Johannes Keller

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Imaging spectrometry has the potential of remotely detecting atmospheric trace gases on the basis of their absorption of radiation. Ozone absorbs particulary in the ultraviolet and visible range of the spectrum, whereas water vapor has strong absorption features in the near infrared. Hence, spectrometry is expected to be a promising tool to extract these(More)
The operational aerosol product of the Multi-angle Imaging SpectroRadiometer (MISR) is available only for a grid cell size of 17.6 km. This spatial resolution is too coarse for studies in complex terrains like Switzerland. An algorithm for retrieving simultaneously aerosol and surface optical properties at a resolution of 1.1 km was developed. It uses MISR(More)
Water vapor is one of the main forces for weather development as well as for mesoscale air transport processes. The monitoring of water vapor is therefore an important aim in remote sensing of the atmosphere. Current operational systems for water vapor detection use primarily the emission in the thermal infrared (AVHRR, GOES, ATSR, Meteosat) or in the(More)
We introduce a new density for the representation of quantum states on phase space. It is constructed as a weighted difference of two smooth probability densities using the Husimi function and first-order Hermite spectrograms. In contrast to the Wigner function, it is accessible by sampling strategies for positive densities. In the semiclassical regime, the(More)
Two methods for the measurement of the column water vapor in the atmosphere are compared with respect to their usefulness for imaging spectrometer campaigns. First, in situ measurements of 26 radiosonde launches are integrated with height to obtain the water vapor column. Second, simultaneous ground irradiance measurements using a sun photometer are(More)
In this thesis we study the quantum propagation of Heisenberg observables for the time-dependent semiclassical Schrödinger equation. We develop a numerical approximation for the evolution of expectation values of Weyl quantized observables by using Husimi functions. The suggested method builds on a discretized version of a second order Egorov type(More)