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tem, which is a programmable fsture of the radar, 6- the radar it's directional receiving capabilities. Appropriate pharing of the reaived signal, at each antenna channel, is required for this purpose in order to achieve the required beamwidth and directivity Any errors in this arpgt d the pmwsing may be due to malfunctioning of the beamforming units3, sofkvare problem, or inadequate calibration data. How- ever, these heamforming ermrs may not be severe enough to mmtaminate the results of the direct radial component comparison. To understand why this is passibie, en explanation k provided, as well ar a simulation, to demonstrate the effects of beam direction errors on the radar's direct radial component estimate. To begin, one may debe a beam direction error, as a function of the radar radial current estimate and ermr, to be given by where A* = sin-'(V-/K) V-, = Radial velocity error of radar V, = Mean rsdial velocity estimate of radar This ermr may not significantly eLct the direct radial mmponeot mmparison if the actual radial components do not vary apprrciably over the beamerror range, Aor. For example, let's consider the ease wheee V- is 3 4 0 emfs, the FFT resolution emr of the experimental radar data. If V, is the expected maximum radial vel~ity of the current to be observed by any beam, then an angular be- emr of 3 i6' is obtained when this velocity is set to 40 m/s, or the maximum radial current o b s d during t* d thi. upabiliw; and (2) mod ezeamat aM obserwd in the mdar1-r radial current c~psd3mswhishm~ pcfomedwiodicdlythro~t thew-entalperi Lother-ds. there was no appnnnr need to check the *st- in the h t pk. JThistypeofrnaifvM~on~ noteddvdng thewerimentd p e E ~ m , sy.-eualpe~tttt -only ~erhrmed when obvlolu deworation of aystem psfomma a- whish occvrnd When more than 1 unit - deffftlffft. Thae lyper of fadm are noted in Appendix A.
the experimental trials. In other wrds, a beam angle error of this magnitude may not significantly effect the results of the direct radial velocity comparlson since the 'sloppiness' of the beam is not detected in the end result (i.e. the radar estimate is still within the error limits of the radar and driler current estimate techniques). Further, this beam enor is a 'best ea~e scenario' since currents are typically on the order of 20 emls in the region where most of the radar estimates &om the experimerimtal data used here where obtained which is in the area of the Avalon Channel. In other words, ifment mwtudes are not srneantly larger than the radar current error, these dimtional errors may be difficult to isolate upon inspection of a radarldrifter radial component comparison. The masking of these beam errors will be hrrther illustrated by a simulation. In the simulation the beam mom are esumed to be Gaussian, with zero mean and having a standard deviation of 6'. This beam direction 'noise' wa4 added to the actual r& I& data by shifting the baing of the radar estimate, by this emr angle term, to generate s beam-red data set. A direct radial component comparison wss then performed between the radial components of drifter buoy 3 and the beam-ermred data. This example utilized the same analysis procedure which was used in Seetion 4.5. The results are shown in the scattergrams of Figure 5.8. It is evident. from inspeetion, that the difference in the scatter is not significantly a%eeted by the beam errors used here. Therefore, for the current regime studied here, it is quite plausible to obtain a goad comparlson for the direct radial component estimate even with significant beam direction errors. The effect of besmbnoing enors on the tangential component estimate may not give rise to ermrs of the magnitudes which were observed for the radial component. The errors are compounded by the fact that more than one beam of data is required to calculate the vector component estimate. Sice the &ect of this type of error on the estimate from the vector current algorithm is not b orn, asimulation is presented which illustrates the magnitudes of this kind of error. The algorithm parameters used
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CENTRE FOR NEWFOUNDLAND STUDIES TOT
Page 6 and 7:
Abstract Esrlm=r#oo of ocean surf-
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Acknowledgements Quite a number of
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Contents Abstract List of Figures L
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5.2 Direct Radial Surface Current C
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3.4 System architecture of Cape Rae
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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
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southward. In t k example the same
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1.2 Conventional Methods for Measur
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iceberg motion, a better relationsh
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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 (
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the shon-r- radar is quite diEerent
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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 58 and 59: oth of these techniques ean then be
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 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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