Based on the NCEP/ NCAR reanalysis data the interannual variability of the East Asian winter mon-soon (EAWM) is studied with a newly defined EAWM intensity index. The marked features for a strong (weak) winter monsoon...Based on the NCEP/ NCAR reanalysis data the interannual variability of the East Asian winter mon-soon (EAWM) is studied with a newly defined EAWM intensity index. The marked features for a strong (weak) winter monsoon include strong (weak) northerly winds along coastal East Asia, cold (warm) East Asian continent and surrounding sea and warm (cold) ocean from the subtropical central Pacific to the trop-ical western Pacific, high (low) pressure in East Asian continent and low (high) pressure in the adjacent ocean and deep (weak) East Asian trough at 500 hPa. These interannual variations are shown to be closely connected to the SST anomaly in the tropical Pacific, both in the western and eastern Pacific. The results suggest that the strength of the EAWM is mainly influenced by the processes associated with the SST anom-aly over the tropical Pacific. The EAWM generally becomes weak when there is a positive SST anomaly in the tropical eastern Pacific (El Ni?o), and it becomes strong when there is a negative SST anomaly (La Ni?a). Moreover, the SST anomaly in the South China Sea is found to be closely related to the EAWM and may persist to the following summer. Both the circulation at 850 hPa and the rainfall in China confirm the connection between the EAWM and the following East Asian summer monsoon. The possible reason for the recent 1998 summer flood in China is briefly discussed too. Key words East Asian winter monsoon - Interannual variability - SST - Summer monsoon This study was supported by “ National Key Programme for Developing Basic Sciences” G1998040900 part 1, and by key project (KZ 952-S1-404) of Chinese Academy of Sciences.展开更多
In this paper, results from a pilot study for the South China Sea Monsoon Experiment are reported. Based on analyses of 9 years of pentad and monthly mean data, the climatology of subseasonal features and interannual ...In this paper, results from a pilot study for the South China Sea Monsoon Experiment are reported. Based on analyses of 9 years of pentad and monthly mean data, the climatology of subseasonal features and interannual variability of the Southeast Asian monsoon (SEAM) are documented. The present analysis is focused on the sudden onset of the South China Sea monsoon and its relation to the atmospheric and oceanic processes on the entire Asian monsoon region. \ \ It is found that the onset of the SEAM occurs around mid-May, signaling the earliest stage of the entire Asian summer monsoon system. The establishment of monsoon rainfall over the South China Sea is abrupt, being accompanied by substantial changes in the large scale atmospheric circulation and sea surface temperature in the adjacent oceans. The onset and fluctuations of SEAM involve the interaction and metamorphosis of the large scale convection over the Indo-China, the South China Sea and the southern Bay of Bengal. Results show that the onset time of the SEAM differs greatly from one year to another. The delayed (advanced) onset of the monsoon may be related to basin-wide warm (cold) events of the Pacific and Indian Oceans. We also present evidence showing that the SEAM fluctuations in May may foreshadow the development of the full-scale Asian summer monsoon during the subsequent months.展开更多
The impact of E1 Nino on the precipitation in China for different seasons are investigateddiagnostically. It is found that E1 Nino can influence the precipitation in China significantly duringits mature phase. In the ...The impact of E1 Nino on the precipitation in China for different seasons are investigateddiagnostically. It is found that E1 Nino can influence the precipitation in China significantly duringits mature phase. In the Northern winter, spring and autumn, the positive precipitation anomaliesare found in the southern part of China during the E1 Nino mature phase. In the Northernsummer, the patterns of the precipitation anomalies in the E1 Nifio mature phase are different fromthose in the other seasons. The negative precipitation anomalies appear in both southern andnorthern parts of China, while in between around the lower reaches of the Yangtze River and theHuaihe River valleys the precipitation anomalies tend to be positive.In the Northern winter, spring and autumn, the physical process by which E1 Nino affects theprecipitation in the southern part of China can be explained by the features of the circulationanomalies over East Asia during the E1 Nino mature phase (Zhang et al. 1996). The appearance ofan anticyclonic anomaly to the north of the maritime continent in the lower troposphere during theE1 Nino mature phase intensifies the subtropical high in the western Pacific and makes it shiftwestward. The associated southwesterly flow is responsible for the positive precipitation anomaliesin the southern part of China. In the Northern summer, the intensified western Pacific subtropicalhigh covers the southeastern periphery of China so that the precipitation there becomes less. In addition, the weakening of the indian monsoon provides less moisture inflow to the northern part ofChina.展开更多
The transition of the global atmospheric circulation in the end of 1970's can clearly be detected in the atmospheric temperature, wind velocity, and so on. Wavelet analysis reveals that the temporal scale of this ...The transition of the global atmospheric circulation in the end of 1970's can clearly be detected in the atmospheric temperature, wind velocity, and so on. Wavelet analysis reveals that the temporal scale of this change is larger than 20 years. Studies in this work indicate that the trend of the transition over the mid-latitude Asia is opposite to that of global average for some variables at the middle troposphere. Another finding of this research is that the African-Asian monsoon circulation is weaker and the trade wind over the tropical eastern Pacific is weaker as well after this transition. Such a signal may be found in the summer precipitation over China as well. Key words Asian monsoon circulation - Weakening - Transition This research was supported by the key project of Chinese Academy of Sciences under Contract KZCX2-203 and the key program of the National Natural Science Foundation of China under Contract 49894170.展开更多
ENSO induces coherent climate anomalies over the Indo-western Pacific, but these anomalies outlast SST anomalies of the equatorial Pacific by a season, with major effects on the Asian summer monsoon. This review provi...ENSO induces coherent climate anomalies over the Indo-western Pacific, but these anomalies outlast SST anomalies of the equatorial Pacific by a season, with major effects on the Asian summer monsoon. This review provides historical accounts of major milestones and synthesizes recent advances in the endeavor to understand summer variability over the Indo-Northwest Pacific region. Specifically, a large-scale anomalous anticyclone （AAC） is a recurrent pattern in post-E1 Nifio summers, spanning the tropical Northwest Pacific and North Indian oceans. Regarding the ocean memory that anchors the summer AAC, competing hypotheses emphasize either SST cooling in the easterly trade wind regime of the Northwest Pacific or SST warming in the westerly monsoon regime of the North Indian Ocean. Our synthesis reveals a coupled ocean- atmosphere mode that builds on both mechanisms in a two-stage evolution. In spring, when the northeast trades prevail, the AAC and Northwest Pacific cooling are coupled via wind-evaporation-SST feedback. The Northwest Pacific cooling persists to trigger a summer feedback that arises from the interaction of the AAC and North Indian Ocean warming, enabled by the westerly monsoon wind regime. This Indo-western Pacific ocean capacitor （IPOC） effect explains why E1 Nifio stages its last act over the monsoonal Indo-Northwest Pacific and casts the Indian Ocean warming and AAC in leading roles. The IPOC displays interdecadal modulations by the ENSO variance cycle, significantly correlated with ENSO at the turn of the 20th century and after the 1970s, but not in between. Outstanding issues, including future climate projections, are also discussed.展开更多
On the interannual timescale, the meridional displacement of the East Asian upper-tropospheric jet stream (EAJS) is significantly associated with the rainfall anomalies in East Asia in summer. In this study, using the...On the interannual timescale, the meridional displacement of the East Asian upper-tropospheric jet stream (EAJS) is significantly associated with the rainfall anomalies in East Asia in summer. In this study, using the data from the National Centers for Environmental Prediction-Department of Energy (NCEP/DOE) reanalysis-2 from 1979 to 2002, the authors investigate the interannual variations of the EAJS's meridional displacement in summer and their associations with the variations of the South Asian high (SAH) and the western North Pacific subtropical high (WNPSH), which are dominant circulation features in the upper and lower troposhere, respectively. The result from an EOF analysis shows that the meridional displacement is the most remarkable feature of the interannual variations of the EAJS in each month of summer and in summer as a whole. A composite analysis indicates that the summer (June-July-August, JJA) EAJS index, which is intended to depict the interannual meridional displacement of the EAJS, is not appropriate because the anomalies of the zonal wind at 200 hPa (U200) in July and August only, rather than in June, significantly contribute to the summer EAJS index. Thus, the index for each month in summer is defined according to the location of the EAJS core in each month. Composite analyses based on the monthly indexes show that corresponding to the monthly equatorward displacement of the EAJS, the South Asian high (SAH) extends southeastward clearly in July and August, and the western North Pacific subtropical high (WNPSH) withdraws southward in June and August.展开更多
Recent advances in studies of the structural characteristics and temporal-spatial variations of the East Asian monsoon （EAM） system and the impact of this system on severe climate disasters in China are reviewed. Pr...Recent advances in studies of the structural characteristics and temporal-spatial variations of the East Asian monsoon （EAM） system and the impact of this system on severe climate disasters in China are reviewed. Previous studies have improved our understanding of the basic characteristics of horizontal and vertical structures and the annual cycle of the EAM system and the water vapor transports in the EAM region. Many studies have shown that the EAM system is a relatively independent subsystem of the Asian- Australian monsoon system, and that there exists an obvious quasi-biennial oscillation with a meridional tripole pattern distribution in the interannual variations of the EAM system. Further analyses of the basic physical processes, both internal and external, that influence the variability of the EAM system indicate that the EAM system may be viewed as an atmosphere-ocean-land coupled system, referred to the EAM climate system in this paper. Further, the paper discusses how the interaction and relationships among various components of this system can be described through the East Asia Pacific （EAP） teleconnection pattern and the teleconnection pattern of meridional upper-tropospheric wind anomalies along the westerly jet over East Asia. Such reasoning suggests that the occurrence of severe floods in the Yangtze and Hualhe River valleys and prolonged droughts in North China are linked, respectively~ to the background interannual and interdecadal variability of the EAM climate system. Besides, outstanding scientific issues related to the EAM system and its impact on climate disasters in China are also discussed.展开更多
Based on the EAP (East Asia/Pacific) teleconnection in the summer circulation anomalies over the Northern Hemisphere, an index measuring the strength of the East Asian summer monsoon, i.e., the so-called EAP index, is...Based on the EAP (East Asia/Pacific) teleconnection in the summer circulation anomalies over the Northern Hemisphere, an index measuring the strength of the East Asian summer monsoon, i.e., the so-called EAP index, is defined in this paper. From the analyses of observed data, it is clearly shown that the EAP index defined in this study can well describe the interannual variability of summer rainfall and surface air temperature in East Asia, especially in the Yangtze River valley and the Huaihe River valley, Korea, and Japan. Moreover, this index can also reflect the interannual variability of the East Asian summer monsoon system including the monsoon horizontal circulation and the vertical-meridional circulation cell over East Asia. From the composite analyses of climate and monsoon circulation anomalies for high EAP index and for low EAP index, respectively, it is well demonstrated that the EAP index proposed in this study can well measure the strength of the East Asian summer monsoon.展开更多
Major progress, problems, and challenges of recent investigation of the Tibetan Plateau uplift processes and resulting environmental changes are reviewed and summarized briefly, which especially covers the National Ti...Major progress, problems, and challenges of recent investigation of the Tibetan Plateau uplift processes and resulting environmental changes are reviewed and summarized briefly, which especially covers the National Tibetan Research Projects of the Chinese Eighth (1992-1996) and Ninth (1997-2001) 'Five-Year Projects'. The Tibetan Plateau uplift is a complicated multiple cyclic process. The Gangdise and Himalayas began to uplift in the展开更多
Recent advances in the study of the characteristics, processes, and causes of spatio-temporal variabilities of the East Asian monsoon （EAM） system are reviewed in this paper. The understanding of the EAM system has ...Recent advances in the study of the characteristics, processes, and causes of spatio-temporal variabilities of the East Asian monsoon （EAM） system are reviewed in this paper. The understanding of the EAM system has improved in many aspects： the basic characteristics of horizontal and vertical structures, the annual cycle of the East Asian summer monsoon （EASM） system and the East Asian winter monsoon （EAWM） system, the characteristics of the spatio-temporal variabilities of the EASM system and the EAWM system, and especially the multiple modes of the EAM system and their spatio-temporal variabilities. Some new results have also been achieved in understanding the atmosphere-ocean interaction and atmosphere-land interaction processes that affect the variability of the EAM system. Based on recent studies, the EAM system can be seen as more than a circulation system, it can be viewed as an atmosphere-ocean-land coupled system, namely, the EAM climate system. In addition, further progress has been made in diagnosing the internal physical mechanisms of EAM climate system variability, especially regarding the characteristics and properties of the East Asia-Pacific （EAP） teleconnection over East Asia and the North Pacific, the ＂Silk Road＂ teleconnection along the westerly jet stream in the upper troposphere over the Asian continent, and the dynamical effects of quasi-stationary planetary wave activity on EAM system variability. At the end of the paper, some scientific problems regarding understanding the EAM system variability are proposed for further study.展开更多
Waterlogging is one of the major water issues in most cities of China and directly restricts their urbanization processes.The construction of Sponge City is an effective approach to solving the urban water issues,part...Waterlogging is one of the major water issues in most cities of China and directly restricts their urbanization processes.The construction of Sponge City is an effective approach to solving the urban water issues,particularly for the waterlogging.In this study,both the urban issues emerged at the stage of rapid urbanization in China and the demands as well as problems of Sponge City construction related with the water issues were investigated,and the opportunities and challenges for the Sponge City construction in the future were also proposed.It was found that the current stormwater management focused on the construction of gray infrastructures(e.g.,drainage network and water tank) based on the fast discharge idea,which was costly and hard to catch up with the rapid expansion of city and its impervious surface,while green infrastructures(e.g.,river,lake and wetland)were ignored.Moreover,the current construction of Sponge City was still limited to low impacted development(LID) approach which was concentrated on source control measures without consideration of the critical functions of surrounding landscapes(i.e.,mountain,river,wetland,forest,farmland and lake),while application of the integrated urban water system approach and its supported technologies including municipal engineering,urban hydrology,environmental science,social science and ecoscape were relatively weak and needed to be improved.Besides,the lack of special Sponge City plan and demonstration area was also a considerable problem.In this paper,some perspectives on Good Sponge City Construction were proposed such as the point that idea of urban plan and construction should conform to the integral and systematic view of sustainable urban development.Therefore,both the basic theoretical research and the basic infrastructure construction such as monitoring system,drainage facility and demonstration area should be strengthened,meanwhile,the reformation and innovation in the urban water management system and the education system should also be urgently pe展开更多
Recent advances in studies on the interaction between the East Asian monsoon and the ENSO cycle are reviewed in this paper. Through the recent studies, not only have the responding features and processes of the East A...Recent advances in studies on the interaction between the East Asian monsoon and the ENSO cycle are reviewed in this paper. Through the recent studies, not only have the responding features and processes of the East Asian winter and summer monsoon circulation anomalies and summer rainfall anomalies in East Asia to the ENSO cycle during its different stages been understood further, but also have the thermal and dynamic effects of the tropical \vestern Pacific on the ENSO cycle been deeply analyzed from the observational facts and dynamic theories. The results of observational and theoretical studies showed that the dynamical effect of the atmospheric circulation and zonai wind anomalies in the lower troposphere over the tropical western Pacific on the ENSO cycle may be through the excitation of the equatorial oceanic Kelvin wave and Rossby waves in the equatorial Pacific. These studies demonstrated further that the ENSO cycle originates from the tropical western Pacific. Moreover, these recent studies also showed that the atmospheric circulation and zonai wind anomalies over the tropical western Pacific not only result from the air-sea interaction over the tropical western Pacific, but are also greatly influenced by the East Asian winter and summer monsoons. Additionally, the scientific problems in the interaction between the Asian monsoon and the ENSO cycle which should be studied further in the near future are also pointed out in this paper.展开更多
A diagnostic study is made to investigate the relationship between water vapor transport from Indian monsoon and that over East Asia in Northern summer. It is found that water vapor transport from Indian monsoon is in...A diagnostic study is made to investigate the relationship between water vapor transport from Indian monsoon and that over East Asia in Northern summer. It is found that water vapor transport from Indian monsoon is inverse to that over East Asia. More (less) Indian monsoon water vapor transport corresponds to less (more) water vapor transport over East Asia and less (more) rainfall in the middle and lower reaches of the Yangtze River valley. The Indian summer monsoon water vapor transport is closely related to the intensity of the western Pacific subtropical high in its southwestern part. The stronger (weaker) the Indian summer monsoon water vapor transport, the weaker (stronger) the western Pacific subtropical high in its southwestern part, which leads to less (more) water vapor transport to East Asia, and thus less (more) rainfall in the middle and lower reaches of the Yangtze River valley. Analysis of the out-going longwave radiation anomalies suggests that the convective heating anomalies over the Indian Ocean may have significant impact not only on the Indian monsoon, but also on the East Asian monsoon.展开更多
Using observation and reanalysis data throughout 1961-1990, the East Asian surface air temperature, precipitation and sea level pressure climatology as simulated by seven fully coupled atmosphere-ocean models, namely ...Using observation and reanalysis data throughout 1961-1990, the East Asian surface air temperature, precipitation and sea level pressure climatology as simulated by seven fully coupled atmosphere-ocean models, namely CCSR/NIES, CGCM2, CSIRO-Mk2, ECHAM4/OPYC3, GFDL-R30, HadCM3, and NCAR-PCM, are systematically evaluated in this study. It is indicated that the above models can successfully reproduce the annual and seasonal surface air temperature and precipitation climatology in East Asia, with relatively good performance for boreal autumn and annual mean. The models' ability to simulate surface air temperature is more reliable than precipitation. In addition, the models can dependably capture the geographical distribution pattern of annual, boreal winter, spring and autumn sea level pressure in East Asia. In contrast, relatively large simulation errors are displayed when simulated boreal summer sea level pressure is compared with reanalysis data in East Asia. It is revealed that the simulation errors for surface air temperature, precipitation and sea level pressure are generally large over and around the Tibetan Plateau. No individual model is best in every aspect. As a whole, the ECHAM4/OPYC3 and HadCM3 performances are much better, whereas the CGCM2 is relatively poorer in East Asia. Additionally, the seven-model ensemble mean usually shows a relatively high reliability.展开更多
Defining the intensity of the East Asian winter monsoon （EAWM） with a simple index has been a difficult task. This paper elaborates on the meanings of 18 existing EAWM strength indices and classifies them into four ...Defining the intensity of the East Asian winter monsoon （EAWM） with a simple index has been a difficult task. This paper elaborates on the meanings of 18 existing EAWM strength indices and classifies them into four categories： low level wind indices, upper zonal wind shear indices, east-west pressure contrast indices, and East Asian trough indices. The temporal/spatial performance and prediction potential of these indices are then analyzed for the 1957-2001 period. It reveals that on the decadal timescale, most indices except the east-west pressure contrast indices can well capture the continuous weakening of the EAWM around 1986. On the interannual timescale, the low level wind indices and East Asian trough indices have the best predictability based on knowledge of the El Nio-Southern Oscillation and Arctic Oscillation, respectively. All the 18 existing indices can well describe the EAWM-related circulation, precipitation, and lower tropospheric air temperature anomalies. However, the variations of surface air temperature over large areas of central China cannot be well captured by most indices, which is possibly related to topographic effects. The results of this study may provide a possible reference for future studies of the EAWM.展开更多
With acquisition and accumulation of new data of structural geological investigations and high-resolution isotopic dating data, we have greatly improved our understanding of the tectonic events occurring in eastern Ch...With acquisition and accumulation of new data of structural geological investigations and high-resolution isotopic dating data, we have greatly improved our understanding of the tectonic events occurring in eastern China during the period from the Late Jurassic to Early Cretaceous and may give a new interpretation of the nature, timing and geodynamic settings of the “Yanshan Movement”. During the Mid-Late Jurassic （165±5 Ma）, great readjustment of plate amalgamation kinematics took place in East Asia and the tectonic regime underwent great transformation, thus initiating a new tectonic regime in which the North China Block was the center and different plates converged toward it from the north, east and southwest and forming the “East Asia convergent” tectonic system characterized by intracontinental subduction and orogeny. As a consequence, the crustal lithosphere of the East Asian continent thickened considerably during the Late Jurassic, followed immediately by Early Cretaceous substantial lithospheric thinning and craton destruction featured by drastic lithospheric extension and widespread volcano-magmatic activities, resulting in a major biotic turnover from the Yanliao biota to Jehol Biota. Such a tremendous tectonic event that took place in the continent of China and East Asia is the basic connotation of the “Yanshan Movement”. In the paper, according to the deformation patterns, geodynamic settings and deep processes, the “Yanshan Movement” is redefined as the Late Jurassic East Asian multi-directional plate convergent tectonic regime and its associated extensive intracontinental orogeny and great tectonic change that started at -165±5 Ma. The substantial lithospheric attenuation in East China is considered the post-effect of the Yanshanian intracontinental orogeny and deformation.展开更多
The North China and the neighbouring Mongolia in Asian Interior is characterized by extremely dry climate, resulted in one of the world＇s major dust emission centres. Deciphering the source region of Asian dust is cr...The North China and the neighbouring Mongolia in Asian Interior is characterized by extremely dry climate, resulted in one of the world＇s major dust emission centres. Deciphering the source region of Asian dust is critical for revealing the mechanism of the dust production, interpreting the paleo-environrnental records of eolian deposits, predicting the overall environmental effects of dust, and setting the strategies for the control of contemporary dust storms. This paper summarizes the geochemical methods applied to the source tracing of Asian dust. Nd-Sr isotopes were the most extensively studied source tracer of Asian dust and have been successfully applied in many cases. Geochemistry of detrital monomineral shows great theoretical advantages in source tracing and deserves further studies. The short-range transportation of Chinese loess with direction similar to that of the prevailing near surface wind is revealed. Source tracing also shows that the Asian dust has two ultimate material sources from the northern margin of the Tibetan Plateau and the Central Asian Orogen, which confirms the importance of mountain processes in the production of silt eolian particles. Based on the recent progresses on the source tracing of Asian dust, discussions are expanded on the natural background of Asian dust storms and potential anthropogenic influence, the materials evolution of the source regions of Asian dust and its relationships with climate changes and Tibetan uplift, and the role of Tibetan uplift in the Asian dust system.展开更多
We here report our recent research results on the climatic features of Tibetan thermodynamic functions and their impacts on the regional climates of the Northern Hemisphere. The results show that the thermodynamic pro...We here report our recent research results on the climatic features of Tibetan thermodynamic functions and their impacts on the regional climates of the Northern Hemisphere. The results show that the thermodynamic processes over the Tibetan Plateau not only strongly influence the Asian monsoon and precipitation, but also modulate the atmospheric circulation and climate over North America and Europe through stimulating the large-scale teleconnections such as the Asian-Pacific oscillation and affect the atmospheric circulation over the southern Indian Ocean. The Tibetan climate may be affected by sea surface temperatures over the tropical Pacific. On the other hand, the Tibetan climate also affects the atmosphere-ocean interactions in the tropics and mid-latitudes of the Pacific by the atmospheric circulation over the North Pacific. In spring and summer, the thermodynamic anomalies on the plateau affect the subtropical high pressure, the Hadley circulation, and the intertropical convergence zone over the Pacific, and then modulate the development of the El Ni-o/Southern Oscillation (ENSO). It is necessary to study the forecasting methods for the development of ENSO from the Tibetan climate anomaly. This result also embodies the essence of interactions among land, atmosphere, and ocean over the Northern Hemisphere. Since the previous studies focused on impacts of the plateau on climates in the Asian monsoon regions, it is essential to pay more attention to studying the roles of the plateau in the Northern Hemispheric and even global climates.展开更多
The initial collision between Indian and Asian continents marked the starting point for transformation of land-sea thermal contrast,uplift of the Tibet-Himalaya orogen,and climate change in Asia.In this paper,we revie...The initial collision between Indian and Asian continents marked the starting point for transformation of land-sea thermal contrast,uplift of the Tibet-Himalaya orogen,and climate change in Asia.In this paper,we review the published literatures from the past 30 years in order to draw consensus on the processes of initial collision and suturing that took place between the Indian and Asian plates.Following a comparison of the different methods that have been used to constrain the initial timing of collision,we propose that the tectono-sedimentary response in the peripheral foreland basin provides the most sensitive index of this event,and that paleomagnetism presents independent evidence as an alternative,reliable,and quantitative research method.In contrast to previous studies that have suggested collision between India and Asia started in Pakistan between ca.55 Ma and50 Ma and progressively closed eastwards,more recent researches have indicated that this major event first occurred in the center of the Yarlung Tsangpo suture zone(YTSZ) between ca.65 Ma and 63 Ma and then spreading both eastwards and westwards.While continental collision is a complicated process,including the processes of deformation,sedimentation,metamorphism,and magmatism,different researchers have tended to define the nature of this event based on their own understanding,an intuitive bias that has meant that its initial timing has remained controversial for decades.Here,we recommend the use of reconstructions of each geological event within the orogenic evolution sequence as this will allow interpretation of collision timing on the basis of multidisciplinary methods.展开更多
Using the NCEP/ NCAR reanalysis dataset covering a 40-year period from January 1958 to December 1997, sea surface temperature (1950-1992), and monthly sea-ice concentration dataset for the period from 1953 to 1995, we...Using the NCEP/ NCAR reanalysis dataset covering a 40-year period from January 1958 to December 1997, sea surface temperature (1950-1992), and monthly sea-ice concentration dataset for the period from 1953 to 1995, we investigate connections between winter Arctic Oscillation (AO) and Siberian high (SH), the East Asian winter monsoon (EAWM), and winter sea-ice extent in the Barents Sea. The results indicate that winter AO not only influences climate variations in the Arctic and the North Atlantic sector, but also shows possible effects on winter SH, and further influences EAWM, When winter AO is in its positive phase, both of winter SH and the EAWM are weaker than normal, and air temperature from near the surface to the middle troposphere is about 0.5-2degreesC higher than normal in the southeastern Siberia and the East Asian coast, including eastern China, Korea, and Japan. When AO reaches its negative phase, an opposite scenario can be observed. The results also indicate that winter SH has no significant effects on climate variations in Arctic and the North Atlantic sector. Its influence intensity and extent are obviously weaker than AO, exhibiting a 'local, feature in contrast to AO. This study further reveals the possible mechanism of how the winter AO is related to winter SH. It is found that winter SH variation is closely related to both dynamic processes and air temperature variations from the surface to the middle troposphere. The western SH variation mainly depends on dynamic processes, while its eastern part is more closely related to air temperature variation. The maintaining of winter SH mainly depends on downward motion of airflow of the nearly entire troposphere. The airflow originates from the North Atlantic sector, whose variation is influenced by the AO. When AO is in its positive (negative) phase, downward motion remarkably weakened (strengthened), which further influences winter SH. In addition, winter AO exhibits significant influences on the simultaneous sea-ice extent in the Barents Sea.展开更多
文摘Based on the NCEP/ NCAR reanalysis data the interannual variability of the East Asian winter mon-soon (EAWM) is studied with a newly defined EAWM intensity index. The marked features for a strong (weak) winter monsoon include strong (weak) northerly winds along coastal East Asia, cold (warm) East Asian continent and surrounding sea and warm (cold) ocean from the subtropical central Pacific to the trop-ical western Pacific, high (low) pressure in East Asian continent and low (high) pressure in the adjacent ocean and deep (weak) East Asian trough at 500 hPa. These interannual variations are shown to be closely connected to the SST anomaly in the tropical Pacific, both in the western and eastern Pacific. The results suggest that the strength of the EAWM is mainly influenced by the processes associated with the SST anom-aly over the tropical Pacific. The EAWM generally becomes weak when there is a positive SST anomaly in the tropical eastern Pacific (El Ni?o), and it becomes strong when there is a negative SST anomaly (La Ni?a). Moreover, the SST anomaly in the South China Sea is found to be closely related to the EAWM and may persist to the following summer. Both the circulation at 850 hPa and the rainfall in China confirm the connection between the EAWM and the following East Asian summer monsoon. The possible reason for the recent 1998 summer flood in China is briefly discussed too. Key words East Asian winter monsoon - Interannual variability - SST - Summer monsoon This study was supported by “ National Key Programme for Developing Basic Sciences” G1998040900 part 1, and by key project (KZ 952-S1-404) of Chinese Academy of Sciences.
文摘In this paper, results from a pilot study for the South China Sea Monsoon Experiment are reported. Based on analyses of 9 years of pentad and monthly mean data, the climatology of subseasonal features and interannual variability of the Southeast Asian monsoon (SEAM) are documented. The present analysis is focused on the sudden onset of the South China Sea monsoon and its relation to the atmospheric and oceanic processes on the entire Asian monsoon region. \ \ It is found that the onset of the SEAM occurs around mid-May, signaling the earliest stage of the entire Asian summer monsoon system. The establishment of monsoon rainfall over the South China Sea is abrupt, being accompanied by substantial changes in the large scale atmospheric circulation and sea surface temperature in the adjacent oceans. The onset and fluctuations of SEAM involve the interaction and metamorphosis of the large scale convection over the Indo-China, the South China Sea and the southern Bay of Bengal. Results show that the onset time of the SEAM differs greatly from one year to another. The delayed (advanced) onset of the monsoon may be related to basin-wide warm (cold) events of the Pacific and Indian Oceans. We also present evidence showing that the SEAM fluctuations in May may foreshadow the development of the full-scale Asian summer monsoon during the subsequent months.
文摘The impact of E1 Nino on the precipitation in China for different seasons are investigateddiagnostically. It is found that E1 Nino can influence the precipitation in China significantly duringits mature phase. In the Northern winter, spring and autumn, the positive precipitation anomaliesare found in the southern part of China during the E1 Nino mature phase. In the Northernsummer, the patterns of the precipitation anomalies in the E1 Nifio mature phase are different fromthose in the other seasons. The negative precipitation anomalies appear in both southern andnorthern parts of China, while in between around the lower reaches of the Yangtze River and theHuaihe River valleys the precipitation anomalies tend to be positive.In the Northern winter, spring and autumn, the physical process by which E1 Nino affects theprecipitation in the southern part of China can be explained by the features of the circulationanomalies over East Asia during the E1 Nino mature phase (Zhang et al. 1996). The appearance ofan anticyclonic anomaly to the north of the maritime continent in the lower troposphere during theE1 Nino mature phase intensifies the subtropical high in the western Pacific and makes it shiftwestward. The associated southwesterly flow is responsible for the positive precipitation anomaliesin the southern part of China. In the Northern summer, the intensified western Pacific subtropicalhigh covers the southeastern periphery of China so that the precipitation there becomes less. In addition, the weakening of the indian monsoon provides less moisture inflow to the northern part ofChina.
基金the key project of Chinese Academy of Sciences under ContractKZCX2-203 and the key program of the National Natural Science Fou
文摘The transition of the global atmospheric circulation in the end of 1970's can clearly be detected in the atmospheric temperature, wind velocity, and so on. Wavelet analysis reveals that the temporal scale of this change is larger than 20 years. Studies in this work indicate that the trend of the transition over the mid-latitude Asia is opposite to that of global average for some variables at the middle troposphere. Another finding of this research is that the African-Asian monsoon circulation is weaker and the trade wind over the tropical eastern Pacific is weaker as well after this transition. Such a signal may be found in the summer precipitation over China as well. Key words Asian monsoon circulation - Weakening - Transition This research was supported by the key project of Chinese Academy of Sciences under Contract KZCX2-203 and the key program of the National Natural Science Foundation of China under Contract 49894170.
基金supported by the National Basic Research Program of China (Grant No. 2012CB 955600)the U.S. National Science Foundation, the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA11010103)+1 种基金the Environment Research and Technology Development Fund 2-1503 of the Japanese Ministry of Environment, the Japan Society for the Promotion of Science Grant-in-Aid for Scientific Research 25287120 and for Young Scientists 15H05466the National Natural Science Foundation of China (Grant Nos. 41205049, 41275081, 41425019, 41525019, 41521005)
文摘ENSO induces coherent climate anomalies over the Indo-western Pacific, but these anomalies outlast SST anomalies of the equatorial Pacific by a season, with major effects on the Asian summer monsoon. This review provides historical accounts of major milestones and synthesizes recent advances in the endeavor to understand summer variability over the Indo-Northwest Pacific region. Specifically, a large-scale anomalous anticyclone （AAC） is a recurrent pattern in post-E1 Nifio summers, spanning the tropical Northwest Pacific and North Indian oceans. Regarding the ocean memory that anchors the summer AAC, competing hypotheses emphasize either SST cooling in the easterly trade wind regime of the Northwest Pacific or SST warming in the westerly monsoon regime of the North Indian Ocean. Our synthesis reveals a coupled ocean- atmosphere mode that builds on both mechanisms in a two-stage evolution. In spring, when the northeast trades prevail, the AAC and Northwest Pacific cooling are coupled via wind-evaporation-SST feedback. The Northwest Pacific cooling persists to trigger a summer feedback that arises from the interaction of the AAC and North Indian Ocean warming, enabled by the westerly monsoon wind regime. This Indo-western Pacific ocean capacitor （IPOC） effect explains why E1 Nifio stages its last act over the monsoonal Indo-Northwest Pacific and casts the Indian Ocean warming and AAC in leading roles. The IPOC displays interdecadal modulations by the ENSO variance cycle, significantly correlated with ENSO at the turn of the 20th century and after the 1970s, but not in between. Outstanding issues, including future climate projections, are also discussed.
基金This work was supported by the Chinese Academy of Sciences(Grant No.KZCX3 SW-221)the National Natural Science Foundation of China under Grant No.40221503.
文摘On the interannual timescale, the meridional displacement of the East Asian upper-tropospheric jet stream (EAJS) is significantly associated with the rainfall anomalies in East Asia in summer. In this study, using the data from the National Centers for Environmental Prediction-Department of Energy (NCEP/DOE) reanalysis-2 from 1979 to 2002, the authors investigate the interannual variations of the EAJS's meridional displacement in summer and their associations with the variations of the South Asian high (SAH) and the western North Pacific subtropical high (WNPSH), which are dominant circulation features in the upper and lower troposhere, respectively. The result from an EOF analysis shows that the meridional displacement is the most remarkable feature of the interannual variations of the EAJS in each month of summer and in summer as a whole. A composite analysis indicates that the summer (June-July-August, JJA) EAJS index, which is intended to depict the interannual meridional displacement of the EAJS, is not appropriate because the anomalies of the zonal wind at 200 hPa (U200) in July and August only, rather than in June, significantly contribute to the summer EAJS index. Thus, the index for each month in summer is defined according to the location of the EAJS core in each month. Composite analyses based on the monthly indexes show that corresponding to the monthly equatorward displacement of the EAJS, the South Asian high (SAH) extends southeastward clearly in July and August, and the western North Pacific subtropical high (WNPSH) withdraws southward in June and August.
基金This paper was supported by the ＂National Key Programme for Developing Basic Sciences＂ under Grant No. G2006CB403600Knowledge Innovation for the 3rd Period,Chinese Academy of Sciences under Grant No. KZCX2-YW-220the National Natural Science Foundation of China under Grant Nos. 40730952, 40575026, 40775051 respectively.
文摘Recent advances in studies of the structural characteristics and temporal-spatial variations of the East Asian monsoon （EAM） system and the impact of this system on severe climate disasters in China are reviewed. Previous studies have improved our understanding of the basic characteristics of horizontal and vertical structures and the annual cycle of the EAM system and the water vapor transports in the EAM region. Many studies have shown that the EAM system is a relatively independent subsystem of the Asian- Australian monsoon system, and that there exists an obvious quasi-biennial oscillation with a meridional tripole pattern distribution in the interannual variations of the EAM system. Further analyses of the basic physical processes, both internal and external, that influence the variability of the EAM system indicate that the EAM system may be viewed as an atmosphere-ocean-land coupled system, referred to the EAM climate system in this paper. Further, the paper discusses how the interaction and relationships among various components of this system can be described through the East Asia Pacific （EAP） teleconnection pattern and the teleconnection pattern of meridional upper-tropospheric wind anomalies along the westerly jet over East Asia. Such reasoning suggests that the occurrence of severe floods in the Yangtze and Hualhe River valleys and prolonged droughts in North China are linked, respectively~ to the background interannual and interdecadal variability of the EAM climate system. Besides, outstanding scientific issues related to the EAM system and its impact on climate disasters in China are also discussed.
基金supported jointly by the National Key Basic Research Development Program(Grant No.G1999043403)the Knowledge Innovation Project of the Chinese Academy of Sciences(CAS)(Grant No.KZCX3-SW-218)+1 种基金the National Natural Science Foundation of China project for young scientists fund(No.40305012) the Western Project of the CAS (KZCX1-10-07).
文摘Based on the EAP (East Asia/Pacific) teleconnection in the summer circulation anomalies over the Northern Hemisphere, an index measuring the strength of the East Asian summer monsoon, i.e., the so-called EAP index, is defined in this paper. From the analyses of observed data, it is clearly shown that the EAP index defined in this study can well describe the interannual variability of summer rainfall and surface air temperature in East Asia, especially in the Yangtze River valley and the Huaihe River valley, Korea, and Japan. Moreover, this index can also reflect the interannual variability of the East Asian summer monsoon system including the monsoon horizontal circulation and the vertical-meridional circulation cell over East Asia. From the composite analyses of climate and monsoon circulation anomalies for high EAP index and for low EAP index, respectively, it is well demonstrated that the EAP index proposed in this study can well measure the strength of the East Asian summer monsoon.
文摘Major progress, problems, and challenges of recent investigation of the Tibetan Plateau uplift processes and resulting environmental changes are reviewed and summarized briefly, which especially covers the National Tibetan Research Projects of the Chinese Eighth (1992-1996) and Ninth (1997-2001) 'Five-Year Projects'. The Tibetan Plateau uplift is a complicated multiple cyclic process. The Gangdise and Himalayas began to uplift in the
基金supported jointly by the National Basic Research Program of China 973 Projects (Grant No. 2010CB950403)the National Special Scientific Research Project for Public Interest (Meteorology) (Grant No. GYHY201006021)+1 种基金the Chinese Academy of Sciences(Grant No. KZCX2-EW-QN204)the National Natural Science Foundation of China (Grant No. 40975046)
文摘Recent advances in the study of the characteristics, processes, and causes of spatio-temporal variabilities of the East Asian monsoon （EAM） system are reviewed in this paper. The understanding of the EAM system has improved in many aspects： the basic characteristics of horizontal and vertical structures, the annual cycle of the East Asian summer monsoon （EASM） system and the East Asian winter monsoon （EAWM） system, the characteristics of the spatio-temporal variabilities of the EASM system and the EAWM system, and especially the multiple modes of the EAM system and their spatio-temporal variabilities. Some new results have also been achieved in understanding the atmosphere-ocean interaction and atmosphere-land interaction processes that affect the variability of the EAM system. Based on recent studies, the EAM system can be seen as more than a circulation system, it can be viewed as an atmosphere-ocean-land coupled system, namely, the EAM climate system. In addition, further progress has been made in diagnosing the internal physical mechanisms of EAM climate system variability, especially regarding the characteristics and properties of the East Asia-Pacific （EAP） teleconnection over East Asia and the North Pacific, the ＂Silk Road＂ teleconnection along the westerly jet stream in the upper troposphere over the Asian continent, and the dynamical effects of quasi-stationary planetary wave activity on EAM system variability. At the end of the paper, some scientific problems regarding understanding the EAM system variability are proposed for further study.
基金supported by the National Natural Science Foundation of China(Grant No.41571028)Key Programs of the Chinese Academy of Sciences(Grant No.KFZD-SW-301)
文摘Waterlogging is one of the major water issues in most cities of China and directly restricts their urbanization processes.The construction of Sponge City is an effective approach to solving the urban water issues,particularly for the waterlogging.In this study,both the urban issues emerged at the stage of rapid urbanization in China and the demands as well as problems of Sponge City construction related with the water issues were investigated,and the opportunities and challenges for the Sponge City construction in the future were also proposed.It was found that the current stormwater management focused on the construction of gray infrastructures(e.g.,drainage network and water tank) based on the fast discharge idea,which was costly and hard to catch up with the rapid expansion of city and its impervious surface,while green infrastructures(e.g.,river,lake and wetland)were ignored.Moreover,the current construction of Sponge City was still limited to low impacted development(LID) approach which was concentrated on source control measures without consideration of the critical functions of surrounding landscapes(i.e.,mountain,river,wetland,forest,farmland and lake),while application of the integrated urban water system approach and its supported technologies including municipal engineering,urban hydrology,environmental science,social science and ecoscape were relatively weak and needed to be improved.Besides,the lack of special Sponge City plan and demonstration area was also a considerable problem.In this paper,some perspectives on Good Sponge City Construction were proposed such as the point that idea of urban plan and construction should conform to the integral and systematic view of sustainable urban development.Therefore,both the basic theoretical research and the basic infrastructure construction such as monitoring system,drainage facility and demonstration area should be strengthened,meanwhile,the reformation and innovation in the urban water management system and the education system should also be urgently pe
基金supported by the National Natural Science Foundation of China(Grant No.40231005)the Progran for Knowledge Innovation Project of Chinese Academy of Sciences(No.KZCX3-SW-218,KZCX2-SW-210).
文摘Recent advances in studies on the interaction between the East Asian monsoon and the ENSO cycle are reviewed in this paper. Through the recent studies, not only have the responding features and processes of the East Asian winter and summer monsoon circulation anomalies and summer rainfall anomalies in East Asia to the ENSO cycle during its different stages been understood further, but also have the thermal and dynamic effects of the tropical \vestern Pacific on the ENSO cycle been deeply analyzed from the observational facts and dynamic theories. The results of observational and theoretical studies showed that the dynamical effect of the atmospheric circulation and zonai wind anomalies in the lower troposphere over the tropical western Pacific on the ENSO cycle may be through the excitation of the equatorial oceanic Kelvin wave and Rossby waves in the equatorial Pacific. These studies demonstrated further that the ENSO cycle originates from the tropical western Pacific. Moreover, these recent studies also showed that the atmospheric circulation and zonai wind anomalies over the tropical western Pacific not only result from the air-sea interaction over the tropical western Pacific, but are also greatly influenced by the East Asian winter and summer monsoons. Additionally, the scientific problems in the interaction between the Asian monsoon and the ENSO cycle which should be studied further in the near future are also pointed out in this paper.
基金This work is supported by the China National Key Program for Developing Basic Sciences(G1998040900, Part 1) and NSFC Excellent
文摘A diagnostic study is made to investigate the relationship between water vapor transport from Indian monsoon and that over East Asia in Northern summer. It is found that water vapor transport from Indian monsoon is inverse to that over East Asia. More (less) Indian monsoon water vapor transport corresponds to less (more) water vapor transport over East Asia and less (more) rainfall in the middle and lower reaches of the Yangtze River valley. The Indian summer monsoon water vapor transport is closely related to the intensity of the western Pacific subtropical high in its southwestern part. The stronger (weaker) the Indian summer monsoon water vapor transport, the weaker (stronger) the western Pacific subtropical high in its southwestern part, which leads to less (more) water vapor transport to East Asia, and thus less (more) rainfall in the middle and lower reaches of the Yangtze River valley. Analysis of the out-going longwave radiation anomalies suggests that the convective heating anomalies over the Indian Ocean may have significant impact not only on the Indian monsoon, but also on the East Asian monsoon.
基金This research was jointly supported by the Chinese Academy of Sciences(CAS)under Grant No.KZCX3-SW-221by the National Natural Science Foundation of China under Grant No.40405015+1 种基金by the Chinese Ministry of Science and Technology under Grant No.2001BA611B(part 1)by the CAS“Hundred Talent Project"funding awarded to Gao Yongqi.
文摘Using observation and reanalysis data throughout 1961-1990, the East Asian surface air temperature, precipitation and sea level pressure climatology as simulated by seven fully coupled atmosphere-ocean models, namely CCSR/NIES, CGCM2, CSIRO-Mk2, ECHAM4/OPYC3, GFDL-R30, HadCM3, and NCAR-PCM, are systematically evaluated in this study. It is indicated that the above models can successfully reproduce the annual and seasonal surface air temperature and precipitation climatology in East Asia, with relatively good performance for boreal autumn and annual mean. The models' ability to simulate surface air temperature is more reliable than precipitation. In addition, the models can dependably capture the geographical distribution pattern of annual, boreal winter, spring and autumn sea level pressure in East Asia. In contrast, relatively large simulation errors are displayed when simulated boreal summer sea level pressure is compared with reanalysis data in East Asia. It is revealed that the simulation errors for surface air temperature, precipitation and sea level pressure are generally large over and around the Tibetan Plateau. No individual model is best in every aspect. As a whole, the ECHAM4/OPYC3 and HadCM3 performances are much better, whereas the CGCM2 is relatively poorer in East Asia. Additionally, the seven-model ensemble mean usually shows a relatively high reliability.
基金supported jointly by the National Basic Research Program of China(2009CB421405)the National Key Technology R&D Program of China (2008BAK50B02)+1 种基金the National Natural Science Foundation of China (40905026 and 40775035)Key Laboratory of Global Change and Marine-Atmospheric Chemistry, SOA (GCMAC0901)
文摘Defining the intensity of the East Asian winter monsoon （EAWM） with a simple index has been a difficult task. This paper elaborates on the meanings of 18 existing EAWM strength indices and classifies them into four categories： low level wind indices, upper zonal wind shear indices, east-west pressure contrast indices, and East Asian trough indices. The temporal/spatial performance and prediction potential of these indices are then analyzed for the 1957-2001 period. It reveals that on the decadal timescale, most indices except the east-west pressure contrast indices can well capture the continuous weakening of the EAWM around 1986. On the interannual timescale, the low level wind indices and East Asian trough indices have the best predictability based on knowledge of the El Nio-Southern Oscillation and Arctic Oscillation, respectively. All the 18 existing indices can well describe the EAWM-related circulation, precipitation, and lower tropospheric air temperature anomalies. However, the variations of surface air temperature over large areas of central China cannot be well captured by most indices, which is possibly related to topographic effects. The results of this study may provide a possible reference for future studies of the EAWM.
文摘With acquisition and accumulation of new data of structural geological investigations and high-resolution isotopic dating data, we have greatly improved our understanding of the tectonic events occurring in eastern China during the period from the Late Jurassic to Early Cretaceous and may give a new interpretation of the nature, timing and geodynamic settings of the “Yanshan Movement”. During the Mid-Late Jurassic （165±5 Ma）, great readjustment of plate amalgamation kinematics took place in East Asia and the tectonic regime underwent great transformation, thus initiating a new tectonic regime in which the North China Block was the center and different plates converged toward it from the north, east and southwest and forming the “East Asia convergent” tectonic system characterized by intracontinental subduction and orogeny. As a consequence, the crustal lithosphere of the East Asian continent thickened considerably during the Late Jurassic, followed immediately by Early Cretaceous substantial lithospheric thinning and craton destruction featured by drastic lithospheric extension and widespread volcano-magmatic activities, resulting in a major biotic turnover from the Yanliao biota to Jehol Biota. Such a tremendous tectonic event that took place in the continent of China and East Asia is the basic connotation of the “Yanshan Movement”. In the paper, according to the deformation patterns, geodynamic settings and deep processes, the “Yanshan Movement” is redefined as the Late Jurassic East Asian multi-directional plate convergent tectonic regime and its associated extensive intracontinental orogeny and great tectonic change that started at -165±5 Ma. The substantial lithospheric attenuation in East China is considered the post-effect of the Yanshanian intracontinental orogeny and deformation.
基金supported by National Natural Science Foundation of China (Grant No. 41021002)
文摘The North China and the neighbouring Mongolia in Asian Interior is characterized by extremely dry climate, resulted in one of the world＇s major dust emission centres. Deciphering the source region of Asian dust is critical for revealing the mechanism of the dust production, interpreting the paleo-environrnental records of eolian deposits, predicting the overall environmental effects of dust, and setting the strategies for the control of contemporary dust storms. This paper summarizes the geochemical methods applied to the source tracing of Asian dust. Nd-Sr isotopes were the most extensively studied source tracer of Asian dust and have been successfully applied in many cases. Geochemistry of detrital monomineral shows great theoretical advantages in source tracing and deserves further studies. The short-range transportation of Chinese loess with direction similar to that of the prevailing near surface wind is revealed. Source tracing also shows that the Asian dust has two ultimate material sources from the northern margin of the Tibetan Plateau and the Central Asian Orogen, which confirms the importance of mountain processes in the production of silt eolian particles. Based on the recent progresses on the source tracing of Asian dust, discussions are expanded on the natural background of Asian dust storms and potential anthropogenic influence, the materials evolution of the source regions of Asian dust and its relationships with climate changes and Tibetan uplift, and the role of Tibetan uplift in the Asian dust system.
基金Supported by National Natural Science Foundation of China (Grant Nos. 40890052, 40921003)the Chinese COPES Project (Grant No. GYHY200706005)
文摘We here report our recent research results on the climatic features of Tibetan thermodynamic functions and their impacts on the regional climates of the Northern Hemisphere. The results show that the thermodynamic processes over the Tibetan Plateau not only strongly influence the Asian monsoon and precipitation, but also modulate the atmospheric circulation and climate over North America and Europe through stimulating the large-scale teleconnections such as the Asian-Pacific oscillation and affect the atmospheric circulation over the southern Indian Ocean. The Tibetan climate may be affected by sea surface temperatures over the tropical Pacific. On the other hand, the Tibetan climate also affects the atmosphere-ocean interactions in the tropics and mid-latitudes of the Pacific by the atmospheric circulation over the North Pacific. In spring and summer, the thermodynamic anomalies on the plateau affect the subtropical high pressure, the Hadley circulation, and the intertropical convergence zone over the Pacific, and then modulate the development of the El Ni-o/Southern Oscillation (ENSO). It is necessary to study the forecasting methods for the development of ENSO from the Tibetan climate anomaly. This result also embodies the essence of interactions among land, atmosphere, and ocean over the Northern Hemisphere. Since the previous studies focused on impacts of the plateau on climates in the Asian monsoon regions, it is essential to pay more attention to studying the roles of the plateau in the Northern Hemispheric and even global climates.
基金supported by the Chinese Academy of Sciences(Grant No.XDB03010401)the National Key Research and Development Plan(Grant No.2016YFC0600303)National Natural Science Foundation of China(Grant No.41490615)
文摘The initial collision between Indian and Asian continents marked the starting point for transformation of land-sea thermal contrast,uplift of the Tibet-Himalaya orogen,and climate change in Asia.In this paper,we review the published literatures from the past 30 years in order to draw consensus on the processes of initial collision and suturing that took place between the Indian and Asian plates.Following a comparison of the different methods that have been used to constrain the initial timing of collision,we propose that the tectono-sedimentary response in the peripheral foreland basin provides the most sensitive index of this event,and that paleomagnetism presents independent evidence as an alternative,reliable,and quantitative research method.In contrast to previous studies that have suggested collision between India and Asia started in Pakistan between ca.55 Ma and50 Ma and progressively closed eastwards,more recent researches have indicated that this major event first occurred in the center of the Yarlung Tsangpo suture zone(YTSZ) between ca.65 Ma and 63 Ma and then spreading both eastwards and westwards.While continental collision is a complicated process,including the processes of deformation,sedimentation,metamorphism,and magmatism,different researchers have tended to define the nature of this event based on their own understanding,an intuitive bias that has meant that its initial timing has remained controversial for decades.Here,we recommend the use of reconstructions of each geological event within the orogenic evolution sequence as this will allow interpretation of collision timing on the basis of multidisciplinary methods.
基金the National Key Basic Research Program (Grant No.G 1998040900), the Frontier Research System for Global Change of Japan and the
文摘Using the NCEP/ NCAR reanalysis dataset covering a 40-year period from January 1958 to December 1997, sea surface temperature (1950-1992), and monthly sea-ice concentration dataset for the period from 1953 to 1995, we investigate connections between winter Arctic Oscillation (AO) and Siberian high (SH), the East Asian winter monsoon (EAWM), and winter sea-ice extent in the Barents Sea. The results indicate that winter AO not only influences climate variations in the Arctic and the North Atlantic sector, but also shows possible effects on winter SH, and further influences EAWM, When winter AO is in its positive phase, both of winter SH and the EAWM are weaker than normal, and air temperature from near the surface to the middle troposphere is about 0.5-2degreesC higher than normal in the southeastern Siberia and the East Asian coast, including eastern China, Korea, and Japan. When AO reaches its negative phase, an opposite scenario can be observed. The results also indicate that winter SH has no significant effects on climate variations in Arctic and the North Atlantic sector. Its influence intensity and extent are obviously weaker than AO, exhibiting a 'local, feature in contrast to AO. This study further reveals the possible mechanism of how the winter AO is related to winter SH. It is found that winter SH variation is closely related to both dynamic processes and air temperature variations from the surface to the middle troposphere. The western SH variation mainly depends on dynamic processes, while its eastern part is more closely related to air temperature variation. The maintaining of winter SH mainly depends on downward motion of airflow of the nearly entire troposphere. The airflow originates from the North Atlantic sector, whose variation is influenced by the AO. When AO is in its positive (negative) phase, downward motion remarkably weakened (strengthened), which further influences winter SH. In addition, winter AO exhibits significant influences on the simultaneous sea-ice extent in the Barents Sea.
