Genesis of Tropical Storm Eugene (2005) from Merging Vortices Associated with ITCZ Breakdowns. Part II: Roles of Vortex Merger and Ambient Potential Vorticity

In this study, the roles of merging midlevel mesoscale convective vortices (MCVs) and convectively generated potential vorticity (PV) patches embedded in the intertropical convergence zone (ITCZ) in determining tropical cyclogenesis are examined by calculating PV and absolute vorticity budgets with a cloud-resolving simulation of Tropical Storm Eugene (2005). Results show that the vortex merger occurs as the gradual capture of small-scale PV patches within a slow-drifting MCV by another fast-moving MCV, thus concentrating high PV near the merger’s circulation center, with its peak amplitude located slightly above the melting level. The merging phase is characterized by sharp increases in surface heat fluxes, low-level convergence, latent heat release (and upward motion), lower tropospheric PV, surface pressure falls, and growth of cyclonic vorticity from the bottom upward. Melting and freezing appear to affect markedly the vertical structures of diabatic heating, convergence, absolute vorticity, and PV, as well the production of PV during the life cycle of Eugene. Results also show significant contributions of the horizontal vorticity to the magnitude of PV and its production within the storm. The storm-scale PV budgets show that the above-mentioned amplification of PV results partly from the net internal dynamical forcing between the PV condensing and diabatic production and partly from the continuous lateral PV fluxes from the ITCZ. Without the latter, Eugene would likely be shorter lived after the merger under the influence of intense vertical shear and colder sea surface temperatures. The vorticity budget reveals that the storm-scale rotational growth occurs in the deep troposphere as a result of the increased flux convergence of absolute vorticity during the merging phase. Unlike the previously hypothesized downward growth associated with merging MCVs, the most rapid growth rate is found in the bottom layers of the merger because of the frictional convergence. It is concluded that tropical cyclogenesis from merging MCVs occurs from the bottom upward.

Questions from an analysis of ethnic distributions in the former Yugoslavia

Ethnic diversity in the former Yugoslavia, measured as informational entropy increased in most regions at the level of the naselje, the opstina, and the region, 1961-1991 (no useful data for Slovenia, Macedonia, and Kosovo in 1991). Vojvodina is the most diverse region, Slovenia the least. An exception to the increase is Kosovo-Metohija, where diversity decreased 1961-1981 driven by already serious interethnic conflict. There is some diminution of the increase in diversity in some regions in 1991, possibly because of refugee flows in anticipation of the impending violence. This rather broad and steady increase in diversity leads to questions about the view that pre-existing ethnic hatreds among broad segments of the population led to the ethnic fracturing and collapse of Yugoslavia. Instead it suggests that this fracturing may instead have been the result of competition between political leaders, stimulated by serious economic difficulties, leading them to emphasize ethnicity in their search for popular support. From this the authors support the view that the collapse of Yugoslavia was from the top downward, not from the bottom upward.

Stratigraphie du Paleozoique de la zone axiale pyreneenne a l'E de l'Ariege

The Paleozoic section in the axial zone of the Pyrenees east of the Ariege, France, consists, from the bottom upward, of the Canaveilles series of interbedded graphitic schists, limestones, and metavolcanics (attributed to the Cambrian), the more homogeneous Jujols schists (lower and middle Ordovician), dated Ashgillian and Gotlandian (Silurian) schists and fossiliferous limestones, grading upward into undifferentiated lower Devonian beds, gray massive middle Devonian limestones, diversified upper Devonian formations, and a zone of transgressive Dinantian (Carboniferous) beds which forms the transition to shaly Visean so-called Culm deposits.