A Surface Drifter For Cost-Effective Meteorology and Oceanography
Surface Velocity, Temperature, Barometric Pressure, Salinity, Air Temperature


ClearSat-2.0 Argos PTT* in ClearSat-15 surface Sphere.

Description

The ClearSat-15 surface drifter accurately follows the surface mixed layer at 15 meters and provides a platform for oceanographic and meteorological measurements at the sea surface. Data from anywhere in the world are reported to the user by satellite telemetry though the Argos system which also makes accurate locations of the drifter's position. Drifter configuration follows the design specifications of WOCE/SVP surface drifters1: spherical shapes for surface and subsurface floatation elements, heavy reinforcement of the tether in the near surface portion, rubber boots at stress concentration points which occur at tether transitions, and a seven-section holey-sock drogue. Each drogue section is a cylinder 1 m high by 1 m in diameter with two opposing holes of diameter 0.5 m cut in its sides. Alternate sections have the holes rotated 900. The holes minimize lift and the tendency of a cylinder to sail. Standard instrument suite reports sea surface temperature, battery condition, and drogue presence. The ClearSat-2.0 PTT, microcontroller and antenna are contained completely within a rugged surface float of fiberglass or ABS plastic. Options include alternate tether lengths, barometric pressure, air temperature, salinity (conductivity/temperature), self-deployment packaging for launching at sea level or from an aircraft, and GPS positioning (accurate to 20 meters).

Technical Specifications:

Physical Hull 33.7 cm. (13.25 in) diameter fiberglass or 40.6 cm. (16 in) ABS; total weight 20 kg (45 lb.).
Drogue 1 meter x 7 meter holey sock centered at 15 meters.
Power Supply 13.5 VDC, 56 AH, sufficient for one year at continuous transmission, or 2 years 1/3 duty cycle.
Transmit Cycle Continuous, 8/16 , 12/12, 12/24, 24/48 (hours on/hours off)
Sea/air Temperature SST: Linearized thermistor sensor imbedded in 316-ss through-hull fitting at base of surface float;fast time- constant design.
Air: Linearized thermistor in flexible probe. Calibration to 0.1oC provided. Temperature range is -5 to 45oC. Accuracy is 0.1 C
Barometric Pressure 800 - 1100 +/- 0.3 mb, 13 or 25 hourly pressures (DBCP format), double battery pack (ClearSat-15 Barometer).
Sea Surface Salinity C/T measurement, 0 - 64 +/- 0.025 mmho/cm., -5 - 35 +/- 0.05 C, 12 hourly samples (ClearSat OPTION).
GPS Year, month, day, hh:mm:ss +/- 1 sec, latitude and longitude +/- 0.0001 deg., 4 to 13 positions, double battery pack (ClearGPS OPTION).
RF output 1± .3 watt into 50 ohms, BNC.
Environmental -50 to 30°C, storage (alkaline battery life is significantly reduced at storage temperatures >30C)
-5 to 45°C, operation.
1 Sybrandy, A.L. and P.P. Niiler, 1991. WOCE/TOGA Lagrangian Drifter Construction Manual, Scripps Institution of Oceanography, SIO Reference 91/6, WOCE Report Number 63.
* CLS/Argos-certified.
For further information about Argos data collection services:
U.S.: North American CLS, Inc., 9200 Basil Court, Suite 306, Landover, MD 20785, U.S.A. Europe: CLS/Service Argos, 18 avenue Edouard Belin, 31055 TOULOUSE Cédex, FRANCE Voice: 61 39 47 74 Telex: 531 752F Fax: 61 75 10 14