Uncertainties of ENSO-related Regional Hadley Circulation Anomalies within Eight Reanalysis Datasets

El Nino-Southern Oscillation(ENSO),the leading mode of global interannual variability,usually intensifies the Hadley Circulation(HC),and meanwhile constrains its meridional extension,leading to an equatorward movement of the jet system.Previous studies have investigated the response of HC to ENSO events using different reanalysis datasets and evaluated their capability in capturing the main features of ENSO-associated HC anomalies.However,these studies mainly focused on the global HC,represented by a zonal-mean mass stream function(MSF).Comparatively fewer studies have evaluated HC responses from a regional perspective,partly due to the prerequisite of the Stokes MSF,which prevents us from integrating a regional HC.In this study,we adopt a recently developed technique to construct the three-dimensional structure of HC and evaluate the capability of eight state-of-the-art reanalyses in reproducing the regional HC response to ENSO events.Results show that all eight reanalyses reproduce the spatial structure of HC responses well,with an intensified HC around the central-eastern Pacific but weakened circulations around the Indo-Pacific warm pool and tropical Atlantic.The spatial correlation coefficient of the three-dimensional HC anomalies among the different datasets is always larger than 0.93.However,these datasets may not capture the amplitudes of the HC responses well.This uncertainty is especially large for ENSO-associated equatorially asymmetric HC anomalies,with the maximum amplitude in Climate Forecast System Reanalysis(CFSR)being about 2.7 times the minimum value in the Twentieth Century Reanalysis(20CR).One should be careful when using reanalysis data to evaluate the intensity of ENSO-associated HC anomalies.

Numerical Simulation of the Regional Ocean Circulation in the Coastal Areas of China

The regional ocean circulation in the coastal areas of China (including a part of the western PacificOcean, the South China Sea and the Bay of Bengal et al.) is simulated by using the improved Princeton University ocean circulation model (POM). Compared with the modeling results obtained by the large-scaleocean general circulation model (OGCM), the basic ocean circulation features simulated by the regionalocean circulation model al-e in good agreement with that simulated by OGCM and some detailed characteristics such as the regional ocean circulation, sea temperature, salinity and flee sea surface height have alsobeen obtained which are in good accord with the observations. These results indicate that the regional oceancirculation model has good capability to produce the legional ocean circulation characteristics and it can beused to develop coupled legional ocean-atmospheric model systems.

Main Features of Regional Circulation Variation during Onset of the South China Sea Monsoon in 1998

In this work, the National Center for Environmental Prediction/ National Center for Atmospheic Research (NCEP/ NCAR) global daily–mean reanalysis data are used to diagnose the features of the local circulation variation during the South China Sea (SCS) monsoon in 1998. It is found that by taking the appearance of southwest wind in lower layers and east wind in upper layers as the sign of the monsoon onset, the SCS monsoon starts on May 25 in 1998, which is later than that in normal years. The formation of the SCS monsoon is not a simple propagation of southwest monsoon in the north—south direction, but a process in which the southwest wind starts first over the north of the SCS, withdraws southward, and then propagates from south to north again. During this process, both meteorological elements and circulation fields change significantly. The outbreak of the SCS monsoon is the result of the seasonal variation of the height in lower and upper layers. The air rounding the Tibetan Plateau might be one of the dynamic reasons that make the summer monsoon start over the SCS at first. At the different stages of the monsoon, the vertical circulations as well as the lower and the upper layer divergence fields undergo evident temporal and regional changes. The SCS monsoon has the 60–day, 20–30–day and 8–15–day low frequency oscillations (LFOs), and dominant scale changes at the different stages of monsoon. The monsoon onset is related to the superimposition of the amplitudes of LFOs with different scales. Key words SCS monsoon - Circulation variation - Regional climate - LFO Sponsored by the National Key Project of Fundamental Research SCSMEX

Atmospheric Circulation and Dynamic Mechanism for Persistent Haze Events in the Beijing–Tianjin–Hebei Region

In this study, regional persistent haze events（RPHEs） in the Beijing–Tianjin–Hebei（BTH） region were identified based on the Objective Identification Technique for Regional Extreme Events for the period 1980–2013. The formation mechanisms of the severe RPHEs were investigated with focus on the atmospheric circulation and dynamic mechanisms. Results indicated that：（1） 49 RPHEs occurred during the past 34 years.（2） The severe RPHEs could be categorized into two types according to the large-scale circulation, i.e. the zonal westerly airflow（ZWA） type and the high-pressure ridge（HPR） type. When the ZWA-type RPHEs occurred, the BTH region was controlled by near zonal westerly airflow in the mid–upper troposphere.Southwesterly winds prevailed in the lower troposphere, and near-surface wind speeds were only 1–2 ms^-1. Warm and humid air originating from the northwestern Pacific was transported into the region, where the relative humidity was 70% to 80%, creating favorable moisture conditions. When the HPR-type RPHEs appeared, northwesterly airflow in the mid–upper troposphere controlled the region. Westerly winds prevailed in the lower troposphere and the moisture conditions were relatively weak.（3） Descending motion in the mid-lower troposphere caused by the above two circulation types provided a crucial dynamic mechanism for the formation of the two types of RPHEs. The descending motion contributed to a reduction in the height of the planetary boundary layer（PBL）, which generated an inversion in the lower troposphere. This inversion trapped the abundant pollution and moisture in the lower PBL, leading to high concentrations of pollutants.

Recent Strengthening of the Regional Hadley Circulation over the Western Pacific during Boreal Spring

Previous studies suggested that there are large discrepancies in the intensity trend of the zonally averaged Hadley circulation (ZAHC) among different reanalyses. As the land, ocean, and topography are not evenly distributed, the ZAHC may mask the regional variability. Changes in the regional HC have important implications for regional climate change. Here, we detect the long-term trend of the boreal spring regional Hadley circulation intensity over the western Pacific (WPHC) since 1979 in both hemispheres using six reanalysis datasets. Unlike the ZAHC, we find that the trend of the spring WPHC intensity is consistent among various reanalysis datasets. All reanalyses show pronounced strengthening trends for the WPHC in both the Northern and Southern Hemisphere, which may be partly attributable to the robust warming trends of sea surface temperature in the tropical western Pacific. The result could improve our understanding of Hadley circulation variability at the regional scale and has implications for regional climate changes.

Regional Oceanic Impact on Circulation and Direct Radiative Effect of Aerosol over East Asia

The Regional Integrated Environmental Model System （RIEMS 2.0） coupled with a chemistry-aerosol model and the Princeton Ocean Model （POM） is employed to simulate regional oceanic impact on atmospheric circulation and the direct radiative effect （DRE） of aerosol over East Asia. The aerosols considered in this study include both major anthropogenic aerosols （e.g., sulfate, black carbon, and organic carbon） and natural aerosols （e.g., soil dust and sea salt）. The RIEMS 2.0 is driven by NCEP/NCAR reanalysis II, and the simulated period is from 1 January to 31 December 2006. The results show the following： （1） The simulated annual mean sea-level pressure by RIEMS 2.0 with POM is lower than without POM over the mainland and higher without POM over the ocean. （2） In summer, the subtropical high simulated by RIEMS 2.0 with POM is stronger and extends further westward, and the continental low is stronger than without POM in summer. （3） The aerosol optical depth （AOD） simulated by RIEMS 2.0 with POM is larger in the middle and lower reaches of the Yangtze River than without POM. （4） The direct radiative effect with POM is stronger than that without POM in the middle and lower reaches of the Yangtze River and parts of southern China. Therefore, the authors should take account of the impact of the regional ocean model on studying the direct climate effect ＆aerosols in long term simulation.

A HOMOGENEOUS MODEL OF UPPER LAYER CIRCULATION IN INDO-PACIFIC REGION

A homogeneous model is proposed to study the upper layer circulation in the Indo-Pacific region,the sources of the Indonesian throughflow (TF) and the North Equatorial Countercurrent (NECC), and the relations of the the with the North Equatorial Current (NEC) and the South Equatorial Current (SEC). The results revealed that the upper layer circulaton, as part of the Pacific Ocean general circulation, is mainly controlled by geostrophic balance; that the NECC’s volume transport is mainly sup plied by the NEC, and its variation has closer relation to the NEC than the SEC; that the TF, whose volume transport is jointly supplied by the NEC through the Mindanao Current (MC) and the SEC, with the NEC being the first source, has significant influence on the circulation structure; and that a large Celebes Sea cyclonic circulation not mentioned elsewhere so far, exists in the calculated results.

Has the regional Hadley circulation over western Pacific during boreal winter been strengthening in recent decades?

Previous studies suggest a robust intensification of the zonally averaged hadley circulation(HC)during boreal winter in recent decades,but little is known regarding the regional HC.This study investigates long-term trends of the winter regional HC over the western pacific(WPHC)since 1979 using six reanalysis datasets.It is found that there are large discrepancies in the long-term trends of WPHC intensity among the six datasets.Specifically,three of the six reanalyses(erainterim,20CR and CFSR)show no discernible long-term trends,whereas NCEP-1,NCEP-2 and JRA-55 display pronounced intensification tendencies.Results in this study suggest that,although the warming trend of SST in the western tropical pacific identified in previous studies is robust,uncertainty remains regarding the long-term trends in the WPHC intensity.This raises a question about the factors involved in changes of the WPHC intensity.

On Willingness of Rural Land Circulation and Securitization in Central Regions of China

On the basis of questionnaire survey in 54 natural villages of 22 cities( counties) in 6 central region provinces,this paper analyzed the willingness of rural land circulation and securitization and influencing factors with the aid of Logistic model and Multinomial Logit model.The study indicates that factors influencing willingness of rural land circulation and securitization mainly include land contract method,land circulation information and approaches,rights and interests of farmers infringed or not,policies of benefiting farmers,and non-agricultural skills. Finally,it came up with following pertinent policy recommendations:( 1) reforming and improving land contract methods;( 2)strengthening disclosure of land circulation information;( 3) reforming and improving land circulation approaches;( 4) strengthening protection of farmers' rights and interests in the process of land circulation;( 5) reinforcing and implementing policies benefiting farmers;( 6) cultivating and developing farmers' non-agricultural skills.

五措并举提升大型仪器设备共享成效的探索

大型仪器设备是高校提高教学科研水平和人才培养质量的重要条件,是反映学校的综合实力和办学水平的重要指标。随着高等教育的发展,高校大型仪器设备的类型和数量在不断增加,由此也带来了重复购置、利用率低等问题。通过加大大型仪器设备信息化共享、加强大型仪器设备人员队伍建设、建立健全大型仪器设备共享机制、探索大型仪器全成本核算管理、强化大型仪器设备制度集成创新,形成以内循环为主、区域化为辅的共享模式,全面提升大型仪器设备共享实效。

中国经济内循环:来自多区域投入产出的演化证据

促进国内经济循环是新发展格局的重要内容。构建经济内循环的理论分析框架,将经济内循环分为区域内经济循环和区域间经济循环两个层面,在此基础上设计区域内循环、区域间循环的测度方法,并将全国划分为11大区域,重新构建11大区域投入产出表,测度分析2007—2015年中国经济内循环的区域特征、产业特征及其演化趋势。结果表明:(1)2007—2015年,中国各区域内部的循环能力总体得到提升,且长三角地区、黄河中下游地区、京津冀地区的区域内循环能力明显强于其他区域;(2)区域间循环系数整体上升,各区域间的差异缩小,其中京津冀地区、长三角地区、黄河中下游地区及大湾区与国内其他区域的联系最为紧密;(3)从区域内产业循环来看,制造业主要通过后向关联促进区域内循环,服务业主要通过前向关联促进区域内循环;(4)区域间产业循环的平均水平提升,通过后向关联促进区域间循环的产业集中在第二产业部门,通过前向关联促进区域间循环的产业集中在第三产业以及农业部门,京津冀地区、长三角地区、大湾区凭借多项优势产业,成为区域经济循环的引擎。

北宋粮食储备与流通对当前我国粮食安全的启示

当前,我国仍存在耕地数量降低、农民务农数量减少和种粮收益不高等问题,需要从国家到个人、思想到行动两个层面上采取措施,才能有效缓解。我国宋代粮食市场突出特点是地区间转运贸易发达,随着北宋粮食贸易的日渐活跃,百姓获得粮食渠道的拓宽,在一定程度上缓解了国家的粮食储备压力,影响了当时的粮食安全标准。北宋农民的赋税负担十分繁重,富民、地主粮食储备较为可观,官方与民间的粮食储备总量存在差距,具备藏粮于富民的特征。宋朝廷利用制度性和市场性的手段,将粮商作为国家的后备粮仓,灵活地缓解了官民粮食储备差距悬殊的矛盾。粮食流通在不同区域呈现出明显的地域性特征,不同的粮食来源和运输距离揭示了政治力量与经济力量在南、北救荒上的不同分配,北方地区的灾荒救济以官方力量为主,南方地区则以民间力量为主,粮食的性质、流通方式存在较大区别,影响着救荒效果。以北宋时期为鉴,当前我国应切实关注民生问题,构建多种形式的土地耕种格局;合理统筹全国区域性粮食流通,完善重大灾情下的粮食供给体系;树立科学粮食储备观,全方位增强社会戒奢从俭意识。

1981~2020年华南地区区域性极端降水事件研究

基于华南地区176个国家级自动气象站资料以及1981~2020年ECMWF ERA5再分析资料,采用区域性极端事件的客观识别方法(OITREE)、合成分析等方法,本文研究了华南地区区域性极端降水事件的时空分布特征,并分析了事件偏多年及偏少年的大尺度环流特征。主要结论如下:区域性极端降水事件的频次在年际尺度上的周期变化较为明显,并具有较明显的月变化特征,高发时段为5~6月;在极端强度及影响范围上,华南地区大部分区域性极端降水事件强度约130 mm d^(-1),较少事件强度超出320 mm d^(-1),且区域性极端降水事件的影响范围呈显著上升趋势(约310 km^(2)a^(-1));在事件的综合强度上,综合指数Z呈现显著的上升趋势[0.05(10 a)^(-1)],表明事件强度呈现显著增加的趋势;在大湾区及广东北部,区域性极端降水事件的累计降水及其对总降水的贡献呈显著上升趋势,而在广西南部地区,两者呈下降趋势;在事件偏多年,华南地区存在显著的西南风水汽输送及整层水汽通量强辐合的特征,而在事件偏少年,华南地区具有整层水汽通量辐合偏弱的特征;一般降水日,850 hPa上华南地区位于弱偏东南风区,区域性极端降水事件降水日,华南地区位于气旋性环流的东南部,受到明显的西南风风速大值带影响。

区域海气耦合模式WON在东南亚低纬高原一次强降水事件模拟中的应用

为改善东南亚低纬高原区(LLHSA)降水模拟的性能,提高降水预报准确性,本文采用大气环流模式WRF(4.2版)和海洋分量模式NEMO(3.4版),用耦合器OASIS3-MCT进行桥接,得到区域海气耦合模式WRF-OASIS-NEMO(WON)。大气和海洋分量模式都配置成相同的Arakawa-C网格,水平空间分辨率设为0.25°,耦合频次设置为逐小时,便于模拟海洋和大气环流相耦合的中尺度运动特征。为评估WON模式的模拟性能,选取2020年8月16-18日的强降水过程为例,与单独WRF模式的模拟效果进行比较分析。WON和WRF模式模拟的降水大值区位于高原东北部和中西部地区,平均日降水量约为20 mm·d^(-1),与观测事实基本相符。WON模式改善了WRF模式在高原南部降水偏多而在高原西北部降水偏少的模拟偏差。WON模式改善了降水动力条件的模拟效果,在高原中南部气旋式环流增强,在高原西侧反气旋式环流增强,进而改善了WRF模式在高原南部周围降水偏少,高原西北部降水偏多的模拟偏差。WRF和WON模式均能再现垂直螺旋度的发展特征,即在对流层中低层为正垂直螺旋度发展,而在对流层高层为负垂直螺旋度发展。两个模式在雨带西部400 hPa高度层附近垂直螺旋度模拟偏强,而在600~700 hPa高度层上垂直螺旋度模拟偏弱。WON模式相对于WRF模式的改进区域主要集中在雨带中西部地区。本次强降水的水汽来源包括孟湾的西南水汽输送和中国南海的偏南水汽输送。WRF模式和WON模式均能较好地重现相关水汽通量特征。WRF模式在孟湾北部水汽辐合偏强,而在中国南海水汽向北输送偏弱。WON模式主要改善了WRF模式在中国南海水汽输送偏弱的模拟偏差。WON模式改善降水模拟效果的主要原因是孟湾海表热通量交换导致孟湾中低层大气偏冷偏干,大气对流活动减弱,在孟湾北部形成的低层反气旋偏差改善了本次强降水过程动力条件和水汽条件的模拟效果。

城市流通网络建设与区域协调发展——来自“全国流通节点城市”布局的证据

合理布局流通节点城市,构建高效协同的城市流通网络,对于推动我国区域协调发展至关重要。基于2009-2020年287个地级市面板数据,以2015年颁布的“全国流通节点城市布局规划”为准自然实验,运用双重差分法实证检验城市流通网络建设对区域协调发展的影响。研究发现,流通节点城市布局政策能够显著提升区域内的协调发展程度,而国家级流通节点城市的政策效果占主导地位。机制检验表明,布局政策能够通过弱化商品贸易壁垒、提升物流效率、加速要素自由流动以及深化国内分工协作,间接促进区域协调发展。进一步分析发现:布局政策对区域协调发展的促进作用在东部、非资源型、营商环境好以及省际贸易结构平衡型的城市表现得更为明显;数字化基础条件能够正向调节流通节点城市布局政策效果;随着区域协调发展程度的提升,流通节点城市布局的政策边际效应将持续增强。研究结论有助于从国土空间治理视角拓展对现代流通体系建设的认识,并为弥合区域经济差距、推动高质量发展提供政策参考价值。

我国农产品流通现代化水平评价、动态演进与收敛性

农产品流通现代化是中国式现代化的具体实践,也是促进小农户共同富裕、加快农业农村现代化、全面推进乡村振兴的重要驱动力。为研究现阶段我国农产品流通现代化特征,解决地区失衡等问题,探索推进农产品流通现代化协同提升路径,从农产品流通规模和效益现代化水平、组织和体制现代化水平、设施和服务现代化水平以及渠道现代化水平四个维度,构建农产品流通现代化水平评价体系,采用变异系数法测度2013—2021年全国30个省份的农产品流通现代化发展水平,并综合运用核密度估计、Dagum基尼系数及其分解、σ收敛、β收敛、俱乐部收敛和多元有序Logit模型深入剖析农产品流通现代化水平的动态演进、地区差异、收敛性特征及其驱动因素。研究发现:第一,全国整体农产品流通现代化水平偏低且提升缓慢,东部地区发展水平最高、增幅最大,中部地区发展大体呈倒V型态势,西部地区提升微弱,东北地区则有衰退趋势。全国整体存在两级分化现象,各地区内部农产品流通现代化发展不均衡,省际绝对差距有逐步扩大趋势,而东部地区内部省份差距最为突出。第二,全国整体及四大地区均不存在σ收敛,但普遍具有条件β收敛特征,表明不同地区农产品流通现代化水平并不会收敛于同一水平。综合考虑地区异质性后,各地区的农产品流通现代化水平趋近各自稳态。第三,农产品流通现代化水平存在跨地区收敛现象,在观测期内形成6个收敛俱乐部和1个存在发展障碍的发散组。低水平俱乐部中的省份可通过加大农业人力资本、物质资本投入和政府扶持力度等路径实现向高水平俱乐部跃进。经济增长可以促进已收敛于高稳态水平俱乐部的省份向更高水平跃迁。基于此,应客观认识并充分重视部分省份及地区农产品流通现代化水平增长缓慢、陷入衰退的事实。引入内部评估机制和地区排名制度,坚持因地制宜和分类精准施策齐头并进。加强地区间、省域间的空间联动性,实现农产品流通现代化水平跨地区协同提升。

西南地区暴雨灾害集中度变化特征及其与环流指数的关系

选取1971—2020年西南地区95个气象站点日降水资料,以降水集中指数(PCI)为基础,构建了暴雨灾害集中指数(PDCI),分析了该指数在西南地区的时空变化特征,并运用交叉小波变换和小波相干变换方法探究了西南地区PDCI与大气环流指数的关系。结果表明:近50 a西南地区PDCI呈现增加趋势,其递增率为0.09/10 a,暴雨灾害发生的机率增长;西南地区75%的站点未来PDCI指数呈现增加趋势,预测暴雨灾害发生将会更为频繁;西南地区PDCI与AO、NAO、NINO1+2、NINO3.4、NINO4、PDO、SOI均存在共振周期,在不同时间段内PDCI与上述多种大气环流指数的相关性存在差异;对应的相关系数介于−0.27~0.31之间,得到上述多种大气环流指数均对西南地区暴雨灾害集中度存在一定影响。

基于熵权TOPSIS法的华东七省物流发展水平评价

当前,关于我国华东地区七省物流发展水平的研究较少。为深入探究华东地区物流发展水平,推动该区域物流行业的健康发展,进而保障该区域经济发展的稳步运行和持续进步,本文基于熵权TOPSIS方法,选出18个有关指标进行体系构建与分析,并对华东七省的物流发展水平现状做出评价,同时根据评价结果给出相应的对策建议,以供参考。

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.

“双循环”背景下中国虚拟水流动格局特征分析——基于MRIO模型

水资源是一项关系到国计民生的基础性自然资源和战略性经济资源,揭示虚拟水流动格局特征对水资源可持续发展具有重要意义。本研究通过构建多区域投入产出(MRIO)模型,利用2017年中国区域间投入产出表数据,构建区域间虚拟水资源核算体系,测算2017年中国贸易隐含虚拟水流量,从省内循环、省际循环和国际循环3个循环结构揭示中国虚拟水流动格局特征,为中国水资源管理政策制定提供有效建议。结论如下:1)中国虚拟水贸易呈现内循环占主体、国际循环占比较少的分布特征,其中内循环平均占比超过90%,省内循环平均占比超过70%,即区域间循环比重较少;2)虚拟水贸易的转移格局与中国区域水资源禀赋存在分布差异,经济较发达的丰水地区水资源最终需求呈现对外的极大依赖性,相反水资源稀缺地区对省际虚拟水流入依赖度较低。结果表明,中国应强调国内循环的主导作用,通过国内大循环推动国内国际双循环;同时依托虚拟水战略,打破省际壁垒,鼓励提高区域间循环比例,推进水资源的可持续管理。