Geomagnetic Storms Impact Terrestrial Weather
It has long been a mystery why small Total Solar Irradiation (TSI) changes have significant effects on Earth’s climate. Solar cycle correlation studies abound but cannot conclusively point to a viable physical mechanism. Here, I show that geomagnetic storms have a profound terrestrial weather impact. Using 67 years of hourly Disturbance storm time (Dst) index and ERA5 reanalysis atmosphere data over North America, I find geomagnetic storm impacts up to two orders of magnitude larger than the long-term global mean surface temperature impact attributed to solar activity. The effects vary depending on region and season. Comparing with solar cycle studies shows that the solar cycle variations are more likely caused by storm-time solar activity bursts as opposed to slow continuous variations, such as the solar cycle scale TSI variations. As for the physical mechanisms, particle precipitation effects such as from cosmic rays, solar energetic particles, or magnetospheric electrons are least consistent with my results. In particular, the cosmic ray – cloudiness hypothesis is falsified. A top-down mechanism operating directly through the ionosphere or through stratospheric chemistry and the polar vortex appears to be more
likely.
Jimmy Raeder earned his Ph.D. in Geophysics from the Universität zu Köln n 1989 under Prof. F. M. Neubauer. His early work included the ESA/GIOTTO mission's magnetic field experiment during its 1986 Halley's Comet flyby. He spent over a decade at UCLA's IGPP pioneering global MHD simulations of Earth's magnetosphere before joining the University of New Hampshire in 2003, where he became Professor (2009) and later Professor Emeritus (2021).
At UNH, Raeder developed OpenGGCM, a widely used community geospace model deployed at NASA/GSFC CCMC, and served as a Co-Investigator on NASA's THEMIS mission. He has published 157 refereed papers (6,000+ citations), including influential Nature Communications studies on Kelvin-Helmholtz waves at Earth's magnetopause (2015, 2023). His honors include NASA Group Achievement Awards, the ESA Cluster Outstanding Contribution Award, and Sigma Xi Fellowship, alongside leadership roles chairing the NSF/GEM Steering Committee and mentoring more than 2 dozens of graduate students and post-docs.