Preliminary report of coseismic surface rupture(part)of Türkiye's M_(W)7.8 earthquake by remote sensing interpretation

Both M_(W) 7.8 and M_(W) 7.5 earthquakes occurred in southeastern Türkiye on February 6,2023,resulting in numerous buildings collapsing and serious casualties.Understanding the distribution of coseismic surface ruptures and secondary disasters surrounding the epicentral area is important for post-earthquake emergency and disaster assessments.High-resolution Maxar and GF-2 satellite data were used after the events to extract the location of the rupture surrounding the first epicentral area.The results show that the length of the interpreted surface rupture zone(part of)is approximately 75 km,with a coseismic sinistral dislocation of 2-3 m near the epicenter;however,this reduced to zero at the tip of the southwest section of the East Anatolia Fault Zone.Moreover,dense soil liquefaction pits were triggered along the rupture trace.These events are in the western region of the Eurasian Seismic Belt and result from the subduction and collision of the Arabian and African Plates toward the Eurasian Plate.The western region of the Chinese mainland and its adjacent areas are in the eastern section of the Eurasian Seismic Belt,where seismic activity is controlled by the collision of the Indian and Eurasian Plates.Both China and Türkiye have independent tectonic histories.

A Port of Opening Up

Border cities in Xinjiang are playing an important part in China’cross-border rail transportation,The expedition of Chinese explorer Zhang Qian more than 2,000 years ago is considered to be the foundation of the ancient Silk Road.Today,his legendary exploration of the ancient Silk Road is renowned worldwide.Venturing across the Eurasian continent with camel caravans laden with silk,spices,tea,and other Chinese goods,he forged vital trade routes of the Silk Road.Xinjiang has had a central role in that trade.

Analysis of Heavy Precipitation Event in Northeast China from August 1 to 5, 2023

This study delves into the multiple weather systems and their interaction mechanisms that caused the severe rainfall event in Northeast China in early August 2023. The analysis reveals that the atmospheric circulation in the mid-to-high latitudes of the Eurasian continent exhibited a significant “two troughs and two ridges” structure, with Northeast China located precisely in the peripheral region of the subtropical high, significantly influenced by its marginal airflows. Additionally, the residual circulation of Typhoon “Doksuri” interacting with the subtropical high and upper-level troughs significantly increased the rainfall intensity and duration in the region. In particular, the continuous and powerful transport of the southwest jet provided the necessary moisture and unstable conditions for the generation and development of convective systems. The rainfall event resulted in nearly 40,000 people affected and crop damage covering an area of approximately 4000 hectares, demonstrating the severity of extreme weather. The study emphasizes that strengthening meteorological monitoring and early warning systems, as well as formulating and improving emergency response mechanisms, are crucial for reducing potential disaster losses caused by heavy rainfall. Future research can further explore the interaction mechanisms among weather systems, limitations of data sources, and the connection between long-term trends of heavy rainfall events and global climate change.

Heat waves in summer 2022 and increasing concern regarding heat waves in general

The year 2022 featured an unprecedented hot summer that has attracted worldwide attention.Abnormal warming spread over most of the Eurasian continent and North America(Fig.1),with Europe and China especially suffering from extraordinarily long-lasting extreme heat events.In addition,severe droughts,which are a common accompaniment to heat waves,attacked Europe and the Yangtze River basin in China.Droughts in Sichuan Province,which is in the upstream region of the Yangtze River basin and is proud of its water resources and hydro power,led to power shortages and adverse effects on the lives and productivity of local people.Extremely high temperatures and severe drought induced massive wildfires in Europe,North America,and Asia,including Chongqing(Fig.2),a neighboring municipality of Sichuan Province.

Can Eurasia Experience a Cold Winter under a Third-Year La Nina in 2022/23?

The Northern Hemisphere(NH)often experiences frequent cold air outbreaks and heavy snowfalls during La Nina winters.In 2022,a third-year La Nina event has exceeded both the oceanic and atmospheric thresholds since spring and is predicted to reach its mature phase in December 2022.Under such a significant global climate signal,whether the Eurasian Continent will experience a tough cold winter should not be assumed,despite the direct influence of mid-to high-latitude,large-scale atmospheric circulations upon frequent Eurasian cold extremes,whose teleconnection physically operates by favoring Arctic air invasions into Eurasia as a consequence of the reduction of the meridional background temperature gradient in the NH.In the 2022/23 winter,as indicated by the seasonal predictions from various climate models and statistical approaches developed at the Institute of Atmospheric Physics,abnormal warming will very likely cover most parts of Europe under the control of the North Atlantic Oscillation and the anomalous anticyclone near the Ural Mountains,despite the cooling effects of La Nina.At the same time,the possibility of frequent cold conditions in mid-latitude Asia is also recognized for this upcoming winter,in accordance with the tendency for cold air invasions to be triggered by the synergistic effect of a warm Arctic and a cold tropical Pacific on the hemispheric scale.However,how the future climate will evolve in the 2022/23 winter is still subject to some uncertainty,mostly in terms of unpredictable internal atmospheric variability.Consequently,the status of the mid-to high-latitude atmospheric circulation should be timely updated by medium-term numerical weather forecasts and sub-seasonal-to-seasonal prediction for the necessary date information and early warnings.

Relative importance of tidal flats and artificial habitats for two spoonbill species and related interspecific differences

Artificial/seminatural environments,such as aquacultural ponds,saltpans,and croplands,have recently been acknowledged as important habitats for coastal waterbirds.Although coastal waterbirds tend to use artificial habitats around tidal flats as roosting sites during high-tide,it remains unclear whether the importance of surrounding habitats relative to tidal flats varies among landscape types,seasons,species,or tidal conditions.The Black-faced Spoonbill(Platalea minor)and Eurasian Spoonbill(P.leucorodia)are two closely related sympatric species in East Asia with narrow and wide distribution ranges and habitat requirements,respectively.We therefore expect that both species will use surrounding artificial habitats across seasons at high tides,but Blackfaced Spoonbills will use them less frequently than Eurasian Spoonbills.Here,we address these hypotheses in the Imazu tidal flat and its surrounding environments in southern Japan.We investigated the habitat use and behavioral patterns of both species through route and behavioral surveys during the fall migration and wintering seasons in 2021.We found that both species used surrounding habitats including artificial ones more frequently than the tidal flat regardless of the tidal condition or season,but spoonbills used these habitats more frequently in winter than in autumn.We also found that Eurasian Spoonbills foraged in surrounding artificial habitats more frequently than Black-faced Spoonbills.These results not only demonstrate how coastal waterbirds exploit surrounding habitats relative to tidal flats but also suggest that the importance of surrounding habitats varies among species and seasons.Our study thus emphasizes that valuing and managing surrounding habitats in addition to tidal flats are key to conserving globally declining waterbirds.

Effects of constant light and dark conditions on the locomotor activity,body mass,and body temperature rhythms of Eurasian Tree Sparrows(Passer montanus)

Light is an essential environmental cue influencing the endogenous circadian clocks that regulate behavioral and physiological processes in animals.Despite extensive research on the circadian rhythms of avian behavior and physiology,the mechanisms by which they adapt and adjust to abnormal photoperiod conditions,such as artificial light,have yet to be fully elucidated.Here,the circadian rhythms of the body mass,activity,and core and peripheral body temperatures of the Eurasian Tree Sparrow(Passer montanus,ETS)-a diurnal passerine-were examined under three different lighting conditions:constant light(LL),constant darkness(DD),and normal light-dark cycles(LD).Our results showed that the activity,body mass,core,tarsometatarsus,and eye temperatures of the ETSs varied significantly with treatment,time,and the interaction between treatment and time;however,there was no significant change in body mass in response to the interaction between time and treatment.Under LD conditions,the ETSs exhibited significant circadian rhythms in activity and core,tarsometatarsus,and eye temperatures.Under LL conditions,only the core temperature exhibited significant rhythmicity.Under DD conditions,there were no significant circadian rhythms in activity,body mass,and eye temperature;however,the core and tarsometatarsus temperatures remained rhythmic.Our results indicate that the core body temperature rhythm of ETS is endogenous and can be maintained under abnormal photoperiods.In contrast,the activity and body surface temperature,uncoupled from the core body temperature under abnormal photoperiod conditions,strongly depend on light.These results differ from those of other diurnal avian species,suggesting a unique coping mechanism of ETS in response to an abnormal photoperiod.

Vicariance and monsoon as drivers of diversification of nemacheilid loaches(Teleostei:Cypriniformes)around the Hengduan Mountains of China

DEAR EDITOR,High mountainous terrains facilitate the diversification of biota by providing a variety of opportunities for isolation(Favre et al.,2015).Within the Nemacheilidae family of loaches,the highly diverse Nemacheilini tribe is a polyphyletic group,with extensive distribution across the Indian and Eurasian plates(Chen et al.,2019;Sgouros et al.,2019).

当前国际战略安全形势的主要动向及突出特点

The international strategic security situation is in its most turbulent period since the end of the Cold War.The trend toward a multipolar world is deepening,and the power game between major countries is more intense than ever.The momentum of economic globalization has been severely hindered or even reversed.Europe is once again mired in war,and the Eurasian continent is beset by crises.Energy security,food security,and environmental security are intertwined,posing unprecedented challenges to mankind.The two major issues of global peace and development have become more prominent,and the world has once again come to a crossroads in history.

The Eurasian Economic Union in the Context of Geopolitical Changes in Europe and Asia

Before Russia launched its special military operation against Ukraine,the economic integration process of the Eurasian Economic Union(EAEU),driven by Russia,was generally proceeding smoothly despite internal disagreements.However,the Russia-Ukraine conflict and the subsequent extreme sanctions imposed by the West have seriously deteriorated the EAEU’s external environment.

Eurasian Snow Cover Variability and Its Association with Summer Rainfall in China

This study investigates the statistical linkage between summer rainfall in China and the preceding spring Eurasian snow water equivalent （SWE）, using the datasets of summer rainfall observations from 513 stations, satellite-observed snow water equivalent, and atmospheric circulation variables in the NCEP/NCAR reanalysis during the period from 1979 to 2004. The first two coupled modes are identified by using the singular value decomposition （SVD） method. The leading SVD mode of the spring SWE variability shows a coherent negative anomaly in most of Eurasia with the opposite anomaly in some small areas of the Tibetan Plateau and East Asia. The mode displays strong interannual variability, superposed on an interdecadal variation that occurred in the late 1980s, with persistent negative phases in 1979-1987 and frequent positive phases afterwards. When the leading mode is in its positive phase, it corresponds to less SWE in spring throughout most of Eurasia. Meanwhile, excessive SWE in some small areas of the Tibetan Plateau and East Asia, summer rainfall in South and Southeast China tends to be increased, whereas it would be decreased in the up-reaches of the Yellow River. In recent two decades, the decreased spring SWE in Eurasia may be one of reasons for severe droughts in North and Northeast China and much more significant rainfall events in South and Southeast China. The second SVD mode of the spring SWE variability shows opposite spatial variations in western and eastern Eurasia, while most of the Tibetan Plateau and East Asia are in phase. This mode significantly correlates with the succeeding summer rainfall in North and Northeast China, that is, less spring SWE in western Eurasia and excessive SWE in eastern Eurasia and the Tibetan Plateau tend to be associated with decreased summer rainfall in North and Northeast China.

Arctic Sea Ice and Eurasian Climate:A Review

The Arctic plays a fundamental role in the climate system and has shown significant climate change in recent decades,including the Arctic warming and decline of Arctic sea-ice extent and thickness. In contrast to the Arctic warming and reduction of Arctic sea ice, Europe, East Asia and North America have experienced anomalously cold conditions, with record snowfall during recent years. In this paper, we review current understanding of the sea-ice impacts on the Eurasian climate.Paleo, observational and modelling studies are covered to summarize several major themes, including： the variability of Arctic sea ice and its controls; the likely causes and apparent impacts of the Arctic sea-ice decline during the satellite era,as well as past and projected future impacts and trends; the links and feedback mechanisms between the Arctic sea ice and the Arctic Oscillation/North Atlantic Oscillation, the recent Eurasian cooling, winter atmospheric circulation, summer precipitation in East Asia, spring snowfall over Eurasia, East Asian winter monsoon, and midlatitude extreme weather; and the remote climate response（e.g., atmospheric circulation, air temperature） to changes in Arctic sea ice. We conclude with a brief summary and suggestions for future research.

The Cretaceous Songliao Basin:Volcanogenic Succession,Sedimentary Sequence and Tectonic Evolution,NE China

The Songliao basin （SB） is a superposed basin with two different kinds of basin fills. The lower one is characterized by a fault-bounded volcanogenic succession comprising of intercalated volcanic, pyrodastic and epiclastic rocks. The volcanic rocks, dating from 110 Ma to 130 Ma, are of geochemically active continental margin type. Fast northward migration of the SB block occurred during the major episodes of the volcanism inferred from their paleomagnetic information. The upper one of the basin fill is dominated by non-marine sag-style sedimentary sequence of silicidastics and minor carbonates. The basin center shifted westwards from the early to late Cretaceous revealed by the GGT seismic velocity structure suggesting dynamic change in the basin evolution. Thus, a superposed basin model is proposed. Evolution of the SB involves three periods including （1） Alptian and pre- Aptian： a retroarc basin and range system of Andes type related to Mongolia-Okhotsk collisional belt （MOCB）; （2） Albian to Companian： a sag-like strike-slip basin under transtension related to oblique subduction of the Pacific plate along the eastern margin of the Eurasian plate; （3） since Maastrichtian： a tectonic inverse basin under compression related to normal subduction of the Pacific plate under the Eurasian plate, characterized by overthrust, westward migration of the depocenter and eastward uplifting of the basin margin.

The Archipelagic Ocean System of the Eastern Eurasian Tethys

Unlike typical oceans such as the wide and 'clean' Atlantic, the Tethys has been showing an archipelagic pattern during all its evolutionary stages. Compared with the traditional, wedge-shaped and relatively 'clean' ocean model, the archipelagic model is more suitable for the Tethys, especially the eastern Tethys. This paper demonstrates the eastern Tethys archipelagic system in terms of the subdivision, characteristics and evolutionary history of the Qinling-Qilian-Kunlun, South China and Xizang (Tibet)-Yunnan Regions of the eastern Eurasian Tethys.

Connections between the Eurasian Teleconnection and Concurrent Variation of Upper-level Jets over East Asia

The variation of the East Asian jet stream （EAJS） associated with the Eurasian （EU） teleconnection pattern is investigated using 60-yr NCEP-NCAR daily reanalysis data over the period 1951-2010.The EAJS consists of three components：the polar front jet （PFJ）; the plateau subtropical jet （PSJ）; and the ocean subtropical jet （OSJ）.Of these three jets over East Asia,the EU pattern exhibits a significant influence on the PFJ and OSJ.There is a simultaneous negative correlation between the EU pattern and the PFJ.A significant positive correlation is found between the EU pattern and the OSJ when the EU pattern leads the OSJ by about 5 days.There is no obvious correlation between the EU pattern and the PSJ.The positive EU phase is accompanied by a weakened and poleward-shifted PFJ,which coincides with an intensified OSJ.A possible mechanism for the variation of the EAJS during different EU phases is explored via analyzing the effects of 10-day high-and low-frequency eddy forcing.The zonal wind tendency due to high-frequency eddy forcing contributes to the simultaneous negative correlation between the EU pattern and the PFJ,as well as the northward/southward shift of the PFJ.High-and low-frequency eddy forcing are both responsible for the positive correlation between the EU pattern and the OSJ,but only high-frequency eddy forcing contributes to the lagged variation of the OSJ relative to the EU pattern.The negative correlation between the EU pattern and winter temperature and precipitation anomalies in China is maintained only when the PFJ and OSJ are out of phase with each other.Thus,the EAJS plays an important role in transmitting the EU signal to winter temperature and precipitation anomalies in China.

Eurasian Snow Conditions and Summer Monsoon Rainfall over South and Southeast Asia: Assessment and Comparison

This study reveals the complex nature of the connection between Eurasian snow and the following summer season＇s monsoon rainfall by using four different indicators of snow conditions and correlating each of them to summer monsoon rainfall. Using 46 years of historical records of mean winter snow depth, maximum snow depth, and snow starting dates, and 27 years of snow area coverage from remote sensing observations over Eurasia, the authors found diverse correlation patterns between snow conditions and the following warm season＇s rainfall over South and Southeast Asia. Some of the results contradict the well-known inverse relationships between snow and the summer monsoon. This study provides an easy comparison of results in that it shows the connections between Eurasian snow and monsoon rainfall by using different Eurasian snow indicators based on the best available historical records without discrimination of regional variations in snow conditions.

Intercomparison of the Impacts of Four Summer Teleconnections over Eurasia on East Asian Rainfall

East Asian summer climate is strongly affected by extratropical circulation disturbances.In this study,impacts of four atmospheric teleconnections over Eurasia on East Asian summer rainfall are investigated using National Centers for Environmental Prediction/National Center for Atmospheric Research （NCEP/NCAR） reanalysis data and Climatic Research Unit （CRU） land precipitation data during 1979-2009.The four teleconnections include the Scandinavian （SCA）,the Polar/Eurasian （PEU）,the East Atlantic/Western Russian （EAWR）,and the circumglobal teleconnection （CGT）.Moreover,the related changes of lower-tropospheric circulation are explored,specifically,the low pressure over northern East Asia （NEAL） and the subtropical high over the western North Pacific （WNPSH）.The results presented are in the positive phase.The PEU and SCA induce significant negative anomalies in North China rainfall （NCR）,while the CGT induces significant positive anomalies.In the past three decades,the PEU and SCA explain more than 20％ of the variance in NCR,twice that explained by the CGT,suggesting a more important role of the former two teleconnections in NCR variation than the latter one.Meanwhile,the PEU and SCA reduce rainfall in Northeast China and South Korea,respectively,and the CGT enhances rainfall in Japan.The rainfall responses are attributed to the SCA-induced northward shift of the NEAL,and PEU-induced northward shift and weakening of the NEAL,respectively.For the CGT,the dipole pattern of rainfall anomalies between North China and Japan is affected by both westward extension of the NEAL and northwestward expansion of the WNPSH.In addition,the EAWR leads to an increase of sporadic rainfall in South China as a result of the eastward retreat of the WNPSH.

Relationships between Regional Indian Summer Monsoon Rainfall and Eurasian Snow Cover

In this work,correlation analysis is applied to study the interannual relationships betWeen indian summer monsoon rainfall of different homogeneous regions and Eurasian Snow Cover(ESC) during winter and spring seasons for the time period from 1973 to 1992.The monsoon rainfall of the western and central regions of india,as well as the all-India monsoon rainfall,is significantly negatively correlated with the ESC averaged for the monthsDecember-March and with,especially,the ESC of February.This study may provide some useful information for the long-range prediction of the regional indian monsoon rainfall.

Influence of the Arctic on the Predictability of Eurasian Winter Extreme Weather Events

The linkage between the Arctic and midlatitudes has received much attention recently due to the rapidly changing climate.Many investigations have been conducted to reveal the relationship between the Arctic and Eurasian extreme events from the perspective of climatological statistics.As a prediction source for extreme events in Eurasia,Arctic conditions are crucial for extreme event predictions.Therefore,it is urgent to explore the Arctic influence on the predictability of Eurasian extreme events due to the large uncertainties in Arctic conditions.Considering the sensitivity and nonlinearity of the atmospheric circulations in midlatitude to Arctic conditions,it is necessary to investigate the Arctic influences on Eurasian extreme weather events in case studies at weather time scales.Previous studies indicate that only perturbations in specific patterns have fast growth.Thus,the conditional nonlinear optimal perturbation approach is recommended for exploring the uncertainties in Arctic initial and boundary conditions and their synergistic effect on Eurasian extreme events.Moreover,the mechanism for extreme event formation may differ in different cases.Therefore,more extreme cases should be investigated to reach robust conclusions.

Influence of October Eurasian Snow on Winter Temperature over Northeast China

This paper addresses the interannual variation of winter air temperature over Northeast China and its connection to preceding Eurasian snow cover. The results show that there is a significant negative correlation between October Eurasian snow cover and following-winter air temperature over Northeast China. The snow cover located in eastern Siberia and to the northeast of Lake Baikal plays an important role in the winter air temperature anomaly. More （less） eastern Siberia snow in October can cause an atmospheric circulation anomaly pattern in which the atmospheric pressure is higher （lower） than normal in the polar region and lower （higher） in the northern mid-high latitudes. Due to the persistence of the eastern Siberia snow from October to the following winter, the winter atmospheric anomaly is favorable （unfavorable） to the widespread movement of cold air masses from the polar region toward the northern mid-high latitudes and, hence, lower （higher） temperature over Northeast China. Simultaneously, when the October snow cover is more （less）, the SST in the northwestern Pacific is continuously lower （higher） as a whole; then, the Aleutian low and the East Asia trough are reinforced （weakened）, favoring the lower （higher） temperature over Northeast China.