Nielsen, O.-K., Mantzius Hansen, K. & Geels, C. 2023: Kortlægning af interesser og potentialer i forbindelse med satellitdata til overvågning af drivhusgasemissioner. Aarhus Universitet, DCE – Nationalt Center for Miljø og Energi, 34 s. - Videnskabelig rapport nr. 523. http://dce2.au.dk/pub/SR523.pdf
This project has made a mapping of interests and needs associated with the use of satellite-based observations of greenhouse gases.
The report describes the current status and ongoing developments in satellite-based services including the work ongoing in CAMS (Copernicus Atmosphere Monitoring Service) and in particular with a focus on the upcoming mission CO2M. A short description of other current and planned satellite missions has also been included. CO2M will allow many new opportunities due to the increased level of ambition compared to previous and current satellite missions. CO2M is therefore considered a game-changer in comparison with previous and current satellite missions.
Use of satellite data to verify national greenhouse gas emissions inventories as a method is recognised by the IPCC. However, the IPCC also acknowledges a number of challenges including the need for specialised modelling competences. Under Danish circumstances, the largest need and potential for verification is for the sources that currently is associated with the largest uncertainties. These sources are generally methane and nitrous oxide and carbon dioxide from land use. There are international examples of the use of atmospheric observations being used to verify national emission inventories. However, the examples reported to the UNFCCC are using land-based observations for the inverse modelling and there are no Danish examples. There are examples of research projects having used satellite data to verify national emission estimates.
As a part of the project, contact has been made to a number of stakeholders with the aim of collecting their input on the interests and competences available related to the use of satellite data in particular with a focus on greenhouse gas emissions. Additionally, the potential needs both short and longer term that could be met using satellite data has been investigated. There have been many responses, which mainly fall within three categories: research institutions, governmental ministries and agencies, and business/interest organisations. In some cases, there is an overlap and some inputs therefore reflect both a research interest and/or a regulatory or business interest. The many inputs received are synthesised in Chapter 2.
The mapping of competences, infrastructure and research interests shows that there are significant existing competences within the field of using satellite data in general, but basically no experience specifically when it relates to greenhouse gases. It is emphasised that Denmark lacks competences within the field of inverse modelling and that it can be relevant to also enhance the competences within retrieval and analysis of satellite data specifically relating to greenhouse gas data. It is also clear, that it will be necessary with land-based observations in addition to satellite data to achieve the best results.
In relation to the mapping of short and long-term needs, the survey showed a large interest in the opportunities in using satellite data to verify and improve the national emission inventory. At the same time there is some uncertainty as to the precision of the estimates that can be derived or formulated in a different way, how large uncertainties are associated with the emission estimates derived based on satellite observations. There is therefore some scepticism as to whether the data will be of sufficient quality, e.g. to be used directly in relation to regulatory measures. It is emphasised that the potential of using data for verification of national emissions is considered to be great including to monitor changes in emissions over time and to verify the effect of individual targeted measures.
Regarding commercial interests, the survey shows that there is considered to be a large potential. However, this requires that the methodologies and uncertainties associated with the estimates are transparently described.
It is important that Danish work in this field is supplementing the work ongoing internationally and it would be very valuable with more international coordination, e.g. in the EU to ensure the optimal use of resources. One example of this could be the planning of land-based observations, where it would be advantageous to coordinate across national borders to ensure the best possible design on the measurement network.
Presently, the necessary competences are not available in Denmark to contribute to the international work on inverse modelling. This will be required to achieve an adequate understanding of the opportunities and limitations specifically pertaining to the Danish circumstances.
The consequences of the Danish specific circumstances related to cloud cover and water vapour in the atmosphere can also necessitate improvements related to the retrieval and analysis of the satellite data.
Based on the mapping in this project, it will be important to quickly decide whether this area should be prioritised in the future. If a coordinated effort is not made, it will not be possible to build the necessary competences. Reliance on ad-hoc projects and sporadic participation in international projects will not build the competences needed in the longer term. Without competences, Denmark will not be able to influence the planned future work at the European level and Denmark will therefore have to rely on services developed without any Danish input and without consideration for specific Danish circumstances.
If it is decided to launch a coordinated effort in this area to fully utilise the data from CO2M, it will be necessary to start a number of initiatives in order to build capacity within the following areas:
Considering the large existing competences within satellite data at DMI, it would be natural that these competences were enhanced to include specific competences related to greenhouse gas emissions. For the land-based observations, it would be obvious to prioritise continuing the work within ICOS with the establishment of one or two atmospheric measurement stations. For inverse modelling, the competences would have to be built from scratch. A build-up of these competences could be considered in connection with existing competences in Denmark within modelling of atmospheric processes
