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Sunlight effects on diel CO2 and CH4 emissions from a tropical reservoir

Current studies show that reservoirs are responsible for emissions of greenhouse gases (St. Louis et al. 2000, Duchemin et al. 2002, Soumis et al. 2004, Abril et al. 2005, Lima et al. 2008). Surface waters of aquatic ecosystems exhibit supersaturated dissolved CO2 (Cole 1999, Richey et al. 2002) bec...
  • por Portal Padrão
  • publicado
  • 26/04/2009
  • 1:06 PM

Positive leader characteristics from high-speed video observations

Based on analyses of high-speed video recordings of cloud-to-ground lightning in Brazil and the USA, the characteristics of positive cloud-to-ground (+CG) leaders are presented. The high frame rates permitted the average, 2-dimensional speeds of development along the paths of the channels to be reso...
  • por Portal Padrão
  • publicado
  • 23/08/2008
  • 3:43 PM

On the sensitivity of cloud-to-ground lightning activity to surface air temperature changes at different time scales in São Paulo, Brazil

This paper presents a study about the sensitivity of cloud-to-ground (CG) lightning activity to changes in surface air temperature at daily, monthly, yearly, and decadal timescales in the city of São Paulo (Brazil). Lightning data collected in the city by the Brazilian Lightning Detection Network (...
  • por Portal Padrão
  • publicado
  • 23/08/2008
  • 3:42 PM

First versus subsequent return-stroke current and field peaks in negative cloud-to-ground lightning discharges

We examine relative magnitudes of electric field peaks of first and subsequent return strokes in negative cloud-to-ground lightning flashes recorded in Florida, Austria, Brazil, and Sweden. On average, the electric field peak of the first stroke is appreciably, 1.7 to 2.4 times, larger than the fiel...
  • por Portal Padrão
  • publicado
  • 23/08/2008
  • 3:41 PM