Texas Automated Buoy System (TABS): A Public Resource

Transcription

1 From Proceedings of the Oceanology International 98 Exhibition and Conference, 1-13 March 1998, Brighton UK, Vol. 1, pp For information about the conference see Texas Automated Buoy System (TABS): A Public Resource F. J. Kelly, Norman L. Guinasso, Jr., Linwood L. Lee III Geochemical and Environmental Research Group, College of Geosciences, Texas A&M University, 727 Graham Road, College Station, Texas USA G. F. Chaplin, Bruce A. Magnell Woods Hole Group/Advanced Coastal Environmental Systems, 81 Technology Park Drive, Falmouth, MA 2541 USA ABSTRACT Robert D. Martin, Jr. Texas General Land Office, Oil-Spill Prevention and Response Division, 17 N. Congress Ave., Austin, TX 7871, USA In August, 1994, The State of Texas General Land Office (GLO) directed the Geochemical and Environmental Research Group (GERG) of Texas A&M University to implement a program that provides real-time observations of surface currents and water temperature at selected locations along the Texas coast. The Texas Automated Buoy System (TABS) became operational in April Initially, the GLO funded five buoy sites: two off Galveston, two off Port Aransas, and one near Sabine Pass. In 1997 it authorized two additional TABS buoys for the region off Brownsville. TABS is a long-term operational system that the GLO considers absolutely critical to its ability to predict where spilled oil will go in Texas waters. Indeed, TABS data have proved pivotal during several recent spill responses. Beyond mandating this primary mission, the GLO has taken three steps to form TABS into an effective public resource: it insists that all TABS data be immediately disseminated through a user-friendly Internet webpage; it supports research to improve the reliability, operational range, and versatility of the TABS buoys; and it encourages other scientific research projects to build on the TABS resources. TABS buoys take five-minute vector averages of current velocity and water temperature two meters below the surface every thirty minutes. A shore-based computer at GERG automatically acquires the data via cellular or satellite telephone four or more times per day, performs QA/QC functions, and adds the observations to the TABS database, which is publicly available through an interactive Web site The buoys observations are viewed hundreds of times each day by boaters, commercial fishing vessels, lightering operations, students, government agencies, and petroleum companies. The accessibility of TABS data and the GLO s long-term commitment to support the project have spawned new research projects and collaborations that build on the TABS core. An example of these is the Gulf of Mexico Ocean Monitoring Program, which is a National Ocean Partnership Program component, funded through the Office of Naval Research. The project s objective is to produce nowcasts and forecasts of surface and subsurface velocities for the entire Gulf of Mexico and distribute them publicly via an Internet Web page. This project and another one are funding the addition of four more buoys to the TABS system, bringing to eleven the total number in operation by spring Page 13

2 INTRODUCTION Recognizing that oil spills threaten the economic and environmental well-being of the Texas Gulf Coast, the Texas Legislature passed the Oil Spill Prevention and Response Act of 1991, and it designated the Texas General Land Office (GLO) as the lead state agency for oil spills in Texas coastal waters. To support the additional GLO mission, the Legislature also created the Coastal Protection Fund through a two-cent-per-barrel fee on all crude-oil products moving through Texas ports. With this mandate and funding, the GLO has moved aggressively to develop its prevention program and response capabilities. (See: Rapid, effective spill response can save substantial monies and greatly mitigate environmental impact. Therefore, the GLO maintains a computer workstation that continuously runs an oil-spill trajectory model. The model, Spillsym, generates maps that are linked to an ArcInfo Geographic Information System to assess resources at risk. However, the accuracy and utility of any such model are almost entirely dependent on timely input of current and wind observations. The traditional use of historical or averaged seasonal data has proved ineffective for real-time operations, especially as a spill approaches the coast. In August 1994, the GLO directed the Geochemical and Environmental Research Group (GERG) at Texas A&M University (TAMU) to implement a program that would provide its computer with real-time observations of surface currents and water temperature and a synthesis of publicly available, real-time, marine weather data. The Texas Automated Buoy System (TABS) became operational in April 1995 with the deployment of its first two buoys off Galveston, Texas. At the time of this writing, TABS has five buoys in operation, e.g., Buoy G, east of Sabine Pass, Buoys B and F off Galveston, and Buoys D and H off Corpus Christi (Figure 1). In 1997 the GLO authorized the purchase of two additional buoys for the South Padre Island region near Brownsville (Buoys J and K in Figure 1). Research projects external to TABS (see below), but cooperating and cost-sharing with it, are contributing four more buoys (Buoys I, L, M, and N in Figure 1). Thus, GERG will deploy the six new buoys during the spring of 1998, bringing to eleven the number of active TABS sites. TABS has proved its worth during real spills, and realistic drills. During the Buffalo Marine Barge 292 oil spill, for example, the National Oceanic and Atmospheric Administration HAZMAT modeling team and the GLO s trajectory modeling team used TABS data and computer simulations to forecast the movement of the oil to an unprecedented level of accuracy (Martin et al., 1997). The trajectory modelers did not have to begin their work with only educated guesses about the offshore currents. The currents were known within minutes of the spill and were continuously tracked for the next 24 days. Midway through the spill TABS data showed the direction of the coastal current switching from up-coast to down-coast. The benefit to cleanup and protection operations was that the Incident Command could make the decision to stand-down an alert to the Sabine Pass area and refocus efforts down-coast a full day earlier than would have been possible prior to TABS. The primary mission of TABS is to provide real-time data when the spill alarm goes off. However, the GLO recognized from the project s inception that three factors would form TABS into an effective public resource as well. Thus, the GLO supports research to improve the reliability, operational range, and versatility of the TABS buoys; it insists that all TABS data be immediately disseminated though a user-friendly Internet Web site; and it encourages other scientific research projects to build on the TABS resources. We focus on the success of these aspects of the project in the following sections. Page 14

3 TABS Buoys NDBC Buoys Discontinued Houston Galveston SRST A G I Proposed NOPP Scheduled 12/97 B C F L 28 N Corpus Christi PTAT2 D H 4219 M N E 422 Gulf of Mexico 26 N 98 W J K W 94 W Figure 1. Map of current and future TABS buoy locations. Bathymetric contours shown for the following depths (meters): 2, 5, 2, 5, 2, 35. TABS EQUIPMENT TABS buoys take a five-minute vector average of current velocity and water temperature about two meters below the surface every thirty minutes. A shore-based PC computer running LINUX automatically acquires the data via either cellular or satellite telephone four times daily under normal conditions. Since the reporting link is fully two-way, GERG can switch to a more frequent schedule during spills. The data are automatically transferred to a UNIX workstation that performs QA/QC functions and adds the observations to the TABS database. Two buoy models are now in operation. Both are schematically illustrated in Figure 2. The original TABS I model was designed for the nearshore coastal environment and intended to obtain just near-surface currents and water temperature. With this focus, the design could take advantage of the large offshore area that is covered by cellular telephone service (Chaplin and Kelly, 1995). By pulling already proven tools and technologies off the shelf and combining them Page 15

4 TABS II Climatronics Met Sensor Antenna Marine Lantern Wiring / Connector Housing Internal Radar Reflector TABS I A 4 m J Antenna Marine Lantern Wiring / Connector housing Internal Radar Reflector Solar Panels (9 total) Solar Panels (6) Buoy Hull Polyethylene Foam Interior Polyurethane Fabric Skin.61 m.79 m Buoy Hull Polyethylene Foam Interior Polyurethane Fabric Skin Cellular Telemetry Module Current Meter Electronics Protective Cage Electromagnetic Current Sensor Chain to Anchor 2.4 m Lifting Bails Aluminum Electronics Housing with Satellite Telemetry System,Data Logger, Current Meter Electronics and Batteries Protective Cage Electromagnetic Current Sensor NOT TO SCALE Figure 2. Schematic diagrams of the TABS I and TABS II buoy models. Chain to Anchor Page 16

5 in an innovative way, the length of the R&D phase was reduced, with the first deployment taking place just nine months from the project s inception. Both buoys are a modified spar design with a flotation package constructed of closedcell, cross-linked, polyethylene foam with a polyurethane fabric-reinforced skin. They have built-in radar reflectors, and central stainless steel or aluminum watertight housings for the current meter and communications electronics. A Marsh-McBirney electromagnetic 2-axis current sensor extends from the buoy bottom. Six or nine solar panels provide power through rechargeable batteries. After a year-and-a-half of successful, operational, field experience with the TABS I model, during which several modifications and upgrades were accomplished, the GLO directed GERG to develop the next generation TABS buoy TABS II was developed in cooperation between GERG and Woods Hole Group/Advanced Coastal Environmental Systems (ACES), Inc. Magnell et al. (1998) describe the details of the new design. The four major design enhancements are 1) a new geostationary satellite telephone system, 2) an increased size of the flotation package, 3) an Argos satellite data transmission system that is automatically activated if the primary communications system fails, and 4) an electronic command and control system based on the ACES Remote System Monitor, which includes a powerful microprocessor and multiple analog and digital I/O ports. On January 2, 1998, GERG deployed the first TABS II buoy for test and evaluation next to Buoy B off Galveston. Initial results are excellent. The new model buoys will be deployed at Sites I through N (Figure 1). Selected buoys will incorporate the Climatronics TacMet meteorological package. PUBLIC DATA DISSEMINATION The data from the TABS buoys are available to the general public on the GERG Web server. Users are able to access the data in both graphical and tabular formats (Lee et al., 1996). The TABS Web page, shown in Figure 3, provides the user with access to a variety of oceanographic and meteorological data products. Users can select a TABS buoy location from the map or from text links for those without a graphical Web browser. For each TABS station the user can choose to view either a graph of the past four days of data or the data in tabular format. The graph consists of a "stick plot" of the currents, cross shelf and along shelf components of the current and water temperature. These data are presented in both English and metric units. The graph can be downloaded as either a GIF image or a postscript file. TABS data are routinely updated every six hours but can be more frequently updated as needed in the event of an oil spill. Each buoy page also contains a link that allows the user to search the TABS database and retrieve data from a buoy for a user selectable time period. The user can access up to two months of data at a time. The results of each database search can be viewed in both graphical and tabular format. For example, Crout (1997) used the TABS database features to facilitate his study comparing currents calculated from satellite altimetry with those observed by the TABS buoys. The TABS Web site also provides access to data from the National Data Buoy Center's (NBDC) buoy and coastal (CMAN) meteorological data. These data are obtained from the Global Telecommunications Stream (GTS) via the Internet. We include three offshore buoys and two CMAN stations, e.g., 4235 located southeast of Galveston, 4219 and 422, which are east and southeast of Port Aransas, respectively, SRST2 near Sabine, and PTAT2 near Page 17

6 Figure 3. Example of TABS main Web page. Page 18

7 Port Aransas (Figure 1). These data are updated hourly and presented in both graphical and tabular formats. There are several additional features of the TABS Web site that can assist in the utilization of the TABS data. A summary plot capability provides a stickplot for each buoy using a common time axis. A status table lists buoy latitude, longitude, lease block and water depth. The status table also indicates which of the buoys have successfully transmitted their data during the past twelve hours and contains other information regarding the operational status of each buoy. Links to National Weather Service coastal and offshore weather forecasts for the Gulf of Mexico are provided on the main TABS Web page. The Web site also contains a number of links to additional real-time oceanographic and meteorological data. There are links to the Houston/Galveston PORTS Web site, the Texas Coastal Ocean Observation Network (TCOON), Galveston Bay and Corpus Christi Bay Animated Hydrodynamic and Oil Spill Model output, Satellite Sea Surface Temperature Images from NOAA and Johns Hopkins University, Tampa Bay PORTS, and other relevant sites. Analysis of the TABS Web server access logs show that utilization of the TABS Web site has been increasing since its inception. A graph of monthly access totals is shown in Figure 4. Peak usage of the TABS Web site generally occurs in mid-october and then tails off rather sharply. We see this as a reflection of the end of the recreational boating season and a decrease of usage by boaters. The three largest groups of TABS users come from the.com,.edu and.net Internet domains. The first represents commercial entities primarily from within the United States; the second represents educational institutions in the U.S. and the last are network service providers. However, since some of the major Internet service providers are in the.com domain, i.e., AOL, it would appear that the majority of the use of the TABS site is coming from the general public. There are several other noteworthy groups that access the TABS site. Some of these are users from the Texas State government and specifically the Texas General Land Office, users from the U.S. government, including users from NOAA, MMS, USGS and NASA. Usage by the offshore industry includes most of the major oil companies. In addition we have seen usage from sixty-nine foreign countries to date. 6 5 Monthly Access Totals for the TABS Web Server 4 Accesses J F M A M J J A S O N D J F M A M J J A S O N D Figure 4. Monthly access totals for TABS Web site from January 1996 January Page 19

8 2 3 4July July July July 5 TGLO TABS Buoy Current Summary knots cm s Buoy G North -4-6 : 6: 12: 18: : 6: 12: 18: : 6: 12: 18: : 6: 12: 18: 1 : knots cm s Buoy B North -4-6 : 6: 12: 18: : 6: 12: 18: : 6: 12: 18: : 6: 12: 18: 1 : knots cm s Buoy F North -4-6 : 6: 12: 18: : 6: 12: 18: : 6: 12: 18: : 6: 12: 18: 1 : knots cm s Buoy D North -4-6 : 6: 12: 18: : 6: 12: 18: : 6: 12: 18: : 6: 12: 18: 1 : knots cm s Buoy H -4-6 : 6: 12: 18: : 6: 12: 18: : 6: 12: 18: : 6: 12: 18: : July 1997 North Figure 5. Stick vector plots of the current velocity measured half-hourly at five buoy locations during the first four days of July (A stick vector points in the direction the current is flowing, with True North at the top of the page. The length of the vector, from its base on the x- axis to its tip, is proportional to the speed; the y-axis serves as the scale.) Page 11

9 RESEARCH PROJECTS THAT BUILD ON TABS Thus far, three research projects have been funded that take advantage of the resources of the TABS core program. The first of these is funded by the GLO itself and titled Texas Automated Buoy System Modeling Effort. TABS buoys have proven highly successful at measuring currents at specific locations. However, the coastal ocean is often highly variable in both time and space. For example, Figure 5 shows stick vector plots of the current velocity measured half-hourly at five buoy locations during the first four days of July Note the strong, persistent, northeastward flow at Buoy D. A little farther offshore at Buoy H (Figure 1), however, the currents are rotating clockwise with a daily period. Currents at Buoy G, east of Sabine Pass, are frequently directed opposite to those off Galveston at Buoy B during this period. This new two-year modeling project will assimilate currents and wind measurements and provide estimates of currents all along the Texas Coast, thus extending the buoys point measurements. A second project, titled An Observational and Predictive Study of Inner Shelf Currents over the Texas-Louisiana Shelf is made possible by a combination of funding sources, including the U.S. Minerals Management Service, Louisiana State University, TAMU, Marine Industry Group-Gulf, and the GLO. It will add Buoy I, extending the TABS network into the coastal waters of western Louisiana. The project s goals are to analyze all the historical data collected by the TABS array, compare the field data with winds and water levels in an effort to understand better the dynamical balances present in the coastal waters of Louisiana and Texas, and develop a dynamically consistent nowcast/forecast of the coastal currents. The third and most ambitious project, Gulf of Mexico Ocean Modeling System is one of the projects of the National Ocean Partnership Program. It is funded by the Office of Naval Research, with Dynalysis of Princeton, Inc., serving as the lead organization. The project s objective is to produce nowcasts and forecasts of surface and subsurface velocities for the entire Gulf of Mexico and distribute them publicly via an Internet Web site. The TABS contribution is to verify model generated velocities and to provide calibration data for currents derived from satellite altimetry along a line running across the Texas continental shelf, e.g., through Buoys B, F, L, M, and N, approximately, in Figure 1. CONCLUSIONS By adopting a farsighted policy toward the TABS program the GLO has transformed a tool critical to its oil spill response mission into a valuable public resource. The public and the scientific community are rapidly adopting it, finding new and innovative uses for its products, and adding to its capabilities. The new TABS II buoy is designed with expandability and flexibility in mind. It can accommodate a variety of additional sensors for meteorology, water optics, acoustics, and water chemistry. As the real-time observations are coupled with the computer models being developed by various research projects, our view and understanding of the waters offshore Texas will expand rapidly and profoundly. ACKNOWLEDGEMENTS The TABS project is funded by the Texas General Land Office, currently through Contract 98-67R. Additional TABS financial support has been provided by ARAMCO Services Page 111

10 Co., Marine Industry Group Gulf (MIRG), and Mobil Co. The Marine Spill Response Corp. has provided ship support. Research projects that build on the TABS project are funded by the Texas General Land Office under Contract R, by the U.S. Minerals Management Service through Louisiana State University subcontract R148185, and by a National Ocean Partnership Program project funded by the Naval Research Laboratory through Dynalysis of Princeton subcontract 12/15/97. This paper does not necessarily reflect the views or policies of the Texas General Land Office or of any of the other agencies and companies providing financial and service support. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. REFERENCES Chaplin, G. F. and F. J. Kelly, 1995: Surface current measurement network using cellular telephone technology. Proceedings of the IEEE Fifth Working Conference on Current Measurement, Feb. 7-9, 1995, St. Petersburg, FL Crout, Richard L., 1997: Coastal currents from satellite altimetry. Sea Technology, Vol. 38, No. 8, Lee, L. L., III, F. J. Kelly and N. L. Guinasso, Jr., 1996: Armchair currents using TABS (Texas Automated Buoy System). Eos Trans. Vol. 76, No. 3, p. OS78. Magnell, B. A., F. J. Kelly and R. A. Arthur, 1998: A new telemetering environmental buoy for offshore applications. Proceedings of the Oceanology International 98 Conference, 1-13 March 1998, Brighton, UK Martin, R. A., F. J. Kelly, Linwood L. Lee III, and Norman L. Guinasso, Jr., 1997: Texas Automated Buoy System: Real-time currents for oil spill response. Proceedings of the 1997 International Oil Spill Conference, April 7-1, 1997, Fort Lauderdale, FL. Page 112