An ozone enhancement in the nocturnal residual layer was observed by the Huntsville ozone lidar from the late evening to midnight on 4 October 2008. The well-correlated ozone, aerosol, water vapor, and wind structures suggest a low-level jet is responsible for this ozone enhancement. HYSPLIT backward trajectories support this conclusion with southerly transport suggesting Birmingham, AL as the source. Correspondingly, the higher increasing rate of surface ozone observed in the morning of 5 October can be explained by the entrainment into the mixed layer of higher ozone aloft on this day as compared with 4 October. This case study demonstrates the importance of continuous high-resolution lidar profiling for capturing short-duration ozone variations in the lower troposphere. Published by Elsevier Ltd.

A tropospheric ozone Differential Absorption Lidar system, developed jointly by The University of Alabama in Huntsville and the National Aeronautics and Space Administration, is making regular observations of ozone vertical distributions between 1 and 8 km with two receivers under both daytime and nighttime conditions using lasers at 285 and 291 nm. This paper describes the lidar system and analysis technique with some measurement examples. An iterative aerosol correction procedure reduces the retrieval error arising from differential aerosol backscatter in the lower troposphere. Lidar observations with coincident ozonesonde flights demonstrate that the retrieval accuracy ranges from better than 10% below 4 km to better than 20% below 8 km with 750-m vertical resolution and 10-min temporal integration.

A tropospheric ozone DIfferential Absorption Lidar (DIAL) system has been developed jointly by NASA and the University of Alabama at Huntsville (UAH). Two separated Nd:YAG pumped dye laser systems produce the laser pulses with wavelengths of 285 and 291 nm at 20 Hz frequency. The receiver is a Newtonian telescope with a 40 cm primary and a two-channel aft optics unit. The detection system currently uses photon counting to facilitate operations at the maximum achievable altitude. This lidar measures free-tropospheric ozone profiles between 4-10 km at Regional Atmospheric Profiling Laboratory for Discovery (RAPCD) in UAH campus (ASL 206 m) under both daytime and nighttime conditions. Frequent coincident ozonesonde flights and theoretical calculations provide evidence to indicate the retrieval accuracy ranges from approx.5% at 4 km to approx.60% at 10 km with 750-m vertical resolution and 30-minute integration. Three Hamamatsu 7400 PMTs and analog detection technique will be added on the current system to extend the measurement to approx.100 m above ground to monitor the PBL and lower tropospheric ozone variations.

3 Shi Kuang 1., John Burris :, Michael J. Newehurch 1, and Steve Johnson 3 4 1University of Alabama in Huntsville, 320 Sparkman Dr., Huntsville, Alabama 35805, USA 5 2NASA-Goddard Space Flight Center, Code 694, Greenbelt, Maryland 20771, USA 6 _NASA-Mashall Space Flight Center, Office Code VP61, Huntsville, Alabama 35812, USA 7 *Corresponding author: _tang@nsstc.uah.edu 8 ABSTRACT: A tropospheric ozone Differential Absorption Lidar (DIAL) system, 9 developed jointly by NASA and the University of Alabama at Huntsville (UAH), 10 measures free-tropospheric ozone Fofiles between 4-10 km. Located at 192 meters 11 altitude in the Regional Atmospheric Profiling Laboratory for Discovery (RAPCD) on the 12 UAH campus in Huntsville, AL, USA, this tropospheric ozone lidar operates under both 13 daytime and nighttime conditions. Frequent coincident ozonesonde flights and theoretical 14 calculations provide evidence to indicate the retrieval accuracy ranges from better than 8% 15 at 4km to 40%-60% at 10 kin with 750-m vertical resolution and 30-minute integration. 16 With anticipated improvements to allow retrievals at both higher and lower altitudes, this 17 ozone lidar, along with co-located aerosol and Doppler Wind Lidars, will provide a unique 18 dataset for investigations of PBL and free-tropospheric chemical and dynamic processes. 19