Multi-span distributed acoustic sensing (DAS) on the Ocean Observatories Initiative Regional Cabled Array 2025-2026: OptoDAS data

The distributed acoustic sensing (DAS) data collected with the Alcatel Subsea Networks OptoDAS system on the south cable of the OOI RCA from November 2025 to January 2026 is available as hdf5 files. The low sampling rate data (8 Hz) has a total size of 1.2 TB and can be accessed here:

http://piweb.ooirsn.uw.edu/das25/data/OptoDAS/

Python code to read the data, convert it to strain rate, and additional data documentation can be found at the following GitHub page:

https://github.com/uwfiberlab/OOI_DAS_2025

For 3 months beginning in November 2025, a novel multi-span distributed acoustic sensing (DAS) technique from Nokia Bell Labs was tested on the two submarine cables of the OOI Regional Cabled Array extending off Pacific City, Oregon. DAS uses backscattered light to measure strain along a fiber with a spatial resolution of meters. 

To facilitate comparison between the Nokia multispan DAS system and conventional DAS interrogators, the first span of the southern cable (out to ~95 km) was also instrumented using an OptoDAS interrogator from Alcatel Subsea Networks. The system was multiplexed such that data could be collected while the observatory continued operating. OptoDAS data were collected continuously from November 12 2025 to January 28 2026, with an outage from November 27 to December 5. The spatial and temporal sampling rates were varied periodically. Please note that the OptoDAS interrogator experienced significant calibration problems during this experiment, and therefore did not always record data consistent with the 2024 OOI experiment. Data with 40 m gauge length appears to have the highest quality. More details can be found in the Github documentation.