This paper presents drop size distribution measurements during NASA’s Tropical Rainfall Measuring Mission (TRMM) – Large Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) and follow-up field campaigns conducted in Kwajalein, Florida Keys, and Wallops Island. Each site represents different climate region. The rainfall in Amazon Basin of Brazil represents tropical continent rainfall, while Wallops Island receives both widespread and convective rainfall. Kwajalein represents the tropical oceanic rainfall, while Florida Keys receives continental rainfall with oceanic background. The differences in characteristics of rainfall have a direct impact on satellite rainfall algorithms including TRMM and upcoming Global Precipitation Measurement (GPM) mission. The error characteristics of drop size distribution measurements and small-scale variability will also be discussed through a regional study.