Expedition August 7 to August 17, 2007 by Humfrey Melling Previous | Next First Report on Progress The ten members of the IPY CAT study travelled to St John's on Tuesday August 7 and assembled to join the CCG crew-change flight early the following morning. The scheduled 7am departure was delayed by more than three hours while we awaited the lost baggage of the five team members who had arrived on the late flight from Victoria last evening. The charter flight to Thule Greenland via Iqaluit was uneventful. At 19:30 EDT on August 8 (Wednesday) CCGS Henry Larsen cast off from Thule and set course north. Thick fog impeded progress to Smith Sound. Our first objective on August 9 (Thursday) was the retrieval of scientific equipment cached at Alexandra Fjord on the Ellesmere side, equipment required for ice-properties research by the group from NRC. Because fog rendered the plan to collect the cache via helicopter impractical, the ship continued on to Alex, dropping anchor at 22:30 in clearing fog. Time on route was spent finding, unpacking and organizing equipment and setting up and testing the CTD (model SBE25) and the automatic camera (for ice thickness monitoring) systems. The former was not immediately functional and required appreciable effort in diagnosis and repair during the day. Friday (August 10) dawned bright and clear. Cached equipment was quickly retrieved from shore, and a sensitive pressure recorder was placed on a shallow mooring sheltered between two small islands in the fjord. CCGS Henry Larsen was heading eastward to Smith Sound by noon. On route, the NRC team was deployed via helicopter to survey a multi-year ice floe via drilling and EMI radar. Subsequently, automatic weather stations installed by the University of Manitoba in September 1996 at Pim Island and Cape Isabella were visited by helicopter for retrieval of data and assessment of needs for repair; both installations were operating, but both had shut down between mid December to mid April with low battery voltage; contrary to expectation, wind speed was not startlingly high at any time when the systems were operating. In the evening, we initiated a hydrographic section eastward across Smith Sound at Cape Sabine. The SBE25 CTD continued to have problems and failed completely on the third station. CCGS Henry Larsen drifted in the vicinity overnight. The following morning (August 11, Saturday), a problem with the ship's cyclo-converter delayed our start by about two hours. CTD profiling was resumed after 10:00 using the back-up SBE19 CTD. This recorded a fine down-cast but failed during the first back-haul. With both CTD probes out of service, CCGS Henry Larsen continued southeast to Foulke Fjord where a sensitive pressure recorder had been deployed last September. While CCGS Henry Larsen stood by, two personnel continued into the fjord via the fast-response craft (FRC). Unfortunately, they were unable to communicate with the acoustic transponder on the mooring and returned empty-handed after three hours of effort. We picked up the Smith Sound hydrographic section at its eastern end at about 21:00 and worked until midnight, when the pressure sensor on the recently repaired SBE25 CTD failed. CCGS Henry Larsen drifted in the vicinity overnight. We continued the hydrographic section using the SBE19 CTD in the morning (August 12, Sunday), finishing in mid-afternoon. When the NRC group had completed a survey of their second multi-year ice floe, the ship set course northward through Kane Basin to the 230-m sill that limits through-flow from the Arctic to the Atlantic. A hydrographic section along the sill (2.5 km spacing) was completed overnight using the now-operational SBE25 CTD. We were excited to observe 34.5-salinity water on the sill at 160 m depth; this water normally rests at 250 m or deeper in the Arctic Ocean and is capable of renewing the deep water of Baffin Bay once past this sill. Monday August 13 was spent in Scoresby Bay, in an attempt to recover a pressure recorder positioned here four years earlier. At the same time, the NRC group surveyed a third multi-year ice floe just outside the bay to the south. Here again we had no success communicating with the acoustic transponder. Following our similar experience at Foulke Fjord, we now have heightened suspicion that the new ATM-891 deck box leased for this expedition from Teledyne Benthos has a serious bug. Regrettably, our primary Benthos deck box did not make it on board. It was apparently moved by mistake from the Larsen staging area at IOS in June to that for the Louis and is now marooned far out in the Canada Basin. The Kane Basin CTD section was continued northward to the southern entrance of Kennedy Channel overnight. On Tuesday morning (August 14) CCGS Henry Larsen was positioned at the principal line of moored instruments for the CAT study. Following ice reconnaissance via helicopter in the morning, we were ready to move up to the line to start work. At this moment, the ship received news that a sailor's wife was seriously ill; the decision to disembark the affected sailor at Grise Fjord was quickly made and CCGS Henry Larsen changed course for this small community on Jones Sound, 400 nautical miles to the south, at about 13:00. CCGS Henry Larsen was in transit to Grise Fjord for the remainder of Tuesday and Wednesday (August 14-15) and arrived off Grise Fjord in the early hours of Thursday. In the evening, we were able to take advantage of calm conditions in Jones Sound to run some in situ tests on the acoustic transponding system. We now understand that the Benthos ATM-891 has a bug that prevents its operation at short (less than 250 m) range; such a restriction could explain our inability to talk to transponders in Foulke Fjord and Scoresby Bay. We are reasonably confident that the ATM-891 will be effective at longer range; we simply need to stand off the locations of moorings when attempting to release them. The sailor was taken ashore by helicopter first thing on Thursday morning (August 16). CCGS Henry Larsen was underway for the north by 11:00, following an ice reconnaissance flight by helicopter. Today, Friday August 17, is our ninth day on board ship. We passed through Smith Sound at noon and expect to reach our work area at the southern end of Kennedy Channel by tomorrow morning. By that time, the diversion to Grise Fjord will have taken about four days. So far the weather has been excellent, a consequence of persistent high atmospheric pressure over Greenland. With the exception of fog today and on our first day out, the visibility has been excellent and the scenery at its very best. Ice conditions have been quite severe, dominated by multi-year ice with most floes very thick and an abundance of giant floes (up to 10-km across). The NRC drill-hole data suggest that average floe thickness in excess of 10 m is not uncommon. The pack is moving towards Baffin Bay at 1-2 knots, so conditions change rapidly. The high surface relief of these floes blocks the visibility of leads beyond about a mile; ice reconnaissance via helicopter has frequently been required.