Laser-induced fluorescence-based detection of atmospheric nitrogen dioxide and comparison of different techniques during the PARADE 2011 field campaign

摘要

GANDALF (Gas Analyzer for Nitrogen Dioxide Applying Laser-inducedFluorescence), a new instrument for the detection of nitrogen dioxide basedon the laser-induced fluorescence (LIF) technique, is presented in thispaper. GANDALF is designed for ground-based and airborne deployment with arobust calibration system. In the current set-up, it uses a multi-mode diodelaser (447–450 nm) and performs in situ, continuous, and autonomousmeasurements with a laser pulse repetition rate of 5 MHz. The performance ofGANDALF was tested during the summer of year 2011 (15 August–10 September) in afield experiment at Kleiner Feldberg, Germany. The location is within aforested region with an urban influence, where NOx levels were between 0.12and 22 parts per billion by volume (ppb). Based on the field results, thelimit of detection is estimated at 5–10 parts per trillion by volume(ppt) in 60 s at a signal-to-noise ratio (SNR) of 2. The overall accuracy andprecision of the instrument are better than 5 % (1σ) and0.5 %+3 ppt (1σ min−1), respectively. A comparison ofnitrogen dioxide measurements based on several techniques during the fieldcampaign PARADE 2011 is presented to explore methodic differences.