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Greenwich wave buoy observations on Fri, Sep 21, 2018

Hourly readings from the Greenwich wave buoy for Fri, Sep 21, 2018, including available wave height, period, direction, wind and sea temperature data.

Last observation shown

Oldest observation available

Daily means for

Latest

Period Summary

Programmatically generated summary. Hog Says

24 wave-buoy observations were recorded during the day. Typical wave height was 8.7 ft (10th–90th percentile 6–9.8 ft), while mean reported wave period; measurement type unavailable was 7.5 seconds (10th–90th percentile 7–8 seconds). Typical wind was 38 mph (10th–90th percentile 32.5–43.1 mph) and mean water temperature was 17.5°C (10th–90th percentile 17.3–17.8°C). 2 of 120 checked values (1.7%) were excluded by quality control.

Generated only from the observations and comparisons shown on this page.

Line chart showing wave height, wave period and sea temperature for Greenwich. Use the detailed observations table below for the same data in text form.

About Greenwich wave buoy

Greenwich Lightship (WMO 62305) is a UK Met Office station in the southern North Sea on the Greenwich meridian. It monitors marine conditions between the Dover Strait and the Thames approaches. The station feed can include wind, wave height, pressure, visibility, and air and sea temperature.

Metrics are rows; hours run left to right. Times use your device time zone.
Greenwich wave buoy hourly observations Fri, Sep 21, 2018Last observation shown
Metric
Wave height (ft)5667810111011109878899101010109QC rejectedQC rejected
Observed period(s)7Reported7Reported7Reported7Reported7Reported7Reported7Reported8Reported8Reported8Reported8Reported7Reported8Reported7Reported8Reported8Reported8Reported8Reported7Reported7Reported7Reported8Reported7Reported8Reported
Wave power(kW/m)------------------------
Wind directionSSWSSWSSSWWWWNWWNWWNWWNWWNWWWWWWWWWWWWNWWNWWNW
Wind speed (mph)443939443938414538363834374137383837333732342928
Water temperature(°C)17.717.817.817.817.717.617.617.417.417.317.317.417.417.417.417.417.417.517.417.417.317.317.217.2

Swipe sideways to see more hours.

Wave metric colour key

Colours move through the scale as each number increases. They do not by themselves mean that conditions are good, safe or suitable for you.

Wave & swell height0–40+ ft
Wave & swell period0–22+ s
Wind speed0–75 mph

The displayed numbers remain the source of truth; colour is an additional visual cue.

Which wave period is shown?

The table shows the best period measurement supplied for each observation. It is not necessarily the energy period used to calculate wave power.

Tp
Peak period: the period at the strongest spectral peak.
Tavg
The provider's average wave period.
Tm02
A mean period calculated from the wave spectrum.
Tz
Mean zero-crossing period.
Reported
A legacy value whose period type was not recorded.
Mixed
A daily or monthly mean containing more than one period type.

Wave power needs a genuine energy period (Te). SurfHog does not substitute Tp, Tavg, Tm02 or Tz when Te is missing.

What does buoy wave power mean?

kW/m means kilowatts of wave power per metre of wave crest. It describes the rate at which the observed sea state carries energy past the buoy.

Unlike the shore-directed forecast value, buoy wave power is the total power at the observation point. It is not projected towards a particular beach and does not predict breaking wave height.

In deep water, wave power can be calculated with:

P is approximately 0.49 times significant wave height squared times wave energy period.

P is power in kW/m, Hs is significant wave height in metres, and Te is wave energy period in seconds.

  • Provider-reported power is used when available.
  • Otherwise, a value is calculated only when both significant height and a genuine energy period are available. The ≈ symbol marks calculated values.
  • A dash is shown instead of substituting peak, Tm02, zero-crossing or other period measurements.
  • Daily and monthly figures use the mean of hourly-normalized observation power values; they are not calculated from mean height and period.

Wave direction, spectrum, water depth and local bathymetry still matter. Wave power is best read alongside height, period and direction rather than as a standalone surf-quality score.

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