Underwater Acoustic Prediction · iPad · iPhone · Mac

Ægir

Know the Sea·Own the Depths

Sound travels where light cannot. Drop a pin on any blue water and watch how it carries — the ray paths, the loss with range, the noise it raises around you — worked out on the iPad in your hands, before you leave the pier.

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Chapter I

The Three Questions

How far will the sound carry? What will it expose in the water around you? What is the noise floor where you are working? One answer, drawn from the real water column — bathymetry, sound speed, seabed and ambient noise — and it shifts hour to hour, basin to basin, and depth to depth.

Until now, that answer lived on a shore-based PC, in a tool licensed by the seat — chained to a desk, a network, and a vendor's release schedule. Ægir Prediction puts it in your hands — on the iPad at the rail, the iPhone in your pocket, the Mac at your desk. Every line of physics running offline on Apple silicon. Every byte of bundled data public-domain or permissively licensed.

01 · PROPAGATION
How Far Will It Carry?
Trace the ray paths and the transmission loss out to range — for survey planning, sonar performance, or a research figure.
02 · EXPOSURE
What Will It Expose?
Weight the sound field to marine-mammal and fish hearing groups and read the impact ranges — the underwater-noise question behind every marine EIA and pre-piling watch.
03 · ENVIRONMENT
What's the Water Doing?
Sound speed, seabed loss, ambient noise and currents — read the conditions under your pin before you commit a vessel day.
Chapter II

What You'll See at the Rail

A ray fan. A transmission-loss field. Impact ranges in metres. The ambient-noise floor in dB. The readouts you actually work with — drawn live on every Apple device you carry. Touch on iPad. Pocket-glance on iPhone. Mouse-and-keyboard precision on Mac. One model state, three surfaces.

Ægir Prediction on iPad Pro — ray-path fan and sound-speed profile over a transmission-loss field. Ægir Prediction on iPhone — transmission-loss field over the Iberian shelf.

● Real screenshots · iPad Pro 13″ & iPhone 17

Noise-exposure footprint drawn over a real coastline, with source and receiver geometry and mitigation zones.
Noise-impact field
EXPOSURE · MITIGATION ZONES
Water-column panel with temperature, salinity and sound-speed profiles.
Water column
TEMP · SALINITY · SOUND SPEED
Seafloor panel showing sediment class, mean grain size and bottom loss over a sediment map.
Seafloor & bottom loss
SEDIMENT · GRAIN SIZE · BL
·
Offline-first
Bundled GEBCO bathymetry and WOA23 climatology cover the whole world ocean. The ray solver runs locally on Apple silicon — your answer in well under a second, no shore link, no round-trip.
·
Mariner units
Feet, fathoms, nautical miles and DMS are first-class. Tap to cycle to metric or MGRS — the model stays in SI underneath.
·
Public-domain physics
Every line of acoustics re-implemented in Swift from Jensen / Kuperman / Porter / Schmidt. No GPL Bellhop, no licensed binaries — just the textbook equations, auditable end-to-end.
Chapter III

One Model · Every Device

The same scenario, the same physics, on whichever Apple device is to hand. Build it on the Mac at home, refine it on the iPad at the rail, check it on the iPhone on the way out. With iCloud sync on, the scenario stays in step across all three; the computation always runs locally and offline, on the device you're holding. Nothing to re-learn, nothing to re-enter — one model, three windows onto it.

MAC Ægir Prediction on a MacBook Pro — the project landing screen.
IPAD Ægir Prediction on iPad Pro — offshore-platform acoustic screening with source levels.
IPHONE Ægir Prediction on iPhone — coastal bathymetry chart with the probe pin.

One scenario · three form factors · optional iCloud sync · always computed on-device

MAC · AT HOME
Build & Report
Lay out and review scenarios on a big screen. Pointer-precision drag, a fresh scenario in a keystroke, the methodology exported in one tap, two scenarios side by side in separate windows.
IPAD · ON THE WATER
Work on Station
Drop the source pin at the rail and recompute on station as conditions change. Touch-first chrome tuned for low-light shipboard and field use — backlight down, gloves on.
IPHONE · ON THE GO
Check Anywhere
Glance at an impact range or the noise floor between tasks, and share a readout straight into an email or report — the whole model in your pocket.
Chapter IV

Eight Modules · All Offline

The full prediction stack ships in the baseline app — bathymetry through noise-impact ranges. Live services sharpen the answer when a connection exists; nothing requires one.

M01
Bathymetry
GEBCO 2025 sub-ice, 5-arc-min global, plus 0.25° regional packs.
BUNDLED GLOBAL
M02
Sound-Speed
WOA23 climatology through the Mackenzie 1981 equation — 24-level global, 72-level HQ packs by region.
BUNDLED + LIVE
M03
Seafloor Loss
Dutkiewicz 2015 sediment classes drive APL-UW TR 9407 reflection loss, per bottom bounce.
BUNDLED GLOBAL
M04
Absorption
Francois–Garrison 1982 from the temperature, salinity and pH of the WOA23 column.
PHYSICS-BASED
M05
Ambient Noise
Wenz 1962 — wind / sea-state, rain and shipping-density components.
LIVE NOAA WIND
M06
Ray Paths & TL
Gaussian-beam ray solver written in Swift, per Jensen / Kuperman / Porter / Schmidt.
NO BELLHOP / GPL
M07
Noise Impact
NMFS 2024 & Southall 2019 hearing-group weighting, pile-driving mitigation and impact ranges for marine mammals and fish.
EIA · MMO
M08
Methodology Export
One-tap export of the methods, parameters and data sources behind any prediction.
ONE-TAP
Chapter V

Pin → Prediction

Five phases, one pass, on-device. From the long-press on the chart to the transmission-loss field and weighted impact ranges, in a few seconds on the full fan.

PHASE 01
Resolve column
Mask-aware bilinear lookup pulls bathymetry, SSP and sediment under the pin from on-device packs.
→ resolveColumn(pin)
PHASE 02
Compute SSP
Mackenzie 1981 sound-speed equation applied to the WOA23 T/S column. Optional diurnal SST overlay.
→ ssp(T, S, p)
PHASE 03
Trace rays
Eikonal-style fan from source ±N°, with surface, bottom and convergence-zone classification per ray.
→ traceFan(ssp, bathy, ang)
PHASE 04
Sum the losses
Geometric spreading + Francois–Garrison absorption + per-bounce seabed loss build the transmission loss; Wenz sets the ambient-noise floor.
→ tl + noise floor
PHASE 05
Weight · read out · export
Hearing-group weighting turns the field into impact ranges; Swift Charts and MapKit draw it; one tap exports the methodology.
→ weight · draw · export
RAY FAN ±15°SOURCE 100m · BOTTOM 3300m
SURFACE BOTTOM SRC
SSPWOA23 · 24-LVL
0 m 3300 m 1490 m/s
TL STRIP3.5 kHz
60 dB 90 dB CZ
Chapter VI

Don't Take Our Word for It

You've seen what it predicts and how. Now drive it yourself: this is a live, working miniature of the prediction console — running right here in your browser on a synthetic Norwegian Sea. Watch the Norwegian Atlantic Current ride the shelf break. Then open the full simulator: drop the source pin, scrub the water column, and trace the rays.

● LIVE RENDER SYNTHETIC DEMO DATA

Enter the Simulator

Bathymetry isobaths · current drift · ray fan · TL field · water column · ambient noise — all interactive, all dummy data.

›
Chapter VII

Onboard the Preview

A short request, a TestFlight invite, and you're in. Every capability is open during the preview.

aegir-onboard ~ /preview
$ aegir invite --request
▸ generating one-time TestFlight code…
REQ
iPadOS / iOS / macOS 26+
Runs on iPad, iPhone and Apple-silicon Mac. iPad landscape-first; iPad portrait and iPhone also supported.
REQ
~250 MB
Baseline IPA with global climatology. Regional packs add 200 MB–1 GB each.
REQ
Optional online
Live wind/SST is fetched only when reachable. Everything else is offline.
REQ
No tracking
No analytics, no telemetry. Crash reports are opt-in via TestFlight.
Coming with v1.0

Editions

Every preview tester gets every capability today. When paid features arrive, the core tool stays free — plus two independent one-time unlocks: Ægir Live for live ocean data, Ægir Pro for the formal report and compliance exports. No subscriptions, ever.

Free Ægir Live Ægir Pro
The full offline toolfree, forever One-time unlockall live ocean data One-time unlockthe deliverable layer
Ray paths, transmission loss & Signal-Excess field✓✓✓
Impact ranges — NMFS 2024 · Southall 2019 · Popper 2014✓✓✓
Bundled global data — GEBCO · WOA23 · sediment✓✓✓
Ambient-noise spectrum · unit tools · local save✓✓✓
Draft Brief Sheet (watermarked)✓✓✓
Clean Brief Sheet — un-watermarked PDF——✓
Live ocean data — HYCOM nowcast · currents / drift · GFS wind / wave / SST—✓—
Formal EIA Report · 8-page Methodology PDF · compliance exports——✓
iCloud scenario sync—✓✓

Ægir Live and Ægir Pro are independent one-time purchases — own either, both, or neither. A Pro buyer's Formal Report is stamped on WOA23 climatology, so Pro never requires Live. Organisation / volume licensing via Apple Business Manager.