ABSTRACT Scientists from University of South Florida rapidly responded to the Deepwater Horizon o... more ABSTRACT Scientists from University of South Florida rapidly responded to the Deepwater Horizon oil spill incident in the Gulf of Mexico (GOM). A trajectory forecast system using ocean circulation models and satellite imagery was implemented immediately upon spill onset. An ensemble of models was reinitialized daily with satellite imagery inferred oil locations, and virtual particles were then tracked using forecast currents. Subsurface trajectories were also forecast on the basis of continual release from the well site. Timely trajectory forecasts were used to plan scientific surveys and other spill response activities. In addition to the existing moored ADCP and shoreline-based HF radar arrays for ocean circulation monitoring on the West Florida Shelf (WFS), satellite-tracked drifters were deployed in both the GOM Loop Current and the shelf regions, and subsurface gliders and bottom-stationed ocean profilers were manipulated to observe the ocean circulation and to sample the ocean water properties on the WFS. The integrated ocean observing and modeling systems were demonstrated to be very useful in the rapid response.
Harmful algal blooms of the dinoflagellate Karenia brevis require an upwelling circulation to man... more Harmful algal blooms of the dinoflagellate Karenia brevis require an upwelling circulation to manifest along the coastline of the West Florida Continental Shelf. Too much upwelling, however, can impede bloom formation by increasing inorganic nutrient levels to the point where faster growing phytoplankton such as diatoms may out-compete the slower growing K. brevis, as occurred in 1998 and 2010. Both 2012 and 2013 experienced persistent upwelling, but only 2012 exhibited a robust harmful algal bloom. Here we examine the subtle differences in the coastal ocean circulation between those two years that led to the disparate bloom evolutions.
Autonomous underwater gliders are becoming important assets of coastal ocean observing systems, b... more Autonomous underwater gliders are becoming important assets of coastal ocean observing systems, but the salinity data may have errors at the depths of thermocline if unpumped CTD sensors are used. Based on the CTD data collected by an autonomous underwater glider on the West Florida Shelf, we examine different salinity corrections, and find that the existing methods successfully adjust the thermal lag effects of a weak thermocline where temperature change is less than 0.7 °C in 3 m of the water column, but fail to calibrate the salinity spikes near a sharp thermocline where temperature change is ∼2 °C within 3 m of the water column. These salinity spikes can be effectively removed by applying a median filter in conjunction with the thermal lag correction methods. Thus, we propose an improved and practical approach of glider salinity error correction, which is especially useful for waters of strong stratification and sharp thermocline.
Multi-sensor platforms like buoys and gliders produce one or more readings per sensor on varying,... more Multi-sensor platforms like buoys and gliders produce one or more readings per sensor on varying, discrete time frequencies. The resulting datasets are a matricies with rows containing readings from sensors that reported at a moment in time and NULL for missing readings from sensors that did not. Traditional Relational Database Management Systems (RDBMS) are already well suited for the dense matricies in which NULL values are infrequent. The efficiency of these systems deteriorates though as data becomes more sparse. The University of South Florida College of Marine Science Ocean Technology Group (COT) operates four gliders. Each glider produces dynamic, different sparse datasets. Other data management solutions exist, but they are based on a RDBMS. COT has been investigating an alternative without using and RDBMS. Glider Database Alternative with Mongo (GDAM) is a data management system for gliders built on the MongoDB NoSQL database engine. It is live in production at COT. GDAM is a collection of scripts which parse, process and store real-time glider datasets. Data is parsed as soon as it is transmitted via satellite to our shore-based servers. The system has been tested during two Slocum G1 glider deployments in September and October of 2012. Archival datasets dating back to March of 2009 have also been uploaded into this system. Records are indexed by time, GPS, and depth with the ability to add more indexes as necessary. The paper outlines dataset problems identified using data from COT glider operations in 2012. These problems inform a discussion of design decisions and possible options considering both RDBMS and NoSQL systems. The paper concludes by discussing the current implementation of GDAM.
Underwater gliders have become a critical component of coastal observing systems for measuring wa... more Underwater gliders have become a critical component of coastal observing systems for measuring water column properties. They efficiently sample from the surface to the seafloor or their depth limit collecting essential density variables for weeks to months at a time, providing invaluable information to validate ocean circulation models. However, they can collect much more data, and how those data sets evolve into potential uses is not always fully appreciated. Obviously, if a truck can hold more gear without significantly hurting gas mileage, why not throw more in the back end? As such, over the past decade other sensing equipment has been incorporated into glider payloads such as fluorometers, dissolved oxygen sensors, ADCPs, nutrient sensors, and more. This has allowed expanded use of the same platform without sacrificing their primary design mission of CTD profiles. These additional sensors have enabled new research in fields such as hypoxia dead zones, red tide evolution, and water column heat content. The combination of the various sensors on the same platform will continue to enhance our understanding of the connections between processes that drive our coastal oceans. An additional research area with potential use for gliders is fisheries management. Fish stock assessment depend upon data sets from fishery dependent or independent surveys that are used to set harvest limits. In the eastern Gulf of Mexico, many economically important species are benthic and generally tied to preferred habitat types. State, federal, and academic groups are coordinating efforts to generate habitat-specific population estimates, the first step of which is creating habitat maps to guide visual or trap surveys for the fish. This is typically done by initially creating detailed bathymetric maps of regions and assessing the bottom types through video and other methods to characterize the seafloor structure, habitat and the distribution of biota. However, visually mapping the entire West Florida Shelf is not feasible. Autonomous systems like gliders should be employed as a first-level reconnaissance tool to opportunistically discover reef features or fish hotspots. For the past several years, we’ve attempted to assess fish populations, site fidelity, migration, and other relevant characteristics by integrating passive acoustic recorders, tag telemetry receivers, and fisheries echosounders to a glider tasked with repeated transects within a test region. Our test region has been a large, well-known artificial reef, the Gulfstream Natural Gas Pipeline, a largely linear feature between Tampa Bay and Mobile Bay. Our sampling has been seasonal and focused on the eastern portion of this feature between the 30 and 50m isobaths on the West Florida Shelf (WFS) with a total of five deployments of a single glider completed. Yet, while the linear reef is a wonderful target for the glider, gliders cannot easily traverse a straight line when coastal tidal currents are involved. So, in typical meandering fashion, the glider would spend a lot of time in the region of the pipeline, but not directly over the pipe. We accepted these data as opportunistic and another form of reconnaissance that can inform the design of follow-on surveys. During our efforts, we have used glider-collected acoustic data to identify several “hotspot” locations with high fish densities for which we do not yet have habitat maps nor measures of fish abundance. We subsequently mapped one of these regions with high resolution multibeam echosounder to create detailed bathymetric imagery of the seafloor. This has resulted in discovering previously unknown regions of habitat including seafloor ridges and demersal fish excavated zones known as “grouper holes”. This technological approach, if applied in an observing system capacity of sustained and continuous operations over a region like the West Florida Shelf, will augment existing efforts to identify and describe fish habitat and help provide data sets complimentary to fish stock assessment.
A GPS-buoy system has been built and is currently undergoing test to measure precise 3D sea floor... more A GPS-buoy system has been built and is currently undergoing test to measure precise 3D sea floor motion in the shallow (less than 200 m) continental shelf environment. Offshore deformation is undersampled in most subduction zones. In Cascadia, the shallow shelf environment constitutes roughly 20%-25% of the offshore area between the coastline and the trench. In the system being tested, the GPS receiver at the top of the buoy is connected to the sea floor through a rigid structure supported by a float. A similar design has been used by INGV (Italy) to measure vertical deformation on the sea floor near the Campi Flegrei caldera. Synthetic analysis shows that by adding a 3-axis digital compass to measure heading and tilt, along with kinematic GPS measurements, position of the anchor can be recovered to an accuracy of several centimeters or better, depending on water depth and GPS baseline length. Synthetic resolution tests show that our ability to detect shallow slow slip events on subduction plate boundaries can be greatly improved by adding offshore GPS-buoy sites
ABSTRACT Scientists from University of South Florida rapidly responded to the Deepwater Horizon o... more ABSTRACT Scientists from University of South Florida rapidly responded to the Deepwater Horizon oil spill incident in the Gulf of Mexico (GOM). A trajectory forecast system using ocean circulation models and satellite imagery was implemented immediately upon spill onset. An ensemble of models was reinitialized daily with satellite imagery inferred oil locations, and virtual particles were then tracked using forecast currents. Subsurface trajectories were also forecast on the basis of continual release from the well site. Timely trajectory forecasts were used to plan scientific surveys and other spill response activities. In addition to the existing moored ADCP and shoreline-based HF radar arrays for ocean circulation monitoring on the West Florida Shelf (WFS), satellite-tracked drifters were deployed in both the GOM Loop Current and the shelf regions, and subsurface gliders and bottom-stationed ocean profilers were manipulated to observe the ocean circulation and to sample the ocean water properties on the WFS. The integrated ocean observing and modeling systems were demonstrated to be very useful in the rapid response.
Harmful algal blooms of the dinoflagellate Karenia brevis require an upwelling circulation to man... more Harmful algal blooms of the dinoflagellate Karenia brevis require an upwelling circulation to manifest along the coastline of the West Florida Continental Shelf. Too much upwelling, however, can impede bloom formation by increasing inorganic nutrient levels to the point where faster growing phytoplankton such as diatoms may out-compete the slower growing K. brevis, as occurred in 1998 and 2010. Both 2012 and 2013 experienced persistent upwelling, but only 2012 exhibited a robust harmful algal bloom. Here we examine the subtle differences in the coastal ocean circulation between those two years that led to the disparate bloom evolutions.
Autonomous underwater gliders are becoming important assets of coastal ocean observing systems, b... more Autonomous underwater gliders are becoming important assets of coastal ocean observing systems, but the salinity data may have errors at the depths of thermocline if unpumped CTD sensors are used. Based on the CTD data collected by an autonomous underwater glider on the West Florida Shelf, we examine different salinity corrections, and find that the existing methods successfully adjust the thermal lag effects of a weak thermocline where temperature change is less than 0.7 °C in 3 m of the water column, but fail to calibrate the salinity spikes near a sharp thermocline where temperature change is ∼2 °C within 3 m of the water column. These salinity spikes can be effectively removed by applying a median filter in conjunction with the thermal lag correction methods. Thus, we propose an improved and practical approach of glider salinity error correction, which is especially useful for waters of strong stratification and sharp thermocline.
Multi-sensor platforms like buoys and gliders produce one or more readings per sensor on varying,... more Multi-sensor platforms like buoys and gliders produce one or more readings per sensor on varying, discrete time frequencies. The resulting datasets are a matricies with rows containing readings from sensors that reported at a moment in time and NULL for missing readings from sensors that did not. Traditional Relational Database Management Systems (RDBMS) are already well suited for the dense matricies in which NULL values are infrequent. The efficiency of these systems deteriorates though as data becomes more sparse. The University of South Florida College of Marine Science Ocean Technology Group (COT) operates four gliders. Each glider produces dynamic, different sparse datasets. Other data management solutions exist, but they are based on a RDBMS. COT has been investigating an alternative without using and RDBMS. Glider Database Alternative with Mongo (GDAM) is a data management system for gliders built on the MongoDB NoSQL database engine. It is live in production at COT. GDAM is a collection of scripts which parse, process and store real-time glider datasets. Data is parsed as soon as it is transmitted via satellite to our shore-based servers. The system has been tested during two Slocum G1 glider deployments in September and October of 2012. Archival datasets dating back to March of 2009 have also been uploaded into this system. Records are indexed by time, GPS, and depth with the ability to add more indexes as necessary. The paper outlines dataset problems identified using data from COT glider operations in 2012. These problems inform a discussion of design decisions and possible options considering both RDBMS and NoSQL systems. The paper concludes by discussing the current implementation of GDAM.
Underwater gliders have become a critical component of coastal observing systems for measuring wa... more Underwater gliders have become a critical component of coastal observing systems for measuring water column properties. They efficiently sample from the surface to the seafloor or their depth limit collecting essential density variables for weeks to months at a time, providing invaluable information to validate ocean circulation models. However, they can collect much more data, and how those data sets evolve into potential uses is not always fully appreciated. Obviously, if a truck can hold more gear without significantly hurting gas mileage, why not throw more in the back end? As such, over the past decade other sensing equipment has been incorporated into glider payloads such as fluorometers, dissolved oxygen sensors, ADCPs, nutrient sensors, and more. This has allowed expanded use of the same platform without sacrificing their primary design mission of CTD profiles. These additional sensors have enabled new research in fields such as hypoxia dead zones, red tide evolution, and water column heat content. The combination of the various sensors on the same platform will continue to enhance our understanding of the connections between processes that drive our coastal oceans. An additional research area with potential use for gliders is fisheries management. Fish stock assessment depend upon data sets from fishery dependent or independent surveys that are used to set harvest limits. In the eastern Gulf of Mexico, many economically important species are benthic and generally tied to preferred habitat types. State, federal, and academic groups are coordinating efforts to generate habitat-specific population estimates, the first step of which is creating habitat maps to guide visual or trap surveys for the fish. This is typically done by initially creating detailed bathymetric maps of regions and assessing the bottom types through video and other methods to characterize the seafloor structure, habitat and the distribution of biota. However, visually mapping the entire West Florida Shelf is not feasible. Autonomous systems like gliders should be employed as a first-level reconnaissance tool to opportunistically discover reef features or fish hotspots. For the past several years, we’ve attempted to assess fish populations, site fidelity, migration, and other relevant characteristics by integrating passive acoustic recorders, tag telemetry receivers, and fisheries echosounders to a glider tasked with repeated transects within a test region. Our test region has been a large, well-known artificial reef, the Gulfstream Natural Gas Pipeline, a largely linear feature between Tampa Bay and Mobile Bay. Our sampling has been seasonal and focused on the eastern portion of this feature between the 30 and 50m isobaths on the West Florida Shelf (WFS) with a total of five deployments of a single glider completed. Yet, while the linear reef is a wonderful target for the glider, gliders cannot easily traverse a straight line when coastal tidal currents are involved. So, in typical meandering fashion, the glider would spend a lot of time in the region of the pipeline, but not directly over the pipe. We accepted these data as opportunistic and another form of reconnaissance that can inform the design of follow-on surveys. During our efforts, we have used glider-collected acoustic data to identify several “hotspot” locations with high fish densities for which we do not yet have habitat maps nor measures of fish abundance. We subsequently mapped one of these regions with high resolution multibeam echosounder to create detailed bathymetric imagery of the seafloor. This has resulted in discovering previously unknown regions of habitat including seafloor ridges and demersal fish excavated zones known as “grouper holes”. This technological approach, if applied in an observing system capacity of sustained and continuous operations over a region like the West Florida Shelf, will augment existing efforts to identify and describe fish habitat and help provide data sets complimentary to fish stock assessment.
A GPS-buoy system has been built and is currently undergoing test to measure precise 3D sea floor... more A GPS-buoy system has been built and is currently undergoing test to measure precise 3D sea floor motion in the shallow (less than 200 m) continental shelf environment. Offshore deformation is undersampled in most subduction zones. In Cascadia, the shallow shelf environment constitutes roughly 20%-25% of the offshore area between the coastline and the trench. In the system being tested, the GPS receiver at the top of the buoy is connected to the sea floor through a rigid structure supported by a float. A similar design has been used by INGV (Italy) to measure vertical deformation on the sea floor near the Campi Flegrei caldera. Synthetic analysis shows that by adding a 3-axis digital compass to measure heading and tilt, along with kinematic GPS measurements, position of the anchor can be recovered to an accuracy of several centimeters or better, depending on water depth and GPS baseline length. Synthetic resolution tests show that our ability to detect shallow slow slip events on subduction plate boundaries can be greatly improved by adding offshore GPS-buoy sites
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