This grant supports a workshop to determine community-defined strategic direction for Real Time GPS (RTGPS) position data products and formats. High-rate real time positions based on RTGPS data improve temporal resolution of observations of natural processes and are likely to improve the understanding of earthquakes, seismic wave propagation, volcanic eruptions, magmatic intrusions, movement of ice, landslides, and structure and dynamics of the atmosphere. RTGPS-based positions may also have substantial impacts on the ability to assess natural hazards in near real time, including source characterization of large earthquake, tsunamis and volcanic eruptions, directly influencing how science and society prepare and react to these hazards. Well-defined data products and formats will allow the integration of these data with data streams from other areas of geodesy, seismology, and cryospheric and atmospheric science, helping to realize the true potential of this valuable resource. A three-day workshop is planned for late March 2012 in Boulder, Colorado and will bring together approximately 50 geoscientists and students with experience and interests in defining data products and formats based on RTGPS data. The organizing committee will produce a final workshop report that will make community-based recommendations RTGPS data products and formats that serve the broad scientific community.
Activities: Recent advances in GPS technology and data processing are providing position solutions with centimeter-level precision at high-rate (1 Hz) and low latency (i.e. the time required for data to arrive for analysis, in this case less than 1 second). These data will have the potential to improve our understanding in diverse areas of geophysics including properties of seismic, volcanic, magmatic and tsunami sources, and profoundly transform rapid event characterization and warning. Scientific and operational applications also include glacier and ice sheet motions; tropospheric modeling; and space weather. Processed real-time GPS (RT-GPS) data will require formats and standards that allow this broad community to utilize these data and associated meta-data in existing research infrastructure. A workshop hosted by UNAVCO and funded by the NSF brought together 70 participants representing a spectrum of research fields, including geodesy, seismology, weather, space weather and natural hazards with participants spanning the Western Hemisphere. Participants represented educational institutions and national facilities as well as federal and state agencies including UNAVCO, IRIS, NSF, NASA, IGS, NOAA, NR-CAN and the USGS. The objective was to define a strategic plan for the current and future needs of these user communities for RT-GPS position data products, processing, formats, standards, analysis and distribution. The workshop participants recognized broad community support for RT-GPS and in particular the scientific, societal (hazards) and operational value of data products derived from these streams. Workshop participants recommended that UNAVCO serve as coordinator for at least two working groups: one focused on formats and metadata and another that addresses data quality and robustness. The recommended working group on RT-GPS formats and metadata would help to define and identify formats that suit each user community. For example, the seismic community has a deeply developed set of tools using the SEED format that requires only position time-series. The nature of geodetic solutions and recent advances such as the availability of integrated geodetic and seismic time series, however, may require expanded formats that contain information about parameter uncertainty, covariance and data quality. The second recommended working group would critically evaluate the robustness of RT-GPS time position series. Participants presented multiple processing strategies and examples using various software packages. It was recognized that the best approach depends on the application, with different strategies optimizing different parameters (e.g. precision, accuracy, completeness or geographic coverage). This group will coordinate an open community exercise in which different data processors provide solutions based on common data sets. The results will be used to evaluate the effects of noise, displacement events, missing data (including communications failures) on the resulting solutions. This working group will engage NSF and NASA program managers to encourage support for this activity. The workshop participants also recommended that a strategy be developed for producing these data products for existing large geodetic networks like the Plate Boundary Observatory. A white paper entitled "Data Products, Formats and Applications of Real-Time GPS Position Data Products for Science and Hazard Monitoring: Results from a Community Workshop on Real-Time GPS Position Data Products and Formats held in Boulder, Colorado, March 26-28, 2012" was developed and posted at www.unavco.org/pubs_reports/reports/reports.html. This white paper formed the basis of additional meetings and discussions which influenced the development of the UNAVCO GAGE proposal currently under review at NSF, recommended an adjustment of resources to support broader community RT-GPS efforts, suggested development of additional proposals to the NSF, NASA and other agencies to foster a wide and diverse RT-GPS community. Intellectual Merit: This workshop directly contributed to the development, awareness and utilization of RT-GPS positions, standards and products for optimum scientific benefit across a wide range of fields. Research projects incorporating RT-GPS positions involve many disciplines within the Earth sciences including earthquake, volcano and tsunami rapid assessment and early warning, hazards, space weather, and meteorology (e.g. Hammond et al., 2011). RT-GPS positions, formats and standards overlap with each other and often divergently evolve. This workshop aimed to bridge developers, producers and users into common data products and formats in an effort that promises high science return across a wide spectrum of investigations. Broader Impacts: This workshop brought together diverse users from a variety of fields in the Earth Sciences to identify and contribute to achieving common goals. Research applications being advanced by RT-GPS positions have significant societal and economic relevance in areas such as natural hazards, global environmental change, space weather and meteorology. Approximately 10% (8 total) of workshop participants were graduate students, including graduates of the UNAVCO RESESS internship programs and groups underrepresented in STEM fields. The practices and products recommended by this workshop will be incorporated into RT-GPS education and outreach activities such as community short courses thereby engaging a broad cross section of users at all levels including students and future researchers.
