Testing of Dynamic Cold-Cloud Seeding Concepts in Thailand Part I: Experimental Design and Its Implementation

Abstract

Dynamic, cold-cloud, seeding concepts are being tested in Thailand in the context of the Applied Atmospheric Resources Research Program (AARRP). This work was conducted under a contract with the Bureau of Reclamation as part of a U.S. Agency for International Development-sponsored program to upgrade Thailand’s weather modification capability.. The AARRP is a component of Thailand’s national program of weather modification under the direction of the Royal Rainmaking Research Development Institute (RRRDI). Part I focuses on the design and execution of the Thai, exploratory, randomized, cold-cloud experiments and on the conceptual model that is guiding these investigations. The treatment units for these experiments are the convective cells, which contain cloud towers that meet the liquid water and updraft requirements. In the Thai design, it is the cell that receives the on-top silver iodide treatment, and any effect of seeding should manifest itself first on this scale before it is seen in the experimental unit that contains the cells. The experimental unit consists of the small multiple-cell convective system located within a radius of 25 km and centered at the location of the convective cell that qualifies the unit for the first treatment. Evaluation of the experiments is to be accomplished using an S-band (10-cm) radar that is located near Omkoi in northwestern Thailand. Fifteen experimental units (8 Seed and 7 No Seed) have been obtained to date, and they appear to be well-matched. Bias does not appear to have been a factor in the selection of these random cases and in the subsequent cloud treatments. Evaluation of these units and the convective cells contained within them is presented in Part II.