Measurements of CO and O₃ at Shemya, Alaska

Abstract

Abstract. In situ measurements of surface CO were conducted from June 1994 to May 1995, and surface ozone was measured from February to May, 1995, at Shemya, Alaska (52o44'N, 174o06'E) using nondispersive infrared-gas filter correlation (GFC) and UV absorption spectroscopy, respectively. Over the same period, air samples were collected in flasks for analysis of CO and other trace gases as part of the NOAA-CMDL cooperative air sampling network. We compared the continuous GFC measurements with the National Oceanic and Atmospheric Administration Climate Monitoring and Diagnostics Laboratory (NOAA-CMDL) flask data. Over this 1-year period, CO mixing ratios varied between 60 and 250 parts per billion by volume (ppbv). Within this range, the comparison between the two measurements is quite good, with an overall R 2 of 0.953 and an average difference of 3.1%. A seasonal cycle is apparent in the CO data, with a springtime maximum and a summer minimum. Synoptic influences on the data include transport from the lower-latitude Pacific, bringing air with very low CO mixing ratios to Shemya, and, occasionally, transport from industrial areas in east Asia, including northern China, Japan, and eastern Russia. A scatterplot of CO versus 03 using all the data shows essentially no relationship at this remote site. This result implies that the primary sources and sinks for these trace gases are different at this location. However, during a few 12-to 48-hour periods in fall and late spring, enhancements in CO or in both CO and 03 were observed. During these periods, isentropic back trajectories indicate transport from the west and southwest. However, the trajectories are often difficult to interpret due to looping and are of short duration due to impact at the surface. These complexities are associated with the presence of cyclonic systems in the region. The local meteorological data suggest that the enhanced concentrations occurred around the time when these cyclonic systems passed near the sampling site. Synoptic surface pressure maps indicate that these cyclonic systems formed or crossed industrial regions in east Asia and passed near Shemya on their way to the Bering Sea. This process suggests a role for transport of anthropogenic pollutants by cyclonic systems moving northward along the western edge of the Pacific Ocean.

Long-term measurements of aerosol and carbon monoxide at the ZOTTO tall tower to characterize polluted and pristine air in the Siberian taiga

“…As is also the case for absorption, the higher CO in winter may be due to the higher static stability of the lower troposphere and higher anthropogenic emissions from heating. In addition, the lower summer CO signal (about 80 ppb lower than during winter), is partly due to the much shorter lifetime of CO in summer because of faster photochemical turnover rates (Jaffe et al, 1998;. Moreover, due to its relatively long lifetime (compared to BC) in the atmosphere, CO has a substantial background concentration, which ranges from 92 ppb in summer up to 160 ppb in early spring (Table 3).…”

Influence of long‐range‐transported pollution on the annual and diurnal cycles of carbon monoxide and ozone at Cheeka Peak Observatory

“…This will likely increase the amount of O 3 exported to North America [ Jacob et al , 1999; Yienger et al , 2000]. Numerous episodes of pollution of Asian origin have already been measured in the North Pacific and on the west coast of North America [ Jaffe et al , 1998, 1999, 2001, 2003a; Kotchenruther et al , 2001a; Price et al , 2003; Jaeglé et al , 2003]. However, to what extent these episodes control the background seasonality of O 3 and other pollutants like carbon monoxide (CO) in the boundary layer is still unclear.…”

Measurements of surface ozone at semi-arid site Anantapur (14.62°N, 77.65°E, 331 m asl) in India

“…Ozone levels at any location are governed mainly by two factors namely local chemistry and transport (Oltmans and Levy 1994;Jaffe et al 1998;Lal et al 1998). Near the earth's surface, ozone is mainly produced by photochemistry involving pollutants which are released from various anthropogenic activities like industrialization, biomass burning, automobile exhausts, etc.…”