Presentationto

Data Buoy Cooperation Panel XVII

J-CAD (JAMSTEC Compact Arctic Drifter)

October 25, 2001 DBCP XVII Page 2

Presentation Outline

• Design Requirements

• Sensors

• Mechanical Characteristics

• System Electronics

• Data Telemetry

• Testing

• Deployments to Date

• Conclusions

October 25, 2001 DBCP XVII Page 3

Design Requirements

• Reduce size, cost, and scope of observations from the buoys developed for the IOEB (Ice-Ocean Environmental Buoy) program

• Use bi-directional ORBCOMM telemetry

• Provide GPS positioning so that under ice-ocean currents can be measured

• Use inductive modem system for all underwater sensors

• Reduce weight to less than 250 kg so the buoy may be easily deployed using a small, light-weight crane

• Provide underwater sensors less than 28 cm in diameter so 30 cm twist drill can be used for sensor deployments

• Provide hourly measurements over a two-year operating lifetime

October 25, 2001 DBCP XVII Page 4

October 25, 2001 DBCP XVII Page 5

J-CAD Sensors

• Meteorological Sensors– YSI thermistor for air-temperature in a naturally aspirated, Gill-plated radiation

shield– Paroscientific Model 216 B barometer with a METOCEAN-designed barometer

port– RM Young Model 5106-MA propeller anemometer mounted about two meters

above the ice• Oceanographic Sensors--data telemetry by Sea-Bird inductive modems

– Two RDI WorkHorse 300 kHz ADCPs measuring 16 layers every 10 minutes• Downward facing unit at 12 m• Upward facing unit at 260 m

– Six Sea-Bird SBE 37 IM CT sensors at 25 m, 80 m, 110 m, 180 m, and 250 m• Pressure data at 110 m and 250 m

• Buoy Monitoring Sensors– Precision navigation, three-axis magnetometer for platform orientation– YSI thermistor on platform hull to provide sea-ice or seawater temperature– Jupiter Model TU30 12-channel GPS receiver

October 25, 2001 DBCP XVII Page 6

J-CAD Mechanical Characteristics

• Electronics Enclosure– 8-inch Sch 40 aluminum pipe acts as enclosure for electronics and lithium

battery packs– RS-232 water-tight port for system testing and data download– Barometer port mast supports GPS and Argos antenna and air-temperature

radiation shield

• Floatation– Surlyn lonomer collar, manufactured by The Gilman Corporation, is highly

resistant to damage by ice– J-CAD will float if ice breaks-up

• Tripod Mast– Supports ORBCOMM antenna and propeller anomometer

October 25, 2001 DBCP XVII Page 7

October 25, 2001 DBCP XVII Page 8

J-CAD System Electronics

• System Controller– METOCEAN digital controller based on Model MAT 906 Argos PTT– Onset Computer Tattletale Model 8 data logger and master controller with 48 MB flash card memory– Modular design provides redundancy

• Underwater Telemetry– Sea-Bird inductive modem with a single conductor, oceanographic cable– Tattletale 8 controller for data logging for all underwater sensors

• Data Collection and Processing– METOCEAN controller handles all meteorological sensors, GPS, and Argos telemetry– Tattletale 8 controller handles central system time, underwater telemetry, and ORBCOMM telemetry– At approximately 10 minutes prior to the hour, sensor sampling commences– Data processing of all sensors begins at the top of the hour and proceeds for 10 minutes after the hour– Data is stored and then readied for transmission 15 minutes after the hour

• Satellite Telemetry– ORBCOMM telemetry is the primary operational mode; Argos is the back-up mode

• Power Supply– Two 245 Ahr lithium battery packs--one only for the ORBCOMM SC and the other for the rest of the

system

October 25, 2001 DBCP XVII Page 9

CTD #1110 METERS

IND COUPLED

October 25, 2001 DBCP XVII Page 10

J-CAD Data Telemetry

• ORBCOMM is the primary telemetry system– ORBCOMM SC is a Panasonic Model KX-G7101, with GPS capability, and

uses 1/4 wave Sinclabs Model SRL-201 antenna– Single 192 byte ORBCOMM message is generated every hour, and three of

these messages are sent every third hour

• Argos telemetry is the back-up– Argos PTT is a METOCEAN Model MAT 906 and uses a 1/4 wave

METOCEAN whip antenna– If 11 hours of ORBCOMM messages are accumulated without transmission,

the Argos PTT begins to transmit Argos messages (6 Argos messages equals one ORBCOMM message)

– Argos suspends transmission when ORBCOMM message accumulation is less than five hours

October 25, 2001 DBCP XVII Page 11

J-CAD Testing

• Functional system testing at the factory– All major subassemblies tested prior to system integration– All sensors and telemetry systems are tested– Limited failure mode testing

• Bedford Basin, Nova Scotia– Complete system testing of one J-CAD, including oceanographic sensors– Practice system deployment

• Seward, Alaska– Complete system testing (all three J-CADs) in a colder climate & higher latitude

• Comparisons made to pier-mounted weather station• Barometric pressure data offsets due to tidal variation and height of pier

– Practice system deployment

• Deployment Site– Final verification that unit is working properly after installation

• Freewave radio telemetry interface allowed this testing in “comfort” of a tent

October 25, 2001 DBCP XVII Page 12

Barometric Pressure Differential

0.80.9

11.11.21.31.41.5

1007

1015

1022

1029

1036

1043

1049

1056

1064

1070

1108

1115

1122

GPSTime

Pre

ssur

e D

iffer

ence

(m

B)

Difference

October 25, 2001 DBCP XVII Page 13

October 25, 2001 DBCP XVII Page 14

October 25, 2001 DBCP XVII Page 15

• Three J-CAD systems have been deployed in the Arctic Ocean

• Long-range plans anticipate two deployments per year--one at the

North Pole and the second in the Beaufort Sea

Deployments to Date

October 25, 2001 DBCP XVII Page 16

• J-CAD is the first system to measure oceanographic sensors using an inductive modem system below the sea-ice

• J-CAD was the first system to use ORBCOMM telemetry from the North Pole

• J-CAD is a very cost-effective system for polar observations

Conclusions