Collating Historic Weather Observations for the East Asian Region： Challenges, Solutions, and Reanalyses

1. IntroductionHistoric instrumental weather observations, made on land or at sea from as early as the 17th century （e.g.,Camuffo et al.,2010）,are integral to extending our understanding of the decadal and centennial variations of Earth＇s climate and for comparison with paleo-proxy data.

East Asian Regional Cooperation Network and China’s Path Choice

The current East Asian regional cooperation framework is a complex system with multiple fields,levels,and players.In terms of social network theory and analysis,the East Asian regional cooperation framework can be defined as an affiliation network of cooperative mechanisms and players.Combing through the process of East Asian regional cooperation and constructing an East Asian regional cooperation network on the basis of the affiliation network model shows that the network has distinct characteristics in terms of cooperation mechanisms,cooperation entities,inter-entity relations,and the interaction of various fields of cooperation.These characteristics are apparent in concentrated form in the dynamics and limitations of East Asian regional cooperation networks.Describing and analyzing the structure and characteristics of the regional cooperation network of the Association of Southeast Asian Nations(ASEAN)can help us conduct a comprehensive examination of the current regional cooperation framework,grasp the developmental prospects of East Asian regional cooperation,and provide reference material for China's path choice in the process of future regional cooperation.

Drought fluctuations based on dendrochronology since 1786 for the Lenglongling Mountains at the northwestern fringe of the East Asian summer monsoon region

The Lenglongling Mountains （LLM） located in northeastern part of the Tibet Plateau, belong to a marginal area of the East Asian summer monsoon （EASM） and are sensitive to monsoon dynamics. Two tree-ring width chronologies developed from six sites of Picea crassifolia in the LLM were employed to study the regional drought variability. Correlation and temporal correlation analyses showed that relationships between the two chronologies and self-calibrated Palmer Drought Severity Index （sc_PDSI） were significant and stable across time, demonstrating the strength of sc_PDSI in modeling drought conditions in this region. Based on the relationships, the mean sc_PDSI was reconstructed for the period from 1786 to 2013. Dry conditions prevailed during 1817-1819, 1829-1831, 1928-1931 and 1999-2001. Relatively wet periods were identified for 1792-1795 and 1954-1956. Spatial correlations with other fourteen precipitation/drought reconstructed series in previous studies revealed that in arid regions of Northwest China, long-term variability of moisture conditions was synchronous before the 1950s at a decadal scale （1791-1954）. In northwestern margin of the EASM, most of all selected reconstructions had better consistency in low-frequency variation, especially during dry periods, indicating similar regional moisture variations and analogous modes of climate forcing on tree growth in the region.

Regional-scale Surface Air Temperature and East Asian Summer Monsoon Changes during the Last Millennium Simulated by the FGOALS-gl Climate System Model

The spatial patterns and regional-scale surface air temperature （SAT） changes during the last millennium,as well as the variability of the East Asian summer monsoon （EASM） were simulated with a low-resolution version of Flexible Global Ocean-Atmosphere-Land-Sea-ice （FGOALS-gl） model.The model was driven by both natural and anthropogenic forcing agents.Major features of the simulated past millennial Northern Hemisphere （NH） mean SAT variations,including the Medieval Climate Anomaly （MCA）,the Little Ice Age （LIA） and the 20th Century Warming （20CW）,were generally consistent with the reconstructions.The simulated MCA showed a global cooling pattern with reference to the 1961-90 mean conditions,indicating the 20CW to be unprecedented over the last millennium in the simulation.The LIA was characterized by pronounced coldness over the continental extratropical NH in both the reconstruction and the simulation.The simulated global mean SAT difference between the MCA and LIA was 0.14°C,with enhanced warming over high-latitude NH continental regions.Consistencies between the simulation and the reconstruction on regional scales were lower than those on hemispheric scales.The major features agreed well between the simulated and reconstructed SAT variations over the Chinese domain,despite some inconsistency in details among different reconstructions.The EASM circulation during the MCA was stronger than that during the LIA The corresponding rainfall anomalies exhibited excessive rainfall in the north but deficient rainfall in the south.Both the zonal and meridional thermal contrast were enhanced during the MCA.This temperature anomaly pattern favored a stronger monsoon circulation.

High-frequency climatic fluctuations over the past 30 ka in northwestern margin of the East Asian monsoon region, China

Whether millennial-to centennial-scale climate variations throughout the Holocene convey universal climate change is still widely debated.In this study,we aimed to obtain a set of high-resolution multi-proxy data(1343 particle size samples,893 total organic carbon samples,and 711 pollen samples)from an alluvial-lacustrine-aeolian sequence based on an improved age-depth model in the northwestern margin of the East Asian monsoon region to explore the dynamics of climate changes over the past 30 ka.Results revealed that the sequence not only documented the major climate events that corresponded well with those reported from the North Atlantic regions but also revealed many marked and high-frequency oscillations at the millennial-and centennial-scale.Specifically,the late stage of the last glacial lasting from 30.1 to 18.1 cal.ka BP was a dry and cold period.The deglacial(18.1-11.5 cal.ka BP)was a wetting(probably also warming)period,and three cold and dry excursions were found in the wetting trend,i.e.,the Oldest Dryas(18.1-15.8 cal.ka BP),the Older Dryas(14.6-13.7 cal.ka BP),and the Younger Dryas(12.5-11.5 cal.ka BP).The Holocene can be divided into three portions:the warmest and wettest early portion from 11.5 to 6.7 cal.ka BP,the dramatically cold and dry middle portion from 6.7 to 3.0 cal.ka BP,and the coldest and driest late portion since 3.0 cal.ka BP.Wavelet analysis results on the total pollen concentration revealed five substantially periodicities:c.5500,2200,900,380,and 210 a.With the exception of the c.5500 a quasi-cycle that was causally associated with the Atlantic meridional overturning circulation,the other four quasi-cycles(i.e.,c.2200,900,380,and 210 a)were found to be indirectly causally associated with solar activities.This study provides considerable insight into the dynamic mechanism of the Asian climate on a long-time scale and future climatic change.

Seasonal and Intraseasonal Variations of East Asian Summer Monsoon Precipitation Simulated by a Regional Air-Sea Coupled Model

The performance of a regional air-sea coupled model, comprising the Regional Integrated Environment Model System （RIEMS） and the Princeton Ocean Model （POM）, in simulating the seasonal and intraseasonal variations of East Asian summer monsoon （EASM） rainfall was investigated. Through comparisons of the model results among the coupled model, the uncoupled RIEMS, and observations, the impact of air-sea coupling on simulating the EASM was also evaluated. Results showed that the regional air sea coupled climate model performed better in simulating the spatial pattern of the precipitation climatology and produced more realistic variations of the EASM rainfall in terms of its amplitude and principal EOF modes. The coupled model also showed greater skill than the uncoupled RIEMS in reproducing the principal features of climatological intraseasonal oscillation （CISO） of EASM rainfall, including its dominant period, intensity, and northward propagation. Further analysis indicated that the improvements in the simulation of the EASM rainfall climatology and its seasonal variation in the coupled model were due to better simulation of the western North Pacific Subtropical High, while the improvements of CISO simulation were owing to the realistic phase relationship between the intraseasonal convection and the underlying SST resulting from the air-sea coupling.

Mid-Holocene Climate Variations Recorded by Palaeolake in Marginal Area of East Asian Monsoon: A Multi-proxy Study

Traditionally, the mid-Holocene in most parts of China was thought to be warmer with higher precipitation, resulting from a strong Asian summer monsoon. However, some recent researches have proposed a mid-Holocene drought interval of millennial-scale in East Asian monsoon margin areas. Thus whether mid-Holocene was dry or humid remains an open issue. Here, Zhuyeze palaeolake, the terminal lake of the Shiyang River Drainage lying in Asian monsoon marginal areas, was selected for reconstructing the details of climate variations during the Holocene, especially mid-Holocene, on the basis of a sedimentological analysis. Qingtu Lake (QTL) section of 6.92m depth was taken from Zhuyeze palaeolake. Multi-proxy analysis of QTL section, including grain size, carbonate, TOC, C/N and δ13C of organic matter, was used to document regional climatic changes during 9-3 cal ka B.P. The record shows a major environmental change at 9.0-7.8 cal ka B.P., attributed to a climate trend towards warmth and humidity. This event was followed by a typical regional drought event which occurred during 7.8-7.5 cal ka B.P. And a warm and humid climate prevailed from 7.5 to 5.0 cal ka B.P., attributed to the warm/humid Holocene Optimum in this region. After that, the climate gradually became drier. Moreover, comparison of the climate record from this paper with the summer insolation at 30°N indicates that the climate pattern reflecting the Asian monsoon changes was caused by insolation change.

THE ANALYSIS OF MECHANISM OF IMPACT OF AEROSOLS ON EAST ASIAN SUMMER MONSOON INDEX AND ONSET

RegCM4.3, a high-resolution regional climate model, which includes five kinds of aerosols(dust, sea salt,sulfate, black carbon and organic carbon), is employed to simulate the East Asian summer monsoon(EASM) from 1995 to 2010 and the simulation data are used to study the possible impact of natural and anthropogenic aerosols on EASM.The results show that the regional climate model can well simulate the EASM and the spatial and temporal distribution of aerosols. The EASM index is reduced by about 5% by the natural and anthropogenic aerosols and the monsoon onset time is also delayed by about a pentad except for Southeast China. The aerosols heat the middle atmosphere through absorbing solar radiation and the air column expands in Southeast China and its offshore areas. As a result, the geopotential height decreases and a cyclonic circulation anomaly is generated in the lower atmosphere. Northerly wind located in the west of cyclonic circulation weakens the low-level southerly wind in the EASM region. Negative surface radiative forcing due to aerosols causes downward motion and an indirect meridional circulation is formed with the low-level northerly wind and high-level southerly wind anomaly in the north of 25° N in the monsoon area, which weakens the vertical circulation of EASM. The summer precipitation of the monsoon region is significantly reduced,especially in North and Southwest China where the value of moisture flux divergence increases.

基于EOF的1951-2020年东亚季风区降水特征及其对夏季风不同配置的响应研究

东亚季风区夏季降水受季风影响显著,不同季风配置通过影响区域水汽输送,在东亚季风区形成不同的降水格局,降水格局的变化容易引起旱涝灾害的发生。本文基于经验正交函数(EOF)分析,利用全球降水气候中心(GPCC)降水资料、美国国家环境预测中心/大气研究中心(NCEP/NCAR)再分析资料和不同夏季风指数,分析了1951-2020年东亚季风区夏季降水格局,进一步结合相关分析、水汽通量分析等,研究了4种夏季风强弱不同配置对东亚季风区夏季降水的影响。结果表明:(1)1951-2020年东亚季风区降水经历了先减少后增加的变化。EOF分析较好地展现了东亚季风区夏季降水的时空分布,东亚季风区夏季降水主要表现为南北向“-、+、-”的三极型分布与南北方降水反相变化的偶极型特征;东亚季风区夏季降水异常主要发生在三极型降水结构的相位转换上,其次是偶极型的相位转换;(2)东亚季风区夏季降水异常是东亚季风、南亚季风、西风环流以及西太平洋季风等系统共同作用的结果。导致东亚季风区降水异常增加(减少)的季风配置主要为配置1:西太平洋季风强,东亚季风和西风弱(配置2:西风强,东亚季风和南亚季风弱);(3)配置1时,西太副高偏南偏西,中高纬形成西风槽,季风区南方季风较强,容易通过切变线以及抬升作用在季风区中部形成降水,导致异常降水增加,配置2时,西风强劲,南方水汽动力不足,无法深入大陆,造成异常降水减少。本文研究结果为气候变化背景下,探究东亚季风区异常降水机理提供理论基础,也为应对区域极端降水事件以及旱涝灾害防治工作提供重要的科学参考依据。

青藏高原春季区域性极端大风频次下降成因

极端大风是一种重要的气象灾害,同时亦是一种重要的气候资源。作为“世界屋脊”的青藏高原(Qinghai-XizangPlateau,QXP)区域是全球和区域气候变化的敏感区,其极端大风事件及其气候变化背景下变化特征与机理尚未完全清楚,尤其在川藏铁路建设背景下,加深高原区域极端大风事件的科学认知可为铁路建设和运营提供科学支撑和参考。为探讨高原区域性极端大风长期变化特征及其可能原因,利用地面观测最大风速日值数据,定义了青藏高原区域性极端大风事件,在此基础上,采用趋势分析、EOF分析、合成分析等多元统计方法分析了1982-2021年高原中东部区域性极端大风事件的时空分布和变化特征、发生的环流条件及其频次减少的可能原因。分析结果表明:(1)自20世纪80年代以来,青藏高原中东部区域性极端大风事件呈显著下降趋势,以95和99百分位定义的区域性极端大风日数每10年分别下降44天和11.6天,且变化主要表现为空间一致型,主要集中在高原东北部。(2)区域性极端大风发生期间,中高纬位势高度呈“西高东低”,低纬地区呈“西低东高”的分布形势,主要特征表现为蒙古-西伯利亚高压正异常,蒙古地区气旋式环流异常,高原东北部西风异常以及蒙古地区地表温度负异常。(3)全球变化背景下,春季西伯利亚高压强度减弱、上一个冬季东亚大槽强度加强致使高原南北两侧气压梯度减小、西风急流减弱导致动量下传减弱并且伴随着气旋性环流异常减弱,以及亚洲地表温度非均匀性上升使得南北温度梯度变小。这些大尺度环流和局地热力因子的协同影响可能是高原中东部区域性极端大风事件发生频次减少的重要原因。

东亚地区人口结构转变中独特的低生育模式及成因

东亚地区的各主要经济体都经历了从高生育水平到远低于更替水平的深刻转变,这使东亚地区成为世界生育“洼地”。中国在生育问题上有其自身独特的发展路径,但与东亚其他经济体一样受相同传统文化的深远影响,同样面临低生育率的挑战。因此,探索传统文化背景下东亚地区生育率的变化趋势、原因及其潜在机制,可以为理解和解决中国的低生育问题提供重要视角。论文围绕非婚生育、婚育年龄、孩次结构、生育偏好等方面分析东亚社会向超低生育水平趋同的独特生育模式,在此基础上探讨影响该地区低生育模式的直接因素,并进一步探究传统文化和社会因素影响东亚社会生育意愿的深层原因。在生育模式方面,东亚地区呈现非婚生育比例低、初婚初育年龄推迟、孩次递进比降低、终身未婚率增加、生育的男孩偏好等特点。这种独特的生育模式是其他地区普遍因素与该地区特有因素共同作用的结果。从直接原因方面剖析,“压缩现代性”刺激了东亚社会结构和家庭结构的转型,教育扩张促使女性经济地位和婚育观念发生改变,而经济不确定性和高昂的生育成本约束着婚姻和生育的选择;从深层原因方面探究,以家庭主义、集体主义和精英主义为核心的儒家价值观和社会规范不仅形塑性别角色、家庭分工、代际关系和生育偏好,影响家庭的教育理念和育儿的心理成本,也对政策干预的有效性形成制约。东亚地区持续的低生育率和独特的生育模式表明儒家文化对生育模式的影响并非单一的,随着经济、社会和文化的变迁,儒家文化对生育率的影响也在不断演变和调整,这对未来生育政策的导向提供了启示。东亚地区应重视其独特的文化制约因素,在政策制定过程中尊重并融入儒家文化价值,围绕促进家庭和谐与代际互助,推动生育政策与传统价值观变化的有机协调,使政策措施与深植于社会中的传统文化期望和行为模式相适应,从而提高政策的文化敏感性和社会影响力,促进东亚社会人口长期均衡发展。

东亚安全秩序变迁与中国的地区战略选择

冷战结束后,东亚安全秩序经历了一个不断变迁的过程。从美国强化日美同盟,牢牢掌握地区安全主导权的霸权秩序;转变为美国联盟体系依然占主导地位,但同时允许东亚地区合作兼容发展的复合秩序;再到2017年以来美国联盟体系转型且不断冲击东亚地区安全合作,从而形成竞争秩序。中国是东亚安全秩序变迁的直接推动者,通过管理中美关系,推动国际权力和平转移,重建地区国家政治信任,以新经济关系促进新安全关系,以及和平解决争端,塑造地区安全的多边治理框架,中国逐渐从权力、关系和治理三个维度建构自身的地区角色和地区战略。为了防止竞争性安全秩序进一步向对抗和冲突方向演变,中国应以维护地区秩序稳定为首要目标,在保持自身战略可持续发展的基础上,推动新安全格局的构建,并聚焦全球安全倡议的重点合作领域,拓展地区公共产品供给的方式和路径,为推动东亚地区从竞争性秩序向包容性秩序的变迁而创造条件、积蓄能量。

冷战后日本对东南亚外交的脉络、逻辑与影响

冷战后日本对东南亚外交的演变脉络呈现明显的阶段性调整,包含政策领域与政策路径等。在此过程中,日本突出东南亚外交的政治色彩并全面发展与东盟国家的各领域双边关系,在持续深化经济外交的基础上取得了经济合作机制化建设进展,且正致力于推动与部分东盟国家的海洋安全合作及其机制化建设,进而试图主导地区秩序构建。日本对东南亚外交的政策逻辑主要体现在国家战略转型、地区框架建构与大国关系互动3个层面。其中,日本国家战略的目标诉求与实施路径,始终对其东南亚外交起到规范作用;日本对东南亚外交既是地区框架建构进程的有效组成部分,又受其规范与制约;日本始终需要考虑美国、中国等大国因素,且美国因素是约束日本外交取向的首要因素。冷战后日本对东南亚的外交深化了日本与东盟国家间双边关系,为日本自身的国家战略转型提供路径支撑,但在地区层面上则导致东亚合作框架泛化、东盟中心地位弱化以及地区安全局势不稳。

新石器时代出土漆器的跨区域比较研究

漆器作为人类早期的重要发明,与早期陶器一样是中华文明对世界文明的重要贡献之一,也是人类对自然资源认识与利用的结晶。目前考古发现最早使用漆器的国家是中国与日本。我国长江下游在距今8200年的井头山遗址出土了迄今世界上最早的漆器,而日本绳文时代鸟滨遗址也出土了距今6000年前的红色漆梳。本文在梳理中日两国新石器时代出土资料的基础上,从漆器原料、制漆工具、制作技术及科技分析等方面,对这一时期漆器制作工艺的复杂性、艺术性和礼仪性进行了跨区域比较分析。漆器作为早期国家祭祀礼仪体系的物化体现之一,彰显了漆器手工业在东亚早期国家进程中具有的重要性和对周边其他国家地区的影响与传播。

DIAGNOSTIC ANALYSIS OF PERSISTENT DROUGHT/FLOOD EVENTS IN SUMMER OVER THE TWO-LAKE REGION OF CHINA

Based on the daily regional mean rainfall,the Z-index method is used to identify persistent flood and drought events lasting for at least 10 days over a region where Dongting Lake and Poyang Lake sit(referred to as the"two-lake region"hereafter).The National Centers for Environmental Prediction(NCEP)reanalysis data are then utilized to perform a preliminary diagnostic analysis on these events.The results indicate that the composite standardized geopotential height at 500 hPa presents two different meridional wave trains from north to south over the East Asian-Pacific region,i.e.,a"-+-"pattern for the droughts and a"+-+"pattern for the floods,respectively.The developing,maintaining and decaying phases in the drought and flood events are closely related to the intensity and location of a subtropical high and an extra-tropical blocking high.It is shown that the East Asian summer monsoon is strong(weak)with the occurrence of persistent drought(flood)events.Droughts(floods)are accompanied by a weak(strong)tropical convergent system and a strong(weak)subtropical convergent system.Furthermore,the persistent drought(flood)events are associated with a divergence(convergence)of vertically integrated water vapor flux.In the vertical profile of water vapor flux,divergence(convergence)in the mid-and lower-levels and convergence(divergence)in the higher levels are evident in the droughts(floods).Both the divergence in the droughts and the convergence in floods are strongest at 850 hPa.

Efects of Crop Growth on Hydrological Processes in River Basins and on Regional Climate in China

The regional climate model RegCM3 incorporating the crop model CERES,called the RegCM3CERES model,was used to study the efects of crop growth and development on regional climate and hydrological processes over seven river basins in China.A 20-year numerical simulation showed that incorporating the crop growth and development processes improved the simulation of precipitation over the Haihe River Basin,Songhuajiang River Basin and Pearl River Basin.When compared with the RegCM3 control run,RegCM3CERES reduced the negative biases of monthly mean temperature over most of the seven basins in summer,especially the Haihe River Basin and Huaihe River Basin.The simulated maximum monthly evapotranspiration for summer(JJA)was around 100 mm in the basins of the Yangtze,Haihe,Huaihe and Pearl Rivers.The seasonal and annual variations of water balance components(runof,evapotranspiration and total precipitation)over all seven basins indicate that changes of evapotranspiration agree well with total precipitation.Compared to the RegCM3,RegCM3CERES simulations indicate reduced local water recycling rate over most of the seven basins due to lower evapotranspiration and greater water flux into these basins and an increased precipitation in the Heihe River Basin and Yellow River Basin,but reduced precipitation in the other five basins.Furthermore,a lower summer leaf area index(1.20 m2m 2),greater root soil moisture(0.01 m3m 3),lower latent heat flux(1.34 W m 2),and greater sensible heat flux(2.04 W m 2)are simulated for the Yangtze River Basin.

Economic growth and unemployment in East Asia

Barro and Sala-i-Martin （2004） analyzed the empirical determinants of growth. The data used in this paper consists of panel data of several macroeconomic variables observed for 55 years 0950-2004） in six East Asian countries and regions. Following the implications of semi-endogenous growth theory, the author regressed output growth on the determinants of steady-state income. The estimation and test results suggest the existence of significant relationship between steady-state income and （trend weighted） R ＆ D input both in Japan and South Korea. In addition, following Cellini （1995）, the author also considers cointegration and error-correction methods as the growth regression of East Asian countries. Meanwhile, Chang, et al （2004） derived the conclusion that the decreases in reallocation shocks are main factor in a downward trend in natural rate of unemployment for South Korea. The author extends this analysis using structural VAR to other Asian countries and regions, Japan and Taiwan region. Impulse responses show that the growth of production in Korea and Taiwan reduce unemployment, but, in Japan, this raises unemployment.

The Statistical Significance Test of Regional Climate Change Caused by Land Use and Land Cover Variation in West China

The West Development Policy being implemented in China is causing significant land use and land cover （LULC） changes in West China. With the up-to-date satellite database of the Global Land Cover Characteristics Database （GLCCD） that characterizes the lower boundary conditions, the regional climate model RIEMS-TEA is used to simulate possible impacts of the significant LULC variation. The model was run for five continuous three-month periods from 1 June to 1 September of 1993, 1994, 1995, 1996, and 1997, and the results of the five groups are examined by means of a student t-test to identify the statistical significance of regional climate variation. The main results are： （1） The regional climate is affected by the LULC variation because the equilibrium of water and heat transfer in the air-vegetation interface is changed. （2） The integrated impact of the LULC variation on regional climate is not only limited to West China where the LULC varies, but also to some areas in the model domain where the LULC does not vary at all. （3） The East Asian monsoon system and its vertical structure are adjusted by the large scale LULC variation in western China, where the consequences are the enhancement of the westward water vapor transfer from the east oast and the relevant increase of wet-hydrostatic energy in the middle-upper atmospheric layers. （4） The ecological engineering in West China affects significantly the regional climate in Northwest China, North China and the middle-lower reaches of the Yangtze River; there are obvious effects in South, Northeast, and Southwest China, but minor effects in Tibet.

基于RCEP的东亚区域贸易协定质量研究

在深挖区域贸易协定质量内涵、梳理区域贸易协定质量测度方法的基础上,构建了区域贸易协定质量测度指标,将东亚区域贸易协定质量研究范围置于RCEP框架下,采用世界银行PTAs数据库数据,测算了东亚区域贸易协定的质量。根据测算结果,从覆盖力指标和法律约束力指标两个维度,按照总体、区域、国家、条款进行分类,多角度分析东亚区域贸易协定质量,归纳出东亚区域经济体深度一体化特征,为推进RCEP框架下的东亚区域各经济体间的高质量贸易投资合作、提升其在全球价值链分工的地位,提供有借鉴的参考。