2018, Grinat, Michael, Epping, Dieter, Meyer, Robert, Szymkiewicz, Adam, Sadurski, A., Jaworska-Szulc, B.

In September 2009 two newly developed vertical electrode systems were installed in boreholes in the water catchment areas Waterdelle and Ostland at the North Sea island Borkum to monitor possible changes of the transition zone between the freshwater lens and the underlying saltwater. The vertical electrode systems, which were both installed between 44 m and 65 m below ground level, are used for geoelectrical multi-electrode measurements carried out automatically several times per day; the measurements are still ongoing. The whole system consisting of a vertical electrode system in a borehole and the measuring unit at ground level is called SAMOS (Saltwater Monitoring System). At both locations the data show a clear resistivity decrease that indicates the transition zone between freshwater and saltwater. The depth of the transition zone as well as the kind of resistivity decrease is very stable since 2010. Temporal changes are visible if single depths are considered. In 2015 Miriam Ibenthal used a vertical 2D density-dependent groundwater flow model to explain the long-term resistivity measurements and showed that the temporal changes at CLIWAT 2 (Ostland) could be explained by variations of the groundwater level, changing groundwater recharge rates and changing pumping rates of the nearby located drinking water supply wells.

2018, Rahman, Mohammad Azizur, González, Eva, Wiederhold, Helga, Deus, Nico, Elbracht, Jörg, Siemon, Bernhard, Szymkiewicz, Adam, Sadurski, A., Jaworska-Szulc, B.

In this study, interdisciplinary approaches are considered to characterize the coastal zone aquifer of the Elbe-Weser region in the North of Lower Saxony, Germany. Geological, hydrogeological, geochemical and geophysical information have been considered to analyze the current status of the aquifers. All the information collectively states that the salinity distribution in the subsurface is heterogeneous both horizontally and vertically. Early age flooding also contributed to this heterogeneity. No general classification of groundwater quality (according to some piper diagrams) could be identified. Helicopter-borne electro-magnetic data clearly show the presence of freshwater reserves below the sea near the west coast. Groundwater recharge largely happens in the moraine ridges (west side of the area) where both the surface elevation and the groundwater level are high. Consequently, submarine groundwater discharge occurs from the same place. All these information will facilitate to develop the planned density driven groundwater flow and transport model for the study area.

2015, Wallrabe, Ulrike, Brunne, Jens, Treffer, Alexander, Grunwald, Ruediger, Bellouard, Yves

We report on the design, fabrication and testing of novel types of low-dispersion axicons for the adaptive shaping of ultrashort laser pulses. An overview is given on the basic geometries and operating principles of our purely reflective adaptive MEMS-type devices based on thermal or piezoelectric actuation. The flexible formation of nondiffracting beams at pulse durations down to a few oscillations of the optical field enables new applications in optical communication, pulse diagnostics, laser-matter interaction and particle manipulation. As an example, we show first promising results of adaptive autocorrelation. The combination of excellent pulse transfer, self-reconstruction properties and propagation invariance of nondiffracting beams with an adaptive approach promises to extend the field of practical applications significantly.

2018, Wiederhold, Helga, Scheer, Wolfgang, Kirsch, Reinhard, Azizur Rahman, M., Ronczka, Mathias, Szymkiewicz, Adam, Sadurski, A., Jaworska-Szulc, B.

Climate change will result in rising sea level and, at least for the North Sea region, in rising groundwater table. This leads to a new balance at the fresh–saline groundwater boundary and a new distribution of saltwater intrusions with strong regional differentiations. These effects are investigated in several research projects funded by the European Union and the German Federal Ministry of Education and Research (BMBF). Objectives and some results from the projects TOPSOIL and go-CAM are presented in this poster.

2016, Janicka, Lucja, Stachlewska, Iwona S., Markowicz, Krzysztof M., Baars, Holger, Engelmann, Ronny, Heese, Birgit, Gross, Barry, Moshary, F., Arend, M.

This paper presents a preliminary study of aerosol optical properties of air-mass advected on 10th July 2013 from Canada above Warsaw, Poland, during the forest fire event that occurred in Quebec at the beginning of July 2013. The observations were conducted with use of the modern version of 8-channel PollyXT lidar capable of measuring at 3β+2α+2δ+VW and interpreted with available information from the MACC model, the CALIPSO and MODIS satellite sensors, the AERONET data products and the data gathered within the Poland-AOD network.

2018, Schneider, A., Zhao, H., Wolf, J., Logashenko, D., Reiter, S., Howahr, M., Eley, M., Gelleszun, M., Wiederhold, H., Szymkiewicz, Adam, Sadurski, A., Jaworska-Szulc, B.

A 3d regional density-driven flow model of a heterogeneous aquifer system at the German North Sea Coast is set up within the joint project NAWAK (“Development of sustainable adaption strategies for the water supply and distribution infrastructure on condition of climatic and demographic change”). The development of the freshwater-saltwater interface is simulated for three climate and demographic scenarios. Groundwater flow simulations are performed with the finite volume code d3f++ (distributed density driven flow) that has been developed with a view to the modelling of large, complex, strongly density-influenced aquifer systems over long time periods.

2016, Gerding, Michael, Baumgarten, Kathrin, Höffner, Josef, Lübken, Franz-Josef, Gross, Barry, Moshary, F., Arend, M.

Ground-based temperature measurements by lidar are an important tool for the understanding of long-term temperature changes as well as the propagation of gravity waves and tides. Though, mesospheric soundings are often limited to nighttime conditions due to the low signal-tonoise ratio during the day. We developed a daylight-capable RMR lidar for temperature soundings in the middle atmosphere. The influences of the narrowband detector on the calculated hydrostatic temperatures as well as their correction are described. The RMR lidar is complemented by a co-located resonance lidar. We present an example for tidal analyses and short-term variability of tidal amplitudes