Showing papers on "Convective available potential energy published in 1989"

A Mesoscale Convective Complex-Generated Inertially Stable Warm Core Vortex

Abstract: A long-lived mesoscale convectively-generated vortex (MCV) associated with a mesoscale convective complex (MCC) is documented. The MCV, with a Rossby number of approximately 0.5, is investigated as a feature intrinsic to the organization of the MCC. On 6–7 July 1982 a particularly large and intense MCC developed in a region of high convective available potential energy (CAPE) but weak vertical wind shear (bulk Richardson number ∼150), and weak advection of temperature and vorticity. Convection initially was organized in a narrow line with elements propagating relative to the mean environmental flow. These elements subsequently developed a large semicircular area of stratiform precipitation and a surface mesolow to the rear. Heavy rain fell over a broad area; amounts as great as 10.9 cm accompanied by flooding were reported in central Oklahoma. As the large semicircular rain area dissipated, a three layered structure became evident: a large upper tropospheric anticyclone, a rain cooled mesoscale h...

Numerical Simulation Of Sea Breezes with Vertical Wind Shear during Dry Season at Cape of Three Points, West Africa

Abstract: The airflow over Cape of Three Points (Gulf of Guinea: 4.5°N, 2°W) has been simulated using a three-dimensional mesoscale model in order to investigate the sea breeze developing in synoptic vertical wind shears during the 1979 dry season. Two different meteorological situations, characterized by two contrasted wind profiles between 500 and 2000 m have been studied, with two types of transitions between the lower circulation (SW monsoon) and the upper African easterly jet (AEJ). The first one is a veering case (6 January) and the second is a backing case (23 January). Calculations of CAPE (convective available potential energy) show that whereas instability is a maximum at both sides of the cape, the site of enhanced convection is determined by the wind shear in the 500–2000 m layer. Numerical results confirm satellite observations.

Analytical Models of Narrow Cold-Frontal Rainbands and Related Phenomena

Abstract: Simplified versions of the steady analytical models of density current developed by Moncrieff and So are shown to represent archetypes of cold-frontal rainbands (NCFRs) by making comparisons with the limited amount of published observational data that describe the phenomena. An overturning (or in a special case, stagnation) of the upper-level, system-relative flow of ahead of the rainband and vortidty within the cold air are important effects not included in conventional density current dynamics. The bands conserve mass energy and domain-averaged total momentum flux and involve a balance between inertial and pressure gradient effects. This is distinct from a semigeostrophic mechanism that requires a base-state baroclinity and an ageostrophic adjustment towards thermal-wind balance. The theory also represents two-diimensional squall lines in the limiting cam when the convective available potential energy is negligible so squall lines could, in principle, be maintained solely by the kinetic energy ...