Ozone Development and Destruction in the Planetary Boundary Layer during DISCOVER-AQ 2011 at the Beltsville, MD, site

During the DISCOVER-AQ experiment several platforms were used to investigate the spatial and temporal distribution ozone in the Beltsville, MD (39.054°N; 76.877 °W), including ozonesonde, tethered balloon, and ground-based observations. With this unique dataset ozone production and destruction can be investigated in the Planetary Boundary Layer (PBL), in the residual layer, and within the PBL in between cold front passages. On selected days, ozonesondes were launched two or three times. A case study entailed a high pressure associated with a heat wave for most of the days. One particular day, 7/20/2011, we observed high concentrations of ozone in the air column extending from the surface to the tropopause. The following days also showed elevated ozone concentrations, but they were confined within the PBL during daytime. Tethersonde balloon flights provided information about the ozone distribution in the surface layer (lowest 200 m of the atmosphere). The hourly profiles were used to investigate the transition periods from day-to-night and nigh-to-day, which were the times when the convective (CBL) and the stable boundary layers (SBL) formed. For selected soundings, levels of nitric oxide profiles were measured. From the micrometeorological tower, we analyzed the ozone mixing ratios and turbulent flux from eddy covariance system located close to the balloon launching site. From turbulent flux and potential temperature profile we determined the development of the SBL and CBL at dawn and sunset. Ozone concentrations at the micrometeorological tower also provided ozone data to compare with ozonesonde and tethered balloon information. In this presentation, we will evaluate the hypothesis that ozone levels during mid afternoon are good estimates of the ozone mixing ratio values in the residual layer of the following night.