Numerical Simulation of Cloud Seeding using a Three-Dimensional Cloud Model

Authors

  • Richard D Farley Institute of Atmospheric Sciences South Dakota School of Mines and Technology Rapid City, South Dakota
  • Phuong Nguyen Institute of Atmospheric Sciences South Dakota School of Mines and Technology Rapid City, South Dakota
  • Harold D Orville Institute of Atmospheric Sciences South Dakota School of Mines and Technology Rapid City, South Dakota

Abstract

This preliminary study is concerned with the numerical modeling of cloud seeding effects in three dimensions for the deep convective cloud case of 19 July 1981 from the CCOPE field experiment. The observed cloud was relatively isolated and grew rapidly to about 11 km height. An extensive anvil was produced. For the first time in our 3D modeling efforts, a silver iodide (Agl) seeding agent is introduced into a three-dimensional cloud model. Ice and precipitation formation occurs 2 min earlier in the seeded case. Maximum mixing ratios show only slight increases (about 5% for graupel/hail) compared to the unseeded case. Domain totals of graupel/hail and rain indicate a more pronounced seeding effect, consistent with surface rainfall estimates of a 20% increase for the seeded case. For the 3D case in this study, 10% of the Agl remains unactivated, caught in a dead zone of virtually no net transport to the southeast of the cloud around 4 km AGL. The use of an inert agent, sulfur hexafluoride, for comparison purposes helps to illustrate the region of activated Agl.

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Scientific Papers