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Solar Transients and Space Weather (STSW)

Science Highlights

Investigate the Onset and Development of Magnetic Flux Transport through the Chromosphere, and the Impact of its Short-term Variability on the Sun-Earth System

What drives the magnetic, thermal, and radiative phenomena of the mid-solar atmosphere that affect the Sun-Earth system on timescales of days or shorter? Convective flows and the continuous emergence of magnetic flux from the solar interior relentlessly force the magnetic and thermodynamic environment at the base of the Sun-Earth system. The chromosphere, a highly structured, partially ionized plasma forming the boundary layer between the solar photosphere and corona, is a conduit through which all of the energy that drives the Sun-Earth system must pass. The chromosphere offers a unique opportunity to understand, and quantify, the response of the outer solar atmosphere to this forcing, and through its study we may develop a deeper physical understanding of the persistent radiative and particulate input into the Sun-Earth system. By necessity, observation, theory, and modeling efforts must work in concert to unlock the fundamental mysteries of the heliosphere's complex inner boundary. In confronting this frontier, HAO will form partnerships with the broader community on all aspects of the initiative with the expectation that the mutual scientific return will benefit all, thus filling a crucial void in our current observational knowledge of processes driving the short-term forcing of Earth's atmosphere.

The envisioned effort will engage HAO staff with those from other divisions of NCAR (specifically CGD, ACD, CISL) and the broader university community in a cross-disciplinary program to investigate the impact of short-term solar variability on the Sun-Earth system. We will interact with the community through a series of focused workshops to develop the comprehensive observing and modeling systems needed to monitor and understand the influence of the radiative and particulate input to the Earth's dynamic atmosphere as forced by the Sun's ever-evolving magnetism. Specific tasks are:

• Develop and deploy wavelength-diverse spectro-polarimetric instruments to monitor the four-dimensional (space+time) evolution of the magnetic field at the inner boundary of the Sun-Earth system, and to provide essential observational context for the modeling and theoretical efforts.
• Research diagnostics for the remote sensing of magnetic field vectors in highly dynamic plasmas, develop the associated inversion tools, and make them available to the community through the CSAC.
• Advance models of magnetic flux emergence through the outer solar atmosphere with increased realism in the physical description of magnetized plasmas and their interaction with radiation.

A "gap" exists in our observational understanding of the solar atmosphere. That gap is widely recognized as the magnetic and thermodynamic environment of the chromosphere. Recent advances in instrumentation and simulation are advancing at a rapid pace such that an effort to pursue this frontier activity is both timely and practical. Resources exist within NASA, NSF, and DoD research programs to perform the effort outlined above.