Automatic Identification System
A large part of constructing a wind energy farm is deciding where to build. Concerns over wind energy potential, marine mammals, marine jurisdictions, and sediment type might dictate this decision; however, it is also important to consider shipping traffic. The Automatic Identification System (AIS) is a program designed to collect location information from vessels across the coastal continental U.S., inland rivers, Hawaii, and Guam. Why should ocean energy planners consider AIS data when planning a wind energy site?
- To be better prepared for working with the multiple stakeholders for ocean spaces. Understanding as many of the possible use conflicts and alternatives in the beginning of a planning process is essential to project planning, and this need is not any different for an offshore wind energy project. AIS data, along with other data sets, are helpful for determining the best areas with the least amount of conflict. The U.S. Coast Guard collects AIS data in real time to monitor and route large-vessel traffic. The Coast Guard has also found a secondary use for the data as a source for historical information. When collected over many months or years, AIS data illustrate patterns of ocean use by large vessels and help ocean energy planners avoid areas that are likely to cause problems with shipping commerce. The data are also helpful for showing where other potential routing measures might be advantageous for the Coast Guard to consider if large numbers of vessels are using a route not currently mapped on nautical charts. Without AIS data, planners have less accurate indicators of the full extent of shipping traffic.
- What used to take months, now takes minutes. To obtain AIS data in the past, it was necessary to submit a formal request to the Coast Guard for only a couple months’ or years’ worth of data. Now, MarineCadastre.gov has data from 2009 to 2014 available for download by UTM zone and month. Aliquot blocks are also available from North Carolina to Maine.
- Analyze trends across years. The AIS Data Handler includes tools for analyzing trends within the AIS data, which makes MarineCadastre.gov a one-stop shop for AIS data and analytical tools. With six years of data now provided on MarineCadastre.gov, users can analyze multiple years of shipping data. The tools make it easy to compare traffic volume, consistency of traffic patterns, and other vessel traffic behavior.
- Economic activity. AIS data have the potential to describe how much of the economy is dependent on ports and large shipping areas. This can show users which ports are the most valuable and what goods may be going in and out of those ports.
- Model vessel noise. Ocean noise maps can be modeled by compiling ship traffic data with previous studies on noise levels. By overlaying noise maps with marine mammal density predictions, scientists can study how marine traffic may affect marine mammals.
- Ship captains must remember to fill in the records, and sometimes one AIS transponder is moved between vessels without the ship name and other information changing. Therefore, there is high potential for human error and omission of data within the data set.
- AIS data are time-consuming and complex to process into a usable format. The AIS Data Handler works to speed up processing time. AIS data only account for 50-60% of vessel traffic.
- The data are only required for larger passenger, tug, container, and tanker vessels while recreational, fishing, and military boats are not usually tracked (see AIS requirements).
- Rules and regulations about carriage requirements have evolved over time. Therefore, users must be careful in studying trends, since the data depend on AIS requirements and when vessels were first required to use AIS.
- MarineCadastre.gov provides AIS data as points, tracklines, and density grids in hopes of catering to a wider range of user needs. MarineCadastre.gov does not distribute the raw AIS data it receives from the U.S. Coast Guard. State and federal agencies, and contractors directly working for those agencies, may request AIS data in various formats from the U.S. Coast Guard. Furthermore, MarineCadastre.gov does not collect or provide access to real-time AIS data.
Examples of AIS data used for ocean planning. The North Carolina Wind Energy Task Force is using AIS data, along with several other data sets from MarineCadastre.gov and data specific to North Carolina, to identify outer continental shelf lease blocks suitable for offshore wind energy siting (view the map).