The Silk Road pattern（SRP）, which is a teleconnection pattern along the Asian upper-tropospheric westerly jet in summer, exhibits both interannual and decadal variabilities. Through the nineyear Gaussian filtering m...The Silk Road pattern（SRP）, which is a teleconnection pattern along the Asian upper-tropospheric westerly jet in summer, exhibits both interannual and decadal variabilities. Through the nineyear Gaussian filtering method and regression analyses, this study compares the interannual and decadal components of the SRP. The results indicate that the interannual SRP corresponds to a well-organized wave train of alternate cyclonic and anticyclonic anomalies across the Eurasian continent along the Asian westerly jet, resulting in a similar wave-like pattern of cold and warm surface temperature anomalies. This pattern of temperature anomalies differs from that associated with the original SRP, which is characterized by warmer or cooler temperatures mainly over Europe–West Asia and Northeast Asia, depending on the phase of the SRP. On the other hand, the decadal SRP shows a similar pattern to the interannual one from Europe to Central Asia, but the meridional wind anomalies tend to be weak over East Asia. These circulation anomalies are responsible for the significant temperature anomalies over Europe–West Asia and Northeast Asia but weak anomalies between these two domains.展开更多
A 600-year pre-industrial simulation with Bergen Climate Model(BCM)Version 2 is used to investigate the linkage between winter Arctic Oscillation(AO)and the Southeast Asian summer monsoon(SEASM)on the inter-decadal ti...A 600-year pre-industrial simulation with Bergen Climate Model(BCM)Version 2 is used to investigate the linkage between winter Arctic Oscillation(AO)and the Southeast Asian summer monsoon(SEASM)on the inter-decadal timescale.The results indicate an in-phase relationship between the AO and SEASM with periods of approximately 16–32 and 60–80 years.During the positive phase of winter AO,an anomalous surface anti-cyclonic atmosphere circulation appears over North Pacific in winter.The corresponding anomalies in ocean circulation and surface heat flux,particularly the latent and sensible heat flux,resemble a negative Pacific Decadal Oscillation(PDO)-like sea surface temperature(SST)pattern.The AO-associated PDO-like winter SST can persist into summer and can therefore lead to inter-decadal variability of summer monsoon rainfall in East and Southeast Asia.展开更多
A simple approach that considers both internal decadal variability and the effect of anthropogenic forcing is developed to predict the decadal components of global sea surface temperatures (SSTs) for the three decades...A simple approach that considers both internal decadal variability and the effect of anthropogenic forcing is developed to predict the decadal components of global sea surface temperatures (SSTs) for the three decades 2011-2040. The internal decadal component is derived by harmonic wave expansion analyses based on the quasiperiodic evolution of the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO), as obtained from observational SST datasets. Furthermore, the external decadal component induced by anthropogenic forcing is assessed with a second-order fit based on the ensemble of projected SSTs in the experiments with multiple coupled climate models associated with the third Coupled Model Intercomparison Project (CMIP3) under the Intergovernmental Panels on Climate Change (IPCC) Special Reports on Emissions Scenario (SRES) A1B. A validation for the years from 2002 to 2010 based on a comparison of the predicted and the observed SST and their spatial correlation, as well as the root mean square error (RMSE), suggests that the approach is reasonable overall. In addition, the predicted results over the 50°S-50°N global band, the Indian Ocean, the western Pacific Ocean, the tropical eastern Pacific Ocean, and the North and the South Atlantic Ocean are presented.展开更多
The internal modes of the North Pacific can lead to climatic oscillations through ocean-atmosphere interactions and induce global climate responses.The best example is the Pacific Decadal Oscillation, but this fails t...The internal modes of the North Pacific can lead to climatic oscillations through ocean-atmosphere interactions and induce global climate responses.The best example is the Pacific Decadal Oscillation, but this fails to explain many climate phenomena. Here, another multidecadal variability over the North Pacific is described, found by analyzing reconstructed data covering the past 140 years. It is named the Pacific Multidecadal Oscillation （PMO）, with anomalously high/low SSTs over the northeastern Pacific, and a quasi-60-year cycle. Related to this low-frequency variability of SST, the global mean temperature and precipitation present significant interdecadal differences. More importantly, the PMO index leads the global mean surface air temperature and SST by one to three years. The Arctic Oscillation pattern and atmospheric circulations are shown to change substantially with the transition of the PMO mode from positive to negative phases. This multidecadal oscillation improves the prospect for a long-term forecast of the global warming trend, since the PMO bears a remarkable relationship with global temperature.展开更多
Cable-stayed bridges have been widely used in high-speed railway infrastructure.The accurate determination of cable’s representative temperatures is vital during the intricate processes of design,construction,and mai...Cable-stayed bridges have been widely used in high-speed railway infrastructure.The accurate determination of cable’s representative temperatures is vital during the intricate processes of design,construction,and maintenance of cable-stayed bridges.However,the representative temperatures of stayed cables are not specified in the existing design codes.To address this issue,this study investigates the distribution of the cable temperature and determinates its representative temperature.First,an experimental investigation,spanning over a period of one year,was carried out near the bridge site to obtain the temperature data.According to the statistical analysis of the measured data,it reveals that the temperature distribution is generally uniform along the cable cross-section without significant temperature gradient.Then,based on the limited data,the Monte Carlo,the gradient boosted regression trees(GBRT),and univariate linear regression(ULR)methods are employed to predict the cable’s representative temperature throughout the service life.These methods effectively overcome the limitations of insufficient monitoring data and accurately predict the representative temperature of the cables.However,each method has its own advantages and limitations in terms of applicability and accuracy.A comprehensive evaluation of the performance of these methods is conducted,and practical recommendations are provided for their application.The proposed methods and representative temperatures provide a good basis for the operation and maintenance of in-service long-span cable-stayed bridges.展开更多
A decadal change of the tropical tropospheric temperature （TT） was identified to occur in the winter of 1997. Compared with that in the former period （1979-1996）, the wintertime TT was significantly high over most...A decadal change of the tropical tropospheric temperature （TT） was identified to occur in the winter of 1997. Compared with that in the former period （1979-1996）, the wintertime TT was significantly high over most of the tropical regions except over the tropical eastern Pacific during the latter period （1997-2014） because the sea surface temperature （SST） exhibited a decadal La Nifia-like pattern after 1997. The warm SST anomalies over the tropical western Pacific facilitated enhanced precipitation and increased heat release to the tropical atmosphere, leading to a warmer tropical tropo- sphere in the latter period. In addition to the mean TT values, the interannual variability of the tropical TT changed in 1997. The leading mode of the tropical TT explained 72.9 % of the total variance in the former period. It led to significant warming over midlatitude North America via a Pacific-North America （PNA）-like wave train and off the coast of East Asia via an anomalous lower-tropospheric anticyclone around the Philippines. The mode remained a similar pattern but explained 85.4 % of the total variance in the latter period, and its location was slightly westward-shifted compared with that in the former period. As a result, the structure of the PNA-like wave train changed, leading to anomalous warming over northwestern North America and enhanced precipitation over the southern North America. Meanwhile, the anomalous lower- tropospheric anticyclone around the Philippines shifted westward, leading to increased precipitation and regional warming over East Asia. The decadal changes of the leading mode of the tropical TT and its influences on the extratropical climate can be attributed to the changes of the tropical SST variability.展开更多
基金supported jointly by the National Natural Science Foundation of China[Grant numbers 41705044 and 41405053]
文摘The Silk Road pattern（SRP）, which is a teleconnection pattern along the Asian upper-tropospheric westerly jet in summer, exhibits both interannual and decadal variabilities. Through the nineyear Gaussian filtering method and regression analyses, this study compares the interannual and decadal components of the SRP. The results indicate that the interannual SRP corresponds to a well-organized wave train of alternate cyclonic and anticyclonic anomalies across the Eurasian continent along the Asian westerly jet, resulting in a similar wave-like pattern of cold and warm surface temperature anomalies. This pattern of temperature anomalies differs from that associated with the original SRP, which is characterized by warmer or cooler temperatures mainly over Europe–West Asia and Northeast Asia, depending on the phase of the SRP. On the other hand, the decadal SRP shows a similar pattern to the interannual one from Europe to Central Asia, but the meridional wind anomalies tend to be weak over East Asia. These circulation anomalies are responsible for the significant temperature anomalies over Europe–West Asia and Northeast Asia but weak anomalies between these two domains.
基金supported by the National Basic Research Program of China(Grant No.2012CB955401)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA05110203)the Center for Climate Dynamics(Project:Integrated Model-data Approach for Understanding Multidecadal Natural Climate Variability)
文摘A 600-year pre-industrial simulation with Bergen Climate Model(BCM)Version 2 is used to investigate the linkage between winter Arctic Oscillation(AO)and the Southeast Asian summer monsoon(SEASM)on the inter-decadal timescale.The results indicate an in-phase relationship between the AO and SEASM with periods of approximately 16–32 and 60–80 years.During the positive phase of winter AO,an anomalous surface anti-cyclonic atmosphere circulation appears over North Pacific in winter.The corresponding anomalies in ocean circulation and surface heat flux,particularly the latent and sensible heat flux,resemble a negative Pacific Decadal Oscillation(PDO)-like sea surface temperature(SST)pattern.The AO-associated PDO-like winter SST can persist into summer and can therefore lead to inter-decadal variability of summer monsoon rainfall in East and Southeast Asia.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDA05090406 and XDA05110203)the special projects of the China Meteorological Administration(Grant No.GYHY201006022)contribution to the DecCen and Blue Arc projects funded by the Research Council of Norway and to the Centre for Climate Dynamics at the Bjerknes Centre
文摘A simple approach that considers both internal decadal variability and the effect of anthropogenic forcing is developed to predict the decadal components of global sea surface temperatures (SSTs) for the three decades 2011-2040. The internal decadal component is derived by harmonic wave expansion analyses based on the quasiperiodic evolution of the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO), as obtained from observational SST datasets. Furthermore, the external decadal component induced by anthropogenic forcing is assessed with a second-order fit based on the ensemble of projected SSTs in the experiments with multiple coupled climate models associated with the third Coupled Model Intercomparison Project (CMIP3) under the Intergovernmental Panels on Climate Change (IPCC) Special Reports on Emissions Scenario (SRES) A1B. A validation for the years from 2002 to 2010 based on a comparison of the predicted and the observed SST and their spatial correlation, as well as the root mean square error (RMSE), suggests that the approach is reasonable overall. In addition, the predicted results over the 50°S-50°N global band, the Indian Ocean, the western Pacific Ocean, the tropical eastern Pacific Ocean, and the North and the South Atlantic Ocean are presented.
基金supported by the National Natural Science Foundation of China[grant number 41421004],[grant number41130103]
文摘The internal modes of the North Pacific can lead to climatic oscillations through ocean-atmosphere interactions and induce global climate responses.The best example is the Pacific Decadal Oscillation, but this fails to explain many climate phenomena. Here, another multidecadal variability over the North Pacific is described, found by analyzing reconstructed data covering the past 140 years. It is named the Pacific Multidecadal Oscillation （PMO）, with anomalously high/low SSTs over the northeastern Pacific, and a quasi-60-year cycle. Related to this low-frequency variability of SST, the global mean temperature and precipitation present significant interdecadal differences. More importantly, the PMO index leads the global mean surface air temperature and SST by one to three years. The Arctic Oscillation pattern and atmospheric circulations are shown to change substantially with the transition of the PMO mode from positive to negative phases. This multidecadal oscillation improves the prospect for a long-term forecast of the global warming trend, since the PMO bears a remarkable relationship with global temperature.
基金Project(2017G006-N)supported by the Project of Science and Technology Research and Development Program of China Railway Corporation。
文摘Cable-stayed bridges have been widely used in high-speed railway infrastructure.The accurate determination of cable’s representative temperatures is vital during the intricate processes of design,construction,and maintenance of cable-stayed bridges.However,the representative temperatures of stayed cables are not specified in the existing design codes.To address this issue,this study investigates the distribution of the cable temperature and determinates its representative temperature.First,an experimental investigation,spanning over a period of one year,was carried out near the bridge site to obtain the temperature data.According to the statistical analysis of the measured data,it reveals that the temperature distribution is generally uniform along the cable cross-section without significant temperature gradient.Then,based on the limited data,the Monte Carlo,the gradient boosted regression trees(GBRT),and univariate linear regression(ULR)methods are employed to predict the cable’s representative temperature throughout the service life.These methods effectively overcome the limitations of insufficient monitoring data and accurately predict the representative temperature of the cables.However,each method has its own advantages and limitations in terms of applicability and accuracy.A comprehensive evaluation of the performance of these methods is conducted,and practical recommendations are provided for their application.The proposed methods and representative temperatures provide a good basis for the operation and maintenance of in-service long-span cable-stayed bridges.
基金supported by the National Natural Science Foundation of China(4142250141230527)the National Key Scientific Research Plan of China(2014CB953904)
文摘A decadal change of the tropical tropospheric temperature （TT） was identified to occur in the winter of 1997. Compared with that in the former period （1979-1996）, the wintertime TT was significantly high over most of the tropical regions except over the tropical eastern Pacific during the latter period （1997-2014） because the sea surface temperature （SST） exhibited a decadal La Nifia-like pattern after 1997. The warm SST anomalies over the tropical western Pacific facilitated enhanced precipitation and increased heat release to the tropical atmosphere, leading to a warmer tropical tropo- sphere in the latter period. In addition to the mean TT values, the interannual variability of the tropical TT changed in 1997. The leading mode of the tropical TT explained 72.9 % of the total variance in the former period. It led to significant warming over midlatitude North America via a Pacific-North America （PNA）-like wave train and off the coast of East Asia via an anomalous lower-tropospheric anticyclone around the Philippines. The mode remained a similar pattern but explained 85.4 % of the total variance in the latter period, and its location was slightly westward-shifted compared with that in the former period. As a result, the structure of the PNA-like wave train changed, leading to anomalous warming over northwestern North America and enhanced precipitation over the southern North America. Meanwhile, the anomalous lower- tropospheric anticyclone around the Philippines shifted westward, leading to increased precipitation and regional warming over East Asia. The decadal changes of the leading mode of the tropical TT and its influences on the extratropical climate can be attributed to the changes of the tropical SST variability.
