Solutions

WRF Cloud Seeding Module

WRF Cloud Seeding Module

Cloud microphysical schemes fall into two categories:

  1. Explicit or bin schemes that predict mass and number of many different sizes of water drops and ice particles
  2. Bulk microphysical parameterizations (BMP) that predict mass/number of total particles of all sizes

Due to the very high computational cost of applying explicit schemes, HAP developers focus most of their attention on the BMP schemes for most applications. So–called "single–moment" schemes predict only the mass mixing ratio of the hydrometeors and then diagnose the number concentration by making various assumptions. A "two–moment" scheme also predicts the number concentration and provides more degrees of freedom for representing a size distribution. A recent scheme by Thompson et al, 2008 takes a hybrid approach in order to be computationally efficient while reproducing measurements from various field experiments. The scheme was implemented into the Weather Research and Forecasting (WRF) model and is regularly tested and improved based on results from cloud and precipitation measurements from a variety of convective and stratiform precipitation events.