51101

51101

51201

Image and data source http://www.ndbc.noaa.gov/obs.shtml

Station 51201 Pacific Islands Ocean Observing System Location: 21.669N 158.12WStation 51101 NDBC Location: 24.321N 162.058W

Station 51201 Pacific Islands Ocean Observing System Location: 21.669N 158.12WStation 51101 NDBC Location: 24.321N 162.058W

Right- skewed distributionWith long tail towards highwaves

~hourly data reporting Significant wave heightsDecember 2013-Feburary 2014

Station 51201 Pacific Islands Ocean Observing System Location: 21.669N 158.12WStation 51101 NDBC Location: 24.321N 162.058W

Less skewed distribution than wave heights.

~hourly data reporting Dominant Period in the SwellDecember 2013-Feburary 2014

Image and data source http://www.ndbc.noaa.gov/obs.shtml

Station 51201 Pacific Islands Ocean Observing System Location: 21.669N 158.12WStation 51101 NDBC Location: 24.321N 162.058W

5120151101

30ft open ocean swell on Jan 22nd, 2014

Image: http://www.petethomasoutdoors.com/2014/01/giant-swell-slams-hawaii-up-next-is-california-and-mavericks-big-wave-surf-contest.html

http://petethomas.typepad.com/.a/6a0120a77b966b970b01a73d5e76e3970d-pi

“The National Weather Service said around 9 a.m. Buoy [51]101, […],reported an ocean swell of 31 feet at 17 seconds. That translates to 50+ feet on the north shore[Buoy 51201] around 7 p.m.”

(http://www.hawaiinewsnow.com/story/24509382/forecasters-issue-high-surf-warning-predict-40-50-foot-waves)

40-50ft waves at reefs

(http://www.hawaiinewsnow.com/story/24509382/forecasters-issue-high-surf-warning-predict-40-50-foot-waves)

(http://www.hawaiinewsnow.com/story/24509382/forecasters-issue-high-surf-warning-predict-40-50-foot-waves)

(http://www.hawaiinewsnow.com/story/24509382/forecasters-issue-high-surf-warning-predict-40-50-foot-waves)

Image and data source http://www.ndbc.noaa.gov/obs.shtml

Station 51201Pacific Islands Ocean Observing System Location: 21.669N 158.12WStation 51101NDBCLocation: 24.321N 162.058W

5120151101

30ft open ocean swell on Jan 22nd, 2014!

Exploring relationships between two (or more) variables

At a location two variables form a pair of coordinates (each sample point in the time seriesbecomes a point in the 2-dimensional space).

Exploring relationships between two(or more) variables

At a location two variables form a pair of coordinates (each sample point in the time seriesbecomes a point in the 2-dimensional space).

Scatter plots can help to detect outliers, or different cluster groups in data samples

Exploring relationships between two (or more) variables

Here the same variable (significant wave heights, left; dominant wave periods, right) from two different observing stations are plotted in a scatter-plot

Exploring relationships between two (or more) variables

Here the same variable (significant wave heights, left, dominant wave periods) from two different observing stations are plotted in a scatter-plot

Buoy NW of Hawaii haslarge waves when waves in Hawaii are (still) small

Exploring relationships between two(or more) variables

The buoy data are shifted by 12 hours(+12h lag in the buoy data from Hawaii)

500 km

51101

51201

Swell direction

Swell direction

12h shift: Correlation Is maximum when we shiftthe time series by two 12h

500 km

Swell direction

Swell direction

12h shift: Correlation Is maximum when we shiftthe time series by two 12h

500 km

Ocean Wave Theory:

t=4 *pi *X/(gT)

Distance X= 500kmPeriod: T=17sg=9.81m/s^2=> Travel time t approx 11h