On the parameterization of drag coefficient over sea surface
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On the parameterization of drag coefficient over sea surface WANG Juanjuan1,2 , SONG Jinbao1∗ , HUANG Yansong3 , FAN Conghui1 1
Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China University of Chinese Academy of Sciences, Beijing 100049, China 3 South China Sea Marine Engineering Surveying Center, South China Sea Branch, State Oceanic Administration, Guangzhou 510300, China 2
Received 20 March 2012; accepted 5 September 2012 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2013
Abstract Six parameterization schemes of roughness or drag coefficient are evaluated on the basis of the data from six experiments. They present great consistency with measurement when friction velocity u ∗ 50
Notes: — denotes unknown.
2.1.1 RMMT The buoy was moored around Zhangzi Island (39◦ 02.908’N, 122◦ 44.355’E, and 44.5 m mean water depth) in the north Huanghai Sea. An eddy correlation system was mounted in the buoy. Three ultrasonic anemometers were installed at about 2, 4 and 6 m above the sea surface. Here, we choose the turbulent data from CSAT3 (from Campbell instruments) installed at the highest layer. A motion pack consisted of a digital magnetic compass and a gyro was mounted in the center of buoy and used to correct the motion of platform. The sampling frequency of ultrasonic anemometer and motion pack was 10 Hz. Besides, three additional meteorological measure-
ments were installed at the top of buoy with sampling interval 1 min. The turbulent data and meteorological measurement data from 25 September to 19 October in 2009 were adopted (Huang et al., 2013). Before calculating the momentum flux and the fiction velocity, the turbulent data had been processed according to the quality control algorithm introduced by Vickers and Mahrt (1997). Especially, the motion correction must have been made to remove the effect of platform motion on the basis of the work of Miller et al. (2008). Subsequently, the threedimensional wind speeds were rotated into an along-wind component and a cross-wind component. Then, according to the
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WANG Juanjuan et al. Acta Oceanol. Sin., 2013, Vol. 32, No. 5, P. 68-74
multiresolution decomposition method introduced by Vichers and Mahrt (2003), we choose appropriate cutoff time to calculate the turbulent fluctuation and obtain the eddy covariance momentum flux. The wave measurement was obtained by an AWAC (acoustic wave and current profiler) from the Nortek Company. It was moored near the buoy and used to measure the sea surface elevation and the current profile. The data from 25 September to 19 October were adopted. Each 3 h, the AWAC worked 1024 s with sampling frequency 2 Hz and then got a group data of wave related parameters, such as significant wave height and spectral peak period. 2.1.2 HEXMAX The data were collected in the neighborhood of Dutch offshore platform Meetpost Noordwijk (MPN). The eddy covariance momentum flux and dissipation measurements of the wind stress were obtained. Here, we use the data subset provided by Janssen (1997)
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