Experimental measurements of the magnetic field vertical gradient during the "North Pole-42" expedition

Research in the Arctic by means of drifting scientific stations has been conducted in our country since 1937. The expeditions "North Pole" ("Severny Polyus", SP) carry out oceanographic, geophysical, hydroacoustic, and other observations. Since 2022, started the operation of a specially designed ice-resistant self-propelled platform (ISP). During the "drifting" expeditions SP-41 and SP-42, magnetometers were installed on the ice at a distance from the ice-resistant self-propelled platform, continuously measuring the components of the Earth's magnetic field. Processing such data to extract anomalies of geological origin is complicated by the intricate procedure of accounting for magnetic variations and the inability to perform it accurately due to the remoteness of variation stations. At the same time, the magnetic anomalies of the Arctic Ocean are of great interest, as they contain stripe magnetic anomalies in the Gakkel Ridge area, which allow for paleomagnetic dating of the ocean floor's age. In the Alpha Ridge area, anomalies of trap rock strata of debatable origin are observed. This paper presents the results of an experiment to study the vertical gradient of the magnetic field using SeaSPY and POS 4 instruments, conducted during the "Severny Polyus-42" (North Pole-42) expedition. The measurement methodology implemented during the "Severny Polyus" expedition was tested for the first time. The primary focus is on the analysis of initial data quality, assessment of the magnetic field's vertical gradient, and comparison of the results with regional magnetic anomalies. Determining the vertical gradient with a large (over 200 m) distance between the instruments proved to be highly stable. The obtained vertical gradient anomalies are representative, and their amplitude significantly exceeds the noise level. It is shown that the observation methodology and the quality of the obtained results allow for effective detection of target anomalies. To confirm the possible geological nature of the anomalies, two-dimensional petromagnetic modeling was performed; in the presented version-without the use of prior information. Further refinement of the measurement methodology is required to ensure the safety of the marine submersible magnetometer under drifting conditions in dense ice cover.