The tropospheric distribution and budget of ethane

Abstract

Abstract. From about 1500 measurements of ethane in the remote troposphere the longitudinally and vertically averaged latitudinal and seasonal variability of ethane was derived. To improve the data coverage, several data sets from literature were included. There are only very few data sets available for the southern hemisphere. Nevertheless, the uncertainty of the average seasonal/latitudinal ethane profile is estimated to less than 30%. The global annually averaged ethane mixing ratio is 860 ppt. There is a strong interhemispheric gradient with an average north/south ratio of 3.5. Within the northern hemisphere there is an average gradient from the highest annual mean value of 2500 ppt around 65øN to about 600 ppt at the equator. In the southern hemisphere there is only a small gradient at low latitudes and at middle and high southern latitudes no significant gradient can be seen. In both hemispheres a significant seasonal cycle with highest mixing ratios in late winter is observed. The ethane source strength needed to balance the atmospheric budget of ethane is estimated to 15.5 Tg/yr, with most of the emissions in the northern hemisphere. An independent estimate of the sources indicate that most of the emissions are due to natural gas losses (6 Tg/yr) and biomass burning (6.4 Tg/yr). This is also compatible with the latitudinal and seasonal variation of the atmospheric ethane removal rates. However, these estimates have substantial uncertainties and it should be noted that the role of the biosphere for the atmospheric budget of ethane is presently not understood.

Extensive regional atmospheric hydrocarbon pollution in the southwestern United States

“…Using similar conditions to the CH 4 calculations, an emission rate of 0.3-0.5 Tg per year is calculated for ethane. By comparison, global natural gas emissions are believed to release 6 Tg of ethane yr Ϫ1 out of a global ethane budget of 13-15.5 Tg per year (17,18).…”

Large‐scale latitudinal and vertical distributions of NMHCs and selected halocarbons in the troposphere over the Pacific Ocean during the March‐April 1999 Pacific Exploratory Mission (PEM‐Tropics B)

“…Fast response in situ measurements of CO were made spectroscopically using a folded-path, differential absorption, [Rudolph, 1995]. Figure 2 and Table I show that north of 10øN, absolute mixing ratios of ethane, ethyne, and propane, were significantly higher for the lower two altitude ranges during PEM-Tropics B compared to PEM-Tropics A. Mixing ratios of C2C14 and CH3C1 were also significantly greater during PEM-Tropics B at low altitudes, but only slightly higher at mid altitudes.…”

Five years of CO, HCN, C<sub>2</sub>H<sub>6</sub>, C<sub>2</sub>H<sub>2</sub>, CH<sub>3</sub>OH, HCOOH and H<sub>2</sub>CO total columns measured in the Canadian high Arctic

“…The sources of C 2 H 6 are natural gas and fossil fuel emissions (Singh and Zimmerman, 1992). C 2 H 2 main sources include natural gas, biofuel combustion products and biomass burning emissions (Gupta et al, 1998;Logan et al, 1981;Rudolph, 1995;Xiao et al, 2007;Zhao et al, 2002). CO, C 2 H 6 and C 2 H 2 are removed by oxidation via OH reaction (Logan et al, 1981), leading to atmospheric lifetimes of approximately fifty-two days (Daniel and Solomon, 1998), eighty days (Xiao et al, 2008) and two weeks in the atmosphere (Xiao et al, 2007), respectively.…”