We hear, see, and read the sea.
Beyond chemistry, AERIEL listens for engines and whales, images reefs band by band, samples the water's own DNA, and fuses ship traffic from sky to surface. Five sensing modalities, one fused picture into NEREID.
Sensing Array
The multi-modal sensing suite that extends the AquaLink Mesh beyond point chemistry — hydroacoustic, optical, genetic, and orbital — all carried by the Mesh Data Fabric to NEREID.
1. Overview
AquaLink chemistry tells us the state of the water; the Sensing Array tells us what moves through it and what threatens it. Five modalities run in parallel — hydroacoustic, optical/hyperspectral, genetic (eDNA), traffic fusion (AIS/radar), and satellite — each registered to a common time and grid by the Mesh Data Fabric, then fused by NEREID into a single situational picture spanning the Breeding Station and the gyre stations.
2. Sensor Modalities
| Modality | What It Detects | Platform | Cadence | Feeds |
|---|---|---|---|---|
| Passive hydroacoustic | Vessel signatures, cetacean vocalizations, ambient noise | Moored hydrophone arrays · drift buoys | Continuous | AE-MET-044 · AE-MET-047 |
| Active sonar | Hull contacts, seabed bathymetry, biomass shoals | 9 gated sonar heads (duty-limited) | On-task / scheduled | AE-MET-047 |
| Optical / hyperspectral | Reef photomosaic, coral bleaching, turbidity plumes | ROV & gantry imaging heads, drift cams | Full-grid ≤ 6 h | AE-MET-002 · AE-MET-003 · AE-MET-007 |
| eDNA samplers | Species presence, invasive arrivals, spawning events | Autonomous in-situ filtration cartridges | 4× daily / event-triggered | AE-MET-043 |
| AIS / radar fusion | Vessel tracks, AIS-gap (dark) targets, course anomalies | Shore radar, station AIS rx, sat-AIS | Continuous | AE-MET-019 · AE-MET-047 |
| Satellite SST / chlorophyll | Sea-surface temperature anomaly, bloom & productivity | Polar-orbit thermal/ocean-colour downlink | Per overpass (≈ 6 h) | AE-MET-012 · AE-MET-056 |
3. Hydroacoustics
The passive array is the array that never blinks. 112 hydrophones across moored arrays and drift buoys listen continuously across 10 Hz – 180 kHz, classifying contacts in two registers: anthropogenic (engine cavitation, propeller blade-rate) and biological (cetacean calls, snapping-shrimp ambient). NEREID matches engine signatures against a known-hull library and flags any acoustic contact without a matching AIS track.
| Attribute | Specification |
|---|---|
| Passive bandwidth | 10 Hz – 180 kHz, 24-bit, 384 kS/s |
| Detection range (vessel) | Typ. 8 – 22 km, sea-state dependent |
| Cetacean classifier | Per-species call templates; logs whale presence for routing advisories |
| Active sonar duty | Gated & power-limited near marine-mammal detections (mitigation interlock) |
| Bearing accuracy | ±2° single array; sub-degree on multi-array triangulation |
4. Optical & Hyperspectral
ROV and gantry heads sweep push-broom hyperspectral lines (380–2500 nm) co-bored with broadband imagers to build a registered reef photomosaic every 6 hours. From the radiance cube NEREID derives live-cover, a bleaching index, and turbidity — early warning of a reef in stress before it whitens to the eye.
| Product | Derives | Alarm Band | Metric |
|---|---|---|---|
| Live reef cover | % hard-coral cover per quadrat | < 35% → watch | AE-MET-002 |
| Bleaching index | Spectral whitening 0–6 scale | ≥ 4 → critical | AE-MET-003 |
| Turbidity plume | Backscatter NTU mapping | > 8 NTU → watch | AE-MET-007 |
| Outplant survival | Per-cluster survival of restoration coral | declining trend → flag | AE-MET-043 |
5. eDNA Samplers
Autonomous in-situ samplers filter and preserve environmental DNA on a 4×-daily cadence, escalating to event-triggered sampling on a spawning cue or an unexpected acoustic contact. NEREID screens the genetic signal for target-species presence, invasive arrivals, and spawning confirmation — a census the camera and hydrophone cannot give. Cartridges are logged as evidence-grade and chain-of-custody preserved through the fabric.
6. AIS / Radar Fusion & Satellite
Shore radar, station AIS receivers, and sat-AIS are fused into a single track picture. The high-value product is the negative: a radar or acoustic contact with no corresponding AIS broadcast — a vessel running dark. These AIS-gap detections (AE-MET-019) are the front end of interdiction tasking. Satellite overpasses add the wide view: sea-surface-temperature anomaly (AE-MET-012) for bleaching forecast and chlorophyll-a (AE-MET-056) for productivity and bloom watch.
7. Fusion into NEREID
All five modalities register to common PTP time and grid, then NEREID cross-checks them: an acoustic contact without an AIS track, a bleaching index that disagrees with SST anomaly, an eDNA hit absent from the camera. Divergence beyond tolerance raises a sensor-trust flag and routes per Alarm Escalation (AE-MON-0040). Units and definitions live in Conservation Metrics.