OCR Text |
Show quently analyzed for silver content by an atomic absorption spe ctroph otomete were ( datat) 1. 3. 4 Replica Analysis and Identification of Silver Iodide Ice Nucle i Several thousand snow crystal replicas were collected on plastic-coated glas slides and analyzed for crys tal habit in relation to seeding. Originally, an electron microscop e technique was emp loyed for identifying silver iodide par ticles which were located at the center of snow crystals, and had thus served as ice nuclei. However, this technique was expensive and during the 1968-6! season a new less expensive technique was developed and used with significan results. 1. 3. 5 Radar and Radiosonde Measurements Throughout the project a radar balloon tracking facility was operated at Mt. Harris (20 nmi we st of the target) for obtaining upper wind measurements at 1 to 3 hour intervals. A 403 MHZ radiosonde system was used initially, and after January 1967, 1680 MHZ radiosonde information was available from Mt. Harris at 3 to 6 hour intervals. PPI photographs from Mt. Harris were also valuable analysis aids, as was AGC vertical-pointing data from a GPG-1 radar, located between the AgI release site and the target area. The measur ments from the radiosondes and tracked balloons were used extensively in all analyses. In fact, it was found to be absolutely mandatory to have frequent measurements of this type for satisfactory analysis under the two main expe mental designs employed in the Park Range Project. 1. 3. 6 Diffusion Tests data Si 1. 5 The de positiv that( \ ascon serve 5rnall The s1 of squ optica impo: Rabbi colde et. a· The and 1 silvE expE gra\ req ope sys 1 In order to adequately analyze for seeding effect, a reliable description of the diffusive characteristics of the released seeding material is required. on This was difficult as no ad e quate model of diffusion was known to exist for mountainous topography. Thus, a large number of diffusion tests were made It h using both ground and airborne releases of phosphorescent particles and be; silver iodide tracers. Lithium stearate was used as an inert tracer in sevtha1 eral dual tracer tests. Plume tracking downwind was made by aircraft, and per also at the surface in the target area. pro Fo1 1. 4 Analysis Procedures ma The analysis procedures for 1968-69 were considerably different than for previous years, due to the major change in experimental operations design, and also due to the availability of a numerical model of orographic fl ow and precipitation. In years prior to the 1968-69 season, the analysis emphasis was on power spectral procedures using pulsed seeding data, along with analyses of snow crystal type, ice nuclei count, and snow samples collec ted for obtaining silver concentration. The analysis procedures for 1968-69 4 tati l. ! |