Temporal and spatial evolution of global major grain trade patterns

The complex and volatile international landscape has significantly impacted global grain supply security. This study uses a complex network analysis model to examine the evolution and trends of the global major grain trade from 1990 to 2020, focusing on network topology, centrality ranking, and community structure. There are three major findings. First, the global major grain trade network has expanded in scale, with a growing emphasis on diversification and balance. During the study period, the United States, Canada, China, and Brazil were the core nodes of the network. Grain-exporting countries were mainly situated in Asia, the Americas, and Europe, and importing countries in Asia, Africa, and Europe. Second, a significant increase in the number of high centrality countries with high export capacity occurred, benefiting from natural advantages such as fertile land and favorable climates. Third, the main global grain trade network is divided into four communities, with the Americas-Europe community being the largest and most widespread. The formation of the community pattern was influenced by geographic proximity, driven by the core exporting countries. Therefore, the world needs to enhance the existing trade model, promote the multi-polarization of the grain trade network, and establish a global vision for the future community. Countries and regions should participate actively in global grain trade security governance and institutional reform, expand trade links with other countries, and optimize import and export policies to reduce trade risks.

Three-dimensional numerical analysis of plant-soil hydraulic interactions on pore water pressure of vegetated slope under different rainfall patterns

Understanding the pore water pressure distribution in unsaturated soil is crucial in predicting shallow landslides triggered by rainfall,mainly when dealing with different temporal patterns of rainfall intensity.However,the hydrological response of vegetated slopes,especially three-dimensional(3D)slopes covered with shrubs,under different rainfall patterns remains unclear and requires further investigation.To address this issue,this study adopts a novel 3D numerical model for simulating hydraulic interactions between the root system of the shrub and the surrounding soil.Three series of numerical parametric studies are conducted to investigate the influences of slope inclination,rainfall pattern and rainfall duration.Four rainfall patterns(advanced,bimodal,delayed,and uniform)and two rainfall durations(4-h intense and 168-h mild rainfall)are considered to study the hydrological response of the slope.The computed results show that 17%higher transpiration-induced suction is found for a steeper slope,which remains even after a short,intense rainfall with a 100-year return period.The extreme rainfalls with advanced(PA),bimodal(PB)and uniform(PU)rainfall patterns need to be considered for the short rainfall duration(4 h),while the delayed(PD)and uniform(PU)rainfall patterns are highly recommended for long rainfall durations(168 h).The presence of plants can improve slope stability markedly under extreme rainfall with a short duration(4 h).For the long duration(168 h),the benefit of the plant in preserving pore-water pressure(PWP)and slope stability may not be sufficient.

An intelligent automatic correlation method of oilbearing strata based on pattern constraints:An example of accretionary stratigraphy of Shishen 100 block in Shinan Oilfield of Bohai Bay Basin,East China

Aiming at the problem that the data-driven automatic correlation methods which are difficult to adapt to the automatic correlation of oil-bearing strata with large changes in lateral sedimentary facies and strata thickness,an intelligent automatic correlation method of oil-bearing strata based on pattern constraints is formed.We propose to introduce knowledge-driven in automatic correlation of oil-bearing strata,constraining the correlation process by stratigraphic sedimentary patterns and improving the similarity measuring machine and conditional constraint dynamic time warping algorithm to automate the correlation of marker layers and the interfaces of each stratum.The application in Shishen 100 block in the Shinan Oilfield of the Bohai Bay Basin shows that the coincidence rate of the marker layers identified by this method is over 95.00%,and the average coincidence rate of identified oil-bearing strata reaches 90.02% compared to artificial correlation results,which is about 17 percentage points higher than that of the existing automatic correlation methods.The accuracy of the automatic correlation of oil-bearing strata has been effectively improved.

Study on the pattern of train arrival headway time in high-speed railway

Purpose-The design goal for the tracking interval of high-speed railway trains in China is 3 min,but it is difficult to achieve,and it is widely believed that it is mainly limited by the tracking interval of train arrivals.If the train arrival tracking interval can be compressed,it will be beneficial for China's high-speed railway to achieve a 3-min train tracking interval.The goal of this article is to study how to compress the train arrival tracking interval.Design/methodologylapproach-By simulating the process of dense train groups arriving at the station and stopping,the headway between train arrivals at the station was calculated,and the pattern of train arrival headway was obtained,changing the traditional understanding that the train arrival headway is considered the main factor limiting the headway of trains.Findings-When the running speed of trains is high,the headway between trains is short,the length of the station approach throat area is considerable and frequent train arrivals at the station,the arrival headway for the first group or several groups of trains will exceed the headway,but the subsequent sets of trains will havea headway equal to the arrival headway.This convergence characteristic is obtained by appropriately increasing the running time.Originality/value-According to this pattern,there is no need to overly emphasize the impact of train arrival headway on the headway.This plays an important role in compressing train headway and improving high-speedrailwaycapacity.

Unveiling the Whole-Brain Projection Patterns of Single Neurons in the Mouse Hippocampus

Astudy published in Science on February 2 revealed the spatial connectivity patterns of over 10,000 mouse hippocampal neurons at the mesoscopic level.The study was conducted by teams from the Center for Excellence in Brain Science and Intelligence Technology(CEBSIT),the Institute of Neuroscience(ION)of the Chinese Academy of Sciences(CAS).

Practice patterns among ophthalmic surgeons in treating concomitant oculoplastic conditions in preoperative period:A questionnaire-based study

BACKGROUND Addressing oculoplastic conditions in the preoperative period ensures both the safety and functional success of any ophthalmic procedure.Some oculoplastic conditions,like nasolacrimal duct obstruction,have been extensively studied,whereas others,like eyelid malposition and thyroid eye disease,have received minimal or no research.AIM To investigate the current practice patterns among ophthalmologists while treating concomitant oculoplastic conditions before any subspecialty ophthalmic intervention.METHODS A cross-sectional survey was disseminated among ophthalmologists all over India.The survey included questions related to pre-operative evaluation,anaesthetic and surgical techniques preferred,post-operative care,the use of adjunctive therapies,and patient follow-up patterns.RESULTS A total of 180 ophthalmologists responded to the survey.Most practitioners(89%)felt that the ROPLAS test was sufficient during pre-operative evaluation before any subspecialty surgery was advised.The most common surgical techniques employed were lacrimal drainage procedures(Dacryocystorhinostomy)(63.3%),eyelid malposition repair(36.9%),and ptosis repair(58.7%).Post-operatively,47.7%of respondents emphasized that at least a 4-week gap should be maintained after lacrimal drainage procedures and eyelid surgeries.Sixty-seven percent of ophthalmologists felt that topical anaesthetic procedures should be preferred while performing ocular surgeries in thyroid eye disease patients.CONCLUSION Approximately 50%of ophthalmologists handle prevalent oculoplastic issues themselves,seeking the expertise of an oculoplastic surgeon under particular conditions.Many ophthalmologists still favor using ROPLAS as a preliminary screening method before proceeding with cataract surgery.Eyelid conditions and thyroid eye disease are not as commonly addressed before subspecialty procedures compared to issues like nasolacrimal duct obstruction and periocular infections.

Spatial Pattern and Influencing Factors of China’s Digital Trade Resilience under the Impact of Trade Frictions

In the era of the digital economy,digital trade has demonstrated strong vitality,becoming a crucial driving force for the highquality development of national and regional economies.However,understanding the resilience of digital trade in the face of external crises is an important topic.Taking the backdrop of Sino-US trade friction,this paper constructs a resilience index system for digital trade.It utilizes entropy method,kernel density estimation,and ArcGIS mapping to calculate and visually analyze the resilience of China’s digital trade from 2017 to 2021.Additionally,a Tobit model is constructed to explore the main influencing factors of digital trade resilience patterns.The research findings indicate:1)temporally,during the period of Sino-US trade friction,China’s digital trade resilience shows an overall upward trend,but there are regional differences in resilience levels across the country,with a severe polarization phenomenon.2)Spatially,high resilience is observed in the eastern and central regions of China,while the western and northeastern regions exhibit low resilience.3)From a dimensional perspective,the resistance of digital trade resilience displays a spatial distribution of high values in the east and low values in the west.The recovery force is aggregated along coastal areas,and the renewal force tends to aggregate along the eastern coastline.4)Factors such as economic scale,industrial structure,urbanization rate,government fiscal expenditure,and technological talents significantly promote the enhancement of digital trade resilience.This study reveals the dynamic characteristics and influencing factors of digital trade resilience in responding to external shocks,providing theoretical basis and policy suggestions for enhancing digital trade resilience,and promoting high-quality economic development in China.

Prevalence,risk factors and clinical features of sensory A-V pattern exotropia

AIM:To investigate the potential mechanisms of A-V pattern and evaluate the surgical outcomes used in the treatment of sensory exotropia.METHODS:The medical records of patients with sensory A-V pattern exotropia who underwent strabismus surgery between May 2014 to June 2019 was retrospectively reviewed.The control group included sensory exotropia patients without A-V pattern and concomitant A-V pattern exotropia patients with normal vision who undergone strabismus surgery over this same time period.Ocular alignment,best corrected visual acuity,oblique muscle function,and stereopsis records were collected.RESULTS:Among the 843 eligible patients,91(10.79%;39 males and 52 females)had A-pattern(54,6.4%)or V-pattern(37,4.4%).Age at onset of vision impairment was 4±5y and at the time of surgery was 25±9y.Statistically significant negative correlations were present between impaired visual acuity and the pre-operative exodeviation(r=-0.198,P=0.016)and patterns(r=-0.207,P=0.015).Age at surgery and exodeviation in patients with concomitant A-V pattern exotropia was significantly earlier as compared with that of sensory A-V pattern exotropia and sensory exotropia(both P<0.0001).There were no significant differences in these clinical variables between sensory exotropia with or without A-V pattern.Deviation and pattern were significantly reduced in patients receiving horizontal rectus surgery with or without oblique muscle surgery(both P<0.0001).CONCLUSION:The prevalence of sensory A-V pattern exotropia in our study is 10.79%.Visual acuity represents an important factor contributing to the occurrence and development of A-V pattern.Isolated horizontal rectus surgery can provide a good option for the correction of sensory A-V pattern exotropia.

Optimization of production well patterns for natural gas hydrate reservoir: Referring to the results from production tests and numerical simulations

Natural gas hydrate is a clean energy source with substantial resource potential.In contrast to conventional oil and gas,natural gas hydrate exists as a multi-phase system consisting of solids,liquids,and gases,which presents unique challenges and complicates the mechanisms of seepage and exploitation.Both domestic and international natural gas hydrate production tests typically employ a single-well production model.Although this approach has seen some success,it continues to be hindered by low production rates and short production cycles.Therefore,there is an urgent need to explore a new well network to significantly increase the production of a single well.This paper provides a comprehensive review of the latest advancements in natural gas hydrate research,including both laboratory studies and field tests.It further examines the gas production processes and development outcomes for single wells,dual wells,multi-branch wells,and multi-well systems under conditions of depressurization,thermal injection,and CO_(2) replacement.On this basis,well types and well networks suitable for commercial exploitation of natural gas hydrate were explored,and the technical direction of natural gas hydrate development was proposed.The study shows that fully exploiting the flexibility of complex structural wells and designing a well network compatible with the reservoir is the key to improving production from a single well.Moreover,multi-well joint exploitation is identified as an effective strategy for achieving large-scale,efficient development of natural gas hydrate.

Territorial Ecological Restoration with a High-carbon Storage Focus in the Beibu Gulf Urban Agglomeration of China:Insights from Carbon Metabolism Spatial Security Patterns

This study focuses on urgent research on restoring and enhancing carbon storage capacity in the Beibu Gulf Urban Agglomer-ation of China,a key area in the‘Belt and Road’Initiative,which aligns with carbon peaking and neutrality goals.This research ana-lyzes the spatial characteristics of carbon metabolism from 2000 to 2020 and uses models to identify stable carbon sink areas,positive carbon flow corridors,and carbon sequestration nodes.The goal is to construct a carbon metabolism spatial security pattern(CMSSP)and propose territorial ecological restoration strategies under different development demand scenarios.The results show the following:1)in 2020,the study area’s carbon sink decreased by 8.29×10^(4) t C/yr compared with that in 2010 and by 10.83×10^(4) t C/yr compared with that in 2000.High-carbon sinks were found mainly in mountainous areas,whereas low-carbon sinks are concentrated in urban con-struction land,rural residential areas,and land margins.2)From 2000 to 2020,the spatial security pattern of carbon metabolism tended to be‘high in the middle of the east and west and low in the gulf.’In 2000,2010,and 2020,16 stable carbon sinks were identified.The carbon energy flow density in Guangxi was greater than that in Guangdong and Hainan,with positive carbon flow corridors located primarily in Guangxi and Guangdong.The number of carbon sequestration nodes remained stable at approximately 15,mainly in Guangxi and Hainan.3)Scenario simulations revealed that under the Nature-based mild restoration scenario,the carbon sink rate will reach 611.85×10^(4) t C/yr by 2030 and increase to 612.45×10^(4) t C/yr by 2060,with stable carbon sinks increasing to 18.In the restora-tion scenario based on Anti-globalization,the carbon sink will decrease from 610.24×10^(4) t C/yr in 2030 to 605.19×10^(4) t C/yr in 2060,with the disappearance of some positive carbon flow corridors and stable carbon sinks.Under the Human-based sustainable restoration scenario,the carbon sink area will decrease from 607.00×10^(4) t C/yr in 2030 to 596.39×10^(4) t C/yr in 2060,with carbon sink areas frag-menting and positive carbon flow corridors becoming less dense.4)On the basis of the current and predicted CMSSPs,this study ex-plores spatial ecological restoration strategies for high-carbon storage areas in bay urban agglomerations at four levels:the land control region,urban agglomeration structure system,carbon sink structure and bay structure control region.

Field Experiment for the Effects of Rice Straw Returning and Seeding Pattern on Wheat Seedling Emergence and Grain Yield

In order to study the effect of rice straw returning and seeding patterns on seedling emergence and grain yield, field experiment was conducted to investi- gate the effects of straw mechanized returning and different seeding patterns on e- mergence rate, emergence uniformity and yield traits of wheat after rice. The results were as follows： in rice straw removal treatments, the emergence rate of mechani- cal seeding in drill was lower than that of mechanical uniform planting and manual broadcast sowing, which were 51.84%, 90.89% and 88.87%, respectively; the emer- gence uniformity of manual broadcast sowing was inferior to mechanical seeding in drill and mechanical uniform planting, which were 0.49, 0.26 and 0.23, respectively. As for the treatments with rice straw returning to the field, the emergence rate and emergence uniformity all decreased in the three seeding patterns, of which mechan- ical seeding in drill dropped markedly with emergence rate decreased by 36.54%. The emergence rate and emergence uniformity affected grain yield by affecting pan- icle, grains per spike and 1 000-grain weight. The grain yield for the treatment with rice straw removal was 6 091.34 kg/hm2, while that with rice straw returning to field was 6 476.20 kg/hm2, and both were higher than the yields of the other two seed- ing patterns. Therefore, mechanical uniform planting was？recommended for its higher emergence rate, better emergence uniformity, which was conductive to increase grain yield in wheat after rice production with rice straw returning to field.

Spatial pattern of dominant tree species of the secondary monsoon rain forest in Lianjiang, Guangdong Province

Based on the summed dominance ratios of species in sample plots, the first three dominant species (Litchi chinensis, Elaeocarpus sylvestris and Canarium album) of the secondary monsoon rain forest of Mt. Royal Shoe in Lianjiang City, western Guangdong, were chosen for analyzing their spatial distribution pattern with the analysis methods such as frequency models of Poisson Distribution, Two Negative Items Distribution, Neyman Distribution, aggregate indexes, Taylor exponential equation and Iwao’s equation modeling. The results showed that these three species distributed in the congregate spatial pattern. Litchi chinensis and Elaeocarpus sylvestris had the characteristic of basic congregate population and attractive characteristic between their plants. The patterns for Canarium album may change and become more evenly distributed with the increase of density. The overall species spatial pattern also depended on the conservation of the secondary monsoon rain forest besides it was affected by the species reproduction characteristics and its growing environment. The congregate spatial patterns of three dominant species showed that it is important to conserve forest urgent conservation of the forest.

Patterned Dual pn Junctions Restraining Substrate Loss of an On-Chip Inductor

Dual pn junctions in lateral and vertical directions are formed by diffusing the p^＋ on the patterned n-well in standard CMOS technology, which are inserted under the inductor in order to reduce the currents in the substrate induced by the electromagnetic field from the inductor. The thickness of high resistance is not equivalent to the width of the depletion region of the vertical pn junctions,but the depth of the bottom pn junction in the substrate are both proposed and validated. For the first time, through the grounded p^＋-diffusion layer shielding the suhstrate from the electric field of the inductor, the width of the depletion regions of the lateral and vertical pn junctions are changed by increasing the voltage applied to the n wells. The quality factor is improved or reduced with the thickness of high resistance by 19%. This phenomenon validates the theory that the pn junction substrate isolation can reduce the loss caused by the currents in the substrate induced by the electromagnetic field from the inductor.

Simulation and Projection of Monso on Rainfall and Rain Patterns over Eastern China under Global Warming by RegCM3

The authors investigate possible changes of monsoon rainfall and associated seasonal (June-JulyAugust) anomaly patterns over eastern China in the late 21st century under the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios (SRES) A2 emission scenario as simulated by a high-resolution regional climate model (RegCM3) nested in a general circulation model (FvGCM/CCM3).Two sets of multi-decadal simulations are performed at 20-km grid spacing for present day and future climate conditions.Results show that the RegCM3 reproduces the mean rainfall distribution;however the evolution of the monsoon rain belt from South China to North China is not well simulated.Concerning the rain pattern classifications,RegCM3 overestimates the occurrence of Pattern 1 (excessive rainfall in northern China) and underestimates that of Pattern 2 (increased rainfall over the Huai River basin).Under future climate conditions,RegCM3 projects less occurrence of Pattern 1,more of Pattern 2,and little change of Pattern 3 (rainfall increase along the Yangtze River).These results indicate that there might be increased rainfall over the Huai-Yellow River area and reduced rainfall over North China in the future,while rainfall over the lower reaches of the Yangtze River basin is not modified significantly.Uncertainties exist in the present study are also discussed.

Teleconnection between Sea Ice in the Barents Sea in June and the Silk Road,Pacific–Japan and East Asian Rainfall Patterns in August

In contrast to previous studies that have tended to focus on the influence of the total Arctic sea-ice cover on the East Asian summer tripole rainfall pattern, the present study identifies the Barents Sea as the key region where the June sea-ice variability exerts the most significant impacts on the East Asian August tripole rainfall pattern, and explores the teleconnection mechanisms involved. The results reveal that a reduction in June sea ice excites anomalous upward air motion due to strong near-surface thermal forcing, which further triggers a meridional overturning wave-like pattern extending to midlatitudes.Anomalous downward motion therefore forms over the Caspian Sea, which in turn induces zonally oriented overturning circulation along the subtropical jet stream, exhibiting the east–west Rossby wave train known as the Silk Road pattern. It is suggested that the Bonin high, a subtropical anticyclone predominant near South Korea, shows a significant anomaly due to the eastward extension of the Silk Road pattern to East Asia. As a possible descending branch of the Hadley cell, the Bonin high anomaly ultimately triggers a meridional overturning, establishing the Pacific–Japan pattern. This in turn induces an anomalous anticyclone and cyclone pair over East Asia, and a tripole vertical convection anomaly meridionally oriented over East Asia. Consequently, a tripole rainfall anomaly pattern is observed over East Asia. Results from numerical experiments using version 5 of the Community Atmosphere Model support the interpretation of this chain of events.

Relationship Between Persistent Heavy Rain Events in the Huaihe River Valley and the Distribution Pattern of Convective Activities in the Tropical Western Pacific Warm Pool

Using daily outgoing long-wave radiation （OLR） data from the National Oceanic and Atmospheric Administration （NOAA） and the National Center for Environmental Prediction/National Center for Atmospheric Research （NCEP/NCAR） reanalysis data of geopotential height fields for 1979-2006, the relationship between persistent heavy rain events （PHREs） in the Huaihe River valley （HRV） and the distribution pattern of convective activity in the tropical western Pacific warm pool （WPWP） is investigated. Based on nine cases of PHREs in the HRV, common characteristics of the West Pacific subtropical high （WPSH） show that the northern edge of the WPSH continues to lie in the HRV and is associated with the persistent ＂north weak south strong＂ distribution pattern of convective activities in the WPWP. Composite analysis of OLR leading the circulation indicates that the response of the WPSH to OLR anomaly patterns lags by about 1-2 days. In order to explain the reason for the effects of the distribution pattern of convective activities in the WPWP on the persistent northern edge of the WPSH in the HRV, four typical persistent heavy and light rain events in the Yangtze River valley （YRV） are contrasted with the PHREs in the HRV. The comparison indicates that when the distribution pattern of the convective activities anomaly behaves in a weak （strong） manner across the whole WPWP, persistent heavy （light） rain tends to occur in the YRV. When the distribution pattern of the convective activities anomaly behaves according to the ＂north weak south strong＂ pattern in the WPWP, persistent heavy rain tends to occur in the HRV. The effects of the ＂north weak south strong＂ distribution pattern of convective activities on PHREs in the HRV are not obvious over the seasonal mean timescale, perhaps due to the non-extreme status of convective activities in the WPWP.

Quantifying spatial scale of positive and negative terrains pattern at watershed-scale:Case in soil and water conservation region on Loess Plateau

The positive and negative terrains(P-N terrains) widely distributed across China's Loess Plateau constitute the dual structure characteristic of loess landforms. Analysis of loess P-N terrains at the watershed scale can serve to elucidate the structural characteristics and spatial patterns of P-N terrains, which benefits a better understanding of watershed evolution and suitable scales for loess landform research. The Two-Term Local Quadrat Variance Analysis(TTLQV) is calculated as the average of the square of the difference between the block totals of all possible adjacent pairs of block size, which can be used to detect both the scale and the intensity of landscape patches(e.g., plant/animal communities and gully networks). In this study, we determined the latitudinal and longitudinal spatial scale of P-N terrain patterns within 104 uniformly distributed watersheds in our target soil and water conservation region. The results showed that TTLQV is very effective for examining the scale of P-N terrain patterns. There were apparently three types of P-N terrain pattern in latitudinal direction(i.e., Loess Tableland type, Loess Hill type, and Transitional Form between Sand and Loess type), whereas there were both lower and higher values for P-N terrain pattern scales in all loess landforms in the longitudinal direction. The P-N terrain pattern alsoclearly presented anisotropy, suggesting that gully networks in the main direction were well-developed while others were relatively undeveloped. In addition, the relationships between the first scales and controlling factors(i.e., gully density, nibble degree, watershed area, mean watershed slope, NDVI, precipitation, loess thickness, and loess landforms) revealed that the first scales are primarily controlled by watershed area and loess landforms. This may indicate that the current spatial pattern of P-N terrains is characterized by internal force. In selecting suitable study areas in China' Loess Plateau, it is crucial to understand four control variables: the spatial scale of the P-N terrain pattern, the watershed area, the main direction of the watershed, and the loess landforms.

Spatial pattern and utility of Populus euphratica seed rain:a simulation study combined with field investigations

Seed dispersal is a fundamental process affecting destinies of seeds and seedlings, as well as regeneration dynamics and distribution patterns of communities. Recently however, declining Populus euphratica forests have failed to regenerate by seeding, while the spatial pattern and utility of their seed rains are unclear. In this study, we designed a model to simulate seed rains based on field investigations by fitting our observations to a normal distribution and testing the model with data from three years, with ac- ceptable results. We examined the simulated results of dispersed seeds patterns on the classification of three factors, i.e., density of Sophora alopecuroides, surface soil moisture and surface soil salinity. The results of seed rain simulation show that over 70% of seeds were dispersed and confined to each of the three plots where their mother trees located. The proportion of 3：7 seeds dispersed inside and outside each plots remained largely unaltered. The differences in the amounts of dispersed seed among the different levels of each of the factors were not significant, although the distributing pattern of P. euphratica in each plot varied. Therefore, in P. eu- phratica communities, the amount of seed does not become a constraint in subsequent germination, although the surface environment does. We conclude that successful P. euphratica seed regeneration relies on less than 30% of seeds dispersed over longer distance to colonize favorable growth habitats.

Dominant Patterns of Summer Rainfall Anomalies in East China during 1951-2006

The dominant patterns of summer rainfall anomalies in East China were studied using Empirical Orthogonal Function （EOF） analysis. The results indicate that after the late 1970s, the first and second dominant patterns switched. During the period before the late 1970s, the spatial pattern of the first （second） dominant mode was the ＂Yangtze River pattern＂ （the ＂South China pattern＂）, but this changed to the ＂South China pattern＂ （the ＂Yangtze River pattern＂） after the late 1970s. This decadal change in the dominant patterns resulted from a significant decadal change in summer rainfall over South China after the late 1970s, i.e., a negative phase during 1978-1992 and a positive phase during 1993-2006. When the decadal variation of rainfall in East China is omitted from the analysis, the first and second dominant patterns represent the ＂Yangtze River pattern＂ and the ＂South China pattern＂, respectively. These results suggest that when decadal variation is included, the rainfall in China may be dominated by one mode during certain periods and by another in other periods. For the interannual variability when decadal variation is excluded, however, the first and second modes can be easily distinguished, and their order has been stable since at least 1951.

Characteristics of the Summer Time Rainfall Patterns over China and the Indian Ocean Sea Surface Temperature Anomalies

Using the monthly summer (June to August) precipitation data over China from 1979 to 1998,and the SST data in Indian Ocean of the overlapping periods,we have analyzed the spatial patterns as well as their temporal evolution of the summer precipitation,along with the relationships between the precipitation over China and the SST in Indian Ocean,with the EOF and SVD methods respectively.The important results are:several canonical anomalous summer precipitation patterns have been identified.The summer SST in Indian Ocean is positively correlated with the simultaneous precipitation in the Yangtze River and Huai River Basin,while negatively with that in other parts of China.