🌊 The Camp Ellis Wave Buoy

Wave height

What it is: "Significant wave height": the average height of the biggest third of the waves, trough to crest. It is close to what an experienced sailor would estimate by eye.

Why it matters: Wave height drives beach erosion, coastal flooding and safe boating. A few big storms each year do most of the work of moving sand along the coast.

📏 Under 1 ft: calm. 1–3 ft: normal. Over 3 ft (1 m) for hours: a storm event here. Single waves can be about twice the significant height.

📍 Here: typically 1.0 ft; biggest so far 10.3 ft. A "storm event" on this page = waves ≥ 3.3 ft (1 m) for 6+ hours.

Wave period (rhythm)

What it is: Seconds between one wave crest and the next.

Why it matters: Short-period waves (under ~6 s) are choppy and made by local wind. Long-period swell (10 s or more) was made by a distant storm, carries much more energy for its height, and reaches farther up the beach.

📏 Tip: count the seconds between waves at the beach — that is the period.

Wave direction

What it is: The compass direction the waves are coming from (like wind direction).

Why it matters: Direction decides which beaches take the hit and which way sand is pushed along the shore.

📏 "E" means waves rolling in from the east.

Wave energy

What it is: How much energy the waves carry toward shore, per metre (or foot) of coastline. It grows with the square of wave height and with the period.

Why it matters: It is the best single measure of how hard the ocean is working on the coast — useful for erosion studies.

📏 1 kWh ≈ running a microwave for an hour.

Air pressure

What it is: The weight of the air above, in hPa (hectopascals) or kPa (1 kPa = 10 hPa).

Why it matters: Falling pressure usually means a storm or front is coming; rising pressure means clearing weather. Very low pressure also lets the sea rise a little higher (storm surge).

📏 ~1013 hPa (101.3 kPa) is average. Under ~1000 hPa usually means a storm.

Wind

What it is: Average wind speed, the strongest gust, and the direction the wind is blowing from.

Why it matters: Wind builds waves, pushes water against the shore, mixes oxygen into the water and dries out soils.

📏 Light: under 10 mph. Breezy: 10–20 mph. Strong: 25+ mph. Gale: 39+ mph.

📍 Here: this buoy has no wind vane — it estimates wind from the shape of the waves, so treat it as approximate, especially in light winds.

Water temperature

What it is: How warm or cold the water is, measured by a sensor just below the surface.

Why it matters: Temperature controls almost everything in the water: how much oxygen it can hold, how fast algae grow, which fish and shellfish are comfortable, and when lobsters and other animals move or molt.

📏 Gulf of Maine coastal water runs roughly 38–45 °F (3–7 °C) in late winter and 60–68 °F (15–20 °C) in late summer. Shallow ponds and marshes swing much more, warming fast on sunny days.

Dissolved oxygen

What it is: Oxygen gas dissolved in the water — the oxygen that fish, crabs, clams and worms breathe through their gills or skin. Shown in mg/L (milligrams per litre), and sometimes as % saturation: 100% means the water holds as much oxygen as it naturally can at that temperature and saltiness.

Why it matters: Low oxygen stresses or kills marine life. It drops when water is warm, still, or full of decaying plant material, and it swings up and down every day because algae make oxygen in sunlight and everything uses it up at night.

📏 Above 5 mg/L: healthy. 2–5 mg/L: stressful for many species. Below 2 mg/L: hypoxic — most fish leave or die. Saturation above 100% means algae are photosynthesising hard.

Current

What it is: How fast and in which direction the water itself is moving, measured below the buoy.

Why it matters: Currents carry larvae, nutrients, sediment and pollution, and matter for swimmers and boaters.

📏 Tidal currents here typically reach a few tenths of a knot; 10 cm/s ≈ 0.2 knots.

Tide / water level

What it is: The height of the water surface. Along the Maine coast the sea rises and falls about 9 feet twice a day (every ~12 h 25 min), pulled by the Moon and Sun.

Why it matters: The tide moves water — and everything in it — back and forth past a sensor, so many readings change with the tide. In marshes and ponds, water level shows how often the tide floods in and how high storms push it.

📏 Heights on tide charts are measured above average low tide (MLLW). Storms and strong onshore winds can push water higher than predicted.