Introduction
-- Chronology --
The CCGS Louis S. St-Laurent and the USCGC Polar Sea departed Victo-
ria, British Columbia, together on the evening of the 17th of July 1994. The
majority of the scientific party of 70 persons boarded by helicopter in Nome,
Alaska, on July 24th; several scientists had sailed with the ships from Victoria
to set up equipment and make preliminary measurements. We sailed through
the Bering Strait on July 25th and entered the ice in the northern Chukchi Sea
early in the afternoon of the following day.
During the first few days, the ships worked some distance apart, as the ice
was not severe. However, from the 30th of July onward, ice coverage was typ-
ically complete, and the ships moved close together, operating in tandem for
the most efficient icebreaking, taking turns leading. This greatly reduced the
fuel consumption for the trailing icebreaker. The ships icebreaking in tandem
averaged 35 knots during the northbound transit. Visibility was generally
poor throughout the time spent in the ice, with fog and overcast the rule. July
31st was the only full clear day. Passive microwave satellite imagery (SSM/I)
received in real time aboard the Polar Sea provided excellent strategic informa-
tion on ice conditions for planning the northbound route and stations.
Beginning in the central Chukchi Sea, the station line ran northward east
of the RussiaU.S. Convention line, but once past 200 nautical miles from
Wrangell Island, our track turned northwestward across the Chukchi Abyssal
Plain and onto the Arlis Plateau, which we reached on the 3rd of August at
78N. Heavy multi-year ice limited our eastward penetration down the flank
of the plateau to longitude 17418′W. We therefore resumed the station line
northward, with the intent of covering the region to the east along 78N on
the return voyage. Near 80N we again attempted a section to the northeast,
but difficult ice conditions limited our penetration in that direction to 8013′N,
17246′W. We therefore continued working northwestward across the Men-
deleyev Ridge and into the Makarov Basin.
On Monday the 8th of August we had an overflight and data transfer by a
Canadian ice reconnaissance flight carrying side-looking radar, which mapped
the ice in a swath 200 km wide and extending 1100 km along our intended
track northward. From this imagery it was clear that difficult ice conditions
lay to the east. Detailed helicopter ice reconnaissance the next few days con-
firmed this, and on Sunday the 14th, near 85N, 170E, we decided to con-
tinue onto the Lomonosov Ridge near 150E before turning east and running
the final northward leg of the outbound voyage along 150155W.
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