Five-year flask measurements of long-lived trace gases in India

Abstract

Abstract. With the rapid growth in population and economic development, emissions of greenhouse gases (GHGs) from the Indian subcontinent have sharply increased during recent decades. However, evaluation of regional fluxes of GHGs and characterization of their spatial and temporal variations by atmospheric inversions remain uncertain due to a sparse regional atmospheric observation network. As a result of Indo-French collaboration, three new atmospheric stations were established in India at Hanle (HLE), Pondicherry (PON) and Port Blair (PBL), with the objective of monitoring the atmospheric concentrations of GHGs and other trace gases. Here we present the results of five-year measurements (2007–2011) of CO2, CH4, N2O, SF6, CO, and H2 from regular flask sampling at these three stations. For each species, annual means, seasonal cycles and gradients between stations were calculated and related to variations in the natural GHG fluxes, anthropogenic emissions, and the monsoon circulations. Covariances between species at the synoptic scale were analyzed to investigate the dominant source(s) of emissions. The flask measurements of various trace gases at the three stations show potential to constrain the inversions of fluxes over Southern and Northeastern India. However, this network of ground stations needs further extension to other parts of India to allow a better understanding of, and constraints on the GHG budgets at regional and continental scales.

Observation of atmospheric CO₂ and CO at Shangri-La station: results from the only regional station located at southwestern China

“…CO enhancement during summer has also been observed in the upper troposphere over South Asia from the CARIBIC aircraft measurements at flight (Schuck et al, 2010;Rauthe-Scho¨ch et al, 2015). Lin et al (2015) observed the atmospheric CO from 2007 to 2011 at the Hanle station (32.78 8 N, 78.96 8 E, 4517 masl) in India, which is located at 2000 km west of Shangri-La. They found that the CO mole fractions reached their maximum in mid-March and the minimum by the end of October and they concluded that the delay in timing of the seasonal CO minimum was due to the mixing time of regional surface CO emissions and the relatively short atmospheric lifetime of CO (1Á2 months on average).…”