Three-year observations of halocarbons at the Nepal Climate Observatory at Pyramid (NCO-P, 5079 m a.s.l.) on the Himalayan range 1University of Urbino, DiSBeF, Urbino, Italy
12 Apr 2011
2CNR-Institute for Atmospheric Sciences and Climate, Bologna, Italy
3Laboratoire de Glaciologie et Géophysique de l'Environnement, Université Grenoble 1-CNRS, Grenoble, France
4Ev-K2-CNR Committee, Bergamo, Italy
5CINFAI, National Consortium of Universities for Atmospheric and Hydrospheric Physics, Italy
Received: 03 August 2010 – Published in Atmos. Chem. Phys. Discuss.: 28 September 2010 Abstract. A monitoring programme for halogenated climate-altering gases has been
established in the frame of the SHARE EV-K2-CNR project at the Nepal
Climate Laboratory – Pyramid in the Himalayan range at the altitude of 5079 m a.s.l.
The site is very well located to provide important insights on
changes in atmospheric composition in a region that is of great significance
for emissions of both anthropogenic and biogenic halogenated compounds.
Measurements are performed since March 2006, with grab samples collected on
a weekly basis. The first three years of data have been analysed. After the
identification of the atmospheric background values for fourteen
halocarbons, the frequency of occurrence of pollution events have been
compared with the same kind of analysis for data collected at other global
background stations. The analysis showed the fully halogenated species,
whose production and consumption are regulated under the Montreal Protocol,
show a significant occurrence of "above the baseline" values, as a
consequence of their current use in the developing countries surrounding the
region, meanwhile the hydrogenated gases, more recently introduced into the
market, show less frequent spikes.
Revised: 08 March 2011 – Accepted: 17 March 2011 – Published: 12 April 2011
Atmospheric concentration trends have been calculated as well, and they
showed a fast increase, ranging from 5.7 to 12.6%, of all the
hydrogenated species, and a clear decrease of methyl chloroform (−17.7%).
The comparison with time series from other stations has also allowed to
derive Meridional gradients, which are absent for long living well mixed
species, while for the more reactive species, the gradient increases
inversely with respect to their atmospheric lifetime. The effect of long
range transport and of local events on the atmospheric composition at the
station has been analysed as well, allowing the identification of relevant
source regions the Northern half of the Indian sub-continent. Also, at finer
spatial scales, a smaller, local contribution of forest fires from the
Khumbu valley has been detected.
Citation: Maione, M., Giostra, U., Arduini, J., Furlani, F., Bonasoni, P., Cristofanelli, P., Laj, P., and Vuillermoz, E.: Three-year observations of halocarbons at the Nepal Climate Observatory at Pyramid (NCO-P, 5079 m a.s.l.) on the Himalayan range, Atmos. Chem. Phys., 11, 3431-3441, doi:10.5194/acp-11-3431-2011, 2011.