By Rachel Teasdale
Weather: Occasional light showers with overcast skies, but the winds have come up to 20-25 knots, and are forecast to get higher tomorrow.
What’s happening today? This morning ROV Jason was recovered early because the winds and seas were building. In the afternoon AUV Sentry was recovered and tonight we will start a 6-hour CTD Tow-Yo.
|Axial Seamount 2015 Expedition video about the suite of instruments and diversity of science associated with the CTD instrument package. Video by Jesse Crowell in association with Saskia Madlener at 77th Parallel Productions. Music by James Andrew Menking|
|CTD during launch on 14 August 2015 to measure background conditions from which water from hydrothermal plumes will be compared.|
The CTD rosette is lowered from the ship’s deck usually to just above the seafloor and then raised back up again. The CTD sensors measure continuously as the CTD ascends or descends, providing real-time information about the properties of the ocean. On this cruise, Nathan Buck is using the CTD data to identify regions of hydrothermal plumes (often rich in chemicals and microbial life) that are emitted from vents on the ocean floor. When the sensors indicate the CTD is in a hydrothermal plume, then individual water samples can be collected at various depths in the rosette of bottles on the CTD.
|Cartoon of tow-yo pattern for CTD measurements, from www.venturedeepocean.org/tools/tow_yo.php|
Tonight’s tow-yo will search for hydrothermal plumes associated with 2015 lava flows of Axial’s North Rift Zone. The CTD will collect samples across a zone 8 km (5 mi) long and 200 m (640 ft.) tall, from 1800 to 1600 m (5760- 5120 ft.) depth. In this way, the CTD will define the location and intensity of the plume and will provide information about its chemical composition and what microbes may be present in it. This will tell us what is coming out of the hydrothermal vents on the new lava flows and what impact they are having on the overlying ocean.
|CTD Rosette prior to launch 18 August 2015. Note vertical Niskin bottles that will collect water samples during the CTD tow-yo.|
More information about CTDs is available at: