I went to bed last night past midnight, so I knew I would have hard time waking up at sunrise. I asked to be woken up for the mooring recovery, so when I woke up at 10:30 am I knew something had not worked around our plan.
I came down to the lab to find what had happened. Winds over 40 knots made the recovery impossible early morning. It is not safe to be on the deck working with extremely heavy equipment and winches with such strong winds. It does not help either to have -22 F (-30 C) windchill. We might even need to deploy a speed boat to get the first float, and trust me, with the seas like they are right now, no one would want to be on the speed boat
A view from the labs porthole. The strong winds (up to 50 knots) and big waves prevented us from recovering the moorings today.
We cannot do any science under this weather, so we decided to go to the location of the second mooring and make sure we have the exact spot by dancing along an ever shrinking triangle around the transponder. Once the winds and seas subside we will retrieve the moorings. When will that be? I really do not know. Last time we lost two days for a storm like this one.
The heavy seas are interfering with the communication with the transponder of the second mooring, so we have decided to postpone the triangulation and 'sail for comfort' around the seas. We might be heading back towards the ice for shelter.
But not all is lost for the journal. This rough weather is bringing us the opportunity to observe pieces of ice aligned in very long lines. This phenomena is called 'Langmuir circulation', in honor of Langmuir who first described it in 1938. Even though it has been more than 70 years since these phenomena attracted scientists attention, it is still a topic that is being researched.
Ice floats aligned with the wind form a very long line that are part of the Langmuir circulation.
Three things are needed in order to observe this circulation: winds, some material floating on the surface (floatsum), and waves. We have the pieces of ice as floatsum, the wind waves and the wind!
The mechanism for forming the Langmuir cells is very complicated to explain. Thorpe ( Annu. Rev. Fluid Mech. 2004. 36:55-79) on a review paper on Langmuir Circulation wrote: 'Studying the associated dynamical processes [of Langmuir circulation] involves some of the most intellectual demanding problems of theoretical and observational fluid dynamics, several of which remain intractable'. I will just describe what is observed in the surface waters. The wind sets a circulation that is formed by alternating cells that move in vertical ellipses.
Diagram of the Langmuir circulation. Note that the circulation of adjacent cells is opposite, which generates convergence zones where flotasum accumulates, and divergent zones between the ice lines.
Adjacent cells spin in opposite directions creating a zone in which the floating materials are brought together (convergence) and zones in which they move apart (divergence). The bands can be separated by distances ranging between 2 m and 1 km. cells are typically between 7-10 meters deep and 1 m y 500 m in the horizontal.
Two lines of ice formed by Langmuir circulation. The distance between both lines is twice that of a Langmuir cell.
The lines formed at the convergence zones, seen here by the presence of the ice floats, are called 'windrows' and can be kilometers long. They are usually not linear, like the one on the right side of the following picture, but often twisted and merged one with the another, like the one on the left side of the same picture.
The line of ice produced by the Langmuir circulation can be kilometers long.
The vertical motion of the Langmuir circulation helps mix the water near the surface. It is regarded as one of several processes that contribute to the dispersion of floating material, like oil. It is also an important process that affects the ecology in the surface layer by enhancing mixing, transporting organisms between different depths near the surface, generating patches of swimming or floating algae, or affecting their exposure to pollution.
We hope to have better weather tomorrow so we can retrieve the moorings.