SIMB3 Technical Specifications

Quick Summary

Seasonal Ice Mass Balance Buoy 3 (SIMB3) is a 4.87 meter long, 12 cm diameter spar-type buoy that measures how sea, lake, or pond ice change thickness through time. Once deployed, SIMB3 uses two ice-facing acoustic rangefinders to measure how the surrounding ice grows and melts. It also measures the vertical profile of temperature through the air, snow, ice, and water, as well as air temperature, barometric pressure, and GPS location. SIMB3 can measure ice up to 3 meters thick and snow up to 0.5 meters thick. It is equipped with a sealed battery and can operate autonomously for up to 1.5 years. Using an Iridium satellite modem, SIMB3 is capable of operating in anywhere in the world, transmitting data on user defined intervals (usually 1 or 4 hours). Immediately after transmission, data is uploaded to the Real-Time Data Portal for viewing and download.


Fully Assembled
Length: 4.87 m (16 ft) Diameter: 12 cm (4.5 in) Weight: 75 kg (34 lbs)
Crated with box top (as shipped)
Length: 2.43 m (96 in) Width: 33 cm (13 in) Height: 30 cm (12 in) Weight: 57 kg (125 lbs)
Crated without box top
Length: 2.43 m (96 in) Width: 33 cm (13 in) Height: 20 cm (8 in) Weight: 39 kg (85 lbs)
Distance between sounders: 4.051 m Distance above freeboard: ~ 1.2 m

Measurements Captured


Ice/snow surface position
From a fixed position 1.2 meters above the ice surface.


Ice bottom position
From a fixed position below the ice.


Temperature profile
At 2 cm intervals through the air, snow, ice, and into the water. 192 values in total.


Air temperature
At 1.2 m above the surface.


Barometric pressure
At 1.2 m above the surface.


Ocean temperature
From a fixed position below the ice.


GPS position
From a fixed position 1.2 meters above the ice surface


Contact us to inquire about non-standard sensor options.
Note: other diagnostic data such as battery voltage, transmission counter, and Iridium/GPS satellite count are also transmitted. For more details, see Getting Started with the SIMB3 datasheet.

Standard Sensor Suite

Instrument Description Accuracy Precision
Maxbotix MB7374 Downward looking rangefinder +/- 0.001 m 0.01 m
Airmar EchoRange + Upward looking rangefinder +/- 0.01 m 0.01 m
Bruncin DTC (3.85 m) Digital temperature chain +/- 0.5 deg C 0.125 deg C
DS18B20 Air temperature sensor +/- 0.5 deg C 0.0625 deg C
BME280 Barometric pressure sensor +/- 1 mBar 0.1 mBar
MTK3339 GPS GPS module 3 m ~ 0.1 m

Operational Considerations

Measurement range
Ice: 0 to 3 m* Snow: 0 to 0.5 m Temperature range: -60 to 60 C
Battery life: up to 1.5 years** Service domain: worldwide***
Tools required for assembly: none**** Time required: < 30 min Min Ice hole diameter: 25.4 cm (10 in)

* SIMB3 is buoyant, fully waterproof, and does not rely on the ice for mechanical support. Operation or deployment in open water is therefore possible, however results may vary.

** battery service life can vary significantly depending on the environment and equipped instruments.

*** transmission over the Iridium network requires a clear view of the sky.

**** while SIMB3 can be assembled without tools, an ice-auger is still required to drill the ice hole, a drill/screwdriver is required to remove the box top, and and a tape measure is recommended for recording initial ice and snow thickness and freeboard measurements.

Data Specifications

Message protocol: Iridium SBD Standard Message size: 275 bytes Max message size: 340 bytes Transmission interval: user defined
Data Availability
Time from transmission: ~ 5 min Data format: CSV, JSON Access: via Real-Time Data Portal or our API

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