Greenhouse Gases and Satellites

It′s seems clear to everyone, based on the latest weather developments at global level:

- Melting of Artic and Antarctic ice

- Floods in Middle East

- Massive Tornados in Mexican Gulf

- Long standing draughts in Brazil′s Amazon and Cerrado Biomes

- World′s average temperature rise

that the Climate change is a reality

Amongst the many factors that influence such changes, the Greenhouse Gases concentration at the Atmosphere is definitively one of the most influential ones as it contributes to global warming and climate change by trapping the sun′s heat and heat from other sources within the atmosphere.

Who is who on Greenhouse Gases?

Here’s a comparative overview of the top five greenhouse gases based on their abundance, source, and global warming potential (GWP):

1.Carbon Dioxide (CO?)

- Abundance: Most abundant anthropogenic greenhouse gas.

- Sources: Primarily from fossil fuel combustion, deforestation, cement production, and certain industrial processes.

- Global Warming Potential (GWP): 1 (standard reference for other gases).

- Atmospheric Lifetime: 300-1,000 years.

- Impact: Major driver of global climate change due to the sheer volume released. CO? concentration has significantly increased since the industrial revolution.

2. Methane (CH?)

- Abundance: Second most prevalent anthropogenic greenhouse gas.

- Sources: Agriculture (especially from rice paddies and livestock digestion), landfills, oil and natural gas extraction, and wetlands.

- Global Warming Potential (GWP): 28-36 times more effective at trapping heat over 100 years than CO?.

- Atmospheric Lifetime: ~12 years.

- Impact: Although methane is less abundant than CO?, its short-term impact on warming is much more significant due to its high GWP.

3. Nitrous Oxide (N?O)

- Abundance: Present in smaller concentrations compared to CO? and CH?.

- Sources: Agricultural activities (synthetic fertilizers), fossil fuel combustion, industrial processes, and sewage treatment.

- Global Warming Potential (GWP): 298 times more potent than CO? over 100 years.

- Atmospheric Lifetime: 114 years.

- Impact: Plays a significant role in both global warming and ozone layer depletion.

4. Fluorinated Gases (HFCs, PFCs, SF?, NF?)

- Abundance: Less common, but highly potent.

- Sources: Industrial processes, refrigeration, air conditioning, manufacturing of electronics, and aerosol propellants.

- Global Warming Potential (GWP):

- Hydrofluorocarbons (HFCs): GWP ranges from 100 to 12,000.

- Perfluorocarbons (PFCs): GWP ranges from 7,000 to 11,000.

- Sulfur Hexafluoride (SF?): GWP around 23,500.

- Nitrogen Trifluoride (NF?): GWP around 16,100.

- Atmospheric Lifetime: Varies significantly, from a few years to thousands of years (e.g., SF? can last more than 3,200 years).

- Impact: Though present in very small quantities, these gases are extremely potent and can stay in the atmosphere for a long time, making them a significant concern for climate policy.

5. Water Vapor (H?O)

- Abundance: Most abundant greenhouse gas overall.

- Sources: Evaporation from oceans, lakes, and rivers; human activities have an indirect effect by warming the atmosphere, which increases evaporation.

- Global Warming Potential (GWP): Variable (not easily assigned as it acts as a feedback rather than a direct driver).

- Atmospheric Lifetime: Typically short (about 9 days).

- Impact: Water vapor amplifies the greenhouse effect because warmer air can hold more moisture, which in turn leads to more warming. It acts as a feedback mechanism rather than being directly influenced by human emissions.

Each gas has a unique combination of properties that determine its overall contribution to the greenhouse effect. Carbon dioxide, for example, is less potent than other gases but far more abundant. Conversely, fluorinated gases are rare but extremely effective at trapping heat.

Speaking specifically about GHG emissions and Satellite emissions observation technologies, this article provides a brief overview of the capabilities of some current satellites with methane monitoring capabilities, as well as those planned for launch, and how they compare.

How Satellites and Greenhouse gases emissions monitoring connect each other?

MethaneSat, the newest satellite with methane monitoring capabilities was launched into space in March 2024. The launch has generated a new wave of interest in methane monitoring via satellite. The US non-profit Environmental Defence Fund (EDF) developed the satellite with the New Zealand Space Agency. The data will be publicly available for free and is designed to call out super-emitters of methane gas.

Several different types of satellites exist for monitoring different types of methane emissions. MethaneSat won’t be the newest satellite in space for long, with several more planned for launch in the next few years. This increasing data availability makes for an exciting time to investigate the opportunities these types of satellites bring for monitoring and regulating methane emissions.

Observing Methane from Space

The shortwave infrared (SWIR) part of the electromagnetic spectrum is important for the detection of methane. Some satellites are designed specifically to detect methane e.g. GHGSat WAF-P and MethaneSat, with very specific measurements in the SWIR, these are the focus of this article.

Multispectral sensors with multiple bands across wavelengths including the capture of information in the SWIR e.g. Worldview-3 and Sentinel-2 can also be used to detect methane.

Methane-detecting satellite sensors can be broadly separated into two categories:

A) Facility Scale Plume Monitors – are designed to quantify individual assets such as oil and gas facilities or landfill sites. Sensors within this category have spatial resolutions better than 1km, allowing for the identification of emitting facilities.

B) Global GHG Mappers – are designed to work at the global and regional scales to observe the total emissions. The spatial resolution on these sensors does not usually allow emissions to be linked to individual facilities. The precision and accuracy of these sensors enable them to be used to monitor methane release from natural features such as wetlands and agricultural lands. These sensors provide information for national greenhouse gas inventory development.

These are two broad categories, with a range of capabilities within each. The different types can be used in combination, using the global mappers to identify hot spots, with the facility scale monitors then able to identify emitters. A demonstrated example is at a landfill site in Madrid, investigated by SRON Netherlands Institute for Space Research and GHGSat, using a range of satellite sensors to analyse emissions.

More satellites in orbit improve the capability to image a site at a higher frequency with multiple sensors which is important for large-scale high pollution events. Though for measurements to be directly comparable more work is needed on interoperability and standardisation. The Committee for Earth Observation Satellites (CEOS) is key to this, coordinating the different operators together from across the World.

Current and Future Satellite Missions

The below graphic shows the current and upcoming methane-specific satellite sensors and the category into which they fit according to CEOS.Methane Observing Satellites accessed via CEOS Greenhouse Gas Satellite Missions Portal.

The below table provides information on a selection of the sensors currently available and planned for launch, to allow a comparison of capability, ordered by spatial resolution. The information has been taken from a combination of sources, the CEOS Greenhouse Gas Satellite Mission Portal, Jacob et al. (2002), Global Methane Tracker 2024 and the EO Portal.

This table displays some of the core information about some of the methane-specific missions’, in descending order by spatial resolution. The information is sourced from multiple locations including CEOS (1), Jacob et al. (2022) (2), Global Methane Tracker 2024(3) and EO Portal(4).

Conflicting and outdated information exists between sources and this table is a best effort to provide consolidated and updated information as of April 2024. The source referenced for each number is shown by the superscript reference. Many of these sensors are yet to be launched and so exact capabilities are yet to be tested.

The choice of the most appropriate sensor is dependent on the asset or environment to be measured and how the information is to be used. Aspects to consider and how they relate to the table include:

- The size of the area or asset

- The spatial resolution of the sensor is important as it dictates how well an emission can be attributed to a specific asset, as well as the capability to capture the entirety of the site. For example, if an anaerobic digestor of 60m diameter is to be monitored, the spatial resolution of GHGSat at 30m would be more appropriate than the 7km of a global mapper.

- How often the location is required to be imaged

The frequency of observation required is dependent on the intended use of the data e.g. regulatory spot check vs operationally leak monitoring. As well as the nature of the methane emissions e.g. diffuse long-term, vs time-bound activities. This is termed Temporal Revisit by Constellation, this column lists the best frequency with which a satellite can monitor a location, though often not achievable in practice due to weather conditions, competing demand for the sensors and budget.

- The nature and level of methane being emitted

The Minimum Detection Threshold column in the table shows the minimum detectable concentration in kilograms per hour by each of the sensors. It should be noted that this is inherently related to the spatial resolution. The detection threshold can be more challenging in adverse weather conditions.

There are further characteristics available on each of these sensors which should be taken into account when choosing a sensor such as precision and error rates.

Some of the sensors listed are yet to be launched, others have data ready to use with data available on various portals.

SENTINEL 5-P TROPOMI – CH4 Data from the public mission is available from ESA open source, through the Copernicus Data Space Ecosystem and accessible through Google Earth Engine, data is available back to February 2019.

GHGSat – Data from GHGSat can be accessed directly on commercial terms from GHGSat. UK based organisations can access GHGSat data for free through the UKSA-funded Methane Monitoring Data Supply for UK Programme running until March 2025. GHGSat data can also be accessed via ESA 3rd Party Missions Programme for registered scientific users. GHGSat have data available from 2016 for GHGSat-D, and from 2020 for its GHGsat-CX1.

MethaneSat – MethaneSat has been in orbit since 4 March 2024. Data is expected to become available later in 2024 on Google Earth Engine. The data when it is available will be open source. There is aerial data for MethaneAir available on Google Earth Engine. MethaneAir was a precursor of the satellite mission, and the data could be viewed as ‘sample data’ though the emissions models are still in development.

GoSAT – GoSAT data is accessible via ESA 3rd Party Missions Programme for registered scientific users. GoSAT has data available from 2009.

Original article and Credits: https://sa.catapult.org.uk/blogs/methane-satellite-missions-capability-comparison/

Cerrado Sustentavel Brazil, supported by Shamal Space, aims to promote the Sustainable environmental and economic exploration of the Cerrado (Brazilian Savanna) Biome, through the adoption of state-of-the-art technologies on Agro, Bio, Quantum, Digital and Space; amongst Space technologies to be adopted, we highlight the access to Earh-Observation tools PROMPTLY available by Shamal Space′s partners on Visible range, Infrared, Multispectral and Synthetic Aperture Radar Satellites; the observation of changes on Atmospheric Heating due to Greenhouse Gases build up is one of the topics being addressed by Cerrado and Shamal Space; as an agent of change, Shamal Space and Cerrado Sustentavel Brazil Project is committed to leverage the study of such phenomena, its influence on the Environment and, more importantly, which mitigatory actions to take to minimize impacts, through the adoption of EOS technologies.