Naval Postgraduate School Ocean Acoustics Laboratory

Monitoring Automatic Identification System (AIS) along Central California


The NPS AIS receiver network was established in 2008 to monitor vessel traffic along the central California coast. Taking advantage of existing Coastal Ocean Currents Monitoring Program (COCMP) sites along the California coast, AIS receive radios were added to expand AIS monitoring beyond the initial NPS stations in Monterey and Point Sur.

Current receiving stations:

Live Map, Statistics

The goal of NPS AIS monitoring is to collect ship track information along the California Coastline to validate ship noise levels as they transit, and investigate trends in marine mammal vocalizations in the presence (and absence) of vessel traffic. Though the Point Sur Ocean Acoustic Observatory array has failed, NPS continues to support a single-hydrophone recording package off Point Sur that can be compared to the AIS data.

 Since AIS broadcasts using VHF frequencies, the operating range (ie, detection range) is dependent on atmospheric conditions.  Maximum reception ranges have been observed to vary between 51 km  (on poor days) to over 1,000 km during ideal conditions.  This data can provide a unique opportunity for atmospheric modeling electromagnetic signals.


Maritime Mobile Service Identities (MMSI) codes (Maritime ID, by country).

AIS receivers were purchased under a research grant from the Office of Naval Research.