A Method for Calculating Thermocline Characteristic Elements in Shelf Sea Area--Quasi-step Function Approximation Method
A Method for Calculating Thermocline Characteristic Elements in Shelf Sea Area--Quasi-step Function Approximation Method
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发表时间：
2003
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通讯作者：
Ren Ge;F. Qiao;Fei Yu;Z. Jiang;Jingsong Guo
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作者：
Ren Ge;F. Qiao;Fei Yu;Z. Jiang;Jingsong Guo
中国陆架海区CTD资料表明，大部分水文要素的垂向结构可以理想化地描述为3层结构模式，即上部均匀层、温跃层和下部均匀层。本文提出了拟阶梯函数逼近法，采用由3条线段组成的拟阶梯函数拟合水文要素的垂向剖面，用最小二乘法求出两个拐点的位置和温跃层的上、下界，并将两个拐点连线的斜率作为温跃层强度。陆架海区的垂直温度结构可概括为正温跃层、逆温跃层、单向多温跃层和正逆温跃层混合型4种类型，不同温跃层类型的特征要素可通过一个或多个拟阶梯函数的最小二乘拟合计算得到。
It is shown from the CTD data collected in Chinese shelf sea area that most of vertical structures of hydrographic elements can be idealized as a 3-layer structure pattern, namely, upper homogeneous layer, thermocline and lower homogeneous layer. In this paper, the quasi-step function approximation method is propsed, i.e., a quasi-step function composed of 3 line segments is used to fit the vertical profile of hydrographic element, the least square method is used to get the two inflection point positions, the upper and lower thermocline bounds, and the slope of the line connecting the two inflection points is taken as the thermocline intensity. The vertical temperature structures in the shelf sea area can be summarized as 4 patterns, positive thermocline, reverse thermocline, unidirectional multi-thermocline and mixed positive and reverse thermocline patterns, and the characteristic elements of different thermocline patterns can be calculated by the least squares fit of one or several quasi-step functions.