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Last modified
7/28/2009 2:28:24 PM
Creation date
10/1/2006 2:14:58 PM
Metadata
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Template:
Weather Modification
Project Name
Annual Report
Title
Seeding Operations & Atmospheric Research, 2005 Annual Report
Prepared By
Duncan Axisia
Date
12/31/2005
Weather Modification - Doc Type
Report
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<br /> <br />Indeed, many of the results reported in the meteorological <br />literature would not survive such strict evaluation. However, <br />like weather forecasting, doud seeding should be held to <br />higher level of proof because of its potential importance to <br />society. <br /> <br />Silverman (2001) replies: <br /> <br />I also recognize that the proposed proof-of-concept criteria <br />for doud seeding are much stricter than those generally <br />required in meteorological research and agree with Hobbs <br />that doud seeding as well as daims of dimate change <br />should be held to a higher level of proof because of its <br />potential importance in society. <br /> <br />A recent publication by Silverman (2003) in the <br />Bulletin of the American Meteorological Society <br />summarizes the results of the South Africa, <br />Mexico, Thailand and India randomized <br />hygroscopic seeding experiments in the form of a <br />critical assessment. Silverman comments that a <br />high priority should be given to programs that <br />investigate, develop and evaluate the physical <br />hypothesis of hygroscopic seeding. Silverman <br />(2003) remarks that his basic position on cloud <br />seeding has not changed; <br /> <br />I oontinue to advocate doud seeding in situations where tl is <br />scientifically and operationally appropriate, and strongly <br />reoommend that an independent evaluation accompany <br />each research or operational project in order that the science <br />of weather modification benefit from the experience. <br /> <br />The level of proof required by water district <br />managers is generally lower than what is <br />expected in the scientific community. The <br />decision of whether to implement or continue an <br />operational program becomes a matter of <br />cosVbenefit risk management (Bruintjes, 1999). <br />The research conducted in Texas during <br />randomized experiments and the experience of <br />previous operational programs is a sufficient <br />proof that cloud seeding is a potential technology <br />to constitute a long-term water resources <br />management strategy. It is not the objective of <br />water districts to take a research role to pass the <br />high level of proof required by scientists. <br /> <br />However, it is the role of the water district to <br />conserve water and to evaluate the success of its <br />programs. Program evaluations in doud seeding <br />can be approached in different ways. <br /> <br />. <br />. <br />. <br />. <br />. <br />~ <br />.. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br /> <br />The TITAN approach <br /> <br />TITAN has been identified as the primary tool <br />utilized to conduct airborne doud seeding <br />operations. All of the Texas cloud seeding <br />projects make use of WSR-74C (C-band) 5cm <br />radars as well as a 10cm NEXRAD feed. This <br />raw data is displayed operationally with the <br />Thunderstorm Identification, Tracking, Analysis, <br />and Nowcasting (TITAN) software. TITAN <br />permits the radar operator to examine the three- <br />dimensional structure of echoing douds in real <br />time. Individual echoes and groups of echoes <br />can be tracked and their development and <br />motion projected in time. The ability to identify <br />and track echoes and calculate their properties <br />with time makes TITAN a potential tool for the <br />evaluation of doud seeding experiments. Such <br />evaluations are fairly straightforward and <br />compare fields like the lifetime, area, volume and <br />rainfall mass of seeded douds to douds that <br />were left unseeded, therefore acting as a control. <br />A control doud is an unseeded cloud that lives in <br />the same environment as its seeded partner, in <br />similar synoptic conditions, at similar distance to <br />the radar and from the same day. The control <br />doud is than run through a model to give the <br />selected control doud the same initial condition <br />as that of the seeded cloud. Such an analysis is <br />presented in Appendix C. <br /> <br />Using the National Weather Service <br />(NWS) NEXRAD (NEXT -RADAR) <br /> <br />Dr. William L. Woodley, President of WWC and <br />Dr. Daniel Rosenfeld, Professor at the Hebrew <br />University of Jerusalem in Jerusalem, Israel, <br />have pursued the assessment of area seeding <br />effects in the High Plains target area in 2000, <br />2001 and 2002. The evaluation of seeding <br />efficacy involved the use of NEXRAD base-scan, <br />mosaic, radar data and a new assessment <br />method. This methodology makes use of <br />"merged" NEXRAD radar data rather than TITAN <br />radar data, since the former provides greater <br />area coverage by "merging" the observations <br />from several radars in Texas. Having selected <br />the radar system and secured the needed data, <br /> <br />27 <br />
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