ASEAN countries are important targets for the United States to promote the “Indo–Pacific” minilateral framework. Their official, think tank, and media opinions regard this as an important opportunity to enhance the...ASEAN countries are important targets for the United States to promote the “Indo–Pacific” minilateral framework. Their official, think tank, and media opinions regard this as an important opportunity to enhance their national status and promote their national interests, which will be beneficial to peace and stability in the “Indo–Pacific” region. However, they are worried that it will damage the “ASEAN centrality.” ASEAN has responded positively and is committed to reshaping its “central position” and regional leadership and improving regional governance capabilities, but there are differences in the responses of various countries. In the future, ASEAN countries will seek to achieve direct and practical interests through the US “Indo–Pacific” minilateral framework, but they are more wor ried that the “central position of ASEAN” will be replaced and its “neutral and balanced” position will be threatened.展开更多
Spin-unrestricted localized INDO method was used to calculate the electronic structure of rare earth cluster Sc(Sc_6Cl_(12)Co).Based on the analysis of the composition of the molecular orbitals and bond orders,it was ...Spin-unrestricted localized INDO method was used to calculate the electronic structure of rare earth cluster Sc(Sc_6Cl_(12)Co).Based on the analysis of the composition of the molecular orbitals and bond orders,it was pointed out that the interstitial transition metal atom Co in the octahedral Sc skeleton forms strong covalent bond with six Sc atoms and the bonding of Sc- Cl is mainly ionic in character.There are nine valence molecular orbitals in the cluster.展开更多
The thermal characteristics during the South China Sea (SCS) summer monsoon onset period near the Indo-China Peninsula are analyzed by using the South China Sea Monsoon Experiment (SCSMEX) reanalysis data from 1 May t...The thermal characteristics during the South China Sea (SCS) summer monsoon onset period near the Indo-China Peninsula are analyzed by using the South China Sea Monsoon Experiment (SCSMEX) reanalysis data from 1 May to 31 August 1998 and the NCEP/ NCAR pentad-mean reanalysis data from January 1980 to December 1995. The possible relationships between the anomaly of thermal features near the Indo-China Peninsula and the SCS monsoon onset are investigated, and the mechanism causing the SCS summer monsoon onset is also discussed. Results from the 1998 SCSMEX reanalysis data show that there exists a strong persistent surface sensible heating near the Indo-China Peninsula prior to the SCS monsoon onset, which has apparent low frequency oscillation features. This sensible healing leads lo a warmer center in the lower atmosphere near the Indo-China Peninsula and strong local horizontal temperature and geopotential height gradients which are favorable to strengthening the southwest wind over the Indo-China Peninsula. It is also found that stronger convergent winds at lower levels and stronger divergent winds at high levels appear, which provide a favorable configuration for the development of vertical motion, enhancement of precipitation, and onset of the SCS monsoon. These results can be verified by analysis of the multi-year mean data. Additionally, it is found that the temperature at 850 hPa increases more rapidly over the Indo-China Peninsula than the South China Sea prior to the SCS monsoon onset, which leads to a strengthening of the temperature difference between the Indo-China Peninsula and the South China Sea. Moreover, results from the analysis of the longitudinal temperature and geopotential height differences show that the eastern retreat of the subtropical high over the Indo-China Peninsula during the period of SCS monsoon onset is associated with the temperature increase over the Indo-China Peninsula and the eastern extension of low trough over the Bay of Bengal.展开更多
Understanding of the temporal variation of oceanic heat content （OHC） is of fundamental importance to the prediction of climate change and associated global meteorological phenomena. However, OHC characteristics in ...Understanding of the temporal variation of oceanic heat content （OHC） is of fundamental importance to the prediction of climate change and associated global meteorological phenomena. However, OHC characteristics in the Pacific and Indian oceans are not well understood. Based on in situ ocean temperature and salinity profiles mainly from the Argo program, we estimated the upper layer （0-750 m） OHC in the Indo-Pacific Ocean （40°S-40°N, 30°E-80°W）. Spatial and temporal variability of OHC and its likely physical mechanisms are also analyzed. Climatic distributions of upper-layer OHC in the Indian and Pacific oceans have a similar saddle pattern in the subtropics, and the highest OHC value was in the northern Arabian Sea. However, OHC variabilities in the two oceans were different. OHC in the Pacific has an east-west see-saw pattern, which does not appear in the Indian Ocean. In the Indian Ocean, the largest change was around 10°S. The most interesting phenomenon is that, there was a long-term shift of OHC in the Indo-Pacific Ocean during 2001-2012. Such variation coincided with modulation of subsurface temperature/salinity. During 2001-2007, there was subsurface cooling （freshening） nearly the entire upper 400 m layer in the western Pacific and warming （salting） in the eastern Pacific. During 2008-2012, the thermocline deepened in the western Pacific but shoaled in the east. In the Indian Ocean, there was only cooling （upper 150 m only） and freshening （almost the entire upper 400 m） during 2001-2007. The thermocline deepened during 2008-2012 in the Indian Ocean. Such change appeared from the equator to off the equator and even to the subtropics （about 20°N/S） in the two oceans. This long-term change of subsurface temperature/salinity may have been caused by change of the wind field over the two oceans during 2001-2012, in turn modifying OHC.展开更多
The establishment of the upper-level South Asian high （SAH） over the Indo-China Peninsula （ICP） during late boreal spring and its possible causes are investigated using long-term NCEP-NCAR and ERA-40 reanalysis an...The establishment of the upper-level South Asian high （SAH） over the Indo-China Peninsula （ICP） during late boreal spring and its possible causes are investigated using long-term NCEP-NCAR and ERA-40 reanalysis and satellite-observed OLR data. Results show that, from early March to mid-April, deep convection stays south of -6°N over the northern Sumatran islands. As the maximum solar radiation moves over the latitudes of the ICP （10-20°N） in late April, the air over the ICP becomes unstable. It ascends over the ICP and descends over the adjacent waters to the east and west. This triggers deep convection over the ICP that induces large latent heating and strong updrafts and upper-level divergence, leading to the formation of an upper-level anticyclonic circulation and the SAH over the ICE During early to mid-May, deep convection over the ICP intensifies and extends northwards to the adjacent waters. Strong latent heating from deep convection enhances and maintains the strong updrafts and upper-level divergence, and the SAH is fully established by mid-May. Thus, the seasonal maximum solar heating and the land-sea contrast around the ICP provide the basic conditions for deep convection to occur preferentially over the ICP, which leads to the formation of the SAH over the ICP from late April to mid-May. Simulations using RegCM4 also indicate that the diabatic heating over the ICP is conducive to the generation and development of upper-level anticyclonic circulation, which leads to an earlier establishment of the SAH.展开更多
In this study, we investigate the spatiotemporal characteristics of drought in India and its impact on agriculture during the summer season （April-September）. In the analysis, we use Standardized Precipitation Evapo...In this study, we investigate the spatiotemporal characteristics of drought in India and its impact on agriculture during the summer season （April-September）. In the analysis, we use Standardized Precipitation Evapotranspiration Index （SPEI） datasets between 1982 and 2012 at the six-monthly timescale. Based on the criterion SPEI 〈 -1, we obtain a map of the number of occurrences of drought and find that the humid subtropical Upper Middle Gangetic Plain （UMGP） region is highly drought-prone, with an occurrence frequency of 40%-45%. This UMGP region contributes at least 18%-20% of India＇s annual cereal production. Not only the probability of drought, but the UMGP region has become increasingly drought-prone in recent decades. Moreover, cereal production in the UMGP region has experienced a gradual declining trend from 2000 onwards, which is consistent with the increase in drought-affected areas from 20%-25% to 50%-60%, before and after 2000, respectively. A higher correlation coefficient （-0.69） between the cereal production changes and drought-affected areas confirms that at least 50% of the agricultural （cereal） losses are associated with drought. While analyzing the individual impact of precipitation and surface temperature on SPEI at 6 month timescale [SPEI （6）] we find that, in the UMGP region, surface temperature plays the primary role in the lowering of the SPEI. The linkage is further confirmed by correlation analysis between SPEI （6） and surface temperature, which exhibits strong negative values in the UMGP region. Higher temperatures may have caused more evaporation and drying, which therefore increased the area affected by drought in recent decades.展开更多
基金a phased result of a project supported by the National Social Science Fund of China in 2020 entitled “The Reconstruction of ‘ASEAN Centrality’ in the Context of ‘Indo–Pacific’ Strategy”(Grant Number:20CGJ029)。
文摘ASEAN countries are important targets for the United States to promote the “Indo–Pacific” minilateral framework. Their official, think tank, and media opinions regard this as an important opportunity to enhance their national status and promote their national interests, which will be beneficial to peace and stability in the “Indo–Pacific” region. However, they are worried that it will damage the “ASEAN centrality.” ASEAN has responded positively and is committed to reshaping its “central position” and regional leadership and improving regional governance capabilities, but there are differences in the responses of various countries. In the future, ASEAN countries will seek to achieve direct and practical interests through the US “Indo–Pacific” minilateral framework, but they are more wor ried that the “central position of ASEAN” will be replaced and its “neutral and balanced” position will be threatened.
文摘Spin-unrestricted localized INDO method was used to calculate the electronic structure of rare earth cluster Sc(Sc_6Cl_(12)Co).Based on the analysis of the composition of the molecular orbitals and bond orders,it was pointed out that the interstitial transition metal atom Co in the octahedral Sc skeleton forms strong covalent bond with six Sc atoms and the bonding of Sc- Cl is mainly ionic in character.There are nine valence molecular orbitals in the cluster.
基金This study is supported by the Nationul Natural Science Foundation of China under Grant No. 40175021is purtly funded by the Ministry of Education through the start-up project for scientists who have returned from abroud.
文摘The thermal characteristics during the South China Sea (SCS) summer monsoon onset period near the Indo-China Peninsula are analyzed by using the South China Sea Monsoon Experiment (SCSMEX) reanalysis data from 1 May to 31 August 1998 and the NCEP/ NCAR pentad-mean reanalysis data from January 1980 to December 1995. The possible relationships between the anomaly of thermal features near the Indo-China Peninsula and the SCS monsoon onset are investigated, and the mechanism causing the SCS summer monsoon onset is also discussed. Results from the 1998 SCSMEX reanalysis data show that there exists a strong persistent surface sensible heating near the Indo-China Peninsula prior to the SCS monsoon onset, which has apparent low frequency oscillation features. This sensible healing leads lo a warmer center in the lower atmosphere near the Indo-China Peninsula and strong local horizontal temperature and geopotential height gradients which are favorable to strengthening the southwest wind over the Indo-China Peninsula. It is also found that stronger convergent winds at lower levels and stronger divergent winds at high levels appear, which provide a favorable configuration for the development of vertical motion, enhancement of precipitation, and onset of the SCS monsoon. These results can be verified by analysis of the multi-year mean data. Additionally, it is found that the temperature at 850 hPa increases more rapidly over the Indo-China Peninsula than the South China Sea prior to the SCS monsoon onset, which leads to a strengthening of the temperature difference between the Indo-China Peninsula and the South China Sea. Moreover, results from the analysis of the longitudinal temperature and geopotential height differences show that the eastern retreat of the subtropical high over the Indo-China Peninsula during the period of SCS monsoon onset is associated with the temperature increase over the Indo-China Peninsula and the eastern extension of low trough over the Bay of Bengal.
基金The National Basic Research Program(973 Program)of China under contract No.2012CB955601the Special Program for National Basic Research under contract No.2012FY112300+1 种基金the Scientific Research Fund of the Second Institute of Oceanography,State Oceanic Administration under contract Nos JG1207,JG1303 and SOED1307the National Natural Science Foundation of China under contract Nos 41206022,and 41406022
文摘Understanding of the temporal variation of oceanic heat content （OHC） is of fundamental importance to the prediction of climate change and associated global meteorological phenomena. However, OHC characteristics in the Pacific and Indian oceans are not well understood. Based on in situ ocean temperature and salinity profiles mainly from the Argo program, we estimated the upper layer （0-750 m） OHC in the Indo-Pacific Ocean （40°S-40°N, 30°E-80°W）. Spatial and temporal variability of OHC and its likely physical mechanisms are also analyzed. Climatic distributions of upper-layer OHC in the Indian and Pacific oceans have a similar saddle pattern in the subtropics, and the highest OHC value was in the northern Arabian Sea. However, OHC variabilities in the two oceans were different. OHC in the Pacific has an east-west see-saw pattern, which does not appear in the Indian Ocean. In the Indian Ocean, the largest change was around 10°S. The most interesting phenomenon is that, there was a long-term shift of OHC in the Indo-Pacific Ocean during 2001-2012. Such variation coincided with modulation of subsurface temperature/salinity. During 2001-2007, there was subsurface cooling （freshening） nearly the entire upper 400 m layer in the western Pacific and warming （salting） in the eastern Pacific. During 2008-2012, the thermocline deepened in the western Pacific but shoaled in the east. In the Indian Ocean, there was only cooling （upper 150 m only） and freshening （almost the entire upper 400 m） during 2001-2007. The thermocline deepened during 2008-2012 in the Indian Ocean. Such change appeared from the equator to off the equator and even to the subtropics （about 20°N/S） in the two oceans. This long-term change of subsurface temperature/salinity may have been caused by change of the wind field over the two oceans during 2001-2012, in turn modifying OHC.
基金jointly supported by the Major Program of the Natural Science Researches for Colleges and Universities in Jiangsu Province(Grant No.14KJA170004)the Natural Science Foundation of Jiangsu Province(Grant No.BK20131432)+5 种基金the“333”Project of Jiangsu Province“Qing Lan”Project of Jiangsu Provincethe Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)supported by the U.S.National Science Foundation(Grant No.AGS-1353740)the U.S.Department of Energy’s Office of Science(Grant No.DE-SC0012602)the U.S.National Oceanic and Atmospheric Administration(Grant No.NA15OAR4310086)
文摘The establishment of the upper-level South Asian high （SAH） over the Indo-China Peninsula （ICP） during late boreal spring and its possible causes are investigated using long-term NCEP-NCAR and ERA-40 reanalysis and satellite-observed OLR data. Results show that, from early March to mid-April, deep convection stays south of -6°N over the northern Sumatran islands. As the maximum solar radiation moves over the latitudes of the ICP （10-20°N） in late April, the air over the ICP becomes unstable. It ascends over the ICP and descends over the adjacent waters to the east and west. This triggers deep convection over the ICP that induces large latent heating and strong updrafts and upper-level divergence, leading to the formation of an upper-level anticyclonic circulation and the SAH over the ICE During early to mid-May, deep convection over the ICP intensifies and extends northwards to the adjacent waters. Strong latent heating from deep convection enhances and maintains the strong updrafts and upper-level divergence, and the SAH is fully established by mid-May. Thus, the seasonal maximum solar heating and the land-sea contrast around the ICP provide the basic conditions for deep convection to occur preferentially over the ICP, which leads to the formation of the SAH over the ICP from late April to mid-May. Simulations using RegCM4 also indicate that the diabatic heating over the ICP is conducive to the generation and development of upper-level anticyclonic circulation, which leads to an earlier establishment of the SAH.
基金supported by the National Basic Research Development Program of China(Grant No.2015CB953602)National Science Foundation of China(Grant Nos.41271542 and 41661144006)a CAS-TWAS President’s Fellowship,2013
文摘In this study, we investigate the spatiotemporal characteristics of drought in India and its impact on agriculture during the summer season （April-September）. In the analysis, we use Standardized Precipitation Evapotranspiration Index （SPEI） datasets between 1982 and 2012 at the six-monthly timescale. Based on the criterion SPEI 〈 -1, we obtain a map of the number of occurrences of drought and find that the humid subtropical Upper Middle Gangetic Plain （UMGP） region is highly drought-prone, with an occurrence frequency of 40%-45%. This UMGP region contributes at least 18%-20% of India＇s annual cereal production. Not only the probability of drought, but the UMGP region has become increasingly drought-prone in recent decades. Moreover, cereal production in the UMGP region has experienced a gradual declining trend from 2000 onwards, which is consistent with the increase in drought-affected areas from 20%-25% to 50%-60%, before and after 2000, respectively. A higher correlation coefficient （-0.69） between the cereal production changes and drought-affected areas confirms that at least 50% of the agricultural （cereal） losses are associated with drought. While analyzing the individual impact of precipitation and surface temperature on SPEI at 6 month timescale [SPEI （6）] we find that, in the UMGP region, surface temperature plays the primary role in the lowering of the SPEI. The linkage is further confirmed by correlation analysis between SPEI （6） and surface temperature, which exhibits strong negative values in the UMGP region. Higher temperatures may have caused more evaporation and drying, which therefore increased the area affected by drought in recent decades.
