The sea-level anomaly (SLA) from a satellite altimeter has a high accuracy and can be used to improve ocean state estimation by assimilation techniques. However, the lack of an accurate mean dynamic topography (MDT...The sea-level anomaly (SLA) from a satellite altimeter has a high accuracy and can be used to improve ocean state estimation by assimilation techniques. However, the lack of an accurate mean dynamic topography (MDT) is still a bothersome issue in an ocean data assimilation. The previous studies showed that the errors in MDT have significant impacts on assimilation results, especially on the time-mean components of ocean states and on the time variant parts of states via nonlinear ocean dynamics. The temporal-spatial differences of three MDTs and their impacts on the SLA analysis are focused on in the South China Sea (SCS). The theoretical analysis shows that even for linear models, the errors in MDT have impacts on the SLA analysis using a sequential data assimilation scheme. Assimilation experiments, based on EnOI scheme and HYCOM, with three MDTs from July 2003 to June 2004 also show that the SLA assimilation is very sensitive to the choice of different MDTs in the SCS with obvious differences between the experimental results and observations in the centre of the SCS and in the vicinity of the Philippine Islands. A new MDT for assimilation of SLA data in the SCS was proposed. The results from the assimilation experiment with this new MDT show a marked reduction (increase) in the RMSEs (correlation coefficient) between the experimental and observed SLA. Furthermore, the subsurface temperature field is also improved with this new MDT in the SCS.展开更多
Collinear analysis technique is widely used for determining sea surface variability with Geosat altimeterdata from its Exact Repeat Mission(ERM).But most of the researches have been only on global scaleor in oceans de...Collinear analysis technique is widely used for determining sea surface variability with Geosat altimeterdata from its Exact Repeat Mission(ERM).But most of the researches have been only on global scaleor in oceans deeper than 2000 m.In shallow shelf waters this method is hampered by the inaccuracy ofocean tide data supplied with Geosat Geophysical Data Records(GDRs).This work uses a modified collinearanalysis technique characterized by simultaneous separation of mean sea level and ocean tide with theleast squares method,to compute sea surface variability in the Northwest Pacific Ocean and eastern ChinaSeas.The mean sea level map obtained contains not ouly bathymetric but also dynamic features such asamphidromes,indicating considerable improvement over previous works.Our sea surface variability mapsshow clearly the main current system,the well-known Zhejiang coastal upwelling,and a northern East Chi-na Sea meso-scale eddy in good agreement with satellite sea surface temperature(SST)observation and展开更多
Background: Self-efficacy has been identified as an important determinant of youth's behavior change including physical activity(PA) participation. However, the dimensionality check of a PA self-efficacy scale has...Background: Self-efficacy has been identified as an important determinant of youth's behavior change including physical activity(PA) participation. However, the dimensionality check of a PA self-efficacy scale has rarely been conducted in China. The current study aims to examine(1) the unidimensionality of a shortened Chinese version of PA self-efficacy scale(S-PASESC);(2) the measurement invariance of S-PASESC across gender and levels of education;(3) the latent factor mean difference between gender and levels of education;(4) the direct effects of self-efficacy on PA by different gender and education levels; and(5) the comparisons of the direct effects of self-efficacy on PA across gender and education levels.Methods: The participants were 5 th through 11 th grade public school students recruited from 7 cities located in different geographic regions of China. The final data include a total of 3003 participants(49.7% boys) who have completed the scales.Results: Confirmatory factor analysis(CFA) test supported the unidimensionality of S-PASESC. The S-PASESC is invariant across gender and 3 levels of education at both configural, full metric, and full scalar levels. Findings from latent mean comparisons showed that boys reported higher PA self-efficacy than girls. Students' perceived PA self-efficacy tend to decrease from elementary to high school. Finally, self-efficacy positively related to PA by groups of different gender and education levels and the relationship between self-efficacy and PA is stronger among middle school boys than girls.Conclusion: Findings suggest S-PASESC is a valid scale for measuring Chinese students' PA self-efficacy.展开更多
Short time existence and uniqueness for the classical motion are studied by the function of the principal curvatures of a smooth surface and the Evans and Spruck's results are generalized.
To study the period components in the monthly mean sea level variations in the Pacific Ocean, this paper analyses the monthly mean series of 236 tide gauge stations in the Pacific on the basis of the improved analytic...To study the period components in the monthly mean sea level variations in the Pacific Ocean, this paper analyses the monthly mean series of 236 tide gauge stations in the Pacific on the basis of the improved analytical method of the monthly mean sea level period signals. The results show that the oscillation periods of the sea level series are not fixed, but vary with stations. This paper also discusses the existences of the quasi-2 years atmospheric oscillation period, the 3~7 a period related to the El Nino events, sunspots, double sunspots and the 25~30 a overlength oscillation periods. The corresponding amplitudes and initial phase angles as well as the linear trend coefficient are obtained by using significant period components plus the linear trend to fit the monthly mean sea level series. A conspicuous features of the results are found,i. e.,taking 25°~30°S as the axial line in the Pacific, the annual lags gradually increase to the north and the south respectively, depicting a variation trend of partial symmetry. But in China seas, the north and south distributional trend of the annual period lags is almost opposite to those in most parts of the Pacific Ocean. In the low-latitude zone where El Nino events occur or impose more significant effects, the ratio of the sum of amplitudes of various periods within 2~7 a to the annual amplitude is equal to or more than 1. 0, while that of the sum of amplitudes of periods larger than 8 a to the annual amplitude is equal to or more than 0. 5. This suggests that the dominant role of annual amplitude in the monthly mean sea level series of this region has declined and that, correspondingly, there exist significant period components of El Nino events as well as the long-period oscillations of quasi-10 a and over 10 a. In the high-latitude zone, off China, in North America north of 40°N and the coast of Japan, the annual period oscillation occupies a dominant position in the various period components.展开更多
This paper summarizes the general methods,existing problems and their causes of the period analysis for the monthly mean sea level and points out that it is the key to the analysing period signals and forecasting the ...This paper summarizes the general methods,existing problems and their causes of the period analysis for the monthly mean sea level and points out that it is the key to the analysing period signals and forecasting the change trend of the monthly mean sea level that the periods of the signals are selected reasonably. As there are often many period signals in these series, nonlinear effects exist between pairs of period signals. In order to avoid the false periods that may be introduced due to the effects of side lobes and the periods with statistical phase significance coherence that may be introduced due to the effects of nonlinear effects and their restraint to other period signals, the maximum entropy spectral analysis and the corresponding significance period test may be performed repeatedly on the basis of the bispectrum analysis and meanwhile the most significant period component is filtered out by the least square filtering method, i. e., the method of the significance period analysis with mixed spectra modeled by a nonlinear system is adopted and the signal periods approaching the reality are selected one by one. The examples of the bispectrum analysis, the signal period analysis by mixed spectra and the fitting parameters for combined period components with linear trend in the time series of monthly mean sea level are given in this paper.展开更多
Monthly changes of sea level recorded on the seas adjacent to Korea (the Huanghai Sea, the East ChinaSea and the East As) are investigated. The major influences on the spatial and temporal variation of mean sea level ...Monthly changes of sea level recorded on the seas adjacent to Korea (the Huanghai Sea, the East ChinaSea and the East As) are investigated. The major influences on the spatial and temporal variation of mean sea level arequantitatively identified. A set of modes of monthly air pressure variation over the Huanghai Sea, East China Sea andEast Sea for the period of 1978-1992 is obtained. Each monthly air pressure distribution can be precisely defined bylinear combination of these modes. Hence, the set of air pressure series can be replaced by a set of time varying coefficents, where each coefficient describes the contribution of a particular mode to a given air pressure distribution. A selected set of the modal coefficients is then added to a multiple Fegresion model, consisting of a trend, monthly wind stress and tidal term, in an attempt to represent the effect of meteorological variations on monthly mean sea level on the seas adjacent to Korea. It is found that although the model may account for over 90% of the observed mean sea level variance, there still remains a high correlation between the residuals, hence identifying a regional variation for further study.展开更多
Global mean sea level budget is rigorously adjusted during the period 2005-2015.The emphasis is to provide the best estimates for the linear rates of changes(trends)of the global mean sea level budget components durin...Global mean sea level budget is rigorously adjusted during the period 2005-2015.The emphasis is to provide the best estimates for the linear rates of changes(trends)of the global mean sea level budget components during this period subject to the constraint:Earth’s hydrosphere conserves water.The newly simultaneously adjusted trends of the budget components suggest a larger correction for the global mean sea level trend implicated by the other budget components’trends under the budget constraint.The simultaneous estimation of the linear trends of the budget components subject to the constraint for closure improves their uncertainties and enables a holistic assessment of the global mean sea budget,which has implications for future sea level science studies,including the future Intergovernmental Panel on Climate Change(IPCC)Assessment Reports,and the US Climate Assessment Reports.展开更多
-In this paper, the maximum entropy spectral, the cross-spectral and the frequency response analyses are madeon the basis of the data of monthly mean sea levels at coastal stations in the Bohai Sea during 1965-1986. T...-In this paper, the maximum entropy spectral, the cross-spectral and the frequency response analyses are madeon the basis of the data of monthly mean sea levels at coastal stations in the Bohai Sea during 1965-1986. The results show that the annual fluctuations of the monthly mean sea levels in the Bohai Sea are the results of the coupling response of seasonal variations of the marine hydrometeorological factors. Furthermore, the regression prediction equation is obtained by using the double screening stepwise regression analysis method . Through the prediction test , it is proved that the obtained results are desirable.展开更多
Tidal data from Weizhou, Zhapo, and Shanwei stations between 1969 and 2010 and from five gauging stations in the western Pacific Ocean provided by PSMSL, and the global mean sea level data recorded between December 19...Tidal data from Weizhou, Zhapo, and Shanwei stations between 1969 and 2010 and from five gauging stations in the western Pacific Ocean provided by PSMSL, and the global mean sea level data recorded between December 1992 and December 2010 by TOPEX and Jason satellites were compiled and analyzed. The results show that the perennial mean sea level near Weizhou Island is 211.7 cm(relative to the water gauge zero), and the relative mean sea level rising rate is 2.2 mm yr-1 from 1969 to 2010, which is consistent with the relative mean sea level rising rate recorded at other gauging stations in the western Pacific regions and with the global mean sea level rising rate. The absolute mean sea level rising rate at Weizhou Island is 3.0 mm yr-1 from 1993 to 2010, also conforming with the global mean sea level rising rate(3.1±0.4 mm yr-1) during the same time period. The highest annual tide level at Weizhou Island has a rising rate of 4.6 mm yr-1 and shows a 20-year quasi-periodic variation from 1966 to 2010. The primary cause of the mean sea level rising is global warming.展开更多
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,includi...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.展开更多
The latest Intergovernmental Panel on Climate Change (IPCC) report shows that sea-level rise, which has been accelerated since the 19th century resulting to the global warming, threatens coastal areas with high popula...The latest Intergovernmental Panel on Climate Change (IPCC) report shows that sea-level rise, which has been accelerated since the 19th century resulting to the global warming, threatens coastal areas with high population growth. A Global Sea Level Observing System (GLOSS) assessment highlighted the lack of data in Africa, and in Côte d’Ivoire in particular. In order to estimate the evolutionary trend of sea level along the Ivorian coast, and to draw up preventive plans to protect properties and populations, we digitized 65 years of historical tidegrams recorded in the Ebrie Lagoon, using the “Surfer” and “Nunieau” software, then processed them using “T-Tide” and “U-Tide” software. The average levels were calculated using the Demerliac filter from complete daily (day and night) recordings for providing a usable database of 31 years of hourly lagoon data from 1979 to 2015. Our results show that a mean water level in lagoon is 1.04 m. The evolutionary trend in sea level, estimated in the lagoon via the Vridi canal, during the rainy season is the most significant at 2.93 mm/year. This is followed by the dry season, with a trend of 2.89 mm/year. The flood season trend is 2.78 mm/year. This suggests that marine water inflows dominate continental inflows. Our results highlight the vulnerability of Côte d’Ivoire’s coasts to the risk of marine submersion.展开更多
Mean Shift跟踪算法在目标尺度变化大和被遮挡时存在较大的缺陷。针对这一问题,提出了一种基于多级正方形匹配的自适应带宽选择和分块抗遮挡的目标跟踪算法。该算法采用目标中心点的离散程度和增量试探法计算出可能的变化尺度,然后采用...Mean Shift跟踪算法在目标尺度变化大和被遮挡时存在较大的缺陷。针对这一问题,提出了一种基于多级正方形匹配的自适应带宽选择和分块抗遮挡的目标跟踪算法。该算法采用目标中心点的离散程度和增量试探法计算出可能的变化尺度,然后采用多级正方形匹配法预测目标的运动趋势,将巴氏系数最大者的尺度作为Mean Shift核函数新的带宽。同时,对前景目标进行分块,根据子块的遮挡程度自适应改变子块权重并按一定准则融合有效子块的跟踪结果。实验结果表明,该算法具有很好的鲁棒性。展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences [grant number XDA20060500]the National Natural Science Foundation of China[grant numbers 41731173 and 42275035]+8 种基金the Natural Science Foundation of Guangdong ProvinceChina [grant number 2022A1515011967]the Science and Technology Program of GuangzhouChina [grant number 202002030492]the Open Fund Project of the Key Laboratory of Marine Environmental Information Technology,the Key Laboratory of Marine Science and Numerical Modeling,Ministry of Natural Resources of the People’s Republic of China [grant number 2020-YB-05]the MEL Visiting Fellowship [grant number MELRS2102]the Independent Research Project Program of the State Key Laboratory of Tropical Oceanography [grant number LTOZZ2005]the Key Special Project for the Introducing Talents Team of the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou)[grant number GML2019ZD0306]the Innovation Academy of South China Sea Ecology and Environmental Engineering [grant number ISEE2018PY06]
基金The National Basic Research Program of China under contract Nos 2012CB417404 and 2011CB403504the National Natural Science Foundation of China under contract No. 41075064the National High Technology Research and Development Program of China under contract No. 2008AA09A404-3
文摘The sea-level anomaly (SLA) from a satellite altimeter has a high accuracy and can be used to improve ocean state estimation by assimilation techniques. However, the lack of an accurate mean dynamic topography (MDT) is still a bothersome issue in an ocean data assimilation. The previous studies showed that the errors in MDT have significant impacts on assimilation results, especially on the time-mean components of ocean states and on the time variant parts of states via nonlinear ocean dynamics. The temporal-spatial differences of three MDTs and their impacts on the SLA analysis are focused on in the South China Sea (SCS). The theoretical analysis shows that even for linear models, the errors in MDT have impacts on the SLA analysis using a sequential data assimilation scheme. Assimilation experiments, based on EnOI scheme and HYCOM, with three MDTs from July 2003 to June 2004 also show that the SLA assimilation is very sensitive to the choice of different MDTs in the SCS with obvious differences between the experimental results and observations in the centre of the SCS and in the vicinity of the Philippine Islands. A new MDT for assimilation of SLA data in the SCS was proposed. The results from the assimilation experiment with this new MDT show a marked reduction (increase) in the RMSEs (correlation coefficient) between the experimental and observed SLA. Furthermore, the subsurface temperature field is also improved with this new MDT in the SCS.
基金This Work was partly supported by the Youth Science Foundation of Ocean University of Qingdao.
文摘Collinear analysis technique is widely used for determining sea surface variability with Geosat altimeterdata from its Exact Repeat Mission(ERM).But most of the researches have been only on global scaleor in oceans deeper than 2000 m.In shallow shelf waters this method is hampered by the inaccuracy ofocean tide data supplied with Geosat Geophysical Data Records(GDRs).This work uses a modified collinearanalysis technique characterized by simultaneous separation of mean sea level and ocean tide with theleast squares method,to compute sea surface variability in the Northwest Pacific Ocean and eastern ChinaSeas.The mean sea level map obtained contains not ouly bathymetric but also dynamic features such asamphidromes,indicating considerable improvement over previous works.Our sea surface variability mapsshow clearly the main current system,the well-known Zhejiang coastal upwelling,and a northern East Chi-na Sea meso-scale eddy in good agreement with satellite sea surface temperature(SST)observation and
基金supported by a grant from the National Social Science Foundation of China (No. 13CTY031)
文摘Background: Self-efficacy has been identified as an important determinant of youth's behavior change including physical activity(PA) participation. However, the dimensionality check of a PA self-efficacy scale has rarely been conducted in China. The current study aims to examine(1) the unidimensionality of a shortened Chinese version of PA self-efficacy scale(S-PASESC);(2) the measurement invariance of S-PASESC across gender and levels of education;(3) the latent factor mean difference between gender and levels of education;(4) the direct effects of self-efficacy on PA by different gender and education levels; and(5) the comparisons of the direct effects of self-efficacy on PA across gender and education levels.Methods: The participants were 5 th through 11 th grade public school students recruited from 7 cities located in different geographic regions of China. The final data include a total of 3003 participants(49.7% boys) who have completed the scales.Results: Confirmatory factor analysis(CFA) test supported the unidimensionality of S-PASESC. The S-PASESC is invariant across gender and 3 levels of education at both configural, full metric, and full scalar levels. Findings from latent mean comparisons showed that boys reported higher PA self-efficacy than girls. Students' perceived PA self-efficacy tend to decrease from elementary to high school. Finally, self-efficacy positively related to PA by groups of different gender and education levels and the relationship between self-efficacy and PA is stronger among middle school boys than girls.Conclusion: Findings suggest S-PASESC is a valid scale for measuring Chinese students' PA self-efficacy.
文摘Short time existence and uniqueness for the classical motion are studied by the function of the principal curvatures of a smooth surface and the Evans and Spruck's results are generalized.
文摘To study the period components in the monthly mean sea level variations in the Pacific Ocean, this paper analyses the monthly mean series of 236 tide gauge stations in the Pacific on the basis of the improved analytical method of the monthly mean sea level period signals. The results show that the oscillation periods of the sea level series are not fixed, but vary with stations. This paper also discusses the existences of the quasi-2 years atmospheric oscillation period, the 3~7 a period related to the El Nino events, sunspots, double sunspots and the 25~30 a overlength oscillation periods. The corresponding amplitudes and initial phase angles as well as the linear trend coefficient are obtained by using significant period components plus the linear trend to fit the monthly mean sea level series. A conspicuous features of the results are found,i. e.,taking 25°~30°S as the axial line in the Pacific, the annual lags gradually increase to the north and the south respectively, depicting a variation trend of partial symmetry. But in China seas, the north and south distributional trend of the annual period lags is almost opposite to those in most parts of the Pacific Ocean. In the low-latitude zone where El Nino events occur or impose more significant effects, the ratio of the sum of amplitudes of various periods within 2~7 a to the annual amplitude is equal to or more than 1. 0, while that of the sum of amplitudes of periods larger than 8 a to the annual amplitude is equal to or more than 0. 5. This suggests that the dominant role of annual amplitude in the monthly mean sea level series of this region has declined and that, correspondingly, there exist significant period components of El Nino events as well as the long-period oscillations of quasi-10 a and over 10 a. In the high-latitude zone, off China, in North America north of 40°N and the coast of Japan, the annual period oscillation occupies a dominant position in the various period components.
文摘This paper summarizes the general methods,existing problems and their causes of the period analysis for the monthly mean sea level and points out that it is the key to the analysing period signals and forecasting the change trend of the monthly mean sea level that the periods of the signals are selected reasonably. As there are often many period signals in these series, nonlinear effects exist between pairs of period signals. In order to avoid the false periods that may be introduced due to the effects of side lobes and the periods with statistical phase significance coherence that may be introduced due to the effects of nonlinear effects and their restraint to other period signals, the maximum entropy spectral analysis and the corresponding significance period test may be performed repeatedly on the basis of the bispectrum analysis and meanwhile the most significant period component is filtered out by the least square filtering method, i. e., the method of the significance period analysis with mixed spectra modeled by a nonlinear system is adopted and the signal periods approaching the reality are selected one by one. The examples of the bispectrum analysis, the signal period analysis by mixed spectra and the fitting parameters for combined period components with linear trend in the time series of monthly mean sea level are given in this paper.
文摘Monthly changes of sea level recorded on the seas adjacent to Korea (the Huanghai Sea, the East ChinaSea and the East As) are investigated. The major influences on the spatial and temporal variation of mean sea level arequantitatively identified. A set of modes of monthly air pressure variation over the Huanghai Sea, East China Sea andEast Sea for the period of 1978-1992 is obtained. Each monthly air pressure distribution can be precisely defined bylinear combination of these modes. Hence, the set of air pressure series can be replaced by a set of time varying coefficents, where each coefficient describes the contribution of a particular mode to a given air pressure distribution. A selected set of the modal coefficients is then added to a multiple Fegresion model, consisting of a trend, monthly wind stress and tidal term, in an attempt to represent the effect of meteorological variations on monthly mean sea level on the seas adjacent to Korea. It is found that although the model may account for over 90% of the observed mean sea level variance, there still remains a high correlation between the residuals, hence identifying a regional variation for further study.
基金partially supported by the Natural Science Foundation of China(Grant No.41974040)。
文摘Global mean sea level budget is rigorously adjusted during the period 2005-2015.The emphasis is to provide the best estimates for the linear rates of changes(trends)of the global mean sea level budget components during this period subject to the constraint:Earth’s hydrosphere conserves water.The newly simultaneously adjusted trends of the budget components suggest a larger correction for the global mean sea level trend implicated by the other budget components’trends under the budget constraint.The simultaneous estimation of the linear trends of the budget components subject to the constraint for closure improves their uncertainties and enables a holistic assessment of the global mean sea budget,which has implications for future sea level science studies,including the future Intergovernmental Panel on Climate Change(IPCC)Assessment Reports,and the US Climate Assessment Reports.
文摘-In this paper, the maximum entropy spectral, the cross-spectral and the frequency response analyses are madeon the basis of the data of monthly mean sea levels at coastal stations in the Bohai Sea during 1965-1986. The results show that the annual fluctuations of the monthly mean sea levels in the Bohai Sea are the results of the coupling response of seasonal variations of the marine hydrometeorological factors. Furthermore, the regression prediction equation is obtained by using the double screening stepwise regression analysis method . Through the prediction test , it is proved that the obtained results are desirable.
基金supported by the Youth Ocean Science Foundation of SOA, China (2010208)the National Natural Science Foundation of China (41030856)
文摘Tidal data from Weizhou, Zhapo, and Shanwei stations between 1969 and 2010 and from five gauging stations in the western Pacific Ocean provided by PSMSL, and the global mean sea level data recorded between December 1992 and December 2010 by TOPEX and Jason satellites were compiled and analyzed. The results show that the perennial mean sea level near Weizhou Island is 211.7 cm(relative to the water gauge zero), and the relative mean sea level rising rate is 2.2 mm yr-1 from 1969 to 2010, which is consistent with the relative mean sea level rising rate recorded at other gauging stations in the western Pacific regions and with the global mean sea level rising rate. The absolute mean sea level rising rate at Weizhou Island is 3.0 mm yr-1 from 1993 to 2010, also conforming with the global mean sea level rising rate(3.1±0.4 mm yr-1) during the same time period. The highest annual tide level at Weizhou Island has a rising rate of 4.6 mm yr-1 and shows a 20-year quasi-periodic variation from 1966 to 2010. The primary cause of the mean sea level rising is global warming.
基金Supported by the National Key R&D Program of China (No.2021YFC3001000)the National Natural Science Foundation of China (Nos.U1911204,51861125203)。
文摘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.
文摘The latest Intergovernmental Panel on Climate Change (IPCC) report shows that sea-level rise, which has been accelerated since the 19th century resulting to the global warming, threatens coastal areas with high population growth. A Global Sea Level Observing System (GLOSS) assessment highlighted the lack of data in Africa, and in Côte d’Ivoire in particular. In order to estimate the evolutionary trend of sea level along the Ivorian coast, and to draw up preventive plans to protect properties and populations, we digitized 65 years of historical tidegrams recorded in the Ebrie Lagoon, using the “Surfer” and “Nunieau” software, then processed them using “T-Tide” and “U-Tide” software. The average levels were calculated using the Demerliac filter from complete daily (day and night) recordings for providing a usable database of 31 years of hourly lagoon data from 1979 to 2015. Our results show that a mean water level in lagoon is 1.04 m. The evolutionary trend in sea level, estimated in the lagoon via the Vridi canal, during the rainy season is the most significant at 2.93 mm/year. This is followed by the dry season, with a trend of 2.89 mm/year. The flood season trend is 2.78 mm/year. This suggests that marine water inflows dominate continental inflows. Our results highlight the vulnerability of Côte d’Ivoire’s coasts to the risk of marine submersion.
文摘为了解中东大西洋渔业产区渔获物的资源状况,根据世界粮农组织(FAO)提供的该海域1950—2019年的渔获量数据,结合渔获种类的平均营养级(mean trophic level,MTL)信息,运用统计学方法分析70年间渔获物平均营养级和营养级平衡指数(fishing in balance,FiB)的变动规律,以掌握该海域渔业资源的可持续利用情况。结果显示,MTL大致可分为4个阶段,1950—1956年,MTL指数在3.20左右,无明显变化;1957—1963年,MTL指数迅速上升至3.44;1964—1996年,MTL在波动中趋于下降,历史最高值(3.54)出现在1985年;1997—2019年,MTL稳定在较高水平,其中2018年为该阶段最低点3.35。FiB指数整体呈上升趋势,1950—1956年,FiB指数呈小幅波动增加;1957—1974年,FiB指数显著上升;1975—1996年,FiB指数呈平稳波动状态;1997—2019年,FiB指数整体呈小幅增长趋势。结果表明,中东大西洋海洋生态系统相对稳定,但潜在的渔业资源量越来越少,开发潜力有限。