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One of the goals of this thesis has been to fiubtt~te the potential of using a sing& station radar to estimate both radial and tangential current mmponents. Thk is certainly pcssihle as the simulations have demomrated. However, further studies will need to he attempted, with more extensive simulations and gmvndtruthing exerto validate the technique with actual data. - Even though the technique developed here may not dupiieate the accuracy ab tained from a *site system it may stii be sficient for search and rescue purposes, or for oil spill mntinpncy planning where surface transport may be required as opposed to heresolution point measurements. 6.4 Future Developments The most important radar parameter for the estimation of ocean currents is the Doppler frequency resolution of the system, since this dictates the resolving p ow of the radar with respect to current magnitude dewtion. To improve on thk resolution the examination of modem speetral estimation techniques may have to be considered (Hickey et ol. [54]). These techniques may be used to obtain a better estimate of the displaced Bragg frequencies and hence the radial current. Such techniques usually require fewer samples than the FFT p- speetd estimate, thereby allowing a scan of the radar coverage area to he performed in a mare timely manner than presently possible. For example, a full scan of the mwage area requires appmdmately one hour d data mumtian to yield the velocity resolution pmvided by the experimental data presented here. If only 32 time samples for e d beam were required, ar oppd to 512 to obtain aspect& estimate, the same zone muld be scanned in approximately 10 minutes. This is very advantageous, especially in the area of search and r-e or oil4piU traddng, where timely and regvlar surfwe current updates are required. It is also important for singlestation wetor current estimation since the sea is more Likely to remain stationary from beam to beam, with respeet to its statistical properties, 79
ar tbis scan time is reduced. Other algorithms may be evaluated for total current wetors, such as those using the equation of mntinuity (Rid and Leise [55]). In addition, these may be incorporated into the present algorithms mnstraints or as additional variables in a Least ~qn- ~pproach to the solution. Aoother approach to the solut'ion could be attempted by wing an iterati~ technique. It has been shown that the radial mmponent can be calculated directly from the radar data. Homww, by varying the tangentid mmponent in the formulatiom developed in Chapter 2, a tangential estimate which minimizen the error, with respect to the known constraints on the radial component, may be computed. This mdd lead to another estite of the tangential component. In the present formulation the re@m approach reduce8 the m eX error, thus neglecting the mean knom radial component. The quality d the measured ocean surface parameters har to he of prime impor- tance. A level of mnhdence has to he assigned to each estimate such that a user can quantify the error in the result. Statistical tdmiques must be incorporated in the radar measvrements such that the user has some degree of certainty in the men- sured quantity The uncertainties should propagate throughout the analysis, from the initial ante- voltage. to the resultant meat map. Since the parameters to be estimated are random variables with known statisti-, techniques which are available to q-tify these errors should he used (Lipa and Barriek (171). Future experiments must eosure that beam integrity is preserved, such that errors incurred here are within some angular tolerance I d . This Level should he a -ion of the error in the spectral estimator used to calculate the Bragg frequencies. This is e p d y important if her resolution radial current measurements are made, since the mrrelatlon betmen adjacent beam directions should be kept to a minimum to enhance spatial selectiv~ty. 80
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CENTRE FOR NEWFOUNDLAND STUDIES TOT
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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
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List of Symbols d : Distance irom r
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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
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Rice 1241, Barrick [I] developed an
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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
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2.2 Radial Surface Currents 2.2.1 T
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Figure 2.1: Radw Spectrum (solid li
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intervals of Ar and A.9, where thee
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Figure 2.3: Wan Q is mbdivided into
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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 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 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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