Magnetic reconnection at earth's magnetopause has been predicted to occur in a variety of configurations - for example, where the magnetosheath magnetic field is most closely antiparallel to that of…

This is a $486,855 grant awarded by the National Aeronautics and Space Administration (NASA) to Trustees of Boston University, a private university in Boston, Massachusetts. The purpose of the grant is to test several models that predict the location of magnetic reconnection at the Earth's magnetopause, the boundary between the Earth's magnetic field and the solar wind. The work will involve comparing the model predictions against in-situ data to gain insight into the global processes governing magnetopause reconnection, which has applications in space science, mission planning, and interpreting measurements. This grant does not have a set-aside designation and is intended to support research activities with an ultimate completion date of July 21, 2025.

Magnetic reconnection at earth's magnetopause has been predicted to occur in a variety of configurations - for example, where the magnetosheath magnetic field is most closely antiparallel to that of the magnetosphere, or where a plasma parameter like exhaust velocity is extremized. These predictions, combined with plasma parameters and jump conditions at the magnetopause, yield global models of the location of so-called x-lines where reconnection occurs, typically parametrized by solar wind conditions and geomagnetic activity. Such models have been used to establish new science, plan magnetosphere missions, and provide context for in-situ measurements, but to date the efforts to verify and compare them have been largely limited to case studies and global MHD simulations. Different predictions arise from different theories of the large-scale physics governing magnetopause reconnection, so determining the accuracy of the resulting x-line models would give insight into global processes that could not be obtained from in-situ measurements alone. The proposed work will test several x-line predictions against in-situ data: the maximum magnetic shear model [trattner+ 2007], bisection of the local fields [moore+ 2002], the maximum exhaust speed model [swisdak and drake, 2007], and the maximum reconnecting field energy model [hesse+ 2013].