Comparisons of the Amazon and Congo River Basins: Hydrology, Fire, Thermodynamics and Lightning
Earle
Williams, Massachusetts Institute of Technology, earlew@ll.mit.edu
(Presenting)
Gabriella
Satori, Geodetic and Geophysical Institute, Hungarian Academy of Sciences,, Sopron, Hungary,, satori@ggki.hu
The Amazon and Congo River basins are largely covered with tropical rainforest at similar geographical latitudes, and on this basis are expected to respond nearly identically to sunlight. Yet optical observations of lightning from space now underway for several years with the NASA Optical Transient Detector and Lightning Imaging Sensor have established a predominance of lightning flash density (flashes/km2/yr) for the Congo, larger by a factor of 2.8 than that in the Amazon. Considerations are given to differences in rainforest canopy properties, hydrology, aerosol and thermodynamics to account for this substantial contrast. Surface station observations are organized to compare the mean basin elevation, the potential temperature, the relative humidity, the diurnal temperature range, the number of sunshine hours, the leaf area index and the number of aerosol-producing fires. It is concluded that the Congo is more continental than the Amazon, primarily because of its more elevated terrain, and its slightly hotter and drier surface conditions. These thermodynamic conditions promote stronger updrafts in cumulonimbus convection in the Congo, which in turn amplify the electrification process responsible for lightning.
Submetido por Lorena Cordeiro Brewster em 01-ABR-2004