Microphysical Observations of Tropical Clouds

Abstract

The results from airborne in situ sampling of convective tropical storms in the Amazon and Kwajalein are presented. Three cases from the Amazon and two from Kwajalein are compared and provide examples of the much larger dataset that was obtained from field campaigns in these two regions during 1999. The strength of the updraft was a major factor in determining the microphysical characteristics of hydrometeors. Weak updrafts exhibited a well-developed warm rain process by the time droplets had reached the freezing level. Stronger updrafts (>5 m s?1) contained smaller droplets or ice particles at cloud midlevels than regions with the weaker updrafts. Significant supercooled liquid water was found only at temperatures warmer than ?12°C, although traces of liquid water were observed at temperatures as cold as ?18°C. In deep stratiform anvil regions, aggregation was observed to be a major growth mechanism. These clouds did not contain appreciable amounts of supercooled water. Clouds with similar updrafts in the Amazon and Kwajalein exhibited similar particle types and concentrations. The implications of these results for current Tropical Rainfall Measuring Mission (TRMM) investigations are discussed.