Abstract
Abstract. This paper is a case study to investigate what the main controlling factors are that determine atmospheric carbon dioxide content for a region in the centre of The Netherlands. We use the Regional Atmospheric Modelling System (RAMS), coupled with a land surface scheme simulating carbon, heat and momentum fluxes (SWAPS-C), and including also submodels for urban and marine fluxes, which in principle should include the dominant mechanisms and should be able to capture the relevant dynamics of the system. To validate the model, observations are used that were taken during an intensive observational campaign in central Netherlands in summer 2002. These include flux-tower observations and aircraft observations of vertical profiles and spatial fluxes of various variables. The simulations performed with the coupled regional model (RAMS-SWAPS-C) are in good qualitative agreement with the observations. The station validation of the model demonstrates that the incoming shortwave radiation and surface fluxes of water and CO2 are well simulated. The comparison against aircraft data shows that the regional meteorology (i.e. wind, temperature) is captured well by the model. Comparing spatially explicitly simulated fluxes with aircraft observed fluxes we conclude that in general latent heat fluxes are underestimated by the model compared to the observations but that the latter exhibit large variability within all flights. Sensitivity experiments demonstrate the relevance of the urban emissions of carbon dioxide for the carbon balance in this particular region. The same tests also show the relation between uncertainties in surface fluxes and those in atmospheric concentrations.
Highlights
A large mismatch exists between our understanding and quantification of ecosystem atmosphere exchange of carbon dioxide at the local scale and that at the continental scale
A comparison will be made between station observations and simulated results focussing on the various fluxes between the land surface and atmosphere
For the simulated period the comparison between station observations and model output looked very promising for the grass and forest sites
Summary
A large mismatch exists between our understanding and quantification of ecosystem atmosphere exchange of carbon dioxide at the local scale and that at the continental scale. Together with the vertical mixing in the atmosphere, these surface fluxes vary diurnally and seasonally, leading to the rectifier effect, which is difficult to capture in large scale transport models. The following question will be addressed: What are the main controlling factors determining atmospheric carbon dioxide concentration at a regional scale as a consequence of the different surface fluxes? To study this regional scale interaction it is important to use land surface descriptions of appropriate complexity, that include the main controlling mechanisms and capture the relevant dynamics of the system, and to represent the real-world spatial variability in soils and vegetation. This paper will conclude with a discussion of these results in terms of the factors that control the carbon dioxide content at a regional scale
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
