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


Right- skewed distributionWith long tail towards highwaves

~hourly data reporting Significant wave heightsDecember 2013-Feburary 2014


Less skewed distribution than wave heights.

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



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





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


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


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

51101

Documents

system location

ndbc location

data source http

pacific islands ocean

reefs http

variablesthe buoy data

058w512015110130ft open

different observing