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Figure 2.1: Radw Spectrum (solid line) bm 6.75 MHz operation. An underlying current with a radial component of approximately 100 em/s and moving away from the radar induces a Dopplershift of apprmdmately 0.045 Hz on the spectrumobserved vlth no underlying m n t (dashed line). pe& Since the frequency computation is performed by using a standard soft-e FFT implementation, the frequency rerolution of the spectrum is the reciprocal of the time interval, in seconds, over which the data from each cell is sampled. This tune interval or coherent integration time (CIT) restricts the radar's ability to "pinpoint' the tiue Doppim bequency using the periodogram appro&. Hence,the actual peak may be 'somewhere between' two adjacent kqnency bins. The estimation of the 'mcnn' or centre h.rl\nency of a 3pectral pePk rs performed wrrh the mrmnonly urm >It u ab-""d ,hat rdsl men, dcwuolu u d by LDB~~YLR~OLR~O onon uu,&m,, ' mlu3arwl ru the c uml raalutrou LNVI&~ by th. FM
'centroid' definition, while an estimate of the ermr in this calculation is provided by the FFT resolution. Thus, a radial current estimate, as well as an estimate of its error. is obtained h m each rada spectrum. To illustrate the above mncepts, an example i. presented using the system param- eters of the Cape Race radar, namely t hw associated with the radar's spatial and Doppler renolutiom. The azimuthal resolution ofa hear array is approximately AID radiaas where A is the radar wavelength and D is the Length of the array (Cob [MI). Since the receive array at Cape Race. circa 1992, wa. 866 m in leogth and the centre radar frequency m8 6.75 Mhz, the approximate radar beamwidth is 3 degreesP. The radar's range miutlon is determined by the bandwidth, f, of the transmit wavefo~m and is giwn by c/(2f) where e is the velociCy of light. Since the radar transmusion bandwidth used to generate the experimental data of thk report aras 375 ldIz the range re~olution for the experiment is approximately 4M1 m. Therefore, the cell size at ranges of 50, 100 and 200 1rm are approximately 1, 2 and 4 square km, respstively. To determine the approximate current frequency resolution we need to refer to the wawform mpetition mterval which, for the expeMlental data, was apprmrimately 0.6 sands. 'Qpicall~ 512 mmples were collected at this sampling interval, per radar beam, to yield a CIT of approximately 300 semnds. Smce the frequency resolution is the reciprocal of this time interval, the resultant Doppler resolution is apprmdmately ,003 Hertz. The mrrespondiog current velocity resolution, using Equation 2.3. is approximately 7 em/s. In other mrds, the current estimate is approximate to within 13.5 wn/s of the FET estimate. The azimuth associated with this estimate is ob tained by the appropriate phasing of the received signal at each antenna. Therefore, to ewer a selected azimuthal extent in the radar ewerage zone, we can dwell in a direction for a time intenral, At, then 'shift dimion and dwell' until the region is coveted. We can t hdre generate radial velocity estimates at range aod andar 'This that each el-t ia ia ktmplc SemoT. aoa*ew, the beamwidth thtuauy vari~a from appmdmately 2 8 to 6.0" beoava of the sut-amay pat-
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 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 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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