Monterey Buoy 46042 LT Karen Wingeart

Outline of Presentation Buoy characteristics Measurements taken Data discussion Conclusions

Parameter Range Freq Avg Resol Accuracy Wind dir 0-360° 1.0 Hz 8 min 1° ±10° Wind spd 0-62 m/s 0.1 m/s ±1.0 m/s Wave ht 0-35 m 2.56 Hz 20 min 0.1 m ±0.2 m Wave pd 0-30 sec 1 sec ±1.0 sec Spectra 0-999 m2/Hz 0.01 Hz ±0.01 Hz Wave dir NA

Measurements taken Wind Direction Wind Speed Wave Energy Significant Wave Height Mean Direction Directional Spread (R1) + = [2(1–R1)]1/2 , R1 = [a12+b12]1/2

Normalized Energy vs. 

Relative Energy vs. Period

Composite contour plot, white lines are missing data Composite contour plot, white lines are missing data. Used to initially identify swell events. Did not look at data >0.15 Hz. Swell events have periods <0.15 Hz.

Energy spectrum related to energy of waves Energy spectrum related to energy of waves. Just prior to the swell event. Two peaks, EN = 0.6 m^2/Hz at T = 14s, & 10s.

At the beginning of the swell event, peak en = 15 m^2/Hz at 14 s period.

Peak of swell event, 100 m^2/Hz, 16 s period.

Wind directions from northeast to northwest Wind directions from northeast to northwest. Local winds from 2 m/s – 12 m/s. Measured SWH and calculated SWH from integrated Pierson-Moskowitz spectrum.

Significant Wave Height The relationship between wind and Hs can be found by integrating the Pierson-Moskowitz spectrum: E(f)=g2/((2)4f5)exp[-(2fU/g)-4] variance = 0E(f)df = U4/(4g2) Hs = 2(/)1/2(U2/g) where =8.1010–3 and =0.74 (Hasselmann et al., 1973). Pierson-Moskowitz spectrum = as wind speed increases, wave period increases, energy increases, and slope of right edge of spectra->f^-5.

Measured Dominant wave period at peak freqs and calcuated dominant wave period.

Peak Frequency Peak Period estimated from local winds using relationship from Hasselmann et al. (1973). fp = g/(2U)

The cloud band north of Monterey Bay moved southeastward, in the direction of the swells. This system was probably the source of the waves.

Conclusions Swells generated by distant storm from Northwest Pacific as evident by large energy increases and directional properties. Data obtained from http://www.ndbc.noaa.gov/, beware of archive gap! Matlab helpful in processing data. Additional study of wind-wave interaction needed with more accurate wind data near buoy site. Conduct study during months of increased storm activity for more swell events, ie. October.

Questions???