Carbon monoxide (CO) and ethane (C<sub>2</sub>H<sub>6</sub>) trends from ground-based solar FTIR measurements at six European stations, comparison and sensitivity analysis with the EMEP model

Abstract

Trends in the CO and C₂H₆ partial columns (~0–15 km) have been estimated from four European ground-based solar FTIR stations for the 1996–2006 time period. The CO trends from the four stations Jungfraujoch, Zugspitze, Harestua and Kiruna have been estimated to −0.45±0.16 % yr⁻¹, −1.00±0.24 % yr⁻¹, −0.62±0.19 % yr⁻¹ and −0.61±0.16 % yr⁻¹, respectively. The corresponding trends for C₂H₆ are −1.51±0.23 % yr⁻¹, −2.11±0.30 % yr⁻¹, −1.09±0.25 % yr⁻¹ and −1.14±0.18 % yr⁻¹. To find possible reasons for the CO trends, the global-scale EMEP MSC-W chemical transport model has been used in a series of sensitivity scenarios. It is shown that the trends are consistent with the combination of a 20 % decrease in the anthropogenic CO emissions seen in Europe and North America during the 1996-2006 period and a 20 % increase in the anthropogenic CO emissions in East Asia, during the same time period. The possible impacts of CH₄ and biogenic volatile organic compounds (BVOCs) are also considered. The European and global-scale EMEP model have been evaluated against the measured CO and C₂H₆ partial columns from Jungfraujoch, Zugspitze, Bremen, Harestua, Kiruna and Ny-Ålesund. The European model reproduces, on average the measurements at the different sites fairly well and within 10–22 % deviation for CO and 14–31 % deviation for C₂H₆. Their seasonal amplitude is captured within 6–35 % and 9–124 % for CO and C₂H₆, respectively. However, 61–98 % of the CO and C₂₆ partial columns in the European model are shown to arise from the boundary conditions, making the global-scale model a more suitable alternative when modeling theses two species. In the evaluation of the global model the average partial columns for year 2006 have shown to be within 1–9 % and 37–50 % for CO and C₂₆, respectively. The global model sensitivity for assumptions done in this paper is also analyzed

Variation of atmospheric CO, δ 13 C, and δ 18 O at high northern latitude during 2004–2009: Observations and model simulations

“…The results of Angelbratt et al . [] also found a similar decreasing trend in CO from the European stations during 1996–2006 (−0.45 ~ −1 ppbv/yr).…”

“…Both the model and observations show a decreasing trend of [CO] during the 6 years, while the modeled trend (À1.4 ± 0.6 ppbv/yr) is slower than the observation (À3.0 ± 1.0 ppbv/yr). The results of Angelbratt et al [2011] also found a similar decreasing trend in CO from the European stations during 1996-2006 (À0.45~À1 ppbv/yr).…”

“…A more recent study of atmospheric CO at Spitsbergen, Norway (79°N), and Journal of Geophysical Research: Atmospheres 10.1002/2015JD023191 Alert, Canada (81°N), also indicated a considerable interannual variation of annual minimum concentrations [Rockmann et al, 2002]. Also, raising the efficiency of fossil fuel use and global effort to control CO emission from automobiles and industrial activity has shown a decreasing trend in the extratropical Northern Hemisphere [Angelbratt et al, 2011;Duncan et al, 2007;Kumar et al, 2013].…”

Discrepancy between simulated and observed ethane and propane levels explained by underestimated fossil emissions

“…Over the past decade the inventories do not fully account for an abrupt increase in the exploitation of unconventional natural gas in the United States 3,4 and therefore likely underestimate present-day emissions 3,4,[12][13][14][15][16][17][18][19][20][21][22][23] . Recent atmospheric model simulations applying current global emission inventories tend to underestimate observed ethane and propane concentrations in wintertime in the Northern Hemisphere [3][4][5]7,12,[24][25][26][27][28][29] .…”

“…Fugitive emission is the main fossil fuel NMHC source and includes venting and flaring, evaporative losses, and equipment leaks but not fuel combustion. Changes in these particular emissions are regarded as the main cause of observed ethane trends 3,4,26,[30][31][32][33][34] . Recent studies 9,35 calculated fugitive fossil fuel emissions from oil, natural gas, and coal systems for ethane based on a joint inventory and atmospheric box-model approach.…”