Atmospheric chemistry measurements at Whiteface Mountain, NY: Ozone and reactive trace gases

Abstract

Measurements of ozone and reactive trace gases spanning four decades at the Whiteface Mountain summit observatory are presented. Ozone (O3) measurements began in the mid-1970’s, and acid rain and O3 precursor gas measurements became routine in the late 1980’s and early 1990’s. Measurements at the lower altitude lodge level have also been performed routinely since about 2000. The 40-year O3 record shows up and down fluctuations through the 1980’s, a relatively stable period into the early 2000’s, and indications of a decreasing trend over the past ten years. Sulfur dioxide (SO2) and carbon monoxide (CO) trends are clearly decreasing over the roughly 25-year period of measurements at the summit observatory. Oxides of nitrogen (NOy and NO2) show rather more complicated trends, increasing to a maximum in the mid-2000’s, and decreasing sharply until 2011 with slight increases in concentration since then. Wind rose analysis shows the greatest contribution to high concentrations of precursor gases are from the west, southwest, and southern sectors, with SO2 and oxides of nitrogen having the most sharply defined high pollution sectors. Seasonal variations of trace gas concentrations at the summit and lodge levels are also examined. Ozone concentrations are highest in the spring months at both locations, and higher at the summit than the lodge. In contrast precursor gases (SO2 and NOx) show highest concentrations in winter months with the lodge consistently higher than the summit.