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MHD Heliosphere with Enhanced Background Solar Wind and Coronal Mass Ejections

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[Technical Report, Final Report]

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The modern technologies and infrastructure are highly vulnerable to space weather events, which are primarily driven by solar activity. Consisting of charged particles emitted by the Sun, the solar wind carries the Suns energy and magnetic field outward and interacts with the Earths magnetosphere. Therefore, modeling the propagation of the solar wind between the Sun and the Earth - including interactions between fast and slow streams and transients such as coronal mass ejections CMEs - is a significant component of space weather research, which directly relates to a DoD mission to develop operational models of the solar-terrestrial system.Our main objective is to improve the quality of our heliospheric simulations by building on the strengths of the Wang-Sheeley-Arge WSAEnlil model, which NOAA currently uses for operational forecasts of the solar wind and CME propagations to Earth, and therefore to enhance the capability of making reliable predictions of the solar wind conditions at Earth. We will accomplish our goal by developing a three-dimensional magnetohydrodynamic MHD solar wind model of higher accuracy with time-dependent boundary conditions from the WSA model and ground-based observations. We emphasize that we will estimate the density and temperature for theambient solar wind at the inner boundary of the heliospheric MHD model from empirical correlations with velocity based on spacecraft data instead of using ad hoc prescriptions as currently done by WSA-Enlil. The proposed work will result in a new heliospheric model consisting of two major components a Improved ambient solar wind structure based on WSA maps and b Propagation of CMEs to Earths orbit as flux ropes, which are more realistic than the Cone CME model employed by WSA-Enlil. We will evaluate our model for certain historical CME events by comparing with the current operational model e.g., WSAEnlilCone and with in situ measurements at Earths orbit.

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[A, Approved For Public Release]