Paleomagnetic Secular Variation within the Pacific Ocean Basin for the Last 3000 Years

Eighteen composite paleomagnetic secular variation (PSV) records (from eight distinct regions) spanning the last 3000 years have been compiled for the Earth's hemisphere containing the Pacific Ocean Basin (POB). These records almost completely surround the POB and include one record (Hawaii) from the middle of the POB. Seven of these composite records (from five distinct regions) also have associated paleointensity records. These true vector data sets are compared with recent spherical harmonic models developed by Constable et al. (2000) and Jackson et al. (2000) to assess the spatial and temporal scale-lengths of total field variability that caused the observed PSV. Previous studies suggest that PSV is spatially coherent (strongly correlated) only over scale-lengths of 4000 km or less. Comparison of the PSV records and spherical harmonic models, however, suggests that the spatial scale-length of field variability in the POB that causes individual PSV features is much larger than that, virtually spanning the POB. However, that pattern is not predictable from knowledge of PSV records in only one region of the POB. Two alternative models are evaluated that might drive the entire pattern of PSV in the POB: movement of high-latitude flux lobes (now located in Siberia and northern Canada) or poleward dynamo wave propagation. High-latitude flux-lobe motion or poleward moving dynamo waves can both account for PSV in the Northern Hemisphere. Neither model, however, can account for variability in both the Northern and Southern Hemisphere at the same time.