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  • Author or Editor: W. Junkermann x
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W. Junkermann and J. M. Burger


A new instrument for the in situ measurement of formaldehyde with online concentration output was built on the base of the Hantzsch chemistry fluorimetric detection of formaldehyde in liquid phase. The instrument was specially designed for applications in a fast-changing environment, for example, in airborne research. Individual instrument components were optimized to reduce size, weight, and power consumption and to improve response time. The small size, battery-operated system was shown to reach good performance, stable sensitivity, and detection limits of <100 ppt for temperatures between 0° and 35°C during aircraft flight missions in field campaigns in the Italian Po Valley. The instrument proved its performance with formaldehyde mixing ratios ranging from 0.5 to 25 ppb.

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A. R. Webb, A. F. Bais, M. Blumthaler, G-P. Gobbi, A. Kylling, R. Schmitt, S. Thiel, F. Barnaba, T. Danielsen, W. Junkermann, A. Kazantzidis, P. Kelly, R. Kift, G. L. Liberti, M. Misslbeck, B. Schallhart, J. Schreder, and C. Topaloglou


Results are presented from the Actinic Flux Determination from Measurements of Irradiance (ADMIRA) campaign to measure spectral global UV irradiance and actinic flux at the ground, beneath an atmosphere well defined by supporting measurements. Actinic flux is required to calculate photolysis rates for atmospheric chemistry, yet most spectral UV measurements are of irradiance. This work represents the first part of a project to provide algorithms for converting irradiances to actinic fluxes with specified uncertainties. The campaign took place in northern Greece in August 2000 and provided an intercomparison of UV spectroradiometers measuring different radiation parameters, as well as a comprehensive radiation and atmospheric dataset. The independently calibrated spectroradiometers measuring irradiance and actinic flux agreed to within 5%, while measurements of spectral direct irradiance differed by 9%. Relative agreement for all parameters proved to be very stable during the campaign. A polarization problem in the Brewer spectrophotometer was identified as a problem in making radiance distribution measurements with this instrument. At UV wavelengths actinic fluxes F were always greater than the corresponding irradiance E by a factor between 1.4 and 2.6. The value of the ratio F : E depended on wavelength, solar zenith angle, and the optical properties of the atmosphere. Both the wavelength and solar zenith angle dependency of the ratio decreased when the scattering in the atmosphere increased and the direct beam proportion of global irradiance decreased, as expected. Two contrasting days, one clear and one with higher aerosol and some cloud, are compared to illustrate behavior of the F : E ratio.

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