---
title: "Oceans, explained | Nexus Observatory"
description: "Interactive explainer: oceans, coasts and maritime in 3D, chapter by chapter. Wave buoys and tide gauges, profiling floats and coastal water quality…"
url: https://observatory.global/industries/oceans/explainer/
publisher: Nexus Observatory Inc.
updated: 2026-11-02
---

Overview 

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Environment and climate. Flux tower; Smoke network; Methane fenceline; River sonde reach; Acoustic grid

Environment and climate · Sector explainer

Explainer

# Measured, reported, verified.

Methane at the fenceline, carbon over the canopy, sound in the forest, chemistry in the river, smoke over the town. Each chapter puts one deployment on the stage, lets you change the input that drives the design, and computes what changes.

**Chapters**: 6
**Deployments**: 5
**Readouts**: 25
**Scale**: 1:1 metres

**01** Methane fenceline

**02** Acoustic biodiversity

**03** Flux tower

**04** River sonde

**05** Smoke network

**06** Proof

**01** · Methane fenceline

Dispersion

## Put the sensor where the plume goes.

A production pad inside its fenceline. Continuous methane sensors sit on the fence at a fixed spacing; the wind decides which of them sees a release from the separator. Turn the wind and change the spacing: the plume width at the fence is computed from a Gaussian dispersion width, and the red count is the sensors that sit inside it.

**Fence perimeter**: 760 m
**Sensors on the fence**: 17
**Source to fence, downwind**: 127 m
**Plume width at the fence (±2.15σy)**: 43 m
**Sensors inside the plume**: 1

Plume width from the Briggs open-country spread for neutral air, σy = 0.08x(1 + 0.0001x)^−0.5 at x metres downwind; ±2.15σy holds the plume to a tenth of its centreline concentration.

**02** · Acoustic biodiversity

Computed

## A grid of ears over one square kilometre.

Autonomous recorders on a square grid inside a one-square-kilometre forest plot. Each records what it can hear within an effective detection radius, set by the species call, the vegetation and the background noise. Change the spacing and the radius: the share of the plot inside at least one radius is computed on a 200 × 200 sample grid.

**Recorders in the plot**: 16
**Area heard by one recorder**: 4.5 ha
**Plot within a detection radius**: 72.2 %
**Unheard area**: 27.8 ha

Coverage counted on a 5 m lattice across the 100 ha plot. Detection radius is set in the field with playback at known distances, per species group and habitat.

**03** · Flux tower

Computed

## The tower sees what is upwind of it.

An eddy-covariance tower above a forest canopy: a sonic anemometer and a gas analyser at the top, sampling ten or twenty times a second. The flux it reports comes from a footprint upwind, and that footprint grows with the height above the canopy. Change the canopy and the measurement height to see the footprint move.

**Displacement height d = 0.67h**: 13.4 m
**Effective height z − d**: 20.6 m
**Peak contribution, 5–10 (z − d)**: 103–206 m
**Fetch for most of the flux, ~100 (z − d)**: 2,060 m
**Above canopy**: 14 m

Displacement height d ≈ 0.67 × canopy height; in neutral air the footprint peaks 5–10 (z − d) upwind and most of the flux comes from within about 100 (z − d). Site design runs a footprint model such as Kljun et al. (2015) on measured turbulence.

**04** · River sonde

Computed

## Stage in, discharge out.

A water-quality sonde in a cage at the bank of a gauged reach: turbidity, conductivity, dissolved oxygen and pH, sent by telemetry. Its readings mean more alongside flow, and flow comes from the stage through the station's rating curve. Raise the stage to see the water rise and the discharge follow the curve.

**Discharge Q**: 18.0 m³/s
**Wetted area**: 26.9 m²
**Mean velocity Q/A**: 0.67 m/s
**Top width**: 24.8 m

Rating curve Q = 18(h − 0.2)^1.6 on a trapezoidal reach, 20 m bed, side slopes 2:1. Each station fits its own curve from measured discharges.

**05** · Smoke network

Computed

## Smoke, read on the health scale.

Low-cost particulate sensors on poles across a town, corrected against a reference station. During a wildfire the network reports fine particulate matter, and the public reads it as an air quality index. Move the 24-hour PM2.5 concentration to see the index, the category and the smoke layer the scene draws for it.

**Air quality index**: 117
**Category**: Unhealthy for sensitive groups
**Breakpoint band**: 35.5–55.4 µg/m³

US EPA index for 24-hour PM2.5 with the 2024 breakpoints, interpolated linearly inside each band. Optical sensors are corrected for humidity against a reference monitor before they report.

**06** · Proof

Computed

## Uncertainty, stated before anyone asks.

What a regulator or a verifier asks to see, from the sector research. It starts with uncertainty. Sensors co-located with a reference instrument average down their random error; a shared bias does not average away, which is why calibration is a record, not a promise.

- Regulator acceptance
- Third-party verification
- Uncertainty quantification
- Reconciliation at the highest reporting level
- Open methods

**Random error of the mean σ/√n**: 5.3 %
**Shared bias (does not average)**: 5.0 %
**Combined standard uncertainty**: 7.3 %
**Expanded uncertainty, k = 2**: 14.6 %

Independent random error averages as σ/√n; a bias shared by every sensor stays and adds in quadrature. Expanded uncertainty with coverage factor k = 2, as in JCGM 100:2008.

## Measurement a verifier can reproduce.

Survey, design, deployment and operation of environmental observing networks: methods on the record, uncertainty stated, data that reconciles at the highest reporting level.

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