Study On The Marine Magnetotelluric Data Processing System

Marine land magnetotelluric (MT) technology usually replants that of the common land. In view of basic theory, data acquirement, data processing and data explanation, the marine magnetotelluric technology is similar to the land magnetotelluric technology. However, owing to the different environment between the land and the seabed, there are differences in apparatus record format, sensor disposal and electromagnetic wave noise. On the basis of the common land magnetotelluric data processing, aiming at the differences between marine and land MT technology, the paper studies the methods of marine magnetotelluric data processing.Compared with the common land, the most significant characteristic of the seabed is its magnetic attenuation caused by the highly conductive sea water. In addition, related theories demonstrate that the movement of the sea generates electromagnetic field which definitely affects the following data processing and explanation. The article calculates electromagnetic field spectrum at all weights which demonstrates that strong noise exists in the seabed's magnetic signal from 0.1Hz to1Hz.Focusing on the data format difference between the apparatus record and the data processing software, converting software is programmed. The apparatus'binary format data is converted into ASCII format which is desired by the data processing software. Ocean current and bumpiness of the seabed may cause sensor's obliquity and orientation which affect the exactness of the results. Based on transform principle of geometry graphics and the obliquity and orientation records in the apparatus, rectifying software is programmed. The effectiveness of the software is proved by comparison between the rectified temporal sequence waveforms and the not-rectified ones.The parameters and configuration of marine land MT data processing software is very complex. To regulate the marine land MT data processing, data processing system platform is programmed in VB.net language. The"shell"function can be called to execute the program. The results demonstrate that the marine land MT data processing system platform can effectively execute data processing and calculates apparent resistivities and phases.