terrigenous deposition from a tropical island with small mountainous rivers surrounded by narrow continental shelves and the coupling between North Atlantic dynamics and climate feedbacks in tropical Southeast Asia during the Dansgaard‐Oeschger stadials. This study demonstrates that climate oscillations occurring at high northern latitudes can be transmitted to tropical Southeast Asia through the functions of sea level, the East Asian winter monsoon and the Intertropical Convergence Zone. Such information is fundamental to correctly assessing future sea level rise and flood risks in tropical Southeast Asia. Plain Language Summary: Sea level rise and extreme climate events are two global climate issues currently faced by humanity under the background of global warming. However, the climate feedbacks in tropical Southeast Asia remain unknown, although portions of this region are now densely populated. Here, a gravity core retrieved from the Northwest (NW) Borneo Trough is employed to reveal variations in terrigenous material composition and their controlling factors over the past 40 ka. We found that the terrigenous sediments delivered to the NW Borneo Trough are primarily sourced from NW Borneo, and their deposition is mainly controlled by sea level change and flooding. Further in‐depth analysis reveals that northern high‐latitude cooling could cause floods in NW Borneo both in the modern and during the past by influencing the East Asian winter monsoon (EAWM) and/or the Intertropical Convergence Zone (ITCZ). Furthermore, our new records suggest that a stronger EAWM during cold stadials could have transported high levels of northerly moisture to NW Borneo, resulting in relatively higher speleothem δ18O values in NW Borneo. In short, abrupt climate changes in the high‐latitude Northern Hemisphere can be transmitted to tropical Southeast Asia through the functions of sea level, the EAWM and the ITCZ. Key Points: Sea level change and flooding are the main controlling factors for terrigenous deposition from tropical Southeast AsiaNorthern high‐latitude cooling could lead to the outbreak of floods in Northwest Borneo via atmospheric teleconnectionClimate oscillations occurring at high northern latitudes can be transmitted to tropical Southeast Asia [ABSTRACT FROM AUTHOR]

Abstract The Kuroshio intrusion (KI) is a northwestward‐flowing branch of the Kuroshio Current, which enters the South China Sea (SCS) and regulates its temperature, salinity, and water mass exchanges. However, limited direct observations hinder our understanding of KI's mechanisms and responses to climate change. Here, we present a 60‐year bi‐monthly resolved coral oxygen isotope (δ18Oc) record from Dongsha Atoll, the northern SCS. The dry‐season (December–March) δ18Oc record reveals interannual to decadal variabilities of the KI. The impact of the East Asian winter monsoon (EAWM) on Dongsha δ18Oc was more pronounced during the 1970s and 1980s and after the early 2000s, while the influence of the El Niño‐Southern Oscillation (ENSO) on Dongsha δ18Oc was higher between the 1980s and 1990s. The Pacific Decadal Oscillation (PDO) may have a relatively minor effect on KI strength or may indirectly modulate KI strength through its influence on ENSO activities. Our Dongsha δ18Oc record highlight the importance of the EAWM, ENSO, and PDO in predicting future KI changes.

Abstract The climate response of tropical Southeast Asia to abrupt climate change originating from high northern latitudes remains poorly understood. Here, marine sediments recovered from the Northwest Borneo Trough are analyzed to trace variations in terrigenous material composition associated with sea level and palaeoflood activities over the past 40 ka. We describe for the first time the influence of sea level change on terrigenous deposition from a tropical island with small mountainous rivers surrounded by narrow continental shelves and the coupling between North Atlantic dynamics and climate feedbacks in tropical Southeast Asia during the Dansgaard‐Oeschger stadials. This study demonstrates that climate oscillations occurring at high northern latitudes can be transmitted to tropical Southeast Asia through the functions of sea level, the East Asian winter monsoon and the Intertropical Convergence Zone. Such information is fundamental to correctly assessing future sea level rise and flood risks in tropical Southeast Asia.

Prolonged low temperature significantly threatens transportation and planting in populous areas and is closely linked to slowly varying forcing such as sea surface temperature (SST). In this study, we reveal the impact of the north–south dipole pattern in extra-tropical North Atlantic SST (DNA) anomaly on surface air temperature (SAT) over southern China in February. The positive phase of the DNA is favorable for a positive North Atlantic Oscillation-like pattern at the troposphere via synoptic eddy vorticity forcing and triggers a southeastward-propagating Rossby wave train associated with the deepened East Asian trough and the strengthened Siberian high, which are conducive to enhancement of the East Asian winter monsoon. A stronger monsoon leads to lower-than-normal SAT over southern China by intensifying southward cold air outbreaks. Considerably, the extremely low temperature over southern China in February 2022 is explainable by this physical mechanism. Furthermore, experiments with a linear baroclinic model verify that the proposed downstream propagating Rossby wave train is mainly associated with the midlatitude North Atlantic SST anomaly. These results emphasize that the extra-tropical North Atlantic SST anomaly should be focused when interpreting and predicting the late winter SAT over southern China. [ABSTRACT FROM AUTHOR]

The East Asian winter monsoon (EAWM) intensifies in the early twenty-first century and links with frequent impacts of large-scale persistent extreme cold events in winter in East Asia in recent years. We found that there has been a significant positive correlation between the EAWM and Interhemispheric Oscillation (IHO). However, conspicuous interdecadal variations have occurred in the relationship between the EAWM and IHO. The relationship between the IHO and EAWM was most significant during 1979–2020, but this relationship was weak and insignificant during 1962–1978. During 1979–2020, the atmospheric mass (surface pressure) difference between the Northern Hemisphere (NH) and Southern Hemisphere (SH) during 1979–2020 was significantly reduced by 7.85% (0.75 × 1015 kg) compared with that during 1962–1978. Such interhemispheric redistribution of atmospheric mass (AM) has had a distinct impact on the land-sea pressure contrast in East Asia and has intensified the connection between the EAWM and IHO. A strengthened EAWM has resulted in notable cooling and more severe winters in China. The apparent exportation of AM in the Antarctic region is an important driving factor for this interhemispheric change. The accompanying anomalous accumulation of AM in the NH is linked with an increase in the pressure difference between land and sea in East Asia, resulting in intensifying correlation between IHO and the EAWM. The decadal enhancement of the IHO during 1979–2020 was closely connected with conspicuous warming in the tropical troposphere/lower stratosphere (UTLS). A seesaw pattern of anomalous air temperature and ozone between tropical and Antarctic UTLS has induced a decrease in Antarctic ozone masses and air temperature and has strengthened the polar vortex, corresponding to a decadal enhancement of interhemispheric AM imbalance. [ABSTRACT FROM AUTHOR]

The Asian westerly jet streams in the upper troposphere play a pivotal role in shaping precipitation patterns, sustaining the diverse but fragile ecosystems in arid Central Asia. Despite their significance, the evolution history of these jet streams and their synergistic effects with the monsoon systems on regional climate change in Asia during the Holocene remain poorly understood. To address this gap, we present a continuous pollen record since 8.6 cal ka BP from Lake Shuang in the Altai Mountains. The first two principal components of the pollen data are employed to track regional changes in vegetation, summer moisture, and winter temperature. Meanwhile, the pollen data and the TraCE‐21ka simulation results were compared to reveal the dynamic mechanism of regional climate change. Results indicate a humid phase spanning the interval ∼8 to 5 cal ka BP in this region, which broadly coincides with the intensification of the Indian Summer Monsoon. This temporal correlation is potentially linked to the poleward shift of the Asian jet, as suggested by simulation results. Furthermore, our data show a consistent winter warming trend throughout the Holocene, indicated by changes in the dominant tree pollen taxa and a reduction of cold‐resistant‐taxa. This trend is associated with the weakening of the East Asian Winter Monsoon, influenced by increasing winter solar insolation and atmospheric CO2 concentration. Overall, our research provides strong paleoclimatological evidence highlighting the interconnected meteorological roles of the Asian jet and monsoon systems in shaping regional climates. Plain Language Summary: The Asian westerly jet streams in the upper troposphere have strong links with the precipitation that maintains the fragile ecosystems of arid Central Asia. Understanding the evolution of the Asian jet streams and their relationship with the winter and summer monsoon system is important for understanding climatic changes in this hydrologically‐constrained region. Pollen data help us to look into the past changes in vegetation and climate. Based on our study from the Altai Mountains, the abundance of birch forest was promoted under a humid climate, while pine forest grew with warmer winter conditions. The humid period in this region lasted from ∼8 to 5 cal ka BP and was linked to increasing summer precipitation. The increase of tree species well‐suited for warmer winter indicates a sustained winter warming trend since the early Holocene. We suggest that this warming trend was caused by the combination of the combined increases in winter insolation and atmospheric CO2 concentration. This persistent Holocene winter warming trend occurred in the regions controlled by the Asian jet and winter monsoon, providing strong evidence for a relationship between them. Key Points: A Holocene pollen record from Lake Shuang in the Altai Mountains shows a humid period during ∼8–5 cal ka BP with persistent winter warmingThis humid period maybe due to a poleward shift of the Asian jet center linked with a strong Indian Summer MonsoonHolocene winter warming was caused by the increasing of CO2 concentration and solar insolation [ABSTRACT FROM AUTHOR]

Based on the daily average temperature data of 2374 stations in China from 1993 to 2022 and the monthly average temperature data of European Centre for Medium‐Range Weather Forecasts (ECMWF) System5 in winter, this article analyses the intraseasonal variations of winter surface air temperature (SAT) over China by using seasonal empirical orthogonal function decomposition (S‐EOF) and compare the prediction skill differences of the first three dominant modes in ECMWF System5. The first mode (S‐EOF1) is characterized by out‐of‐phase changes in SAT anomalies (SATA) between December and January. Both the Siberian high (SH) and the central Pacific El Niño‐Southern Oscillation (CP ENSO) can impact S‐EOF1. The second mode (S‐EOF2) is characterized by consistency in warm anomalies over the Northeast and Qinghai‐Tibet Plateau's variation, while the other areas are characterized by the out‐of‐phase change in SATA. S‐EOF2 is closely related to Arctic oscillation (AO). The third mode is characterized by alternating changes over 3 months in winter, which is related to the Pacific meridional mode (PMM) and the North Atlantic SST tripole (NAT). Comparing the ECMWF System5 prediction skill for the first three leading modes for the intraseasonal variations in winter SAT, the prediction skill is not high. The model did not predict the extent of warm anomalies and the intraseasonal fluctuation in S‐EOF1, which may be due to the poor prediction skills for the range and intensity of the CP ENSO and the SH. The second mode has the highest prediction skill among the three modes. For the prediction skill of AO is good. The model can capture the intraseasonal reverse SATA between December and January but did not capture the reverse SATAs between January and February. Because the model does not predict obvious PMM and NAT well. [ABSTRACT FROM AUTHOR]

Studies of the multi-scale climate variability of the Asian monsoon are essential to an advanced understanding of the physical processes of the global climate system. In this paper, the progress achieved in this field is systematically reviewed, with a focus on the past several years. The achievements are summarized into the following topics: (1) the onset of the South China Sea summer monsoon; (2) the East Asian summer monsoon; (3) the East Asian winter monsoon; and (4) the Indian summer monsoon. Specifically, new results are highlighted, including the advanced or delayed local monsoon onset tending to be synchronized over the Arabian Sea, Bay of Bengal, Indochina Peninsula, and South China Sea; the basic features of the record-breaking mei-yu in 2020, which have been extensively investigated with an emphasis on the role of multi-scale processes; the recovery of the East Asian winter monsoon intensity after the early 2000s in the presence of continuing greenhouse gas emissions, which is believed to have been dominated by internal climate variability (mostly the Arctic Oscillation); and the accelerated warming over South Asia, which exceeded the tropical Indian Ocean warming, is considered to be the main driver of the Indian summer monsoon rainfall recovery since 1999. A brief summary is provided in the final section along with some further discussion on future research directions regarding our understanding of the Asian monsoon variability. [ABSTRACT FROM AUTHOR]

As one of the most significant circulation systems over the Northern Hemisphere in the cold season, the East Asian winter monsoon (EAWM) has been broadly investigated from the seasonal-mean perspective, while subseasonal variations in the EAWM still remain ambiguous. Based on Season-reliant Empirical Orthogonal Function (S-EOF) analysis, this study shows that the subseasonal strength reversal of the EAWM (SR-EAWM), featuring a weaker (or stronger) EAWM in early winter (December) and a stronger (or weaker) EAWM in late winter (January–February), is a distinct leading mode of the month-to-month variation of the EAWM. The weak-to-strong SR-EAWM is characterized by an anomalous low over Eurasia and a weakened East Asian major trough (EAT) in early winter, with an intensified Siberian High and a deepened EAT in late winter. The SR-EAWM is preceded by surface air temperature anomalies over Davis Strait (DST) and those over central-eastern North America (CENAT) in September–October. The DST mainly influences the SR-EAWM in early winter through a "sea ice bridge" of the November Baffin Bay sea ice concentration anomaly (BBSIC). The BBSIC could intensify the DST in December by altering surface heat flux, thus exciting a downstream atmospheric response and modulating the strength of the EAT in early winter. The CENAT affects the SR-EAWM in late winter by inducing an "ocean bridge" of the western North Atlantic sea surface temperature anomaly (WNASST). The WNASST can persist into late winter and then significantly affects the SR-EAWM by regulating Eurasian circulation anomalies and the downstream EAT. The bridge roles of the BBSIC and WNASST can be further verified by a linear baroclinic model. Finally, two physical-empirical models are established using the DST/BBSIC and the CENAT indices, respectively. Both exhibit promising prediction skills. The results highlight that the DST, BBSIC, and CENAT are crucial predictability sources for the SR-EAWM. [ABSTRACT FROM AUTHOR]

Dust deposition in northeastern Asia since the Last Glacial Maximum has previously been studied using a variety of archives. However, the mechanisms driving variability in dust are less well constrained. Here, we present records of the Nd‐Sr isotope and major element composition of sediments from Lake Tuofengling, a crater lake located in northeastern China, over the past ∼25 thousand years. The results indicate that the lithogenic fractions of the sediments are a mixture between aeolian dust and local volcanic detritus. Our provenance data suggest that the aeolian dust component is predominantly from the Mongolia Plateau, likely carried by the East Asian Winter Monsoon. Our isotope and calculated dust flux records exhibit similar changing patterns to proxies of global ice volume and the strength of Atlantic meridional overturning circulation, potentially implicating ice sheets and ocean circulation as the dominant drivers of the East Asian Winter Monsoon over this time interval. Plain Language Summary: Dust storms occur frequently throughout Central and East Asia today. Several driving factors, particularly related to the East Asian Summer Monsoon, the East Asian Winter Monsoon (EAWM), and the westerlies, can influence dust production and transport in these regions, both in the modern and during the past. Uncovering the dominant factor(s) can assist in furthering our understanding of atmospheric circulation over Asia during climates both similar and different from today. Here, we collected sediments from a crater lake (Lake Tuofengling (TFL)) located in northeastern Asia and reconstructed dust inputs over the past 25 thousand years. We found that the dust delivered to TFL sediments is mainly sourced from the Mongolian Plateau associated with transport via winds related to the EAWM. Further in‐depth analysis indicates that shifts in ice volume and Atlantic Ocean circulation may be important drivers for the EAWM, at least over the past 25 thousand years. Key Points: Geochemical evidence suggests that the Mongolian Plateau (MP) is the main source of dust for Lake Tuofengling (TFL)The East Asian Winter Monsoon (EAWM) is likely the dominant carrier of aeolian dust from the MP to TFLDust flux and EAWM variability could be driven by a combination of changes in ice volume and Atlantic Ocean circulation [ABSTRACT FROM AUTHOR]

The evolution of the East Asian winter monsoon (EAWM) during the Holocene remains controversial because of the lack of reliable proxies. In this study, a link between cross‐front transport and the EAWM was found in the North Yellow Sea, and the EAWM intensity could be imprinted in the leaked sediment, which permits reliable reconstruction of the EAWM on well‐preserved offshore deposition. By comparison with instrumental data, the wind speed of the EAWM since 4.4 ka was quantitatively reconstructed for the first time at high resolution (∼5 yr). The results show that the EAWM gradually weakened in the mid‐to‐late Holocene, which was likely controlled by solar insolation, and that there has been a negative relationship between the EAWM and temperature on the centennial scale since ∼2.0 ka; this relationship was reversed by increasing CO2 emissions during the Current Warm Period. Plain Language Summary: The East Asian monsoon is characterized by a distinct seasonal reversal of monsoon flow driven by temperature differences between the Pacific Ocean and the East Asian continent. It influences more than 2 billion people around East Asia by regulating the risk of drought or flooding. However, the evolution of the East Asian winter monsoon (EAWM) in the mid‐to‐late Holocene remains elusive, limiting our understanding of its driving force and projections under climate change. This study analyzed sediment transport dynamics under varying winter monsoons in the North Yellow Sea. It was found that coastal sediments could be transported offshore, and their pathways differed under different strengths of the winter monsoon. Based on the sedimentary records of offshore muddy deposition, the EAWM proxy was extracted, and the wind speed of the EAWM from 4.4 ka was quantitatively reconstructed. A gradual weakening trend during 4.4–0.7 ka and a dramatic strengthening after 0.2 ka were found in the EAWM; the EAWM was negatively related to the temperature on the centennial scale since ∼2.0 ka, but this relationship was reversed by an increase in CO2 emissions since ∼1800 CE, indicating a shift in the controlling mechanism. Key Points: A link between cross‐front transport and the East Asian winter monsoon (EAWM) was found in the shelf sea, and the leaked sediment was used to reconstruct the EAWMThe wind speed of the EAWM since 4.4 ka was quantitatively reconstructed at high resolution (∼5 yr) for the first timeCorrelation between the EAWM and the temperature on the centennial scale since ∼2.0 ka was reversed by the increasing CO2 at the Current Warm Period [ABSTRACT FROM AUTHOR]

Abstract Dust deposition in northeastern Asia since the Last Glacial Maximum has previously been studied using a variety of archives. However, the mechanisms driving variability in dust are less well constrained. Here, we present records of the Nd‐Sr isotope and major element composition of sediments from Lake Tuofengling, a crater lake located in northeastern China, over the past ∼25 thousand years. The results indicate that the lithogenic fractions of the sediments are a mixture between aeolian dust and local volcanic detritus. Our provenance data suggest that the aeolian dust component is predominantly from the Mongolia Plateau, likely carried by the East Asian Winter Monsoon. Our isotope and calculated dust flux records exhibit similar changing patterns to proxies of global ice volume and the strength of Atlantic meridional overturning circulation, potentially implicating ice sheets and ocean circulation as the dominant drivers of the East Asian Winter Monsoon over this time interval.

Coastal dune sediments and landforms offer a unique opportunity to understand climate change and sea level change on the centennial-millennial time scale. However, there is a paucity of chronological studies on the effects of storms on the evolution of coastal dunes along the temperate coastline of China. In this study, optically stimulated luminescence (OSL) dating of sand dunes was conducted to investigate the process and mechanism of coastal dune evolution on the southeastern coast of Hainan Island, China. The results show that the coastal dune evolution experienced three rapid accumulation periods: 28-21 ka, 14-4 ka, and 3.0 ka-present. The three rapid accumulation periods correspond to the last glacial maximum, the late Pleistocene/early-mid Holocene, and the late Holocene climatic dry-cold period, respectively. Sea level change and the East Asian winter monsoon, in conjunction with the enhanced storminess, play a key role in driving the sand dune evolution on the south-eastern coast of Hainan Island. These findings are of great significance for regional planning and coastal defense schemes.

Abstract The evolution of the East Asian winter monsoon (EAWM) during the Holocene remains controversial because of the lack of reliable proxies. In this study, a link between cross‐front transport and the EAWM was found in the North Yellow Sea, and the EAWM intensity could be imprinted in the leaked sediment, which permits reliable reconstruction of the EAWM on well‐preserved offshore deposition. By comparison with instrumental data, the wind speed of the EAWM since 4.4 ka was quantitatively reconstructed for the first time at high resolution (∼5 yr). The results show that the EAWM gradually weakened in the mid‐to‐late Holocene, which was likely controlled by solar insolation, and that there has been a negative relationship between the EAWM and temperature on the centennial scale since ∼2.0 ka; this relationship was reversed by increasing CO2 emissions during the Current Warm Period.

It is generally accepted that the glacial‐interglacial variations of the East Asian winter monsoon (EAWM) are controlled by the volume of the Northern Hemisphere ice sheets (NHIS), but the fact that they exhibit different evolution patterns during glacial inceptions is often overlooked. By generating an independent chronology framework and integrating multi‐proxy records from the loess sections on the central Chinese Loess Plateau, here we show that the rapid intensifying of the EAWM during glacial inceptions reflects millennial perturbations in the large‐scale atmospheric circulation in East Asia in response to insolation‐triggered abrupt North Atlantic cooling. This climate teleconnection between North Atlantic and East Asia is found to be particularly effective only when the NHIS reaches a critical large size. Our integrated multi‐proxy records thus highlight the key role of ice volume in modulating the response of the EAWM to insolation‐triggered North Atlantic cooling during the interglacial‐glacial transitions. Plain Language Summary: The strength of the East Asian winter monsoon is thought to be dynamically linked to the volume of the Northern Hemisphere ice sheets during the Quaternary glacial‐interglacial cycles. Nevertheless, paleoclimatic records generally indicate a rapid shift in the East Asian winter monsoon intensity in the mid‐way of the gradual build‐up of the Northern Hemisphere ice sheets, meaning that our current understanding of the East Asian winter monsoon dynamics remains elusive. By generating an independent chronology framework and integrating multi‐proxy records from the loess sections on the central Chinese Loess Plateau, here we show that the rapid intensifying of the East Asian winter monsoon during glacial inceptions, previously demonstrated as a direct response to the build‐up of the Northern Hemisphere ice sheets, actually reflects millennial perturbations in the large‐scale atmospheric circulation in East Asia caused by insolation‐triggered abrupt North Atlantic cooling when Northern Hemisphere ice sheets reach a critically large size. Our results thus offer new insights into how the climate teleconnections between high‐ and middle‐latitudes of the Northern Hemisphere have controlled the East Asian winter monsoon during glacial inceptions. Key Points: Microcodium 87Sr/86Sr record captures the cooling trend in East Asia at the interglacial‐glacial transitionsDecoupled evolution of East Asian winter monsoon and temperature occurred during glacial inceptionsIce volume modulates the response of East Asian winter monsoon to insolation‐triggered North Atlantic cooling during glacial inceptions [ABSTRACT FROM AUTHOR]

Chinese loess provides the most detailed terrestrial records of paleoclimate changes. We employed the grain-size components of aeolian sediments to reconstruct the history of the East Asian winter monsoon (EAWM) on the Chinese Loess Plateau (CLP). Here, using the grain-size class vs. standard deviation method, we extracted the environmentally sensitive grain-size components of nine last glacial loess sections. The grain-size class vs. standard deviation diagrams showed two major grain-size components (fine and coarse), which varied from section to section. Material resource distances and post-depositional pedogenesis were the main factors affecting environmentally sensitive grain-size components. The coarse grain-size components of the Yulin, Baicaoyuan, Xifeng, and Luochuan sections were influenced by the transportation distance, while we attributed the fine grain-size components of the Weinan, Shaoling, Duanjiapo, and Chaona sections to pedogenesis. At the same time, the Mianchi section's sensitive grain-size component was also coarse, and was affected by the local circulation from the nearby Yellow River terrace. Our comparison of sensitive grain-size components and EAWM revealed that the coarse grain-size components were progressively finer along with the EAWM from the northwest to the southeast on the CLP, and they can be regarded as the most suitable proxy indicator of the EAWM on the CLP. [ABSTRACT FROM AUTHOR]

The turnabout of air temperature anomalies over East Asia between the first and second halves of winter 2020/21 was examined from a teleconnection perspective with regionally different convective heating anomalies over the Indo-westem Pacific sector. In the first half of winter 2020/21, the air temperature over East Asia was lower than normal, accompanied by a pair of anticyclonic and cyclonic anomalies in the upper troposphere southeast of the Tibetan Plateau and north of Japan, respectively. This dipole pattern is newly referred to as the Southeast Asia-Japan (SAJ) pattern in this study, indicating the propagation of Rossby waves caused by enhanced tropical convection over the eastern Indian Ocean toward the South China Sea. In the second half of winter 2020/21, the enhanced convection shifted eastward to the Philippine Sea. The subsequent anticyclonic anomaly changed its position to the south of Japan, which was similar to the western Pacific (WP)-Iike teleconnection pattern, causing warmer conditions over East Asia. The composite analysis indicated that the anomalous anticyclone over the southeastern Tibetan Plateau corresponding to the SAJ pattern emerged simultaneously with intensification of convection over the South China Sea. Half of the cases of the WP-Iike pattern have been accompanied by enhanced convection over the Philippine Sea. The different circulation patterns were reproduced by prescribing the heat source over the South China Sea and Philippine Sea to the linear baroclinic model. Moreover, the vorticity budget analysis suggested that the presence of upper-tropospheric convergence of winds to the southeast of the Tibetan Plateau seen in the climatology is conceivable for the in situ localized anomalous circulation constituting the SAJ pattern due to vortex stretching effects. [ABSTRACT FROM AUTHOR]

The changes in near-surface wind speed (NWS) have a crucial influence on the wind power industry, and previous studies have indicated that NWS on global and China has declined continuously for decades under global warming. However, recently, the decreasing trend of global NWS has slowed down and even showed a recovery trend. Using the observation data of 831 weather stations of the China Meteorological Administration and the Japanese 55-year reanalysis data from 1970 to 2019, NWS changes in eastern China were analyzed and the possible influencing factors were discussed. Results show that winter NWS presented a decreasing trend from −0.29 m s−1 per decade (p

The scarcity of Holocene winter temperature records from the core area of the Mongolian-Siberian High (MSH) hampers our understanding of the long-term evolution of the MSH and its modulation of the East Asian Winter Monsoon (EAWM). Here we use the body size of Pediastrum , a new and sensitive temperature proxy, from the sediments of Tolbo Lake in the western Mongolian Plateau, to reconstruct changes in winter temperature in the core area of the MSH during the Holocene. A large-scale investigation of modern Pediastrum body size across East Asia indicates that it is an accurate proxy indicator for mean winter temperature. The Holocene winter temperature based on Pediastrum body size from Tolbo Lake shows a general warming trend with the maximum at ∼2.6 ka. The current warming has attained the magnitude of the previous Holocene maximum, despite the underlying forcing being different. The mid-late Holocene winter warming in inland Eurasia may have weakened the MSH and reduced the intensity of the EAWM. • First Holocene winter temperature record based on Pediastrum body size. • Increasing trend of Holocene winter temperature in the Altai Mountains. • Holocene winter warming in inland Eurasia weakened the East Asia winter monsoon. [ABSTRACT FROM AUTHOR]

Abstract It is generally accepted that the glacial‐interglacial variations of the East Asian winter monsoon (EAWM) are controlled by the volume of the Northern Hemisphere ice sheets (NHIS), but the fact that they exhibit different evolution patterns during glacial inceptions is often overlooked. By generating an independent chronology framework and integrating multi‐proxy records from the loess sections on the central Chinese Loess Plateau, here we show that the rapid intensifying of the EAWM during glacial inceptions reflects millennial perturbations in the large‐scale atmospheric circulation in East Asia in response to insolation‐triggered abrupt North Atlantic cooling. This climate teleconnection between North Atlantic and East Asia is found to be particularly effective only when the NHIS reaches a critical large size. Our integrated multi‐proxy records thus highlight the key role of ice volume in modulating the response of the EAWM to insolation‐triggered North Atlantic cooling during the interglacial‐glacial transitions.

This paper reviews recent advances in understanding the interaction between the East Asian winter monsoon (EAWM) and El Niño-Southern Oscillation (ENSO). The achievements are summarized into two aspects: 1) the impacts of ENSO on the EAWM, and 2) effects of the EAWM on ENSO. For the first aspect, the results show that: the current climate model simulations of ENSO impacts on the EAWM have a common weaker bias than in the observations; The influence of central Pacific type ENSO on the EAWM is generally weaker than that of the eastern Pacific type ENSO; The precipitation anomalies in the tropical Indian Ocean tend to contribute to the intra-seasonal transition of ENSO teleconnection over East Asia; The ENSO-EAWM relationship is unstable and subject to non-linear modulation by the state of oceans and extratropical atmospheric phenomena, which include the Pacific Decadal Oscillation and the Arctic Oscillation. Regarding the second aspect, studies have shown that the “pure” EAWM (denoted as EAWMres), which is independent of the ENSO signal, can lead to significant variations in the tropical convection over the western Pacific, the local Hadley circulation over East Asia, and the Walker circulation over the equatorial latitudes; The CMIP6 models can preproduce the above EAWMres effects well, although with some weaker bias. The changes in tropical convection and extratropical zonal flow associated with the EAWMres tend to have a significant modulating effect on the ENSO atmospheric teleconnection over North America. A strong EAWM and a strong Australian summer monsoon coherently provide favorable conditions for the onset of El Niño.

Strong cold air outbreaks caused heavy snowfall over the inland areas of the Sea of Japan coast of Japan in mid‐December 2020. The 48‐hr accumulated snowfall during the term broke a snowfall record at some observational stations of the Japan Meteorological Agency (JMA). We investigated the impacts of atmospheric and oceanic temperature changes due to historical global warming since the pre‐industrial period on this heavy snowfall event. Hindcast and pseudo non‐warming experiments were conducted using the nonhydrostatic model developed by the JMA. The historical climatic differences were obtained from the database for policy decision‐making for future climate change (d4PDF). Our experiments indicated that historical global warming enhanced precipitation over the whole region and enhanced heavy snowfall over the inland areas on the Sea of Japan side. In this event, the contribution of conversion from snowfall to rainfall due to warming was limited over coastal areas. The enhancement of precipitation was mainly caused by oceanic warming, which increased latent heat flux over the Sea of Japan and made the low‐level atmosphere less stable. Historical atmospheric warming suppressed precipitation due to atmospheric stabilization. Our results indicated that the heavy snowfall was caused by the cold air outbreaks under the warm sea surface temperatures in December and enhanced by historical global warming. Plain Language Summary: Heavy snowfall occurs over the inland areas of the Sea of Japan coast in mid‐December 2020. The 48‐hr accumulated snowfall broke a snowfall record at some observational stations. The numerical simulations indicate that historical global warming since the pre‐industrial period enhanced the heavy snowfall over the inland areas on the Sea of Japan side. The oceanic warming is more important for the enhancement of snowfall than atmospheric warming only, because oceanic warming supplies more moisture to the atmosphere and makes the low‐level atmosphere less stable. Since the sea surface temperature in December is warmer than that in other month in winter, it widely enhances snowfall over the inland areas along the Sea of Japan. Key Points: Historical global warming enhanced heavy snowfall occurring over inland areas along the Sea of Japan in central Japan in mid‐December 2020Sensitivity experiments indicate that warming of the Sea of Japan mainly contributed to the enhancement of heavy snowfallOceanic warming supplies more moisture to the atmosphere and makes the low‐level atmosphere less stable, which enhances precipitation [ABSTRACT FROM AUTHOR]

It is still not well understood if subseasonal variability of the local PM2.5 in the Beijing-Tianjin-Hebei (BTH) region is affected by the stratospheric state. Using PM2.5 observations and the ERA5 reanalysis, the evolution of the air quality in BTH during the January 2021 sudden stratospheric warming (SSW) is explored. The subseasonal variability of the PM2.5 concentration after the SSW onset is evidently enhanced. Stratospheric circumpolar easterly anomalies lasted for 53 days during the January–February 2021 SSW with two evident stratospheric pulses arriving at the ground. During the tropospheric wave weakening period and the intermittent period of dormant stratospheric pulses, the East Asian winter monsoon weakened, anomalous temperature inversion developed in the lower troposphere, anomalous surface southerlies prevailed, atmospheric moisture increased, and the boundary layer top height lowered, all of which favor the accumulation of pollutant particulates, leading to two periods of pollution processes in the BTH region. In the phase of strengthened East Asian winter monsoon around the very beginning of the SSW and another two periods when stratospheric pulses had reached the near surface, opposite-signed circulation patterns and meteorological conditions were observed, which helped to dilute and diffuse air pollutants in the BTH region. As a result, the air quality was excellent during the two periods when the stratospheric pulse had reached the near surface. The increased subseasonal variation of the regional pollutant particulates after the SSW onset highlights the important role of the stratosphere in the regional environment and provides implications for the environmental prediction. [ABSTRACT FROM AUTHOR]

Studying the sedimentary characteristics of the muddy area along the Yellow Sea shelf is of great significance for deepening the understanding of the climate and environment evolution since the last glacial period. Recently, a small muddy area developed in the southern Weihai offshore has attracted a lot of attention. Based on high-resolution grain size, clay mineral, AMS14C, and OSL data of sediments from the core WHZK01 in the muddy area, we acquired a new understanding of sedimentary characteristics, sources and paleoclimatic environment during the last 13 kyr. The results show that the core WHZK01 sediments were mainly from the Yellow River and local rivers along the coast. However, the sources varied for different deposition units. The riverbed (before 13 kyrBP) and fluvial plain deposits (13–10 kyrBP) were mainly from local river inputs. The very thin littoral deposits from 10 kyrBP to 8 kyrBP also mainly originate from coastal river inputs, while the littoral-neritic deposits since 8 kyrBP were dominated by the Yellow River materials and partly supplied by the coastal rivers and the island erosion. In addition, five events related with the strong East Asian winter monsoon (EAWM) during the intervals of 13.0–11.0 kyrBP, 10.0–8.2 kyrBP, 7.0–5.0 kyrBP, 3.5–2.5 kyrBP, and 1.2–0.5 kyrBP were identified. Three events related with the enhancement of the EAWM since the middle Holocene have strengthened the transport capacity of the coastal currents of the Shandong Peninsula. Meanwhile, more Yellow River-derived distal sediments were deposited to the southern Weihai offshore and formed wedge-shaped muddy bodies. In short, the ratio of smectite/illite could be used as an effective EAWM indicator since 13 kyrBP on the northwestern shelf of the South Yellow Sea. [ABSTRACT FROM AUTHOR]

In this study, we used a ~47.0-kyr record of Sr–Nd isotopic data derived from lake sediments in Dahu swamp in the eastern Nanling Mountains to explore the possible changes in the source of sediments, and to provide insights into the East Asian winter monsoon (EAWM) driven climatic signals. Based on Sr–Nd isotopic results, we argued that local weathered granitic residues were the dominant source of sediments throughout the past ∼47.0 kyr. However, variations of 87Sr/86Sr and 144Nd/143Nd ratios were likely disturbed by the mixture of an additional input from Chinese Loess Plateau (CLP). During some dry/cold millennial periods (e.g., Heinrich event 5, 4, and 2, and the 26.0–24.0 kyr B.P), similar Sr–Nd isotopic signatures between the lake sediments and the fine fraction (<20 μm) of the loess from CLP implied an aeolian dust source. Thus, variability of Sr-Nd isotopic ratios indirectly indicated two modes of climate patterns: the wet and warm intervals during which the sediments were mainly derived from the local weathered residues were expressed in increased 87Sr/86Sr and decreased 144Nd/143Nd ratios, whereas during the dry and cold intervals the increased input of fine dust from CLP transported by strengthened EAWM winds would favor declined 87Sr/86Sr and increased 144Nd/143Nd ratios. Our Sr‒Nd isotopic records revealed an anti-phase between the EAWM and the summer monsoon, and displayed a good consistency with the record of mean grain size of quartz of loess from CLP, which was regarded as a reliable proxy of EAWM, suggested they can indirectly reflect variability of EAWM strength. [ABSTRACT FROM AUTHOR]

This paper collects and analyzes the 1954–2017 monthly average reanalysis data from the U.S. National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR), the 1954–2017 haze days observation data from the National Meteorological Information Center/China Meteorological Administration (NMIC/CMA) and the PM2.5 daily average mass concentration data in 2013–2017 from the China Air Quality Online Monitoring Platform. The atmospheric apparent heat source Q1 (negative Q1 means cold source in winter) over the Tibetan Plateau in December of 1954–2017 is estimated based on thermodynamic equations, and the East Asian winter monsoon index (EAWMI) is calculated. In addition, the discrepancies of the air quality among China's five typical regions (Beijing–Tianjin–Hebei, Fen-Wei Plain, Yangtze River Delta, Pearl River Delta and Sichuan-Chongqing regions) under the joint influence of the Q1 and EAWMI are studied. Results show that when it is a strong cold source year, abnormal downdrafts and "temperature inversion covers" occur in areas far from the high terrain, resulting in increased pollution, while the opposite is true in weak cold source years. In strong EAWMI years, there is an abnormal northerly sinking cold flow in the lower layers of mid-high latitudes, which increases the pollution in the area south of 30° N, and the opposite is true in weak EAWMI years. Affected by the combined activities of the Q1 and the EAWMI, the meteorological conditions of the five typical regions are different, and thus present different air pollution characteristics. [ABSTRACT FROM AUTHOR]

The leading mode of the atmospheric background flow over the North Atlantic–Arctic Ocean (i.e., 300-hPa meridional wind; V300-EOF1) exhibited notable decadal variations during 1979–2019, with intensified V300-EOF1 since the early-2000s. The modulation of the interdecadal change in the East Asian winter monsoon (EAWM) by the V300-EOF1 mode and its link with the concurrently warmer North Atlantic and low Arctic sea ice was explored through observational analysis and numerical simulations. The results indicated that the intensified V300-EOF1 mode enhanced the modulation of Rossby wave trains propagating from the North Atlantic–Arctic region to East Asia, which interfered with the climatological quasi-stationary waves to induce a stronger EAWM. The widespread North Atlantic–Arctic warming tended to modulate and interact with this V300-EOF1 background flow, which further enhanced the quasi-stationary Rossby waves along the midlatitude and sub-polar waveguides, resulting in a strengthened EAWM and cold East Asia. This finding was further verified by numerical experiments conducted with an atmospheric model. The model responses generally captured the observed physical processes, albeit weaker in magnitude, suggestive of a modulating role played by external forcings in the enhancement of the V300-EOF1 mode and the EAWM. Noting also the large internal variability in the atmospheric responses, with approximately half of the model years capturing a stronger-than-average East Asian cooling along with deep and strong Arctic warming. This further indicates the importance of atmospheric internal variability in the development of the V300-EOF1 mode. These results have implications for future changes in the EAWM and concomitant East Asian cooling on interdecadal timescales. [ABSTRACT FROM AUTHOR]

This study investigates inter‐model spreading of changes in East Asian winter monsoon circulation and the underlying reasons under 1.5 and 2.0°C global warming for Representative Concentration Pathway 8.5. Results show that the spatial patterns of multi‐model ensemble and inter‐model spreading of changes in 850‐hPa zonal and meridional winds over East Asia are similar under the two global warming targets. The multi‐model ensemble changes in 850‐hPa meridional wind (V850) over southern China are near zero under the two targets. Meanwhile, the V850 changes over southern China exhibit large inter‐model spreading, which is closely related to those of regional differences in sea surface temperature changes (DSSTC) in the tropical Pacific. Models with positive V850 anomalies over southern China tend to project weak (strong) surface warming in the western North Pacific (South China Sea and the equatorial central and eastern Pacific). Such a configuration results in decreased precipitation over the east of the Philippines and hence an anomalous lower‐level high to its northwest. Accordingly, southwesterly anomalies prevail over southern China. The southwesterly anomalies are further enhanced by related positive feedback processes. Models with negative V850 anomalies tend to project strong (weak) surface warming in the western North Pacific (South China Sea). The projected surface warming in the equatorial central and eastern Pacific is also strong, but weaker than that of models with positive V850 anomalies. Therefore, the induced precipitation and circulation changes over the East Asia–western North Pacific are basically opposite to those described above. Besides, the inter‐model spreading of V850 changes over southern China decrease by about 36.2% from 1.5 to 2.0°C global warming, which can be partly attributed to the decrease in the inter‐model spreading of DSSTC in the tropical Pacific. Numerical experiments confirm the role of the sea surface temperature changes in the tropical Pacific. [ABSTRACT FROM AUTHOR]

The boreal winter precipitation variability over East Asia and the western North Pacific is often attributed to the El Niño-Southern Oscillation (ENSO). The present study investigates the independent impacts of the East Asian winter monsoon (EAWM) on winter precipitation anomalies over East Asia and the western North Pacific. It is revealed that anomalous EAWM is accompanied by a south-north dipole pattern of precipitation anomalies in the above regions. During strong EAWM years, the enhanced northeasterly winds induce anomalous convergence and divergence over the tropical and subtropical regions, respectively, leading to anomalous ascent and above-normal precipitation over the southern South China Sea-Philippine Sea and anomalous descent and below-normal precipitation over eastern China-subtropical western North Pacific. Opposite convergence, vertical motion and precipitation anomalies are induced in the above regions during weak EAWM years. In the observations, both ENSO and EAWM contribute to the south-north dipole precipitation anomaly pattern with a larger contribution from ENSO and EAWM for the tropical and subtropical precipitation anomalies, respectively. Atmospheric model experiments with climatological annually varying sea surface temperature forcing confirm the independent role of the EAWM in the formation of the south-north dipole precipitation anomaly pattern. A moisture budget diagnosis shows that the dynamic effect associated with vertical motion is dominant in the formation of the above precipitation anomaly pattern in both the observations and model simulations. The horizontal moisture transport has an additional contribution to the formation of subtropical precipitation anomalies. [ABSTRACT FROM AUTHOR]

Using the ERA5 and MERRA2 reanalysis, and surface meteorological observation data, this study explores the possible impact of the sudden stratospheric warming (SSW) events on air quality in the Beijing-Tianjin-Hebei (BTH) region. As the duration of split SSW events is longer and the stratospheric signal pulses propagate further downward than displacement SSWs, subseasonal variability of the atmospheric particulates in the BTH is larger during split SSWs. The air particulate concentration is light before the SSW onset due to the enhanced perturbation in the troposphere associated with strengthened planetary waves. The air particulate concentration around the SSW onset dates begins to rise due to weakening of the tropospheric disturbance as the enhanced planetary waves enter the stratosphere. In the decaying period of the SSW, the air particulate concentration decreases as the stratospheric negative Northern Annular Mode (NAM) signal propagates downward. Specifically, in the pre-SSW period of displacement (split) SSW events, a wavenumber-1-like (wavenumber-2-like) anomaly pattern is strengthened. The East Asian winter monsoon intensifies as the east Asian trough is deepened especially before the split SSW event onset, leading to a cleaning period. Around the SSW onset period as the tropospheric perturbation diminishes and the East Asian winter monsoon weakens, a surge of air particulate concentration is observed. After the SSW onset, due to the downward propagation of the stratospheric negative NAM signal, cold anomalies form in the northeastern East Asia especially for split SSWs, corresponding to a cleaning period in the BHT region. The local meteorological conditions during the SSWs are also discussed. [ABSTRACT FROM AUTHOR]

The snow cover extent (SCE) on the southeastern Tibet Plateau (SETP) has an important impact on the dynamics of the East Asian winter monsoon and the runoff changes of the first and third largest rivers in Asia, namely, the Yangtze River and the Yarlung Zangbo River. Unfortunately, the shortness of instrumental SCE data of a few decades limits our ability to understand its long-term variability before the industrial era. Here, we developed Abies faxoniana tree-ring total ring width (TRW), early-wood width (EWW), and late-wood width (LWW) chronologies for the past four centuries at Little Qamdo Village (XQDV), Markam County, on the SETP. The most significant positive correlation (r = 0.62, p < 0.01) was found between the EWW chronology and SCE from March to May (SCE3–5). The SCE would affect the onset of the growing season through soil moisture, restricting the early-wood growth of trees. Thus, we presented a reconstruction of SCE3–5via EWW chronology since AD 1660 for SETP. We observed two abrupt changes from low to high around the years 1685 and 1998 for our reconstructed SCE3–5. In addition, we found that the positive anomalies of the reconstructed SCE3–5 after 1988 cohered with the distinct increase of the East Asian winter monsoon.

Here, we perform a set of sensitivity experiments in a climate model to quantify the impacts of local and remote insolation changes on the East Asian winter monsoon (EASM) and Australian summer monsoon (AusSM) at early and middle Holocene relative to the present. We show that the EAWM during Holocene is enhanced, driven overwhelmingly by the local insolation change in the low to mid‐latitude Northern Hemisphere (NH) through its impacts on land‐sea thermal contrast, with the NH high latitude forcing playing a negligible role. In contrast, the AusSM is also enhanced, opposite to the local insolation forcing, because the local forcing impact is overwhelmed by that from the remote forcing of both NH low latitude and Southern Hemisphere high latitude, with the latter dominating in the mid‐Holocene. Plain Language Summary: Orbital‐induced insolation variations play an important role in driving monsoon changes at geological time scales. One key issue that has remained outstanding is whether the monsoon is driven by local insolation from the corresponding hemisphere or remote insolation from the other hemisphere. For the first time, this work systematically isolates local and remote insolation impacts on East Asian winter monsoon (EAWM) and Australian summer monsoon (AusSM) during the early and middle Holocene. Our study suggests that the EAWM is enhanced during Holocene compared with PI by local insolation forcing over the Northern Hemisphere (NH) tropical‐mid‐latitude region. In contrast, the weakening impact on AusSM by local insolation is completely overwhelmed by the enhancement of the remote forcing from both the NH low latitude and Southern Hemisphere high latitude. Key Points: The first study to isolate the local and remote insolation effect on East Asian winter monsoon and Australian summer monsoonThe enhanced East Asian winter monsoon is predominantly driven by local insolationThe Australian summer monsoon is enhanced by remote forcing from northern Hemisphere low latitude and Southern Hemisphere high latitude [ABSTRACT FROM AUTHOR]

Abstract In the East Asian monsoon area, stalagmites generally record lower and higher oxygen isotope (δ18O) levels during warm humid interglacial and cold dry glacial periods, respectively. Here, we report unusually low stalagmite δ18O from the last glacial period (ca. 32.2–22.3 ka) in Fukugaguchi Cave, Niigata Prefecture, Japan, where a major moisture source is the East Asian winter monsoon (EAWM) that carries vapor from the warm surface of the Japan Sea. The δ18O profile of this stalagmite may imply millennial-scale changes, and high δ18O intervals that are related to Dansgaard–Oeschger (D–O) interstadials. More importantly, the stalagmite exhibits low overall δ18O values; the mean δ18O (− 8.87‰) is distinctly lower than the mid-Holocene mean of another stalagmite from the same cave (4.2–8.2 ka, − 7.64‰). An interpretation assuming a more intense EAWM and greater vapor transportation during the last glacial period, compared with the mid-Holocene, contradicts the limited inflow of the Tsushima Warm Current into the Japan Sea because of lowered sea level. Additionally, our model calculation using δ18O data from meteoric water indicated that the amount effect of winter meteoric water was insignificant (1.2‰/1000 mm). Low stalagmite δ18O for the last glacial period in Fukugaguchi Cave most likely resulted from 18O-depleted surface water, which developed in the isolated Japan Sea. The estimated amplitude of the δ18O decrease in surface water was ~ 3‰ at most, consistent with the abnormally low values for foraminifera (by ~ 2.5‰) in sediment during the last glacial period, shown by samples collected from the Japan Sea. This is the first terrestrial evidence of 18O depletion in Japan Sea surface water during the last glacial period.

Sea surface temperature (SST) in the Yellow Sea Warm Current (YSWC) pathway is sensitive to the East Asian Winter Monsoon (EAWM) and YSWC. However, the role of the YSWC in the evolution of regional SST remains unclear. Here, we present new U 37 k ′ based SST and grain size sequences spanning the last 6 092 years in the sediment core Z1, which was retrieved from the central Yellow Sea muddy area. Overall, U 37 k ′ -SST gradually increased since 6.1 ka BP, with a series of centennial-scale fluctuations. Its variation was mainly caused by EAWM when YSWC was weak between 6.1 and ∼3.9 ka BP, as shown by the end-member content of grain size. However, after YSWC was fully developed, i.e., since ∼3.9 ka BP, it exerted critical effects on SST evolution in its pathway. The 1 010, and 538-year cycles of the SST sequence indicated a basic control of solar activity on the oceanic conditions in the Yellow Sea. It is suggested that the variation of total solar irradiance was amplified by thermohaline circulation and then transmitted to the Yellow Sea through the EAWM. Meanwhile, the tropical Pacific signal of El Niño was transmitted to the YSWC through the Kuroshio Current. The dual properties of warm water transported by YSWC to compensate the EAWM and driving by Kuroshio Current closely linked the variation of SST in the YSWC pathway to the Northern Hemisphere high latitude climate and the tropical Pacific. These findings highlight the significance of YSWC on regional SST evolution and its teleconnection to high and low latitude forcing, which grains a better understanding of the long-term evolution of SST in the middle latitude Yellow Sea. [ABSTRACT FROM AUTHOR]

Future projection of diffusion conditions associated with extreme haze events over eastern China is of great importance to government emission regulations and public human health. Here, the diffusion conditions and their changes under future warming scenarios are examined. The relative strength of haze events in the Northern China Plain region increase from 150% during 2006–15 to 190% during 2090–99 under RCP8.5 scenarios, induced by a stronger and longer-lasting anticyclone anomaly in eastern China. The strengthened anticyclone anomaly is mainly induced by increased northern wave train convergence emanating from the Barents–Kara Sea, and the longer duration of the anticyclone anomaly is mainly induced by stronger local feedback that can extract more energy from the basic state to maintain the anticyclone anomaly in eastern China. Aerosol reduction is found to play a dominant role in strengthening the upstream wave train near the Barents–Kara Sea and the downstream anticyclone in eastern China, while the effects from increased greenhouse gases are small. The results of this study indicate that future aerosol emissions reduction can induce deteriorating diffusion conditions, suggesting more stringent regulations on aerosol emissions in China are needed to meet air quality standards.

Chinese loess provides the most detailed terrestrial records of paleoclimate changes. We employed the grain-size components of aeolian sediments to reconstruct the history of the East Asian winter monsoon (EAWM) on the Chinese Loess Plateau (CLP). Here, using the grain-size class vs. standard deviation method, we extracted the environmentally sensitive grain-size components of nine last glacial loess sections. The grain-size class vs. standard deviation diagrams showed two major grain-size components (fine and coarse), which varied from section to section. Material resource distances and post-depositional pedogenesis were the main factors affecting environmentally sensitive grain-size components. The coarse grain-size components of the Yulin, Baicaoyuan, Xifeng, and Luochuan sections were influenced by the transportation distance, while we attributed the fine grain-size components of the Weinan, Shaoling, Duanjiapo, and Chaona sections to pedogenesis. At the same time, the Mianchi section’s sensitive grain-size component was also coarse, and was affected by the local circulation from the nearby Yellow River terrace. Our comparison of sensitive grain-size components and EAWM revealed that the coarse grain-size components were progressively finer along with the EAWM from the northwest to the southeast on the CLP, and they can be regarded as the most suitable proxy indicator of the EAWM on the CLP.

This study examines the relationship between the Quasi‐Biennial Oscillation (QBO) and the variability of the East Asian winter monsoon (EAWM) in the Northern Hemisphere (NH) winter. Here, we consider the effects of QBO winds in the lower stratosphere at 70 hPa. It is found that during the period of 1958–2019, the EAWM in the early winter months (November–December) is weaker in the easterly phase of the QBO (EQBO) than in the westerly phase of the QBO (WQBO). During EQBO, the northerly monsoon flow is weakened, and anomalous warm temperatures occur over East Asia. Moreover, components of the EAWM circulation system, including the Siberian High, Aleutian Low, East Asian trough, and East Asian jet stream, are all weakened. Our further analysis suggests that the QBO may influence the EAWM directly via a subtropical pathway. The EQBO tends to weaken the East Asian jet stream and shift it poleward, and the changes in the East Asian jet stream lead to a weakened EAWM. The activities of planetary waves are also changed in association with the QBO. Examinations of individual zonal wavenumbers (WNs) of planetary waves in the SLP field reveal that WN 1 is strengthened while WNs 2 and 3 are weakened during EQBO. Specifically, the anomalous WN 2 leads to weakening of the Siberian High, Aleutian Low, and East Asian trough, and the anomalous WN 3 reduces the pressure gradient between the East Asia landmass and the western Pacific. The changes in WNs 2 and 3 associated with the QBO play a dominant role in anomalous EAWM. [ABSTRACT FROM AUTHOR]

The East Asian winter monsoon (EAWM) is one of the most important climate systems during boreal winter. It has a large meridional extent and provides a vital bridge between the mid‐to‐high latitudes and the tropics. This paper reviews the latest research on the climate variability of the EAWM, with particular emphasis on the associated processes of extratropical–tropical interaction. Some new results have been achieved in understanding the variation of the EAWM on interdecadal, interannual, and intraseasonal time scales, such as the interdecadal strengthening in the early 21st century, the unstable impact of El Niño–South Oscillation (ENSO) on the EAWM, and the intraseasonal strong cold events in East Asia. In addition, understanding of the extratropical–tropical interactions related to the EAWM has improved in several aspects, including the impacts of the EAWM on ENSO‐related climate effects, and the variation of regional Hadley circulation over the western Pacific and its climate impacts in the Asia–Australia region. Moreover, recent work has systematically evaluated the capacity of climate models to simulate the EAWM, including its climatology, interannual to interdecadal variations, and its relationship with ENSO. Finally, some scientific issues regarding our understanding of the EAWM are proposed for future investigation. [ABSTRACT FROM AUTHOR]

Traditionally, the Yellow Sea (YS) is believed to be well mixed throughout the water column or to experience significant temperature inversions in winter. Recently, we found a significant positive surface‐bottom temperature difference (SBTD) as large as 3.7°C in northeastern coastal waters of the Shandong Peninsula in the YS in winter. By analyzing 4 years (June 2016–September 2020) of online in situ observations, this study examined monthly and interannual variations in winter positive SBTD and the underlying dynamics. The winter positive SBTD generally formed in November, peaked in December/January, and disappeared in March. At the interannual time scale, this SBTD was strongest in 2018 and weakest in 2020. The underlying dynamics involved the combined effects of prevailing winter monsoon winds and resultant surface heat loss and current heat advection. When the surface northerly wind was strong, strengthened southward advection of cold air over the ocean cooled the water column intensely, whereas wind‐enhanced southward advection of warm surface water partly offset the sea surface cooling and resulted in surface temperature cooling that was considerably slower than bottom temperature or even surface temperature warming. These processes together generated strong positive SBTDs. When the surface northerly wind was weak, all of the above processes became weak and resulted in weak positive SBTDs. The relationship with Yellow River runoff was also discussed. This study enriches our knowledge of winter thermal structure in the YS. More observations and coupled physical‐biogeochemical simulations are needed to further clarify the impacts on climate and marine ecology. Plain Language Summary: Water temperature is an important physical attribute of the world's oceans. Its spatiotemporal variations at multiple scales are of vital importance in modulating a variety of processes in both the ocean and atmosphere, such as weather, climate, and marine ecosystems. Traditionally, the Yellow Sea is believed to be well mixed throughout the water column or to experience significant temperature inversions that have a higher temperature at a deeper depth in winter. However, we recently found a significant positive surface‐bottom temperature difference in northeastern coastal waters of the Shandong Peninsula in the Yellow Sea in winter. The positive surface‐bottom temperature difference could be as large as 3.7°C. In the present work, monthly and interannual variations in the positive surface‐bottom temperature difference in winter were investigated with 4 years of online in situ observations. Results indicated that winter positive surface‐bottom temperature differences occurred every year, generally formed in November, peaked in December/January, and disappeared in March. The underlying dynamics involved the combined effects of prevailing winter monsoon winds and resultant surface heat loss and current heat advection. This study enriches our knowledge of winter thermal structure in the Yellow Sea and is meaningful for mariculture activities in coastal waters of the Shandong Peninsula. Key Points: Winter positive surface‐bottom temperature differences were reported in northeastern coastal waters of the Shandong PeninsulaThere were significant monthly and interannual variations, peaking in December/January of each year and in 2018 during 2017–2020The underlying dynamics involved combined effects of prevailing winter monsoon winds and resultant surface heat loss and current advection [ABSTRACT FROM AUTHOR]

Although numerous studies have paid attention to the unstable relationship between the El Niño/Southern Oscillation (ENSO) and East Asian winter monsoon (EAWM), significant discrepancies have existed, especially regarding the modulation of the Pacific decadal oscillation (PDO) and Atlantic multidecadal oscillation (AMO). Here, we reexamine this issue by applying a new method that considers the changing relationship between ENSO and the spatial variations of the EAWM rather than a given EAWM index. We suggest a complicated spatial‐temporal variation in the ENSO‐EAWM relationship (EER), which consists of two major modes regulated by the PDO and AMO in distinct ways. In other words, the PDO and AMO modulate two different aspects of the decadal EER, which helps to clarify the disagreements among previous studies that are generally based on specific and regional EWAM indices. Plain Language Summary: The East Asian winter monsoon (EAWM) exert significant impacts on the Asian climate, affecting the livelihoods of billions of people, thus considerable efforts have been made to understand its dynamics and prediction. The effect of El Niño/Southern Oscillation (ENSO) has received great attention because it provides the most skillful predictability. Although it is well accepted that ENSO has a reversed relationship with the EAWM (i.e., El Niño corresponds to a weakened EAWM), recent studies reveals that such reversed ENSO‐EAWM relationship (EER) is unstable on decadal timescales, which could be attributed to the Pacific decadal oscillation (PDO) and Atlantic multidecadal oscillation (AMO). Nevertheless, significant discrepancies have existed among previous studies, especially regarding the modulation of PDO and AMO. Here, based on a new method that considers the changing role of ENSO in the EAWM spatial variations rather than a specific EAWM index, we conclude that the decadal variation in the EER shows great spatial inconsistency, which could be decomposed to two leading modes regulated by the PDO and AMO via distinct ways. This conclusion can deepen our comprehension of the EAWM dynamics and also help to explain the contradictions among existing studies that are generally based on regional EAWM indices. Key Points: The decadal variation in the ENSO‐East Asian winter monsoon relationship (EER) shows great spatial inconsistencyThe decadal variation in the EER comprises two major modes, which are modulated by the Pacific decadal oscillation and Atlantic multidecadal oscillation via distinct ways [ABSTRACT FROM AUTHOR]

The aeolian loess-paleosol sequences in the Chinese Loess Plateau (CLP) are an excellent archive of variations in atmospheric circulation in the geological past. However, there is no consensus regarding the roles of the East Asian winter monsoon and westerly winds in transporting the dust responsible for loess deposition during glacial and interstadial periods. We conducted detailed measurements of the anisotropy of magnetic susceptibility (AMS) on two parallel loess profiles covering the most recent 130 ka in the western CLP to determine paleowind directions. Results show that the magnetic lineations of the loess and paleosol units in both sections are significantly clustered along the northwest to southeast direction. These observations demonstrate that the prevailing wind system responsible for dust transport in the western CLP was the northwesterly winter monsoon, rather than the westerly winds. The AMS-derived dust-bearing wind direction was relatively stable during the last glacial and interglacial cycle in the western CLP, consistent with sedimentary and AMS evidence from the eastern CLP. Accordingly, it is reasonable to conclude that large areas of deserts and Gobi deserts areas located in the upwind direction were the dominant sources for the aeolian deposits of the Loess Plateau. [ABSTRACT FROM AUTHOR]