In 2018,summer precipitation was above normal in North and Northwest China and below normal around the Yangtze River valley,due to an extremely strong East Asian summer monsoon(EASM).The atmospheric circulation anomal...In 2018,summer precipitation was above normal in North and Northwest China and below normal around the Yangtze River valley,due to an extremely strong East Asian summer monsoon(EASM).The atmospheric circulation anomalies in East Asia and key external forcing factors that influence the EASM in 2018 are explored in this paper.The results show that there existed an anomalous cyclonic circulation near the Philippines,while the western Pacific subtropical high was located more northward than its normal position.In the mid–high latitudes,a negative geopotential height anomaly center was found near the Ural Mountains,suppressing the blocking activity.Under such a circulation pattern,precipitation near the Yangtze River valley decreased because local divergence and subsidence intensified,whereas precipitation in northern China increased due to large amounts of water vapor transport by anomalously strong southerly winds.Further analyses reveal that the strong EASM circulation in 2018 might result from the joint influences of several external forcing factors.The weak La Ni?a event that started from October 2017,the positive North Atlantic Tripolar mode(NAT)in spring 2018,and the reduced snow cover over the Tibetan Plateau in winter 2017/18 all collaboratively contributed to formation of the cyclonic circulation anomaly near the Philippines,leading to the extremely strong EASM.Especially,the positive NAT and the reduced Tibetan snow cover may have caused the negative geopotential height anomaly near the Ural Mountains,in favor of a strong EASM.The above external factors and their reinforcing impacts on the EASM are further verified by two groups of similar historical cases.展开更多
The horizontal coordinate systems commonly used in most global ocean models are the spherical latitude-longit- ude grid and displaced poles, such as a tripolar grid. The effect of the horizontal coordinate system on A...The horizontal coordinate systems commonly used in most global ocean models are the spherical latitude-longit- ude grid and displaced poles, such as a tripolar grid. The effect of the horizontal coordinate system on Atlantic meri- dional overturning circulation （AMOC） is evaluated by using an OGCM （ocean general circulation model）. Two ex- periments are conducted with the model---one using a latitude-longitude grid （referred to as Latl） and the other us- ing a tripolar grid （referred to as Tri）. The results show that Tri simulates a stronger North Atlantic deep water （NADW） than Lat_l, as more saline water masses enter the Greenland-Iceland-Norwegian （GIN） seas in Tri. The stronger NADW can be attributed to two factors. One is the removal of the zonal filter in Tri, which leads to an in- creasing of the zonal gradient of temperature and salinity, thus strengthening the north geostrophic flow. In turn, it decreases the positive subsurface temperature and salinity biases in the subtropical regions. The other may be associ- ated with topography at the North Pole, because realistic topography is applied in the tripolar grid while the latitude-longitude grid employs an artificial island around the North Pole. In order to evaluate the effect of the filter on AMOC, three enhanced filter experiments are carried out. Compared to Lat_l, an enhanced filter can also aug- ment NADW formation, since more saline water is suppressed in the GIN seas, but accumulated in the Labrador Sea, especially in experiment Lat_2 S, which is the experiment with an enhanced filter on salinity.展开更多
Since the financial crisis hit in 2007, the US dollar privilege has not only become ＂exorbitant＂ but ＂extortianate. ＂ Countries such as China are no longer willing to allow the USA to exercise this extortionate be...Since the financial crisis hit in 2007, the US dollar privilege has not only become ＂exorbitant＂ but ＂extortianate. ＂ Countries such as China are no longer willing to allow the USA to exercise this extortionate behavior. The potential geopolitical implications of a US dollar decline are immense. The USA would lose its privileged seigniorage position and with that the ability to achieve permanently higher returns on foreign assets than the returns paid to foreigners who invest in the USA. The global economy is already close to operating with three regional exchange rate anchors： the US dollar; the euro; and, increasingly, the renminbi. Hence, the transition to a tripolar system could occur sooner than many assert. Nevertheless, given the importance of financial deepening and integration in the internationalization of currencies, any shift will still be gradual.展开更多
The effect of solar wind（SW） on the North Atlantic sea surface temperature（SST） in boreal winter is examined through an analysis of observational data during 1964-2013.The North Atlantic SSTs show a pronounced mer...The effect of solar wind（SW） on the North Atlantic sea surface temperature（SST） in boreal winter is examined through an analysis of observational data during 1964-2013.The North Atlantic SSTs show a pronounced meridional tripolar pattern in response to solar wind speed（SWS） variations.This pattern is broadly similar to the leading empirical orthogonal function（EOF） mode of interannual variations in the wintertime SSTs over North Atlantic.The time series of this leading EOF mode of SST shows a significant interannual period,which is the same as that of wintertime SWS.This response also appears as a compact north-south seesaw of sea level pressure and a vertical tripolar structure of zonal wind,which simultaneously resembles the North Atlantic Oscillation（NAO） in the overlying atmosphere.As compared with the typical low SWS winters,during the typical high SWS winters,the stratospheric polar night jet（PNJ） is evidently enhanced and extends from the stratosphere to the troposphere,even down to the North Atlantic Ocean surface.Notably,the North Atlantic Ocean is an exclusive region in which the SW signal spreads downward from the stratosphere to the troposphere.Thus,it seems that the SW is a possible factor for this North Atlantic SST tripolar mode.The dynamical process of stratosphere-troposphere coupling,together with the global atmospheric electric circuit-cloud microphysical process,probably accounts for the particular downward propagation of the SW signal.展开更多
The spindle behavior and MPF activity changes in the progression of oocyte maturation were investigated and compared with cytological observation and kinase assay between gynogenetic silver crucian carp and amphimicti...The spindle behavior and MPF activity changes in the progression of oocyte maturation were investigated and compared with cytological observation and kinase assay between gynogenetic silver crucian carp and amphimictic colored crucian carp. MPF activity was measured by using histone H1 as phosphorylation substrate. There were two similar oscillatory MPF kinase activity changes during oocyte maturation in two kinds of fishes with different reproductive modes, but there existed some subtle difference between them. The subtle difference was that the first peak of MPF kinase activity was kept to a longerlasting time in the gynogenetic silver crucian carp than in the amphimictic colored crucian carp. It was suggested that the difference may be related to the spindle behavior changes, such as tripolar spindle formation and spindle rearrangement in the gynogenetic crucian carp.展开更多
This article presents a study we have made of one class of coherent structures of the tripolar vortex. Considering the sheared flow and sheared magnetic field which are common in the thermonuclear plasma and space pla...This article presents a study we have made of one class of coherent structures of the tripolar vortex. Considering the sheared flow and sheared magnetic field which are common in the thermonuclear plasma and space plasma, we have simulated the dynamics of the tripolar vortex. The results show that the tripolar vortex is largely stable in most cases, but a strongly sheared magnetic field will make the structure less stable, and lead it to decays into single vortices with the large space scale. These results are consistent with findings from former research about the dipolar vortex.展开更多
本文发展了一个可以适用于任意水平正交曲线坐标系的海洋模式动力框架,并将其应用于中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室发展的气候系统海洋模式LICOM2.0(LASG/IAP Climate system Ocean Model,versi...本文发展了一个可以适用于任意水平正交曲线坐标系的海洋模式动力框架,并将其应用于中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室发展的气候系统海洋模式LICOM2.0(LASG/IAP Climate system Ocean Model,version2.0)。在经纬网格坐标系下,新的动力框架与LICOM2.0原有的动力框架模拟结果完全一致。基于新的动力框架,海洋模式可采用能够准确描述北冰洋地形的三极网格,克服了LICOM2.0经纬网格版本必须将北极点处理为孤岛的缺陷,从而显著改进了模式对于北冰洋环流和北大西洋经圈翻转流函数(AMOC)的模拟能力。此外,引进三极网格还可以避免模式网格距随纬度增加而急剧减小带来的计算不稳定,在LICOM2.0的三极网格版本中,模式不需要采用任何空间滤波方案仍然能够保证计算的稳定性,从而与LICOM2.0的经纬网格版本相比,极大地提高了模式的并行效率,这一点在当水平分辨率提高到0.1度时表现得尤为明显,海洋模式的并行加速比可以从经纬网格版本的5.8左右提高到三极网格版本的15.0左右。展开更多
基金the National Key Research and Development Program of China(2018YFC1506006)National Science and Technology Support Program of China(2015BAC03B04)National Natural Science Foundation of China(41805067 and 41275073)
文摘In 2018,summer precipitation was above normal in North and Northwest China and below normal around the Yangtze River valley,due to an extremely strong East Asian summer monsoon(EASM).The atmospheric circulation anomalies in East Asia and key external forcing factors that influence the EASM in 2018 are explored in this paper.The results show that there existed an anomalous cyclonic circulation near the Philippines,while the western Pacific subtropical high was located more northward than its normal position.In the mid–high latitudes,a negative geopotential height anomaly center was found near the Ural Mountains,suppressing the blocking activity.Under such a circulation pattern,precipitation near the Yangtze River valley decreased because local divergence and subsidence intensified,whereas precipitation in northern China increased due to large amounts of water vapor transport by anomalously strong southerly winds.Further analyses reveal that the strong EASM circulation in 2018 might result from the joint influences of several external forcing factors.The weak La Ni?a event that started from October 2017,the positive North Atlantic Tripolar mode(NAT)in spring 2018,and the reduced snow cover over the Tibetan Plateau in winter 2017/18 all collaboratively contributed to formation of the cyclonic circulation anomaly near the Philippines,leading to the extremely strong EASM.Especially,the positive NAT and the reduced Tibetan snow cover may have caused the negative geopotential height anomaly near the Ural Mountains,in favor of a strong EASM.The above external factors and their reinforcing impacts on the EASM are further verified by two groups of similar historical cases.
基金Supported by the National(Key)Basic Research and Development(973)Program of China(2013CB956204)National Natural Science Foundation of China(41530426)
文摘The horizontal coordinate systems commonly used in most global ocean models are the spherical latitude-longit- ude grid and displaced poles, such as a tripolar grid. The effect of the horizontal coordinate system on Atlantic meri- dional overturning circulation （AMOC） is evaluated by using an OGCM （ocean general circulation model）. Two ex- periments are conducted with the model---one using a latitude-longitude grid （referred to as Latl） and the other us- ing a tripolar grid （referred to as Tri）. The results show that Tri simulates a stronger North Atlantic deep water （NADW） than Lat_l, as more saline water masses enter the Greenland-Iceland-Norwegian （GIN） seas in Tri. The stronger NADW can be attributed to two factors. One is the removal of the zonal filter in Tri, which leads to an in- creasing of the zonal gradient of temperature and salinity, thus strengthening the north geostrophic flow. In turn, it decreases the positive subsurface temperature and salinity biases in the subtropical regions. The other may be associ- ated with topography at the North Pole, because realistic topography is applied in the tripolar grid while the latitude-longitude grid employs an artificial island around the North Pole. In order to evaluate the effect of the filter on AMOC, three enhanced filter experiments are carried out. Compared to Lat_l, an enhanced filter can also aug- ment NADW formation, since more saline water is suppressed in the GIN seas, but accumulated in the Labrador Sea, especially in experiment Lat_2 S, which is the experiment with an enhanced filter on salinity.
文摘Since the financial crisis hit in 2007, the US dollar privilege has not only become ＂exorbitant＂ but ＂extortianate. ＂ Countries such as China are no longer willing to allow the USA to exercise this extortionate behavior. The potential geopolitical implications of a US dollar decline are immense. The USA would lose its privileged seigniorage position and with that the ability to achieve permanently higher returns on foreign assets than the returns paid to foreigners who invest in the USA. The global economy is already close to operating with three regional exchange rate anchors： the US dollar; the euro; and, increasingly, the renminbi. Hence, the transition to a tripolar system could occur sooner than many assert. Nevertheless, given the importance of financial deepening and integration in the internationalization of currencies, any shift will still be gradual.
基金Supported by the National(Key)Basic Research and Development(973)Program of China(2012CB957804)National Natural Science Foundation of China(41490642 and 41375069)
文摘The effect of solar wind（SW） on the North Atlantic sea surface temperature（SST） in boreal winter is examined through an analysis of observational data during 1964-2013.The North Atlantic SSTs show a pronounced meridional tripolar pattern in response to solar wind speed（SWS） variations.This pattern is broadly similar to the leading empirical orthogonal function（EOF） mode of interannual variations in the wintertime SSTs over North Atlantic.The time series of this leading EOF mode of SST shows a significant interannual period,which is the same as that of wintertime SWS.This response also appears as a compact north-south seesaw of sea level pressure and a vertical tripolar structure of zonal wind,which simultaneously resembles the North Atlantic Oscillation（NAO） in the overlying atmosphere.As compared with the typical low SWS winters,during the typical high SWS winters,the stratospheric polar night jet（PNJ） is evidently enhanced and extends from the stratosphere to the troposphere,even down to the North Atlantic Ocean surface.Notably,the North Atlantic Ocean is an exclusive region in which the SW signal spreads downward from the stratosphere to the troposphere.Thus,it seems that the SW is a possible factor for this North Atlantic SST tripolar mode.The dynamical process of stratosphere-troposphere coupling,together with the global atmospheric electric circuit-cloud microphysical process,probably accounts for the particular downward propagation of the SW signal.
文摘The spindle behavior and MPF activity changes in the progression of oocyte maturation were investigated and compared with cytological observation and kinase assay between gynogenetic silver crucian carp and amphimictic colored crucian carp. MPF activity was measured by using histone H1 as phosphorylation substrate. There were two similar oscillatory MPF kinase activity changes during oocyte maturation in two kinds of fishes with different reproductive modes, but there existed some subtle difference between them. The subtle difference was that the first peak of MPF kinase activity was kept to a longerlasting time in the gynogenetic silver crucian carp than in the amphimictic colored crucian carp. It was suggested that the difference may be related to the spindle behavior changes, such as tripolar spindle formation and spindle rearrangement in the gynogenetic crucian carp.
基金The project supported by the National Natural Science Foundation of China (Nos. 10075047, 40336052)
文摘This article presents a study we have made of one class of coherent structures of the tripolar vortex. Considering the sheared flow and sheared magnetic field which are common in the thermonuclear plasma and space plasma, we have simulated the dynamics of the tripolar vortex. The results show that the tripolar vortex is largely stable in most cases, but a strongly sheared magnetic field will make the structure less stable, and lead it to decays into single vortices with the large space scale. These results are consistent with findings from former research about the dipolar vortex.
文摘本文发展了一个可以适用于任意水平正交曲线坐标系的海洋模式动力框架,并将其应用于中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室发展的气候系统海洋模式LICOM2.0(LASG/IAP Climate system Ocean Model,version2.0)。在经纬网格坐标系下,新的动力框架与LICOM2.0原有的动力框架模拟结果完全一致。基于新的动力框架,海洋模式可采用能够准确描述北冰洋地形的三极网格,克服了LICOM2.0经纬网格版本必须将北极点处理为孤岛的缺陷,从而显著改进了模式对于北冰洋环流和北大西洋经圈翻转流函数(AMOC)的模拟能力。此外,引进三极网格还可以避免模式网格距随纬度增加而急剧减小带来的计算不稳定,在LICOM2.0的三极网格版本中,模式不需要采用任何空间滤波方案仍然能够保证计算的稳定性,从而与LICOM2.0的经纬网格版本相比,极大地提高了模式的并行效率,这一点在当水平分辨率提高到0.1度时表现得尤为明显,海洋模式的并行加速比可以从经纬网格版本的5.8左右提高到三极网格版本的15.0左右。
