Analysis of Lower Tropospheric Trace Gas Profiles Obtained from a Unique Combination of Aircraft and Tethered Balloon Observations

Vertical profiles of ozone and NOx obtained using Millersville University's tethered balloon system are presented from the July 2011 Edgewood, Maryland and the September 2013 Houston, Texas deployments of the NASA DISCOVER-AQ mission. These balloon profiles can be used to connect aircraft data from the lowest portion of NASA's P3-B spirals (~300m AGL) to the surface, thus creating complete profiles from the surface to 3 -5 km AGL. The balloon data are essential for establishing a unique data set for the lower, but highly variable part of the boundary layer. A UV ozone analyzer and a chemiluminescent NOx analyzer were attached on the balloon during profiles that were coincident in time with the P-3B spirals, generating an overlap of atmospheric chemistry measurements over the vertical gradient with the P3-B aircraft. In the Houston deployment an NO2 sonde was also flown on the tethered balloon. In both locations, the tethered balloon site was in the vicinity of coastal regions providing vertical profiles near a convergence zone of air pollution during a sea or bay breeze. Localized late day pollutant peaks were observed when the sea or bay breeze convergence zone was over the sampling site. While the overlap provides a continuous vertical profile, investigated here are instances where the P3-B and tethered balloon measurements do not agree. SODAR was used to measure wind speed and wind direction to an altitude of ~400m AGL. Additionally, the tethersonde on the balloon provides pressure, altitude, temperature, relative humidity, wind speed, and wind direction. Complete vertical profiles are achieved by time syncing the chemistry analyzers on board the balloon with the tethersonde's meteorological measurements. Analysis of the combined aircraft and balloon vertical profiles of ozone and NOx provides insight to better understand the role of local and mesoscale features on regional air quality.