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physical processes within them (see Appendix A). The instrumented platform consisted of the <br />Particle Measuring Systems’ (PMS) Passive Cavity Aerosol Spectrometer Probe (PCASP SPP- <br />200), the Droplet Measurement Technologies (DMT) Cloud Droplet Probe (CDP), the DMT Cloud <br />Imaging Probe (CIP), DMT’s airborne CCN counter and Texas A&M University’s aircraft-based <br />high flow rate Differential Mobility Analyzer (DMA)/Tandem Differential Mobility Analyzer (TDMA). <br /> NEXRAD weather radar data equipped with Thunderstorm Identification, Tracking, Analysis, and <br />Nowcasting (TITAN) hardware and software. Geostationary Positioning Satellite (GPS) latitude <br />and longitude data from the research aircraft is displayed on the TITAN software; <br /> FX-Net workstation that provides access to the basic display capability of an Advanced Weather <br />Interactive Processing System (AWIPS) workstation via the Internet. <br />The planned research utilized the base of operations of the SOAR Program at the airport in Plains, <br />Texas. A significant effort of the measurement program was focused within the multi-county target areas <br />of the Texas weather modification programs and the surrounding counties in New Mexico and Oklahoma. <br />The co-Principal Investigators for SPECTRA Phase I were Dr. William L. Woodley (President, Woodley <br />Weather Consultants) and Prof. Daniel Rosenfeld (Hebrew University of Jerusalem, in Jerusalem, Israel), <br />who have composed the primary research team in Texas for the past 20 years. Mr. Duncan Axisa of <br />SOAR served as the primary instrumentation technician and as flight scientist. The piloting of the <br />research aircraft was the responsibility of Mr. Gary Walker (SOAR). Mr. Caleb Midgley (SOAR) provided a <br />daily forecast for the duration of the field program. Mr. Ronen Lahav (Hebrew University of Jerusalem) <br />assisted for one week with the aircraft measurement program. The TDLR’s Mr. George Bomar provided <br />administrative and technical oversight for the effort. <br />Operational outcome <br />During the SPECTRA 1 field campaign, the SOAR research aircraft was deployed in a region of <br />enhanced convection to conduct CCN measurements and subsequent measurements of drop size <br />distributions through the vertical development of the convective cloud. In order to achieve the program <br />objectives, the aircraft had to first measure the CCN and aerosol concentrations below cloud base, and <br />then proceed to penetrate the cloud formation in vertical steps to measure the microphysical properties of <br />the clouds. <br />th <br />The first research flight was conducted on the afternoon of the 7 August 2004 when convective storms <br />developed just to the north of the Lubbock area. 34 research flights were flown totaling 75 flight hours <br />thst <br />from the period 7 August 2004 to 1 October 2004. Despite the instrumentation challenges that are <br />identified and listed in this report, an extensive amount of good quality research grade data was collected <br />during the SPECTRA 1 field campaign that satisfy the objectives of the field program. <br />Results of the analysis <br />The analysis methodology focused on satisfying the primary goal of SPECTRA 1, which is the <br />documentation of the Cloud Condensation Nuclei (CCN) distribution at the cloud bases and their effect on <br />the cloud Drop Size Distribution (DSD) and precipitation forming mechanisms. In order to fulfill this goal, <br />the analysis requires proceeding with the following tasks: <br />1. Relate the CCN concentrations to the maximum cloud droplet concentrations at cloud base. <br />2. Determine how the cloud droplet effective diameter varies with increasing cloud depth. <br />3. Determine the height at which precipitation sized particles develop. <br />The analyses lead to the following findings: <br />3 <br />