I was laying in bed last night contemplating customers, carrots and other things I’m suppose to consider, during the spring on a Farm-childcare, when sea-ice came drifting through my consciousness. It’s usually a sign sleep is creeping up, and worldly worries are melting away. Last night it led to some delightful, dazing dreaminess I doubt I can fully replicate, but which show the complexity of even a thing as simple as water.
Yesterday I was briefly discussing how a tendril of the Gulf Stream, coming north, for a time rides at the top of the ocean, but then takes a dive under the colder waters. For a time it is less dense than surrounding waters, but then it becomes more dense.
This occurs because there are two variables involved. First, there is temperature, and second, there is salinity. The Gulf Stream is more salty than surrounding waters, because it was subjected to a lot of evaporation down in the hot tropics before it came north. Salty water wants to sink. However the Gulf Stream is much warmer than surrounding waters. Warmer waters want to rise.
An analogy is needed. Imagine the water coming north is a bunch of hot air balloons. As long as the air in the balloons is hot, the balloons remain high, but gradually they cool, until they reach a momentous occasion where they take a dive.
It is a simple enough thing to model this on your multi-million dollar computer. First you need to loot the wallets of drained tax-payers, and then you convince the government to print up some extra money. Easy as pie, when you are falling asleep and in a dream world, but I find it easier to command the non-virtual reality in dreamland, and to model the two variables outside computers in the fresh air.
Instantly Fram Strait is experiencing complete calm. What’s more it has been doing so for weeks. The Gulf Stream, coming north, does so in a glassy stillness, and the point where it dives beneath colder water can be seen by the way sea-gull feathers drifting north in the current come to a halt. The waters to the north are still, even stagnant.
IE: In dreamland we have simplified things to a degree where slowly moving water is sliding beneath still water. If course we can’t have water coming in without water going out, but let’s have that happen someplace else, so it won’t mess up our dreamland model. Also, of course, you can’t have a fluid in motion moving past a still fluid without this annoying thing called “turbulence” making little whirls along the boundary, like little storms along a front. Fortunately our dreamland model has a “mute” key that dampens that stuff away. In the end we have a nice simple scenario.
Now, as we slip deeper into dreamland and our brains gain super-powers, let’s have a little fun by adding another variable or two. Let’s reduce the amount of warming due to sunlight, as winter comes and the sun sinks low. Or let’s chill the air. This cools the Gulf Stream tendril coming north more quickly, so it reaches the magical point where salinity trumps heat five miles further south.
Oh oh. Problem. If the water sinks earlier, the completely static water which it is sinking under has to move, doesn’t it? Doesn’t it have to move south to fill in the space above the sinking water?
Or suppose we change the salinity of the Gulf Stream heading north. How? How about a tropical storm dumping a foot of warm rain. Now the tendril wants to come further north before sinking. Would not it plow into the static surface water, and make it move?
But how about both chilling the water and reducing the salinity? How are we going to manage that?
What’s that you say? Why don’t we redirect all the sea-ice heading south along the east coast of Greenland, in that cold current, and push it across Fram Strait into the warm current heading north? That will both cool the northbound tendril of the Gulf Stream, and make it less salty, you say?
Funny you should say that, for that is exactly the scenario we were looking at yesterday, as vast amounts of ice were melted just west of Svalbard.
Ordinarily it is at this point I get a headache, but when I am falling asleep the implications have a nice way of knocking me over the brink into unconsciousness. Sort of like an uppercut to the jaw. As I pass out, I am usually pondering one of three things.
First, if you cool the water heading north, and lower its salinity, how will this effect the melt from beneath to the north? In Theory, if you dumped enough ice into the northbound water, you could so cool and so dilute the current that it wouldn’t be all that different from the water to the north, and could skip the bother of sinking beneath it. What effect would that have on surface currents, and submarine currents?
Second, how many more buoys will the taxpayers allow before they come with burning torches? We don’t need a mere string of buoys across Fram Strait. We need north-south strings. We need surface reports and reports at depth, so we can have a 3-D picture of the daily fluctuations of temperature, salinity, and the speed the water is moving, like the weather-maps we get for the air above.
Lastly, what does it mean if ice does not travel in the cold, southbound current to the southerly tip of Greenland? Through much of the winter the ice levels were low, because ice was held back at the Pole, and much of the ice off the east coast of Greenland was “home grown”. Now even more ice is being deprived of it’s right to take the normal route because it has headed across to the wrong lane of the two-lane highway in Fram Strait. Will less ice off the south tip of Greenland make that water warmer? (Currently there is a fringe of warmer-than-normal water right along the Greenland coast, but then waters are colder-than-normal clear across to Spain.)
Usually thinking about all this is quite enough to cure insomnia. If necessary, you can add another variable: Wind. A strong wind can move surface water. What effect does a cold north wind have on a current coming from the south? Do you have a current heading south at the surface even as it heads north deeper down? Oh oh. Time to hit that “mute” key again, as I see turbulence rearing its head.
In the end I think very few things travel in the nice neat lines shown by textbooks. I am old enough to remember the way the Gulf Stream was portrayed in textbooks before we could see the surface with heat-sensitive satellites. It was nothing like this:
I have a vivid memory, from back in those pre-satellite days, of attending a class held to make the general public more aware of beach erosion and why we should alter our attitudes about where we built marinas and beach houses. It was taught by a knowledgeable young scientist, and in the audience was a garrulous old fisherman. For some reason the subject got off the topic of beaches and moved out into the Gulf Stream, and at that point the fisherman began to talk about “warm whirlpools” and “cold whirlpools” and how he’d use them to hunt the best places to fish, and the young scientist rolled his eyes, as if the old man was talking nonsense, and finally the young man cut the fisherman off, making it obvious he felt the man was inventing tall tales. Later I always wondered what the scientist thought, when he saw the first satellite images come in, showing exactly what the old fisherman had described.
Perhaps it is for this reason that I, meaning no disrespect to scientists, am less than certain the map below is fully accurate.
The thing I am watching for are the changes fishermen described the last time the AMO shifted from “warm” to “cold”. They were dramatic.
In any case, I highly recommend thinking about this stuff next time you have trouble sleeping.
In more mundane matters, The DMI maps continue to show the high pressure over towards Bering Strait, and the low nudging toward the Pole, but weakening.
I’m worried they may have had troubles with the airstrip at Barneo, as there have been no reports since the 18th. You can see the ice is “active” across the Pole in the NRL “Speed and Drift” map from yesterday.
This map also shows ice is likely moving away from the northwest coast of Hudson Bay.
In terms of the Northwest Passage, the western approach looks like it is opening up nicely, with ice moving away from the coast of Alaska. However the ice in Baffin Bay seems to be being crammed north into the eastern approaches.
Lastly, it looks like ice continues to be exported to the “wrong side” of Fram Strait.
The thickness map shows an odd little mountain range of thicker ice crossing right over the pole. (Not really a mountain range, but worth noting: 9 feet thick rather than six feet thick.)
Lastly the “Race Against Time” expedition has been reporting struggling over a lot of pressure ridges as they approach the Pole from the Russian side. Mark Wood mentioned the ice was much flatter when he skied the route two years ago. At last report they had crossed 89 degrees north. Unfortunately they only report by satellite phone, without pictures.