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End date: 2016 × Start date: 2010 × DDC: 550 × Has files: Yes × Version: publishedVersion × Publisher: Göttingen : Copernicus × Subject: Middle atmosphere × WGL Institute: IAP ×

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Now showing 1 - 3 of 3
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    Validation of the radiation pattern of the Middle Atmosphere Alomar Radar System (MAARSY)
    (Göttingen : Copernicus, 2012) Renkwitz, T.; Singer, W.; Latteck, R.; Stober, G.; Rapp, M.
    In 2009/2010 the Leibniz-Institute of Atmospheric Physics (IAP) installed a new powerful VHF radar on the island Andøya in Northern Norway (69.30 N, 16.04 E). The Middle Atmosphere Alomar Radar System (MAARSY) allows studies with high spatial and temporal resolution in the troposphere/lower stratosphere and in the mesosphere/lower thermosphere of the Arctic atmosphere. The monostatic radar is operated at 53.5 MHz with an active phased array antenna consisting of 433 Yagi antennas. Each individual antenna is connected to its own transceiver with independent phase control and a scalable power output of up to 2 kW, which implies high flexibility of beam forming and beam steering. During the design phase of MAARSY several model studies have been carried out in order to estimate the radiation pattern for various combinations of beam forming and steering. However, parameters like mutual coupling, active impedance and ground parameters have an impact on the radiation pattern, but can hardly be measured. Hence, experiments need to be designed to verify the model results. For this purpose, the radar has occasionally been used in passive mode, monitoring the noise power received from both distinct cosmic noise sources like e.g. Cassiopeia A and Cygnus A, and the diffuse cosmic background noise. The analysis of the collected dataset enables us to verify beam forming and steering attempts. These results document the current status of the radar during its development and provide valuable information for further improvement.
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    Investigation of horizontal structures at mesospheric altitudes using coherent radar imaging
    (Göttingen : Copernicus, 2013) Sommer, S.; Stober, G.; Schult, C.; Zecha, M.; Latteck, R.
    The Middle Atmosphere Alomar Radar System (MAARSY) in Northern Norway (69.30°N, 16.04°E) was used to perform interferometric observations of Polar Mesosperic Summer Echoes (PMSE) in June 2012. Coherent Radar Imaging (CRI) using Capon's method was applied allowing a high spatial resolution. The algorithm was validated by simulation and trajectories of meteor head echoes. Both data sets show a good correspondence with the algorithm. Using this algorithm, the aspect sensitivity of PMSE was analysed in a case study, making use of the capability of CRI to resolve the pattern within the beam volume. No correction of the beam pattern was made yet. It was found in this case study, that no large variations in the scattering width and the scattering center occured apart from a very short period of time at the upper edge of the PMSE.
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    New experiments to validate the radiation pattern of the Middle Atmosphere Alomar Radar System (MAARSY)
    (Göttingen : Copernicus, 2013) Renkwitz, T.; Stober, G.; Latteck, R.; Singer, W.; Rapp, M.
    The Middle Atmosphere Alomar Radar System (MAARSY) is a monostatic radar with an active phased array antenna designed for studies of phenomena in the mesosphere and lower thermosphere. Its design in particular the flexible beam forming and steering capability makes it to a powerful instrument to perform observations with high angular and temporal resolution. The knowledge of the actual radiation pattern is crucial to configure and analyze experiments carried out with the radar. The simulated radiation pattern is evaluated by the observation of cosmic radio emissions which are compared to a Global Sky temperature Maps model consisting of the most recent, thorough and accurate radio astronomy surveys. Additionally to these passive receive-only experiments active two-way experiments are presented, which corroborate the findings of the passive experiments.