Variability in Planetary Wave Activity over the 20th Century
The contrasting geographies of the Southern and Northern hemispheres play a significant role in the observed planetary wave regimes. In addition to differences in the continental distribution and the location of major north-south mountain chains, the mean equator-to-pole temperature difference is significantly larger in the Southern Hemisphere (around 70 K) than in the Northern Hemisphere (around 40 K). As such, the evolving nature of these wave regimes have been extensively studied in climate models and re-analyses. Planetary wave amplitude is a challenging quantity to derive from global data sets compared to parameters such as the speed of the jet stream or the planetary wavenumber. In this study, the evolution of planetary wave amplitudes over the 20th Century are analyzed using a novel implementation of the quasi-geostrophic wave activity parameter. The trajectories of change are distinctive between the hemispheres and can be linked to sea ice properties.
Dr. Lynch is a Professor of Earth, Environmental and Planetary Science at Brown University and Director of the Institute at Brown for Environment and Society. Her research focuses on polar climate modeling, indigenous environmental knowledge, and climate policy analysis.