Will the Globe Encounter the Warmest Winter after the Hottest Summer in 2023?

In the boreal summer and autumn of 2023,the globe experienced an extremely hot period across both oceans and continents.The consecutive record-breaking mean surface temperature has caused many to speculate upon how the global temperature will evolve in the coming 2023/24 boreal winter.In this report,as shown in the multi-model ensemble mean(MME)prediction released by the Institute of Atmospheric Physics at the Chinese Academy of Sciences,a medium-to-strong eastern Pacific El Niño event will reach its mature phase in the following 2−3 months,which tends to excite an anomalous anticyclone over the western North Pacific and the Pacific-North American teleconnection,thus serving to modulate the winter climate in East Asia and North America.Despite some uncertainty due to unpredictable internal atmospheric variability,the global mean surface temperature(GMST)in the 2023/24 winter will likely be the warmest in recorded history as a consequence of both the El Niño event and the long-term global warming trend.Specifically,the middle and low latitudes of Eurasia are expected to experience an anomalously warm winter,and the surface air temperature anomaly in China will likely exceed 2.4 standard deviations above climatology and subsequently be recorded as the warmest winter since 1991.Moreover,the necessary early warnings are still reliable in the timely updated mediumterm numerical weather forecasts and sub-seasonal-to-seasonal prediction.

A spatial-explicit dynamic vegetation model that couples carbon,water,and nitrogen processes for arid and semiarid ecosystems

Arid and semiarid ecosystems, or dryland, are important to global biogeochemical cycles. Dryland＇s community structure and vegetation dynamics as well as biogeochemical cycles are sensitive to changes in climate and atmospheric composition. Vegetation dynamic models has been applied in global change studies, but the com- plex interactions among the carbon （C）, water, and nitrogen （N） cycles have not been adequately addressed in the current models. In this study, a process-based vegetation dynamic model was developed to study the responses of dryland ecosystems to environmental changes, emphasizing on the interactions among the C, water, and N proc- esses. To address the interactions between the C and water processes, it not only considers the effects of annual precipitation on vegetation distribution and soil moisture on organic matter （SOM） decomposition, but also explicitly models root competition for water and the water compensation processes. To address the interactions between C and N processes, it models the soil inorganic mater processes, such as N mineralization/immobilization, denitrifica- tion/nitrification, and N leaching, as well as the root competition for soil N. The model was parameterized for major plant functional types and evaluated against field observations.

Modeling grassland net primary productivity and water-use efficiency along an elevational gradient of the Northern Tianshan Mountains

Mountainous ecosystems are considered highly sensitive and vulnerable to natural disasters and cli- rnatic changes. Therefore, quantifying the effects of elevation on grassland productivity to understand ecosys- tem-climate interactions is vital for mountainous ecosystems. Water-use efficiency （WUE） provides a useful index for understanding the metabolism of terrestrial ecosystems as well as for evaluating the degradation of grasslands. This paper explored net primary productivity （NPP） and WUE in grasslands along an elevational gradient ranging from 400 to 3,400 m asl in the northern Tianshan Mountains-southern Junggar Basin （TMJB）, Xinjiang of China, using the Biome-BGC model. The results showed that： 1 ） the NPP increased by 0.05 g C/（m2-a） with every increase of 1-m elevation, reached the maximum at the mid-high elevation （1,600 m asl）, and then decreased by 0.06 g C/（m2.a） per 1-m increase in elevation; 2） the grassland NPP was positively correlated with temperature in alpine meadow （AM, 2,700-3,500 m asl）, mid-mountain forest meadow （MMFM, 1,650-2,700 m asl） and low-mountain dry grassland （LMDG, 650-1,650 m asl）, while positive correlations were found between NPP and annual precipitation in plain desert grassland （PDG, lower than 650 m asl）; 3） an increase （from 0.08 to 1.09 g C/（m2.a）） in mean NPP for the grassland in TMJB under a real climate change scenario was observed from 1959 to 2009; and 4） remarkable differences in WUE were found among different elevations, in general, WUE increased with decreasing elevation, because water availability is lower at lower elevations; however, at elevations lower than 540 m asl, we did observe a decreasing trend of WUE with decreasing elevation, which may be due to the sharp changes in canopy cover over this gradient. Our research suggests that the NPP simulated by Biome-BGC is consistent with field data, and the modeling provides an opportunity to further evaluate interactions between environmental factors and ecosystem productivity.

Skilful Forecasts of Summer Rainfall in the Yangtze River Basin from November

Variability in the East Asian summer monsoon(EASM)brings the risk of heavy flooding or drought to the Yangtze River basin,with potentially devastating impacts.Early forecasts of the likelihood of enhanced or reduced monsoon rainfall can enable better management of water and hydropower resources by decision-makers,supporting livelihoods and major economic and population centres across eastern China.This paper demonstrates that the EASM is predictable in a dynamical forecast model from the preceding November,and that this allows skilful forecasts of summer mean rainfall in the Yangtze River basin at a lead time of six months.The skill for May–June–July rainfall is of a similar magnitude to seasonal forecasts initialised in spring,although the skill in June–July–August is much weaker and not consistently significant.However,there is some evidence for enhanced skill following El Niño events.The potential for decadal-scale variability in forecast skill is also examined,although we find no evidence for significant variation.

Why Was the Strengthening of Rainfall in Summer over the Yangtze River Valley in 2016 Less Pronounced than that in 1998 under Similar Preceding El Nino Events？Role of Midlatitude Circulation in August

It is widely recognized that rainfall over the Yangtze River valley （YRV） strengthens considerably during the decaying summer of E1 Nifio, as demonstrated by the catastrophic flooding suffered in the summer of 1998. Nevertheless, the rainfall over the YRV in the summer of 2016 was much weaker than that in 1998, despite the intensity of the 2016 E1 Nifio having been as strong as that in 1998. A thorough comparison of the YRV summer rainfall anomaly between 2016 and 1998 suggests that the difference was caused by the sub-seasonal variation in the YRV rainfall anomaly between these two years, principally in August. The precipitation anomaly was negative in August 2016--different to the positive anomaly of 1998.

环氧度对异戊橡胶/环氧化杜仲胶并用胶性能的影响

制备了一系列环氧度的环氧化杜仲胶(EEUG)并用于改性异戊橡胶(IR),采用不含补强填料的胶料配方进行硫化。重点研究了环氧度对IR/EEUG并用胶的硫化特性、结晶结构以及静态和动态力学性能的影响。利用差示扫描量热法、偏光显微镜和原子力显微镜分析了EEUG的聚集态结构和IR/EEUG的结晶结构和相结构。结果表明,EEUG由结晶结构转变为无定形结构的临界环氧度为21.0%(摩尔分数)。环氧度为14.3%、EEUG用量为10 phr的硫化胶90IR/10EEUG-14.3中可见少量微小晶体,且随着EEUG-14.3用量增加,IR/EEUG硫化胶的拉伸强度和断裂伸长率下降。随EEUG环氧度增加,90IR/10EEUG硫化胶的拉伸强度和断裂伸长率同时增加,90IR/10EEUG-21.0拉伸性能最佳。EEUG-21.0处于结晶结构向无定形结构转变的临界状态,容易发生应变诱导结晶,甚至通过EEUG与IR分子间相互作用引发IR应变诱导结晶。EEUG的存在提高了IR硫化胶0℃时的tanδ值、降低了60℃时的tanδ值,说明适宜环氧度的EEUG可同时改善IR的抗湿滑性和滚动阻力。

The Seasonal Prediction of the Exceptional Yangtze River Rainfall in Summer 2020

During June and July of 2020,the Yangtze River basin suffered from extreme mei-yu rainfall and catastrophic flooding.This study explores the seasonal predictability and associated dynamical causes for this extreme Yangtze River rainfall event,based on forecasts from the Met Office GloSea5 operational forecast system.The forecasts successfully predicted above-average rainfall over the Yangtze River basin,which arose from the successful reproduction of the anomalous western North Pacific subtropical high(WNPSH).Our results indicate that both the Indian Ocean warm sea surface temperature(SST)and local WNP SST gradient were responsible for the westward extension of the WNPSH,and the forecasts captured these tropical signals well.We explore extratropical drivers but find a large model spread among the forecast members regarding the meridional displacements of the East Asian mid-latitude westerly jet(EAJ).The forecast members with an evident southward displacement of the EAJ favored more extreme Yangtze River rainfall.However,the forecast Yangtze River rainfall anomaly was weaker compared to that was observed and no member showed such strong rainfall.In observations,the EAJ displayed an evident acceleration in summer 2020,which could lead to a significant wind convergence in the lower troposphere around the Yangtze River basin,and favor more mei-yu rainfall.The model forecast failed to satisfactorily reproduce these processes.This difference implies that the observed enhancement of the EAJ intensity gave a large boost to the Yangtze River rainfall,hindering a better forecast of the intensity of the event and disaster mitigation.

Meridional Displacement of the East Asian Upper-tropospheric Westerly Jet and Its Relationship with the East Asian Summer Rainfall in CMIP5 Simulations

As the first leading mode of upper-tropospheric circulation in observations, the meridional displacement of the East Asian westerly jet (EAJ) varies closely with the East Asian rainfall in summer. In this study, the interannual variation of the EAJ meridional displacement and its relationship with the East Asian summer rainfall are evaluated, using the historical simulations of CMIP5 (phase 5 of the Coupled Model Intercomparison Project). The models can generally reproduce the meridional displacement of the EAJ, which is mainly manifested as the first principal mode in most of the simulations. For the relationship between the meridional displacement of the EAJ and East Asian rainfall, almost all the models depict a weaker correlation than observations and exhibit considerably large spread across the models. It is found that the discrepancy in the interannual relationship is closely related to the simulation of the climate mean state, including the climatological location of the westerly jet in Eurasia and rainfall bias in South Asia and the western North Pacific. In addition, a close relationship between the simulation discrepancy and intensity of EAJ variability is also found: the models with a stronger intensity of the EAJ meridional displacement tend to reproduce a closer interannual relationship, and vice versa.

Seasonal Forecasts of the Summer 2016 Yangtze River Basin Rainfall

The Yangtze River has been subject to heavy flooding throughout history, and in recent times severe floods such as those in 1998 have resulted in heavy loss of life and livelihoods. Dams along the river help to manage flood waters, and are important sources of electricity for the region. Being able to forecast high-impact events at long lead times therefore has enormous potential benefit. Recent improvements in seasonal forecasting mean that dynamical climate models can start to be used directly for operational services. The teleconnection from E1 Nifio to Yangtze River basin rainfall meant that the strong E1 Nifio in winter 2015/16 provided a valuable opportunity to test the application of a dynamical forecast system. This paper therefore presents a case study of a real-time seasonal forecast for the Yangtze River basin, building on previous work demonstrating the retrospective skill of such a forecast. A simple forecasting methodology is presented, in which the forecast probabilities are derived from the historical relationship between hindcast and observations. Its performance for 2016 is discussed. The heavy rainfall in the May-June-July period was correctly forecast well in advance. August saw anomalously low rainfall, and the forecasts for the June-July-August period correctly showed closer to average levels. The forecasts contributed to the confidence of decision-makers across the Yangtze River basin. Trials of climate services such as this help to promote appropriate use of seasonal forecasts, and highlight areas for future improvements.

The Anomalous Mei-yu Rainfall of Summer 2020 from a Circulation Clustering Perspective:Current and Possible Future Prevalence

Highly unusual amounts of rainfall were seen in the 2020 summer in many parts of China,Japan,and South Korea.At the intercontinental scale,case studies have attributed this exceptional event to a displacement of the climatological western North Pacific subtropical anticyclone,potentially associated Indian Ocean sea surface temperature patterns and a mid-latitude wave train emanating from the North Atlantic.Using clusters of spatial patterns of sea level pressure,we show that an unprecedented 80%of the 2020 summer days in East Asia were dominated by clusters of surface pressure greater than normal over the South China Sea.By examining the rainfall and water vapor fluxes in other years when these clusters were also prevalent,we find that the frequency of these types of clusters was likely to have been largely responsible for the unusual rainfall of 2020.From two ensembles of future climate projections,we show that summers like 2020 in East Asia may become more frequent and considerably wetter in a warmer world with an enhanced moisture supply.

Predictable and Unpredictable Components of the Summer East Asia–Pacific Teleconnection Pattern

The East Asia–Pacific(EAP) teleconnection pattern is the dominant mode of circulation variability during boreal summer over the western North Pacific and East Asia, extending from the tropics to high latitudes. However, much of this pattern is absent in multi-model ensemble mean forecasts, characterized by very weak circulation anomalies in the mid and high latitudes. This study focuses on the absence of the EAP pattern in the extratropics, using state-of-the-art coupled seasonal forecast systems. The results indicate that the extratropical circulation is much less predictable, and lies in the large spread among different ensemble members, implying a large contribution from atmospheric internal variability. However,the tropical–mid-latitude teleconnections are also relatively weaker in models than observations, which also contributes to the failure of prediction of the extratropical circulation. Further results indicate that the extratropical EAP pattern varies closely with the anomalous surface temperatures in eastern Russia, which also show low predictability. This unpredictable circulation–surface temperature connection associated with the EAP pattern can also modulate the East Asian rainband.

Skillful Seasonal Forecasts of Summer Surface Air Temperature in Western China by Global Seasonal Forecast System Version 5

Variations of surface air temperature （SAT） are key in affecting the hydrological cycle, ecosystems and agriculture in western China in summer. This study assesses the seasonal forecast skill and reliability of SAT in western China, using the GloSea5 operational forecast system from the UK Met Office. Useful predictions are demonstrated, with considerable skill over most regions of western China. The temporal correlation coefficients of SAT between model predictions and observations axe larger than 0.6, in both northwestern China and the Tibetan Plateau. There are two important sources of skill for these predictions in western China： interannual variation of SST in the western Pacific and the SST trend in the tropical Pacific. The tropical SST change in the recent two decades, with a warming in the western Pacific and cooling in the eastern Pacific, which is reproduced well by the forecast system, provides a large contribution to the skill of SAT in northwestern China. Additionally, the interannual variation of SST in the western Pacific gives rise to the reliable prediction of SAT around the Tibetan Plateau. It modulates convection around the Maritime Continent and further modulates the variation of SAT on the Tibetan Plateau via the surrounding circulation. This process is evident irrespective of detrending both in observations and the model predictions, and acts as a source of skill in predictions for the Tibetan Plateau. The predictability and reliability demonstrated in this study is potentially useful for climate services providing early warning of extreme climate events and could imply useful economic benefits.

Seasonal Rainfall Forecasts for the Yangtze River Basin in the Extreme Summer of 2020

Seasonal forecasts for Yangtze River basin rainfall in June,May–June–July(MJJ),and June–July–August(JJA)2020 are presented,based on the Met Office GloSea5 system.The three-month forecasts are based on dynamical predictions of an East Asian Summer Monsoon(EASM)index,which is transformed into regional-mean rainfall through linear regression.The June rainfall forecasts for the middle/lower Yangtze River basin are based on linear regression of precipitation.The forecasts verify well in terms of giving strong,consistent predictions of above-average rainfall at lead times of at least three months.However,the Yangtze region was subject to exceptionally heavy rainfall throughout the summer period,leading to observed values that lie outside the 95%prediction intervals of the three-month forecasts.The forecasts presented here are consistent with other studies of the 2020 EASM rainfall,whereby the enhanced mei-yu front in early summer is skillfully forecast,but the impact of midlatitude drivers enhancing the rainfall in later summer is not captured.This case study demonstrates both the utility of probabilistic seasonal forecasts for the Yangtze region and the potential limitations in anticipating complex extreme events driven by a combination of coincident factors.

Contrasts between the Interannual Variations of Extreme Rainfall over Western and Eastern Sichuan in Mid-summer

Rainfall amount in mid-summer(July and August)is much greater over eastern than western Sichuan,which are characterized by basin and plateau,respectively.It is shown that the interannual variations of extreme rainfall over these two regions are roughly independent,and they correspond to distinct anomalies of both large-scale circulation and sea surface temperature(SST).The enhanced extreme rainfall over western Sichuan is associated with a southward shift of the Asian westerly jet,while the enhanced extreme rainfall over eastern Sichuan is associated with an anticyclonic anomaly in the upper troposphere over China.At low levels,on the other hand,the enhanced extreme rainfall over western Sichuan is related to two components of wind anomalies,namely southwesterly over southwestern Sichuan and northeasterly over northeastern Sichuan,which favor more rainfall under the effects of the topography.Relatively speaking,the enhanced extreme rainfall over eastern Sichuan corresponds to the low-level southerly anomalies to the east of Sichuan,which curve into northeasterly anomalies over the basin when they encounter the mountains to the north of the basin.Therefore,it can be concluded that the topography in and around Sichuan plays a crucial role in inducing extreme rainfall both over western and eastern Sichuan.Finally,the enhanced extreme rainfall in western and eastern Sichuan is related to warmer SSTs in the Maritime Continent and cooler SSTs in the equatorial central Pacific,respectively.

基于激发态运动方程耦合簇的神经网络透热势能矩阵:苯硫酚^(1)πσ^(*)态-介导的光解

本文用最近发展的神经网络拟合方法[Chin.J.Chem.Phys.34,825(2021)]构造了一个新的涉及苯硫酚^(1)πσ^(*)态-介导光解的^(1)ππ^(*)和^(1)πσ^(*)态耦合非绝热势能面.势能面包含了解离过程中的三个关键振动模式,即S-H伸缩、弯曲和扭转振动.由于单双激发态运动方程耦合簇方法具有简单、效率高、精度高的优点,采用激发态运动方程耦合簇方法计算了苯硫酚激发态^(1)ππ^(*)和^(1)πσ^(*)的绝热能量.神经网络拟合绝热激发态S_(1)和S_(2)态的均方根误差分别为0.89和1.33 meV,表明神经网络方法具有很高的拟合精度.在构建非绝热势能面的过程中,仅利用了体系绝热势能,避免了非常耗时的非绝热耦合计算,极大地提高了效率.为了检测新的非绝热势能面的可靠性,本文进一步展开了苯硫酚光解非绝热动力学模拟.动力学计算得到的S_(1)振电态0^(0)和3^(1)的寿命与实验和之前的理论结果均吻合,验证了基于激发态运动方程耦合簇绝热能量构建的非绝热势能面的可靠精确性,并可进一步应用到实际大分子体系中.

神经网络方法构建苯硫酚三维非绝热势能面

本文利用神经网络方法构建了苯硫酚三维的基态(S0)绝热势能面以及激发态1ππ^(*)和1πσ^(*)耦合的非绝热势能面.特别地,1ππ^(*)和1πσ^(*)非绝热势能面的透热化是通过神经网络拟合实现的,拟合仅基于其绝热势能,但对非绝热势能矩阵的非对角元施加了对称性的正确限制.神经网络拟合的3个态的势能面的拟合均方根误差都非常小(<4 meV),体现了神经网络方法的高精度.在神经网络构建的势能面上计算得到了S0态的低位能级和S_(1)态0^(0)的寿命,结果均与早前非绝热势能面上的结果吻合,验证了神经网络方法构建的绝热和非绝热势能面的高精度和可靠性.

Modified Coffin-Manson equation to predict the fatigue life of structural materials subjected to mechanical-thermal coupling non-coaxial loading

With regard to the structures subjected to severe mechanical-thermal coupling fatigue conditions,the consistency between service conditions and loading conditions was the prerequisite for the fatigue prop-erties test and fatigue life prediction.A miniature piezoelectric-driven instrument integrating with a tripodal piezoelectric actuator and envelope-type heating function was developed to investigate the mechanical-thermal coupling fatigue properties and obtain the fatigue life of materials under approximate service conditions.A physical model was described to quantitatively calculate the alternating deformation under the mechanical-thermal coupling tensile-bending combined condition.Accordingly,a fatigue life prediction method based on the Coffin-Manson equation under tensile-bending combined loading was proposed to estimate the mechanical-thermal coupling fatigue life in terms of the total coupling defor-mation and plastic strain amplitude.The feasibility of the proposed instrument was verified through the analysis of displacement responses of high entropy alloy specimens under the thermal-mechanical cou-pling tensile-bending combined condition at temperatures ranging from RT to 600°C.The comparison between fatigue lives directly measured through thermal-mechanical coupling experiments and theoreti-cally predicted fatigue lives indicated the availability of the modified Coffin-Manson equation.

Seasonal Rainfall Forecasts for the Yangtze River Basin of China in Summer 2019 from an Improved Climate Service

Rainfall forecasts for the summer monsoon season in the Yangtze River basin(YRB) allow decision-makers to plan for possible flooding, which can affect the lives and livelihoods of millions of people. A trial climate service was developed in 2016, producing a prototype seasonal forecast product for use by stakeholders in the region, based on rainfall forecasts directly from a dynamical model. Here, we describe an improved service based on a simple statistical downscaling approach. Through using dynamical forecast of an East Asian summer monsoon(EASM) index, seasonal mean rainfall for the upper and middle/lower reaches of YRB can be forecast separately by use of the statistical downscaling, with significant skills for lead times of up to at least three months. The skill in different sub-basin regions of YRB varies with the target season. The rainfall forecast skill in the middle/lower reaches of YRB is significant in May–June–July(MJJ), and the forecast skill for rainfall in the upper reaches of YRB is significant in June–July–August(JJA). The mean rainfall for the basin as a whole can be skillfully forecast in both MJJ and JJA. The forecasts issued in 2019 gave good guidance for the enhanced rainfall in the MJJ period and the near-average conditions in JJA. Initial feedback from users in the basin suggests that the improved forecasts better meet their needs and will enable more robust decision-making.

Beclin-1/LC3-II dependent macroautophagy was uninfluenced in ischemia-challenged vascular endothelial cells

Autophagy has been extensively studied and occurs in many biological settings.However,a question remains as to whether ischemia enhances Beclin-1/LC3-II-dependent macroautophagy in vascular endothelial cells,as has been previously thought.Furthermore,the effect of the level of autophagy on cell or skin flap survival still requires elucidation.We created a lethal ischemia model in human umbilical vascular endothelial cells(HUVECs),performed quantitative proteomics and bioinformatics analyses,and verified the autophagic status and effect both in vitro and in vivo.The significantly upregulated proteins encoded by autophagy-related genes(ATGs)included ATG2A,ATG3,ATG4B,ATG5,ATG7,ATG9A,ATG12,ATG16,and ATG101.The significantly enhanced lysosomal proteins were cathepsin B,cathepsin D,lysosome-associated membrane protein 1(LAMP1),and LAMP2.However,the differentially expressed proteins excluded Beclin-1,microtubule-associated protein light chain 3(LC3)-I,and LC3-II.Western blot analyses verified that the protein expression levels of Beclin-1,LC3-I,and LC3-II were neither upregulated nor downregulated in ischemia-challenged HUVECs.The autophagic status was not enhanced by rapamycin in ischemic HUVECs but appeared to be inhibited by chloroquine.Our in vivo study on rats showed that a downregulation in autophagic status jeopardized skin flap survival.In conclusion,Ischemia neither enhanced nor inhibited Beclin-1/LC3-II-dependent canonical macroautophagy both in vitro and in vivo,in contradiction to previous studies.An appropriate autophagic homeostasis can minimize cell or skin flap damage.

The effect of hierarchical single-crystal ZSM-5 zeolites with different Si/Al ratios on its pore structure and catalytic performance

Hierarchical single-crystal ZSM-5 zeolites with different Si/Al ratios(Hier-ZSM-5-x,where x=50,100,150 and 200)were synthesized using an ordered mesoporous carbon-silica composite as hard template.Hier-ZSM-5-x exhibits improved mass transport properties,excellent mechanical and hydrothermal stability,and higher catalytic activity than commercial bulk zeolites in the benzyl alcohol self-etherification reaction.Results show that a decrease in the Si/Al ratio in hierarchical single-crystal ZSM-5 zeolites leads to a significant increase in the acidity and the density of micropores,which increases the final catalytic conversion.The effect of porous hierarchy on the diffusion of active sites and the final catalytic activity was also studied by comparing the catalytic conversion after selectively designed poisoned acid sites.These poisoned Hier-ZSM-5-x shows much higher catalytic conversion than the poisoned commercial ZSM-5 zeolite,which indicates that the numerous intracrystalline mesopores significantly reduce the diffusion path of the reactant,leading to the faster diffusion inside the zeolite to contact with the acid sites in the micropores predominating in ZSM-5 zeolites.This study can be extended to develop a series of hierarchical single-crystal zeolites with expected catalytic performance.