The next generation of emissions monitoring satellites are coming

Professor Jorg M Hacker spends his days with his wife soaring through far flung areas of Australia in a two-seater plane.

While Hacker might sport a sun visor and sandals, this is no weekend trip. The work that Hacker and his wife Shakti Chakravarty undertake is a crucial part of a larger push to improve how Australia tracks its emissions.

When I spoke to Hacker, he was parked at a beach in Karratha, in the north of Western Australia after a big day.

“We are flying through the emission plumes of the LNG facilities in Western Australia to determine how much methane and carbon dioxide they contain,” he told me with a chuckle. “We love it.”

But this isn’t done in secret or under the cover of night.

Often not even the operators know the exact amount of emissions

Professor Jorg M Hacker

Prof Hacker is the Chief Scientist of the independent research institute ARA – Airborne Research Australia, based in Adelaide. Funded by the United Nations Environmental Programme (UNEP), Hacker and his team make sure the operators know what they’re up to well in advance.

“It’s not very productive to sneak up on them and then point the finger at them – that will probably help nobody,” Hacker told me.

“If we can objectively and independently determine the emissions … at least then that is established.

“Often not even the operators know the exact amount of emissions, at least not from independent fully traceable and quality-assured measurements.”

Magic Numbers

To understand how to cut down our emissions, we need to be able to accurately measure how much is there in the first place.

In a country like Australia, there are broadly two ways of measuring emissions. The first is the traditional method – known as ‘bottom up’ – where tonnes of coal, litres of gas, or even number of cows in a paddock, are used to estimate the amount of greenhouse gasses emitted by industry, state or whole country. These figures have been published in some form or another since the 1990s. But, this may not be the best – or only – way to track our errant gases anymore.

The second way to measure emissions is called ‘top down’. This means physically measuring the amount of methane or carbon dioxide in a column of atmosphere, and then modelling it to fit a larger area.

Hacker’s plane does this on the smallest scales – measuring plumes directly from feedlots, LNG facilities and coal mines and even garbage dumps.

On a trip like the one in Western Australia, Hacker and Chakravarty will fly the plane back and forward along a 2D plane vertically, forming what’s known as a ‘wall’.

“The aeroplanes we are flying are quite special. They use premium unleaded petrol, not aviation gasoline,” he said.  “It’s essential that the plane does not pollute the air or you would be effectively measuring the exhaust.”

The plane is something of a motorised glider – the engine is small, the wings are longer than normal, and the craft is specially designed to fly steadily and slowly through the plumes of gas. 

To make sense of the measurements, one has to know the exact wind speed and direction, the concentrations of the gases and many other atmospheric parameters, as well as the position and attitude of the plane. These are all measured up to 20-times per second.

These planes are technologically incredible. But Hacker and Chakravarty – and teams like them – can only be in so many places at once. To go broader, there is a new technology that more and more scientists are counting on to measure emissions all across the world – satellites.  

Now, things have changed quite a bit …and they are about to theoretically change much more seriously.

Professor Pep Canadell

Satellite Hotspots

Emissions monitoring instruments were first added to satellites decades ago, but according to Professor Pep Canadell – a Chief Research Scientist at CSIRO and director of the Global Carbon Project – they weren’t worth writing home about.

“Satellites have gone from – not quite useless – but just technologically being developed,” he told me over the phone.  

“Now, things have changed quite a bit – I’m being modest here, and they are about to theoretically change much more seriously.”

The original satellites could measure emissions, but they were more like a Jackson Pollock painting than an in-focus photo. Small strips of the Earth could be measured as the satellite flew past, but each ‘pixel’ could be tens of kilometres long.  It has improved considerably in recent years.

This has meant that large swathes of the planet can be regularly analysed, and areas or facilities can be zoomed in on for individual plumes.

Both planes and these next generation satellites can measure something that until recently was very difficult to pin down – hotspots.

One can measure a lot of things from a satellite, but a satellite is a very long way away

Professor Jorg M Hacker

Hotspots are areas of high emissions – usually where emissions don’t match the bottom-up reporting, lighting up on the satellite maps like a red spectre of untracked emissions.

They occur for a number of reasons. Maybe companies aren’t reporting properly, or there’s a leakage that they don’t know about. If these emissions aren’t caught, they can go undetected.

Planes, according to Canadell, are “really good at detecting those hotspots.”

When Canadell and his team create carbon budget analysis, they include both top down and bottom up reporting. The aim is to create something that reconciles both datasets.

“Not that we push things to be the same, but that we try to understand why they’re different,” he told me. 

Light shining through

To understand this, it’s worth unpacking what top down systems – like satellites, planes, or even ground based ‘column measurements’ – are actually recording.

We use a pattern of what reaches the surface to quantify what’s being absorbed through the atmosphere.

Dr Nicholas Deutscher

Known as the gold standard for emissions monitoring, column reporting uses a network of spectrometers which absorb radiation from the Sun.

“What we do is basically track the Sun through the sky,” said Dr Nicholas Deutscher, a University of Wollongong atmospheric researcher.

“But the atmosphere absorbs some of that energy. So, we use a pattern of what reaches the surface to quantify what’s being absorbed through the atmosphere, and by which particularly gasses.”

For column monitoring, the scientists record the energy as it reaches the surface.

Satellites do this a little differently. Once the energy reaches the surface, it then bounces off the ground, and travels back through the atmosphere again to hit the satellite. 

“Instead of looking up at the Sun, they look down at the surface of the Earth and the reflected sunlight,” said Deutscher.

“They get two passes of the atmosphere instead of one.”

This is then put into models with atmospheric data, temperature and a host of other information to be able to work out how much methane or carbon dioxide is spread through the atmosphere.

Satellites regularly use column measurements like Deutscher’s to confirm that the results they are getting are actually accurate. Planes like Hacker’s use finer measurements to go directly through the plume.

“One can measure a lot of things from a satellite, but a satellite is a very long way away,” said Hacker. 

“Regarding ground-based measurements, that’s fine too. But if you’re on the ground, you are in one location, and the plume is either there or it’s not.”

“We measure individual transects – we get a vertical distribution.  Also, our instruments are very well calibrated down to the PPB (particles per billion) level. They are extremely well calibrated, and nobody can dispute that what we are measuring is not correct.”

Next Generation

Unsurprisingly, all of the scientists we spoke to appreciated the other’s techniques but thought their way of measuring emissions was the best.

Column measuring is the most accurate, but it can’t move and needs people and resources. Planes can look at specific plumes, but there’s only so many planes like Hacker’s, and they can’t be in multiple places at once.

Satellites can have more errors, and they’re not as granular as planes. But with each new generation of satellite they’re getting more accurate, and able to look at emissions with higher resolution.

The Government told Cosmos a year ago: “…satellite data is not currently reliable enough on its own for emissions estimates, given technical challenges like visibility through clouds or estimates on uneven ground.”

Those well-informed about top-down emissions monitoring are incredibly excited about what’s to come.

Canadell thinks that the next generation of satellites – particularly run by non-governmental organisations (NGOs) – will be a boon.  

“MethaneSAT – this satellite comes from an NGO in the US, the Environmental Defence Fund. An NGO has gone out and developed a satellite about to launch, supposedly to be used for everyone to measure methane” he chuckles in almost disbelief.

“That’s quite formidable.”

For him, the idea of a non-governmental satellite discovering hotspots, governments then checking and updating their models is “a beautiful win-win”.