Understanding OLR and DLR vs Radiance Measurement by CERES and Pyrgeometer.

Outgoing Longwave Radiation OLR from the Top of the Atmosphere ToA is measured by a CERES satellite looking down on ToA equipped with a sensor as one end of a thermocouple with its other end kept at a steady temperature generating a voltage scaling with the temperature difference at its ends. 

The CERES instrument is calibrated by determining a gain factor from sensor temperature to radiance letting the instrument look at a black body of known temperature $T_B$ with assumed Planck radiation $\sigma T_B^4$ while recording the sensor temperature. With the gain factor so determined the instrument reports radiance from ToA from a reading of sensor temperature. This is the simplest form of calibration assuming linearity. Very primitive technique, where the details of the instrument do not matter. It is like measuring intensity of rainfall using your hands to collect water calibrated to a faucet. The accuracy is at best 1 W/m2 or 0.4% of the same size as estimated Earth Energy Imbalance from CO2.  

A pyrgeometer measuring Downwelling Longwave Radiation from the atmosphere to the Earth surface also uses a sensor as one end of a thermocouple with the other end kept a base temperature, and also measures a voltage scaling with temperature difference. The calibration is here different because the outgoing radiation from the sensor can no longer be included in the calibration process, but has to be supplied through a Planck formula $\epsilon\sigma T^4$ with $T$ sensor temperature and $\epsilon$ sensor emissivity. The accuracy is at best 5 W/m2 again too big to detect global warming if present.

OLR and DLR are thus measured in a similar way, but with different forms of calibration the difference being that OLR faces empty space ay 0 K, while DLR faces the Earth surface. The accuracy is not enough to decide any size of global warming, although it is claimed that trends can be detected. 

In both cases Planck's Law in the form $\sigma T^4$ is used, which in the case of DLR is incorrect because the correct form is $\sigma (T^4-T_E^4)$ with $T_E$ Earth temperature expressing negative DLR.  

Summary: Measurements of OLR and DLR are made to detect global warming. The accuracy of the instruments is not good enough to detect any warming if present. DLR measurements can be questioned since an incorrect Planck Law is used. OLR and DLR as radiance as process variable fluctuate and as such are difficult to measure.  

EEI is a cornerstone of global warming alarmism, and so measuremennt of EEI has become a prime task for instrument technology, which does not seem to have delivered. The effect of EEI on surface temperature is unknown and impossible to measure and DLR is a misconception based on an incorrect form of Planck's Law.

ChatGPT on objective of CERES: 

CERES connects to global warming because it:

• Measures the planetary energy balance directly at TOA.

• Detects changes in OLR and OSR (reflected shortwave) caused by greenhouse gases, aerosols, clouds, and ice.

• Provides the evidence that Earth is currently taking in more energy than it loses — the physical basis of global warming.

ChatGPT on objective of measuring DLR :

• Provide a direct measure of the atmosphere’s infrared emission to the surface, essential for closing the surface energy budget, quantifying the greenhouse effect, tracking climate change, and validating models.

We read that the objective of CERES is to support global warming alarmism by measuring and reporting EEI attributed to CO2. But the objective is not reached, because (i) the accuracy of the measurement is not better than 1 W/m2, which is the expected size of EEI, and (ii) attribution to CO2 to is not credible because it is swamped by changes of cloud cover. We read that the objective of measuring DLR by a pyrgeometer is to quantify greenhouse effect. Both cases amounts to "chasing after wind" using "ghost detectors". 

Is Measuring Temperature at Distance Possible and Useful?

Climate alarmism of global warming claims to be supported by measurement of the energy balance of  Earth+atmosphere by instruments like pyrgeometers, bolometers and radiometers with an accuracy of at best 1-2 Watts/m2 compared to a total of around 240 W/m2 and a projected total imbalance of 4 W/m2 as "radiative forcing" from doubling of atmospheric CO2 corresponding to a warming of 1 K. 

The case for global warming may seem weak from these measurements, but nevertheless they serve to foster alarmism. 

To properly evaluate the measurements it is necessary to understand how these instruments are designed and how they operate. For a pyrgeometer or bolometer using a thermocouple as sensor, there are two fundamentally different views:

1. A thermocouple essentially measures incoming radiance from a source as a process variable. 
2. A thermocouple essentially measures a source temperature as a state variable.  

It is natural to make a comparison in terms of a bank account:

1. Difference between deposits and withdrawals as process variable.
2. Total savings as state variable.

We understand that total savings may be fairly stable, while deposits minus withdrawals can fluctuate quite a bit. The same for temperature vs radiance imbalance. 

What does then a thermocouple as sensor in fact measure? Radiance or temperature? 

1. There is a widely spread view that a thermocouple essentially measures radiance and so can be used to reliably measure both incoming and outgoing radiance for Earth+atmosphere and so determine imbalance, even if the accuracy is not better than 1-2 Watts/m2, and so detect global warming. Radiance is then measured through a calibration process confronting the sensor with sources of known temperature $T$ with radiance according to an assumed Planck-Stefan-Boltzmann Law of the form $\sigma T^4$.  

2. There is also a different view that a thermocouple essentially measures source temperature by essentially allowing the sensor to take on the source temperature by radiative equilibrium established optically at distance. In practice the radiative equilibrium source-sensor is only partially established by sensor cooling, but the principle of radiative equilibrium with equal temperature remains. 

Case 2 builds on a clear physical principle of radiative equilibrium in stable measurement of a state variable.

Case 1 is based on instrument calibration vs sources/blackbodies of known temperature $T$ assumed to give radiance input of $\sigma T^4$, while the true input is PSB in the form $\sigma (T^4-T_i^4)$, where $T_i$ is instrument base temperature which is not 0 in general. Case 1 is thus based on a calibration process using an incorrect PSB law inflating input radiance. Moreover the measurement concerns a process variable prone to instability. There are cryogenic sensors with very small $T_i$ and better precision. A proof of the correct PSB Law in classical terms without statistics is presented here and in this talk.

Case 1 is consensus and is used to support alarmism from measured radiance imbalance of Earth+atmosphere as if this is a fact. But the measurement precision barely can capture any imbalance from doubled CO2. Unfortunately many climate skeptics embrace the idea that a pyrgeometer measures massive incoming radiance (Downwelling/Upwelling/Outgoing Longwave Radiation) and so go along with a basic alarmist argument: The measured energy imbalance is the result of more CO2. 

A careful study shows that a thermocouple in fact measures source temperature as stable output, while derived radiance can be misleading because the calibration uses an incorrect PBS Law and is prone to instability. This means that measured energy imbalance can be questioned along with alarmism.

But the discussion is pretty much closed on 1 as the truth. Hopefully a new discussion can take place around the question: What does a thermocouple primarily measure and on what physical grounds? How can a thermometer acting at distance be constructed? Is an IR-camera such a thing?

CERES Satellite vs Surface Buoy Temperatures

The recent discussion on the Big Bluff of  DLR gets perspective in a WUWT post by Willis Eschenbach on CERES Calculated Surface Datasets:

• The CERES dataset is satellite data that is based on radiation measurements made from low earth orbit. The CERES data has two parts. The first part is observational data, measurements of downwelling and upwelling solar radiation and of upwelling longwave radiation. It is usually referred as the CERES “top-of-atmosphere” data. The official name is “CERES EBAF-TOA”, and it is available here.
• However, the second part of the CERES is not top-of-atmosphere observations from the satellite. Instead, it is calculated surface data based on the CERES TOA observations along with other satellite observations. It’s called the “CERES EBAF-Surface” dataset, and is available from the same location.
• As a result, I’ve always been concerned about the accuracy of the CERES surface data. After all, it’s just calculations, it’s not actual observations. So I got to thinking that I could “ground-truth” the CERES surface observations by using the TAO buoy data. It’s not a comprehensive test by any means, but the TAO buoys cover a region of great interest to me, the tropical Pacific. The TAO buoy data is available here.

Eschenbach is surprised to see that makes CERES and TAO surface temperatures observation agree.

But this is not surprising: To measure surface temperature at distance from satellite is possible, through the atmospheric window at clear sky.

Eschenbach is even more surprised to see agreement on DLR from CERES satellite and TAO surface data. 

Again this is no wonder, since DLR is computed in the same (unphysical) way from temperature measurements. By inventive "calculation" anything can be supported. 

KlimatUpplysningen 2: The Big DLR/Back Radiation Bluff

This is a reposting of an earlier post.

The Earth's energy budget is surveyed by

• pyrgeometers on ground measuring downwelling longwave radiation DLR (GEWEX)
• bolometers on satellites measuring outgoing longwave radiation OLR (ERBE and CERES)

where

• $DLR$ = heat flux from atmosphere to the Earth surface (in W/m2)
• $OLR$ = heat flux from atmosphere into outer space at 0 K (or 3 K)

operating according to the following algebraic formulas:

• $DLR  = V/K + \sigma T_i^4$ = $DLR$-Pyrgeometer Formula
• $OLR = E + \sigma T_i^4$ = $OLR$-Bolometer Formula 

where 

• $T_i$ is measured instrument temperature
• $V$ is voltage measured by pyrgeometer sensor and $K$ is a sensitivity coefficient
• $E$ is heat flux measured by a bolometer thermal link.

The Bolometer Formula is obtained from Stefan-Boltzmann's Law 

•  $E = \sigma (T_a^4 - T_i^4)$

where $\sigma = 5.67 \times 10^{-8}$ is Stefan-Boltzmann's constant, $T_a$ is the bolometric temperature obtained by calibrating the bolometer against a blackbody. Defining $OLR = \sigma T_a^4$ gives the Bolometer Formula with $OLR$ representing the heat flux from the atmosphere into outer space as stated. 

$OLR$ as reported by ERBE and CERES based on the $OLR$-Bolometer Formula is thus the heat flux from the Earth with atmosphere into outer space based on Stefan-Boltzmann's Law, and as such represents real physics: The Earth + atmosphere transforms shortwave heat energy received from the Sun into longwave heat energy which is returned to outer space as $OLR$.  This makes sense as true real physics.

We now turn to $DLR$, which we know by previous posts represents the BIG BLUFF of CO2 alarmism: The $DLR$-Pyrgeometer Formula seems to be an analog of the $OLR$-Bolometer Formula and the BIG BLUFF is now to argue that since the OLR-Bolometer Formula makes sense as an expression of Stefan-Boltzmann's Law, also the $DLR$-Pyrgeometer Formula makes sense. But this is not true!

The $DLR$-Pyrgeometer Formula is supposed to be an algebraic reformulation of  

• $\sigma (T_a^4 - T_i^4) = V/K$ with $DLR = \sigma T_a^4$,

where $\sigma (T_a^4 - T_i^4)$ is the heat flux between the atmosphere at temperature $T_a$ and the pyrgeometer at $T_i  > T_a$ according to Stefan-Boltzmann's Law, as measured by the (negative) voltage $V$. The BIG BLUFF is to give the algebraic reformulation a physical meaning with $DLR = \sigma T_a^4$ interpreted  as the heat flux from the atmosphere to the Earth surface. But this is not the physics:

• $\sigma T_a^4$ is heat flux from a blackbody into outer space at 0 K.
• $\sigma T_a^4$ is not heat flux from the atmosphere to the Earth surface because there is no such heat flux because $T_a <  T_i$.

We can see through the BIG BLUFF of CO2-alarmism with $DLR$ as heat flux from the atmosphere to the Earth surface with a warming effect:

$DLR$ is computed from a non-physical $DLR$-Pyrgeometer Formula which is deceptively similar to a physical $OLR$-Bolometer Formula, and the BIG BLUFF is to say that because $OLR$ is real so is $DLR$ and global warming. 

The BIG BLUFF of $DLR$ is

• cleverly constructed with a clever mixing of $OLR$ and $DLR$, 
• cleverly covered up in technical documents presenting the non-physical $DLR$-Pyrgeometer Formula as a version of the True Stefan-Boltzmann's Law, which expresses one-way heat flux from warm to cold,  
• hiding that the $DLR$-Pyrgeometer Formula represents a False Stefan-Boltzmann Law expressing two-way heat flux with in particular heat flux from a cold atmosphere to a warm Earth surface in violation with the 2nd Law of thermodynamics.      

Global warming alarmism is based on $DLR$ demonstrated by instrumental evidence as a scientific evidence of global warming by back radiation from "greenhouse gasses" including the trace gas CO2. But this is fabricated evidence without physics reality and so it is a BIG BLUFF.  It may be the BIGGEST SCIENCE BLUFF EVER, in the sense that it asks for diversion of massive resources into meaningless curbing of CO2 emissions with no doubt catastrophical consequences for large parts of the human population.  

It is not hard to see the bluff once you understand where to look and not get diverted away from what is really happening when the trick is performed.

PS Here is from the product specifikation of the Kipp and Zonen CG3 pyrgeometer:

• The CGR 3 is a pyrgeometer, designed for meteorological measurements of downward atmospheric long wave radiation. The CGR 3 provides a voltage that is proportional to the net radiation in the far infrared (FIR). By calculation, downward atmospheric long wave radiation is derived.

It could not be more clear: Net radiation is measured, DLR is derived.  The BLUFF! 

Story of Vanishing Evidence of CO2 Warming

In the late 20 century as the cold war was coming to an end, the fear of nuclear war was replaced by a fear of anthropogenic global warming caused by emissions of CO2 from burning of fossil fuels.

Governments united under UN gave massive support to science for producing evidence of global warming by CO2, evidence which governments could use to motivate a special tax on CO2, which would lead society into a new world without CO2-emissions, with lots of tax money to be spent by politicians.

Scientists started, with great enthusiasm stimulated by generous government grants, searching for evidence of a warming effect of CO2 in the form of a  "greenhouse effect" with CO2 named "greenhouse gas" because of its capability of absorbing and emitting infrared radiation at isolated specific frequencies, because of its unsymmetric molecular structure, as observed in an early study by the Swedish Nobel Laureate Svante Arrhenius from 1896.

But finding evidence was difficult because CO2 is an atmospheric trace gas (now 390 ppm) and it is always difficult to find evidence of a big effect from a small cause, because this can only happen in unstable systems and such systems have no permanence allowing study.

An idea which developed was that doubling of CO2 would cause a "radiative forcing" of extra 2 - 4 W/m2 to be added to the 240 W/m2 received from the Sun, which was connected to a global warming of 1 C. Of course 1 C would be barely noticeable, but that was the best that could be squeezed out of CO2 alone, but with feedback from the system under "radiative forcing" from doubled CO2, the warming could be inflated to 3 C, which would enough to motivate a tax on CO2 to save the world.

The whole story of global warming by CO2 then rested on finding evidence of "radiative forcing" of  2 - 4 W/m2 from doubled CO2 and scientists were ordered to construct instruments for recording radiation spectra, which could show this effect.

But this turned out to be virtually impossible, because 2 - 4 W/m2 was too small to be measured: It required an accuracy below 1% which was impossible to achieve in practice. The difficulty of a big effect from a small cause showed its real face.

To counter this "small cause - big effect" syndrome, new physics of "back radiation" was invented showing a warming of 300 W/m2 of the Earth surface from the colder atmosphere as a big cause, but the new physics violated the 2nd law of thermodynamics and thus belonged to fiction.

What then remained of scientific support of CO2 alarmism based on observation, was a recorded global warming 1970 - 1998 of 0.5 C, which was connected to an increase of atmospheric CO2 from 330 to 370 ppm during the same time.

But this connection disappeared during 1998 - 2013, which went by without global warming, while CO2 continued to increase to 390 ppm.

The evidence of global warming by CO2 has thus today crumbled to nil,  which presents a difficult case for the new report by IPPC under UN in charge of CO2 alarmism, to be presented in September. Without scientific support, a CO2 tax cannot be motivated and the whole BIG BLUFF project of unprecedented  dimensions, collapses.

... and All the King's Horses and all the King's Men Couldn't put Humpty together again...

This is a summary of a study I was led into starting in 2009 and I have reported on this blog.

AGW vs WMD

NASA is now spending big money on projects such as CERES to find instrumental evidence of anthropogenic global warming AGW, but finds nothing. It is similar to the fruitless efforts by CIA to find evidence of weapons of mass destruction WMD in Saddam Hussein's Iraq. Is this an expression of paralyzed US politics?

CERES and Radiative Forcing

      The Earth's energy budget according to CERES showing unphysical "back radiation" of 340 W/m2
'
An overview of the CERES project is given in CERES, a review: Past, present and Future (2011):

• The Clouds and Earth Radiant Energy System (CERES) project’s objectives are to measure the reflected solar radiance (shortwave) and Earth-emitted (longwave) radiances and from these measurements to compute the shortwave and longwave radiation fluxes at the top of the atmosphere (TOA) and the surface and radiation divergence within the atmosphere. The fluxes at TOA are to be retrieved to an accuracy of 2%. 
• The first objective of CERES is to measure OLR radiances to an accuracy of 1% and reflected solar radiances to 2%. The global mean OLR flux is approximately 240 W/m2, so the requirement is 2.4 W/m2 accuracy. Likewise the global mean reflected flux is 100 W/m2, thus the requirement for shortwave flux is 2 W/m2.

We compare the accuracy of 2-3 W/m2 with by IPCC supposed "radiative forcing of  CO2" of 1.8 W/m2 and "total anthropogenic radiative forcing" of 1.6 W/m2 during 1750-2005 and 3.7 W/m2 from doubled CO2. 

We conclude that the accuracy of CERES even at the lower level of 1% for OLR, would not be good enough to detect effects of "radiative forcing" by CO2. 

That the "radiative forcing" of doubled CO2 would be 3.7 W/m2 is a wild guess by IPCC without experimental support, which serves as the following cornerstone of CO2 alarmism:

• Without any feedbacks, a doubling of CO2 (which amounts to a forcing of 3.7 W/m2) would result in 1 °C global warming, which is easy to calculate and is undisputed. 

Here the "easy undisputed calculation" is dQ = 4 dT, where dQ is "radiative forcing" and dT corresponding global warming as a differentiated form of Stefan-Boltzmann's Law Q = sigma T^4. 

The number 3.7 or 4 W/m2 is so chosen by IPCC that the global warming would be 1 C, according to the "easy undisputed calculation", which is not too big to not be possible and not too small to be negligible. The basic argument of CO2 alarmism is that with feedback 1 C can become 3 C which is alarming. 

The whole idea of "radiative forcing" lacks sound physics basis since the forcing comes from the Sun and only from the Sun, and this is reflected by the fact that it cannot be discovered by instruments measuring physical phenomena, that is, it is fiction of a BIG BLUFF.

PS CERES is selling itself e.g. on a video telling us

• When you add greenhouse gasses such as CO2 and methane you change that radiation balance on the top of the atmosphere and you change the amount of outgoing radiation so that imbalance means more energy in the system...part of it goes into the ocean...and part of goes into actually warming the Earth...all of those things should give you a coherent picture of how things are changing as we warm the climate...

The purpose is obvious: Use CERES to show global warming by radiative forcing from CO2. The only trouble is that CERES shows nothing of this sort...all attempts to measure radiative forcing by CO2 seem to fail miserably...the scale of the BIG BLUFF with its organized governmental science support, is really impressive...  

CERES: No Global Warming Detected

In previous posts we have decoded the BIG BLUFF of CO2 alarmism based on fabricating evidence of a global warming effect of CO2 in large scale experimental projects such as ERBE followed by CERES designed to produce measurements of radiative fluxes. While ERBE focussed on outgoing long wave radiation OLR as one-way heat flux from the Earth + atmosphere into outer space at 3 K, which is physical heat flux, CERES has lifted the ambition to include two-way heat fluxes between different parts of the atmosphere and the Earth surface, which lack physical reality:

 

The objective of CERES is described as follows on Daily Press Febr 14 2012:

• Clouds and the Earth's Radiant System CERES is one of five earth science experiments aboard Suomi NPP, a $1.5 billion satellite NASA launched into space Oct. 28 2012 from Vandenberg Air Force Base in California.
• Managed at NASA Langley Research Center in Hampton, CERES measures the amount of sunlight that enters Earth and how much sunlight and thermal radiation is reflected back to space. The concept is known as Earth's energy budget.
• According to NASA, the sun annually provides the planet about 340 watts per square meter — roughly the energy radiated from six incandescent light bulbs. If the planet returned an equal amount of energy to space, temperatures would be constant, Loeb said.
• That is not occurring. Instead, roughly 0.8 watts per square meter stays on Earth.
• The energy is trapped by greenhouse gases, such as water vapor and carbon dioxide, that come from burning fossil fuels and other sources. Clouds also play a role; they reflect sunlight back into space and, depending on their height and thickness, prevent it from leaving the planet.
• The imbalance helps explain why global temperatures increased 1.4 degrees since last century and sea levels are rising, Loeb said.
• NASA uses computer models to summarize the images into daily and monthly reports that date back to 1985. That's when another Langley instrument, ERBE, or Earth Radiation Budget Experiment, began monitoring the planet.
• Four successive CERES instruments — the one launched in October is a fifth generation — followed, providing data used by, among others, the Intergovernmental Panel on Climate Change. 
• The panel, which shared a Nobel Peace Prize with former Vice President Al Gore, wrote what many view as the definitive report on climate change.

CERES has four main objectives:

1. For climate change analysis, provide a continuation of the ERBE record of radiative fluxes at the top of the atmosphere (TOA), analyzed using the same algorithms that produced the ERBE data.
2. Double the accuracy of estimates of radiative fluxes at TOA and the Earth's surface.
3. Provide the first long-term global estimates of the radiative fluxes within the Earth's atmosphere.
4. Provide cloud property estimates that are consistent with the radiative fluxes from surface to TOA.

CERES primary measured data are obtained as output:  

• scanning thermistor bolometer sensors which measure Earth-reflected and Earth- emitted filtered radiances in the broadband shortwave (0.3 μm - 5.0 μm), broadband total-wave (0.3 μm - >100 μm), and narrow-band water vapor window (8 μm-12 μm) spectral regions. 

We see that CERES is used to record radiative heat fluxes using sophisticated technology with the ambition to discover effects of global warming by CO2 as an radiative imbalance.  To the disappointment of the designers and users of CERES including IPCC Al Gore,  the instruments show next to nothing: An imbalance of 0.8 W/m2 out of 340 W/m2 is smaller than any thinkable measurement error. 

CERES (like LHC) thus discovers nothing, and what we can now expect is a new bigger project with more sensitive instruments with doubled accuracy with the hope of finding something which is not zero as evidence of global warming by CO2. 

This will not be cheap, but when you go to an expensive restaurant you expect to be offered something special, and so the high price and sophistication of the instrumentation can be seen as a guarantee that something will be discovered.  

BIG BLUFF: Pyrgeometer DLR as Bolometer OLR

The Earth's energy budget is surveyed by

• pyrgeometers on ground measuring downwelling longwave radiation DLR (GEWEX)
• bolometers on satellites measuring outgoing longwave radiation OLR (ERBE and CERES)

where

• DLR = heat flux from atmosphere to the Earth surface (in W/m2)
• OLR = heat flux from atmosphere into outer space at 0 K (or 3 K)

operating according to the following algebraic formulas:

• DLR  = V/K + sigma T_i^4 = DLR-Pyrgeometer Formula
• OLR = E + sigma T_i^4 = OLR-Bolometer Formula 

where 

• T_i is measured instrument temperature
• V is voltage measured by pyrgeometer sensor and K is a sensitivity coefficient
• E is heat flux measured by a bolometer thermal link.

The Bolometer Formula is obtained from Stefan-Boltzmann's Law 

•  E = sigma (T_a^4 - T_i^4)

where sigma = 5.67 x 10^-8 is Stefan-Boltzmann's constant, T_a is the bolometric temperature obtained by calibrating the bolometer against a blackbody. Defining OLR = sigma T_a^4 gives the Bolometer Formula with OLR representing the heat flux from the atmosphere into outer space as stated. 

OLR as reported by ERBE and CERES based on the OLR-Bolometer Formula is thus the heat flux from the Earth with atmosphere into outer space based on Stefan-Boltzmann's Law, and as such represents real physics: The Earth + atmosphere transforms shortwave heat energy received from the Sun into longwave heat energy which is returned to outer space as OLR.  This makes sense as true real physics.

We now turn to DLR, which we know by previous posts represents the BIG BLUFF of CO2 alarmism: The DLR-Pyrgeometer Formula seems to be an analog of the OLR-Bolometer Formula and the BIG BLUFF is now to argue that since the OLR-Bolometer Formula makes sense as an expression of Stefan-Boltzmann's Law, also the DLR-Pyrgeometer Formula makes sense. But this is not true!

The DLR-Pyrgeometer Formula is supposed to be an algebraic reformulation of  

• sigma (T_a^4 - T_i^4) = V/K with DLR = sigma T_a^4,

where sigma (T_a^4 - T_i^4) is the heat flux between the atmosphere at temperature T_a and the pyrgeometer at T_i  > T_a according to Stefan-Boltzmann's Law, as measured by the (negative) voltage V. The BIG BLUFF is to give the algebraic reformulation a physical meaning with DLR = sigma T_a^4 interpreted  as the heat flux from the atmosphere to the Earth surface. But this is not the physics:

• sigma T_a^4 is heat flux from a blackbody into outer space at 0 K.
• sigma T_a^4 is not heat flux from the atmosphere to the Earth surface because there is no such heat flux because T_a <  T_i.

We can see through the BIG BLUFF of CO2-alarmism with DLR as heat flux from the atmosphere to the Earth surface with a warming effect:

DLR is computed from a non-physical DLR-Pyrgeometer Formula which is deceptively similar to a physical OLR-Bolometer Formula, and the BIG BLUFF is to say that because OLR is real so is DLR and global warming. 

The BIG BLUFF of DLR is

• cleverly constructed with a clever mixing of OLR and DLR 
• cleverly covered up in technical documents presenting the non-physical DLR-Pyrgeometer Formula as a version of the True Stefan-Boltzmann's Law, which expresses one-way heat flux from warm to cold,  
• hiding that the DLR-Pyrgeometer Formula represents a False Stefan-Boltzmann Law expressing two-way heat flux with in particular heat flux from a cold atmosphere to a warm Earth surface in violation with the 2nd Law of thermodynamics.      

Global warming alarmism is based on DLR demonstrated by instrumental evidence as a scientific evidence of warming from "greenhouse gasses" including the trace gas CO2. But this is fabricated evidence without physics reality and so it is a BIG BLUFF. 

It is not hard to see the bluff once you understand where to look and not get diverted away from what is really happening when the trick is performed.