Riverine drifter in Boston Harbor

Clearwater is pleased to announce the Riverine Drifter, a highly integrated, small, light-weight instrument designed for detailed surveys of currents and bathymetry in shallow environments. Riverine Drifter is a scaled down ClearSat-1 drifter instrumented with a Nortek Aquadopp modified with a fourth sensor for highly accurate bathymetric measurements, GPS location, 212 MB Compact Flash Card, and Iridium 9601 SBD modem. As it drifts with tidal currents, Riverine Drifter is able to take detailed profiles of 3-D current structure and depth all tied back to GPS time and geographic coordinates. Data excerpts can be relayed to the user via Iridium SBD. The entire data set is easily downloaded from the memory card. Sampling rates for Aquadopp and GPS can be as high as 1 Hz. Extensive field tests have been conducted in a variety of environments in Boston Harbor. Clearwater has shipped its first Riverine Drifters to Dr. Luca Centurioni at the Scripps Institution of Oceanography for use in studies of river discharge off the coasts of Southern California.

Photograph of Argos 3 PNT-K and antenna in Clearwater Instrumentation SVP drifter

Clearwater has completed integrating the new CLS Argos 3 PMT into applications for drifters incorporating Sea Surface Temperature, Air pressure and GPS location. These newly developed applications for the WOCE SVP drifter used in the Global Drifter Program, studies of surface circulation and observational operations offer potential advantages over similar equipment equipped with the Argos 2 PTT. Unlike the Argos 2 PTT the Argos 3 PMT receives a downlink message from Argos 3 satellites which informs it of the time, satellite ephemera, and PMT location. This information allows the PMT to transmit only in the presence of a satellite saving valuable energy which otherwise would be wasted. Early indications are that power requirements are reduced by 75% by not transmitting to an empty sky and that data returns are better than 95% because it only is sent when a satellite is overhead. In addition, improvements in data management by the PMT and in data processing by CLS can provide error checking, accurate sample times and advanced processing. Using Argos 3 means that a scientist can get exactly the accurately obtained data time series she wants.

Clearwater has completely upgraded its SmartSensor temperature string to make it smaller and lighter while improving its reliability and life. With a complete redesign of the MasterModem surface receiver and subsurface SmartSensor nodes, the new system is easier to handle and lasts up to 500,000 temperature-pressure cycles. The strings which are built on rugged polyethylene-coated steel mooring wire can be ordered with up to 20 nodes with temperature and pressure, or any combination of temperature-pressure nodes and temperature only nodes and lengths up to 300 meters.

Clearwater has developed a high data rate system for drifters integrating extensive subsurface observations. The first ClearSat-HDR system was built for Dr. Luca Centurioni at the Scripps Institution of Oceanography and integrates a Nortek Aquadopp into a Clearwater SmartSensor thermistor string consisting of 20 nodes measuring temperature and pressure. The Aquadopp and SmartSensors are interrogated every 90 seconds. Data are accumulated in the surface host and 6 KB messages are sent to the user every half hour using inexpensive Iridium RUDICS. The ClearSat-HDR system can be configured to collect subsurface data from any instrument with a serial interface. The data communication system also is compatible with surface applications producing volumes of data approaching 500 KB per day.

Red Sea Drifter Tracks

One hundred ClearSat-1 drifters are gathering data for a WHOI/KAUST project on near-surface Lagrangian currents in the Red Sea. This study, headed by principal investigators Robert Beardsley, Richard Limeburner, and Roger A. Goldsmith, will be the first research to gather and examine detailed data on near-surface currents in this eastern region of the Red Sea. The ClearSat-1 drifters allow detailed, spatially explicit measurement of near-surface current velocity at multiple spatial and temporal scales. Visit WHOI’s Red Sea 2008 research page to read a summary of the project and view some of the initial data our drifters have gathered. 

This image shows test data as displayed by Google Earth.

Ice Buoy

In collaboration with LBL Inc., we have developed a test version of an ice buoy that can tolerate the extreme stresses of ice movement. The ever-increasing need to monitor changing polar conditions is requiring a corresponding investment in research instrumentation suited to the extremes of these environments. In collaboration with LBL Inc., we have developed a test version of an ice buoy that can tolerate the extreme stresses of ice movement. The ever-increasing need to monitor changing polar conditions is requiring a corresponding investment in research instrumentation suited to the extremes of these environments. In collaboration with LBL Inc., we have developed a test version of an ice buoy that can tolerate the extreme stresses of ice movement. The ever-increasing need to monitor changing polar conditions is requiring a corresponding investment in research instrumentation suited to the extremes of these environments. In collaboration with LBL Inc., we have developed a test version of an ice buoy that can tolerate the extreme stresses of ice movement. The ever-increasing need to monitor changing polar conditions is requiring a corresponding investment in research instrumentation suited to the extremes of these environments.