Ice distribution and sea currents (1943)

This map was published in 1943 as part of the United States Armed Forces manual. M-101 Atlas of World Maps.

The map shows all ocean currents, with their intensity, direction and temperature, as well as the distribution of ice on the planet. It uses the following colours for this purpose:

• All warm ocean currents appear in red.
• All cold ocean currents are shown in green.
• The solid purple line shows the maximum extent of polar ice that may affect navigation.
• The dotted purple line shows the regions where icebergs can reach.
• In the northern hemisphere, below the maximum ice extent, areas that may be navigable by heavy vessels are shown in varying shades of purple, depending on the maximum number of months in which this is possible.

Sources

• Perry-Castañeda Library Map Collection – Thematic Maps