A novel ozone sensor for direct eddy flux measurements

Abstract

Asmall, lightweight (1.5 kg) and fast-response ozone sensor for direct eddy flux measurements has been built. The basis for detection is the chemiluminescence of an organic dye adsorbed on dry silica gel in the reaction with ozone. The chemiluminescence is monitored with a cheap and small blue-sensitive photomultiplier. At a flow rate of 100 I min d the ozone sensor has a 90 % response time of significantly better than 0.1 s with a detection limit lower than 50 ppt at SIN = 3. There are no interferences from other atmospheric trace gases like NOx, H202 and PAN. Water vapour and SO2 enhance the chemiluminescence efficiency of the ozone sensor. Since their response times are 22 seconds and 30 minutes, respectively, no correlation between rapid ozone fluctuations and those of these two trace gases is noticed by the ozone sensor when operating at a frequency of 10 Hz.The ozone sensor was tested for several weeks in continuous measurements of ozone fluxes and deposition velocities over different croplands using the eddy correlation technique Good agreement was found between ozone dry deposition velocities derived from profile measurements and by eddy correlation.

A fast and precise chemiluminescence ozone detector for eddy flux and airborne application

“…Guesten et al (1992) observed a considerable enhancement of the sensor sensitivity by ∼40 % after abrupt changes of the absolute humidity from 0 to 1 %. The τ − 90 response time was estimated to ∼22 s. Although such sudden humidity changes do not occur in the atmosphere (at least not on stationary measurement platforms), this strong H 2 O cross-sensitivity might introduce a significant source of uncertainty at too rare calibration sequences.…”

“…(2) A device manufactured by the company GFAS is based on the instrument described by Schurath et al (1991) and Guesten et al (1992). It uses Coumarin-47 as dye and was sold until the year ∼2000.…”

Measurements of nitrogen oxides and ozone fluxes by eddy covariance at a meadow: evidence for an internal leaf resistance to NO<sub>2</sub>

“…Simultaneously, eddy covariance fluxes of O 3 were measured with a surface chemiluminescence instrument (Table 1) (Güsten et al, 1992;Güsten and Heinrich, 1996), which was mounted on the three-pod mast with its inlet mounted directly next to that of NO and NO 2 .…”

Civil Aircraft for the regular investigation of the atmosphere based on an instrumented container: The new CARIBIC system

“…The fast O 3 sensor is based on the chemiluminescence of O 3 on the surface of an organic dye adsorbed on silica gel powder deposited on a 1 cm diameter aluminum disk (Güsten et al, 1992). The measurement frequency is 10 Hz, which, at the cruising speed of ∼250 m/s, result in a high spatial resolution of merely ∼25 m. However, turbulence within the inlet tube causes mixing of air which degrades the spatial resolution to effectively 30-40 m distance, still ample for our purposes.…”