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黑潮延伸体区域海表温度锋的时空变化特征分析 被引量:2
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作者 刘明洋 谭言科 +2 位作者 李崇银 余沛龙 殷明 《热带气象学报》 CSCD 北大核心 2017年第6期903-911,共9页
利用NOAA最优插值逐日海表温度资料和AVISO中心的海表高度异常资料,分析了黑潮延伸体区域的海表温度锋的时空变化特征以及导致其年代际变化可能的原因。结果表明,气候平均态的黑潮延伸体区域海表温度锋位于黑潮延伸体区域北部边缘,在143... 利用NOAA最优插值逐日海表温度资料和AVISO中心的海表高度异常资料,分析了黑潮延伸体区域的海表温度锋的时空变化特征以及导致其年代际变化可能的原因。结果表明,气候平均态的黑潮延伸体区域海表温度锋位于黑潮延伸体区域北部边缘,在143°E和150°E附近存在两个弯曲,SST水平梯度最大值出现在142°E附近,强度超过4.5℃/(100 km),其后强度自西向东逐渐递减,在149°E附近又出现一个较弱的大值中心,在141~153°E范围内,海表温度锋位置的平均值为36.25°N,强度的平均值为3.22℃/(100 km)。黑潮延伸体区域的海表温度锋南北位置的季节变化很弱,而其强度的季节变化非常显著。相较于较弱的季节变化,海表温度锋位置的年际和年代际的低频变化则要显著得多,其南北变化跨度超过2°。海表温度锋强度的年际和年代际的低频变化也较强,超过4.5℃/(100 km)。黑潮延伸体区域的海表温度锋的变化与太平洋年代际振荡(PDO)以及北太平洋涡旋振荡(NPGO)存在显著的相关关系,NPGO和PDO在中东太平洋区域会强迫产生海表高度异常,随后向西传播,在约3年后到达黑潮延伸体区域,使该区域流场发生变化产生海洋热平流异常,最终导致海表温度锋强度发生变化。 展开更多
关键词 黑潮延伸体 海表温度锋 时空变化 PDO NPGO
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A linear crack length measurement method for railway bridges based on calibration points fitting 被引量:1
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作者 WANG Ji-wu yu Peng-fei +1 位作者 LUO Hai-bao yu pei-long 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2020年第2期118-125,共8页
For the linear crack skeleton of railway bridges with irregular strike,it is difficult to accurately express the crack contour feature by using a single smoothing fitting algorithm.In order to improve the measurement ... For the linear crack skeleton of railway bridges with irregular strike,it is difficult to accurately express the crack contour feature by using a single smoothing fitting algorithm.In order to improve the measurement accuracy,a polynomial curve fitting was proposed,which used the calibration point of crack contour as the boundary point,and then put them all together to produce a continuous contour curve to achieve the crack length measurement.The method was tested by measuring the linar cracks with different shapes.It is shown that this proposed algorithm can not only solve the jagged problem generated in the crack skeleton extraction process,but also improve the crack length measurement accuracy.The relative deviation is less than 0.15,and the measurement accuracy is over 98.05%,which provides a more effective means for the crack length measurement in railway bridges. 展开更多
关键词 crack skeleton length measurement calibration point polynomial fitting railway bridge
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