Abstract：Airborne geophysical data often suffer from corrugations or line level errors, which can be adjusted or removed by using levelling procedure. Levelling is a critical step in airborne geophysical data processing and interpretation. Microlevelling routine can be applied to removing the remaining line level after tie line leveling. Based on practical aeromagnetic data levelling, the authors deal in detail with the principle of microlevelling and key steps in microlevelling procedure. For the purpose of microlevelling data, a directional high pass filter perpendicular to the flight line direction is first employed to produce a decorrugation noise grid. The noise grid is then extracted as new channel flight data. Amplitude limiting and low pass filtering can be applied to the noise channel so as to remove the residual geological signal and leave only the component of line level drift, which is then subtracted from the original data to produce the final microlevelled data. This paper has also discussed some key technical problems in airborne geophysical data leveling, especially in microlevelling. The discussion in this paper may be useful in practical data processing.
[1] 熊盛青. 发展中国航空物探技术有关问题的思考[J].中国地质, 2009, 36(6):1366-1374.[2] Luyendyk A P J. Processing of airborne magnetic data[J]. AGSO Journal of Australian Geology and Geophysics, 1997, 17(2):31-38.[3] Foster M R, Jines W R, Van Der Weg K. Statistical estimation of systematic errors at intersections of lines of aeromagnetic Survey Data[J]. Journal of Geophysical Research, 1970, 75(8):1507-1511.[4] Kellogg W C, Yarger H L, Robertson R R, et al. Diurnal drift removal from aeromagnetic data using least squares[J]. Geophysics, 1978, 43(6):1148-1156.[5] Green A A. A comparison of adjustment procedures for leveling aeromagnetic survey data[J]. Geophysics, 1983, 48(8):745-753.[6] Minty B R S. Simple micro-leveling for aeromagnetic data[J]. Exploration Geophysics, 1991, 22(4):591-592.[7] Ferraccioli F, Gambetta M, Bozzo E. Microlevelling procedures applied to regional aeromagnetic data:An example from the Transantarctic Mountains[J]. Geophysical Prospecting, 1998, 46(2):177-196.[8] 中国国土资源航空物探遥感中心.中国及毗邻海域航空磁力ΔT异常图(1:500万)[M].北京:地质出版社,2004.[9] 王乃东.有关1:25万航磁系列图的几个问题[J]. 物探与化探,2007,31(5):459-464.[10] Green A A. Leveling airborne gamma-radiation data using between-channel correlation information[J]. Geophysics, 1987, 52(11):1557-1562.[11] Nelson J B. Leveling total-field aeromagnetic data with measured horizontal gradients[J]. Geophysics, 1994, 59(8):1166-1170.[12] Pilkington M, Roest W R. Removing varying directional trends in aeromagnetic data[J]. Geophysics, 1998, 63(2):446-453.[13] Fedi M, Florio G. Decorrugation and removal of directional trends of magnetic fields by the wavelet transform:Application to archaeological areas[J]. Geophysical Prospecting, 2003, 51(4):261-272.[14] Mauring E, Kihle O. Leveling aerogeophysical data using a moving differential median filter[J]. Geophysics, 2006, 71(1):L5-L11.[15] Huang H. Airborne geophysical data leveling based on line-to-line correlations[J]. Geophysics, 2008, 73(3):F83-F89.[16] Beiki M, Bastani M, Pedersen L B. Leveling HEM and aeromagnetic data using differential polynomial fitting[J]. Geophysics, 2010, 75(1):L13-L23.[17] Naudy H, Dreyer H. Essai de filtrage non-lineaire applique aux profis aeromagnetiques[J]. Geophysical Prospecting, 1968, 16(2):171-178.[18] 贝庚. 用非线性滤波法处理航磁剖面[J].地质与勘探,1978,14(1):90-92.[19] 张维斌.介绍法国处理航磁数据中的简单方法[J]. 物探化探计算技术,1980,2(1):48-55.[20] 梁锦文.一种非线性滤波方法的试验效果[J].物探化探计算技术,1981,3(2):22-28.[21] 于长春,熊盛青,郭志宏,等.改进的非线性滤波方法在中高山地区的应用[J].物探与化探,2003,27(1):39-42.[22] 郭志宏,刘浩军,熊盛青.平面网格位场数据的空间域非线性曲率滤波方法[J].地球物理学进展,2003,18(1):134-137.[23] 刘浩军,薛典军,郭志宏,等.航空物探软件系统研制[J].物探与化探,2003,27(2):146-149.
