11th Conference on Atmospheric Radiation and the 11th Conference on Cloud Physics

Wednesday, 5 June 2002
Observations of droplet concentration and spectrum shape variability in Amazon clouds
Antônio Carlos Santana dos Santos, Universidade Federal do Ceará, Fortaleza, Brazil; and A. A. Costa and J. C. P. de Oliveira
Poster PDF (260.6 kB)
Microphysical variables such as droplet concentration and size distribution influence precipitation formation and cloud radiative properties, therefore cloud microphyisics has great importance in possible feedbacks regarding climate change. Several authors investigated the variability in droplet concentration and/or size from both observations (Hill e Choularton, 1985; Austin et al., 1985; Twohy e Hudson, 1995; Oliveira, 1998; Costa et al, 2000a, etc.) and modeling (Brenguier and Grabowski 1993; Grabowski 1993, Costa et al., 2000b, etc.). In this work, cloud microphysics data collected during the Tropical Rainfall Measuring Mission / Large-Scale Biosphere-Atmosphere Experiment in Amazonia (TRMM/LBA) were analyzed. The instrumented aircraft performed several flights over the region, including the 23 January 1999 flight, in which it penetrated a cloud system and an isolated cell. Using the hydrometeor distribution-function data, cloud regions were classified according to the concentration and spectrum shape variability in 4 different types. The occurrence of regions with more or less variability was investigated and significant differences were found between the system and the isolated cell, as well as between convective and stratiform parts. Particularly, minumum variability was found in stratiform regions of the cloud system whereas maximum variability was found in the isolated cell and in the convective regions of the cloud system, indicating the role of entrainment and turbulence in generating inhomogeneities in clouds.

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