On the surface roughness characteristics of the land fast sea-ice in the Bohai Sea
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On the surface roughness characteristics of the land fast sea-ice in the Bohai Sea LIU Chengyu1,2, CHAO Jinlong1,3, GU Wei1*, LI Lantao1,3, XU Yingjun1 1
State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China 2 Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China 3 Academy of Ministry of Civil Affairs and Ministry of Education for Disaster Reduction and Emergency Management, Beijing Normal University, Beijing 100875, China Received 16 July 2012; accepted 19 February 2014 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2014
Abstract The surface roughness characteristics (e.g., height and slope) of sea ice are critical for determining the parameters of an electromagnetic scattering, a surface emission and a surface drag coefficients. It is also important in identifying various ice types, retrieval ice thickness, surface temperature and drag coefficients from remote sensing data. The point clouds (a set of points which are usually defined by X, Y, and Z coordinates that represents the external surface of an object on earth) of land fast ice in five in situ sites in the eastern coast Bohai Sea were measured using a laser scanner-Trimble GX during 2011–2012 winter season. Two hundred and fifty profiles selected from the point clouds of different samples have been used to calculate the height root mean square, height skewness, height kurtosis, slope root mean square, slope skewness and slope kurtosis of them. The root mean square of the height, the root mean square of the slope and the correlation length are about 0.090, 0.075 and 11.74 m, respectively. The heights of 150 profiles in three sites manifest the Gaussian distribution and the slopes of total 250 profiles distributed exponentially. In addition, the fractal dimension and power spectral density profiles were calculated. The results show that the fractal dimension of land fast ice in the Bohai Sea is about 1.132. The power spectral densities of 250 profiles can be expressed through an exponential autocorrelation function. Key words: sea ice, roughness, statistical parameters, fractal dimension, spectral density Citation: Liu Chengyu, Chao Jinlong, Gu Wei, Li Lantao, Xu Yingjun. 2014. On the surface roughness characteristics of the land fast sea-ice in the Bohai Sea. Acta Oceanologica Sinica, 33(7): 97–106, doi: 10.1007/s13131-014-0509-3
1 Introduction Sea ice has caused a lot of adverse impacts on an offshore aquaculture, a marine transportation, and an offshore oil engineering. To limit these adverse impacts, it is critical to collect the information of sea ice (thickness, extent and concentration) precisely. A remote sensing technology has superiority for obtaining real-time and large-scale sea ice information, and it has played an important role in sea ice monitoring in the Bohai Sea in recent years. As a general rule, the sea-ice surface is always rough (Wadhams, 2000). So most of the sea-ice surface in the Bohai Sea are also not
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