The precipitous decay in the intensity of the Earth's dipole magnetic field since 1840 is a robust feature defined by magnetic observatory data. The drop is related to a low magnetic intensity region called the South Atlantic Anomaly, which may be driven by the growth of a prominent reversed magnetic flux core patch off the coast of South Africa. The magnetic dipole history prior to the era of modern observatory measurements is uncertain because of the near lack of archeomagnetic data from the Southern Hemisphere. A paleointensity record of the geomagnetic field for the Southern Hemisphere is potentially held in Iron Age (300 to 1800 AD) ceramics of southern Africa. The Paleomagnetism Research Group at the University of Rochester is analyzing this record. They are combining these paleointensity data with magnetic directions obtained from analyses of oriented archeological materials and other field strength measures using a new technique (the analysis of single grain pottery temper). The ultimate goal of the project is to use the new magnetic records to test geomagnetic field models and contrasting interpretations of the long-term nature of the modern dipole decrease. A Southern Hemisphere archeomagnetic record is of interest to a broad range of scientists, ranging from those studying processes active in the Earth?s core to those interested in the efficiency of magnetic shielding from solar energetic particles. The investigation involves international collaboration with South African archeologists and geologists. The work incorporates graduate and undergraduate student studies and a small number of K-12 activities. The latter integrate the teaching efforts of the University of Rochester Paleomagnetism Research Group with the Rochester community. Outreach activities also include dissemination of the research results in South Africa. This award is co-funded by NSF's Geophysics Program and the Office of International Science and Engineering.
