Priority 1: Exploring Atmospheric, Earth System, and Solar Processees, Variability and Change

Space Weather

Background

The NCAR program in space weather seeks to understand and ultimately predict disturbances in near-Earth space and the upper atmosphere that are caused by solar events and variability.

Understanding space weather is important for human space flight, especially beyond Earth orbit, because of the high-energy radiation hazards. It is also a key factor in satellite design and tracking because of the effects of radiation on computer circuits and power systems. Geomagnetic storms disrupt communications and navigation systems, which, together with increased radiation danger, are particularly important for aviation on polar routes, where protection from the magnetosphere is less and the effects of auroral activity are greatest. Acquiring a predictive capability for the most severe events, even if with short lead-time and approximate specificity, is a primary goal of the national space weather program.

This research activity is complex. Time scales range from minutes to decades with a variety of phenomena such as:

• the solar magnetic cycle,
• eruption of magnetic flux in active regions and sunspots,
• coronal mass ejections,
• solar ultraviolet irradiance,
• flares,
• solar energetic particles,
• interplanetary magnetic field,
• radiation belt dynamics,
• geomagnetic storms,
• ionospheric disruptions, and
• changes in upper atmosphere density, composition, and chemistry.

Some of these phenomena are well understood and can be described using numerical models of the space environment; in other areas scientists are pursuing fundamental advances to understand the physical processes involved.

Progress

NCAR researchers have made exciting advances in space weather prediction this year. Mausumi Dikpati and colleagues have published a paper that documents their significant progress in understanding the 11-year solar cycle and predicting its future magnitude. Dikpati and her colleagues developed a flux-transport model of the solar interior dynamo to describe the transport and re-cycling of magnetic flux that causes the seemingly random variation of the cyclical intensity. These predictions are now being used to drive calculations of future thermospheric density, superimposed on the gradual cooling and contraction of the upper atmosphere caused by increasing CO2 levels.

At the other end of the time spectrum, Yuhong Fan and Sarah Gibson have made significant progress in detecting the precursors and modeling the processes involved in sudden eruptions of magnetic flux into coronal mass ejections. Using 3D magnetohydrodynamic simulations of twisted flux tubes emerging into the corona, it is now possible to measure the resulting perturbations 30 to 60 minutes before they arrive at the Earth. Researchers use coupled models to describe the resulting geomagnetic storms and thermosphere/ionosphere disturbances. These models were developed by collaborative efforts between NCAR and university researchers.

NCAR scientists are pursuing future developments that will allow solar observations to drive realistic models of the corona and solar wind. Scientists intend to use these models as input to geospace models but to do so will require better understanding and measurement of the behavior of the solar magnetic field in the corona. To address these problems, NCAR, the University of Hawaii, and the University of Michigan, are designing a new large coronagraph, the Coronal Solar Magnetism Observatory (COSMO) described in the next section.

Plans

NCAR researchers are making important contributions for community modeling development through participation in the Center for Integrated Space weather Modeling (CISM), a NSF Science and Technology Center led by Prof. W. Jeffrey Hughes at Boston University, This activity also supports coupled model development for the NASA Living-with-a-Star program. Based on previous work in collaboration with researchers at Dartmouth College, Boston University, the University of Maryland, and Rice University, NCAR is providing a model that forms one of the core components of the physics-based numerical modeling chain being developed by the CISM program. It will be made available to the geoscience community through a collaboration with the Community Coordinated Modeling Center at NASA Goddard.

For further detail, please read the full project report linked below.

ESSL Annual Report