DIFFERENTIAL ABSORPTION LIDAR (DIAL)

Kuang, S., J. Burris, M. J. Newchurch, S. Johnson (2007), Differential Absorption Lidar (DIAL) Measurements of Free-Tropospheric Ozone, submitted to J. Atmos. Oceanic Technol. Full Text

A tropospheric ozone DIfferential Absorption Lidar (DIAL) system, developed jointly by NASA and the University of Alabama at Huntsville (UAH), measures free-tropospheric ozone profiles between 4-10 km. Located at 192 meters altitude in the Regional Atmospheric Profiling Laboratory for Discovery (RAPCD) on the UAH campus in Huntsville, AL, USA, this tropospheric ozone lidar operates under both daytime and nighttime conditions.  Frequent coincident ozonesonde flights and theoretical calculations provide evidence to indicate the retrieval accuracy ranges from better than 8% at 4km to 40%-60% at 10 km with 750-m vertical resolution and 30-minute integration.  With anticipated improvements to allow retrievals at both higher and lower altitudes, this ozone lidar, along with co-located aerosol and Doppler Wind Lidars, will provide a unique dataset for investigations of PBL and free-tropospheric chemical and dynamic processes.

DIAL daytime measurement at 13:22 local time, Sep. 16, 2006. (a) 285nm raw, background-and-dead-time (BG & DT) corrected, and fully corrected data. The raw data were integrated over 36000 shots, 30 min for 20Hz repetition frequency. (b) Difference, (model-data)/model, between 285 fully corrected data and model. (c) 291nm raw, dead-time-and-background corrected, and fully corrected data. (d) Difference, (model-data)/model, between 291 fully corrected data and model. (e) Comparison of ozonesonde measurement and DIAL and with single wavelength retrievals with 750 m vertical resolution. The balloon ozonesonde was launched at 13:16 local time and also provided the temperature and pressure profiles to calculate single wavelength retrieval, correct ozone absorption cross section and Rayleigh effects in Dial retrieval. The ±10% uncertainty of the ozonesonde is represented by gray envelope. The error bars represent the 1-sigma statistical uncertainty of Dial retrieval.