Reclassification and distribution patterns of discovered oils in theDongying Depression, Bohai Bay Basin, China

The Dongying Depression is an important petrolifeous province,with diverse source rocks and complex petroleum distribution patterns.A total of 32 crude oils were analyzed by the gas chromatographyemass spectrometry and isotopic compositions to better understanding the petroleum systems in the study area.Three oil types were classified by hierarchical cluster analyses.Type I and II oils have closely correlation with the discovered source rocks,which have been confirmed to be mainly derived from the lower third and upper forth member of the Eocene Shahejie Formation source rocks(Es3^(L) and Es4^(U)),respectively.Obviously,type III oils contain abundant gammacerane,tricyclic terpanes and C_(29) steranes and have lower values of δ13C than type I and II oils,indicating a completely different source rock and biological origins.Until recently,type III oils fail to match any of the discovered source rock,which contains main contribution of aquatic organism or/and bacteria inputs.In addition,the spacial distribution of these three oil types were discussed.Type I oils mainly distributed in the Es3 and Es4 reservoirs that closed to the generative kitchens.Type II oils occurred in the Es4 reservoirs in the sourthern slope of the depression,which probably caused by lateral migration along the horizontal fractures and sandstone layers within the Es4 interval.Differently,type III oils in the sourthern slope of the depression were mainly discovered in the Eocene Kongdian or Ordocician reservoirs,which suggests great exploration potential of deep underlying strata.

Sedimentary Processes and Depositional Characteristics of Coarse-grained Subaqueous Fans along Steep Slopes in a Lacustrine Rift Basin:A Case Study from the Dongying Depression,Bohai Bay Basin,China

Coarse-grained subaqueous fans are vital oil and gas exploration targets in the Bohai Bay basin,China.The insufficient understanding of their sedimentary processes,depositional patterns,and controlling factors restricts efficient exploration and development.Coarse-grained subaqueous fans in the Yong′an area,Dongying Depression,are investigated in this study.These fans include nearshore subaqueous fans,and sublacustrine fans,and their sedimentary processes,depositional patterns and distribution characteristics are mainly controlled by tectonic activity and paleogeomorphology.Nearshore subaqueous fans developed near the boundary fault during the early–middle deposition stage due to strong tectonic activity and large topographic subsidence.Early sublacustrine fans developed at the front of the nearshore subaqueous fans in the area where the topography changed from gentle to steep along the source direction.While the topography was gentle,sublacustrine fans did not develop.During the late weak tectonic activity stage,late sublacustrine fans developed with multiple stages superimposed.Frequent fault activity and related earthquakes steepened the basin margin,and the boundary fault slopes were 25.9°–34°.During the early–middle deposition stage,hyperpycnal flows triggered by outburst floods developed.During the late deposition stage,with weak tectonic activity,seasonal floods triggered hyperpycnal flows,and hybrid event beds developed distally.

Diversity of depositional architecture and sandbody distribution of sublacustrine fans during forced regression: A case study of Paleogene Middle Sha 3 Member in Dongying Sag, Bohai Bay Basin, East China

Currently, the differences in gravity flow deposits within different systems tracts in continental lacustrine basins are not clear. Taking the middle submember of the third member of Paleogene Shahejie Formation(Sha 3 Member) in the Shishen 100 area of the Dongying Sag in the Bohai Bay Basin as an example, the depositional architecture of sublacustrine fans during forced regression and the impact of the fourth-order base-level changes on their growth were investigated using cores, well logs and 3D seismic data. Sublacustrine fans were mainly caused by hyperpycnal flow during the fourth-order base-level rise, while the proportion of slump-induced sublacustrine fans gradually increased during the late fourth-order base-level fall. From rising to falling of the fourth-order base-level, the extension distance of channels inside hyperpycnal-fed sublacustrine fans reduced progressively, resulting in the transformation in their morphology from a significantly channelized fan to a skirt-like fan. Furthermore, the depositional architecture of distributary channel complexes in sublacustrine fans changed from vertical aggradation to lateral migration, and the lateral size of individual channel steadily decreased. The lobe complex's architectural patterns evolved from compensational stacking of lateral migration to aggradational stacking, and the lateral size of individual lobe steadily grew. This study deepens the understanding of depositional features of gravity flow in high-frequency sequence stratigraphy and provides a geological foundation for the fine development of sublacustrine fan reservoirs.

Genetic mechanisms and control on hydrocarbon accumulation in transtensional structures: A case study of Gaoqing area, northern Dongying Sag, China

Broom-shaped structures are widely seen in transtensional basins, including those discovered in many sags of the Bohai Bay Basin. Broom-shaped transtensional structural zones are generally petroliferous and thus important targets for hydrocarbon exploration. This study analyzed the evolution and genetic mechanisms of the broom-shaped transtensional structures in the Gaoqing area of the Dongying Sag using the 3D seismic flattening technique and a physical simulation experiment. Furthermore, the control effects of the broom-shaped transtensional structures on hydrocarbon accumulation and distribution were discussed. The research results are as follows. The Gaoqing area is of a broom-shaped transtensional structure in planar view, composed of several arc-shaped secondary faults intersecting with high-level main fault in the same direction. On the seismic section, it appears as a typical semi-flower-like structure. In the early stage (that is, during the deposition of the Kongdian Formation to the lower submember of the 4th member of the Shahejie Formation, Es4(L)), single-fault pattern consisting of single or multiple faults in alignment was developed under extensional stress. While with the change of structural stress (that is, during the deposition of the Es4(U) to the Es2(L)), more secondary faults were formed, and came in a pattern of broom-shaped structure together with the major fault. In the late stage (that is, during the deposition of the Es1 to the Guantao Formation), the en echelon fault pattern was formed, as the major fault broke into multiple secondary faults. The divergent end of the broom-shaped transtensional structure has many secondary faults developed, the fault planes are gentle, and small-scale fan deltas are the predominant type of deposits. The hydrocarbon tends to laterally migrate far away and accumulate mianly in structural and lithologic-structural traps. On the other hand, in the convergent end, the fault planes are relatively steep, resulting in small-scale subaqueous fans or large-scale deltas deposited along the major fault, with hydrocarbon accumulating minaly in structural-lithologic traps proximal to the provenances.

Spatial Organization of Innovation in the Oil Equipment Manufacturing Industry: Case of Dongying, China

As innovation and technological change have become increasingly important for the competitiveness and sustainable growth of firms,cooperative innovation is now crucial for traditional industries in the context of globalization.This paper proposes a framework for analyzing the spatial pattern of cooperative innovation for traditional industries in developing countries.Based on in-depth interviews with 35 firms in the oil equipment manufacturing industry in Dongying City,China,this study argues that different firms in the innovation pyramid have various innovation activity preferences and spatial patterns.Firms with high innovation abilities tend to cooperate with various partners that are geographically dispersed and continuously expanding,while firms with inferior abilities usually cooperate with nearby fixed partners.Due to the differences in innovation environment and actor locations,firms tend to make different choices regarding innovation types and models,which highlight the importance of personnel training and basic scientific research at the global scale and practical product research and development at the national scale.Additionally,talent flow is the most important way to realize relationships for firm innovation activity.

Characteristics and origin of abnormally high porosity zones in buried Paleogene clastic reservoirs in the Shengtuo area, Dongying Sag, East China

There are three abnormally high porosity zones developed in buried Paleogene nearshore subaqueous fan and sublacustrine fan clastic＇reservoirs at 2,800-3,200 m, 3,250-3,700 m and 3,900- 4,400 m, respectively, within the Shengtuo area of the Dongying Sag. Here the porosity of reservoirs buried deeper than 4,000 m can still be greater than 20%. Investigation of these three abnormally high porosity （AHP） zones in the 3rd to 4th member of the Paleogene Shahejie Formation in the Shengtuo area was carried out with utilization of core observation, thin section identification, SEM observation, image analysis, core physical property testing and other technical methods. The results show that, the AHP zones in 2,800-3,200 m and 3,250-3,700 m are visible pores primary AHP zones dominated by significant primary intergranular pores （more than 50% of the total porosity）, while secondary pores and micropores in authigenic clays may develop in some reservoirs. AHP reservoirs in the AHP zone of 3,900-4,400 m are dominated by micropores in matrix, visible pores are mainly grain dissolution pores but with low absolute content （〈 1%）, so this zone belongs to the micropores primary AHP zone. The genesis of the three AHP zones was studied to distinguish between porosity enhancement and porosity preservation. Our research shows that, in deeply buried clastic reservoirs in the Shengtuo area, mineral dissolution occurred in a relatively closed diagenetic system with high temperature and high salinity. Reservoir rocks underwent extensive feldspar dissolution, while detrital carbonate grains and carbonate cements show no evidence of extensive dissolution. Although significant feldspar dissolution pores developed, feldspar dissolution enhanced porosity only a little due to the precipitation of almost isovolumetric dissolution products in the nearby primary intergranular pores in forms of authigenic clays and quartz cements. Net enhanced porosity originating from feldspar dissolution is generally less than 0.25%. Thus, the subsurface dissolution has little impact on the mid-deep buried high porosity reservoirs. Reservoirs in braided channels of middle fans in sublacustrine fans and reservoirs in the middle-front of fan bodies of nearshore subaqueous fans provide the basis for the development of AHP zones. The shallow development of fluid overpressure and early hydrocarbon emplacement have effectively retarded compaction and carbonate cementation, so that the high porosity in the superficial layers is preserved in the mid-deep layers. These are the main controlling factors in the development of AHP zones.

Relationship between salt diapirism and faulting in the central structural belt of the Dongying sag,Bohai Gulf basin,China

Many growth faults developed in the Dongying sag of the Jiyang depression of the Bohai Gulf basin, China. These normal growth faults consist of flower-like grabens in the hanging walls of the major faults, accompanied by reverse dragging. The central structural belt is an important structural unit in the Dongying sag, and is divided into a series of small blocks by these faults. These internal blocks can be classified into five structural classes, including parallel blocks, arc-shape blocks, plume-like blocks, ring-radial blocks, and splay blocks. It is shown that these complicated block classes and the 'negative flower-like' fault associations in the central structural belt resulted from regional NNW-SSE extension accompanying local salt diapirism and related reverse dragging, rather than strike-slip faulting. On the basis of the diapirism strength, diapers in the central structural belt can be divided into lower salt ridges and pillows, and blind piercing structures. Diapirs are mainly composed of some salts with a little soft mudstone and gypsum. These structures began forming during deposition of the Sha 3 member and terminated during deposition of the Guangtao formation.

Hydrocarbon accumulation characteristics of beachbar sandstones in the southern slope of the Dongying Sag, Jiyang Depression, Bohai Bay Basin, China

A number of beach-bar sandstone reservoir beds are developed in the upper fourth member of the Eocene Shahejie Formation （Es4s） on the southern slope of the Dongying Sag.Based on the analysis of seismic and logging data,with characterization and petrographic studies of core and cutting samples,this paper analyzes the hydrocarbon accumulation characteristics in two typical blocks of the Boxing and Wangjiagang oilfields,especially reservoir bed heterogeneity and migration conditions that influence oil and gas distribution,calculates the index of reservoir bed quality （IRQ） with a mathematical method,and discusses the relationship between driving force and resistance of hydrocarbon accumulation.Taking into account the characteristics of thin interbeds in beach-bar sandstones,an experimental model simulated the characteristics of hydrocarbon migration and accumulation in thin interbedded sandstones with reservoir bed heterogeneity.The results showed that hydrocarbon distribution and properties were extremely non-uniform.Reservoir bed and migration conditions controlled hydrocarbon accumulation in beach-bar sandstones.IRQ is above 0.4 in the main hydrocarbon region.Sand body distribution,structural configuration and fault systems controlled the direction of regional migration and location of hydrocarbon accumulation.Simulation experiments indicated that the change of driving force for hydrocarbon migration affected selective accumulation mechanisms.Hydrocarbon moved vertically along fault zones to the reservoir and resulted in the distribution of hydrocarbon in the reservoir.Two kinds of hydrocarbon accumulation models exist in the study area.One is a hydrocarbon accumulation model controlled by reservoir bed heterogeneity and the second is a hydrocarbon accumulation model controlled by a complex migration system with faults connecting sandbodies.Finally,different exploration strategies should be adopted for the detailed exploration for beach-bar sandstone reservoirs according to different geological backgrounds.

Distribution of sterane maturity parameters in a lacustrine basin and their control factors:A case study from the Dongying Sag,East China

Fifty samples from the source rocks in Member 3 and Member 4 of the Paleogene Shahejie Formation in the Bohai Bay Basin, East China, were analyzed to investigate the distribution, evolution of the molecular maturity ratios C29ββ/（ββ＋αα） and C2920S/（20S＋20R） and their control factors in the natural geological profile and sequence. The results showed that progressive changes in molecular maturity parameters are associated with major changes in thermal evolution of related biomarkers. Increases in the C29ββ/（ββ＋αα） and C2920S/（20S＋20R） ratios result from the difference in the relative rate between generation and thermal degradation of isomers involved. The samples from a hyper-saline environment below 3.5 km in which evaporitic rocks deposited shows high response of Sr/Ba, Sr/Ca, Fe/ Mn, Pr/n-C17, Ph/n-C18 and gammacerane and low response of Pr/Ph. There presents negative reversal of biomarker maturity C29ββ/（ββ＋αα, C29ββ/（ββ＋αα） and Ts/（Ts＋Ym） in the samples from hypersaline environment, reflecting that the gypsum- halite have negative effect on the isomerization of biomarker and thermal evolution of organic matter. The minerals in evaporites also retard the conventional thermal indicators including vitrinite reflectance （Ro） and pyrolysis peak temperature Tmax at the depth below 3.4 km （i.e. 〉3.4 km）, and these parameters also show the inhibition from overpressure in the range of 2.4-3.4 kin. This result will be helpful in the interpretation and application of molecular maturity parameters for similar saline lacustrine basins.

Distribution and controls of petroliferous plays in subtle traps within a Paleogene lacustrine sequence stratigraphic framework, Dongying Depression, Bohai Bay Basin, Eastern China

The characteristics of petroliferous plays in subtle traps within a sequence stratigraphic framework in the Dongying Depression are investigated in this study.Sand bodies within lowstand systems tracts(LSTs)of sequences,comprising incisedchannel fills,sublacustrine fans,deltas in LSTs,controlled by syndepositional normal faults,and sand bodies within transgressive systems tracts(TSTs)to early highstand systems tracts(HSTs),consisting of beach bars,and turbidites,controlled by the prodelta slope,paleorelief,and syndepositional normal faults,are good subtle reservoirs.Mudstones and shale of deep lake subfacies in TSTs to early HSTs of sequences are source and cap rocks.Abnormal overpressure is the dominant dynamic factor for hydrocarbon migration from source rock to the subtle traps.Normal faults,sand bodies,and unconformities function as conduit systems.Sand bodies distributed in the abnormal overpressure source rocks within LSTs to early HSTs are petroliferous plays in lithologic traps.The petroliferous plays in stratigraphic traps are controlled by unconformities at margins of the Depression.

Effects of Network Closure on Cooperative Innovation: Evidence from Dongying's Petroleum Equipment Industry in China

There are two opposing viewpoints on which kind of network configuration provides a more competitive advantage, namely,network closure or structural holes, with the latter occupying the dominant position in the literature. Using social network analysis and negative binomial regression methods, we graph the co-patent network of Dongying's petroleum equipment industry in China and explore its impact on enterprise innovation. The analysis is based on 17 face-to-face interviews, 31 enterprise questionnaires, and 354 co-patent records from the China State Intellectual Property Office identifying cooperative innovation for the years 1988–2013. We find that this network is closed, controlled by state-owned enterprises, and its closure has positive effects on enterprise innovation performance. This may be related to China's unique industrial development history, state system and policies, regional culture and circumstances, and enterprise characteristics. Therefore, for some industries in specific regions, the advantages usually attributed to structural holes and open innovation may not necessarily apply.

Depositional Environment of Es_4~u and Es_3~l Shales Based on Biomarkers from the Boxing Sag of Dongying Depression, East China

The Boxing Sag is located in the southwest of Dongying Depression, southern Bohai Bay Basin of East China. It is one of the main petroliferous sags in the Dongying Depression, and has two major source rocks, namely the upper 4th Member （Es4u） and lower 3rd Member （Es31） shales of Eocene Shahejie Formation, which are the new exploration targets in recent years. In this study, 16 core samples were collected from Es4u and Es31 shales in the Boxing Sag, and the saturate hydrocarbons were analyzed by gas chromatography （GC） and gas chromatography-mass spectrometry （GC-MS）, respectively. The results show that Es4u shale has obvious phytane and gammacerane predominance, higher concentration of tricyclic terpanes and regular steranes, and very low concentration of 4- methly steranes; Es31 shale has pristane predominance, lower concentration of tricyclic terpanes, gammacerane and regular steranes, and higher concentration of 4-methly steranes. The Es4u shale can be further divided into two types based on the distribution of n-alkanes in gas chromatograms： normal distribution and double peak pattern. The biomarker characteristics and sedimentary facies distribution show that Es4u shale was deposited in the saline-hypersaline semi-deep （Type A Es4u shale, sag center） to shallow （Type B Es4u shale, sag edge） lacustrine environments, Es31 shale was deposited in the freshwater-brackish semi-deep-deep lacustrine environments, and the former sedimentary facies maps of Es4u and Es31 in the Boxing Sag are further modified.

Distribution Patterns of Calcite Cement in the Turbidite Sandstones of the Shahejie Formation in the Dongying Depression,Eastern China

Calcite cements are volumetrically dominant among the most diagenetic constituents in turbidite sandstones of the Paleogene Shahejie Formation in the Dongying Depression.The results show carbonate cements mainly occur in three phases:Calcite I(pre-compaction),Calcite II(post-compaction)and ankerite in the turbidite sandstone.The isotopic composition of Calcite I and Calcite II range from−4.3‰to 4.4‰,−3.5‰to 4.3‰PDB,respectively,suggesting that the calcite cements are mainly derived from the interbedded shales.The early calcite cement precipitated from the mixing of lacustrine and meteoric waters at 38-69℃.The late-phase calcite precipitated from pore waters modified by water-rock interactions at 64-126℃.Two distribution patterns of calcite cements can be identified,depending on their position within the sandstone.The peripheral cementation of the sandstones is near the sand-shale contact.The development of cement is controlled by sandstone thickness and the properties of the interbedded shale.For scattered cementation,the distribution of the calcite cement is not controlled by the sand-shale contact.Calcite cement was preferentially distributed in coarse-grained sandstones,indicating that sandstones with high original permeability are the preferred pathway for the migration of early diagenetic fluids.

A novel redox indicator based on relative abundances of C_(31) and C_(32) homohopanes in the Eocene lacustrine Dongying Depression, East China

A suite of oils and bitumens from the Eocene Shahejie Formation(Es) in Dongying Depression was geochemically characterized to illustrate impact of source input and redox conditions on distributions of pentacyclic terpanes. The Es_(4) developed under highly reducing, sulfidic hypersaline conditions, while Es_(3) formed under dysoxic, brackish to freshwater conditions. Oils derived from Es_(4) are enriched in C_(32) homohopanes(C_(32) H), while those from Es_(3) are prominently enriched in C_(31) homohopanes(C_(31) H). The C_(32) H/C_(31) H ratio shows positive correlation with homohopane index(HHI), gammacerane index, and negative correlation with pristane/phytane ratio, and can be used to evaluate oxic/anoxic conditions during deposition. High C32 H/C_(31) H ratio(> 0.8) is an important characteristic of oils derived from anoxic environments, while low values(< 0.8) indicate dysoxic conditions and extremely low values(< 0.4)indicate strong oxic conditions. The C_(32) H/C_(31) H ratio can be applied for deposition condition diagnosis because carboxyl group of C_(32) hopanoic acids might be reduced to C_(32) homohopanes under anoxic conditions, and oxidized to C_(31) homohopane under oxic conditions. Advantages to use C_(32) H/C_(31) H ratio as redox condition proxy compared to the HHI and gammacerane indexes are wider valid maturity range,less sensitive to biodegradation influence and better differentiating reducing from oxic environments.

Impacts of Future Changes in Heavy Precipitation and Extreme Drought on the Economy over South China and Indochina

Heavy precipitation and extreme drought have caused severe economic losses over South China and Indochina(INCSC)in recent decades.Given the areas with large gross domestic product(GDP)in the INCSC region are distributed along the coastline and greatly affected by global warming,understanding the possible economic impacts induced by future changes in the maximum consecutive 5-day precipitation(RX5day)and the maximum consecutive dry days(CDD)is critical for adaptation planning in this region.Based on the latest data released by phase 6 of the Coupled Model Intercomparison Project(CMIP6),future projections of precipitation extremes with bias correction and their impacts on GDP over the INCSC region under the fossil-fueled development Shared Socioeconomic Pathway(SSP5-8.5)are investigated.Results indicate that RX5day will intensify robustly throughout the INCSC region,while CDD will lengthen in most regions under global warming.The changes in climate consistently dominate the effect on GDP over the INCSC region,rather than the change of GDP.If only considering the effect of climate change on GDP,the changes in precipitation extremes bring a larger impact on the economy in the future to the provinces of Hunan,Jiangxi,Fujian,Guangdong,and Hainan in South China,as well as the Malay Peninsula and southern Cambodia in Indochina.Thus,timely regional adaptation strategies are urgent for these regions.Moreover,from the sub-regional average viewpoint,over two thirds of CMIP6 models agree that maintaining a lower global warming level will reduce the economic impacts from heavy precipitation over the INCSC region.

Resilience effects for household food expenditure and dietary diversity in rural western China

A more resilient livelihood is increasingly recognized as an efficient way to improve vulnerable households’food security and optimize their dietary decisions.This study quantifies rural household resilience in western China,identifies the three pillars(absorptive capacity,adaptive capacity,and transformative capacity)contribution to resilience,and then establishes the estimated Resilience Capacity Index(RCI)linked with food security and dietary diversity supported by the multiple indicator multiple cause(MIMIC)model.Results show that,despite geographical heterogeneity,the RCI consistently increased from 2015 to 2021.Households with a higher RCI inheriting better capacity to deal with risk and shocks are significantly and positively correlated with increasing food expenditure and diversifying food choices.It can be because resilient households will allocate more money to food expenditure instead of saving for livelihood uncertainty.Thus,policymakers can provide more incentives for rural households to adopt more dynamic and effective risk management strategies.This,in turn,could yield positive spillover effects by preventing human capital loss associated with dietary-related chronic diseases and mortality.

The impact of Internet access on household dietary quality:Evidence from rural China

Over the past few decades,the Internet has rapidly diffused across China.The spread of the Internet has had a profound economic and social impact on Chinese rural areas.Existing research shows that Internet access significantly impacts agricultural production and improves smallholder farmers’income.Beyond these,the Internet can affect other dimensions of social welfare.However,research about the impact of Internet access on dietary quality in rural China remains scarce.This study utilizes multi-period panel data from Fixed Observation Point in rural China from 2009 to 2015 to estimate the impact of Internet access on dietary quality and food consumption of rural households and conducts a causal analysis.Regression models with time and household fixed effects allow robust estimation while reducing potential issues of unobserved heterogeneity.The estimates show that Internet access has significantly increased rural household dietary quality(measured by the Chinese Diet Balance Index).Further research finds that Internet access has increased the consumption of animal products,such as aquatic and dairy products.We also examine the underlying mechanisms.Internet access improves dietary quality and food consumption mainly through increasing household income and food expenditure.These results encourage the promotion of Internet access as a valuable tool for nutritional improvements,especially in rural areas.

基于AHP和熵值法China Daily头版封面插画视觉感知评价研究

为了探索报纸插图视觉中哪些因素对读者产生影响,提升阅读者的视觉感知水平,以China Daily头版封面插画为例,从内容层、形式、功能感知三个维度,建构出审美艺术性、创意趣味性、风格独特性、符号内涵性、标题内容区分度、色调内容协调度、色调舒适度、明度舒适度、纯度舒适度、图形大小舒适度、图形造型舒适度、构图留白舒适度等24个指标。结合问卷调查,利用层次分析法和熵值法进行统计分析。研究得出:读者对于China Daily封面插画的感知评价由高到低依次为形式层感知、功能层感知、内容层感知;构图留白舒适度、阅读动态性、叙事直观性等因素对读者视觉感知影响较大;从优化读者文化继承性、字体设计协调度、主题明确性等方面入手,有助于提升读者的视觉阅读体验。

对外传播中的福州城市形象话语建构——以“十三五”期间China Daily报道为例

以“十三五”期间China Daily有关福州的报道为语料,以文化话语研究为理论框架,从话语主体、话语主题和话语形式三个方面探讨福州城市形象的话语建构。研究发现,总体上China Daily对外塑造了一个积极的福州城市形象,其中以文化形象最受关注。此外,与以往同类研究相比,样本媒体进一步传递了普通民众的声音,更多使用人物通讯的报道形式,从而更有效地对外讲述了福州故事、中国故事。本研究对城市形象的话语建构与国际传播具有现实意义。

Differences in spring precipitation over southern China associated with multiyear La Ni?a events

Composite analyses were performed in this study to reveal the difference in spring precipitation over southern China during multiyear La Ni?a events during 1901 to 2015. It was found that there is significantly below-normal precipitation during the first boreal spring, but above-normal precipitation during the second year. The difference in spring precipitation over southern China is correlative to the variation in western North Pacific anomalous cyclone(WNPC), which can in turn be attributed to the different sea surface temperature anomaly(SSTA) over the Tropical Pacific. The remote forcing of negative SSTA in the equatorial central and eastern Pacific and the local air-sea interaction in the western North Pacific are the usual causes of WNPC formation and maintenance.SSTA in the first spring is stronger than those in the second spring. As a result, the intensity of WNPC in the first year is stronger, which is more likely to reduce the moisture in southern China by changing the moisture transport, leading to prolonged precipitation deficits over southern China. However, the tropical SSTA signals in the second year are too weak to induce the formation and maintenance of WNPC and the below-normal precipitation over southern China. Thus, the variation in tropical SSTA signals between two consecutive springs during multiyear La Ni?a events leads to obvious differences in the spatial pattern of precipitation anomaly in southern China by causing the different WNPC response.