Laserfiche WebLink
<br />OtJ2497 <br /> <br />prepared for seeding operations to coordinate with surface 700-mb <br />mean layer wind speeds and directions. <br /> <br />Operational Status: MBA said that the program would be considered <br />to be in operational status during the time interval from 30 minutes <br />prior to the start of seeding until the end of an operational day. <br />In other words, operational status occurs in a normal situation from <br />0730 hours, 30 minutes prior to the seeding day, until 1000 hours <br />the following day when data collection stops for the operational day. <br />Alternately, if the day is declared operational during the period <br />0800 to 0800 hours, the project would be considered to be in opera- <br />tional status. Alert status would always precede operational status. <br /> <br />The project meteorologist would use forecast wind speed, wind direc- <br />tion, the time of onset of precipitation, and inversion conditions <br />observed by the acoustic echo sounder to specify which seeding genera- <br />tors are to be used to seed the orographic cloud systems. The genera- <br />tors would be turned on at the start of an operational period if the <br />project meteorologist has judged that sufficient convection is present <br />in the area. As indicated in the trajectory calculation, seeding <br />would be conducted approximately 65 km upwind of the area of effect, <br />assuming a neutral atmospheric stability, and a 15 m/s wind normal to <br />the barrier. The precise location of the aircraft would be dictated <br />by the location oJ the convective activity as determined by a 35-dBZ <br />(strength of radar signal) reflectivity or a gradient of more than <br />10 dBZ in 5 km. MBA said that the seeding should be at the _50 isotherm, <br />at a preferred rate of 10 g/min. The seeding would continue to produce <br />a calculated 10-particles/litre density of artificial nuclei within <br />the cloud for 1 hour. <br /> <br />I <br /> <br />In the orographic case when vertical transport is blocked by <br />inversion conditions, aircraft seeding would be conducted. The <br />aircraft will produce a line source of silver iodide (AgI) nuclei <br />at the level of onset of activity, the -50C isotherm. After the <br />disseminated plume has stabilized behind the aircraft, the nucleus <br />density should be 10 nuclei/litre. <br /> <br />Radar observations during the operational period would be taken for <br />the purpose of determining cloud top heights to aid in the ascertaining <br />of seedability and of observing convective cell motions in conjunction <br />with seeding. The cloud top heights would be checked periodically <br />throughout the operation (at least hourly), and submitted to the <br />project meteorologist. The observations should minimally include <br />maximum cloud top heights, minimum cloud top heights, and a sub- <br />jective evaluation of the variability during the observation period. <br />Convective cells would be defined by the 35-dBZ contour on the radar <br />and will be followed simultaneously with seeding operations. <br /> <br />22 <br />