Evaluation of CMAQ modeling accuracy using satellite-retrieved trace gases and ground-observed lightning data.

摘要

Using OMI ozone profiles as the boundary conditions for CMAQ calculations significantly improves the agreement of the model prediction of ozone with ozonesonde observations during the IONS 2006 period. This improvement results from both representing the free-tropospheric ozone amounts more accurately and representing recirculating air masses more accurately. A simultaneous assessment of the OMI ozone profiles with the sondes indicates agreement to better than 10% throughout the free troposphere with 10--20% differences in the PBL. By modifying modeled O3 with OMI O3 throughout the model domain once a model-day, further improvement occurs, especially in the interior region where influences from the boundary condition are small.;Lightning is a particularly significant NOx, source in the middle and upper troposphere where NOx, is long-lived, typically at more dilute concentrations, and consequently more efficient at producing ozone than in the boundary layer where the majority of NOx, is emitted. We study the influence of lightning-produced NOx (LNO x) on the upper tropospheric ozone concentration by applying the National Lightning Detection Network (NLDN) lightning data as an extra NOx emission source to the CMAQ model. We estimate the total lightning NO x amount from NLDN CG flashes based on a set of assumptions (detection efficiency (DE) ∼95%, IC:CG ratio ∼ 3, LNOx production rate ∼ 500 moles N Per flash), and put them into 39 CMAQ model layers according to Pickering's vertical-distribution profile [Pickering et al., 1998]. LNOx contributes 27% to total NOx emission during July 15--September 7, 2006. Model prediction shows significant enhancement in upper tropospheric ozone concentration due to lightning-produced NO x above the southeastern and eastern U.S. A case study in Huntsville, AL, during August 2006 shows increased NO2 in the upper troposphere due to lightning-NOx injection and simulates corresponding ozone enhancement around same altitude. The improved ozone prediction is still lower than ozonesonde measurement.