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subtended by the b- increases in sbb with range eerulting in a lager radar ceU size per 6xd range resolution and beamwidth. This would not beapmbi-if the antenna beamwidth a.as a 'pencil' beam, since it could be atexed in any diretion to obtain the desired radial current density per unit area. However, with a ked beamwidth h m an wtual system only one rsdid current speed b estimated fmm each range- azimuth cell, and this cell glm in size with increasing range. At ranges of 50, 100 and 200 km, for example, a beamwidth of 5' subten*, in azimuth, a distance of 4.4, 8.7 and 17.4 h respectively. If the radial extent of the input data is 5 km and data h m three adjacent be- are uJed to estimate the current components, the region sizes corresponding to there ranges and beamwidth will be 66. 130 and 260 square !dometers respectively. In order to maintam constant-area sectors, an alternative approach would be to permit the radial width of the cell to proportionately decrease as the range b increased. However, the shape of the seetars will &bit a range dependency in that the sectors becomes 'thinner' as the range is increased. As well, there is still no guarantee that current uniformity will prevail even in this situation since the region, instead of being modi6ed radially, will be extended in a lsteral sense. Therefore. when comparing e4timates at different ranges, this aspect of the current processing scheme will ultimately have to be addreased. The azimuth extent used by the Maor current algorithmn must take into eonsid- erstion the receive antenna heamwidth in the direction of the location of the estimate. For example, an noted in Section 3.2 1, the radar beamwidth of the Cape Race sys tem is appmxbately 6' when the beam is steered 6W from broadside. Therefore, when performing an estimate near the azimuthal extremes of the radar coverage zone care m m he taken to mure that this extent is Large enough to at least cwer two be- in the estimate sector. Moreom, if the current resolution of the datanets is coarse, an compared to the mean nurents of the average area, additional care must be taken such that the h g e in radial current over azimuth is adequate to s e a
the tangentid component. For -pie, the adar data used here were processed to I yield a current resolution of 8pprmdmately 7 mjs. while the mean m ent owr the experimental zone k on the order of 20 -1s. Therefore, it may be difficult to mea- sure the change in the radial current from adjacent be-, aod hence the tangential current component, if the &age rn lea thao the nominal error of the radial current messurement. An alternative in this ease is to in- the slmuthal extent of the region and proceed with the essmnption of current uniformity In summary, from the above discurnion there is a elear tradeoff betMen the radar parameters of beamwidth aod current resoittian, an well an the selection of the opt& ma1 region size to be used for wetor current estimation based on these parameters. This vdl aLso depend on the variability of the current regimes being monitored and the magnitudes of the currents. For example the technique may provide better ec timates when cur-& are large, relative to the current resolution of the system. it may &o provide reliable mean current etimates in the event of extreme -nt variability in the estimation region if the size chasen is large enough to 'force' a mean estimate from the region. AU in dl, m y of tbe paints noted here wiU have to be in- vestigated further to determine their etfeets on the reliability of the estimate provided by the aigorithmn. 4.6.4 Simplifications At t h stage in the algorithm development, it is unclear how the mam algorithmn parameters, AR and AB, sect the solution. It may vltimately require some 'good- ness of fit' testing while varying the algorithmn parameters to minimize the solution in a least squares sense with same optimal set. Since this may detract from the fun- damental issue of establishing the potential of the algorithm for current estimation, optimal parameter selection will not be dealt with. Hence, for the 6 of simplicity, key issues related to the algorithmn fundament& will be a ddrd here. These will 50
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 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 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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