A historical and research perspective of the life cycle of extratropical cyclones: observations and high-resolution numerical simulations (Invited Presentation)

This lecture opens with an overview of the emergence of modern conceptualizations and the dynamical prediction of the structure and life cycles of extratropical cyclones and their internal frontal and associated precipitation systems at Vilhelm Bjerknes' Leipzig Geophysical Institute (1913-1917) and the Bergen Geophysical Institute (1918-1922). We present: i) the recently discovered unpublished analyses that formed the basis for the Bergen School conceptual models of extratropical cyclones by J.Bjerknes, H.Solberg and T. Bergeron; ii) the Leipzig school contribution to development of quasi-geostrophic theory and its application to graphical numerical diagnosis and numerical prediction by T. Hesselberg and H. Sverdrup. We next revisit the 1989 ERICA IOP-4 extratropical cyclone life cycle through a high-resolution (3-km) simulation with the NCAR/WRF-ARW regional prediction system. This simulation illustrates the Thor Bergeron, and Shapiro-Keyser extratropical warm-core seclusion process.