10b.3 Diagnosing the Intercept Parameter for Exponential Raindrop Size Distribution Based on Video Disdrometer Observations

Information about the drop size distribution (DSD) is essential for understanding precipitation physics, estimating rainfall, and improving microphysics parameterizations in numerical weather prediction (NWP) models (Steiner et al. 2004). The characteristics of rain DSDs are often associated with the types of storms (e.g., convective versus stratiform rain) and their stages of development (e.g., the developing versus decaying stage, Brandes et al. 2006). Strong convective rain usually contains both large and small drops and has a broad DSD while the decaying stage is often dominated by small drops. Stratiform rain usually contains relatively larger drops but has a low number concentration for a given rain rate (Zhang et al. 2006). Rain DSDs are usually represented by distribution models such as the exponential distribution, gamma distribution, and lognormal distribution. A DSD model usually contains a few free parameters that should be easy to determine and the model should be capable of capturing the main physical processes and properties. The exponential distribution is the most commonly used DSD model that has some of these properties, and it is given by