Geologic,Fluid Inclusion and Stable Isotope Constraints on Mechanisms of Ore Deposition at the Datuanshan Copper Deposit,Middle-Lower Yangtze Valley,Eastern China

The Datuanshan deposit is one of the largest and most representative stratabound copper deposits in the Tongling area,the largest ore district in the Middle-Lower Yangtze River metallogenic belt.The location of the orebodies is controlled by the interlayer-slipping faults between the Triassic and Permian strata,and all the orebodies are distributed in stratiform shape around the Mesozoic quartz monzodiorite dikes.Based on field evidence and petrographic observations,four mineralization stages in the Datuanshan deposit have been identified：the skarn,early quartz-sulfide,late quartzsulfide and carbonate stages.Chalcopytite is the main copper mineral and mainly formed at the late quartz-sulfide stage.Fluid inclusions at different stages were studied for petrography,microthermometry,laser Raman spectrometry and stable isotopes.Four types of fluid inclusions,including three-phase fluid inclusions（type 1）,liquid-rich fluid inclusions（type 2）,vapour-rich fluid inclusions（type 3） and pure vapour fluid inclusions（type 4）,were observed.The minerals from the skarn,early and late quartz-sulfide stages contain all fluid inclusion types,but only type 2 fluid inclusions were observed at the carbonate stage.Petrographic observations suggest that most of the inclusions studied in this paper are likely primary.The coexistence of different types of fluid inclusions with contrasting homogenization characteristics（to the liquid and vapour phase,respectively） and similar homogenization temperatures（the modes are 440-480℃,380-400℃ and 280-320℃ for the skarn,early and late quartz-sulfide stages,respectively） in the first three stages,strongly suggests that three episodes of fluid boiling occurred during these stages,which is supported by the hydrogen isotope data.Laser Raman spectra identified CH_4 at the skarn and early quartz-sulfide stages.Combined with other geological features,the early ore-forming fluids were inferred to be under a relatively reduced environment.The CO_2 component has been identified at the late quartz-sulfide and carbonate stages,indicating that the late ore-forming fluids were under a relatively oxidized environment,probably as a result of inflow of and mixing with meteoric water.In addition,microthermometric results of fluid inclusions and H-O isotope data mdicate that the ore forming fluids were dominated by magmatic water in the early stages（skarn and early quartz-sulfide stages） and mixed with meteoric water in the late stages（late quartz-sulfide and carbonate stages）.The evidence listed above suggests that the chalcopyrite deposition in the Datuanshan deposit probably resulted from the combination of multiepisode fluid boiling and mixing of magmatic and meteoric water.

The 2022 Extreme Heatwave in Shanghai,Lower Reaches of the Yangtze River Valley:Combined Influences of Multiscale Variabilities

In the summer of 2022,China(especially the Yangtze River Valley,YRV)suffered its strongest heatwave(HW)event since 1961.In this study,we examined the influences of multiscale variabilities on the 2022 extreme HW in the lower reaches of the YRV,focusing on the city of Shanghai.We found that about 1/3 of the 2022 HW days in Shanghai can be attributed to the long-term warming trend of global warming.During mid-summer of 2022,an enhanced western Pacific subtropical high(WPSH)and anomalous double blockings over the Ural Mountains and Sea of Okhotsk,respectively,were associated with the persistently anomalous high pressure over the YRV,leading to the extreme HW.The Pacific Decadal Oscillation played a major role in the anomalous blocking pattern associated with the HW at the decadal time scale.Also,the positive phase of the Atlantic Multidecadal Oscillation may have contributed to regulating the formation of the double-blocking pattern.Anomalous warming of both the warm pool of the western Pacific and tropical North Atlantic at the interannual time scale may also have favored the persistency of the double blocking and the anomalously strong WPSH.At the subseasonal time scale,the anomalously frequent phases 2-5 of the canonical northward propagating variability of boreal summer intraseasonal oscillation associated with the anomalous propagation of a weak Madden-Julian Oscillation suppressed the convection over the YRV and also contributed to the HW.Therefore,the 2022 extreme HW originated from multiscale forcing including both the climate warming trend and air-sea interaction at multiple time scales.

THE FLOODS AND DROUGHTS OF THE LOWER YANGTZE VALLEY AND THEIR PREDICTIONS

During Ching dynasty from 1644 to 1911, an interval of 268 years, there occurred in the lower Yangtze valley 197 floods and 156 droughts. The most serious droughts came in 1785, 1814, and 1856; and the most disastrous floods in 1680,

Why Was the Strengthening of Rainfall in Summer over the Yangtze River Valley in 2016 Less Pronounced than that in 1998 under Similar Preceding El Nino Events？Role of Midlatitude Circulation in August

It is widely recognized that rainfall over the Yangtze River valley （YRV） strengthens considerably during the decaying summer of E1 Nifio, as demonstrated by the catastrophic flooding suffered in the summer of 1998. Nevertheless, the rainfall over the YRV in the summer of 2016 was much weaker than that in 1998, despite the intensity of the 2016 E1 Nifio having been as strong as that in 1998. A thorough comparison of the YRV summer rainfall anomaly between 2016 and 1998 suggests that the difference was caused by the sub-seasonal variation in the YRV rainfall anomaly between these two years, principally in August. The precipitation anomaly was negative in August 2016--different to the positive anomaly of 1998.

Anomalous Midsummer Rainfall in Yangtze River-Huaihe River Valleys and Its Association with the East Asia Westerly Jet

In this study, the interannual and interdecadal relationship between midsummer Yangtze River-Huaihe River valley （YHRV） rainfall and the position of the East Asia westerly jet （EAWJ） were investigated. The midsummer YHRV rainfall was found to significantly increase after the 1980s. Moreover, the location of the EAWJ was found abnormally south of the climatic mean during 1980–2008 （ID2） compared to 1951–1979 （ID1）. During ID2, associated with the southward movement of the EAWJ, an anomalous upper-level conver-gence occurred over middle-high latitudes （35° –55° N） and divergence occurred over lower latitudes （～30°N） of East Asia. Correspondingly, anomalous descending and ascending motion was observed in middle-high and lower latitudes along 90°–130° E, respectively, favoring more precipitation over YHRV. On an interan-nual time scale, the EAWJ and YHRV rainfall exhibited similar relationships during the two periods. When the EAWJ was centered abnormally southward, rainfall over YHRV tended to increase. However, EAWJ-related circulations were significantly different during the two periods. During ID1, the circulation of the southward-moving EAWJ exhibited alternating positive–negative–positive distributions from low to middle– high latitudes along the East Asian coast; the most significant anomaly appeared west of the Okhotsk Sea. However, during ID2 the EAWJ was more closely correlated with the tropical and subtropical circulations. Significant differences between ID1 and ID2 were also recorded sea surface temperatures （SSTs）. During ID1, the EAWJ was influenced by the extratropical SST over the northern Pacific; however, the EAWJ was more significantly affected by the SST of the tropical western Pacific during ID2.

Holocene environmental change and archaeology,Yangtze River Valley,China:Review and prospects

Holocene environmental change and environmental archaeology are important components of an international project studying the human-earth interaction system. This paper reviews the progress of Holocene environmental change and environmental archaeology research in the Yangtze River Valley over the last three decades, that includes the evolution of large freshwater lakes, Holocene transgression and sea-level changes, Holocene climate change and East Asian monsoon variation, relationship between the rise and fall of primitive civilizations and environmental changes, cultural interruptions and palaeo- flood events, as well as relationship between the origin of agriculture and climate change. These research components are underpinned by the dating of lacustrine sediments, stalagmites and peat to establish a chronology of regional environmental and cultural evolution. Interdisciplinary and other environment proxy indicators need to be used in comparative studies of archaeological site formation and natural sedi- mentary environment in the upper, middle and lower reaches of the Yangtze River Valley. Modern tech- nology such as remote sensing, molecular bioarchaeology, and virtual reality, should be integrated with currently used dating, geochemical, sedimentological, and palaeobotanical methods of analysis in envi- ronmental archaeology macro- and micro-studies, so as to provide a greater comprehensive insight into Holocene environmental and cultural interaction and change in the Yangtze River Valley area.

Synergistic Contribution of Precipitation Anomalies over Northwestern India and the South China Sea to High Temperature over the Yangtze River Valley

This study explores the characteristics of high temperature anomalies over eastern China and associated influencing factors using observations and model outputs.Results show that more long-duration（over 8 days） high temperature events occur over the middle and lower reaches of the Yangtze River Valley（YRV） than over the surrounding regions,and control most of the interannual variation of summer mean temperature in situ.The synergistic effect of summer precipitation over the South China Sea（SCS） region（18°–27°N,115°–124°E） and the northwestern India and Arabian Sea（IAS） region（18°–27°N,60°–80°E） contributes more significantly to the variation of summer YRV temperature,relative to the respective SCS or IAS precipitation anomaly.More precipitation（enhanced condensational heating） over the SCS region strengthens the western Pacific subtropical high（WPSH） and simultaneously weakens the westerly trough over the east coast of Asia,and accordingly results in associated high temperature anomalies over the YRV region through stimulating an East Asia–Pacific（EAP） pattern.More precipitation over the IAS region further adjusts the variations of the WPSH and westerly trough,and eventually reinforces high temperature anomalies over the YRV region.Furthermore,the condensational heating related to more IAS precipitation can adjust upper-tropospheric easterly anomalies over the YRV region by exciting a circumglobal teleconnection,inducing cold horizontal temperature advection and related anomalous descent,which is also conducive to the YRV high temperature anomalies.The reproduction of the above association in the model results indicates that the above results can be explained both statistically and dynamically.

A Simulation Study of a Heavy Rainfall Process over the Yangtze River Valley Using the Two-Way Nesting Approach

In this study, the major features of a heavy rainfall event in the Yangtze River region on 3-7 June 2011 and its event-related large-scale circulation and predictability were studied. Both observational analysis and model simulation were used, the latter being based on the Weather Research and Forecasting （WRF） model forced by NCEP Global Forecast System （GFS） datasets. It was found that, during 3-5 June, the western Pacific subtropical high apparently extended to the west and was much stronger, and the Indian summer monsoon trough was slightly weaker than in normal years. The east-west oriented shear line over the middle and lower reaches of the Yangtze River was favorable for the transportation and convergence of water vapor, and the precipitation band was located slightly to the south of the shear line. During 6-7 June, the western Pacific subtropical high retreated eastward, while the trough over the Okhotsk Sea deepened. The low vortex in Northeast China intensified, bringing much more cold air to the middle and lower reaches of the Yangtze River, and the shear line over this area moved slightly southward. The convection band moved southward and became weaker, so the rainfall during 6-7 June weakened and was located slightly to the south of the previous precipitation band. Many of the observed features, including background circulation and the distribution and amount of precipitation, were reproduced reasonably by the WRF, suggesting a feasibility of this model for forecasting extreme weather events in the Yangtze River region.

Numerical Simulation of the 1999 Yangtze River Valley Heavy Rainfall Including Sensitivity Experiments with Different SSTA

With the IAP/LASG GOALS model, the heavy rainfall of the summer of 1999 in the Yangtze River valley is simulated with observational sea surface temperature (SST). Comparing the simulations of 1999 with the corresponding ones of 1998 and the sensitivity experiments with different sea surface temperature anomalies (SSTA) at different ocean regions, the relationships between the floods in the Yangtze River valley and the SSTA in the Pacific and Indian Oceans are studied. The results show that the positive SSTA in the tropical Indian Ocean are a major contributor to the heavy rainfall and may be a very important index to predict the heavy rainfall over the Yangtze River valley in the summer. The simulations also show that the relationships between the SSTA in the tropical eastern Pacific and the heavy rainfall in the Yangtze River valley are very complicated, and the heavy rainfall in the Yangtze River valley can occur in both a decaying and an intensifying El Nino event and also in a La Nina event. However, the different SSTA of different periods in the above three cases play different parts.

Correlation Analysis of Persistent Heavy Rainfall Events in the Vicinity of the Yangtze River Valley and Global Outgoing Longwave Radiation in the Preceding Month

Based on the National Oceanic and Atmospheric Administration （NOAA） daily satellite dataset of global outgoing longwave radiation （OLR） for the period of 1974-2004 and the NCEP-NCAR reanalysis for 1971- 2004, the linkage between persistent heavy rainfall （PHR） events in the vicinity of the Yangtze River valley and global OLR leading up to those events （with 1- to 3O-day lag） was investigated. The results reveal that there is a significant connection between the initiation of PHR events over the study area and anomalous convective activity over the tropical Indian Ocean, maritime continent, and tropical western Pacific Ocean. During the 30-day period prior to the onset of PHR events, the major significantly anomalous convective centers have an apparent dipole structure, always with enhanced convection in the west and suppressed convection in the east. This dipole structure continuously shifts eastward with time during the 30-day lead period. The influence of the anomalous convective activity over the tropical oceans on the initiation of PHR events over the study area is achieved via an interaction between tropical and extratropical latitudes. More specifically, anomalous convective activity weakens the Walker circulation cell over the tropical Indian Ocean first. This is followed by a weakening of the Indian summer monsoon background state and the excitation and dispersion of Rossby wave activity over Eurasia. Finally, a major modulation of the large scale background circulation occurs. As a result, the condition of a phase-lock among major large scale circulation features favoring PHR events is established over the study area.

Numerical Simulation of the Relationships between the 1998 Yangtze River Valley Floods and SST Anomalies

With the IAP/LASG GOALS model, the relationships between the floods in the Yangtze River valley arid sea surface temperature anomalies (SSTA) in the Pacific and Indian Oceans in 1998 have been studied. The results show that the model can reproduce the heavy rainfall over the Yangtze River valley in the sum-mer of 1998 forced by global observational sea surface temperatures (SST). The model can also reproduce the observed principal features of the subtropical high anomalies over the western Pacific. The experiments with the observed SST in different ocean areas and different periods have been made. By comparing the ef-fects of SSTA of different ocean areas on the floods, it is found that the SSTA in the Indian Ocean are a ma-jor contributor to the floods, and the results also show that the SSTA in the Indian Ocean and the western Pacific have a much closer relationship with the strong anomalies of the subtropical high over the western Pacific than the SSTA in other concerned areas. The study also indicates that the floods and subtropical high anomalies in the summer of 1998 are more controlled by the simultaneous summertime SSTA than by SSTA in the preceding winter and spring seasons.

Improving Multi-model Ensemble Probabilistic Prediction of Yangtze River Valley Summer Rainfall

Seasonal prediction of summer rainfall over the Yangtze River valley（YRV） is valuable for agricultural and industrial production and freshwater resource management in China, but remains a major challenge. Earlier multi-model ensemble（MME） prediction schemes for summer rainfall over China focus on single-value prediction, which cannot provide the necessary uncertainty information, while commonly-used ensemble schemes for probability density function（PDF） prediction are not adapted to YRV summer rainfall prediction. In the present study, an MME PDF prediction scheme is proposed based on the ENSEMBLES hindcasts. It is similar to the earlier Bayesian ensemble prediction scheme, but with optimization of ensemble members and a revision of the variance modeling of the likelihood function. The optimized ensemble members are regressed YRV summer rainfall with factors selected from model outputs of synchronous 500-h Pa geopotential height as predictors. The revised variance modeling of the likelihood function is a simple linear regression with ensemble spread as the predictor. The cross-validation skill of 1960–2002 YRV summer rainfall prediction shows that the new scheme produces a skillful PDF prediction, and is much better-calibrated, sharper, and more accurate than the earlier Bayesian ensemble and raw ensemble.

Development of a Meteorological and Hydrological Coupling Index for Droughts and Floods along the Yangtze River Valley of China

To comprehensively investigate characteristics of summer droughts and floods in the Yangtze River valley, a meteorological and hydrological coupling index （MHCI） was developed using meteorological and hydro- logical data. The results indicate that： （1） in representing drought/flood information for the Yangtze River valley, the MHCI can reflect composite features of precipitation and hydrological observations; （2） compre- hensive analysis of the interannual phase difference of the precipitation and hydrological indices is important to recognize and predict annual drought/flood events along the valley; the hydrological index contributes more strongly to nonlinear and continuity features that indicate transition from long-term drought to flood conditions; （3） time series of the MHCI from 1960-2009 are very effective and sensitive in reflecting annual drought/flood characteristics, i.e. there is more rainfall or typical flooding in the valley when the MHCI is positive, and vice versa; and （4） verification of the MHCI indicates that there is significant correlation between precipitation and hydrologic responses in the valley during summer; the correlation coefficient was found to reach 0.82, exceeding the 0.001 significance level.

The Effect of Geologic Structures on the Control of Floods in the Middle Yangtze River Valley

This paper discusses the role of geologic structures in the occurrence of floods and how to prevent flood in the middle reaches of the Yangtze River, and gives the author's suggestion that the Luoshan Qiakou be expanded and the land reclaimed from Dongting Lake be returned to the lake in compliance with the law of geology.

Changes of the relationship between population and environment in the Yangtze River Valley in history

The Yangtze River Valley (YRV) occupies a very important position in the course of historical development of the Chinese nation. Since the early stage of Old Stone Age, our forefathers have laboured, lived and multiplied on this land, and left us plentiful of ancient cultural heritage. The fossil of Yunyang Man found in Yunyang of Hubei Province based on determination was two million years ago. That is to say, the populationenvironment relationship in the YRV has gone on at least over two million years. Here we briefly inquire into the history of variations in the development of the populationenvironment relationship in the YRV in the period of feudal society including semicolonial and semifeudal society in modern times.

Economic development and major guarantee projects in the region along the Yangtze River

The region along the Yangtze River is the major exploitation belt and a linkage of eastern and western parts of China. It plays an essential role in the national economic development. Since the implementation of the reform and open door policy, regional economy has got rapidly developed. In the process of development, the region also faces difficulties like energy shortage, backward transportation facilities, grain output reduction, and environmental deterioration. Countermeasures are put forward in the paper to cope with the difficulties.

Distribution of winter-spring snow over the Tibetan Plateau and its relationship with summer precipitationin Yangtze River

The distribution of winter-spring snow cover over the Tibetan Plateau （TP） and its relationship with summer precipitation in the middle and lower reaches of Yangtze River Valley （MLYRV） during 2003-2013 have been investigated with the moderate-resolution imaging spectrometer （MODIS） Terra data （MOD10A2） and precipitation observations. Results show that snow cover percentage （SCP） remains approximately 20% in winter and spring then tails off to below 5% with warmer temperature and snow melt in summer. The lower and highest percentages present a declining tendency while the middle SCP exhibits an opposite variation. The maximum value appears from the middle of October to March and the minimum emerges from July to August. The annual and winter-spring SCPs present a decreasing tendency. Snow cover is mainly situated in the periphery of the plateau and mountainous regions, and less snow in the interior of the plateau, basin and valley areas in view of snow cover frequency （SCF） over the TP. Whatever annual or winter-spring snow cover, they all have remarkable declining tendency during 2003-2013, and annual snow cover presents a decreasing trend in the interior of the TP and increasing trend in the periphery of the TP. Hie multi-year averaged eight-day SCP is negatively related to mean precipitation in the MLYRV. Spring SCP is negatively related to summer precipitation while winter SCP is positively related to summer precipitation in most parts of the MLYRV. Hence, the influence of winter snow cover on precipitation is much more significant than that in spring on the basis of correlation analysis. The oscillation of SCF from southeast to northwest over the TP corresponds well to the beginning,development and cessation of the rain belt in eastern China.

Influences of three oceans on record-breaking rainfall over the Yangtze River Valley in June 2020

The rainfall over the Yangtze River Valley(YRV)in June 2020 broke the record since 1979.Here we show that all three oceans of the Pacific,Indian and Atlantic Oceans contribute to the YRV rainfall in June 2020,but the Atlantic plays a dominant role.The sea surface temperature(SST)anomalies in three oceans are associated with the two vorticity anomalies:negative 200-hPa relative vorticity anomalies over North China(NC)and negative 850-hPa relative vorticity anomalies in the South China Sea(SCS).The rainfall anomalies in the YRV are mainly controlled by atmospheric process associated with the NC vorticity.The positive SST anomalies in May over the western North Atlantic induce positive geopotential height anomalies in June over the mid-latitude North Atlantic,which affect the rainfall anomalies in the YRV by changing the NC vorticity via Atlantic-induced atmospheric wave train across Europe.The Indian Ocean and tropical North Atlantic,as capacitors of Pacific El Niño events in the preceding winter,affect the SCS vorticity associated with the anomalous anticyclone over the SCS and also facilitate the YRV rainfall by providing favorable moisture conditions.This study suggests that the May SST over the western North Atlantic is a good predictor of June rainfall anomalies in the YRV and highlights the important impacts of three-ocean SSTs on extreme weather and climate events in China.

Diagnosing the Dynamic and Thermodynamic Effects for the Exceptional 2020 Summer Rainy Season in the Yangtze River Valley

An exceptional rainy season occurred in the Yangtze River valley of eastern China in June-July 2020.The relative importance of the dynamic and thermodynamic effects on this unusual event is evaluated through the budget equations of moisture and moist static energy(MSE).The moisture budget analysis suggests that the thermodynamic effect contributes to the precipitation anomaly by 8.5%through the advection of abnormal water vapor by mean vertical motion,while the dynamic effect,related to water vapor advection by anomalous vertical motion,has the dominant contribution.The MSE budget analysis further reveals that the anomalous vertical motion is both constrained by the dynamic effect related to changes in atmospheric circulation and the thermodynamic effect related to changes of the atmospheric thermal state,with a ratio of thermodynamic versus total effects estimated at 45.3%.The dynamic effect is linked to the advection of warm and humid air by the abnormal southwesterly wind,which is related with an anomalous anticyclone over the Philippine Sea.The thermodynamic effect is partly induced by the positive advection of anomalous MSE(mainly latent energy)by the mean vertical motion.This analysis of the dynamic and thermodynamic effects is useful to understand the underlying physical mechanisms leading to the unusual rainy season in the Yangtze River valley in summer 2020.It is also helpful to put forward a few speculations on the potential role of global warming whose primary effect is,after all,to change the thermal state of the atmosphere.

Energy Budgets on the Interactions between the Mean and Eddy Flows during a Persistent Heavy Rainfall Event over the Yangtze River Valley in Summer 2010

In this study,a persistent heavy rainfall event（PHRE） that lasted for around 9 days（from 0000 UTC 17 to0000 UTC 26 June 2010） and caused accumulated precipitation above 600 mm over the Yangtze River valley,was reasonably reproduced by the advanced research WRF model.Based on the simulation,a set of energy budget equations that divided the real meteorological field into the mean and eddy flows were calculated so as to understand the interactions between the precipitation-related eddy flows and their background circulations（BCs）.The results indicated that the precipitation-related eddy flows interacted with their BCs intensely during the PHRE.At different layers,the energy cycles showed distinct characteristics.In the upper troposphere,downscaled energy cascade processes appeared,which favored the maintenance of upper-level eddy flows;whereas,a baroclinic energy conversion,which reduced the upper-level jet,also occurred.In the middle troposphere,significant upscaled energy cascade processes,which reflect the eddy flows＇ reactionary effects on their BCs,appeared.These effects cannot be ignored with respect to the BCs＇ evolution,and the reactionary effects were stronger in the dynamical field than in the thermodynamical field.In the lower troposphere,a long-lived quasi-stationary lower-level shear line was the direct trigger for the PHRE.The corresponding eddy flows were sustained mainly through the baroclinic energy conversion associated with convection activities.Alongside this,the downscaled energy cascade processes of kinetic energy,which reflect the direct influences of BCs on the precipitation-related eddy flows,were also favorable.A downscaled energy cascade of exergy also appeared in the lower troposphere,which favored the precipitation-related eddy flow indirectly via the baroclinic energy conversion.