为了提高多元低密度奇偶校验（LDPC,low density parity-check）码符号翻转译码算法的性能并降低译码的复杂度,提出了基于平均概率和停止准则的多元LDPC码加权符号翻转译码（APSCWSF,average probability and stopping criterion weight...为了提高多元低密度奇偶校验（LDPC,low density parity-check）码符号翻转译码算法的性能并降低译码的复杂度,提出了基于平均概率和停止准则的多元LDPC码加权符号翻转译码（APSCWSF,average probability and stopping criterion weighted symbol flipping）算法。该算法将校验节点邻接符号节点的平均概率信息作为权重,使翻转函数更加有效,提高符号的翻转效率,进而改善译码性能。并且通过设置迭代停止准则进一步加快算法的收敛速度。仿真结果显示,在加性高斯白噪声信道下,误符号率为10-5时,相比WSF算法、NSCWSF算法（Osc=10）和NSCWSF算法（Osc=6）,APSCWSF算法（Osc=10）分别获得约0.68 d B、0.83 d B和0.96 d B的增益。同时,APSCWSF算法（Osc=6）的平均迭代次数也分别降低78.60%~79.32%、74.89%~75.95%和67.20%~70.80%。展开更多
The calculation of the meridional overturning streamfunction in the southern Indian Ocean is biased by the Indonesian Throughflow.Therefore,this study applies the vertical overturning streamfunction to diagnose the sh...The calculation of the meridional overturning streamfunction in the southern Indian Ocean is biased by the Indonesian Throughflow.Therefore,this study applies the vertical overturning streamfunction to diagnose the shallow overturning circulation in the Indian Ocean.Using the Ocean General Circulation Model for the Earth simulator output,improvements with the vertical overturning streamfunction compared with the meridional overturning streamfunction are explored.The results show that the vertical overturning streamfunction smoothly connects the shallow overturning circulations of the northern Indian Ocean and the southern Indian Ocean with the whole cycle of the subtropical cell and the cross-equatorial cell.The vertical overturning streamfunction shows a much cleaner shallow overturning circulation,which is underestimated by the meridional overturning streamfunction.It shows that the shallow overturning circulation has a magnitude of~13 Sv(1 Sv≡106 m 3 s−1),of which the subtropical cell accounts for~8 Sv.In addition,the vertical overturning streamfunction captures a clockwise overturning cell in the upper 600 m layer between 30°S and 34°S.This cell has a magnitude of about−5 Sv and probably corresponds to the wind-forced subtropical gyre.Therefore,the vertical overturning streamfunction provides a new approach for estimating the shallow overturning circulation in the Indian Ocean.展开更多
We analyzed the temporal and spatial variation, and interannual variability of the North Pacific meridional overturning circulation using an empirical orthogonal function method, and calculated mass transport using Si...We analyzed the temporal and spatial variation, and interannual variability of the North Pacific meridional overturning circulation using an empirical orthogonal function method, and calculated mass transport using Simple Ocean Data Assimilation Data from 1958-2008. The meridional streamfunction field in the North Pacific tilts N-S; the Tropical Cell （TC）, Subtropical Cell （STC）, and Deep Tropical Cell （DTC） may be in phase on an annual time scale; the TC and the STC are out of phase on an interannual time scale, but the interannual variability of the DTC is complex. The TC and STC interannual variability is associated with ENSO （El Nifio-Southem Oscillation）. The TC northward, southward, upward, and downward transports all weaken in E1 Nifios and strengthen in La Nifias. The STC northward and southward transports are out of phase, while the STC northward and downward transports are in phase. Sea-surface water that reaches the middle latitude and is subducted may not completely return to the vopics. The zonal wind anomalies over the central North Pacific, which control Ekman transport, and the east-west slope of the sea level may be major factors causing the TC northward and southward transport interannual variability and the STC northward and southward transports on the interannual time scale. The DTC northward and southward transports decrease during strong E1 Nifios and increase during strong La Nifias. DTC upward and downward transports are not strongly correlated with the Nifio-3 index and may not be completely controlled by ENSO.展开更多
文摘为了提高多元低密度奇偶校验（LDPC,low density parity-check）码符号翻转译码算法的性能并降低译码的复杂度,提出了基于平均概率和停止准则的多元LDPC码加权符号翻转译码（APSCWSF,average probability and stopping criterion weighted symbol flipping）算法。该算法将校验节点邻接符号节点的平均概率信息作为权重,使翻转函数更加有效,提高符号的翻转效率,进而改善译码性能。并且通过设置迭代停止准则进一步加快算法的收敛速度。仿真结果显示,在加性高斯白噪声信道下,误符号率为10-5时,相比WSF算法、NSCWSF算法（Osc=10）和NSCWSF算法（Osc=6）,APSCWSF算法（Osc=10）分别获得约0.68 d B、0.83 d B和0.96 d B的增益。同时,APSCWSF算法（Osc=6）的平均迭代次数也分别降低78.60%~79.32%、74.89%~75.95%和67.20%~70.80%。
基金supported by the National Key Research and Development Program of China[grant number 2016YFC1401803]the National Natural Science Foundation of China[grant numbers 41976019 and 42076020]+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences[grant number XDA20060502]the open project of the State Key Laboratory of Tropical Oceanography,South China Sea Institute of Oceanology,Chinese Academy of Sciences[grant number LTO1910]the Research Program of the Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)[grant number GML2019ZD0306]the Key Research Program of the Chinese Academy of Sciences[grant number ZDRW-XH-2019-2]。
文摘The calculation of the meridional overturning streamfunction in the southern Indian Ocean is biased by the Indonesian Throughflow.Therefore,this study applies the vertical overturning streamfunction to diagnose the shallow overturning circulation in the Indian Ocean.Using the Ocean General Circulation Model for the Earth simulator output,improvements with the vertical overturning streamfunction compared with the meridional overturning streamfunction are explored.The results show that the vertical overturning streamfunction smoothly connects the shallow overturning circulations of the northern Indian Ocean and the southern Indian Ocean with the whole cycle of the subtropical cell and the cross-equatorial cell.The vertical overturning streamfunction shows a much cleaner shallow overturning circulation,which is underestimated by the meridional overturning streamfunction.It shows that the shallow overturning circulation has a magnitude of~13 Sv(1 Sv≡106 m 3 s−1),of which the subtropical cell accounts for~8 Sv.In addition,the vertical overturning streamfunction captures a clockwise overturning cell in the upper 600 m layer between 30°S and 34°S.This cell has a magnitude of about−5 Sv and probably corresponds to the wind-forced subtropical gyre.Therefore,the vertical overturning streamfunction provides a new approach for estimating the shallow overturning circulation in the Indian Ocean.
基金Supported by the National Basic Research Program of China(973 Program)(Nos.2012CB417402,2007CB816002)
文摘We analyzed the temporal and spatial variation, and interannual variability of the North Pacific meridional overturning circulation using an empirical orthogonal function method, and calculated mass transport using Simple Ocean Data Assimilation Data from 1958-2008. The meridional streamfunction field in the North Pacific tilts N-S; the Tropical Cell （TC）, Subtropical Cell （STC）, and Deep Tropical Cell （DTC） may be in phase on an annual time scale; the TC and the STC are out of phase on an interannual time scale, but the interannual variability of the DTC is complex. The TC and STC interannual variability is associated with ENSO （El Nifio-Southem Oscillation）. The TC northward, southward, upward, and downward transports all weaken in E1 Nifios and strengthen in La Nifias. The STC northward and southward transports are out of phase, while the STC northward and downward transports are in phase. Sea-surface water that reaches the middle latitude and is subducted may not completely return to the vopics. The zonal wind anomalies over the central North Pacific, which control Ekman transport, and the east-west slope of the sea level may be major factors causing the TC northward and southward transport interannual variability and the STC northward and southward transports on the interannual time scale. The DTC northward and southward transports decrease during strong E1 Nifios and increase during strong La Nifias. DTC upward and downward transports are not strongly correlated with the Nifio-3 index and may not be completely controlled by ENSO.
