Reflections of a Southern Ocean Storm

Consistent with forecasts from NOAA/NCEP in the US (``Passage Forecast``), winds and waves started to rise during the early evening of 27 March. Stormy weather was reasonably timed, but not necessarily for ideal reasons. Turns out that early morning of 27 March, one of the VMPs (vertical micro-structure profilers) hit the ocean bottom at around 3800m. Well, it remains stuck. This event is not uncommon, but it is quite unfortunate. We were hoping it could dislodge itself through the modest tidal motions down there. However, it remains stuck.

We spent much of the day of 28 March stationed near to the stuck VMP, hoping that it would rise. We also spent that time sitting out the storm. Southern Ocean storms happen on a weekly basis, or even more frequently. Indeed, we may have yet another storm coming through in a few days.

The view from Monkey Island as we were facing the wind.  The ship was relatively stationary, as we were at this time in a wait-and-see pattern to see if the VMP rose and to wait out the storm.  So the fact that the bow pitched so high as to cause bow spray says a lot about the strength of the wind and the swells. Standing atop Monkey Island exposed us to heavy winds, though there is a barrier that diverts the winds overhead. We could thus stand face to the wind without being blown over.  This sort of photo is classic for any oceanographer to show at the start of a seminar presentation. It really is an amazing experience to ride these waves on a research vessel such as the JC Ross. 

Incessant winds and waves

One amazing facet of this storm was the extent of the howling winds. We have witnessed winds upwards of 40-50 knots for nearly 24 hours now (still blowing steady at 40-50 knots as I write!), with the attendant waves and swell. OK, this is not hurricane winds. But for 24 hours and still going! Note that a knot is a unit of speed equal to one nautical mile (1.852 km) per hour, which is approximately 1.151 mile per hour. So a 50 knot wind is 92.6 kph or 57.5 mph.

24 hours at this speed is an amazing amount of energy transferred from the atmosphere to the ocean. It is no wonder that the Southern Ocean is home to the largest ocean swells on the planet, arising from the strong and sustained winds and the infinite fetch (distance over which winds can blow before hitting land). It is also home to the strongest current on the planet, the Antarctic Circumpolar Current (ACC). We are in fact somewhat south of the ACC now, sitting in the northern portion of the Weddell Sea. Nonetheless, the winds are here, the waves are here, and both are really really powerful. 

The wind-swept sea starting to organize into swell.  Note that foam that is ripped off the tops of cresting waves.

For those interested in wave information, I took the following reading from the ship's instrumentation: maximum wave height 9.3m; significant wave height 6.1m; winds sustained around 40 knots with gusts to 55 knots; position: 61,56 S; 31,40 W. Later in the afternoon, the winds and waves rose further. So my guess is the peak swell was around 11-12 metres and sustained winds 45-50 knots. Another interesting facet of this storm is the absence of heavy rains or snow.  In fact, most of the storm was just wind and diffuse clouds. There has not been much precipitation at all.

By late afternoon of 28 March, the wind swept sea had organized into quasi-regular swells, thus making the rocking and rolling motion of the ship quite impressive. Many of us were so fascinated by the waves and winds that we kept returning to the Monkey Island on top of the ship's navigation bridge to feel the energy, get wind blow frozen, return inside to get warm, then go out yet again.

Another shot from Monkey Island over-look.  Again, note the foam streaks aligned with the wind, and the white caps getting ripped off the crests of waves. At this point, the sky was a pale over-cast, with some moments of sun and blue sky.  But the winds kept howling and the wave swell kept growing.

I learned by trial and error that it is very difficult to capture the essence of a storm at sea using a camera, particularly when safely positioned high above the ship deck. One needs a lower vantage point to properly gauge the size of the waves and strength of the winds. To do so, however, meant moving to one of the lower decks. But that option was unsafe, since every so often a wave would over-top the lower deck railing. So the captain wisely made the lower decks off limits during the storm.

Making a turn to the northeast and surfing downwind

During the afternoon of 28 March, we concluded that it was time to move to the next CTD/VMP section, which was about three hours away to the northeast. Therefore, we reluctantly left the stuck VMP, with a diminishing hope that it will be recovered.

 Moving to the next CTD section meant turning the ship from facing westward into the wind (the wind was blowing from the west and towards the east, which is typical for Southern Ocean winds), to having the ship face nearly downwind towards the northeast. Everyone was warned to put away any loose objects, since there was a good chance objects would fall or fly about during the turn. Those of us on top of the Monkey Island were ready as well, and yes, we were excited!

This photo was taken near to the time when we started to make the turn towards the northeast, and thus downwind. It was an amazing sight to see how the ship rolled as it turned.  But with a heavy ballast in the keel, it remained quite stable.

As the ship turned, we did some wild rolls requiring everyone to hold on, really hold on. Moving across rolling waves upwards of 10 metres requires a deft hand at the steering wheel. During dinner, we asked the bridge officers about the maneuver. They jokingly said they turned the wheel and closed their eyes!

Upon stabilizing in the northeast direction, nearly downwind, the best views were now aft (the rear). What was previously an up down pitching motion facing the wind became a downwind surfing action. The surfing of the ship was astonishing. The wave swells were peaking around 9-10 metres at this point, causing the ship to ride the swell like an experienced surfer. Every few waves appeared to come right up to the lower deck rails, almost swamping the ship. But the ship speed was just right to avoid the wash. Doubtless those on the bridge have done this before.

Many of us on the Monkey Island were fascinated by the how the birds reacted to the storm. Generally, they swooped low to the wave tops, trying not to fly too high so to avoid the bulk of the wind. Rarely did any of the larger birds (albatross, petrels) flap their wings, given the wind that was more than sufficient to keep them aloft.

Besides the real possibility of suffering from motion sickness (I remain fine), a downside of non-stop wave action is the difficulty maintaining a sound sleep pattern. Sleep has come to me in fits and spurts during the past few days. When asking crew about sleep, they sound more upbeat, or merely less concerned.  Perhaps what they have learned to trust that the ship is going to be fine, even as it creaks and moans, and even as the wind keeps howling.  Or perhaps they have learned to let go to the fact that we are simply not in control.  

Yet another photo of the windy sea. Any number of us stood in awe of the wind and waves, staring into the never-ending distance full of white caps, soaring birds, and howling winds. One wonders why we stood there, but we did, fascinated, mesmerized, and deeply reverential to the rawness of these natural forces. It felt like we were certainly visitors. This could not be our home. But we were grateful for the privilege of sharing this place for a brief moment of time.