29 March 2004
Monday, 29 March 2004
With the tempest somewhat appeased, early this morning we returned to SF6 mapping. The patch was originally released as a hexagon approximately 7 km across, and as recently as Saturday apparently a single well-defined blob. The question now is whether it has been stretched, distorted and broken into filaments by the variable relative motion of the surface ocean currents, particularly in response to the recent storm. It could also have been forced down upon meeting a slightly less dense, warmer layer of surface water. This real prospect would effectively spell the end of following this patch and perhaps set the scene for moving on to a second release. The surface buoy tracking the patch was moving erratically, reflecting the great variability of the surface ocean that confronts us during this experiment.
By 1 pm today, we completed in-station CTD casts for continuous vertical profiles of water properties. Water samples at selected depths were also collected. This allows for post-cruise analysis of dissolved-gas, chemical and biological properties. CTD measurements were hampered by the ship drifting out of the patch during the course of the scheduled "Gas" and "Bio" casts, resulting in necessary repeats casts.
Thank goodness for the strains of Miles Davis' Summertime floating from the new speakers of CTD control computer. Thank goodness, too, for last night’s entertainment from our own shipboard musicians: Ed Abraham (Irish fiddle and banjo), Craig Stevens (guitar) and Skipper Roger Goodison (guitar). Thanks too, for the so-far reliable e-mail contact with home and our real lives. And thanks most of all for the safety and protection of our vessel RV Tangaroa and for all the good folks of the shipboard party, without which none of this would be possible. The difficult conditions and ambitious tasks of recent days have illustrated this last point only too well.
Evening now and we are still searching for the elusive patch. Much depends on decisions to be made in the next day or two. Much depends also on the whims of the weather. A second release or infusion looks increasingly a prospect.
The CTD Team
The CTD Team consists of one, Matt Walkington, with casual and much appreciated help from many others of the science party and crew. It’s aim is to use our Seabird 911plus/32 CTD/water sampler instrumentation to deliver high resolution, high accuracy profiles of water properties plus discrete water samples as required at the "in", "out" and "survey" stations.