The history of the first decade of the observing system in the Gulf of Maine, and plans for the second decade

Abstract

The coastal ocean observing system in the Gulf of Maine was deployed in the summer of 2001. The system operated a real-time data buoy array that collected oceanographic and meteorological measurements in a 24/7 operation at as many as 11 locations in the Gulf of Maine (GoM). The data return of the GoM sensor array has averaged approximately 90% over its first decade of operation. In addition to the hourly operational data delivery to several online websites, the University of Maine provides an archive of data and model output that are significantly advancing the scientific understanding of the GoM as a physical and ecological system. Over the decade of operation, the data have revealed marked seasonal and interannual variability of the circulation and physical properties of the gulf. From the time of the initial deployments in the summer of 2001, the GoM buoy array has been an unusually comprehensive suite of oceanographic sensors including surface current meters, Doppler current profilers for subsurface currents, temperature, salinity, dissolved oxygen, chlorophyll and colored dissolved organic matter (CDOM) fluorometers, radiometers, multi wavelength absorption, and attenuation sensors at multiple depths. In addition, wave instruments and meteorological sensors were deployed on the buoys including air temperature, wind speed and direction, atmospheric pressure, and forward scattering visibility. In recent years the sampling scheme of the system has increased in resolution beyond hourly for several high-value data streams. The meteorological data are collected at ten-minute intervals, and water-column temperature and salinity are measured at three-minute intervals to provide records of internal wave activity. The higher frequency records are not provided in real-time. The full ten-minute meteorological data are updated hourly (or half-hourly during storm events), and the higher frequency temperature and salinity data are updated semi annually. Wave measurements have recently included wave directional spectra. The broad suite of sensors on the GoM Integrated Ocean Observing System (GoMIOOS) serve a wide variety of real-time oceanographic and marine meteorological data and data products to scientists, state and federal regulators, the National Weather Service, the US and Canadian Coast Guards, educators, regional natural-resource managers, the Gulf of Maine fishing and maritime industries, fishermen, boaters, and the general public. The success of the system has resulted inan energized and enthusiastic scientific and technical community involved in operational ocean observing activities, and a large user group which have come to depend on the real-time data streams the system provides. The first decade of data collected by the GoMIOOS has provided a wealth of scientific information, and lead to a new understating in of the oceanography of the GoM. In many cases the buoy array provided the first baseline information as well as the first comprehensive characterizations of marked seasonal and interannual variability of the circulation and physical properties of the Gulf. Between the fall of 2004 and spring of 2005 Doppler currents measured, for the first time, outflow of deep salty slope waters that suggested a regime shift in the transports through the Northeast Channel (NEC). Experiments from earlier decades consistently observed inflow of dense slope waters throughout all seasons. During the same period a salinity anomaly event lowered salinity throughout the GoM by roughly 2 psu by the winter of 2005. In following years, the previously unusual slope outflow and reduced salinity have often reoccurred. These modern measurements are oceanographic anomalies that suggest climate change may be causing significant physical transformations. Ocean sensors, ocean platform technologies, and modeling and visualization techniques are in a period of rapid technical development. If stable funding can be achieved, the capabilities of operational ocean observing systems will increase dramatically over the next decade. Autonomous vehicles could become the fast response survey fleet of the Integrated Ocean Observing System (IOOS®), as well as the workhorses for routine, sustained, marine survey functions that are currently prohibitively expensive using research vessels. Practical autonomous vehicles will likely expand beyond gliders and propeller-driven autonomous underwater vehicles (AUVs) to include autonomous surface vessels (ASVs). The combination of time-series measurements from profiling packages on buoy arrays with the repeated spatial surveys of the autonomous fleets will provide a new look at our coastal oceans that could transform coastal ocean science and management.