Associations between the autumn Arctic sea ice concentrations (SICs) and North American winter precipitation were examined using singular value decomposition. The results show that a reduced SIC in the majority of the...Associations between the autumn Arctic sea ice concentrations (SICs) and North American winter precipitation were examined using singular value decomposition. The results show that a reduced SIC in the majority of the Arctic is accompanied by dry conditions over the Great Plains, the southern United States, Mexico, eastern Alaska, and southeastern Greenland, and by wet conditions over the majority of Canada, the northeastern United States, and the majority of Greenland. Atmospheric circulation anomalies associated with the SIC variability show a wave train structure that is persistent from autumn to winter and is responsible for the covariability between the autumn Arctic SICs and North American winter precipitation. This relationship suggests a potential long-term outlook for the North American winter precipitation.展开更多
The relationship between the variability of the surface elevation of the Greenland Ice Sheet (GIS) in winter and sea level pressure is identified through analysis of data from satellite-borne radar altimeters, togethe...The relationship between the variability of the surface elevation of the Greenland Ice Sheet (GIS) in winter and sea level pressure is identified through analysis of data from satellite-borne radar altimeters, together with meteorological data fields during 1993 2005. We found that both the North Pacific Oscillation (NPO) and the North Atlantic Oscillation (NAO), the two major teleconnection patterns of the atmospheric surface pressure fields in the Northern Hemisphere, significantly influence the GIS winter elevation change. Further, it is suggested that the NPO may affect the GIS accumulation by influencing the NAO, particularly by changing the intensity and location of the Icelandic Low.展开更多
Temperature and salinity profile data, collected by southern elephant seals equipped with autonomous CTD-Satellite Relay Data Loggers(CTD-SRDLs) during the Antarctic wintertime in 2011 and 2012, were used to study the...Temperature and salinity profile data, collected by southern elephant seals equipped with autonomous CTD-Satellite Relay Data Loggers(CTD-SRDLs) during the Antarctic wintertime in 2011 and 2012, were used to study the evolution of water property and the resultant formation of the high density water in the Mackenzie Bay polynya(MBP) in front of the Amery Ice Shelf(AIS). In late March the upper 100–200 m layer is characterized by strong halocline and inversion thermocline. The mixed layer keeps deepening up to 250 m by mid-April with potential temperature remaining nearly the surface freezing point and sea surface salinity increasing from 34.00 to 34.21. From then on until mid-May, the whole water column stays isothermally at about^(-1).90℃while the surface salinity increases by a further 0.23. Hereafter the temperature increases while salinity decreases along with the increasing depth both by 0.1 order of magnitude vertically. The upper ocean heat content ranging from 120.5 to 2.9 MJ m^(-2), heat flux with the values of 9.8–287.0 W m^(-2) loss and the sea ice growth rates of 4.3–11.7 cm d^(-1) were estimated by using simple 1-D heat and salt budget methods. The MBP exists throughout the whole Antarctic winter(March to October) due to the air-sea-ice interaction, with an average size of about 5.0×10~3 km^2. It can be speculated that the decrease of the salinity of the upper ocean may occur after October each year. The recurring sea-ice production and the associated brine rejection process increase the salinity of the water column in the MBP progressively, resulting in, eventually, the formation of a large body of high density water.展开更多
Aims Woody plants represent the ancestral growth form in angiosperms with herbs evolving repeatedly from them.While there are a number of hypotheses about drivers of the evolution of the herbaceous habit,the ability t...Aims Woody plants represent the ancestral growth form in angiosperms with herbs evolving repeatedly from them.While there are a number of hypotheses about drivers of the evolution of the herbaceous habit,the ability to avoid frost damage in winter by discarding their aboveground biomass has often been invoked as the main force in their evolution.We propose instead that any unpredictable disturbance might have been much more important than the seasonal frost,as herbs easily survive repeated disturbance.Methods We tested this hypothesis by comparing herbs and woody plants in their ability to deal with three types of simulated disturbances,more predictable winter freezing,less predictable spring freezing and herbivory.Comparison was made in an experimental common garden setup with 20 species differing in woodiness.We evaluated the effects of these disturbances on mortality and regrowth of plants.Important Findings Herbs did not have an advantage over woody plants in survival when exposed to winter freezing.In less predictable conditions of spring freezing herbs survived the treatment better than woody plants and this advantage was even larger in case of the simulated herbivory treatment.The advantage of herbs over woody plants in less predictable conditions suggests that herbaceous growth form might be an adaptation to unpredictable disturbance,which herbs are able to tolerate thanks to their ability to survive loss of aboveground biomass.Consequently,factors such as mammal herbivory or fire might have been the most likely factors in the transition from woody species to herbs.展开更多
The role of tourism in social and economic development and stabilizing the Olympic legacy has been widely discussed.Beijing is the first“Dual-Olympic City”.For the first time,the Beijing Winter Olympics has adopted ...The role of tourism in social and economic development and stabilizing the Olympic legacy has been widely discussed.Beijing is the first“Dual-Olympic City”.For the first time,the Beijing Winter Olympics has adopted a model of three competition areas,which has attracted much attention to the study of its tourism legacy.In the legacy plan,the construction of the“Beijing-Zhangjiakou Sports Culture and Tourism Belt”was proposed.The development of ice and snow tourism and the cultivation of the ice and snow tourism market is also reflected in many policy documents and government actions.The scientific planning before the competition laid a good foundation for the sustainable development of its ice and snow tourism heritage.This research combines Olympic legacy research with tourism destination theory,and focuses on ice and snow tourism directly related to the Winter Olympics and the significance of pre-event planning for legacy protection.At the same time,the improvement of the quality of ice and snow tourism destinations is embedded in the pre-Olympic legacy,and opinions and suggestions on how to ensure the stability of the legacy after the games are given.This study uses the literature review method and the second-hand materials survey research method,then through establishing a tourism legacy pre-game evaluation model and the use of geographic information,government reports,policies,publicly released statistics and news reports,etc..It explores the legacy of the Beijing 2022 Winter Olympics and Paralympics,aiming to lay the foundation for preserving the continuous value of the ice and snow tourism legacy during and after the Olympics.The results indicate that the Beijing Winter Olympics has made relatively complete plans and reliable progress in both tangible and intangible legacy.Complete tourism infrastructure,an optimistic sport and cultural atmosphere,and the improvement of residents’health concept and sports awareness have become boosters for the development of ice and snow tourism in the Beijing-Zhangjiakou region.展开更多
Since Beijing and Zhangjiakou in neighboring Hebei Province won the bid to host the 2022 Winter Olympics,the entire country has become increasingly enthusiastic about winter sports.Skiing and skating are popular winte...Since Beijing and Zhangjiakou in neighboring Hebei Province won the bid to host the 2022 Winter Olympics,the entire country has become increasingly enthusiastic about winter sports.Skiing and skating are popular winter activities while lesser-known games such as curling and ice hockey have also become familiar to sports lovers.展开更多
基金supported by the National Basic Research Program of China (2011CB30970)the National Natural Science Foundation of China (41176169 and 40930848)
文摘Associations between the autumn Arctic sea ice concentrations (SICs) and North American winter precipitation were examined using singular value decomposition. The results show that a reduced SIC in the majority of the Arctic is accompanied by dry conditions over the Great Plains, the southern United States, Mexico, eastern Alaska, and southeastern Greenland, and by wet conditions over the majority of Canada, the northeastern United States, and the majority of Greenland. Atmospheric circulation anomalies associated with the SIC variability show a wave train structure that is persistent from autumn to winter and is responsible for the covariability between the autumn Arctic SICs and North American winter precipitation. This relationship suggests a potential long-term outlook for the North American winter precipitation.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX2-YW-Q1-02)the National Basic Research Program of China (973 Program, Grant No. 2009CB421406) and the Nansen Scientific Society in Norway
文摘The relationship between the variability of the surface elevation of the Greenland Ice Sheet (GIS) in winter and sea level pressure is identified through analysis of data from satellite-borne radar altimeters, together with meteorological data fields during 1993 2005. We found that both the North Pacific Oscillation (NPO) and the North Atlantic Oscillation (NAO), the two major teleconnection patterns of the atmospheric surface pressure fields in the Northern Hemisphere, significantly influence the GIS winter elevation change. Further, it is suggested that the NPO may affect the GIS accumulation by influencing the NAO, particularly by changing the intensity and location of the Icelandic Low.
基金the Science and Technology Basic Work of the Ministry of Science and Technology of China (No. 2012FY112300)
文摘Temperature and salinity profile data, collected by southern elephant seals equipped with autonomous CTD-Satellite Relay Data Loggers(CTD-SRDLs) during the Antarctic wintertime in 2011 and 2012, were used to study the evolution of water property and the resultant formation of the high density water in the Mackenzie Bay polynya(MBP) in front of the Amery Ice Shelf(AIS). In late March the upper 100–200 m layer is characterized by strong halocline and inversion thermocline. The mixed layer keeps deepening up to 250 m by mid-April with potential temperature remaining nearly the surface freezing point and sea surface salinity increasing from 34.00 to 34.21. From then on until mid-May, the whole water column stays isothermally at about^(-1).90℃while the surface salinity increases by a further 0.23. Hereafter the temperature increases while salinity decreases along with the increasing depth both by 0.1 order of magnitude vertically. The upper ocean heat content ranging from 120.5 to 2.9 MJ m^(-2), heat flux with the values of 9.8–287.0 W m^(-2) loss and the sea ice growth rates of 4.3–11.7 cm d^(-1) were estimated by using simple 1-D heat and salt budget methods. The MBP exists throughout the whole Antarctic winter(March to October) due to the air-sea-ice interaction, with an average size of about 5.0×10~3 km^2. It can be speculated that the decrease of the salinity of the upper ocean may occur after October each year. The recurring sea-ice production and the associated brine rejection process increase the salinity of the water column in the MBP progressively, resulting in, eventually, the formation of a large body of high density water.
基金This work was supported by the Czech Science Foundation(l6-19245S and19-13231S)by Charles University Research Centre program(204069)by long-term research development project no.RVO 67985939 of the Czech Academy of Sciences.
文摘Aims Woody plants represent the ancestral growth form in angiosperms with herbs evolving repeatedly from them.While there are a number of hypotheses about drivers of the evolution of the herbaceous habit,the ability to avoid frost damage in winter by discarding their aboveground biomass has often been invoked as the main force in their evolution.We propose instead that any unpredictable disturbance might have been much more important than the seasonal frost,as herbs easily survive repeated disturbance.Methods We tested this hypothesis by comparing herbs and woody plants in their ability to deal with three types of simulated disturbances,more predictable winter freezing,less predictable spring freezing and herbivory.Comparison was made in an experimental common garden setup with 20 species differing in woodiness.We evaluated the effects of these disturbances on mortality and regrowth of plants.Important Findings Herbs did not have an advantage over woody plants in survival when exposed to winter freezing.In less predictable conditions of spring freezing herbs survived the treatment better than woody plants and this advantage was even larger in case of the simulated herbivory treatment.The advantage of herbs over woody plants in less predictable conditions suggests that herbaceous growth form might be an adaptation to unpredictable disturbance,which herbs are able to tolerate thanks to their ability to survive loss of aboveground biomass.Consequently,factors such as mammal herbivory or fire might have been the most likely factors in the transition from woody species to herbs.
基金The Key Project of National Social Science Foundation (21ATY001)The National Natural Science Foundation of China Youth Project (42001255)
文摘The role of tourism in social and economic development and stabilizing the Olympic legacy has been widely discussed.Beijing is the first“Dual-Olympic City”.For the first time,the Beijing Winter Olympics has adopted a model of three competition areas,which has attracted much attention to the study of its tourism legacy.In the legacy plan,the construction of the“Beijing-Zhangjiakou Sports Culture and Tourism Belt”was proposed.The development of ice and snow tourism and the cultivation of the ice and snow tourism market is also reflected in many policy documents and government actions.The scientific planning before the competition laid a good foundation for the sustainable development of its ice and snow tourism heritage.This research combines Olympic legacy research with tourism destination theory,and focuses on ice and snow tourism directly related to the Winter Olympics and the significance of pre-event planning for legacy protection.At the same time,the improvement of the quality of ice and snow tourism destinations is embedded in the pre-Olympic legacy,and opinions and suggestions on how to ensure the stability of the legacy after the games are given.This study uses the literature review method and the second-hand materials survey research method,then through establishing a tourism legacy pre-game evaluation model and the use of geographic information,government reports,policies,publicly released statistics and news reports,etc..It explores the legacy of the Beijing 2022 Winter Olympics and Paralympics,aiming to lay the foundation for preserving the continuous value of the ice and snow tourism legacy during and after the Olympics.The results indicate that the Beijing Winter Olympics has made relatively complete plans and reliable progress in both tangible and intangible legacy.Complete tourism infrastructure,an optimistic sport and cultural atmosphere,and the improvement of residents’health concept and sports awareness have become boosters for the development of ice and snow tourism in the Beijing-Zhangjiakou region.
文摘Since Beijing and Zhangjiakou in neighboring Hebei Province won the bid to host the 2022 Winter Olympics,the entire country has become increasingly enthusiastic about winter sports.Skiing and skating are popular winter activities while lesser-known games such as curling and ice hockey have also become familiar to sports lovers.
