18.02.2004: Atmos. Chem. Phys. Discuss., 4, 1151-1180, 2004

MAX-DOAS measurements of formaldehyde in the Po-Valley A. Heckel, A. Richter, T. Tarsu, F. Wittrock, C. Hak, I. Pundt, W. Junkermann, and J. P. Burrows

During the first measurement campaign of the EU Format project in summer 2002 near Milan, northern Italy, ground-based scattered light differential optical absorption spectroscopy (DOAS) measurements were performed using a new multi-axis instrument. From the measurements, vertical column densities of formaldehyde (HCHO) have been retrieved throughout the 4 weeks period, employing a fitting window from 335 nm to 357 nm. In the radiative transfer calculations aerosol parameters derived from the analysis of the oxygen dimer O4 absorption were used. By analysing the measurements from different viewing directions (zenith, 4x off-axis) vertical profile information, and in particular mixing ratios for the boundary layer have been derived for the first time for HCHO with a multi-axis DOAS (MAX-DOAS) instrument. HCHO mixing ratios varied between 0.7 ppb and 4.2 ppb, which is in excellent agreement with simultaneous measurements from both a Hantzsch in-situ and a long-path DOAS instrument operated at the same place.

Full paper available at http://www.copernicus.org/EGU/acp/acpd/4/1151/acpd-4-1151.pdf