Use of sophisticated three-dimensional numerical models in weather modification efforts

Understanding of the complex interactions between the mesoscale and cloud environment and between microphysical and dynamical processes within clouds can be substantially increased with the aid of sophisticated numerical models. These models can provide additional insight in key areas where scientific knowledge is presently lacking. To study the initiation, organization and complete life cycle of convective and orographic clouds over complex terrain requires time-dependent models with three spatial dimensions. The sophistication is necessary because the interactions that occur in nature in a cloud and between the cloud and its environment are often times non-linear and self compensating. In the past, numerical models with one or two spatial dimensions have been extensively used in weather modification research and only recently have models with three spatial dimensions received more attention. The reason for this is that the computer technology to run these sophisticated models has improved in the past several years and is now more available. The paper gives an overview of the present state of art of numerical modelling in weather modification efforts. Some of the recent applications and studies in precipitation enhancement programs using the sophisticated three-dimensional time dependent Clark model are highlighted.