Planetary Boundary Layer height and surface ozone verification in the NOAA/EPA Air Quality Forecast System

Planetary Boundary Layer (PBL) height is one of those meteorological parameters that are not easy to measure, and no observations on regular basis exist. On the other hand, PBL physics plays a significant role in numerical weather prediction, and PBL height is one of the most important parameters in atmospheric modeling. Specifically, this parameter has a major impact on air quality forecasting. Surface ozone concentrations predicted by a chemical transport model, are strongly dependent on PBL height estimates used in the model. This study attempts to verify the accuracy of PBL height prediction and its influence on surface ozone concentration forecasts. The air quality forecast (AQF) system is based on the NWS/NCEP Eta meteorological model and the U.S. EPA CMAQ air quality model. It has been operationally implemented at NWS/NCEP in September 2004 and is run twice per day at a 12 km resolution. In CMAQ ozone predictions, PBL height computed in the Eta model is used. To verify the PBL height, the RAOBS observational data are used. Several methods of PBL height estimation from standard radiosonde data are explored. Estimated observed PBL heights as well as computed Eta PBL heights are incorporated into NCEP's Forecast Verification System (FVS), and different statistical parameters are calculated. Spatial distribution of PBL height errors is investigated. The dependencies between predicted PBL height accuracy and surface ozone concentration errors are studied.

Disclaimer: The research presented here was performed under the Memorandum of Understanding between the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) and under agreement number DW13921548. Although it has been reviewed by EPA and NOAA and approved for publication, it does not necessarily reflect their views or policies.