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A new helicopter payload designed to overcome rotor downwash allows better than 10 cm resolution for turbulence and microphysical observations in boundary layer clouds.

Abstract. During SPURT (Spurenstofftransport in derTropopausenregion, trace gas transport in the tropopause region) we performed measurements of a wide range of trace gases with different lifetimes and sink/source characteristics in the northern hemispheric upper troposphere (UT) and lowermost stratosphere (LMS). A large number of in-situ instruments were deployed on board a Learjet 35A, flying at altitudes up to 13.7 km, at times reaching to nearly 380 K potential temperature. Eight measurement campaigns (consisting of a total of 36 flights), distributed over all seasons and typically covering latitudes between 35 • N and 75 • N in the European longitude sector (10 • W-20 • E), were performed. Here we present an overview of the project, describing the instrumentation, the encountered meteorological situations during the campaigns and the data set available from SPURT. Measurements were obtained for N 2 O, CH 4 , CO, CO 2 , CFC12, H 2 , SF 6 , NO, NO y , O 3 and H 2 O. We illustrate the strength of this new data set by showing mean distributions of the mixing ratios of selected trace gases, using a potential temperature-equivalent latitude coordinate system. The observations reveal that the LMS is most stratospheric in character during spring, with the highest mixing ratios of O 3 and NO y and the lowest mixing ratios of N 2 O and SF 6 . The lowest mixing ratios of NO y and O 3 are observed during autumn, together with the highest mixing ratios of N 2 O and SF 6 indicating a strong tropospheric influence. For H 2 O, however, the maximum concentrations in the LMS are found during summer, suggesting unique (temperatureCorrespondence to: A. Engel (an.engel@meteor.uni-frankfurt.de) and convection-controlled) conditions for this molecule during transport across the tropopause. The SPURT data set is presently the most accurate and complete data set for many trace species in the LMS, and its main value is the simultaneous measurement of a suite of trace gases having different lifetimes and physical-chemical histories. It is thus very well suited for studies of atmospheric transport, for model validation, and for investigations of seasonal changes in the UT/LMS, as demonstrated in accompanying and elsewhere published studies.

Abstract. During the SATURN experiment, which took place from 27 May to 14 June 2002, new particle formation in the continental boundary layer was investigated. Simultaneous ground-based and tethered-balloon-borne measurements were performed, including meteorological parameters, particle number concentrations and size distributions, gaseous precursor concentrations and SODAR and LIDAR observations.Newly formed particles were observed inside the residual layer, before the break-up process of the nocturnal inversion, and inside the mixing layer throughout the break-up of the nocturnal inversion and during the evolution of the planetary boundary layer.

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