Day 4

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Paper title Coordination of ground based and in orbit multipoint measurements: comparison of magnetospheric and ground currents
  1. Malcolm Dunlop Beihang University Speaker
  2. Xiangcheng Dong STFC RAL Space
  3. Dong Wei Southern University of Science and Technology
  4. Xin Tan Beihang University
  5. Junying Yang Beihang University
  6. Chao Xiong Wuhan University, China
Form of presentation Poster
  • B2. Earth Explorer missions
    • B2.05 Swarm - ESA's Extremely Versatile Magnetic Field and Geospace Explorer
Abstract text The scaling of field-aligned current sheets (FACs) connecting different regions of the magnetosphere can be explored by multi-spacecraft measurements, both at low (LEO) and high altitudes. With the relation to (R1/R2) and (sub-)auroral boundaries (mapping to current distributions at the magnetopause and ring current and regions in between) such distributed current measurements can assist in future combination with SMILE data and are also enhanced by added LEO coverage, such as is planned with NanoMagSat. Individual events, sampled by higher altitude spacecraft (e.g. Cluster, MMS), in conjunction with Swarm or other LEO satellites, show different FAC scale sizes. Large and small-scale (MLT) trends in FAC orientation can also be inferred from dual-spacecraft (e.g. the Swarm A&C spacecraft). Conjugate effects seen in ground magnetic signals (dH/dt, as a proxy for GICs) and spacecraft (e.g. Cluster/Swarm) show intense variations take place in the main phase of a geomagnetic storm (e.g. cusp response) and during active substorms (e.g. driven by arrival of bursty bulk flows, BBF). The most intense dH/dt is associated with FACs, driven by BBFs at geosynchronous orbit (via a modified substorm current wedge, SCW). Previous demonstration of directly driven dB/dt by bursty bulk flows (BBFs) at geosynchronous orbit has been rare. In situ ring current morphology can be investigated by MMS, THEMIS and Cluster, using the multi-spacecraft curlometer method, and linked to LEO signals via R2-FACs and the effect on the internal geomagnetic field. These in situ measurements suggest the ring current is a superposition of a relatively stable, outer westward ring current, dominating the dawn-side, and closing banana currents due to a peak or trough of plasma pressure in the afternoon and night-side sectors (depending on geomagnetic activity). The transport relationship between these two banana currents via (R2) FACs can be investigated with spacecraft at LEO.