Reconnection-Driven Evolution of Polar Cap Boundaries: Investigating Timescales of Expansion, Contraction, and Steady-State

The primary focus of this study is to characterize the time scales associated with polar cap boundary evolution, specifically the duration required for the boundary to reach its maximum and minimum expansion radii and subsequently restabilize. By establishing time thresholds that delineate boundary changes driven by dayside and nightside reconnection, this research advances our understanding of large-scale magnetic reconnection dynamics and their associated temporal characteristics. To achieve this, we analyze spatial and temporal variations in polar cap boundaries, the open field line magnetic flux within these boundaries, and key variables that serve as both responses and drivers of reconnection. Region 1/Region 2 (R1/R2) current mapping from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) and geomagnetic field data from NOAA’s Geostationary Operational Environmental Satellites (GOES) are examined as direct responses to reconnection. Additionally, solar wind parameters from the OMNI2 database are incorporated to investigate the drivers of reconnection in relation to polar cap boundary dynamics, specifically size and location changes. This analysis provides insights into large-scale reconnection dynamics and its associated temporal characteristics, contributing to broader understanding into magnetospheric response timescales.