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Revista Brasileira de Geofísica

Print version ISSN 0102-261X

Abstract

ABDOULAEV, Sanjar et al. Analysis of mesoscale system using cloud-to-ground flash data. Rev. Bras. Geof. [online]. 2001, vol.19, n.1, pp.75-95. ISSN 0102-261X.  http://dx.doi.org/10.1590/S0102-261X2001000100006.

Time-Integrated Cloud-to-Ground Lightning Field (TILF) are used as a source to diagnose the structure and evolution of mesoscale rainfall systems observed by radar and satellite during cold front movement (16 cases) and local cyclogenesis (9 cases) southward of Brazilian and South Atlantic Ocean. The major cloud-to-ground lightning events are associated with local cyclogenesis, when hourly registered number of flashes is four times greater than frontal cases. Building the TILF with time intervals of 0.5 to 2 hours and superposed one by one, using appropriated color-coded display, are determinate as following: a) direction and velocity of cold fronts, showing narrow bands or not accentuates arcs; b) warm and cold sections of fronts associated with cyclones and cyclonic waves, showing their convex and concave shape; c) developing and dissipating convection having same characteristics on satellite image, but different form of TILF and preferential flash polarity. The analysis of 37 mesoscale systems classified using 6 morphologic types of radar echoes, indicated that lightning rate have periodic oscillation during system evolution, increasing with extent of height of 30 dBZ towards negative temperatures. The area of systems with echoes >30 dBZ, reflectivity cores more than 50 dBZ and 30 dBZ at height greater than 7.5 km, have flash density more than 0.025 flashes .h-1.km-2. The lightning rates of linear and nonlinear severe storm or moderate bands accompanied by large stratiform regions are stronger than others.

Keywords : Cloud-to-ground flashes; Radar; Satellite; Mesoscale systems on fronts; Cyclones.

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