Within heliophysics, space weather is the newest field and also the field most pertinent to life and technology. The most explosive space weather originates as solar eruptions, producing myriad secondary effects as they propagate through the heliosphere. When these events approach Earth’s magnetosphere, inducing geomagnetic storms (GSs), they can wreak havoc on humans, spacecraft, and instruments. Determining how and when these adverse effects occur, and ultimately mitigating them, is a key goal of heliophysics today. Much is at stake: Society depends increasingly on vulnerable satellite-based technologies (e.g., GPS and cell phones), and electric power grids can be severely damaged by ground-level magnetic changes. Chigomezyo Ngwira is combining theory, modeling, and data analysis in novel ways to make progress on this urgent problem.
Chigo’s work has been focused on the critical ground-level effects of solar eruptions: geomagnetically induced currents (GICs). As the magnetosphere is reconfigured by an eruption, the current system from the ionosphere to the surface is altered, inducing large currents in wires and associated power grid equipment. At worst, portions of the grid could be disabled, straining the resources of hospitals, data farms, and other critical facilities. The scientific foundation required for comprehensive understanding of GICs became available only recently, thanks largely to Chigo and his colleagues.
Chigo has made great strides on two crucial fronts: (1) GICs at middle and southern latitudes, locations earlier thought not to be threatened by GSs, and (2) impacts of extreme GSs and GICs based on historical events and state-of-the-art simulations of the near-Earth response to extreme solar eruptions. In “Improved Modeling of Geomagnetically Induced Currents in the South African Power Network,” Chigo and colleagues showed, for the first time, that significant GICs could occur in the South African grid during major GSs. This pioneering work launched major GIC activities in South Africa.
In “Simulation of the 23 July 2012 Extreme Space Weather Event: What if This Extremely Rare CME Was Earth Directed?,” Chigo and colleagues used advanced models to study, for the first time, the GIC activity that such a well-observed extreme event would cause if aimed at Earth. In “Modeling Extreme ‘Carrington-Type’ Space Weather Events Using Three-Dimensional Global MHD Simulations,” he and his coauthors predicted maximum possible GIC amplitudes and revealed impacts at latitudes much farther south than expected.
Chigomezyo Ngwira’s research is a prime example of how science directly benefits society worldwide, through better understanding of natural hazards and improved preparedness for extreme events. His results not only guide U.S. policy decisions now but also manifest enormous potential for guiding energy policy in the developing world.
—Judith T. Karpen, NASA Goddard Space Flight Center, Greenbelt, Md.
The 1859 Carrington event is the most intense geomagnetic storm in recorded history, and the literature provides numerous explanations for what dro...