The Liverpool Bay Coastal Observatory - towards the goals

A pilot Coastal Observatory was established in Liverpool Bay (eastern Irish Sea) in 2002 with an anticipated lifespan of at least 10 years. In an evolving process, near realtime measurements are integrated with coupled models in a pre-operational prediction system. The aim is to understand a coastal sea´s response to natural forcing and the consequences of human activity, providing scientific underpinning for coastal management. The impact of human activity on the world´s oceans and the use made of them by humanity is greatest in coastal seas. The eastern Irish Sea is an excellent study area, affected by all coastal sea processes with tidal forcing dominant and near-shore physical and bio-geochemical processes influenced by estuarine discharge where both vertical and horizontal gradients are important. The sea is subject to a range of human industrial, agricultural, fishing and recreational pressures. The time series measurements enable definition of the seasonal cycle, its interannual variability and quantification of the importance of events relative to the mean. Applications include eutrophication (the region receives significantly elevated levels of nutrient inputs), shoreline management (coastal flooding and beach erosion/accretion), and understanding present conditions to predict the impact of climate change (for instance if the number and severity of storms, or of high or low river flows, change). The integrated, systematic measurement suite, which started in August 2002, covers a range of space and time scales, concentrating on horizontal and vertical gradients, and includes in situ surface waves and vertical profiles of current, temperature, salinity, turbidity, nutrients and chlorophyll; regional water column surveys nine times a year; shore-based phased array HF radar measuring waves and surface currents out to a range of 50 km; instrumented ferries measuring surface properties; coastal tide gauges; satellite data-infrared (for sea surface temperature) - - and visible (for chlorophyll and suspended sediment). Acoustic telemetry and the Orbcomm satellite system are the primary resource for in situ telemetry. The core measurements and infrastructure also form the basis for process studies, instrument trials, for instance a three week glider deployment, and for the incorporation of new sensors. In cooperation with the UK Met Office, and as a component of the National Centre for Ocean Forecasting, a suite of nested 3-dimensional models (the Proudman Oceanographic Laboratory Coastal Ocean Modelling System-POLCOMS) is run daily, focusing on the Observatory area by covering the ocean/shelf of northwest Europe (at 12 km resolution), the Irish Sea (at 1.8 km) and Liverpool Bay (at ~ 200m resolution). These models simulate the physical (hydrodynamic coupled with wave) environment, nutrient and plankton dynamics, and the processes influencing sediment suspension and transport. The measurements test the models against events as they happen in a truly 3-D context - most is learned when model predictions diverge from reality. The value of some of the observations is enhanced by data assimilation which benefits both the models, keeping them on track, and the observations, augmenting their spatial coverage. All measurements and model outputs are displayed on the Coastal Observatory web-site for an audience of researchers, coastal managers and the public. After nearly 4 years of operation we are beginning to build up a picture, which only continuous monitoring provides, of the interaction between a coastal sea and its major estuaries. As always more detailed measurements indicate that processes are more complicated and distributions can have large variability