Analysis of the Impact of Long‐Term Changes in the Geomagnetic Field on the Spatial Pattern of the Weddell Sea Anomaly.

We simulated the impact of long‐term changes in the geomagnetic field on the spatial pattern of the Weddell Sea Anomaly (WSA). The Weddell Sea Anomaly, belonging to the region near the tip of the Antarctic Peninsula, Falklands, and surrounding seas, is the best‐known example of ionospheric reversed diurnal cycle. This paper investigates whether and to what extent long‐term changes in the geomagnetic field influence spatial morphology of the WSA. The major concept centers on a normalized density difference index, serving as a measure of difference between dayside and nightside ionospheric density. Through combined analysis of in situ ionospheric electron density data from past mission CHAMP, ongoing ESA mission Swarm, and simulations based on the NCAR TIEGCM model, we examine changes in the spatial pattern of the WSA‐like anomalies, which could be linked to long‐term changes in the geomagnetic field. A series of simulations provides theoretical analysis of changes in the morphology of the WSA on time scales longer than several decades. Numerical analysis shows that from the time when the WSA was discovered (around 1960) till present, maximum of the WSA has migrated by approximately 7° in longitude towards the Pacific Ocean, showing clear westward drift, consistent with temporal evolution of the geomagnetic dipole component. Key Points: Numerical reconstruction of the WSA is derived with the TIEGCM modelTwo LEO satellite missions are used for determining and tracking maximum of the WSAThe WSA exhibits westward migration towards the Pacific Ocean [ABSTRACT FROM AUTHOR]