Displays ship traffic, identifying the number of times vessels reported positions within a given area over a certain time period. Global ship traffic is aggregated over August 2011 through mid-August 2012 at 10 km resolution. Ship traffic for the State of Hawaiʻi covers 2008-2009 and is aggregated at a higher resolution (1 km). In both cases, maps can be viewed but the underlying data are restricted by the source providers.
The Automatic Identification System (AIS) is an internationally-recognized shipboard broadcast system that communicates information to shore-based stations and other AIS-equipped ships. The U.S. Coast Guard has developed rules applicable to both U.S. and foreign vessels that require owners and operators of most commercial vessels to install and use the AIS to increase the security and safety of maritime transportation.
NOTE: These data represent total AIS position reports, not total number of ships. While useful for mapping areas of relatively high versus low shipping activity, these data should not be interpreted as the total number of ships that have visited each pixel location: a ship may transmit its position repeatedly at the same location, such as when it is anchored.
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