This series will explain the importance of various data sets within MarineCadastre.gov and why they should be considered when determining ocean use sites.

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 important to also consider shipping traffic. The Automatic Identification System (AIS) is a program designed to collect locational information from vessels across the coastal continental U.S., inland rivers, Hawaii, and Guam (Navigation Center).

Why should ocean energy planners consider AIS data when planning a wind energy site?

1.  To be better prepared for working with the multiple stakeholders for ocean spaces. There are many possible deterrents to building a wind energy project in state or federal waters, and understanding as many of the possible use conflicts and alternatives in the beginning is essential to project planning. AIS data, along with many other data types, are helpful for determining the best areas with the least amount of conflict. AIS data in real time, collected by the U.S. Coast Guard, are used for monitoring and routing large-vessel traffic, but they have found a secondary use as historical information. When collected over many months or years, AIS data can give 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 in 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 are left with using less accurate predictions of shipping lanes that do not describe the full extent of shipping traffic.

2.  What used to take months, now takes minutes. To obtain AIS data in the past, a person had to submit a formal request to the Coast Guard for only a couple of month’s or a year’s worth of data. Now MarineCadastre.gov has the entire calendar year 2009 collection available for download by UTM zone and month.

3.  AIS Data Handler analyzes trends. There are many great tools available for analyzing real-time data; however, few of those tools analyze trends. The AIS Data Handler includes tools for analyzing trends within the AIS data, providing a one-stop-shop for AIS data and analytical tools.

4.  Bonus reasons. AIS data are an indicator of economic activity and can be used to model probable vessel noise levels for marine mammal research. AIS data have the potential to describe how much of the economy is dependent on ports and large shipping areas. This can then show users which ports are the most valuable and what goods are going in and out of those ports. By compiling ship traffic data with previous studies regarding noise levels for boats of similar size to those in the AIS data, noise maps can be made of the ocean based on vessel traffic. By overlaying these noise maps with marine mammal density predictions, scientists can study possible human effects on marine mammals.

Quick Caveats. AIS data are time-consuming and complex to process into a usable format. Ship masters must remember to fill in the records, and sometimes one AIS receiver is moved between multiple boats without the ship name and other information changing. Therefore there is high potential for human error and omission of data within the data set. The AIS Data Handler works to clean up these errors for usability. AIS data only account for 50-60% of vessel traffic. The data are only required for larger passenger vessels, tug boats, etc., with recreational, fishing, and military boats usually not being tracked. Lastly, rules and regulations about carriage requirements have evolved over time; therefore, be careful in studying trends, since the data depend on AIS requirements and when those boats were first required to start using AIS.

An example 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 the Marine Cadastre and data specific to North Carolina, to identify outer continental shelf lease blocks suitable for offshore wind energy siting.