Hach 2100AN

Manufacturer: Biospherical Instruments Inc.

www.biospherical.com

The PRR-600 is hand-lowered profiling reflectance radiometer designed to measure downwelling irradiance, upwelling irradiance, and reflectance in the SeaWiFS wavelength bands. Measures seven channels each of downwelling irradiance and upwelling radiance (412, 443, 490, 510, 555, 665 nm, and PAR (400-700 nm)). Near-synchronous (milliseconds) sampling of downwelling and upwelling signals. Temperature and depth/pressure transducers operate to 200 m. Tilt and roll sensors included. Fully integrated and microprocessor-controlled.

Freefall design for free descent mode away from the ship. Cable length is about 90 m.Filter photodetectors in the PRR-600 are specified to 10 nm FWHM +/- 1 nm with center wavelengths designed to hit the SeaWiFS bands while taking into account details such as the viewing geometry of the system. Both the irradiance and radiance detector geometries have been designed to limit the solid angle to 10o, and the filter design has been specified to compensate for this solid angle in arriving at the center wavelengths and bandwidths in the assembled instrument. The PRR-600 irradiance collector is Teflon®, backed with quartz, optimized for excellent cosine response in water.

The signals from all sensors are digitized and available as RS-232 output. Data are presented as 12-bit mantissa plus 2-bit exponent plus sign. Complete software is provided for decoding the binary data to ASCII files. Irradiance sensors are calibrated using a NIST Standard of Spectral Irradiance. Radiance calibrations are performed using a 61 cm integrating sphere tied to the NIST Standard of Spectral Irradiance with a calibrated transfer radiometer and reference reflectance plaque. Instrument calibration need to be repeated. Last calibration 199?

The PRR-600 radiometer is equipped with a compact, splashproof, plastic deckbox that provides computer interface and power distribution. PRR-600 software is menu-driven and provides data acquisition, display, and analysis functions (MS-DOS based, but relatively user friendly. See details on web page).