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Oceanology International 2014 – Maritime Security Ambient Noise Measurement Using Naval Sensors Daniel Toogood – Marine Scientist AEUK/14/0309 Presentation Overview • Introduction to acoustics within Royal Navy operations • The importance of ambient noise in the marine soundscape • Ambient noise complexity and variability • Outline of how acoustic data is collected • Strengths and limitations for environmental understanding • Knowledge exploitation – Marine Strategy Framework Directive • Data dissemination Role of the UK Royal Navy • Protection of UK Interests – Sea Lanes – Strategic Assets – Sovereign Waters • Maritime Security – Piracy – Narcotics • International Engagement – Humanitarian Support – Joint Operations • Operate in a Global Environment – Littoral and freshwater – Blue water and open ocean – Extreme environments – Arctic, Antarctic The importance of sound…. • Other energy types can’t propagate within the ocean – Light - tens of metres, very high data rate – High Frequency (HF) Radio – few metres – Extremely Low Frequency Radio (ELF) – hundreds km, low data rate • Extended range (dependent on frequency) – 100 Hz (minimal attenuation) – 1 kHz (0.019 dB / km) – 10 kHz (0.19 dB / km – 100 kHz (90 dB / km) (high attenuation) • Acoustic waves have slow propagation – Acoustic - 340 m/s (air) – Acoustic – 1500 m/s (water) – EM Waves - 300,000 km/s (air) Understanding the environment • Physical Oceanography – Temperature – Salinity – Vertical structure – Seastate / waves – Bubbles – Precipitation – Suspended sediment • Geophysics – Sediment characteristics – Seabed roughness • Biological content – Cetaceans – Snapping shrimp – Fish • Spatial and temporal variability • Seasonal variation • Daily variation • Tidal variation • Ambient Noise Modelled Sound Propagation - January Modelled Sound Propagation - February Modelled Sound Propagation - March Modelled Sound Propagation - April Modelled Sound Propagation - May Modelled Sound Propagation - June Modelled Sound Propagation - July Modelled Sound Propagation - August Modelled Sound Propagation - September Modelled Sound Propagation - October Modelled Sound Propagation - November Modelled Sound Propagation - December Modelled Sound Propagation - January vs August • Spatial variability – freshwater run off, fronts, etc • Temporal variability – diurnal variation, ocean stratification, etc • Optimum periods for high energy anthropogenic activity! Wenz, 1962 Ambient Noise • Natural – Biological – Geological/earthquakes – Meteorological/oceanic conditions – Ice • Anthropogenic – Offshore renewables – Commercial shipping – Sonar – Acoustic deterrent devices (ADDs) – Industry/construction/explosives • Structure – Continuous – Impulsive • Varies with: – Frequency – Sound speed profile – Direction – Time – Sensor depth – Bottom type – Water depth – Sea-state Military application of sound • Passive sonar = ‘listening’ to underwater noise and analysing it to discriminate natural and man-made objects • Active sonar = transmission of a pulse followed by analysis of the echo • Different objects have different characteristics…the ‘noise’ is the background against which the military are trying to detect, classify and localise • “One man’s noise is another man’s signal”….large proportion of marine community is investigating ‘underwater noise’ rather than identifying discrete objects Navy Sonar Capability • Wide bandwidth: 10s Hz 100s kHz • Multiple transducers arranged into arrays • Increase signal to noise ratio – provides ambient noise directionality • Some sensors can be deployed at selectable depth to exploit propagation paths provides information on noise variation with depth • High capacity data recording increasingly available LF towed array HF Diver Detection MF Bow Array LF towed array HF hull array MF bow array MF flank array Balance of Naval Data for Environmental Understanding Positive • Some regions not normally accessible by civilian scientific vessels Negative • Protection of assets is the priority • Sensors are highly accurate • Some data would need be de-sensitised (remove sensitive characteristics) • Data recorded to established standard, using detailed protocols • Data may vary in some spatial and temporal aspects • Data from platform patrols are stored • At present no established broad distribution • Decadal scale repetition • Routine quality assurance • Will continue into the future… How could such data be useful… • Establish longer term datasets for an area – Acoustic soundscapes – Shipping noise levels – Global warming / ocean acidification (supporting environmental data) – Baseline noise levels for areas of emerging commercial interest (arctic, deep sea) • Supports predictive modelling – Validation data • Support of legislation – Marine Strategy Framework Directive…. Ambient Noise and the MSFD • Establish Good Environmental Status - GES • Descriptor 11 – “Introduction of energy, including underwater noise, is at levels that do not adversely affect the marine environment” • “Protect and preserve the marine environment, prevent its deterioration or, where practicable, restore marine ecosystems in areas where they have been adversely affected” • “Prevent and reduce inputs in the marine environment, with a view to phasing out pollution, so as to ensure that there are no significant impacts on or risks to marine biodiversity, marine ecosystems, human health or legitimate uses of the sea” Ambient Noise and the MSFD – Descriptor 11 • Ambient Noise Monitoring Programme • Cefas (under defra funding) are currently evaluating possible ambient noise studies • To be coordinated via the UK Clean and Safe Seas Evidence Group (CSSEG) – Input from the MSCC Underwater Sound Forum – EU Technical Sub-Group (TSG) – Project will identify suitable sources and sample data – Then design and implementation of UK monitoring programme • Military data could contribute! Marine Strategy Framework Directive Consultation, January 2014. Defra. Available: Here Dissemination Pathway Civilian Holdings MoD Holdings Platform CSSEG Shore • Determine GES • Ship/sub/aircraft • Data analysis • Analysis • Acoustic/ environment sensors • Removal of sensitive facets • Incorporation into modelling/study • Quality Control Into Policy… Public Data Access • Immediate storage • Operational analysis UK Data Portals • BODC End User… • Model incorporation • Wider dissemination • Further independent analysis Key Questions…. Key Questions • Who pays? • Who stores? • Who has access? • How is it broken down? • Temporal/Regional composition? • How long is data available? Precedents Exist • MSFD – Noise register • UKHO Sonobuoy data • Cetacean stranding Contact ATLAS ELEKTRONIK UK Ltd. Dorset Green Technology Park Winfrith Newburgh Dorchester • DT2 8ZB United Kingdom Phone: +44 (0) 1305 212400 www.uk.atlas-elektronik.com