2. Overview
2-dimensional sea ice extent
measurements don’t give us a full
understanding of sea ice. Sea ice ranges in
thickness from just a few millimeters to
more than 15 feet thick. Knowing sea ice
thickness helps scientists identify regions
most vulnerable to melting during warm
summer months.

3. Overview (cont.)
With sea ice floating out in the vast ocean
in the coldest parts of the world, measuring
sea ice thickness can be extremely difficult.
Let’s find out about some of the tools and
techniques scientists use to determine sea
ice thickness.

4. From the Surface
 Drilling holes: Simple and
straightforward. Just drill & measure.
 Sled radar: Scientists sometimes pull
sleds equipped with ground-penetrating
radar sensors, across the ice.
 Submarines: Upward-looking sonar lets
scientists measure thickness from below.
Sea ice drilling. Image source: NSIDC/Martin
Hartley
Upward-looking sonar. Image source:
Science Direct
Although not practical on large
scales, field measurements can give
provide details about how ice
moves, melts, or grows in a particular
area.

5. From the Air
Aircraft and satellites allow scientists to cover a lot more ground.
However, data records don’t go back very far and measurement accuracy
is more difficult than with ground observations.
Example: CryoSat-2
The European Space Agency’s
CryoSat-2 uses a radar altimeter to
measure the thickness of floating sea
ice & detect annual variations.
CryoSat-2 determines thickness by
measuring the freeboard of ice
floes, the height by which the ice
extends above the water surface.
Cryo-Sat 2 freeboard measurement.
Image source: ESA/AOES MediaLab

6. Learn More
 Climate Central Blog: Drilling Holes…
http://www.climatecentral.org/blogs/extreme-science-
drilling-holes-in-arctic-sea-ice/
 CryoSat:
http://www.esa.int/Our_Activities/Observing_the_Eart
h/CryoSat
 ICESat: http://icesat.gsfc.nasa.gov/
Want to learn more about how sea ice thickness
is measured? Here are a few good resources to
get you started.