January 7-10: Mertz Glacier

Post from VIMS graduate student Mar Arroyo.

7 – 10 Jan 2017
66° 45’ S, 145° 51’ E
Mertz Glacier

After a few long days of CTDs in the Dalton Polynya, the thick ice surrounding the Totten Glacier was much too difficult to crush through. After abandoning efforts to reach the Totten, we’ve sailed north and east for about a day to the Mertz Glacier and polynya. The skies were blue and the weather was calm. The Mertz looked like a wall, extending across the entire horizon. We were able to sail within 1 nautical mile of the glacier!

View of the western side of the Mertz Glacier tongue.
View of the western side of the Mertz Glacier tongue.

The Mertz Polynya region is an important area in East Antarctica because it is a site of deep Antarctica Bottom Water formation, supplying the deep Indian and Pacific oceans with atmospheric gasses, like oxygen. In February 2010, a massive iceberg named B9B had crashed into the protruding tongue of the Mertz Glacier, which changed the distribution of ice in the region.

ASAR image of B9B crashing into the Mertz Glacier tongue on February 13th, 2010. The broken Mertz Glacier Tongue (MGT) was carried west by ocean currents into the Weddell Sea region, where most of the tongue has melted away.

Calving events like this one act as “natural experiments” to show what sort of modifications can occur in the polynya waters during changes in the landscape. On this voyage, we completed 15 CTD stations in narrow bands of clear water along the western and northern end of the Mertz. We actually sampled super-cooled deep water from the western end of the Mertz, at temperatures below -2.0 °C! Theoretically, this water should be frozen, as seawater will freeze at around -1.8°C, depending on the salinity and the pressure. Super cool.

A lot of fun, hard work!