Measurements of nitrogen oxides at Barrow, Alaska during spring: Evidence for regional and northern hemispheric sources of pollution

Abstract

Total reactive nitrogen oxide (NOy) and NO were measured at the National Oceanic and Atmospheric Administration Geophysical Monitoring for Climatic Change (NOAA GMCC) site at Barrow, Alaska, for 5 weeks during the spring of 1989. The data demonstrate the existence of a complex array of pollution sources which influence arctic air chemistry. During periods when 10‐day back‐trajectories indicated southerly flow, median NOy concentrations ranged from 284 to 467 ppt. When the 10‐day back‐trajectories originated in the Arctic, median NOy, concentrations ranged from 617 to 734 ppt, providing evidence for the long‐range transport of pollutants to the Arctic known as “arctic haze.” The NOy concentrations observed during the spring background periods are significantly higher than previous measurements of NOy at Barrow taken during summer, regardless of where the air mass originated. These observations provide evidence for a greatly increased NOy lifetime during the colder months over a large region of the background troposphere as well as the presence of much higher NOy concentrations in the Arctic. During four 12–60 hour events, substantially elevated NOy were observed in air not impacted by emissions from the town of Barrow. During these four events, peak NOy concentrations of 3 to 16 ppb were observed. Other data, including NO, SO2, SO4, and meteorology, were used to help identify the source region for the elevated NOy levels. These data present a consistent picture which indicates that during certain periods, elevated NOy levels are associated with air coming from the Prudhoe Bay industrial area approximately 300 km to the ESE and demonstrate that this facility is a major source of nitrogen oxides, and possibly other air pollutants, to the Alaskan Arctic.