Drogue status of the Lagrangian Submesoscale Experiment (LASER) surface drifters

During the LAgrangian Submesoscale ExpeRiment (LASER), more than 1000 biodegradable drifters were launched in the Gulf of Mexico, in order to study surface flows in winter conditions. The floater, extending 5 cm below the surface, contained the satellite tracking system. The drogue, extending 60 cm below the surface, hung beneath the floater on a flexible tether. On some floats, the drogue separated from the floater during storms. An algorithm was developed to detect drogue loss based on two properties that distinguish drogued from undrogued drifters. First, undrogued drifters often flip over, pointing their satellite antenna downward and thus intermittently reducing the frequency of GPS fixes. Second, undrogued drifters respond more strongly to wind forcing than drogued drifters. 40% of the drifters were found to have lost their drogues in the first 7 weeks between January 20, 2016 and March 29, 2016. Drogue loss times were estimated with a precision of less than a half-hour for 60% of the drifters and less than 3 hrs for 85%. The data set contains the drogue status and drogue-loss estimates of all drifters released during LASER, including the precision and uncertainty levels, as well as the drogue loss estimates from GPS transmission anomalies only. Raw drifter data can be found in GRIIDC dataset R4.x265.000:0027.