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oth of these techniques ean then be compared to the dts from thedrifteranalysis. Both simulated and actual data will be subjected to the algorithm. 4.2 Drifter Data Weighted splines were fitted to the northerly aod easterly errordinates of each driner track to form an evenly spaced time series, with t he hour inten*, of position and velocity rn described by Helbig (491. Weights were chosen to he inversely proportional to the &mated quality of each pasitional Ex. s supplied by Senice Arga. The data were not low-pass atered and extensive simulations by Helbig (491 indicated the rdtant rpeeds exhibited standard dwiations of about 5-7 m/s. The gist of the drifter velocity calculation is to aerentiate the splined-fitted pasitiaodd&a. It should be noted that although thespline 6ttio~ anddiEere~tI~ting a intended to smooth irregularities from the drifter tracks, the deriwd velocities are not eqwvalent to the radar results since they mntaio iaiormation at scds which may be different than thase mewred by the radar. The drifter estimate is Lagrandan in nature. glving an average due over a portion of a tradr. Howwer, the radar meslue is Euleriao, being ao aver* estimate over the radar resolution cell, which may he several square Idlometem. Therefore, the drifter and radar estimates may never truly equate unless the current is uniform wer a region that is large, with respect to the dimensions associated with both estimates. Hoover, this is the ody Imown reliable technique to ted the radar cwent estimate since currents near the s h e are extremely =cult to monitor. 4.3 Radar Data Data from each radar beam direction was -pled at a rate of appmximately 1.7 Hz, as described in Section 2.2.2. This unambigously displays the spectral mntent of the signal to apprmdmately f 0.8 Hz. which is su!Xcient for current measurement 39
since at 6.75 MHz the Bragg ~uencie. are apprmdmately +0.25 Hz. The nominal dwell time, or time to collect a series of mnsecutiw eeha pukes, was approximately 3W seconds. Therefore, appmdmately 512 samples were obtained and spectrally processed to give an FFT bin resolution of apprmdmately 0.0033 Hz. This yielded a current veimity resolution of appmdmately 7 on/sec. During any dwell period. 8ignals at the receivem are combined to yield a eon- structive signal from one coarse direction only (See Section 3.3.1). The radar was configured to yield 31 coarse beams, each separated by appro-tely C. Therefore, s selected extent in azimuth may be covered by dwelling on a coarse beam for a time inted, say At, at one &rune azimuth and then 'shifting' the beam direction and 'dwelling' until the required szimuthal axtent is cwered. Directions between the marse beams can be synthesized by h e beam steering, in -hare, the coarse beam data to generate t he samples at range and angular intervals of Ar and A6, rep- tively, where AT is the radar range resolution and A6 is the nominal radar beamwidth. This h e beam steering calculation is the spatial equivalent of the frequency estima- tion problem in that the freqvency resolution can be improved by either inmesing the sampling interval, coUedig more samples, or both. In the beamforming ease, the number of directions is increased by chmsing an appropriate angular ln-ent and introdveing new phase factan to &steer the coarse beam data. This angular increment is d y some integral factor of the beamwidth (Collin [44]).$ Time samples from each range-azimuth 4 were spectrally piocensed using an FFT routine to yield the Doppler inf~nnation.~ Sine the frequency placements of "(rmfo- '(rmg. LDcrv May wll not k &wed here mm I, u . -dud pracnluc m radu rlgd pro-q 1% ad mlc, bomn. r b all sr
Page 1:
CENTRE FOR NEWFOUNDLAND STUDIES TOT
Page 6 and 7:
Abstract Esrlm=r#oo of ocean surf-
Page 8 and 9: Acknowledgements Quite a number of
Page 10 and 11: Contents Abstract List of Figures L
Page 12 and 13: 5.2 Direct Radial Surface Current C
Page 14 and 15: 3.4 System architecture of Cape Rae
Page 16 and 17: List of Tables 5.1 Summary of stati
Page 18 and 19: List of Symbols d : Distance irom r
Page 20 and 21: Chapter 1 Introduction The monitori
Page 22 and 23: southward. In t k example the same
Page 24 and 25: 1.2 Conventional Methods for Measur
Page 26 and 27: iceberg motion, a better relationsh
Page 28 and 29: magnitude of the radid component is
Page 30 and 31: Rice 1241, Barrick [I] developed an
Page 32 and 33: ange broad and narrow-ham systems (
Page 34 and 35: the shon-r- radar is quite diEerent
Page 36 and 37: of a chapter. Thig dso provides an
Page 38 and 39: 2.2 Radial Surface Currents 2.2.1 T
Page 40 and 41: Figure 2.1: Radw Spectrum (solid li
Page 42 and 43: intervals of Ar and A.9, where thee
Page 44 and 45: Figure 2.3: Wan Q is mbdivided into
Page 46 and 47: The abwe system of equations is swe
Page 48 and 49: Chapter 3 Experimental Data 3.1 Int
Page 50 and 51: e built at other eoastd sites such
Page 52 and 53: Since the mean currents within mast
Page 54 and 55: Figure 3.4: System architecture of
Page 56 and 57: spatid variability and to check sys
Page 60 and 61: the dominant, or 9-, peaks of the s
Page 62 and 63: modelled, since they are known quan
Page 64 and 65: Sine the drifter estimates m e mnst
Page 66 and 67: 4.6.2 Selection of Algorithmn Param
Page 68 and 69: subtended by the b- increases in sb
Page 70 and 71: simplib the analysis by converting
Page 72 and 73: for then beams is therefore 3, 5 an
Page 74 and 75: with the graphs are from a linear r
Page 76 and 77: Fiere 5.2: Scattergrams of radid su
Page 78 and 79: Table 5.2 that the SNR eases of 10
Page 80 and 81: m-ments deliwred by radar and buoys
Page 82 and 83: Figure 5.6: Scattergrams of simulat
Page 84 and 85: Figure 5.7: Scattergrams of -tor me
Page 86 and 87: size. In other words, the algorithm
Page 88 and 89: tem, which is a programmable fsture
Page 90 and 91: Radii vetocify [cws) - Radar Figure
Page 92 and 93: ocean surface m nts where the curre
Page 94 and 95: Chapter 6 Conclusions 6.1 Direct Ra
Page 96 and 97: gential component estimate, wen wit
Page 98 and 99: One of the goals of this thesis has
Page 100 and 101: Future work dl also deal with the f
Page 102 and 103: [I4 D. Diemand, E. Faemer, and J. B
Page 104 and 105: (461 D. Barriek, M. Evans, and B. W
Page 106 and 107: DATE (LOCAL) EVENT Comments shorn 6
Page 108 and 109:
TIME - DATE (LOCAL) EVENT Comments
Page 110 and 111:
The tape was mated by using the DEC
Page 112 and 113:
Where DATLOG - Array of 32x3 bytes
Page 114 and 115:
Appendix C Catalogue of the NRSL Ra
Page 116 and 117:
Date (1992) 11/11 12/11 13/11 14/11
Page 118 and 119:
Time I FFT 1 - Date 01/11/92 02/11/
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