Settled Science: Clusters of small satellites could help estimate Earth's reflected energy

From M.I.T. and the “Total outgoing radiation is actually one of the biggest uncertainties in climate change” department:

Batches of shoebox-sized satellites could improve estimates of Earth’s reflected energy

Clusters of four or more small satellites could look at a single location on Earth from multiple angles, and measure that location's total reflectance with an error that is half that of single satellites in operation today, an MIT-led study suggests. CREDIT Courtesy of the researchers (edited by MIT News)

Clusters of four or more small satellites could look at a single location on Earth from multiple angles, and measure that location’s total reflectance with an error that is half that of single satellites in operation today, an MIT-led study suggests. CREDIT Courtesy of the researchers (edited by MIT News)

A team of small, shoebox-sized satellites, flying in formation around the Earth, could estimate the planet’s reflected energy with twice the accuracy of traditional monolith satellites, according to an MIT-led study published online in Acta Astronautica. If done right, such satellite swarms could also be cheaper to build, launch, and maintain.

The researchers, led by Sreeja Nag, a former graduate student in MIT’s Department of Aeronautics and Astronautics (AeroAstro), simulated the performance of a single large, orbiting satellite with nine sensors, compared with a cluster of three to eight small, single-sensor satellites flying together around the Earth. In particular, the team looked at how each satellite formation measures albedo, or the amount of light reflected from the Earth — an indication of how much heat the planet reflects.

The team found that clusters of four or more small satellites were able to look at a single location on Earth from multiple angles, and measure that location’s total reflectance with an error that is half that of single satellites in operation today. Nag says such a correction in estimation error could significantly improve scientists’ climate projections.

“Total outgoing radiation is actually one of the biggest uncertainties in climate change, because it is a complex function of where on Earth you are, what season it is, what time of day it is, and it’s very difficult to ascertain how much heat leaves the Earth,” Nag says. “If we can estimate the reflectance of different surface types, globally, frequently, and more accurately, which a cluster of satellites would let you do, then at least you’ve solved one part of the climate puzzle.”

Nag, who is now a research engineer at the Bay Area Environmental Research Institute, NASA Ames Research Center, and NASA Goddard Space Flight Center, has co-authored the paper with Oli de Weck, an AeroAstro professor at MIT; Charles Gatebe of NASA Goddard Space Flight Center; and David Miller, NASA Chief Technologist and the Jerome C. Hunsaker Professor in AeroAstro.

A 3-D view

Nag says that to accurately estimate the reflectance of any ground spot on Earth requires measurements taken of that spot from multiple angles at the same time.

“The Earth does not reflect equally in all directions,” Nag says. “If you don’t get these multiple angles, you might under- or overestimate how much it’s reflecting, if you have to extrapolate from just one direction.”

Today, satellites that measure the Earth’s albedo typically do so with multiple cameras, arranged on a single satellite. For example, NASA’s Multi-angle Imaging SpectroRadiometer (MISR) instrument on the Terra satellite houses nine cameras that take images of the Earth from a fan-like arrangement of angles. Nag says the drawback of this design is that the cameras have a limited view, as they are not designed to change angles and can only observe within a single plane.

Instead, the team proposes a cluster of small satellites that travel around the Earth in a loose formation, close enough to each other to be able to image the same spot on the ground from their various vantage points. Each satellite can move within the formation, taking pictures of the same spot at the same time from different angles.

“Over time, the cluster would cover the whole Earth, and you’d have a multiangular, 3-D view of the entire planet from space, which has not been done before with multiple satellites,” Nag says. “Moreover, we can use multiple clusters for more frequent coverage of the Earth.”

Estimating error

Nag and her colleagues simulated formations of three to eight small, orbiting satellites, and developed an algorithm to direct each satellite to point to the same ground spot simultaneously, regardless of its position in space. They programmed each formation to measure a theoretical quantity known as bidirectional reflectance distribution function, or BRDF, that is used to calculate albedo and total outgoing radiation, based on the angles at which measurements are taken and the angle of the sun’s incoming rays.

For each formation, Nag calculated the satellites’ error in measuring BRDF and compared these errors with those of the MISR instrument on the Terra satellite. She validated all errors against data from the NASA Goddard’s Cloud Absorption Radiometer, an airborne instrument that obtains tens of thousands of angular measurements of a ground spot. She found that every formation with seven or more single-sensor satellites performed better than the nine-sensor monolith satellite, with lower estimation errors. The best three-satellite clusters generated half the error of MISR’s estimates of albedo. The accuracy of overall estimates improved with the number of satellites in the cluster.

“We found that even if you can’t maintain your satellites perfectly, the worst-case error is less than what the single satellite is able to do,” Nag says. “For the best-case scenario, if you are more than halving the error that you currently get, you’re halving the amount of error you would get in reflected heat leaving the Earth. That’s really important for climate change.”

“This work is significant not only for demonstrating the capability for instantaneous multiangular BRDF measurements from space for different land surface types and biomes, but also for establishing a strong methodological bridge between the systems engineering of future small satellite clusters and high fidelity Earth science simulations,” de Weck says. “Our team fully expects that a demonstration mission of this type could be flown within the next decade.”

While multisatellite formation flights have been deemed expensive endeavors, Nag says this assumption mostly pertains to satellites that need to maintain very strict formations, with centimeter-level accuracy — a precision that requires expensive control systems. The satellites she proposes would not have to keep to any single formation as long as they all point to the same location.

There’s another big advantage to monitoring the Earth with small satellites: less risk.

“You can launch three of these guys and start operating, and then put three more up in space later — your performance would improve with more satellites,” Nag says. “If you lose one or two satellites, you don’t lose the whole measurement system — you have graceful degradation. If you lose the monolith, you lose everything.”



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NZ Willy

You mean we should litter nearby space with space junk, on purpose? For no significant gain? Tell me people aren’t actually thinking this.


It isn’t junk if it is doing something useful.

For no significant gain?

Did you read the article? They would halve the error.


An error cut in half . . . would still be an error.

send Obatard to the Russian space station. he can then wet his thumb and stick up his arse. if were going to trash the heavens start with something we will not miss upon reentry.


What? No, wait, like, the science is, like settled. Why are we now questioning the reflected energy? The assumed value was factored into all the models. My brain is throbbing. Anyone see “Scanners”?

Evan Jones

An error cut in half . . . would still be an error.
There is error in any measurement. Even the breathtakingly beautiful CRN is subject to error.
Reducing MoE by a half in this case would be a very good thing. It would test Lindzen’s work. I would like to see those results.

“What? No, wait, like, the science is, like settled.”
huh? read the IPCC.
let me help you.
1. GHGs increase the opacity of the atmosphere to outgoing LWIR. settled
2. Humans add GHGs to the atmosphere: settled
3. INcreasing the opacity to LWIR will slow the rate cooling ( ie “warm” ) the planet.
the simple way to think of this is too consider how a thermos keeps your cofffee
warmer than it would be otherwise.. it doesnt warm the coffee it slows the cooling.
what is unsettled or subject to uncertainty?
How much warming.
“the science” is a vague reference. try to avoid that.


We’ve littered LEO (Low Earth Orbit) for decades with junk that has far less purpose.

Besides, the accuracy claim only applies to single pixels. If what matters is the whole field, which is all that matters, for the purpose of establishing the planets energy balance, other pixels will pick up the energy reflected off the perpendicular, especially when measurements are made from a few geosynchronous weather satellites which each has a continuous view of half the planet supplemented with data from polar orbiters.

James Bull

My thought on this is that it would reduce incoming radiation as near earth orbit would be littered with large numbers of these satellites.
James Bull


stick a temp gauge on the moon pointing back at earth.
would this work ????

george e. smith

measuring the earth albedo doesn’t tell you anything about how much heat the planet reflects.
The earth’s oceans absorb about 97% (there’s that number) of solar spectrum energy, and they reflect something close to that of Infrared radiation, so getting the albedo correct leaves you up a creek on measuring the IR reflectance.
You could of course directly measure how much heat the earth reflects.

Modeled that many small satellites are better than one large. GIGO.
I place the need for such measurements as very low on the rational scale, deep into irrational levels.
A desire to use expensive to launch space clutter to measure reflectance solely for albedo ranks right up there with narcissistic mirror watching.

john harmsworth

This may make sense depending what the error is presently. If it is significant then it will be better to spend the money and effort to qualify the data rather than TRILLIONS to mitigate a problem based on unverified worst case scenarios.I have been wondering about this for some time. Next we will hear from the Alarmists that the science is settled and verifying the data would be a waste of money! I suspect they don’t want to know what better satellite data would say.

There is independent evidence from recent studies of variation in albedo.
“A major change in albedo occurred between the early earthshine measurements and the more recent ones (Fig. 4). For the 1994/1995 period, Palle´ et al. (2003) obtained a mean albedo of 0:310 +/-0:004, while for the more recent period, 1999/2001, the albedo is 0:295 +/-0:002 (with a 0.6% precision in the determination). The combined difference in the mean A between the former and latter periods is of 0:015 +/-0:005, assuming the 1994/1995 and 1999/ 2001 uncertainties are independent. This corresponds to a 5% +/-1:7% decrease in the albedo between the two periods.”
Goode, P.R. and Pallé, E., 2007. Shortwave forcing of the Earth’s climate: Modern and historical variations in the Sun’s irradiance and the Earth’s reflectance. Journal of Atmospheric and Solar-Terrestrial Physics, 69(13), pp.1556-1568.
The latest paper by Palle is
Palle, E., et al. “Earth’s albedo variations 1998–2014 as measured from ground-based earthshine observations.” Geophysical Research Letters (2016).
In my opinion, the group restricted the time span in order to get published. But that is just an opinion.

Clyde Spencer

The problem is that albedo is a good proxy for only diffuse reflectance — something that approaches Lambertian reflectance. With more than 71% of the Earth’s surface reflecting specularly, any measurement of albedo underestimates the total reflectance because the specular reflectance increases with the angle of incidence. Albedo essentially measures the apparent reflectance only back towards the sun. However, significant quantities of light are reflected in other directions, hence the need to derive the BRDF and to measure the specular reflectance away from the sun.
Another issue is that other celestial bodies have only inorganic surfaces whose reflectance is controlled by the complex index of refraction and particle size. On Earth, red and blue light tends to be used to grow plants rather than heat the surface. That has to be taken into consideration in any estimate of energy balance.


Looks like we are trying to create the worlds sattelitejunkosphere whereby all incoming light is reflected back into space by the very things that are trying to measure it below. Should cool things off a bit. Suppose we could make a “hole at the pole” to let some light in.


The crowded skies would very much depend on the altitude and inclination of these “swarms” as well as the delivery method. The skies aren’t crowded with satellites as much as they are infested with the flotsam and jetsam associated with transportation and deployment of orbital hardware. BTW we don’t have enough materials here on earth to build enough satellites to block the sun.


Whew, thats a relief.

Dr. Dave

Don’t forget the debris from the collision of a Russian satellite with an Iridium satellite and the aftermath of the Chinese destruction of a satellite using an ASAT weapon

Colisions ought to give many bits with eccentric orbits and rapid drag decay, and some with stable orbits. Then the cooler sun lowered air drag from lower atmospheric height. So many more of those bits survive…
So how much does the lower drag increase space junk lifespan and reduce space access and safety?
We’re rapidly increasing the risk to launches and at some point not too many years of launches in the future space will be hard to reach… How do we clean up the junk then?
FWIW, my approach would be a satellite that gets in front of some junk and decelerates it with a blast of gas so it deorbits…

How precise are the multiple sensors at reading the same “spot” on earth, and how big is that spot? Is the spot 10′ x 10′ or 1000′ x 1000′? If the former, could the directional algorithm be useful in making a space-based Tonopah solar array?

Bruce Cobb

“Nag says such a correction in estimation error could significantly improve scientists’ climate projections.”
Translation: It will give them more wiggle-room to tweak their fundamentally-flawed models.

george e. smith

Well she has a good name for the job.
I’m sure you can put up 60 swarm satellites in a bucky ball orbit. and they will just stay in that configuration forever.
Well then you can turn the bucky balls into a great stellated dodecahedron configuration which would give you 72 satellites all staying in the same geometry.
Can you just imagine the energy it would take to keep a 72 satellite constellation of satellites in a stable stationary orbital structure around the planet.
You should try putting up one geostationary satellite, and then when you figure out where to put another one in geostationary orbit, that remains at a constant distance from the first one, then at that point you can figure out where #3 has to go.
I’ll be asleep most of the time that you are putting up however many you decide to put in the same plane around the earth.
I’ll be wide awake the moment you start putting them out of that plane. That is something I just have to see for myself.

Clyde Spencer

If you put satellites in geostationary orbits, the sensor optics will have to be steerable to get reflectance measurements at different viewing angles. Also, geostationary requires equatorial orbits so you can’t get readings near the poles. That is a critical limitation because the ground materials vary with latitude.


If they don’t get the answer they want, they’ll adjust the data, anyway.

Was thinking the same thing. After all, NASA is the ‘government’ and this would be great if the data is not altered/adjusted.


but, but… I’ve seen Trenberth’s graphs.. They already know the answer to one dp. !

I wondered whether this improvement was important. After some searching, found a quite thorough discussion on remote sensing of albedo by Maurer at U. Hawaii Manoa. He says climate models need accuracy of +/- 0.02 to 0.05. Says the best current satellites do about +/-0.06.
So yes, the improvement in accuracy would be important, and no the science is not settled.
Current best estimate of TOA radiative imbalance is 0.6+/-0.4. (stephens 2012) Never good to have an error range almost as big as the central estimate for a fundamental of GHE.

john harmsworth

Thank you Ristvan
That is the argument for doing this-in a nutshell. We should all be behind this. Assuming they will publish the raw data!


‘So yes, the improvement in accuracy would be important, and no the science is not settled.’
If you assume there is a problem that needs addressing.

Pat Frank

It’s 0.6(+/-)4, R. There’s a decimal error in the rms calculation in Stephens 2012. Take a look.

I will. TY

Wim Röst

A 3-D view. I suppose this will improve our knowledge of the reflectance of the different types of clouds.


What is Gore Sat doing now?

is this a surprise
El Nino patterns contributed to long-lived marine heatwave in North Pacific
I assume not.

Clyde Spencer

I think that the researcher is overly optimistic that a single sensor would suffice. On the daylight side, a visible-light panchromatic sensor might suffice. However, on the dark side, a thermal IR sensor with much higher sensitivity than the panchromatic sensor would be necessary to measure the re-radiated energy, which is part of the overall energy balance. The Earth’s surface is >71% water, which primarily reflects specularly, unless there are significant white caps. To measure the specular reflection, the satellites have to be viewing the surface in a plane that includes the satellite, the surface, and the sun, and at several different angles. If the satellites are not viewing in the plane of incidence, then the estimates will be very low. The satellites will also have to have large differences in time because the visible-light reflectance of water can vary from about 2% in clear, tropical waters directly under the sun, to 100% inside the Arctic Circle. However, if the satellites aren’t viewing in other directions, for things that have diffuse reflectance (i.e. snow, sand, and clouds especially), then the estimate of the total will also be low. I’m not sure how her proposal would be superior to MISR. We probably need at least three satellites equivalent to MISR with polar, oblique, and equatorial orbits to improve our understanding of total reflectance (Not albedo; the astronomical term albedo is commonly used inappropriately.).

CS, you may be confusing albedo with TOA radiative imbalance. The former is simply reflected incoming short wave radiation (SWR), mostly visible light frequencies. Only ‘sunny side’ by definition. The latter is incoming SWR minus reflected outgoing SLR minus outgoing longwave radiation (OLR, infrared) which happens both sunnyside and dark side, integrated across the full 24 hour day, by latitude. So for a better estimate of albedo only, SWR sensor suffices.
The current satellites do TOA imbalance by monitoring all three on one platform.. The MIT proposal is to do albedo separately, and the TOA imbalance calculation on the ground. Theoretically OLR also has the satellite aperture problem, so dunno how much albedo alone would improve the delta TOA measurement.

Clyde Spencer

No, I’m definitely NOT confusing albedo with TOA radiative imbalance. First off, albedo is an apparent brightness of celestial bodies, which is the result of diffuse reflectance. The total reflectance of Earth is greater than the apparent albedo because an observer has to be in the right position to also capture specular reflections from water and ice. (Actually, even snow has a strong forward scattering that varies with the compaction and the angle of illumination.) Also, high clouds can scatter light outside the FOV of orbital sensors (See also remarks in last paragraph.). What the researcher was addressing was determining the total reflectance of the sunlit side of Earth, which requires determining the BRDF of each and every unique type of reflector, for different angles of illumination, and hopefully, also capture the specular reflection component.The ultimate goal is to use that information to determine the TOA radiative imbalance. However, to do it properly, the thermal IR should be measured on both the sunlit and dark side of the Earth. The sunlit side has a minuscule amount of thermal IR compared to visible light. If it is measured accurately, the IR radiating from the dark side can be used as a lower-bound, first-order estimate of the IR on the sunlit side. Now, to minimize potential errors, the sensor used for the dark side of Earth should have an identical FOV, and the same altitude, the same period of return, and hopefully, a quick followup on the readings taken on the sunlit-side. That is, a nominal orbit of 90 minutes between sunlit and dark side. In other words, a single sensor (assuming it is pointable) could determine the detailed reflectance of the sunlit side of Earth. However, to make that information more usable, there should be a second sensor, pointing directly downward, and characterizing the radiated IR, and being able to identify clouds on the dark side.
The problem has a second-order issue in that the radiated IR would be leaving at a normal to the surface of the radiating body. That means outward along the Earth radius for water bodies. For mountain ranges, that means normal to the rock surfaces, which will be oblique to the Earth radius. Similarly, for clouds, in that the IR should be normal to the bulk, meaning that for a cumulus and especially cumulonimbus clouds, significant amounts of IR will be radiated in directions other than normal to the Earth surface. So, a sensor looking directly downward might miss significant radiative emanations from irregular cloud masses. Even though it might be outside the FOV of the sensor, it can still escape the atmosphere if it is less than 90 degrees from the normal to Earth’s surface.

george e. smith

I think you have a glitch there. Thermal emitters of BB like radiation are Lambertian radiators. That is the radiance of any spot on the surface is constant, independent of angle so I(theta) = I(0)cos(theta). They do not radiate just normal to the surface. if the surface is rough enough so that wavelength sized surface elements can have sizable tilt angles, then the radiation pattern can approach isotropic.
A perfectly isotropic radiator is NOT possible. (Can’t satisfy Maxwell’s equations for the boundary conditions.

Clyde Spencer

I think you intended your comment for me instead of ristvan. Yes, a black body radiator should be radiating uniformly in all directions, i.e. Lambertian. But consider an IR sensor looking downward with a narrow FOV. If it sees a horizontal surface, it will record a flux that is representative of the emitted IR for all points. What happens if it is looking at a spot on the ground that is a vertical cliff? Will it see a representative flux that is characteristic of the temperature of the cliff, or the temperature of the ground or water at the base of the cliff?

“The researchers … simulated the performance of a single large, orbiting satellite with nine sensors, compared with a cluster of three to eight small, single-sensor satellites flying together around the Earth.”
“simulated the performance” – there ya go!
From the surface perspective, an object ‘reflects/radiates’ SW energy omnidirectional (horizon-to-horizon). I don’t see how expanding the cone of observation from a single point to maybe few 10/100 km across is going to make that much difference.

john harmsworth

The Warmists presently use inaccurate data as justification for their position. Why wouldn’t we want better data when, as Ristvan ouitlines above, the error band is presently larger than the whole of the assumed problem?

And, just how long have the government cheats and NGOs been lying to us saying that 97% were absolutely sure the earth is retaining heat and they knew exactly how bad it was?
I’ve never seen legitimate error bars for any of their stories. They’re hidden along with the decline.
This includes the folks at fake organizations like BEST, universities, local governments, the green renewables machine and the UN (et al)
They said I should be in jail for denying their made up data concerning CAGW when I knew all along they were lying for money and power.
So out of the blue, they want me to help pay for a new system with a lot of new machines they say will now provide the correct data they so desperately need to save us from ourselves.
I didn’t believe their lies before and I don’t believe them now.
They don’t know the earth’s true temperature nor do they know how earth’s climate really works, period.
Just a lot of bad guesses for lots of taxpayer money and we don’t even get the data we paid for… go figure.

Also, data download from a single platform requires you to track & follow that platform across the sky w/ hi-gain antenna to get a large enough signal to receive/process error-free data. Tracking & downloading data from a cluster of platforms will be…difficult at best.

Greg Woods

I think it would be much easier if we just legislated a number. It would give Sen. Whitehorse something to do besides bothering us D’iers…and save on all that space junk…

george e. smith

I think that legislating a value of three for Pi would be a good start to simplifying things.

Ian Macdonald

Make it four, that allows for inflation.

Pamela Gray

The assumption is that short term reflectance, or short term anything, can predict something into the future 50 to 100 years. The only way out of this quagmire is to think millennial oscillator, and short term random walk.

john harmsworth

I hear you Pamela but the political problem is happening now and the lousy data supports the other guys position.This is the definitive info as far as I’m concerned. If it says there is no imbalance right now, how do the Warmists respond to that? We can say quite directly, with data, that the models are wrong and fail to account adequately for energy loss-as measured. I think that would be game over, though I’m sure they would wriggle on the hook for some time.

If it says there is no imbalance right now,

It’s likely imbalanced effectively all the time.
Consider how unequal surface temperatures are due to surface topology, then half the surface is in the sun, the other half is in the dark, but the length of day/night is different from pole to pole.
You would have to capture the entire planet 24x7x365 and you would still be off because of the variations are not symmetrical.
Let alone we can’t even measure it accurately.

Interesting discussion. I wonder if NASA will actually use more accurate data, or just adjust it to fit the model.


Hmm, whatever happened to that CO2 measuring satellite ?
Has NASA conveniently “adjusted” it yet ?

Clyde Spencer

I find it interesting that almost nothing is coming out about what OCO-2 is finding. There was an an initial announcement at AGU shortly after its launch. It didn’t seem to support the paradigm of industrial emanations, with significant CO2 observed over the Amazon Basin, and CO2 ‘hot spots’ in the ocean. The data are available to the public, but it isn’t that easy to work with. I have looked at some of what is available at the JPL website, and even more recent data doesn’t support the story line. That is probably why there hasn’t been any hoopla over what this expensive satellite is telling us.

john harmsworth

Maybe I’m a sucker, but I think better data is better data. By the time this is published, NASA will be under a different administration. I definitely believe it has been politicized under Obama to a shocking extent. Even Hillary is not as beholden to the ecoloons of her party as he is. Trump will pretty obviously just want to know where space is and where would be a good place to build a resort where girls with big boobs can go to be tremendous.


Debbie does the Dallas BEAM?

Tom in Florida

The caveat is the words “If done right. Hell, if everything about climate was done right we wouldn’t be so concerned with this.

Tom in Florida

Sorry forgot to close the ” after right.

Bloke down the pub

Let me guess, when they get the new measurement, it’ll be worse than we thought.


Data? We don’t need no steenking data. We got models.
Given the increased cosmic ray activity, it may be important to have more accurate Earth Radiation Balance than we currently do. I would regard these as a step in the right direction.


“You can launch three of these guys and start operating, and then put three more up in space later — your performance would improve with more satellites,” Nag says. “If you lose one or two satellites, you don’t lose the whole measurement system — you have graceful degradation. If you lose the monolith, you lose everything.”

That’s an excellent argument, but I’m only aware of a few of the older monolith satellites that have bit the dust. Still, as the old satellites age and decay, this array of coordinated sensors sounds like a better idea for replacement instead of shooting up another “more of the same.”
If one of these shoe boxes in an array bites the dust, how hard would it be to launch and maneuver a replacement shoe box into place? If we’d need to launch another array of shoe boxes to regain performance, then inside of a few years the “launching space junk” criticism might be relevant.

Clyde Spencer

A ‘shoe-box” can’t store much fuel for maneuvering or pointing a sensor. That is another reason I’m dubious about the value of ‘shoe-boxes’ over something like MISR.

Clyde Spencer

I would say that most of the observational satellites that have made it into orbit have far out-lived their design life.

george e. smith

Just fire a whole flock of Go-Pro cameras out there, and let them photograph what they see.


Why don’t they just monitor inbound reflected energy on cloudless nights?
If that doesn’t rise with CO2, then it’s yet another nail in the coffin for the CAGW “settled science”

Geoff Sherrington

This is highly misleading re accuracy.
It is currently not possible to state the accuracy of existing systems. Most of the discussion is about precision, which is not accuracy, and where accuracy is used it refers to lab performance and not to operational accuracy in orbit. The lab doesn’t simulate orbital performance.
The usual way to measure accuracy is to make appropriately similar measurements using equipment operating on different principles, leaving to a study of the differences.
It is ludicrous to assert that a new idea will halve the error when the present error is not known ( hence the suggestion for improvement with a swarm).
More poor science from climate workers. It is endemic



Plants grow by converting the energy of the sun into making sugars and starches. So if plants are growing, then the sunlight balance will be skewed to show more absorption on the surface. BUT, the energy used to make the carbohydrates is NOT energy available for heating the world.
Maybe all that extra greening of the world is actually cooling it.

Clyde Spencer

It is an important point that red and blue light is absorbed by plants and primarily sequesters CO2 and builds plant material. That is a reason that a single panchromatic sensor is less desirable than a three-band sensor. But, if the absorbed red and blue light isn’t heating the plants, that would be evident in the IR emanations that should be taken simultaneously with the light reflectance.


How about somebody with an hour up their sleeve researches how much additional plant material, (kg), the world is growing each year, multiplies that by the energy required to produce that mass, (W/kg), to see if that is enough to stop warming, eg more than a few W/m2.

Twice the accuracy! – half the error! – no figures!
They Current global energy uptake rate has been estimated to about 0,6 W/m^2.
Unless these satellites will measure both the outgoing effect and the incoming effect with an uncertainty of less than 0,1 W/m^2 @ 95% confidence level, and no significant systematic errors, these scientists should not be allowed to play with their extremely expensive pet toys for money which can be used to solve real problems for real people.
“Earth’s energy imbalance
If the incoming energy flux is not equal to the outgoing thermal radiation, the result is an energy imbalance, resulting in net heat added to or lost by the planet (if the incoming flux is larger or smaller than the outgoing). Earth’s energy imbalance measurements provided by Argo floats detected accumulation of ocean heat content (OHC). The estimated imbalance was measured during a deep solar minimum of 2005-2010 at 0.58 ± 0.15 W/m².[11] Later research estimated the surface energy imbalance to be 0.60 ± 0.17 W/m². ”
Wikipedia: Earth’s energy budget
And the scientists should loose something valuable to them if they underestimate the uncertainty and miss.
“In God we trust; all others must bring data.” W. Edwards Deming

Nooooo! You know what happened with those temperature measuring satellites and the ARGO buoys—the nasty things refused to agree with models. If these satellites don’t cooperate……


SpaceX is planning to disrupt the industry with a 4000 satellite constellation. Launch costs are decreasing sharply. It isn’t clear to me whether Sreeja Nag’s small project could piggyback on SpaceX’s constellation or if it would need its own launch. In any event, the project is becoming more feasible with every passing day.

charles nelson

My biggest fear is that the number of satellites up there, measuring the incoming radiation will reach such a number that they begin to reflect that radiation back into space.


Trust us, we’re “Scientists”. Nothing can go wrong, (click) can go wrong (click) can go wrong………


I find science amazing…
When you can’t measure something accurately….but can accurately know the range of error


What price accuracy?
I could envision swarms of pico satellites, about 1 cc, which are configured with solar arrays and a small nano battery as well as a solar sail and nano actuators. They would communicate sensor data to a local mother and on down the line to the home office.Several million with various sensors dispersed in various orbits. Also throw in a self destruct atomizer if they need to be removed for transit…
Did I miss anything?


The article is completely spot on. I’m totally baffled at “why didn’t anyone think of it before”.
The earth reflectance is indeed irrelevant if it’s measured directly below the satellite. The only decent approximation would be to measure the point that reflects the sunlight on the surface of earth, but the reflectance function is outgoing through the whole hemisphere from any point of earth’s surface. About halving the error, well, it depends where the satellites are.


How much will this thing cost? And is it worth that price? Perhaps the money could be spent better on Earth or perhaps a permanent Moon base. As others have said, if they don’t like the data, then it will be ignored anyway.

Cube sats are cheap. Many hobbists have launched them. hmm I think over 130 hobbists got rides, many failed, but they got a ride.

Paul Penrose

Hey, at least they are talking about actually measuring something instead of just modeling it. This is a step in the right direction! And since they would be in low altitude orbits, they would not be up there a long time. Probably just a few years before they reentered. So they don’t have to be designed to last a long time, are small, so they are (relatively) cheap to build. Launch costs are lower because of the light weight and low altitude orbit. And with players like SpaceX pushing launch costs down, this may actually be a good idea.

all measurement includes modelling.


I’m a nobody who had read about these matters for about a decade, and there is this idea that has at times rattles around in my ignorant skull . .
Water molecules at the edge of space, being “aligned” into sheet-like thin layers, sometimes, by magnetic fields, which creates a slight “sheen”, sometimes, deflecting some light in some places . .
So, please abuse me of my affliction if it’s silly, experts ; )


So what? Why do we need to know something to that accuracy when it is not something in our control. We should be content with decent readings and let nature do its thing. It is hubris to think that we have control of the climate. What egotists we have in our power positions.

of course it is under our control.
For example. emitting c02 causes the planet to green as skeptics have argued.
Greening the planet changes albedo.

Johann Wundersamer
Johann Wundersamer

“You can launch three of these guys and start operating, and then put three more up in space later — your performance would improve with more satellites,” Nag says. “If you lose one or two satellites, you don’t lose the whole measurement system — you have graceful degradation.”
Oh well.


Lots of negativity here on this idea…but, in general, I’m supportive of efforts to improve empiricism in climate science. We all (mostly) agree that there’s too much computer modeling being done in lieu of actual observations, and too many untested assumptions being used without question. Plans and ideas to reduce the number of untested assumptions and gather more observations / data should be encouraged.

of course there is negativity. the reason is simple. nobody here is actually interested in improved observation.

Clyde Spencer

You said, “nobody here is actually interested in improved observation.”
It is strange that you would make such a statement in reply to Rip when he said, “I’m supportive of efforts to improve empiricism in climate science.” Did you not read his comment before replying?
I believe from what I read that there are others who similarly would like to see improved observations. However, I won’t attempt to speak for them.
Your statement about “nobody” is categorically false. I’m interested in improved observation because I think it is woefully inadequate. One of the problems is that many involved in the field are not the classic disinterested observer. Instead, they have already decided what the problem is and focus on finding confirmatory’ evidence.’

Steve Fraser

Before this, I think sensor at L2, looking at the ‘dark side’ of the earth, would get us a lot closer approximation.

Pamela Gray

No amount of accuracy or precision determines cause and effect. The only thing that these satellites can measure is an effect of a proposed plausible set of drivers. one of which serves as the null hypothesis. It must also be the case that both the null and proposed driving mechanism must be plausible and undergirded with sufficient research to make them plausible. Natural intrinsic oscillation has not been subjected to enough research to rule it in or rule it out. Therefore any extrinsic to natural variation “added” driver must be held suspect. Which is why I am skeptical of both solar and anthropogenic greenhouse gas drivers.

unicorns have not been ruled out.
My null is simple. Invisible unicorns cause the warming. falsify that null.

Svend Ferdinandsen

I wonder if the hight of the radiation is taken into account. The radiation from a hight of 3km have 1 thousends more surface and will then radiate a bit more energy than the ground.
It is small amounts, but the TOA difference is in the same order.

A friend of mine here on the Front Range , Jack Rudd , was one of the implementers of the space debris database in APL tracking every object over about 10cm . Had less than 10k items some time ago .
While the equation for the equilibrium temperature of a ball with an arbitrary absorption=emission spectrum , I’d be inclined to call it the Kirchhoff spectrum except several others deserve equal recognition , or even a spherical map of spectra , ie : color , heated by an arbitrary power spectrum is quite simple , measuring the ae spectrum clearly is not . This is something I would really like to see some details on how its done from some of the people spending their lives doing it .
The specs of the Multi-angle Imaging SpectroRadiometer (MISR) , , mentioned are a quite informative overview . I find it interesting that the “Temperature of main structure: +5 degrees C” is very close to our calculated gray body orbital temperature .
BTW : my recent Hangout with the Silicon Valley Forth Interest Group demonstrating how more usable by ordinary humans 4th.CoSy is getting , and the invitation to this year’s MidSummer Party are linked at the top of .

The Dude of Voo

Once again, to the studious reader of technical papers, regarding “Climate Science” … the required accuracy of measurements is grossly insufficient to support the conclusion that the Earth is retaining heat due to Mann-kind’s CO2 emissions. Trenberth and pals said the Earth was retaining about 0.9 Watts per square meter. Hansen, at first, said 0.85 Watts/m^2, and later, 0.58W/m^2. Stephens 2012 said 0.6W … Allan 2014 said 0.34 W/m^2 and 0.62 W for another time period. Apparently, the “consensus” determination is that the measure of “Global Warming” is bigger than half-a-watt, but less than a whole watt. Per meter squared, of course … or ¾W/m^2
Here, Nag et al. 2016 proposes an array of cube-sats, as opposed to the traditional method of one satellite, to measure the Earth’s albedo. Mostly, this allows for a broader capture area, since the reflectance of the Earth has serious angular differences that get missed by the traditional single-satellite sensor. Kimes and Sellers 1985 points out that most natural surfaces are not isotropic, and errors in the angular distribution of albedo can reach as high as 45%. Strugnell & Lucht 2001 quantify the absolute errors in albedo retrieval in the visible light spectrum, are approximately ±1.5% and absolute errors, in the NIR, and total shortwave, are ±3%.
A 3% error in albedo translates to about 4W/m^2; a 1.5% error is about 2W/m^2, according to Nag 2016. Compare that to the ¾W/m^2 magnitude of “Global Warming”.
”An albedo error of 0.001 [0.1%] translates to 1.36 W/m^2 in Earth’s outgoing radiation error.”
An albedo error of 0.00055 (0.055%) translates to 0.748W/m^2, or ¾W/m^2 according to Nag 2016
Just one parameter – the Earth’s albedo – as a “budget item” in the Earth’s heat balance – has intrinsic errors in the measurement, that dwarf the size of the supposed “budget surplus”. Each and every other parameter in this “budget” has similar errors.
Quotes from some references:
Nag 2016: ”Three satellites, in some specific formations, show average albedo errors of less than 2% with respect to airborne, ground data; and seven satellites in any slotted formation outperform the monolithic error of 3.6%. In fact, the maximum possible albedo error, purely based on angular sampling, of 12% for monoliths, is outperformed by a five-satellite formation in any slotted arrangement and an eight satellite formation can bring that error down four fold to 3%.”
Nag, Sreeja, et al. 2016 “Effect of satellite formations and imaging modes on global albedo estimation.” Acts Astronautica
Strugnell & Lucht 2001: ”Early investigators proposed various methods to estimate albedo over large areas from aerial photography, airborne scanners, and satellite system [see Starks et al. (1991) and references therein] but with the exception of Kriebel (1979) these methods assumed a Lambertian terrestrial surface, a necessity due to the nadir-viewing sensors used by the investigators. This assumption is still made where albedo measurements are required, at such a fine scale, that only nadir data are available, for example, when investigating the urban heat island effect (Soler and Ruiz 1994). Most natural surfaces, however, are anisotropic diffusers of incident radiation and the Lambertian assumption can result in errors of up to 45% in the calculation of albedo (Kimes and Sellers 1985). In order to accurately retrieve albedo from remotely sensed measurements, the directional nature of the reflected radiation needs to be taken into account.”
”…estimated [bidirectional reflectance distribution function] is integrated to produce the albedo.”
”…if we are able to accurately quantify the surface BRDF, [the bidirectional reflectance distribution function,] we can calculate albedo at any solar zenith angle, and under any skylight conditions. This … allows us to predict surface albedo under cloud cover, which is not currently possible using albedo measurements from remote sensing … BRDF is not directly measurable, …”
”Expected relative retrieval accuracies for albedo are between 1.9% and 11.4% (ignoring errors in atmospheric corrections) depending on scene cloudiness, and whether one, or both instruments are used (Lucht 1998).”
”… a land cover class such as, boreal needleleaf forest, will have a [ bidirectional reflectance distribution function] that varies from one location to another … the assumption of similarity made for members of a [ bidirectional reflectance distribution function] family may no longer be fulfilled as the underlying radiation scattering mechanisms change.”
”…the use of the multiplicative factor dramatically improves the albedo retrieval, compared to using the archetypal BRDF for all pixels. For the needleleaf tree landcover type we used a PARABOLA Jack Pine BRDF as the archetype and PARABOLA Black Spruce as the test BRF dataset. The differences in albedos of the two datasets were 17.295% in the red and 19.714% in the near-infrared (NIR). By using the a factor to constrain the archetypal BRDF to the observed test BRFs we reduced this error to 12.534% in the red and 0.357% in the NIR. For dense grass we used a PARABOLA prairie BRDF (Deering and Leone 1990) as the archetype and a PARABOLA mixed grass test dataset. Errors were reduced from 49.431% to 12.020% in the red and from 61.077% to 0.546% in the NIR. The two datasets have similarly shaped BRDFs in the NIR that accounts for the small error. In the visible, however, the two BRDFs appear quite different, which accounts for the larger error. It should be noted that as albedos are usually small in the visible, even quite large relative errors result in only small changes in the surface albedo and hence the radiation budget.”
”To investigate the robustness of the algorithm, we took the archetypal BRDFs in Table 2, and varied the three weights parameterizing the BRDF by up to ±10%, mimicking the variation we might expect in a given BRDF class. We then compared the white-sky albedo of the new BRDFs with those of the archetypal BRDFs. The errors vary according to BRDF class, with the largest error seen in the visible band of the urban BRDF (class 25). When all three weights were reduced by 10% in this class, the archetypal albedo overestimated the real albedo by 30.4%; however, the constrained inversion albedo only overestimate the real albedo by 8.4%. The class 25 archetype is based on poorly sampled AVHRR data (the only urban AVHRR dataset available at the time of writing). A new urban BRDF dataset from Meister et al. (Meister et al. 1999) will be used in future work. The mean error across all classes using the archetypal albedo, to estimate real albedos, is 6.61% in the visible and 6.44% in the NIR. Using the constrained inversion errors are reduced to 0.53% in the visible and 0.48% in the NIR.”
”The errors in the visible albedo varied from 15% to 45% with a mean of 25%. To put this into perspective, a typical visible albedo of 0.05 would have an error of ±0.0125. Mean errors in the NIR and total shortwave were much lower, 11% and 10%, respectively.”
”These are, again, relative errors, and we emphasize that, as visible albedos are generally low (≪0.1), absolute errors, in the visible, are of the order of ±0.015 [1.5%]. Typical absolute errors, in the NIR, and total shortwave, are ±0.03 [3%].”
A 3% error in albedo translates to about 4W/m^2; a 1.5% error is about 2W/m^2, according to Nag 2016
Strugnell, Nicholas & Wolfgang Lucht 2001. “An algorithm to infer continental-scale albedo from AVHRR data, land cover class, and field observations of typical BRDFs.” Journal of Climate