CTDT Groundtruth Opportunities

Overall Coverage of the Mixing Zephyr Night and Alvin Programs

Notice that because the ALVIN submersible usually descends and ascends directly upon a dive target -- historically (during the MZ cruises?) a particular vent field (initially located via CTDT surveys) -- very few ALVIN tracks transgress the perimeters of the known vent fields. This means that few observations of what the sea floor is like between known fields were obtained via Mixing Zephyrs dive program.

Diffuse Flow Sites: Cirque and Dune

In retrospect, the sea floor observation of diffuse flow at a location specified on the basis of CTDT information is rather remarkable, and certainly unprecedented. Since the cost of locating and mapping potentially-extensive areas via submersible is discouraging, it is worth re-examining the Mixing Zephyr CTDT casts that traversed near where the diffuse flow was observed. In turn, the ALVIN dive 2931 observations of diffuse flow separated from known fields of hydrothermal activity represent one of the best opportunities in all of the MZ data to "groundtruth" the CTDT measurements. This map shows dive 2931 proceeding generally from south to north. The first dive target -- the location of suspected diffuse flow -- is indicated by a magenta dot, while the locations of the 2 observed areas of diffuse flow are indicated by magenta stars. One area has been named "Cirque" and the other "Dune."

Name	X	Y	Longitude		Latitude 		Depth	Water Samples
Cirque?	5878    9562	129.085912765213	47.9799124134209	2131	GT Yellow; M Yellow;
Dune?	5882    9738	129.085859274975	47.9814955743456	2127	GT Purple; M Red;