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ICOS-INWIRE report 2.4 ATM tests
The objective of task 2.4 is to test ‘heavy-duty’ atmospheric CO2/CH4 and meteo sensor systems for remote areas and challenging environments in order to demonstrate that the performance of these systems are compatible with the WMO recommendations. Measurements have been performed under a variety of conditions in order to test: - Effect of high and variable water vapour concentration on the built-in correction to obtain correct dry mole fractions - Efficiency of Nafion dryers and functionality in combination with (dry) calibration gases - Instrument set up and performance under high particle load (dusty environments) - Instrument performance on mobile platform with induced vibrations and movements Conclusions from the first round of tests are: • Measurements in air with high aerosol load requires a sound management strategy for filters and intake lines. • Measurements in areas with high ambient humidity require careful consideration of the functioning of a drier system, if such are used, and it might actually introduce errors in the same order as that caused by the water vapour itself. • Measurement on mobile platforms should preferably be done with instruments designed for the purpose as the performance of “standard” stationary instruments may be reduced under such conditions. In any case, it is important to evaluate the effect of the movements. • In any location, crucial parts of the measurement setup are also to have correct time on all instruments (time synchronization), power backup and lightning protection. • A tentative general conclusion is that WMO specifications can be met provided all ‘help’ systems are functioning as intended. However, it is recommendable to perform long term tests to verify that such a conclusion holds. This could be done on some selected ICOS sites were such autonomous systems could be installed and run in parallel with the ordinary ICOS systems.
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ICOS-INWIRE report 3.1
ICOS-INWIRE Deliverable 3.1: Report on Automatic near real time GHG concentration data processing
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ICOS-INWIRE report 4.3
A heavy-duty, robust autonomous eddy covariance system (HAEC) has been designed and constructed in line with the ICOS-INWIRE work package (WP) 4 objectives. The main design criteria are: a resistance to extreme weather especially cold extremes, the efficient use of limited energy supply, the intelligent use of wireless technology, the compliance to ICOS specifications and where feasible WMO standards, and the use of readily available technologies where possible. The system can be divided in four parts: an eddy covariance element containing its own data logger and power supply, meteorology and radiation elements, a wireless networked ground sensors element and an electricity and data handling element. The wireless networked sensors had to be designed and constructed from scratch. Initial prototypes have been tested in the field. While not yet faultless they have shown great stability and consistency. Tests in Spain have been concluded, tests in Sweden are underway and at the end of the winter the final testing phase in Finland will start.
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ICOS-INWIRE report 6.2 Network design
A coordinated network design study for Europe was performed using three different regional inversion systems for the estimation of biosphere-atmosphere exchange fluxes. Uncertainties for prior fluxes and model-data mismatch were harmonized to assure the inter-comparability of the inversion results. The prior error structure was based on a comparison of the different prior fluxes used in the inversions with eddy covariance observations. Uncertainty reductions in biosphere-atmosphere exchange fluxes were computed by the different inversion systems for the current and planned ICOS network of atmospheric stations, as well as for a hypothetic network with a gap in the area of Germany. Inversion results show a strong spatial inhomogeneity in the uncertainty reductions with typical values for seasonal fluxes around 30-50% near observing sites for the pixel scale (50 km), and around 50% for national scales. While the general level of uncertainty reduction differs between the inversion systems, the increase of uncertainty reduction with increasing number of stations per area or country is similar.
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ICOS-INWIRE report 6.3 comp TCCON
A comparison of TCCON observations of column-averaged dry air mole fractions of CO2 with a combination of tall-tower based in-situ profile observations for the PBL, boundary layer height data, and TM3-simulated CO2 mixing ratios for the free troposphere. In general, the dry-air mole fractions retrieved by the different methods (TM3 model, synthetic model + tall-tower in-situ, TCCON) agreed within limits. The model-derived columns are likely biased high vs. TCCON during winter and also possibly during summer. One possible reason could be that the age of air in the stratosphere is too low in the TM3 model. This would lead to overestimated CO2 values in the upper part of the column. More surprising was the small difference between CO2 profiles derived from model + in-situ observations vs. just modelled ones. The original expectation had been that stronger impacts would be found when using in-situ observations from the towers rather than TM3 model output. However, this was only found for Orleans but not for Bialystok.
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ICOS-INWIRE report D2.1
Report on requirements of heavy-duty atmospheric CO2/CH4/meteo sensors systems for remote areas and challenging environments A full benefit of continuous monitoring networks is only obtained with a high spatial coverage of stations and a very high range of validated data (no long data gaps). This implies the development of very robust and reliable measuring stations, including some deployed in very harsh environment. In this report we analyse possible causes for troubleshooting in such locations and we provide requirements and recommendations to avoid them. We have identified three categories of possible troubleshooting sources; environmental conditions, personal knowledge and instruments and sensors. Based on our monitoring experience we have listed a series of potential usual encountered problems and addressed solutions, recommendation and requirements to avoid them as much as possible. Some typical schematics and solutions are also included into annexes. This report was written with input from scientists from partner laboratories involved in ICOS-INWIRE.
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ICOS-INWIRE report D6.1
Report on revised compatibility goals for atmospheric GHG observations over the continent by C. Gerbig, U. Karstens, T. Koch, P. Kountouris (MPG) The question addressed by this study is if measurements that do not comply with the WMO-recommended compatibility (0.1 ppm for CO2, 2 ppb for CH4) are expected to be useful as input data for regional inversions over continental areas. The assessment of the impact of measurement bias errors on retrieved fluxes was made using the Jena STILT-TM3 regional inversion system. A set of 57 stations was used, corresponding to current and planned ICOS observing stations. Model-data mismatch was set to reflect current inverse transport model capabilities, but also future systems with reduced model-data mismatch (an up to a factor 30 smaller model-data mismatch than current models was investigated). The results show that measurement biases of 0.1 ppm for CO2 and 2 ppb for CH4 are compatible with uncertainty targets for retrieved spatially resolved fluxes that require flux signals to be resolved on annual to inter-annual time scales. Relaxing those requirements will reduce the capability to detect changes in fluxes. The results also show that for domain-wide or national aggregated annual fluxes the uncertainty reduction achieved by current inversions (about 75% for CO2 and CH4) is not significantly impacted by measurement biases unless they exceed about 0.5 ppm or 10 ppb for CO2 and CH4, respectively.
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