A review of the drogue sensor 

 data provided by the five recov- 

 ered buoys shows that the pres- 

 ence of the drogue was reliably 

 reported in all cases. Two of the 

 buoys (4530 and 4566) had short 

 periods (< 4 days) during which 

 the drogue sensor indicated 

 detachment. In the case of 4566 it 

 occurred when the buoy entered a 

 shallow area and it is likely that 

 the drogue was dragging on the 

 bottom. In the case of 4530 it 

 occurred during the first four days 

 after its launch. This suggests 

 tangle of the tether which eventu- 

 ally broke free. After the buoy and 

 drogues were recovered all of the 

 drogue sensors properly recorded 

 drogue detachment. 



MINI-DRIFTING BUOYS 



Since 1986, the International Ice 

 Patrol has been cooperating with 

 the U. S. Naval Oceanographic 

 Research and Development 

 Activity (NORDA) in field testing 

 small (~ 1 m long and 20-30 kg) 

 and low cost ($2-3,000) drifting 

 buoys. These mini-drifters have a 

 design life of 3-4 months and 

 come in a variety of configura- 

 tions. There are several reasons 

 why they might be more appropri- 

 ate for use in the Ice Patrol buoy 

 program than the currently-used 

 standard configuration. The 

 smaller buoys cost less than half 

 as much as the standard buoys, 

 which would permit more than 

 doubling the number of buoys 

 deployed each season for the 

 same cost. Their small size 



makes storing, transporting, and 

 deploying the buoys easier. 

 Finally, their design life is well- 

 matched to the average period 

 that a drifter remains in the Ice 

 Patrol operations area (2-3 

 months). The current configura- 

 tion transmits for about a year, 

 while the buoy typically remains in 

 the Ice Patrol operation area and 

 the drogue remains attached for 

 about a third of that time. 



Before integrating the mini-drifters 

 into the Ice Patrol program, the 

 issues of reliability, accuracy, and 

 drift characteristics need to be 

 considered. Anderson (1987) 

 described the details of a 1986 

 field test, which was conducted 

 entirely in the relatively calm and 

 warm waters of the Gulf of Mexico. 

 Thayer et. al. (1988) and Pickett 

 (1989) describe the 1988 field 

 tests, which were conducted in 

 both the Gulf of Mexico and the 

 rougher and colder waters of the 

 North Atlantic. The goals of these 

 two tests were essentially the 

 same: first, to determine if the 

 buoys would survive air deploy- 

 ment over a wide range of altitude 

 and speeds and, second, to 

 determine if the buoy lifetime and 

 number of ARGOS fixes per day 

 was consistent with the perform- 

 ance of the standard buoys. 



The 1988 field tests showed that 

 the buoys survived the air drops 

 well, but that the buoy life was far 

 short of the 3 month design life. 



All of the mini-drifters used in the 

 1988 tests were Compact Mete- 

 orological and Oceanographic 

 Drifters (CMOD), which are 

 manufactured by METOCEAN of 

 Halifax, Nova Scotia. The drogue 

 consists of the cylindrical outer 

 case of the drifter (approximately 

 12 cm by 70 cm) tethered at 100 

 m. The buoys are equipped with a 

 barometer, air and sea surface 

 temperature sensors. There is no 

 drogue sensor. 



The 1988 tests showed that the 

 CMOD's survived an average of 

 34 days in the Gulf of Mexico and 

 17 days in the North Atlantic. Of 

 the five deptoyed by Ice Patrol 

 aircraft, two were deployed in the 

 Ice Patrol operations area (1388 

 and 1387). Buoy 1388 failed upon 

 deployment and 1387 provided 

 data for fifteen days. Two 

 CMOD's (1386 and 1389) were 

 deptoyed in the North Atlantic by 

 Ice Patrol aircraft enroute between 

 the United States and Newfound- 

 land. Buoy 1 386 transmitted data 

 for 22 days after its deptoyment 

 and 1 389 for thirteen days. The 

 fifth CMOD (3435), deptoyed by 

 Ice Patrol for AES, was launched 

 with a standard buoy (4566). 

 Buoy 3435 failed after twelve 

 hours of drift and its track is of little 

 value. The data from the one 

 CMOD (1387) that did provide a 

 significant trajectory in the IIP 

 operations area are described 

 below. 



75 



