Description: The Naval Research Laboratory (NRL) has developed a shallow water environmental profiler the autonomously measures physical and optical properties of the water column at periodic, user-specified intervals over an extended time period (weeks to months). The profiler is a trawl-resistant bottom mooring equipped with a bottom-up profiler. Data are collected and stored on-board, and can be transmitted in near-real-time to a land station when the profiler surfaces. The patent-pending NRL system, equipped with advanced instrumentation, includes the capability to simultaneously collect measurements of physical and bio-optical properties. Physical Measurements: temperature, salinity, pressure, currents, and waves. Bio-optical Measurements: bean-attenuation coefficient, backscattering coefficient at three wavelengths, downwelling irradiance at seven wavelengths, chlorophyll, phycoerythrin, and colored dissolved organic matter fluorescence. A small profiling unit was designed to optimally accommodate all the sensors within the required space confines, but with adequate buoyancy for non-powered ascent during vertical profiles. The complete measurement data set is archived on the unit and a user-specified subset is transmitted on the next ascent to a land station using Iridium satellite communications when the profiler float is at the surface. This system provides a unique capability of monitoring water column properties at a fixed location and broadcasting data for operational use, while maintaining a non-interfering trawl-resistance posture.

Advanced Control Features:

  • Custom-designed hardware and software control system, developed to integrate all the sensors, data flow, storage, and transmission.
  • Programmable, dynamic configuration for event scheduling.
  • Base and profiling unit electrically isolated; computers communicate via inductive coupling, enabling event coordination and synchronization, as well as real-time updates to the system configuration.
  • Inductive charging system is also employed to recharge the profiler batteries from the larger bank of batteries in the base unit to achieve a maximum power budget.

Advantages/Features Include:

  • Autonomous Measurement: Both optical and physical properties of the water column can be autonomously measured at a single location over extended periods of time.
  • Fixed Location: Measurements at a fixed location can be easier to interpret for operational and scientific purposes and limits the risk of system loss.
  • Trawl-Resistance: The form factor of the bottom mooring and the bottom-up configuration of the profiling unit greatly reduce the likelihood of damage from ship trawling.
  • Improved Antenna System: Allows for more reliable real-time data transmission of measured properties.
  • Improved Software and Hardware Systems: Better integration allows for complex configuration of data collection protocols and data flow.

Applications Include:

  • Harbor protection
  • Marine park monitoring
  • Integrated coastal observing systems
  • Environmental protection monitoring
  • Coastal protection systems
  • Satellite algorithm development and validation


  • Book, J.W., P. Martin, M. Rixen, J. Dykes, D. Wang, S. Ladner, M. Tudor, and J. Chiggiato. 2008. "Real-Time Coastal Monitoring and Prediction for Operations and Research." 2007 NRL Review, Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, DC 20375, pp. 187-190.
  • Book, J., M. Rixen, A. Carta, M. Hulbert, A. Quaid, E. Coelho, V. Grandi, and L. Gualdesi, 2007: "Shallow Water Environmental Profiler in Trawl-Resistant Real-Time Configuration (SEPTR) Used for Frontal Dynamics Research. " 2007 - Rapp. Comm. Int. Mer Medit., Vol. 38, pg. 130, CIESM Congress (Instanbul, 2007), CIESM: The Mediterranean Science Commission, Monaco.

Back to Oceanography
Technology Tags: