Observations

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Science case

Long term measurements of atmospheric CO2 from the global network indicate that the level at which we might stabilise future CO2 concentrations is rapidly rising due to the impact of accelerating fossil fuel burning. These measurements, first started more than 50 years ago at Mauna Loa by the visionary scientist Dave Keeling, have changed our perception of the Earth system because they provided the first high accuracy record of essential components of the Earth’s atmosphere. Without this long record of observations, our awareness and understanding of global change would have come far more slowly. Sudden events, such as the marked fluctuations in global CO2 uptake after the 1991 volcanic eruption of Mount Pinatubo, increased fire emissions in Indonesia in 1997/1998 after a very strong El Niño, and more recently, the 2003 European drought, look very differently in the context of a 5, 10, or 15-year rather than a 30-year record. Such long term observations are notoriously difficult to fund with short term funding cycles and Europe unfortunately lags behind other areas in the world in developing robust monitoring programmes.

ICOS will bring these measurements into a network that can operate with secured funding with a time horizon of 10-20 years, thus assuring the continuity of data that is needed to detect trends and anomalies in concentrations of the major greenhouse gases.

Greenhouse gas observations can only be integrated in the global network of climate relevant monitoring if the measurements conform to the WMO GAW recommendations for measurement good practice, data treatment and precision requirements [refs]. The greenhouse gases are important Essential Climate Variables as defined in the GCOS - Global Climate Observing System, to which the EU and it member states have agreed to contribute.

GHG budgets and the multiple constraint approach

Attribution of changes in greenhouse gas levels to specific areas and processes is important to monitor compliance to treaties, policy effectiveness, and the stability of natural greenhouse gas sinks. To achieve that, the greenhouse gas balance must be characterized at regional scales. For Europe this is highly challenging because of the variable natural landscape and scattered industrial sources. The GHG balance is affected by fossil fuel burning and by biological responses of the ecosystem to agricultural and forest management, as well as to climate forcing. To establish this balance for any domain, one needs to characterize inflow of GHGs, outflow of GHGs, and the internal exchange (sources and sinks) between the atmosphere and the other GHG or carbon reservoirs.
Inflow and outflow of long-lived greenhouse gases, such as CO2, are estimated from observations in the atmosphere using high-precision concentration measurements in a strategically deployed network of tall towers. Through mass balance, these observations also inform on carbon sources and sinks in an area of maximum ~1000 km2 upwind of each tower. Weather models, satellite observations of carbon dioxide, as well as of land-use and vegetation health provide boundary conditions and help to scale down to smaller scales. At the local scale, (~2 km2) sources and sinks of greenhouse gases and changes in natural carbon stocks are monitored through direct
flux measurements in a network of flux towers. Process specific attribution of GHG exchange requires two additional components: measurement of atmospheric oxygen and radon and various isotope abundances (13C, 18O, 2H), that reveal unique signatures of different sources, and numerical models to consistently integrate the information from the large scale (global, national, provincial) to smaller scales.
This combination of methods, while still subject to considerable uncertainties, is presently the most accurate manner to arrive at spatially explicit GHG budgets. It is referred to as the ‘multiple constraint’ method and forms the core of ICOS.

Quantitative estimates.

However the scale at which climate anomalies such as droughts, floods and heat waves, and human intervention (land use management) have impact on land-atmosphere fluxes is still much smaller than currently resolved by the multiple constraint method. The scientific breakthrough that is required is to achieve understanding at this scale is to regionalise the current large scale estimates. This is non-trivial. The sparseness of current atmospheric data limits the analysis to large scale sources and sinks and forces us to make assumptions about the behaviour of sources and sinks at regional scales, and this is arguably the stumbling block currently preventing improved understanding. To improve the resolution of regional scale sources and sinks requires a very high density of observations.
As the unique Dutch contribution to this effort we propose a high density observation network in combination with the multiple constraint approach, aiming at determining the greenhouse gas balance at the very high resolution of landscapes, conglomerations and industrial zones. The small surface area of the Netherlands, its high population density, the heterogeneous landscape, the influence of the sea, and the strongly managed agricultural sector make this an excellent contribution to the infrastructure of ICOS and for the development of greenhouse gas cycle science in Europe. Developing this network is only possible within the larger scale framework of ICOS that provides the standards, protocols and the required data at the boundaries of the dense network.
Hence ICOS-NL contributes not only to ICOS by making observations relevant to ICOS, but adds considerable value by exploiting the synergies between the national (ICOS) and very dense (ICOS-NL) networks. Ultimately, ICOS-NL will provide quantitative estimates of the annual greenhouse gas balance of the Netherlands on a scale of several kilometers, nested in the larger domain of ICOS.

A high density greenhouse gas cycle observation network in the Netherlands.

Retrieving information of land-atmosphere exchange at regional scales from continuous concentration measurements made at tall towers is a recent advance in determining sources and sinks. Dutch researchers led the FP6 and FP7 programmes that implemented a set of six tall towers in Europe and the regional projects of the CarboEurope-IP. ICOS-NL will take full advantage of this expertise in developing the world's first high density observational system for GHG measurements.

Only recently, since 2005-2006, we established in Europe in research mode a coordinated network of tall towers that performs continuous long-term, very precise and accurate observations of all the most relevant greenhouse gases. These towers cover most of Western Europe but are still 700-1500 km apart. These observations now for the first time allow us to test in real life the potential of such continuous observations in inverse model systems. Current inverse model systems used until now only the afternoon values to avoid biases due to vertical mixing processes not captured in these relative coarse models. The challenge will be to make use of the information content of the full diurnal cycle of the continuous observations. The data series and evaluation by forward and inverse models that have been performed tell us that the sensitivity of detectable concentration changes to surface emissions, as observed at tall towers, is highly variable, depending for example strongly on the meteorological conditions. For the greenhouse gases and conditions in Europe this sensitivity is limited to distances of 100-500 km [refs]. Recent developments in high resolution inversions from an ensemble of five different model indicate that for methane and nitrous oxide the current network, by combining the synergy of information from the individual observations, is able to capture the spatial distribution and absolute value of the emission strengths at annual to seasonal timescale in a wide area around and between the observation points [refs]. In order to determine emissions with inverse systems at higher temporal and spatial resolution, a higher density of the network than currently available, will be required. Another challenge will be to move the network operation of such a network from science to operational mode, by using innovative and cost-effective new technologies in measurement techniques and network operation logistics.

Atmospheric inverse modelling at these smaller scales is challenging, as small scale circulations have the potential to dramatically complicate the interpretation of the measurements. The strong variability of land-atmosphere fluxes requires transport models with much higher spatial resolution than those currently used. Furthermore, performing inversions at this scale requires improved and detailed knowledge of the behaviour of the land emissions and uptake near a tower.
This knowledge is key input into the inverse modelling framework, that will determine the spatial and temporal patterns of emissions and uptake.

Remote sensing of greenhouse gases

A recent development is to measure greenhouse gases from space using satellite instruments, and to use the improved global measurement coverage obtained using this approach to improve inverse modeling derived source and sink estimates. The technique has been demonstrated for CH4 measurements from the SCIAMACHY instrument. The improved accuracy of the GOSAT instrument yields significantly improved measurements of CH4 and allows application of the approach to CO2. New instruments are under development, such as OCO-2 for CO2 and Tropomi for CH4 (both planned for launch in 2014), which are expected to take significant further steps in measurement accuracy, coverage, and resolution. Besides application to large-scale modeling this opens the way towards the application of space born greenhouse gas measurements to regional scale modeling, which we will further explore as part of this project.

The observational network

For adequate direct greenhouse gas concentration and flux monitoring purposes, we will establish:

  1. a network of six tall towers observing atmospheric trace gas (CO2, CH4) concentrations at the western and eastern boundaries of the Netherlands, as well as in the centre of the ‘Randstad’. This will characterise inflow and outflow of greenhouse gases at our borders and constrains sources and sinks on national to regional levels across the country.
  2. of the six tower site two are super sites observing non-CO2 greenhouse gas mixing ratios, atmospheric oxygen, radon and several isotope abundance measurements at two of the above six atmospheric locations to separate man-made and natural terrestrial and oceanic contributions to the greenhouse gas balance.
  3. a network of five ecological sites to monitor greenhouse gas exchange in selected ecosystems, including peat lands, managed agricultural fields, production forests, and natural wetland areas. This will establish the stability of important carbon reservoirs, and allow improved understanding of key ecosystems undergoing climate change.
  4. development of an innovative low maintenance in-situ FTIR system on the basis of the Wollongong FTIR system with improved time resolution and stability and testing at supersites Cabauw and Lutjewad. The in-situ FTIR stores full infrared spectra and allows at current ambient levels to detect at high precision all of the most important greenhouse gases
  5. an archive of satellite measurements of vertical column average CH4 and CO2 from existing (GOSAT) and upcoming (OCO-2,Tropomi) missions.
  6. monitoring of auxiliary information (meteorological variables, ecosystem parameters, land-use indicators) using appropriate methods (including, soil and biomass sampling, satellites, etc.) needed for consistent interpretation in the multiple constraint method.

From the observations sites, two of the concentration observation sites and two of the ecosystem observation sites will be ICOS level I sites and form the contribution of ICOS-nl to the European ICOS network. The other sites will be associated Level II sites.

Talent case

Greenhouse gas cycle and climate change research in the Netherlands has reached high levels of quality with world-renowned leaders in instrument development (ECN, RuG, SRON, UU), laboratory and field experimentation (ECN, RuG, VU, UU, WUR), monitoring (ECN, KNMI, WUR, RuG), and modelling (ECN, UU, VU, SRON, WUR). An increased level of collaboration is already brought about by several European and certainly also national projects (CarboEurope-IP , CarboOcean, CcSP). These historical collaborations make ICOS-NL such a strong bid and provide promising potential for further collaboration and excellence. So far, however, this group has lacked a suitable common infrastructure. ICOS-NL aims at realising this potential by building an infrastructure, which will initiate closer collaboration and thereby boost the innovative and interdisciplinary character of Dutch greenhouse gas research.

This improved science environment is the main pillar for attracting talent from abroad and preventing Dutch talent from leaving the country, for scientific and career opportunity reasons, which is an important and necessary aspect of the ICOS-NL proposal. ICOS-NL will improve the climate for collaborative greenhouse gas research in the Netherlands by:

  1. Bridging the gap between participating institutes.
  2. Facilitating access to state of the art research equipment and transparent, quality controlled data archives.
  3. Developing common (community available) research models.
  4. Creating opportunities for exchange of researchers and students between participating universities and research institutes.
  5. Creating a spin off as an education and training institute that will attract students and is important for long-term continuity of the facility.

Innovation case

As the unique Dutch contribution to this effort we propose a high density observation network in combination with the multiple constraint approach, aiming at determining the greenhouse gas balance at the very high resolution of landscapes, conglomerations and industrial zones. The small surface area of the Netherlands, its high population density, the heterogeneous landscape, the influence of the sea, and the strongly managed agricultural sector make this an excellent contribution to the infrastructure of ICOS and for the development of greenhouse gas cycle science in Europe. Developing this network is only possible within the larger scale framework of ICOS that provides the standards, protocols and the required data at the boundaries of the dense network.

Retrieving information of land-atmosphere exchange at regional scales from continuous concentration measurements made at tall towers is a very recent advance in determining sources and sinks. Dutch researchers led the FP6 and FP7 programmes that implemented a set of six tall towers in Europe and the regional projects of the CarboEurope-IP. ICOS-NL will take full advantage of this expertise in developing the world's first high density observational system for GHG measurements. Atmospheric inverse modelling at these scales is also challenging, as small scale circulations have the potential to dramatically complicate the interpretation of these measurements. The strong variability of land-atmosphere fluxes requires transport models with much higher spatial resolution than those currently used. Furthermore, performing inversions at this scale requires improved and detailed knowledge of the behaviour of the land emissions and uptake near a tower.
This knowledge is key input into the inverse modelling framework, that will determine the spatial and temporal patterns of emissions and uptake.

We propose to acquire and improve two closed-path Fourier Transform InfraRed spectrometers (Dual-FTIR) from the world leaders of this technology at the University of Wollongong (Australia). The instrument will be used for automatic long-term atmospheric measurements of CO2, CH4, N2O, CO, δ13C in CO2 and δD in H2O at the Cabauw and Lutjewad. In addition to measuring the important greenhouse gases CH4 and N2O with significantly higher precision, this instrument will enable us to perform for the first time in-situ, quasi-continuous measurements of vertical profiles of isotope signatures, i.e., δ13C in CO2 and δD in H2O at Cabauw.

Partnership case

EarthNetworks
Kipp Instruments
SensorSense
EcoTech?
Uni Bremen?

Business case

The EarthNetworks partner has agreed to take responsibility in a public-private partnership for the operation of the five Level 2 atmospheric stations making use of the synergies with their global meteorological network. They will contribute the costs of one of the five atmospheric Level 2 stations. For operation of the Level 1 atmospheric and ecosystem site a station fee is required to the ICOS central facilities for Atmosphere, Ecosystem and the Calibration Facility. ICOS-nl will receive a user fee from ICOS members for the use of the EBS for data assimilation systems and a contribution for the computing costs of the supercomputing facility. About 10-20% of the annual exploitation budget of the ICOS-nl CPF is expected to be received from user fees.

Total Costs

non-NWO contributions

EN

Requested NWO financing

Technical case

Possible focus for the Netherlands

Critical mass

Embedding

Proven willingness to cooperate

Dutch researchers led the FP6 and FP7 programmes that implemented a set of six tall towers in Europe and the regional projects of the CarboEurope-IP. ME cluster. COCOS/InGOS.

Reflection of social trends

Other relevant information

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