The Study On Diural Variation Correction Mode Of Marine Magnetic

In order to strengthen the construction of our coastal marine geological andgeophysical survey basic database,it is necessary to conduct a comprehensive andsystematic collation of boat gravity,magnetic and seismic data, forming the digitallibrary to meet the needs of the national results, and constructing “Digital Ocean”basic framework.Marine magnetic data processing as one of the important aspects, working out asophisticated marine magnetic data compilation software is necessary. We use Matlab,C#language. According to marine geology and geophysics survey specifications andmarine magnetic data processing, developed a magnetic pre-processing softwareconsists of diurnal variation correction, magnetic anomalies and adjustmentprocessing. In practical work, magnetic raw data is complex. After removing theoutliers, filtering, interpolation operation, raw data records may still exist problems.We focused on the error message in the calculation of the magnetic anomaly. addingthe appropriate error message, easily and quickly find the error. In the treatmentworks, all sectors are subject to a map, convenienting to test. We dealed with anumber of blocks of actual magnetic data in Nanhai sea and obtained the satisfactoryresults. In terms of design, processing speed or in the treatment outcomes, thesoftware has achieved satisfactory results.Magnetic measurements in the ocean, the greatest impact on the magneticmeasurement accuracy is solar diurnal variation of the geomagnetic field, calleddiurnal variation.If we want to get the diurnal variation correction value on thediurnal variation station,first we must obtain the diurnal variation correction basevalue.We take out four conventional method to get the diurnal variation correctionbase value in the sofeware: the average value method proposed by standard, themoment method base, the base period method proposed by bian and weighted averagemethod proposed by Lee. Four methods have the same calculation principle.They all have their certain rationality. On this basis, we have tried a method named empiricalmode decomposition (EMD) method suitable for short-term measurements and amethod according to the normal field and magnetic anomalies suitable for long-termmeasurements. A satisfactory result was got in processing different blocks data ofNanhai sea by using this software，proved the feasibility of the new method.How to get a reasonable magnetic quiet part and magnetic disturbance part ofdiurnal variation data in magnetic disturbance day，there is not a very reasonableapproach in tradition. We improved specification diurnal variation correction methodin magnetic disturbance day by observing the actual diurnal variation data.effectivelyweaken the offset caused distortion correction between magnetic quiet part andmagnetic disturbance part of diurnal variation data.We hnow that according to raw data to obtain the magnetic anomaly and then getprecision through adjustment for processing the magnetic data,there are largeamounts of data and easily lead to a variety of problems. Through human-computerinteraction, real-time testing, we can ensure a higher final magnetic data accuracy andachieve better results.