Concurrence of low temperature,precipitation and freezing weather in an extensive area would cause devastating impacts on local economy and society.We call such a combination of concurrent disastrous weather“extensiv...Concurrence of low temperature,precipitation and freezing weather in an extensive area would cause devastating impacts on local economy and society.We call such a combination of concurrent disastrous weather“extensive coldprecipitation-freezing”events(ECPFEs).In this study,the ECPFEs in southern China(15°−35°N,102°−123°E)are objectively defined by using daily surface observational data for the period 1951−2013.An ECPFE in southern China is defined if the low temperature area,precipitation area and freezing area concurrently exceed their respective thresholds for at least three consecutive days.The identified ECPFEs are shown to be reasonable and reliable,compared with those in previous studies.The circulation anomalies in ECPFEs are characterized by a large-scale tilted ridge and trough pairing over mid-and high-latitude Eurasia,and the intensified subtropical westerlies along the southern foot of the Tibetan Plateau and the anomalous anticyclonic circulation over the subtropical western Pacific.Comparative analysis reveals that the stable cold air from the north and the warm and moist air from the south converge,facilitating a favorable environment for the concurrence of extensive low-temperature,precipitation and freezing weather.展开更多
This study investigates the major patterns of large-scale tilted ridges(LSTRS)over the Eurasian continent and their connections with large-scale surface air temperature during boreal winter.A total number of 134 LSTR ...This study investigates the major patterns of large-scale tilted ridges(LSTRS)over the Eurasian continent and their connections with large-scale surface air temperature during boreal winter.A total number of 134 LSTR events with zonal extent exceeding 90°of longitude on the peak day are identified.Using self-organizing map(SOM),the LSTRs are classified into five clusters that are characterized by different spatial distributions and orientations.The leading two clusters are closely associated with extensive and persistent cold events over different places.Considering the first cluster,LSTRs extend from the Ural Mountains to Northeast Asia and are favorable for the amplification and southeastward extension of the Siberian high.Therefore,this cluster is closely associated with the occurrence of extensive and persistent cold events in china.In comparison with the first cluster,the LSTRs of second group are situated to the west,with starting points from the Kola Peninsula,and cause extensive and persistent cold events over Eastern Europe,central Asia,and central Siberia.The results suggest that the vertical coupling between LSTRs and the corresponding anomalous sea level pressure is crucial for the persistent cold temperature events associated with the leading two SOM clusters.展开更多
It had very long been a dream in polymer science to synthesize long multi-block polymer chains with an orderedchain sequence and controllable block lengths. Using ionic or living free radical polymerization or furnish...It had very long been a dream in polymer science to synthesize long multi-block polymer chains with an orderedchain sequence and controllable block lengths. Using ionic or living free radical polymerization or furnishing each end ofpolymer blocks with a reactive functional group, one can only prepare heteropolymer chains with few long blocks, such asdiblock and triblock copolymers. The most plausible result so far was a pentablock copolymer. Recently, using a combinationof polymer physics and synthetic chemistry, we have invented self-assembly assisted polycondensation (SAAP). Thiscommunication reports the results of using this novel. method to connect 10-100 triblock polymer chains together to formlong multi-block heteropolymer chains with an ordered sequence and controllable block lengths.展开更多
基金This research was funded by the National Natural Science Foundation of China(Grant Nos.41975072 and 41675086)the National Science and Technology Support Program of China(Grant No.2015BAC03B03).
文摘Concurrence of low temperature,precipitation and freezing weather in an extensive area would cause devastating impacts on local economy and society.We call such a combination of concurrent disastrous weather“extensive coldprecipitation-freezing”events(ECPFEs).In this study,the ECPFEs in southern China(15°−35°N,102°−123°E)are objectively defined by using daily surface observational data for the period 1951−2013.An ECPFE in southern China is defined if the low temperature area,precipitation area and freezing area concurrently exceed their respective thresholds for at least three consecutive days.The identified ECPFEs are shown to be reasonable and reliable,compared with those in previous studies.The circulation anomalies in ECPFEs are characterized by a large-scale tilted ridge and trough pairing over mid-and high-latitude Eurasia,and the intensified subtropical westerlies along the southern foot of the Tibetan Plateau and the anomalous anticyclonic circulation over the subtropical western Pacific.Comparative analysis reveals that the stable cold air from the north and the warm and moist air from the south converge,facilitating a favorable environment for the concurrence of extensive low-temperature,precipitation and freezing weather.
基金jointly supported by the National Natural Science Foundation of China [grant number 41375064 and41675086]the National Key Technology Research and Development Program of the Ministry of Science and Technology of China [grant number 2015BAC03B03]
文摘This study investigates the major patterns of large-scale tilted ridges(LSTRS)over the Eurasian continent and their connections with large-scale surface air temperature during boreal winter.A total number of 134 LSTR events with zonal extent exceeding 90°of longitude on the peak day are identified.Using self-organizing map(SOM),the LSTRs are classified into five clusters that are characterized by different spatial distributions and orientations.The leading two clusters are closely associated with extensive and persistent cold events over different places.Considering the first cluster,LSTRs extend from the Ural Mountains to Northeast Asia and are favorable for the amplification and southeastward extension of the Siberian high.Therefore,this cluster is closely associated with the occurrence of extensive and persistent cold events in china.In comparison with the first cluster,the LSTRs of second group are situated to the west,with starting points from the Kola Peninsula,and cause extensive and persistent cold events over Eastern Europe,central Asia,and central Siberia.The results suggest that the vertical coupling between LSTRs and the corresponding anomalous sea level pressure is crucial for the persistent cold temperature events associated with the leading two SOM clusters.
基金Financial support of the Research Grants Council of the Hong Kong Special Administration Region Earmarked Grant (CUHK4267/00P, CUHK 4209/99P, 2160122) and NNSFC 29974027 is gratefully acknowledged.
文摘It had very long been a dream in polymer science to synthesize long multi-block polymer chains with an orderedchain sequence and controllable block lengths. Using ionic or living free radical polymerization or furnishing each end ofpolymer blocks with a reactive functional group, one can only prepare heteropolymer chains with few long blocks, such asdiblock and triblock copolymers. The most plausible result so far was a pentablock copolymer. Recently, using a combinationof polymer physics and synthetic chemistry, we have invented self-assembly assisted polycondensation (SAAP). Thiscommunication reports the results of using this novel. method to connect 10-100 triblock polymer chains together to formlong multi-block heteropolymer chains with an ordered sequence and controllable block lengths.
