Identification of spacecraft conjunctions in the cusps Original Research Article

The comparison of particle energy distributions from different altitudes in the cusp is important for developing our understanding of magnetospheric entry and energization processes. The Cluster multi-spacecraft mission allows the opportunity to better understand the features at higher altitudes, facilitating direct comparisons with concurrent low-altitude observations by one or more of the DMSP spacecraft. A simple technique has been developed to search orbit and particle data from both missions for near-simultaneous cusp region crossings using model magnetic field line tracing and the Altitude Adjusted Corrected Geomagnetic (AACGM) coordinate system. This method can quickly search large periods of time and give an indication of the quality of the magnetic conjunctions through automatically generated plots. This technique can also be applied to other regions and spacecraft (e.g., inner magnetospheric observations by NASA Living with a Star (LWS) geospace missions). Examples of two types of conjunctions between Cluster and DMSP are presented, along with a brief description of how these methods provide insight into the temporal and spatial evolution of plasma in the cusp regions.