Measurements of OCS and CS₂ in the free troposphere

Abstract

Distributions of the ambient atmospheric mixing ratios of OCS and CS2 were determined from grab samples collected at altitudes ranging from 6 to 8 km (20,000 to 26,000 feet) during an aircraft flight between San Juan, Puerto Rico, and Albany, New York (July 11–12, 1982). No spatial variation is observed for OCS mixing ratios at these altitudes and latitudes within the uncertainty of the collection and analysis techniques. The average OCS mixing ratio is 517±65 pptv, where the standard deviation includes atmospheric as well as experimental variability. CS2 values, on the other hand, show considerable spatial variability that may be correlated with intense local cumulonimbus activity.

Atmospheric trace gas analysis using matrix isolation-fourier transform infrared spectroscopy

“…There is a loss of 10-15% of CS2 between the two sets of analyses which may be significant. The mean and standard deviation of the OCS mixing ratios (excluding the polluted 17 °o samples) are 491 + 60 ppt, which agree well with the values of Torres et al (1980) and Carroll (1985) of 509 -+ 63 ppt and 517 + 65 ppt, respectively. This is consistent with the view that OCS is well-mixed in the free troposphere (Khalil and Rasmussen, 1984).…”

Vehicular emission of volatile organic compounds (VOCs) from a tunnel study in Hong Kong

“…Emission of OCS from vehicles is one of such example (Fried et al, 1992). The average concentrations of OCS at the inlet and outlet of the tunnel were 970 pptv and 1200 pptv, respectively, which is higher than that of free troposphere (510 ppt) (Carroll, 1985) and similar to that in Beijing, China (1340 ppt) (Mu et al, 2002).…”

Ground‐based infrared spectroscopic measurements of carbonyl sulfide: Free tropospheric trends from a 24‐year time series of solar absorption measurements

“…Carbonyl sulfide (OCS) is the predominant sulfur‐bearing gas in the remote troposphere with a global average concentration of about 500 parts per trillion by volume (pptv or 10 −12 ppv) [e.g., Sandalls and Penkett , 1977; Maroulis et al , 1977; Torres et al , 1980; Rasmussen et al , 1982a, 1982b; Carroll , 1985; Johnson and Harrison , 1986; Johnson et al , 1993; Mihalopoulos et al , 1991; Thornton et al , 1996; Notholt et al , 2000] and a lifetime of about 4 years [ Chin and Davis , 1995; Watts , 2000], though estimates from measurements and models range from 1–7 years. Despite a high tropospheric abundance, its low reactivity and limited knowledge of the strengths of its sources and sinks have resulted in an uncertainty in its chemistry and long‐term trend.…”

“…However, Turco et al [1980] concluded that as much as 50% of OCS emissions might originate from anthropogenic emissions. Other estimates of the mean IHR are as high as 1.25 [ Bingemer et al , 1990], though most estimates are lower [ Carroll , 1985; Johnson and Harrison , 1986; Mihalopoulos et al , 1991; Griffith et al , 1998; Xu et al , 2001; Sturges et al , 2001]. …”