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Employing Unmanned Aerial Vehicles (UAVs) as an Element of the Integrated Ocean Observing System A. S. Lomax Itri Corporation, Director NOAA Projects W. Corso Lockheed Martin Space Operations J. F. Etro Itri Corporation, President well known – relatively inexpensive broad-scale and repeatable observations – as are some of the limitations and challenges – low spatial resolution as well as modeling the target and transfer medium. UAVs used in the coastal zone as a new platform for remote sensing have a role to play as a coastal component of the IOOS. Abstract - The Integrated Ocean Observing System (IOOS) provides a framework to integrate environmental data with existing and new technologies resulting in information that will improve our use and management of oceanic and coastal areas. The coastal zone is a dynamic biological, chemical, physical, and geological environment that is rich with opportunities for commerce and in need of well thought out resource management and conservation. In order to maintain responsible stewardship of this delicate environment while sharing coastal resources for economic benefit, we must have a means to measure, monitor, and characterize processes, parameters, and habitats accurately, in a timely fashion, and cost-effectively. While in situ observations and measurements provide the most precise and accurate means of data collection, this method is limited by its coarse spatial and/or temporal resolution and the potentially high cost of increasing fidelity. Satellite remote sensing provides a means of collecting large geographic views of data, but the information available from satellites can be constrained by (1) the spatial and spectral resolution of the sensor, (2) atmospheric absorption and other effects, (3) data refresh time of sensor platforms, and (4) cost. Airborne remote sensing provides a mechanism for overcoming shortcomings of space-borne sensors but typically at a high cost and with restrictions on flight regulations and endurance. In some types of operations, Unmanned Aerial Vehicles (UAVs) are less expensive and more flexible to operate than manned aircraft and continuing developments in the field are increasing the operational capabilities of these platforms and the variety of available sensors for data collection. Employment of UAV platforms and associated sensors, coordinated with in situ and other remote sensors, provides a powerful tool in characterizing the coastal ocean for habitat monitoring, hazard response and mitigation, resource management, and commercial use. UAVs can be a critically important element of the national coastal component of IOOS. II. WHY UAVS FOR COASTAL OCEAN SCIENCE? UAVs come in all shapes and sizes – from long-range, high endurance models like the U.S. Air Force Global Hawk with ranges on the order of thousands of miles to small, man-portable UAVs with ranges of a few miles. Each UAV, much like the spectrum of remote sensing sensors, has advantages and limitations. In designing for a particular mission, there are trade-offs between cost to build, cost to operate, size, range, payload, and required support infrastructure. A large UAV like the Global Hawk (44 ft body, 116 ft wingspan, 2000 lb payload) offers outstanding performance (42 hour endurance, 13,000 mile range) and capability (electro-optical, infrared, and synthetic aperture radar sensors) but at a high cost ($20-30 million per unit) while requiring significant support infrastructure [1]. While these capabilities would be invaluable for coastal ocean observations, the cost to acquire and operate this type of platform is prohibitively high. A more reasonable option for the coastal ocean community is a family of small, lightweight UAVs currently in development and production. These UAVs provide the right balance between capability and performance (Table I) and cost. These UAVs are propelled by gasoline-powered engines, are capable of programmed or manually-controlled flight, and require minimal ground space for launch and recovery. These aircraft could be operated from a ship with existing catapult-launch technology and emerging technology for soft water landings. The UAV system includes a ground station which is used to program missions, make in-flight adjustments, and receive, process, display and potentially disseminate real-time imagery and imagery products. These UAVs can be packaged with their ground station to fit into a mid-sized sport utility vehicle and they typically involve relatively simple assembly and user-friendly operation. Currently, operational sensor I. INTRODUCTION Remote sensing, in its broadest definition, is the observation or measurement of something from afar. It is commonly thought of in terms of satellite-borne sensors but it also includes airborne sensors and underwater acoustic sensors. The advantages of remote sensing are 1 TABLE I in the practical sense, marine resource managers and public health officials may not require an absolute quantitative value of algae concentration in order to decide whether or not to suspend fishing in coastal areas or close beach access to the public. Instead, these decision-makers may only need high-resolution, near-realtime imagery that shows a clearly-defined, in space and time, plume of color in the ocean. This plume could be imaged using a panchromatic camera and enhanced through the use of filters or image processing techniques. It is this type of operational product that can be made readily available through the use of a UAV. Another application of UAVs is based in the flexibility of changing sensor characteristics. It is possible to quickly change out filters on an optical sensor so that very specific bands may be quickly understood and observed. For example it has been noted that the limited spectral resolution of widely available sensors represented a challenge to mapping sea grasses in coastal areas of the State of Washington because the spectral band sets do not provide the resolution to discriminate between co-occurring plant species [2]. It may be possible with UAVs to tune the band observed very specifically to the phenomena or species of interest by a quick and inexpensive trial and error process. The National Ocean Research Leadership Council (NORLC) has identified that an IOOS must be designed to provide data and information that serves seven societal goals: (1) Improve predictions of climate change and weather and their effect on coastal communities and the nation (Weather & Climate); (2) Improve the safety and efficiency of maritime operations (Maritime Operations); (3) More effectively mitigate the effects of natural hazards (Natural Hazards); (4) Improve national and homeland security (Homeland Security); (5) Reduce public health risks (Public Health); (6) More effectively protect and restore healthy coastal ecosystems (Ecosystem Health); and (7) Enable the sustained use of ocean and coastal resources (Living Resources). [3] In order to achieve these goals, the NORLC identified 20 core variables that must be measured and monitored. Many of these core variables, listed in Table II, can be measured using existing technologies that can be mounted on or deployed by UAVs. Each of these capabilities or potential capabilities is discussed briefly below. • Salinity Current remote sensing techniques for measuring salinity employ microwave wavelengths. Small enough microwave sensors do not currently exist to permit such measurements from small UAVs but as technology progresses, this could be possible in the future. While a new technique for estimating salinity has been proposed using outgoing longwave radiation (OLR - a parameter that could be measured using infrared sensors) [4], this technique requires the use of large-scale NOMINAL SPECIFICATIONS OF UAVS FOR COASTAL OCEAN SCIENCE AND OPERATIONS MISSIONS Parameter Wing span Fuselage length Payload Endurance Cruising speed Nominal mission altitude Value 2-4m 1-3 m Up to 10 kg Up to 8-10 hrs 75-100 kph 150-350 m AGL packages small enough to meet payload restrictions for small UAVs are panchromatic (visible) and infrared imagers. Small UAVs like these have some significant advantages over other air- and space-borne remote sensing platforms. They can fly lower than aircraft and will generate imagery of high spatial resolution (on the order of < 0.2 m and less). UAVs can fly below low clouds removing that potential obstruction from the field of view. The cost of some operations is significantly lower for UAVs. In some instances, a UAV could be operated for collecting imagery at about 1/3 of the cost to the customer below the cost for comparable spatial coverage from a manned aircraft. Overhead costs and full system labor expenses, including crew staffing, are less expensive than those associated with manned flight operations. The minimal launch and recovery requirements also may ensure that UAVs can get to places that aircraft can’t reach very easily and also provide a platform that can be deployed more rapidly than manned aircraft. Also, in general, UAVs make less noise than aircraft and are smaller and less intrusive, so it is less likely to disturb the natural environment it is observing. Small UAVs do have some limitations to their operational capabilities. First, their payload capacity limits the sensors that are currently available for operations to collecting visible and infrared imagery. In some cases, a UAV must stay in constant contact with its ground station which limits it to operations within line-of-sight. Furthermore, slow speeds of advance and short duration flights may limit the extent of the mission. Despite these limitations, UAVs can be a valuable data collection platform when employed in the context of their capabilities. III. UAVS AS A COMPONENT OF IOOS A. IOOS Core Variables and Societal Goals UAVs have current capabilities and future potential to measure several IOOS core variables in order to support several of the seven societal goals of the IOOS. An example of this may be illustrated by a case of a Harmful Algal Bloom (HAB). Extensive research efforts have been dedicated to modeling the spectral characteristics of various species of harmful algae in hopes of ultimately developing algorithms for measuring concentrations of these algae in optically-complex coastal waters. However, 2 TABLE II IOOS CORE VARIABLES THAT UAVS COULD MEASURE Core Variable Salinity Temperature Bathymetry Sea Level Surface Waves Surface Currents Ice Distribution Contaminants Dissolved Nutrients Fish Species Fish Abundance Zooplankton Species Optical Properties Heat Flux Ocean Color Bottom Character Pathogens Dissolved O2 Phytoplankton Species Zooplankton Abundance • • • Current Capability Future Capability X • X X X X X X x X x X • X ? ? gridded climatic data that would not match well with fine-scale UAV-measured OLR. Temperature Miniature thermal infrared cameras currently exist that can be mounted on a UAV for measuring sea surface temperature. The technical specifications for one such camera include a 7.5-13.5 µm spectral range, a nominal thermal range of 0-40 C, and a normalized thermal resolution of < 0.04 C [5]. Bathymetry Studies have shown the ability to measure nearshore bathymetry using hyperspectral imagers and LIDAR systems (e.g. [6], [7]). While these systems do not yet exist in an off-the-shelf operational package that can fit on a small UAV, technological advances will, in the near future, miniaturize these types of sensors to allow them to be flown on such a platform. Visible imagery collected from an UAV can also be processed in a way such that video frame-to-frame pixel matching will allow terrain and shallow water bathymetry mapping by using photogrammetric techniques. Surface waves Miniature, air-launched wave buoys have been developed for use in military operations [8]. These buoys are designed to measure non-directional wave spectra so as to yield significant wave height and significant wave period data. These buoys are also equipped with thermistors to measure sea surface temperature. While the buoys were designed for deployment from larger aircraft, through some re-engineering of the buoy and the UAV, these small buoys (~ 2 kg) could be deployed from UAVs to a location where wave data may be required for a specified • • 3 amount of time. An example where this may be useful is in monitoring and predicting the dispersion of oil following a spill. Surface currents UAVs will likely not be able to directly measure surface currents directly because this typically involves the use of HF radar which require large antennae. However, techniques could be developed that would infer surface currents by other means. First, miniature drifting buoys deployed from a UAV as discussed above, if equipped with a GPS transponder, could be tracked in a Geographic Information System (GIS) to yield surface current speed and direction. A less-precise technique would be to use change detection algorithms in a GIS to monitor the movement of ocean features revealed through infrared or ocean color imagery collected from a UAV. Ice distribution Sea ice distribution and extent can be measured using infrared and panchromatic cameras on UAVs. Change detection techniques applied to time-series imagery can be used to measure ice motion. Trained ice analysts can infer rough magnitudes of ice thickness and type using panchromatic (visible) imagery. While UAVs would not be useful in providing a piece of the long-term climatic sea ice record, they could provide an extremely valuable data source for tactically ensuring safety of navigation through the Great Lakes. Contaminants Because IOOS focuses more on collecting data on surface runoff of contaminants over a long-term continuous record rather than from specific, unrelated events, the IOOS Development Plan does not include oil spill monitoring as an aspect of the contaminant core variable [9]. UAVs can provide a flexible, inexpensive, and timely solution for collecting visible and infrared imagery of oil spills to be used in response and restoration activities that encompass several of the seven goals. Furthermore, data and imagery collected from oil spill events should become part of the IOOS data archive as it could prove valuable in case studies of lessons learned and for impact assessments of ecosystem health. Optical properties and ocean color UAVs possess both a near-term capability and future capability with respect to ocean optics and color. In the near-term, panchromatic cameras on UAVs can provide high-resolution, true-color images of near-shore features. Through the use of filters or image processing techniques, it is possible to retrieve specific spectral information on a particular feature. With investment in research and development, multi- and hyperspectral sensors will be miniaturized so as to fit within the payload constraints of these UAVs. Prime applications for UAVs in this arena are to use them to provide high-resolution monitoring and tracking of HABs in addition to benthic mapping (shallow, clear waters), coral reef monitoring, and assessment of coastal habitats for threatened or endangered species. • Heat flux Heat flux measurements from satellites typically uses infrared imagery in the same bands available in UAV-capable sensors. However, most applications for heat flux data involve broad-scale and long-term studies and UAVs would not be a practical solution for contributing to this aspect of IOOS in the microscale. • Phytoplankton species and zooplankton abundance As multi- and hyperspectral sensors become available, measurements of phytoplankton and zooplankton may be possible as algorithms are developed in the scientific community. The NORLC matched the seven societal goals to any necessary core parameters that would be needed to support the goal. The results of this analysis are in Table III. By taking the union of Table II, the core parameters that could be measured from UAVs, and Table III, the core parameters mapped to societal goals, it is clear that UAVs can serve as a data collection platform in support of each of the societal goals. and sensor resolution), and relatively inexpensive platform for responding to short-duration, localized data requirements. But as in military operations, tactical-scale operations are always driven by some prior knowledge of the environment and the need, from a strategic level, to conduct the mission. It is in this scheme that UAVs would provide value to the IOOS: collecting high-fidelity data that can not be collected efficiently by other means in response to a requirement driven by end-user requirements and the end-to-end systems view of the ‘big picture’. Three potential example operational employments of UAVs in the context of IOOS are given below. Example 1 Derived products from MODIS imagery reveal the potential presence of a HAB along the Mississippi and Alabama Gulf Coast that could potentially threaten the oyster fisheries and tourist activities along the coast and associated barrier islands. A UAV is used to collect imagery of the Sound in order to determine the exact extent and motion of the bloom. The UAV team sets up operations near Biloxi and on the first day conducts 8 hours of continuous flight operations collecting visible imagery over the Sound with a spatial resolution of 1 m. During initial flight operations, the team, receiving a real-time video link, discovers the presence and precise location of a red plume in the water. The team immediately re-programs the flight plan in order to capture higher resolution imagery of the plume. Local marine resource managers are present with the UAV team and are able to make immediate, informed decisions regarding the closure of oyster beds and canceling of tourist boats traveling to the Gulf Islands National Seashore. At the end of the day’s flight operations, the imagery and its associated metadata are uploaded to an appropriate IOOS Primary Data Assembly and Quality Control (PDAQC) point to become part of the IOOS data holdings. The next day, the team continues flight operations monitoring the changing shape, size, and motion of the HAB permitting further decisions that impact public health and marine resource management. B. UAV Concept of Operations (CONOPS) in IOOS UAVs are employed by the military in both strategic and tactical applications, both of which have parallels in utilization for coastal ocean science. In tactical military applications, UAVs are vectored to specific, localized missions whether it be to conduct surveillance or to carry out offensive operations. Scientifically speaking, tactical employment of UAVs would involve missions near shore dedicated to a very specific event (e.g. incident response vice general surveillance). The range and time-on-station requirements for tactical scientific employment are not nearly as robust and fall in line with the capabilities of UAVs discussed above. These UAVs provide a mobile, flexible (in terms of sensor packages, data collection plans, 4 TABLE III. available to researchers who have an interest in studying the refuge’s ecosystem. Because of the wireless infrastructure available in the area, the team is able to immediately upload imagery and metadata to an IOOS PDAQC as soon as it has been processed and geo-referenced thus allowing the pictures to be captured in the daily news cycle for inclusion in the local and national evening news reports. Example 3 The process is finally complete designating the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve (NWHI) the 14th National Marine Sanctuary. In order to survey and characterize this sparsely-studied ecosystem and because of the lack of adequate facilities to deploy manned aircraft, a UAV team is sent aboard a research vessel collecting various in-situ data and samples. The UAV team conducts surveillance flights over each reef/atoll/island by launching the UAV from the ship and recovering it after it lands softly in the water nearby. Equipped with a miniaturized hyperspectral sensor, the imagery that is collected will serve two purposes. First, once the vessel returns to Honolulu and the imagery is uploaded to an IOOS PDAQC, the scientific community will be able to analyze the ~0.2 m resolution data to catalogue and assess the ecosystem. The second purpose of this data set is that it will serve as a high resolution baseline reference for change detection studies as observations, both remotely-sensed and in-situ, are made in the future. Each of the above scenarios describes potentially real events and real applications of a UAV as it may contribute to the IOOS. IOOS CORE PARAMETERS THAT SHOULD BE MEASURED IN ORDER TO IMPACT SOCIETAL GOALS (ADAPTED FROM [9]). CURRENT PARAMETERS MEASURABLE FROM UAVS ARE IN BLUE WHILE FUTURE CAPABILITIES ARE INDICATED IN Core Parameter Salinity Temperature Bathymetry Sea Level Surface Waves Surface Currents Ice Distribution Contaminants Dissolved Nutrients Fish Species Fish Abundance Zooplankton Species Optical Properties Heat Flux Ocean Color Bottom Character Pathogens Dissolved O2 Phytoplankton Species Zooplankton Abundance Weather & Climate Marine Operations Natural Hazards Homeland Security Public Health Ecosystem Health Living Resources GREEN. X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X IV. OPEN TECHNICAL AND OPERATIONAL ISSUES While UAVs do have the potential to play an important role as a component of the Observation Subsystem of IOOS, there are operational and technical issues that would need to be resolved before UAVs could be “plugged in” to the system. Some of these issues include: • Use of very high fidelity spatial data In nearly all instances the pixel sizes of the data generated by a small UAV will be less than 0.3 meters. In some cases it can be as small as 3 centimeters. Is the IOOS community ready to use very high fidelity data in science and operations? • Development of advanced sensors for small UAVs Current technology limits the suite of sensors available for small UAVs to panchromatic and infrared. Further technological development is required to miniaturize multi- and hyperspectral sensors and LIDAR systems that would fit within the weight and size limitations of small UAVs. Development of these advanced sensors will greatly expand the potential applications for UAVs in the IOOS. • Sufficiency of reconnaissance tools Until the CONOPs for employing UAVs is fully developed and tested, it is uncertain if the broad-scale satellite sensors will prove to be an adequate Example 2 In the midst of a storm, an oil tanker runs aground in the vicinity of Philadelphia Naval Shipyard releasing tens of thousands of gallons of crude oil into the Delaware River threatening marine life in the river and the protected ecosystem of the nearby John Heinz National Wildlife Refuge. A UAV team arrives on scene to map and track the oil spill. After setting up operations in a small parking lot adjacent to the river, the UAV team initially conducts an orientation flight to determine the extent of the spill. This visible imagery is used to direct teams in real-time who are deploying booms to contain the spill. After these teams’ actions are set in motion and the buoy is deployed, the UAV team re-programs the flight plan to collect imagery over the Wildlife Refuge. This imagery will serve as baseline data for subsequent change-detection analyses that will aid in monitoring any necessary clean-up activities in the refuge. This data, once archived in the IOOS infrastructure, will be freely 5 • • • reconnaissance tool for directing the localized employment of UAVs. The question to be answered is whether or not the spatial and temporal resolution of satellite sensors are sufficient to direct the flight of a UAV to an area of interest within the nominal range of the UAV and do so in a timely manner. Employment of a variable-resolution sensor Satellite-borne sensors orbit the earth at fixed altitudes which leads to fixed spatial resolutions in data products. However, UAVs may fly at variable altitudes which will lead to a variable resolution capability for the sensors it carries. This will require, for each application of UAV data collection (e.g. oil spill, HABs, etc.), that the user determine the required spatial resolution for the imagery and, therefore, the UAV flight altitude. Staging of UAVs and response time The practical employment of UAVs will be limited by their range, time on station, and the number of UAVs in the operational fleet. There are two options for the strategic employment of UAVs: distributed and centralized. In a distributed deployment, UAVs would be staged around the country’s coastline to respond quickly to local data collection requirements. The advantage of a distributed plan is that it shortens the response time to an incident or event. In a centralized employment, a few UAVs would be staged at a single location with an associated infrastructure to transport the UAV and associated equipment and personnel to the required location in the required timeframe. By centrally locating a group of transportable UAVs, efficiencies are gained in minimizing the support infrastructure. Such a CONOPS would emulate the U.S. Coast Guard’s National Strike Force who is charged with providing experts to oil and hazardous material spill events. Accepting UAV data of opportunity in IOOS When weighing the role that UAVs can play in the IOOS and the type of data that they can provide, the IOOS community should consider the potential differences in requirements between research quality and operational quality data and products. When considering those variables that can be measured from UAVs, consideration must be given to redefining the standards for what is considered useful IOOS data. Typical data and derived products in the context of IOOS as we see it today are considered research quality adhering to very high standards of precision, accuracy, and confidence. Derived products often require the use of complex algorithms that must be peer-reviewed and extensively tested and validated. However, in many practical operational situations where IOOS will have its greatest impact, such high standards may be unnecessary or cost-prohibitive. Data quality standards for operational decision-making may be lower than • those standards required for scientific research. Those persons who used early TIROS information will certainly attest to the value of using the data and information available. The value that may be derived from all types of data will be recovered in the metadata associated with the data. Assigning quality tags to UAV-collected data The IOOS development plan calls for developing standards of quality control (QC) so that QC flags can be assigned to IOOS data sets prior to entering the DMAC subsystem [9]. As the marine science, user, and data management communities collaborate on defining these standards, attention must be given to defining the metadata standards specifically for imagery from UAV platforms. Because of the differences in data quality requirements between the operational and research communities, it will be imperative to engage both communities so that standards are defined for and in terminology understood by both groups. V. CONCLUSION “To make the most effective decisions for protecting and preserving ocean resources, accurate information from an ocean observing system is required to allow for detection and prediction of the causes and consequences of changes in marine and coastal ecosystems, watersheds and nonliving resources” [10]. UAVs and associated sensors enhance the remote sensing backbone of the IOOS architecture and provide timely, accurate, and cost-effective information on coastal oceans. 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