Modelling CO2 weather-why horizontal resolution matters
Agustí Panareda, Anna (European Centre for Medium-Range Weather Forecasts (UK))
Diamantakis, Michail (European Centre for Medium-Range Weather Forecasts (UK))
Massart, Sébastien (European Centre for Medium-Range Weather Forecasts (UK))
Chevallier, Frédéric (Centre National de la Recherche Scientifique. Laboratoire des Sciences du Climat et de l'Environnement (France))
Muñoz Sabater, Joaquín (European Centre for Medium-Range Weather Forecasts (UK))
Barré, Jérôme (European Centre for Medium-Range Weather Forecasts (UK))
Curcoll Masanes, Roger (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Engelen, Richard (European Centre for Medium-Range Weather Forecasts (UK))
Langerock, Bavo (Royal Belgian Institute for Space Aeronomy (Belgium))
Law, Rachel M. (Commonwealth Scientific and Industrial Research Organisation. Oceans and Atmosphere (Australia))
Loh, Zoë (Commonwealth Scientific and Industrial Research Organisation. Oceans and Atmosphere (Australia))
Morguí, Josep-Anton (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Parrington, Mark (European Centre for Medium-Range Weather Forecasts (UK))
Peuch, Vincent-Henri (European Centre for Medium-Range Weather Forecasts (UK))
Ramonet, Michel (Centre National de la Recherche Scientifique. Laboratoire des Sciences du Climat et de l'Environnement (France))
Roehl, Coleen (California Institute of Technology (Estats Units d'Amèrica))
Vermeulen, Alex T. (European Research Infrastructure Consortium. Integrated Carbon Observation System. Carbon Portal (Sweden))
Warneke, Thorsten (University of Bremen. Institute of Environmental Physics (Germany))
Wunch, Debra (University of Toronto. Department of Physics)

Data:	2019
Resum:	Climate change mitigation efforts require information on the current greenhouse gas atmospheric concentrations and their sources and sinks. Carbon dioxide (CO) is the most abundant anthropogenic greenhouse gas. Its variability in the atmosphere is modulated by the synergy between weather and CO surface fluxes, often referred to as CO weather. It is interpreted with the help of global or regional numerical transport models, with horizontal resolutions ranging from a few hundreds of kilometres to a few kilometres. Changes in the model horizontal resolution affect not only atmospheric transport but also the representation of topography and surface CO fluxes. This paper assesses the impact of horizontal resolution on the simulated atmospheric CO variability with a numerical weather prediction model. The simulations are performed using the Copernicus Atmosphere Monitoring Service (CAMS) CO forecasting system at different resolutions from 9 to 80 km and are evaluated using in situ atmospheric surface measurements and atmospheric column-mean observations of CO, as well as radiosonde and SYNOP observations of the winds. The results indicate that both diurnal and day-to-day variability of atmospheric CO are generally better represented at high resolution, as shown by a reduction in the errors in simulated wind and CO. Mountain stations display the largest improvements at high resolution as they directly benefit from the more realistic orography. In addition, the CO spatial gradients are generally improved with increasing resolution for both stations near the surface and those observing the total column, as the overall inter-station error is also reduced in magnitude. However, close to emission hotspots, the high resolution can also lead to a deterioration of the simulation skill, highlighting uncertainties in the high-resolution fluxes that are more diffuse at lower resolutions. We conclude that increasing horizontal resolution matters for modelling CO weather because it has the potential to bring together improvements in the surface representation of both winds and CO fluxes, as well as an expected reduction in numerical errors of transport. Modelling applications like atmospheric inversion systems to estimate surface fluxes will only be able to benefit fully from upgrades in horizontal resolution if the topography, winds and prior flux distribution are also upgraded accordingly. It is clear from the results that an additional increase in resolution might reduce errors even further. However, the horizontal resolution sensitivity tests indicate that the change in the CO and wind modelling error with resolution is not linear, making it difficult to quantify the improvement beyond the tested resolutions. Finally, we show that the high-resolution simulations are useful for the assessment of the small-scale variability of CO which cannot be represented in coarser-resolution models. These representativeness errors need to be considered when assimilating in situ data and high-resolution satellite data such as Greenhouse gases Observing Satellite (GOSAT), Orbiting Carbon Observatory-2 (OCO-2), the Chinese Carbon Dioxide Observation Satellite Mission (TanSat) and future missions such as the Geostationary Carbon Observatory (GeoCarb) and the Sentinel satellite constellation for CO. For these reasons, the high-resolution CO simulations provided by the CAMS in real time can be useful to estimate such small-scale variability in real time, as well as providing boundary conditions for regional modelling studies and supporting field experiments.
Ajuts:	European Commission 776186
Nota:	Unidad de excelencia María de Maeztu MdM-2015-0552
Nota:	Altres ajuts: The ClimaDat Network has received funding from the "la Caixa" Foundation, under agreement 2010-002624
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Publicat a:	Atmospheric chemistry and physics, Vol. 19, Issue 11 (June 2019) , p. 7347-7376, ISSN 1680-7324

DOI: 10.5194/acp-19-7347-2019

30 p, 10.6 MB

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