Diurnal variation effect in marine magnetometric surveys: clues from surveys in southeast Brazil

Author(s)

Sergipe, Paula Possamai ^[1] ; Marangoni, Yara Regina ^[2] ; Zanon dos Santos, Roberto Paulo ^[2] ; de Moura, Denise Silva ^[2] ; Jovane, Luigi ^[1]

Affiliation

^[1] Univ Sao Paulo, Oceanog Inst, Sao Paulo - Brazil

^[2] Univ Sao Paulo, Inst Astron Geophys & Atmospher Sci, Sao Paulo - Brazil

• Document type: Journal article
• Source: MARINE GEOPHYSICAL RESEARCH; v. 42, n. 3 SEP 2021.
• Web of Science Citations: 0

Abstract

The diurnal variation of the magnetic field cannot be predicted or modeled and for that reason, it is monitored during the magnetic surveys, usually by a stationary magnetometer. However, marine surveys have a practical issue with diurnal monitoring, owing to the distance between the survey, stationary magnetometers, and magnetic observatories. This work aims to verify the use of nearby magnetic observatories to estimate the diurnal variation correction in different marine surveys and evaluate its effectiveness. In this study, we selected surveys at the continental shelf near Santos city (Survey 1), continental slope next to the first survey location (Survey 2), continental shelf near Ubatuba city (Survey 3), and Mamangua ria in the Paraty city (Survey 4), all southeast to the Brazilian coast. The crossing points were implemented to compare the magnetic field values at different times and days at the same measurement point, before and after the correction. Afterwards, we measure the Pearson's Correlation of the raw data and the diurnal corrected data in all crossing points of each survey which showed an improvement after correction by the value approximating to 1, which indicates a very well correlation. The Ubatuba and Mamangua surveys allowed comparing the observatory correction results with the base magnetometer results that were rather similar. Our analyses indicate a satisfactory diurnal correction using the observatory data and the crossing points approach, which can be used for every marine magnetometric survey worldwide placed near the coast (< 280 km) that do not have a stationary magnetometer available. (AU)

• FAPESP's process: 18/19355-7 - Analysis of magnetic profiles in NW-SE direction at Santos Basin/SP: is the Ribeira Fold Belt the basement of the basin at São Paulo Coast line
• Grantee: Paula Possamai Sergipe
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 16/24946-9 - Sea-level changes and Global Monsoon System: clues from marine cores in Brazil
• Grantee: Luigi Jovane
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants