I hope you’ll excuse the exaggerated exuberance in the headline, but when I saw the image above, and then the animation lower down in this story, my first reaction really was to exclaim out loud “whoa!”
I was really struck by the two very curious whirlpool-like features on opposite sides of Earth — one gigantic the other small, one eerily green and the other swirling over a red dessert. And so I decided to try to shoehorn them into one ImaGeo post! Here goes…
At first, the glowing green whirlpool seen in the image above seemed wondrous: It turns out to be a giant bloom of phytoplankton in the Gulf of Finland that has been swirled into a vortex by an ocean eddy. It was imaged on July 18, 2018 by the the Landsat 8 satellite, according to a NASA Earth Observatory story.
The swirling bloom is at least 15 miles across, which means New York City’s Manhattan Island could fit inside it with a little room to spare. (For a more tangible sense of scale, click on the version of the image at right and look for the ships.)
But my sense of wonder quickly turned to unease when I learned that the phytoplankton are most likely photosynthesizing cyanobacteria, a form of blue-green algae. And that almost the entire Gulf of Finland has been “infested” with the organisms, as a Finish news site put it — likely the result of recent soaring temperatures and an abundant supply of nutrients in the water from sewage and agriculture runoff.
Extensive phytoplankton blooms are common in North Atlantic and Arctic Ocean waters, “with blooms spanning hundreds and sometimes thousands of kilometers,” according to NASA. But blooms this summer off of Scandinavia “seem to be particularly intense.”
The blooms have been leading to trouble in recent years. As NASA puts it:
In recent years, the proliferation of algae blooms in the Baltic Sea has led to the regular appearance of “dead zones” in the basin. Phytoplankton and cyanobacteria consume the abundant nutrients in the Baltic—fueled largely by runoff from sewage and agriculture—and reproduce in such vast numbers that their growth and decay deplete the oxygen content of the water. According to researchers from Finland’s University of Turku, the dead zone this year is estimated to span about 70,000 square kilometers (27,000 square miles).
The Baltic experiences some of the world’s largest dead zones. And a study published earlier this month by German and Finnish researchers found that oxygen loss in coastal areas over the past century is unprecedented in the last 1,500 years.
Meanwhile, on the other side of the planet, check out this little whirlpool spinning in the clouds above the Australian outback, a bit west of the city of Alice Springs. It is what meteorologists call a “mesovortex” — a cyclonic swirl of air that can range from a mile or so in diameter to tens of miles wide.
Mesovortices can spawn in the eyewall of a hurricane, and in association with thunderstorm activity. But this one seems to have been born in another way — perhaps as winds were diverted around a blunt, high-profile landscape feature.
This happens all the time off the coast of California (to mention just one region) as prevailing winds encounter islands, creating what are known as “von Kármán vortices.” Here’s an awesome example:
So many von Karman vortices. So amazing to watch. (h/t @lilly_wx) pic.twitter.com/6hBa7mJ2Q1
— Dakota Smith (@weatherdak) March 31, 2018
“It certainly has a similar look to some of the vortices that often form off California,” said Philippe Papin, an atmospheric scientist at the Naval Research Laboratory, replying to a query I posed to him on Twitter.
In fact, I learned of the little Australian vortex from a Tweet by Papin:
Check out this stunning #Himawari 0.5km visible loop of a clear #vortex within a stratocumulus deck near #AliceSprings, #AU. I’m use to seeing shallow vortices in the marine layer off of #California, but not in the #Australia #Outback!
Source: @CIRA_CSU: https://t.co/f0o3JWWs7W pic.twitter.com/fkDbfaiMJ7
— Philippe Papin (@pppapin) July 24, 2018
But the Red Center of Australia is a very different environment than the coastal waters of Southern California, to say the least!
Well actually, we’ve got a low-lying cloud deck that is similar to what is often present off the California coast. We’ve also got moving air. And I think we’ve got a candidate for a blunt, high-profile landscape feature — a kind of island in a red dessert sea:
You’re looking at the remnants of a likely impact crater. Known as Gosses Bluff, it is about 100 miles west of Alice Springs in Australia’s Northern Territory.
It is located in what seems to me to be just the right place to have caused the diversion of air needed to form a little von Kármán vortex.