利用不同方法校正船体运动对海气通量观测结果的影响

The Air-Sea Eddy Covariance Fluxes Correction Using Different Methods for the Ship-based Measurement

采用姿态校正法、滤波法、改进滤波法以及耗散法等方法,分析了北黄海冬季船载涡动相关资料,并结合协谱分析研究了不同方法对海气通量观测结果的校正效果。结果显示,船体运动对动量通量观测结果有明显影响,对感热、潜热等通量观测结果的影响很小。关于动量通量,对定点观测资料采用姿态校正法与耗散法可以得到比较合理的结果,而对走航观测资料各种校正方法的处理结果均存在一定的不确定性。滤波法在校正船体运动影响的同时,也去除了海洋大气中存在的与船体运动同频率的真实湍流脉动,改进滤波法可以在一定程度上修正滤波法对协谱的低估,但对湍流通量的估计仍有一定误差。耗散法可以得到比较合理的动量通量,但对感热和潜热通量的估计明显偏大。

The air-sea eddy covariance fluxes were measured on anchored and moving oceanographic research vessel in the North Yellow Sea.The different methods containing the gyro-stabilized method,the filtering method,the revised filtering method and the inertial-dissipation method were used to correct the ship-motion induced noise.Performance of the correction methods was evaluated by analyzing the cospectra of turbulent fluxes.It was shown that the effect of the ship-motion was considerable to the momentum flux measurement,and was slight to the sensible and latent heat flux measurement.For momentum flux correction,the gyro-stabilized method and inertial-dissipation method can obtain reasonable results for measurement on anchored platform,and the uncertainties were found in the results of all correction methods for measurement on moving platform.The filtering method can remove the effect of ship-motion,but it also removed the turbulent fluctuations in marine atmosphere,frequency of which coincides with that of the ship-motion.The revised filtering method can partly resolve the problem caused by the filtering method,but its results were also contaminated in the determination of turbulent fluxes.The inertial-dissipation method can obtain reasonable momentum flux.However,the results of sensible and latent heat flux were overestimated.