The Role of Latent Heat Release in Explosive Cyclogenesis
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
Pagination or Media Count:
Extratropical cyclones and their attendant fronts are the primary cause of day to day weather changes at any given location in middle and higher latitudes. Storms that deepen at least 24 mb in a period of 24 hours or less are rapid developing storms. This research attempts to analyze the role of latent heating in explosive cyclogenesis, using the Sutcliffe Development Equation SDE. The SDE describes cyclone development in terms of absolute vorticity advection, thickness advection, stability, and latent heating. The basic premise to be tested is that latent heating, including stable and convective components, plays a significant role in the rapid development of extratropical cyclones. The Sutcliffe Equation Analysis Model SEAM, developed to study these storms, uses a grid of 27 points x axis by 18 points y axis with a spacing of 190.5 km. Verti- cal resolution in the SEAM consists of 19 levels from 1000 mb to 100 mb in 50 mb increments. The model atmosphere extends to 100 mb to accommodate moisture convergence and subordinate parameters needed to calculate latent heating, which is parameterized into two basic types stable and convective latent heat release. Stable latent heat release SLHR is a large scale effect while convective latent heat release CLHR is a sub-grid scale effect. Analysis of results show that CLHR values were virtually non-existent in the normal case and very small in the bomb case. Comparison of Sutcliffe values and storm tracks show that areas of positive values downstream of the surface center indi- cate movement of either type of storm. The explosive storm followed along the Sutcliffe value ridge, while the normal storm moved perpendicular to the ridge.