| OCR Text |
Show SECTION 1. 0 SUMMARY OF PURPOSE, DESIGN, AND CONCLUSIONS 1. 1 Objectives of the Project The main purpose of the project was to obtain definitive evidence as to whether it is physically and economically possible to augment precipitation in the headwaters of drainage basins by engineering-scale application of weather modification techniques. Specifically, the study was planned to test the applicability of ground and airborne silver iodide seeding in orographic;: precipitation systems. In order to accomplish the primary objective, a satisfactory experimental design had to be established. This design then had to be supported by a specialized data collection network with sufficient time and space resolution to supply adequate measurement for analysis. Accordingly, secondary objectives of the program were the development and testing of experimental techniques for weather modification studies, and evaluation of the usefulness of various seeding, observing, and analysis methods. 1. 2 Experimental Design The experiments were carried out in the Park Range near Steamboat Springs, Colorado. · Figure 1 shows the experimental area and the seeding and observing stations as they existed during the last year of the study. 1. 2. 1 Pulsed Seeding Design A rather novel experimental design was originally established. The design applied. power spectral analysis procedures to precipitation-rate time histories, in order to deter.mine the effect of one cycle per hour ( 1 cph) pulsed silver iodide seeding. This design was employed during the seasons of 1965-66, 196667, and part of 1967-68. During the first year of operation (1964-65), no seeding was done, but the collected precipitation rate data was used to establish natural background power spectrum features. In the latter two-thirds of the 1967-68 season the frequency of pulsed seeding was decreased to ½cph or¼ cph and the seeding site was moved further upwind of the target. Airborne seeding events were introduced in January and February 1968, and continued during the 1968-69 season. The short-period variability of wind and stability was found to smear the seeding period into the short unseeded period, and thus, conclusive results concerning seeding effect were not obtained by this method. 1 |
