Quasi‐lagrangian energetics of an intense mediterranean cyclone

Abstract

SUMMARYStudies of the energetics of synoptic-scale systems and similar kinds of investigation have traditionally used a Eulerian framework. In this study, the energetics of a synoptic-scale system have been considered using a quasiLagrangian method, in order to isolate the disturbance under consideration within a volume which moves together with the system at each stage of its development.Applying a Lagrangian framework implies that the dimensions of the computational area can be modified on the basis of predetermined criteria. In this study, an area surrounding a depression as shown on the surface analysis, has been selected. This area moves together with the centre of the depression. The energetics results obtained using such a quasi-Lagrangian scheme are compared to those obtained by using a Eulerian framework.The synoptic-scale system studied here is a wintertime frontal depression, the greatest development of which occurred in the central Mediterranean on 7 December 1991. This depression moved east accompanied by significant temperature changes, heavy precipitation and gale force winds.

On the dynamics of a case study of explosive cyclogenesis in the Mediterranean

“…Actually, the transient barotropic growth seems to result in the development of the upperlevel baroclinic wave at 05/18 UTC and the subsequent explosive development. In agreement with this mechanism, Michaelides (1992) and Michaelides et al (1999) demonstrated that barotropic energy conversions are connected with intense cyclogenesis in the Mediterranean at least in the early stages of development. It should be noted that the radical change from a ''leaf'' of cold thick multi-layered clouds to a ''comma'' cloud configuration on the IR images and the dark area below the head of the ''comma'' on the WV images during the period between 06/00 UTC and 06/06 UTC (see Fig.…”

A 40‐year climatological study of relative vorticity distribution over the Mediterranean

“…The important role of the upper level forcing in low level development was stressed in previous studies of cyclogenesis in the central Mediterranean (e.g. Karein, 1979;Prezerakos et al, 1997;Michaelides et al, 1999). Minor maxima appear at 850, 700 and 500 hPa.…”

The energy cycle and structural evolution of cyclones over southeastern South America in three case studies

“…When the energy budget equations are applied to a limited area of the atmosphere it is necessary to define the computational domain. This can be done by means of either an Eulerian or a quasi‐Lagrangian scheme [ Starr , 1945; Johnson and Downey , 1975; Michaelides et al , 1999]. Following Michaelides et al [1999], the Eulerian scheme (carried out within a fixed volume in space) has disadvantages when utilized for individual systems, which are characterized by time evolution and mobility.…”

“…This can be done by means of either an Eulerian or a quasi‐Lagrangian scheme [ Starr , 1945; Johnson and Downey , 1975; Michaelides et al , 1999]. Following Michaelides et al [1999], the Eulerian scheme (carried out within a fixed volume in space) has disadvantages when utilized for individual systems, which are characterized by time evolution and mobility. On the other hand, the quasi‐Lagrangian scheme (volume moving with the position of the system center) is a more practical approach to study systems with high mobility, where it focuses on the disturbance itself.…”