The WALRUS is a compact tethered buoy that consists of five miniature spectrometers configured to measure upwelling radiance at four points both above and below the surface, and downwelling irradiance incident on the surface.  It also incorporates an electronic compass and tilt/roll sensor which are sampled along with the radiometric measurements.  The WALRUS can be either hand-deployed for station-to-station sampling or moored for moored for time-series sampling at a single location. 

The WALRUS  is completely self-contained and can be operated manually, autonomously, or via an externally connected computer for real-time data collection and display. A sophisticated embedded controller powered by internal rechargeable batteries (or powered externally if desired) performs all of the functions for operating and collecting data from the spectrometers. The controller is programmed to seek optimal integration times depending on light levels, automatically correct for dark current, and radiometrically calibrate the output data. It has many other sophisticated programming functions for autonomous operation.

The WALRUS contains five independent radiometers for measuring plane irradiance and radiance from 350 to 850 nm with 2.5 nm FWHM resolution. Completely self-contained with programmable controller, data logger and rechargeable batteries.

• Up to five independent channels (CCD spectrometers) for measuring up to four light-field quantities (irradiance or radiance) nearly simultaneously.
• Measures light-field quantities from 350 to 850 nm with 2.6 nm FWHM resolution with absolute radiometric accuracy of 98%.
• Sophisticated embedded controller is easily programmed for autonomous data collection (e.g., moorings) or communicates with external computer.
• Built-in auto exposure and dark correction plus radiometrically calibrated output.
• Up to 512 MB of nonvolatile flash memory for internal logging.
• Can be connected to an external controller or can be operated completely autonomously.

• Ocean-color remote sensing - Measure above and in-water remote-sensing reflectance.
• Environmental monitoring - Self-mooring or Tethered.