A Puzzling Collapse of Earth's Upper Atmosphere

(sorry - no graphs. see original article for graphs)

A Puzzling Collapse of Earth's Upper Atmosphere, NASA Science

July 15, 2010: NASA-funded researchers are monitoring a big event in our planet's atmosphere. High above Earth's surface where the atmosphere meets space, a rarefied layer of gas called "the thermosphere" recently collapsed and now is rebounding again.

Layers of Earth's upper atmosphere. Credit: John Emmert/NRL. [larger image] "This is the biggest contraction of the thermosphere in at least 43 years," says John Emmert of the Naval Research Lab, lead author of a paper announcing the finding in the June 19th issue of the Geophysical Research Letters (GRL). "It's a Space Age record."

The collapse happened during the deep solar minimum of 2008-2009—a fact which comes as little surprise to researchers. The thermosphere always cools and contracts when solar activity is low. In this case, however, the magnitude of the collapse was two to three times greater than low solar activity could explain.

"Something is going on that we do not understand," says Emmert.

The thermosphere ranges in altitude from 90 km to 600+ km. It is a realm of meteors, auroras and satellites, which skim through the thermosphere as they circle Earth. It is also where solar radiation makes first contact with our planet. The thermosphere intercepts extreme ultraviolet (EUV) photons from the sun before they can reach the ground. When solar activity is high, solar EUV warms the thermosphere, causing it to puff up like a marshmallow held over a camp fire. (This heating can raise temperatures as high as 1400 K—hence the name thermosphere.) When solar activity is low, the opposite happens.

Lately, solar activity has been very low. In 2008 and 2009, the sun plunged into a century-class solar minimum. Sunspots were scarce, solar flares almost non-existent, and solar EUV radiation was at a low ebb. Researchers immediately turned their attention to the thermosphere to see what would happen.

These plots show how the density of the thermosphere (at a fiducial height of 400 km) has waxed and waned during the past four solar cycles. Frames (a) and (c) are density; frame (b) is the sun's radio intensity at a wavelength of 10.7 cm, a key indicator of solar activity. Note the yellow circled region. In 2008 and 2009, the density of the thermosphere was 28% lower than expectations set by previous solar minima. Credit: Emmert et al. (2010), Geophys. Res. Lett., 37, L12102.
How do you know what's happening all the way up in the thermosphere?

Emmert uses a clever technique: Because satellites feel aerodynamic drag when they move through the thermosphere, it is possible to monitor conditions there by watching satellites decay. He analyzed the decay rates of more than 5000 satellites ranging in altitude between 200 and 600 km and ranging in time between 1967 and 2010. This provided a unique space-time sampling of thermospheric density, temperature, and pressure covering almost the entire Space Age. In this way he discovered that the thermospheric collapse of 2008-2009 was not only bigger than any previous collapse, but also bigger than the sun alone could explain.

One possible explanation is carbon dioxide (CO2).

An NCAR video shows how carbon dioxide warms the lower atmosphere, but cools the upper atmosphere. [more] When carbon dioxide gets into the thermosphere, it acts as a coolant, shedding heat via infrared radiation. It is widely-known that CO2 levels have been increasing in Earth's atmosphere. Extra CO2 in the thermosphere could have magnified the cooling action of solar minimum.

"But the numbers don't quite add up," says Emmert. "Even when we take CO2 into account using our best understanding of how it operates as a coolant, we cannot fully explain the thermosphere's collapse."

According to Emmert and colleagues, low solar EUV accounts for about 30% of the collapse. Extra CO2 accounts for at least another 10%. That leaves as much as 60% unaccounted for.

In their GRL paper, the authors acknowledge that the situation is complicated. There's more to it than just solar EUV and terrestrial CO2. For instance, trends in global climate could alter the composition of the thermosphere, changing its thermal properties and the way it responds to external stimuli. The overall sensitivity of the thermosphere to solar radiation could actually be increasing.

"The density anomalies," they wrote, "may signify that an as-yet-unidentified climatological tipping point involving energy balance and chemistry feedbacks has been reached."

Or not.

Important clues may be found in the way the thermosphere rebounds. Solar minimum is now coming to an end, EUV radiation is on the rise, and the thermosphere is puffing up again. Exactly how the recovery proceeds could unravel the contributions of solar vs. terrestrial sources.

"We will continue to monitor the situation," says Emmert.

For more information see Emmert, J. T., J. L. Lean, and J. M. Picone (2010), Record-low thermospheric density during the 2008 solar minimum, Geophys. Res. Lett., 37, L12102.


Author: Dr. Tony Phillips | Credit: Science@NASA

Volcano Musings

Last week an undersea volcano near Tonga erupted spectacularly on my birthday. Wonderful pictures at Undersea volcano erupts off Tonga coast, including this one:

Today I read that the alert on Mount Redoubt in Alaska is at red (RED: Eruption is imminent with significant emission of volcanic ash into the atmosphere likely OR eruption is underway or suspected with significant emission of volcanic ash into the atmosphere [ash-plume height specified, if possible].) And on the same web page (Alaska Volcano Observatory), I find this photo, taken on my birthday:What a beautiful, beautiful mountain! We are so blessed to live on an earth that is beautiful.
Here is a current readout of the webicorder, just look at all that recent activity. Cool! (or maybe the correct word should be HOT!)
Last night at our team worship time it was commented and wondered at whether there will be mountains and canyons on the New Earth. Mel mentioned that some theologians think those two geographic features are a direct result of sin and the flood and thus will not be on the New Earth. I say: what a sad, pathetic thought. Not Mel's thoughts! but those who look at these things and see only the result of sin. To think that God's perfectly created earth, made just for us, would be smooth as a new cue ball with no high and low features - how very, very sad. I find it equally sad to think that the New Earth and/or New Heaven will be only a city. Ei yi yi!

I look at creation and see the work of God. I see a tiny manifestation of the power of God. And as I've written before, an example of His creativity and beauty. I think God gave us these kinds of things to be a reminder of how great He is and how little we really are. We may be the pinnacle of creation, as I've heard mankind referred to, but we are only a created being on a world created for us. In some ways, seeing the beauty and power of a volcano brings mankind 'back down to size' and brings glory and honor to the Creator of the universe instead. We are not God.

Mankind does such amazing things now - the ISS (International Space Station) is one example, the Mars rovers are another, and the hydrogen bomb and all the other bombs that have followed are even more examples. Yes, mankind can do great things. But can we make the earth quake at a 7.6 as just happened near Tonga? Or can we cause an undersea volcano to erupt? Or cause a series of tornados to devastate a wide area of the American mid-West? No - these things are not in our power. (And I pray they never are!) God can cause them to happen - and He does!

He is still God, and we will continue to remain merely created beings.
How very, very thankful I am for that!

Our Beautiful Earth

I am always amazed when I see photos of the earth taken from space. If you can, and are interested, check this photo out on the actual website, Earth Observatory. Download the full size and then click on it to see it 'up close.' Before the 'space age' man never saw the earth quite like this. We are so blessed to be able to do so.Our Creater is such a wonderful artist. I don't tend to think of God as being 'artistic', probably because I've never heard Him refered to in that way. But every time I see something like this, I wonder at it. Man is artistic, but man is just a pale comparrison to his Creator! The textures and colors, the patterns here and there in the photo - absolutely beautiful. A study in whites.I want to raise my hands and shout out loud - Praise God from whom all blessings flow!

On February 24, 2009, cold northerly winds (perhaps katabatic winds from Greenland) encountered moist air over the Greenland Sea, and their meeting generated dozens of parallel rows of clouds, commonly called “cloud streets,” in the skies around the island of Jan Mayen.
The island added its own influence to the weather, creating an obstacle to the prevailing winds. Like water in a stream as it flows around a boulder, the wind diverged on the north side of the island and converged on the south side. Downwind of Jan Mayen, the air swirled into a string of spiraling eddies, known as von Karman vortices.
At upper left, a small piece of the snow-covered coastline of Greenland is visible, and a mosaic of sea ice hugs the shore. Close to the shoreline, the floes of ice are large, and their shapes are irregular. Farther from the coast, however (top center), the pieces of ice are so small they look like foam.
This image was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite at 12:40 UTC (1:40 p.m. local time in Jan Mayen).
NASA image by Jeff Schmaltz, MODIS Rapid Response Team. Caption by Rebecca Lindsey.