ANNUAL SEA ICE BREAKUP NEAR COULMAN ISLAND, ANTARCTICA WITH THE USE OF LANDSAT IMAGERY

Imagery from the Landsat Thematic Mapper and Operational Land Imager document the annual breakup of sea ice near Coulman Island off the coast of Antarctica in the Ross Sea at latitude 73.5 S and longitude 169.6 E. Landsat 8 provides imagery from late 2013 to present. With less frequent coverage, Landsat 7 provides satellite imagery from 1999 to 2011 and Landsats 4 and 5 extend the coverage with a few scenes back to 1988 and 1989.

Landsat 8, launched in February 2013 has more bands and higher spectral resolution compared to Landsat 7. The new band 1 in the blue portion of the spectrum allows a closer look at coastal waters and helps estimate the tolerance of aerosols in the atmosphere. Band 9 provides a better detection of cirrus cloud contamination. Landsat 8 returns 400 scenes per day, 150 more than Landsat 7, which increases the probability of capturing cloudless imagery and has led to significantly more scenes being collected over Antarctica.

Landsat cannot document changes in sea ice during the Antarctic winter; at this latitude the sun does not rise from early May until early August, Julian days 129 to 216. The fast ice near Coulman Island is frozen to the coast and shows very little change over the winter. Higher solar radiation and higher air temperatures in the summer intensify the break up when open water reaches the coast of the island.

The annual breakup occurs between November and December. The January imagery displays the most cloud cover, but also large sections of water that are free from ice, and the converging orbits allow coverage much more frequently than the nominal 16 day revisit time. Hopefully later imagery will show the refreezing of the fast ice before the sun drops too low for image acquisition. Compared to the common small scale view provided by other satellite sensors, Landsat 8 provides a much higher resolution view of the annual cycle.