Sunday, November 15, 2020

Effects Of Heat Flow From Russian Rivers On Arctic Ice Formation

 These are a couple personal bookmarks that I will probably be coming back to.

The three great north-flowing Russian rivers move a lot of water, in the case of the Lena in flood a mind-bendingly huge amount, and thus, because a given volume of water will contain around 1000 times the heat energy as the same volume of air (specific heat capacity x density) the big rivers are moving a lot of joules of heat into the Arctic.

Here's what makes the Lena so amazing: the average annual discharge of 15,500 m3/s (550,000 cu ft/s) is big but not that big, the Mississippi averages 16,800 m3/s (593,000 cu ft/) neither getting close to the Amazon which averages 209,000 cubic metres per second (7,400,000 cu ft/s)

But during the spring flood the Lena can hit 241,000 m3/s (8,500,000 cu ft/s)!!!

And the Yensei is no slouch at flood: 112,000 m3/s (4,000,000 cu ft/s)

By comparison the big river on the Canadian side of the basin, the Mackenzie floods at 35,000 m3/s (1,200,000 cu ft/s)

So when you have 100°F air temps in a Siberian summer as we did this year, you end up heating the river water, slowing the ice formation on the Russian side of the basin (the Ob is the big river just starting to freeze over under the volume chart below):

That's far from the whole story of what's going on on the Russian side, the air temps themselves, although not carrying as much heat as the water make a difference as do the icebreakers reducing albedo by exposing water and so on and so on....

And so, on to my bookmarks. First up, from the journal Science:

Science Advances  06 Nov 2020

Increasing riverine heat influx triggers Arctic sea ice decline and oceanic and atmospheric warming


Arctic river discharge increased over the last several decades, conveying heat and freshwater into the Arctic Ocean and likely affecting regional sea ice and the ocean heat budget. However, until now, there have been only limited assessments of riverine heat impacts. Here, we adopted a synthesis of a pan-Arctic sea ice–ocean model and a land surface model to quantify impacts of river heat on the Arctic sea ice and ocean heat budget. We show that river heat contributed up to 10% of the regional sea ice reduction over the Arctic shelves from 1980 to 2015. Particularly notable, this effect occurs as earlier sea ice breakup in late spring and early summer. The increasing ice-free area in the shelf seas results in a warmer ocean in summer, enhancing ocean–atmosphere energy exchange and atmospheric warming. Our findings suggest that a positive river heat–sea ice feedback nearly doubles the river heat effect.

And from Cold Region Hydrology in a Changing Climate (Proceedings of symposium H02 held during IUGG2011 in Melbourne, Australia, July 2011):

"Siberian Lena River heat flow regime and change"

(6 page PDF)