MAX-DOAS measurements of formaldehyde in the Po-Valley A. Heckel1, A. Richter1, T. Tarsu1, F. Wittrock1, C. Hak2, I. Pundt2, W. Junkermann3, and J. P. Burrows1 1Institute of Environmental Physics (IUP), P.O. Box 33 04 40, University Bremen, 28334 Bremen, Germany 2IUP, Im Neuenheimer Feld 229, University Heidelberg, 69120 Heidelberg, Germany 3IMK-IFU, Kreuzeckbahnstrasse 19, 82467 Garmisch-Partenkirchen, Germany
Abstract. 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 data set of this four week
measurement period, the detailed analysis results of three days, 12–14 August, are presented exemplary.
Slant column densities for formaldehyde (HCHO) and the oxygen dimer (O4)
have been retrieved, employing fitting windows from 335 nm to 357 nm and 350 nm to
360 nm respectively. In order to convert slant into vertical columns radiative
transfer calculations were perfomred using aerosol parameters derived from the actual
O4 measurements. 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 vertical columns are in the range of 5 to
with an relative error of about 15%.
This corresponds to HCHO mixing ratios in the boundary layer of
0.7 ppb to 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.
Citation: Heckel, A., Richter, A., Tarsu, T., Wittrock, F., Hak, C., Pundt, I., Junkermann, W., and Burrows, J. P.: MAX-DOAS measurements of formaldehyde in the Po-Valley, Atmos. Chem. Phys., 5, 909-918, doi:10.5194/acp-5-909-2005, 2005.