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Greenwich wave buoy daily means for Mar 2018

Daily means from the Greenwich wave buoy for Mar 2018, including available wave height, period, direction, wind and sea temperature data.

Last observation shown

Data available:  to 

Monthly means for

Latest

Period Summary

Programmatically generated summary. Hog Says

601 wave-buoy observations covered 30 of 31 days (97%). Typical wave height was 2.3 ft (10th–90th percentile 1.3–4.3 ft), while mean reported wave period; measurement type unavailable was 6.4 seconds (10th–90th percentile 5–8 seconds). Typical wind was 19.7 mph (10th–90th percentile 8.1–28.9 mph) and mean water temperature was 8.1°C (10th–90th percentile 7.6–8.4°C). 26 of 3,005 checked values (0.9%) were excluded by quality control. Across 7 comparable years, mean wave height was below the same-month mean of 2.8 ft and mean wave period was below the same-month mean of 6.5 seconds.

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

Typical Wave Height

2.3ft
Mean: 2.6 ft
P10–P90: 1.3 — 4.3 ft
Recorded extremes

0 — 7.5 ft

Available for 597 of 601 hourly samples

Mean Wave Period

6.4secs
P10–P90: 5 — 8secs
Recorded extremes

4 — 10secs

Available for 584 of 601 hourly samples

Mean Water Temperature

8.1°C
P10–P90: 7.6 — 8.4°C
Recorded extremes

7 — 9.3°C

Typical Wind

SSE, 19.7mph
Mean: 18.9 mph
P10–P90: 8.1 — 28.9 mph
Recorded extremes

1.1 — 57.5 mph

Circular concentration: 32%

Available for 596 of 601 hourly samples

Compared With Previous Marchs

Historical baseline from 4,741 observations across 7 years.

Wave Height
2.6ft
0.2ft below mean
Historical mean 2.8ft
Wave Period
6.4s
0.1s below mean
Historical mean 6.5s
Water Temperature
8.1°C
0.8°C below mean
Historical mean 8.9°C

Chart showing grouped wave observations for Greenwich. Use the table on this page for a text version of the same measurements. To open hourly observations, use a linked day name in the table.

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; days run left to right.
Greenwich wave buoy daily means Mar 2018Last observation shown
Metric
Mean wave height (ft)-422222QC rejected22243233444212432122333
Mean observed period(s)-6Reported5Reported5Reported6Reported5Reported6Reported6Reported6Reported6Reported9Reported7Reported7Reported6Reported7Reported8Reported7Reported6Reported6Reported6Reported6Reported6Reported6Reported8Reported9Reported8Reported6Reported6Reported6Reported6Reported6Reported
Mean wave power(kW/m)-------------------------------
Mean wind direction-ESEconcentration 75%ESEconcentration 88%Sconcentration 89%SSEconcentration 80%Sconcentration 53%WSWconcentration 79%WSWconcentration 85%SSEconcentration 79%Sconcentration 77%ESEconcentration 78%WSWconcentration 56%Wconcentration 88%SSEconcentration 88%SSEconcentration 89%Sconcentration 63%NEconcentration 85%ENEconcentration 85%ENEconcentration 89%NEconcentration 85%NNEconcentration 62%NNEconcentration 46%SSEconcentration 91%Econcentration 63%NEconcentration 79%Variableconcentration 25%Variableconcentration 22%Variableconcentration 19%SSEconcentration 78%SEconcentration 51%WSWconcentration 70%
Mean wind speed (mph)-2624202314202717201527192322162223161414241915791913181519
Mean water temperature(°C)-7.27.57.67.77.87.97.98.08.18.38.28.28.28.48.58.27.57.57.67.98.08.18.28.38.58.38.38.28.28.2

Swipe sideways to see more days.

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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