No abstract

Abstract. The measurement of water vapour concentration in the atmosphere is an ongoing challenge in environmental research. Satisfactory solutions exist for ground-based meteorological stations and measurements of mean values. However, carrying out advanced research of thermodynamic processes aloft as well, above the surface layer and especially in the atmospheric boundary layer (ABL), requires the resolution of small-scale turbulence. Sophisticated optical instruments are used in airborne meteorology with manned aircraft to achieve the necessary fast-response measurements of the order of 10 Hz (e.g. LiCor 7500). Since these instruments are too large and heavy for the application on small remotely piloted aircraft (RPA), a method is presented in this study that enhances small capacitive humidity sensors to be able to resolve turbulent eddies of the order of 10 m. The sensor examined here is a polymer-based sensor of the type P14-Rapid, by the Swiss company Innovative Sensor Technologies (IST) AG, with a surface area of less than 10 mm 2 and a negligible weight. A physical and dynamical model of this sensor is described and then inverted in order to restore original water vapour fluctuations from sensor measurements. Examples of flight measurements show how the method can be used to correct vertical profiles and resolve turbulence spectra up to about 3 Hz. At an airspeed of 25 m s −1 this corresponds to a spatial resolution of less than 10 m.

raturen oberhalb + 50°C zwei Signale fur Methylenkohlenstoffatome, bei tiefen Temperaturen ( 5 -25 "C) vier scharfe Signale. Demnach liegen von 15 b zwei Konformere nebena . X = H ; b . X = B r 14 15

The 1‐phenyl‐1‐(trimethylsilyl)ethyl cation is generated as a persistent species in solution and characterized experimentally by 1H, 13C, and 29Si NMR spectroscopy. The α‐silyl effect is elucidated by comparison with other benzyl cations, such as cumyl and 1‐phenylethyl cations. Concomitant quantum chemical calculations of structures, relative thermodynamic stabilities, chemical shifts, and the harmonic oscillator model of aromaticity (HOMA) indices are congruent with the analysis of the experimental NMR spectroscopy results; therefore, we conclude that, in benzyl cations, the α‐silyl substituent is stabilizing with respect to H, but destabilizing relative to a methyl group.

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