OPERATIONALISATION OF A MULTI-USER CONCEPT FOR SATELLITE BASED OIL SPILL AND SHIP DETECTION SERVICES

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1 OPERATIONALISATION OF A MULTI-USER CONCEPT FOR SATELLITE BASED OIL SPILL AND SHIP DETECTION SERVICES Line Steinbakk, Jan Petter Pedersen, Tony Bauna Kongsberg Satellite Services, N-9291 Tromsø, Norway line@ksat.no, janp@ksat.no, tonyb@ksat.no ABSTRACT Satellite based Synthetic Aperture Radar (SAR) has become one of the most important sensors for operational monitoring of marine environment. Kongsberg Satellite Services (KSAT) has since 1994 been delivering SAR based oil spill and ship detection services to European end users in near real time, i.e. less than one hour after satellite overpass. The satellite based information is used in combination with other surveillance methods, and the near real-time availability is therefore crucial. Sustainable pan-european marine surveillance requires cooperation among the end-users. KSAT has during the recent years derived a multi-user model which is now being applied for the operational end-users. This model has been successfully applied, lately in the ESA/GSE Marcoast project for the North and the Baltic Sea users, and now also for EMSA. A multi-user web site has been established, allowing all approved users access to the relevant service information, from satellite planning until the service information on oil spills, pollution source, ships, wind etc. Keywords: Satellite, SAR, Oil spill, Multiuser, Marine Surveillance, Information and cost sharing. 1 INTRODUCTION Marine surveillance is important for environmental protection and sustainable management of the Exclusive Economic Zone (EEZ) of coastal nations. National legislation and international agreements exist to prevent illegal activities such as; oil pollution, fisheries incursion and smuggling. The majority of European coastal nations have already dedicated marine surveillance programs. These programs are operated by national authorities and are based on a combination of coastal radar, airborne and vessel surveillance systems. During the latter years several European coastal nations have utilized satellite monitoring as an integrated part of their surveillance system. Satellite Synthetic Aperture Radar (SAR) can provide large area coverage of the Earth s surface independent of weather and light conditions. SAR has evolved to become one of the most important sensors for operational monitoring of the marine environment. Kongsberg Satellite Services (KSAT) in Tromsø, Norway has provided a service utilizing satellite SAR images for detection of oil spill since The continuing development into an operational service has been conducted in close cooperation with key end users, starting with the Pollution Control Authority in Norway as the first user. The service chain now meets the most important user requirements. It is also well accepted among the users that the combination of aircraft and satellite is a cost-effective solution for large area surveillance. Despite this positive acceptance among the users, the service contracts have been on a yearly basis and also dependent upon the customer s annual surveillance budgets. The main challenge has therefore been to establish a sustainable, operational pan-european surveillance service. Recent activities such as the Norwegian SatOcean [1] program under the responsibility of the Norwegian Space Centre, an ESA supported Marked Development project on Marine Surveillance (ESA-MD MAS) [2] as well as the on-going ESA GSE MARCOAST project have documented that service information and cost sharing models based on harmonized user requirements seem to the preferred strategy towards sustainable services. The multi-user service concept has been applied operationally for North Sea users during the first phase of the Marcoast project. The experience obtained here founded the basis for the first pan-european satellite monitoring service recently established by EMSA under a contract with a KSAT led consortium. 2 SERVICE CHAIN The KSAT oil and ship detection service chain is based on SAR data from the European Envisat and the Canadian Radarsat-1 satellites. The service chain (figure 1), includes a dialogue with the users to harmonise the coverage requirements which are being used for satellite tasking requests and aircraft operations coordination. The other service chain elements include SAR data acquisition and processing, reception and integration of non-space Proc. Envisat Symposium 2007, Montreux, Switzerland April 2007 (ESA SP-636, July 2007)

2 data into the analysis process, image analysis and interpretation, followed by early warning alert to the customer as well as information ingestion into the service web-server. Figure. 1: KSAT oil and ship detection service chain. A dedicated service workstation developed by Kongsberg Spacetec is applied for multi-source data ingestion and integration, information extraction, presentation and distribution. The operator utilizes SAR data integrated with meteorological data and geographical information during the analysis and interpretation process. The oil spil analysis still relies upon interactive human interpretation, while the ship detection is done automatically. KSAT operating engineers have analysed several thousands of SAR images, and thereof developed their experience and knowledge on interpretation of SAR images in terms of identifying possible oil spills. Automatic oil spill detection algorithms have been tested with encouraging reliability, and KSAT has initiated a process for integrating these into the operational service chain. The basis for the near real-time service capability to provide the information to the customer within 30 minutes after acquisition, are the powerful RADARSAT and ENVISAT SAR processors capable of generating ScanSAR images in less than 10 minutes. It has been documented that radar images with a spatial resolution of 100 meters is very suitable for detecting oil spill and ships at the sea surface [3,4,5,6]. As the users have become more experienced on utilizing satellite EO services, their demand has developed from simple feature or object detection into more detailed information and identification. The service now provides extended information on oil spills, including a source notification and identification if present. Identification on fixed targets such as offshore installations is derived from a database updated regularly, while ship identification is derived from operationally accessing the AIS database via the Norwegian Coastal Directorate. The identification information is provided to the users as a graphical layer via the web-server and in the service source reports. The users are informed about possible oil spills within 60 minutes after data acquisition. EMSA receives both the image data and the service information, while other users receive only the report with the results from the analysis. The complete service information is also made available at the customer s web-page. The web page also contains updated information on planned satellite passes. Figure 3 below shows the web-server currently applied for the Marcoast users. Figure 3: KSAT service information web-server user interface. Figure 2: Example of a SAR image with an oil spill (upper right part), overlaid ship identification from AIS. Access to the acquisition plans is important for coordination with aerial surveillance The users have an aircraft stand-by or already flying in the area to check reported oil spills. The delivery time is therefore crucial for this integrated service. The requested delivery time is < 30 minutes, but < 1 hour is acceptable. A user feedback function has also been implemented on the web-page, and the users now provide KSAT with results (text and

3 images) from verifying flights. This feedback is also essential for KSAT in order to improve service performance. 3 DEVELOPMENT OF MULTI-USER MODELS KSAT experience a growing interest for near-real time oil spill and ship detection services. The traditional picture has been services deliveries on an annual basis where the temporal and geographical coverage have been determined by individual national surveillance budgets. It has been difficult to obtain long term commitments from the customers based on commercial pricing policies. Service costing has been based on a per-image pricing, and the traditional service model has been one service setup for each customer. This results in the customer has been paying the full cost of the service, in which they don t utilize the full potential of the satellite. In addition, no coordination between customers have existed, and frequent acquisition request conflicts have occurred. Figure 4: North Sea users service area. A wide swath SAR image normally covers more than one EEZ. In the Baltic a single ASAR Wide Swath image can cover fractions of up to 6 nations EEZ. The existing cost model might be acceptable for nations with a considerable EEZ, but small coastal nations must pay the total cost of the service, even though only a small part of the image covers their EEZ. This makes the service less accessible for nations with a small EEZ. There has been little coordination among users of EObased services, in spite the fact that oil spills often affects neighboring countries as well. With the traditional single user model an identified possible oil spill was only reported to the buying customer, even if the spill was identified in another nation s EEZ. This model was therefore a blockage for the development of a sustainable pan-european service. In order to improve the operational utilsiation of the services, an initiative to develop multinational services was taken by KSAT through an ESA s Marked Development Project four years ago. KSAT initiated a close cooperation between key countries in the Baltic and the North Sea. The idea was to utilize the large coverage of ASAR to develop a harmonized information and costsharing service for the two areas. Establishing a single harmonized service for each area could be the first step towards a sustainable service. The first operational trial started in March 2004 in cooperation with Maritime and Coastguard Agency (UK), The North Sea Directorate (NL) and Federal Institute of Hydrology (DE) as paying customers. Later Belgium, represented by Management Unit of the North Sea Mathematical Models (MUMM) joined the service. The service cost for each nation is calculated based on temporal and geographical coverage of the nations EEZ, and is therefore a proportion of the size of the EEZ. With this model the countries pay only for the part of the satellite image that actually covers their area. This represents a more correct costing of the service and for small coastal nations this service model represents an opportunity to start using satellite surveillance. A slightly different model has been applied in the Baltic where Finland and Sweden coordinates their satellite orders. All requested images are included in one joint service and all countries participating receive results from the analysis performed on these images, e.g. the result of an oil spill analysis from an image ordered and paid for by Sweden will also be distributed to Finland. Poland has been included in the service for a limited trial period. The countries also coordinate flight surveillance for images covering more than one EEZ, and the three countries agree in advance who is responsible for surveillance in the area. Diplomatic clearance has been agreed for flying into each others area. This approach results in a more costeffective utilization of the aircrafts and an improved surveillance for the whole area. This model has been maintained and refined via the ESA GSE Marocast and the MARISS projects by involving the same users. Marcoast includes oil spill detection in the North and the Baltic Sea, while MARISS focuses on ship detection in the Baltic. Figure 5 shows a ship detection and identification example from the Baltic Sea done under the MARISS project. The objective of the MARISS demonstrations is to correlate the SAR derived ship positions with the AIS information, in order to identify targets with unknown identity that will be further inspected. The multi-user model has also been expanded to utilize the same data sets for oil spill, hip detection as well as for extraction of wind speed and direction. The satellite derived wind information is being used by KSAT

4 as one of the input information sources for the oil spill confidence assessments. Figure 6 shows an example of multiple use of the same SAR scene, both for oil spill/ship detection (upper), and for wind information (lower). for various operational reasons has not all the reported spills been verified by the users. The overall delivery of the service information within the 60 minutes has been obtained app. 92 % of the totally applied data. From the delayed deliveries 43 % is within 15 minutes, and 72 % within 30 minutes. The delivery performance has not been fully according to the contractual commitment, and KSAT has performed the necessary actions to improve this. An investment in an upgraded Envisat processor with an increased processing capacity has increased the data throughput and improved the service delivery performance. Figure 5: Ship detection and identification by combining SAR and AIS from the Baltic Sea. The multi national services approach has found a large interest among the involved users. The model has been successfully applied during the last 2-3 years, and the users confirm that this approach both contributes to a significant cost reduction for each country but also improves the cooperation between neighboring countries. For the North Sea service the cost for each nation has decreased and the number of satellite images used to monitor the area has increased significantly compared to the period with single user services in the area. 4 SERVICE PERFORMANCE & IMPROVEMENT The increased user involvement in the service has also contributed to the derivation of more specific service quality parameters, which are listed in the table 1 below. Target Service quality parameters Delivery time 60 minutes after end of acquisition False Alarm Max 10 % false alarms Rate Probability of > 80% minor spills in wind < 12 m/s detection > 90% major spills in wind < 12 m/s Pos. accuracy Better than 250m Table 1: Target service quality parameters. The service has been validated as part of the Marcoast project. The only validated parameter that can be provided with a reliable significance is the delivery time. The statistics on the reliability of the reported spills has been more difficult to obtain. This is mainly due to that Figure 6: Example of multiple-use of a SAR scene in the North Sea service area, both for oil spill/ship (red areas, upper) and wind information (lower).

5 Verification of the reported spills by the users is based on operational decisions. This consequence is that no user feedback has been obtained for 43 % of the totally reported possible spills. 9 % of the reported spills have been confirmed by user verification. For 13 % of the reported spills could nothing could be observed by the users during the verification activities. 5 TOWARDS A PAN-EUROPEAN SERVICE The KSAT oil spill and ship detection service is a result from a long-term national Norwegian service development activity. The service improvements during the recent years has benefited from the national multi-user SatOcean program managed by the Norwegian Space Center (NSC). The aim of this program is to establish a cost-effective use of satellite data for the purpose of national surveillance and monitoring. The program activities include documentation of the national public user needs for access to surveillance and monitoring information in particular over the large ocean areas, pilot service deliveries involving the national users responsible for oil spill detection, ship traffic detection and ice mapping and monitoring. In the ESA GSE Marocast project European service providers were brought together, and a prototype pan- European service network was established. The service concepts as well as the experience from the KSAT service deliveries in Northern Europe have been compared to those of the Southern European MARCOST partners, and a baseline for establishing an operational and harmonized pan-european network was established. The cooperation between KSAT and Telespazio has developed during the Marcoast project, and this resulted in a successful outcome of the respond to the EMSA invitation for providing a pan-european oil spill detection service. Other Marcoast partners are also contributing to this service set-up and deliveries. The EMSA service may be seen as the second step of the service being provided by KSAT to the operational users in the North Sea and the Baltic Sea for years. The existing services now merge into one single North European oil spill service under the responsibility of EMSA, and further expanded into a pan-european service by the service deliveries in the Mediterranean area. EMSA will coordinate the coverage requirements from the individual member states and distribute them to the overall service desk at KSAT. Both Envisat and Radarsat will be applied, and the service information shall now be provided within 30 minutes after acquisition. This service will be fully operational from early Summer The main benefits for the users is expected to be an increased, larger area satellite coverage and improved access to information on all reported oil spill. The final level of the EMSA service is yet not known, but it is expected that individual member states with service requirements beyond those covered by EMSA will manage additional service operations contracts with the providers. The ship detection service in the GMES context is still in the consolidation phase, where the main objectives are to involve the main users, demonstrate the capabilities and better understand the user requirements. KSAT contributes to this activity, and the experience obtained from serving the oil spill users represent important input. The results from these initial activities will be used for continuing into the next phase, and a service development similar to that of EMSA could also be expected. 6 CONCLUSIONS The capabilities to use the SAR data for oil spill and ship detection have been documented during the last ten years, and the operational capabilities have been established [2, 3, 4, 5, 6, 7]. The challenges during these years blocking a fast development of sustainable oil spill and ship detection services have been the dependency of individual nation s annual surveillance budget, high service costs and coordination among the end-users. Fortunately, there have been important improvements during the last couple of years which is now turning this picture. The most important has been the establishment of the EMSA oil spill detection which settles the pan- European legal framework for the service deliveries. The capabilities now available for EMSA are the results of years investment in service development e.g. within national development programs such as the Norwegian SatOcean program and international R&D programs under the responsibility of ESA and EC. These developments have included both technical improvements as well as strengthening the user involvement through service deliveries. The user operational level differ from (near)fully operational to an interested user where documentation of the capabilities still are needed. The development of the KSAT multi-user model has been resognised as an important contribution for expanding the user involvement. The operational utilisation of this model for the users in the North and the Baltic Sea has documented that the cost benefit of the multinational oil spill service has improved compared to the traditional single user services. By the establishment of the pan-european EMSA oil spill service, through which the individual member states will benefit, we have reached an important milestone for the long-term user engagement. The experience from the oil spill service development is now being applied towards a similar

6 development for the ship detection in a pan-european perspective. Other important contributions towards sustainable services are the changes of the practicing of the data and pricing policies. One of the most important modification is the acceptance among the satellite owners of a multiuser data sharing model as compared to the previous oneto-one model. The service validation results now being derived under Marcoast and MARISS show that technical service improvements still will be needed. The most important activity should be to improve the overall service reliability to achieve the 10 % false alarm rate that has been defined by the users. In the pan-european perspective it is important that the service is provided with the same level of reliability and quality. Integration of additional information into the decision and quality assessment process will also be an important part of the service improvement. Wind information from numerical models and from the SAR data is operationally available but the full utilization has yet not been obtained. Additional important information includes algae/biological materials and updated high resolution map coastline information. Harmonisation of the services being provided in the North and South of Europe respectively by KSAT and Telespazio is therefore given high priority. The service chains will likely be different, but harmonisation of the analysis methods and algorithms as well as the decision criteria is now being carried out. The number of service users increase, and the delivery times e.g. for oil spill has been reduced from 60 to 30 minutes. The total workload has therefore increased significantly and the integration of fully automated methods is now becoming mandatory. The future availability of the services is also important and obvious user requirements. KSAT is therefore continuously working towards utilisation of the future SAR missions. Radarsat-2 will be integrated when available during early The initial work towards utilisation of other missions like Cosmo-Skymed, Radarsat follow-on and Sentinel will also be initiated. - SAR based oil and ship detection services. ERS/Envisat Symposium, Salzburg, Austria, September J.P. Pedersen, T. Bauna,.G. Seljelv, F. Landmark, J.H. Andersen, Earth Observation a Cost-effective Improvement for Oil Spill Monitoring,, Proceedings of the 27. ISPRS conference, Tromsø, Norway, J.P. Pedersen, F. Landmark, T. Bauna, R.T. Enoksen, Oil Spill Detection Activities in Norwegian Waters, TSS Report TSS-OLJ-1627/JPP-96, , Paper presented at RADARSAT Workshop T. Wahl, Å. Skøelv, T. Anderssen, J.P. Pedersen, J.H. Andersen, O.A. Follum, G.D. Strøm, T-I. Bern, H. Hamnes, R. Solberg, Radar satellites: A new tool for pollution monitoring in coastal waters, Coastal Management 24:61-71, J.P. Pedersen (Editor), Utilisation of ERS SAR Data for Near real-time Detection of Oil Spills at Sea, TSS Report TSS-CEO-008/JPP-96, February 1996, Executive Summary from Final Report to the EU/CEO Applications Proof-of-Concept Study. 7. J.P. Pedersen, L.G. Seljelv, T. Bauna, G.D. Strøm, O.A. Follum, J.H. Andersen, T. Wahl, Å. Skøelv, Towards an Operational Oil Spill Detection Service in the Mediterranean? The Norwegian Experience: A Preoperational Early Warning Detection Service Using ERS SAR Data», Spill Science & Technology Bulletin, Vol. 3, No 1/2, pp , J.P. Pedersen, L. Steinbakk, M. Indregard, Satellite based oil spill and ship detection service from national towards pan-european multi-user services, Paper presented at the 31st International Symposium on Remote Sensing of Environment (ISRSE) Juni 2005 St Petersburg. 5. REFERENCES 1. J.P. Pedersen, Sathav program, KSAT report L. Steinbakk, JP Pedersen, M. Indregard, ESA/EOMD of Envisat Marine Surveillance Services-