In this paper,an antenna array composed of circular array and orthogonal linear array is proposed by using the design of long and short baseline“orthogonal linear array”and the circular array ambiguity resolution de...In this paper,an antenna array composed of circular array and orthogonal linear array is proposed by using the design of long and short baseline“orthogonal linear array”and the circular array ambiguity resolution design of multi-group baseline clustering.The effectiveness of the antenna array in this paper is verified by sufficient simulation and experiment.After the system deviation correction work,it is found that in the L/S/C/X frequency bands,the ambiguity resolution probability is high,and the phase difference system error between each channel is basically the same.The angle measurement error is less than 0.5°,and the positioning error is less than 2.5 km.Notably,as the center frequency increases,calibration consistency improves,and the calibration frequency points become applicable over a wider frequency range.At a center frequency of 11.5 GHz,the calibration frequency point bandwidth extends to 1200 MHz.This combined antenna array deployment holds significant promise for a wide range of applications in contemporary wireless communication systems.展开更多
The standard deviation of the central Pacific sea surface temperature anomaly （SSTA） during the period from October to February shows that the central Pacific SSTA variation is primarily due to the occurrence of the...The standard deviation of the central Pacific sea surface temperature anomaly （SSTA） during the period from October to February shows that the central Pacific SSTA variation is primarily due to the occurrence of the Central Pacific E1 Nifio （CP-E1 Nifio） and has a connection with the subtropical air-sea interaction in the northeastern Pacific. After removing the influence of the Eastern Pacific E1 Nifio, an S-EOF analysis is conducted and the leading mode shows a clear seasonal SSTA evolving from the subtropical northeastern Pacific to the tropical central Pacific with a quasi-biennial period. The initial subtropical SSTA is generated by the wind speed decrease and surface heat flux increase due to a north Pacific anomalous cyclone. Such subtropical SSTA can further influence the establishment of the SSTA in the tropical central Pacific via the wind-evaporation-SST （WES） feedback. After established, the central equatorial Pacific SSTA can be strengthened by the zonal advective feedback and thermocline feedback, and develop into CP-E1 Nifio. However, as the thermocline feedback increases the SSTA cooling after the mature phase, the heat flux loss and the reversed zonal advective feedback can cause the phase transition of CP-EI Nifio. Along with the wind stress variability, the recharge （discharge） process occurs in the central （eastern） equatorial Pacific and such a process causes the phase consistency between the thermocline depth and SST anomalies, which presents a contrast to the original recharge/discharge theory.展开更多
Earth’s free oscillation can provide essential constraints for refining Earth models,inverting seismic source mechanisms,and studying the deep internal structure of the Earth.Large earthquakes can simultaneously exci...Earth’s free oscillation can provide essential constraints for refining Earth models,inverting seismic source mechanisms,and studying the deep internal structure of the Earth.Large earthquakes can simultaneously excite numerous normal modes.Due to the Earth’s ellipticity,rotation,and internal heterogeneities,these normal modes undergo splitting,with the frequencies of singlets of normal modes becoming very close(only a fewµHz apart).This imposes greater demands on the detection of normal modes.This paper introduces a novel method for normal mode detection based on the normal time-frequency transform(NTFT).Compared to classical FT spectrum methods and recent optimal sequence estimation(OSE),the proposed method not only detects more weak normal modes but also reveals the spatial distribution of the phase of each normal mode.Taking the detection of 0S2 as an example,the phase measurements of each singlet are spatially inconsistent.This phenomenon can provide prior information for other methods,such as product spectrum analysis(PSA),spherical harmonic stacking(SHS),multistation experiments(MSE),and OSE.Additionally,understanding the phase distribution patterns contributes to further study of geological structures,offering crucial foundational data and observational support.展开更多
文摘In this paper,an antenna array composed of circular array and orthogonal linear array is proposed by using the design of long and short baseline“orthogonal linear array”and the circular array ambiguity resolution design of multi-group baseline clustering.The effectiveness of the antenna array in this paper is verified by sufficient simulation and experiment.After the system deviation correction work,it is found that in the L/S/C/X frequency bands,the ambiguity resolution probability is high,and the phase difference system error between each channel is basically the same.The angle measurement error is less than 0.5°,and the positioning error is less than 2.5 km.Notably,as the center frequency increases,calibration consistency improves,and the calibration frequency points become applicable over a wider frequency range.At a center frequency of 11.5 GHz,the calibration frequency point bandwidth extends to 1200 MHz.This combined antenna array deployment holds significant promise for a wide range of applications in contemporary wireless communication systems.
基金supported by the National Basic Research Program of China(973Program:2012CB955604)National Natural Science Foundation of China(Nos.40975038and40830106)+5 种基金the CMA Program(GYHY200906008)the financial support provided by the China Scholarship Counciljointly supported by the 973 Program of China(2010CB950404)DOE grant DE-SC0005110National Science Foundation(NSF)grants ATM1034798NOAA grand NA10OAR4310200
文摘The standard deviation of the central Pacific sea surface temperature anomaly （SSTA） during the period from October to February shows that the central Pacific SSTA variation is primarily due to the occurrence of the Central Pacific E1 Nifio （CP-E1 Nifio） and has a connection with the subtropical air-sea interaction in the northeastern Pacific. After removing the influence of the Eastern Pacific E1 Nifio, an S-EOF analysis is conducted and the leading mode shows a clear seasonal SSTA evolving from the subtropical northeastern Pacific to the tropical central Pacific with a quasi-biennial period. The initial subtropical SSTA is generated by the wind speed decrease and surface heat flux increase due to a north Pacific anomalous cyclone. Such subtropical SSTA can further influence the establishment of the SSTA in the tropical central Pacific via the wind-evaporation-SST （WES） feedback. After established, the central equatorial Pacific SSTA can be strengthened by the zonal advective feedback and thermocline feedback, and develop into CP-E1 Nifio. However, as the thermocline feedback increases the SSTA cooling after the mature phase, the heat flux loss and the reversed zonal advective feedback can cause the phase transition of CP-EI Nifio. Along with the wind stress variability, the recharge （discharge） process occurs in the central （eastern） equatorial Pacific and such a process causes the phase consistency between the thermocline depth and SST anomalies, which presents a contrast to the original recharge/discharge theory.
基金supported by Natural Science Foundation of China(No.41704003)Shandong Provincial Natural Science Foundation(No.ZR2021MD031).
文摘Earth’s free oscillation can provide essential constraints for refining Earth models,inverting seismic source mechanisms,and studying the deep internal structure of the Earth.Large earthquakes can simultaneously excite numerous normal modes.Due to the Earth’s ellipticity,rotation,and internal heterogeneities,these normal modes undergo splitting,with the frequencies of singlets of normal modes becoming very close(only a fewµHz apart).This imposes greater demands on the detection of normal modes.This paper introduces a novel method for normal mode detection based on the normal time-frequency transform(NTFT).Compared to classical FT spectrum methods and recent optimal sequence estimation(OSE),the proposed method not only detects more weak normal modes but also reveals the spatial distribution of the phase of each normal mode.Taking the detection of 0S2 as an example,the phase measurements of each singlet are spatially inconsistent.This phenomenon can provide prior information for other methods,such as product spectrum analysis(PSA),spherical harmonic stacking(SHS),multistation experiments(MSE),and OSE.Additionally,understanding the phase distribution patterns contributes to further study of geological structures,offering crucial foundational data and observational support.
