Instruments

How the readings are made

Bluegraph's readings come from moored buoys, coastal weather stations, tide gauges, estuary sensors and radars on the shore. Each page here explains one kind of instrument: what it measures, where its sensors are, and how it makes each measurement. A 3D drawing of the instrument lets you rotate it, look inside and watch it work.

Stations: 740
Instrument types: 13
Drawn: 13
Census: October 2026

Drawn

Open one to rotate it, look inside and watch it work.

Moored buoy · NDBC The 3-meter discus buoy An aluminum disk with the SCOOP payload: weather sensors on a low frame, and waves calculated from the hull's own motion.

Hull: 3.0 m across
Wind: 3.8 m up
On Bluegraph: 38 buoys

Moored buoy · NDBC The 3-meter foam buoy A ring of ionomer foam clamped around an aluminum well. It carries the same SCOOP payload as the discus, higher up on a triangular frame.

Hull: 3.0 m across
Wind: 4.1 m up
On Bluegraph: 38 buoys

Moored buoy · NDBC The 2.1-meter ionomer foam buoy A solid hull of foam wound in layers, with the whole SCOOP payload set into it. It is smaller and lighter than the 3-meter discus.

Hull: 2.1 m across
Wind: 3.2 m up
On Bluegraph: 10 buoys

Moored buoy · NDBC The 2.3-meter foam discus buoy A circular foam hull with vertical sides that carries SCOOP on a four-post tower. It is moored on the Great Lakes from spring until the lakes freeze.

Hull: 2.3 m across
Wind: 3.6 m up
On Bluegraph: 4 buoys

Moored buoy · ECCC ECCC's 3-meter discus buoy The same aluminum disk as NDBC's, with ECCC's own tower, the payload inside the hull, and chain for ballast.

Hull: 3.0 m across
Wind: 5 m up
On Bluegraph: 22 buoys

Moored buoy · ECCC The 6-meter NOMAD buoy ECCC's boat-shaped aluminum buoy, moored by the bow in deep water. It swings to face the waves and pitches more than it rolls.

Hull: 6 m long
Wind: 5 m up
On Bluegraph: 6 buoys

Wave buoy · Datawell The Datawell Waverider A steel sphere 0.9 m across, moored on a rubber cord so that it circles with the water as each wave passes.

Hull: 0.9 m sphere
Mooring: 30 m rubber cord
On Bluegraph: 77 buoys

Wave buoy · Sofar Ocean The Sofar Spotter A small solar-powered buoy that measures waves by using GPS to track its own motion east, north and up.

Hull: 42 cm across
Motion: GPS, 2.5 Hz
On Bluegraph: 4 buoys

Coastal station · NDBC and partners The coastal weather station Weather sensors on a lighthouse in Chesapeake Bay: two anemometers 18 m up, a shaded thermometer, and an hourly report by satellite.

Drawn: Thomas Point, MD
Wind: 18 m up
On Bluegraph: 172 stations

Water level station · CO-OPS The tide gauge A radar on a pier measures the water level once a second. Six-minute averages, tied to benchmarks on land, give the tide and its residual.

Sensor: Radar, 10° beam
Value: Mean of 360, every 6 min
On Bluegraph: 226 gauges

Water quality · NERRS The water-quality sonde A multiparameter sonde in a perforated tube on a piling that measures the estuary's water every 15 minutes.

Sonde: 70.5 cm long
Readings: Every 15 min
On Bluegraph: 37 stations

Weather · NERRS The estuary weather station A tower of weather sensors and a logger that samples every 5 seconds and records 15-minute averages.

Wind: 6.1 m up
Records: Every 15 min
On Bluegraph: 28 stations

Shore radar · IOOS HF radar surface currents Radars on the shore measure the surface current tens of kilometers offshore, from the Doppler shift of their echo off ocean waves half as long as their radio waves.

Radars: About 180
Grid: 2 and 6 km
Stations: 130

What the stations are

Bluegraph's stations, grouped by the instrument that makes their readings. Buoys are grouped by the hull named on their NDBC station pages, and the other stations by Bluegraph's own station list (October 2026).

Instrument	Operated by	Stations
Moored buoys		277
3-meter discus	NDBC	38
3-meter discus	Environment and Climate Change Canada	22
3-meter foam	NDBC	38
2.1-meter ionomer foam	NDBC	10
2.3-meter foam discus	NDBC	4
6-meter NOMAD	Environment and Climate Change Canada	6
Waverider	Partners	77
Spotter	Partners	4
Hull not named	Partners	69
Hull not named	Environment and Climate Change Canada	8
Hull not named	NDBC	1
Coastal stations		172
Coastal weather station	Marine Exchange of Alaska	67
Coastal weather station	National Weather Service offices	35
Coastal weather station	NDBC (C-MAN)	33
Coastal weather station	Texas Coastal Ocean Observing Network	18
Coastal weather station	Federal Aviation Administration	9
Coastal weather station	Universities and laboratories	7
Coastal weather station	NOAA National Ocean Service	3
Tide gauges		226
Tide gauge	NOAA CO-OPS	226
Estuary stations		65
Water-quality sonde	National Estuarine Research Reserves	37
Weather station	National Estuarine Research Reserves	28
Surface currents shown at stations above, not counted again
HF radar	IOOS regional partners	130