An elevated reservoir of air pollutants over the Mid-Atlantic States during the 2011 DISCOVER-AQ campaign: Airborne measurements and numerical simulations

Aircraft and ozonesonde measurements detected ∼120 ppbv ozone at 800 m altitude, but ∼80 ppbv ozone near the surface. High concentrations of other pollutants were also observed around the ozone peak: ∼300 ppbv CO at 1200 m, ∼2 ppbv NO₂ at 800 m, ∼5 ppbv SO₂ at 600 m, and strong aerosol optical scattering (2 × 10⁻⁴ m⁻¹) at 600 m.

These results suggest that the elevated reservoir is a mixture of automobile exhaust (high concentrations of O₃, CO, and NO₂) and power plant emissions (high SO₂ and aerosols). Back trajectory calculations show a local stagnation event before the formation of this elevated reservoir. Forward trajectories suggest an influence on downwind air quality, supported by surface ozone observations on the next day over the downwind PA, NJ and NY area.