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Using the daily average temperature data of 125 national meteorological observation stations and NCAR/NCEP reanalysis data from 1961 to 2022, the main patterns of Asian circulation changes in winter and their impact on low-temperature events in Yunnan province were analyzed. The results show that there are two patterns of atmospheric circulation at 500 hPa in Asia during winter, namely zonal and meridional patterns, and the impact of the two patterns on low-temperature events in Yunnan province is significantly different. During the zonal circulation pattern, the stronger cold air flows directly southward from Lake Baikal to low latitudes, mainly affecting the eastern part of East Asia. The low-temperature events in Yunnan province also mainly occur in the eastern region. At this time, the low-temperature process is closely related to the strengthening of the Ural Mountains High and the Siberian High, as well as the wave trains at mid-to-high latitudes in Eurasia. During the meridional circulation pattern, the cold air flows southward along the eastern coast of the East Asian continent with the northerly airflow of the eastern side of the anomalous anticyclone in Lake Baikal, and moves southeast in the form of backflow in mid-to-low latitude areas. The activity is located southward and westward, which is beneficial for the low temperature of Yunnan province, the Tibet Plateau, and low latitude areas in Southeast Asia. At this time, the low-temperature events are mainly related to the changes in the subtropical wave train and the strengthening of positive surface level pressure (SLP) anomalies on the Tibet Plateau, but not closely related to the strengthening of High pressure in the Ural Mountain and the Siberian.

The Siberian High (SH) over central Asia can affect East Asian weather and climate, and its formation is primarily due to the uplift of the Tibetan and Mongolian Plateaus (TP and MP). However, it is unclear whether these plateaus can modulate the synoptic (2–7 days) evolution of the SH and the subsequent temperature over East Asia during the boreal winter. Using model simulations with and without the plateau topography north of the Himalaya, we show that the synoptic evolution of the winter SH is accompanied by an anomalous tropospheric transient wave train that migrates eastward to the MP over central Siberia before the SH intensification, which is then forced to propagate southeastward along the northeastern flank of the TP after the SH peaks. This results in subsequent cold anomalies from the north to the south of East Asia and thus increases synoptic variability of winter surface air temperature (Tas) over South China. However, the plateau uplift weakens this synoptic wave train due to the inefficiency of energy conversion from the mean flow to the transient flow, thus partly limiting the increase of the synoptic variability over South China. Further analyses showed that the synoptic evolution of the SH and its associated temperature anomalies is mainly caused and maintained by the anomalous cold advection due to the southeastward propagating northerly wind anomaly and the increased winter mean temperature gradient in the lower troposphere due to the northern plateau uplift. Our findings suggest that the TP and MP uplifts north of the Himalaya can affect both the winter mean state and synoptic-scale variability over East Asia and thus play a crucial role in the emergence of frequent cold air outbreaks from the higher latitudes toward South China. [ABSTRACT FROM AUTHOR]

Decadal variations in near‐surface wind speed (NSWS) and their causes are poorly understood. We found that the decadal transition of winter NSWS in northern China (NC) was 10 years earlier than in southern China (SC), which could be linked to the changes in intensities of the eastward wave‐activity flux and Siberian High (SH) induced by the Warm Arctic‐Cold Eurasia (WACE) dipole pattern. From 1973 to 1990, the WACE pattern from positive to negative phases confined the eastward wave trains to high latitudes with a decreasing SH, inducing an NSWS reduction. From 1991 to 2000, the WACE strengthened from negative to positive phases, causing a decadal transition in NSWS first in NC. After 2000, accompanied by the strengthening of the positive WACE, the eastward wave trains propagated downstream to lower latitudes, the SH and the meridional pressure gradient enhanced. Therefore, the transition of decadal NSWS occurred in SC until 2000. Plain Language Summary: Near‐surface wind speed (NSWS) is critical in exchanging energy, water, and momentum between the Earth's surface and the lower atmosphere. Previous studies have reported that the slowdown in NSWS and its reversal could be a manifestation of decadal variations in the climate system. However, the regional non‐synchronization of decadal variations in NSWS and the corresponding cause are poorly understood. This study reported a non‐synchronization of the decadal transition in winter NSWS between northern China (NC) and southern China (SC). The significant turning point of winter NSWS across NC was 10 years earlier than those across SC, and it was caused mainly by the zonal wind. The non‐synchronization of decadal variations in winter NSWS between NC and SC was linked to the Warm Arctic‐Cold Eurasia (WACE) atmospheric circulation pattern, and the Siberian High (SH) could serve as a bridge through which the WACE atmospheric circulation pattern influences the asynchronous transition of decadal NSWS between NC and SC. This study improves the understanding of decadal variations in NSWS across China. Key Points: The decadal near‐surface wind speed (NSWS) transition in winter over northern China (NC) was 10 years earlier than in southern China (SC)The non‐synchronization of the decadal transition in NSWS between NC and SC was linked with the Warm Arctic‐Cold Eurasia patternIntensities of wave‐activity flux and Siberian High influenced the non‐synchronization of decadal transition in NSWS between NC and SC [ABSTRACT FROM AUTHOR]

The Siberian High (SH) is one of the most prominent wintertime circulation systems in the Northern Hemisphere. The variability of the intensity of the SH during the boreal winter has been extensively studied, while the reasons behind its formation remain largely elusive. This study investigates the interannual variation and underlying mechanisms of the SH formation, especially the three-dimensional circulation and associated surface boundary conditions. Early SH formation is usually accompanied by a Eurasian teleconnection (EU)-like pattern and a strengthened subtropical westerly jet, and opposite conditions are true for a delayed SH formation. Boundary conditions, including North Atlantic sea surface temperature (NASST) anomalies and the high-latitude Central Eurasia snow-cover extent (HCESCE) anomalies could modulate SH formation by affecting the overlying atmospheric circulations. Specifically, anomalously cold NASSTs can result in an anomalous equivalent barotropic anticyclone via diabatic heating and transient eddy forcing. Such an anomalous anticyclone and related divergence anomalies in the upper troposphere act as effective atmospheric Rossby sources, triggering a downstream propagating atmospheric teleconnection with a pattern similar to that of a positive EU-like wave train, favoring the early formation of the SH. In addition, the reduced HCESCE warms the overlying atmosphere, thus weakening the atmospheric baroclinicity and transient eddy activities over the SH region. These weakened eddy activities can intensify the EU-like pattern via vorticity forcing and strengthen the subtropical westerly jet via the eddy–mean flow interaction. The processes for the impacts of the NASST and HCESCE anomalies on the formation of the SH can be verified by a series of numerical simulations. [ABSTRACT FROM AUTHOR]

The Siberian High (SibH), a prominent feature of the Northern Hemisphere atmospheric circulation, exhibited enhanced interdecadal variability since 1970, characterized by a sharp decline from 1970 to 1990 followed by a steep recovery from 1990 to 2010. The factors underpinning these variations are unclear. Using the CanESM5 large ensemble, including the single forcing simulations, we find that anthropogenic aerosols played an important role in influencing the above SibH trends on top of pronounced internally-generated variations. Changes in the SibH during both periods are embedded in aerosol-induced upper-tropospheric mid-latitude wave trains propagating from upstream regions, with subsequent downward propagation of the signal to the surface via three-dimensional dynamical adjustments. Further insights into the physical mechanisms using regional aerosol perturbation experiments with CESM1 reveal a dominant role of decreased North American aerosol emissions in driving the atmospheric wave train through interaction with the North Atlantic jet during the first period. In the second period, European aerosol emissions, characterized by a large and extensive decrease, are crucial to explain the SibH recovery. A better understanding of the factors driving multidecadal variability of the SibH, and in particular of the interplay between internal variability and external forcing, is critical to reducing uncertainties in future projections of regional extremes, such as cold surges, which can cause large social and economic impacts on densely populated East Asia.

The complex interaction between the Pacific decadal oscillation (PDO) and East Asian winter temperatures remains unclear. This study reveals that since the early 2000s, East Asia has experienced a strengthening of Aleutian low (AL) and Siberian high (SH) during negative PDO phases, leading to an intensified East Asian winter monsoon (EAWM). The increased pressure gradient between the SH and the AL, driven by warming in the western Pacific associated with the negative PDO phase, has significantly contributed to a shift toward cooling in East Asia (105°–150° E, 20°–50° N) since the early 2000s. Observations and model simulations provide evidence that the enhanced tropical convection in the western Pacific under a negative PDO phase has intensified the atmospheric circulations associated with the EAWM since the early 2000s. Understanding these dynamics is crucial for improving winter temperature forecasts in East Asia.

Yunnan plays a pivotal role in transmitting electricity from west to east within China's Southern Power Grid. During 7–13 January 2021, a large-scale continuous ice-covering event of ultra-high voltage (UHV) transmission lines occurred in the Qujing area of eastern Yunnan Province. Based on ERA5 reanalysis data and meteorological observation data of UHV transmission line icing in China's Southern Power Grid, the synoptic causes of the icing are comprehensively analyzed from various perspectives, including weather situations, vertical stratification of temperature and humidity, local meteorological elements, and atmospheric circulation indices. The results indicate a strong East Asian trough and a blocking high directing northern airflow southward ahead of the ridge. Cold air enters the Qujing area and combines with warm and moist air from the subtropical high pressure of 50–110° E. As warm and cold air masses form a quasi-stationary front over the northern mountainous area of Qujing due to topographic uplift, the mechanism of "supercooling and warm rain" caused by the "warm–cold" temperature profile structure leads to freezing rain events. Large-scale circulation indices in the Siberian High, East Asian Trough, and 50–110° E Subtropical High regions provided clear precursor signals within 0–2 days before the icing events. [ABSTRACT FROM AUTHOR]

The climatic warming-induced shrinking of permafrost currently encompasses 65% of alpine areas in North China, where a large population relies on its water and land resources. With increasing recognition of the economic and ecological impacts of permafrost basins, forecasts of environmental vulnerability have gained prominence. However, the links between permafrost and winter water resources remain inadequately explored, with most studies focusing on in-situ measurements related to snow cover and frozen layer thickness. Evaluating more complex phenomena, such as the magnitude and persistence of air temperature or low streamflow, depends on numerous climate-driven factors interacting through various subsurface flow mechanisms, basin drainage mechanics, and hydro-climatic correlations at a macroscale. The present study focuses on winter warming, flow increases, and their teleconnections in Xinjiang, China. The research analyzes their links to the atmospheric cycle of the Siberian High (SH) using long-term data spanning 55 years from two large alpine permafrost basins. Changes in variability and correlation persistence were explored for the past decades, and significant variability and connections were constructed using statistical correlation. The years 1980 and 1990 were a turning point when both winter temperatures and winter river flow began to exhibit a notable and consistent upward trend. Subsequently, the period from the mid-1990s to 2013 was characterized by high variability and persistence in these trends. The influence of the SH plays a dominant role in regard to both winter temperatures and river flow, and these variabilities and correlations can be utilized to estimate and predict winter flow in ungauged permafrost rivers in Xinjiang China. [ABSTRACT FROM AUTHOR]

Atmospheric rivers (ARs) that reach the complex terrain of High Mountain Asia (HMA) cause significant hydrological impacts for millions of people. While ARs are often associated with precipitation extremes and can cause floods and debris flows affecting populated communities, little is known about ARs that reach as far inland as HMA. This paper characterizes AR types and investigates dynamical mechanisms associated with the development of ARs that typically affect HMA. Combined empirical orthogonal function (cEOF) analysis using integrated water vapor transport (IVT) is applied to days where an AR reaches HMA. K-means cluster analysis applied to the first two principal components uncovered three subtypes of AR events with distinct synoptic characteristics during winter and spring months. The first subtype increases precipitation and IVT in Western HMA and is associated with a zonally oriented wave train propagating within the westerly jet waveguide. The second subtype is associated with enhanced southwesterly IVT, anomalous upper-level cyclonic circulation centered on 45 ∘ E, and precipitation in Northwestern HMA. The third subtype shows anomalous precipitation in Eastern HMA and southwesterly IVT across the Bay of Bengal. Interannual variations in the frequency of HMA ARs and relationships with various teleconnection patterns show that western HMA AR subtypes are sensitive to well-known remote large-scale climate factors, such as the El Niño Southern Oscillation, Arctic Oscillation, and the Siberian High. These results provide synoptic characterization of the three types of ARs that reach HMA and reveal the previously unexplored significance of their contribution to winter and spring precipitation.Supplementary informationThe online version contains supplementary material available at 10.1007/s00382-021-06008-z.

The sea surface temperature (SST) and ocean heat content in the Korea Waters are gradually increased. Especially the increasing trend of annual mean SST in the Korea Water is higher about 2.6 times than the global mean during past 55 years (1968–2022). Before 2010s, the increasing trend of SST was led by winter season in the Korea Waters. However, this pattern was clearly changed after 2010s. The increasing trend of SST during summer is higher about 3.9 times than during winter after 2010s. We examine the long-term variations of several ocean and climate factors to understand the reasons for the long-term pattern changes of SST between summer and winter in recent. Tsushima warm current was significantly strengthened in summer compare to winter during past 33 years (1986–2018). The long-term patterns of Siberian High and East Asian Winter Monsoon were definitely changed before and after early- or mid-2000s. The intensities of those two climate factors was changed to the increasing trend or weakened decreasing trend from the distinctive decreasing trend. In addition, the extreme weather condition like the heatwave days and cold spell days in the Korea significantly increased since mid- or late-2000s. From these results, we can consider that the occurrences of frequent and intensified marine heatwaves during summer and marine cold spells during winter in the Korea Waters might be related with the long-term pattern change of SST, which should be caused by the long-term change of climate factors and advection heat, in a few decade.

Subseasonal reversal of warm Arctic–cold Eurasia (SR‐WACE) pattern has significant impacts on transitions of weather and climate extremes in Eurasia. This study explored the performances of climate models to simulate the main features of SR‐WACE. For real‐time predictions, most of the state‐of‐the‐art climate models showed limited ability to accurately forecast SR‐WACE in advance. Furthermore, most of the historical simulations from Phase 6 of the Coupled Model Intercomparison Project (CMIP6) had also difficulties in well simulating the SR‐WACE. Further exploration showed that the simultaneous reversal of the Ural blocking high (UB) and Siberian high (SH) is the key atmospheric driver of the SR‐WACE occurrences, which were verified by both of the real‐time predictions and historical simulations. Our results implied that the simulation of SR‐WACE was a huge challenge and the critical solutions included improving simulation of subseasonal reversals of UB and SH in the atmosphere. Plain Language Summary: We explored the performances of climate models to simulate the main features of subseasonal reversal of warm Arctic–cold Eurasia (SR‐WACE) pattern. For real‐time predictions, most of the state‐of‐the‐art climate models showed limited ability to accurately forecast SR‐WACE in advance, which possibly restricted the subseasonal to seasonal forecasts skill of climate anomalies in mid‐low latitudes. Furthermore, the historical simulations from Phase 6 of the Coupled Model Intercomparison Project (CMIP6) had also difficulties in well simulating the SR‐WACE. The most of CMIP6 models only reproduce the SR‐WACE phenomenon with higher order modes and lower explained variances than observations. We further explored the atmospheric circulation associated with the SR‐WACE in CMIP6 models and found that when a strong reversal of the Ural blocking high and Siberian high (SH) is simultaneously simulated can a SR‐WACE occur. This result was also validated in real‐time prediction models. Therefore, the simulation of SR‐WACE was a huge challenge and the critical solutions included improving simulation of subseasonal reversals of UB and SH in the atmosphere. Key Points: Most of climate models had difficulties in well simulating the subseasonal reversal of warm Arctic–cold Eurasia (SR‐WACE) patternMost of CMIP6 models only reproduce the SR‐WACE phenomenon with higher order modes and lower explained variances than observationsThe simultaneous reversal of the Ural blocking high and Siberian high is key for simulating the SR‐WACE [ABSTRACT FROM AUTHOR]

Atmospheric mineral dust is a poorly constrained yet extremely important component of the climate system. Provenance studies from geologic dust archives are crucial to understand the drivers of the dust cycle over long time scales. Our multi‐technique provenance analysis of a rare Paleogene (35–27 Ma) eolian dust sequence from Ulantatal, ∼400 km northwest of the Chinese Loess Plateau (CLP), shows that Paleogene dust transporting winds generally varied between northwesterly and westerly, the same as those in the late Neogene‐Quaternary bipolar icehouse. We propose that, as today, westerly wind circulation patterns would have been modulated by an Arctic Oscillation (AO)‐like situation, and that the warm Eocene favored a long‐term negative phase of AO, leading to meridional westerly circulation and the dominance of a northwesterly dust transport pathway. After the Eocene‐Oligocene transition (EOT), long‐term positive phase of AO‐like conditions initiated, leading to stronger and more zonal westerlies. The Siberian High (SH) also formed or strengthened at the EOT and started to control dust storm activity along the northwesterly transport pathway. We argue that increased Paleogene Northern Hemisphere (NH) ice volume was the ultimate driver of this modern‐type dust transport regime in the Ulantatal region, possibly also controlling initial Ulantatal dust sequence formation via the development of the SH and modern‐type eolian regime. The similarity between the Ulantatal and late Neogene northern CLP dust provenance signals suggests that the increased NH ice volume, via its control on the northwesterly dust transport, could have promoted increased loess formation also in the late Miocene. Plain Language Summary: Understanding the effects and responses of atmospheric mineral dust to climate changes in the geologic past is crucial for predicting future scenarios. Analysis of the source of dust deposited 35–27 million years ago in Ulantatal, Inner Mongolia, China reveals that the Central‐East Asian atmospheric circulation during this time interval was similar to that of today. Specifically, dust transport was dominated by northwesterly and westerly winds despite a significantly warmer global climate. We also propose that Arctic Oscillation (AO)‐type conditions, stemming from the temperature difference between the high and low latitudes, modulated planetary westerly winds during this period. Our results suggest that during warmer phases, a negative AO type dominated and resulted in wave‐like westerly wind patterns and a northwesterly dust transport pathway to Ulantatal. During cooler phases, the westerly circulation became stronger and more zonal. The Siberian High pressure system was possibly strengthened during increased Northern Hemisphere (NH) ice volume and further affected northwesterly dust transport. Our findings suggest that NH ice volume increase was possibly also responsible for the formation of the Ulantatal dust sequence itself. Our results imply that even under significantly warmer conditions than today, polar ice affects the long‐term dustiness in this highly populated region. Key Points: The provenance of a Paleogene (35–27 Ma) eolian dust sequence in Ulantatal, Inner Mongolia, China, reveals a modern‐type eolian regimeGlobal cooling and possibly expansion of Northern Hemisphere ice volume modulated the dust provenance by strengthening the Siberian HighLong‐term negative (positive) phase of Arctic Oscillation‐like conditions were favored in the warmhouse Eocene (coolhouse Oligocene) [ABSTRACT FROM AUTHOR]

Severe rainfall during the recent northeast monsoon season (October, November and December) in 2021 caused unexpected disasters (triggered flooding and landslides) in the pilgrim city of Tirupati and the metropolitan city of Chennai over the peninsular of India (PI). The remote and regional influence of several ocean‐atmospheric climate indices on northeast monsoon rainfall (NEMR) during the OND season is investigated to understand the contributory mechanisms of extreme rainfall events over the PI during 2021. The interannual variability of NEMR and its relationship with the OND sea surface temperature (SST) anomaly over the Niño3.4 and Indian Ocean Dipole (IOD) regions are considered. In addition, SST anomalies over the Bay of Bengal (BoB), such as east BoB (EBoB), east equatorial Indian Ocean (EEIO) and their gradients (GSST) connections with NEMR, are also examined. The impact of Siberian High (SH), Western Pacific High (WPH), Arabian Sea Surface Pressure (ASSP), easterly waves (EW) and land surface temperature contrast (LSTC) is also analysed and incorporated to find a specific linkage with NEM 2021. The results show that excess NEMR during OND 2021 is suggestively associated with favourable large‐scale conditions like negative IOD and the La Niña phase over the Indo‐Pacific region. In November 2021, two deep depressions made landfall over Tamil Nadu (within the latitude of 11°–13°N) and over adjoining areas, which caused copious amounts of rainfall (maximum ~90 mm·day−1), leading to flooding conditions over Tirupati and Chennai. During the NEM season, abundant warming of BoB and weak vertical wind shear, along with negative anomalies of ASSP, modulated the cyclonic activities that enhanced the sufficient moisture transports from BoB to the PI. The MSLP anomalies over the ASSP region depict a significant correlation (−0.47) with the interannual variability of NEM as compared to SH and WPH during the OND season of 2021. [ABSTRACT FROM AUTHOR]

Increasing evidence has shown that marine heatwaves (MHWs) have destructive impacts on marine ecosystems, and understanding the causes of these events is beneficial for mitigating the associated adverse effects on the provision of ecosystem services. During the 2019/20 boreal winter, a long-lasting extreme MHW event was recorded (over 90 days) in the Yellow Sea (YS). Observations and numerical experiments revealed that the unprecedented winter MHW event was initiated and sustained by a significant decrease in ocean heat loss in the YS, which may be associated with the pronounced weakening of the Siberian high system induced by an extreme positive Arctic Oscillation (AO) event. A weakened northerly wind is the essential prerequisite, while the extreme AO event is only a trigger for the winter MHW in the YS. It was also found that the extreme winter MHW event is likely to substantially affect the seasonal evolution of the vertical thermal structure, which may have a great impact on the whole ecosystem in the YS. This study provides new insights for the prediction of winter MHWs in the YS, as well as their effects on marine ecosystems in a changing climate. [ABSTRACT FROM AUTHOR]

The Siberian High (SH), an important atmospheric system over Eurasia, exhibits notable seasonality—forming in autumn and peaking in the boreal winter. Many previous studies have revealed the characteristics of the SH in its peak phase; however, the SH formation process remains unclear. This study examined the climatological characteristics of SH formation with a cumulative sea-level-pressure series over the Siberian region based on observational data. First, the SH formation dates were objectively detected in both the climatology (October 1, 55th pentad) and individual years. Then, the thermodynamic processes around SH formation were investigated based on these formation dates. The results indicated that, in the lower troposphere, an anticyclonic circulation dominates over the Eurasian continent after SH formation. In the middle troposphere, an anomalous northeast–southwest-oriented ridge and trough appear over upstream of the SH and the coast of Northeast Asia, respectively. In the upper troposphere, the subtropical westerly jet, with its entrance located over the SH, intensifies and migrates southward, accompanying the amplification of its secondary circulation that features downward (upward) motion over Siberia (south of the Tibetan Plateau). The combined effects of the jet-associated circulation, negative vorticity advection and cold advection associated with the ridge and trough, and diabatic cooling contribute to high-level convergence and large-scale subsidence over the SH area, thereby resulting in SH formation. Further diagnosis reveals that dynamic processes play a more important role in SH formation than the thermal processes do. [ABSTRACT FROM AUTHOR]

The cold air outbreaks in the northern parts of India exert significant impacts on human health, energy, agriculture and transportation. In this study, we investigate the synoptic dynamics of cold waves and their linkages to large scale circulations for the winter period from 1982 to2020. Cold waves are classified into normal and intense (NCWs and ICWs) based on intensity and we examine the underlying mechanisms of formation and their atmospheric drivers. Notably, the spatial extent of the ICWs is almost double than that of normal ones thereby having the potential to affect a wider population. The NCWs are often influenced by western disturbances, leading to the inflow of cold air from Siberia (a region of shallow high). In contrast, ICWs are mostly linked to the presence of an omega block over the Ural-Siberian region. The downstream portion of the Ural block favours the inflow of cold northerlies into north India, leading to cold air advection and extreme cold wave conditions. The influence of Arctic warming for ICWs is further confirmed through a prominent Quasi-Resonant Amplification (QRA) fingerprint. Furthermore, La Niña condition seems to play a crucial role in triggering ICWs over north India. During La Niña, the prominent low level cyclonic anomaly helps in advecting the cold air from the higher latitudes into the country. The frequency as well as the duration of cold wave events are also found to be higher in La Niña years compared to El Niño and neutral years. The trend analysis of cold wave events over north India reveals a significant decrease in the frequency, duration and intensity during the analysis period due to a combination of various factors such as rising winter minimum temperatures (due to global warming), decreasing number of synoptic winter weather systems and Arctic amplification.

Abstract Atmospheric mineral dust is a poorly constrained yet extremely important component of the climate system. Provenance studies from geologic dust archives are crucial to understand the drivers of the dust cycle over long time scales. Our multi‐technique provenance analysis of a rare Paleogene (35–27 Ma) eolian dust sequence from Ulantatal, ∼400 km northwest of the Chinese Loess Plateau (CLP), shows that Paleogene dust transporting winds generally varied between northwesterly and westerly, the same as those in the late Neogene‐Quaternary bipolar icehouse. We propose that, as today, westerly wind circulation patterns would have been modulated by an Arctic Oscillation (AO)‐like situation, and that the warm Eocene favored a long‐term negative phase of AO, leading to meridional westerly circulation and the dominance of a northwesterly dust transport pathway. After the Eocene‐Oligocene transition (EOT), long‐term positive phase of AO‐like conditions initiated, leading to stronger and more zonal westerlies. The Siberian High (SH) also formed or strengthened at the EOT and started to control dust storm activity along the northwesterly transport pathway. We argue that increased Paleogene Northern Hemisphere (NH) ice volume was the ultimate driver of this modern‐type dust transport regime in the Ulantatal region, possibly also controlling initial Ulantatal dust sequence formation via the development of the SH and modern‐type eolian regime. The similarity between the Ulantatal and late Neogene northern CLP dust provenance signals suggests that the increased NH ice volume, via its control on the northwesterly dust transport, could have promoted increased loess formation also in the late Miocene.

The aeolian activity in central Asia (CA)and its relevant dust emissions significantly influenced the global climate changes and biogeochemical cycles. Fully understanding the formation processes and mechanism of aeolian activity in CA is helpful to elevate our knowledge of global climate change, materials cycles and aeolian disasters monitoring and prevention. However, this issue is still controversial at present. We systematically review and integrate the geological archives and instrumental data to trace the variations of aeolian activity on sub-orbital, centennial, and decadal timescales in CA, and assessed the relationship between aeolian activity changes and climate changes, atmospheric circulation system changes and human activities. The result suggested that on the sub-orbital scale, during the past 8500 years, the low intensity and relatively stable aeolian activity occurred during the early to middle Holocene (8500-4000 Cal. Yr B.P.), followed by a more intensive/frequent and more variable aeolian activity conditions during late Holocene (4000-0 Cal. Yr B.P.). On centennial scale, over the past 1000 years, the more intensive (attenuated)aeolian activity occurred during the Little Ice Age (Medieval Warm Period). On the decadal scale, during the last century, aeolian activity in CA has decreased greatly since the 1960s, accompanied by the increasing of temperature and precipitation. Compared to the changes of climate, atmospheric circulation system and human activities, we proposed that the Siberian High (SH) which related to the temperature variations, rather than the precipitation and human activity, largely controlled aeolian activity in CA on the sub-orbital, centennial, and decadal timescales. Cooling at high latitudes markedly enhances the intensity of the SH, which is displaced southward as a result, causing the incursion of cold air masses from high latitudes which result in more robust wind regimes that provide suitable wind regimes for dust emission the study area. [ABSTRACT FROM AUTHOR]

The effect of future Arctic amplification (AA) on the extratropical atmospheric circulation remains unclear in modeling studies. Using a collection of coordinated atmospheric and coupled global climate model perturbation experiments, we find an emergent relationship between the high-latitude 1,000–500 hPa thickness response and an enhancement of the Siberian High in winter. This wave number-1-like sea level pressure anomaly pattern is linked to an equatorward shift of the eddy-driven jet and a dynamical cooling response in eastern Asia. Additional simulations, where AA is imposed directly into the model domain by nudging, demonstrate how the sea ice forcing is insufficient by itself to capture the vertical extent of the warming and by extension the amplitude of the response in the Siberian High. This study demonstrates the importance of the vertical extent of the tropospheric warming over the polar cap in revealing the “warm Arctic, cold Siberia” anomaly pattern in future projections.

To reveal the main characteristics of winter temperature change in Yunnan and the key circulation factors affecting on it， the winter temperature variation is first investigated by using monthly mean temperature data of 124 meteorological observation stations in Yunnan， NCEP / NCAR reanalysis data， some atmospheric teleconnection indices and atmospheric circulation characteristic indices provided by CPC （Climate Prediction Center） and NCC （National Climate Center）.The results show that the annual variability of winter temperature is more obvious in the East than that in the West.There are four dominant EOF patterns of winter temperature in Yunnan， i.e.the whole regional consistent pattern， the East-West difference pattern， the meridional triple-like pattern and the northwest-southeast difference pattern.The four dominant patterns account for 90% of the EOF total variance contribution.The interannual changes of the first three patterns show a significant linear trend， but the fourth pattern mainly shows interdecadal fluctuation characteristics.It is found that the situation and trends of wave train in mid-high latitude regions is obvious different corresponding to different temperature patterns.The geopotential height in four key areas related to the anomalous wave trains in mid-high latitude regions at 500 hPa， as well as the atmospheric circulation anomalies in low-high level in the Bay of Bengal（BOB）， have a very important impact on the temperature patterns.The first EOF pattern is closely related to geopotential height difference between in the southern （20°N -30°N， 90°E -120°E） and Northern （45°N -60°N， 90°E -120°E） East Asia.When the geopotential height is low in Southern and high in Northern， the temperature is uniform warming， and vice versa.The second pattern is related to the zonal wave trains in the mid-high latitude regions.When the geopotential height from East Asia to Northwest Pacific region （15°N -25°N， 80°E -100°E） is high （low）， there is a cyclone（anticyclone） occur in 700 hPa in the northern BOB （15°N -25°N， 80°E -100°E）， 300 hPa Uwnd-shear-300 index in Southeast Asia is higher （less） than zero， which is conducive to the cold Western and warm Eastern （warm Western and clod Eastern）.The third pattern is related to the northwest-southeast wave train in the middle and high latitude regions.The geopotential height in plateau area （30°N -50°N， 80°E -110°E） is high （low）， which is conducive to the meridional triple-like pattern， with warm-cold-warm （cold-war-cold） from West to East of Yunnan.The fourth pattern is mainly affected by the changes of local circulation in BOB.The correlation between EOF time coefficients and atmospheric teleconnection indices and key circulation system indices further shows the important role of circulation wave train in mid-high latitude regions.At the same time， it also shows that the change of geopotential height in Plateau is one of the important factors affecting the temperature in winter in Yunnan.

In this study, we compared two anomalous wet February periods in 2021 and 2022 in China. The same anomalies appeared in the spatial distribution of precipitation, with anomalous precipitation centered over the southeast coast. However, temperature discrepancies appeared in most of China, with anomalously high temperatures in 2021 and lower temperatures in 2022. Both instances of increased precipitation were attributed to warm and moist advection from the south, with transport in 2021 being partly enhanced by the South China Sea cyclone, whereas transport in 2022 was mainly due to the subtropical western North Pacific anticyclone. Therefore, in this study, we aimed to compare and analyze temperature and precipitation anomalies in February 2021 and 2022 using the self-organizing map method. Warm events in East Asia and cold events in Siberia and the Tibetan Plateau types were obtained by mode 1, which contained 2021. Mode 6 exhibited opposite warm types in Siberia and cold types in southern Asia, including February temperature and precipitation anomalies in 2022. Based on the results of this study, we can conclude that precipitation anomalies in February 2021 and 2022 occurred under different temperature and circulation anomalies, and both were influenced by La Niña events. Autumn sea ice loss in the Barents Sea contributed significantly to warm and rainy events in February 2021. However, the cold and rainy events of February 2022 were closely related to the strengthening of the Siberian High. [ABSTRACT FROM AUTHOR]

In early November 2021, China experienced its second strongest cold wave event during 1981–2021. Although the Siberian high is considered the main factor influencing cold wave events in East Asia, it was not extremely strong from 4 to November 9, 2021. The spatial distribution of the correlation coefficients between the sea level pressure and the daily temperature anomalies shows a monopole pattern, with a notable negative centre in the southern part of the Siberian high monitoring domain. However, the correlation between the sea level pressure and temperature drop presents a typical dipole pattern, with a distinct negative centre in the northern monitoring domain and a positive centre in southern East Asia. During the November 2021 super cold wave process, the sea level pressure anomalies display a dipole pattern with a higher centre in the north and a lower centre in the south owing to the northward shift of the Intertropical Convergence Zone. The meridional pressure gradient index clearly reveals the non-negligible effect of subtropical low-pressure on this super cold wave process, indicating its possibly essential supplementary role in enhancing this process. The above findings provide a new understanding of its mechanism and long-range forecasts.

This study analyses the spring climate anomalies under different configurations of western North Pacific anticyclone (WNPA) and Siberian high (SH). Compared to the WNPA alone with increased precipitation over southern China, the out‐of‐phase configuration (strong‐WNPA–weak‐SH) can enhance the WNPA‐related southwesterlies over eastern China, favouring increased precipitation with larger amplitude over southern China and southern Northeast China. Differently, the in‐phase configuration (strong‐WNPA–strong‐SH) decreases and confines WNPA‐related southwesterlies over southern China, causing decreased precipitation over eastern Southwest China; additionally, the WNPA‐related southwesterlies converge with SH‐related northwesterlies over the lower reaches of the Yangtze River, causing increased precipitation there. For surface air temperature, the WNPA alone induces warming over western Southwest China through changing heat flux, while the SH alone induces cooling over northern China through changing temperature advection, and over Northwest and southern China through changing heat flux. In the out‐of‐phase configuration, warming expands into Northern China due to the cooperation of weakening SH. In the in‐phase configuration, SH‐related cooling mainly occurs to the north of the Yangtze River because of the obstruction of WNPA. Further analysis indicates the eastern Pacific (EP) and central Pacific (CP) El Niño‐Southern Oscillation (ENSO), European low and Ural high contribute to the different configurations of WNPA and SH. The EP ENSO‐related zonal overturning circulation intensifies the WNPA and European low‐induced warm advection weakens the SH, resulting in the out‐of‐phase configuration. The CP ENSO‐related zonal overturning circulation intensifies the WNPA with a northeast–southwest tilt and Ural high‐induced cold advection intensifies SH, resulting in the in‐phase configuration. [ABSTRACT FROM AUTHOR]

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Copyright of Plateau Meteorology is the property of Plateau Meteorology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Two late Holocene cold events were described for the Southern Russian Far East: 2800–2600 year BP and the Little Ice Age (LIA) (~1300–1850 CE). The synthesis is based on multi-proxy records on profile "the mainland (Primorye)-islands (Sakhalin-Kurils)". Main archives are sediments of small lakes and peat bogs that recorded the high-resolution environmental changes. The temporal resolution of reconstructions here is up to 26–40 years. During the cold event of 2800–2600 year BP, the humidity decreased sharply, there were long-term dry seasons without strong floods, and buried soil formed on floodplains. The LIA was wet in the mainland and the Kurils, with frequent strong floods, but was drier in Sakhalin. The cooling was characterized by sharp temperature fluctuations where high moisture conditions alternated with short-term drier periods. The shift in geographical position and intensity of the main centers of atmospheric action caused a paleoclimatic interpretation of these events (Aleutian Low, Siberian and North Pacific Highs, the summer Okhotsk anticyclone and the Far East depression). Changes in the North Pacific oscillations played an important role in the alternation of cold-dry and cold-wet periods. Anomalies in the intensity of El Niño and the monsoon system led to changes in tropical and extratropical cyclone trajectories and cyclogenesis in general. [ABSTRACT FROM AUTHOR]

The spatiotemporal variations in the frequency of rail breakage (FRB) in the high-speed railway of the Beijing–Tianjin–Hebei (BTH) region and its relationship with atmospheric circulation anomalies and surface temperature are analyzed in this study, based on the monthly FRB data of BTH region and the ERA5 reanalysis data from 2010 to 2020. The frequency of rail breaking in the BTH region varies significantly depending on the season, with winter having the highest incidence. In fact, more than 60% of the total FRB in the BTH region occur during the winter season. Both the annual total and winter FRB in BTH region are very unevenly distributed in time and space, and both are relatively similar in spatial distribution patterns. The FRB in Beijing railway section is the most frequent, followed by Tianjin, and the lowest frequency is observed in Chengde. It is found that the increasing winter FRB in BTH region and the intensified Siberian high are related. When the Siberian high is strong, the East Asian winter monsoon and the East Asian Trough in the middle troposphere could be enhanced through atmospheric teleconnection, which is conducive to the cold air advection from northern high latitudes to the BTH region, resulting in an abnormally cold winter in BTH region, thus providing low temperatures for broken rails on high-speed railways, and vice versa. The research results might provide a scientific basis for monitoring and predicting the broken rails in BTH high-speed railway during winter, thereby providing a guarantee for the safe operation of the high-speed railway. [ABSTRACT FROM AUTHOR]

The topography of the Tianshan Mountains and the Pamir Plateau strongly shapes the seasonality of precipitation in Central Asia (CA): cold-season (October-April) precipitation dominates western CA and warm-season (May-September) precipitation dominates eastern CA. The precipitation/moisture patterns between western and eastern CA are completely opposite at seasonal, decadal and centennial scale. However, the pattern contrasts for millennial or longer time scales remain unknown. In this study, we investigated the precipitation variations in western CA, as recorded in a 6.5-m loess section in southern Kazakhstan, which has accumulated since ~14.4 ka. According to the robust relationship between the surface soil organic matter δ13C and the climatic parameters, the δ13C signature is here considered as a precipitation proxy. The record reveals an overall decreasing precipitation before ~6.0 ka followed by an increasing trend afterward, being consistent with the previously reported precipitation records in western CA. The late-deglaciation precipitation in western CA is in phase with that in eastern CA at millennial scales, which are both driven by the North Atlantic Oscillation (NAO) and the Siberian High. [ABSTRACT FROM AUTHOR]

Influence of the Siberian High longitudinal position on cyclonic activity over the Far Eastern Seas and the Pacific Ocean in winter, spring and summer is considered. Eastward shift of this atmospheric center causes general decreasing of number of cyclones over the region, but their intensity increases; on the contrary: cyclones are more frequent but weaker when the Siberian High is located in western position. The Siberian High, being a winter center, cannot influence directly on spring and summer cyclones, but it influences on formation of the Far Eastern Low, which intensity correlates with number and intensity of spring and summer cyclones.

Arid Central Asia (ACA) is a major dust source region in the Northern Hemisphere, owing to the prevalence of aeolian activity that substantially impacts the ecological environment and human wellbeing in this region. However, the driving mechanisms of aeolian activity in ACA during the Holocene are unclear, making it difficult to predict possible future aeolian activity. We used AMS 14C dating, combined with grain-size analysis, high-resolution X-ray fluorescence scanning, and scanning electron microscopy of a sediment core from Lake Ailike, in the Junggar Basin, to reconstruct the history of aeolian activity in ACA during the Holocene. We found that periods of increased aeolian activity on the millennial-scale are correlated with the strengthening of the Siberian High, and that there is a consistency between aeolian activity and climatic fluctuations in the mid-latitudes of Europe. These findings support a close relationship between climate fluctuations in mid- and high-latitude regions of the Northern Hemisphere. Lower/higher temperatures in high latitudes result in the expansion/contraction of polar air masses, leading to the strengthening/weakening of the Siberian High. Additionally, more/less frequent aeolian activity in ACA corresponded to cooling/warming trends in the mid-latitudes of Europe during the Holocene. While ongoing global warming may lead to a long-term decrease in aeolian activity in ACA, the weakening of the polar vortex has resulted in more frequent cold waves affecting the mid-latitudes of Eurasia during winter in recent years. • Aeolian activity in arid Central Asia is linked to the Siberian High. • Fluctuations in mid-latitude climate are correlated with the Siberian High. • A strong climatic correlation exists between middle and high latitudes. [ABSTRACT FROM AUTHOR]

Eolian activity determines the magnitude of dust emission. However, geological records of eolian activity are scarce due to strong wind erosion in the dust source areas. Northern Xinjiang is recognized as a major dust source region in arid central Asia. Here we present a lacustrine record of eolian activity over the past 1600 years from Jili Lake, in northern Xinjiang, which acts a natural trap for airborne materials. Based on the stratigraphic variability of two sedimentary sequences and 20 radiocarbon dates, we infer that Jili Lake initially developed in the southwestern part of the lake basin during the mid-Holocene and then expanded to close to its modern surface area until 1600 years ago. Grain-size analyses of materials from different parts of the lake sedimentary system, including lake surface sediments, lake catchment deposits, and airborne sand and dust collected from near the lakeshore, demonstrate that the coarse silt and fine sand fraction (40–200 μm) of the lake sediments was transported primarily by strong winds and can be regarded as an indicator of changes in eolian activity. We argue that wind strength played an important role in lifting and transporting the coarse particles, although an arid climate cannot be entirely excluded out as a factor favoring eolian activity. The most intensive eolian activity occurred from ∼910 to 1300 AD, roughly corresponding to the Medieval Warm Period (MWP), whereas eolian activity was weak during the Little Ice Age (LIA, ∼1300 to 1760 AD). However, this pattern is inconsistent with other dust records from central Asia. Eolian dust activity reflects the coupling of dust-generating windstorms and dust source areas which were swept by cold air surges. The spatial differentiation of eolian dust activity in arid central Asia may thus be causally linked to the intensity and extent of the Siberian High (SH), given that intense cyclogenesis always occurs on the southwestern periphery of the SH in springtime. Changes in the SH can be further ascribed to atmospheric circulation modulated by phase alternations of the North Atlantic Oscillation (NAO) due to large-scale thermal contrasts. Our results suggest that the dynamics of Asian dust emission are closely linked with the spatial variability of the SH. Nonetheless, more records of eolian activity are needed to further elucidate the forcing mechanisms of dust entrainment in the source area of Asian dust. [ABSTRACT FROM AUTHOR]

Interdecadal change in the relationship between the winter Siberian high (SH) and tropical cyclone genesis frequency (TCGF) is investigated using observational and reanalysis data. Focus is on the Western North Pacific (WNP) where environmental background associated with TCGF is closely related to the winter SH. It is demonstrated that the relationship presents clear interdecadal change during 1980–2020. A significant negative correlation dominates in the last two decades of the 20th century (P1), but it clearly weakens from the early 2000s onward (P2). Observational evidence shows that such interdecadal change is related dominantly to variations in the air–sea responses associated with the winter SH over the North Pacific. During P1, when the SH is anomalously strengthened, an Aleutian Low (AL) response occurs over the downstream North Pacific, which gradually develops into a meridional dipole distribution pattern consistent with the negative North Pacific Oscillation (NPO) mode during the following spring. The northeasterly wind anomaly over the subtropical North Pacific maintains and further delivers into the tropical Pacific. It favors easterly wind anomaly enhancement over the tropical Pacific around summer and grows into an anticyclonic circulation response in the WNP, which restrains the genesis of TCs. During P2, the eastward shift of the SH anomaly favors a weak AL over the Northeast Pacific followed by a northeastward-shifted anticyclone over the subtropical central-eastern Pacific, which confines the relatively weak northeasterly wind anomalies far away from the tropical Pacific. This was concurrent with a weakening relationship between the SH and WNP TCGF, indicating weaker downstream impacts of the winter SH. [ABSTRACT FROM AUTHOR]

[Display omitted] • The first overview of the loess-based atmospheric dust dynamics in Central Asia. • Scenarios of dust activity are different in northern and southern Central Asia. • We provide a clearer boundary regarding aeolian dynamic systems in Central Asia. Different origins of loess deposits in northern and southern Central Asia are not only associated with Central Asian topography, but also with aeolian dust dynamics. However, the latter has received far less attention so far. This review focuses on atmospheric dust dynamics for loess deposition in Central Asia, aiming to heal this knowledge gap. Comparisons of loess grain size data from the Chinese Loess Plateau, and the northern and southern Central Asia suggested that the Siberian High-pressure system largely controlled dust mobilization and loess accumulation in northern Central Asia, instead of southern Central Asia. The North Atlantic Oscillation (NAO) mode also provided an additional promising solution to trigger of loess accumulation in the North Tianshan Mountains. In southern Central Asia, intensity of dust activity was majorly determined by the Caspian Sea-Hindu Kush Index (CasHKI), with stronger dust dynamics under higher CasHKI modes. However, the causes of variations in the CasHKI intensity represent a future challenge. The CasHKI values also influenced the wind dynamics controlling dust mobilization in the Fergana Valley. Therefore, the Central Asia can be divided into two parts regarding the aeolian dust dynamics, with a boundary located in the North Tianshan Mountains and the south of Aral Sea. The Siberian High and NAO phase appeared to affect the dust activity and loess accumulation in the northern part; while dust entrainment and deposition were mostly determined by the CasHKI mode in the southern part. However, precisely determining the boundary highlights the necessity of investigations on loess deposits in the Tashkent region. In addition, we further recommend that the dynamic linkages between the mid-latitude Westerlies and aeolian loess deposition constitute a future critical research topic in Central Asia. [ABSTRACT FROM AUTHOR]

Eastern Central Asia has an arid environment and experiences frequent dust storms. Modern observations indicate that the dust storm frequency in eastern Central Asia is modulated mainly by the intensity of the Siberian High (SH). However, a lack of knowledge about the process influencing the variation of the SH limits our ability to understand the genesis of dust storms and their predictions. In this study, we present data on heavy mineral assemblages and sediment grain size in a loess section in eastern Central Asia, spanning the last glacial. Combined with previously published results, we propose that the sorting coefficient in loess‐paleosol sequences is a more sensitive proxy for wind intensity—and thus for the intensity of the SH—than the commonly used proxies of the mean grain size and grain size fractions, which are also influenced by changes in dust source and vegetation cover. Our sorting coefficient series clearly reveals Heinrich events, as well as the prominent ∼5 kyr Bond cycle. Larger sorting coefficients correspond to more depleted Sanbao Cave stalagmite δ18O values, revealing an antiphase relationship between the intensity of the SH and the East Asian Summer Monsoon during the last glacial. The sorting coefficient series also support the significant influence of Arctic sea‐ice cover on the intensity of the SH. Plain Language Summary: Central Asia is characterized by an arid environment. Dust storms occur frequently in Central Asia. Modern observations indicate that the frequency of dust storms in eastern Central Asia is mainly related to the near‐surface wind intensity, which is modulated by the Siberian High (SH). Therefore, understanding the change process of the SH intensity and its driving mechanism is helpful to effectively predict dust storms in the future. Bulk grain size proxies, such as mean/median grain size or grain size fraction, are usually used to reflect changes in the intensity of the SH, but they will also be affected by other factors such as vegetation coverage and dust provenance. In this study, we first theoretically discuss the potential of sorting coefficient as an indicator of near‐surface wind intensity. The sorting coefficient is then applied to a Central Asian loess section to infer the variation of the SH intensity. In contrast to commonly used mean grain size, sorting coefficients not only clearly reveal Heinrich events but also demonstrate very strong ∼5 kyr cycles, known as the "Bond Cycle". Larger sorting coefficient corresponding to more depleted Sanbao cave stalagmite δ18O values indicates an antiphase relationship between the SH and East Asian Summer Monsoon during the last glacial. Key Points: Sorting coefficient is a more sensitive proxy for wind intensity than commonly used proxies of mean grain size and grain size fractionAntiphase relationship between the Siberian High (SH) and East Asian Summer Monsoon during the last glacialOur results support the great influence of the extent of Arctic sea ice on the intensity of the SH [ABSTRACT FROM AUTHOR]

Loess contributes considerably to understanding the interactions between dust cycles and climate change. However, systematic and regional‐scale reconstructions of variations in the dust mass accumulation rate (MAR) using Central Asian loess are lacking. Based on the high‐resolution luminescence dating of 10 loess sections, we present a stacked suborbital‐scale (multi‐millennial‐scale herein) dust MAR record over the past 30 ka in the eastern Yili Basin, Central Asia, which shows obvious advantages at representing basin‐scale dust accumulation changes when compared with that based on individual sites. The stacked results in the eastern Yili Basin indicate that the MAR level remained high during the Last Glacial Maximum, followed by a dramatically decreasing trend throughout the last deglaciation, and exhibited a slight decrease during the early Holocene and early middle Holocene, followed by a clear increasing trend toward the late Holocene. We propose that changes in the Siberian High intensity dominantly modulated the aforementioned MAR variations. These results effectively link dust accumulation to the Siberian High, imply a possibly weakened dust activity in the Yili Basin at a long‐term scale under future global warming scenarios, and also provide a significant reference for dust accumulation reconstruction in other basins in Central Asia. Plain Language Summary: Aeolian‐formed loess can be used to represent past dust activities (source, transport, and deposition), which interact with paleoclimate change. Although loess is widely distributed in Central Asia, regional‐scale and systematic reconstruction of changes in the dust mass accumulation rate (MAR) using Central Asian loess is lacking. In this study, based on the high‐resolution luminescence dating of 10 loess sections, we reconstruct variations in the stacked MAR over the past 30 ka in the eastern Yili Basin, Central Asia, which represents basin‐scale dust accumulation. The results indicate four suborbital‐scale phases in MARs, including the relatively high Last Glacial Maximum, the dramatically decreasing last deglaciation, the slightly decreasing early Holocene and early middle Holocene, and the obviously increasing late middle Holocene and late Holocene. We attribute the aforementioned MAR variations to changes in the Siberian High intensity. This study implies that dust activity in the Yili Basin will possibly be weakened at a long‐term scale under future global warming scenarios, and it is also significant for geological dust accumulation reconstruction in other basins in Central Asia. Key Points: A stacked dust mass accumulation rate record over the past 30 ka was constructed based on loess in the eastern Yili Basin, Central AsiaThe stacked dust record represents basin‐scale, suborbital‐scale dust accumulation, in contrast to that from individual sitesThe Siberian High is proposed to have been mainly responsible for basin‐scale, suborbital‐scale variations in the mass accumulation rates [ABSTRACT FROM AUTHOR]

An unprecedented cold wave intruded into East Asia in early January 2021 and led to record-breaking or historical extreme low temperatures over vast regions. This study shows that a major stratospheric sudden warming (SSW) event at the beginning of January 2021 exerted an important influence on this cold wave. The major SSW event occurred on 2 January 2021 and subsequently led to the displacement of the stratospheric polar vortex to the East Asian side. Moreover, the SSW event induced the stratospheric warming signal to propagate downward to the mid-to-lower troposphere, which not only enhanced the blocking in the Urals–Siberia region and the negative phase of the Arctic Oscillation, but also shifted the tropospheric polar vortex off the pole. The displaced tropospheric polar vortex, Ural blocking, and another downstream blocking ridge over western North America formed a distinct inverted omega-shaped circulation pattern (IOCP) in the East Asia–North Pacific sector. This IOCP was the most direct and impactful atmospheric pattern causing the cold wave in East Asia. The IOCP triggered a meridional cell with an upward branch in East Asia and a downward branch in Siberia. The meridional cell intensified the Siberian high and low-level northerly winds, which also favored the invasion of the cold wave into East Asia. Hence, the SSW event and tropospheric circulations such as the IOCP, negative phase of Arctic Oscillation, Ural blocking, enhanced Siberian high, and eastward propagation of Rossby wave eventually induced the outbreak of an unprecedented cold wave in East Asia in early January 2021. [ABSTRACT FROM AUTHOR]

Two supercold waves straddling 2020 and 2021 successively hit China and caused record-breaking extremely low temperatures. In this study, the distinct features of these two supercold waves are analyzed on the medium-range time scale. The blocking pattern from the Kara Sea to Lake Baikal characterized the first cold wave, while the large-scale tilted ridge and trough over the Asian continent featured the second cold wave. Prior to the cold waves, both the northwest and hyperpolar paths of cold air contributed to a zonally extensive cold air accumulation in the key region of Siberia. This might be the primary reason why strong and extensive supercold waves occur even under the Arctic amplification background. The two cold waves straddling 2020 and 2021 exhibited distinct features: (1) the blocking circulation occurred to the north or the east of the Ural Mountains and was not confined only to the Ural Mountains as it was for the earlier cold waves; (2) the collocation of the Asian blocking pattern and the polar vortex deflection towards East Asia preferred the hyperpolar path of cold air accumulation and the subsequent southward outburst; and (3) both high- and low-frequency processes worked in concert, leading to the very intense cold waves. The cold air advance along the northwest path, which coincides with the southeastward intrusion of the Siberian High (SH) front edge, is associated with the high-frequency process, while the cold air movement along the hyperpolar path, which is close to the eastern edge of the SH, is controlled by the low-frequency process. [ABSTRACT FROM AUTHOR]

This study investigates the large-scale circulation anomalies of strong and weak cold surges in southern China. Results show that the strong and weak surges are associated with a distinct Rossby wave train across Eurasia projecting onto the Scandinavia (SCAND) and Eurasian (EU) patterns. On one hand, the strong surge is preceded by a positive SCAND pattern and a transition of the EU pattern from its negative to positive phase. The corresponding wave train propagates southeastward from East Asia to the North Pacific. This is associated with a strong intensification of the Siberian high, a deepened East Asian trough, and a sharp meridional pressure gradient between northern and southern China; these advect intense cold air masses from Siberia to southern China. On the other hand, the weak surge is preceded by a negative SCAND pattern and a positive EU pattern. The corresponding wave train does not propagate from East Asia to the North Pacific. This wave train has a weak impact on the East Asian winter monsoon circulation and corresponds to weak cold air advections towards southern China. Overall, the intra-seasonal variation of the Eurasian teleconnection patterns is crucial for a comprehensive understanding of the cold surge in southern China.

Siberian High (SH) is the dominant pressure system located in the mid-high latitudes of Eurasia during boreal wintertime. This study reveals a triggering impact of SH variation in preceding winter on the following ENSO events, and gives a possible explanation via diagnosing the SH-associated air-sea response over the tropical Pacific and North Pacific. When SH is anomalously enhanced (suppressed) during boreal winter, an Aleutian Low enhanced (suppressed) response will occur over the downstream North Pacific. The Aleutian Low response gradually evolves into a meridional dipole structure similar to the negative (positive) phase of the North Pacific Oscillation (NPO) during the following spring and early summer. Correspondingly, the oceanic response in the North Pacific features a pattern similar to the negative (positive) phase of the Victoria mode. These SH-associated air-sea responses over the subtropical North Pacific will be maintained and further delivered into the tropical Pacific through the so-called seasonal footprinting mechanism, which favors the Bjerknes feedback established around boreal summer and finally grows into a La Niña (El Niño).

The two leading modes of winter surface air temperature (SAT) over China during 1961–2017 are a spatially consistent pattern and a north-south dipole pattern. Based on the two leading modes, the characteristics of the extreme cold and warm days in the two patterns, defined by the standard deviation larger than 1.28 or smaller than −1.28 in the time series of the two leading modes, are analyzed. With the increase of winter SAT during 1961–2017, the number of spatially consistent extreme cold days decreased and their occurrence was restricted to late December to early January, whereas the number of spatially consistent extreme warm days increased significantly in January and February. Global warming is associated with an increase in the spatially consistent extreme warm days and a decrease in spatially consistent extreme cold days, but has little relation to the sum of extreme cold and warm days of either the spatially consistent or north-south dipole pattern. The Siberian High (SH) is the main factor controlling the sum of spatially consistent extreme warm and cold days. The strong (weak) SH before (after) the 1990s corresponds to an increase (decrease) in the sum of the spatially consistent extreme warm and cold days. The occurrences of extreme south-cold-north-warm and extreme south-warm-north-cold days are related to the north-south difference of the SH. When the center of the SH is in mid-high latitudes, the extreme south-warm-north-cold (south-cold-north-warm) days occur more (less) often. During the winters of 1961–2017, the total number of extreme cold and warm days of the north-south dipole pattern changes negligibly. The North Atlantic meridional overturning circulation (AMOC) may be the main factor affecting the sum of the extreme cold and warm days of the two types of SAT pattern in China. [ABSTRACT FROM AUTHOR]

An observational study illustrates that three distinct modes of winter Siberian high variability exist in observations at the inter-annual time scale. In this paper, we compare the connection between these diverse Siberian high variation modes with pre-autumn and simultaneous Eurasian snow cover in an observation and BCC-CSM2-MR coupled climate model run under pre-industrial conditions from the CMIP6 project. Our analyses indicate that the inter-annual variation of observed Siberian high modes do have a connection with pre-autumn and simultaneous Eurasian snow cover anomalies, but the BCC-CSM2-MR coupled climate model does not capture the observed diverse Eurasian snow–Siberian high relationships well. The BCC-CSM2-MR coupled climate model can partly reproduce the observed Siberian high variation modes, but fail to capture the spatial distribution and statistics of boreal fall and winter Eurasian snowpack, which is a key facet of simulated diverse Siberian high variability irrespective of the influence of Eurasian snow cover.