Seismic-py: Reading Seismic Data with Python

The field of seismic exploration of the Earth has changed dramatically over the last half a century. The Society of Exploration Geophysicists (SEG) has worked to create standards to store the vast amounts of seismic data in a way that will be portable across computer architectures. However, it has been impossible to predict the needs of the immense range of seismic data acquisition systems. As a result, vendors have had to bend the rules to accommodate the needs of new instruments and experiment types. For low level access to seismic data, there is need for a standard open source library to allow access to a wide range of vendor data files that can handle all of the variations. A new seismic software package, seismic-py, provides an infrastructure for creating and managing drivers for each particular format. Drivers can be derived from one of the known formats and altered to handle any slight variations. Alternatively drivers can be developed from scratch for formats that are very different from any previously defined format. Python has been the key to making driver development easy and efficient to implement. The goal of seismic-py is to be the base system that will power a wide range of experimentation with seismic data and at the same time provide clear documentation for the historical record of seismic data formats

New Standards for Providing Meteorological and Hydrographic Information via AIS Application-specific Messages

AIS Application-specific messages transmitted in binary format will be increasingly used to digitally communicate maritime safety/security information between participating vessels and shore stations. This includes time-sensitive meteorological and hydrographic information that is critical for safe vessel transits and efficient ports/waterways management. IMO recently completed a new Safety-of-Navigation Circular (SN/Circ.) that includes a number of meteorologi-cal and hydrographic message applications and data parameters. In conjunction with the development of a new SN/Circ., IMO will establish an International Application (IA) Register for AIS Application-Specific Messages. IALA plans to establish a similar register for regional appli-cations. While there are no specific standards for the presentation/display of AIS application-specific messages on shipborne or shore-based systems, IMO issued guidance that includes specific mention of conforming to the e-Navigation concept of operation. For both IHO S-57 and S-100-related data dealing with dynamic met/hydro information, it is recommended that IHO uses the same data content fields and parameters that are defined in the new IMO SN/Circ. on AIS Application-specific Messages

Encoding AIS Binary Messages in XML Format for Providing Hydrographic-related Information

A specification is proposed to enable hydrographic and maritime safety agencies to encode AIS messages using Extensible Markup Language (XML). It specifies the order, length, and type of fields contained in ITU-R.M.1371-1. A XML schema validates the message definitions, and a XSLT style sheet produces reference documentation in \u27html\u27 format. AIS binary messages in XML are an effective means to communicate dynamic and real-time port/waterway information. For example, tidal information can be continuously broadcast to maritime users and applied to a tide-aware ENC. The XML format aligns with the type of data encapsulation planned for the IHO Geospatial Standard for Digital Hydrographic Data (S-100)

Proposed AIS Binary Message Format Using XML for Providing Hydrographic-related Information

UNH is working with the USCG and NOAA to use XML (Extensible Markup Language) to define binary messages for maritime-based AIS (Automatic Identification System). A draft specification format is under development that will enable hydrographic and maritime safety agencies to encode AIS message contents by providing a bit-level description in XML (informally known the AIS Binary Message Decoder Ring ). An AIS binary message definition in XML specifies the order, length, and type of fields following a subset of that used by the ITU-R.M.1371-1. The specification is independent of programming language (e.g., can be implemented in C, C++, C#, Java, Python, etc.) to allow vendors to integrate the system into their individual design requirements. The draft specification also contains a reference implementation of an AIS XML to Python compiler that has been released as open-source under the GNU General Public License (GPL) version 2. A XML schema and an additional program will provide validation of the XML message definitions. A XSLT style sheet produces reference documentation in ‘html’ format. Although the XML message definition file specifies the order, size, and type of the bit stream, it does not specify semantics or how binary messages should be displayed on a shipboard ECDIS, or presented on other shipboard/shore-side display devices

Marine Ship Automatic Identification System (AIS) for Enhanced Coastal Security Capabilities: An Oil Spill Tracking Application

National and international trade via shipping is already significant, and expected to continue increasing rapidly over the next decade. Both more ships and larger ships will contribute to this trade, includingships from countries with less rigorous shipping maintenance and inspection standards than the United States, and less strict pollution monitoring regulations. Changes in ship traffic management protocols have been implemented in recent years in the U.S. to minimize damage to coastlines, particularly near sensitive or protected marine environments. For example, to reduce risk to coastal resources off central California, shipping lanes for larger vessels were moved further offshore to allow for additional response time in case of accidents before such vessels might drift into coastal areas. Similarly, shipsare now routed via specific approach channels when entering Boston Harbor to reduce impacts within adjacent National Marine Sanctuary resources. Several recent high profile cases have occurred where \u27mystery\u27 oil spills were found near shipping channels, but no vessel could be readily identified as their source. These incidents lead to extensive and expensive efforts to attempt to identify the shipsresponsible. As time passes in responding to these incidents, the likelihood of confirming the identity of the ships diminishes. Unfortunately, reports of vessels engaging in illegal oily waste discharge to reduce fees for offloading the waste in port are ongoing. We here discuss use of improved capabilities of near-continuous real-time position location monitoring of shipping traffic using marine AutomaticIdentification Systems (AIS) for ships that would facilitate identification of ships responsible for illegal oily waste discharge. The next phase of the National AIS, N-AIS Increment 2, can supply additional spatial coverage not currently included in the N-AIS Increment 1, which can provide an enhanced capability for monitoring shipping and improving managem- ent of coastal ship traffic and response to pollution incidents. These methods will not only improve response time, but reduce cost of response as well

Traffic Analysis for the Calibration of Risk Assessment Methods

In order to provide some measure of the uncertainty inherent in the sorts of charting data that are provided to the end-user, we have previously proposed risk models that measure the magnitude of the uncertainty for a ship operating in a particular area. Calibration of these models is essential, but the complexity of the models means that we require detailed information on the sorts of ships, traffic patterns and density within the model area to make a reliable assessment. In theory, the ais system should provide this information for a suitably instrumented area. We consider the problem of converting, filtering and analysing the raw ais traffic to provide statistical characterizations of the traffic in a particular area, and illustrate the method with data from 2008-10-01 through 2008-11-30 around Norfolk, VA. We show that it is possible to automatically construct aggregate statistical characteristics of the port, resulting in distributions of transit location, termination and duration by vessel category, as well as type of traffic, physical dimensions, and intensity of activity. We also observe that although 60 days give us suffi- cient data for our immediate purposes, a large proportion of it—up to 52% by message volume—must be considered dubious due to difficulties in configuration, maintenance and operation of ais transceivers

Establishing a Regional AIS Application Specific Message Register

The goal of the Regional AIS Application Specific Message Register is to provide awareness of what applications exist, facilitate harmonization, and promote proper binary messaging for regional applications. To be hosted on the IALA website, establishing the Register will be a 3-step process: 1) Compile all existing AIS binaries into a Jcollection.K 2) Convert the JcollectionK into a Register. 3) Develop IALA guidance on best practices for creating and using AIS Binary Messages. Recommendations are provided in regard to: - Benefit of a web-based HTML user interface for input/output. - Use of XML to organize/format register applications in a consistent manner. - Having the collection/registration become a JloopK process. - Conforming to ISO standards to organize and manage the Register. - Benefit of a joint IMO-IALA register for both international and regional applications

Enhancing AIS to Improve Whale-Ship Collision Avoidance and Maritime Security

Whale-ship strikes are of growing worldwide concern due to the steady growth of commercial shipping. Improving the current situation involves the creation of a communication capability allowing whale position information to be estimated and exchanged among vessels and other observation assets. An early example of such a system has been implemented for the shipping lane approaches to the harbor of Boston, Massachusetts where ship traffic transits areas of the Stellwagen Bank National Marine Sanctuary frequently used by whales. It uses the Automated Identification Systems (AIS) technology, currently required for larger vessels but becoming more common in all classes of vessels. However, we believe the default mode of AIS operation will be inadequate to meet the long-term needs of whale-ship collision avoidance, and will likewise fall short of meeting other current and future marine safety and security communication needs. This paper explores the emerging safety and security needs for vessel communications, and considers the consequences of a communication framework supporting asynchronous messaging that can be used to enhance the basic AIS capability. The options we analyze can be pursued within the AIS standardization process, or independently developed with attention to compatibility with existing AIS systems. Examples are discussed for minimizing ship interactions with Humpback Whales and endangered North Atlantic Right Whales on the east coast, and North Pacific Right Whales, Bowhead Whales, Humpback Whales, Blue Whales and Beluga Whales in west coast, Alaskan and Hawaiian waters