Methodology:

Three drifting buoys (with ID numbers 103, 104, and 105) were deployed during the cruise to track the position of precipitation-receiving water masses (eddies) and simultaneously record temperature and salinity. The drifters were equipped with 10-m drogues and so approximately follow the surface mixed layer; the sensors were located at the depth of approximately 2 m.

Instruments:
Model 121 GPS / Iridium drifters by Brightwaters Instruments (BI) with temperature and salinity sensors (http://brightwaters.com/products/121/121.htm). Model 121 a current following (Lagrangian) drifting buoy, is released in a body of water and moves with the currents over a period of hours to months. Onboard electronics acquire a time series of positions using the Global Position System (GPS) as the drifter moves. Positions and optional sensor data are telemetered over the worldwide Iridium satellite network and delivered to the end user via a web browser. The DANCE drifters were configured with the “standard” size hull, which is approximately 1 meter (40 in.) tall excluding the antenna mast and weighs about 11 Kg (24 lbs). The Model 121 features a 12 channel GPS receiver and records position to 0.001 minute of latitude and longitude (1.8 meters). Absolute accuracy of the position is better than 15 meters worldwide. In areas served by one of three Satellite Based Augmentation Systems (WAAS in North America, EGNOS in Europe, and MSAS in East Asia) absolute accuracy is better than 3 meters 2DRMS. BI conductivity / temperature sensor: -10 to +40C, resolution 0.01C; 0-60 mmho/cm, resolution 0.01 mmho/cm; full digital sensor with individual calibration yields typical postprocessed accuracy of 0.05C and 0.05 mmho/cm.