A novel ozone sensor for direct eddy flux measurements |
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| Authors: | Hans Güsten Günther Heinrich Ralf W H Schmidt Ulrich Schurath |
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| Institution: | (1) Institut für Meteorologie und Klimaforschung, Kernforschungszentrum/Universität Karlsruhe, 7500 Karlsruhe, Federal Republic of Germany;(2) Institut für physikalische Chemie und theoretische Chemie, Universität Bonn, 5300 Bonn, Federal Republic of Germany |
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| Abstract: | A small, 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 l min-1 the ozone sensor has a 90% response time of significantly better than 0.1 s with a detection limit lower than 50 ppt at S/N=3. There are no interferences from other atmospheric trace gases like NOx, H2O2 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. |
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| Keywords: | Ozone sensor chemiluminescence eddy correlation eddy flux dry deposition |
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