bandkl1 (58K)

mpilogo4 (4K)




RESEARCH

The satellite HCHO observations provides informations concerning the localization of biomass burning (intense source of HCHO). The anthropogenic activities (fossil fuel combustion, photosmog) constitute another high HCHO source which allows to distinguish the great industrial region on earth (e.g. the Pô plain in northern Italy).


HCHO PRINCIPAL SOURCE

Formaldehyde (HCHO) is an important indicator of tropospheric hydrocarbon emissions and photochemical activity [Chance et al, 2000]. HCHO is a principal intermediate in the oxidation of hydrocarbons in the troposphere [Meller and Moortgat, 2000].
The oxidation of the Methane (CH4) global background provides a constant HCHO source. Methane is converted to CH3 by reaction with OH or by photolysis (playing a role at high altitudes). By a threebody reaction, CH3 is converted to CH3O2, which ultimately forms HCHO.


HCHO ADDITIONAL SOURCES

In continental boundary layers, anthropogenic sources usually dominate over CH4 as a source of HCHO [Munger et al., 1995; Lee et al., 1998] and make a contribution to the HCHO atmospheric column.

  • Formaldehyde is a primary emission product from biomass burning [Carlier et al., 1986; Lipari et al., 1984] and
  • from fossil fuel combustion [Anderson et al., 1996].
  • It is also formed in the atmosphere as a secondary product in the photochemical oxidation of non-methane hydrocarbons (NMHCs) [Altshuller, 1993; Levi, 1971] and
  • by ozonolysis in NO-rich environment [Atkinson et al., 1995; Grosjean et al., 1996].


HCHO_chemistry_lila (164K)



HCHO REMOVAL

HCHO is a short-lived molecule. It photolyses readily at wavelengths below 400 nm and reacts rapidly with the hydroxyl radical (OH) providing an average tropospheric lifetime for HCHO of about 5 hours [Arlander et al., 1995]. The main removal processes in the troposphere during daylight are the reaction with OH radicals and photolysis.

HCHO is photodissociated to form HCO, which reacts with oxygen primarily to form CO, precursor of CO2. HCHO photolysis and its oxidation by OH radicals also generate hydro peroxy radical (HO2) which react with NO producing NO2, a precursor of O3. Removal by wet and dry deposition can be important during the night [Altschuller, 1993; Lowe and Schmidt, 1983]. HCHO is also involved in acidification of rain and is considered as a precursor of hydrogen peroxide.

HCHO UTILITY AND RETRIEVAL

Due to the relatively constant CH4 concentrations in the troposphere (main HCHO source) combined with the short lifetime of HCHO (photolysis dominant HCHO sink), HCHO provides an important indicator of biomass burning and NMHCs oxidation over continent (additional HCHO sources). The HCHO-data are derived from observations made by the GOME. The global Ozone Monitoring Experiment (GOME), launched on the ERS-2 satellite in April, 1995, obtain about 30,000 Earth radiance spectra each day.

Spectra cover the ultraviolet (237-405 nm at 0.2 nm resolution) and the visible (407-794 nm at 0.4 nm resolution) [Burrows et al., 1993; Ladstätter-Weißenmayer, 2003]. HCHO slant columns are determined from GOME spectra by using algorithms developed at the IUP, with the DOAS technique [Platt, 1994], over the wavelength region 337.3-356.1 nm. This fitting window was determined as the optimum compromise between large amplitude for the differential HCHO cross sections and small spectral interference. The fitting includes the interfering species O3, NO2, BrO, and the O2-O2 collision complex.


References

Altshuller A. P., Production of aldehydes as primary emissions and from secondary atmospheric reactions of alkenes and alkanes during the night and early morning hours. Atmospheric Environment, 27, 21-31, 1993.

Anderson L. G., Lanning J. A., Barrel R., Mityagishima J., Jones R. H., and Wolfe P., Sources and sinks of formaldehyde and acetaldehyde: An analysis of Denver's ambient concentration data. Atmospheric Environment 30, 2113-2123, 1996.

Arlander D. W., Brüning D., Schmidt U., and Ehhalt D. H., The Tropospheric Distribution of Formaldehyde During TROPZ II. Journal of Atmospheric Chemistry, 22, 251-268, 1995.

Atkinson R., Tuazon E. C., and S.M. A., Products of the gas-phase reactions of O3 with alkenes. Environment Sciences Technology, 29, 1860-1866, 1995.

Burrows J. P., Chance K., Goede A. P. H., Guzzi R., Kerridge B. j., Muller C., Perner D., Platt U., Pommereau J.-P., Schneider W., Spurr R. J. D., and van der Woerd H., Global Ozone Monitoring Experiment Interim Science Report ed. T. D. Guyenne and C. Readings, Report ESA SP-1151, ESA Publications Division, ESTEC, Noordwijk, The Netherlands, ISBN 92-9092-041-6, 1993.

Carlier P., Hannachi H., and Mouvier G., The chemistry of carbonyl compounds in the atmosphere. Atmospheric Environment, 20, 2079-2099, 1986.

Chance K., Palmer P. I., Spurr R. J. D., Martin R. V., Kurosu T. P., and Jacob D. J., Satellite observations of formaldehyde over North America from GOME. Geophysical Research Letters, 27, 3461-3464, 2000.

Grosjean E., De Andrade J. B., and Grosjean D., Carbonyl products of the gas-phase reaction of ozone with simple alkenes. Environment Sciences Technology 30, 975-983, 1996.

Ladstätter-Weißenmayer A., Heland J., Kormann R., v. Kuhlmann R., Lawrence M. G., Meyer-Arnek J., Richter A., Wittrock F., Ziereis H., and Burrows J. P. (2003) Transport and build-up of tropospheric trace gases during the MINOS campaign: Comparision of GOME, in situ aircraft measurements and MATCH-MPIC-data. Atmos. Chem. Phys. Discuss. 3, 3051-3094.

Lee Y.-N. and al. e., Atmospheric chemistry and distribution of formaldehyde and several multioxygenated carbonyl compounds during the 1995 Nashville/Middle Tennessee Ozone Study. Journal of Geophysical Research, 103, 22449-22462, 1998.

Levi H., Normal atmosphere: Large radical and formaldehyde concentrations predicted. Sciences, 173, 141-143, 1971.

Lipari F., Dasch J. M., and Scuggs W. F., Aldehyde emissions from wood-burning fireplaces. Environment Sciences Technology, 18, 326-330, 1984.

Lowe D. C. and Schmidt U., Formaldehyde (HCHO) measurements in the momurban atmosphere. Journal of Geophysical Research, 88, 10844-10858, 1983.

Meller R. and Moortgat G. K., Temperature dependence of the absorption cross sections of formaldehyde between 223 and 323 K in the wavelenght range 225-375 nm. Journal of Geophysical Research, 105, 7089-7101, 2000.

Munger J. W., Jacob D. J., Daube B. C., Horowitz L. W., Keene W. C., and Heikes B. G., Formaldehyde, glyoxal. and methylglyoxal at a rural mountain site in central Virginia. Journal of Geophysical Research, 100, 9325-9334, 1995.

Platt U., "Differential optical absorption spectroscopy (DOAS)", in Air Monitoring by Spectroscopic Techniques. Chem. Anal. Ser., 127, 27-84, 1994.








RESULTS

HCHO
HCHO96logo (130K)

scale_hcho0 (8K)

7,5 year mean of Formaldehyde (HCHO) tropospheric column density (1996 to june 2003).
Data from GOME instrument (only measurements with less than 20% cloud cover). Unit: 1015 molecules per cm2.


Video IGAC-Conference "Formaldehyde, Satellite Measurements of Shipping Emissions"