Direct covariance flux estimates from mobile platforms at sea
Direct covariance flux estimates from mobile platforms at sea
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DOI：
10.1175/1520-0426(1998)015
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发表时间：
1998-04-01
影响因子：
2.2
通讯作者：
Fairall, CW
中科院分区：
文献类型：
--
作者：
Edson, JB;Hinton, AA;Fairall, CW
本文描述了由安装在海上运动平台上的风速计计算直接协方差通量的两种方法。这些方法涉及使用捷联系统或陀螺稳定系统，这些系统用于计算以下项：1)由于平台的俯仰、滚动和航向变化而引起的风速的瞬时倾斜；2)由于平台绕其局部坐标系轴旋转而在风速计上的角速度；以及3)平台相对于固定参照系的平移速度。本文比较了三种捷联系统从最近的两次野外实验中计算出的通量。这些比较表明，直接协方差通量与用整体空气动力学方法得到的通量有很好的一致性。另外，船舶系统和研究平台Flip之间的比较表明，流动扭曲系统使动量通量系统地增加了15%。有证据表明，这一修正适用于一类常用的科考船。应用对运动污染和失真如何导致直接协方差通量估计的校正，不确定度约为10%-20%。
This paper describes two methods for computing direct covariance fluxes from anemometers mounted on moving platforms at sea. These methods involve the use of either a strapped-down or gyro-stabilized system that are used to compute terms that correct for the 1) instantaneous tilt of the anemomter due to the pitch, roll, and heading variations of the platform; 2) angular velocities at the anemometer due to rotation of the platform about its local coordinate system axes; and 3) translational velocities of the platform with respect to a fixed frame of reference. The paper provides a comparison of fluxes computed with three strapped-down systems from two recent field experiments. These comparisons shows that the direct covariance fluxes are in good agreement with fluxes derived using the bulk aerodynamic method. Additional comparisons between the ship system and the research platform FLIP indicate that flow distortion systematically increases the momentum flux by 15%. Evidence suggests that this correction is appropriate for a commonly used class of research vessels. The application of corrections for both motion contamination and how distortion results in direct covariance flux estimates with an uncertainty of approximately 10%-20%.