Measurements of trace gases and photolysis frequencies during SLOPE96 and a coarse estimate of the local OH concentration from HNO₃ formation

Abstract

Abstract. The Schauinsland Ozone Precursor Experiment (SLOPE96) campaign was conducted in June 1996 to study the physicochemical transformation of pollutants and the production of photooxidants during transport from the city of Freiburg to the Schauinsland mountain. For this purpose, chemical surface measurements were made at the entrance of the valley Groges Tal, and close to the Schauinsland summit, at 1200 m altitude on a saddle at the end of the valley. In addition, measurements of ozone, NO2, and meteorological parameters were made on two tethered balloons and aboard a small aircraft. This paper describes the experimental setup and the measurements of ozone, odd-nitrogen compounds, carbonyl compounds, CO, and photolysis frequencies made during SLOPE96. The various instruments used on the different platforms were harmonized on the basis of intercomparison experiments in order to achieve a consistent picture. Large precursor concentrations from the nearby city of Freiburg are transported to Schauinsland in a valley wind system during stagnant high-pressure conditions. These conditions occurred only on 2 days of the campaign, and only 1 day (June 5) was predictable enough to allow for deployment of the aircraft and the balloons.

Measurements of total odd nitrogen (NO<sub>y</sub>) aboard MOZAIC in-service aircraft: instrument design, operation and performance

“…During long series of laboratory tests for this and other gold converters deployed, e.g., at Schauinsland (Flocke et al, 1998;Pätz et al, 2000) and aboard the UK research aircraft C-130 (Gerbig et al, 1996), we always found the same behaviour in terms of the temperature dependence of the conversion efficiency for NO 2 and HNO 3 , as well as PAN and other organic nitrates. Therefore, only the conversion efficiency for NO 2 is checked in flight.…”

Intercomparison of four different in-situ techniques for ambient formaldehyde measurements in urban air

“…They recommended carrying out in-situ calibrations with gas-phase standards introduced at the instruments' air inlets. - Pätz et al (2000) measured formaldehyde with TDLAS and Hantzsch during a field campaign at Schauinsland mountain. The concentrations measured by both instruments were very close to the theoretical concentration of the employed reference gas.…”

Comparison of airborne measured and calculated spectral actinic flux and derived photolysis frequencies during the PEM Tropics B mission

“…Past photolysis frequency determinations [ Bahe , 1980] have been performed using three principal methods that have been reported in the literature since the early 1970s. The three different methods are chemical actinometry [ Dickerson et al , 1979, 1982; Bahe et al , 1979; Blackburn et al , 1992; Bairai and Stedman , 1992; Shetter et al , 1992, 1996; Parrish et al , 1983; Lantz et al , 1996], filter radiometry [ Hofzumahaus et al , 1992; Junkermann et al , 1989; Volz‐Thomas et al , 1996], and spectroradiometry [ Müller et al , 1995; Shetter and Müller , 1999; Hofzumahaus et al , 1999; Pätz et al , 2000]. Discussions of the history and advantages and disadvantages of the three techniques were presented previously by Shetter and Müller [1999].…”

“…Spectroradiometer measurements of photolysis frequencies have been reported recently by Pätz et al [2000], Hofzumahaus et al [1999], Shetter and Müller [1999], Müller et al [1995], McElroy [1995], and McElroy et al [1995]. Spectroradiometers can determine solar irradiance or actinic flux as a function of wavelength.…”