UV absorption cross sections of nitrous oxide (N2O) and carbon tetrachloride (CCl4) between 210 and 350 K and the atmospheric implications 1Earth System Research Laboratory, Chemical Sciences Division, National Oceanic and Atmospheric Administration, 325 Broadway, Boulder Colorado, 80305-3328, USA
2Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder Colorado, 80309, USA
3NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA
4Science Systems and Applications, Inc., Lanham, MD, 20706, USA
Received: 07 April 2010 – Published in Atmos. Chem. Phys. Discuss.: 26 April 2010 Abstract. Absorption cross sections of nitrous oxide (N2O) and
carbon tetrachloride (CCl4) are reported at five atomic UV lines
(184.95, 202.548, 206.200, 213.857, and 228.8 nm) at temperatures in the
range 210–350 K. In addition, UV absorption spectra of CCl4 are
reported between 200–235 nm as a function of temperature (225–350 K).
The results from this work are critically compared with results from earlier
studies. For N2O, the present results are in good agreement with the
current JPL recommendation enabling a reduction in the estimated uncertainty
in the N2O atmospheric photolysis rate. For CCl4, the present
cross section results are systematically greater than the current
recommendation at the reduced temperatures most relevant to stratospheric
photolysis. The new cross sections result in a 5–7% increase in the
modeled CCl4 photolysis loss, and a slight decrease in the
stratospheric lifetime, from 51 to 50 years, for present day conditions. The
corresponding changes in modeled inorganic chlorine and ozone in the
stratosphere are quite small. A CCl4 cross section parameterization for
use in atmospheric model calculations is presented.
Revised: 23 June 2010 – Accepted: 01 July 2010 – Published: 07 July 2010
Citation: Rontu Carlon, N., Papanastasiou, D. K., Fleming, E. L., Jackman, C. H., Newman, P. A., and Burkholder, J. B.: UV absorption cross sections of nitrous oxide (N2O) and carbon tetrachloride (CCl4) between 210 and 350 K and the atmospheric implications, Atmos. Chem. Phys., 10, 6137-6149, doi:10.5194/acp-10-6137-2010, 2010.