Sedimentary lithofacies characteristics and sweet-spot interval characterization of the Sinian Doushantuo Formation in Upper Yangtze Platform, South China

The Sinian Doushantuo Formation is the oldest shale gas reservoir discovered in the world, which contains good shale gas shows as the Eyangye-1 and Zidi-1 wells in the Yichang Region of western Hubei province, China. The shales in the Doushantuo Formation feature considerable thickness (135 m), high gas content (4.83 m^3/t) and high fragile mineral content (up to 75%). Due to the influences of the sedimentary environment, the shale reservoirs here have high dolomitic content (54%) and abruptly changes in vertical lithofacies. Moreover, the characteristics of the shale sweet-spot differ significantly from that in the Wufeng Formation and Longmaxi Formation in southeast Sichuan Basin. A high-resolution sequence stratigraphic correlation was performed on the shales of the Doushantuo Formation at the Eyangye-1 well, Zidi-1 well, Zidi-2 well and some outcrop profiles in Yichang area for the identification of their sedimentary microfacies characteristics. A comprehensive comparative analysis was made by incorporating the elemental geochemistry, wireline and mud logging data of the well to further identify the sweet-spot interval therein. With the analysis of Eyangye-1 well, the sweet-spot interval of the Doushantuo Formation is 3360?3408 m, of which sedimentary microfacies is deepwater reduced environment with many pyrite laminaes, and the TOC is high to 3.42%, the Ro is 3.3%, the organic and matrix pore are well developed and the aperture more than 50 nm, the porosity is 2.7%, the desorption gas content average is 2.16%, and the main mineral is dolomitic (54%) and siliceous quartz (21%). Additionally, these parameters combined with previous studies will shed light on evaluating and characterizing the layers therein, also provide referential geological data for the following exploration and development activities of this shale system.

From Basin Black Shales to Platform Carbonate Rocks:A Study on Sequence Stratigraphy for the Lower Cambrian of the Upper-Yangtze Region in South China

In the Upper-Yangtze region, especially in Guizhou Province and its adjacent areas, the Lower Cambrian is well developed and is marked by a succession from black shales of the basin facies to carbonate rocks of the platform facies. The drowning event of the platform occurring at the turn from Sinian to Cambrian resulted in a set of black shales, i.e. the Niutitang Formation, which makes up the bottom part of the Lower Cambrian. With the shoaling of the sedimentary environment, a set of carbonate rocks, i.e. the Qingxudong Formation, was formed in the top part of the Lower Cambrian. Thus, the Lower Cambrian in the study area makes up one second-order sequence that can be further subdivided into five third-order sequences, and forms a regularly cyclic succession of transgression-regression. There is a regularly vertical stacking pattern for the third-order sequences in the second-order sequence. From bottom to top, the succession of the ＂CS （condensed section） ＋HST （high-stand system tract）＂ of the third-order sequences is changed into the succession of the ＂TST （transgressive system tract）＋CS＋HST＂. Correspondingly, the drowning-type sequence boundary is changed into the exposure-type one. Therefore, both the second-order and the third-order sequences have similar sedimentary-facies architectures. A concomitant with these temporal changes, the Lower Cambrian with a thickness of 1000 m that contains five third-order sequences is changed into a condensed succession that cannot identify third-order sequences toward the southeast with the deepening of the sedimentary environment. According to the elementary features of the third-order sequences, i.e. the regularity o sedimentary-facies successions in space and the synchronism of sedimentary-environment changes in time, the detailed division of the third-order sequences at main logged sections in different paleogeographical background becomes the basis to establish the sequence-stratigraphic framework that can demonstrate two types of facies-changing surface and two types of diachronism in the stratigraphic records. This sequence-stratigraphic framework shows a growing process of the carbonate platform from the base of the condensed succession formed by black shales of basin facies. Resulting from the rapid transgression at the turn from Sinian to Cambrian the ecological space became open, which formed the antecedent condition of paleogeographical setting for ＂the Cambrian Biological Explosion＂. Ultimately, the genetic relationship between the depositional events and the biological-diversity events is very complex and there remain lots of problems that need further research in the future.

The Late Triassic Sequence-Stratigraphic Framework of the Upper Yangtze Region,South China

In the transitional period between the Middle and the Late Triassic, the Indochina orogeny caused two tectonic events in South China：（1） the formation and uplift of the Qinling-Dabie orogenic belt along the northern margin of the South China Plate, due to its collision with the North China Plate; and 2） the development of a 1300-km-wide intra-continental orogen in the southeastern part of the South China Plate, which led to a northwestward movement of the foreland thrust-fold zone. These tectonic events resulted in the ending of the Yangtze Platform, and were a stable paleogeographic factor from the Eidacaran to the end of the Middle Triassic. This platform was characterized by the widespread development of shallow-water carbonates. After the end of the Yangtze Platform, the upper Yangtze foreland basin（or Sichuan foreland basin） was formed during the Late Triassic and became a accumulation site of fluvial deposits that are composed of related strata of the Xujiahe Formation. In western Sichuan Province, the Xujiahe Formation overlies the Maantang Formation shallow-water carbonate rocks of the Xiaotangzi Formation siliciclastic rocks（from shelf shales to littoral facies）. The sequence-stratigraphic framework of the Upper Triassic in the upper Yangtze foreland basin indicates a particular alluvial architecture, characterized by sequences composed of（1） successions of low-energy fluvial deposits of high-accommodation phases, including coal seams, and（2） high-energy fluvial deposits of low-accommodation phases, including amalgamated river-channel sandstones. The spatial distribution of these fluvial deposits belonging to the Xujiahe Formation and its relative strata is characterized by gradual thinning-out, overlapping, and pinching-out toward both the east and south. This sedimentary record therefore expresses a particular sequence-stratigraphic succession of fluvial deposits within the filling succession of the foreland basin. The sequence-stratigraphic framework for the Upper Triassic in the Upper Yangtze region provides a record of the end of the Yangtze Platform and the formation of the upper Yangtze foreland basin.

Acanthomorph Biostratigraphic Succession of the Ediacaran Doushantuo Formation in the East Yangtze Gorges,South China

Large acanthomorphic acritarchs have been found in chert of the Ediacaran Doushantuo Formation at several localities in South China, including the East Yangtze Gorges of Hubei Province,Weng＇an area of Guizhou Province, and elsewhere. However, their potential for biostratigraphic subdivision and correlation of Ediacaran successions is limited by facies control, taphonomic biases,and taxonomic problems. In the Yangtze Gorges, the Doushantuo Formation is generally subdivided into four lithologic members. However, in the Weng＇an area, the Doushantuo Formation comprises just a lower and upper part separated by a mid-Doushantuo erosional surface. In the Yangtze Gorges at the Zhangcunping section, the Doushantuo succession is similar to that at Weng＇an. So far, the correlation between the Yangtze Gorges and Weng＇an area, and elsewhere has been an issue of debate. To resolvethe debate, we selected eight sections in the Yangtze Gorges area and systemically sampled chert nodules of the Doushantuo Formation, focusing in particular on the upper Doushantuo Formation. Our data confirm two different assemblages appearing separately in the second and third members, which are separated by a negative δ13C excursion （EN2）. The lower assemblage is characterized by Tianzhushania and a diverse suite of large acanthomorphic acritarchs. The upper assemblage is distinguished from the lower assemblage, by （1） absence of Tianzhushania; （2） occurrence of abundant,100-150 μm, smooth-walled spherical microfossils; （3） occurrence of highly diverse acanthomorphic acritarchs including species extending from the second member and new forms in this member; （4）occurrence of unnamed new forms of protist; and （5） occurrence of the tubular microfossil Sinocyclocylicus guizhouensis. Since the Tianzhushania-dominated assemblage is not present in Australia, it seems that only the upper acanthomorph assemblage is present and thus the lower Doushantuo acanthomorph assemblage is missing in Australia.

Controlling Factors of Organic Nanopore Development: A Case Study on Marine Shale in the Middle and Upper Yangtze Region, South China

The Upper Ordovician Wufeng-Lower Silurian Longmaxi and the Lower Cambrian Qiongzhusi shales are the major targets for shale gas exploration and development in China.Although the two organic-rich shales share similar distribution ranges and thicknesses,they exhibit substantially different exploration and development results.This work analyzed the nanopore structures of the shale reservoirs in this region.Pore development of 51 shale samples collected from various formations and locations was compared using the petromineralogical,geochemical,structural geological and reservoir geological methods.The results indicate that the reservoir space in these shales is dominated by organic pores and the total pore volume of micropores,mesopores,macropores in different tectonic areas and formations show different trends with the increase of TOC.It is suggested that organic pores of shale can be well preserved in areas with simple structure and suitable preservation conditions,and the shale with smaller maximum ancient burial depth and later hydrocarbongeneration-end-time is also more conducive to pore preservation.Organic pore evolution models are established,and they are as follows:①Organic matter pore development stage,②Early stage of organic matter pore destruction,and③late stage of organic matter pore destruction.The areas conducive to pore development are favorable for shale gas development.Research results can effectively guide the optimization and evaluation of favorable areas of shale gas.

Characteristics and distribution patterns of reef complexes on the carbonate platform margin in deep water areas:the western South China Sea

As a potential oil and gas reservoir, reef complexes have been a research focus from petroleum geologists for a long time. There are favorable conditions for the development of reef complexes in the South China Sea; however, their internal structures, evolution and distribution are still poorly understood. Based on 2D and 3D seismic data, the internal structures and evolution patterns of the reef complexes on the carbonate platform margin in the deep water areas over the western South China Sea were studied in detail. The result shows that two types of reef complexes, i.e., fault controlling platform margin reef complexes and ramp reef complexes have been developed in the study area. The reef complexes have independent or continuous mound or lenticular seismic reflections, with three internal structures （i.e., aggrading, prograding and retrograding structures）. There are different growth rates during the evolution of the reef complexes, resulting in the formation of catch-up reefs, keep-up reefs and quick step reefs. The study also reveals that different platform margin reef complexes have different internal structures and distributions, because of the different platform types. These results may be applied to the exploration and prediction of carbonate platform margin reef complexes in other areas that are similar to the study area.

Seismic Characteristics and Development Patterns of Miocene Carbonate Platform in the Beikang Basin,Southern South China Sea

The Beikang Basin is located in the southern part of the South China Sea(SCS),which is one of most tectonically complex sea areas.It is a deepwater sedimentary basin that was mainly deposited during the Cenozoic era.Owing to data restrictions,the research on carbonate platforms of this area is still in its infancy.High-resolution seismic data are analyzed to identify the Miocene carbonate platforms and reconstruct the architecture and growth history.The carbonate platforms of Beikang Basin began to develop in the Late Oligocene-Early Miocene,were extended in the Middle Miocene,and declined in the Late Miocene.The carbonate platform mainly developed during two periods:the Oligocene to the Early Miocene,and the Middle Miocene.The carbonate platforms that developed in the Middle Miocene were the most prosperous.The Middle Miocene carbonate platform in the Beikang Basin can be divided into three stages.In the first stage,the platforms had wide range which were thin.During the second stage,the platforms had a smaller range that was controlled by faults.In the third stage,the platforms were gradually submerged.The platform structure developed in the Middle Miocene at the Beikang Basin was controlled by the rate of rising/falling of the sea level and the carbonate growth rate.Based on an analysis of these changes and relationship,the platform can be divided into several patterns:retrogradation,submerged,aggradation,progradation,outward with up-stepping,outward with down-stepping,and down-stepping platforms.At the top of the carbonate platforms in the Beikang Basin a set of carbonate wings or mushrooms usually appeared.These were formed during a period of relative sea-level decline.It is believed that the Miocene carbonate platforms in the Beikang Basin are mainly controlled by tectonic and sedimentary environments,and are also affected by terrestrial detritus.

Application of the monitoring and early warning system for internal solitary waves:Take the second natural gas hydrates production test in the South China Sea as an example

Internal solitary waves(ISWs) contain great energy and have the characteristics of emergency and concealment. To avoid their damage to offshore engineering, a new generation of monitoring and early warning system for ISWs was developed using technologies of double buoys monitoring, intelligent realtime data transmission, and automatic software identification. The system was applied to the second natural gas hydrates(NGHs) production test in the Shenhu Area, South China Sea(SCS) and successfully provided the early warning of ISWs for 173 days(from October 2019 to April 2020). The abrupt changes in the thrust force of the drilling platform under the attack of ISWs were consistent with the early warning information, proving the reliability of this system. A total of 93 ISWs were detected around the drilling platform. Most of them occurred during the spring tides in October–December 2019 and April 2020, while few of them occurred in winter. As suggested by the theoretical model, the full-depth structure of ISWs was a typical current profile of mode-1, and the velocities of wave-induced currents can reach 80 cm/s and30 cm/s, respectively, in the upper ocean and near the seabed. The ISWs may be primarily generated from the interactions between the topography and semidiurnal tides in the Luzon Strait, and then propagate westward to the drilling platform. This study could serve as an important reference for the early warning of ISWs for offshore engineering construction in the future.

Development of the Miocene Guangle Carbonate Platform in the South China Sea:Architecture and Controlling Factors

This study investigates the evolution of the Miocene Guangle carbonate platform(or Triton Horst)of the northwestern South China Sea margin.The platform is located at a junction area surrounded by Yinggehai basin,Qiongdongnan basin and Zhongjiannan basin.Well and regional geophysical data allow the identification of the morphologic and stratigraphic patterns.The Guangle carbonate platform was initiated on a tectonic uplift during the Early Miocene.The early platform was limited at Mesozoic granitic basement,pre-Paleogene sediments localized tectonic uplift and was small extension at the beginning stage.While during the Middle Miocene,the carbonate buildup flourished,and grow a thrived and thick carbonate succession overlining the whole Guangle Uplift.The isolated platforms then united afterward and covered an extensive area of several tens of thousands of square kilometers.However,it terminated in the Late Miocene.What are the control factors on the initiation,growth and demise of the Guangle carbonate platform?The onset of widespread carbonate deposits largely reflected the Early Miocene transgression linked with early post-rift subsidence and the opening of the South China Sea.Stressed carbonate growth conditions on the Guangle carbonate platform probably resulted from increased inorganic nutrient input derived from the adjacent uplifted mainland,possibly enhanced by deteriorated climatic conditions promoting platform drowning.Therefore,tectonics and terrigenous input could be two main controlling factors on the development of the Guangle carbonate platforms and main evolution stages.

The Role of Bottom Currents on the Morphological Development Around a Drowned Carbonate Platform,NW South China Sea

The seafloor around carbonate platforms is largely shaped and modified by downslope processes.However,the role of alongslope processes,including bottom currents,on the morphological development of carbonate platforms remains poorly understood.Here,we use high-resolution multibeam bathymetric data and two-dimensional seismic profiles to investigate the detailed sea-floor morphology around the Zhongjianbei carbonate platform(ZCP)in the northwest South China Sea.A series of depositional bodies and erosional channels are identified to the south of the ZCP and are interpreted as contourite drifts and channels resulted from the interaction between bottom currents and bathymetric features.In addition,active fluid seepages have led to the formation of widespread pockmarks on the seafloor.Importantly,the contourite channels and widespread pockmarks also show a close relationship in their distribution.We propose that the contourite channels around the ZCP are evolved from the coalescence of pockmarks under the persistent erosion of bottom currents.Based on the morphological analysis,we reconstruct the past bottom-current pathways around the ZCP that are parallel to the platform slopes and heading to the south.This study provides new insights into the formation of complex bathymetry and helps understanding how bottom currents and active fluid seepages can influence the morphological development around carbonate platforms.

Late Tremadocian(Early Ordovician) reefs on the Yangtze Platform, South China, and their geobiological implications: a synthesis

This study provides an overview and discussion of controls on the distribution of organic reefs during the Early Ordovican Period, in the Yangtze Platform, a region of epicontinental sedimentary rocks in South China. The Yangtze Platform was located in low latitudes during the Early Ordovician and recorded rich and diverse reefs through that time. During the late Tremadocian Epoch, dolomitic and stratiform stromatolites were common in supratidal to intertidal zones of the western Yangtze Platform, while columnar stromatolites formed in deeper waters of the eastern Yangtze Platform. Skeletal-dominated reefs occurred in upper subtidal settings of the central Yangtze Platform. A transition from microbial-dominated to metazoan-dominated reefs with shallowing-upward cycles was evident, indicating that the composition of the main reef-builders was driven mainly by water depth.Increasing metazoan competition during the Great Ordovician Biodiversification Event reduced the abundance of microbial reefs. Sufficient nutrient supply is interpreted to have promoted development of skeletal-dominated reefs locally in shallow settings in the central Yangtze Platform, especially represented by the expansion of abundant solitary fossils of lithistid sponges and Calathium. High salinity environmental settings facilitated the bloom of stromatolites in near-shore locations. Low oxygen content in deep subtidal settings may have led to the absence of skeletal reefs in these habitats, so the mass occurrences of stromatolites was located in the shallower-water central and eastern platform. No keratose sponge-bearing stromatolite can be confirmed across the platform during this interval.

Biodiversification of Late Ordovician Hirnantia Fauna on the Upper Yangtze Platform,South China

The Hirnantia Fauna is a globally-represented,cool water brachiopod fauna that originated and flourished in shallow marine environments at intermediate to low latitudes after the first episode of the end-Ordovician mass extinction.It was well-developed,widely distributed,long in stratigraphical range,and complex in palaeoecological differentiation on the Upper Yangtze Platform of the South China paleoplate,where it has been extensively studied.Qualitative and quantitative analyses show that the FAD of the Hirnantia Fauna in South China becomes stratigraphically higher from nearshore to offshore localities on the Yangtze Platform,while the range of the fauna becomes shorter whereas the taxonomic diversity increases.Over its stratigraphical range the diversity of the Hirnantia Fauna at nearshore localities consistently decreases,but trends in the opposite direction at offshore,deeper water localities.The fauna was represented by different communities,subcommunities or associations with changing environmental factors(such as water depth and substrate) at different localities or horizons.

The Relationship of Land-Ocean Thermal Anomaly Difference with Mei-yu and South China Sea Summer Monsoon

Based on the NCEP/NCAR reanalysis data for the period of 1948-2004 and the monthly rainfall data at 160 stations in China from 1951 to 2004, the relationships among the land-ocean temperature anomaly difference in the mid-lower troposphere in spring （April-May）, the mei-yu rainfall in the Yangtze River- Huaihe River basin, and the activities of the South China Sea summer monsoon （SCSSM） are analyzed by using correlation and composite analyses. Results show that a significant positive correlation exists between mei-yu rainfall and air temperature in the middle latitudes above the western Pacific, while a significant negative correlation is located to the southwest of the Baikal Lake. When the land-ocean thermal anomaly difference is stronger in spring, the western Pacific subtropical high （WPSH） will be weaker and retreat eastward in summer （June-July）, and the SCSSM will be stronger and advance further north, resulting in deficient moisture along the mei-yu front and below-normal precipitation in the mid and lower reaches of the Yangtze River, and vice versa for the weaker difference case. The effects and relative importance of the land and ocean anomalous heating on monsoon variability is also compared. It is found that the land and ocean thermal anomalies are both closely related to the summer circulation and mei-yu rainfall and SCSSM intensity, whereas the land heating anomaly is more important than ocean heating in changing the land-ocean thermal contrast and hence the summer monsoon intensity.

Hydrodynamic Comparison of a Semi-submersible,TLP,and Spar:Numerical Study in the South China Sea Environment

The South China Sea contains tremendous oil and gas resources in deepwater areas. However, one of the keys for deepwater exploration, the investigation of deepwater floating platforms, is very inadequate. In this paper, the authors studied and compared the hydrodynamics and global motion behaviors of typical deepwater platforms in the South China Sea environment. The hydrodynamic models of three main types of floating platforms, e.g. the Semi-submersible, tension leg platform （TLP）, and Truss Spar, which could potentially be utilized in the South China Sea, were established by using the 3-D potential theory. Additionally, some important considerations which significantly influence the hydrodynamics were given. The RAOs in frequency domains as well as global motions in time domains under time-varying wind, random waves, and current in 100-y, 10-y, and 1-y return period environment conditions were predicted, compared, and analyzed. The results indicate that the heave and especially the pitch motion of the TLP are favorable. The heave response of the Truss Spar is perfect and comparable with that of the TLP when the peak period of random waves is low. However, the pitch motion of Truss Spar is extraordinarily lar^er than that of Semi-submersible and TLP.

Characteristics of the Geotectonics in South China and Their Constraints on Primary Diamond

The Asian continent is one of the best places in the world to study continental dynamics. In this region the tectonic framework of the South China plate is related to the activity of the Pacific plate and Indian plate since the Mesozoic. In the South China plate, as the ophiolitic mélange of the middle Proterozoic in the Shaoxing-Yingtan-Tengxian-Beihai faulted zone was confirmed to be a subducting ocean, the evolution of the Yangtze block and Cathaysian block, which are located on both sides of the fault zone, becomes clearer and clearer. A primary diamond deposit, which was first found by Bao Chaomin and his colleagues in Longyou County of Zhejiang Province in 1998, originated from kimberlitoid pipes. The pipes are located in the Cretaceous basin beside this deep fault and the diamond-bearing pipe was formed deep within a favourable geological structure. Diamond there occurs as octahedral crystals without visual impurities. There are more than 100 similar pipes in the area, which have been poorly studied so far, so this area should have great prospects for diamond exploration.

Seismic Imaging and 3D Architecture of Yongle Atoll of the Xisha Archipelago, South China Sea

Yongle atoll in the Xisha(Paracel) Archipelago is an isolated carbonate platform developed on Precambrian metamorphic and Mesozoic volcanic rocks since the early Miocene. To identify the 3D stratigraphic architecture and evolution of this platform, 13 high-resolution seismic profiles and shallow-to-deep water multi-beam data were processed and analyzed to reveal seismic facies, sequence boundary reflectors, seismic units, and platform architecture. Nine types of seismic facies were recognized based on their geometry, which included seismic amplitude, continuity, and termination patterns;additionally, six reflections, i.e., Tg, T60, T50, T40, T30, and T20, were identified in the Cenozoic strata. Five seismic units, SQ1(lower Miocene), SQ2(middle Miocene), SQ3(upper Miocene), SQ4(Pliocene), and SQ5(Quaternary), were identified from bottom to top across the platform. The platform grew rapidly in the middle Miocene and backstepped in the late Miocene–Pliocene. Here, we discuss the developmental characteristics and evolution of the Yongle Atoll, in combination with drilling wells, which can be divided into four stages: the initiation stage in the early Miocene, the flourishing stage in the middle Miocene, the partial-drowning stage in the late Miocene–Pliocene, and modern atoll in the Quaternary.

Geology and mineralization of the supergiant Shimensi granitic-type W-Cu-Mo deposit(1.168 Mt)in northern Jiangxi,South China:A Review

The Shimensi deposit is a recently discovered W-Cu-Mo polymetallic deposit located in the Jiangnan porphyry-skarn W belt in South China.The deposit has a resource of 0.74×10^(6)t of WO_(3)accompanied by 0.4×10^(6)t Cu and 28000 t Mo and other useful components like Ga,making it one of the largest W deposits in the world.This paper is aimed to reveal the ore-controlling mechanisms of the Shimensi deposit,involving the role of the ore-related granites,the tectonic background for its formation,and the metallogenesis model.The systematic geological survey suggests multi-types of alteration are developed in the deposit,mainly including greisenization,potassic-alteration,sericitization,chloritization,and silicification.Drilling engineering data and mining works indicate that the Shimensi deposit consists of two main orebodies of I and II.Therein,the W resource has reached a supergiant scale,and the accompanied Cu,Mo,Au,Bi,Ga,and some other useful components are also of economic significance.The main ore-minerals consist of scheelite,wolframite and chalcopyrite.Disseminated mineralization is the dominant type of the W-Cu-Mo polymetallic orebodies,and mainly distributes in the inner and external contact zone that between the Neoproterozoic biotite granodiorite and the Yanshanian granites.The main orebody occurs at the external contact zone,and the pegmatoid crust near the inner contact zone is an important prospecting marker of the W mineralization.Of them,the disseminated W ores within the wall rock of the Neoproterozoic biotite granodiorite is a new mineralization type identified in this paper.Combining previous geochronological and isotopic data,we propose that the mineralization of the Shimensi deposit is closely related to the intruding of the Yanshanian porphyritic biotite granite and granite porphyry.Geochemical data suggest that the biotite granodiorite is rich in Ca and had provided a large amount of Ca for the precipitation of scheelite in this area.Thus,it is a favorable wall rock type for W mineralization.The Shimensi deposit belongs to granitic-type W polymetallic deposit related to post-magmatic hydrothermal,and the ore-forming fluid was initially derived from the Yanshanian magmas.

Trends of sea surface wind energy over the South China Sea

Studies on climate change typically consider temperature and precipitation over extended periods but less so the wind. We used the Cross-Calibrated Multi-Platform (CCMP) 24-year wind fi eld data set to investigate the trends of wind energy over the South China Sea during 1988-2011. The results reveal a clear trend of increase in wind power density for each of three base statistics (i.e., mean, 90 th percentile and 99 th percentile) in all seasons and for annual means. The trends of wind power density showed obvious temporal and spatial variations. The magnitude of the trends was greatest in winter, intermediate in spring, and smallest in summer and autumn. A greater trend of increase was found in the northern areas of the South China Sea than in southern parts. The magnitude of the annual and seasonal trends over the South China Sea was larger in extreme high events (i.e., 90 th and 99 th percentiles) compared to the mean conditions. Sea surface temperature showed a negative correlation with the variability of wind power density over the majority of the South China Sea in all seasons and annual means, except for winter (41.7%).

Observational and Modeling Studies of Impacts of the South China Sea Monsoon on the Monsoon Rainfall in the Middle-Lower Reaches of the Yangtze River During Summer

Based on the ERA-40 and NCEP/NCAR reanalysis data,the NOAA Climate Prediction Center＇s merged analysis of precipitation（CMAP）,and the fifth-generation PSU/NCAR Mesoscale Model version 3（MM5v3）,we defined a monsoon intensity index over the East Asian tropical region and analyzed the impacts of summer（June-July） South China Sea（SCS） monsoon anomaly on monsoon precipitation over the middle-lower reaches of the Yangtze River（MLRYR） using both observational data analysis and numerical simulation methods.The results from the data analysis show that the interannual variations of the tropical monsoon over the SCS are negatively correlated with the southwesterly winds and precipitation over the MLRYR during June-July.Corresponding to stronger（weaker） tropical monsoon and precipitation,the southwesterly winds are weaker（stronger） over the MLRYR,with less（more） local precipitation.The simulation results further exhibit that when changing the SCS monsoon intensity,there are significant variations of monsoon and precipitation over the MLRYR.The simulated anomalies generally consist with the observations,which verifies the impact of the tropical monsoon on the monsoon precipitation over the MLRYR.This impact might be supported by certain physical processes.Moreover,when the tropical summer monsoon is stronger,the tropical anomalous westerly winds and positive precipitation anomalies usually maintain in the tropics and do not move northward into the MLRYR,hence the transport of water vapor toward southern China is weakened and the southwest flow and precipitation over southern China are also attenuated.On the other hand,the strengthened tropical monsoon may result in the weakening and southward shift of the western Pacific subtropical high through self-adjustment of the atmospheric circulation,leading to the weakening of the monsoon flows and precipitation over the MLRYR.