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<br />The radar system was contained in a semi-type trailer. <br />The 4.27 m diameter dish antenna was installed on the roof <br />in a fiberglass radome to protect the dish from the weather, <br />especially from wind loading. Data were continually recorded, <br />whenever clouds were present, from the time of installation <br />until it was disassembled except for a nine day period between <br />February 4-12. During this time the radar was inoperative <br />due to failure of the pulse package. <br /> <br />2.4.4 <br /> <br />Acoustical Sounder <br /> <br />An AeroVironment Model 2000 Doppler acoustic sounder <br />was provided by NAWC for operation at the Happy Jack site. <br />The system used two antennas to provide horizontal wind direction <br />and speed from the doppler shift of the reflected 1500 Hz <br />signal. System resolution is about 3 degrees and 0.2 m's-l <br />according to the manufacturer. <br /> <br />The system provided 15 minute mean winds at 30 m intervals <br />beginning at 30 m agl (above ground level) and extending to <br />as high as 600 m agl under favorable conditions. Past experience <br />with the same system suggested that maximum attainable levels <br />were usually between 300-600 m depending upon the turbulence <br />present. Also, the signal may be lost at higher levels under <br />strong wind conditions. The system is sensitive to the local <br />site as echoes from nearby trees or other structures can degrade <br />the signal. <br /> <br />The Happy Jack site was a moderate-sized clearing in <br />the forest. A larger clearing would have been desirable, <br />but none was available near Happy Jack. <br /> <br />2-13 <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />f <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />