A conceptual framework to quantify the influence of convective boundary layer development on carbon dioxide mixing ratios 1Applied Physics Department, BarcelonaTech (UPC) and Institute for Space Studies of Catalonia (IEEC-UPC), Barcelona, Spain
26 Mar 2012
2Meteorology and Air Quality Section, Wageningen University, Wageningen, The Netherlands
3Max Planck Institute for Meteorology, Hamburg, Germany
Received: 21 Oct 2011 – Published in Atmos. Chem. Phys. Discuss.: 12 Dec 2011 Abstract. Interpretation of observed diurnal carbon dioxide (CO2) mixing ratios near
the surface requires knowledge of the local dynamics of the planetary
boundary layer. In this paper, we study the relationship between the boundary
layer dynamics and the CO2 budget in convective conditions through a newly
derived set of analytical equations. From these equations, we are able to
quantify how uncertainties in boundary layer dynamical variables or in the
morning CO2 distribution in the mixed-layer or in the free atmosphere (FA)
influence the bulk CO2 mixing ratio.
Revised: 05 Mar 2012 – Accepted: 14 Mar 2012 – Published: 26 Mar 2012
We find that the largest uncertainty incurred on the mid-day CO2 mixing
ratio comes from the prescribed early morning CO2 mixing ratios in the
stable boundary layer, and in the free atmosphere. Errors in these values
influence CO2 mixing ratios inversely proportional to the boundary layer
depth (h), just like uncertainties in the assumed initial boundary layer
depth and surface CO2 flux. The influence of uncertainties in the boundary
layer depth itself is one order of magnitude smaller. If we "invert" the
problem and calculate CO2 surface exchange from observed or simulated
CO2 mixing ratios, the sensitivities to errors in boundary layer dynamics
also invert: they become linearly proportional to the boundary layer depth.
We demonstrate these relations for a typical well characterized situation at
the Cabauw site in The Netherlands, and conclude that knowledge of the
temperature and carbon dioxide profiles of the atmosphere in the early
morning are of vital importance to correctly interpret observed CO2 mixing
ratios during midday.
Citation: Pino, D., Vilà-Guerau de Arellano, J., Peters, W., Schröter, J., van Heerwaarden, C. C., and Krol, M. C.: A conceptual framework to quantify the influence of convective boundary layer development on carbon dioxide mixing ratios, Atmos. Chem. Phys., 12, 2969-2985, doi:10.5194/acp-12-2969-2012, 2012.