4 results
Search Results
Now showing 1 - 4 of 4
- ItemMultichannel analysis of correlation length of SEVIRI images around ground-based cloud observatories to determine their representativeness(München : European Geopyhsical Union, 2015) Slobodda, J.; Hünerbein, A.; Lindstrot, R.; Preusker, R.; Ebell, K.; Fischer, J.Images of measured radiance in different channels of the geostationary Meteosat-9 SEVIRI instrument are analysed with respect to the representativeness of the observations of eight cloud observatories in Europe (e.g. measurements from cloud radars or microwave radiometers). Cloudy situations are selected to get a time series for every pixel in a 300 km × 300 km area centred around each ground station. Then a cross correlation of each time series to the pixel nearest to the corresponding ground site is calculated. In the end a correlation length is calculated to define the representativeness. It is found that measurements in the visible and near infrared channels, which respond to cloud physical properties, are correlated in an area with a 1 to 4 km radius, while the thermal channels, that correspond to cloud top temperature, are correlated to a distance of about 20 km. This also points to a higher variability of the cloud microphysical properties inside a cloud than of the cloud top temperature. The correlation length even increases for the channels at 6.2, 7.3 and 9.7 μm. They respond to radiation from the upper atmospheric layers emitted by atmospheric gases and higher level clouds, which are more homogeneous than low-level clouds. Additionally, correlations at different distances, corresponding to the grid box sizes of forecast models, were compared. The results suggest the possibility of comparisons between instantaneous cloud observations from ground sites and regional forecast models and ground-based measurements. For larger distances typical for global models the correlations decrease, especially for short-wave measurements and corresponding cloud products. By comparing daily means, the correlation length of each station is increased to about 3 to 10 times the value of instantaneous measurements and also the comparability to models grows.
- ItemTarget ion and neutral spread in high power impulse magnetron sputtering(New York, NY : Inst., 2022) Hajihoseini, H.; Brenning, N.; Rudolph, M.; Raadu, M.A.; Lundin, D.; Fischer, J.; Minea, T. M.; Gudmundsson, J.T.In magnetron sputtering, only a fraction of the sputtered target material leaving the ionization region is directed toward the substrate. This fraction may be different for ions and neutrals of the target material as the neutrals and ions can exhibit a different spread as they travel from the target surface toward the substrate. This difference can be significant in high power impulse magnetron sputtering (HiPIMS) where a substantial fraction of the sputtered material is known to be ionized. Geometrical factors or transport parameters that account for the loss of produced film-forming species to the chamber walls are needed for experimental characterization and modeling of the magnetron sputtering discharge. Here, we experimentally determine transport parameters for ions and neutral atoms in a HiPIMS discharge with a titanium target for various magnet configurations. Transport parameters are determined to a typical substrate, with the same diameter (100 mm) as the cathode target, and located at a distance 70 mm from the target surface. As the magnet configuration and/or the discharge current are changed, the transport parameter for neutral atoms ζ tn remains roughly the same, while transport parameters for ions ζ ti vary greatly. Furthermore, the relative ion-to-neutral transport factors, ζ ti / ζ tn, that describe the relative deposited fractions of target material ions and neutrals onto the substrate, are determined to be in the range from 0.4 to 1.1.
- ItemOverview of the Earthcare L2 lidar retrieval chain(Les Ulis : EDP Sciences, 2016) van Zadelhoff, Gerd-Jan; Donovan, D.; Wandinger, U.; Daou, D.; Horn, S.; Hunerbein, A.; Fischer, J.; von Bismarck, J.; Filipitsch, F.; Docter, N.; Eisinger, M.; Lajas, D.; Wehr, T.In this paper an introduction to the planned L2 retrieval algorithms for the Earth Clouds and Radiation Explorer (EarthCARE) lidar ATLID is given. The ATLID instrument is a high spectral resolution lidar which will provide independent retrievals of extinction and backscatter profiles and will be launched in 2018. A short description of the intended operational ESA products is given together with the logic behind the choices made.
- ItemEntwicklung eines VCz-Züchtungsverfahrens für 150 mm SI GaAs-Kristalle : Schlußbericht ; Kurztitel: 150 mm GaAs-VCz Kristalle(Hannover : Technische Informationsbibliothek (TIB), 2003) Neubert, Michael; Czupalla, M.; Fischer, J.; Hojnacki, A.; Lange, R.-P.; Pilatzek, M.; Frank-Rotsch, Christiane; Kupfer, U.; Naumann, M.; Pietsch, M.; Rudolph, P.[no abstract available]