Onboard Data Processing

The on-board processing pipeline takes raw accelerometer and GPS samples captured by the buoy and reduces them — on the buoy itself — into a compact summary that fits inside an Iridium short-burst-data message: significant wave height, peak period, directional spectrum, energy bands.

Doing the maths on the buoy (rather than transmitting raw samples) is what makes long-duration polar deployments practical — satellite bandwidth is expensive, power-hungry, and unreliable.

The maths code is written in C and compiles for any Linux. On the buoy it runs on the Maths Control host (a low-power Linux board woken briefly to do the calculation), described below.

• Maths control — Linux services, Raspberry Pi image, debug web UI, and the automation around the maths-CPU that schedules wakes, runs the C code, and packages the output for the Iridium uplink.

Wave-motion mathematics

The wave-motion mathematics — significant wave height, peak period, spectral and directional analysis — was developed by Dr Alison Kohout (NIWA) and collaborators, and is the scientific core of the WII project. Her work is documented and partly open at:

Waves in Ice — Alison Kohout’s project page

Covers the WIIOS sensor design, data collection from SIPEX II, PIPERS, and JARE61, the data analysis approach, and the publications that came out of it.

The peer-reviewed papers — including the 2014 Nature paper on storm-induced sea-ice breakup — are mirrored locally at Data → Publications.

The WII5 buoys carry an implementation of those algorithms tuned to the constraints of on-buoy computation (memory, CPU, wake-cycle budget). The underlying mathematics is hers.

Status: placeholder. WII5 maths source release is pending assessment.