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Improving the understanding of the influencing factors on sea level based on wavelet coherence and partial wavelet coherence

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海洋湖沼学报(英文) 2023年第5期41卷 1643-1659页

作者： Chao SONG Xiaohong CHEN Wenjun XIA School of Civil Engineering Sun Yat-sen UniversityGuangzhou 510275China Guangdong Engineering Technology Research Center of Water Security Regulation and Control for Southern China Sun Yat sen UniversityGuangzhou 510275China Key Laboratory of Water Cycle and Water Security in Southern China of Guangdong High Education Institute Sun Yat-sen UniversityGuangzhou 510275China

Relationship between sea level change and a single climate indicator has been widely discussed.However,few studies focused on the relationship between monthly mean sea level(MMSL)and several key impact factors,including CO_(2) concentration,sea ice area,and sunspots,on various time scales.In addition,research on the independent relationship between climate factors and sea level on various time scales is lacking,especially when the dependence of climate factors on Nino 3.4 is excluded.Based on this,we use wavelet coherence(WC)and partial wavelet coherence(PWC)to establish a relationship between MMSL and its influencing factors.The WC results show that the influence of climate indices on MMSL has strong regional characteristics.The significant correlation between Southern Hemisphere sea ice area and MMSL is opposite to that between Northern Hemisphere sea ice area and MMSL.The PWC results show that after removing the influence of Nino 3.4,the significant coherent regions of the Pacific Decadal Oscillation(PDO),Dipole Mode Index(DMI),Atlantic Multidecadal Oscillation(AMO),and Southern Oscillation Index(SOI)decrease to varying degrees on different time scales in different regions,demonstrating the influence of Nino 3.4.Our work emphasizes the interrelationship and independent relationship between MMSL and its influencing factors on various time scales and the use of PWC and WC to describe this relationship.The study has an important reference significance for selecting the best predictors of sea level change or climate systems.

关键词： wavelet coherence partial wavelet coherence monthly mean sea level influencing factors time scale significant correlation

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Co‑movement of commodity price indexes and energy price index:a wavelet coherence approach

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Financial Innovation 2021年第1期7卷 323-340页

作者： Dervis Kirikkaleli Hasan Gügö Department of Banking and Finance Faculty of Economic and Administrative SciencesEuropean University of LefkeLefkeNorthern CyprusTR‑10MersinTurkey Department of Economics Eastern Mediterranean UniversityFamagustaNorth CyprusTurkey

This research sheds light on the causal link between commodity price indexes,i.e.,the Agricultural Raw Materials Price Index,Industry Input Price Index,Metal Price Index,and Energy Price Index,in the global market,using wavelet coherence,Toda–Yamamoto causality,and gradual shift causality tests over the period 1992M1 to 2019M12.Findings from the wavelet power spectrum and partial wavelet coherence reveal that:(1)there was significant volatility in the Agricultural Raw Materials Price Index,Industry Input Price Index,Metal Price Index,and Energy Price Index between 2004 and 2014 at different frequencies;and(2)commodity price indexes significantly caused the energy price index at different time periods and frequencies.It is noteworthy that the outcomes of the Toda–Yamamoto causality and gradual-shift causality tests are in line with the results of wavelet coherence.

关键词： Energy price Commodity price wavelet coherence Causality

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Co-movement and Forecasting Analysis of Major Real Estate Markets by wavelet coherence and Multiple wavelet coherence

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Chinese Journal of Urban and Environmental Studies 2017年第2期05卷 37-54页

作者： Cengiz KARATAS Gazanfer UNAL Adil YILMAZ Financial Economics Graduate Program Yeditepe University

wavelet coherence of time series provides valuable information about dynamic correlation and its impact on time scales. Here, the authors analyze the wavelet coherence of major real estate markets data, and take the USA, Hong Kong of China, Canada, Japan, and Developed Europe real estate market prices as time series. The wavelet coherence results show relationships among these markets, the correlations between the two and three markets(by multiple wavelet coherence) and how these relationships vary in the time-frequency space. These relationships allow the authors to build VARMA models of real estate data which produce forecasts with small errors.

关键词： Real estate markets REIT co-movement wavelet coherence MWC VARMA

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Development of a validation technique for road surface profile applicable to point cloud data

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Journal of Road Engineering 2022年第2期2卷 114-123页

作者： Kazuya Tomiyama Yuki Yamaguchi Kazushi Moriishi Yuki Kotani Division of Civil and Environmental Engineering Kitami Institute of TechnologyKitami 090-8507Japan Obayashi Road Corporation Tokyo 101-8228Japan Graduate School of Engineering Kitami Institute of TechnologyKitami 090-8507Japan

In recent years,various information and communication technology(ICT)devices measuring three-dimensional(3D)point cloud data have been developed and widely used for the application of pavement surface investigation.However,ICT devices have generally been developed not only for measuring road surface profiles but for various geo-reference point clouds.In this background,the validation of surface profiles acquired with ICT devices fulfils an important role in proving the reliability of measurement result composed by point clouds.This study proposes a wavelet transform agreement(WTA)which involves a normalization factor of profile amplitude for further improvement in the wavelet-based coherence technique.The WTA analysis allows evaluating similarity/dissimilarity of two profiles considering both the location and wavelength simultaneously.For this purpose,a terrestrial laser scanner(TLS),a mobile mapping system(MMS),and an unmanned aerial vehicle(UAV)are employed to prove the advantage of WTA in practical applications.As a result,the advantages of WTA analysis are clearly recognized in the optimization for the measurement interval of TLS,the multi-line measurement of MMS for ride quality improvement of a pavement,and the efficient operation of UAV in terms of the flight altitude.This paper also shows the identification of aging development for surface roughness over time in terms of locations and wavelengths.These findings help not only to guarantee the accuracy of profile measurements but to realize the sophisticated way of using 3D point clouds acquired with ICT devices.The outcomes of this study contribute to the increase of productivity for pavement works with improving the quality of surface profile measurement.

关键词： Surface profile Profile validation Point cloud wavelet agreement wavelet coherence

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The influence of human activity and precipitation change on mid-long term evolution of landslide and debris flow disasters

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Research in Cold and Arid Regions 2013年第6期5卷 715-721页

作者： Yun Tao Chuan Tang Meteorological Institute of Yunnan Province National Professional Laboratory for Geo-hazard Prevention Chengdu University of Technology

After defining landslide and debris flow, human activity, and precipitation indices, using with landslide and debris flow disaster data in low-latitude plateau of China, reflecting human activity and precipitation data, the influence of human activity and precipitation on mid-long term evolution of landslide and debris flow was studied with the wavelet technique. Results indicate that mid-long evolution of landslide and debris flow disaster trends to increase 0.9 unit every year, and presents obvious stage feature. The abrupt point from rare to frequent periods took place in 1993. There is significant in-phase resonance oscillation between human activity and landslide and debris flow frequency on a scale of 11-16 years, in which the variation of human activity occurs about 0.2-2.8 years before landslide and debris flow variation. Thus, the increase of landslide and debris flow frequency in low latitude plateau of China may be mainly caused by geo-environmental degradation induced by human activity. After the impact of human activity is removed, there is sig- nificant in-phase resonance oscillation between landslide and debris flow frequency and summer rainfall in low-latitude plateau of China in quasi-three-year and quasi-six-year scales, in which the variation of summer precipitation occurs about 0.0-0.8 years before landslide and debris flow variation. Summer precipitation is one of important external causes which impacts landslide and debris flow frequency in low-latitude plateau of China. The mid-long term evolution predicting model of landslide and debris flow disasters frequency in low-latitude plateau region with better fitting and predicting ability was built by considering human activity and summer rainfall.

关键词： landslide and debris flow wavelet coherence human activity summer precipitation low-latitude plateau of China

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The meaning of “coherent” and its quantication in coherent hemodynamics spectroscopy

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Journal of Innovative Optical Health Sciences 2018年第6期 55-77页

作者： Angelo Sassaroli Kristen Tgavalekos Sergio Fantini Department of Biomedical Engineering Tufts University MedfordMA 02155USA

We have recently introduced a new technique,coherent hemodynamics spectroscopy(CHS),which aims at characterizing a specic kind of tissue hemodynamics that feature a high level of covariation with a given physiological quantity.In this study,we carry out a detailed analysis of the signicance of coherence and phase synchronization between oscillations of arterial blood pressure(ABP)and total hemoglobin concentration([Hbt]),measured with near-infrared spectroscopy(NIRS)during a typical protocol for CHS,based on a cyclic thigh cuffocclusion and release.Even though CHS is based on a linear time invariant model between ABP(input)and NIRS measurands(outputs),for practical reasons in a typical CHS protocol,we inducenite“groups”of ABP oscillations,in which each group is characterized by a different frequency.For this reason,ABP(input)and NIRS measurands(output)are not stationary processes,and we have used wavelet coherence and phase synchronization index(PSI),as a metric of coherence and phase synchronization,respectively.PSI was calculated by using both the wavelet cross spectrum and the Hilbert transform.We have also used linear coherence(which requires stationary process)for comparison with wavelet coherence.Themethod of surrogate data is used tond critical values for the signicance of covariation between ABP and[Hbt].Because we have found similar critical values for wavelet coherence and PSI by usingve of the most used methods of surrogate data,we propose to use the data-independent Gaussian random numbers(GRNs),for CHS.By using wavelet coherence and wavelet cross spectrum,and GRNs as surrogate data,we have found the same results for the signicance of coherence and phase synchronization between ABP and[Hbt]:on a total set of 20 periods of cuffoscillations,we have found 17 coherent oscillations and 17 phase synchronous oscillations.Phase synchronization assessed with Hilbert transform yielded similar results with 14 phase synchronous oscillations.Linear coherence and wavelet coherence overall yielded similar number of

关键词： wavelet coherence phase synchronization near-infrared spectroscopy surrogate data

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The response of river discharge to climate fluctuations in the source region of the Yellow River

The response of river discharge to climate fluctuations in t...

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中国科学院地质与地球物理研究所2012年度（第12届）...

作者： Jianfeng Zhang Guomin Li S.Liang Division of Engineering Geology and Water Resources Institute of Geology and GeophysicsChinese Academy of Sciences Graduate University of Chinese Academy of Science School of Water Resources and Environment China University of Geosciences

The Yellow River is the second biggest river in China and serves as a source of domestic and agricultural water supply in the watershed.In the last several decades, this river’s discharge reduced to zero several times since 1960,especially in the 1990s.The decreasing river flow has caused some serious eco-environmental problems in the source region.To study the important effects of climate on river discharge in the source area,a data set of 44 wateryear river flow,air temperature and precipitation is selected and wavelet analysis is performed to describe and identify the features of climate(air temperature and precipitation) and river discharge.Results of continuous wavelet transform (CWT) show that all three parameters have common significant periods of 1-2 and 3-6 years against red noise in different time spans while river discharge probably has a 16-year-period mainly in the cone of influence(COI). Comparison of river flow and its CWT suggests these zero river flows are connected to extreme low values located in different scales,indicating that climate does control the river discharge in the source area.The cross wavelet (XWT) and wavelet coherence(WTC) clearly illustrate that the first zero river discharge(about in 1961) is only related to precipitation,while the rest have resulted from the combination of air temperature and precipitation.

关键词： The Yellow River Zero discharge Cross wavelet wavelet coherence

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