A doppler radar for continuous remote measurement of river ice velocity

Original publisher: Hanover, N.H. : U.S. Army Cold Regions Research and Engineering Laboratory, 1995. OCLC Number: (OCoLC)34682733 Subject: Doppler radar. Excerpt: ... 2.0 peak, and raw - peak records, respectively. Given the various measurement errors, these compari-1.6 ) sons suggest fundamental agreement of ( m / sthe methods. However, additional development of 1.2 city the peak return data reduction method is needed elo 0.8 because of the significant underprediction of the V e mean Icvelocity. 0.4 Ice velocities exceeding 5 m / s during breakup Video Data have been reported on some rivers. The maxi-0 mum Doppler frequency that can be obtained with a given system is limited by the Nyquist 0.04 e ≤ sampling rate, f N / 2. With our system, rencveloci-d ties of up to 6 m / s can be obtained with Doppler iffe frequencies less than 200 Hz, indicating that the 0 D d Nyquist rate does not restrict velocity alizemeasure-ment at the high end of the observed range. Un-rm - 0.04 like optical methods, the large changes in Noriver stage that can occur during breakup do not affect Doppler radar velocity measurement. - 0.08 0 10 20 30 Time ( min ) Frazil ice run - December 1993 Figure 10. Ice velocity data, best polynomial fit, Doppler radar ice velocity and simultaneous and normalized difference between the data and video ice velocity records were obtained for the polynomial of the video ice breakup record. Connecticut River at the Cornish - Windsor bridge on 28 December 1993. Frazil pans and 2.5 floes were moving downstream during the measurement period at a river flow of about 170 2.0 3 m / s, just prior to ice cover formation. Over sev-/ s ) eral hours of data collection, the river flow and ( m1.5 ice velocity conditions were relatively citysteady, and we selected a typical 1000-s record for Veloanaly-1.0 sis. The video setup and grid were the same as in Video Data 0.5 Peak Data the previous event. The radar antenna was Raw Data mounted at the same height and location...