| During the HOTRAX cruise, we
installed three autonomous ice mass balance buoys (IMB). These buoys
measure position, barometric pressure, air, ice, and ocean temperature,
snow accumulation and melt, ice growth, and ice surface and bottom
ablation. The thermodynamic mass balance of sea ice is a simple but
powerful concept. It is the balance of how much the ice grows in the
winter and melts in the summer. The mass balance is the great
integrator of the heat budget. If there is a net increase of heat, then
the ice will thin. A net cooling will result in thicker ice.
IMBs have routinely been installed as part of
Monitoring the drift, thickness, and mass balance of Arctic sea ice,
the International Arctic Buoy Program, the North Pole Environmental
Observatory, and the Beaufort Gyre Project. On HOTRAX the buoys were
installed as listed below.
|
Buoy |
Date |
Latitude |
Longitude |
Initial thickness |
|
2005D |
22 August |
80 56.334 N |
175 39.033 W |
1.40 m |
|
2005E |
25 August |
83 08.923 N |
174 28.884 W |
1.78 m |
|
2005F |
2 September |
85 58.992 N |
162 13.885 W |
2.6 m |
|
Drift map of buoys through 16 October
2006. Buoy name is at start.
 |
| The components of an ice
mass balance buoy are: 1.
Buoy housing - the electronics
are housed in a sealed 20 cm diameter aluminum tube.
2. Thermistor string
- custom constructed by C.R.R.E.L., the thermistor string measures the
resistance of a specific electric current at points along its length,
which are later converted to temperature correlated to specific depth:1.4-m-longPVC rod with
YSI thermistors (accuracy of 0.1 C) spaced every 10 cm.
3. Above ice acoustic rangefinder -
a sonic
rangefinder made by
Campbell Scientific
(model SR-50) specifically for measuring snow depth. The sensor is mounted
on a pole, frozen into the ice, looking down at the snow surface. It
measures distance between the instrument and the snow surface, thus
recording the changes in the snow depth. When the snow melts in the summer,
the instrument then measures surface ice ablation.
4. Underice acoustic rangefinder - a
Benthos (Model PSA-916) underwater sonar altimer is mounted on a pole,
frozen into the ice, looking up at the underside of the ice sheet. It
measures distance between the instrument and the ice bottom, thus recording
ice bottom growth and ablation.
5. Barometer - sea level pressure is measured using a Vaisala barometer (model number PTB210A).
6. The Datalogger - a Campbell Scientific
CR10X
datalogger is the brains of the buoy system.
It collects information
from each instrument, processes and organizes the data, adds a time
stamp to the data, and sends it on to the ARGOS transmitter for transmission
to the satellite.
7. ARGOS transmitter – data
is send to the ARGOS satellite
system using a transmitter built for Campbell Scientific (SAT ARGOS).
8. Lithium battery pack. |
