In this study an attempt is made to investigate the upper-tropospheric downstream development over north-west Europe, which leads to surface cyclogenesis in the central Mediterranean. A case study is analysed to demonstrate that the upper-tropospheric downstream development could be closely related to the upper-tropospheric frontogenesis that appears upon the north-eastern flank of a blocking high. The frontogenesis is characterised by a jet streak within a strongly baroclinic zone and a tropopause folding associated with cold stratospheric air intrusion into the troposphere. According to this interpretation, the eddy ageostrophic divergence of eddy geopotential fluxes (dispersion and spreading of eddy kinetic energy), other than friction dissipation and barotropic conversion to the mean flow, is mainly responsible for the loss of kinetic energy from a decaying depression of synoptic scale that has passed the mature stage. This dispersed eddy kinetic energy accumulates in the vicinity of the aforementioned jet streak where it is transferred downstream and further triggers the generation or rejuvenation of a new disturbance.

National and international authorities recommend a variety of air- quality standards that should not be exceeded in local and regional scales currently. With this work a uniform indexing scale is introduced which characterises several urban pollutants in a simple and comparable manner. The ’indicators’ proposed are implemented at the Athens Metropolitan Area (AMA) which is an area with serious pollution problems. Hourly data from all available monitoring stations are analysed during 1983 and 1995. This analysis demonstrates that the status of air quality in Athens can be characterised as acute with regards to photochemical pollutants while strong spatial and temporal variability is encountered for all pollutants. National and international authorities recommend a variety of air-quality standards that should not be exceeded in local and regional scales currently. With this work a uniform indexing scale is introduced which characterizes several urban pollutants in a simple and comparable manner. The ‘indicators’ proposed are implemented at the Athens Metropolitan Area (AMA) which is an area with serious pollution problems. Hourly data from all available monitoring stations are analyzed during 1983 and 1995. This analysis demonstrates that the status of air quality in Athens can be characterized as acute with regards to photochemical pollutants while strong spatial and temporal variability is encountered for all pollutants.

Studies 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 quasi-Lagrangian 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 framework 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 Eularian 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.