The Northern Hemisphere(NH)often experiences frequent cold air outbreaks and heavy snowfalls during La Nina winters.In 2022,a third-year La Nina event has exceeded both the oceanic and atmospheric thresholds since spr...The Northern Hemisphere(NH)often experiences frequent cold air outbreaks and heavy snowfalls during La Nina winters.In 2022,a third-year La Nina event has exceeded both the oceanic and atmospheric thresholds since spring and is predicted to reach its mature phase in December 2022.Under such a significant global climate signal,whether the Eurasian Continent will experience a tough cold winter should not be assumed,despite the direct influence of mid-to high-latitude,large-scale atmospheric circulations upon frequent Eurasian cold extremes,whose teleconnection physically operates by favoring Arctic air invasions into Eurasia as a consequence of the reduction of the meridional background temperature gradient in the NH.In the 2022/23 winter,as indicated by the seasonal predictions from various climate models and statistical approaches developed at the Institute of Atmospheric Physics,abnormal warming will very likely cover most parts of Europe under the control of the North Atlantic Oscillation and the anomalous anticyclone near the Ural Mountains,despite the cooling effects of La Nina.At the same time,the possibility of frequent cold conditions in mid-latitude Asia is also recognized for this upcoming winter,in accordance with the tendency for cold air invasions to be triggered by the synergistic effect of a warm Arctic and a cold tropical Pacific on the hemispheric scale.However,how the future climate will evolve in the 2022/23 winter is still subject to some uncertainty,mostly in terms of unpredictable internal atmospheric variability.Consequently,the status of the mid-to high-latitude atmospheric circulation should be timely updated by medium-term numerical weather forecasts and sub-seasonal-to-seasonal prediction for the necessary date information and early warnings.展开更多
Composite analyses were performed in this study to reveal the difference in spring precipitation over southern China during multiyear La Ni?a events during 1901 to 2015. It was found that there is significantly below-...Composite analyses were performed in this study to reveal the difference in spring precipitation over southern China during multiyear La Ni?a events during 1901 to 2015. It was found that there is significantly below-normal precipitation during the first boreal spring, but above-normal precipitation during the second year. The difference in spring precipitation over southern China is correlative to the variation in western North Pacific anomalous cyclone(WNPC), which can in turn be attributed to the different sea surface temperature anomaly(SSTA) over the Tropical Pacific. The remote forcing of negative SSTA in the equatorial central and eastern Pacific and the local air-sea interaction in the western North Pacific are the usual causes of WNPC formation and maintenance.SSTA in the first spring is stronger than those in the second spring. As a result, the intensity of WNPC in the first year is stronger, which is more likely to reduce the moisture in southern China by changing the moisture transport, leading to prolonged precipitation deficits over southern China. However, the tropical SSTA signals in the second year are too weak to induce the formation and maintenance of WNPC and the below-normal precipitation over southern China. Thus, the variation in tropical SSTA signals between two consecutive springs during multiyear La Ni?a events leads to obvious differences in the spatial pattern of precipitation anomaly in southern China by causing the different WNPC response.展开更多
通过对近百年 El Nino/ L a Nina事件与北京气候相关性研究发现 ,El Nino/ L aNina事件与北京夏季 ( 6～ 8月 )降水、平均最高气温 ( 7月 )和冬季 ( 1月 )平均最低气温之间相互关系显著。 El Nino事件与夏季降水、冬季平均最低气温呈负...通过对近百年 El Nino/ L a Nina事件与北京气候相关性研究发现 ,El Nino/ L aNina事件与北京夏季 ( 6～ 8月 )降水、平均最高气温 ( 7月 )和冬季 ( 1月 )平均最低气温之间相互关系显著。 El Nino事件与夏季降水、冬季平均最低气温呈负相关 ,与夏季平均最高气温呈正相关 ,造成降水减少 ,气温年较差增大 ,大陆性增强的气候特点。L a Nina事件与夏季降水、冬季平均最低气温呈正相关 ,与夏季平均最高气温呈负相关 ,使降水增加 ,气温年较差减小 。展开更多
The curved surface of the maximum sea temperature anomaly (MSTA) was created from the JEDAC subsurface sea temperature anomaly data at the tropical Pacific between 1955 and 2000. It is quite similar to the depth distr...The curved surface of the maximum sea temperature anomaly (MSTA) was created from the JEDAC subsurface sea temperature anomaly data at the tropical Pacific between 1955 and 2000. It is quite similar to the depth distribution of the 20℃ isotherm, which is usually the replacement of thermocline. From the distribution and moving trajectory of positive or negative sea temperature anomalies (STA) on the curved surface we analyzed all the El Nino and La Nina events since the later 1960s. Based on the analyses we found that, using the subsurface warm pool as the beginning point, the warm or cold signal propagates initially eastward and upward along the equatorial curved surface of MSTA to the eastern Pacific and stays there several months and then to (urn north, usually moving westward near 10°N to western Pacific and finally propagates southward to return to warm pool to form an off-equator closed circuit. It takes about 2 to 4 years for the temperature anomaly to move around the cycle. If the STA of warm (cold) water is strong enough, there will be two successive El Nino (La Nina) events during the period of 2 to 4 years. Sometime, it becomes weak in motion due to the unsuitable oceanic or atmospheric condition. This kind process may not be considered as an El Nino ( La Nina) event, but the moving trajectory of warm (cold) water can still be recognized. Because of the alternate between warm and cold water around the circuits, the positive (negative) anomaly signal in equatorial western Pacific coexists with negative (positive) anomaly signal near 10°N in eastern Pacific before the outbreak of El Nino (La Nina) event. The signals move in the opposite directions. So it appears as El Nino (La Nina) in equator at 2-4 years intervals. The paper also analyzed several exceptional cases and discussed the effect and importance of oceanic circulation in the evolution of El Nino/ La Nina event.展开更多
Statistic and typical-year composition methods are used to study the northwest Pacific typhoonactivities in relation with the El Nino and La Nina events. The result indicates that the typhoon tends to be inactive in t...Statistic and typical-year composition methods are used to study the northwest Pacific typhoonactivities in relation with the El Nino and La Nina events. The result indicates that the typhoon tends to be inactive in the El Nino years and active in the La Nina years and it is also dependent on the onset and ending time andintensity of the events and areas of genesis of typhoons. With statistic features of the frequency of typhoon activity in the EI Nino and La Nina years and the time-lag correlation between the frequency and sea surface temperature (SST), useful information is provided for the prediction of typhoon occurrence. In addition, the singularvalues disassemble (SVD) method is applied to study the correlation between the geopotential field and SST fief(l.The result shows that the air-sea coupling in the EI Nino years is unfavorable for the typhoon to develop. whichtake place with a smaller number. Opposite situations are found with the La Nina years.展开更多
The increased concentration of greenhouse gases in the atmosphere from human activities traps heat within the climate system and increases ocean heat content(OHC). Here, we provide the first analysis of recent OHC cha...The increased concentration of greenhouse gases in the atmosphere from human activities traps heat within the climate system and increases ocean heat content(OHC). Here, we provide the first analysis of recent OHC changes through 2021 from two international groups. The world ocean, in 2021, was the hottest ever recorded by humans, and the 2021 annual OHC value is even higher than last year’s record value by 14 ± 11 ZJ(1 zetta J = 1021 J) using the IAP/CAS dataset and by16 ± 10 ZJ using NCEI/NOAA dataset. The long-term ocean warming is larger in the Atlantic and Southern Oceans than in other regions and is mainly attributed, via climate model simulations, to an increase in anthropogenic greenhouse gas concentrations. The year-to-year variation of OHC is primarily tied to the El Nino-Southern Oscillation(ENSO). In the seven maritime domains of the Indian, Tropical Atlantic, North Atlantic, Northwest Pacific, North Pacific, Southern oceans,and the Mediterranean Sea, robust warming is observed but with distinct inter-annual to decadal variability. Four out of seven domains showed record-high heat content in 2021. The anomalous global and regional ocean warming established in this study should be incorporated into climate risk assessments, adaptation, and mitigation.展开更多
After the strong 2015/16 El Nino event,cold conditions prevailed in the tropical Pacific with the second-year cooling of the 2017/18 La Ni?a event.Many coupled models failed to predict the cold SST anomalies(SSTAs)in ...After the strong 2015/16 El Nino event,cold conditions prevailed in the tropical Pacific with the second-year cooling of the 2017/18 La Ni?a event.Many coupled models failed to predict the cold SST anomalies(SSTAs)in 2017.By using the ERA5 and GODAS(Global Ocean Data Assimilation System)products,atmospheric and oceanic factors were examined that could have been responsible for the second-year cooling,including surface wind and the subsurface thermal state.A time sequence is described to demonstrate how the cold SSTAs were produced in the central-eastern equatorial Pacific in late 2017.Since July 2017,easterly anomalies strengthened in the central Pacific;in the meantime,wind stress divergence anomalies emerged in the far eastern region,which strengthened during the following months and propagated westward,contributing to the development of the second-year cooling in 2017.At the subsurface,weak negative temperature anomalies were accompanied by upwelling in the eastern equatorial Pacific,which provided the cold water source for the sea surface.Thereafter,both the cold anomalies and upwelling were enhanced and extended westward in the centraleastern equatorial Pacific.These changes were associated with the seasonally weakened EUC(the Equatorial Undercurrent)and strengthened SEC(the South Equatorial Current),which favored more cold waters being accumulated in the central-equatorial Pacific.Then,the subsurface cold waters stretched upward with the convergence of the horizontal currents and eventually outcropped to the surface.The subsurface-induced SSTAs acted to induce local coupled air–sea interactions,which generated atmospheric–oceanic anomalies developing and evolving into the second-year cooling in the fall of 2017.展开更多
伴随着 El Nino 和 La Nina 事件的发生发展，我国东部地区季节降水异常的特征也发生变化。本文通过统计1951-2010年我国东部地区120个站点的月平均降水量资料，利用合成分析的方法，研究中国东部季节降水与 El Nino 和 La Nina 事件的...伴随着 El Nino 和 La Nina 事件的发生发展，我国东部地区季节降水异常的特征也发生变化。本文通过统计1951-2010年我国东部地区120个站点的月平均降水量资料，利用合成分析的方法，研究中国东部季节降水与 El Nino 和 La Nina 事件的关联。结果显示，El Nino 当年冬季和次年春夏季我国东部大部分地区以多雨为主，La Nina 年则相反；长江中下游地区降水显著异常偏多发生在 El Nino 次年春季，且此时长江流域以及河套地区降水量均显著增加，但 La Nina 次年春季该地区雨量无明显变化；El Nino 次年春季和 La Nina 次年夏季西南地区易发生干旱。结果表明 El Nino 和 La Nina 对中国东部季节降水的影响存在非对称性，对于部分地区具有一定的预测意义。展开更多
The impact of La Ni?a on the winter Arctic stratosphere has thus far been an ambiguous topic of research. Contradictory results have been reported depending on the La Ni?a events considered. This study shows that this...The impact of La Ni?a on the winter Arctic stratosphere has thus far been an ambiguous topic of research. Contradictory results have been reported depending on the La Ni?a events considered. This study shows that this is mainly due to the decadal variation of La Ni?a’s impact on the winter Arctic stratosphere since the late 1970 s. Specifically,during the period1951–78,the tropospheric La Ni?a teleconnection exhibits a typical negative Pacific–North America pattern,which strongly inhibits the propagation of the planetary waves from the extratropical troposphere to the stratosphere,and leads to a significantly strengthened stratospheric polar vortex. In contrast,during 1979–2015,the La Ni?a teleconnection shifts eastwards,with an anomalous high concentrated in the northeastern Pacific. The destructive interference of the La Ni?a teleconnection with climatological stationary waves seen in the earlier period reduces greatly,which prevents the drastic reduction of planetary wave activities in the extratropical stratosphere. Correspondingly,the stratospheric response shows a less disturbed stratospheric polar vortex in winter.展开更多
基金supported by the Key Research Program of Frontier Sciences,CAS(Grant No.ZDBS-LY-DQC010)the National Natural Science Foundation of China(Grant No.42175045)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB42000000)。
文摘The Northern Hemisphere(NH)often experiences frequent cold air outbreaks and heavy snowfalls during La Nina winters.In 2022,a third-year La Nina event has exceeded both the oceanic and atmospheric thresholds since spring and is predicted to reach its mature phase in December 2022.Under such a significant global climate signal,whether the Eurasian Continent will experience a tough cold winter should not be assumed,despite the direct influence of mid-to high-latitude,large-scale atmospheric circulations upon frequent Eurasian cold extremes,whose teleconnection physically operates by favoring Arctic air invasions into Eurasia as a consequence of the reduction of the meridional background temperature gradient in the NH.In the 2022/23 winter,as indicated by the seasonal predictions from various climate models and statistical approaches developed at the Institute of Atmospheric Physics,abnormal warming will very likely cover most parts of Europe under the control of the North Atlantic Oscillation and the anomalous anticyclone near the Ural Mountains,despite the cooling effects of La Nina.At the same time,the possibility of frequent cold conditions in mid-latitude Asia is also recognized for this upcoming winter,in accordance with the tendency for cold air invasions to be triggered by the synergistic effect of a warm Arctic and a cold tropical Pacific on the hemispheric scale.However,how the future climate will evolve in the 2022/23 winter is still subject to some uncertainty,mostly in terms of unpredictable internal atmospheric variability.Consequently,the status of the mid-to high-latitude atmospheric circulation should be timely updated by medium-term numerical weather forecasts and sub-seasonal-to-seasonal prediction for the necessary date information and early warnings.
基金The National Natural Science Foundation of China under contract Nos 41576029, 41976221 and 42030410the National Key Research and Development Program of China under contract No. 2019YFA0606702the Startup Foundation for Introducing Talent of Nanjing University of Information Science and Technology。
文摘Composite analyses were performed in this study to reveal the difference in spring precipitation over southern China during multiyear La Ni?a events during 1901 to 2015. It was found that there is significantly below-normal precipitation during the first boreal spring, but above-normal precipitation during the second year. The difference in spring precipitation over southern China is correlative to the variation in western North Pacific anomalous cyclone(WNPC), which can in turn be attributed to the different sea surface temperature anomaly(SSTA) over the Tropical Pacific. The remote forcing of negative SSTA in the equatorial central and eastern Pacific and the local air-sea interaction in the western North Pacific are the usual causes of WNPC formation and maintenance.SSTA in the first spring is stronger than those in the second spring. As a result, the intensity of WNPC in the first year is stronger, which is more likely to reduce the moisture in southern China by changing the moisture transport, leading to prolonged precipitation deficits over southern China. However, the tropical SSTA signals in the second year are too weak to induce the formation and maintenance of WNPC and the below-normal precipitation over southern China. Thus, the variation in tropical SSTA signals between two consecutive springs during multiyear La Ni?a events leads to obvious differences in the spatial pattern of precipitation anomaly in southern China by causing the different WNPC response.
基金This work was supported by the National Natural Science Foundation of China under Grant No.40126002.
文摘The curved surface of the maximum sea temperature anomaly (MSTA) was created from the JEDAC subsurface sea temperature anomaly data at the tropical Pacific between 1955 and 2000. It is quite similar to the depth distribution of the 20℃ isotherm, which is usually the replacement of thermocline. From the distribution and moving trajectory of positive or negative sea temperature anomalies (STA) on the curved surface we analyzed all the El Nino and La Nina events since the later 1960s. Based on the analyses we found that, using the subsurface warm pool as the beginning point, the warm or cold signal propagates initially eastward and upward along the equatorial curved surface of MSTA to the eastern Pacific and stays there several months and then to (urn north, usually moving westward near 10°N to western Pacific and finally propagates southward to return to warm pool to form an off-equator closed circuit. It takes about 2 to 4 years for the temperature anomaly to move around the cycle. If the STA of warm (cold) water is strong enough, there will be two successive El Nino (La Nina) events during the period of 2 to 4 years. Sometime, it becomes weak in motion due to the unsuitable oceanic or atmospheric condition. This kind process may not be considered as an El Nino ( La Nina) event, but the moving trajectory of warm (cold) water can still be recognized. Because of the alternate between warm and cold water around the circuits, the positive (negative) anomaly signal in equatorial western Pacific coexists with negative (positive) anomaly signal near 10°N in eastern Pacific before the outbreak of El Nino (La Nina) event. The signals move in the opposite directions. So it appears as El Nino (La Nina) in equator at 2-4 years intervals. The paper also analyzed several exceptional cases and discussed the effect and importance of oceanic circulation in the evolution of El Nino/ La Nina event.
文摘Statistic and typical-year composition methods are used to study the northwest Pacific typhoonactivities in relation with the El Nino and La Nina events. The result indicates that the typhoon tends to be inactive in the El Nino years and active in the La Nina years and it is also dependent on the onset and ending time andintensity of the events and areas of genesis of typhoons. With statistic features of the frequency of typhoon activity in the EI Nino and La Nina years and the time-lag correlation between the frequency and sea surface temperature (SST), useful information is provided for the prediction of typhoon occurrence. In addition, the singularvalues disassemble (SVD) method is applied to study the correlation between the geopotential field and SST fief(l.The result shows that the air-sea coupling in the EI Nino years is unfavorable for the typhoon to develop. whichtake place with a smaller number. Opposite situations are found with the La Nina years.
基金supported by the National Natural Science Foundation of China(Grant No.42122046,42076202)Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB42040402)+5 种基金National Natural Science Foundation of China(Grant No.42076202)National Key R&D Program of China(Grant No.2017YFA0603202)Key Deployment Project of Centre for Ocean Mega-Research of Science,CAS(Grant Nos.COMS2019Q01 and COMS2019Q07)NCAR is sponsored by the US National Science Foundationsupported by NASA Award 80NSSC17K0565the Regional and Global Model Analysis(RGMA)component of the Earth and Environmental System Modeling Program of the U.S.Department of Energy’s Office of Biological&Environmental Research(BER)via National Science Foundation IA 1844590。
文摘The increased concentration of greenhouse gases in the atmosphere from human activities traps heat within the climate system and increases ocean heat content(OHC). Here, we provide the first analysis of recent OHC changes through 2021 from two international groups. The world ocean, in 2021, was the hottest ever recorded by humans, and the 2021 annual OHC value is even higher than last year’s record value by 14 ± 11 ZJ(1 zetta J = 1021 J) using the IAP/CAS dataset and by16 ± 10 ZJ using NCEI/NOAA dataset. The long-term ocean warming is larger in the Atlantic and Southern Oceans than in other regions and is mainly attributed, via climate model simulations, to an increase in anthropogenic greenhouse gas concentrations. The year-to-year variation of OHC is primarily tied to the El Nino-Southern Oscillation(ENSO). In the seven maritime domains of the Indian, Tropical Atlantic, North Atlantic, Northwest Pacific, North Pacific, Southern oceans,and the Mediterranean Sea, robust warming is observed but with distinct inter-annual to decadal variability. Four out of seven domains showed record-high heat content in 2021. The anomalous global and regional ocean warming established in this study should be incorporated into climate risk assessments, adaptation, and mitigation.
基金jointly supported by grants from the National Natural Science Foundation of China[Grant Nos.41576029 and 41690122(41690120)]the National Program on Global Change and Air–Sea Interaction(Grant No.GASIIPOVAI-03)+1 种基金the National Key Research and Development Program(Grant No.2018YFC1505802)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDA19060102 and XDB 40000000)。
文摘After the strong 2015/16 El Nino event,cold conditions prevailed in the tropical Pacific with the second-year cooling of the 2017/18 La Ni?a event.Many coupled models failed to predict the cold SST anomalies(SSTAs)in 2017.By using the ERA5 and GODAS(Global Ocean Data Assimilation System)products,atmospheric and oceanic factors were examined that could have been responsible for the second-year cooling,including surface wind and the subsurface thermal state.A time sequence is described to demonstrate how the cold SSTAs were produced in the central-eastern equatorial Pacific in late 2017.Since July 2017,easterly anomalies strengthened in the central Pacific;in the meantime,wind stress divergence anomalies emerged in the far eastern region,which strengthened during the following months and propagated westward,contributing to the development of the second-year cooling in 2017.At the subsurface,weak negative temperature anomalies were accompanied by upwelling in the eastern equatorial Pacific,which provided the cold water source for the sea surface.Thereafter,both the cold anomalies and upwelling were enhanced and extended westward in the centraleastern equatorial Pacific.These changes were associated with the seasonally weakened EUC(the Equatorial Undercurrent)and strengthened SEC(the South Equatorial Current),which favored more cold waters being accumulated in the central-equatorial Pacific.Then,the subsurface cold waters stretched upward with the convergence of the horizontal currents and eventually outcropped to the surface.The subsurface-induced SSTAs acted to induce local coupled air–sea interactions,which generated atmospheric–oceanic anomalies developing and evolving into the second-year cooling in the fall of 2017.
文摘伴随着 El Nino 和 La Nina 事件的发生发展，我国东部地区季节降水异常的特征也发生变化。本文通过统计1951-2010年我国东部地区120个站点的月平均降水量资料，利用合成分析的方法，研究中国东部季节降水与 El Nino 和 La Nina 事件的关联。结果显示，El Nino 当年冬季和次年春夏季我国东部大部分地区以多雨为主，La Nina 年则相反；长江中下游地区降水显著异常偏多发生在 El Nino 次年春季，且此时长江流域以及河套地区降水量均显著增加，但 La Nina 次年春季该地区雨量无明显变化；El Nino 次年春季和 La Nina 次年夏季西南地区易发生干旱。结果表明 El Nino 和 La Nina 对中国东部季节降水的影响存在非对称性，对于部分地区具有一定的预测意义。
基金jointly supported by an NSFC project (Grant Nos.41505034,41630423)the China National 973 project (Grant No.2015CB453200)+8 种基金NSF (AGS1565653)NSFC project (Grant No.41475084)NRL (Grant No.N00173-161G906)Jiangsu NSF key project (Grant No.BK20150062)the Startup Foundation for Introducing Talent of NUIST (Grant No.2014R010)a project funded by the Jiangsu Shuang-Chuang Team (Grant No.R2014SCT001)the Startup Foundation for Introducing Talent of NUIST (Grant No.2014R010)the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe China Scholarship Council for funding and travel support
文摘The impact of La Ni?a on the winter Arctic stratosphere has thus far been an ambiguous topic of research. Contradictory results have been reported depending on the La Ni?a events considered. This study shows that this is mainly due to the decadal variation of La Ni?a’s impact on the winter Arctic stratosphere since the late 1970 s. Specifically,during the period1951–78,the tropospheric La Ni?a teleconnection exhibits a typical negative Pacific–North America pattern,which strongly inhibits the propagation of the planetary waves from the extratropical troposphere to the stratosphere,and leads to a significantly strengthened stratospheric polar vortex. In contrast,during 1979–2015,the La Ni?a teleconnection shifts eastwards,with an anomalous high concentrated in the northeastern Pacific. The destructive interference of the La Ni?a teleconnection with climatological stationary waves seen in the earlier period reduces greatly,which prevents the drastic reduction of planetary wave activities in the extratropical stratosphere. Correspondingly,the stratospheric response shows a less disturbed stratospheric polar vortex in winter.
