GUIDE WAVE ANALYSIS AND FORECASTING - WMO

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74 TABLE 6.1 Performance of operational wave models (the statistics quoted in the last columns are defined in the text) Model Organization Location of Verifying data and verification period Wind/wave parameter Verification statistics — analysis buoys (0-hour forecast unless otherwise indicated) ME RMSE SI r N* CSOWM Environment Canada NW Atlantic 10 buoys on US/Canadian east coast Wind speed (m/s) 1.7 3.2 59 0.68 871 (May–July 1990) Wave height (m) 0.19 0.56 42 0.80 974 Peak period (s) –1.0 2.4 32 0.30 918 NE Pacific 12 buoys on US/Canadian west coast Wind speed 0.0 2.4 41 0.67 575 (May–July 1990) Wave height –0.18 0.55 31 0.81 629 Peak period –1.4 3.8 42 0.12 630 GUIDE TO WAVE ANALYSIS AND FORECASTING GSOWM US Navy US east coast US/Canada east coast buoys Wind speed –0.1 3.0 37 0.72 967 (20 February–20 March 1992) Wave height 0.31 0.86 41 0.83 1016 US west coast US/Canada west coast buoys Wind speed –1.2 3.1 55 0.54 644 (20 February–20 March 1992) Wave height 0.95 1.16 56 0.58 710 Hawaii Buoys around Hawaiian Islands Wind speed –1.3 1.7 23 0.92 203 (20 February–20 March 1992) Wave height 0.09 0.63 23 0.59 209 NW Pacific Buoys around Japan Wind speed –0.4 2.6 37 0.76 158 (20 February–20 March 1992) Wave height 0.25 0.67 39 0.77 160 MRI-II Japan Meteorological NW Pacific Buoys around Japan Wave height 0.05 0.58 34 0.83 – Agency (entire year 1991) (24-hour forecast) Coastal wave Coastal Japan 11 buoys off the coast of Japan Wave height –0.06 0.46 39 0.82 – model (hybrid) (entire year 1991) (24-hour forecast) WAM European Centre for NW Atlantic US/Canada east coast buoys Wind speed 0.06 2.0 42 0.64 434 Medium-Range Weather (August 1992) Wave height –0.06 0.36 34 0.73 549 Forecasts (ECMWF) NE Pacific US/Canada west coast buoys Wind speed –0.01 1.5 23 0.89 369 (August 1992) Wave height 0.16 0.40 20 0.88 371 Hawaii Buoys around Hawaiian Islands Wind speed –0.42 1.5 20 0.46 351 (August 1992) Wave height 0.0 0.35 17 0.50 352 NW Pacific Buoys around Japan Wind speed –0.78 2.6 34 0.86 204 (August 1992) Wave height –0.08 0.68 31 0.88 194 * Number of data points
Wind (m/s) Waves (m) Buoy/GSOWM Waves RMS 1.08 Mean error 0.7 Scatter Index 0.35 Buoy/GSCLI Winds RMS 3.39 Mean error 1.5 Scatter Index 0.48 altimeter wave heights. The WAM model wave height field is compared daily against the altimeter fast delivery product from the ERS-1 which is received in real time. (Note that care should be taken in using altimeter data provided by the space agencies, as H s may be significantly biased and require correction. Further, the bias for data from a particular instrument may change as algorithms change, and it may differ from one originating source to another.) A list of wave models operated by various national Meteorological (and Oceanographic) Services is given in Table 6.2. Most of these wave models are verified routinely against available wind and wave data. Besides these wave models, there are other wave models which have been developed and are being used either experimentally or operationally by other organizations like universities, private companies, etc. Additional informa- OPERATIONAL WAVE MODELS 75 Buoy/WAM Waves RMS 0.91 Mean error 0.1 Scatter Index 0.30 tion on these wave models and their verification programmes is available elsewhere (see WMO, 1985, 1991, 1994(a)). 6.5 Wave model hindcasts Buoy/NOGAPS Wind RMS 3.90 Mean error 2.0 Scatter Index 0.55 Figure 6.6 — Wind and wave verification at a buoy location (lat. 50°54'N, long. 135°48'W) in the Gulf of Alaska. The plot shows wind speed and significant wave height values for the period 20 February to 20 March 1992 as measured by the buoy (* **) and as simulated by the wave models GSOWM (– – –) and WAM (——). Also shown are wind and wave verification statistics for GSOWM and WAM (source: Paul Wittman, Fleet Numerical Oceanography Centre, Monterey, USA) A wave model in operational use will usually be forced by forecast winds to produce wave forecasts. However, the model may also be driven by analysed winds pertaining to past events, such as the passage of hurricanes (tropical cyclones) or rapid cyclogenesis over the sea. In such cases the wave field generated by the wave model is called the hindcast wave field. Wave hindcasting is a non-real-time application of numerical wave models which has become an important marine application in many national weather services.
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WORLD METEOROLOGICAL ORGANIZATION G
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© 1998, World Meteorological Organ
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IV Chapter 7 - WAVES IN SHALLOW WAT
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ACKNOWLEDGEMENTS The revision of th
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VIII has been included particularly
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X considerable attention. Annex III
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2 η Crest Zero level a H = 2a a Tr
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4 Figure 1.5 — Paths of the water
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6 When waves propagate into shallow
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8 1.3.2 Wave groups and group veloc
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10 wavelengths in a given sea state
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12 for instance, a frequency of 0.1
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14 in which E(f) is the variance de
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16 2.1.1 Wind and pressure analyses
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18 GUIDE TO WAVE ANALYSIS AND FOREC
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20 Figure 2.2(a) (right) — Usual
Page 33 and 34: 22 As a quick approximation of ocea
Page 35 and 36: 24 GUIDE TO WAVE ANALYSIS AND FOREC
Page 37 and 38: 26 Gr G Gr ∇p C Cnf ∇p C Cnf
Page 39 and 40: 28 POINT C — The effect of warm a
Page 41 and 42: 30 a general sense, and can be appl
Page 43 and 44: 32 Free atmosphere Ekman layer Cons
Page 45 and 46: 3.1 Introduction This chapter gives
Page 47 and 48: ange of directions. Also, waves at
Page 49 and 50: small enough that swell can survive
Page 51 and 52: Figure 3.7 — Structure of spectra
Page 53 and 54: 4.1 Introduction CHAPTER 4 WAVE FOR
Page 55 and 56: necessary to forecast waves for a p
Page 57 and 58: TABLE 4.4 Additional wave informati
Page 59 and 60: TABLE 4.6 Ranges of swell periods a
Page 61 and 62: this situation, the angular spreadi
Page 63 and 64: the energy flux is c gH 2 . This is
Page 65 and 66: α0, degrees Solution: 80° 70° 60
Page 67 and 68: 5.1 Introduction National Meteorolo
Page 69 and 70: only once, since it is usual to sto
Page 71 and 72: Frequency 0.050 0.067 0.083 0.100 0
Page 73 and 74: The models may differ in several re
Page 75 and 76: The CH class may include many semi-
Page 77 and 78: 6.1 Introductory remarks Since the
Page 79 and 80: in some applications, the zero up/d
Page 81 and 82: OPERATIONAL WAVE MODELS 71 Figure 6
Page 83: give large differences in the compa
Page 87 and 88: TABLE 6.2 Numerical wave models ope
Page 89 and 90: TABLE 6.2 (cont.) Country Name of m
Page 91 and 92: 7.1 Introduction The evolution of w
Page 93 and 94: water boundary into shallow water.
Page 95 and 96: eflected waves, although the latter
Page 97 and 98: Energy (cm 2 /Hz) Energy (cm 2 /Hz)
Page 99 and 100: 8.1 Introduction Wave data are ofte
Page 101 and 102: matter and timing the intervals bet
Page 103 and 104: a Directional Waverider (Barstow et
Page 105 and 106: 80°N 60°N 40°N 20°N 0° -20°S
Page 107 and 108: a combination of sea-surface temper
Page 109 and 110: 8.7.1 Digital analysis of wave reco
Page 111 and 112: 9.1 Introduction Chapter 8 describe
Page 113 and 114: Presentation of data and wave clima
Page 115 and 116: the monsoon season of June to Septe
Page 117 and 118: Probability of non-exceedance case
Page 119 and 120: individual wave height derived usin
Page 121 and 122: emote, data-sparse areas. However,
Page 123 and 124: TABLE 9.2 (cont.) Country Source of
Page 125 and 126: For a storm hindcast, select the mo
Page 127 and 128: TABLE 9.3 (cont.) Country Model use
Page 129 and 130: ANNEX I ABBREVIATIONS AND KEY TO SY
Page 131 and 132: Abbreviation/ Definition Symbol MOS
Page 133 and 134: CODE FORM: D . . . . D or IIiii* SE
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sensors, spectral peak wave period
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cs1cs1 The ratio of the spectral de
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M jM j n mn m n smn sm n bn bn b P
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1744 Im Indicator for method of cal
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The following distributions are bri
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4. Weibull distribution Probability
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8. Fisher-Tippett Type I (FT-I) (or
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ANNEX IV THE PNJ (PIERSON-NEUMANN-J
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ANNEX IV 141 Duration graph. Distor
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REFERENCES Abbott, M. B., H. H. Pet
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REFERENCES 145 Carter, D. J. T., P.
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REFERENCES 147 Gumbel, E. J., 1958:
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REFERENCES 149 Maat, N., C. Kraan a
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Slutz, R. J., S. J. Lubker, J. D. H
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SELECTED BIBLIOGRAPHY CERC, 1984: C
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156 Energy . . . . . . . . . . . .
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158 steepness . . . . . . . . . . .
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