Of all the seas bordering the Arctic Ocean, the Laptev Sea is the most extreme, when it comes to the yearly ecological whiplash the arctic subjects its species and geology to. The water goes from nearly fresh to salty and the water temperatures swing from freezing to 60° F (16° C) near the shore. The tundra bordering it goes from sunbaked heat in the summer to one of the coldest places in the northern hemisphere in the winter.
Arctic rivers vary greatly in their flow, at a trickle in the frozen depths of winter and in a roaring flood during the height of the summer melt, and the Lena River is the tenth largest river in the world, though perhaps it is difficult to measure a river’s size when it freezes to the bottom in places, in February. The river rises sixty feet during its flood stage. Maximum discharge has exceeded 4.2 million cubic feet (120,000 cubic metres) per second, and the minimum has fallen to 39,300 cubic feet (1,100 cubic metres). In other words, a hundred times as much fresh water pours into the Laptev Sea in August as does in January.
The huge surge of fresh water into the Laptev Sea is one reason its shorelines freeze so swiftly. The ice has spread over much of the sea in only a week. (October 4 left, October 9 right.)
During calmer years the fresh water is able to stratify more, and a definite “lens”of fresh water forms at the surface, but on stormy years the mixing of the fresh water with the salty occurs more quickly. The sea is over the continental shelf and relatively shallow, so there is little exchange with the deeps, as occurs over much of the Antarctic coast. Winds tend to shift from summer sea-breezes, when the land is hotter and air rises over land, to winter land-breezes, when the sea is warmer and cold air sinks over Siberia. A dramatic change occurs during September, when days shrink shorter than nights, and the landscape shifts from sun-baked to snow-covered.
On his blog at Weatherbell, Joseph D’Aleo mentions the Siberian snows have been early this year.
As soon as there is even a dusting of snow the tundra loses its ability to absorb heat from the shrinking daylight, and increases its ability to lose heat to the skies of the increasing nights. Although we are suppose to speak in terms of “heat-loss”, Siberia becomes a “cold-producer”. The chilled air sinks, and builds high pressure as it presses down, and the Siberian high pressure (which I like to call “Igor”) can be the coldest and strongest in the northern hemisphere, with temperatures in the depth of winter down to -90° F.
The effect on the Laptev Sea is a quick freeze, as the winds start to flow off the land. It is all the quicker because the water is made brackish by the Lena River’s floods. However as the Lena River’s waters freeze, the flow swiftly shrinks. Also the winds start to pick up off the land, as the difference in temperature between the sea and the tundra increases. For a brief time there is a maritime airmass rubbing cheeks with an arctic high, and often this breeds storms that roll along the Siberian coast (with these storms having an oddity: Warmer winds from the north than from the south.) (Not so odd in Australia, I suppose.) These storms churn the water and can break up the ice, yet the freeze can be delayed but not denied. Eventually the Laptev is ice-covered.
However even when ice-covered, though less heat is lost, heat continues to radiate up through the ice. It may seem odd to call it “heat” when it is below freezing, but it is far “hotter” than the air pouring off Siberia. The air over the land is often below -50°F while the air over the sea-ice is “warmed” and seldom below -30°F. This difference can create “land-breezes” that in fact are roaring gales, and the gales are so strong they push the Laptiv Sea ice away from shore, creating a polynya of open water even in the depth of winter. This creates a difference in air temperature at the surface of +28°F over the water and -50°F over the land, which can only increase the gales, and the result is that large amounts of Laptev sea-ice are exported towards the North Pole. Most winters see the Laptev Sea as the largest creator and exporter of sea-ice, though the amounts vary a lot from year to year, depending on weather patterns.
Each time the polynya forms and the exposed water must be refrozen, an interesting process occurs wherein salt is exuded from the forming ice. Unlike Antarctica, where the super-cooled brine vanishes down to great depths, Laptev brine sinks in shallow water. In the delta of the Lena River the water becomes much saltier, as the summer flood turns to a winter trickle, and the “lens” of fresher water atop the Laptev Sea is constantly frozen and exported.
Just imagine a scientist trying to get his mind around all the variables we have discussed already. For a true scientist the challenge is a sheer joy, though for a person who wants a simple answer the Laptev Sea is a nightmare. Even if you could comprehend one year’s changes in temperature and salinity, the following year is likely to be completely different. One year the Lena basin may experience cold and drought as the following year sees mildness and rains, greatly altering the flow of fresh water into the Laptev Sea, and therefore altering the point at which water freezes, and changing all sorts of exchanges between water and air, all sorts of up-welling and down-welling influencing currents, and influencing evaporation rates and the formation of storms.
Just, (for the joy of it), consider this variable: In the case of fresh water, water at 32.1° F floats on top of water at 35°F, but in the case of salt water, water at 32.1°F sinks below water at 35°F. For your homework assignment, figure out the flow of fresh water from the Lena River, chilling as it flows into the Laptev Sea, and also becoming more saline, and determine the point at which it stops being more buoyant than the water it is entering, and starts to sink.
I think the true joy of a true scientist is not so much in figuring everything out, as it is in seeing how wonderful everything is. We might find some answers, but we will never comprehend the entirety of the sheer majesty and magnitude of what our Creator has achieved.