The tropical Indian Ocean （TIO） displays a uniform basin-wide warming or cooling in sea surface temperature （SST） during the decay year of E1 Nifio-Southern Oscillation （ENSO） events. This warming or cooling is ...The tropical Indian Ocean （TIO） displays a uniform basin-wide warming or cooling in sea surface temperature （SST） during the decay year of E1 Nifio-Southern Oscillation （ENSO） events. This warming or cooling is called the tropical Indian Ocean Basin Mode （IOBM）. Recent studies showed that the IOBM dominates the interannual variability of the TIO SST and has impacts on the tropical climate from the TIO to the western Pacific. Analyses on a 148-year-long monthly coral δ28O record from the Seychelles Islands demonstrate that the Seychelles coral δ18O not only is associated with the local SST but also indicates the interannul variability of the basin-wide SST in the TIO. Moreover, the Seychelles coral δ180 shows a dominant period of 3-7 years that well represents the variability of the IOBM, which in return is modulated by the inter-decadal climate variability The correlation between the Seychelles coral dlSO and the SST reveals that the coral δ18O lags the SST in the eastern equato- rial Pacific by five months and reaches its peak in the spring following the mature phase of ENSO. The spatial pattern of the first EOF mode indicates that the Seychelles Islands are located at the crucial place of the IOBM. Thus, the Seychelles coral δ80 could be used as a proxy of the IOBM to investigate the ENSO teleconnection on the TIO in terms of long-time climate variability.展开更多
The relationships between the tropical Indian Ocean basin （IOB）/dipole （IOD） mode of SST anomalies （SSTAs） and ENSO phase transition during the following year are examined and compared in observations for the pe...The relationships between the tropical Indian Ocean basin （IOB）/dipole （IOD） mode of SST anomalies （SSTAs） and ENSO phase transition during the following year are examined and compared in observations for the period 1958-2008. Both partial correlation analysis and composite analysis show that both the positive （negative） phase of the lOB and IOD （independent of each other） in the tropical Indian Ocean are possible contributors to the E1 Nino （La Nifia） decay and phase transition to La Nifia （El Nifio） about one year later. However, the influence on ENSO transition induced by the IOB is stronger than that by the IOD. The SSTAs in the equatorial central-eastern Pacific in the coming year originate from subsurface temperature anomalies in the equatorial eastern Indian and western Pacific Ocean, induced by the IOB and IOD through eastward and upward propagation to meet the surface. During this process, however the contribution of the oceanic channel process between the tropical Indian and Pacific oceans is totally different for the IOB and IOD. For the IOD, the influence of the Indonesian Throughflow transport anomalies could propagate to the eastern Pacific to induce the ENSO transition. For the IOB, the impact of the oceanic channel stays and disappears in the western Pacific without propagation to the eastern Pacific.展开更多
Using 20 models of the Coupled Model Intercomparison Project Phase 5 （CMIP5）, the simulation of the Southwest Indian Ocean （SWIO） thermocline dome is evaluated and its role in shaping the Indian Ocean Basin （IOB...Using 20 models of the Coupled Model Intercomparison Project Phase 5 （CMIP5）, the simulation of the Southwest Indian Ocean （SWIO） thermocline dome is evaluated and its role in shaping the Indian Ocean Basin （IOB） mode following E1 Nifio investigated. In most of the CMIP5 models, due to an easterly wind bias along the equator, the simulated SWIO thermocline is too deep, which could further influence the amplitude of the interannual IOB mode. A model with a shallow （deep） thermocline dome tends to simulate a strong （weak） IOB mode, including key attributes such as the SWIO SST warming, antisymmetric pattern during boreal spring, and second North Indian Ocean warming during boreal summer. Under global warming, the thermocline dome deepens with the easterly wind trend along the equator in most of the models. However, the IOB amplitude does not follow such a change of the SWIO thermocline among the models; rather, it follows future changes in both ENSO forcing and local convection feedback, suggesting a decreasing effect of the deepening SWIO thermocline dome on the change in the IOB mode in the future.展开更多
The two leading modes of the interannual variability of the tropical Indian Ocean （TIO） sea surface temperature （SST） anomaly are the Indian Ocean basin mode （IOBM） and the Indian Ocean dipole mode （IODM） from...The two leading modes of the interannual variability of the tropical Indian Ocean （TIO） sea surface temperature （SST） anomaly are the Indian Ocean basin mode （IOBM） and the Indian Ocean dipole mode （IODM） from March to August. In this paper, the relationship between the TIO SST anomaly and the sub-seasonal evolution of the circula- tion and rainfall over East Asia during boreal spring and summer is investigated by using correlation analysis and composite analysis based on multi-source observation data from 1979 to 2013, together with numerical simulations from an atmospheric general circulation model. The results indicate that the impacts of the IOBM on the circulation and rainfall over East Asia vary remarkably from spring to summer. The anomalous anticyclone over the tropical Northwest Pacific induced by the warm IOBM is closely linked with the Pacific-Japan or East Asia-Pacific telecon- nection pattern, which persists from March to August. In the upper troposphere over East Asia, the warm phase of the IOBM generates a significant anticyclonic response from March to May. In June and July, however, the circulation response is characterized by enhanced subtropical westerly flow. A distinct anomalous cyclone is found in August. Overall, the IOBM can exert significant influence on the western North Pacific subtropical high, the South Asian high, and the East Asian jet, which collectively modulate the precipitation anomaly over East Asia. In contrast, the ef- fects of the IODM on the climate anomaly over East Asia are relatively weak in boreal spring and summer. There- fore, studying the impacts of the TIO SST anomaly on the climate anomaly in East Asia should take full account of the different sub-seasonal response during boreal spring and summer.展开更多
Both the tropical Indian and tropical Pacific Oceans are active atmosphere-ocean interactive regions with robust interannual variability, which also constitutes a linkage between the two basins in the mode of variabil...Both the tropical Indian and tropical Pacific Oceans are active atmosphere-ocean interactive regions with robust interannual variability, which also constitutes a linkage between the two basins in the mode of variability. Using a global atmosphere- ocean coupled model, we conducted two experiments （CTRL and PC） to explore the contributions of Indian Ocean interannual sea surface temperature （SST） modes to the occurrence of E1 Nino events. The results show that interannual variability of the SST in the Indian Ocean induces a rapid growth of E1 Nino events during the boreal autumn in an E1 Nino developing year. However, it weakens E1 Nino events or even promotes cold phase conversions in an E1 Nino decaying year. Therefore, the en- tire period of the E1 Nino is shortened by the interannual variations of the Indian Ocean SST. Specifically, during the E1 Nino developing years, the positive Indian Ocean Dipole （IOD） events force an anomalous Walker circulation, which then enhances the existing westerly wind anomalies over the west Pacific. This will cause a warmer E1 Nino event, with some modulations by ocean advection and oceanic Rossby and Kelvin waves. However, with the onset of the South Asian monsoon, the Indian Ocean Basin （IOB） warming SST anomalies excite low level easterly wind anomalies over the west tropical Pacific during the El Nino decaying years. As a result, the E1 Nino event is prompted to change from a warm phase to a cold phase. At the same time, an associated atmospheric anticyclone anomaly appears and leads to a decreasing precipitation anomaly over the northwest Pacific. In summary, with remote forcing in the atmospheric circulation, the IOD mode usually affects the E1 Nino during the developing years, whereas the IOB mode affects the E1 Nino during the decaying years.展开更多
利用英国Hadley中心的海温和NASA的臭氧混合比的月平均再分析资料,计算表征热带印度洋海温变化的主模态(IOB、IOD)的IOBI指数和IODI指数,分析了1980—2015年间热带印度洋海温异常与东亚地区平流层臭氧混合比之间的相关关系,探讨了热带...利用英国Hadley中心的海温和NASA的臭氧混合比的月平均再分析资料,计算表征热带印度洋海温变化的主模态(IOB、IOD)的IOBI指数和IODI指数,分析了1980—2015年间热带印度洋海温异常与东亚地区平流层臭氧混合比之间的相关关系,探讨了热带印度洋海温变化对东亚臭氧层分布的影响.结果表明:(1)热带印度洋海温变化对东亚地区平流层臭氧分布有明显的影响,并且与IOB、IOD的时间变化规律相一致;(2)IOBI、IODI与东亚平流层臭氧变化具有一定的相关关系,特别是在春、秋季节时,平流层低层(70 h Pa)和中层(40h Pa)高度处两者间的相关性尤为显著.展开更多
As the primary interannual signal of variability in the tropical ocean-atmosphere interaction, the El Ni?o-Southern Oscillation has a considerable impact on tropical cyclone(TC) activity over the western North Pacific...As the primary interannual signal of variability in the tropical ocean-atmosphere interaction, the El Ni?o-Southern Oscillation has a considerable impact on tropical cyclone(TC) activity over the western North Pacific(WNP). Both 2018 and2021 were La Ni?a decay years, but TC activity over the WNP during the two summers(June–August) showed notable differences. In 2018, summer TC activity was unusually high with a total of 18 TCs, and the region of TC genesis was mainly in the central and eastern WNP. In contrast, only 9 TCs were generated in summer 2021, and the region of TC genesis was primarily in the western WNP. By comparing the characteristics of the large-scale environmental conditions over the regions of TC genesis, the thermal factors of the tropical oceans, and the activity of the Madden-Julian Oscillation(MJO), this study revealed the possible causes for the marked differences in TC genesis over the WNP during the two summers, which both had a similar background of La Ni?a decay. The Indian Ocean Basin Mode(IOBM) transitioned of a cold anomaly in the winter of 2017/2018and persisted until summer 2018. At the same time, the Pacific Meridional Mode(PMM) maintained a positive phase, leading to eastward and northward displacement of the Western Pacific Subtropical High in summer, and eastward extension of the tropical monsoon trough, which presented conditions conducive to TC genesis over the Northwest Pacific. Moreover, the days when the MJO stagnated in phases 5 and 6 in the summer of 2018 increased by approximately 150% relative to climatological state,providing dynamic conditions favorable for TC formation. In 2021, the IOBM quickly turned to a warm anomaly in March and persisted until summer, whereas the PMM became a negative phase in January and remained so until summer. At the same time,the MJO stagnated in phases 2 and 3 for up to 47 days, with the center of convection located over the western Maritime Continent, producing conditions unconducive to TC genesis over the Northwest Pacific. Thus, despite being under a similar background of La Ni?a decaying year, the distinct evolutions of the IOBM, PMM, and MJO in spring and summer of 2018 and2021 were the main causes of the notable differences in TC activity over the WNP during these two summers, and the anomalies in IOBM and MJO contributed more significantly than those of the PMM.展开更多
基金supported by the National Basic Research Program of China(Grant Nos.2010CB950302,2012CB955603,2013CB-956102,2010CB950101)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA11010103)
文摘The tropical Indian Ocean （TIO） displays a uniform basin-wide warming or cooling in sea surface temperature （SST） during the decay year of E1 Nifio-Southern Oscillation （ENSO） events. This warming or cooling is called the tropical Indian Ocean Basin Mode （IOBM）. Recent studies showed that the IOBM dominates the interannual variability of the TIO SST and has impacts on the tropical climate from the TIO to the western Pacific. Analyses on a 148-year-long monthly coral δ28O record from the Seychelles Islands demonstrate that the Seychelles coral δ18O not only is associated with the local SST but also indicates the interannul variability of the basin-wide SST in the TIO. Moreover, the Seychelles coral δ180 shows a dominant period of 3-7 years that well represents the variability of the IOBM, which in return is modulated by the inter-decadal climate variability The correlation between the Seychelles coral dlSO and the SST reveals that the coral δ18O lags the SST in the eastern equato- rial Pacific by five months and reaches its peak in the spring following the mature phase of ENSO. The spatial pattern of the first EOF mode indicates that the Seychelles Islands are located at the crucial place of the IOBM. Thus, the Seychelles coral δ80 could be used as a proxy of the IOBM to investigate the ENSO teleconnection on the TIO in terms of long-time climate variability.
基金jointly supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA11010102)the NSFC (Grant Nos. 41375094 and 41406028)+1 种基金the "973" project (Grant No. 2012CB956000)the NSFC–Shandong Joint Fund for Marine Science Research Centers (Grant No. U1406401)
文摘The relationships between the tropical Indian Ocean basin （IOB）/dipole （IOD） mode of SST anomalies （SSTAs） and ENSO phase transition during the following year are examined and compared in observations for the period 1958-2008. Both partial correlation analysis and composite analysis show that both the positive （negative） phase of the lOB and IOD （independent of each other） in the tropical Indian Ocean are possible contributors to the E1 Nino （La Nifia） decay and phase transition to La Nifia （El Nifio） about one year later. However, the influence on ENSO transition induced by the IOB is stronger than that by the IOD. The SSTAs in the equatorial central-eastern Pacific in the coming year originate from subsurface temperature anomalies in the equatorial eastern Indian and western Pacific Ocean, induced by the IOB and IOD through eastward and upward propagation to meet the surface. During this process, however the contribution of the oceanic channel process between the tropical Indian and Pacific oceans is totally different for the IOB and IOD. For the IOD, the influence of the Indonesian Throughflow transport anomalies could propagate to the eastern Pacific to induce the ENSO transition. For the IOB, the impact of the oceanic channel stays and disappears in the western Pacific without propagation to the eastern Pacific.
基金supported by the National Basic Research Program of China (Grant Nos.2012CB955600 and 2015CB954300)the National Natural Science Foundation of China (Grant Nos. 41106010 and 41476003)+1 种基金the State Key Laboratory of Tropical Oceanography, Chinese Academy of Sciences (Grant Nos. LTO1206 and LTOZZ1202)a China Meteorological Public Welfare Science Research Project (Grant No. GYHY201306027)
文摘Using 20 models of the Coupled Model Intercomparison Project Phase 5 （CMIP5）, the simulation of the Southwest Indian Ocean （SWIO） thermocline dome is evaluated and its role in shaping the Indian Ocean Basin （IOB） mode following E1 Nifio investigated. In most of the CMIP5 models, due to an easterly wind bias along the equator, the simulated SWIO thermocline is too deep, which could further influence the amplitude of the interannual IOB mode. A model with a shallow （deep） thermocline dome tends to simulate a strong （weak） IOB mode, including key attributes such as the SWIO SST warming, antisymmetric pattern during boreal spring, and second North Indian Ocean warming during boreal summer. Under global warming, the thermocline dome deepens with the easterly wind trend along the equator in most of the models. However, the IOB amplitude does not follow such a change of the SWIO thermocline among the models; rather, it follows future changes in both ENSO forcing and local convection feedback, suggesting a decreasing effect of the deepening SWIO thermocline dome on the change in the IOB mode in the future.
基金Supported by the National Natural Science Foundation of China(91337216)Chinese Academy of Sciences Project(XDA11010402)+1 种基金China Meteorological Administration Special Public Welfare Research Fund(GYHY201406001)Special Program for Applied Research on Super Computation of the NSFC–Guangdong Joint Fund(the second phase)
文摘The two leading modes of the interannual variability of the tropical Indian Ocean （TIO） sea surface temperature （SST） anomaly are the Indian Ocean basin mode （IOBM） and the Indian Ocean dipole mode （IODM） from March to August. In this paper, the relationship between the TIO SST anomaly and the sub-seasonal evolution of the circula- tion and rainfall over East Asia during boreal spring and summer is investigated by using correlation analysis and composite analysis based on multi-source observation data from 1979 to 2013, together with numerical simulations from an atmospheric general circulation model. The results indicate that the impacts of the IOBM on the circulation and rainfall over East Asia vary remarkably from spring to summer. The anomalous anticyclone over the tropical Northwest Pacific induced by the warm IOBM is closely linked with the Pacific-Japan or East Asia-Pacific telecon- nection pattern, which persists from March to August. In the upper troposphere over East Asia, the warm phase of the IOBM generates a significant anticyclonic response from March to May. In June and July, however, the circulation response is characterized by enhanced subtropical westerly flow. A distinct anomalous cyclone is found in August. Overall, the IOBM can exert significant influence on the western North Pacific subtropical high, the South Asian high, and the East Asian jet, which collectively modulate the precipitation anomaly over East Asia. In contrast, the ef- fects of the IODM on the climate anomaly over East Asia are relatively weak in boreal spring and summer. There- fore, studying the impacts of the TIO SST anomaly on the climate anomaly in East Asia should take full account of the different sub-seasonal response during boreal spring and summer.
基金supported by the National Basic Research Program of China(Grant Nos.2010CB428504,2012CB956002)the National Natural Science Foundation of China(Grant Nos.40906005,41105059,41065005,GYHY2011-06017,GYHY201306027)+1 种基金the National Key Technologies R&D Program of China(Grant No.2009BAC51B01)the Jiangsu Collaborative Innovation Center for Climate Change
文摘Both the tropical Indian and tropical Pacific Oceans are active atmosphere-ocean interactive regions with robust interannual variability, which also constitutes a linkage between the two basins in the mode of variability. Using a global atmosphere- ocean coupled model, we conducted two experiments （CTRL and PC） to explore the contributions of Indian Ocean interannual sea surface temperature （SST） modes to the occurrence of E1 Nino events. The results show that interannual variability of the SST in the Indian Ocean induces a rapid growth of E1 Nino events during the boreal autumn in an E1 Nino developing year. However, it weakens E1 Nino events or even promotes cold phase conversions in an E1 Nino decaying year. Therefore, the en- tire period of the E1 Nino is shortened by the interannual variations of the Indian Ocean SST. Specifically, during the E1 Nino developing years, the positive Indian Ocean Dipole （IOD） events force an anomalous Walker circulation, which then enhances the existing westerly wind anomalies over the west Pacific. This will cause a warmer E1 Nino event, with some modulations by ocean advection and oceanic Rossby and Kelvin waves. However, with the onset of the South Asian monsoon, the Indian Ocean Basin （IOB） warming SST anomalies excite low level easterly wind anomalies over the west tropical Pacific during the El Nino decaying years. As a result, the E1 Nino event is prompted to change from a warm phase to a cold phase. At the same time, an associated atmospheric anticyclone anomaly appears and leads to a decreasing precipitation anomaly over the northwest Pacific. In summary, with remote forcing in the atmospheric circulation, the IOD mode usually affects the E1 Nino during the developing years, whereas the IOB mode affects the E1 Nino during the decaying years.
文摘利用英国Hadley中心的海温和NASA的臭氧混合比的月平均再分析资料,计算表征热带印度洋海温变化的主模态(IOB、IOD)的IOBI指数和IODI指数,分析了1980—2015年间热带印度洋海温异常与东亚地区平流层臭氧混合比之间的相关关系,探讨了热带印度洋海温变化对东亚臭氧层分布的影响.结果表明:(1)热带印度洋海温变化对东亚地区平流层臭氧分布有明显的影响,并且与IOB、IOD的时间变化规律相一致;(2)IOBI、IODI与东亚平流层臭氧变化具有一定的相关关系,特别是在春、秋季节时,平流层低层(70 h Pa)和中层(40h Pa)高度处两者间的相关性尤为显著.
基金supported by the National Key R&D Program of China (Grant No.2022YFF0801604)the National Natural Science Foundation of China (Grant No.42175056)+4 种基金the Provincial Natural Science Foundation of Anhui (Grant No.2208085UQ10)the Civilian Space Programme of China (Grant No.Do40305)the Fengyun Application Pioneering Project (Grant No.FY-APP-ZX-2023.02)the China Meteorological Administration Innovation and Development Project (Grant No.CXFZ2024J048)the China Meteorological Administration Youth Innovation Team (Grant No.CMA2024QN06)。
文摘As the primary interannual signal of variability in the tropical ocean-atmosphere interaction, the El Ni?o-Southern Oscillation has a considerable impact on tropical cyclone(TC) activity over the western North Pacific(WNP). Both 2018 and2021 were La Ni?a decay years, but TC activity over the WNP during the two summers(June–August) showed notable differences. In 2018, summer TC activity was unusually high with a total of 18 TCs, and the region of TC genesis was mainly in the central and eastern WNP. In contrast, only 9 TCs were generated in summer 2021, and the region of TC genesis was primarily in the western WNP. By comparing the characteristics of the large-scale environmental conditions over the regions of TC genesis, the thermal factors of the tropical oceans, and the activity of the Madden-Julian Oscillation(MJO), this study revealed the possible causes for the marked differences in TC genesis over the WNP during the two summers, which both had a similar background of La Ni?a decay. The Indian Ocean Basin Mode(IOBM) transitioned of a cold anomaly in the winter of 2017/2018and persisted until summer 2018. At the same time, the Pacific Meridional Mode(PMM) maintained a positive phase, leading to eastward and northward displacement of the Western Pacific Subtropical High in summer, and eastward extension of the tropical monsoon trough, which presented conditions conducive to TC genesis over the Northwest Pacific. Moreover, the days when the MJO stagnated in phases 5 and 6 in the summer of 2018 increased by approximately 150% relative to climatological state,providing dynamic conditions favorable for TC formation. In 2021, the IOBM quickly turned to a warm anomaly in March and persisted until summer, whereas the PMM became a negative phase in January and remained so until summer. At the same time,the MJO stagnated in phases 2 and 3 for up to 47 days, with the center of convection located over the western Maritime Continent, producing conditions unconducive to TC genesis over the Northwest Pacific. Thus, despite being under a similar background of La Ni?a decaying year, the distinct evolutions of the IOBM, PMM, and MJO in spring and summer of 2018 and2021 were the main causes of the notable differences in TC activity over the WNP during these two summers, and the anomalies in IOBM and MJO contributed more significantly than those of the PMM.
