While Arctic sea ice has been decreasing in recent decades that is largely due to anthropogenic forcing,the extent of Antarctic sea ice showed a positive trend during 1979–2015, followed by an abrupt decrease. The sh...While Arctic sea ice has been decreasing in recent decades that is largely due to anthropogenic forcing,the extent of Antarctic sea ice showed a positive trend during 1979–2015, followed by an abrupt decrease. The shortness of the satellite record limits our ability to quantify the possible contribution of anthropogenic forcing and internal variability to the observed Antarctic sea ice variability. In this study,ice core and fast ice records with annual resolution from six sites are used to reconstruct the annualresolved northernmost latitude of sea ice edge(NLSIE) for different sectors of the Southern Ocean, including the Weddell Sea(WS), Bellingshausen Sea(BS), Amundsen Sea(AS), Ross Sea(RS), and the Indian and western Pacific Ocean(Ind WPac). The linear trends of the NLSIE are analyzed for each sector for the past100–200 years and found to be à0.08°, à0.17°, +0.07°, +0.02°, and à0.03° per decade(!95% confidence level) for the WS, BS, AS, RS, and Ind WPac, respectively. For the entire Antarctic, our composite NLSIE shows a decreasing trend(à0.03° per decade, 99% confidence level) during the 20 th century, with a rapid decline in the mid-1950 s. It was not until the early 1980 s that the observed increasing trend occurred. A comparison with major climate indices shows that the long-term linear trends in all five sectors are largely dominated by the changes in the Southern Annular Mode(SAM). The multi-decadal variability in WS,BS, and AS is dominated by the Interdecadal Pacific Oscillation, whereas that in the Ind WPac and RS is dominated by the SAM.展开更多
Long time series of Antarctic sea ice extent (SIE) are important for climate research and model forecasting. A historic ice extent in the Ross Sea in early austral winter was rebuilt through sea salt ions in the DT4...Long time series of Antarctic sea ice extent (SIE) are important for climate research and model forecasting. A historic ice extent in the Ross Sea in early austral winter was rebuilt through sea salt ions in the DT401 ice core in interior East Antarctica. El Nino-Southern Oscillation (ENSO) had a significant influence on the sea salt deposition in DT401 through its influence on the Ross Sea SIE and the transport of sea salt inland. Spectral analysis also supported the influence of ENSO with a significant 2-6 a periodicity band. In addition, statistically significant decadal (10 a) and pentadecadal (50-70 a) periodicities suggested the existence of a teleconnection from the Pacific decadal oscillation (PDO), which originated from sea surface temperature anomalies in the tropical Pacific Ocean. The first eigenvector of the empirical orthogonal function analysis (EOF1) showed lower values during the Medieval Warm Period (MWP), while higher values were found in the Little Ice Age (LIA). A higher frequency of ENSO events were found in the cold climatic stage, The post 1800 AD period was occupied by significant fluctuations of the EOF1, and PDO may be one of the influencing factors. The EOF1 values showed moderate fluctuations from 680 BC to 1000 AD, showing that the climate was relatively stable in this period.展开更多
Based on the merged satellite altimeter data and in-situ observations, as well as a diagnosis of linear baroclinic Rossby wave solutions, this study analyzed the rapidly rise of sea level/sea surface height (SSH) in...Based on the merged satellite altimeter data and in-situ observations, as well as a diagnosis of linear baroclinic Rossby wave solutions, this study analyzed the rapidly rise of sea level/sea surface height (SSH) in the tropical Pacific and Indian Oceans during recent two decades. Results show that the sea level rise signals in the tropical west Pacific and the southeast Indian Ocean are closely linked to each other through the pathways of oceanic waveguide within the Indonesian Seas in the form of thermocline adjustment. The sea level changes in the southeast Indian Ocean are strongly influenced by the low-frequency westward-propagating waves originated in the tropical Pacific, whereas those in the southwest Indian Ocean respond mainly to the local wind forcing. Analyses of the lead-lag correlation further reveal the different origins of interannual and interdecadal variabilities in the tropical Pacific. The interannual wave signals are dominated by the wind variability along the equatorial Pa- cific, which is associated with the El Nifio-Southern Oscillation; whereas the interdecadal signals are driven mainly by the wind curl off the equatorial Pacific, which is closely related to the Pacific Decadal Oscillation.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA19070103)the National Key Research & Development Program of China (2018YFA0605901)+1 种基金the State Key Laboratory of Cryospheric Science (SKLCS-ZZ-2021)the National Natural Science Foundation of China (42071086, 41425003, 41941009)。
文摘While Arctic sea ice has been decreasing in recent decades that is largely due to anthropogenic forcing,the extent of Antarctic sea ice showed a positive trend during 1979–2015, followed by an abrupt decrease. The shortness of the satellite record limits our ability to quantify the possible contribution of anthropogenic forcing and internal variability to the observed Antarctic sea ice variability. In this study,ice core and fast ice records with annual resolution from six sites are used to reconstruct the annualresolved northernmost latitude of sea ice edge(NLSIE) for different sectors of the Southern Ocean, including the Weddell Sea(WS), Bellingshausen Sea(BS), Amundsen Sea(AS), Ross Sea(RS), and the Indian and western Pacific Ocean(Ind WPac). The linear trends of the NLSIE are analyzed for each sector for the past100–200 years and found to be à0.08°, à0.17°, +0.07°, +0.02°, and à0.03° per decade(!95% confidence level) for the WS, BS, AS, RS, and Ind WPac, respectively. For the entire Antarctic, our composite NLSIE shows a decreasing trend(à0.03° per decade, 99% confidence level) during the 20 th century, with a rapid decline in the mid-1950 s. It was not until the early 1980 s that the observed increasing trend occurred. A comparison with major climate indices shows that the long-term linear trends in all five sectors are largely dominated by the changes in the Southern Annular Mode(SAM). The multi-decadal variability in WS,BS, and AS is dominated by the Interdecadal Pacific Oscillation, whereas that in the Ind WPac and RS is dominated by the SAM.
基金financially supported by the National Natural Science Foundation of China(Grant No.41121001)National Basic Research Program of China(Grant No.2013CBA01804)+2 种基金State Key Laboratory of Cryospheric Sciences,National Natural Science Foundation of China(Grant No.41201069)State Oceanic Administration of People’s Republic of China Project on Climate in Polar Regions(Grant Nos.CHINARE 2014-04-04,CHINARE 2014-02-02)the Foundation for Excellent Youth Scholars of CAREERI,CAS
文摘Long time series of Antarctic sea ice extent (SIE) are important for climate research and model forecasting. A historic ice extent in the Ross Sea in early austral winter was rebuilt through sea salt ions in the DT401 ice core in interior East Antarctica. El Nino-Southern Oscillation (ENSO) had a significant influence on the sea salt deposition in DT401 through its influence on the Ross Sea SIE and the transport of sea salt inland. Spectral analysis also supported the influence of ENSO with a significant 2-6 a periodicity band. In addition, statistically significant decadal (10 a) and pentadecadal (50-70 a) periodicities suggested the existence of a teleconnection from the Pacific decadal oscillation (PDO), which originated from sea surface temperature anomalies in the tropical Pacific Ocean. The first eigenvector of the empirical orthogonal function analysis (EOF1) showed lower values during the Medieval Warm Period (MWP), while higher values were found in the Little Ice Age (LIA). A higher frequency of ENSO events were found in the cold climatic stage, The post 1800 AD period was occupied by significant fluctuations of the EOF1, and PDO may be one of the influencing factors. The EOF1 values showed moderate fluctuations from 680 BC to 1000 AD, showing that the climate was relatively stable in this period.
基金supported by the "Strategic Priority Research Program" of the Chinese Academy of Sciences (Grant No. XDA11010103)the National Basic Research Program of China (Grant Nos. 2012CB955603, 2010CB950302)+1 种基金National Natural Science Foundation of China (Grant Nos. 41176024, 41176028)supported by the CAS/SAFEA International Partnership Program for Creative Research Teams
文摘Based on the merged satellite altimeter data and in-situ observations, as well as a diagnosis of linear baroclinic Rossby wave solutions, this study analyzed the rapidly rise of sea level/sea surface height (SSH) in the tropical Pacific and Indian Oceans during recent two decades. Results show that the sea level rise signals in the tropical west Pacific and the southeast Indian Ocean are closely linked to each other through the pathways of oceanic waveguide within the Indonesian Seas in the form of thermocline adjustment. The sea level changes in the southeast Indian Ocean are strongly influenced by the low-frequency westward-propagating waves originated in the tropical Pacific, whereas those in the southwest Indian Ocean respond mainly to the local wind forcing. Analyses of the lead-lag correlation further reveal the different origins of interannual and interdecadal variabilities in the tropical Pacific. The interannual wave signals are dominated by the wind variability along the equatorial Pa- cific, which is associated with the El Nifio-Southern Oscillation; whereas the interdecadal signals are driven mainly by the wind curl off the equatorial Pacific, which is closely related to the Pacific Decadal Oscillation.