Modtran, Up and Down

We have explored up and down looking spectrometers in prior posts. In all cases the up looking instruments have been on the ground. A fun thing about the Modtran program is that you can look both up and down from any altitude you choose. Here we will begin at the surface and proceed up.

1Modtran up and down 1m Here we are looking at both up and down from 1 meter. The Modtran convention is that the “background run” is red and the “model” blue. In this series red will be looking down and seeing the radiation going up, and the blue will be looking up and seeing the radiation coming down.

It is interesting that looking down Modtran sees no signature of the CO2 bands, only a slight reduction in intensity and temperature from the surface blackbody over the range between WN’s 400-900. Looking up, there is a very strong signal from all the CO2 bands.

2Modtran up and down 10m

At ten meters there is very little difference.

3Modtran up and down 100m

Deja vu all over again at 100 meters except for the suggestion of a signal at WN 618 where CO2 picks up a vibrational quantum number. This is the strongest CO2 band besides 667.4, albeit two orders of magnitude weaker.

4Modtran up and down 1km

Finally, at one kilometer we begin to see a half baked signal in the CO2 bands looking down. How is this possible? How, in the first kilometer, where nearly all CO2 is introduced to the atmosphere, can there be no radiative signature?

The answer is simple and surprising. The atmosphere does not radiate in the CO2 bands in the first kilometer. At least not in the bands strong enough to generate a signal. In the first kilometer, all of the signal originates at higher altitudes.

CO2 is a fun kind of molecule. It likes to swim, and it likes to dance. Quantum vibration is the dominant form of excitation in the IR part of the spectrum and this “gitt’n jiggy wid it” is the reason CO2 absorption is thermalized rather that re radiated in the first kilometer of the earth’s atmosphere.

The concept here is very simple. We are talking about the percentage of light energy absorbed by CO2 that is kinetically dispersed (thermalized) rather than re emitted as a photon, and the observation that we are not seeing CO2 photons emitted in the first kilometer of the atmosphere.

The formal physics of this concept is very difficult. It engages the entire legal cannon of radiative transfer laws from Planck, Boltzmann, Kirchoff, Beer,, without being satisfyingly resolved by any of them. An important reason for this is that the atmosphere is never in equilibrium. This concept of a tendency for CO2 to thermalize rather than radiate in the first kilometer is probably better thought of as just a physical property of the atmosphere.

We will climb higher in the next post.

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Carbon Pricks

It is not well-known that there was once there was a job title “Prick”. It was back during the witch crazes and Inquisition that racked Europe during the 13th to 16th centuries.

Many forces combined in this human aberration that resulted in the slaughter of hundreds of thousands. The early modern period saw the breakdown of the feudal order as the beginnings of industrialization fostered the growth of towns. There was a collateral decline in the authority of the Roman Catholic Church. The climate had turned cold in the Little Ice Age, and plagues ravaged the population packed into the towns.

In spite of the Renaissance, and in part because of it, there was a dark undercurrent of guilt and uncertainty and a feeling of impending doom.

Time for scapegoats. Time to placate the angry God.

The job of the Prick was to go around and prick birthmarks. Birthmarks were thought possible evidence of salacious conjugation with the devil, but it was recognized that not all were. If your pricked birthmark bled, it was deemed natural. If not…

Zoom to the 21st century. The nasty black ooze of buried hydrocarbons has been transformed by modern alchemy into traffic choked megalopolis where the dream of zipping about at every whim comes to face the reality of the stupendous magnitude of the desire to do so. Electrons spun by the same ooze power information far beyond our capacity to assimilate. People seated together text rather than talk. There is deep uncertainty, and a feeling of impending doom.

Meet the modern witch, Carbon. Element number 6. An element so magical an entire branch of chemistry is devoted to it. An element fundamental to the chemistry of life itself.

A modern sort of witch, to be sure. Capable of both good and evil. Both Christ and Antichrist. The green and the black. Blamed for every natural event, real or imagined.

Time to sacrifice the ooze to the angry God.

The Carbon pricks go around checking our footprints.

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Food Stamp Cowboys

Sad but true. The food stamp cowboy is a close relative of the OSHA cowboy:


A food stamp cowboy would actually need all the protections afforded by OSHA. A real cowboy would not.

A cowboy fills a niche. Ironworkers are cowboys too. This is how the big cities were built:



Life is dangerous. Every generation develops its own definition, but getting nothing done is dangerous too.



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The Religious Left

I have never been a fan of the religious right. These folks seemed always against the Theory of Evolution, women’s rights, and generally in favor of literal interpretations of the Bible.

Doesn’t work for me.

Now comes an insidious religious left, clothed in the trappings of science, yet every bit as doctrinaire and opposed to progress in science as the religious right.

The religious left is the Calvinistic “Science” of dangerous human warming. No matter the mountain of contravening data. Nothing matters but chapter and verse. You must have credentials to think.

Doesn’t work for me.

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79-9.101 Shiprock

This picture was taken in September 1979. There is a print of it in my office, faded a bit. When I wax geological, the sheer improbability of this mineralogically unusual salient weighs heavily. High in Magnesium, Potassium and Sodium; low in silica. Indicative of deep mantle provenance and deep crystallization.

It is not alone. It is the oldest and largest of a late Oligocene/early Miocene Navajo Intrusive Complex. When you drive to Kayenta, Arizona, you see the foreshadowing, mafic menhirs begin punctuating a red landscape .

We were young then. We had climbed the highest peaks in the major ranges of Colorado and were headed for a river trip down the Grand Canyon. Foolish perhaps, we steered our VW bus down a dirt road in the dark. Knowing full well it was Navajo land. Knowing full well the site was sacred and climbing had been banned.

We hadn’t come to climb. We came to worship. Maybe that spirit was somehow clear to a few pickup trucks that slowed to check us out. Whatever, they let us be, and I took this picture as the first sun washed it in the morning.

Unforgettable, at least with a reminder on the wall, and business and fate carried us back there last week.


From the south the shoulders of scree are less prominent and you get a perspective on one of the three dikes that radiate from Shiprock in nearly 120 degree increments.


The real story here may be the uplift of the Colorado Plateau. Like at the rim of the Grand Canyon, your feet are in the Triassic, and to see when the dinosaurs roamed you look not down, but up. You try to imagine a Mesozoic section as tall as from the rim to the river that has been eroded away. This is the story of Shiprock. It’s ultramafic low silica magma intruded a mile of sediments since removed.

Why this uplift and under plating should have happened here, at a time between the Eocene Laramide buckling of the “ancestral” Rocky Mountains, and the general uplift and extension of the intermountain West since the Miocene, remains a mystery. So much so that Navajo legends of an uplifting creature saving their ancestors is still nearly as good an explanation as any.



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What is Waiting in the Wings?

We recently finished a series of posts on the 2 good greenhouse gas in which we established that all the “earthlight”, the long wave spectra emitted at the temperature of the planet surface is extinguished within about 100 meters of the surface in the bands comprising the fundamental bending strike zone of CO2.

This past series established what CO2 cannot do to warm the planet. We are told that the “wings”, bands outside the fundamental bending zero transmission zone will pick up the slack and warm the planet. This series will explore what CO2 can do to warm the planet.

Modtran Transmission v Fundamental bend

The argument is very simple. The earth emits a finite amount of light. When that light is extinguished by complete absorption and zero transmission, it’s gone! It can’t just sneak around somewhere. The atmosphere completely blankets the earth.

In the graphic above transmission to the tropopause at 280 ppm CO2 is shown. There is a large flat spot of zero transmission. This flat spot is defined by the fundamental bending mode of CO2 shown here at 400 ppm. The zero transmission zone grows accordingly when 400 ppm transmission is plotted, but the point here is that zero at 280 ppm and zero now equals zero difference.

The red plots are the significant excitation bands for CO2. The fundamental 667.4 band represents nearly 90% of the total energy, and the other bands had to be exaggerated orders of magnitude to even get them to show up in the graphic. Four of these bands fall outside the primary zero transmission flat spot, but two of these, 647.1 and 720.8 form their own zero transmission troughs even at 280 ppm. This leaves only 544.3 and 597.3, shown with dotted lines to their corresponding troughs as candidates for warming in the wings.

What of these wings? Below are MODTRAN CO2 only 280 ppm vs 400 ppm comparisons for a few altitudes:

Modtran 5km 280v400ppm CO2

Modtran 10km 280v400ppm CO2

Modtran 15km 280v400ppm CO2 Modtran 20 km 280v400ppm CO2 Modtran 70 km 280v400ppm CO2

If your eyes are anything like mine, you will see that there is very little difference between the 280 and 400 ppm plots for CO2 alone and that no large lateral “wings” of radiance emerge. Ain’t much chicken on them wings.

In the next post we will explore what makes the “wings” take flight. Water.

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The 2 Good Greenhouse Gas III (Looking Up)

We have been looking down so far. What happens when you stand on the ground and point a spectrometer up? Interesting things.

downwelling ground up


In the CO2 bands around wave number 667 a spectrometer pointed up from the ground sees radiation at very near surface temperature. In the cases above that near surface temperature was about 245  K in Barrow and 300 K at Nauru. The spectra are very different in form as a result of different humidities in the atmospheric window and ozone bands to the right. In the cold, dry air at Barrow the instrument reads near zero except for the ozone bands. Those photons are running away straight to space and there is nothing to see. In the warm, moist air of Nauru the window is very “dirty” and noisy due to scatter and radiation by water.

Looking Up Barrow and Nauru vs Looking down Sahara

We can add our trusty Sahara looking down for comparison. The hot dry air is a good inverse for Barrow.

All Up

Finally we add an interesting spectrum looking up from Cerro Toco at 5 km altitude (but still on the ground) in the Atacama Desert in Chile. Notice how in the dry desert air the atmospheric window very closely matches Barrow with the photons fleeing at the speed of light and the instrument seeing next to nothing, while the higher near surface temperature shows clearly in the CO2 bands.

Note the difference between Barrow and Cerro Toco. The dip in the Barrow (Grey) CO2 bands results from a strong surface inversion. Close to the instrument, the radiance reads at a lower temperature. You essentially get an inverted altitude profile of CO2  absorption. Below is the 1 meter path at 400 ppm.


infrared_spectrum surface looking up and down Arctic Ice

In an amazing experiment shown above, the same instrument, one pointed up from the surface of Arctic ice, and another looking down from some sort of platform at 20km took measurements of the same place at essentially the same time. In the atmospheric window the U-2 looking down sees a very chilly near surface at~267 K. The one on the ice looking up sees a much chillier 160 K. The 20 km looking down sees a very clean signal of high intensity, the ice looking up sees a noisier signal of very low intensity.

They both see a clean blackbody signal in the CO2 bands with the 15 micron/667.4 wave number “spike” pointed up towards higher intensity and temperature. No surface inversion here.

In this series we first explored the lack of correlation between temperature and CO2 at long time scales, the dependence of CO2 on temperature at Neogene scale, and the dependence of CO2 variation around the trend on temperature, but not the trend itself as the trend becomes distorted by human emission in the satellite era.

We followed up with a look at radiance on the IR earth bands and found that satellites are seeing CO2 radiance taking place between ten and twenty kilometers in the upper troposphere and lower stratosphere. We then found that the same instruments pointed up from the surface see CO2 radiating very near the surface.

The problem is that the 2 good greenhouse gas  gobbles up all the surface IR within a hundred meters of the surface. This is clear from transmission.


Even at 280 ppm preindustrial levels of CO2 there is ZERO transmission of  surface IR to the tropopause in the fundamental bending bending bands. Furthermore, the 667.4 band and its homologous rotational bands DEFINE the zero transmission gap.

The fundamental bend commands 89% of the Boltzmann absorptive and radiative potential of CO2. This is why it gobbles up the surface IR so fast. This is why CO2 does not drive temperature at any time scale. It has already eaten all the earth photons in its strike zone at preindustrial levels. Adding more CO2 has no effect in these bands.

It is just too good.

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