In recent decades the Arctic surface air temperature(SAT) in autumn has been increasing steadily. In winter, however, instead of a linear trend, the Arctic SAT shows an abrupt change that occurred in 2004. During the ...In recent decades the Arctic surface air temperature(SAT) in autumn has been increasing steadily. In winter, however, instead of a linear trend, the Arctic SAT shows an abrupt change that occurred in 2004. During the years from 1979 to 2003, the first principle component(PC1) of winter Arctic SAT remains stable, and no significant increasing trend is detected. However, the PC1 changes abruptly from negative to positive phase in the winter of 2004. The enhanced Siberian high may have contributed to this abrupt change because the temporal evolution of Arctic temperature correlates significantly with sea level pressure variation in the northern Eurasian continent, and the atmospheric circulation anomaly related to the Siberian high from 2004 to 2013 favors a warmer Arctic. With the help of the meridional wind anomaly around the Siberian high, warmer air is transported to the high latitudes and therefore increases the Arctic temperature.展开更多
The surface air temperature over the Eurasian continent has exhibited a significant cooling trend in recent decades(1990–2013), which has occurred simultaneously with Arctic warming and Arctic sea ice loss. While man...The surface air temperature over the Eurasian continent has exhibited a significant cooling trend in recent decades(1990–2013), which has occurred simultaneously with Arctic warming and Arctic sea ice loss. While many studies demonstrated that midlatitude cold extremes are linked to Arctic warming and Arctic sea ice loss, some studies suggest that they are unrelated.The causal relationship between midlatitude cold extremes and Arctic change is uncertain, and it is thus an unsolved and difficult issue. It has been widely recognized that the severity and location of midlatitude cold extremes are closely related to the persistence, location and movement of blocking systems. It might be possible that the Arctic sea ice decline or the Arctic’s warming influences midlatitude cold extremes by changing the blocking system. This paper reviews the recent research advances on the linkages between the blocking system and Arctic warming. The nonlinear multiscale interaction model of Luo et al.revealed that the magnitude of the meridional gradient(PVy) of the background potential vorticity(PV) is a key parameter that reflects changes in the dispersion and nonlinearity of the blocking system. It was found that Arctic warming played a role in reducing the dispersion of the blocking system and enhancing its nonlinearity by reducing the magnitude of PVy. A small PVyis a favorable background condition for increasing the duration of blocking events and producing midlatitude cold extremes.However, because the magnitude of PVyreflects the difference between the background PVof the Arctic high latitudes and the midlatitude continent, the occurrence of midlatitude cold extremes not only depends on an anomalous background PVover Arctic high latitudes but also on its value over the midlatitudes. Thus, Arctic warming or sea ice decline is not necessary for the occurrence of midlatitude cold extremes.展开更多
The task of vortex boundaries setting is one of the most complexes in examination of factors influencing on the vortex (circulation system) development and destruction. In this study a new approach of vortex analysis ...The task of vortex boundaries setting is one of the most complexes in examination of factors influencing on the vortex (circulation system) development and destruction. In this study a new approach of vortex analysis as a whole system is proposed. It is based on vorticity equation where vorticity (left part of the equation) is defined as time coefficients of EOF-decomposition, which is integrated indexes characterizing individual vortex dynamics. Right part of the vorticity equation depicts internal and external factors influencing on the vortex. It's approbation is done on the example of an arctic-subarctic circulation system including blocking anticyclone in winter 2012 which persisted for a long time over the Atlantic sector of the Arctic and led to the formation of the largest positive air temperature anomalies and the minimum ice cover area in the Barents and Kara seas in the entire history of regular observations. It is shown that the main factor in long-term maintenance of the blocking anticyclone over the Arctic was vorticity advection, which was stabilized by horizontal heat advection.展开更多
Arctic region is experiencing strong warming and related changes in the state of sea ice, permafrost, tundra, marine environment and terrestrial ecosystems. These changes are found in any climatological data set compr...Arctic region is experiencing strong warming and related changes in the state of sea ice, permafrost, tundra, marine environment and terrestrial ecosystems. These changes are found in any climatological data set comprising the Arctic region. This study compares the temperature trends in several surface, satellite and reanalysis data sets. We demonstrate large differences in the 1979-2002 temperature trends. Data sets disagree on the magnitude of the trends as well as on their seasonal, zonal and vertical pattern. It was found that the surface temperature trends are stronger than the trends in the tropospheric temperature for each latitude band north of 50?N for each month except for the months during the ice-melting season. These results emphasize that the conclusions of climate studies drawn on the basis of a single data set analysis should be treated with caution as they may be affected by the artificial biases in data.展开更多
The rate of warming of Arctic surface temperature is about 2–3 times faster than the global mean surface warming. Increases of ice albedo feedback and water vapor as well as moisture intrusion from outside the Arctic...The rate of warming of Arctic surface temperature is about 2–3 times faster than the global mean surface warming. Increases of ice albedo feedback and water vapor as well as moisture intrusion from outside the Arctic all have major roles in this phenomenon. In contrast to this rapid Arctic warming, in recent decades, stronger cold air outbreaks have occurred more frequently during winter in East Asia than were recorded in the 1990s, resulting in severe socioeconomic impacts. A number of related studies have claimed the increased frequency of these stronger cold air outbreaks is linked to the amplified warming in the Arctic through complicated mechanisms. As there are time lags between the observed Arctic warming and East Asian cold weather response at various scales, understanding the entire chain of processes from the Arctic to East Asia has importance for forecasting winter weather in East Asia. There are two pathways linking Arctic warming with East Asian cold weather events. One is the synoptic-scale pathway in the lower troposphere via strengthening of the Siberian High initiated by Ural blocking. The other is the planetary-scale path through the stratosphere via activation of planetary waves and downward propagation, which weakens the polar vortex. This study briefly reviews the current understanding of the linkage mechanisms between Arctic warming and East Asian winter cold weather.展开更多
利用2015年NCEP/NCAR再分析一日四时次资料和日资料,应用区域平均、热流量方程估算等方法对2015年12月29日北极爆发性增温的原因进行研究。结果表明,2015年12月29日北极出现爆发性增温,日增温幅度最高达到25°C以上。增温期间,受到...利用2015年NCEP/NCAR再分析一日四时次资料和日资料,应用区域平均、热流量方程估算等方法对2015年12月29日北极爆发性增温的原因进行研究。结果表明,2015年12月29日北极出现爆发性增温,日增温幅度最高达到25°C以上。增温期间,受到强盛温带气旋系统和反气旋系统的共同作用,增温区域出现强盛的南风,风速最大值达到20 m s-1以上,位置不断北进达到北极点。强盛的南风为北极地区带来强盛的暖平流,同时暖湿空气进入北极后,增温区上空云量明显增加。12月28日至12月29日温度平流由冷平流转变为暖平流,暖平流的中心区域与温度爆发性增长的区域有很好的对应关系,暖平流是北极爆发性增温的重要原因。对于一直处于极夜的北极地区,由于云量的增加,大气顶向上长波辐射减少,加剧了温度的上升。温度平流增温贡献率为20.4%,垂直项的贡献率为-9.9%,非绝热作用贡献率为89.5%,温度平流和非绝热作用共同导致了本次北极地区的爆发性增温,非绝热作用是本次爆发性增温最重要的增温因素。展开更多
基金supported by the National Basic Research Program of China (2013CBA01804 and 2015CB453200)the National Natural Science Foundation of China (41475080 and 41221064)State Oceanic Administration Project (201205007)
文摘In recent decades the Arctic surface air temperature(SAT) in autumn has been increasing steadily. In winter, however, instead of a linear trend, the Arctic SAT shows an abrupt change that occurred in 2004. During the years from 1979 to 2003, the first principle component(PC1) of winter Arctic SAT remains stable, and no significant increasing trend is detected. However, the PC1 changes abruptly from negative to positive phase in the winter of 2004. The enhanced Siberian high may have contributed to this abrupt change because the temporal evolution of Arctic temperature correlates significantly with sea level pressure variation in the northern Eurasian continent, and the atmospheric circulation anomaly related to the Siberian high from 2004 to 2013 favors a warmer Arctic. With the help of the meridional wind anomaly around the Siberian high, warmer air is transported to the high latitudes and therefore increases the Arctic temperature.
基金supported by the National Key Research and Development Program of China (Grant No. 2016YFA0601802)the National Natural Science Foundation of China (Grant No. 41430533)
文摘The surface air temperature over the Eurasian continent has exhibited a significant cooling trend in recent decades(1990–2013), which has occurred simultaneously with Arctic warming and Arctic sea ice loss. While many studies demonstrated that midlatitude cold extremes are linked to Arctic warming and Arctic sea ice loss, some studies suggest that they are unrelated.The causal relationship between midlatitude cold extremes and Arctic change is uncertain, and it is thus an unsolved and difficult issue. It has been widely recognized that the severity and location of midlatitude cold extremes are closely related to the persistence, location and movement of blocking systems. It might be possible that the Arctic sea ice decline or the Arctic’s warming influences midlatitude cold extremes by changing the blocking system. This paper reviews the recent research advances on the linkages between the blocking system and Arctic warming. The nonlinear multiscale interaction model of Luo et al.revealed that the magnitude of the meridional gradient(PVy) of the background potential vorticity(PV) is a key parameter that reflects changes in the dispersion and nonlinearity of the blocking system. It was found that Arctic warming played a role in reducing the dispersion of the blocking system and enhancing its nonlinearity by reducing the magnitude of PVy. A small PVyis a favorable background condition for increasing the duration of blocking events and producing midlatitude cold extremes.However, because the magnitude of PVyreflects the difference between the background PVof the Arctic high latitudes and the midlatitude continent, the occurrence of midlatitude cold extremes not only depends on an anomalous background PVover Arctic high latitudes but also on its value over the midlatitudes. Thus, Arctic warming or sea ice decline is not necessary for the occurrence of midlatitude cold extremes.
基金the National Natural Science Foundation of China[Grants No.41991283]the Research Council of Norway Funded Project BASIC[Grant No.325440]Chinese-Norwegian Collaboration Projects Within Climate funded by the Research Council of Norway(COMBINED)[Grant No.328935].
文摘The task of vortex boundaries setting is one of the most complexes in examination of factors influencing on the vortex (circulation system) development and destruction. In this study a new approach of vortex analysis as a whole system is proposed. It is based on vorticity equation where vorticity (left part of the equation) is defined as time coefficients of EOF-decomposition, which is integrated indexes characterizing individual vortex dynamics. Right part of the vorticity equation depicts internal and external factors influencing on the vortex. It's approbation is done on the example of an arctic-subarctic circulation system including blocking anticyclone in winter 2012 which persisted for a long time over the Atlantic sector of the Arctic and led to the formation of the largest positive air temperature anomalies and the minimum ice cover area in the Barents and Kara seas in the entire history of regular observations. It is shown that the main factor in long-term maintenance of the blocking anticyclone over the Arctic was vorticity advection, which was stabilized by horizontal heat advection.
文摘Arctic region is experiencing strong warming and related changes in the state of sea ice, permafrost, tundra, marine environment and terrestrial ecosystems. These changes are found in any climatological data set comprising the Arctic region. This study compares the temperature trends in several surface, satellite and reanalysis data sets. We demonstrate large differences in the 1979-2002 temperature trends. Data sets disagree on the magnitude of the trends as well as on their seasonal, zonal and vertical pattern. It was found that the surface temperature trends are stronger than the trends in the tropospheric temperature for each latitude band north of 50?N for each month except for the months during the ice-melting season. These results emphasize that the conclusions of climate studies drawn on the basis of a single data set analysis should be treated with caution as they may be affected by the artificial biases in data.
基金supported by the project of Korea Polar Research Institute (Grant no. PE18130)
文摘The rate of warming of Arctic surface temperature is about 2–3 times faster than the global mean surface warming. Increases of ice albedo feedback and water vapor as well as moisture intrusion from outside the Arctic all have major roles in this phenomenon. In contrast to this rapid Arctic warming, in recent decades, stronger cold air outbreaks have occurred more frequently during winter in East Asia than were recorded in the 1990s, resulting in severe socioeconomic impacts. A number of related studies have claimed the increased frequency of these stronger cold air outbreaks is linked to the amplified warming in the Arctic through complicated mechanisms. As there are time lags between the observed Arctic warming and East Asian cold weather response at various scales, understanding the entire chain of processes from the Arctic to East Asia has importance for forecasting winter weather in East Asia. There are two pathways linking Arctic warming with East Asian cold weather events. One is the synoptic-scale pathway in the lower troposphere via strengthening of the Siberian High initiated by Ural blocking. The other is the planetary-scale path through the stratosphere via activation of planetary waves and downward propagation, which weakens the polar vortex. This study briefly reviews the current understanding of the linkage mechanisms between Arctic warming and East Asian winter cold weather.
文摘利用2015年NCEP/NCAR再分析一日四时次资料和日资料,应用区域平均、热流量方程估算等方法对2015年12月29日北极爆发性增温的原因进行研究。结果表明,2015年12月29日北极出现爆发性增温,日增温幅度最高达到25°C以上。增温期间,受到强盛温带气旋系统和反气旋系统的共同作用,增温区域出现强盛的南风,风速最大值达到20 m s-1以上,位置不断北进达到北极点。强盛的南风为北极地区带来强盛的暖平流,同时暖湿空气进入北极后,增温区上空云量明显增加。12月28日至12月29日温度平流由冷平流转变为暖平流,暖平流的中心区域与温度爆发性增长的区域有很好的对应关系,暖平流是北极爆发性增温的重要原因。对于一直处于极夜的北极地区,由于云量的增加,大气顶向上长波辐射减少,加剧了温度的上升。温度平流增温贡献率为20.4%,垂直项的贡献率为-9.9%,非绝热作用贡献率为89.5%,温度平流和非绝热作用共同导致了本次北极地区的爆发性增温,非绝热作用是本次爆发性增温最重要的增温因素。
